Metabolic studies of isolated human eccrine sweat glands.

This paper describes a method for isolating and studying the metabolism of human eccrine sweat glands. (a) Electron microscopy of glands which had been isolated and then incubated for an hour revealed no apparent alteration in morphology. (b) Known variation in gland size (male > female > children) was reflected in the relative rates of lactate production. (c) Lactate production was approximately 1.5 nmoles/gland per hr in the absence of glucose and rose to 2.7 at physiological concentrations of glucose (5.6 mmoles/liter). This amount of lactate production agrees well with the amounts found in sweat. (d) Both adrenergic (epinephrine) and cholinergic (methacholine) stimuli increased lactate production. (e) Glycogen depletion was demonstrated during incubation. (f) O(2) consumption was measured and aerobic metabolism was found to account for less than 1% of the energy derived from anaerobic pathways. These studies demonstrate that the large amounts of lactate appearing in human eccrine sweat can be accounted for by glandular metabolism and that both glycogen and glucose can be used as substrates.

Genesis of the sweat:plasma urea concentration gradient.

Experiments with 14C-labeled urea in human volunteers show that urea is sequestered in the epidermis, where it turns over more slowly than in general body water. Sequestered urea, presumed to be concentrated through insensible evaporation of water, is the source of the excess urea found in sweat. Physiologic and clinical implications of the existence of this urea pool are discussed.

A cluster of sternal wound infections requiring muscle flap repair: problems in epidemiologic investigation.

A cluster of sternal wound infections (SWI) requiring muscle flap closure occurred in a California hospital in 1988. Review of SWI rates by surgical team revealed that a single team (Team A) was associated with a cluster of SWI requiring muscle flap repair (MFR). Team A's rate of SWI requiring MFR was 2.27% in 441 heart operations. A case/control study was conducted to determine if the higher rate of SWI requiring MFR could be attributed to disproportionately large numbers of patients at high risk treated by Team A. Data on major risk factors for SWI collected for case and control groups included the following: age at operation, weight, body surface area, history of obesity, diabetes mellitus, or cigarette smoking, duration of cardiopulmonary bypass, use of internal mammary artery graft, number of coronary arteries bypassed, use of prostheses, operating room staffing, and emergent nature of operation. No statistically significant differences between Team A cases requiring MFR and control cases were observed for predisposing risk factors. Surgical technique remains a principal suspected risk factor for SWI requiring MFR in this cluster.

Attempted prevention of diarrheal disease in Apache children with a non-absorbable broad-spectrum antimicrobial.

A double-blind study was conducted to test the prophylactic effect of a non-absorbable broad-spectrum antimicrobial (oral colistin sulfate) against acute diarrhea in Apache children. Children 1 to 6 months old had over twice the morbidity from diarrhea if assigned to the antimicrobial group as compared to placebo, while the toddler group (7-30 months) taking the antimicrobial had somewhat less diarrhea. Enteropathogenic E. coli were significantly more often isolated from the antimicrobial group (but only in well children). No special effect on the children's growth by the antimicrobial was discerned.

Permanent cardiac pacing after a cardiac operation: predicting the use of permanent pacemakers.

BACKGROUND: The need for permanent cardiac pacing after cardiac operations is infrequent but associated with increased morbidity and resource utilization. We identified patient risk factors for pacemaker insertion to enable development of a predictive model. METHODS: Data were collected prospectively for 10,421 consecutive patients who had cardiac operations between January 1990 and December 1995. Two hundred fifty-five patients (2.4%) were identified as having received a permanent pacemaker during the same hospitalization. Logistic regression analysis was performed to determine the independent, multivariate predictors of permanent pacing. The predictive accuracy and precision of the logistic regression model was evaluated in the 1996 database of 2,236 consecutive patients by the calculation of Brier scores. RESULTS: Eight independent predictors of permanent pacemaker requirement were identified. The factor-adjusted odds ratios (OR) with 95% confidence interval (CI) associated with each predictor are as follows: (1) valve replacement surgery (aortic: OR 5.8, CI 3.9-8.7; mitral: OR 4.9, CI 3.1-7.8; tricuspid: OR 8.0, CI 5.5-11.9; double: OR 8.9, CI 5.5-14.6; and triple: OR 7.5, CI 2.9-19.3); (2) repeat operation: OR 2.4, CI 1.8-3.3; (3) age 75 years or older: OR 3.0, CI 2.0-4.4; (4) ablative arrhythmia operation: OR 4.2, CI 1.9-9.5; (5) mitral valve annular reconstruction: OR 2.4, CI 1.4-4.2; (6) use of cold blood cardioplegia: OR 2.0, CI 1.2-3.6; (7) preoperative renal failure: OR 1.6, CI 1.0-2.6; and (8) active endocarditis: OR 1.7, CI 0.9-3.0. A model for postoperative permanent pacemaker requirement using the eight predictors was formulated and tested (Brier score = 0.017+/-0.003; Z = 0.18). CONCLUSIONS: The proposed predictive model correlated highly with actual pacemaker use, which suggests that the requirement for pacing results from either operative trauma or increased ischemic burden. Preoperative identification of patients at increased risk of conduction disturbances may allow for earlier detection and improved treatment. Patients requiring postoperative pacing had increased morbidity and length of stay.

Palladium-catalysed cross-coupling reactions in supercritical carbon dioxide.

Heck and Suzuki reactions proceed in good yield in supercritical carbon dioxide in the presence of palladium acetate and tri-tert-butylphosphine with both free and polymer-tethered substrates.

Valve surgery in octogenarians.

OBJECTIVE: To review the outcomes of octogenarians undergoing valve operations. PATIENTS AND METHODS: One hundred and twenty-five consecutive patients aged 80 years and over received valve operations between 1990 and 1996 at the Toronto General Hospital, Toronto, Ontario. All hospital survivors were prospectively followed for a mean of 36.6 months (range 0.1 to 89.9). RESULTS: One hundred and two patients received aortic valve operations, 18 patients received mitral procedures and five patients underwent double valve operations. Significant aortic stenosis was present in 95 of 102 patients (93%) receiving isolated aortic valve surgery, and mitral regurgitation was present in 16 of 18 patients (89%) undergoing mitral valve operations. Overall in-hospital mortality was 6.4% (n=8) and the perioperative infarction rate was 1.6% (n=2). In-hospital mortality was higher for mitral valve patients at 17% (n=3) than for aortic valve patients at 4% (n=4) (P=0.06). For the group overall, the six-year actuarial survival rate was 71.6+/-6%. The actuarial freedom from valve-related death was 97.1+/-2% at three years. Concomitant coronary artery disease was not significantly associated with perioperative mortality. Survivors had significantly improved New York Heart Association functional class status. CONCLUSION: In carefully selected patients aged 80 years and over, aortic valve surgery carries a low perioperative mortality with good intermediate term survival and benefits. Octogenarians undergoing mitral valve procedures experience higher perioperative mortality. Although the number of participants was small for this study, it does appear that coexistent coronary artery disease should not be the sole reason for denial of surgery because it has less of an impact on short and intermediate term survival than other factors.

Intussusception in the adult--a rare disease.

We present two cases of intussusception in the adult. Both cases were secondary to a benign lipoma as the lead point. These cases represent typical cases of adult intussusception, a rare disease characterized by insidious onset, vague abdominal symptoms, and elusive diagnosis. A diagnostic and therapeutic approach to adult intussusception is suggested. The need to consider this rare entity in the differential diagnosis of chronic abdominal complaints in the adult is emphasized.

Further mechanical considerations between polar and SRM mobile ergometer systems during laboratory-based high-intensity, intermittent cycling activity.

The purpose of this article is to outline mechanical issues related to the use of the Polar S710 heart monitor with Power Unit when compared with the SRM Powercrank system. There are issues outlined in this article that refer to the suitability of the Polar S710 for the quantification of performance during downhill cycling that relate to chain vibration, chain tension, and time interval sampling rates.

Issues in human experimentation.

The current status of two difficult and controversial issues--confidentiality of preliminary results of clinical studies and compensation for research-related injuries--is outlined. The principle of not publicizing results of clinical research until enough data have been accumulated to give statistically valid support for conclusions is in conflict with the principle of ready availability to the public of results of government-conducted and government-sponsored research. New legislation may be required to resolve the problem. The lack of a mechanism to compensate research subjects for unanticipated injuries that are not the result of negligence is a barrier to obtaining truly informed consent. A plan for overcoming this problem through Department of Health, Education, and Welfare regulations has been proposed and awaits implementation.

Taking to the skies.

The role of Helicopter EMS must be to improve patient care and/or to ensure the most rapid transport of critically ill or injured patients. It has been suggested by Rhee et al, that the aeromedical service can be justified when the speed of the helicopter transport, the skills of the medical crew, and/or the ability of the helicopter to overcome environmental obstacles is likely to contribute to improved patient outcome. If one adds the essentials of well-trained, professional personnel and equipment, the "helicopter" becomes an important part of the overall medical care system and an essential component in improving patient outcome. While reviewing the role of the HEMS, it cannot be sufficiently emphasized that such a service in no way replaces an established ground ambulance system. A proficient, well-trained and well-equipped ground EMS program remains the backbone of an efficient pre-hospital and interhospital system. HEMS cannot be viewed as an isolated component of any EMS system. Instead, it must serve to complement the existing resources of the community. These is sufficient literature to suggest that the use of air medical services in transporting patients to tertiary care facilities or trauma centers has led to an improvement in overall survival rates. At the same time, an apparent paradox in mortality rate has occurred at the receiving hospital. While more patients are saved by speedy transport to a hospital, the mortality rate in that hospital may actually increase. Some patients who may have died from their injuries at the scene, or in transit, now die upon admission.(ABSTRACT TRUNCATED AT 250 WORDS)

Permanent internal pacemaker safety in air medical transport.

Helicopter and fixed-wing air medical transportation provides an important role in the management of critically-ill patients. As the use of cardiac pacemakers continues to grow, knowledge of their expanding capabilities and sophistication is important. The environments of our "airborne intensive care units" are subject to many sources of electromagnetic and vibrational interference. Although pacemaker shielding mechanisms have become quite elaborate, further studies are needed to define their reliability in modern aircraft. Further, the possible effects of electromagnetic and vibrational interference upon inflight reprogramming require further study.