[Mutltifaceted biological roles of leptin]. / Rôles biologiques à multiples facettes de la leptine.

The identification of leptin allowed the discovery of a new endocrine system. This major adipokine controlling energy homeostasis is also involved in the regulation of neuroendocrine function and fertility. Unfortunately, leptin is not able to treat common obesity, which associates hyperleptinemia and resistance to the hormone. Conversely, treatment with recombinant leptin is effective in situations of leptin deficiency. Several pathophysiological situations associated with adipose tissue dysfunctions and abnormal regulation of leptin secretion are discussed in this review. The advantage of the potential use of the leptin assay in some pathophysiological conditions is proposed.

[Mutltifaceted biological roles of adiponectin]. / Rôles biologiques à multiples facettes de l'adiponectine.

Adiponectin is a major adipokine involved in energy homeostasis that exerts insulin-sensitizing properties. The level of adiponectin is reduced in situations of insulin resistance and is negatively associated with several pathophysiological situations including abdominal obesity, metabolic syndrome, steatosis and non-alcoholic steatohepatitis, type 2 diabetes, some cancers and cognitive diseases. These aspects are discussed in this review.

The neurobehavioral effects of the designer drug naphyrone - an experimental investigation with pharmacokinetics and concentration/effect relationship in mice.

RATIONALE: The recreational use of naphyrone, a potent synthetic cathinone with a pyrovalerone structure, has raised questions about possible deleterious neurobehavioral consequences. OBJECTIVE: To investigate naphyrone-induced neurobehavioral effects and alterations in brain monoamines using two patterns of abuse, i.e., single and repeated (binge) use. METHODS: We studied naphyrone dose/induced locomotor activity relationship at 3, 10, 30, and 100 mg/kg in mice. We investigated the effects of single (30 mg/kg; acute injection) versus repeated (30 mg/kg ×3/day for 3 days; binge injection) intraperitoneal naphyrone administration on locomotor activity, anxiety-like behavior, spatial recognition memory, anhedonia, behavioral despair, and social interaction. We measured post-mortem prefrontal cortex levels of monoamines and modeled naphyrone pharmacokinetics and concentration/locomotor effect relationship. RESULTS: Both naphyrone administration patterns induced time-dependent increases in locomotor activity (p < 0.001 and p < 0.0001, respectively) and social interaction (p < 0.05 and p < 0.001, respectively) but did not alter spatial recognition memory or anhedonia. Acute naphyrone injection induced anxiety-like behavior (p < 0.01) and reduced resignation (p < 0.01) whereas binge administration induced non-anxiety-like behavior (p < 0.05) and did not alter behavioral despair. Both patterns increased the prefrontal cortex dopamine (p < 0.0001) and norepinephrine (p < 0.05 and p < 0.01, respectively) but not serotonin content. Naphyrone pharmacokinetics followed a two-compartment model with an overall elimination half-life of 0.3 h. The naphyrone concentration/locomotor effect relationship was described by an additive Emax model with an EC50 of 672 µg/L. CONCLUSIONS: Single naphyrone administration increases locomotor activity according to a direct concentration/effect relationship. The neurobehavioral effects after binge differs from those after single administration and are not explained by drug accumulation given the relatively fast elimination.

[Utility of soluble transferrin receptor measurement for early diagnostic of iron deficiency in elderly hospitalized patients]. / Intérêt du dosage du récepteur soluble de la transferrine dans le diagnostic biologique précoce du déficit martial chez les patients âgés hospitalisés.

Diagnosis of iron deficiency is not easily performed in inflammatory situation as usually encountered in elderly hospitalized patients (>70 years old). At first, we determined serum soluble receptor transferrin (RsTf), RsTf/serum ferritin ratio (RsTf-F index) and biochemical and haematological values used to evaluate iron status, in iron-depleted subjects (ferritinemia≤50 µg/L) (group 2) (n=22, 82±7 years) or not (group 1, reference group) (n=18, 82±6 years), without inflammatory diseases. Relevance of the biological parameters to diagnose iron deficiency was evaluated (ROC curve) and a cut-off value of RsTf-F (>1.85) was established. Then, we selected 60 patients (group 3) suspect of iron deficiency as previously validated with an inflammatory syndrome (CRP>12 mg/L). Almost all patients (95%) presented at least one risk factor of iron deficiency (anticoagulant drugs, nutritional or gastrointestinal diseases). In group 3, index RsTf-F values were increased (RsTf-F: 2.69±0.82 versus group 1: 1.25±0.34, p<0.05), in anemic patients (women Hb<120 g/L, men Hb<130 g/L) (n=42) and in non-anemic patients (n=18) (respectively RsTf-F: 2.84±0.87 versus 2.35±0.58, p<0.05). Thus, in elderly patients with inflammatory disorders, RsTf-F index could suspect iron deficiency before appearance of biological anemia.

Genotype-phenotype correlations for exudative age-related macular degeneration associated with homozygous HTRA1 and CFH genotypes.

PURPOSE: Major genetic factors for age-related macular degeneration (AMD) have recently been identified as susceptibility risk factors, including polymorphisms of HTRA1 and CFH genes. The purpose was to analyze the angiographic features of patients harboring homozygous genotypes for HTRA1 and CFH genes in a French exudative AMD population. METHODS: Two hundred patients affected with exudative AMD were genotyped for the polymorphisms rs11200638 of the HTRA1 gene and rs10611710 of the CFH gene. Four homozygous groups were extracted from the entire cohort: double homozygous for wild-type alleles of both genes (group 1), homozygous for the polymorphism of the HTRA1 gene only (group 2), homozygous for the polymorphism of the CFH gene only (group 3), and double homozygous carriers for both polymorphisms (group 4). Choroidal neovascularization (CNV) was graded as classic and predominantly classic (PC), occult, minimally classic (MC), or retinal angiomatosis proliferation (RAP). RESULTS: Group 1 (n = 9) presented 44.4% classic and PC, 33.3% occult, 11.1% MC, and 11.1% RAP. Group 2 (n = 12) presented 50.0% classic and PC, 33.3% occult, no MC CNV and 16.7% RAP. Group 3 (n = 28) presented 10.7% classic and PC, 67.9% occult, 14.3% MC, and 7.1% RAP. Group 4 (n = 17) presented 29.4% classic and PC, 52.9% occult, 11.8% MC, and 5.9% RAP. Occult CNV or MC CNV was more frequently observed in group 3 than in group 2 (82.1% vs 33.3%; P < 0.02). Classic and PC CNV were more frequently observed in group 2 than in group 3 (50% vs. 10.7%; P < 0.03). CONCLUSIONS: This attempt at a genotypic-angiographic correlation in an exudative AMD sample suggests an association between occult or MC CNV and the CFH polymorphism and between classic and PC CNV and the HTRA1 polymorphism.

PLEKHA1-LOC387715-HTRA1 polymorphisms and exudative age-related macular degeneration in the French population.

PURPOSE: Identification of genetic factors for age-related macular degeneration (AMD) is of crucial importance in this common cause of blindness. Exudative AMD is rapidly progressive and usually associated with severe prognosis. Our purpose was to investigate this association on locus 10q26 in a case-control study including French patients specifically affected with exudative AMD. METHODS: Polymorphisms rs4146894:G>A of Pleckstrin Homology Domain-containing Protein Family A member 1 (PLEKHA1) gene, rs10490924:G>T at LOC387715, and rs11200638:G>A of HTRA1 (HTRA serine peptidase 1) gene were analyzed in AMD cases (n=118, age=72.3+/-3.8 years old) and healthy controls (n=116, age=72.0+/-3.8 years old). RESULTS: PLEKHA1 polymorphism was associated with AMD. The A allele frequency was 0.67 in cases versus 0.41 in controls, (p=0.0001). After age and sex adjustment, the odds ratio for risk of AMD was 9.1 (4.0-20.9, 95% CI, p=0.0001) for the AA genotype and 2.6 (1.3-5.5, 95% CI, p=0.04) for the AG genotype, conditional on HTRA1. Association was even stronger and independent with HTRA1. The A allele frequency was 0.51 in cases versus 0.22 in controls, (p=0.0001). The odds ratio was 15.5 (5.5-43.9, 95% CI, p=0.0001) for the AA genotype and 3.4 (1.9-6.1, 95% CI, p=0.0001) for the AG genotype. No further information was obtained from LOC387715 due to virtually complete linkage disequilibrium with HTRA1 polymorphism in cases (D'=1.0) and controls (D'=0.98). Although a role for PLEKHA1 could not be totally excluded, there was a four times higher AMD risk was associated with haplotype "A-T-A" involving "PLEKHA1-LOC387715-HTRA1" risk alleles. CONCLUSIONS: Compared to PLEKHA1, HTRA1/LOC387715 genetic variations were independently and strongly associated with exudative AMD in the French population. Chromosome-10 genetic variants appear as potentially useful risk markers for early detection of AMD.

Very low oral doses of vitamin B-12 increase serum concentrations in elderly subjects with food-bound vitamin B-12 malabsorption.

The BOSSANOVA study, a randomized double-blind trial, was designed to test the ability of very low oral doses of vitamin B-12 to increase the serum vitamin B-12 concentration in elderly subjects with food-bound vitamin B-12 malabsorption, and to determine whether there was a dose response. We also aimed to quantitatively assess the most efficient dose to be added to flour in addition to folic acid (flour cofortification with vitamin B-12 and folic acid). Sixty-seven patients were randomly assigned to 1 of 6 groups receiving various daily oral doses of vitamin B-12 (i.e., 2.5, 5, 10, 20, 40, or 80 microg/d) for 30 d. The dose-response was tested for different biological variables using a mixed model, taking into account the variable's initial value (between-subject effect), a linear log-dose effect, and a linear log (dosextime) interaction, where time was d 15 or d 30. We planned to determine the amount of oral vitamin B-12 that would increase the serum vitamin B-12 concentration by 37 pmol/L (50 ng/L). Significant between-subject effects were found for serum vitamin B-12, plasma homocysteine, and methylmalonic acid concentrations, but a log-dose effect was found only for vitamin B-12 (P<0.001). The slope of the line tended to be higher (P=0.07) at d 30 than at d 15. For a mean serum vitamin B-12 increase of 37 pmol/L, a dose of 5.9 (95% CI, 0.9-12.1) microg/d was needed. We concluded that very low oral doses of vitamin B-12 increased serum vitamin B-12 concentrations in elderly subjects with subclinical vitamin B-12 deficiency, following a log-dose pattern. Our results could be beneficial in the design of a public health program for safe flour cofortification with folic acid.

Apparent mineralocorticoid excess: report of six new cases and extensive personal experience.

In mineralocorticoid target tissues such as the cortical collecting duct in the kidney, the enzyme 11beta-hydroxysteroid dehydrogenase type 2 (11betaHSD2) is responsible for the peripheral inactivation of cortisol to cortisone, thereby protecting the mineralocorticoid receptor from inappropriate activation by cortisol. Mutations in the HSD11B2 gene cause the syndrome of apparent mineralocorticoid excess, an autosomal recessive form of inherited hypertension in which cortisol acts as a potent mineralocorticoid. Herein are described six new families with mutations in the HSD11B2 gene causing hypokalemic hypertension, with low plasma aldosterone and low renin levels in affected individuals, indicating mineralocorticoid hypertension. Profiling of urinary steroid metabolites showed decreased cortisol inactivation, with urinary tetrahydrocortisol and tetrahydrocortisone ratio (THF + 5alphaTHF)/THE ranging 2.4 to 40 and nearly absent urinary free cortisone in all but one case. Genetic analysis of the HSD11B2 gene from these patients with apparent mineralocorticoid excess revealed distinct homozygous point mutations in four families, a compound heterozygous mutation in one family, and a large 23-bp exonic insert with frameshift and disruption of the amino acid sequence in another family. Expression studies of mutants that were expressed in HEK-293 cells showed marked reduction or abolition of 11betaHSD2 enzymatic activity. These cases are reviewed along with previous ones from the authors' extensive personal experience to highlight the importance of 11betaHSD2 in the understanding of a new biologic principle in hormone action, demonstrating that local metabolism of the glucocorticoid hormones into inactive derivatives by the enzyme 11betaHSD2 is one of the mechanisms that intervene to allow specific aldosterone regulatory effects.

Geriatric Nutritional Risk Index: a new index for evaluating at-risk elderly medical patients.

BACKGROUND: Patients at risk of malnutrition and related morbidity and mortality can be identified with the Nutritional Risk Index (NRI). However, this index remains limited for elderly patients because of difficulties in establishing their normal weight. OBJECTIVE: Therefore, we replaced the usual weight in this formula by ideal weight according to the Lorentz formula (WLo), creating a new index called the Geriatric Nutritional Risk Index (GNRI). DESIGN: First, a prospective study enrolled 181 hospitalized elderly patients. Nutritional status [albumin, prealbumin, and body mass index (BMI)] and GNRI were assessed. GNRI correlated with a severity score taking into account complications (bedsores or infections) and 6-mo mortality. Second, the GNRI was measured prospectively in 2474 patients admitted to a geriatric rehabilitation care unit over a 3-y period. RESULTS: The severity score correlated with albumin and GNRI but not with BMI or weight:WLo. Risk of mortality (odds ratio) and risk of complications were, respectively, 29 (95% CI: 5.2, 161.4) and 4.4 (95% CI: 1.3, 14.9) for major nutrition-related risk (GNRI: <82), 6.6 (95% CI: 1.3, 33.0), 4.9 (95% CI: 1.9, 12.5) for moderate nutrition-related risk (GNRI: 82 to <92), and 5.6 (95% CI: 1.2, 26.6) and 3.3 (95% CI: 1.4, 8.0) for a low nutrition-related risk (GNRI: 92 to < or =98). Accordingly, 12.2%, 31.4%, 29.4%, and 27.0% of the 2474 patients had major, moderate, low, and no nutrition-related risk, respectively. CONCLUSION: GNRI is a simple and accurate tool for predicting the risk of morbidity and mortality in hospitalized elderly patients and should be recorded systematically on admission.

Cardiac specific increase in aldosterone production induces coronary dysfunction in aldosterone synthase-transgenic mice.

BACKGROUND: Elevated circulating aldosterone level is associated with impaired cardiovascular function. Although the mechanisms are not fully understood, aldosterone antagonists decrease total and cardiovascular mortality in heart failure and myocardial infarction. Aldosterone induces cardiac fibrosis in experimental models, and it is synthesized locally in rat heart. These observations suggest pathological effects of aldosterone in heart that remain unclear. METHODS AND RESULTS: Transgenic mice (TG) that overexpress the terminal enzyme of aldosterone biosynthesis, aldosterone synthase (AS), in heart have been raised by gene targeting with the alpha-myosin heavy chain promoter. AS mRNA increased 100-fold and aldosterone concentration 1.7-fold in hearts of male TG mice relative to wild-type. No structural or myocardial alterations were evidenced, because ventricle/body weight, AT1 and AT2 receptor binding, and collagen content were unchanged in TG. No alteration in cardiac function was evidenced by echocardiography, isolated perfused heart, or whole-cell patch clamp experiments. In contrast, coronary function was impaired, because basal coronary flow was decreased in isolated perfused heart (-55% of baseline values), and vasodilatation to acetylcholine, bradykinin, and sodium nitroprusside was decreased by 75%, 60%, and 75%, respectively, in TG mice compared with wild-type, showing that the defect was not related to NO production. CONCLUSIONS: Increased cardiac aldosterone production in male mice induces a major coronary endothelium-independent dysfunction with no detectable alterations in cardiac structure and function. However, coronary dysfunction may be harmful for coronary adaptation to increased flow demand.

Impaired 11-beta hydroxysteroid dehydrogenase type 2 activity in sweat gland ducts in human essential hypertension.

The enzyme 11-beta hydroxysteroid dehydrogenase type 2 plays a major role in blood pressure regulation. It metabolizes glucocorticoid hormones into derivatives with low affinity for the mineralocorticoid receptor, preventing its permanent occupancy by circulating cortisol, which is 100- to 1000-fold more abundant than aldosterone in the plasma. Inactivating mutations of the enzyme result in severe hypertension, as seen in children with apparent mineralocorticoid excess syndrome. In patients with essential hypertension, however, attempts to evidence enzyme deficiency have been inconclusive. In this pilot study, its catalytic activity was measured directly in aldosterone-sensitive sweat gland ducts collected from skin biopsy samples of 10 male normotensive subjects and 10 subjects with essential hypertension (more than 140 to 90 mm Hg) with no sign of hypermineralocorticism. Isolated ducts were assayed for nicotinamide-dinucleotide-dependent dehydrogenase activity (transformation of tritiated corticosterone into tritiated-11 dehydrocorticosterone, as measured by high-pressure liquid chromatography). Hypertensive patients exhibited significantly lower 11-beta hydroxysteroid dehydrogenase type 2 activity (9.7+/-4.7 femtomoles per 3 mm length of duct and per 10 minutes incubation, median+/-SD) than did normotensive subjects (15.9+/-2.6). Such defect was undetectable using the classical urinary corticosteroid metabolism indexes, probably because of compensatory mechanisms. Relations between these findings and blood pressure levels should benefit from direct enzyme measurements in the vasculature. In conclusion, this cross-sectional study points to partial 11-beta hydroxysteroid dehydrogenase type 2 deficiency as a novel feature of essential hypertension, which should stimulate search for new signaling pathways and therapeutical targets.