Biomedical subjects
Publications and source records attributed to M Hartog.
CD1 mice infected with Coxsackie B4 virus showed an early polymorph infiltration of the pancreas, which later changed to a mononuclear exudate. A state of glucose tolerance developed concurrently and both events coincided with the inhibition of migration of spleen cells in the presence of the virus. The relevance of these findings to human juvenile-onset diabetes mellitus is discussed.
Using a cellular cytotoxicity assay, we have investigated the antigenicity of pharmaceutical insulins and of highly purified insulin constituents (unformulated monocomponent (MC) insulin, insulin B-component and C-peptide) in control, insulin naive, subjects and in three groups of type I diabetic patients. These were: Group 1, newly diagnosed patients receiving either porcine or bovine MC insulins for less than one week; Group 2, established patients receiving porcine or bovine MC insulin for 2-6 years; Group 3, established patients receiving conventional bovine insulin for 2-6 years, and tested within two weeks of switching to either porcine or bovine MC insulins. In control subjects, there was a higher incidence of cytotoxic reactions with beef (72%) than with porcine (33%) pharmaceutical preparations (p less than 0.01) but there was a similar incidence of reactions with the purified beef and pork constituents. All patients, except those Group 3 patients receiving bovine MC insulins, had a significantly increased incidence of aggregate reactions to the spectrum of antigens. In porcine treated patients, there was an increase in the incidence of reactions to pharmaceutical preparations in Group 1 (p less than 0.05) and Group 3 (p less than 0.001), but this was absent from each of the bovine treated groups. All patient groups showed significant increases in the incidence of reactions against insulin constituents of their therapeutic analog. In Groups 1 and 2, but not 3, there was significant analog cross reactivity. We deduce that the reactivity seen in control subjects is principally directed against unidentified formulation constituents of bovine pharmaceutical preparations. Patients on both acute and chronic therapy with insulin show T-cell sensitization to MC insulin and its components. Chronic therapy with conventional bovine insulin induces tolerogenesis, but this is reversed on exposure to a fresh insulin analog.
Ninety-six juvenile onset type diabetics showed an increase in the frequency of HLA B8 and B15 and a decrease in frequency of HLA B7 antigens. Sixty-four maturity onset diabetics showed no disturbance in the frequency of these antigens. Fifty-four of the juvenile onset type diabetics, with an average duration of disease of 3.2 years were tested for the presence of islet cell antibodies (ICAs). Thirty-two percent were positive, the frequency decreasing from 70% in those patients tested within one year of diagnosis to 0.5% in those patients tested more than 5 years after diagnosis. No correlation was found between HLA type and the frequency of ICAs, but there was an increase in other autoantibodies in B15 positive patients. Preliminary absorption studies suggest a cross reactivity of ICAs and Coxsackie B4 virus.
T- and K-cell cytotoxic activity has been measured in groups of type I diabetic patients and comparable groups of healthy control subjects. The mean cytotoxic indices for T-cell activity were 0.72 for 13 type I diabetics and -2.38 for a control group. These values are not significantly different. K-cell cytotoxic activity was measured using both chicken red blood cells and Chang liver cells coated with appropriate xenogenic antibodies. Using the chicken red blood cell system the percentage specific chromium release was 55.3 for 17 type I diabetics and 50.0 for a control group. These values are not significantly different. Using the chicken red blood cell system the percentage specific chromium release was 55.3 for 17 type I diabetics and 50.0 for a control group. These values are not significantly different. Using the Chang liver cell system the percentage specific chromium release was 13.9 for 37 type I diabetics and 9.7 for a control group. This difference is statistically significant (p less than 0.05).
Insulin antibodies and T-cell lymphocyte cytotoxic reactivity against insulin and its related peptides were studied longitudinally in 3 groups of patients with type I diabetes mellitus (DM). Group 1 patients were those in whom the diagnosis was made within 1 week of the initiation diagnosis. They were subdivided into those receiving MC porcine (A) or MC bovine (B) insulin. Group 2 patients were those with a duration of DM for 2-6 years who were receiving either MC porcine (A) or MC bovine (B) insulins. Group 3 subjects were those who had been on conventional recrystallized insulin and then switched to MC porcine (A) or MC bovine (B) insulins for 2 weeks before the start of the study. The incidence of cytotoxic reactions and insulin antibodies were approximately 40-50% for group 1 (either 1A or 1B) at the initiation of the study. At 3-month follow up all patients in group 1B developed insulin antibodies (p less than 0.02) and a significant increase in the frequency of cytotoxic reactions (p less than 0.01). By contrast there was a decline in the frequency of cytotoxic reactions in group 1A (p less than 0.01 at 1 year) and the increase in insulin antibodies was non-significant. Group 2B had higher frequency in cytotoxic reactions (p less than 0.005) and of insulin antibodies (p less than 0.05) than group 2A. A significant decrease (p less than 0.01) in cytotoxic reactions was observed at 3 months following the switch of patients from conventional bovine insulin preparations to 'A' but not to 'B'. However in both subgroups insulin antibodies persisted for at least 12 months. Cross-reactivity between antibodies to human, porcine and bovine insulins was evident in all groups. The early cellular and humoral immune phenomena were positively correlated in both group 1A and 1B suggesting their common involvement in the pathogenesis of DM.
Glycosylated haemoglobin (GHb) was measured in 71 patients with stable chronic renal failure by the thiobarbituric acid (TBA) reaction and by agar gel electrophoresis. Nineteen patients were diabetic. Of the non-diabetics, 22 were treated conservatively (including 8 children), 15 by maintenance haemodialysis, and 15 by continuous ambulatory peritoneal dialysis. GHb measured by both methods correlated with postprandial blood glucose levels. There was a significant discrepancy between the two methods only in patients with serum urea concentrations greater than 30 mmol/l, mean +/- SD, (6.8 +/- 2.6% vs 8.2 +/- 2.5% for TBA and electrophoresis, respectively). This difference, delta GHb, correlated with serum urea, serum creatinine, and serum bicarbonate, but after logistic regression of results from all 71 patients only serum urea was associated with delta GHb. Lower haemoglobin and GHb and high fetal haemoglobin concentrations in the haemodialysis group suggested increased haemolysis in these patients. Measurement of GHb by the TBA method and by agar gel electrophoresis remain useful indicators of hyperglycaemia in patients with mild, stable chronic renal failure.
In vitro studies have suggested that a low packed cell volume may cause reagent strips to overestimate blood glucose concentration. The reliability of such strips has therefore been investigated in diabetic patients with end-stage renal failure, all of whom had low haematocrits (24 +2- 4 (4/- SD) %). Three brands of strips were evaluated and their results were compared with laboratory whole blood glucose concentrations determined on the same samples. All over-read compared with the laboratory (BM Glycemie 1-44 strips 118 +/- 1%, Glucostix 132 +/- 2%, ExacTech strips 163 +/- 4%) and the percentage overread was negatively correlated with the haematocrit for each strip (all p less than 0.001).
Increased free radical peroxidation of lipoproteins may contribute to the excess atherosclerosis in Type 2 diabetes mellitus and may be aggravated by increasing polyunsaturate intake. Increasing intake of monounsaturates might have similar hypolipidaemic effects while avoiding this problem. Therefore the effects of high monounsaturated and polyunsaturated fat diets on plasma lipoproteins and lipid peroxidation were compared, against each other and a relatively high saturated fat baseline diet, in 13 men with Type 2 diabetes and 12 healthy controls, randomized in crossover fashion to each diet. There were no differences in plasma lipoproteins between the monounsaturated and polyunsaturated fat diets in the diabetic and control groups separately, but when both groups were combined, high density lipoprotein cholesterol was higher on the monounsaturated fat diet (p = 0.04). Plasma lipid peroxidation was similar on the monounsaturated and polyunsaturated fat diets in both groups, but all indices of plasma lipid peroxidation in the diabetic group and lipid peroxides in the controls were significantly lower on these diets compared to the baseline diet. Both high monounsaturated and polyunsaturated fat diets increase hepatic metabolism of low density lipoprotein and shorten its circulating half-life and both may reduce lipid peroxidation, compared to high saturated fat diets, by this mechanism. On high polyunsaturated fat diets, this effect may offset any increased susceptibility of polyunsaturate enriched low density lipoprotein to peroxidation.