Group items tagged

multiple preclinical studies have suggested that DHA and/or EPA supplementation may have potential benefit through a multitude of diverse, but complementary mechanisms

pre-injury dietary supplementation with fish oil effectively reduces post-traumatic elevations in protein oxidation

The benefits of pre-traumatic DHA supplementation have not only been independently confirmed,[150] but DHA supplementation has been shown to significantly reduce the number of swollen, disconnected and injured axons when administered following traumatic brain injury.

DHA has provided neuroprotection in experimental models of both focal and diffuse traumatic brain injury

potential mechanisms of neuroprotection, in addition to DHA and EPA's well-established anti-oxidant and anti-inflammatory properties

Despite abundant laboratory evidence supporting its neuroprotective effects in experimental models, the role of dietary DHA and/or EPA supplementation in human neurological diseases remains uncertain

Several population-based, observational studies have suggested that increased dietary fish and/or omega-3 polyunsaturated fatty acid consumption may reduce risk for ischemic stroke in several populations

Randomized control trials have also demonstrated significant reductions in ischemic stroke recurrence,[217] relative risk for ischemic stroke,[2] and reduced incidence of both symptomatic vasospasm and mortality following subarachnoid hemorrhage

Clinical trials in Alzheimer's disease have also been largely ineffective

The clinical evidence thus far appears equivocal

curcumin has gained much attention from Western researchers for its potential therapeutic benefits in large part due to its potent anti-oxidant[128,194,236] and anti-inflammatory properties

Curcumin is highly lipophilic and crosses the blood-brain barrier enabling it to exert a multitude of different established neuroprotective effects

in the context of TBI, a series of preclinical studies have suggested that pre-traumatic and post-traumatic curcumin supplementation may bolster the brain's resilience to injury and serve as a valuable therapeutic option

Curcumin may confer significant neuroprotection because of its ability to act on multiple deleterious post-traumatic, molecular cascades

studies demonstrated that both pre- and post-traumatic curcumin administration resulted in a significant reduction of neuroinflammation via inhibition of the pro-inflammatory molecules interleukin 1β and nuclear factor kappa B (NFκB)

no human studies have been conducted with respect to the effects of curcumin administration on the treatment of TBI, subarachnoid or intracranial hemorrhage, epilepsy or stroke

studies have demonstrated that resveratrol treatment reduces brain edema and lesion volume, as well as improves neurobehavioral functional performance following TBI

green tea consumption or supplementation with its derivatives may bolster cognitive function acutely and may slow cognitive decline

At least one population based study, though, did demonstrate that increased green tea consumption was associated with a reduced risk for Parkinson's disease independent of total caffeine intake

a randomized, placebo-controlled trial demonstrated that administration of green tea extract and L-theanine, over 16 weeks of treatment, improved indices of memory and brain theta wave activity on electroencephalography, suggesting greater cognitive alertness

Other animal studies have also demonstrated that theanine, another important component of green tea extract, exerts a multitude of neuroprotective benefits in experimental models of ischemic stroke,[63,97] Alzheimer's disease,[109] and Parkinson's disease

Theanine, like EGCG, contains multiple mechanisms of neuroprotective action including protection from excitotoxic injury[97] and inhibition of inflammation

potent anti-oxidant EGCG which is capable of crossing the blood-nerve and blood-brain barrier,

Epigallocatechin-3-gallate also displays neuroprotective properties

More recent research has suggested that vitamin D supplementation and the prevention of vitamin D deficiency may serve valuable roles in the treatment of TBI and may represents an important and necessary neuroprotective adjuvant for post-TBI progesterone therapy

Progesterone is one of the few agents to demonstrate significant reductions in mortality following TBI in human patients in preliminary trials

in vitro and in vivo studies have suggested that vitamin D supplementation with progesterone administration may significantly enhance neuroprotection

Vitamin D deficiency may increase inflammatory damage and behavioral impairment following experimental injury and attenuate the protective effects of post-traumatic progesterone treatment.[37]

emerging evidence has suggested that daily intravenous administration of vitamin E following TBI significantly decreases mortality and improves patient outcomes

high dose vitamin C administration following injury stabilized or reduced peri-lesional edema and infarction in the majority of patients receiving post-injury treatment

it has been speculated that combined vitamin C and E therapy may potentiate CNS anti-oxidation and act synergistically with regards to neuroprotection

one prospective human study has found that combined intake of vitamin C and E displays significant treatment interaction and reduces the risk of stroke

Pycnogenol has demonstrated the ability to slow or reduce the pathological processes associated with Alzheimer's disease

Pcynogenol administration, in a clinical study of elderly patients, led to improved cognition and reductions in markers of lipid peroxidase

One other point of consideration is that in neurodegenerative disease states like Alzheimer's disease and Parkinson's disease, where there are high levels of reactive oxygen species generation, vitamin E can tend to become oxidized itself. For maximal effectiveness and to maintain its anti-oxidant capacity, vitamin E must be given in conjunction with other anti-oxidants like vitamin C or flavonoids

These various factors might account for the null effects of alpha-tocopherol supplementation in patients with MCI and Alzheimer's disease

preliminary results obtained in a pediatric population have suggested that post-traumatic oral creatine administration (0.4 g/kg) given within four hours of traumatic brain injury and then daily thereafter, may improve both acute and long-term outcomes

Acutely, post-traumatic creatine administration seemed to reduce duration of post-traumatic amnesia, length of time spent in the intensive care unit, and duration of intubation

At three and six months post-injury, subjects in the creatine treatment group demonstrated improvement on indices of self care, communication abilities, locomotion, sociability, personality or behavior and cognitive function when compared to untreated controls

patients in the creatine-treatment group were less likely to experience headaches, dizziness and fatigue over six months of follow-up

CNS creatine is derived from both its local biosynthesis from the essential amino acids methionine, glycine and arginine

Studies of patients with CNS creatine deficiency and/or murine models with genetic ablation of creatine kinase have consistently demonstrated significant neurological impairment in the absence of proper creatine, phosphocreatine, or creatine kinase function; thus highlighting its functional importance

chronic dosing may partially reverse neurological impairments in human CNS creatine deficiency syndromes

Several studies have suggested that creatine supplementation may also reduce oxidative DNA damage and brain glutamate levels in Huntington disease patients

Another study highlighted that creatine supplementation marginally improved indices of mood and reduced the need for increased dopaminergic therapy in patients with Parkinson's disease

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

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

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

These data suggest that PAA may show a therapeutic advantage to blood cancers vs solid tumors because of the communication between tumor cells and blood plasma

These results strongly suggest that the mechanism of PAA killing of MM cells is indeed iron-dependent

These results suggest that PAA administration in SMM may be able to prevent progression to symtomatic MM

A recent study by Yun and colleagues demonstrated that vitamin C selectively kills KRAS and BRAF mutant colorectal cancer cells by targeting GAPDH, but spares normal cells

RAS family genes show the most frequent mutations in MM. KRAS, NRAS and BRAF are mutated in 22%, 20% and 7% of MM samples

the disease stage rather than the mutation of RAS and/or BRAF is the major predictive factor for PAA sensitivity in MM treatment

Other molecular mechanisms including ATP depletion and ATM-AMPK signaling have been reported to explain PAA-induced cell death

our pilot study also suggested that PAA could overcome drug resistance to bortezomib in MM cells

Our findings complement reported studies and further address the mechanism of action using clinical samples in which we observed that PAA killed tumor cells with high iron content, suggesting that iron might be the initiator of PAA cytotoxicity

combination of PAA with standard therapeutic drugs, such as melphalan, may significantly reduce the dose of melphalan needed

Combined treatment of reduced dose melphalan with PAA achieved a significantly longer progression-free survival than the same dose of melphalan alone.

These data also suggest that the bone marrow suppression induced by high-dose melphalan can be ameliorated by the combination of PAA with lower dose of melphalan because of the lack of toxicity of PAA on normal cells with low iron content.

if creatinine clearance is <30 mL/min, high dose ascorbic acid should be not administrated.

In MM preclinical and clinical studies, ascorbate was used as an adjunct drug and showed controversial results (Harvey et al., 2009, Perrone et al., 2009, Held et al., 2013, Sharma et al., 2012, Nakano et al., 2011, Takahashi, 2010, Sharma et al., 2009, Qazilbash et al., 2008). However, none of these tests used pharmacological doses of ascorbate and intravenous administration

Multiple myeloma (MM) is a plasma cell neoplasm.

Cameron and Pauling reported that high doses of vitamin C increased survival of patients with cancer

pharmacologically dosed ascorbic acid (PAA) 50–100 g (Chen et al., 2008, Padayatty et al., 2004, Hoffer et al., 2008, Padayatty et al., 2006, Welsh et al., 2013), administered intravenously, has potent anti-cancer activity and its role as anti-cancer therapy is being studied at the University of Iowa and in other centers

In the presence of catalytic metal ions like iron, PAA administered intravenously exerts pro-oxidant effects leading to the formation of highly reactive oxygen species (ROS), resulting in cell death

the labile iron pool (LIP) is significantly elevated in MM cells

The survival of CD138+ cells in vitro was significantly decreased following PAA treatment in all 9 MM

In contrast, no significant change of cell viability was observed in CD138− BM cells from the same patients

The same effect of PAA was also observed in the SMM patients

no response to PAA was detected in CD138+ cells from the 2 MGUS patients

the combination of melphalan plus PAA showed greater tumor burden reduction than each drug alone, suggesting a synergistic activity between these two drugs

Both catalase and NAC protect cells from oxidative damage

cells pretreated with NAC and catalase became resistant to PAA even at high doses

adding deferoxamine (DFO), an iron chelator, to OCI-MY5 cells before PAA treatment was also sufficient to prevent PAA-induced cellular death

iron is essential for PAA to achieve its anti-cancer activity

PAA induced early necrosis (Fig. 3Fig. 3A, 60 min) followed by late apoptosis

results further indicated that PAA induced mitochondria-mediated apoptosis

PAA by reacting with LIP and generating ROS induces mitochondria-mediated apoptosis in which AIF1 cleavage is important for cell death.

ROS and H2O2 are well known factors mediating PAA-induced cancer cell death

PAA was sensitive to all 9 MMs and 2 SMMs

The starting point for innate immunity activation is the recognition of conserved structures of bacteria, viruses, and fungal components through pattern-recognition receptors

TLRs are PRRs that recognize microbe-associated molecular patterns

TLRs are transmembrane proteins containing extracellular domains rich in leucine repeat sequences and a cytosolic domain homologous to the IL1 receptor intracellular domain

The major proinflammatory mediators produced by the TLR4 activation in response to endotoxin (LPS) are TNFα, IL1β and IL6, which are also elevated in obese and insulin-resistant patients

Obesity, high-fat diet, diabetes, and NAFLD are associated with higher gut permeability leading to metabolic endotoxemia.

Probiotics, prebiotics, and antibiotic treatment can reduce LPS absorption

LPS promotes hepatic insulin resistance, hypertriglyceridemia, hepatic triglyceride accumulation, and secretion of pro-inflammatory cytokines promoting the progression of fatty liver disease.

In the endothelium, LPS induces the expression of pro-inflammatory, chemotactic, and adhesion molecules, which promotes atherosclerosis development and progression.

In the adipose tissue, LPS induces adipogenesis, insulin resistance, macrophage infiltration, oxidative stress, and release of pro-inflammatory cytokines and chemokines.

the gut microbiota has been recently proposed to be an environmental factor involved in the control of body weight and energy homeostasis by modulating plasma LPS levels

dietary fats alone might not be sufficient to cause overweight and obesity, suggesting that a bacterially related factor might be responsible for high-fat diet-induced obesity.

This was accompanied in high-fat-fed mice by a change in gut microbiota composition, with reduction in Bifidobacterium and Eubacterium spp.

n humans, it was also shown that meals with high-fat and high-carbohydrate content (fast-food style western diet) were able to decrease bifidobacteria levels and increase intestinal permeability and LPS concentrations

it was demonstrated that, more than the fat amount, its composition was a critical modulator of ME (Laugerette et al. 2012). Very recently, Mani et al. (2013) demonstrated that LPS concentration was increased by a meal rich in saturated fatty acids (SFA), while decreased after a meal rich in n-3 polyunsaturated fatty acids (n-3 PUFA).

this effect seems to be due to the fact that some SFA (e.g., lauric and mystiric acids) are part of the lipid-A component of LPS and also to n-3 PUFA's role on reducing LPS potency when substituting SFA in lipid-A

these experimental results suggest a pivotal role of CD14-mediated TLR4 activation in the development of LPS-mediated nutritional changes.

This suggests a link between gut microbiota, western diet, and obesity and indicates that gut microbiota manipulation can beneficially affect the host's weight and adiposity.

endotoxemia was independently associated with energy intake but not fat intake in a multivariate analysis

in vitro that endotoxemia activates pro-inflammatory cytokine/chemokine production via NFκB and MAPK signaling in preadipocytes and decreased peroxisome proliferator-activated receptor γ activity and insulin responsiveness in adipocytes.

T2DM patients have mean values of LPS that are 76% higher than healthy controls

LPS-induced release of glucagon, GH and cortisol, which inhibit glucose uptake, both peripheral and hepatic

LPSs also seem to induce ROS-mediated apoptosis in pancreatic cells

Recent evidence has been linking ME with dyslipidemia, increased intrahepatic triglycerides, development, and progression of alcoholic and nonalcoholic fatty liver disease

The hepatocytes, rather than hepatic macrophages, are the cells responsible for its clearance, being ultimately excreted in bile

All the subclasses of plasma lipoproteins can bind and neutralize the toxic effects of LPS, both in vitro (Eichbaum et al. 1991) and in vivo (Harris et al. 1990), and this phenomenon seems to be dependent on the number of phospholipids in the lipoprotein surface (Levels et al. 2001). LDL seems to be involved in LPS clearance, but this antiatherogenic effect is outweighed by its proatherogenic features

LPS produces hypertriglyceridemia by several mechanisms, depending on LPS concentration. In animal models, low-dose LPS increases hepatic lipoprotein (such as VLDL) synthesis, whereas high-dose LPS decreases lipoprotein catabolism

When a dose of LPS similar to that observed in ME was infused in humans, a 2.5-fold increase in endothelial lipase was observed, with consequent reduction in total and HDL. This mechanism may explain low HDL levels in ‘ME’ and other inflammatory conditions such as obesity and metabolic syndrome

It is known that the high-fat diet and the ‘ME’ increase intrahepatic triglyceride accumulation, thus synergistically contributing to the development and progression of alcoholic and NAFLD, from the initial stages characterized by intrahepatic triglyceride accumulation up to chronic inflammation (nonalcoholic steatohepatitis), fibrosis, and cirrhosis

On the other hand, LPS activates Kupffer cells leading to an increased production of ROS and pro-inflammatory cytokines like TNFα

high-fat diet mice presented with ME, which positively and significantly correlated with plasminogen activator inhibitor (PAI-1), IL1, TNFα, STAMP2, NADPHox, MCP-1, and F4/80 (a specific marker of mature macrophages) mRNAs

prebiotic administration reduces intestinal permeability to LPS in obese mice and is associated with decreased systemic inflammation when compared with controls

Cani et al. also found that high-fat diet mice presented with not only ME but also higher levels of inflammatory markers, oxidative stress, and macrophage infiltration markers

This suggests that important links between gut microbiota, ME, inflammation, and oxidative stress are implicated in a high-fat diet situation

high-fat feeding is associated with adipose tissue macrophage infiltration (F4/80-positive cells) and increased levels of chemokine MCP-1, suggesting a strong link between ME, proinflammatory status, oxidative stress, and, lately, increased CV risk

LPS has been shown to promote atherosclerosis

markers of systemic inflammation such as circulating bacterial endotoxin were elevated in patients with chronic infections and were strong predictors of increased atherosclerotic risk

As a TLR4 ligand, LPS has been suggested to induce atherosclerosis development and progression, via a TLR4-mediated inflammatory state.

An association between testosterone and WBC count was not observed

These findings are consistent with the hypothesis that in men higher androgen concentration is anti-inflammatory, and higher estrogen concentration is pro-inflammatory.

the probability of elevated CRP concentrations (≥ 3 mg/L) decreased with higher total and calculated free testosterone concentrations, while the probability increased with higher total and calculated free estradiol concentrations

there is ample evidence supporting the immunosuppressive effect of androgens

The incidence of autoimmune diseases is higher in androgen-deficient men

Studies have shown that the induction of hypogonadism in older men is followed by a significant increase in IL-6 concentrations (Khosla et al. 2002), a potent stimulator of inflammation, and that activation of the androgen receptor exerts a direct anti-inflammatory effect

It has been suggested that the mechanisms for the immunosuppressive effect of androgens could be either a direct effect on the expression of inflammatory genes (Bellido et al. 1995; Asirvatham et al. 2006), or an indirect effect through inhibition of nuclear factor-kB activation

Estradiol is the major biologically active estrogen, and about 80% is formed in adult men from the aromatization of testosterone primarily in the adipose tissue

estrogen can stimulate the transcription factor C/EBP-β, which is involved in CRP transcription

Most prior cross-sectional studies have observed inverse associations between androgen concentrations and inflammatory biomarkers

A recent study in Chinese men showed that lower concentrations of total and calculated free testosterone were associated with higher CRP concentration

Data from the Boston Area Community Health Survey also reported inverse associations between testosterone and CRP concentrations

Total testosterone was inversely associated with WBC count (Tang et al. 2007; Schneider et al. 2009; Brand et al. 2012), but calculated free testosterone was not associated with WBC

The first trial found a decrease in CRP, interleukin-1β (IL-1β), and tumor necrosis factor-α (TNFα) but no changes in IL-6 and IL-10 concentrations between the active treatment and placebo arms

the majority of studies in the literature have not observed statistically significant associations between estradiol and inflammatory biomarkers in men, although several of them observed point estimates in the positive direction

total testosterone and estradiol compete for binding to SHBG, and seem to have opposite effects on the concentration of inflammatory biomarkers

A small randomized controlled trial of estrogen replacement therapy in prostate cancer patients showed an increase in CRP in the active treatment group versus the comparator group

Obese men are known to have lower androgen concentrations compared to their normal-weight counterparts

The strongest suggestion of an interaction was the inverse association between androstanediol glucuronide and CRP concentrations in obese participants, while the association was positive in the non-obese

A recent Chinese cross-sectional study observed stronger inverse associations between total testosterone and CRP concentrations in individuals with a BMI of 27.5 kg/m2 or greater

our results suggest that total and calculated free testosterone are modestly inversely associated with CRP concentrations, and that total and calculated free estradiol are modestly positively associated with CRP and WBC

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

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

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

High density level of PGR in the TE was an independent prognostic factor for CF.

Our large-sized study demonstrates a wide distribution of PGR in stromal and epithelial cells of both benign and malignant prostate tissue

there seems to be a general agreement of PGR presence in the stromal cells of PCa

In line with our findings, several have also reported a high PGR expression in TE of PCa [9,10,23,25]. In contrast, others have demonstrated a total lack of PGR expression in TE

the actions of progesterone are tissue specific

In our work univariate analysis demonstrated a high PGR expression in TS to be associated with clinical failure in PCa patients. So far we have not yet demonstrated the mechanism underlying this association

Several non-genomic proliferative actions of progesterone have been proposed in tumor cells of other organs, including breast [35–37], astrocytoma [38] and osteosarcoma [39] cell lines. However, such results are contradicted by suggestions of anti-proliferative actions of progesterone in endometrial cancer

Yu et al. found PGR to be negatively regulating stromal cell proliferation in vitro

high PGR density level in TE was associated with CF in patients with Gleason score ≥ 7

Bonkhoff et al. have suggested progressive emergence of PGR during PCa progression and metastasis

Latil and co-workers found a decreased PGR expression in clinically localized tumors and increased PGR expression in hormone-refractory tumors, when compared with normal prostate tissue

Our findings provide further support to these findings, indicating that PGR plays a role in the pathogenesis of PCa

Ki67 and PGR in TE were correlated with CF (S3 Text), indicating an association between PGR and proliferative activity

The mechanism behind the PGR up-regulation in PCa has not yet been elucidated

The PGR is, like the glucocorticoid receptor, similar to androgen receptor with 88% sequence homology in the ligand-binding domain

progesterone induced expression of androgen receptor-regulated genes could be a potential mechanism contributing to the development of castrate resistant PCa

A possibility of different roles by the two PGR isoforms in normal prostate tissue and PCa, as is suggested for the estrogen receptors [13], must also be taken into account

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

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

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