H Déchaud

University of Yaounde I, Yaoundé, Centre Province, Cameroon

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Publications (71)199.81 Total impact

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    ABSTRACT: Abstract Context: Male infertility is one of the leading causes of social frustration and marginalization, mainly in the developing world. It is attributed to many factors including exposure to agropesticides such as manganese ethylenebis (dithiocarbamate) (maneb), which is one of the most frequently used fungicides in Cameroon. Previous reports support efficiency of some medicinal plants commonly used in Cameroonian folk medicine for the treatment of this disorder. Objective: The present study was aimed at assessing the protective effect of extracts from selected plant species, namely Basella alba L. (Basellaceae) (MEBa) and Carpolobia alba G. Don (Polygalaceae) (AECa), in alleviating the maneb-induced impairment of male reproductive function in Wistar albino rats. Materials and methods: The rats were treated with vehicle, plant extract (MEBa or AECa), maneb and maneb plus plant extract, respectively, and their fertility was assessed. Animals were thereafter sacrificed and organs (liver, kidneys and reproductive organs) were dissected out and weighed. Serum androgens together with alanine aminotransferase, liver glutathione and thiobarbituric acid reactive species (TBARS) were also measured. Results and discussion: From this study, both plant extracts stimulated testosterone and improved fertility. Administration of MEBa plus maneb prevented fertility reduction by maneb and minimized the inhibitory effect of maneb on testosterone levels. AECa also improved fertility of the maneb-exposed rats, though without restoring testosterone levels, and other investigated parameters remained unaffected by different treatments. Conclusion: These findings emphasized the beneficial effects of B. alba and C. alba extracts on male fertility, and suggest their protective effect against maneb-induced toxicity in male reproductive function.
    Pharmaceutical Biology 09/2013; · 1.21 Impact Factor
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    ABSTRACT: Bisphenol A (BPA), is one of the most abundant endocrine disruptors that are present in our environment, and has been repeatedly detected in most human biological samples. As it has been suggested that part of the BPA measured in human samples is due to contamination during samples collection or laboratory measurements, we have developed a specific radioimmunoassay for the measurement of BPA-glucuronide (BPA-G), the main endogenous metabolite of BPA in urine. We used a polyclonal anti-BPA antibody which has a 95% cross reactivity with BPA-G, and insignificant cross reactivity with most analogous BPA phenolic structures. To eliminate unconjugated BPA from urine samples, an extraction step with dichloromethane was required. The method proved to be valid, precise and accurate in the range of 0.05μg/L to 5μg/L. With this method, we measured BPA-G in 163 urine samples from a hospital population. We detected BPA-G in all samples, with mean values of 4.64μg/L. In conclusion, the present radioimmunoassay is a useful tool for the screening of BPA exposure in human populations encompassing the problem of eventual contamination from laboratory manipulation.
    Talanta 10/2012; 100C:410-413. · 3.50 Impact Factor
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    ABSTRACT: This study aimed at investigating the effect of agropesticides on male reproductive function in farmers in Djutitsa (West Cameroon). To this end, 47 farmers in Djutitsa were asked questions on their health status and pesticide use in agriculture. Thereafter, their blood samples were collected for assessment of sex hormones including serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), androstenedione, testosterone, as well as sex hormone binding globulin (SHBG). Their serum triiodothyronine (T3) and thyroxine (T4) levels were also measured. Thirty seven men not exposed to agropesticides were recruited as control group. Fifty six pesticides containing 25 active substances were currently used by farmers enrolled in our study, and most of their symptoms were related to spread/use of these chemicals. Compared to the control group, there was no significant difference in FSH, LH, SHBG, estradiol, and thyroid hormones (T3 and T4) levels. Farmers had significantly lower serum testosterone (20.93 ± 1.03 nM vs. 24.32 ± 1.32 nM; P < 0.05) and higher androstenedione level (3.83 ± 0.20 nM vs. 2.80 ± 0.15 nM; P < 0.001). Their serum free testosterone as well as bioavailable testosterone were unchanged, while estradiol/testosterone and androstenedione/testosterone ratios were significantly increased (0.45 ± 0.03% vs. 0.33 ± 0.02%; P < 0.01 and 12.26 ± 3.64 vs 19.31 ± 6.82; P < 0.001, respectively). Our results suggest that male farmers of Djutitsa (West Cameroon) are exposed to agropesticides due to improper protective tool, and this exposure may impair their reproductive function through inhibition of testosterone synthesis; probably by inhibition of testicular 17β- hydroxysteroid dehydrogenase (17HSD3) and induction of aromatase (CYP19).
    Environmental Toxicology 07/2012; 27(7):423-32. · 2.71 Impact Factor
  • Pratique Médicale et Chirurgicale de l'Animal de Compagnie. 01/2012; 47(2):62.
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    ABSTRACT: 1. Total testosterone assay is recommended as the first-line approach. 2. Radioimmunological assay following prior treatment of the sample (extraction or extraction + chromatography) is the recommended method pending wider experience with mass spectrometry. 3. Where testosterone is twice the upper limit of normal, it is recommended that DHEAS assay be performed. DHEAS is primarily of cortico-adrenal origin in women. Thus, a DHEAS level over 600 mg/dl indicates a diagnosis of androgen-secreting adrenal cortical adenoma.. If DHEAS is normal, the diagnosis could be either ovarian hyperthecosis, normally associated with insulin resistance, or androgen-secreting ovarian tumour. 4. More rarely, elevated testosterone is associated with a marked elevation of SHBG possibly as the result of use of medication having an estrogenic effect (tamoxifen, raloxifene, Op'DDD), or of hyperthyroidism or liver disease. 5. Normal testosterone levels in patients with clear clinical symptoms of hyperandrogenism (hirsutism, seborrhoeic acne) must be interpreted with care. SHBG is normally reduced in the event of overweight, metabolic syndrome or familial history of diabetes.
    Annales d Endocrinologie 02/2010; 71(1):2-7. · 1.02 Impact Factor
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    ABSTRACT: Testosterone (T) circulates in the blood tightly bound to sex hormone-binding globulin (SHBG) and weakly to albumin. Measuring protein unbound T (free) or non-SHBG-bound T rather than total T has been recommended for the evaluation of androgen disorders in humans. Ammonium sulfate precipitation has been widely used to separate [SHBG-T] complex from free and albumin-bound T. To achieve more specificity in this separation, we used monoclonal anti-SHBG antibody and developed a suitable and convenient immunoassay for measuring non-SHBG-bound T. Magnetic beads were covalently coupled to a monoclonal anti-SHBG antibody to capture [SHBG-T] complex from plasma samples. Magnetic separation was then performed to allow measurement of non-SHBG-bound T in the supernatant by direct radioimmunoassay. When 300 microL of plasma samples were incubated at room temperature with 10 microL of anti-SHBG beads, residual SHBG concentration was undetectable in the supernatant. The specificity of proteins retained on anti-SHBG beads was further demonstrated by peptide mass fingerprint on a MALDI-TOF analyzer. The non-specific adsorption of T on beads was low (5%), and dissociation of T from SHBG-T complex was less than 5% after 180 min of incubation. The plasma concentrations of non-SHBG-bound T using anti-SHBG beads were highly correlated to those obtained using ammonium sulfate precipitation. We conclude that SHBG immunocapture is a highly specific and useful tool for an experimental direct measurement of plasma non-SHBG-bound T. This methodology is also convenient and appropriate for routine and automated assay.
    Analytica chimica acta 01/2010; 658(1):87-90. · 4.31 Impact Factor
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    ABSTRACT: 1. Le dosage de la testostérone totale est recommandé en première intention. 2. La méthode de dosage radioimmunologique après traitement préalable de l’échantillon (extraction ou extraction + chromatographie) est la méthode recommandée dans l’attente d’une plus large expérience de l’utilisation de la spectrométrie de masse. 3. Lorsque la testostérone est deux fois plus élevée que la valeur supérieure de la normale, il est recommandé de prescrire un dosage de DHEAS, qui est principalement d’origine corticosurrénale chez la femme. Ainsi, une DHEAS supérieure à 600 mg/dl permet de retenir le diagnostic de corticosurrénalome sécrétant des androgènes. Si la DHEAS est normale, le diagnostic peut hésiter entre une hyperthécose ovarienne, habituellement associée à un contexte d’insulinorésistance, et une tumeur ovarienne sécrétant des androgènes. 4.L’élévation de la testostérone est plus rarement associée à une forte élévation de la SHBG qui peut être la conséquence de la prise de médicaments à effet estrogènique (tamoxifène, raloxifène, Op’DDD), ou d’une hyperthyroïdie voire d’une pathologie hépatique. 5. Un taux de testostérone normal en cas de symptômes évident d’hyperandrogénie clinique évidente (hirsutisme, acné séborrhéique) doit être interprété avec prudence. SHBG est habituellement diminuée en cas de surpoids, de syndrome métabolique ou dans un contexte familial de diabète. Elle permet de corriger l’interprétation de la testostérone totale et permet le calcul de la testostérone libre.
    Annales D Endocrinologie - ANN ENDOCRINOL. 01/2010; 71(1).
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    ABSTRACT: Sex hormone-binding globulin (SHBG) is the main transport binding protein for sex steroid hormones in plasma and regulates their accessibility to target cells. Plasma SHBG is secreted by the liver under the control of hormones and nutritional factors. In the human hepatoma cell line (HepG2), thyroid and estrogenic hormones, and a variety of drugs including the antioestrogen tamoxifen, the phytoestrogen, genistein and mitotane (Op'DDD) increase SHBG production and SHBG gene promoter activity. In contrast, monosaccharides (glucose or fructose) effectively decrease SHBG expression by inducing lipogenesis, which reduces hepatic HNF-4alpha levels, a transcription factor that play a critical role in controlling the SHBG promoter. Interestingly, diminishing hepatic lipogenesis and free fatty acid liver biosynthesis also appear to be associated with the positive effects of thyroid hormones and PPARgamma antagonists on SHBG expression. This mechanism provides a biological explanation for why SHBG is a sensitive biomarker of insulin resistance and the metabolic syndrome, and why low plasma SHBG levels are a risk factor for developing hyperglycemia and type 2 diabetes, especially in women. These important advances in our knowledge of the regulation of SHBG expression in the liver open new approaches for identifying and preventing metabolic disorder-associated diseases early in life.
    Molecular and Cellular Endocrinology 09/2009; 316(1):53-9. · 4.04 Impact Factor
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    ABSTRACT: Glucocorticoid Receptor (GR) polymorphisms have been repeatedly associated with obesity and metabolic parameters in man. We have previously shown the genetic influence of a polymorphism in the gene encoding CBG on some obesity parameters in a small female population. In this study we have explored possible genetic associations between obesity and metabolic measures and CBG or GR polymorphisms in a new male population. Two hundred and ninety-five men with body mass index (BMI) ranging from 19 to 55 kg/m 2 were studied. Serum CBG levels, CBG and GR gene polymorphisms in relation with anthropometric and biochemical parameters were analysed. GR BclI polymorphism was found to influence weight, BMI, waist circumference and glucose levels. CBG polymorphism showed a significant effect for BMI and waist circumference. The frequency of CBG allele 90 was markedly increased among men with morbid obesity compared to the rest of the population (30 versus 18%, p=0.02). The influence of GR BclI polymorphism is replicated in an additional population and CBG polymorphism has a small but significant influence on obesity in men. Further studies are needed to understand the mechanism by which these polymorphisms impact on cortisol and obesity.
    International Journal of Genetics and Molecular Biology 08/2009; 1:59-63.
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    ABSTRACT: Bisphenol A (BPA) is widely used in the manufacturing of polycarbonate plastic food and drink packaging. Possessing a weak estrogenic activity, BPA is listed among a growing list of endocrine disrupting compounds. In this study, a polyclonal anti-BPA antibody was obtained by immunization with BPA-monocarboxymethylether covalently linked to BSA. The antibody demonstrates negligible cross-reactivity with most analogous BPA phenolic structures, and no cross-reactivity with endogenous steroids. An extraction step with ethyl acetate minimized matrix effects and allowed the BPA measurement in plasma and other biological samples. Recovery after loading test was 96 +/- 4% and dilution tests had a linear profile (r2 > 0.93). The limit of detection of the BPA RIA was 0.08 microg L(-1) with an IC50 of 1.25 microg L(-1). The intra- and inter-assay coefficients of variation were 5.6 and 8.6%, respectively at a BPA concentration of 0.7 microg L(-1) and 6.9 and 5.7% at a BPA concentration of 1.3 microg L(-1). A significant correlation was found between the values obtained by the RIA and HPLC-MS (r2 = 0.92) or HPLC coupled to a fluorescence detector (r2 = 0.80). In conclusion, we described a BPA-RIA that is a suitable tool for evaluating human exposure to BPA.
    Analytica chimica acta 07/2009; 645(1-2):1-4. · 4.31 Impact Factor
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    ABSTRACT: Previous evidence has suggested that a low sex hormone-binding globulin (SHBG) concentration is associated with insulin-resistance and a low adiponectin concentration. We investigated the association between SHBG and the risk of hyperglycemia in each sex and we determined potential interactions between SHBG and adiponectin levels in the development of dysglycemia. We used a nested case-control design in the large prospective study, Data from an Epidemiological Study on the Insulin Resistance Syndrome (DESIR). We studied 227 men and women who were normoglycemic at baseline but hyperglycemic at 3 years (glycemia > or = 6.1 mmol/l or type 2 diabetes). They were matched for sex, age, and body mass index with 227 subjects who remained normoglycemic at 3 years. At baseline, the concentration of SHBG was significantly lower in women who subsequently developed hyperglycemia than in those who remained normoglycemic, with no difference for men. In multiple regression, SHBG at baseline was as an independent determinant of plasma adiponectin levels, in both women (P<0.0001) and men (P=0.002). In multivariate conditional logistic regression taking into account physical activity and changes in waist circumference over the follow-up, plasma SHBG remained significantly associated with the development of hyperglycemia in women but not in men. These associations persisted after adjustment for fasting insulinemia, high fasting glucose, and adiponectin levels. These findings suggest that a low SHBG level is a strong risk marker for dysglycemia in women, independently of both adiponectinemia and insulinemia. SHBG may therefore improve the identification of women at risk of diabetes.
    European Journal of Endocrinology 06/2009; 161(1):81-5. · 3.14 Impact Factor
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    ABSTRACT: Bisphenol A (BPA) is an endocrine disruptor with weak estrogenic activity, used in epoxy resin and polycarbonate plastic. Human exposure may occur by contamination from food or food-contact material and by occupational scenarios. Occupational health hazards may be associated with allergic contact dermatitis (ACD) secondary to BPA exposure. Most ACD occurs in workers handling BPA products, such as plastic-product workers, and those exposed to epoxy adhesive tapes, foams, and dental products. The present study examined in vitro cutaneous penetration of BPA through pig skin, using a Franz cell. After 2, 5, and 10 h of exposure, total BPA skin content was 3, 6.9, and 11.4% of the applied dose, respectively. BPA remained essentially on the skin surface and penetration mainly accumulated in the dermis. As the pig skin model is a reliable predictor of percutaneous penetration in humans, these findings may be reassuring for workers in contact with BPA-based products.
    Journal of Toxicology and Environmental Health Part A 02/2008; 71(8):471-3. · 1.73 Impact Factor
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    ABSTRACT: Obesity, insulin resistance, and weight loss have been associated with changes in hypothalamic-pituitary-adrenal (HPA) axis. So far, no conclusive data relating to this association are available. In this study, we aim to investigate the effects of massive weight loss on cortisol suppressibility, cortisol-binding globulin (CBG), and free cortisol index (FCI) in formerly obese women. Ten glucose-normotolerant, fertile, obese women (BMI >40 kg/m2, aged 38.66 +/- 13.35 years) were studied before and 2 years after biliopancreatic diversion (BPD) when stable weight was achieved and were compared with age-matched healthy volunteers. Cortisol suppression was evaluated by a 4-mg intravenous dexamethasone suppression test (DEX-ST). FCI was calculated as the cortisol-to-CBG ratio. Insulin sensitivity was measured by an euglycemic-hyperinsulinemic clamp, and insulin secretion was measured by a C-peptide deconvolution method. No difference was found in cortisol suppression after DEX-ST before or after weight loss. A decrease in ACTH was significantly greater in control subjects than in obese (P = 0.05) and postobese women (P < or = 0.01) as was the decrease in dehydroepiandrosterone (P < or = 0.05 and P < or = 0.01, respectively). CBG decreased from 51.50 +/- 12.76 to 34.33 +/- 7.24 mg/l (P < or = 0.01) following BPD. FCI increased from 11.15 +/- 2.85 to 18.16 +/- 6.82 (P < or = 0.05). Insulin secretion decreased (52.04 +/- 16.71 vs. 30.62 +/- 16.32 nmol/m(-2); P < or = 0.05), and insulin sensitivity increased by 163% (P < or = 0.0001). Serum CBG was related to BMI (r(0) = 0.708; P = 0.0001), body weight (r(0) = 0.643; P = 0.0001), body fat percent (r(0) = 0.462; P = 0.001), C-reactive protein (r(0) = 0.619; P = 0.004), and leptin (r(0) = 0.579; P = 0.007) and negatively to M value (r(0) = -0.603; P = 0.005). After massive weight loss in morbidly obese subjects, an increase of free cortisol was associated with a simultaneous decrease in CBG levels, which might be an adaptive phenomenon relating to environmental changes. This topic, not addressed before, adds new insight into the complex mechanisms linking HPA activity to obesity.
    Diabetes care 06/2007; 30(6):1494-500. · 7.74 Impact Factor
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    ABSTRACT: The mouse kidney expresses the gene of ornithine aminotransferase (Oat). Previous works suggest that Oat is differentially expressed in female and male mouse kidney (Alonso E, Rubio V. Biochem J 259: 131-138, 1989; Levillain O, Diaz JJ, Blanchard O, Dechaud H. Endocrinology 146: 950-959, 2005; Manteuffel-Cymborowska M, Chmurzynska W, Peska M, Grzelakowska-Sztabert B. Int J Biochem Cell Biol 27: 287-295, 1995; Natesan S, Reddy SR. Comp Biochem Physiol B Biochem Mol Biol 130: 585-595, 2001; Yu H, Yoo PK, Aguirre CC, Tsoa RW, Kern RM, Grody WW, Cederbaum SD, Iyer RK. J Histochem Cytochem 51: 1151-1160, 2003). This study was designed to provide a detailed description of the sexual dimorphism of Oat expression in the mouse kidney and to test the influence of sex hormones on its regulation. Experiments were performed on male and female Swiss OF1 mice during their postnatal development, at adulthood, and in orchidectomized and ovariectomized mice. Kidneys, dissected renal zones, and mitochondria were used to analyze OAT mRNA and protein levels and measure OAT activity. The results revealed that before puberty, Oat expression was similar between female and male kidneys whereas from puberty until adulthood Oat expression increased in the female kidney, becoming approximately 2.5-fold higher than in the male kidney. This sex-differential expression of Oat was associated with a sex-specific distribution of Oat along the corticopapillary axis and within the nephron. OAT was three- to fourfold more expressed in the female than the male cortex. In males, Oat was highly expressed in the medulla, mainly in the thick ascending limbs. Renal Oat distribution in orchidectomized mice resembled that in the females. Ovariectomy did not influence Oat expression. Sex differences are explained by the physiological increase in plasma testosterone in males. Expression of medium-chain acyl-CoA synthetase protein confirmed this finding. We report sexual dimorphism of Oat expression in the mouse kidney and show that Oat is naturally downregulated in the presence of testosterone.
    American journal of physiology. Renal physiology 04/2007; 292(3):F1016-27. · 3.61 Impact Factor
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    ABSTRACT: Bioavailable testosterone (BT) concentration is considered the best marker for evaluating testicular function in men. The decrease of BT in older men is more pronounced than the decrease in total testosterone because of the parallel increase in sex hormone-binding globulin (SHBG) concentrations. Measurement of BT is therefore crucial for the diagnosis of hypoandrogenism in the aging male population. We compared BT concentrations measured by a specific RIA after ammonium sulfate precipitation (BT(meas)) with those obtained by theoretical calculations (BT(cal)) in plasma samples from 694 young men (14 to 49 years old) and 51 older men (50 to 81 years old). We based theoretical calculations on Vermeulen's simplified mass equation using total testosterone and SHBG concentrations. BT(cal) and BT(meas) correlated significantly in young (Pearson r = 0.87) and aging (r = 0.89) men, but the BT(cal):BT(meas) ratio differed markedly between the 2 groups (2.28 vs 3.48; P <0.001). In men, there is an age-associated discrepancy between calculated and measured BT concentrations. We suggest some hypotheses for the discrepancy, but additional studies will be performed to finally elucidate this difference in results and to determine the most appropriate method for BT measurements in older men.
    Clinical Chemistry 04/2007; 53(4):723-8. · 7.15 Impact Factor
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    ABSTRACT: Androgen-secreting neoplasms (ASNs) are generally associated with rapidly progressive symptoms of hyperandrogenism, which result in various degrees of virilization. A plasma concentration of testosterone of more than 200 ng/dL (8.7 nmol/L) (or two to three times the upper normal range) with a normal dehydroepiandrosterone sulfate (DHEAS) level is highly suggestive of an ovarian ASN. The value of low dexamethasone suppression test is associated with high sensitivity but limited specificity in differential diagnosis of hyperandrogenism. Suppression of testosterone levels by administration of a progestogen or gonadotropin-releasing hormone agonist will not discriminate an ovarian ASN from hyperthecosis, but will strongly orientate the diagnosis to the ovarian origin of androgen excess. Ovarian and adrenal venous catheterization and sampling should be reserved for patients in whom the presence of a small ovarian tumor cannot be excluded on imaging studies and restrictive to expert unit.
    12/2006: pages 75-84;
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    ABSTRACT: Side effects of mitotane (o,p'-DDD) have suggested estrogenic effects. The objective of the study was to explore o,p'-DDD potential estrogenic effect on SHBG and corticosteroid-binding globulin (CBG). Human hepatoma cell lines (HepG2), lacking estrogen receptor (ER)-alpha, and Hep89, stably transfected by ERalpha, were used. Setting: The study was conducted at an academic research laboratory and medical center. The study included 10 male patients with recurrent adrenal carcinoma, receiving mitotane (4-6.5 g daily) for more than 6 months. The main outcome measures were SHBG/CBG mRNA levels measured by real-time PCR, culture medium SHBG/CBG concentrations measured by specific immunoassays, and transient transfection experiments with human SHBG proximal promoter reporter constructs. Increased serum SHBG and CBG concentrations, which exceeded normal male limits, were observed in most mitotane-treated patients. In the HepG2 cell line, 17beta-estradiol (E2) or o,p'-DDD treatment had no effect on mRNA or SHBG/CBG concentrations. In contrast, in the Hep89 cell line, E2 increased concentrations of SHBG (r = 0.44, P < 0.0001) and CBG (r = 0.585, P < 0.0001) secreted into culture media in a dose-dependent manner. o,p'-DDD significantly increased SHBG (150% vs. control, P < 0.05) and CBG (184% vs. control, P < 0.05) production by Hep89 cells, at a concentration of 2 x 10(-5) m. Transient transfection experiments in Hep89 cells showed that E2 or o,p'-DDD treatment did not increase the transcriptional activity of the minimal proximal promoter of human SHBG gene. Mitotane increased SHBG/CBG gene expression and liver production by mechanisms requiring the presence of ERalpha.
    Journal of Clinical Endocrinology &amp Metabolism 06/2006; 91(6):2165-70. · 6.43 Impact Factor
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    ABSTRACT: Although various brain regions have been shown to respond to the presentation of visual sexual stimuli (VSS), whether these regions are specifically mediating sexual arousal or whether they mediate general emotional or motivational arousal is unknown. To clarify this issue, our purpose was to map the regions where the response to VSS was related to plasma testosterone. Specific objectives were (i) to identify regions that respond differentially to VSS in untreated hypogonadal patients compared with healthy controls and (ii) to identify in hypogonadal patients the regions that respond differentially to VSS as a function of therapeutically induced increased testosterone levels. In nine male hypogonadal patients, in the same patients under treatment, and in eight healthy males, we used Positron Emission Tomography to investigate responses of regional cerebral blood flow to VSS. Statistical Parametric Mapping was used to locate regions that demonstrated a differential response. Regions responding differentially both in untreated patients compared with controls and in untreated patients compared with themselves under treatment were the right orbitofrontal cortex, insula and claustrum, where the activation was higher in controls than in untreated patients and where activation increased under treatment, and the left inferior frontal gyrus, that demonstrated a deactivation only in controls and in patients under treatment. That these responses appear to depend on testosterone indicates that these regions mediate sexual arousal and not only a process of general emotional or motivational arousal.
    Psychoneuroendocrinology 07/2005; 30(5):461-82. · 5.14 Impact Factor
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    ABSTRACT: The enzymes ornithine aminotransferase (OAT) and ornithine decarboxylase (ODC) share L-ornithine as a common substrate and arginase II produces this amino acid. In the murine kidney, testosterone induced ODC gene expression and polyamine production, but it is unknown how OAT gene is expressed under androgen treatment. These experiments were designed to study the influence of testosterone on the renal expression of OAT gene. Pharmacological and physiological doses of testosterone were injected into female and castrated male mice. Total RNA and soluble proteins extracted from whole kidneys were analyzed by Northern and Western blots, respectively. The results clearly indicate that pharmacological doses of testosterone simultaneously down-regulated the level of OAT protein and up-regulated the expression of arginase II and ODC genes. Variations of the levels of OAT protein and arginase II mRNA and protein were strongly correlated with testosteronemia. Orchidectomy increased the renal level of OAT protein and decreased that of ODC and arginase II. These effects were reversed by injecting a physiological dose of testosterone into castrated male mice. In conclusion, OAT and ODC genes are inversely regulated by testosterone in the mouse kidney. Consequently, in kidneys of testosterone-treated mice, L-arginine-derived ornithine produced by arginase II might be preferentially used by ODC for putrescine production rather than by OAT. This metabolic fate of L-ornithine was facilitated by decreasing OAT gene expression. In contrast, in female and castrated male mice devoided of testosterone, OAT gene is highly expressed and L-ornithine is converted into L-glutamate.
    Endocrinology 02/2005; 146(2):950-9. · 4.72 Impact Factor
  • Annales D Endocrinologie - ANN ENDOCRINOL. 01/2005; 66(5):484-484.

Publication Stats

962 Citations
199.81 Total Impact Points

Institutions

  • 2012
    • University of Yaounde I
      • Department of Biochemistry
      Yaoundé, Centre Province, Cameroon
  • 1989–2012
    • Hospices Civils de Lyon
      Lyons, Rhône-Alpes, France
  • 2009
    • Université de Rennes 1
      Roazhon, Brittany, France
  • 2007
    • CHU de Lyon - Hôpital de la Croix-Rousse
      Lyons, Rhône-Alpes, France
    • University of Lyon
      Lyons, Rhône-Alpes, France
  • 2005
    • French Institute of Health and Medical Research
      Lutetia Parisorum, Île-de-France, France
  • 1993
    • CHU de Lyon - Groupement Hospitalier Edouard Herriot
      Lyons, Rhône-Alpes, France
  • 1988
    • Claude Bernard University Lyon 1
      • Laboratoire de physique
      Villeurbanne, Rhone-Alpes, France