Hulda J Wohltmann

Plasma lipids and lipoproteins in young insulin-dependent diabetic patients: relationship with control.

SummaryPlasma and lipoprotein cholesterol and triglycerides, glucose and haemoglobin A1c concentrations were measured in 106 patients (56 males) with insulin-dependent diabetes mellitus (age range 2–22 years) and 36 normal volunteers (19 males) with similar age and sex distribution. The diabetic patients were further divided into three subgroups: “good”, fair and poor control, based on 24 h glycosuria and haemoglobin A1c concentrations. Total, low density lipoprotein and very low density lipoprotein cholesterol levels were significantly increased in male patients in poor control when compared with the group in “good” control and with normal subjects. Triglyceride and very low density lipoprotein triglyceride levels were also significantly increased in poorly controlled males. The most significant difference however was a decrease of high density lipoprotein cholesterol in male patients in poor control. There was a significant inverse correlation between haemoglobin A1c and high density lipoprotein cholesterol (r = -0.63) and a direct correlation between haemoglobin A1c and low density lipoprotein cholesterol (r = 0.35) and triglycerides (r = 0.62) in the male diabetics. The findings were similar in females. The most striking change was observed in low density lipoprotein cholesterol levels, which were more markedly increased in poorly controlled females than in poorly controlled males. No statistical singificant differences were found between the groups in good and fair control for any of the plasma and lipoprotein lipids studied. A significant difference however was found between the groups in poor and fair control. There was a significant correlation in females between haemoglobin A1c and low density lipoprotein cholesterol levels (r = 0.43), haemoglobin A1c and triglycerides levels (r = 0.54) and an inverse correlation between haemoglobin A1c and high density lipoprotein cholesterol (r = -0.59).

Surface binding, internalization and degradation by cultured human fibroblasts of low density lipoproteins isolated from Type 1 (insulin-dependent) diabetic patients: Changes with metabolic control

SummaryA previous study of low density lipoprotein metabolism by cultured cells focused on the metabolism of normal lipoproteins in vitro by fibroblasts isolated from diabetic patients. No abnormalities were found. We have followed the opposite approach. Using normal human fibroblasts as test cells we compared the metabolism in vitro of low density lipoproteins isolated from diabetic patients before and after metabolic control. We found a significant decrease (p<0.02) in internalization and degradation of low density lipoproteins isolated from diabetic patients before metabolic control when compared with those isolated from normal control subjects or from the same patients after metabolic control. The observed changes were mainly apparent in intracellular degradation. To evaluate whether the observed differences in low density lipoprotein behaviour were correlated with lipid or apolipoprotein composition, we measured cholesterol, triglyceride, apolipoprotein B and total protein levels in the low density lipoproteins tested. A significant decrease (p<0.05) of the triglyceride/protein ratio was found in post-control low density lipoproteins suggesting that a high triglyceride content may interfere with low density lipoprotein metabolism. The present study represents the first observation that metabolic control in diabetes mellitus can alter low density lipoprotein-cell interaction and suggests a possible mechanism for the enhanced incidence of atherosclerosis in diabetic patients.

Bartter's Syndrome: Urinary Prostaglandin E-like Material and Kallikrein; Indomethacin Effects

The urinary excretions of prostaglandin E-like material (iPGE) and kallikrein were measured in two children with Bartters syndrome. Urinary iPGE excretion was three and 10 times greater than normal, and urinary kallikrein was five and 10 times greater than normal in the two subjects. Furthermore, excretions of iPGE and kallikrein were highly correlated (P less than 0.005) with each other before and during treatment with indomethacin, a prostaglandin synthetase inhibitor. Indomethacin significantly (P less than 0.001) reduced urinary iPGE, urinary kallikrein, and plasma renin activity, while increasing the sensitivity to intravenous angiotensin II and the serum potassium to normal. The results confirm that renal prostaglandins may be involved in the pathogenesis of Bartters syndrome and suggest that renal prostaglandins and the kallikrein-kinin system are linked.

Platelet Function During Continuous Insulin Infusion Treatment in Insulin-dependent Diabetic Patients

Patients with diabetes mellitus manifest increased in vitro platelet aggregation andincreased synthesis of the proaggregant and vasoconstrictor, thromboxane A2 (TXA2). We studied the effects of continuous insulin infusion treatment on platelet aggregation and arachidonic acid (AA)-stimulated platelet TXA2 synthesis (15 and 30 s post-AA, 1 mM) in 16 type I diabetic patients. Strict glycemic control was induced with the Biostator for 2 days and maintained for 12–14 days with continuous subcutaneous insulin infusion (CSII). The average premeal plasma glucose level (4/day) fell from 184 ± 15, before treatment, to 107 ± 6 mg/dl on the final day (P < 0.001). After control, platelet synthesis of TXA2, measured by radioimmunoassay of its stable metabolite, immunoreactive TXB2 (iTXB2), decreased in all patients (30 s: 276 ± 31 versus 199 ± 28ng iTXB2/ml/ 5 × 105 platelets; P < 0.05). The reductionin platelet iTXB2 synthesis (15 and 30 s) was greater in poorly controlled patients (HbA1c>12%; N = 8), and for all patients the decrease in iTXB2 (15 and 30 s) was correlated with the prestudy HbA1c level (15 s: r = 0.6; P < 0.01). In contrast, platelet aggregation responses did not improve during intensive insulin treatment. The ED50 for AA (dose producing 50% maximum aggregation at 1 min) was unchanged after 2 wk of treatment and the ED50 for aggregation induced by ADP fell significantly inpatients with HbA1c 12% (2.8 ± 1.3 versus 1.2 ± 0.6 μM; P < 0.01). Other factors that were associated in this study with platelet aggregation responses were plasma lipoprotein levels and microvascular disease. In all patients before treatment, the ED50 for AA was inversely correlated with the LDL-cholesterol level(r = 0.57; P < 0.01). Although platelet aggregation did not improve during the period of intensive treatment, when the relations of microvascular disease and glycemic control to platelet aggregation were analyzed together in all patients, the ED50 for AA was greatest (P < 0.02) in thosepatients without microvascular disease and HbA1c <12%, indicating less platelet aggregability. Thus, a brief period of CSII treatment reduced AA-stimulated platelet iTXB2 generation; however, the effects of this treatment on platelet aggregation appear to be complex and other extraplatelet factors also seem to influence the aggregation response.

Increased Platelet Arachidonic Acid Metabolism in Diabetes Mellitus

Platelets obtained from some diabetic patients show enhanced in vitro platelet aggregation. This study sought to determine if platelets obtained from insulindependent diabetic subjects synthesize increased quantities of the labile aggregating substance, thromboxane A2 (TXA2), and if it may play a role in the enhanced platelet aggregation. Arachidonic acid (1 mM)-stimulated TXA2 synthesis, as determined via radioimmunoassay of its stable metabolite TXB2, was significantly greater (P < 0.01, N = 12) in platelet-rich plasma obtained from diabetics compared with matched controls. Arachidonic acid-stimulated TXB2 synthesis in the diabetic platelet-rich plasma was positively correlated with the ambient fasting plasma glucose (r = 0.61, P < 0.02, N = 15). Platelet aggregation induced by arachidonic acid (0.4–0.8 mM) was inhibited significantly less by 13-azaprostanoic acid (P < 0.04, N = 14), a competitive antagonist of the actions of prostaglandin H2 or TXA2 on platelets, compared with matched controls. The results support the notion that platelets obtained from some insulin-dependent diabetic subjects manifest increased synthesis of TXA2, which may contribute to the enhanced platelet aggregation.

Soluble immune complexes in patients with diabetes mellitus: detection and pathological significance

SummaryA series of 148 diabetic patients were studied for the presence of soluble immune complexes using five different screening techniques. The percentage of positive results was 26% with direct nephelometry and PEG-C4, 27% with PEG-IgG, 33% with radiolabelled Clq binding and 57% with a specific technique for detection of insulin-anti-insulin immune complexes. The percentages of positivity in a group of 40 healthy donors were 2.5% for direct nephelometry and radiolabelled Clq binding, 5% for the PEG-C4 technique, and 10% for the PEG-IgG technique. Sixteen percent of the patients studied had positive results in three or more of the screening tests. When the results of the different screening tests in all patients and controls were compared among themselves, we found correlation coefficients between-0.01 (p = 0.854) when the direct nephelometry and the PEG-C4 tests were compared and 0.29 (p < 0.0003) when the direct nephelometry and PEG-IgG tests were compared. When the results of each test for the whole group of patients and the group of normal healthy donors were compared, significant differences were found for direct nephelometry (p = 0.004), PEG-IgG, PEG-C4, and insulin-anti-insulin immune complexes (p < 0.0001), as well as for anti-insulin antibodies (p < 0.001); no significant difference was observed when the results of radiolabelled Clq binding in diabetics and controls were compared (p = 0.2). Significant correlations were found between the results of several screening tests for soluble immune complexes, insulin dosage, and clinical or biochemical expressions of microangiopathy, nephropathy, or vasculopathy. These correlations were more consistent when we divided the patients into normal or abnormal groups for proteinuria, microangiopathy, and diabetic complications and considered the number of positive tests in each patient rather than the results of individual tests.

Influence of Glycemic Control on Interaction of Very-Low- and Low-Density Lipoproteins Isolated From Type I Diabetic Patients With Human Monocyte-Derived Macrophages

The VLDL and LDL fractions were isolated from 29 patients with type 1 diabetes at the time of admission to the hospital to restore glycemic control and again at discharge. These lipoprotein fractions were incubated with human monocyte-derived macrophages, and the rates of macrophage CE synthesis were determined. The rates of CE synthesis in human macrophages were significantly greater (P < 0.005) when incubated with VLDL isolated from type I diabetic patients before compared with after glycemic control was attained and averaged 1.84 ± 0.52 and 1.09 ± 0.27 nmol (1.20 ± 0.34 and 0.71 ± 0.18 μg) [14C]cholesteryl oleate synthesized mg cell protein−1 · 20 h−1 respectively. In contrast, when LDL isolated from the same patient during the same period was incubated with human macrophages, the rates of cellular cholesteryl ester synthesis did not differ significantly and averaged 4.23 ± 1.26 and 3.91 ± 0.96 nmol (2.75 ± 0.82 and 2.55 ± 0.63 μg) [14C]cholesteryl oleate synthesized · mg−1 cell protein · 20 h−1, respectively. There was a significant increase in the total cholesterol content of VLDL isolated before glycemic control compared with that isolated after glycemic control was attained (P < 0.05) resulting from a significant increase in the FC and CE (P < 0.05) contents of these VLDL particles. There was a significant decrease in the ratio of FC to PL in VLDL, but not LDL, isolated after glycemic control (P < 0.05). The percentage of apoE in VLDL was significantly decreased (P < 0.05) after glycemic control was attained. In LDL isolated after glycemic control was achieved, a significant decrease (P < 0.005) in the percentage of triglycerides was observed. In addition, there was a significant decrease (P < 0.0001) in the extent of glycation of LDL isolated after glycemic control. These studies suggest that during periods of poor glycemic control, the composition of VLDL isolated from type 1 diabetic patients is altered. These modified VLDLs stimulate CE synthesis rates in human macrophages and, thus, may contribute to the increased prevalence of atherosclerosis in diabetic patients.

Predicting Insulin Requirements for a Portable Insulin Pump Using the Biostator: Evidence for Reversible Insulin Resistance in Poorly Controlled Type I Diabetics

Glycemie control was achieved in 14 patients with insulin-dependent diabetes mellitus (IDOM) by 36–48-h treatment with a recently marketed clinical model, Biostator glucose controller (Life Science Instruments, Miles Laboratories, Elkhart, Indiana). Control was maintained by continuous subcutaneous insulin infusion with a portable pump, programmed using infusion profiles from the Biostator. Control of glycemie excursion with the Biostator was variable among patients. This control, reflected by the M-value or a blood glucose index (mean of pre-, peak, and 2-h postmeal levels for four meals) of each patient, correlated directly with their prior glycemie control, as assessed by hemoglobin A1c (HbA1c) level (r = 0.66, P < 0.01 and r = 0.82, P < 0.005, for M-value and blood glucose index, respectively). Total insulin infused by the Biostator/24 h overpre-dicted the subcutaneous infusion dose required on day 2 of pump treatment (183 ± 11%, P < 0.001). Therefore, these data were not used to program the portable pump. Instead, total insulin dose was estimated using a dietary glucose/insulin (G/l) ratio. This ratio, derived from dietary total available glucose, urine glucose, and insulin dose/24 h during depot insulin treatment, accurately estimated total insulin for pump infusion (97 ± 4%). The basal infusion rate of the Biostator between 2400 and 0600 h also exceeded the subcutaneous infusion requirement and was reduced to 40% for the initial pump basal rate. The remainder of the insulin (total minus basal) was distributed as premeal boluses according to the Biostator infusion profile for meals. This initial distribution (%) of premeal insulin correlated well with that eventually needed for optimal control with infusion pump treatment (r = 0.88, P < 0.001). The insulin regimens derived resulted in average premeal plasma glucose levels of 113 ± 5.9 mg/dl on day 2 of pump treatment. During 5–10 days of continued infusion pump treatment, the insulin dose needed to maintain blood glucose control decreased in the group as a whole. This decrease was primarily due to the dose reductions seen in patients who were in poor glycemie control before study. The decrease (%) in insulin dose in patients with HbA1c > 11% was 31.3 ± 4.1% (P < 0.001) compared with 8.6 ± 4.9% in patients with HbA1c < 11% (P = NS). In all patients, the change in insulin requirements (%) correlated with their initial HbA1c level (r = 0.72, P < 0.05). Glycemie control did not change significantly during this period. Our study supports the coordinated use of closed-and open-loop insulin delivery systems. The Biostator infusion profiles are helpful in programming meal insulin distribution for the portable infusion pump. However, with the algorithms we used, the Biostator significantly overestimates total and basal insulin needs for subcutaneous infusion. The correlation between initial HbA1c levels and glycemie control on the Biostator as well as the relationship of HbA1c to the subsequent decrease in insulin requirements during pump treatment suggest that patients with poorly controlled IDDM are insulin resistant, and that this improves with strict glycemie control.

Specificity of the Effect of Insulin on Permeability of Frog Sartorius Muscles to Sugar

The permeability of isolated frog sartorius muscles to 3-O-methylglucose is increased by low concentrations of insulin, but is relatively insensitive to a variety of other peptides and proteins, many of which have been reported to enhance the uptake and metabolism of glucose by rat hemidiaphragms or adipose tissue in vitro. ACTH, growth hormone, oxytocin, vasopressin and the separated chains of oxidized insulin and of insulin S-sulfonate did not alter the permeability of frog muscles to sugar when tested either alone or together with a submaximal concentration of insulin. These substances were able to retard the degradation of I-131 insulin by frog muscle extracts, but, in contrast to the situation for rat hemidiaphragms, media that had been used for incubation of frog sartorius muscles exhibited only a barely detectable ability to degrade I-131 insulin. The results suggest that some of these peptides may augment the effect of insulin on rat hemidiaphragms by diminishing the rate of degradation of insulin in the medium. Glucagon increased the permeability of frog muscles to sugar, but this effect seemed to be attributable to contamination of the preparation with insulin. Prolactin, TSH and epinephrine augmented permeability to 3-methylglucose when used at concentrations that were higher than those ordinarily found in plasma.

Leydig cell tumor in identical twin.

A case is presented of an identical twin who had an interstitial cell tumor of the testis removed, and comparison is made with his identical brother over an ensuing six-year period. The dramatic effects of the interstitial cell tumor are clearly shown in the comparison of the two males over this six-year period. To our knowledge this is the only such case in the world literature.