Polymorphic markers of the NO synthase genes and genetic predisposition to diabetic polyneuropathy in type 1 diabetes mellitus

The allele and genotype frequency distributions of polymorphic markers of the NOS1, NOS2, and NOS3 genes coding for three different NO synthases were compared for type 1 diabetes mellitus (T1DM) patients with or without diabetic polyneuropathy (DPN). The groups (total 180 patients, ethnic Russians or East Slavs from Moscow) had nonoverlapping (polar) phenotypes. Group DPN+ included patients with DPN and T1DM duration of no more than 5 years. Control group DPN- included patients without DPN and with T1DM duration of at least 10 years. No significant differences in allele and genotype frequency distributions were revealed for the polymorphic markers (CA) _n of gene NOS1 (CCTTT) _n of gene NOS2, and ecNOS4a/4b and Glu298Asp of gene NOS3, suggesting a lack of association between the polymorphic markers and DPN. In the case of the (CCTTT) _n polymorphic marker of the NOS2 gene, a tendency toward an association with DPN was observed for allele 14. Carriers of this allele have a lower risk of DPN in T1DM.__________Translated from Molekulyarnaya Biologiya, Vol. 39, No. 2, 2005, pp. 224–229.Original Russian Text Copyright © 2005 by Zotova, Voronko, Bursa, Galeev, Strokov, Nosikov.     

Involvement of cellular calcium in exocrine pancreatic insufficiency during streptozotocin-induced diabetes mellitus

This study investigates the effects of the islet hormones insulin (Ins), glucagon (Glu), and somatostatin (Som) with nerve stimulation (EFS) acetylcholine (ACh) and cholecytokinin-octapeptide (CCK-8) on amylase secretion and intracellular free calcium concentration [Ca(2+)](i) in the pancreas of age-matched control and diabetic rats. Either Ins, Glu or Som elicited small increases in amylase secretion from the pancreas of age-matched control animals compared to a much larger increase in amylase secretion with either EFS, ACh or CCK-8. Combining the islet hormones with either EFS, ACh or CCK-8 resulted in marked potentiation of amylase output. In the diabetic pancreas, the islet hormones had no effect on amylase secretion compared to diabetic control. Moreover, either EFS, ACh or CCK-8 evoked a much smaller increase in amylase output compared to age-matched control. In addition, the islet hormones failed to potentiate the secretory effects of either EFS, ACh or CCK-8. In fura-2 loaded acinar cells from age-matched control pancreas either Ins or Glu elicited a small increase in [Ca(2+)](i) whereas Som had no effect. Both ACh and CCK-8 evoked large increases in [Ca(2+)](i) compared to control. Combining either Ins, Glu or Som with either ACh or CCK-8 resulted in a marked elevation in [Ca(2+)](i) compared to the responses obtained with either the islet hormones, ACh or CCK-8 alone. In diabetic fura-2 loaded pancreatic acinar cells, the islet hormones had no effect on [Ca(2+)](i) compared to control and moreover, the responses were much smaller than those obtained in acinar cells from age-matched control. Both ACh and CCK-8 induced large increases in [Ca(2+)]( i) in diabetic acinar cells. However, combining the islet hormones with either ACh or CCK-8 failed to enhance [Ca(2+)](i) compared to the reponses obtained in acinar cells from age-matched control. The results suggests that [Ca(2+)](i) homeostasis is deranged during diabetes mellitus and this in turn is probably associated with reduced pancreatic amylase secretion.     

Polymorphic markers of the NO synthase genes and genetic predisposition to diabetic polyneuropathy in patients with type 1 diabetes mellitus

The allele and genotype frequencies of polymorphic markers of NOS1, NOS2 and NOS3 genes, encoding three types of NO synthases, were compared in type 1 diabetes patients with and without diabetic polyneuropathty. 180 type 1 diabetes patients (T1DM) of Russian or Eastern Slavonic origin, living in Moscow city, were divided into two groups using non-overlapping (polar) phenotypes. 86 patients had overt DPN and T1DM duration in this group was less than 5 years (DPN+ group) and 94 patients had no clinical DPN and T1DM duration was more than 10 years (DPN- group). We have not found the significant differences of allele and genotype frequencies of polymorphic markers (CA)n of NOS1 gene, (CCTTT)n of NOS2 gene, ecNOS4a/4b and Glu298Asp of NOS3 gene that indicates that all these markers are not associated with diabetic polyneuropathty. Only in the case of (CCTTT)n marker of NOS2 gene we have found a tendency for the association of 14 allele with DPN development. The carriers of this allele have the lower risk of DPN in T1DM.     

The use of SNP markers for estimation of individual genetic predisposition to diabetes mellitus type 1 and 2

Single nucleotide polymorphisms (SNPs) are now considered as the most perspective and convenient markers for studies of genetic basis of multifactorial diseases. Fast development of technologies for exact screening of a large volume of genetic information and construction of genomic maps of SNP-markers promote the development of innovative diagnostic systems on the basis of significant SNP for an estimation of individual genetic risk of development of various diseases. This review considers the basic aspects of genetics of diabetes mellitus type 1 and 2 and an opportunity to use SNP as markers for the estimation of individual genetic predisposition to this disease.     

Appearance and metabolic development of diabetes mellitus in the sand rat, Psammomys obesus

The aim of this study was to examine the long-term effects of synthetic chow diet on the metabolic pattern of diabetic syndrome in a large group of sand rats. Few animals had a fulminating reaction with markedly decreased glucose tolerance, low plasma insulin levels and death within 3-4 weeks. But the most of sand rats developed obesity and elevated plasma insulin levels. From the third month, 40% of sand rats presented a diabetic syndrome with hyperinsulinemia, hyperglycemia, markedly decreased glucose tolerance and insulin resistance. Plasma lipids were increased; the lipid and glycogen accumulation in the liver was high. So this diabetic syndrome can be compared to maturity onset diabetes. If this synthetic chow diet lasted more than 6 months, the most of animals lost considerable weight with a strong lipid depletion of fat stores. Serum immunoreactive insulin levels fall and the blood glucose rose over 500 mg/100 ml with glycosuria and ketonuria . The elevated triglyceride content of plasma and the lipid deposits in the liver were exaggerated; glycogen had disappeared. Animals developed an overtly insulin- dependent diabetes, the latter phase of the disease. The sand rat appears to us as a potentially interesting model for investigation both maturity onset and ketotic-type diabetic syndrome.     

The challenge of type 1 diabetes mellitus

Diabetes mellitus is a heterogeneous group of diseases characterized by high blood glucose levels due to defects in insulin secretion, insulin action, or both. With the number of cases expected to increase rapidly in the years to come, diabetes is a growing health challenge worldwide. Of the approximately 16 million diabetics in the United States, about 1.5 million suffer from type 1 diabetes. In this catabolic disorder afflicting predominantly young individuals, blood insulin is almost completely absent, leading to hyperglycemia and alterations in lipid metabolism. Type 1 diabetes is thought to be induced by a toxic or infectious insult that occurs in genetically predisposed individuals. With recent advances in the understanding of the involved immunology and cellular and molecular mechanisms, researchers strive to battle the disease with new preventive and corrective strategies.     

Development and characterization of a novel rat model of type 2 diabetes mellitus: the UC Davis type 2 diabetes mellitus UCD-T2DM rat

The prevalence of type 2 diabetes (T2DM) is increasing, creating a need for T2DM animal models for the study of disease pathogenesis, prevention, and treatment. The purpose of this project was to develop a rat model of T2DM that more closely models the pathophysiology of T2DM in humans. The model was created by crossing obese Sprague-Dawley rats with insulin resistance resulting from polygenic adult-onset obesity with Zucker diabetic fatty-lean rats that have a defect in pancreatic beta-cell function but normal leptin signaling. We have characterized the model with respect to diabetes incidence; age of onset; longitudinal measurements of glucose, insulin, and lipids; and glucose tolerance. Longitudinal fasting glucose and insulin data demonstrated progressive hyperglycemia (with fasting and fed glucose concentrations >250 and >450 mg/dl, respectively) after onset along with hyperinsulinemia resulting from insulin resistance at onset followed by a progressive decline in circulating insulin concentrations, indicative of beta-cell decompensation. The incidence of diabetes in male and female rats was 92 and 43%, respectively, with an average age of onset of 6 mo in males and 9.5 mo in females. Results from intravenous glucose tolerance tests, pancreas immunohistochemistry, and islet insulin content further support a role for beta-cell dysfunction in the pathophysiology of T2DM in this model. Diabetic animals also exhibit glycosuria, polyuria, and hyperphagia. Thus diabetes in the UC Davis-T2DM rat is more similar to clinical T2DM in humans than in other existing rat models and provides a useful model for future studies of the pathophysiology, treatment, and prevention of T2DM.     

Growth and body composition in type 1 diabetes mellitus

Over the last 50 years the prognosis for growth and pubertal development in children with type 1 diabetes mellitus (T1DM) has improved considerably. The early reports of Mauriac's syndrome were related not only to relative deficiency of insulin but also reduced caloric intake. Improved insulin delivery and liberalisation of caloric intake has resulted in improved growth, but subtle abnormalities persist. The frequently reported increased height at diagnosis may relate to prior hyperinsulinaemia and genetic background with respect to lDDM2 the insulin gene VNTR. Subsequent growth faltering is thought to be related to impairment of the GH/IGF-1 axis but children with T1DM are also more at risk of hypothyroidism and coeliac disease. At puberty, persisting abnormalities of the GH/IGF-1 axis and our inability to reverse these totally, even with intensified insulin therapy, contribute to the blunted pubertal growth in the girls but abnormal sex steroid concentrations may also be important. Intensification of insulin therapy may result in leptin resistance and excessive gains in fat mass, particularly in girls. Although it is likely that most children with T1DM will have normal final heights, this excessive weight gain in girls may lead to problems with compliance. Furthermore, hyperinsulinaemia in these subjects may also lead to ovarian hyperandrogenism, increased early risk of microvascular complications and long-term risk of cardiovascular disease.     

Exercise,free radicals,and lipid peroxidation in type 1 diabetes mellitus

Indirect biochemical techniques have solely been used to ascertain whether type 1 diabetes mellitus patients are more susceptible to resting and exercise-induced oxidative stress. To date there is no direct evidence to support the contention that type 1 diabetic patients have increased levels of free radical species. Thus, the aim of this study was to use electron spin resonance (ESR) spectroscopy in conjunction with alpha-phenyl-tert-butylnitrone (PBN) spin trapping to measure pre- and postexercise free radical concentration in the venous blood of young male patients with type 1 diabetes mellitus (HbA(1c) = 8.2 +/- 1%, n = 12) and healthy matched controls (HbA(1c) = 5.5 +/- 0.2%, n = 13). Supporting measures of lipid peroxidation (malondialdehyde and lipid hydroperoxides), ambient blood glucose and selected antioxidants were also measured. The diabetic patients presented with a comparatively greater concentration of free radicals as measured by ESR and lipid hydroperoxides (LH) compared to the healthy group (p <.05, pooled rest and exercise data), although there was no difference in malondialdehyde (MDA) concentration. alpha-Tocopherol was comparatively lower in the healthy group (p <.05, pooled rest and exercise data vs. diabetic group) due to a selective decrease during physical exercise (p <.05 vs. rest). The hyperfine coupling constants recorded from the ESR spectra (a(Nitrogen) = 1.37 mT and abeta(Hydrogen) = 0.17 mT) are suggestive of either oxygen or carbon-centered species and are consistent with literature values. We suggest that the greater concentration of oxidants seen in the diabetic group may be due to increased glucose autoxidation as a function of this pathology and/or a lower exercise-induced oxidation rate of the major lipid soluble antioxidant alpha-tocopherol. We suggest that the ESR-detected radicals are secondary species derived from decomposition of LH because these are the major initial reaction products of free radical attack on cell membranes.     

Genetic analysis of the structure of the predisposition to diabetes mellitus. II. The prevalence, morbidity and heritability of diabetes mellitus

Prevalence of diabetes mellitus (D.M.) was estimated in several Moscow districts. The prevalence increases with the age from 0.073 in males and 0.085% in females at the age of 16-19 yrs to 4.9 in males and 6.2% in females at the age of 75 yrs and older. The overall prevalence of D.M. was 1.12%. The morbidity risks have the same patterns of increase: from 0.007 and 0.008% at the age of 0-4 yrs to 1.6 and 2.7% at the age of 75 yrs and older in males and females, respectively. The values of "cumulative" morbidity risk, for the population living long enough, derived from the estimates of age-specific morbidity risks were 6.57 for males and 11.93% for females. The estimate of correlation between first-degree relatives at onset-age of D.M. was 0.307. Accounted for the age-at-onset of the probands and for current ages of siblings, the estimates of recurrence risks, i.e. the probability to develop D.M. for siblings living long enough, were: 27.28 for sisters of the male-probands, 21.59 for sisters of the female-probands, 19.28 for brothers of male-probands and 9.62% for brothers of the female-probands. Thus, the family distribution of D.M., according to the sex of the probands and that of their relatives corresponds to the multifactorial model of inheritance for the diseases with sex-specific thresholds. The estimates of correlation in liability and that of heritability of D.M. calculated from the data on sibs, were 0.284 +/- 0.0351 and 0.568 +/- 0.0702, respectively. The data obtained show that hereditary factors play an essential role in the development of D.M. These results are of a practical interest for genetic counselling, as well as for establishing the preventive measures in the Public Health Service.     

Genetic and immunologic aspects of type 1 diabetes mellitus

Prediction of type 1 diabetes mellitus (IDDM) and its identification in preclinical period is one of the central problems in modern medicine. They are based comprehensive genetic, immunologic and metabolic evaluations. We observed four hundred seven first-degree relatives of patients with IDDM (240 families in which one of the children or one of the parents had IDDM) have been included in the study. The study of HLA-DQA1, HLA-DQB1 polymorphic alleles and DRB1 genes and their combinations. The genetic study included searching HLA loci (HLA-DQA1, HLA-DQB1 polymorphic alleles and DRB1 genes) loci. To evaluate the genetic risk two approaches we used: first--carrying predisposing HLA-DQ alleles and DRB1-genes and it's combination (mainly associated in Russian population was DRB1*04-DQB1*0302, DRB1*04-DQA1*0301, DQA1*0301-DQB1*0302, DQA1*0301-DQB1*0302 and four susceptible alleles in A- and B- chains (Asp 57-, Arg 52+)) and second--IBD (identity by descent), in Russian population HLA-identical for 2 haplotypes sibs had risk of development of IDDM of 18%, for 1 haplotype--3%, for 0 haplotype-0.9%. The antibodies (ICA, IAA) prevalence rate has not depended on availability of predisposing HLA-DQ alleles and DRB1-genes and haploidentity of normal sibs and sibs with IDDM. However, GADA prevalence rate in groups having high predisposed alleles has been noticed as significantly higher (28.6%) comparing with 7.7% in groups that had no predisposing alleles (p < 0.05). The comparison of antibodies prevalence rate to sibs HLA-identity has shown the significant increase or GADA prevalence rate in group of siblings identical for one haplotype comparing with non-identical sibs (27.3% and 0% respectively, p < 0.001).     

Anti-GAD-positive patients with type 1 diabetes mellitus have higher prevalence of autoimmune thyroiditis than anti-GAD-negative patients with type 1 and type 2 diabetes mellitus

The aim of our study was to evaluate antibodies against thyroglobulin (anti-TG) and thyroid peroxidase (anti-TPO) - markers of autoimmune thyroiditis - in several groups of adult patients with type 1 and type 2 diabetes mellitus (DM). We were particularly interested whether the presence of thyroid antibodies is related to the positivity of glutamic acid decarboxylase antibodies (anti-GAD). We found elevated anti-GAD in 46 % (97/210) patients with type 1 DM. All patients with type 2 diabetes were anti-GAD-negative. At least one thyroid antibody (anti-TG and/or anti-TPO) was found in 30 % (62/210) patients with type 1 DM and 27 % (22/83) type 2 diabetes patients. The patients with type 1 DM were further grouped according to their anti-GAD status. The anti-GAD-positive patients had a higher prevalence of anti-TG antibodies than the anti-GAD-negative patients (25 % vs. 12 %, p=0.03) as well as anti-TPO antibodies (32 % vs. 12 %, p<0.001). At least one thyroid antibody was detected in 39 % (38/97) of anti-GAD-positive but only in 21 % (24/113) of anti-GAD-negative patients with type 1 DM (p=0.006). No significant difference in the frequency of thyroid antibodies was found between anti-GAD-negative patients with type 1 and type 2 DM (21 % vs. 27 %, p=0.4). The groups with or without thyroid antibodies in both type 1 and type 2 diabetic patients did not differ in actual age, the age at diabetes onset, duration of diabetes, body mass index or HbA1c level. Patients with elevated thyroid antibodies had significantly higher levels of TSH than those without thyroid antibodies (1.86 vs. 3.22 mIU/l, p=0.04 in type 1 DM; 2.06 vs. 4.89 mIU/l, p=0.003 in type 2 DM). We conclude that there is a higher frequency of thyroid-specific antibodies in anti-GAD-positive adult patients with type 1 DM than in anti-GAD-negative patients or in patients with type 2 DM. Patients with or without thyroid antibodies do not differ in age, DM onset and duration, BMI or HbA1c. Thyroid antibodies-positive patients have higher levels of thyroid stimulating hormone (TSH).