The effect of FK506 on glycemic response as assessed by the hyperglycemic clamp technique.

We studied seven nondiabetic subjects with the autoimmune diseases psoriasis, multiple sclerosis, and primary biliary sclerosis who were to receive FK506 as experimental immunotherapy. All subjects underwent two standard oral glucose tolerance tests and two 180-min hyperglycemic clamps immediately before and 10 weeks after starting FK506. There was no significant difference in weight or HbA1c pre- vs. post-FK506 treatment. FK506 levels were therapeutic and non-toxic (0.1-1 ng/ml) for all subjects studied. Repeated measures analysis of variance for interaction between time and treatment was performed on insulin (after outlier removed) and glucose values from the OGTT. There was neither time-by-treatment interaction, nor a treatment effect (P > 0.1). There were no significant differences in pre- vs. post-FK506 treatment values of plasma glucose during the hyperglycemic clamp mean acute insulin response to glucose (AIRG) 164 +/- 38 pmol/L vs. 148 +/- 46 pmol/L (P > 0.1); mean incremental area under the insulin curve (IAUC) during the first 10 min of the study, 473 +/- 109 pmol/L vs. 443 +/- 146 pmol/L (P > 0.1); total area under the insulin curve (TAUC) during the first 10 min of the study, 786 +/- 152 pmol/L vs. 781 +/- 18 pmol/L (P > 0.1); mean glucose infusion rate (GIR) 37.7 +/- 5.0 mumol/kg/min vs. 33.3 +/- 4.4 mumol/kg/min (P > 0.1); or mean insulin sensitivity index (ISI), 3.05 +/- 0.4 vs. 3.13 +/- 0.5 (P > 0.1). Mean steady-state insulin secretion (SSI) was significantly lower 244 +/- 43 pmol/L vs. 200 +/- 25.2 pmol/L (P = 0.03). Peak first-phase insulin secretion values of 321 +/- 62 pmol/L vs. 263 +/- 57 pmol/L approached significance (P = 0.07). No patient progressed to diabetes during the study. FK506 decreased steady-state insulin secretion during the last 60 min of the clamp, regardless of initial glucose tolerance. Insulin sensitivity and glucose infusion rate did not change in the group as a whole with FK506 treatment.

Meningioma in congenital adrenal hyperplasia.

A diversity of malignancies have been reported in patients with congenital adrenal hyperplasia. We report a case of multiple meningiomas, tumors which are more common in females and reported to have sex steroid receptors, in a 46,XX male (severe female hermaphrodite raised as a male) with 21-hydroxylase deficiency. The patient has been treated with glucocorticoids since 3 years of age and testosterone since puberty.

Simultaneous assessment of insulin secretion and insulin sensitivity using a hyperglycemia clamp.

A hyperglycemic clamp is an established method to assess insulin secretion and is generally used only for this purpose. To determine whether it could also be used to assess insulin sensitivity, we compared insulin sensitivity indices (ISI) obtained during euglycemic and hyperglycemic clamp experiments in 22 nonobese volunteers (body mass index, 23.9 +/- 0.6 kg/m2) and in 20 obese individuals (body mass index, 30.8 +/- 1.3 kg/m2) matched for age and gender. The ISI values (micromoles per kg.min/pmol) of the obese group assessed during hyperglycemic (0.088 +/- 0.011) and euglycemic (0.050 +/- 0.005) clamp experiments were both significantly lower than the ISI of the nonobese group assessed in hyperglycemic and euglycemic clamp experiments (0.179 +/- 0.024 and 0.096 +/- 0.009, respectively; both P less than 0.01). Although the ISI values obtained with hyperglycemic clamps were consistently greater than those obtained with euglycemic clamp (0.137 +/- 0.016 vs. 0.075 +/- 0.007; P less than 0.001), they were highly correlated (r = 0.84; P less than 0.0001). Moreover, when these indices were converted to clearance rates, thereby correcting for the mass action effects of glucose on glucose disposal, the values obtained with the hyperglycemic clamp (0.0137 +/- 0.0016 mL/kg.min/pmol) were statistically identical to those obtained with the euglycemic clamp (0.0142 +/- 0.0013 mL/kg.min/pmol), as indicated by a regression equation having an intercept of 0 and a slope (1.03) not different from 1. We, therefore, conclude that the hyperglycemic clamp and the euglycemic clamp yield comparable estimates of insulin sensitivity and that, under appropriate conditions, the hyperglycemic clamp technique may be used to assess both insulin sensitivity and insulin secretion in the same individual in a single experiment.

The accuracy of blood glucose testing by children.

While studies have evaluated the accuracy of adult patients and health personnel in reading various glucose oxidase impregnated strips to estimate blood glucose, there are no studies exclusively evaluating the accuracy of children with diabetes reading their own strips as compared to a staff member, and meter to meter variability in reading these strips. We evaluated the accuracy of reading chemstrip bG by children at a summer camp. The children's visual readings of their own strips were compared to the visual reading of a single staff member. A total of 356 Chemstrip bG's were visually read by diabetic children and a single trained staff member at a summer camp for diabetics. The strips were then analyzed by two Accu-Chek bG meters. Intermachine variability was found to be negligible over the entire bG range. For the purposes of this study, we define accurate visual readings as those within +/- 15 percent of the meter reading of a given strip. At low bG values (40-79 mg/dl), accuracy by children and staff is low, with underestimating occurring in 39 percent of staff readings and 57 percent of children's readings. At intermediate bG values (120-239 mg/dl) readings are more accurate, especially when read by the staff, with misreadings occurring in only 16-19 percent of the strips. At high bG values (240-399 mg/dl), accuracy by children is decreased, with underestimation 500 percent more often than staff. We conclude that children are less accurate at reading Chemstrip bG than a trained staff member (51% versus 33% misreading), especially at the upper and lower ranges of bG values when visual readings are least accurate, and the need for therapeutic intervention is the greatest.

Insulin effects on apolipoprotein B lipoprotein synthesis and secretion by primary cultures of rat hepatocytes.

Lipoprotein synthesis and secretion were examined in primary cultures of rat hepatocytes cultured on collagen-coated plates and incubated with pharmacologic and physiologic concentrations of insulin. Media insulin concentration declined rapidly over the course of incubation indicating that hepatocytes rapidly degrade insulin. When insulin was present in the media, cellular triglyceride accumulated while lipid secretion declined. Insulin inhibited the incorporation of labeled amino acids into total secretory lipoprotein apoproteins and apolipoprotein B (apo B) as well as apo B mass as measured by monoclonal radioimmunoassay. The effect of insulin on apo B secretion occurred as early as three hours after the addition of insulin to the culture media and both apo B of higher molecular weight (apo BH) and apo B of lower molecular weight (apo BL) were affected. Cellular apo B did not accumulate within cells. The majority of secretory lipid radioactivity synthesized from acetate was in VLDL density lipoproteins. The composition of newly synthesized lipids as assessed by thin layer chromatography was not significantly altered with insulin. These studies support the finding that insulin inhibits VLDL secretion by hepatocytes while at the same time stimulating overall triglyceride synthesis. A suggested mechanism is that insulin uncouples triglyceride and apo B synthesis, which influences subsequent lipoprotein assembly and secretory pathways. These results are consistent with the concept that postprandial insulin release inhibits hepatic lipoprotein secretion while intestinal lipoprotein metabolic pathways are most active.

In vitro malignant transformation of hamster retina by herpes simplex virus.

Hamster retina was infected in vitro with irradiated herpes simplex virus type 2. Cells underwent malignant transformation, and when injected subcutaneously into nude mice and hamsters, produced transferable tumors. Transformed cells were found to have HSV antigen as determined by indirect fluorescent staining. In addition, the undifferentiated transformed retinal cells possess neurosecretory granules and retinoic acid receptors and produce growth factor, features similar to those found in spontaneous human retinoblastoma. This is the first neoplasm of ocular tissues induced experimentally by herpes simplex virus (HSV).

Replication of a low-copy-number plasmid by a plasmid DNA-membrane complex extracted from minicells of Escherichia coli.

A DNA-membrane complex was extracted from minicells of an Escherichia coli mutant harboring a "miniplasmid" derivative (11.2 kilobases) of the low-copynumber plasmid RK2 (56 kilobases). The complex contained various species of supercoiled and intermediate forms of plasmid DNA, of which approximately 20% was bound firmly to the membrane after centrifugation in a CsCl density gradient. The plasmid DNA-membrane complex synthesized new plasmid DNA without the addition of exogenous template, enzymes, or other proteins. DNA synthesis appeared to proceed semi-conservatively, was dependent on the four deoxynucleoside triphosphates, partially dependent on ribonucleoside triphosphates, and was sensitive to rifampin, an antibiotic known to inhibit initiation of replication. Novobiocin and nalidixic acid also inhibited synthesis, as did the omission of ATP, N-Ethylmaleimide, an inhibitor of DNA polymerase II and III activity, but not DNA polymerase I activity, also partially inhibited the synthetic reaction, as did chloramphenicol. The plasmid DNA synthetic product was analyzed by alkaline sucrose and dye-CsCl gradient centrifugation, as well as by agarose gel electrophoresis. In each case, the product consisted of parental and intermediate forms of plasmid DNA. Some chromosomal DNA was also synthesized by a contaminating bacterial DNA-membrane complex, but this synthesis was rifampin insensitive and could be separated from plasmid DNA synthesis.