Walkiria Lopes Miranda

Prevalence of vitamin D receptor gene polymorphisms FokI and BsmI in Brazilian individuals with type 1 diabetes and their relation to β-cell autoimmunity and to remaining β-cell function

The effect of the vitamin D receptor (VDR) gene polymorphisms on susceptibility to type 1 diabetes (T1DM) is heterogeneous. Genetic factors may also influence the residual beta-cell function. We studied the frequency of VDR FokI (rs10735810) and BsmI (rs154410) polymorphisms in T1DM and their relationship to beta-cell autoimmunity and residual beta-cell function. We genotyped 189 T1DM (diabetes duration, 7.1 +/- 5.4 years) and 194 controls (C) by restriction length polymorphism-polymerase chain reaction. GAD65Ab, IA2Ab, ionized calcium (iCa), HbA(1c)and fasting C-peptide (FCP) were evaluated. FCP values greater than 0.6 ng/ml were considered as residual beta-cell function. The BsmI was more frequent in the C (bb plus Bb 79.1 C vs. 66.1% T1DM, p = 0.006), and the FokI polymorphism frequencies were similar between T1DM and C. We did not observe differences in pancreatic autoantibody profiles according to VDR genotypes. We observed that T1DM with f allele tended to have lower residual pancreatic beta-cell function (5.8% ff and Ff vs. 14.3% FF, p = 0.074) with similar age, diabetes duration, AAb positivity, HbA(1c), and iCa. Age at diagnosis of T1DM with BsmI polymorphism tended to be greater (10.7 +/- 4.9 bb and Bb vs. 9.3 +/- 4.5 years BB, p = 0.06). In conclusion, the results of this study showed no relationship between VDR polymorphisms and beta-cell autoimmunity; however we observed a relationship with age and remaining beta-cell function in Brazilian individuals with T1DM. These data may contribute to understanding the heterogeneous relationship between genetic markers and clinical features observed in this disease.

Influence of dexamethasone and weight loss on the regulation of serum leptin levels in obese individuals

The adipocyte hormone leptin is thought to serve as a signal to the central nervous system reflecting the status of fat stores. Serum leptin levels and adipocyte leptin messenger RNA levels are clearly increased in obesity. Nevertheless, the factors regulating leptin production are not fully understood. The aim of this study was to determine the effects of in vivo administration of the synthetic glucocorticoid dexamethasone and weight loss on serum leptin levels in two independent protocols. Twenty-five obese subjects were studied (18 women and 7 men, mean age 26.6 +/- 6 years, BMI 31.1 +/- 2.5 kg/m(2), %fat 40.3 +/- 8.3) and compared at baseline to 22 healthy individuals. Serum levels of leptin, insulin, proinsulin and glucose were assessed at baseline and after ingestion of dexamethasone, 4 mg per day (2 mg, twice daily) for two consecutive days. To study the effects of weight loss on serum leptin, 17 of the obese subjects were submitted to a low-calorie dietary intervention trial for 8 weeks and again blood samples were collected. Serum leptin levels were significantly higher in the obese group compared to the control group and a high positive correlation between leptinemia and the magnitude of fat mass was found (r = 0.88, P<0.0001). After dexamethasone, there was a significant increase in serum leptin levels (22.9 +/- 12.3 vs 51.4 +/- 23.3 ng/ml, P<0.05). Weight loss (86.1 +/- 15.1 vs 80.6 +/- 14.2 kg, P<0.05) led to a reduction in leptin levels (25.13 +/- 12.8 vs 15.9 +/- 9.1 ng/ml, P<0.05). We conclude that serum leptin levels are primordially dependent on fat mass magnitude. Glucocorticoids at supraphysiologic levels are potent secretagogues of leptin in obese subjects and a mild fat mass reduction leads to a disproportionate decrease in serum leptin levels. This suggests that, in addition to the changes in fat mass, complex nutritional and hormonal interactions may also play an important role in the regulation of leptin levels.

Antibodies to bovine serum albumin in Brazilian children and young adults with IDDM.

OBJECTIVE To evaluate the prevalence of IgG antibodies to bovine serum albumin (BSA) in a cohort of Brazilian children and young adults with IDDM. RESEARCH DESIGN AND METHODS Sera from 81 subjects with < 1 year of IDDM (group 1), III subjects with > 1 year of IDDM (group 2), and 207 normoglycemic subjects were tested using an immunofluorimetric assay. A receiver-operating-characteristic curve was used to establish the threshold of anti-BSA antibody titers defining the positivity of the assay. RESULTS The distribution of the fluorimetric index (FI) of anti-BSA antibodies did not have a gaussian profile. Rank sum of FI was significantly higher in patients than in control subjects (P < 0.0001). Average logFI values of both IDDM groups were significantly higher than that of the control group (P < 0.005 for both groups). There was a trend toward higher FI levels in group 1 than in group 2 (P = 0.06). A FI cutoff of 0.7 optimized the ratio of true-positive to false-positive of the assay, with the best equilibrium between sensitivity and specificity. The prevalence of anti-BSA antibodies was 52% in group 1, 47% in group 2, and 28% in the control group (P = 0.0001). An independent association between anti-BSA antibodies and IDDM, with an odds ratio of 3.03 (P < 0.0001), was observed in a logistic regression analysis. However anti-BSA antibodies explained only 5% of the variability of IDDM versus NIDDM. CONCLUSIONS Our results confirm that the prevalence of anti-BSA antibodies is higher in IDDM subjects than in control subjects, even after 1 year of diabetes. However, a large overlap of antibody titers is observed in patients and control subjects, suggesting that anti-BSA antibodies are neither sensitive nor specific markers of IDDM.

Prevalência dos marcadores imunológicos Anti-GAD e Anti-IA2 em parentes de primeiro grau de diabéticos do tipo 1 em amostra da população da Grande São Paulo

BACKGROUND: Increasingly accurate prediction of Type1 Diabetes Mellitus (DM1), based on analysis of autoantibody markers, has become possible in first-degree relatives of patients with diabetes (PDM1). These markers indicate autoimmune process against pancreatic islet beta-cells. Anti-GAD and anti-IA2 are considered predictive of DM1, whose prevalences are considerably variable in different populations studied. There are few data about the frequency of these markers on the Brazilian population. The aim of this study is determine the prevalence of positivity for anti-GAD and for anti-IA2 among DM1 patients first-degree relatives (PDM1) in a sample of the Brazilian population of Great Sao Paulo City. METHODS: Forty-eight children and adolescents PDM1 with median of age of 14.5 years (range 6.7 to 17.9 years). Anti-GAD and anti-IA2 was mesured by radioassay (Kronus®, USA). The cut-off limit for both antibodies was set at the 99th percentile from normal subjects serum samples (anti-GAD: n=194; Median of age=13.4 yrs; range 9.7 to 64 yrs; anti-IA2: n=71; Median of age= 12.6; range 11.1 - 15.2 yrs). A subject was considered to be positive for anti-IA2 if specific binding exceeded the 99th among the analysis of 71 subjects. The limit to positivity was 1.72 U/ml to anti-GAD and 0.97 U/ml to anti-IA2. RESULTS: Five PDM1(10.4%) have showed positivity to anti-GAD, with significantly higher prevalence than controls (P<0.01). The anti-IA2 prevalence rate seems to be equivalent between PDM1 and controls. CONCLUSION: The prevalence of anti-GAD has been more prevalent among the PDM1. No differences were observed between prevalences for anti-IA2 showed by PDM1 and controls.BACKGROUND Increasingly accurate prediction of Type I Diabetes Mellitus (DMI), based on analysis of autoantibody markers, has become possible in first-degree relatives of patients with diabetes (PDMI). These markers indicate autoimmune process against pancreatic islet beta-cells. Anti-GAD and anti-IA2 are considered predictive of DMI, whose prevalences are considerably variable in different populations studied. There are few data about the frequency of these markers on the Brazilian population. The aim of this study is determine the prevalence of positivity for anti-GAD and for anti-IA2 among DMI patients first-degree relatives (PDMI) in a sample of the Brazilian population of Great São Paulo City. METHODS Forty-eight children and adolescents PDMI with median of age of 14.5 years (range 6.7 to 17.9 years). Anti-GAD and anti-IA2 was measured by radioassay (Kronus , USA). The cut-off limit for both antibodies was set at the 99th percentile from normal subjects serum samples (anti-GAD: n=194; Median of age=13.4 yrs; range 9.7 to 64 yrs; anti-IA2: n=71; Median of age=12.6; range 11.1-15.2 yrs). A subject was considered to be positive for anti-IA2 if specific binding exceeded the 99th among the analysis of 71 subjects. The limit to positivity was 1.72 U/ml to anti-GAD and 0.97 U/ml to anti-IA2. RESULTS Five PDMI (10.4%) have showed positivity to anti-GAD, with significantly higher prevalence than controls (P<0.01). The anti-IA2 prevalence rate seems to be equivalent between PDMI and controls. CONCLUSION The prevalence of anti-GAD has been more prevalent among the PDMI. No differences were observed between prevalences for anti-IA2 showed by PDMI and controls.

Low levels of sex hormone-binding globulin and hyperproinsulinemia as markers of increased pancreatic Beta-cell demand in men

Low levels of sex hormone-binding globulin (SHBG) are considered to be an indirect index of hyperinsulinemia, predicting the later onset of diabetes mellitus type 2. In the insulin resistance state and in the presence of an increased pancreatic beta-cell demand (e.g. obesity) both absolute and relative increases in proinsulin secretion occur. In the present study we investigated the correlation between SHBG and pancreatic beta-cell secretion in men with different body compositions. Eighteen young men (30.0 +/- 2.4 years) with normal glucose tolerance and body mass indexes (BMI) ranging from 22.6 to 43.2 kg/m2 were submitted to an oral glucose tolerance test (75 g) and baseline and 120-min blood samples were used to determine insulin, proinsulin and C-peptide by specific immunoassays. Baseline SHBG values were significantly correlated with baseline insulin (r = -0.58, P < 0.05), proinsulin (r = -0.47, P < 0.05), C-peptide (r = -0.55, P < 0.05) and also with proinsulin at 120 min after glucose load (r = -0.58, P < 0.05). Stepwise regression analysis revealed that proinsulin values at 120 min were the strongest predictor of SHBG (r = -0.58, P < 0.05). When subjects were divided into obese (BMI > 28 kg/m2, N = 8) and nonobese (BMI < or = 25 kg/m2, N = 10) groups, significantly lower levels of SHBG were found in the obese subjects. The obese group had significantly higher baseline proinsulin, C-peptide and 120-min proinsulin and insulin levels. For the first time using a specific assay for insulin determination, a strong inverse correlation between insulinemia and SHBG levels was confirmed. The finding of a strong negative correlation between SHBG levels and pancreatic beta-cell secretion, mainly for the 120-min post-glucose load proinsulin levels, reinforces the concept that low SHBG levels are a suitable marker of increased pancreatic beta-cell demand.

Influence of the Presence of Islet -Cell Antibodies (Ica) and Insulin Auto Antibodies (Iaa) Over the Metabolic Control of Type I Diabetic Patients

Many factors exert influence in obtaining a good metabolic control in patients with Type I diabetes (DMI). Objective-a) To evaluate the influence of the presence of ICA at diagnosis in C-peptide secretion during the first year of follow-up. b) To study the realtionship between IA and insulin dose and type. We analysed 14 patients, diagnosed within 6 weeks, with chronological age=9.8y (2.3-22y). 9F and 5 M, in a double-blind, prospective study. ICA were detected by imunoperoxidase technique (A-protein/peroxidase in rat pancreas), limit of sensibility = 101DFU.1A dosage- RIA (NV <60nU/mL). We analysed HbA1 levels (affinity cromatography- nv=3.6-5.3%), and C-peptide(RIE-kit DPC) basal and after stimulation with Sustacal, before NCT introduction and each three months during the first year. Insulin dose was also assessed (units per kilo - U/Kg). Patients with ICA negative (n=5); ICA positive (n=9). Values of C-peptide (CP) in relation to ICA:Table

Effects of Nicotinamide (Nct) in Insulin Secretion in Patients With Type I Diabetes Mellitus (Dmi)

Its known that at diagnosis of DMI there is still some reserve of pancreatic B-cells. and that its preservation is important to reduce the chronic complications of the disease. Objective- Evaluate nicotinamide action upon insulin secretion in recent-onset DML We analysed 14 patients, diagnosed within 6 weeks, with chronological age=9 Sv (2.3-2.2v). 9F and 5 M. in a double-blind prospective study. They were divided in 2 groups to receive NCT. 40 mg kg/d. (Group 1) or Placebo (Group 2). We analysed HbA1 levels ([Illegible Text] cromatography - nv=3.6-5.3″,)and C-peptide months (RIE-kit DPC) basai and after stimulation with Sustacal, before NCT introdution and each three months during the first year. Insulin dose was also assessed (units per kilo - U/Kg). Results. -C-petide. HbA1 and U/kg evolution during the first year after diagnosis: Table