Biomedical subjects

Lucia Perego

Publications and source records attributed to Lucia Perego.

10 recordsLinked to original sources

PubMed2006

Effect of gonadotropins during in vitro maturation of feline oocytes on oocyte-cumulus cells functional coupling and intracellular concentration of glutathione.

Information about the mechanisms of meiotic arrest and resumption of meiosis in feline oocytes is still limited. The aim of this study was to investigate the effect of the presence of gonadotropins during IVM, on meiotic progression in relation to the status of gap junction mediated communications between oocyte and cumulus cells, to the cAMP intracellular content, and to the intra-oocyte concentration of glutathione (GSH) in feline oocytes. Our results indicated that about 50% of cumulus-oocyte complexes (COCs) showed functionally open communications at the time of collection, while the remainder were partially or totally closed. After 3h of culture, the percentage of COCs with functional gap junctions was significantly greater in the group matured in the presence of gonadotropins than in those matured without them, where an interruption of communications was observed. Moreover, this precocious uncoupling was associated with a moderate increase of cAMP concentration in the oocyte, lower than in the group exposed to gonadotropins. Intra-oocyte glutathione levels decreased significantly after 24h of IVM, whether gonadotropins were present or absent during the culturing process. The presence of thiol compounds in the IVM medium induced an intra-oocyte GSH concentration significantly higher than that found in oocytes cultured without these compounds, and similar to the GSH content of immature oocytes. Moreover, the intracellular GSH concentration increased as meiosis progressed. The present study suggests that in feline oocytes, gonadotropins affect the dynamic changes in communications between oocyte and cumulus cells during IVM. However, the intracellular concentration of GSH is not influenced by the gonadotropin stimulation. Moreover, the presence of gonadotropins and thiol compounds results in an increase of GSH levels along with meiotic progression of the oocytes.

Animals↗

PubMed2005

Impact of common polymorphisms in candidate genes for insulin resistance and obesity on weight loss of morbidly obese subjects after laparoscopic adjustable gastric banding and hypocaloric diet.

CONTEXT: It is unknown whether genetic factors that play an important role in body weight homeostasis influence the response to laparoscopic adjustable gastric banding (LAGB). OBJECTIVE: We investigated the impact of common polymorphisms in four candidate genes for insulin resistance on weight loss after LAGB. DESIGN: The design was a 6-month follow-up study. SETTING: The study setting was hospitalized care. PATIENTS: A total of 167 unrelated morbidly obese subjects were recruited according to the following criteria: age, 18-66 yr inclusive; and body mass index greater than 40 kg/m2 or greater than 35.0 kg/m2 in the presence of comorbidities. INTERVENTION: LAGB was used as an intervention. MAIN OUTCOME MEASURE: Measure of correlation between weight loss and common polymorphisms in candidate genes for insulin resistance and obesity was the main outcome measure. RESULTS: The following single nucleotide polymorphisms were detected by digestion of PCR products with appropriate restriction enzymes: Gly972Arg of the insulin receptor substrate-1 gene, Pro12Ala of the proliferator-activated receptor-gamma gene, C-174G in the promoter of IL-6 gene, and G-866A in the promoter of uncoupling protein 2 gene. Baseline characteristics including body mass index did not differ between the genotypes. At the 6-month follow-up after LAGB, carriers of G-174G IL-6 genotype had lost more weight than G-174C or C-174C genotype (P = 0.037), and carriers of A-866A uncoupling protein 2 genotype had lost more weight as compared with G-866G (P = 0.018) and G-866A (P = 0.035) genotype, respectively. Weight loss was lower in carriers of Gly972Arg insulin receptor substrate-1 genotype than Gly972Gly carriers, but not statistically significant (P = 0.06). No difference between carriers of Pro12Ala and Pro12Pro proliferator-activated receptor-gamma genotype was observed. CONCLUSIONS: These data demonstrate that genetic factors, which play an important role in the regulation of body weight, may account for differences in the therapeutic response to LAGB.

Adult↗

PubMed2005

Circulating leptin correlates with left ventricular mass in morbid (grade III) obesity before and after weight loss induced by bariatric surgery: a potential role for leptin in mediating human left ventricular hypertrophy.

CONTEXT: Obesity is frequently associated with left ventricular hypertrophy, even when uncomplicated by hypertension or diabetes mellitus. Left ventricular hypertrophy is an important risk factor for congestive heart failure. OBJECTIVE: The objective of this study was to evaluate the relationship between leptin and left ventricular mass in uncomplicated, morbid (grade 3) obesity and the existence of leptin receptors and intracellular signaling proteins in the human heart. DESIGN: Left ventricular mass (LVM) was calculated through electrocardiogram reading in normotensive grade III obese patients (World Health Organization classification) undergoing bariatric surgery [laparoscopic adjustable gastric banding (LAGB)] at baseline and 1 yr later. The control group was composed of healthy lean normotensive subjects. Leptin receptors were detected by PCR and immunocytochemistry in human heart biopsies. SETTING: This study was performed at university hospitals. PATIENTS: Thirty-one grade 3 obese patients and 30 healthy nonobese normotensive, age- and sex-matched control subjects were studied. INTERVENTION: Obese subjects underwent LAGB to induce weight loss and were evaluated at baseline and after 1 yr. RESULTS: LVM, plasma leptin, glucose, insulin levels, and homeostasis model assessment index were higher in obese than in lean controls (P < 0.01); at univariate regression analysis, LVM correlated with body mass index, leptin, and homeostasis model assessment index; at multiple regression analysis, LVM only correlated with leptin levels (P = 0.001). Obese subjects were reevaluated 1 yr after LAGB, when their body mass index changed from 46.2 +/- 1.24 to 36.6 +/- 1.05 kg/m(2) (P < 0.01); the decrease in LVM correlated only with the decrease in leptin levels (P < 0.01). We demonstrated that long and short isoforms of the leptin receptor and intracellular proteins mediating leptin signaling were expressed in human heart by RT-PCR, immunocytochemistry, or both methods. CONCLUSIONS: These data suggest that leptin could contribute to the left ventricular hypertrophy in humans.

Adult↗

PubMed2005

Morphological and functional differences in haemostatic axis between kidney transplanted and end-stage renal disease patients.

End-stage renal disease (ESRD) is characterized by several atherothrombotic abnormalities, and kidney transplant seems to improve most of them. However, because it is not clear which mechanism is responsible for such improvement, our purpose was to clarify that point.We conducted a cross sectional study involving 30 ESRD patients, 30 ESRD kidney-transplanted patients (Ktx) and 30 healthy controls (C) to evaluate platelet morphology and function, atherothrombotic profile, endothelial abnormalities and cytokine levels involved in the insulin resistance/endothelial dysfunction. (i) Platelet morphology: The ESRD group showed platelet size similar to the other two groups (ESRD=3518x10(3)+/-549x10(3) nm2, C=3075x10(3)+/-197x10(3) nm2, Ktx=2862x10(3)+/-205x10(3) nm2) with similar platelet granules and number. (ii) Platelet surface glycoprotein: The CD41 and P-Selectin were similar between groups. (iii) Platelet intracellular calcium: Resting intracellular calcium was statistically higher in ESRD compared to the C group (ESRD=182.1+/-34.5, Ktx=126.7+/-14.1, C=72.0+/-11.0 nM, P<0.01). (iv) Hypercoagulability markers and natural anticoagulants: The Ktx and ESRD groups showed higher levels of hypercoagulability markers compared to the C group. A reduction in antithrombin activity was evident in ESRD compared to the Ktx group (P=0.03). (v) Endothelial morphology: The ESRD group showed a thickened vessel basal membrane compared to the Ktx and C groups with more endothelial sufference. (vi) Insulin resistance and pro-inflammatory cytokine profile: The ESRD showed a higher homeostasis model assessment provided equations for estimating insulin resistance (HOMA-IR) compared to the Ktx and C groups (ESRD=2.6+/-0.3, Ktx=1.8+/-0.2, C=1.1+/-0.1, P=0.005) and increased soluble tumor neurosis factor alpha (sTNFalpha) (P<0.05) and soluble vascular cell adhesion molecule (sVCAM) levels (P<0.01). Positive correlations were evident among HOMA-IR and sTNFalpha (P<0.001) and sVCAM (P=0.01), respectively. In a small subgroup of ESRD who underwent Ktx (five pts), our findings were confirmed at 1 year of follow-up, suggesting an improvement of almost haemostatic abnormalities. Kidney transplant is associated with a better atherothrombotic profile in ESRD, platelet intracellular calcium and cytokines seem to be most influenced by the transplant, while most morphological abnormalities are retained.

Adult↗

PubMed2005

Laparoscopic gastric banding prevents type 2 diabetes and arterial hypertension and induces their remission in morbid obesity: a 4-year case-controlled study.

OBJECTIVE: Lifestyle modifications and pharmacological interventions can prevent type 2 diabetes in obese subjects with impaired glucose tolerance. The aim of this study was to compare laparoscopic adjustable gastric banding (LAGB) and conventional diet (No-LAGB) in the prevention (primary intervention study; 56 vs. 29 patients) and remission (secondary intervention study; 17 vs. 20 patients) of type 2 diabetes and hypertension in grade 3 obesity in a 4-year study. RESEARCH DESIGN AND METHODS: The subjects (n = 122; age 48.5 +/- 1.05 years; BMI 45.7 +/- 0.67 kg/m2) underwent a diagnostic workup, including psychological and psychiatric assessments, in preparation for the LAGB procedure. Of the 122 subjects, 73 had the surgery (LAGB group). The control group (No-LAGB group) consisted of the 49 subjects who refused the surgery but agreed to be followed up; 6 of these subjects dropped out by the 2nd year of the study, so that the final number of patients was 73 and 43 in the LAGB and No-LAGB groups, respectively. All patients had a yearly visit and oral glucose tolerance test. RESULTS: From baseline to the end of the 4-year follow-up, BMI decreased from 45.9 +/- 0.89 at baseline to 37.7 +/- 0.71 kg/m2 in the LAGB group and remained steady in the No-LAGB group (from 45.2 +/- 1.04 to 46.5 +/- 1.37 kg/m2), with no significant differences between the primary and secondary intervention groups. In the primary intervention study, five of the No-LAGB subjects (17.2%) and none of the LAGB subjects (0.0%; P = 0.0001) progressed to type 2 diabetes; in the secondary intervention study, type 2 diabetes remitted in one No-LAGB patient (4.0%) and seven LAGB patients (45.0%; P = 0.0052). Hypertension occurred in 11 No-LAGB patients (25.6%) and 1 LAGB patient (1.4%; P = 0.0001) and remitted in 1 No-LAGB (2.3%) and 15 LAGB patients (20.5%; P = 0.0001). A study of body mass composition revealed a significant reduction of fat mass and a transitory, but not significant, decrease of fat-free mass in LAGB patients. CONCLUSIONS: In morbid obesity, sustained and long-lasting weight loss obtained through LAGB prevents the occurrence of type 2 diabetes and hypertension and decreases the prevalence of these disorders.

Adult↗

PubMed2005

C-174G polymorphism in the promoter of the interleukin-6 gene is associated with insulin resistance.

OBJECTIVE: The C-174G promoter polymorphism of the interleukin (IL)-6 gene was found to influence transcriptional activity and plasma IL-6 levels in humans. We addressed the question of whether the C-174G IL-6 polymorphism contributes to variation of insulin sensitivity. RESEARCH DESIGN AND METHODS: Two cohorts of subjects were genotyped. Cohort 1 includes 275 nondiabetic subjects who underwent a euglycemic-hyperinsulinemic clamp. Cohort 2 includes 77 patients with morbid obesity who underwent laparoscopic adjustable gastric banding (LAGB). RESULTS: The genotypes were consistent with Hardy-Weinberg equilibrium proportions. In cohort 1, insulin sensitivity was reduced in carriers of the -174G/G genotype as compared with subjects carrying the C allele (P = 0.004). Carriers of -174G/G displayed significantly higher plasma IL-6 levels in comparison with carriers of the C allele. In a stepwise linear regression analysis, the C-174G polymorphism was independently associated with insulin sensitivity; however, after inclusion of plasma IL-6 concentrations, the polymorphism was excluded from the model explaining insulin sensitivity variability, thus suggesting that the polymorphism was affecting insulin sensitivity by regulating IL-6 plasma levels. IL-6 mRNA levels were measured by real-time RT-PCR in subcutaneous fat obtained from obese patients of cohort 2 during LAGB. Carriers of -174G/G showed increased IL-6 expression compared with subjects carrying the C allele (P = 0.04). There was a significant correlation between adipose IL-6 mRNA expression and insulin resistance assessed by homeostasis model assessment (rho = 0.28, P = 0.014). CONCLUSIONS: These results indicate that the -174G/G genotype of the IL-6 gene may contribute to variations in insulin sensitivity.

Adipose Tissue↗

PubMed2004

The -866A/A genotype in the promoter of the human uncoupling protein 2 gene is associated with insulin resistance and increased risk of type 2 diabetes.

Uncoupling protein (UCP)-2 is a member of the mitochondrial inner membrane carriers that uncouple pro-ton entry in the mitochondrial matrix from ATP synthesis. The -866G/A polymorphism in the UCP2 gene, which enhances its transcriptional activity, was associated with enhanced risk for type 2 diabetes in obese subjects. We addressed the question of whether the -866G/A polymorphism contributes to variation in insulin sensitivity by genotyping 181 nondiabetic offspring of type 2 diabetic patients. Insulin sensitivity, assessed by the hyperinsulinemic-euglycemic clamp, was reduced in -866A/A carriers compared with -866A/G or -866G/G carriers (P = 0.01). To directly investigate the correlation between UCP2 expression and insulin resistance, UCP2 mRNA levels were measured by real-time RT-PCR in subcutaneous fat obtained from 100 obese subjects who underwent laparoscopic adjustable gastric banding. UCP2 mRNA expression was significantly correlated with insulin resistance as assessed by the homeostasis model assessment index (r = 0.27, P = 0.007). We examined the association of the -866A/A genotype in a case-control study including 483 type 2 diabetic subjects and 565 control subjects. The -866A/A genotype was associated with diabetes in women (odds ratio 1.84, 95% CI 1.03-3.28; P = 0.037), but not in men. These results indicate that the -866A/A genotype of the UCP2 gene may contribute to diabetes susceptibility by affecting insulin sensitivity.

Adipose Tissue↗

PubMed2003

Chronic hyperglycemia impairs insulin secretion by affecting insulin receptor expression, splicing, and signaling in RIN beta cell line and human islets of Langerhans.

Recent evidence suggests that insulin signaling through the insulin receptor A type (Ex11-), regulates insulin gene transcription. Because chronic hyperglycemia negatively affects insulin receptor function and regulates alternative splicing of the insulin receptor, we inquired whether chronic exposure of pancreatic beta-cells to high glucose results in alterations in insulin signaling due to changes in insulin receptor expression and relative abundance of its spliced isoforms. Our results demonstrate that the insulin receptor is localized in insulin secretory vescicles in human pancreatic beta-cells. Furthermore, we find that alterations in insulin expression and secretion caused by chronic exposure to high glucose are paralleled by decreased insulin receptor expression and increased relative abundance of the Ex11+ isoform in both human islets and RIN beta-cells. PDX-1 and HMGI(Y) transcription factors are down-regulated by high glucose. These changes are associated with defects in insulin signaling involving insulin receptor-associated PI 3-kinase/Akt/PHAS-I pathway in RIN beta-cells. Re-expression in RIN beta-cells chronically exposed to high glucose of the Ex11-, but not the Ex11+, isoform restored insulin mRNA expression. These data suggest that changes in early steps of insulin receptor signaling may play a role in determining beta-cell dysfunction caused by chronic hyperglycemia.

Adaptor Proteins, Signal Transducing↗

PubMed2002

Obesity modulates the expression of haptoglobin in the white adipose tissue via TNFalpha.

Increase in adipose mass results in obesity and modulation of several factors in white adipose tissue (WAT). Two important examples are tumor necrosis factor alpha (TNFalpha) and leptin, both of which are upregulated in adipose tissue in obesity. In order to isolate genes differentially expressed in the WAT of genetically obese db/db mice compared to their lean littermates, we performed RNA fingerprinting and identified haptoglobin (Hp), which is significantly upregulated in the obese animals. Hp is a glycoprotein induced by a number of cytokines, LPS (Lipopolysaccharide), and more generally by inflammation. A significant upregulation of WAT Hp expression was also evident in several experimental obese models including the yellow agouti (/) A(y), ob/ob and goldthioglucose-treated mice (10-, 8-, and 7-fold, respectively). To identify the potential signals for an increase in Hp expression in obesity, we examined leptin and TNFalpha in vivo. Wild type animals treated with recombinant leptin did not show any alteration in WAT Hp expression compared to controls that were food restricted to the level of intake of the treated animals. On the other hand, Hp expression was induced in mice transgenically expressing TNFalpha in adipose tissue. Finally, a significant downregulation of WAT Hp mRNA was observed in ob/ob mice deficient in TNFalpha function, when compared to the ob/ob controls. These results demonstrate that haptoglobin expression in WAT is increased in obesity in rodents and TNFalpha is an important signal for this regulation.

Adipocytes↗

PubMedDate not supplied

The multi-faceted cross-talk between the insulin and angiotensin II signaling systems.

Insulin and angiotensin II are hormones that play pivotal roles in the control of two vital and closely related systems, the metabolic and the circulatory systems, respectively. A failure in the proper action of each of these hormones results, to a variable degree, in the development of two highly prevalent and commonly overlapping diseases-diabetes mellitus and hypertension. In recent years, a series of studies has revealed a tight connection between the signal transduction pathways that mediate insulin and angiotensin II actions in target tissues. This molecular cross-talk occurs at multiple levels and plays an important role in phenomena that range from the action of anti-hypertensive drugs to cardiac hypertrophy and energy acquisition by the heart. At the extracellular level, the angiotensin-converting enzyme controls angiotensin II synthesis but also interferes with insulin signaling through the proper regulation of angiotensin II and through the accumulation of bradykinin. At an early intracellular level, angiotensin II, acting through JAK-2/IRS-1/PI3-kinase, JNK and ERK, may induce the serine phosphorylation and inhibition of key elements of the insulin-signaling pathway. Finally, by inducing the expression of the regulatory protein SOCS-3, angiotensin II may impose a late control on the insulin signal. This review will focus on the main advances obtained in this field and will discuss the implications of this molecular cross-talk in the common clinical association between diabetes mellitus and hypertension.

Angiotensin II↗