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

joe.endocrinology-journals.org/...R25.full male hormone hormones testosterone hypogonadal-obesity-adipocytokine hypothesis
shared by Nathan Goodyear on 08 May 13 - No Cached
  • E2 and the inflammatory adipocytokines tumour necrosis factor α (TNFα) and interleukin 6 (IL6) inhibit hypothalamic production of GNRH and subsequent release of LH and FSH from the pituitary
  • Leptin, an adipose-derived hormone with a well-known role in regulation of body weight and food intake, also induces LH release under normal conditions via stimulation of hypothalamic GNRH neurons
  • In human obesity, whereby adipocytes are producing elevated amounts of leptin, the hypothalamic–pituitary axis becomes leptin resistant
  • ...39 more annotations...
  • there is evidence from animal studies that leptin resistance, inflammation and oestrogens inhibit neuronal release of kisspeptin
  • Beyond hypothalamic action, leptin also directly inhibits the stimulatory action of gonadotrophins on the Leydig cells of the testis to decrease testosterone production; therefore, elevated leptin levels in obesity may further diminish androgen status
  • Prostate cancer patients with pre-existing T2DM show a further deterioration of insulin resistance and worsening of diabetic control following ADT
  • ADT for the treatment of prostatic carcinoma in some large epidemiological studies has been shown to be associated with an increased risk of developing MetS and T2DM
  • Non-diabetic men undergoing androgen ablation show increased occurrence of new-onset diabetes and demonstrate elevated insulin levels and worsening glycaemic control
  • increasing insulin resistance assessed by glucose tolerence test and hypoglycemic clamp was shown to be associated with a decrease in Leydig cell testosterone secretion in men
  • The response to testosterone replacement of insulin sensitivity is in part dependent on the androgen receptor (AR)
  • Low levels of testosterone have been associated with an atherogenic lipoprotein profile, characterised by high LDL and triglyceride levels
  • a positive correlation between serum testosterone and HDL has been reported in both healthy and diabetic men
  • up to 70% of the body's insulin sensitivity is accounted for by muscle
  • Testosterone deficiency is associated with a decrease in lean body mass
  • relative muscle mass is inversely associated with insulin resistance and pre-diabetes
  • GLUT4 and IRS1 were up-regulated in cultured adipocytes and skeletal muscle cells following testosterone treatment at low dose and short-time incubations
  • local conversion of testosterone to DHT and activation of AR may be important for glucose uptake
  • inverse correlation between testosterone levels and adverse mitochondrial function
  • orchidectomy of male Wistar rats and associated testosterone deficiency induced increased absorption of glucose from the intestine
  • (Kelley & Mandarino 2000). Frederiksen et al. (2012a) recently demonstrated that testosterone may influence components of metabolic flexibility as 6 months of transdermal testosterone treatment in aging men with low–normal bioavailable testosterone levels increased lipid oxidation and decreased glucose oxidation during the fasting state.
  • Decreased lipid oxidation coupled with diet-induced chronic FA elevation is linked to increased accumulation of myocellular lipid, in particular diacylglycerol and/or ceramide in myocytes
  • In the Chang human adult liver cell line, insulin receptor mRNA expression was significantly increased following exposure to testosterone
  • Testosterone deprivation via castration of male rats led to decreased expression of Glut4 in liver tissue, as well as adipose and muscle
  • oestrogen was found to increase the expression of insulin receptors in insulin-resistant HepG2 human liver cell line
  • FFA decrease hepatic insulin binding and extraction, increase hepatic gluconeogenesis and increase hepatic insulin resistance.
  • Only one, albeit large-scale, population-based cross-sectional study reports an association between low serum testosterone concentrations and hepatic steatosis in men (Völzke et al. 2010)
  • This suggests that testosterone may confer some of its beneficial effects on hepatic lipid metabolism via conversion to E2 and subsequent activation of ERα.
  • hypogonadal men exhibiting a reduced lean body mass and an increased fat mass, abdominal or central obesity
  • visceral adipose tissue was inversely correlated with bioavailable testosterone
  • there was no change in visceral fat mass in aged men with low testosterone levels following 6 months of transdermal TRT, yet subcutaneous fat mass was significantly reduced in both the thigh and the abdominal areas when analysed by MRI (Frederiksen et al. 2012b)
  • ADT of prostate cancer patients increased both visceral and subcutaneous abdominal fat in a 12-month prospective observational study (Hamilton et al. 2011)
  • Catecholamines are the major lipolysis regulating hormones in man and regulate adipocyte lipolysis through activation of adenylate cyclase to produce cAMP
  • deficiency of androgen action decreases lipolysis and is primarily responsible for the induction of obesity (Yanase et al. 2008)
  • may be some regional differences in the action of testosterone on subcutaneous and visceral adipose function
  • proinflammatory adipocytokines IL1, IL6 and TNFα are increased in obesity with a downstream effect that stimulates liver production of CRP
  • observational evidence suggests that IL1β, IL6, TNFα and CRP are inversely associated with serum testosterone levels in patients
  • TRT has been reported to significantly reduce these proinflammatory mediators
  • This suggests a role for AR in the metabolic actions of testosterone on fat accumulation and adipose tissue inflammatory response
  • testosterone treatment may have beneficial effects on preventing the pathogenesis of obesity by inhibiting adipogenesis, decreasing triglyceride uptake and storage, increasing lipolysis, influencing lipoprotein content and function and may directly reduce fat mass and increase muscle mass
  • Early interventional studies suggest that TRT in hypogonadal men with T2DM and/or MetS has beneficial effects on lipids, adiposity and parameters of insulin sensitivity and glucose control
  • Evidence that whole-body insulin sensitivity is reduced in testosterone deficiency and increases with testosterone replacement supports a key role of this hormone in glucose and lipid metabolism
  • Impaired insulin sensitivity in these three tissues is characterised by defects in insulin-stimulated glucose transport activity, in particular into skeletal muscle, impaired insulin-mediated inhibition of hepatic glucose production and stimulation of glycogen synthesis in liver, and a reduced ability of insulin to inhibit lipolysis in adipose tissue
  • Nathan Goodyear on 08 May 13
     
    Great review of the Hypogonadal-obesity-adipocytokine hypothesis.
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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.
38More

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

joe.endocrinology-journals.org/...R37.full
shared by Nathan Goodyear on 04 Feb 14 - No Cached
    • Nathan Goodyear
      Nathan Goodyear on 04 Feb 14
       
      80% of E2 production in men, that will cause low T in men, comes from SQ adiposity.  This leads to increase in visceral adiposity.
  • Only 5% of men with type 2 diabetes have elevated LH levels (Dhindsa et al. 2004, 2011). This is consistent with recent findings that the 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
  • ...32 more annotations...
  • kisspeptin has emerged as one of the most potent secretagogues of GNRH release
  • Consistent with the 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
  • Figure 4
  • Interestingly, a recent 16-week study of experimentally induced hypogonadism in healthy men with graded testosterone add-back either with or without concomitant aromatase inhibitor treatment has in fact suggested that low oestradiol (but not low testosterone) may be responsible for the hypogonadism-associated increase in total body and intra-abdominal fat mass
    • Nathan Goodyear
      Nathan Goodyear on 04 Feb 14
       
      This does not fit with the research on receptors, specifically estrogen receptors.  These studies that the authors are referencing are looking at "circulating" levels, not tissue levels.
  • 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
  • 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
  • This is supported by observational studies showing that weight gain and development of diabetes accelerate the age-related decline in testosterone
  • Weight loss can reactivate the hypothalamic–pituitary–testicular axis
  • 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
  • Several observational and randomised studies reviewed in Grossmann (2011) have shown that weight loss, whether by diet or surgery, leads to substantial increases in testosterone, especially in morbidly obese men
  • This suggests that 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 those men in whom glycaemic control worsened, testosterone decreased
  • successful weight loss combined with optimisation of glycaemic control may be sufficient to normalise circulating testosterone levels in the majority of such men
  • weight loss, optimisation of diabetic control and assiduous care of comorbidities should remain the first-line approach.
    • Nathan Goodyear
      Nathan Goodyear on 04 Feb 14
       
      This obviously goes against marketing-based medicine
  • In part, the discrepant results may be due to the fact men in the Vigen cohort (Vigen et al. 2013) had a higher burden of comorbidities. Given that one (Basaria et al. 2010), but not all (Srinivas-Shankar et al. 2010), RCTs in men with a similarly high burden of comorbidities reported an increase in cardiovascular events in men randomised to testosterone treatment (see section on Testosterone therapy: potential risks below) (Basaria et al. 2010), testosterone should be used with caution in frail men with multiple comorbidities
  • The retrospective, non-randomised and non-blinded design of these studies (Shores et al. 2012, Muraleedharan et al. 2013, Vigen et al. 2013) leaves open the possibility for residual confounding and multiple other sources of bias. These have been elegantly summarised by Wu (2012).
  • Effects of testosterone therapy on body composition were metabolically favourable with modest decreases in fat mass and increases in lean body mass
  • This suggests that testosterone has limited effects on glucose metabolism in relatively healthy men with only mildly reduced testosterone.
  • it is conceivable that testosterone treatment may have more significant effects on glucose metabolism in uncontrolled diabetes, akin to what has generally been shown for conventional anti-diabetic medications.
  • the evidence from controlled studies show that testosterone therapy consistently reduces fat mass and increases lean body mass, but inconsistently decreases insulin resistance.
  • Interestingly, testosterone therapy does not consistently improve glucose metabolism despite a reduction in fat mass and an increase in lean mass
  • the majority of RCTs (recently reviewed in Ng Tang Fui et al. (2013a)) showed that testosterone therapy does not reduce visceral fat
    • Nathan Goodyear
      Nathan Goodyear on 04 Feb 14
       
      visceral and abdominal adiposity are biologically different and thus the risks associated with the two are different.
    • Nathan Goodyear
      Nathan Goodyear on 04 Feb 14
       
      yet low T is associated with an increase in visceral adiposity--confusing!
  • testosterone therapy decreases SHBG
  • testosterone is inversely associated with total cholesterol, LDL cholesterol and triglyceride (Tg) levels, but positively associated with HDL cholesterol levels, even if adjusted for confounders
  • Although observational studies show a consistent association of low testosterone with adverse lipid profiles, whether testosterone therapy exerts beneficial effects on lipid profiles is less clear
  • Whereas testosterone-induced decreases in total cholesterol, LDL cholesterol and Lpa are expected to reduce cardiovascular risk, testosterone also decreases the levels of the cardio-protective HDL cholesterol. Therefore, the net effect of testosterone therapy on cardiovascular risk remains uncertain.
  • data have not shown evidence that testosterone causes prostate cancer, or that it makes subclinical prostate cancer grow
  • compared with otherwise healthy young men with organic androgen deficiency, there may be increased risks in older, obese men because of comorbidities and of decreased testosterone clearance
  • recent evidence that fat accumulation may be oestradiol-, rather than testosterone-dependent
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JISSN | Full text | International Society of Sports Nutrition position stand: creatine ... - 0 views

www.jissn.com/6 creatine sports nutrition exercise
shared by Nathan Goodyear on 27 Jan 14 - No Cached
  • the energy supplied to rephosphorylate adenosine diphosphate (ADP) to adenosine triphosphate (ATP) during and following intense exercise is largely dependent on the amount of phosphocreatine (PCr) stored in the muscle
  • Creatine is chemically known as a non-protein nitrogen
  • It is synthesized in the liver and pancreas from the amino acids arginine, glycine, and methionine
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  • Approximately 95% of the body's creatine is stored in skeletal muscle
  • About two thirds of the creatine found in skeletal muscle is stored as phosphocreatine (PCr) while the remaining amount of creatine is stored as free creatine
  • The body breaks down about 1 – 2% of the creatine pool per day (about 1–2 grams/day) into creatinine in the skeletal muscle
  • The magnitude of the increase in skeletal muscle creatine content is important because studies have reported performance changes to be correlated to this increase
  • "loading" protocol. This protocol is characterized by ingesting approximately 0.3 grams/kg/day of CM for 5 – 7 days (e.g., ≃5 grams taken four times per day) and 3–5 grams/day thereafter [18,22]. Research has shown a 10–40% increase in muscle creatine and PCr stores using this protocol
  • Additional research has reported that the loading protocol may only need to be 2–3 days in length to be beneficial, particularly if the ingestion coincides with protein and/or carbohydrate
  • A few studies have reported protocols with no loading period to be sufficient for increasing muscle creatine (3 g/d for 28 days)
  • Cycling protocols involve the consumption of "loading" doses for 3–5 days every 3 to 4 weeks
  • Most of these forms of creatine have been reported to be no better than traditional CM in terms of increasing strength or performance
  • Recent studies do suggest, however, that adding β-alanine to CM may produce greater effects than CM alone
  • These investigations indicate that the combination may have greater effects on strength, lean mass, and body fat percentage; in addition to delaying neuromuscular fatigue
  • creatine phosphate has been reported to be as effective as CM at improving LBM and strength
  • Green et al. [24] reported that adding 93 g of carbohydrate to 5 g of CM increased total muscle creatine by 60%
  • Steenge et al. [23] reported that adding 47 g of carbohydrate and 50 g of protein to CM was as effective at promoting muscle retention of creatine as adding 96 g of carbohydrate.
  • It appears that combining CM with carbohydrate or carbohydrate and protein produces optimal results
  • Studies suggest that increasing skeletal muscle creatine uptake may enhance the benefits of training
  • Nearly 70% of these studies have reported a significant improvement in exercise capacity,
  • Long-term CM supplementation appears to enhance the overall quality of training, leading to 5 to 15% greater gains in strength and performance
  • Nearly all studies indicate that "proper" CM supplementation increases body mass by about 1 to 2 kg in the first week of loading
  • short-term adaptations reported from CM supplementation include increased cycling power, total work performed on the bench press and jump squat, as well as improved sport performance in sprinting, swimming, and soccer
  • Long-term adaptations when combining CM supplementation with training include increased muscle creatine and PCr content, lean body mass, strength, sprint performance, power, rate of force development, and muscle diameter
  • subjects taking CM typically gain about twice as much body mass and/or fat free mass (i.e., an extra 2 to 4 pounds of muscle mass during 4 to 12 weeks of training) than subjects taking a placebo
  • The gains in muscle mass appear to be a result of an improved ability to perform high-intensity exercise via increased PCr availability and enhanced ATP synthesis, thereby enabling an athlete to train harder
  • there is no evidence to support the notion that normal creatine intakes (< 25 g/d) in healthy adults cause renal dysfunction
  • no long-term side effects have been observed in athletes (up to 5 years),
  • One cohort of patients taking 1.5 – 3 grams/day of CM has been monitored since 1981 with no significant side effects
  • Nathan Goodyear on 27 Jan 14
     
    Nice review of the data, up to the publication date, on creatine.
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Effects of testosterone on lean mass gain in elderly men: systemati... - PubMed - NCBI - 0 views

www.ncbi.nlm.nih.gov/...25637335 Testosterone men male hormone muscle mass fat mass
shared by Nathan Goodyear on 02 Feb 15 - No Cached
  • Nathan Goodyear on 02 Feb 15
     
    Meta-analysis finds that Testosterone therapy in men over 60 increased lean mass and decreased fat mass.
41More

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
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  • 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
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Changes in fat and lean body mass during androgen-de... [Urology. 2004] - PubMed - NCBI - 0 views

www.ncbi.nlm.nih.gov/...15072892 androgen deprivation therapy men male body composition hormone hormones Testosterone low T fat mass lean muscle prostate cancer
shared by Nathan Goodyear on 03 Mar 14 - No Cached
  • Nathan Goodyear on 03 Mar 14
     
    Androgen deprivation therapy resulted in an 11% increase in fat mass and just under 4% decrease in lean muscle mass in men.  
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High aromatase activity in hypogonadal men is associated with higher spine bone mineral... - 0 views

www.ncbi.nlm.nih.gov/...26142101 aromatase activity hypogonadal men low T low Testosterone fat obesity obese lean body mass muscle BMD men male hormoens
shared by Nathan Goodyear on 06 Jul 15 - No Cached
  • Nathan Goodyear on 06 Jul 15
     
    Only abstract available here--high Estradiol:Testosterone, thus high aromatase activity, increased abdominal fat and reduced lean muscle mass.  The authors also reported an higher bone mineral density, but that pales in the comparison of the metabolic dysfunction of high fat and low muscle mass causes.
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Predictors of skeletal muscle mass in elderly men and women - 0 views

www.sciencedirect.com/...S0047637498001304 Testosterone free Testosterone muscle muscle mass men women male female hormone hormones
shared by Nathan Goodyear on 05 Mar 15 - No Cached
  • Nathan Goodyear on 05 Mar 15
     
    Study of men and women finds that low free Testosterone, physical activity, and IGF1 is associated with muscle mass in men; no such relationship between sex hormone and muscle mass in women was found.
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JAMA Network | JAMA | Association of All-Cause Mortality With Overweight and Obesity Us... - 0 views

jama.jamanetwork.com/article.aspx obese obesity overweight mortality
shared by Nathan Goodyear on 02 Jan 13 - No Cached
  • Nathan Goodyear on 02 Jan 13
     
    Don't get to excited about this article.  It is just a meta-analysis.  Second, they looked at BMI and BMI is a notoriously bad estimater of muscle mass versus fat content.  I am the perfect example, my BMI has me as obese, yet my measured fat % is 16%.   My read on this, is most of the individuals that are "overweight" are actually at a health weight with a higher muscle mass percentage not picked up with the BMI measurement.
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Testosterone restores insulin sensitivity in patients with diabetes and hypogonadism | ... - 0 views

www.healio.com/...with-diabetes-and-hypogonadism testosterone insulin sensitivity diabetes resistance low T hypogonadotrophic hypogonadism GLUT4 DHT fat mass lean muscle inflammation men male hormone hormones
shared by Nathan Goodyear on 19 May 14 - No Cached
  • Nathan Goodyear on 19 May 14
     
    This is the abstract from oral presentation at AACE in Las Vegas from May.  Small study finds reduction in fat mass, increase in muscle mass, increase in insulin sensitivity, and reduction in inflammation signaling with Testosterone therapy in men with low Testosterone.  These men were type 2 diabetics.  This is consistent with prior published literature.  However, men without diabetes, this association is hard to reproduce. The degree of glucose control also effects the response to Testosterone therapy i.e. the worse the glucose control, the more the response from Testosterone.   Also of note, those men with hypogonatrophic hypogonadism had decreased insulin receptor expression, decreased insulin sensitivity, and decreased GLUT-4 expression versus eugonadal men.  Remember from prior studies, it is the conversion of Testosterone to DHT that increases GLUT-4 transcription, translocation, and expression.
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Effect of Testosterone Treatment on Glucose Metabolism in men With Type 2 Diabetes: A R... - 0 views

care.diabetesjournals.org/...dc13-2845.abstract diabetes type II diabetes low T Testosterone glucose insulin metabolism men male hormone hormones HOMA-IR fat mass lean
shared by Nathan Goodyear on 15 May 14 - No Cached
  • Nathan Goodyear on 15 May 14
     
    Study finds no improvement with glucose control in diabetics.  This study looked at moderately controlled diabetes. Studies have previously shown that poorly controlled diabetes definitely benefits more than those with more mild glucose control problems.  Additionally, the Testosterone levels in this study would not have met the definition of low T by other studies.  So, the question is did these men need T?  Second, did the authors design the study long enough to see changes in the insulin sensitivity and glucose control?  Abstract only available and thus I don't have access to that information.  Third, and this might support the 2nd point, increased lean mass and decreased fat mass was found.  This points to positive metabolic change.  Would this have, given more time, resulted in improved glucose control? No change in visceral adiposity was seen.  This finding, also, is not new.  Testosterone therapy does not improve visceral adiposity.  Though, increasing fat adiposity, low Testosterone, and associated increase in systemic inflammatory cytokine production results in visceral adiposity, Testosterone therapy does reverse the visceral adiposity.  
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Abstract 3608: Lipoprotein (a) Cholesterol, But Not Lp(a) Mass, Is An Independent Predi... - 0 views

circ.ahajournals.org/...II_818-c Lp(a) Lp(a) mass lipoprotein(a) lipoprotein(a) mass heart health cardiovascular disease risk
shared by Nathan Goodyear on 26 Aug 14 - No Cached
  • Nathan Goodyear on 26 Aug 14
     
    Lipoprotein (a) cholesterol is a better predictor of CAD and CVD events than Lipoprotein (a) mass.
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Saccharomyces boulardii Administration Changes Gut Microbiota and Reduces Hepatic Steat... - 0 views

mbio.asm.org/...e01011-14.long saccharomyces boulardii gut gut flora gut microbiota obesity inflammation fatty liver diabetes overweight fat mass
shared by Nathan Goodyear on 05 Jun 16 - No Cached
  • Nathan Goodyear on 05 Jun 16
     
    Saccharomyces boulardii found to reduce weight, fat mass, fatty liver, and inflammation in mice diabetes and obesity models.
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Fat-free mass index and fat mass index percentiles in Caucasians aged 1898 y - 0 views

www.nature.com/...0802037a.html FMI FFMI body composition BMI fat mass index
shared by Nathan Goodyear on 27 Jul 16 - No Cached
  • BMI is the sum of FFMI+FMI
  • FMI were significantly higher in elderly subjects as compared to younger ones
  • During menopause and aging39,40 changes in FFM and FM are not adequately picked up by changes in BMI
  • ...8 more annotations...
  • One advantage of FMI, as compared to the BMI concept, is that it amplifies the relative effect of aging on body fat
  • We believe that the definition of obesity based on relative body fat (ie percentage) remains of great value for the definition of obesity. However, in a situation in which a patient is losing weight without substantially changing his/her relative body fat (as is the case with crash diets), the calculation of FMI will quantitatively reveal the amount of body fat store lost.
  • high sensitivity of FMI (respectively FFMI) to a slight change of body fat stores
  • Sarcopenic obesity has been defined as a low FFM associated with a high body fat
  • relative FFM lower than 73% (ie a relative body fat greater than 27%) in men and a FFM lower than 62% (ie a body fat greater than 38%) in women.
  • FMIs greater than 8.2 kg/m2 in men and 11.8 kg/m2 in women would define the 'overfat' status (rather than the overweight range) in terms of fat mass
  • In young women, FMI averaged 5.5 kg/m2 (range 5th-95th percentile: 3.5-8.7 kg/m2) ie 38% higher than in males
  • the average FMI for young men was 4.0 kg/m2
  • Nathan Goodyear on 27 Jul 16
     
    good review of FMI, FFMI, and BMI.
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Comparison of Liquid Chromatography-Tandem Mass Spectrometry, RIA, and ELISA Methods fo... - 0 views

cebp.aacrjournals.org/...292.long mass spectrometry ELISA hormone hormones estrogen estrogen metabolite urinary
shared by Nathan Goodyear on 23 Jun 12 - No Cached
  • Nathan Goodyear on 23 Jun 12
     
    Mass Spectrometry better than RIA and ELISA for urinary estrogen metabolite testing.
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Comparison of Sex Steroid Measurements in Men by Immunoassay versus Mass Spectroscopy a... - 0 views

www.ncbi.nlm.nih.gov/...PMC2636568 MS mass spectroscopy immunoassay hormone hormones measurement measurements bone mineral density
shared by Nathan Goodyear on 24 Jun 12 - No Cached
  • Nathan Goodyear on 24 Jun 12
     
    Mass Spectroscopy proves to be better test, specifically specificity, in men due to low Estradiol levels.  This study compared MS to Immunoassay.
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Higher Testosterone Levels Are Associated with Less Loss of Lean Body Mass in Older Men - 0 views

jcem.endojournals.org/...3855.abstract testosterone levels body mass muscle
shared by Nathan Goodyear on 22 Dec 11 - No Cached
  • Nathan Goodyear on 22 Dec 11
     
    Testosterone shown to slow loss of lean body mass, also known as muscle.
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Metabolic effects of testosterone replacement therapy on hypogonadal men with type 2 di... - 0 views

www.ajandrology.com/article.asp Testosterone therapy diabetes lipids glucose triglycerides men male hormone hormones
shared by Nathan Goodyear on 17 Jan 14 - No Cached
  • up to 40% of men with T2DM have testosterone deficiency
  • Among diabetic patients, a reduction in sex hormone binding globulin levels induced by insulin resistance leads to a further decline of testosterone levels
  • low bioavailable testosterone concentration was related to decreased lean body mass and muscle strength
  • ...13 more annotations...
  • Testosterone deficiency has a high prevalence in men with T2DM, and it is also associated with impaired insulin sensitivity, increased percentage body fat, central obesity, dyslipidemia, hypertension and cardiovascular diseases (CVD)
  • A meta-analysis of four randomized controlled trials (RCTs) showed that TRT seemed to improve glycemic control as well as fat mass in T2DM subjects with low testosterone levels and sexual dysfunction.
  • testosterone administration could increase muscle mass and strength
  • Insulin stimulates glucose uptake into muscle and adipose tissue via the Glut4 glucose transporter isoform. When insulin activates signaling via the insulin receptor, Glut4 interacts with insulin receptor substrate 1 to initialize intracellular signaling and facilitate glucose transportation into the cell
  • The benefits of TRT on glucose metabolism can mainly be explained by its influence on the insulin signaling pathway
  • Insulin resistance as assessed by, which is calculated from the equation (If*Gf/22.5, where If is fasting insulin and Gf is fasting glucose), was definitely improved by TRT after testosterone administration in three studies
  • Testosterone was observed to elevate the expression levels and stimulate translocation of Glut4 in cultured skeletal muscle cells and to upregulate Glut4 by activating insulin receptor signaling pathways in neonatal rats
  • These effects were inhibited by a dihydrotestosterone (DHT) blocker, indicating that glucose uptake may correlate with conversion of testosterone to DHT and activation of the androgen receptor.
  • TRT reduced triglyceride levels
  • TRT has been reported to have a positive effect in the decrease of total and LDL cholesterol levels and triglycerides in hypogonadal men
  • a recent meta-analysis showed that statins could significantly lower testosterone concentrations.
  • Epidemiological studies have found a negative relationship between testosterone levels and typical cardiovascular risk markers, such as body mass index, waist circumference, visceral adiposity and carotid intima-media thickness.
  • Testosterone treatment was shown to raise hemoglobin, hematocrit and thromboxane, all of which might give rise to CVD
  • Nathan Goodyear on 17 Jan 14
     
    Low Testosterone is a very significant problem in men with type II Diabetes.  Estimated to reach 40%, likely much higher.  They based these estimates only on T levels and sexual symptoms. Testosterone improves glycemic control primarily through Increased transcription and transloction of GLUT4 insulin receptors to the cell surface.  Inflammation reduction is also a mechanism.  Testosteorne lowers Triglycerides in the traditional lipid profile.  Studies are mixed on the other aspects of  lipids.  
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Muscle Mass Index As a Predictor of Longevity in Older Adults - The American Journal of... - 0 views

www.amjmed.com/...fulltext muscle mass mortality exercise health wellness longevity
shared by Nathan Goodyear on 19 Jul 14 - No Cached
  • Nathan Goodyear on 19 Jul 14
     
    Higher muscle mass associated with lower mortality in older adults.  so many focus on cardio and forget about resistance training.
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