The importance of calcium ions forin vitro malignant hyperthermia testing

Intracellular Ca++ levels in skeletal muscle are elevated during the in vitro contracture response of muscle from subjects with malignant hyperthermia. The role of Ca++ in the bathing medium and the consequences of substitution of Sr++ for Ca++ in the response to agents associated with malignant hyperthermia were examined. When Ca++ was omitted from the bathing medium the contractures induced in human vastus lateralis by halothane (three per cent) or succinylcholine (50 mM) were reduced by 80 and 100 per cent, respectively, while contractures induced by caffeine (8 mM) were only reduced by 50 per cent. Substitution of Ca++ by another divalent cation, Sr++, completely restored contractures induced by caffeine, but only partially restored contractures induced by halothane or succinylcholine (to 50 and 30 per cent of Ca(++)-containing medium, respectively). Mepacrine (10 microM) was effective in antagonizing contractures by caffeine, whereas verapamil and nifedipine (10 microM) were not. These results support an essential role for extracellular Ca++ not fulfilled by Sr++ in contracture induction by halothane and succinylcholine, but not by caffeine.     

Evaluation of a low-dose neonatal chest radiographic system

A new low-dose chest radiographic system for use in the neonatal nursery was evaluated. This test system, composed of a Du Pont Kevlar fiber-front cassette, Quanta fast-detail screen, Cronex 4L film (wide latitude), and additional yttrium filtration (0.1 mm), reduced the radiation dose in neonatal chest radiography by 69% (0.9 vs 2.9 mrad [0.009 vs 0.029 mGy]) as compared with a conventional system without added yttrium filtration; the thyroid dose was reduced by 76% (0.9 vs 3.7 mrad [0.009 vs 0.037 mGy]). The cumulative dose reduction was achieved through a combination of factors, including (1) beam hardening by the added yttrium filter, (2) increased X-ray transmission through the Kevlar cassette, and (3) a fast film-screen combination. Scatter radiation at distances of 1 and 6 ft. (0.3 and 1.8 m) was negligible for both systems. Image sharpness was compared for the conventional system with and without added yttrium filtration and for the Kevlar system with yttrium. Although sharpness of bony detail was unchanged by adding yttrium filtration to the conventional system, a decrease in sharpness was noted with the Kevlar system. Because image sharpness was affected in the test system, we are not using the Kevlar-Cronex 4L system for mobile chest radiography in the neonatal intensive care unit, despite dose reductions. However, further study is recommended to determine if there is a slower film-screen combination with yttrium filtration that will not degrade image sharpness.     

Sequential metabolic studies of pancreas allograft function in type 1 diabetic recipients.

We have previously shown that the loss of acute first phase insulin secretion precedes pancreas allograft rejection and development of glucose intolerance in Type 1 diabetic patients. In order to examine whether there is a progressive loss of phases of insulin secretion and beta-cell function in technically successful pancreas transplants during the first year, we measured glucose, insulin, and C-peptide responses to physiological (mixed meal) and pharmacological (IV glucose and IV glucagon) stimulation in 27 glucose-tolerant, insulin-independent allograft recipients at 3, 6, and 12 months. Mean +/- SE fasting serum glucose levels were normalized throughout the study period. Postprandial serum glucose profiles tended to increase by 12 months compared to 3 and 6 months, although peak glucose levels were not statistically different. Following pancreas transplantation, basal serum insulin levels were high at 3 months (163 +/- 17 pM), 6 months (165 +/- 22 pM), and 12 months (248 +/- 54 pM, p = NS) in the Type 1 diabetic pancreas allograft recipients when compared to normal (25 +/- 3 pM). We observed slight elevations in postprandial insulin and C-peptide profiles at 12 months compared to 3 and 6 months. Following IV glucose and glucagon stimulation, serum insulin and C-peptide levels as well as phases of insulin release did not differ over the 12-month study period. Similarly, the glucose decay constant (KG) was nearly identical at 3, 6, and 12 months. In summary, 1 year following successful whole cadaveric, heterotopic pancreas transplantation in Type 1 diabetic recipients, fasting serum glucose remains normalized, while postprandial glucose tends to rise.(ABSTRACT TRUNCATED AT 250 WORDS)     

Human immunodeficiency virus antibody testing. A description of practices and policies at US infectious disease-teaching hospitals and Minnesota hospitals

A questionnaire that asked about policies concerning the use of human immunodeficiency virus (HIV) antibody tests was sent in January 1987 to the 200 hospitals in the United States that conduct infectious disease (ID) fellowship training (US ID hospitals) and to all 171 short-term-care Minnesota hospitals. Information was received from 189 of the US ID hospitals (94.5%) and from 160 (94%) of the Minnesota hospitals. Only 49% of the US ID hospitals and 37% of the Minnesota hospitals had an HIV antibody test-ordering policy; 47% of the US ID hospitals and 39% of the Minnesota hospitals had a specific educational program for physicians about the HIV antibody test; and 62% of the US ID hospitals and 41% of the Minnesota hospitals had an HIV autopsy policy. Marked variety existed in approaches to handling test results, obtaining patient consent, and providing risk-reduction information among the hospitals surveyed. These data suggest the need for a consensus on optimal use of HIV antibody testing at hospitals.     

Safety of simultaneous aortic reconstruction and renal transplantation

Patients with aortic disease and end-stage renal failure who require both aortic reconstruction and renal transplantation (simultaneously or staged) pose a formidable clinical challenge. Traditionally, the performance of either one of these procedures has been viewed as a relative contraindication to the performance of the other. From 1978 to 1989, eight patients were referred to us with the combination of aortic disease and end-stage renal failure. Seven had aneurysmal disease and one had aorto-iliac occlusive disease. Five patients presented with their diseases sequentially and had two sequential operations, with a mean interval of 4 years between procedures. Three patients presented with their diseases simultaneously and underwent simultaneous aortic reconstruction and living related renal transplantation. All patients were followed up for a mean interval of 4.5 years. By life-table analysis, the 5-year renal graft survival was 100%, the primary aortic graft patency was 82%, and the secondary aortic graft patency was 100%. The only death in this series occurred 11 years after aortic reconstruction and 4 months after a renal transplantation and was due to overwhelming cytomegalovirus sepsis. There were no significant differences between the simultaneous and staged groups in terms of operative mortality, postoperative complications, transplant function, or aortic graft patency. From this experience, we conclude that: (1) patients who present simultaneously with aortic disease and end-stage renal failure can safely undergo simultaneous aortic reconstruction and renal transplantation; (2) patients who present with these two diseases sequentially can undergo a second reconstructive procedure with very low operative morbidity and mortality rates; (3) when these two procedures have been performed sequentially, the second procedure has not significantly altered the 30-day or 5-year results of the first procedure; and (4) the 30-day and 5-year results of each procedure have been excellent regardless of the temporal sequence in which they were performed.