The influence of diabetes mellitus on postoperative infections

Clinicians and researchers are linking elevated glucose levels with potential infectious outcomes. Physiologic processes to fight foreign agents are potentially impaired during periods of hyperglycemia. Some of these responses, such as immune function and the inflammatory response, are impaired when they are needed most, such as during the recovery from surgical procedures. Investigators have demonstrated the importance of control of serum glucose postoperatively. Outcomes are improved when tighter glycemic control is practiced. The current literature challenges practitioners to become more cognizant of serum glucose in surgical patients and patients who are critically ill, implementing protocols to gain tighter control of serum glucose in any patient may be appropriate. Further investigation of glycemic control in surgical and other populations will reinforce research findings in this area. Studies should be performed on surgical patients who are particularly vulnerable to DM, glycemic alterations, and postoperative infections, such as patients undergoing peripheral vascular surgery. Further investigations are also needed on the role of hyperglycemia and outcomes in nondiabetic individuals, and on the similarities or differences in glycemic control in types 1 and 2 DM. To increase the generalizability of the study findings, definitions used across studies, such as the type of diabetes, should be standardized. When these studies determine optimal glycemic control practices in a variety of patient populations, clinicians will be able to determine the best practice guidelines to optimize patient care and limit adverse infectious outcomes.

Clinical characteristics and outcome of pregnancy in women with gestational hyperglycaemia with and without antibodies to beta-cell antigens

AIMS

To evaluate the prevalence of beta-cell autoantibodies in women with gestational diabetes and impaired glucose tolerance, and identify clinical characteristics differentiating hyperglycaemic patients with and without autoantibodies.

METHODS

One hundred and twenty-three pregnant patients with gestational diabetes, 84 with impaired glucose tolerance and 290 with normoglycaemia were evaluated for anti-islet cell antibodies, glutamic acid decarboxylase (GAD) autoantibodies, and the components of the metabolic syndrome.

RESULTS

Autoantibody positivity was 8.9%, 17.9% and 0.3% in patients with diabetes, impaired tolerance and normoglycaemia, respectively. Hyperglycaemic patients with autoantibodies had lower body mass index, waist, weight gain at the time of the screening test and a lower percentage of previous pregnancies than those without autoantibodies. In addition, their fasting insulin values were significantly lower and inversely related to the presence of autoantibodies (odds ratio (OR) = 0.64; 95% confidence interval (CI) 0.42-0.96), the lowest values being found in anti-GAD+ patients. Autoantibody-positive women with diabetes were more frequently treated with insulin than negative patients (OR = 7.21; 95% CI 1.85-28.08).

CONCLUSIONS

Autoantibody-positive women with gestational hyperglycaemia displayed fewer features of insulin resistance and required more frequent insulin therapy than negative women and presumably had presymptomatic Type 1 diabetes. If this conclusion is corroborated by the follow-up of larger series, clinical and immunological distinction of types of gestational hyperglycaemia would be useful.

Prediction and diagnosis of type 1 diabetes using beta-cell autoantibodies

The clinical manifestation of type 1 diabetes is the endpoint of a long-lasting immune-mediated destruction process of the B-cells. Autoantibodies originating from this process can be applied in the diagnosis and clinical discrimination of autoimmune diabetes as well as in the prediction of this disease. At clinical diagnosis between 80-90% of patients with type 1 diabetes are positive for antibodies to B-cell antigens, such as ICA and antibodies to glutamic acid decarboxylase or IA2. These antibodies can also be detected in the presymptomatic period before onset of the disease, and can thus be used to predict type 1 diabetes. Using a combination of antibodies, diabetes can be predicted in 70-80% of future cases of diabetes, with a positive predictive value between 30-80%, depending on the type of antibody tested for and the population studied. Between 5 and 30% of patients initially diagnosed with type 2 diabetes will show progression to insulin dependency and turn out to have type 1 within three years of diagnosis. It is clinically relevant to identify these patients early in the course of disease, as deterioration of metabolic control results in an increased risk for macro- and micro-vascular complications. Autoantibodies to glutamic acid decarboxylase or ICA are of high diagnostic sensitivity in these cases and are better predictors for future insulin dependency than biochemical or clinical parameters. Increasing knowledge on the applicability of antibodies for diabetes prediction and diagnosis and the development of commercial assays for antibodies to glutamic acid decarboxylase and IA2 antibodies has enabled the implementation of B-cell autoantibodies in routine diagnostic settings.

Thyroid autoimmunity in children and adolescents with type 1 diabetes: a multicenter survey

OBJECTIVE

To investigate thyroid autoimmunity in a very large nationwide cohort of children and adolescents with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Data were analyzed from 17,749 patients with type 1 diabetes aged 0.1-20 years who were treated in 118 pediatric diabetes centers in Germany and Austria. Antibodies to thyroglobulin (anti-TG) and thyroperoxidase (anti-TPO) were measured and documented at least once in 7,097 patients. A total of 49.5% of these patients were boys, the mean age was 12.4 years (range 0.3-20.0 years), and the mean duration of diabetes was 4.5 years (range 0.0-19.5 years). A titer exceeding 100 units/ml or 1:100 was considered significantly elevated.

RESULTS

In 1,530 patients, thyroid antibody levels were elevated on at least one occasion, whereas 5,567 were antibody-negative during the observation period. Patients with thyroid antibodies were significantly older (P < 0.001), had a longer duration of diabetes (P < 0.001), and developed diabetes later in life (P < 0.001) than those without antibodies. A total of 63% of patients with positive antibodies were girls, compared with 45% of patients without antibodies (P < 0.001). The prevalence of significant thyroid antibody titers increased with increasing age; the highest prevalence was in the 15- to 20-year age group (anti-TPO: 16.9%, P < 0.001; anti-TG: 12.8%, P < 0.001). Thyroid-stimulating hormone (TSH) levels were higher in patients with thyroid autoimmunity (3.34 microU/ml, range 0.0-615.0 microU/ml) than in control subjects (1.84 microU/ml, range 0.0-149.0 microU/ml) (P < 0.001). Even higher TSH levels were observed in patients with both anti-TPO and anti-TG (4.55 microU/ml, range 0.0-197.0 microU/ml).

CONCLUSIONS

Thyroid autoimmunity seems to be particularly common in girls with diabetes during the second decade of life and may be associated with elevated TSH levels, indicating subclinical hypothyroidism.

The diabetes-prone NZO/Hl strain. II. Pancreatic immunopathology

We report the first combined light and electron microscopic analysis of the pancreas during the development of type 2 diabetes in the New Zealand Obese (NZO) mouse. As in most other polygenic rodent models of type 2 diabetes, hyperglycemia associated with beta cell destruction is male sex-limited. Increasing degrees of hyperinsulinemia and transition to diabetes were clearly reflected by the islet volume fraction, by the beta cell granulation state, and by ultrastructural changes, primarily of the endoplasmic reticulum. One of the unusual histopathologic features of NZO mice of both sexes was the presence of B-lymphocyte enriched leukocytic aggregates in the pancreas. Immunocytochemical analysis of the pancreas of 52-week-old diabetic males indicated enrichment for CD19(+) B lymphocytes. Staining of adjacent sections for CD3 and CD5 indicated CD5 coexpression on some of the CD19(+) cells, suggesting the presence of the B1-B subset associated with generation of natural autoantibodies in other autoimmune-prone New Zealand mouse strains. In addition, plasma cells in peri-insular leukocytic infiltrates were identified by electron microscopy. Hence, although autoimmunity has previously proven to be a secondary manifestation of beta cell destruction in most rodent models of type 2 diabetes, the present observations suggest that B lymphocyte function, in association with male gender, may contribute to the development of insulin resistance and chronic hyperglycemia in the NZO model.

Antidiabetogenic effect of mycophenolate mofetil is associated with down-regulation of adhesive interactions and autoreactive cell activation

We have investigated the immunomodulatory potential of mycophenolate mofetil (MMF) on the development of autoimmune diabetes induced by multiple low doses of streptozotocin (MLD-SZ) in genetically susceptible DA rats. Administration of 25 mg/kg MMF continuously during the 7 weeks of MLD-SZ treatment, or as a 10-day treatment starting together with MLD-SZ (early treatment), or 5 days after the last dose of SZ (late treatment) significantly suppressed the development of hyperglycemia. Ex vivo analyses performed on day 10 after diabetes induction showed that MMF treatment down-regulates adhesive interactions and proliferation of autoreactive spleen cells. Similar effects were observed in vitro when MLD-SZ-derived splenocytes were cultured with an active metabolite of MMF, mycophenolic acid (MPA). These results suggest that the antidiabetogenic effect of MMF involves inhibition of the expansion and migration of autoreactive cells.

Low-dose streptozotocin induces sustained hyperglycemia in Macaca nemestrina

The potential for using macaques to create a nonhuman primate diabetic model was investigated. The significant objectives were to determine a) prognosis of STZ induced permanent beta cell destruction in nonhuman primates, and b) the potential to use STZ treated animals in a model of autoimmune diabetes by following adoptively transferred lymphocytes into MHC identical macaques. Beta cell impairment was achieved by a single intravenous, low dose (10-40 mg/kg body weight) streptozotocin injection in a majority of pigtailed macaques (Macaca nemestrina). Multiple injections, even at low doses at close intervals affected liver and kidney functions in addition to beta cell destruction. Abnormal IVGTT were observed in all streptozotocin-treated animals, in some within a week to 10 days. The fasting blood glucose levels rose from <70 mg/dl in pre-STZ stage to above 400 mg/dl in severely diabetic macaques. Histological evidence suggests loss of beta cells when animals were euthanized within two to four weeks post-STZ treatment. Near complete destruction of beta cells was observed in animals maintained longer than three months on insulin. Donor T cells from STZ-treated animals were incubated overnight with 10U/ml IL-2 and 2.5 ug/ml PHA and then injected iv into a MHC-identical non-diabetic sibling. Three weeks later a second injection of donor PMBC labeled with vital dye Cell Tracker Green was given and the animal was euthanized after 24 hours. The recipient showed labeled donor T cells in the pancreas, spleen and peripheral blood, consistent with specific homing of activated lymphocytes from the diabetic donor.

Agonist-dependent failure of neutrophil function in diabetes correlates with extent of hyperglycemia

Inexplicable controversies with regard to possible functional defects of neutrophilic polymorphonuclear leukocytes (PMNs) in diabetes persist. The purpose of the present study was to elucidate the relative effectiveness of several PMN agonists in stimulating lysosomal-enzyme secretion and leukotriene (LT) B(4) production by PMNs isolated from diabetic subjects. Formyl-methionyl-leucyl-phenylalanine (fMLP) and platelet-activating factor (PAF) induced significantly less lysosomal-enzyme secretion and LTB(4) production in diabetic-subject PMNs than in normal-subject PMNs. It is surprising that PMNs from these same diabetic subjects responded normally after stimulation with A23187, serum-opsonized zymosan, or phorbol myristate acetate. The in vitro responsiveness of PMNs stimulated with fMLP or PAF was inversely correlated with indices of in vivo glycemic control (fasting plasma glucose and glycated-hemoglobin levels). In combination, these results indicate that hyperglycemia is associated with sustained decreases in PMN function but only in response to agonists that initiate stimulus-response coupling via G-protein-coupled receptors. This agonist-selective reduction in PMN responsiveness may contribute to the compromised host defense associated with sustained hyperglycemia in diabetes.

Risk of type 1 diabetes development in children with incidental hyperglycemia: A multicenter Italian study

OBJECTIVE

The aim of our study was to determine whether children with incidental hyperglycemia are at an increased risk of developing type 1 diabetes.

RESEARCH DESIGN AND METHODS

A total of 748 subjects, 1-18 years of age (9.04 +/- 3.62, mean +/- SD), without family history of type 1 diabetes, without obesity, and not receiving drugs were studied and found to have incidental elevated glycemia defined as fasting plasma glucose >5.6 mmol/l confirmed on two occasions. Subjects were tested for immunological, metabolic, and immunogenetic markers.

RESULTS

Islet cell antibodies >5 Juvenile Diabetes Foundation units were found in 10% of subjects, elevated insulin autoantibody levels in 4.6%, GAD antibody in 4.9%, and anti-tyrosine phosphatase-like protein autoantibodies in 3.9%. First-phase insulin response (FPIR) was <1st centile in 25.6% of subjects. The HLA-DR3/DR3 and HLA-DR4/other alleles were more frequent in hyperglycemic children than in normal control subjects (P = 0.012 and P = 0.005, respectively), and the HLA-DR other/other allele was less frequent than in normal control subjects (P = 0.000027). After a median follow-up of 42 months (range 1 month to 7 years), 16 (2.1%) subjects (11 males and 5 females), 4.1-13.9 years of age, became insulin dependent. All had one or more islet autoantibodies, and the majority had impaired insulin response and genetic susceptibility to type 1 diabetes. Diabetes symptoms were recorded in 11 patients and ketonuria only in 4 patients. The cumulative risk of type 1 diabetes was similar in males and females, and it was also similar in subjects under or over 10 years, whereas the cumulative risk of type 1 diabetes was increased in subjects with one or more autoantibodies and in those with FPIR <1st centile.

CONCLUSIONS

Children with incidental hyperglycemia have a higher-than-normal frequency of immunological, metabolic, or genetic markers for type 1 diabetes and have an increased risk of developing type 1 diabetes.

Short-term hyperglycemia induces lymphopenia and lymphocyte subset redistribution

Alterations in lymphocytes are a common finding in both type I and type II diabetes. Autoimmune phenomena in type I diabetes, the stage of the diabetic disorder and metabolic effects of therapeutic interventions may also affect actual distribution of lymphocyte phenotypes. This study investigated immunological effects specific to standardized hyperglycemia in non-diabetic individuals to exclude immunological changes potentially related to diabetes stage and treatment. 37 subjects (mean age +/- SD 39 +/- 5 years) underwent a sequence-controlled crossover with oral administration of a solution containing either 75 g glucose or artificial sweetener (i.e. placebo). At rest and at two hours, counts of white blood cells (WBC), mixed lymphocytes, mature T-cells (CD3), T-helper cells (CD4), T-suppressor/ cytotoxic cells (CD8), B-cells (CD19), natural killer cells (CD16/CD56), and interleukin-2 receptor bearing peripheral blood mononuclear cells (CD25) were measured by flow cytometry. Subjects showed a significant decrease in WBC, lymphocytes, and all lymphocyte subsets with the OGTT compared with the placebo solution (p < .05 to p < .001). In non-diabetic individuals, short-term hyperglycemia induces immunological changes that may be relevant to explain similar findings in patients with diabetes mellitus. Future studies need to validate these findings and their potential clinical implications in a diabetic population.

Elevated ambient glucose induces acute inflammatory events in the microvasculature: effects of insulin

We employed intravital microscopy of the rat mesenteric microvasculature to study the effects of local hyperglycemia on leukocyte-endothelial cell interactions. Intraperitoneal injection of 6, 12.5, and 25 mmol/l D-glucose to the rat significantly and time-dependently increased leukocyte rolling and leukocyte adherence in, and leukocyte transmigration through mesenteric venules compared with control rats injected with Krebs-Henseleit (K-H) solution alone or given 25 mmol/l L-glucose intraperitoneally. The response elicited by D-glucose was associated with significant attenuation of endothelial nitric oxide (NO) release, as demonstrated by direct measurement of NO release in inferior vena caval segments isolated from rats exposed to 25 mmol/l D-glucose for 4 h (P < 0.01 vs. vena caval segments from control rats). Local application of 0.05 U/min insulin for 90 min significantly attenuated glucose-induced leukocyte rolling, adherence, and migration (P < 0.01 from 25 mmol/l D-glucose alone). Immunohistochemical localization of P-selectin expressed on endothelial surface was significantly increased 4 h after exposure of the mesenteric tissue to high ambient glucose (P < 0.01 vs. ileal venules from rats injected with K-H solution alone or 25 mmol/l L-glucose). Insulin markedly inhibited endothelial cell surface expression of P-selectin in ileal venules exposed to elevated ambient glucose in vivo (P < 0.01 vs. control rats injected with 25 mmol/l L-glucose). These data demonstrate that acute increases in ambient glucose comparable to those seen in diabetic patients are able to initiate an inflammatory response within the microcirculation. This inflammatory response to glucose is associated with upregulation of the endothelial cell adhesion molecule P-selectin and can be blocked by local application of insulin.

Acute activation of peripheral lymphocytes during treatment of diabetic ketoacidosis

Activated peripheral T-lymphocytes are increased in both pre-insulin-dependent diabetes mellitus (IDDM) patients and in recently diagnosed IDDM patients, as well as in various forms of acute stress. We studied the in vivo T-lymphocyte activation in six patients in severe diabetic ketoacidosis (DKA) prior to treatment, after 24 h of treatment and > or =5 days after admission. Five of the six patients showed an increased percentage of activated T-lymphocytes based on the expression of HLA-DR at 24 h of treatment when compared to the admission percentage of activation (P<.05). There was no correlation to the admission serum glucose, osmolality, or electrolytes. Serum pH showed a trend toward an inverse correlation, but was not statistically significant. We speculate that T-lymphocyte activation plays a role in the progression of the acute complications of subclinical brain edema and interstitial pulmonary edema of DKA. This process could also be another factor in the progression of the chronic complications of IDDM in addition to the well-established effects of hyperglycemia and hypertension.

Possible relationship of monocyte chemoattractant protein-1 with diabetic nephropathy

BACKGROUND

Monocyte chemoattractant protein-1 (MCP-1) is a specific chemokine to recruit and activate monocytes from the circulation to inflammatory site. In diabetic nephropathy, similar to other glomerulonephropathies, infiltration and activation of monocytes/macrophages in glomerulus have been implicated in the development of glomerular injury. The aim of the present study was to examine a possible relationship of MCP-1 with diabetic nephropathy and to investigate the role of glycated albumin (Gly-Alb) as well as high concentration of glucose (HG) on MCP-1 production by cultured human mesangial cells.

METHODS

MCP-1 in serum or urine and urinary albumin (Alb) as well as several clinical parameters such as plasma glucose, serum Gly-Alb, and hemoglobin A1c (HbA1c) were measured after overnight fasting in 16 control subjects and 54 diabetic patients. The relationships between the levels of urinary Alb and urinary or serum MCP-1 and also between the values of respective clinical parameter and urinary MCP-1 levels were analyzed. Next, using cultured human mesangial cells, we investigated the role of Gly-Alb and/or HG on the gene and protein expression of MCP-1.

RESULTS

Urinary levels (ng/g creatinine), but not serum levels, of MCP-1 increased in accordance with the extent of albuminuria. In all subjects, there were significant correlations between the urinary levels of Alb and MCP-1 (r = 0.746, P < 0.0001) and between the levels of serum Gly-Alb and urinary MCP-1 (r = 0.475, P < 0.0001). In cultured human mesangial cells, the gene and protein expression of MCP-1 was dose and time dependently up-regulated by Gly-Alb. HG slightly but significantly stimulated MCP-1 expression. The combination of Gly-Alb and HG showed the greatest stimulation in more than an additive manner on MCP-1 production.

CONCLUSIONS

This study suggests that facilitated MCP-1 production by mesangial cells in diabetic milieu contributes to the initiation and progression of diabetic nephropathy.

Amelioration of hyperglycemic and hyperosmotic induced vascular dysfunction by in vivo inhibition of protein kinase C and p38 MAP kinase pathway in the rat mesenteric microcirculation

BACKGROUND

Recently, we demonstrated in vivo effects of acutely induced hyperglycemia, diabetes and mannitol infusions on rat mesenteric microcirculation concerning leukocyte-endothelial-cell interaction (Schäffler et al. EJCI 28: 886-893, 1998).

DESIGN

In this study we have investigated the possible involvement of the protein kinase C (PKC) and p38 MAP kinase cascade as signal transducing elements during hyperglycemic and osmotic stress in an in vivo rat model.

RESULTS

Acutely induced hyperglycemia resulted in a significant increase in leukocyte adhesion. This effect could be mimicked by mannitol. Both PKC and p38 MAP kinase were involved in the effects mediated by glucose and mannitol. Acutely induced hyperglycemia resulted in a significant increase in leukocyte emigration. This effect could be imitated by mannitol. However, PKC and p38 MAP kinase were only involved under osmotic stimulation. The hyperglycemia-induced reduction in leukocyte rolling velocity seemed to be a glucose-specific effect, since mannitol did not influence leukocyte rolling velocity. This glucose effect on leukocyte rolling velocity was mediated by an activation of the PKC/p38 MAP kinase cascade. Both hyperglycemia and osmotic stimuli alone were able to reduce venular shear rate without recruitment of the p38 MAP kinase cascade. The observed reduction of shear rate seems to be mediated only by the osmotic effects of glucose via activation of the PKC system.

CONCLUSION

The observed effects of glucose on adhesion, emigration and shear rate are due to osmotic effects. The PKC/MAP kinase cascade is involved as a signal transducing component. The reduction of leukocyte rolling velocity is a glucose-specific effect, mediated by the activation of both the PKC and the p38 MAP kinase cascade. Venular shear rate and leukocyte emigration can be influenced by glucose and mannitol due to different regulation mechanisms. It is concluded, that isoform-specific inhibitors of PKC and specific MAP kinase inhibitors represent a potential drug target for preventing microvascular dysfunction in diabetes.

Effect of hyperglycemia and hyperlipidemia on atherosclerosis in LDL receptor-deficient mice: establishment of a combined model and association with heat shock protein 65 immunity

Diabetes and atherosclerosis have been proposed to be influenced by immune and autoimmune mechanisms. A common incriminated antigen in both disorders is the heat shock protein (HSP)-60/65. In the current study, we established a model combining hyperglycemia with hyperlipidemia in LDL receptor-deficient (LDL-RD) mice and assessed its possible influences on lipid profile, HSP60/65, and atherogenesis. LDL-RD mice were injected either with streptozotocin to induce hyperglycemia or with citrate buffer (control). When hyperglycemia was induced, both study groups were challenged with a high-fat (Western) diet for 6 weeks. Plasma fasting glucose, lipid profile, and antibody levels to HSP65 and oxidized LDL were assessed. At death, the spleens from both groups were evaluated for their proliferative response to HSP65 and the consequent cytokine production. The extent of atherosclerosis was assessed at the aortic sinus. Plasma glucose, cholesterol, and triglyceride levels were elevated in mice injected with streptozotocin compared with control mice. Atherosclerotic lesions were significantly larger in the streptozotocin-injected hyperglycemic LDL-RD mice (132 +/- 23 x 10(5) microm2) in comparison to their normoglycemic litter-mates (20 +/- 6.6 x 10(5) microm2; P < 0.0001). Both humoral and cellular immune response to HSP65 was more pronounced in streptozotocin-injected mice. When challenged with HSP65 in vitro, splenocytes from streptozotocin-injected mice favored the production of the T-helper (TH)-1 cytokine gamma-interferon. In conclusion, we have established a mouse model that combines hyperglycemia with diet-induced hyperlipidemia in LDL-RD mice and studied its effect on atherosclerosis progression. The accelerated atherosclerotic process is associated with heightened immune response to HSP65 and a shift to a TH1 cytokine profile.

Unintended immunomodulation: part I. Effects of common clinical conditions on cytokine biosynthesis

Cytokines are low molecular weight proteins that act in an autocrine, paracrine and endocrine fashion to regulate and integrate immune effector cell function. Cytokine production is tightly controlled by a complex network of co-stimulatory and feedback loops. The systemic concentrations of some cytokines, most notably tumor necrosis factor and various interleukins, correlate with the extent of inflammation, and the severity of critical illness and patient outcome. Thus, cytokine expression is often monitored and/or manipulated as a therapeutic target in studies of sepsis and other inflammatory conditions. Unfortunately, some therapies designed to modify cytokine response have failed to improve outcomes in sepsis, and some of these therapies have actually been harmful. Several common clinical conditions, as well as, therapeutic interventions significantly influence cytokine expression. Furthermore, the magnitude and extent of these effects may be greater than those produced by immunomodulating therapies. In contrast, other conditions may not produce clinically significant changes in cytokine expression, and must simply be considered when interpreting studies designed to determine the effects of immunomodulation. Some conditions may even result in changes in the inflammatory response and may thus add to the inflammatory burden of a critically ill patient. This review provides intensivists and other clinicians with an overview of the effects of altered physiologic conditions on cytokine expression. This information is important so that studies measuring cytokines can be correctly interpreted and clinical circumstances in which cytokine manipulation is undesirable can perhaps be avoided.

An anti-insulin serum, but not a glucagon antagonist, alters glycemia in fed chickens

Attempts at altering plasma glucose and, as a consequence, food intake were performed in fed broiler chickens by single i.v. injection of des-His1(Glu9) glucagon amide (a glucagon antagonist) or a non-stimulating anti-insulin serum. Plasma glucose level was not altered by des-His1(Glu9) glucagon amide but was rapidly and largely increased (for at least 2 h) by the injection of the insulin-immune serum. Hour and cumulative food intake were unaltered up to 10 h post injection. These results strongly suggest that in fed chickens, plasma glucose is mainly, if not exclusively, controlled by plasma insulin, and that the transient and heavy hyperglycemia evoked by inhibiting insulin action does not alter food intake.

[Heterogeneity of diabetes mellitus]

AIM

To define a criterium for differentiation of different types of diabetes mellitus (DM).

MATERIALS AND METHODS

The condition of immunity, antibodies to the pancreatic island cells, proliferative activity of peripheral blood lymphocytes in response to human immunoglobulin were studied in 152 patients with DM.

RESULTS

Sensitization of lymphocytes to insulin is associated with DM type I. Latent sensitization of lymphocytes to insulin detectable in inhibition of functional activity of prostaglandin-synthesizing cells is encountered in classic course of DM type II, while detectable in inhibition of functional activity of the cells carrying receptors to histamine is observed in patients with symptoms of either DM type I or DM type II. Lack of either apparent or latent lymphocyte sensitization to insulin in chronic hyperglycemia is associated with secondary DM.

CONCLUSION

How lymphocytes are sensitized to insulin is important for differential diagnosis not only of DM type but also of DM forms within the same type. Groups of the DM patients were different not only by immunological indices but also by clinical course, treatment and prognosis.

Refractory hyperglycemia complicating an evolving connective tissue disease: response to cyclosporine

A 33-year-old woman with longstanding rheumatoid arthritis and Sjögren's syndrome developed type B insulin resistance (diabetes mellitus due to anti-insulin receptor antibodies) simultaneous with the evolution of her rheumatic disease to mixed connective tissue disease. Cyclosporine therapy induced a remission of receptor antibody mediated insulin resistance and controlled clinical manifestations of her systemic lupus erythematosus and dermatomyositis, but had no effect on the sclerodermatous features of her illness.

Streptozotocin-induced diabetes in mice lacking alphabeta T cells

Multiple low-dose streptozotocin (MD-STZ) is widely used for the experimental induction of diabetes, but, as non-obese diabetic (NOD)-scid/scid mice have been found to display enhanced susceptibility to MD-STZ, whether or not the model is genuinely autoimmune and T cell-mediated has been unclear. Mice bearing a targeted mutation of the T cell receptor (TCR) alpha-chain were therefore used to assess whether TCR alphabeta+ cells are involved in the diabetogenic effects of MD-STZ injections. Young NOD mice lacking TCR alphabeta cells, when given five daily injections of 40 mg/kg STZ, developed diabetes at low frequency (2/12), despite the widespread destruction of pancreatic islet cells. By comparison, most normal control mice became hyperglycaemic (12/23). We conclude that whilst much of the tissue destruction observed in this model is due to the direct toxic effect of STZ, a significant amount is also due to the action of TCR alphabeta cells tipping the balance between tolerable and clinically damaging action on islet cells.

Immunologic effects of acute hyperglycemia in nondiabetic rats

BACKGROUND

This study was designed to determine the consequences of acute hyperglycemia on the immune function of peripheral neutrophils, peritoneal macrophages, and alveolar macrophages in nondiabetic rats.

METHODS

The animals were randomly divided into nonsurgical (normal) and surgical groups. The postoperative rats were further divided into normoglycemic (control) and hyperglycemic (glucose) groups. The hyperglycemic condition was maintained by constant infusion of glucose to raise plasma glucose concentration to 300 mg/dL for 3 hours. The immune cells were then harvested to determine their phagocytic and oxidative capacities via flow cytometry.

RESULTS

The results showed that hyperglycemia significantly decreased the respiratory burst of alveolar macrophages (p < .05). In contrast, hyperglycemia enhanced phagocytosis in these cells (p < .002). There was a significant activation of the respiratory burst in peripheral neutrophils by surgery (p < .002), but no effect of hyperglycemia.

CONCLUSIONS

We conclude that hyperglycemia itself can influence immune function in some phagocytic cells, which may be an important factor in postsurgical infection.

Alterations in the expression of the alpha 3 beta 1 integrin in certain membrane domains of the glomerular epithelial cells (podocytes) in diabetes mellitus

In view of the major alterations which take place at the level of the extracellular matrix of the glomerular wall in diabetes mellitus and the key roles played by beta 1 integrins in cell-to-matrix interactions, it is imperative to understand the role played by integrins in the development of diabetic glomerulosclerosis. In the present study, we revealed by immunocytochemistry the ultrastructural distribution of the alpha 3 beta 1 at the level of the plasma membrane of the different renal glomerular cells from short- and long-term diabetic rats. For the endothelial cells, the labelling present on both the luminal and abluminal plasma membranes was low. For the podocyte epithelial cells, the labelling was present on both the luminal and basal plasma membranes, the former being concentrated at points of contact between podocyte foot processes. The labelling on the basal plasma membrane was more significant and similar in domains facing either the glomerular basement membrane or the mesangial matrix. The plasma membrane of mesangial cells also exhibited alpha 3 beta 1. The labelling was recorded under diabetic conditions, at the same sites, with similar intensities, alongside that of the basal plasma membrane of podocytes facing the glomerular basement membrane, the density of which decreased significantly. This decrease in labelling was similar in renal tissues from short- and long-term diabetic animals. These results demonstrate that alpha 3 beta 1 present at the podocyte basal plasma membrane facing the glomerular basement membrane, which undergoes important alterations in diabetes, could be involved in the major dysfunctions of the glomerular wall characteristic of diabetic glomerulosclerosis. Since the changes in integrin were found to occur as early as after 1 month of hyperglycaemia, when morphological alterations of the glomerular basement membrane are not yet established, we propose that they constitute an early event which precedes the onset of diabetic nephropathy.

Prediabetic markers in children with stress hyperglycemia

BACKGROUND

Previous studies have shown that children with stress hyperglycemia have an increased risk for development of type I or insulin-dependent diabetes mellitus.

OBJECTIVE

To determine whether stress hyperglycemia in prospectively screened pediatric patients represents a prediabetic state.

DESIGN

Prospective, cohort analytic study.

SETTING

The Children's Hospital of the King's Daughters is an urban pediatric emergency department at a tertiary care, university-based children's hospital in Norfolk, Va.

PATIENT POPULATION

All patients who required a venipuncture for evaluation of an acute illness or injury from October 1992 through March 1993 were screened prospectively for hyperglycemia (blood glucose level > or = 8.3 mmol/L [> or = 150 mg/dL]). Each hyperglycemic patient was age matched to a stress control subject (defined as a nonhyperglycemic but acutely ill child) from the emergency department and a healthy control subject from a well-child clinic.

INTERVENTION

Blood samples were obtained at the time of initial evaluation in the emergency department from 30 hyperglycemic patients (age range, 4 weeks to 12.4 years; median, 2 years), 30 stress control subjects, and 30 healthy control subjects. All samples were tested for islet cell antibodies, insulin autoantibodies, glutamic acid decarboxylase (GAD) antibodies, and HLA typing, specifically the genotypes at the DQB1 gene.

MAIN OUTCOME MEASURES

The presence of immunologic or genetic markers for insulin-dependent diabetes mellitus and/or the clinical development of insulin-dependent diabetes mellitus.

RESULTS

No patients or control subjects were positive for islet cell antibodies. One hyperglycemic patient and 3 stress control subjects were positive for insulin autoantibodies; all 4 of these subjects had sickle-cell disease and fever. Four of the 8 patients with sickle-cell disease had insulin autoantibodies, compared with none of the 52 patients and stress control subjects without sickle-cell disease (P < .001). One healthy control subject had antibodies to GAD65. The patient group did not show increased genotypes at the DQB1 gene that were indicative of an enhanced risk for insulin-dependent diabetes mellitus. Of the 32 hyperglycemic patients, 27 healthy control subjects, and 25 stress control subjects contacted for follow-up at 31 to 36 months, none has developed insulin-dependent diabetes mellitus.

CONCLUSIONS

Children with stress hyperglycemia do not have an increased prevalence of immunologic or genetic markers of insulin-dependent diabetes mellitus and thus do not appear to be at an increased risk for development of insulin-dependent diabetes mellitus. Our data suggest that insulin autoantibodies develop in children subject to sickle cell crises.

Transgenic expression of interleukin 10 in the pancreas renders resistant mice susceptible to low dose streptozotocin-induced diabetes

Transgenic mice expressing interleukin 10 (IL-10) within the beta cells of the pancreas were used to assess the role of this cytokine in the development of diabetes following low-dose streptozotocin treatment. Nontransgenic mice injected with low doses of streptozotocin were largely resistant to the induction of hyperglycaemia; that is, average blood glucose values, although above mean blood glucose levels of buffer-injected controls, did not exceed 14 mmol/l. In sharp contrast, IL-10 transgenic mice exhibited significant sensitivity to the diabetogenic actions of streptozotocin resulting in a mean blood glucose level of 21.6 mmol/l at the end of the 56-day study period. Histological analysis of pancreata from streptozotocin-injected transgenic mice revealed severe insulitis and destruction of pancreatic beta cells, whereas their streptozotocin-injected nontransgenic littermates remained completely insulitis-free. According to immunocytochemical analysis, the pancreatic inflammatory infiltrates of streptozotocin-injected transgenic mice contained CD4+ and CD8+ T lymphocytes, B lymphocytes and macrophages. Furthermore, various adhesion molecules, the co-stimulatory molecule B7-1 and the Ia antigen could be detected. Splenocytes from streptozotocin-injected transgenic mice did not transfer disease to irradiated syngeneic nontransgenic recipients, suggesting that the presence of IL-10 in streptozotocin-injected mice had a general immunostimulatory effect but did not lead to the activation of beta cell-specific T cells. Our data suggest a critical role for IL-10 in the development of diabetes in vivo despite its established immunosuppressive activities in vitro.