Insulin-specific IgE in serum of 67 diabetic patients against human insulin (Novo), porcine insulin, and bovine insulin. Four case reports.

We have investigated the binding of insulin-specific IgE (IgE1) to porcine, bovine, and human insulin (Novo), pancreatic polypeptide, and a-component in serum samples from type I diabetic patients treated with insulin preparations of different purity. Patients treated with porcine or mixed-species purified insulin (monocomponent) did not differ significantly from a nondiabetic control group. Hence, in these groups no IgE1 could be detected against any of the components investigated. Serum samples from patients treated with five-times recrystallized insulin preparations and patients with insulin allergy showed a significantly greater binding of IgE1 to the three species of insulin; IgE1 binding was greatest to bovine insulin and least to human insulin. The difference in binding was most significant in the allergic patients (P less than 0.001), probably due to differences in the affinity. It is concluded that conventional (recrystallized) insulin induces more IgE1 than monocomponent insulin. Data are presented on confirmed allergy in four diabetic patients whose allergy disappeared upon transfer to human insulin.

Evaluation of patients with local reactions to insulin with skin tests and in vitro techniques.

To better understand the part played by IgE and IgG antibody in the production of dermal reactions to insulin and the usefulness of skin tests in the evaluation of these reactions, we studied 21 diabetic patients referred for evaluation of large local insulin reactions, 46 diabetic patients without local insulin reactions, and 22 healthy nondiabetic controls. Study subjects were skin tested with 15 different insulins, and the results were evaluated over 48 h. All control subjects and 41 of 46 diabetic patients without local reactions were skin-test negative to insulin. The 11% of diabetic patients who reacted had positive wheal-and-flare reactions at 20 min to animal-species insulin but negative skin tests to human insulin. Study revealed two subgroups of patients with histories of local reactions. Ten (48%) of these patients had negative skin tests to insulin. Five of this subgroup remained skin-test negative to quantities of less than or equal to 8 U insulin/skin test. Eleven (52%) of the patients formed a subgroup with positive insulin skin tests; most of these patients were skin-test positive to human insulin and to beef, pork, or both insulins as well. Although the group mean insulin-specific IgE values of this latter subgroup were significantly higher than those of any other study group, overlap of these individual IgE values did not allow separation of specific individuals with positive skin tests from those of patients on insulin without dermal reactions.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of hyperinsulinemia on arterial wall and peripheral muscle metabolism in dogs.

Peripheral hyperinsulinemia may be associated with metabolic consequences that could contribute to the high incidence of macrovascular disease in patients with diabetes mellitus. Arterial wall and striated muscle cells were studied in dogs to examine the effect of hyperinsulinemia on the lipid content and on lipogenic and glycolytic enzyme activity. Eight pancreatectomized dogs received segmental pancreatic autografts with venous drainage into the iliac vein. Glucose disappearance rates (K values) were normal four years after transplantation, but both fasting serum insulin levels (48.9 +/- 4.8 v 11.8 +/- 1.9 microU/mL) and the total area under the glucose-insulin response curve (1797 +/- 196 v 1110 +/- 158 microU X min/mL) were significantly greater than in control animals (P less than 0.05). The hyperinsulinemic dogs had a marked triglyceride elevation in arterial smooth muscle (20.6 +/- 8.0 v 0.5 +/- 0.4 mumol/g) and striated muscle (171.4 +/- 46.6 v 41.2 +/- 7.7 mumol/g) (P less than 0.001). Moreover, key enzymes in lipid synthesis (glucose-6-phosphate dehydrogenase, malic enzyme, and 3-hydroxyacyl-CoA DH) were significantly increased (P less than 0.01) in the hyperinsulinemic animals, while the glycolytic enzymes, (phosphofructokinase, hexokinase, pyruvate kinase, and alpha-glycerophosphate DH) were not significantly different. These data demonstrate substantial enhancement of lipid synthesis in arterial wall and striated muscle in hyperinsulinemic dogs. Altered substrate metabolism in arterial walls, in association with hyperinsulinemia, may have important implications with regard to macrovascular disease in diabetes, particularly in insulin-treated patients. In addition, these studies may serve to stimulate longer term assessments of macroangiopathy in the increasing number of patients with functioning pancreatic allografts draining into the systemic circulation.

Influence of portal delivery of insulin on intracellular glucose and lipid metabolism.

We have investigated whether portal delivery of insulin as a result of intrahepatic islet cell autografts would prevent the development of metabolic alterations. Seven pancreatectomized dogs received islet autografts transplanted into the liver through the portal vein (PD). One year after transplantation, their intravenous glucose tolerance and insulin responses were similar to age-matched control (C) dogs (n = 5). Also, normal triglyceride content in arterial smooth muscle and striated muscle was observed in the dogs with portal insulin delivery in contrast to the substantial increases we observed in pancreatectomized dogs (n = 7) with pancreatic autografts that drained into the systemic circulation (SD). In these dogs, the tissue samples were taken at the age of 3 to 4 years. Triglyceride content (mean +/- SEM) in the aorta was 4.9 +/- 1.2 versus 2.6 +/- 0.6 versus 20.7 +/- 8.0 mumol/g (P less than .01) in C, PD, and SD models, respectively. The corresponding values for triglyceride content in striated muscles were 29.1 +/- 1.2, 25.9 +/- 1.5, and 171.4 +/- 46.6 mumol/g (P less than .01). Glucose-6-phosphate dehydrogenase (G-6-PDH) and malic enzyme, key enzymes for lipid synthesis, were also normal in the PD model, in contrast to the fivefold increased activity of these enzymes in the SD model (P less than .01). The glycolytic enzymes, hexokinase (HK) and phosphofructokinase (PFK), were normal compared with the decreased values in the SD. These data indicate that it is possible to normalize glucose and lipid metabolism in arterial walls by portal delivery of insulin, following intrahepatic islet cell transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Determination of insulin specific IgE in serum of diabetic patients by solid-phase radioimmunoassay.

A solid-phase assay system for quantitative measurement of insulin specific IgE has been developed. Insulin specific IgE and IgG are bound to insulin covalently coupled to Sepharose particles. After a washing procedure which removes unbound immunoglobulins, 125I-anti-human IgE-rabbit globulin is added to the Sepharose to determine the amount of bound IgE. The use of standardized 125I-anti-human-IgE-globulin permits quantitation against a calibration curve of IgE and expression as units/ml. No cross-reactivity of IgG was found. Insulin specific IgE was determined in the sera of diabetic patients. Patients treated with porcine or mixed species purified insulin (monocomponent MC) did not differ significantly from a non-diabetic control group, whereas serum samples taken from patients treated with crystallized insulin preparations showed a significantly higher level of insulin specific IgE (p less than 0.05). Twenty-four patients with generalized insulin allergy and eight patients with immunological insulin resistance also had considerably higher values of IgE antibodies than the control group (p less than 0.001 and p less than 0.005, respectively). No correlation was found between the concentration of insulin specific IgE and IgG in individual sera and the level of insulin specific IgE was independent of the total IgE. In all cases of allergy elicited by purified insulin (monocomponent MC), it was ascertained that the diabetic patients in question had received less pure insulin during earlier treatment.

Metabolism in ischemic muscles before and after treatment with glucose-insulin-potassium infusion.

Arteriosclerosis, arterial thrombosis and emboli in the lower extremities of man result in metabolic disorders in the muscles due to a deficit between oxygen required and oxygen made available. Furthermore, diminished perfusion pressure results in diminished exchange of substrates and electrolytes across the capillary walls. In the muscle cells there is a depression of glycolytic enzyme function and a stimulation of lipid activity, resulting in accumulation of free fatty acids and acidosis within the cells. In order to increase R.Q. in the muscles in question, infusion of glucose-insulin-potassium were installed via a catheter introduced into the superior vena cava for 3 days. Following this, muscle samples showed significant increase of carbohydrate metabolism as compared to lipid metabolism and nearly normalization of intracellular content of free fatty acids. This was accompanied by improvement of the clinical condition of the patients and loss of pain in the extremities affected.

Activity of enzymes of glucose and triglyceride metabolism in adipose and muscle tissue from normal pregnant women at term.

In order to further investigate insulin insensitivity in pregnancy, the activities of key enzymes in glycolysis and lipid metabolism were measured in adipose and muscle tissue biopsies from 20 normal pregnant women undergoing caesarean section at term, and 23 non-pregnant women of similar age and body weight undergoing gynaecological surgery. The activity of pyruvate kinase was decreased in pregnant women in both adipose tissue (0.015 (0.009-0.024) (median and range) vs 0.020 (0.009-0.038) Ug-1 wet weight, p less than 0.05) and muscle tissue (6.7 (3.6-10.9) vs 12.0 (2.8-16.2) U g-1 wet weight, p less than 0.001). The activity of hexokinase was decreased in adipose tissue only (0.045 (0.022-0.085) vs 0.057 (0.025-0.097) U g-1 wet weight, p less than 0.05), while the activity of phosphofructokinase was decreased in muscle tissue only (1.3 (0.7-2.6) vs 2.1 (0.3-4.5) U g-1 wet weight, p less than 0.01). Glucose-6-phosphate dehydrogenase activity was increased in muscle tissue (0.30 (0.11-0.59) vs 0.17 (0.09-0.48) U g-1 wet weight, p less than 0.05), while the activity of hydroxyacyl-CoA dehydrogenase was decreased in adipose tissue (0.5 (0.3-1.1) vs 1.0 (0.5-2.3) U g-1 wet weight p less than 0.001) from the pregnant women. Similar results were found when enzyme activities were calculated per gram of protein, but with poorer reproducibility.(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta and muscle metabolism in pigs with peripheral hyperinsulinaemia.

Peripheral hyperinsulinaemia usually found in conventionally treated Type 1 (insulin-dependent) diabetic patients may have deleterious metabolic effects. We have used a hyperinsulinaemic model to examine intermediary metabolism in two key peripheral tissues, aorta and muscle. Nine pigs were immunized with crystalline insulin. Subsequently, they showed an insulin-binding capacity of 86.2 +/- 25.0 pmol/l and fasting total serum insulin of 3.9 +/- 3.1 nmol/l (control range 0.034-0.072 nmol/l), impaired glucose tolerance after oral glucose tolerance testing, significantly elevated levels of peripheral venous serum free insulin and C-peptide, and increased mean post-prandial free insulin/glucose ratios. The immunized pigs showed marked elevation of aorta and muscle triglycerides compared with control pigs (n = 15) but similar levels of non-esterified fatty acids. The glucose-6-phosphate-dehydrogenase, malic enzyme and 3-hydroxyacyl-CoA-dehydrogenase activities were all increased significantly (by 50%-300%) in both aorta and muscle. Phosphofructokinase was decreased in both tissues. Hexokinase was increased in muscle alone whereas pyruvate kinase was significantly decreased in aorta. Glyceraldehyde-3-phosphate dehydrogenase activity was not significantly different in aorta and muscle. Thus in insulin immunized pigs with normal beta-cell function and pronounced peripheral hyperinsulinaemia there was increased peripheral lipogenic activity. These findings have potentially important implications with regard to macrovascular disease in diabetes.

Intracellular metabolism in biopsies from the aorta in patients undergoing coronary bypass surgery.

Abnormal glucose and lipid metabolism in striated muscles and arterial wall has been demonstrated in 3 species: the pig, the dog, and human Type 2 diabetic patients, sharing the common feature of peripheral hyperinsulinaemia. In this study eighteen consecutive patients undergoing coronary bypass surgery and eight control patients were examined. Prior to surgery an oral glucose tolerance test showed that eleven out of eighteen patients had impaired glucose tolerance and significantly elevated fasting immune reactive insulin (IRI) and C-peptide concentrations. There was a statistically significant correlation between the 2 hour blood glucose value and the fasting plasma insulin level (R = 0.55, p less than 0.05). During the operation, aortic and muscle biopsies were taken. The eighteen patients undergoing coronary bypass surgery showed disturbances in glucose metabolism, i.e. decreased activity of glycolytic enzymes (hexokinase 0.30 +/- 0.06 versus 0.40 +/- 0.06 U/g, p less than 0.001, and phosphofructokinase 0.48 +/- 0.09 versus 0.61 +/- 0.07 U/g, p less than 0.01). Malic enzyme activity was increased in all patients (0.17 +/- 0.03 versus 0.06 +/- 0.02 U/g, p less than 0.001). Glucose-6-phosphate dehydrogenase was increased in the eleven patients with impaired glucose tolerance (0.55 +/- 0.10 versus 0.30 +/- 0.07, p less than 0.01) parallel to a significant increase in triglyceride content in the aortic wall (16.1 +/- 4.8 versus 3.7 +/- 3.2 mumol/g, p less than 0.01) as well as in the striated muscles (374 +/- 44 versus 48 +/- 6 mumol/g, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Contribution of muscle and liver to glucose-fatty acid cycle in humans.

To examine the influence of elevated free fatty acid (FFA) levels on hepatic glucose production (HGP) and oxidative and nonoxidative pathways of glucose metabolism, 12 healthy subjects participated in two euglycemic insulin-clamp studies performed with and without infusion of Intralipid plus heparin. To elucidate the role of skeletal muscle in this putative interaction, we performed muscle biopsies for the measurement of activities of glycogen synthase (GS), pyruvate dehydrogenase (PDH), and carnitine palmitoyltransferase (CPT). Infusion of Intralipid plus heparin caused an increase in plasma FFA concentrations and rate of lipid oxidation (measured by indirect calorimetry) that was not inhibited by insulin. Suppression of HGP by insulin was impaired by elevated plasma FFA levels. Furthermore, the increase in plasma FFA was associated with a 20% reduction in total glucose metabolism (P < 0.01), which was completely accounted for by a reduction in the rate of glucose oxidation. Although the fractional activity of GS was increased by insulin, elevation of plasma FFA had no influence on this key enzyme of glycogen synthesis. In addition, the activities of PDH and CPT were uninfluenced by the elevation of FFA, suggesting that oxidative processes in skeletal muscle were not a major target for the operative glucose-fatty acid cycle under the current conditions. Taken together, the data indicate that the interaction between FFA and glucose metabolism also involves impaired suppression of HGP by insulin.

Carbohydrate and lipid metabolism of skeletal muscle in type 2 diabetic patients.

Peripheral hyperinsulinaemia is the cause of metabolic changes that might contribute to the high incidence of macrovascular disease in patients with diabetes mellitus. In order to test this hypothesis muscle biopsies from 12 Type 2 diabetic patients and 14 age and sex matched non-diabetic patients, undergoing minor surgery, were obtained. The diabetic patients had significantly elevated fasting serum insulin (0.29 +/- 0.05 vs 0.06 +/- 0.03 nmol-1) and glucose (8.3 +/- 1.5 vs 4.6 +/- 0.5 mmol-1) and HbA1 levels (8.4 +/- 0.4 vs 5.0 +/- 0.2 per cent). The fasting and 2-h postprandial C-peptide levels were 0.99 +/- 0.25 vs 0.39 +/- 0.12 and 3.12 +/- 0.75 vs 1.09 +/- 0.34 nmol/l, respectively. The diabetic patients showed a marked elevation of triglyceride in the striated muscle biopsies compared to the non-diabetic controls (290 +/- 52 vs 48 +/- 6 mumol/g wet weight, p less than 0.001). Moreover, the activities of glucose-6-phosphate dehydrogenase (0.25 +/- 0.03 vs 0.13 +/- 0.01 U/g wet weight) and malic enzyme (0.15 +/- 0.01 vs 0.05 +/- 0.01 U/g wet weight), necessary for lipid synthesis, were significantly increased (both p less than 0.001) in the diabetic patients while the glycolytic enzymes, hexokinase (0.65 +/- 0.09 vs 1.82 +/- 0.11 U/g wet weight), pyruvate kinase (7.3 +/- 0.9 vs 13.2 +/- 0.9 U/g wet weight), phosphofructokinase (1.3 +/- 0.2 vs 2.6 +/- 0.2 U/g wet weight), and alpha-glycerophosphate dehydrogenase (7.3 +/- 0.5 vs 12.5 +/- 0.7 U/g wet weight) were decreased (all p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)