Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.

Abstract: Decreased maximal O2 uptake (VO2max) and stimulation of the sympathetic nervous system have been previously shown to occur at high altitude. We hypothesized that tachycardia mediated by beta-adrenergic stimulation acted to defend VO2max at high altitude. Propranolol treatment beginning before high-altitude (4,300 m) ascent reduced heart rate during maximal and submaximal exercise in six healthy men treated with propranolol (80 mg three times daily) compared with five healthy subjects receiving placebo (lactose). Compared with sea-level values, the VO2max fell on day 2 at high altitude, but the magnitude of fall was similar in the placebo and propranolol treatment groups (26 +/- 6 vs. 32 +/- 5%, P = NS) and VO2max remained similar at high altitude in both groups once treatment was discontinued. During 30 min of submaximal (80% of VO2max) exercise, propranolol-treated subjects maintained O2 uptake levels that were as large as those in placebo subjects. The maintenance of maximal or submaximal levels of O2 uptake in propranolol-treated subjects at 4,300 m could not be attributed to increased minute ventilation, arterial O2 saturation, or hemoglobin concentration. Rather, it appeared that propranolol-treated subjects maintained O2 uptake by transporting a greater proportion of the O2 uptake with each heartbeat. Thus, contrary to our hypothesis, beta-adrenergic blockade did not impair maximal or submaximal O2 uptake at high altitude due perhaps to compensatory mechanisms acting to maintain stroke volume and cardiac output.
Adult

Abstract: Gastrointestinal motor function in patients with primary anorexia nervosa has rarely been investigated. We studied oesophageal motor activity in 30 consecutive patients meeting standard diagnostic criteria for primary anorexia nervosa (Feighner et al; DSM III). Seven were found to suffer from achalasia instead of primary anorexia nervosa, one from diffuse oesophageal spasm and one from severe gastro-oesophageal reflux and upper oesophageal sphincter hypertonicity, while partly non-propulsive and repetitive high amplitude, long duration contractions prevailed in the lower oesophagus of another six. In four patients with oesophageal dysmotility not responding to therapy and in 12 of 15 patients with normal oesophageal manometry, gastric emptying of a semisolid meal was studied. Emptying was normal in only three but markedly delayed in 13 cases (half emptying times 97-330 min, median: 147 min, as compared with 21-119 min, median: 47 min, in 24 healthy controls). In eight patients, the effects of domperidone 10 mg iv and placebo were compared under random double blind conditions. Half emptying times were shortened significantly (p less than 0.01) by domperidone. Conclusions: symptoms of disordered upper gastrointestinal motor activity may be mistaken as indicating primary anorexia nervosa; clinical evaluation of patients with presumed primary anorexia nervosa should rule out the possibility that disordered oesophageal motor activity underlies the symptoms; delayed gastric emptying is a frequent feature in primary anorexia nervosa and might be returned to normal with domperidone.
Adolescence

Abstract: Percutaneous coronary laser thermal angioplasty was successfully performed before conventional balloon angioplasty in a 55 year old white man with a 90% left anterior descending artery stenotic lesion and angina at rest (Canadian Heart Association class IV). The lesion was reduced to 50% residual stenosis using a 1.7 mm laser-heated metallic capped fiber and two pulses of 8 W of argon laser energy, each delivered for 5 seconds. With subsequent balloon angioplasty, the lesion was further decreased to 10% residual stenosis. The entire procedure was well tolerated without chest pain or burning, vessel perforation or spasm, thrombus formation or embolization of debris. The patient was free of pain at 1 month follow-up. This case demonstrates the feasibility of safely performing percutaneous coronary laser thermal angioplasty. Additional studies are indicated to determine the clinical role and potential benefits of coronary laser thermal angioplasty in relation to the established procedures of bypass surgery and conventional balloon angioplasty.
Angiography