Genetic variation in the visfatin (PBEF1/NAMPT) gene and type 2 diabetes in the Greek population.

Visfatin (NAMPT formerly known as PBEF1) is an adipokine that is strongly expressed in visceral fat and has caused much debate among researchers, regarding its involvement in glucose homeostasis and insulin resistance. It was initially isolated from bone marrow cells, and its involvement in inflammatory procedures such as sepsis and acute lung inflammation is now evident. Several studies have also reported an association of plasma visfatin levels with obesity. We undertook an evaluation of the involvement of the NAMPT gene in the development of type 2 diabetes (T2DM) in the Greek population. We studied 178 patients with T2DM and 177 controls that were matched for sex, age and body mass index. We genotyped three tagging SNPs selected from the HapMap II CEPH European population as reference for the Greek population. These three SNPs tag another 12 SNPs over the entire NAMPT gene with a mean r(2) of 0.92. No indications of association with disease status were found with any of the tested variants or the inferred haplotypes. Results were also negative when the quantitative traits of weight and BMI were tested. Although our study covers common variants across the NAMPT gene, the possible involvement of rare variants in T2DM etiology cannot be ruled out and will require the investigation of very large numbers of cases and controls.

Acute effect of smoking on plasma Obestatin levels.

BACKGROUND: Smoking and smoking cessation are considered to be associated with weight changes. We have recently shown that smoking acutely increases plasma levels of ghrelin, a known orexigenic hormone. Obestatin is a peptide encoded by the ghrelin gene, which opposes ghrelin effects on food intake. We conducted a study in adult volunteers measuring plasma levels of obestatin immediately after initiation of smoking. METHODS: 31 volunteers (mean age 32.2 +/- 9.2 years and mean BMI 25.7 +/- 4.1), 17 smokers and 14 non-smokers, were enrolled in our study. The 2 groups were matched in age and BMI. Plasma obestatin concentrations were determined at baseline (T0), 2 (T2), 5 (T5), 15 (T15), and 60 (T60) minutes after the initiation of smoking. RESULTS: In all 31 subjects, no significant difference in the mean values of plasma obestatin levels was observed from baseline at T2, T5, T15 and T60 after initiation of smoking (overall p = 0.15). However, a trend for higher obestatin levels was noted in smokers vs non-smokers (overall p = 0.069), which was not related to the pack-years. CONCLUSION: On the contrary with ghrelin's response after smoking initiation, there is no such an acute response of plasma obestatin levels.

A polymorphism in the resistin gene promoter is associated with body mass index in women with polycystic ovary syndrome.

Resistin does not appear to be a major gene predisposing to polycystic ovary syndrome (PCOS). However, an association of a resistin variant with body mass index was found in women with PCOS, suggesting that resistin may be related to adiposity in PCOS.

Association of the T45G polymorphism in exon 2 of the adiponectin gene with polycystic ovary syndrome: role of Delta4-androstenedione.

BACKGROUND: Insulin resistance is a prominent feature of polycystic ovary syndrome (PCOS), independent of obesity. It is possible that insulin resistance in PCOS is genetically determined. Adiponectin is a protein that modulates insulin action and is regarded as a possible link between adiposity and insulin resistance. The objective of this study was to examine the role of the adiponectin gene T45G polymorphism, located in exon 2, in PCOS, since this polymorphism has been shown to be associated with obesity and insulin resistance. SUBJECTS AND METHODS: Two hundred and thirty-two women were studied, and were classified as follows: 132 women with PCOS [62 with body mass index (BMI) > 25 kg/m2 and 70 with BMI < 25 kg/m2] and 100 ovulating women without hyperandrogenemia (controls: 19 with BMI > 25 kg/m2 and 81 with BMI < 25 kg/m2). From all subjects a whole-blood sample was taken and was used for isolation of peripheral blood leukocytes. The adiponectin T45G polymorphism, located in exon 2, was genotyped by amplification of genomic DNA. In all subjects, serum gonadotropin, androgen, 17-OH-progesterone, fasting glucose, insulin and adiponectin levels were measured between the third and sixth day of the menstrual cycle. RESULTS: A statistically significant difference was observed in the frequency of GG and TG genotypes between women with PCOS (40/132; 30.3%) and controls (19/100; 19.0%). In a subgroup of PCOS women with high Delta4-androstenedione levels (Delta4A > 3.11 ng/ml), a statistically significant difference between the frequencies of the genotypes was also noticed compared with the control group, in contrast to the subgroup with relatively low Delta4-androstenedione levels (Delta4A < 3.11 ng/ml). No significant associations were found between this adiponectin polymorphism and BMI, testosterone level, adiponectin levels and glucose-to-insulin ratio. CONCLUSIONS: Our study suggests that adiponectin polymorphisms are not causatively involved in the metabolic disturbances of PCOS, but that an interaction between adiponectin and steroid synthesis or action might exist.

Differential effects of unopposed versus opposed hormone therapy, tibolone, and raloxifene on substance p levels.

OBJECTIVE: To evaluate the effects of unopposed therapy (conjugated equine estrogens [CEE]) vs. opposed therapy (CEE and medroxyprogesterone acetate), tibolone, and raloxifene on serum substance p levels. DESIGN: Clinical study. SETTING: University hospital. PATIENT(S): One hundred eight postmenopausal women were assigned to four treatment groups: unopposed hormone therapy (HT) (n = 30), opposed HT (n = 48), tibolone (n = 18), and raloxifene (n = 12). INTERVENTION(S): Conjugated equine estrogens, CEE and medroxyprogesterone acetate, tibolone, and raloxifene were administered orally; blood samples were collected before therapy and 3 months after. MAIN OUTCOME MEASURE(S): Serum substance p levels were measured before and at the end of the third month of the treatment.The serum substance p levels were increased in the unopposed HT group after treatment. On the contrary, substance p levels were decreased in the opposed HT group, in the tibolone group, and in the raloxifene group. CONCLUSION(S): Addition of progesterone (P) to estrogen (E) treatment significantly decreases serum substance p levels. Tibolone and raloxifene exert the same effect.

Parental genomic imprinting in endocrinopathies.

Genomic imprinting is the phenomenon whereby some genes preferentially produce mRNA transcripts from the gene copy derived from the parent of a specific sex. It has been implicated in a number of human diseases (most of them of endocrine interest), such as Prader-Willi/Angelman syndromes, Silver-Russell syndrome, Beckwith-Wiedemann syndrome, transient neonatal diabetes, the focal form of nesidioblastosis, and pseudohypoparathyroidism. Involvement of imprinted genes affecting birth weight and causing susceptibility to type 1 diabetes is under investigation. Recent knowledge about the varied molecular mechanisms involved will be outlined.