Apoptosis and oxidative status in peripheral blood mononuclear cells of diabetic patients

We have compared the concentrations of intracellular glutathione (GSH), glutathione-dependent antioxidative enzymes, the cell death rate and immunophenotype profile of peripheral blood mononuclear cells (PBMC) from healthy donors and from patients with insulin-dependent type I (IDDM) or non insulin-dependent type II (NIDDM) diabetes mellitus. The IDDM and NIDDM patients had above-normal absolute lymphocyte counts, whereas the percentages of CD3, CD4 and CD8 T lymphocytes were significantly reduced. In contrast, the absolute number and percentage of B lymphocytes was higher in diabetic patients than in healthy donors. The low intracellular reduced glutathione (GSH) and the unbalanced profile of key enzymes involved in GSH metabolism, gamma glutamyltransferase (-GT) and glutathione-S-transferase (GST), account for the increased oxidative status of PBMC from diabetic patients. The plasma membranes of PBMC from diabetic patients were less permeable to propidium iodide than those of PBMC from healthy donors, indicating that the apoptotic cell death rate was lower in the cells from diabetic patients. These differences are potentially useful markers of pathogenic metabolic changes which occur during clinical diabetes and if they are confirmed could be used to identify the onset of diabetes.     

T cell autoreactivity to insulin in diabetic and related non-diabetic individuals

T cell autoreactivity to insulin in type I diabetic and related non-diabetic individuals was analyzed. Peripheral T lymphocytes from both insulin-treated diabetic and untreated non-diabetic members of four families were found to proliferate in vitro in response to human insulin. T cell autoreactivity to insulin therefore does not appear to be diagnostic of the onset of type I diabetes. Highest T cell responses to human insulin were usually detected in insulin-dependent type I diabetes patients treated with a mixture of beef and pork insulin than with self insulin, the greater the dose of animal insulin the higher the T cell response. The T cell repertoires for self insulin appear to be similar in diabetics and non-diabetics based on their patterns of T cell reactivity to beef insulin, port insulin, human insulin, and various peptide of human insulin. The autoreactive T cells analyzed recognize two conformational epitopes of human insulin formed by interactions between A chain and B chain residues. One epitope is associated with the A chain loop and is present in the A1-A14/B1-B16 peptide, and the other epitope consists mainly of B chain residues located in the A16-A21/B10-B25 peptide. These two epitopes are present in amphipathic alpha-helical regions of insulin. HLA-DR (DR3, DR4, and DR5) and HLA-DQ (DQw2/DQw3) Ag can restrict these T cell responses to human insulin epitopes. The ability to detect insulin-specific autoreactive T cells in healthy non-diabetic individuals supports the hypothesis that autoreactive lymphocytes do not necessarily elicit autoimmune disease if present in an environment in which their activity is immunoregulated.     

In vivo expression of perforin by CD8+ lymphocytes in autoimmune disease. Studies on spontaneous and adoptively transferred diabetes in nonobese diabetic mice

A potent cytolytic pore-forming protein (perforin or cytolysin) has previously been found to be associated with the cytoplasmic granules of CTL and NK cells. Inasmuch as all previous studies on perforin have been conducted with cultured CTL and NK cell lines, it is not clear whether perforin may play a role in the cytotoxicity mediated by CTL that have been primed in vivo. In this study, we investigated the presence of perforin in pancreata from nonobese diabetic (NOD) mice, which have been studied as a model of autoimmune, insulin-dependent (type I) diabetes mellitus. Whereas adult NOD mice spontaneously develop diabetes, it is possible to induce diabetes in young, irradiated NOD mice by adoptive transfer of splenocytes obtained from diabetic donors. By means of immunohistochemical analysis, we were able to detect perforin Ag in a small subpopulation of CD8+/Thy-1+/asialo GM1-/CD4- lymphocytes in the pancreatic islets of animals undergoing both spontaneous and adoptive transfer-mediated insulitis. Perforin+/CD8+ lymphocytes were found in small clusters and were observed to display the morphology of large granular lymphocytes. These observations show for the first time the presence of perforin-containing CD8+ lymphocytes in tissues of animals undergoing autoimmune disease.     

Effect of prolonged exercise and carbohydrate ingestion on type 1 and type 2 T lymphocyte distribution and intracellular cytokine production in humans.

The present study was undertaken to examine the role of the exercise-induced stress hormone response on the regulation of type 1 and type 2 T lymphocyte intracellular cytokine production. Subjects performed 2.5 h of cycling exercise at 65% maximal O2 uptake while ingesting a 6.4% carbohydrate (CHO) solution, 12.8% CHO solution, or a placebo. Peripheral whole blood samples were stimulated and stained for T lymphocyte surface antigens (CD4 and CD8). Cells were then permeabilized, stained for intracellular cytokines, and analyzed using flow cytometry. Exercise resulted in a decrease (P < 0.05) in the number and percentage of IFN-gamma positive CD4+ and CD8+ T lymphocytes. These stimulated cells produced less IFN-gamma immediately postexercise (P < 0.05) and 2-h postexercise (P < 0.05) compared with preexercise. However, CHO ingestion, which attenuated the exercise-induced stress hormone response compared with placebo (P < 0.05), prevented both the decrease in the number and percentage of IFN-gamma-positive CD4+ and CD8+ T lymphocytes and the suppression of IFN-gamma production from stimulated CD4+ and CD8+ T lymphocytes. There was no effect of exercise on the number of, or cytokine production from, IL-4-positive CD4+ or CD8+ T lymphocytes. These data provide support for the role of exercise-induced elevations in stress hormones in the regulation of type 1 T lymphocyte cytokine production and distribution.     

GALNT2 Expression Is Reduced in Patients with Type 2 Diabetes: Possible Role of Hyperglycemia

Impaired insulin action plays a major role in the pathogenesis of type 2 diabetes, a chronic metabolic disorder which imposes a tremendous burden to morbidity and mortality worldwide. Unraveling the molecular mechanisms underlying insulin resistance would improve setting up preventive and treatment strategies of type 2 diabetes. Down-regulation of GALNT2, an UDPN-acetyl-alpha-D-galactosamine polypeptideN-acetylgalactosaminyltransferase-2 (ppGalNAc-T2), causes impaired insulin signaling and action in cultured human liver cells. In addition, GALNT2 mRNA levels are down-regulated in liver of spontaneously insulin resistant, diabetic Goto-Kakizaki rats. To investigate the role of GALNT2 in human hyperglycemia, we measured GALNT2 mRNA expression levels in peripheral whole blood cells of 84 non-obese and 46 obese non-diabetic individuals as well as of 98 obese patients with type 2 diabetes. We also measured GALNT2 mRNA expression in human U937 cells cultured under different glucose concentrations. In vivo studies indicated that GALNT2 mRNA levels were significantly reduced from non obese control to obese non diabetic and to obese diabetic individuals (p<0.001). In vitro studies showed that GALNT2 mRNA levels was reduced in U937 cells exposed to high glucose concentrations (i.e. 25 mmol/l glucose) as compared to cells exposed to low glucose concentration (i.e. 5.5 mmol/l glucose +19.5 mmol/l mannitol). In conclusion, our data indicate that GALNT2 is down-regulated in patients with type 2 diabetes and suggest that this association is, at least partly, secondary to hyperglycemia. Further studies are needed to understand whether GALNT2 down-regulation plays a pathogenic role in maintaining and/or aggravating the metabolic abnormalities of diabetic milieu.     

The responses of lymphocytes from Asian and Caucasian diabetic patients and non-diabetics to hydrogen peroxide and sodium nitrite in the Comet assay

Numerous factors may influence the incidence of diabetes in the population. The production of reactive oxygen species (ROS) is elevated in diabetes patients. Based on the reported involvement of reactive species and nitrate/nitrite in diabetes, this present study has examined in the alkaline Comet assay, the effect of different levels of NaNO(2) in the presence of the oxygen radical generating agent, hydrogen peroxide (H(2)O(2)). Peripheral lymphocytes from diabetic and non-diabetic Caucasians and Asians of both sexes were studied in vitro. Endogenous factors (e.g., sex, age, body mass index-BMI) and exogenous factors (lifestyle factors e.g., smoking and drinking habits, diet) were taken into account. A preliminary study in two individuals showed that DNA damage remained constant over a wide dose range of NaNO(2) (1-75mM), but when H(2)O(2) was added at a constant concentration of 50microM per dose of NaNO(2), there was an increase in DNA damage corresponding with the varying levels of NaNO(2) investigated. This was also seen with the 44 individuals (non-diabetic, n=24; type 1 diabetic, n=11; type 2 diabetic, n=9) investigated. NaNO(2) was capable of inducing a significant level of DNA damage in lymphocytes (p<0.001), but only with the addition of H(2)O(2). When levels of DNA damage were analysed in terms of the different variables there were few significant differences in damage between diabetic and non-diabetic subjects, or other sub-population groups, and no statistically significant differences in susceptibility were observed between subject covariates using regression techniques.     

Double transgenic mice with type 1 diabetes mellitus develop somatic, metabolic and vascular disorders

The double transgenic mice (dTg) were obtained by mating: (i) transgenic mice expressing the hemagglutinin of influenza virus under the insulin promoter with (ii) transgenic mice expressing specific T lymphocytes with receptor for the immunodominant epitope of the same virus. In this study we show that dTg mice developed type 1 diabetes mellitus associated with hyperglycemia, low level of plasma insulin, glucosuria, weight loss and approximately 90% mortality (at 3 months biological age). The membrane of red blood cells was more sensitive to osmotic shock in diabetic mice, compared to non-diabetic mice, assessing systemic oxidative stress. Both vasoconstriction and vasorelaxation of the renal arteries decreased significantly in diabetic mice (compared to the control group of non-diabetic mice) related to the phenotypic change of endothelium and smooth muscle cells within the artery wall. This animal model, may be used in developing various strategies to study pancreatic beta-cell function, as well as for a better metabolic control conducting to a reduced risk of vascular complications.     

An early but intense cytokine production within the islets may be predictive for type 1 diabetes occurrence in the Bio Breeding (BB) rat

The Bio Breeding (BB) rat is a useful animal model of type 1 autoimmune diabetes. The aim of this study was to observe and follow the cytokine and antigenic expressions within the islets of Langerhans in young non-diabetic, in pre-diabetic hyperglycemic, and in overtly diabetic animals. BB rats were therefore checked at day 21 up to day 90 of life for blood glucose, insulin levels, degree of islet infiltration, expression of proinflammatory and protective cytokines and antibodies including CD4, CD8, CD25, LFA-1, and ICAM-1. Animals were treated with insulin as they became diabetic. We found that islets of non-diabetic BB rats became positive to both IL-1beta and IL-4 very early on, confirming a local but intense production of both cytokines within the islets during the initial non-diabetic period. In addition, we observed that the production of these interleukins together with the expression levels of CD4 and CD25 are events predictive for type 1 diabetes onset in non-diabetic BB rats, as for non-obese diabetic (NOD) mice. In particular, the production of IL-1beta and IL-4 during the non-diabetic period together with the lack of enhancement of CD4 and CD25, indicating selective recruitment of activated T cells, may explain the failure of anti-diabetic treatments in this animal model of type 1 diabetes.     

Rotavirus Activates Lymphocytes from Non-Obese Diabetic Mice by Triggering Toll-Like Receptor 7 Signaling and Interferon Production in Plasmacytoid Dendritic Cells

It has been proposed that rotavirus infection promotes the progression of genetically-predisposed children to type 1 diabetes, a chronic autoimmune disease marked by infiltration of activated lymphocytes into pancreatic islets. Non-obese diabetic (NOD) mice provide a model for the human disease. Infection of adult NOD mice with rhesus monkey rotavirus (RRV) accelerates diabetes onset, without evidence of pancreatic infection. Rather, RRV spreads to the pancreatic and mesenteric lymph nodes where its association with antigen-presenting cells, including dendritic cells, induces cellular maturation. RRV infection increases levels of the class I major histocompatibility complex on B cells and proinflammatory cytokine expression by T cells at these sites. In autoimmunity-resistant mice and human mononuclear cells from blood, rotavirus-exposed plasmacytoid dendritic cells contribute to bystander polyclonal B cell activation through type I interferon expression. Here we tested the hypothesis that rotavirus induces bystander activation of lymphocytes from NOD mice by provoking dendritic cell activation and proinflammatory cytokine secretion. NOD mouse splenocytes were stimulated with rotavirus and assessed for activation by flow cytometry. This stimulation activated antigen-presenting cells and B cells independently of virus strain and replicative ability. Instead, activation depended on virus dose and was prevented by blockade of virus decapsidation, inhibition of endosomal acidification and interference with signaling through Toll-like receptor 7 and the type I interferon receptor. Plasmacytoid dendritic cells were more efficiently activated than conventional dendritic cells by RRV, and contributed to the activation of B and T cells, including islet-autoreactive CD8⁺ T cells. Thus, a double-stranded RNA virus can induce Toll-like receptor 7 signaling, resulting in lymphocyte activation. Our findings suggest that bystander activation mediated by type I interferon contributes to the lymphocyte activation observed following RRV infection of NOD mice, and may play a role in diabetes acceleration by rotavirus.     

Advances in the cellular immunological pathogenesis of type 1 diabetes

Type 1 diabetes is an autoimmune disease caused by the immune‐mediated destruction of insulin‐producing pancreatic β cells. In recent years, the incidence of type 1 diabetes continues to increase. It is supposed that genetic, environmental and immune factors participate in the damage of pancreatic β cells. Both the immune regulation and the immune response are involved in the pathogenesis of type 1 diabetes, in which cellular immunity plays a significant role. For the infiltration of CD4⁺ and CD8⁺ T lymphocyte, B lymphocytes, natural killer cells, dendritic cells and other immune cells take part in the damage of pancreatic β cells, which ultimately lead to type 1 diabetes. This review outlines the cellular immunological mechanism of type 1 diabetes, with a particular emphasis to T lymphocyte and natural killer cells, and provides the effective immune therapy in T1D, which is approached at three stages. However, future studies will be directed at searching for an effective, safe and long‐lasting strategy to enhance the regulation of a diabetogenic immune system with limited toxicity and without global immunosuppression.     

Time course of NADH oxidase, inducible nitric oxide synthase and peroxynitrite in diabetic retinopathy in the BBZ/WOR rat.

This study investigated the time course of NADH oxidase, a source of superoxide in the vascular endothelium, inducible nitric oxide synthase (iNOS), and peroxynitrite (ONOO(-)) in the BBZ/Wor rat, a spontaneous model of noninsulin dependent diabetes (NIDDM). Colloidal gold-labeled immunocytochemical studies of iNOS and nitrotyrosine, a marker for OONO(-), were done on sections of retinas from male BBZ/Wor rats in which NADH oxidase was localized by cerium derived cytochemistry at three time points: pre-diabetes (prior to the onset of hyperglycemia); new onset diabetes (2-6 days after onset of hyperglycemia); and chronic diabetes (4-18 months after onset of hyperglycemia). Control retinas were from age matched non-diabetic BB(DR)/Wor rats. The percentage of blood vessels positive for NADH oxidase increased significantly (P = 0.05) in new onset (64.2 +/- 6.5%) and chronic diabetes (83.2 +/- 11.4%), as compared to pre-diabetes (25.8 +/- 5.6%) and nondiabetic controls (33.6 +/- 15.9%). The percentage of blood vessels positive for iNOS immunoreactivity was significantly higher in new onset diabetic retinas (69.6 +/- 5.88%, P = 0.0001; 8.9 +/- 3.29 colloidal gold particles (cgp) /50 microm(2)) than in chronic diabetic retinas (49.9 +/- 9.75%; 7.9 +/- 5.12 cgp) and both were significantly higher (P = 0.0001) than in prediabetic (3.7 +/- 0.81%; 0.4 +/- 0.56 cgp) and nondiabetic control retinas (8.7 +/- 4.66%; 1.2 +/- 1.40 cgp). In new onset diabetes, levels of nitrotyrosine immunoreactivity (60.8 +/- 16.91 cgp) were significantly higher (P = 0.0001) than those in chronic diabetes (29.5 +/- 4.31 cgp); both were significantly higher (P = 0.0001) than those in prediabetic (8.2 +/- 1.70 cgp) and nondiabetic retinas (9.0 +/- 1.87 cgp). There was no cumulative increase in nitrotyrosine in the chronic diabetic retinas as a function of time. In rats with diabetes there was disruption of the inner blood-retinal barrier. These results suggest that iNOS and ONOO(-) may contribute to retinal damage in diabetes from the onset of hyperglycemia in NIDDM.     

Thiazolidinediones upregulate impaired fatty acid uptake in skeletal muscle of type 2 diabetic subjects

We examined the regulation of free fatty acid (FFA, palmitate) uptake into skeletal muscle cells of nondiabetic and type 2 diabetic subjects. Palmitate uptake included a protein-mediated component that was inhibited by phloretin. The protein-mediated component of uptake in muscle cells from type 2 diabetic subjects (78 +/- 13 nmol. mg protein-1. min-1) was reduced compared with that in nondiabetic muscle (150 +/- 17, P < 0.01). Acute insulin exposure caused a modest (16 +/- 5%, P < 0.025) but significant increase in protein-mediated uptake in nondiabetic muscle. There was no significant insulin effect in diabetic muscle (+19 +/- 19%, P = not significant). Chronic (4 day) treatment with a series of thiazolidinediones, troglitazone (Tgz), rosiglitazone (Rgz), and pioglitazone (Pio) increased FFA uptake. Only the phloretin-inhibitable component was increased by treatment, which normalized this activity in diabetic muscle cells. Under the same conditions, FFA oxidation was also increased by thiazolidinedione treatment. Increases in FFA uptake and oxidation were associated with upregulation of fatty acid translocase (FAT/CD36) expression. FAT/CD36 protein was increased by Tgz (90 +/- 22% over control), Rgz (146 +/- 42%), and Pio (111 +/- 37%, P < 0.05 for all 3) treatment. Tgz treatment had no effect on fatty acid transporter protein-1 and membrane-associated plasmalemmal fatty acid-binding protein mRNA expression. We conclude that FFA uptake into cultured muscle cells is, in part, protein mediated and acutely insulin responsive. The basal activity of FFA uptake is impaired in type 2 diabetes. In addition, chronic thiazolidinedione treatment increased FFA uptake and oxidation into cultured human skeletal muscle cells in concert with upregulation of FAT/CD36 expression. Increased FFA uptake and oxidation may contribute to lower circulating FFA levels and reduced insulin resistance in skeletal muscle of individuals with type 2 diabetes following thiazolidinedione treatment.     

Lymphocyte subsets and cytokines in women with gestational diabetes mellitus and their newborn

This study aimed to identify potential immunological markers for predicting type 1 diabetes in patients with gestational diabetes mellitus (GDM) and any immunological impairment in their newborn. In 62 GDM patients and 74 women with normal glucose tolerance (NGT), and their babies, we assessed total lymphocytes, T lymphocyte subsets CD3 and CD8 expressing T cell receptor (TCR) alpha/beta or gamma/delta, CD16 and CD19, pancreatic autoantibodies and cytokines (IL-5, IL-2, soluble receptor IL-2). At delivery, umbilical cord blood samples were taken for lymphocyte subpopulations and cytokine measurements. GDM mothers had higher levels of total lymphocytes, CD8 expressing TCR gamma/delta, and lower levels of CD3 expressing TCR alpha/beta than NGT controls. Insulin-treated GDM mothers had lower CD4 and CD4/CD8 ratios, and higher CD8 and IL-5 than diet-treated GDM or controls. Five women were positive for pancreatic autoantibodies, with lower CD4 (p<0.01) and CD4/CD8 ratios (p<0.05), and higher CD8 (p<0.03) and CD19 than GDM and control mothers negative for autoantibodies. GDM newborn had higher CD8 gamma/delta and lower CD16 than NGT babies. There were no significant differences in TNF-alpha concentrations in the cord blood obtained from the GDM and NGT newborn. In conclusion, GDM women and their newborn have lymphocyte subset impairments, which are more important in patients positive for autoantibodies and/or treated with insulin.     

Correlation between intracellular interferon-gamma (IFN-gamma) production by CD4+ and CD8+ lymphocytes and IFN-gamma gene polymorphism in patients with type 2 diabetes mellitus and latent autoimmune diabetes of adults (LADA)

IFN-gamma is considered to be involved in the pathogenesis of diabetes mellitus. In this study, the presence of T/A mutation at position -874 in IFN-gamma gene was assessed in patients with latent autoimmune diabetes of adults (LADA), in patients with type 2 diabetes and in healthy individuals. Subsequently, an attempt was made to correlate the presence of this mutation with the ability of CD4+ or CD8+ lymphocytes from these individuals to release IFN-gamma following mitogenic stimulation. There were no significant differences in the distribution of genotypes and haplotypes in the three study groups. However, the frequency of the low IFN-gamma production allele (IFN-gamma 874( *)A) was significantly higher in type 2 diabetics compared to controls. CD4+ and CD8+ cells obtained from type 2 diabetics released significantly lower amounts of IFN-gamma in the intracellular space, compared to those released by cells obtained from LADA patients and healthy volunteers. Furthermore, even CD4+ and CD8+ from type 2 diabetics bearing the TT genotype (high producers) released significantly lower amounts of IFN-gamma than LADA patients carrying the same genotype, probably due to the activity of molecules directly or indirectly inhibiting IFN-gamma production. The results of this study indicate that IFN-gamma may contribute to the development of type 2 diabetes, based on a combination of molecular and immunological observations.     

Aberrant Pregnancy Adaptations in the Peripheral Immune Response in Type 1 Diabetes: A Rat Model

Introduction

Despite tight glycemic control, pregnancy complication rate in type 1 diabetes patients is higher than in normal pregnancy. Other etiological factors may be responsible for the development of adverse pregnancy outcome. Acceptance of the semi-allogeneic fetus is accompanied by adaptations in the maternal immune-response. Maladaptations of the immune-response has been shown to contribute to pregnancy complications. We hypothesized that type 1 diabetes, as an autoimmune disease, may be associated with maladaptations of the immune-response to pregnancy, possibly resulting in pregnancy complications.

Methods

We studied pregnancy outcome and pregnancy-induced immunological adaptations in a normoglycemic rat-model of type 1 diabetes, i.e. biobreeding diabetes-prone rats (BBDP; 5 non-pregnant rats, 7 pregnant day 10 rats and 6 pregnant day 18 rats) , versus non-diabetic control rats (i.e. congenic non-diabetic biobreeding diabetes-resistant (BBDR; 6 non-pregnant rats, 6 pregnant day 10 rats and 6 pregnant day 18 rats) and Wistar-rats (6 non-pregnant, 6 pregnant day 10 rats and 5 pregnant day 18 rats)).

Results

We observed reduced litter size, lower fetal weight of viable fetuses and increased numbers of resorptions versus control rats. These complications are accompanied by various differences in the immune-response between BBDP and control rats in both pregnant and non-pregnant animals. The immune-response in non-pregnant BBDP-rats was characterized by decreased percentages of lymphocytes, increased percentages of effector T-cells, regulatory T-cells and natural killer cells, an increased Th1/Th2-ratio and activated monocytes versus Wistar and BBDR-rats. Furthermore, pregnancy-induced adaptations in BBDP-rats coincided with an increased Th1/Th2-ratio, a decreased mean fluorescence intensity CD161a/NKR-P1b ratio and no further activation of monocytes versus non-diabetic control rats.

Conclusion

This study suggests that even in the face of strict normoglycemia, pregnancy complications still occur in type 1 diabetic pregnancies. This adverse pregnancy outcome may be related to the aberrant immunological adaptations to pregnancy in diabetic rats.     

Acute effects of valsartan on insulin sensitivity in obese, non-hypertensive subjects with and without type 2 diabetes.

BACKGROUND: Two studies were designed to determine whether a single dose (80 mg) of the angiotensin II receptor blocker (ARB), valsartan, alters insulin sensitivity in obese, non-hypertensive subjects with and without Type 2 diabetes. METHODS: Insulin sensitivity (S(I)), glucose effectiveness (S(G)), and acute insulin response (AIR(0-10 min)) were measured by means of a 3-hour insulin-modified frequently sampled intravenous glucose tolerance test (FSIVGTT) before and after a single dose of valsartan. Study 1: obese, normotensive non-diabetic male subjects (n = 12), mean (SD) age 37.2 +/- 11.2 years, BMI 32.8 +/- 6.8 kg/m (2); Study 2: obese, normotensive Type 2 diabetic patients (n = 12), mean age 55.7 +/- 6.9 years, BMI 35.0 +/- 6.8 kg/m (2)/l. Both studies were randomised, double-blind, placebo-controlled, single-dose crossover group studies involving subjects in two study days, two weeks apart. After fasting samples were taken, a 300 mg/kg iv glucose bolus was injected at 0 min, and 0.05 U/kg iv insulin was given 20 min later. Blood samples for analysis of glucose and insulin were taken throughout the 3-hour study period. RESULTS: Study 1 (non-diabetic subjects) S(I) 2.81 vs. 2.63 x 10 (-4) min (-1) per microU/ml (p = 0.54), S(G) 0.020 vs. 0.020 min (-1) (p = 0.90), AIR(0-10) min 3305 vs. 3450 microU/min/ml (p = 0.71); Study 2 (patients with type 2 diabetes) S(I) 0.59 vs. 0.85 x 10 (-4) min (-1) per microU/ml (p = 0.15), S(G) 0.013 vs. 0.014 min (-1) (p = 0.71), AIR(0-10) min 65 vs. 119 microU/min/ml (p = 0.14), placebo vs. valsartan, respectively. CONCLUSION: In obese, non-hypertensive non-diabetic and Type 2 diabetic subjects a single dose of valsartan does not alter insulin sensitivity.     

Influence of the thymus extract on the immunological function of animals with experimental diabetes

After immunization with SRBC, the number of plaque-forming cells (PFC) in the spleen of alloxan-diabetic mice, in nondiabetic TIR mice and in alloxan-diabetic TIR mice was significantly decreased as compared with control non-diabetic donors. The ability of lymphocytes from alloxan-diabetic mice to adoptively restore the suppressed immune response of TIR mice, was reduced in comparison with the effect of lymphocytes from normal, nondiabetic donors. Local GVH reaction in nondiabetic rat recipients provoked by lymphocytes from control healthy mice was 5.6 +/- 0.7 mm. Significantly lower rate of local GVH reaction after injection of lymphocytes from diabetic donors was found in diabetic as in nondiabetic recipients as well. Treatment of alloxan-diabetic mice with thymus extract or with insulin, partly restored depressed function of the humoral and cellular system. Treatment of diabetic mice with both thymus extract and insulin, was even more effective in restoring of their immune reactivity. Diabetic condition strongly influenced the function of the immune system. This could be attributed to depletion of T-lymphocytes, changed relations between the lymphocyte subpopulations in diabetic donors, and disturbance of lymphocyte metabolism.     

The role of mutation accumulation in HIV progression

The onset of AIDS is characterized by the collapse of the immune system after a prolonged asymptomatic period. The mechanistic basis of this disease progression has remained obscure, hindering the development of effective therapies. Here I present a mechanism that underlies the deterioration of the immune system during HIV infection. The elevated turnover of lymphocytes throughout the asymptomatic period is postulated to result in the accumulation of deleterious mutations, which impairs immunological function, replicative ability and viability of lymphocytes. This mutational meltdown is proposed to occur throughout the hierarchy of lymphocyte progenitors, resulting in the deterioration of lymphocyte regeneration and an ensuing rise in viral loads. A mathematical model is used to illustrate this mechanism of progressive immunological deterioration. Mutation accumulation may explain not only the decline in CD4+T cells, but also the functional deterioration of CD4+T cells, CD8+T cells and B cells, and the exhaustion of lymphocyte regeneration.     

Reversal of experimental diabetes by multiple bone marrow transplantation

Therapeutic utility of bone marrow transplantation in diabetic patients to overcome deficient beta-cell population is an attractive proposal. However, the status of bone marrow stem cells (BMSCs) under hyperglycemia is not known. In the present study, we investigated the status of BMSCs in experimental-diabetic mice and demonstrated the rescue of experimental diabetes by multiple diabetic bone marrow transplantation. Our flow-cytometry analysis for CD34+, CD45+, flk1+, c-kit+, and CD34+CD45+ revealed that BMSC reserve remains unaffected under sustained hyperglycemia. We found that single injection of diabetic bone marrow cells (approximately 10(6)) resulted in reduction and stabilization of moderate hyperglycemia. However, multiple injections at regular intervals led to restoration of stabilized normoglycemia during a 30 day follow-up. Reversal of diabetes was evidenced by disappearance of hyperglycemia, normal intra-peritoneal glucose tolerance test, and histology and morphometry of pancreas. The present study thus demonstrates that diabetic bone marrow retains its stemness and potential to induce pancreatic regeneration on transplantation.     

Lactate dehydrogenase isoenzymes in diabetic patients

Lactate dehydrogenase (LDH) isoenzyme profiles in human platelets and the sera of patients with type I and II diabetes mellitus and vascular complications, as well as normal subjects were measured utilizing a recently established, modified micromethod. LDH-3 was the predominating species in platelets (37.5 +/- 3.0%), with LDH-2, 1, 4 and 5 following in decreasing order of concentration. The LDH-3/LDH-4 ratio in platelets varied from 6.2 to 1.38. Type I and type II diabetic patients with vascular complications showed a significantly higher ratio for LDH-3/LDH-4 (3.99 +/- 1.20 for DM I, 2.16 +/- 0.25 for DM II patients) than the mean ratio for normal subjects (1.14 +/- 0.08). This platelet-specific LDH isoenzyme pattern may be the result of frequent in vivo platelet-vessel wall interactions in the diabetic patients whose platelets are known to be hyperaggregable in in vitro test systems. Since non-diabetic patients patients with vascular complications also displayed a similarly elevated LDH-3/LDH-4 ratio, a wider classification is preferable, although the measurement of the LDH isoenzyme pattern will be helpful in assessing diabetic vascular complications.