Muscle fiber composition and blood ammonia levels after intense exercise in humans

The relationship between fiber type composition and the increase in blood ammonia was examined following a maximal O2 consumption (VO2max) test. Muscle biopsies were taken from the middle portion of the vastus lateralis for determination of fiber type percentages. Two subject groups were selected on the basis of a high (HST) or low (LST) percentage of slow-twitch fibers and compared for blood ammonia and lactate levels after exercise at work loads of approximately 85 and 110% of VO2max. An inverse relationship was found between the percentage of slow-twitch fibers and the increase in blood ammonia. Blood ammonia increased after exercise at both 85 and 110% of VO2max. However, the increase was twofold greater for the LST group following the 110% work effort. The increases in blood ammonia and lactate were positively correlated for both groups following exercise. The results suggest that the proportion of slow-twitch fibers plays an important role in determining the magnitude of the increase in blood ammonia after intense exercise.     

A case of veno-occlusive disease of the liver in Britain associated with herbal tea consumption

Veno-occlusive disease of the liver with clinical and pathological features similar to those of the condition occurring in the Caribbean is described in a young woman resident in Britain. The diagnosis was made from liver biopsies and hepatic venography and was confirmed at necropsy. Small amounts of pyrroliziding alkaloids were recovered from a sample of mate (Paraguay) tea, owned by the patient, to which she was addicted. It seems probable that the consumption of large amounts of this tea over a period of years was the cause of the hepatic disease.     

Regulation of acetylcholine synthesis: does cytoplasmic acetylcholine control high affinity choline uptake?

When brain synaptosomes are obtained from animals that have been injected intravenously with [2H4]choline 1 minute before being killed, their high affinity [3H] choline uptake is correlated inversely with their acetylcholine content and directly with the rate at which they synthesize [2H4]acetylcholine. The control of such choline uptake by the cytoplasmic acetylcholine concentration is proposed as a mechanism regulating acetylcholine synthesis in cholinergic nerve terminals.     

Human joint performance and the roughness of articular cartilage

The Doppler technique has been used to evaluate venous reflux in the spermatic cord. Valsalva-induced reflux occurred on the left side in 83% and on the right side in 59% of 118 patients without clinical varicoceles and there was no difference in incidence between fertile and infertile men. The significance of Valsalva-induced reflux should be questioned. Greater importance should be attributed to the spontaneous venous reflux that occurred during quiet respiration in the majority of patients with varicoceles. Seven velocity waveform patterns are described and these are thought to represent increasing degrees of internal spermatic vein reflux and provide a basis on which it is possible to grade varicoceles. The Doppler grades correlated with the size of the varicocele, and with the internal spermatic vein diameter and testosterone concentrations.     

Multiple choice questions for continuing education in family medicine

Multiple choice questions used in continuing medical education may require characteristics different from those used in tests and examinations. The questions of three continuing education exercise were assessed by 48 board certified family physicians. Each physician answered one third of the questions and then judged them on usefulness in patient management, as discriminators of quality of medical care, and on educational value. The relevance of each question was determined by a composite index based on these factors. The content of each question was independently analyzed by three physicians. Relevant questions tended to be those concerned with surgery, symptoms, and management, and those requiring more than simple factual recall. Questions on office management or concerning specific diagnoses were considered less relevant. Neither the manner of asking the question nor the severity of the illness appeared to influence relevance. This information should benefit those developing continuing education programs for family physicians, especially those designed for self-administered individual learning.