Characterization of circulating insulin and proinsulin-binding antibodies in autoimmune hypoglycemia.

Five patients with fasting and(or) postprandial hypoglycemia were found to have insulin antibodies in the absence of previously documented immunization. Studies on the equilibrium-binding of insulin to the autoantibodies revealed two classes of binding sites with association constants and binding capacities analogous to those of insulin antibodies from insulin-treated diabetic patients. Similarly, no consistent differences in these parameters were found in both groups of patients with insulins of bovine, porcine, and human origin. Proinsulin (C-segment directed) antibodies capable of binding bovine or porcine proinsulin were present in 10 of 10 and 9 of 10 insulin-treated diabetics serving as controls, respectively, and, when present, provide incontrovertible evidence of exogenous insulin administration. No such antibodies could be detected in the hypoglycemic patients with autoimmune insulin antibodies. The kinetics of dissociation of the insulin-antibody complexes were consistent with the existence of two classes of antibody sites. The corresponding dissociation rate constants were large enough to predict that significant amounts of free hormone may be generated by this mechanism and provide a plausible pathogenesis for the hypoglycemia in these patients.

A pilot study of the continuous glucose monitoring system: clinical decisions and glycemic control after its use in pediatric type 1 diabetic subjects.

OBJECTIVE: To determine whether the continuous glucose monitoring system (CGMS) (MiniMed, Sylmar, CA) could be used to make clinical decisions and whether it has an impact on glycemia in pediatric type 1 diabetic subjects. RESEARCH DESIGN AND METHODS: Pediatric subjects were recruited if they had HbA(1c) >8.0% with management problems (n = 35) or episodes of severe or nocturnal hypoglycemia or hypoglycemia unawareness associated with HbA(1c) < or =8.0% (n = 12). A total of 47 patients with a mean HbA(1c) value of 8.6 +/- 1.6% (mean age 11.8 +/- 4.6 years, youngest 2.7 years, and diabetes duration 5.5 +/- 3.5 years) on three to four insulin injections/day (n = 24) or insulin pump therapy (n = 23) were followed with the CGMS for a mean of 69.5 +/- 28 h. Comparisons were made between the number of high (>150 mg/dl) and low (<70 mg/dl) glucose patterns discerned with the sensor or the logbook, and HbA(1c) levels were evaluated. RESULTS: In patients on injection therapy, 30 high or low glucose patterns were discerned with the logbook records and 120 patterns with the CGMS. Specific alterations of the diabetes regimen were made. An overall significant change in HbA(1c), from 3 months before wearing the sensor to 6 months after (analysis of variance 0.04), was found in the subjects. Post hoc analysis showed a significant change in HbA(1c) from 8.6 +/- 1.5% at baseline to 8.4 +/- 1.3% at 3 months (paired Student's t test 0.03). CONCLUSIONS: The CGMS can be used by pediatric patients to detect abnormal patterns of glycemia. The information that was obtained could be used to alter the diabetes regimen and impact glycemic outcome.

Clinical, endocrinological, and enzymatic characterization of two patients with 5 alpha-reductase deficiency: evidence that a single enzyme is responsible for the 5 alpha-reduction of cortisol and testosterone.

Two siblings with 46,XY male pseudohermapthroditism were demonstrated to have the phenotype characteristic of 5 alpha-reductase deficiency, namely normal testes and male Wolffian duct derivatives (epididymis, vas deferens, and seminal vesicle) terminating in a blind-ending vagina. Clitoromegaly was present at birth and increased further at the time of expected puberty. The diagnosis of 5 alpha-reductase deficiency was confirmed by demonstration of male levels of testosterone and testosterone precursors before and after hCG administration, elevated plasma testosterone to dihydrotestosterone and urinary etiocholanolone to androsterone ratios, and by in vitro studies indicating 5 alpha-reductase enzyme deficiency in the epididymis of one patient. Studies of control and mutant epididymal microsomes indicated that a single enzyme is responsible in the normal person for the 5 alpha-reduction of testosterone and cortisol (and probably other delta 4-3-ketosteroids as well) and that 5 alpha-reductase activity is undetectable for all substrates examined in the mutant. This finding explains why the formation of 5 alpha-reduced glucocorticoids is also defective in the disorder.

Cellular senescence, radiation damage to mitochondria, and the compensatory response in ripening pear fruits.

A compensatory response, viz. in vivo recovery from radiation damage to mitochondria, occurs in preclimacteric pear fruits (Pyrus communis L.) treated with ionizing radiation. The compensatory response is absent or markedly impaired in senescent fruits irradiated at or near the climacteric peak. Senescent cells failed to recover from harmful effects of radiation on: 1) mitochondrial yield, 2) in vivo incorporation of amino acids into mitochondrial protein, and 3) mitochondrial respiratory control and ADP/O. A diminished response to "split-dose" irradiation and a delayed rate of recovery confirmed the degeneracy and loss of compensatory power with cell age.A loss of restorative activity, especially in mitochondria that supply the cell with essential energy, may underlie the more obvious signs of cumulative stress that accompany cellular senescence. Use of ionizing radiation as an investigative tool and the molecular implications of radiation damage, recovery, and cellular senescence are discussed.

Insulin pump therapy in type 1 pediatric patients: now and into the year 2000.

There are a number of medical conditions such as growth failure in children, pregnancy, lipid abnormalities, and early complications that are improved by the meticulous glycemic control that can be achieved with insulin pump therapy (CSII). By using an insulin pump, many patients with severe hypoglycemia, the dawn phenomenon, extremes of glycemic excursion, recurrent diabetic ketoacidosis (DKA) and hypoglycemia unawareness have amelioration of these problems. However, pump therapy involves problems such as weight gain, recurrent ketosis due to pump failure, infections, and risk of hypoglycemia. Owing to many developmental issues, young children may not be able to wear the pump without parental supervision. We have used the pump at night time only in these patients. This has allowed children of 7-10 years of age to benefit from improved nocturnal glycemia without the risk of pump therapy when they are without an adult to help. We have also used the pump in subjects with recurrent DKA and in our general patient population (mean age 13.6+/-3.9 years). In our pump cohort, CSII led to improvement in quality of life, knowledge, adherence, and responsibility. A reduction in hypoglycemia, DKA rate and mean HbA(1c) was associated with pump usage. For this to occur, however, pump education must be geared to the pediatric subject and his/her family. Education materials and tools help in learning how to use the pump and how to deal with the intricacies of basal and bolus dosing, and the effect of exercise, food and illness on diabetes management. The pump has improved since it was first introduced and these modifications have made it easier, more painless and less hazardous. With the development of continuous glucose sensors and implantable pumps, the next century will see pump therapy lead to the artificial pancreas.

Y-derived sequence detected in minute chromosomes by polymerase chain reaction and in situ hybridization.

A 10-year-old girl and a 10-month-old girl, both with ambiguous genitalia, were found to have 45,X/46,X,mar and 45,X/46,X,r(?) mosaicism. The marker chromosomes in both girls were very small. Polymerase chain reaction, with synthetic oligonucleotide primers from Y-specific DNA sequences pY-80 and pY53.3 containing the sex-determining region Y(SRY), proved the marker chromosomes to contain the Y short arm material. In situ hybridization with probe pY-80 confirmed that the marker chromosomes included the Y short arms. These findings, together with ambiguous genitalia in the girls, indicate that the marker chromosomes include the testis-determining factor gene.