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Nathan Goodyear

Testosterone level in men with type 2 diabetes mellitus and related metabolic... - 0 views

www.ncbi.nlm.nih.gov/...PMC4364844

low T low Testosterone Diabetes Testosterone men male hormones metabolic syndrome

shared by Nathan Goodyear on 30 Mar 15 - No Cached
  • defined by consistent symptoms and signs of androgen deficiency, and an unequivocally low serum testosterone level
  • the threshold serum testosterone level below which adverse clinical outcomes occur in the general population is not known
  • most population-based studies use the serum testosterone level corresponding to the lower limit, quoted from 8.7 to 12.7 nmol/L, of the normal range for young Caucasian men as the threshold
    • Nathan Goodyear
      Nathan Goodyear on 31 Mar 15
       
      this equals 251 to 366 in serum Total Testosterone
  • ...57 more annotations...
  • Researchers tried to examine whether serum total or free testosterone would be a better/more reliable choice when studying the effect of testosterone. The results were mixed. Some reported significant associations of both serum total and free testosterone level with clinical parameters25, whereas others reported that only serum free testosterone26 or only serum total testosterone6 showed significant associations.
  • −0.124 nmol/L/year in serum total testosterone
    • Nathan Goodyear
      Nathan Goodyear on 31 Mar 15
       
      this equates to a 4 ng/dl decline annually in total Testosterone.
  • In experimental studies, androgen receptor knockout mice developed significant insulin resistance rapidly
  • In mouse models, testosterone promoted differentiation of pluripotent stem cells to the myogenic lineage
  • testosterone decreased insulin resistance by enhancing catecholamine induced lipolysis in vitro, and reducing lipoprotein lipase activity and triglyceride uptake in human abdominal tissue in vivo
  • by promoting lipolysis and myogenesis, testosterone might lead to improved insulin resistance
  • testosterone regulated skeletal muscle genes involved in glucose metabolism that led to decreased systemic insulin resistance
  • In the liver, hepatic androgen receptor signaling inhibited development of insulin resistance in mice
  • independent and inverse association of testosterone with hepatic steatosis shown in a cross-sectional study carried out in humans
  • In short, androgen improves insulin resistance by changing body composition and reducing body fat.
  • Although a low serum testosterone level could contribute to the development of obesity and type 2 diabetes through changes in body composition, obesity might also alter the metabolism of testosterone
  • In obese men, the peripheral conversion from testosterone to estrogen could attenuate the amplitude of luteinizing hormone pulses and centrally inhibit testosterone production
  • leptin, an adipokine, has been shown to be inversely correlated with serum testosterone level in men
  • Leydig cells expressed leptin receptors and leptin has been shown to inhibit testosterone secretion, suggesting a role of obesity and leptin in the pathogenesis of low testosterone
    • Nathan Goodyear
      Nathan Goodyear on 31 Mar 15
       
      So what is "unequivocal"?
  • Baltimore Longitudinal Study of Aging (BLSA) cohort made up of 3,565 middle-class, mostly Caucasian men from the USA, the incidence of low serum total testosterone increased from approximately 20% of men aged over 60 years, 30% over 70 years, to 50% over 80 years-of-age
  • 30–44% sex hormone binding globulin (SHBG)-bound testosterone and 54–68% albumin-bound testosterone
  • As the binding of testosterone to albumin is non-specific and therefore not tight, the sum of free and albumin-bound testosterone is named bioavailable testosterone, which reflects the hormone available at the cellular level
  • Serum total testosterone is composed of 0.5–3.0% of free testosterone unbound to plasma proteins
  • alterations in SHBG concentration might affect total serum testosterone level without altering free or bioavailable testosterone
  • listed in Table​T
  • A significant, independent and longitudinal effect of age on testosterone has been observed with an average change of −0.124 nmol/L/year in serum total testosterone28. The same trend has been shown in Europe and Australia
  • Asian men residing in HK and Japan, but not those living in the USA, had 20% higher serum total testosterone than in Caucasians living in the USA, as shown in a large multinational observational prospective cohort of the Osteoporotic Fractures in Men Study
  • subjects with chronic diseases consistently had a 10–15% lower level compared with age-matched healthy subjects
  • In Caucasians, the mean serum total testosterone level for men in large epidemiological studies has been reported to range from 15.1 to 16.6 nmol/L
  • Asians, higher values, ranging from 18.1 to 19.1 nmol/L, were seen in Korea and Japan
  • Chinese middle-aged men reported a similar mean serum testosterone level of 17.1 nmol/L in 179 men who had a family history of type 2 diabetes and 17.8 nmol/L in 128 men who had no family history of type 2 diabetes
  • The reduction of total testosterone was 0.4% per year in both groups
  • HK involving a cohort of 1,489 community-dwelling men with a mean age of 72 years, a mean serum total testosterone of 19.0 nmol/L was reported
  • pro-inflammatory factors, such as tumor necrosis factor-α in the testes, could locally inhibit testosterone biosynthesis in Leydig cells47, and testosterone treatment in men was shown to reduce the level of tumor necrosis factor-α
  • In Asians, a genetic deletion polymorphism of uridine diphosphate-glucuronosyltransferase UGT2B17 was associated with reduced androgen glucuronidation. This resulted in higher level of active androgen in Asians as compared to Caucasians, as Caucasians' androgen would be glucuronidated into inactive forms faster.
  • Compared with Caucasians, the frequency of this deletion polymorphism of UGT2B17 was 22-fold higher in Asian subjects
  • Other researchers have suggested that environmental, but not genetic, factors influenced serum total testosterone
  • The basal and ligand-induced activity of the AR is inversely associated with the length of the CAG repeat chain
  • In the European Male Aging Study, increased estrogen/androgen ratio in association with longer AR CAG repeat was observed
  • a smaller number of AR CAG repeat had been shown to be associated with benign prostate hypertrophy and faster prostate growth during testosterone treatment
  • In India, men with CAG ≤19 had increased risk of prostate cancer
  • the odds of having a short CAG repeat (≤17) were substantially higher in patients with lymph node-positive prostate cancer than in those with lymph node-negative disease or in the general population
  • assessing the polymorphism at the AR level could be a potential tool towards individualized assessment and treatment of hypogonadism.
  • In elderly men, there was reduced testicular response to gonadotropins with suppressed and altered pulsatility of the hypothalamic pulse generator
  • a significant, independent and longitudinal effect of age on serum total testosterone level had been observed
  • A significant graded inverse association between serum testosterone level and insulin levels independent of age has also been reported in Caucasian men
  • Low testosterone is commonly associated with a high prevalence of MES
  • most studies showed that changes in serum testosterone level led to changes in body composition, insulin resistance and the presence of MES, the reverse might also be possible
  • MES predicted a 2.6-fold increased risk of development of low serum testosterone level independent of age, smoking and other potential confounders
  • Other prospective studies have shown that development of MES accelerated the age-related decline in serum testosterone level
  • In men with type 2 diabetes, changes in serum testosterone level over time correlated inversely with changes in insulin resistance
  • weight loss by either diet control or bariatric surgery led to a substantial increase in total testosterone, especially in morbidly obese men, and the rise in serum testosterone level was proportional to the amount of weight lost
  • To date, published clinical trials are small, of short duration and often used pharmacological, not physiological, doses of testosterone
  • In the population-based Osteoporotic Fractures in Men Study cohort from Sweden, men in the highest quartile of serum testosterone level had the lowest risk of cardiovascular events compared with men in the other three quartiles (hazard ratio [HR] 0.70
  • low serum total testosterone was associated with a significant fourfold higher risk of cardiovascular events when comparing men from the lowest testosterone tertile with those in the highest tertile
  • Shores et al. were the first to report that low serum testosterone level, including both serum total and free testosterone, was associated with increased mortality
  • low serum total testosterone predicted increased risk of cardiovascular mortality with a HR of 1.38
  • low serum total testosterone increased all-cause (HR 1.35, 95% CI 1.13–1.62, P < 0.001) and cardiovascular mortality (HR 1.25
  • European Association for the Study of Diabetes 2013 suggested there was an inverse relationship between serum testosterone level and acute myocardial infarction
  • Diabetic men in the highest quartile of serum total testosterone had a significantly reduced risk of acute MI when compared with those in the lower quartiles
  • serum total testosterone level in the middle two quartiles at baseline predicted reduced incidence of death compared with having the highest and lowest levels
  • Nathan Goodyear on 30 Mar 15
     
    Nice review of Testosterone levels and some of the evidence linking Diabetes with low T.  However, the conclusion by the authors regarding what is causing the low T in men with Diabetes is baffling.  The literature does not point to one cause, it is clearly multifactorial--obesity, inflammation, high aromatase activity...I would suggest the authors continue their readings in the manner.
Nathan Goodyear

Testosterone and the Cardiovascular System: A Comprehensive Review of the Clinical Lite... - 0 views

jaha.ahajournals.org/...e000272.full

Testosterone men male cardiovascular disease low T

shared by Nathan Goodyear on 20 Nov 13 - No Cached
  • Low endogenous bioavailable testosterone levels have been shown to be associated with higher rates of all‐cause and cardiovascular‐related mortality.39,41,46–47 Patients suffering from CAD,13–18 CHF,137 T2DM,25–26 and obesity27–28
  • have all been shown to have lower levels of endogenous testosterone compared with those in healthy controls. In addition, the severity of CAD15,17,29–30 and CHF137 correlates with the degree of testosterone deficiency
  • In patients with CHF, testosterone replacement therapy has been shown to significantly improve exercise tolerance while having no effect on LVEF
  • ...66 more annotations...
  • testosterone therapy causes a shift in the skeletal muscle of CHF patients toward a higher concentration of type I muscle fibers
  • Testosterone replacement therapy has also been shown to improve the homeostatic model of insulin resistance and hemoglobin A1c in diabetics26,68–69 and to lower the BMI in obese patients.
  • Lower levels of endogenous testosterone have been associated with longer duration of the QTc interval
  • testosterone replacement has been shown to shorten the QTc interval
  • negative correlation has been demonstrated between endogenous testosterone levels and IMT of the carotid arteries, abdominal aorta, and thoracic aorta
  • These findings suggest that men with lower levels of endogenous testosterone may be at a higher risk of developing atherosclerosis.
  • Current guidelines from the Endocrine Society make no recommendations on whether patients with heart disease should be screened for hypogonadism and do not recommend supplementing patients with heart disease to improve survival.
  • The Massachusetts Male Aging Study also projects ≈481 000 new cases of hypogonadism annually in US men within the same age group
  • since 1993 prescriptions for testosterone, regardless of the formulation, have increased nearly 500%
  • Testosterone levels are lower in patients with chronic illnesses such as end‐stage renal disease, human immunodeficiency virus, chronic obstructive pulmonary disease, type 2 diabetes mellitus (T2DM), obesity, and several genetic conditions such as Klinefelter syndrome
  • A growing body of evidence suggests that men with lower levels of endogenous testosterone are more prone to develop CAD during their lifetimes
  • There are 2 major potential confounding factors that the older studies generally failed to account for. These factors are the subfraction of testosterone used to perform the analysis and the method used to account for subclinical CAD.
  • The biologically inactive form of testosterone is tightly bound to SHBG and is therefore unable to bind to androgen receptors
  • The biologically inactive fraction of testosterone comprises nearly 68% of the total testosterone in human serum
  • The biologically active subfraction of testosterone, also referred to as bioavailable testosterone, is either loosely bound to albumin or circulates freely in the blood, the latter referred to as free testosterone
  • It is estimated that ≈30% of total serum testosterone is bound to albumin, whereas the remaining 1% to 3% circulates as free testosterone
  • it can be argued that using the biologically active form of testosterone to evaluate the association with CAD will produce the most reliable results
  • English et al14 found statistically significant lower levels of bioavailable testosterone, free testosterone, and free androgen index in patients with catheterization‐proven CAD compared with controls with normal coronary arteries
  • patients with catheterization‐proven CAD had statistically significant lower levels of bioavailable testosterone
  • In conclusion, existing evidence suggests that men with CAD have lower levels of endogenous testosterone,13–18 and more specifically lower levels of bioavailable testosterone
  • low testosterone levels are associated with risk factors for CAD such as T2DM25–26 and obesity
  • In a meta‐analysis of these 7 population‐based studies, Araujo et al41 showed a trend toward increased cardiovascular mortality associated with lower levels of total testosterone, but statistical significance was not achieved (RR, 1.25
  • the authors showed that a decrease of 2.1 standard deviations in levels of total testosterone was associated with a 25% increase in the risk of cardiovascular mortality
  • the relative risk of all‐cause mortality in men with lower levels of total testosterone was calculated to be 1.35
  • higher risk of cardiovascular mortality is associated with lower levels of bioavailable testosterone
  • Existing evidence seems to suggest that lower levels of endogenous testosterone are associated with higher rates of all‐cause mortality and cardiovascular mortality
  • studies have shown that lower levels of endogenous bioavailable testosterone are associated with higher rates of all‐cause and cardiovascular mortality
  • It may be possible that using bioavailable testosterone to perform mortality analysis will yield more accurate results because it prevents the biologically inactive subfraction of testosterone from playing a potential confounding role in the analysis
  • The earliest published material on this matter dates to the late 1930s
  • the concept that testosterone replacement therapy improves angina has yet to be proven wrong
  • In more recent studies, 3 randomized, placebo‐controlled trials demonstrated that administration of testosterone improves myocardial ischemia in men with CAD
  • The improvement in myocardial ischemia was shown to occur in response to both acute and chronic testosterone therapy and seemed to be independent of whether an intravenous or transdermal formulation of testosterone was used.
  • testosterone had no effect on endothelial nitric oxide activity
  • There is growing evidence from in vivo animal models and in vitro models that testosterone induces coronary vasodilation by modulating the activity of ion channels, such as potassium and calcium channels, on the surface of vascular smooth muscle cells
  • Experimental studies suggest that the most likely mechanism of action for testosterone on vascular smooth muscle cells is via modulation of action of non‐ATP‐sensitive potassium ion channels, calcium‐activated potassium ion channels, voltage‐sensitive potassium ion channels, and finally L‐type calcium ion channels
  • Corona et al confirmed those results by demonstrating that not only total testosterone levels are lower among diabetics, but also the levels of free testosterone and SHBG are lower in diabetic patients
  • Laaksonen et al65 followed 702 Finnish men for 11 years and demonstrated that men in the lowest quartile of total testosterone, free testosterone, and SHBG were more likely to develop T2DM and metabolic syndrome.
  • Vikan et al followed 1454 Swedish men for 11 years and discovered that men in the highest quartile of total testosterone were significantly less likely to develop T2DM
  • authors demonstrated a statistically significant increase in the incidence of T2DM in subjects receiving gonadotropin‐releasing hormone antagonist therapy. In addition, a significant increase in the rate of myocardial infarction, stroke, sudden cardiac death, and development of cardiovascular disease was noted in patients receiving antiandrogen therapy.67
  • Several authors have demonstrated that the administration of testosterone in diabetic men improves the homeostatic model of insulin resistance, hemoglobin A1c, and fasting plasma glucose
  • Existing evidence strongly suggests that the levels of total and free testosterone are lower among diabetic patients compared with those in nondiabetics
  • insulin seems to be acting as a stimulant for the hypothalamus to secret gonadotropin‐releasing hormone, which consequently results in increased testosterone production. It can be argued that decreased stimulation of the hypothalamus in diabetics secondary to insulin deficiency could result in hypogonadotropic hypogonadism
  • BMI has been shown to be inversely associated with testosterone levels
  • This interaction may be a result of the promotion of lipolysis in abdominal adipose tissue by testosterone, which may in turn cause reduced abdominal adiposity. On the other hand, given that adipose tissue has a higher concentration of the enzyme aromatase, it could be that increased adipose tissue results in more testosterone being converted to estrogen, thereby causing hypogonadism. Third, increased abdominal obesity may cause reduced testosterone secretion by negatively affecting the hypothalamus‐pituitary‐testicular axis. Finally, testosterone may be the key factor in activating the enzyme 11‐hydroxysteroid dehydrogenase in adipose tissue, which transforms glucocorticoids into their inactive form.
  • increasing age may alter the association between testosterone and CRP. Another possible explanation for the association between testosterone level and CRP is central obesity and waist circumference
  • Bai et al have provided convincing evidence that testosterone might be able to shorten the QTc interval by augmenting the activity of slowly activating delayed rectifier potassium channels while simultaneously slowing the activity of L‐type calcium channels
  • consistent evidence that supplemental testosterone shortens the QTc interval.
  • Intima‐media thickness (IMT) of the carotid artery is considered a marker for preclinical atherosclerosis
  • Studies have shown that levels of endogenous testosterone are inversely associated with IMT of the carotid artery,126–128,32,129–130 as well as both the thoracic134 and the abdominal aorta
  • 1 study has demonstrated that lower levels of free testosterone are associated with accelerated progression of carotid artery IMT
  • another study has reported that decreased levels of total and bioavailable testosterone are associated with progression of atherosclerosis in the abdominal aorta
  • These findings suggest that normal physiologic testosterone levels may help to protect men from the development of atherosclerosis
  • Czesla et al successfully demonstrated that the muscle specimens that were exposed to metenolone had a significant shift in their composition toward type I muscle fibers
  • Type I muscle fibers, also known as slow‐twitch or oxidative fibers, are associated with enhanced strength and physical capability
  • It has been shown that those with advanced CHF have a higher percentage of type II muscle fibers, based on muscle biopsy
  • Studies have shown that men with CHF suffer from reduced levels of total and free testosterone.137 It has also been shown that reduced testosterone levels in men with CHF portends a poor prognosis and is associated with increased CHF mortality.138 Reduced testosterone has also been shown to correlate negatively with exercise capacity in CHF patients.
  • Testosterone replacement therapy has been shown to significantly improve exercise capacity, without affecting LVEF
  • the results of the 3 meta‐analyses seem to indicate that testosterone replacement therapy does not cause an increase in the rate of adverse cardiovascular events
  • Data from 3 meta‐analyses seem to contradict the commonly held belief that testosterone administration may increase the risk of developing prostate cancer
  • One meta‐analysis reported an increase in all prostate‐related adverse events with testosterone administration.146 However, when each prostate‐related event, including prostate cancer and a rise in PSA, was analyzed separately, no differences were observed between the testosterone group and the placebo group
  • the existing data from the 3 meta‐analyses seem to indicate that testosterone replacement therapy does not increase the risk of adverse cardiovascular events
  • the authors correctly point out the weaknesses of their study which include retrospective study design and lack of randomization, small sample size at extremes of follow‐up, lack of outcome validation by chart review and poor generalizability of the results given that only male veterans with CAD were included in this study
    • Nathan Goodyear
      Nathan Goodyear on 04 Dec 13
       
      The authors here present Total Testosterone as a "confounding" value
    • Nathan Goodyear
      Nathan Goodyear on 09 Dec 13
       
      This would be HSD-II
  • the studies that failed to find an association between testosterone and CRP used an older population group
  • low testosterone may influence the severity of CAD by adversely affecting the mediators of the inflammatory response such as high‐sensitivity C‐reactive protein, interleukin‐6, and tumor necrosis factor–α
  • Nathan Goodyear on 20 Nov 13
     
    Good review of Testosterone and CHD.  Low T is associated with increased all cause mortality and cardiovascular mortality, CAD, CHF, type II diabetes, obesity, increased IMT,  increased severity of CAD and CHF.  Testosterone replacement in men with low T has been shown to improve exercise tolerance in CHF, improve insulin resistance, improve HgbA1c and lower BMI in the obese.
Nathan Goodyear

Nature Clinical Practice Endocrinology & Metabolism | Testosterone and ill-health in ag... - 0 views

www.nature.com/...ncpendmet1050.html

low T Testosterone health men male hormone hormones metabolic syndrome metabolic syndrome MetS insulin resistance diabetes aging

shared by Nathan Goodyear on 03 Mar 14 - No Cached
  • Levels of total and bioavailable testosterone and SHBG were reported to be inversely correlated with the prevalence of the metabolic syndrome in men aged 40–80 years
  • as were total testosterone and SHBG in men aged 65–96 years
  • and in a cross-sectional analysis of a large cohort of non-diabetic men aged 70–89 years
  • ...18 more annotations...
  • In longitudinal studies, decreased levels of total testosterone and SHBG predicted an increased incidence of metabolic syndrome in nonobese men
  • Free testosterone level is not associated with the prevalence of metabolic syndrome in middle-aged and older men
  • Levels of free, bioavailable and total testosterone are lower in men with T2DM than in age-matched controls,34, 35 and decreased total testosterone level predicts incident T2DM in middle-aged men.
  • men with T2DM commonly have low total or free testosterone levels
  • Total, bioavailable and free testosterone levels are inversely correlated with fasting insulin level and insulin resistance in middle-aged men without T2DM
  • total testosterone is positively correlated with insulin sensitivity in men with normal or impaired glucose tolerance or T2DM
  • low SHBG level is more strongly associated with metabolic syndrome than low total testosterone in aging men
  • the recognized association between low SHBG level and insulin resistance
  • Low levels of SHBG are also associated with smaller, denser LDL-cholesterol molecules in nondiabetic men,58 and were found to predict increased cardiovascular disease mortality in one study of older men
  • Low levels of SHBG might reflect obesity, insulin resistance and overall poor health
  • Compared with those who have normal testosterone levels, men aged 40 years or more with total testosterone levels <9.8 nmol/l or elevated LH level have greater CIMT
  • In men aged 73–94 years, total testosterone was inversely correlated with CIMT
  • a prospective analysis of men aged 73–91 years, progression of CIMT was not related to total testosterone level, but it was inversely related to free testosterone level
  • A study of men aged 55 years or more found that those with total and bioavailable testosterone levels in the highest tertile had a lower risk of severe aortic atherosclerosis (detected by radiography as abdominal aortic calcification) than those with the lowest testosterone levels.
  • a large study of men aged 69–80 years, those with total or free testosterone in the lowest quartile had increased odds of lower-extremity peripheral arterial disease
  • the possibility of reverse causation has to be considered, as systemic illness can result in decreased testosterone levels
  • previous case–control studies and longitudinal studies have failed to identify low testosterone levels as strong predictors of clinically significant coronary disease
  • Reviews of trials on testosterone therapy in men with either low or low-to-normal testosterone levels have not shown consistent beneficial effects either on lipid profiles or on actual cardiovascular events.24, 54, 55 These trials, however, have not been designed or powered to detect treatment-related differences in cardiovascular outcome
  • Nathan Goodyear on 03 Mar 14
     
    Declining Testosterone or low Testosterone is clearly associated with poor health in men.   Very nice review of the association between low Testosterone and metabolic dysfunction.  Low T is associated with increased metabolic syndrome, Diabetes, weight gain, insulin resistance...
Nathan Goodyear

Clinical experience with intravenous administration of ascorbic acid: achievable levels... - 0 views

www.ncbi.nlm.nih.gov/...PMC3751545

IV vitamin C dosing ascorbic acid inflammation disease cancer IV vitamin C intravenous vitamin C IV intravenous vitamin C vitamin C CRP therapy treatment alternative

shared by Nathan Goodyear on 26 Aug 14 - No Cached
  • Patients with higher tumor markers are likely to have higher tumor burden, higher oxidative stress and, therefore, are more likely to have lower post IVC plasma levels.
  • Our data also showed that cancer patients with metastasis tend to have lower post-IVC vitamin C levels than those without metastasis
  • Lower peak plasma concentrations are obtained in cancer patients than in healthy subjects. Cancer patients who are deficient in vitamin C prior to therapy tend to achieve lower plasma levels post infusion.
  • ...25 more annotations...
  • Patients with higher inflammation or tumor burdens, as measured by CRP levels or tumor antigen levels, tend to show lower peak plasma ascorbate levels after IVC.
  • Patients with metastatic tumors tend to achieve lower post infusion plasma ascorbate levels than those with localized tumors.
  • Meta-analyses of clinical studies involving cancer and vitamins also conclude that antioxidant supplementation does not interfere with the efficacy of chemotherapeutic regiments
  • Most of the prostate cancer patients studied, 75±19% (95% confidence), showed reductions in PSA levels during the course of their IVC therapy
  • Laboratory studies suggest that, at high concentrations, ascorbate does not interfere with chemotherapy or irradiation and may enhance efficacy in some situations
  • Cameron and Pauling observed fourfold survival times in terminal cancer patients treated with intravenous ascorbate infusions followed by oral supplementation
  • The inflammatory microenvironment of cancer cells leads to increasing oxidative stress, which apparently depletes vitamin C, resulting in lower plasma ascorbate concentrations in blood samples post IVC infusion. Another explanation for this finding may be that cancers are themselves more metabolically active in their uptake of vitamin C, causing subjects to absorb more of the vitamin, and as a results show lower plasma ascorbate concentrations in blood post IVC infusion.
  • patients with severely elevated CRP levels attain plasma ascorbate concentrations after IVC infusions that are only 65% of those attained for subjects with normal CRP levels
  • The finding of decreased plasma ascorbate levels in cancer patients may relate to the molecular structure of ascorbic acid; in particular, the similarity of its oxidized form, dihydroascorbic acid, to glucose
  • Since tumor have increased requirement for glucose [67], transport of dehydroascorbate into the cancer cells via glucose transport molecules and ascorbate through sodium-dependent transporter may be elevated
  • Increased accumulation of ascorbic acid in the tumor site was supported by measurements of the level of ascorbic acid in tumors in animal experiments
  • patients with advanced malignancies may have lower level of ascorbic acid in tissue, creating a higher demand for the vitamin C
  • IVC therapy appears to reduce CRP levels in cancer patients.
  • CRP concentrations directly correlate with disease activity in many cases and can contribute to disease progression through a range of pro-inflammatory properties.
  • Being an exquisitely sensitive marker of systemic inflammation and tissue damage, CRP is very useful in screening for organic disease and monitoring treatment responses
  • ncreases in CRP concentrations have been associated with poorer prognosis of survival in cancer patients, particularly with advance disease independent of tumor stage
  • Regarding inflammation, 73±13% of subjects (95% confidence) showed a reduction in CRP levels during therapy. This was an even more dramatic 86±13% (95% confidence) in subjects who started therapy with CRP levels above 10 mg/L
  • patients treated by IVC with follow-up several year showed that suppression of inflammation in cancer patients by high-dose IVC is feasible and potentially beneficial
  • Inflammation is a marker of high cancer risk, and poor treatment outcome
  • The subjects with highly elevated CRP concentrations have a three-fold elevation “all-cause” mortality risk and a twenty-eight fold increase in cancer mortality risk
  • cancer patients may need higher doses to achieve a given plasma concentration.
  • patients with lower vitamin C levels may see more distribution of intravenously administered ascorbate into tissues and thus attain less in plasma.
  • When treating patients with IVC, the first treatment likely serves to replenish depleted tissue stores, if those subjects were vitamin C deficient at the beginning of the treatment. Then, in subsequent treatments, with increasing doses, higher plasma concentrations can be attained. On-going treatments serve to progressively reduce oxidative stress in cancer patients.
  • large doses given intravenously may result in maximum plasma concentrations of roughly 30 mM, a level that has been shown to be sufficient for preferential cytotoxicity against cancer cells
  • oral intake of vitamin C exceeded 200 mg administered once daily, it was difficult to increase plasma and tissue concentrations above roughly 200 μM.
  • Nathan Goodyear on 26 Aug 14
     
    Great review on the use of IV vitamin C in cancer and to reduce inflammation.  The article does a great job of discussing the mechanism of vitamin C therapy in cancer as well as the proposed reasons for low vitamin C in cancer patients.  The study also highlights the obstacles to rise in vitamin C levels post IV vitamin C in cancer patients.
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https://www.fitspresso-co.com/ - 0 views

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  • fitspresso on 27 Sep 23
     
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Nathan Goodyear

Testosterone Deficiency, Cardiac Health, and Older Men - 0 views

www.hindawi.com/...143763

low T Testosterone obesity type II diabetes diabetes health wellness metabolic syndrome lipids cholesterol hypogonadism TDS testicular dysgenesis syndrome men male hormone hormones prostate cancer

shared by Nathan Goodyear on 12 May 14 - No Cached
  • Studies have shown pharmacological doses of testosterone to relax coronary arteries when injected intraluminally [39] and to produce modest but consistent improvement in exercise-induced angina and reverse associated ECG changes [40]. The mechanism of action is via blockade of calcium channels with effect of similar magnitude to nifedipine
    • Nathan Goodyear
      Nathan Goodyear on 12 May 14
       
      This directly refutes the recent studies (3) that Testosterone therapy increases cardiovascular events.
    • Nathan Goodyear
      Nathan Goodyear on 13 May 14
       
      Testosterone acts as a calcium channel blocker inducing vasodilation.
  • men with chronic stable angina pectoris, the ischaemic threshold increased after 4 weeks of TRT and a recent study demonstrates improvement continuing beyond 12 months [
  • Exercise capacity in men with chronic heart failure increased after 12 weeks
  • ...36 more annotations...
  • Studies have shown an inverse relationship between serum testosterone and fasting blood glucose and insulin levels
  • Medications such as chronic analgesics, anticonvulsants, 5ARIs, and androgen ablation therapy are associated with increased risk of testosterone deficiency and insulin resistance
  • Women with T2D or metabolic syndrome characteristically have low SHBG and high free testosterone
    • Nathan Goodyear
      Nathan Goodyear on 12 May 14
       
      This stands in polar opposite of that with men.
  • Hypogonadism is a common feature of the metabolic syndrome
  • The precise interaction between insulin resistance, visceral adiposity, and hypogonadism is, as yet, unclear but the important mechanisms are through increased aromatase production, raised leptin levels, and increase in inflammatory kinins
  • levels of testosterone are reduced in proportion to degree of obesity
  • Men should be encouraged to combine aerobic exercise with strength training. As muscle increases, glucose will be burned more efficiently and insulin levels will fall. A minimum of 30 minutes exercise three times weekly should be advised
  • Testosterone increases levels of fast-twitch muscle fibres
  • By increasing testosterone, levels of type 2 fibres increase and glucose burning improves
  • Weight loss will increase levels of testosterone
  • studies now clearly show that low testosterone leads to visceral obesity and metabolic syndrome and is also a consequence of obesity
  • In the case of MMAS [43], a baseline total testosterone of less than 10.4 nmol/L was associated with a greater than 4-fold incidence of type 2 diabetes over the next 9 years
  • There is high level evidence that TRT improves insulin resistance
  • Low testosterone predicts increased mortality and testosterone therapy improves survival in 587 men with type 2 diabetes
  • A similar retrospective US study involved 1031 men with 372 on TRT. The cumulative mortality was 21% in the untreated group versus 10% ( ) in the treated group with the greatest effect in younger men and those with type 2 diabetes
  • the presence of ED has been shown to be an independent risk factor, particularly in hypogonadal men, increasing the risk of cardiac events by over 50%
  • A recent online publication on ischaemic heart disease mortality in men concluded optimal androgen levels are a biomarker for survival
  • inverse associations between low TT or FT (Table 2) and the severity of CAD
  • A recent 10 year study from Western Australia involving 3690 men followed up from 2001–2010 concluded that TT and FT levels in the normal range were associated with decreased all-cause and cardiovascular mortality, for the first time suggesting that both low and DHT are associated with all-cause mortality and higher levels of DHT reduced cardiovascular risk
  • TDS is associated with increased cardiovascular and all-cause mortality
  • The effect of treatment with TRT reduced the mortality rate of treated cohort (8.4%) to that of the eugonadal group whereas the mortality for the untreated remained high at 19.2%
  • hypogonadal men had slightly increased triglycerides and HDL
  • Men with angiographically proven CAD (coronary artery disease) have significantly lower testosterone levels [29] compared to controls ( ) and there was a significant inverse relationship between the degree of CAD and TT (total testosterone) levels
  • TRT has also been shown to reduce fibrinogen to levels similar to fibrates
  • men treated with long acting testosterone showed highly significant reductions in TC, LDL, and triglycerides with increase in HDL, associated with significant reduction in weight, BMI, and visceral fat
  • Low androgen levels are associated with an increase in inflammatory markers
  • In the Moscow study, C-reactive protein was reduced by TRT at 30 weeks versus placebo
  • In some studies, a decline in diastolic blood pressure has been observed, after 3–9 months [24, 26] and in systolic blood pressure
  • A decline was noted in IL6 and TNF-alpha
  • No studies to date show an increase in LUTS/BPH symptoms with higher serum testosterone levels
  • TRT has been shown to upregulate PDE5 [65] and enhance the effect of PDE5Is (now an accepted therapy for both ED and LUTS), it no longer seems logical to advice avoidance of TRT in men with mild to moderate BPH.
    • Nathan Goodyear
      Nathan Goodyear on 12 May 14
       
      What about just starting with normalization of Testosterone levels first.
  • Several meta-analyses have failed to show a link between TRT and development of prostate cancer [66] but some studies have shown a tendency for more aggressive prostate cancer in men with low testosterone
    • Nathan Goodyear
      Nathan Goodyear on 12 May 14
       
      And if one would have looked at their estrogen levels, I guarantee they would have been found to be elevated.
  • low bioavailable testosterone and high SHBG were associated with a 4.9- and 3.2-fold risk of positive biopsy
  • Current EAU, ISSAM, and BSSM guidance [1, 2] is that there is “no evidence TRT is associated with increased risk of prostate cancer or activation of subclinical cancer.”
  • Men with prostate cancer, treated with androgen deprivation, develop an increase of fat mass with an altered lipid profile
  • Erectile dysfunction is an established marker for future cardiovascular risk and the major presenting symptom leading to a diagnosis of low testosterone
Nathan Goodyear

Testosterone and glucose metabolism in men: current concepts and controversies - 0 views

joe.endocrinology-journals.org/...R37.full

Low T Testosterone metabolic syndrome MetS Diabetes men male glucose hormone hormones g

shared by Nathan Goodyear on 04 Feb 14 - No Cached
  • Around 50% of ageing, obese men presenting to the diabetes clinic have lowered testosterone levels relative to reference ranges based on healthy young men
  • The absence of high-level evidence in this area is illustrated by the Endocrine Society testosterone therapy in men with androgen deficiency clinical practice guidelines (Bhasin et al. 2010), which are appropriate for, but not specific to men with metabolic disorders. All 32 recommendations made in these guidelines are based on either very low or low quality evidence.
  • A key concept relates to making a distinction between replacement and pharmacological testosterone therapy
  • ...59 more annotations...
  • The presence of symptoms was more closely linked to increasing age than to testosterone levels
  • Findings similar to type 2 diabetes were reported for men with the metabolic syndrome, which were associated with reductions in total testosterone of −2.2 nmol/l (95% CI −2.41 to 1.94) and in free testosterone
  • low testosterone is more predictive of the metabolic syndrome in lean men
  • Cross-sectional studies uniformly show that 30–50% of men with type 2 diabetes have lowered circulating testosterone levels, relative to references based on healthy young men
  • In a recent cross-sectional study of 240 middle-aged men (mean age 54 years) with either type 2 diabetes, type 1 diabetes or without diabetes (Ng Tang Fui et al. 2013b), increasing BMI and age were dominant drivers of low total and free testosterone respectively.
  • both diabetes and the metabolic syndrome are associated with a modest reduction in testosterone, in magnitude comparable with the effect of 10 years of ageing
  • In a cross-sectional study of 490 men with type 2 diabetes, there was a strong independent association of low testosterone with anaemia
  • In men, low testosterone is a marker of poor health, and may improve our ability to predict risk
    • Nathan Goodyear
      Nathan Goodyear on 04 Feb 14
       
      probably the most important point made in this article
  • low testosterone identifies men with an adverse metabolic phenotype
  • Diabetic men with low testosterone are significantly more likely to be obese or insulin resistant
  • increased inflammation, evidenced by higher CRP levels
  • Bioavailable but not free testosterone was independently predictive of mortality
  • It remains possible that low testosterone is a consequence of insulin resistance, or simply a biomarker, co-existing because of in-common risk factors.
  • In prospective studies, reviewed in detail elsewhere (Grossmann et al. 2010) the inverse association of low testosterone with metabolic syndrome or diabetes is less consistent for free testosterone compared with total testosterone
  • In a study from the Framingham cohort, SHBG but not testosterone was prospectively and independently associated with incident metabolic syndrome
  • low SHBG (Ding et al. 2009) but not testosterone (Haring et al. 2013) with an increased risk of future diabetes
  • In cross-sectional studies of men with (Grossmann et al. 2008) and without (Bonnet et al. 2013) diabetes, SHBG but not testosterone was inversely associated with worse glycaemic control
  • SHBG may have biological actions beyond serving as a carrier protein for and regulator of circulating sex steroids
  • In men with diabetes, free testosterone, if measured by gold standard equilibrium dialysis (Dhindsa et al. 2004), is reduced
    • Nathan Goodyear
      Nathan Goodyear on 04 Feb 14
       
      expensive, laborious process filled with variables
  • Low free testosterone remains inversely associated with insulin resistance, independent of SHBG (Grossmann et al. 2008). This suggests that the low testosterone–dysglycaemia association is not solely a consequence of low SHBG.
  • Experimental evidence reviewed below suggests that visceral adipose tissue is an important intermediate (rather than a confounder) in the inverse association of testosterone with insulin resistance and metabolic disorders.
  • testosterone promotes the commitment of pluripotent stem cells into the myogenic lineage and inhibits their differentiation into adipocytes
  • testosterone regulates the metabolic functions of mature adipocytes (Xu et al. 1991, Marin et al. 1995) and myocytes (Pitteloud et al. 2005) in ways that reduce insulin resistance.
  • Pre-clinical evidence (reviewed in Rao et al. (2013)) suggests that at the cellular level, testosterone may improve glucose metabolism by modulating the expression of the glucose-transported Glut4 and the insulin receptor, as well as by regulating key enzymes involved in glycolysis.
  • More recently testosterone has been shown to protect murine pancreatic β cells against glucotoxicity-induced apoptosis
  • Interestingly, a reciprocal feedback also appears to exist, given that not only chronic (Cameron et al. 1990, Allan 2013) but also, as shown more recently (Iranmanesh et al. 2012, Caronia et al. 2013), acute hyperglycaemia can lower testosterone levels.
  • There is also evidence that testosterone regulates insulin sensitivity directly and acutely
  • In men with prostate cancer commencing androgen deprivation therapy, both total as well as, although not in all studies (Smith 2004), visceral fat mass increases (Hamilton et al. 2011) within 3 months
  • More prolonged (>12 months) androgen deprivation therapy has been associated with increased risk of diabetes in several large observational registry studies
  • Testosterone has also been shown to reduce the concentration of pro-inflammatory cytokines in some, but not all studies, reviewed recently in Kelly & Jones (2013). It is not know whether this effect is independent of testosterone-induced changes in body composition.
  • the observations discussed in this section suggest that it is the decrease in testosterone that causes insulin resistance and diabetes. One important caveat remains: the strongest evidence that low testosterone is the cause rather than consequence of insulin resistance comes from men with prostate cancer (Grossmann & Zajac 2011a) or biochemical castration, and from mice lacking the androgen receptor.
  • Several large prospective studies have shown that weight gain or development of type 2 diabetes is major drivers of the age-related decline in testosterone levels
  • there is increasing evidence that healthy ageing by itself is generally not associated with marked reductions in testosterone
  • Circulating testosterone, on an average 30%, is lower in obese compared with lean men
  • increased visceral fat is an important component in the association of low testosterone and insulin resistance
  • The vast majority of men with metabolic disorders have functional gonadal axis suppression with modest reductions in testosterone levels
  • obesity is a dominant risk factor
  • men with Klinefelter syndrome have an increased risk of metabolic disorders. Interestingly, greater body fat mass is already present before puberty
  • Only 5% of men with type 2 diabetes have elevated LH levels
  • inhibition of the gonadal axis predominantly takes place in the hypothalamus, especially with more severe obesity
  • Metabolic factors, such as leptin, insulin (via deficiency or resistance) and ghrelin are believed to act at the ventromedial and arcuate nuclei of the hypothalamus to inhibit gonadotropin-releasing hormone (GNRH) secretion from GNRH neurons situated in the preoptic area
  • kisspeptin has emerged as one of the most potent secretagogues of GNRH release
  • hypothesis that obesity-mediated inhibition of kisspeptin signalling contributes to the suppression of the HPT axis, infusion of a bioactive kisspeptin fragment has been recently shown to robustly increase LH pulsatility, LH levels and circulating testosterone in hypotestosteronaemic men with type 2 diabetes
  • A smaller study with a similar experimental design found that acute testosterone withdrawal reduced insulin sensitivity independent of body weight, whereas oestradiol withdrawal had no effects
  • suppression of the diabesity-associated HPT axis is functional, and may hence be reversible
  • Obesity and dysglycaemia and associated comorbidities such as obstructive sleep apnoea (Hoyos et al. 2012b) are important contributors to the suppression of the HPT axis
  • weight gain and development of diabetes accelerate the age-related decline in testosterone
  • Modifiable risk factors such as obesity and co-morbidities are more strongly associated with a decline in circulating testosterone levels than age alone
  • 55% of symptomatic androgen deficiency reverted to a normal testosterone or an asymptomatic state after 8-year follow-up, suggesting that androgen deficiency is not a stable state
  • Weight loss can reactivate the hypothalamic–pituitary–testicular axis
  • Leptin treatment resolves hypogonadism in leptin-deficient men
  • The hypothalamic–pituitary–testicular axis remains responsive to treatment with aromatase inhibitors or selective oestrogen receptor modulators in obese men
  • Kisspeptin treatment increases LH secretion, pulse frequency and circulating testosterone levels in hypotestosteronaemic men with type 2 diabetes
  • change in BMI was associated with the change in testosterone (Corona et al. 2013a,b).
  • weight loss can lead to genuine reactivation of the gonadal axis by reversal of obesity-associated hypothalamic suppression
  • There is pre-clinical and observational evidence that chronic hyperglycaemia can inhibit the HPT axis
  • in men who improved their glycaemic control over time, testosterone levels increased. By contrast, in those men in whom glycaemic control worsened, testosterone decreased
  • testosterone levels should be measured after successful weight loss to identify men with an insufficient rise in their testosterone levels. Such men may have HPT axis pathology unrelated to their obesity, which will require appropriate evaluation and management.
  • Nathan Goodyear on 04 Feb 14
     
    Article discusses the expanding evidence of low T and Metabolic syndrome.
Nathan Goodyear

Testosterone: a vascular hormone in health and disease - 0 views

joe.endocrinology-journals.org/...R47.full

testosterone hormone health disease hormones men male cardiovascular disease CVD

shared by Nathan Goodyear on 13 May 13 - No Cached
  • Testosterone has beneficial effects on several cardiovascular risk factors, which include cholesterol, endothelial dysfunction and inflammation
  • In clinical studies, acute and chronic testosterone administration increases coronary artery diameter and flow, improves cardiac ischaemia and symptoms in men with chronic stable angina and reduces peripheral vascular resistance in chronic heart failure.
  • testosterone is an L-calcium channel blocker and induces potassium channel activation in vascular smooth muscle cells
  • ...54 more annotations...
  • Animal studies have consistently demonstrated that testosterone is atheroprotective, whereas testosterone deficiency promotes the early stages of atherogenesis
  • there is no compelling evidence that testosterone replacement to levels within the normal healthy range contributes adversely to the pathogenesis of CVD (Carson & Rosano 2011) or prostate cancer (Morgentaler & Schulman 2009)
  • bidirectional effect between decreased testosterone concentrations and disease pathology exists as concomitant cardiovascular risk factors (including inflammation, obesity and insulin resistance) are known to reduce testosterone levels and that testosterone confers beneficial effects on these cardiovascular risk factors
  • Achieving a normal physiological testosterone concentration through the administration of testosterone replacement therapy (TRT) has been shown to improve risk factors for atherosclerosis including reducing central adiposity and insulin resistance and improving lipid profiles (in particular, lowering cholesterol), clotting and inflammatory profiles and vascular function
  • It is well known that impaired erectile function and CVD are closely related in that ED can be the first clinical manifestation of atherosclerosis often preceding a cardiovascular event by 3–5 years
  • no decrease in the response (i.e. no tachyphylaxis) of testosterone and that patient benefit persists in the long term.
  • free testosterone levels within the physiological range, has been shown to result in a marked increase in both flow- and nitroglycerin-mediated brachial artery vasodilation in men with CAD
  • Clinical studies, however, have revealed either small reductions of 2–3 mm in diastolic pressure or no significant effects when testosterone is replaced within normal physiological limits in humans
  • Endothelium-independent mechanisms of testosterone are considered to occur primarily via the inhibition of voltage-operated Ca2+ channels (VOCCs) and/or activation of K+ channels (KCs) on smooth muscle cells (SMCs)
  • Testosterone shares the same molecular binding site as nifedipine
  • Testosterone increases the expression of endothelial nitric oxide synthase (eNOS) and enhances nitric oxide (NO) production
  • Testosterone also inhibited the Ca2+ influx response to PGF2α
  • one of the major actions of testosterone is on NO and its signalling pathways
  • In addition to direct effects on NOS expression, testosterone may also affect phosphodiesterase type 5 (PDE5 (PDE5A)) gene expression, an enzyme controlling the degradation of cGMP, which acts as a vasodilatory second messenger
  • the significance of the action of testosterone on VSMC apoptosis and proliferation in atherosclerosis is difficult to delineate and may be dependent upon the stage of plaque development
  • Several human studies have shown that carotid IMT (CIMT) and aortic calcification negatively correlate with serum testosterone
  • t long-term testosterone treatment reduced CIMT in men with low testosterone levels and angina
  • neither intracellular nor membrane-associated ARs are required for the rapid vasodilator effect
  • acute responses appear to be AR independent, long-term AR-mediated effects on the vasculature have also been described, primarily in the context of vascular tone regulation via the modulation of gene transcription
  • Testosterone and DHT increased the expression of eNOS in HUVECs
  • oestrogens have been shown to activate eNOS and stimulate NO production in an ERα-dependent manner
  • Several studies, however, have demonstrated that the vasodilatory actions of testosterone are not reduced by aromatase inhibition
  • non-aromatisable DHT elicited similar vasodilation to testosterone treatment in arterial smooth muscle
  • increased endothelial NOS (eNOS) expression and phosphorylation were observed in testosterone- and DHT-treated human umbilical vein endothelial cells
  • Androgen deprivation leads to a reduction in neuronal NOS expression associated with a decrease of intracavernosal pressure in penile arteries during erection, an effect that is promptly reversed by androgen replacement therapy
  • Observational evidence suggests that several pro-inflammatory cytokines (including interleukin 1β (IL1β), IL6, tumour necrosis factor α (TNFα), and highly sensitive CRP) and serum testosterone levels are inversely associated in patients with CAD, T2DM and/or hypogonadism
  • patients with the highest IL1β concentrations had lower endogenous testosterone levels
  • TRT has been reported to significantly reduce TNFα and elevate the circulating anti-inflammatory IL10 in hypogonadal men with CVD
  • testosterone treatment to normalise levels in hypogonadal men with the MetS resulted in a significant reduction in the circulating CRP, IL1β and TNFα, with a trend towards lower IL6 compared with placebo
  • parenteral testosterone undecanoate, CRP decreased significantly in hypogonadal elderly men
  • Higher levels of serum adiponectin have been shown to lower cardiovascular risk
  • Research suggests that the expression of VCAM-1, as induced by pro-inflammatory cytokines such as TNFα or interferon γ (IFNγ (IFNG)) in endothelial cells, can be attenuated by treatment with testosterone
  • Testosterone also inhibits the production of pro-inflammatory cytokines such as IL6, IL1β and TNFα in a range of cell types including human endothelial cells
  • decreased inflammatory response to TNFα and lipopolysaccharide (LPS) in human endothelial cells when treated with DHT
  • The key to unravelling the link between testosterone and its role in atherosclerosis may lay in the understanding of testosterone signalling and the cross-talk between receptors and intracellular events that result in pro- and/or anti-inflammatory actions in athero-sensitive cells.
  • testosterone functions through the AR to modulate adhesion molecule expression
  • pre-treatment with DHT reduced the cytokine-stimulated inflammatory response
  • DHT inhibited NFκB activation
  • DHT could inhibit an LPS-induced upregulation of MCP1
  • Both NFκB and AR act at the transcriptional level and have been experimentally found to be antagonistic to each other
  • As the AR and NFκB are mutual antagonists, their interaction and influence on functions can be bidirectional, with inflammatory agents that activate NFκB interfering with normal androgen signalling as well as the AR interrupting NFκB inflammatory transcription
  • prolonged exposure of vascular cells to the inflammatory activation of NFκB associated with atherosclerosis may reduce or alter any potentially protective effects of testosterone
  • DHT and IFNγ also modulate each other's signalling through interaction at the transcriptional level, suggesting that androgens down-regulate IFN-induced genes
  • (Simoncini et al. 2000a,b). Norata et al. (2010) suggest that part of the testosterone-mediated atheroprotective effects could depend on ER activation mediated by the testosterone/DHT 3β-derivative, 3β-Adiol
  • TNFα-induced induction of ICAM-1, VCAM-1 and E-selectin as well as MCP1 and IL6 was significantly reduced by a pre-incubation with 3β-Adiol in HUVECs
  • 3β-Adiol also reduced LPS-induced gene expression of IL6, TNFα, cyclooxygenase 2 (COX2 (PTGS2)), CD40, CX3CR1, plasminogen activator inhibitor-1, MMP9, resistin, pentraxin-3 and MCP1 in the monocytic cell line U937 (Norata et al. 2010)
  • This study suggests that testosterone metabolites, other than those generated through aromatisation, could exert anti-inflammatory effects that are mediated by ER activation.
  • The authors suggest that DHT differentially effects COX2 levels under physiological and pathophysiological conditions in human coronary artery smooth muscle cells and via AR-dependent and -independent mechanisms influenced by the physiological state of the cell
  • There are, however, a number of systematic meta-analyses of clinical trials of TRT that have not demonstrated an increased risk of adverse cardiovascular events or mortality
  • The TOM trial, which was designed to investigate the effect of TRT on frailty in elderly men, was terminated prematurely as a result of an increased incidence of cardiovascular-related events after 6 months in the treatment arm
  • trials of TRT in men with either chronic stable angina or chronic cardiac failure have also found no increase in either cardiovascular events or mortality in studies up to 12 months
  • Evidence may therefore suggest that low testosterone levels and testosterone levels above the normal range have an adverse effect on CVD, whereas testosterone levels titrated to within the mid- to upper-normal range have at least a neutral effect or, taking into account the knowledge of the beneficial effects of testosterone on a series of cardiovascular risk factors, there may possibly be a cardioprotective action
  • The effect of testosterone on human vascular function is a complex issue and may be dependent upon the underlying androgen and/or disease status.
  • the majority of studies suggest that testosterone may display both acute and chronic vasodilatory effects upon various vascular beds at both physiological and supraphysiological concentrations and via endothelium-dependent and -independent mechanisms
  • Nathan Goodyear on 13 May 13
     
    Good deep look into the testosterone and CVD link.
Nathan Goodyear

Nutrients | Free Full-Text | Vitamin C Status Correlates with Markers of Metabolic and ... - 0 views

www.mdpi.com/...htm

vitamin C health cognition

shared by Nathan Goodyear on 28 Feb 18 - No Cached
  • vitamin C deficiency is the fourth most prevalent nutrient deficiency reported in the United States
  • Hypovitaminosis C (defined as a plasma concentration ≤23 µmol/L)
  • The CHALICE (Canterbury Health, Ageing and Lifecourse) study is a unique New Zealand study comprising a comprehensive database of determinants of health
  • ...17 more annotations...
  • The CHALICE cohort of 404 individuals aged 50 years had an average vitamin C intake of ~110 mg/day, which should provide adequate plasma concentrations [14]. Despite this, a significant proportion of the participants had inadequate plasma vitamin C status
  • inadequate plasma vitamin C concentrations (i.e., <50 µmol/L)
  • adequate plasma levels (i.e., >50 µmol/L)
  • Higher plasma vitamin C status was associated with lower weight, BMI and waist circumference
  • plasma vitamin C was negatively associated with blood triglycerides, HbA1c and insulin, and positively associated with HDL levels.
  • No correlation was found between plasma vitamin C and the two indicators of heart health; blood pressure and cardiovascular risk score.
  • 2.4% of 50-year-olds were deficient in vitamin C (i.e., <11 µmol/L)
  • hypovitaminosis C (i.e., <23 µmol/L)
  • A high proportion (63%) of our participants had inadequate plasma vitamin C concentrations (i.e., <50 µmol/L)
  • The association of low vitamin C with obesity in this study replicates results in the literature [35,40,41,42,43,44], and it is apparent that individuals with higher weight require higher intakes of vitamin C to reach adequate vitamin C status
  • higher plasma vitamin C status is associated with lower circulating levels of blood triglycerides, insulin and HbA1c
  • A role for vitamin C in the prevention or management of diabetes and/or metabolic syndrome has been suggested
  • In this study, we also demonstrate lower levels of mild cognitive impairment in those with high vitamin C status
  • The odds of mild cognitive impairment were twice as high for those below 23 μmol/L plasma vitamin C concentration.
  • Vitamin C is present at very high concentrations in the brain
  • animal models have shown that the brain is the last organ to be depleted of the vitamin during prolonged deficiency
  • A recent animal study has shown that moderate vitamin C deficiency may play a role in accelerating amyloid plaque accumulation in Alzheimer’s disease
  • Nathan Goodyear on 28 Feb 18
     
    New study: vitamin C levels correlate with cognitive and metabolic health. What is your vitamin C level? Despite the adequate levels of vitamin C intake, a large % of the individuals had inadequate vitamin C levels which points to a demand issue.  Higher oxidative stress, chronic inflammation... would drive demand for vitamin C higher. Lower vitamin C levels were associated with more metabolic disease, ie. DM, and more cognitive decline.
Nathan Goodyear

The Role of Vitamin C in Human Immunity and Its Treatment Potential Against COVID-19: A... - 0 views

www.ncbi.nlm.nih.gov/...PMC9925039

COVID-19 SARS-CoV-2 COVID WBC ascorbic acid vitamin C

shared by Nathan Goodyear on 01 Sep 23 - No Cached
  • vitamins A, B, C, E, B6, B12, folate, zinc, iron, copper, and selenium
  • White blood cells, including neutrophils and monocytes, accumulate concentrations of vitamin C up to 100 times greater than that of plasma
  • Vitamin C is a crucial component of both the innate (nonspecific) and adaptive (specific) portions of the immune system
  • ...52 more annotations...
  • play a role during the initial chemotactic response of neutrophils shortly after infection
  • following vitamin C supplementation, a 20% increase in neutrophil chemotactic activity was observed
  • also contributes to the phagocytosis and killing of microbes by neutrophils
  • low levels of vitamin C occurring in high-stress situations
  • maturation, proliferation, and viability of T cells have all been shown to be upregulated by the presence of normal physiologic concentrations of vitamin C
  • Vitamin C has been shown to directly affect the number of Igs released from B cells
  • vitamin C among healthy young adult males showed a significant increase in serum levels of IgA, IgG, and IgM
  • effects of high-dose vitamin C on cytokine levels in cancer patients, finding decreased amounts of the cytokines Interleukin-1 alpha (IL-1 alpha), IL-2, IL-8, and tumor necrosis factor-alpha (TNF-alpha) after high-dose vitamin C infusion
  • when vitamin C was supplemented with vitamin E in healthy adults, it increased the production of cytokines IL-1 beta and TNF-alpha
  • vitamin C acts to modulate the levels of cytokines to prevent them from fluctuating in either direction
  • vitamin C also acts as an important antioxidant to the cells of the immune system.
  • human leukocytes, neutrophils, in particular, possess the ability to transport the oxidized form of vitamin C across its membrane to use as a defense mechanism against ROS produced during an immune response
  • Vitamin C also can recover other endogenous antioxidants in the body such as vitamin E and glutathione, returning them to their active state
  • vitamin C can decrease the activation of NF-kB
  • can reduce harmful nitrogen-based compounds such as N-nitrosamines and nitrosamides, both of which are carcinogenic 
  • subjects taking oral vitamin C supplementation saw a 60% to 90% reduction in oxidative stress compared to a placebo control
  • subjects infused with vitamin C alone had a 516% increase in glutathione levels compared to subjects not provided the 500 mg daily supplementation
  • hydroxylating proline and lysine
  • mature and stabilize the tissue of a healing wound
  • healing
  • oral surgery
  • improved soft tissue regeneration
  • vitamin C increases the mRNA levels of type I and type III collagen in the human dermis
  • Studies have demonstrated that those with low levels of vitamin C are at a significantly higher risk of respiratory infection compared to those with normal levels
  • viral cold duration was reduced by about 8% in adults and 13.5% in children using prophylactic daily doses of 200 mg of oral vitamin C
  • prophylactically supplementing vitamin C decreases the risk of infection with respiratory viruses such as the common cold
  • combined with probiotics, oral vitamin C supplementation showed a 33% decrease in the incidence of respiratory tract infections in preschool-age children [
  • high-dose oral supplementation of vitamin C managed to prevent or reduce symptoms if taken before or just after the onset of cold- or flu-like symptoms
  • improvements in oxygen saturation and decreased IL-6 levels (a marker of inflammation) in the treatment group compared to the control group
  • 8 g doses of oral vitamin C
  • there is a negative correlation between age and serum levels of vitamin C
  • Patients with COVID-19 will likely also experience depletion in serum levels of vitamin C as a direct result of the upregulation of the immune system to combat the infection
  • Colunga et al. suggested that oral vitamin C can be combined with oral Quercetin, an antiviral flavonoid, to improve Quercetin’s ability to block viral membrane fusion of SARS-CoV-2
  • high doses of 1-2 g/day of oral vitamin C could prevent other upper respiratory infections
  • It appears vitamin C supplementation by itself does not provide a striking benefit in preventing COVID-19 infection for those without a deficiency
    • Nathan Goodyear
      Nathan Goodyear on 01 Sep 23
       
      Flawed statement. What is normal? Vitamin D. Many variables effect levels and dose, including the two compartment kinetics and absorption.
  • Hiedra et al. were able to show decreases in inflammatory biomarkers, such as D-dimer and ferritin
  • some evidence to support that prophylactic use of vitamin C helps reduce the severity of respiratory infection symptoms once a subject has already been infected
  • oral vitamin C in combination with zinc provided the largest amount of antibody titers 42 days
  • linear relationship between days of vitamin C therapy and survival duration
  • other studies were unable to find any definitive improvement concerning therapy with vitamin C
    • Nathan Goodyear
      Nathan Goodyear on 01 Sep 23
       
      Either these studies are designed to fail or the authors are lacking some basic understanding of pharmacokinetics and pharmacodynamics with vitamin C.
  • Fowler et al. aimed to see if a high-dose vitamin C infusion would benefit patients affected by ARDS, but they were unable to conclude that vitamin C infusion, compared to a placebo, could decrease vascular inflammation and damage in ARDS
    • Nathan Goodyear
      Nathan Goodyear on 01 Sep 23
       
      At what dose, duration, frequency???
  • in a sample of 67 COVID-19-positive ICU patients, 82% of them displayed plasma vitamin C levels below 0.4 mg/dL
    • Nathan Goodyear
      Nathan Goodyear on 01 Sep 23
       
      They are kind of make the point from my earlier note.
  • continuous vitamin C infusion at a rate of 60 mg/kg/day for four days decreased the need for mechanical ventilation and vasopressor use but had no significant effect on overall mortality
    • Nathan Goodyear
      Nathan Goodyear on 01 Sep 23
       
      Again, designed to fail or ignorance designed the study which failed
  • Carr et al. suggested that high-dose IV vitamin C is most effective when treating sepsis as septic patients receiving the normal daily recommendations through diet still showed decreased vitamin C levels
  • High-dose IV vitamin C treatment has also been shown by Kakodkar et al. to decrease syndecan-1, an endothelial glycocalyx that contributes to mortality in septic patients
  • combined with hydrocortisone and thiamine, septic patients treated with 1.5 g of IV vitamin C every six hours showed a distinct decrease in their SOFA scores and none of the patients treated developed organ failure
  • combined with hydrocortisone and thiamine, septic patients treated with 1.5 g of IV vitamin C every six hours showed a distinct decrease in their SOFA scores and none of the patients treated developed organ failure
  • reduced overall mortality
  • reduced overall mortality
  • propose the use for high-dose vitamin C to aid in the treatment of septic shock-induced hypotension
  • treatment of severe sepsis using a high dose (up to 200 mg/kg/day) of IV vitamin C was explored in phase I, a double-blind, randomized, placebo-controlled trial by Fowler et al. [75]. Their findings included a reduction in SOFA scores and decreased vascular injury compared to a placebo control group, all while showing minimal adverse side effects
    • Nathan Goodyear
      Nathan Goodyear on 01 Sep 23
       
      High dose here is laughable. Again, duration and frequency also.
  • Maintaining a daily intake of 75 and 100 mg for men and women, respectively, as recommended by the U.S. Institute of Medicine
    • Nathan Goodyear
      Nathan Goodyear on 01 Sep 23
       
      This recommendation is FRANK IGNORANCE
Nathan Goodyear

The Complex Role of Estrogens in Inflammation - 0 views

edrv.endojournals.org/...521.full

estrogens inflammation

shared by Nathan Goodyear on 14 Aug 12 - No Cached
  • These studies suggest inflammation-dependent up-regulation of ERβ relative to ERα.
  • up-regulation of ERβ relative to ERα under hypoxic conditions, which might lead to a preponderance of signaling through ERβ pathways
  • it seems that E2 at periovulatory to pregnancy levels inhibited proinflammatory cytokines from PBMCs
  • ...26 more annotations...
  • it is clear that E2 can stimulate antibody production by B cells, probably by inhibiting T cell suppression of B cells
  • In cycling women, the largest quantities of Ig were detected before ovulation
  • In contrast, E2 at high concentrations leads to a suppression of B-lymphocyte lineage precursors
  • E2 at periovulatory to pregnancy serum levels is able to stimulate antibody secretion under healthy conditions but also in autoimmune diseases, whereas similar serum levels of E2 lead to a suppression of bone marrow B cell lineage precursors
  • In chronic inflammatory disorders, where B cells play a decisive role, E2 would promote the disease when autoaggressive B cells are already present, whereas chronically elevated E2 would inhibit initiation of an autoimmune disease when no such B cells are available. This might be a good reason why particularly B cell-dependent diseases such as SLE, mixed connective tissue disease (Sharp syndrome), IgA nephropathy, dermatitis herpetiformis, gluten sensitive enteropathy, myasthenia gravis, and thyroiditis appear in women in the reproductive years, predominantly, in the third or fourth decades of life
  • Th17 cells are thought to be the main responsible cells for chronic inflammatory tissue destruction in autoimmune diseases
  • IFN-γ, IL-12, and TNF were allocated to Th1 reactions
  • IL-4, IL-5, and IL-10 to Th2 responses
  • antiinflammatory T regulatory cells producing TGF-β and proinflammatory T helper type 17 cells (Th17) producing IL-17
  • no direct effects of estrogens on Th17 cells or IL-17 secretion have been described until now.
  • So-called Th17 cells producing IL-17 are the main T cells responsible for chronic inflammation.
  • Because IFN-γ has been allocated a Th17-inhibiting role (Fig. 1⇑), its increase by E2 at pregnancy doses and the E2-mediated inhibition of TNF must be viewed as a favorable effect in chronic inflammation
  • in humans and mice, E2 at periovulatory to pregnancy levels stimulates IL-4, IL-10, and IFN-γ but inhibits TNF from CD4+ T cells
  • In humans and mice, E3 and E2, respectively, at pregnancy levels inhibit T cell-dependent delayed type hypersensitivity
  • increased IL-4, IL-10, and IFN-γ in the presence of low TNF support an antiaggressive immune response
  • secretion of IL-1β is increased at periovulatory/proestrus to early pregnancy levels, whereas IL-1 secretion is inhibited at high pregnancy levels
  • The dichotomous effect of E2 on IL-1β and TNF at high and low concentrations is most probably due to inhibition of NF-κB at high concentrations
  • experiments with mouse and rat macroglial and microglial cells demonstrate that E2 at proestrus to pregnancy levels exerts neuroprotective effects by increasing TGF-β and by inhibiting iNOS and NO release, and reducing expression of proinflammatory cytokines and prostaglandin E2 production.
  • E2 at periovulatory to pregnancy levels inhibits NF-κB activation, which must be viewed as an antiinflammatory signal
  • It was shown that E2 concentrations equal to or above 10−10 m are necessary to inhibit NF-κB activation
  • important proinflammatory cytokines are typically inhibited at periovulatory (proestrus) to pregnancy levels of E2, which is evident for IL-6, IL-8, and TNF
  • low E2 concentrations were demonstrated to have no or even stimulatory effects
  • This renders a woman in the postmenopausal phase to a more proinflammatory situation
  • most in vitro studies demonstrated a stimulatory effect of E2 on secretion of IL-4, IL-10, and TGF-β typically at periovulatory to pregnancy levels
  • E2 at periovulatory to pregnancy levels has an ameliorating effect on chronic inflammatory diseases as long as B cell-dependent immunity or an overshooting fibrotic tissue repair process do not play a crucial pathogenic role. However, when the B cell plays an important role, E2 might even stimulate the disease process as substantiated by flare-ups in SLE during pregnancy
    • Nathan Goodyear
      Nathan Goodyear on 15 Aug 12
       
      SLE, mixed connective tissue disease (Sharp syndrome), IgA nephropathy, dermatitis herpetiformis, gluten sensitive enteropathy, myasthenia gravis, and thyroiditis
  • Short-term administration of E2 at pregnancy levels was shown to induce an inflammatory response specific to the lateral prostate of the castrated male rat
  • Nathan Goodyear on 14 Aug 12
     
    great review of the complex interaction between Estrogens and inflammation.  Reference here is in females.
Nathan Goodyear

Lowered testosterone in male obesity: Mechanisms, morbidity and management Tang Fui MN,... - 0 views

www.ajandrology.com/article.asp

Testosterone male obesity overweight men hormone hormones low T Low T

shared by Nathan Goodyear on 15 Jan 14 - No Cached
  • The number of overweight people is expected to increase from 937 million in 2005 to 1.35 billion in 2030
  • Similarly the number of obese people is projected to increase from 396 million in 2005 to 573 million in 2030
  • By 2030, China alone is predicted to have more overweight men and women than the traditional market economies combined
  • ...37 more annotations...
  • diacylglycerol O-acyltransferase 2 (DGAT2), mechanistically implicated in this differential storage, [10] is regulated by dihydrotestosterone, [11] suggesting a potential role for androgens to influence the genetic predisposition to either the MHO or MONW phenotype.
  • bariatric surgery achieves 10%-30% long-term weight loss in controlled studies
  • The fact that obese men have lower testosterone compared to lean men has been recognized for more than 30 years
  • Reductions in testosterone levels correlate with the severity of obesity and men
  • epidemiological data suggest that the single most powerful predictor of low testosterone is obesity, and that obesity is a major contributor of the age-associated decline in testosterone levels.
  • healthy ageing by itself is uncommonly associated with marked reductions in testosterone levels
  • obesity blunts this LH rise, obesity leads to hypothalamic-pituitary suppression irrespective of age which cannot be compensated for by physiological mechanisms
  • Reductions in total testosterone levels are largely a consequence of reductions in sex hormone binding globulin (SHBG) due to obesity-associated hyperinsulinemia
  • although controversial, measurement of free testosterone levels may provide a more accurate assessment of androgen status than the (usually preferred) measurement of total testosterone in situations where SHBG levels are outside the reference range
  • SHBG increases with age
  • marked obesity however is associated with an unequivocal reduction of free testosterone levels, where LH and follicle stimulating hormone (FSH) levels are usually low or inappropriately normal, suggesting that the dominant suppression occurs at the hypothalamic-pituitary level
  • adipose tissue, especially when in the inflamed, insulin-resistant state, expresses aromatase which converts testosterone to estradiol (E 2 ). Adipose E 2 in turn may feedback negatively to decrease pituitary gonadotropin secretion
  • diabetic obesity is associated with decreases in circulatory E 2
  • In addition to E 2 , increased visceral fat also releases increased amounts of pro-inflammatory cytokines, insulin and leptin; all of which may inhibit the activity of the HPT axis at multiple levels
  • In the prospective Massachusetts Male Aging Study (MMAS), moving from a non-obese to an obese state resulted in a decline of testosterone levels
  • weight loss, whether by diet or surgery, increases testosterone levels proportional to the amount of weight lost
  • fat is androgen-responsive
  • low testosterone may augment the effects of a hypercaloric diet
  • In human male ex vivo adipose tissue, testosterone decreased adipocyte differentiation by 50%.
  • Testosterone enhances catecholamine-induced lipolysis in vitro and reduces lipoprotein lipase activity and triglyceride uptake in human abdominal adipose tissue in vivo
  • in men with prostate cancer receiving 12 months of androgen deprivation therapy, fat mass increased by 3.4 kg and abdominal VAT by 22%, with the majority of these changes established within 6 months
  • severe sex steroid deficiency can increase fat mass rapidly
  • bidirectional relationship between testosterone and obesity
  • increasing body fat suppresses the HPT axis by multiple mechanisms [30] via increased secretion of pro-inflammatory cytokines, insulin resistance and diabetes; [19],[44] while on the other hand low testosterone promotes further accumulation of total and visceral fat mass, thereby exacerbating the gonadotropin inhibition
  • androgens may play a more significant role in VAT than SAT
  • men undergoing androgen depletion for prostate cancer show more marked increases in visceral compared to subcutaneous fat following treatment
    • Nathan Goodyear
      Nathan Goodyear on 16 Jan 14
       
      Interesting: low T increases VAT, yet T therapy does not reduce VAT, yet T therapy reduces SAT.
  • irisin, derived from muscle, induces brown fat-like properties in rodent white fat
  • androgens can act via the PPARg-pathway [37] which is implicated in the differentiation of precursor fat cells to the energy-consuming phenotype
  • low testosterone may compound the effect of increasing fat mass by making it more difficult for obese men to lose weight via exercise
  • pro-inflammatory cytokines released by adipose tissue may contribute to loss of muscle mass and function, leading to inactivity and further weight gain in a vicious cycle
  • Sarcopenic obesity, a phenotype recapitulated in men receiving ADT for prostate cancer, [55] may not only be associated with functional limitations, but also aggravate the metabolic risks of obesity;
  • observational evidence associating higher endogenous testosterone with reduced loss of muscle mass and crude measures of muscle function in men losing weight
  • genuine reactivation of the HPT axis in obese men requires more substantial weight-loss
  • A number of intervention studies have confirmed that both diet- and surgically-induced weight losses are associated with increased testosterone, with the rise in testosterone generally proportional to the amount of weight lost
  • men, regardless of obesity level, can benefit from the effect of weight loss.
  • inconsistent effect of testosterone on VAT
  • Nathan Goodyear on 15 Jan 14
     
    to be read
Nathan Goodyear

Secular Decline in Male Testosterone and Sex Hormone Binding Globulin Serum Levels in D... - 0 views

jcem.endojournals.org/...4696.long

decline male testosterone hormone danish low t low Testosterone men SHBG serum levels

shared by Nathan Goodyear on 10 Dec 12 - No Cached
  • Serum SHBG levels are negatively associated with obesity and various measures of insulin resistance
  • SHBG levels increase during pharmacological oral estrogen treatment
  • insulin decreases SHBG productio
  • ...5 more annotations...
  • The secular decline in SHBG and testosterone serum levels did not lead to a change in the level of free testosterone
  • existence of specific binding sites for SHBG at the cell membrane of steroid-responsive tissues has been shown
  • it is alarming that changes of this magnitude can be detected over such a relatively short time
  • Sex steroids stimulate SHBG production and secretion in vitro
  • Serum testosterone levels decreased and SHBG levels increased with increasing age
  • Nathan Goodyear on 10 Dec 12
     
    lower levels of SHBG and serum testosterone were found in more recently born men.  Preceding generations of men produced higher testosterone levels than men born in more recent generations.
Nathan Goodyear

Metabolic management of brain cancer - 0 views

www.sciencedirect.com/...S0005272810006857

brain cancer

shared by Nathan Goodyear on 17 Jun 13 - No Cached
  • Glutamine is a major metabolic fuel for both brain tumor cells and tumor-associated macrophages (TAMs)
  • the malignant phenotype of brain tumor cells that survive radiotherapy is often greater than that of the cells from the original tumor.
  • Conventional chemotherapy has faired little better than radiation therapy for the long-term management of malignant brain cancer
  • ...37 more annotations...
  • most conventional radiation and brain cancer chemotherapies can enhance glioma energy metabolism and invasive properties, which would contribute to tumor recurrence and reduced patient survival [34].
  • We contend that all cancer regardless of tissue or cellular origin is a disease of abnormal energy metabolism
  • complex disease phenotypes can be managed through self-organizing networks that display system wide dynamics involving oxidative and non-oxidative (substrate level) phosphorylation
  • As long as brain tumors are provided a physiological environment conducive for their energy needs they will survive; when this environment is restricted or abruptly changed they will either grow slower, growth arrest, or perish [8] and [19]
  • New information also suggests that ketones are toxic to some human tumor cells and that ketones and ketogenic diets might restrict availability of glutamine to tumor cells [68], [69] and [70].
  • The success in dealing with environmental stress and disease is therefore dependent on the integrated action of all cells in the organism
  • Tumor cells survive in hypoxic environments not because they have inherited genes making them more fit or adaptable than normal cells, but because they have damaged mitochondria and have thus acquired the ability to derive energy largely through substrate level phosphorylation
  • Cancer cells survive and multiply only in physiological environments that provide fuels (mostly glucose and glutamine) subserving their requirement for substrate level phosphorylation
  • Integrity of the inner mitochondrial membrane is necessary for ketone body metabolism since β-hydroxybutyrate dehydrogenase, which catalyzes the first step in the metabolism of β-OHB to acetoacetate, interacts with cardiolipin and other phospholipids in the inner membrane
  • the mitochondria of many gliomas and most tumors for that matter are dysfunctional
  • Cardiolipin is essential for efficient oxidative energy production and mitochondrial function
  • Any genetic or environmental alteration in the content or composition of cardiolipin will compromise energy production through oxidative phosphorylation
  • The Crabtree effect involves the inhibition of respiration by high levels of glucose
  • the Warburg effect involves elevated glycolysis from impaired oxidative phosphorylation
  • the Crabtree effect can be reversible, the Warburg effect is largely irreversible because its origin is with permanently damaged mitochondria
  • The continued production of lactic acid in the presence of oxygen is the metabolic hallmark of most cancers and is referred to as aerobic glycolysis or the Warburg effect
  • We recently described how the retrograde signaling system could induce changes in oncogenes and tumor suppressor genes to facilitate tumor cell survival following mitochondrial damage [48].
  • In addition to glycolysis, glutamine can also increase ATP production under hypoxic conditions through substrate level phosphorylation in the TCA cycle after its metabolism to α-ketoglutarate
  • mitochondrial lipid abnormalities, which alter electron transport activities, can account in large part for the Warburg effect
  • targeting both glucose and glutamine metabolism could be effective for managing most cancers including brain cancer
  • The bulk of experimental evidence indicates that mitochondria are dysfunctional in tumors and incapable of generating sufficient ATP through oxidative phosphorylation
  • Cardiolipin defects in tumor cells are also associated with reduced activities of several enzymes of the mitochondrial electron transport chain making it unlikely that tumor cells with cardiolipin abnormalities can generate adequate energy through oxidative phosphorylation
  • The Crabtree effect involves the inhibition of respiration by high levels of glucose
  • Warburg effect involves elevated glycolysis from impaired oxidative phosphorylation
  • TCA cycle substrate level phosphorylation could therefore become another source of ATP production in tumor cells with impairments in oxidative phosphorylation
  • Caloric restriction, which lowers glucose and elevates ketone bodies [63] and [64], improves mitochondrial respiratory function and glutathione redox state in normal cells
  • DR naturally inhibits glycolysis and tumor growth by lowering circulating glucose levels, while at the same time, enhancing the health and vitality of normal cells and tissues through ketone body metabolism
  • DR is anti-angiogenic
  • DR also reduces angiogenesis in prostate and breast cancer
  • We suggest that apoptosis resistance arises largely from enhanced substrate level phosphorylation of tumor cells and to the genes associated with elevated glycolysis and glutaminolysis, e.g., c-Myc, Hif-1a, etc, which inhibit apoptosis
  • Modern medicine has not looked favorably on diet therapies for managing complex diseases especially when well-established procedures for acceptable clinical practice are available, regardless of how ineffective these procedures might be in managing the disease
  • More than 60 years of clinical research indicates that such approaches are largely ineffective in extending survival or improving quality of life
  • The process is rooted in the well-established scientific principle that tumor cells are largely dependent on substrate level phosphorylation for their survival and growth
  • Glucose and glutamine drive substrate level phosphorylation
  • targeting the glycolytically active tumor cells that produce pro-cachexia molecules, restricted diet therapies can potentially reduce tumor cachexia
  • It is important to recognize, however, that “more is not better” with respect to the ketogenic diet
  • Blood glucose ranges between 3.0 and 3.5 mM (55–65 mg/dl) and β-OHB ranges between 4 and 7 mM should be effective for tumor management
  • Nathan Goodyear on 17 Jun 13
     
    Dr Seyfriend presents his metabolic approach to the treatment of brain cancer.
Nathan Goodyear

Relationship between Low Free Testosterone Levels and Loss of Muscle Mass : Scientific ... - 0 views

www.nature.com/...srep01818.html

muscle men male hormone Testosterone free Testosterone low T low Testosterone

shared by Nathan Goodyear on 05 Mar 15 - No Cached
  • Our data confirm that a low FT level is a significant predictor of a risk for loss of appendicular muscle
  • Total lean mass is associated with bioavailable T in postmenopausal women
  • Further studies are needed to determine the role of androgens in preserving muscle mass in women
  • ...11 more annotations...
  • Approximately 1% to 2% of T in the blood exists as FT
  • appendicular muscle loss was significantly associated with low levels of FT
  • These results suggest that a threshold level of FT exists for muscle loss, rather than a dose-response relationship
  • In the previous cross-sectional and longitudinal studies of French and American men, no dose-response relationships were reported between T and muscle mass
  • A minimal serum level of FT may be needed to preserve muscle mass in men, regardless of race/ethnicity.
  • Our result is in line with previous studies that reported a relationship between low FT and low muscle mass in men
  • T stimulates protein synthesis and inhibits protein degradation in muscle cells
  • T also increases satellite cell replication and activation in older men
  • In this study, no significant association between TT levels and muscle loss were observed
  • Although a progressive decrease in TT levels with ageing is observed in middle-aged and elderly American men16, 17, the TT levels do not change during ageing in Japanese men
  • FT levels may be a good marker for the loss of muscle mas
  • Nathan Goodyear on 05 Mar 15
     
    study of Japanese men finds that low free Testosterone was a predictor of decrease in muscle mass.
Nathan Goodyear

Testosterone for the aging male; current evidence and recommended practice - 0 views

www.ncbi.nlm.nih.gov/...PMC2544367

leptin Testosterone low T low Testosterone male hormone hormones

shared by Nathan Goodyear on 27 Oct 14 - No Cached
  • Total serum testosterone consists of free testosterone (2%–3%), testosterone bound to sex hormone binding globulin (SHBG) (45%) and testosterone bound to other proteins (mainly albumin −50%)
  • Testosterone binds only loosely to albumin and so this testosterone as well as free testosterone is available to tissues and is termed bioavailable testosterone
  • Testosterone bound to SHBG is tightly bound and is biologically inactive
  • ...13 more annotations...
  • Bioavailable and free testosterone are known to correlate better than total testosterone with clinical sequelae of androgenization such as bone mineral density and muscle strength
  • peak levels seen in the morning following sleep, which can be maintained into the seventh decade
  • Samples should always be taken in the morning before 11 am
  • The reliable measurement of serum free testosterone requires equilibrium dialysis. This is not appropriate for clinical use as it is very time consuming and therefore expensive.
  • With increasing age, a greater number of men have total testosterone levels just below the normal range or in the low-normal range. In these patients total testosterone can be an unreliable indicator of hypogonadal status.
  • It is advised that at least two serum testosterone measurements, taken before 11 am on different mornings, are necessary to confirm the diagnosis.
  • Patients with serum total testosterone consistently below 8 nmol/l invariably demonstrate the clinical syndrome of hypogonadism and are likely to benefit from treatment. Patients with serum total testosterone in the range 8–12 nmol/l often have symptoms attributable to hypogonadism and it may be decided to offer either a clinical trial of testosterone treatment or to make further efforts to define serum bioavailable or free testosterone and then reconsider treatment. Patients with serum total testosterone persistently above 12 nmol/l do not have hypogonadism and symptoms are likely to be due to other disease states or ageing per se so testosterone treatment is not indicated.
  • Total testosterone levels fall at an average of 1.6% per year whilst free and bioavailable levels fall by 2%–3% per year.
  • With advancing age there is also a reduction in androgen receptor concentration in some target tissues and this may contribute to the clinical syndrome of LOH
  • Metabolic clearance declines with age
  • Gonadotrophin levels rise during aging (Feldman et al 2002) and testicular secretory responses to recombinant human chorionic gonadotrophin (hCG) are reduced
  • There are changes in the lutenising hormone (LH) production which consist of decreased LH pulse frequency and amplitude, (Veldhuis et al 1992; Pincus et al 1997) although pituitary production of LH in response to pharmacological stimulation with exogenous GnRH analogues is preserved
  • the decreases in testosterone levels with aging seem to reflect changes at all levels of the hypothalamic-pituitary-testicular axis
  • Nathan Goodyear on 27 Oct 14
     
    Leptin inhibits male Testosterone production at the level of the hypothalamus and at the testicle level.
Nathan Goodyear

Longitudinal Effects of Aging on Serum Total and Free Testosterone Levels in Healthy Me... - 0 views

press.endocrine.org/...jcem.86.2.7219

low t low Testosterone Testosterone SHBG FAI free androgen index male hormone hormones aging obesity

shared by Nathan Goodyear on 30 Mar 15 - No Cached
  • NUMEROUS CROSS-SECTIONAL INVESTIGATIONS have demonstrated lower concentrations of circulating testosterone (T) and/or free T in older men
  • Two small-scale longitudinal investigations have observed decreases, with aging, in total T
  • T levels decline at a more or less constant rate, with age, in men, with no period of accelerated decline
  • ...15 more annotations...
  • aging in men is associated with decreases in bone mineral density (BMD) (18, 19), lean body and muscle mass
  • strength (22, 23) and aerobic capacity (24), as well as with increases in total and abdominal body fat, low-density lipoprotein cholesterol, and/or low-density lipoprotein/high-density lipoprotein cholesterol ratios (25, 26, 27, 28), all of which also occur in nonelderly hypogonadal men
  • Most (1, 5, 6, 7, 8, 9), but not all (10, 11, 12), cross-sectional studies have demonstrated a decrease, with age, in total T in men
    • Nathan Goodyear
      Nathan Goodyear on 30 Mar 15
       
      FAI: 100 x total Testosterone nmol/L/SHBG nmol/L
    • Nathan Goodyear
      Nathan Goodyear on 30 Mar 15
       
      These numbers do point to an increase in ng/dl decline in Total Testosterone with increasing age (decade group)
  • total T, but not free T index, tended to decrease with greater BMI is consistent with prior studies showing that obesity is associated with decreases in both SHBG and total T, with an unchanged T-to-SHBG ratio
  • The conventional definition for T levels is statistical (values more than 2 sd below the mean), rather than functional. Such a definition does not reflect clinical realities, such as the existence of characteristic individual set points for circulating hormone levels, below which one, but not another, individual may develop metabolic changes of hormone deficiency; nor does it address the concept of reserve capacity, the possibility that persons with hormone levels 2 sd below the population mean still may have adequate hormone concentrations to meet their metabolic needs.
    • Nathan Goodyear
      Nathan Goodyear on 30 Mar 15
       
      good explanation of problems with just using a number to define low T
  • both T and free T index (a calculated value related to free or bioavailable T) decreased progressively at a rate that did not vary significantly with age, from the third to the ninth decades.
  • contrasts with other studies showing diminished free, as well as total, T in with increasing total (48) or abdominal (49) obesity in men.
  • Our analysis of date-adjusted T and free T index levels, by decade, showed that relatively high numbers of older men in this generally healthy population had at least one hypogonadal value (defined as below the 2.5th percentile for young men)
  • The issue of how properly to define hypogonadism, or indeed any hormone deficiency, remains problematic
  • The decrease in free T index was somewhat steeper than that of total T, owing to a trend for an increase in SHBG with age
  • LH for gonadal function
  • It would clearly be better to define the lower limit of normal for a hormone as: the blood level at which metabolic and/or clinical sequelae of hormone deficiency begin to appear, or the level below which definite benefits can be demonstrated for hormone supplementation for a significant proportion of the population
  • an effect of aging to lower both total and bioavailable circulating T levels at a relatively constant rate, independent of obesity, illness, medications, cigarette smoking, or alcohol intake
  • Nathan Goodyear on 30 Mar 15
     
    Article highlights the problems with the definition of low T.  This article finds consistent decline in Total Testosterone and FAI with increasing age groups, with a significant portion of men > 60 meeting the required levels for "low T".  This study found a decrease in total T and FAI at a consistent rate independent of variables, such as BMI.    This study did find a decrease in SHBG and total T with obesity; in contrast to other studies.
Nathan Goodyear

Ibuprofen alters human testicular physiology to produce a state of compensated hypogona... - 0 views

www.pnas.org/...1715035115.full

ibuprofen Testosterone epigenetics hormones low Testosterone low T

shared by Nathan Goodyear on 09 Jan 18 - No Cached
  • The levels of LH in the ibuprofen group had increased by 23% after 14 d of administration
  • This increase was even more pronounced at 44 d, at 33%
  • We found an 18% decrease (P = 0.056) in the ibuprofen group compared with the placebo group after 14 d (Fig. 1A) and a 23% decrease (P = 0.02) after 44 d (Fig. 1C). Taken together, these in vivo data suggest that ibuprofen induced a state of compensated hypogonadism during the trial, which occurred as early as 14 d and was maintained until the end of the trial at 44 d
  • ...27 more annotations...
  • We first investigated testosterone production after 24 and 48 h of ibuprofen exposure to assess its effects on Leydig cell steroidogenesis. Inhibition of testosterone levels was significant and dose-dependent (β = −0.405, P = 0.01 at 24 h and β = −0.664, P < 0.0001 at 48 h) (Fig. 2A) and was augmented over time
  • The AMH data show that the hypogonadism affected not only Leydig cells but also Sertoli cells and also occurred as early as 14 d of administration
  • Sertoli cell activity showed that AMH levels decreased significantly with ibuprofen administration, by 9% (P = 0.02) after 14 d (Fig. 1B) and by 7% (P = 0.05) after 44 d compared with the placebo group
  • Examination of the effect of ibuprofen exposure on both the ∆4 and ∆5 steroid pathways (Fig. 2B) showed that it generally inhibited all steroids from pregnenolone down to testosterone and 17β-estradiol; the production of each steroid measured decreased at doses of 10−5–10−4 M. Under control conditions, production of androstenediol and dehydroepiandrosterone (DHEA) was below the limit of detection except in one experiment with DHEA
  • Measuring the mRNA expression of genes involved in steroidogenesis in vitro showed that ibuprofen had a profound inhibitory effect on the expression of these genes (Fig. 3 B–D), consistent with that seen above in our ex vivo organ model. Taken together, these data examining effects on the endocrine cells confirm that ibuprofen-induced changes in the transcriptional machinery were the likely reason for the inhibition of steroidogenesis.
  • Suppression of gene expression concerned the initial conversion of cholesterol to the final testosterone synthesis. Hence, expression of genes involved in cholesterol transport to the Leydig cell mitochondria was impaired
  • A previous study reported androsterone levels decreased by 63% among men receiving 400 mg of ibuprofen every 6 h for 4 wk
  • We next examined the gene expression involved in testicular steroidogenesis ex vivo and found that levels of expression of every gene that we studied except CYP19A1 decreased after exposure for 48 h compared with controls
  • the changes in gene expression indicate that the transcriptional machinery behind the endocrine action of Leydig cells was most likely impaired by ibuprofen exposure.
  • Together, these data show that ibuprofen also directly impairs Sertoli cell function ex vivo by inhibiting transcription
  • ibuprofen use in men led to (i) elevation of LH; (ii) a decreased testosterone/LH ratio and, to a lesser degree, a decreased inhibin B/FSH ratio; and (iii) a reduction in the levels of the Sertoli cell hormone AMH
  • The decrease in the free testosterone/LH ratio resulted primarily from the increased LH levels, revealing that testicular responsiveness to gonadotropins likely declined during the ibuprofen exposure. Our data from the ex vivo experiments support this notion, indicating that the observed elevation in LH resulted from ibuprofen’s direct antiandrogenic action
  • AMH levels were consistently suppressed by ibuprofen both in vivo and ex vivo, indicating that this hormone is uncoupled from gonadotropins in adult men. The ibuprofen suppression of AMH further demonstrated that the analgesic targeted not only the Leydig cells but also the Sertoli cells, a feature encountered not only in the human adult testis but also in the fetal testis
  • ibuprofen displayed broad transcription-repression abilities involving steroidogenesis, peptide hormones, and prostaglandin synthesis
  • a chemical compound, through its effects on the signaling compounds, can result in changes in the testis at gene level, resulting in perturbations at higher physiological levels in the adult human
  • The analgesics acetaminophen/paracetamol and ibuprofen have previously been shown to inhibit the postexercise response in muscles by repressing transcription
  • Previous ex vivo studies on adult testis have indeed pointed to an antiandrogenicity, only on Leydig cells, of phthalates (41), aspirin, indomethacin (42), and bisphenol A (BPA) and its analogs
  • ibuprofen’s effects were not restricted to Leydig and Sertoli cells, as data showed that the expression of genes in peritubular cells was also affected
  • short-term exposure
  • In the clinical setting, compromised Leydig cell function resulting in increased insensitivity to LH is defined as compensated hypogonadism (4), an entity associated with all-cause mortality
  • compensated hypogonadic men present with an increased likelihood of reproductive, cognitive, and physical symptoms
  • an inverse relationship was recently reported between endurance exercise training and male sexual libido
  • AMH concentrations are lower in seminal plasma from patients with azoospermia than from men with normal sperm levels
  • inhibin B is a key clinical marker of reproductive health (32). The function of AMH, also secreted by Sertoli cells, and its regulation through FSH remain unclear in men
  • the striking dual effect of ibuprofen observed here on both Leydig and Sertoli cells makes this NSAID the chemical compound, of all the chemical classes considered, with the broadest endocrine-disturbing properties identified so far in men.
  • after administration of 600 mg of ibuprofen to healthy volunteers
  • 14 d or at the last day of administration at 44 d
  • Nathan Goodyear on 09 Jan 18
     
    ibuprofen alters genetic expression that results in decreased Testosterone production.
Nathan Goodyear

Effect of Testosterone Replacement Therapy on Cognitive Performance and Depression in M... - 0 views

www.ncbi.nlm.nih.gov/...PMC5209560

low T Low testosterone Testosterone male hormones Testosterone therapy depression brain cognition ED erectile dysfunction

shared by Nathan Goodyear on 09 Jan 17 - No Cached
  • Azad et al [15] used single photon emission computed tomography and showed that, after 3~5 weeks of TRT, cerebral perfusion was increased in the midbrain and the superior frontal gyrus in seven men with hypogonadism
  • After 12~14 weeks, increased perfusion was still observed in the midbrain as well as in the midcingulate gyrus
  • TDS patients who received TRT showed significant improvement in cognitive function only if mild cognitive impairment was present at baseline
  • ...4 more annotations...
  • Cherrier et al [17] evaluated a sample of 32 subjects, which included 17 men with mild cognitive impairment and 15 with Alzheimer's disease. At the 6-week follow-up, patients who received TRT showed significantly better scores regarding spatial memory, constructional abilities, and verbal memory compared to those noted in the placebo group. Taken together, these results suggest that TRT has a beneficial effect on cognitive function
  • TRT improved mood and well-being, and reduced fatigue and irritability in hypogonadal men
  • The study by Pope et al [20] involved men with depression refractory to standard anti-depressants, and found that TRT lowered the Hamilton Depression score,
  • depression tends to increase as testosterone levels decrease [21], it is highly likely that TRT improved symptoms of depression by increasing testosterone levels.
  • Nathan Goodyear on 09 Jan 17
     
    men with Testosterone <300 ng/dl with levels after 8 months of therapy achieving +680 ng/dl.
Nathan Goodyear

Hormonal Modulation in Aging Patients with Erectile Dysfunction and Metabolic Syndrome - 0 views

www.ncbi.nlm.nih.gov/...PMC3888699

low T Testosterone hypogonadism MetS metabolic syndrome men male hormone hormones

shared by Nathan Goodyear on 05 Feb 14 - No Cached
  • Hypogonadism and MetS are strongly associated [12, 13, 16], having even been demonstrated that with the increasing number of MetS parameters there is a proportional raise in the incidence of hypogonadism
  • increasing number of MetS components is inversely associated with T levels
  • the presence of MetS did not prove to be a significant determinant of hypogonadism, as it did not lead to a decline in T levels, in MetS patients with already established hypogonadism, the increasing number of MetS features was associated with further decline in T
  • ...15 more annotations...
  • In the setting of MetS, hypertriglyceridemia and increased WC have been reported as the most important determinants of hypogonadism
  • recent literature consistently associates obesity not only with higher risk of hypogonadism [4, 6, 27] but also with lower T levels
  • Visceral adiposity has been particularly related with reduction of T and SHBG levels (independent of other metabolic disorders)
  • WC was one of the MetS parameters with the greatest influence in T levels decrease, presenting itself as a strong risk factor for hypogonadism development
  • MetS-related T decline was not accompanied by an increase in pituitary LH levels, suggesting impairment in gonadotropin secretion
  • The molecules behind this smoothing compensatory effect of GnRH/LH are still unknown, but estrogens and insulin, as well as leptin, TNF-α, and other adipokines, were proposed candidates
  • fat stores undertake an increase aromatization of androgens, therefore raising estrogen levels [9, 15], which in turn decrease LH secretion
  • our data contradicts the concept that estradiol exerts a negative feedback on hypothalamic GnRH secretion
  • taking into account that high estradiol levels have already been described as the only abnormality in a subset of patients with ED, the hypothesis that the later might not only be caused by androgen deficiency is becoming increasingly evident
  • it has been reported that the chronic exposure to phosphodiesterase type 5 inhibitors (PDE5i), widely used for the treatment of ED, may influence serum estradiol levels
  • thyroid disorders (specially hyperthyroidism) have been related to ED and hypogonadism, and so must be considered in a sexual-dysfunction setting
  • It is clear from the current literature that collecting a more thorough hormonal panel might be a wise approach to further uncover hormonal relations
    • Nathan Goodyear
      Nathan Goodyear on 05 Feb 14
       
      outstanding point.  This hits to the point that Low T is the effect not the cause.
  • We concluded that in ED patients with hypogonadism and MetS, the attenuated response of HPG axis (normal or low LH levels) might not always be due to an underlying adiposity-dependent estrogen-raising effect.
  • our findings indicate that ED, aging, and estradiol might have a stronger connection than what is currently described in the literature.
  • this study underlines the importance of the collection of a full hormonal panel in ED men
  • Nathan Goodyear on 05 Feb 14
     
    low T strongly associated with metabolic syndrome in men.
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