Dehydroepiandrosterone protects low density lipoproteins against peroxidation by free radicals produced by gamma-radiolysis of ethanol-water mixtures

Anabolic Hormone Deficiencies in Heart Failure with Reduced or Preserved Ejection Fraction and Correlation with Plasma Total Antioxidant Capacity

BACKGROUND

While anabolic hormone deficit is a common finding in heart failure with reduced ejection fraction (HFrEF), few data are available in heart failure with preserved ejection fraction (HFpEF).

METHODS

Blood samples were collected for metabolic (total cholesterol, HDL cholesterol, LDL cholesterol, creatinine, and glucose) and hormonal (IGF-1, DHEA-S, TSH, fT3, fT4, and T) determination, comparing 30 patients with HFpEF and 20 patients with HFrEF. Total antioxidant capacity was evaluated by using the spectrophotometric method using the latency time in the appearance of the radical species of a chromogen (LAG, sec) as a parameter proportional to antioxidant content of the sample. Echocardiographic parameters were also assessed in the two groups.

RESULTS

A high prevalence of testosterone (32% in HFrEF and 72% in HFpEF, p < 0.05) and DHEA-S deficiencies was observed in HFpEF patients. Echocardiographic parameters did not correlate with hormone values. A significant direct correlation between T (r ² = 0.25, p < 0.05) and DHEA-S (r ² = 0.19, p < 0.05) with LAG was observed only in HFpEF.

CONCLUSION

Anabolic hormone deficiency is clearly shown in HFpEF, as already known in HFrEF. Although longitudinal studies are required to confirm the prognostic value of this observation, our data suggest different mechanisms in modulating antioxidants in the two conditions, with possible therapeutic implications.

Anabolic Hormones Deficiencies in Heart Failure With Preserved Ejection Fraction: Prevalence and Impact on Antioxidants Levels and Myocardial Dysfunction

Purpose: In heart failure with reduced ejection fraction, catabolic mechanisms have a strong negative impact on mortality and morbidity. The relationship between anabolic hormonal deficiency and heart failure with preserved ejection fraction (HFpEF) has still been poorly investigated. On the other hand, oxidative stress is recognized as a player in the pathogenesis of HFpEF. Therefore, we performed a cohort study in HFpEF aimed to (1) define the multi-hormonal deficiency prevalence in HFpEF patients; (2) investigate the relationships between hormonal deficiencies and echocardiographic indexes; (3) explore the modulatory activity of anabolic hormones on antioxidant systems. Methods: 84 patients with diagnosis of HFpEF were enrolled in the study. Plasma levels of N-terminal pro-brain natriuretic peptide, fasting glucose, insulin, lipid pattern, insulin-like growth factor-1, dehydroepiandrosterone-sulfate (DHEA-S), total testosterone (T, only in male subjects) were evaluated. Hormonal deficiencies were defined according to T.O.S.C.A. multi-centric study, as previously published. An echocardiographic evaluation was performed. Plasma total antioxidant capacity (TAC) was measured using the system metmyoglobin -H₂O₂ and the chromogen ABTS, whose radical form is spectroscopically revealed; latency time (LAG) in the appearance of ABTS• is proportional to antioxidants in sample. Results: Multiple deficiencies were discovered. DHEA-S deficiency in 87% of patients, IGF-1 in 67% of patients, T in 42%. Patients with DHEA-S deficiency showed lower levels of TAC expressed by LAG (mean ± SEM 91.25 ± 9.34 vs. 75.22 ± 4.38 s; p < 0.05). No differences between TAC in patients with or without IGF-1 deficiency were found. A trend toward high level of TAC in patients without hormonal deficiencies compared with patients with one or multiple deficiencies was found. Regarding echocardiographic parameters, Left Atrial and Left Atrial Volume Index were significantly higher in patients with low IGF-1 values (mean ± SD 90.84 ± 3.86 vs. 72.83 ± 3.78 mL; 51.03 ± 2.33 vs. 40.56 ± 2.46 mL/m², respectively; p < 0.05). Conclusions: Our study showed high prevalence of anabolic deficiencies in HFpEF. DHEA-S seems to influence antioxidant levels; IGF-1 deficiency was associated with alteration in parameters of myocardial structure and dysfunction. These data suggest a role of anabolic hormones in the complex pathophysiological mechanisms of HFpEF and could represent the basis for longitudinal studies and investigations on possible benefits of replacement therapy.

How stress mediators can cumulatively contribute to Alzheimer's disease An allostatic load approach

Allostatic load is defined as the frequent activation of the neuroendocrine, immunological, metabolic and cardiovascular systems, which makes individuals more susceptible to stress-related health problems. According to this model, physiological dysregulations start to emerge decades before diseases manifest. Consequently, stress research has shifted its attention to anticipating the degree of this dysregulation to better understand the impact of stress hormones and other biomarkers on disease progression. In view of the growing number of studies that demonstrate the influence of modifiable risk factors on cognitive decline, in addition to the effects of chronic stress mediators, the objective of the present review was to present an overview of the development of cognitive changes based on studies on stress and its mediators.

Relationship between serum DHEAS and oxidative stress levels of body mass index in healthy postmenopausal women

OBJECTIVES

Menopause is a natural step in the process of aging. Postmenopausal women have decreased levels of antioxidants and increased oxidative stress, the latter of which plays an important role in atherogenesis. The aim of the present study was to evaluate the relationship of the body mass index (BMI) with serum catalase activity, malondialdehyde (MDA), and dehydroepiandrosterone sulfate (DHEAS) levels in healthy postmenopausal women and estimate whether the MDA/DHEAS ratio is a possible marker of oxidative stress for determining cardiovascular risk in these women.

METHODS

We investigated serum catalase activity, MDA, and DHEAS levels, parity history, age, and BMI in 96 healthy postmenopausal women aged 50-82 years. The serum MDA levels and catalase activity were measured spectrophotometrically. The serum DHEAS levels were measured using an enzyme-linked immunosorbent assay. The ratio percentage of the serum DHEAS levels to serum MDA levels was designated as a biomarker for oxidative stress.

RESULTS

The mean BMI of the patients was 31.72 ± 6.16 kg/m(2) (range = 20.5-47.94). The MDA/DHEAS ratio was significantly decreased in patients with a BMI over 30 compared to that of patients with a BMI between 25 and 30 (P = 0.025). Moreover, BMI was positively correlated with serum DHEAS levels (r = 0.285, P < 0.01) and negatively correlated with the MDA/DHEAS ratio (r = -0.241, P < 0.05) in postmenopausal women. Furthermore, BMI was observed to be a potential predictor of the MDA/DHEAS ratio based on covariance analysis (P = 0.039).

CONCLUSIONS

Our results indicate that healthy, obese, postmenopausal women have a decreased MDA/DHEAS ratio. Additionally, BMI was observed to be a potential predictor of the MDA/DHEAS ratio.

Perceived stress at work is associated with lower levels of DHEA-S

BACKGROUND

It is known that long-term psychosocial stress may cause or contribute to different diseases and symptoms and accelerate aging. One of the consequences of prolonged psychosocial stress may be a negative effect on the levels of dehydroepiandrosterone (DHEA) and its sulphated metabolite dehydroepiandrosterone sulphate (DHEA-S). The aim of this study is to investigate whether levels of DHEA and DHEA-S differ in individuals who report perceived stress at work compared to individuals who report no perceived stress at work.

METHODS

Morning fasting DHEA-S and DHEA levels were measured in serum in a non-stressed group (n = 40) and a stressed group (n = 41). DHEA and DHEA-S levels were compared between the groups using ANCOVA, controlling for age.

RESULTS

The mean DHEA-S levels were 23% lower in the subjects who reported stress at work compared to the non-stressed group. Statistical analysis (ANCOVA) showed a significant difference in DHEA-S levels between the groups (p = 0.010). There was no difference in DHEA level between the groups.

CONCLUSIONS

This study indicates that stressed individual have markedly lower levels of DHEA-S. Given the important and beneficial functions of DHEA and DHEA-S, lower levels of DHEA-S may constitute one link between psychosocial stress, ill health and accelerated ageing.

Dehydroepiandrosterone-mediated stimulation of sigma-1 receptor activates Akt-eNOS signaling in the thoracic aorta of ovariectomized rats with abdominal aortic banding

OBJECTIVE

Decreased dehydroepiandrosterone (DHEA) levels are associated with endothelial dysfunction and increased cardiovascular mortality in postmenopausal women. Using ovariectomized rats, we first defined whether expression of sigma-1 receptor (Sig-1R) in the aorta is regulated following pressure overload (PO) and also after DHEA treatment. We also investigated effects of DHEA known as Sig-1R agonist on impaired Akt/endothelial nitric oxide synthase (eNOS) signaling in the thoracic aorta under PO.

RESEARCH DESIGN/METHODS

Wistar rats subjected to bilateral ovariectomy (OVX) were further treated with abdominal aortic stenosis 2 weeks later. DHEA (15 and 30 mg/kg) was administered orally once a day for 14 days starting from 2 weeks after the aortic banding.

RESULTS

Time course study indicated that expression of Sig-1R expression and eNOS decreased time dependently in the thoracic aorta from 1 to 4 weeks after PO. DHEA treatment significantly inhibited the decreased Sig-1R expression in the thoracic aorta. The DHEA treatment also significantly restored PO-induced impaired Akt phosphorylation and stimulated eNOS protein expression with concomitant increased Akt-mediated eNOS phosphorylation (Ser1177). We did not find any changes in the phosphorylation of ERK1/2 and PKCα in the aorta following PO and after treatment with DHEA.

CONCLUSION

We here reported, for the first time, that DHEA treatment induces the upregulation and stimulation of Sig-1R in the thoracic aorta that stimulate Sig-1R-mediated Akt-eNOS signaling pathways in ovariectomized rats under PO.

DHEA, important source of sex steroids in men and even more in women

A major achievement from 500 million years of evolution is the establishment of a high secretion rate of dehydroepiandrosterone (DHEA) by the human adrenal glands coupled with the indroduction of menopause which stops secretion of estrogens by the ovary. Cessation of estrogen secretion at menopause eliminates the risks of endometrial hyperplasia and cancer which would result from non-opposed estrogen stimulation during the post-menopausal years. In fact, from the time of menopause, DHEA becomes the exclusive and tissue-specific source of sex steroids for all tissues except the uterus. Intracrinology, a term coined in 1988, describes the local formation, action and inactivation of sex steroids from the inactive sex steroid precursor DHEA. Over the past 25 years most, if not all, the genes encoding the human steroidogenic and steroid-inactivating enzymes have been cloned and sequenced and their enzymatic activity characterized. The problem with DHEA, however, is that its secretion decreases from the age of 30 years and is already decreased, on average, by 60% at time of menopause. In addition, there is a large variability in the circulating levels of DHEA with some post-menopausal women having barely detectable serum concentrations of the steroid while others have normal values. Since there is no feedback mechanism controlling DHEA secretion within 'normal' values, women with low DHEA will remain with such a deficit of sex steroids for their remaining lifetime. Since there is no other significant source of sex steroids after menopause, one can reasonably believe that low DHEA is involved, in association with the aging process, in a series of medical problems classically associated with post-menopause, namely osteoporosis, muscle loss, vaginal atrophy, fat accumulation, hot flashes, skin atrophy, type 2 diabetes, memory loss, cognition loss and possibly Alzheimer's disease. A recent randomized, placebo-controlled study has shown that all the signs and symptoms of vaginal atrophy, a classical problem recognized to be due to the hormone deficiency of menopause, can be rapidly improved or corrected by local administration of DHEA without systemic exposure to estrogens. In addition, the four domains of sexual dysfucntion are improved. For the other problems of menopause, although similar large scale, randomized and placebo-controlled studies usually remain to be performed, the available evidence already strongly suggests that they could be improved, corrected or even prevented by exogenous DHEA. In men, the contribution of adrenal DHEA to the total androgen pool has been measured at 40% in 65-75-year-old men. Such data stress the necessity of blocking both the testicular and adrenal sources of androgens in order to achieve optimal benefits in prostate cancer therapy. On the other hand, the comparable decrease in serum DHEA levels observed in both sexes has less consequence in men who continue to receive a practically constant supply of testicular sex steroids during their whole life. In fact, in men, the appearance of hormone-deficiency symptoms common to women is observed at a later age and with a lower degree of severity. Consequently, DHEA replacement has shown much more easily measurable beneficial effects in women. Most importantly, despite the non-scientific and unfortunate availability of DHEA as a food supplement in the United States, a situation that discourages rigorous clinical trials on the crucial physiological and therapeutic role of DHEA, no serious adverse event related to DHEA has ever been reported in the world literature (thousands of subjects exposed) or in the monitoring of adverse events by the FDA (millions of subjects exposed), thus indicating, as expected from its known physiology, the excellent safety profile of DHEA. With today's knowledge, one can reasonably suggest that DHEA offers the promise of a safe and efficient replacement therapy for the multiple problems related to hormone deficiency after menopause without the risks associated with estrogen-based or any other treatments.

Decreased dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) concentrations in plasma of Alzheimer's disease (AD) patients

DHEA is secreted by the adrenal cortex and is also a neurosteroid. Its sulfate (DHEAS) is the most abundant steroid in circulation. The levels of both are seen to decline in concentration with age. Evidence is available for altered levels of DHEA and DHEAS in AD but is limited to relatively few studies assessing small cohorts. This study assessed plasma DHEA and DHEAS levels in AD sufferers (n=72) and compared them to age-matched controls (n=72). Plasma DHEA concentrations were significantly lower in AD patients compared to control (4.24+/-0.4 ng/ml for AD; 3.38+/-0.3 ng/ml for control, p=0.027, Mann-Whitney 1-tailed) and DHEA levels were significantly correlated to DHEAS levels in both control and AD conditions (Spearman's rho correlation coefficient=0.635 in controls and 0.467 in AD, p<or=0.01). This study highlighted a measurable difference in DHEA and DHEAS concentrations in plasma from a large cohort of patients suffering from AD when compared to age-matched controls.

Altered DHEA and DHEAS response to exercise in healthy older adults

Dehydroepiandrosterone (DHEA) and its sulfate (DHEAS) are hormones produced by the adrenal cortex that decline in concentration with age. Decreased DHEA levels are associated with age-related disease and oxidative stress but might be increased in younger adults by exercise. Studies are presented assessing the response of DHEA and DHEAS to varied-intensity exercise in older age. DHEA increased significantly in young adults (14.5 +/- 6.1 ng/ml rising to 21.1 +/- 7.5 ng/ml; p < .01), whereas DHEAS decreased significantly (2.56 +/- 1.11 microg/ml falling to 1.90 +/- 0.8 microg/ml; p < .05), after submaximal exercise. DHEA and DHEAS levels were significantly lower in older adults than in younger adults (p < .01), and there was no observed response of either hormone to exercise in older adults. Lipoprotein protein carbonylation is presented as a measure of oxidative status and significantly decreased in younger adults postexercise. Participants with higher DHEA postexercise had lower LDL protein carbonyl concentrations (Pearson's coefficient -.409, p < .05).

Antiapoptotic effects of dehydroepiandrosterone on testicular torsion/detorsion in rats

In the present study, we aimed to evaluate the effects of dehydroepiandrosterone (DHEA) on apoptosis of testicular germ cells after repair of testicular torsion in rats. Twenty-four adult male Sprague-Dawley rats were randomly divided into four groups, with six rats in each group: sham operation, torsion/detorsion (T/D), T/D + vehicle, and T/D + DHEA. Three hours before detorsion, 50 mg kg(-1) DHEA was given intraperitoneally to T/D + DHEA group. In all groups, bilateral orchiectomies were performed and both testicles were histologically examined, with apoptosis detected using the in situ DNA fragmentation [terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL)] system, with morphological damage detected using a four-level grading scale in each specimen. The testes of the sham group showed a normal histology. In T/D and T/D + vehicle groups, apoptotic spermatogonia and spermatocyte number were significantly higher than in the sham group (P < 0.01 for all). The T/D + DHEA group showed a reduction in apoptotic spermatocyte and spermatogonia number in seminiferous epithelia compared with T/D group (P < 0.01 for both). Apoptotic cell number of contralateral testes did not reveal any significant differences among these groups (P > 0.05). Specimens from T/D and T/D + vehicle had a significantly greater histological injury than sham and T/D + DHEA groups in the ipsilateral testes (P < 0.01 for both). Therefore, the results suggest that DHEA may be a protective agent for preventing apoptosis caused by testicular torsion.

Dehydroepiandrosterone stimulates endothelial proliferation and angiogenesis through extracellular signal-regulated kinase 1/2-mediated mechanisms

Dehydroepiandrosterone (DHEA) activates a plasma membrane receptor on vascular endothelial cells and phosphorylates ERK 1/2. We hypothesize that ERK1/2-dependent vascular endothelial proliferation underlies part of the beneficial vascular effect of DHEA. DHEA (0.1-10 nm) activated ERK1/2 in bovine aortic endothelial cells (BAECs) by 15 min, causing nuclear translocation of phosphorylated ERK1/2 and phosphorylation of nuclear p90 ribosomal S6 kinase. ERK1/2 phosphorylation was dependent on plasma membrane-initiated activation of Gi/o proteins and the upstream MAPK kinase because the effect was seen with albumin-conjugated DHEA and was blocked by pertussis toxin or PD098059. A 15-min incubation of BAECs with 1 nm DHEA (or albumin-conjugated DHEA) increased endothelial proliferation by 30% at 24 h. This effect was not altered by inhibition of estrogen or androgen receptors or nitric oxide production. There was a similar effect of DHEA to increase endothelial migration. DHEA also increased the formation of primitive capillary tubes of BAECs in vitro in solubilized basement membrane. These rapid DHEA-induced effects were reversed by the inhibition of either Gi/o-proteins or ERK1/2. Additionally, DHEA enhanced angiogenesis in vivo in a chick embryo chorioallantoic membrane assay. These findings indicate that exposure to DHEA, at concentrations found in human blood, causes vascular endothelial proliferation by a plasma membrane-initiated activity that is Gi/o and ERK1/2 dependent. These data, along with previous findings, define an important vascular endothelial cell signaling pathway that is activated by DHEA and suggest that this steroid may play a role in vascular function.

Dehydroepiandrosterone treatment attenuates reperfusion injury after testicular torsion and detorsion in rats

PURPOSE

We aimed to evaluate the effects of dehydroepiandrosterone (DHEA) on antioxidant enzyme activities, lipid peroxidation, and histopathologic changes in both testes after unilateral testicular torsion and detorsion.

METHODS

Twenty-four adult male Sprague-Dawley rats were randomly divided into 4 groups (n = 6 for each group): sham operation, torsion/detorsion (T/D), T/D + vehicle, and T/D + DHEA. Three hours before detorsion, 50 mg/kg DHEA was given intraperitoneally to the T/D + DHEA group. Testicular ischemia was achieved by twisting the left testis 720 degrees clockwise for 3 hours, and reperfusion was allowed for 24 hours after detorsion. In all groups, bilateral orchiectomies to determine the testicular tissue catalase (CAT) and superoxide dismutase activities and malondialdehyde (MDA) levels and histopathologic examination were performed.

RESULTS

Compared with those from the sham group, CAT activities in the ipsilateral testis obtained from the T/D group were significantly lower and MDA levels were significantly higher (P < .05 for all). Administration of DHEA prevented increases in MDA levels and decreases in CAT and superoxide dismutase activities when compared to the T/D group. Specimens from the T/D and the T/D + vehicle groups had a significantly greater histologic injury than the specimens from the sham and the T/D + DHEA groups had (P < .01 for both).

CONCLUSIONS

The results suggest that DHEA may be a protective agent for preventing biochemical and histopathologic changes related to oxidative stress in testicular injury caused by testis torsion.

Dehydroepiandrosterone protects vascular endothelial cells against apoptosis through a Galphai protein-dependent activation of phosphatidylinositol 3-kinase/Akt and regulation of antiapoptotic Bcl-2 expression

The adrenal steroid dehydroepiandrosterone (DHEA) may improve vascular function, but the mechanism is unclear. In the present study, we show that DHEA significantly increased cell viability, reduced caspase-3 activity, and protected both bovine and human vascular endothelial cells against serum deprivation-induced apoptosis. This effect was dose dependent and maximal at physiological concentrations (0.1-10 nM). DHEA stimulation of bovine aortic endothelial cells resulted in rapid and dose-dependent phosphorylation of Akt, which was blocked by LY294002, a specific inhibitor of phosphatidylinositol 3-kinase (PI3K), the upstream kinase of Akt. Accordingly, inhibition of PI3K or transfection of the cells with dominant-negative Akt ablated the antiapoptotic effect of DHEA. The induced Akt phosphorylation and subsequent cytoprotective effect of DHEA were dependent on activation of Galphai proteins, but were estrogen receptor independent, because these effects were blocked by pertussis toxin but not by the estrogen receptor inhibitor ICI182,780 or the aromatase inhibitor aminoglutethimide. Finally, DHEA enhanced antiapoptotic Bcl-2 protein expression, its promoter activity, and gene transcription attributable to the activation of the PI3K/Akt pathway. Neutralization of Bcl-2 by antibody transfection significantly decreased the antiapoptotic effect of DHEA. These findings provide the first evidence that DHEA acts as a survival factor for endothelial cells by triggering the Galphai-PI3K/Akt-Bcl-2 pathway to protect cells against apoptosis. This may represent an important mechanism underlying the vascular protective effect of DHEA.

Presence and active synthesis of the 67 kDa elastin-receptor in human circulating white blood cells

Early after the identification of the elastin-receptor (El-R) on mesenchymal cells, it was demonstrated that phagocytic cells and lymphocytes could also respond to elastin peptides. Nevertheless, the level of El-R expression has never been demonstrated on immune cells and no data exist whether these cells actively synthesize this El-R. Thus, our aim in the present work was to study the expression and number of El-R on white blood cells (WBC) using a specific 67 kDa El-R antibody and to demonstrate the presence of mRNA corresponding to the gene coding for El-R. Our results show that messenger RNA corresponding to the presumptive gene coding for the 67 kDa El-R subunit could be detected in all three WBC-types investigated. On all of these WBC, the presence of El-R could be demonstrated, however their number and their function varied following the cell type. The presence of El-R is very important for the interaction of circulating cell with the matrix as these cells intervene during atherosclerosis and in host defence.

Dehydroepiandrosterone inhibits the proliferation of human umbilical vein endothelial cells by enhancing the expression of p53 and p21, restricting the phosphorylation of retinoblastoma protein, and is androgen- and estrogen-receptor independent

Dehydroepiandrosterone (DHEA), a steroid hormone, modified the proliferation of human umbilical vein endothelial cells in a dose-dependent manner. Its inactive sulfate ester (DHEA-S) and two of its metabolites -- estradiol and testosterone -- had no inhibitory effect at physiological concentrations. Antiproliferation was associated with arrest in the G1 phase of the cell cycle, but not with cell death, as evaluated by cleavage of poly(ADP-ribose) polymerase and exposure of phosphatidylserine. The effect was not blocked by inhibitors of androgen or estrogen receptors. DHEA diminished the levels of phosphorylated retinoblastoma protein and increased the expression of p53 and p21 mRNAs. These results show that DHEA inhibits endothelial cell proliferation by regulating cell cycle relevant proteins through a cytoplasmic steroid hormone-independent pathway.

Is brain dehydroepiandrosterone synthesis modulated by free radicals in mice?

Dehydroepiandrosterone (DHEA) is a neurosteroid synthesized de novo in the brain, in addition to the periphery, modulating some membrane, ion-gated channel neurotransmitter receptors. P450-17alpha-hydroxylase activity converting pregnenolone to DHEA, has not yet been identified in the brain of rodents. Studies in brain-derived primary cultures and cell lines, suggest a possible alternative pathway for DHEA synthesis involving oxygenated hydroxyperoxides. We investigated DHEA synthesis in the brains of castrated male mice before and after treatment with N-acetylcysteine amide (AD4) (a newly developed brain penetrating antioxidant). We found a significant increase in brain DHEA level 24 h after castration, which was totally blocked by AD4. This blockade of castration-induced increased brain DHEA synthesis, supports the assumption that this synthesis may also be affected by free radicals. This is the first in vivo study indicating the possible existence of an in-brain oxidative stress-related pathway leading to brain DHEA production.

Signal transduction and functional changes in neutrophils with aging

It is well known that the immune response decreases during aging, leading to a higher susceptibility to infections, cancers and autoimmune disorders. Most widely studied have been alterations in the adaptive immune response. Recently, the role of the innate immune response as a first-line defence against bacterial invasion and as a modulator of the adaptive immune response has become more widely recognized. One of the most important cell components of the innate response is neutrophils and it is therefore important to elucidate their function during aging. With aging there is an alteration of the receptor-driven functions of human neutrophils, such as superoxide anion production, chemotaxis and apoptosis. One of the alterations underlying these functional changes is a decrease in signalling elicited by specific receptors. Alterations were also found in the neutrophil membrane lipid rafts. These alterations in neutrophil functions and signal transduction that occur during aging might contribute to the significant increase in infections in old age.

Dehydroepiandrosterone Prevents Oxidative Injury in Obstructive Jaundice in Rats

We investigated the effect of dehydroepiandrosterone (DHEA) on oxidative injury in obstructive jaundice using three groups of rats: sham-operated group; common bile duct (CBD) group — the CBD was ligated; and DHEA group — DHEA administration followed CBD ligation. Liver function tests were performed using blood samples, and malondialdehyde concentration (MDA), superoxide dismutase activities (SOD), glutathione peroxidase (GPx), and total glutathione (tGSH) concentrations were measured in liver tissue. Serum alkaline phosphatase, γ-glutamyltransferase and alanine aminotransferase activity were significantly elevated in the CBD group compared with the other groups. Serum aspartate aminotransferase and total bilirubin were highest in the CBD group; the MDA concentration was higher in the CBD group than the sham group. There were no significant differences in GPx activity among the groups. SOD activity and tGSH concentration were significantly lower in the CBD group than the other groups. DHEA may protect hepatic tissue against oxidative injury in obstructive jaundice by decreasing MDA concentration and increasing SOD activity and tGSH concentration.

Cœur et androgènes

Beyond regulation of sexual function, male steroids play an important role in many physiological homeostasis systems, including the cardiovascular system. Via a specific androgen receptor, testosterone mediates cardiomyocyte trophicity both in physiological situations and in hypertrophy-related cardiac diseases. Androgens also regulate pathological levels of inflammatory cytokines such as Il-6 or TNF in advanced heart failure. They also mediate vascular resistance since coronary vasodilatation has been proven both in vitro and in vivo. Reduced free testosterone serum levels (age-mediated or premature coronary artery disease) promote a pro-atherogenic lipid profile expressed as lower serum HDL-cholesterol and up-regulation of triglyceride levels. This observation has relevant clinical implications for the evaluation and treatment of coronary artery disease. As most of normal and diseased cardiovascular system functions are influenced by androgens, further evaluation of their physiological implications should be undertaken as well as large-scale rigorous studies of the therapeutic implications in two disabling diseases, coronary heart disease and heart failure.

Oxidation of protein in human low-density lipoprotein exposed to peroxyl radicals facilitates uptake by monocytes; protection by antioxidants in vitro

Generation of neoepitopes on apolipoprotein B within oxidised low-density lipoprotein (LDL) is important in the unregulated uptake of LDL by monocytic scavenger receptors (CD36, SR-AI, LOX-1). Freshly isolated LDL was oxidised by peroxyl radicals generated from the thermal decomposition of an aqueous azo-compound. We describe that formation of carbonyl groups on the protein component is early as protein oxidation was seen after 90min. This is associated with an increased propensity for LDL uptake by U937 monocytes. Three classes of antioxidants (quercetin, dehydroepiandrosterone (DHEA) and ascorbic acid) have been examined for their capacity to inhibit AAPH-induced protein oxidation, (protein carbonyls, Δ electrophoretic mobility and LDL uptake by U937 monocytes). CD36 expression was assessed by flow cytometry and was seen to be unaltered by oxidised LDL uptake. All three classes were effective antioxidants, quercetin (P<0.01), ascorbic acid (P<0.01), DHEA (P<0.05). As LDL protein is the control point for LDL metabolism, the degree of oxidation and protection by antioxidants is likely to be of great importance for (patho)-physiological uptake of LDL by monocytes.

[Molecular mechanisms of the protective effect of vitamin e against atherosclerosis]

Oxidation of low-density lipoproteins constitutes the first step of a very complex process leading to atherosclerosis. Vitamin E, and principally a-tocopherol, is considered as the principal inhibitor of lipid peroxidation. Some studies showed the beneficial role of vitamin E in the prevention and reduction of atherosclerosis and its associated pathologies. However, other in vitro studies advance a prooxidant role of vitamin E. The results of the epidemiologic studies are difficult to generalize without taking account of the clinical randomized tests. In this work, we reviewed the principal studies devoted to the role of vitamin E and discussed the assumption of a prooxidant effect of this molecule.

Monocytes influence the fate of T cells challenged with oxidised low density lipoproteins towards apoptosis or MHC-restricted proliferation

Atherosclerosis has been implicated in myocardial infarction, stroke and a host of cardiovascular diseases. The presence of activated T lymphocytes and macrophages, and the increased expression of HLA-DR antigen are consistent with the notion of immune activity in the atherosclerotic plaque. The nature of the causative antigen has not been established although oxidised low density lipoproteins (oxLDL) that accumulate in atherosclerotic plaques could fulfil this role. Here, we report that monocytes play a key role in influencing the fate of purified peripheral human T lymphocytes from healthy donors when the cells are exposed to LDL oxidised under the controlled conditions of water radiolysis. Our data showed that oxLDL generated under these conditions were chemoattractants for T cells. However, they induced a state of apoptosis in T lymphocytes cultured in the absence of monocytes. The extent of apoptosis was related to the degree of oxidation of LDL and the time of T cell exposure to oxLDL. OxLDL-dependent apoptosis did not involve a scavenger-like receptor. CD4(+) cells were more sensitive to the apoptotic effect of oxLDL than CD8(+) cells. OxLDL-primed (12 h) autologous monocytes triggered a robust proliferation of T lymphocytes cultured in the absence of oxLDL. The strength of T cell stimulation was related to the degree of oxidation of the LDL used in priming. Heterologous monocytes exposed to oxLDL under similar conditions induced a response that was not different than monocytes exposed to untreated LDL (natLDL) which did not induce T cell proliferation. Fucoidan did not modify the oxLDL-, monocyte-dependent T cell response to proliferation, suggesting that a scavenger-like receptor was not involved. The expression of the HLA-DR marker and the B7.2 protein were up-regulated in monocytes exposed to oxLDL but not to natLDL. The levels of B7.1 were unchanged. Our data are consistent with the notion that monocytes are critical for T cell survival in the presence of oxLDL and MHC-restricted T cell proliferative response to oxLDL.

Novel 21-aminosteroid U-74389G inhibits low-density lipoprotein peroxidation induced by .OH and O2-. free radicals

LDL peroxidation represents one of the first event in the atherogenesis process. Inhibiting LDL oxidation may impede this process and offers a new mechanism to retard atherogenesis. 21-Aminosteroids, derived from methylprednisolone, have recently excited much interest by virtue of their ability to inhibit lipid peroxidation. The aim of our work was to investigate the effect of a novel 21-aminosteroid, U-74389G, in the LDL peroxidation initiated in a metal- and cell-free system by oxygen free radicals, .OH and O2-., generated by water gamma-radiolysis. In a concentration dependent manner, U-74389G increased the resistance of LDL to oxidation measured by the length of the lag phase, reduced the formation of conjugated dienes and thiobarbituric acid-reactive substances (TBARS), and also reduced the alpha-tocopherol disappearance by about 47% at the concentration 20 microM. U-74389G was also able to reduce the chemotactic activity of oxidized LDL towards monocytes, as well as the cholesterol accumulation in macrophages. These observations suggest that the U-74389G is a potent antioxidant by decreasing LDL peroxidation and this should be evaluated in in vivo models as a potential therapy to retard atherogenesis.

A comparison of the kinetics of low-density lipoprotein oxidation induced by copper or by γ-rays: Influence of radiation dose-rate and copper concentration

The oxidation of low-density lipoproteins is the first step in the complex process leading to atherosclerosis. The aim of our study was to compare the kinetics of low density lipoprotein oxidation induced by copper ions or by oxygen free radicals generated by60Co γ-rays. The effects of copper concentration and irradiation dose-rate on LDL peroxidation kinetics were also studied. The oxidation of LDL was followed by the measurement of conjugated diene, hydroperoxides, and thiobarbituric acid reactive substance formation as well as α-tocopherol disappearance. In the case of gamma irradiation, the lag-phase before the onset of lipid peroxidation was inversely correlated to the radiation dose-rate. The radiation chemical rates (v) increased with increasing dose-rate. Copper-induced LDL peroxidation followed two kinetic patterns: a slow kinetic for copper concentrations between 5–20 µM, and a fast kinetic for a copper concentration of 40 µM. The concentration-dependent oxidation kinetics suggest the existence of a saturable copper binding site on apo-B. When compared with γ-rays, copper ions act as drastic and powerful oxidants only at higher concentrations ([Formula: see text]40 µM).Key words: LDL, peroxidation, kinetics, copper, γ-radiolysis, dose-rate.

Low dehydroepiandrosterone and ischemic heart disease in middle-aged men: prospective results from the Massachusetts Male Aging Study

The adrenal steroid dehydroepiandrosterone (DHEA) and its sulfate (DHEAS) have been characterized as "protective" against ischemic heart disease (IHD), especially in men, on the basis of sparse epidemiologic evidence. The authors used data from the Massachusetts Male Aging Study, a random sample prospective study of 1,709 men aged 40-70 years at baseline, to test whether serum levels of DHEA or DHEAS could predict incident IHD over a 9-year interval. At baseline (1987-1989) and follow-up (1995-1997), an interviewer-phlebotomist visited each subject in his home to obtain comprehensive health information, body measurements, and blood samples for hormone and lipid analysis. Incident IHD between baseline and follow-up was ascertained from hospital records and death registries, supplemented by self-report and evidence of medication. In the analysis sample of 1,167 men, those with serum DHEAS in the lowest quartile at baseline (<1.6 microg/ml) were significantly more likely to incur IHD by follow-up (adjusted odds ratio = 1.60, 95 percent confidence interval: 1.07, 2.39; p = 0.02), independently of a comprehensive set of known risk factors including age, obesity, diabetes, hypertension, smoking, serum lipids, alcohol intake, and physical activity. Low serum DHEA was similarly predictive. These results confirm prior evidence that low DHEA and DHEAS can predict IHD in men.

Biogerontological research in Canada

There is an ever increasing interest in the study of the aging process. This review is aimed to make an overview of the biological aging research in Canada. I will summarize, to the best of my knowledge, the biological aging research undertaken actually in Canadian institutions dealing with various aspects of this research using many different experimental approaches, models from animals to humans and a huge array of techniques. The biological aging research is developing continuously in Canada, however, it is very important that we assist in a near future to its huge explosion if we would respond to the needs of an ever increasing aging population. Initiatives recently proposed by the Canadian government concerning the creation of Canadian Institutes on Health Research will provide good opportunities to establish a performant, cost-effective, and innovative biological aging research.

Effects of gliclazide versus metformin on the clinical profile and lipid peroxidation markers in type 2 diabetes

The sulfonylurea gliclazide and the biguanide metformin have different mechanisms to reduce glycemia. We performed a randomized study to compare these two agents with respect to glycemic control and effects on lipid peroxidation markers in 36 adult patients with type 2 diabetes. Both agents significantly decreased glycosylated hemoglobin ([HbA1c] P < .05), fructosamine (P < .05), and the glucose-excursion curve during the oral glucose tolerance test ([OGTT] P < .01). With regard to the insulin curve during this test, no significant change was observed with metformin and a significant increase was measured with gliclazide (P < .05). Considering the small number of events, no significant difference was detected in the number of hypoglycemic episodes between the two agents. More upper-gastrointestinal (GI) symptoms were observed with metformin compared with gliclazide (P < .05). Even with no change in the standard lipid profile, both agents increased serum vitamin E (P < .01 for gliclazide and P < .05 for metformin) and decreased the level of lipid peroxidation markers in low-density lipoprotein (LDL) and high-density lipoprotein (HDL) particles (P < .05). Despite different mechanisms of action, gliclazide and metformin demonstrated comparable levels of efficacy and complementary effects on lipid peroxidation markers.

Dehydroepiandrosterone protects tissues of streptozotocin-treated rats against oxidative stress

Chronic hyperglycemia in diabetes determines the overproduction of free radicals, and evidence is increasing that these contribute to the development of diabetic complications. It has recently been reported that dehydroepiandrosterone possesses antioxidant properties; this study evaluates whether, administered daily for three weeks per os, it may provide antioxidant protection in tissues of rats with streptozotocin-induced diabetes. Lipid peroxidation was evaluated on liver, brain and kidney homogenates from diabetic animals, measuring both steady-state concentrations of thiobarbituric acid reactive substances and fluorescent chromolipids. Hyperglycemic rats had higher thiobarbituric acid reactive substances formation and fluorescent chromolipids levels than controls. Dehydroepiandrosterone-treatment (4 mg/day for 3 weeks) protected tissues against lipid peroxidation: liver, kidney and brain homogenates from dehydroepiandrosterone-treated animals showed a significant decrease of both thiobarbituric acid reactive substances and fluorescent chromolipids formation. The effect of dehydroepiandrosterone on the cellular antioxidant defenses was also investigated, as impaired antioxidant enzyme activities were considered proof of oxygen-dependent toxicity. In kidney and liver homogenates, dehydroepiandrosterone treatment restored to near-control values the cytosolic level of reduced glutathione, as well as the enzymatic activities of superoxide-dismutase, glutathione-peroxidase, catalase. In the brain, only an increase of catalase activity was evident (p < .05), which reverted with dehydroepiandrosterone treatment. The results demonstrate that DHEA treatment clearly reduces oxidative stress products in the tissues of streptozotocin-treated rats.

Age-related increased susceptibility of high-density lipoproteins (HDL) to in vitro oxidation induced by gamma-radiolysis of water

In the present study, we investigated the age-related susceptibility of high-density lipoproteins (HDL) to oxidation. HDL were obtained from healthy, normolipidemic young, middle-aged and elderly subjects. Oxidation of HDL was induced in vitro by oxygen free radicals generated by water gamma-radiolysis, and followed by the decrease of endogenous vitamin E and the formation of conjugated dienes and thiobarbituric acid-reactive substances, as well as the alterations of apolipoproteins A-I/A-II. The resistance of HDL to oxidation, evaluated by the length of the lag phase, decreased with aging. This increased oxidizability of HDL with aging could have a dramatic impact on the development of atherosclerosis in the elderly population.