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3849. Endothelin: an important factor in acute renal failure?
Very low concentrations of the vasoconstrictor peptide endothelin cause intense long-lasting renal vasoconstriction. In the isolated perfused rat kidney, the concentration of endothelin required to reduce blood-flow by 50% is 200 pmol/l, compared with 1000 pmol/l angiotensin II (previously the most potent known vasoconstrictor). Whereas angiotensin II has little effect on the glomerular filtration rate (GFR), a rise in endothelin from 100 to 800 pmol/l reduces GFR by 90%. Endothelin is probably present in the circulation at low concentrations in vivo; events associated clinically with acute renal failure would tend to increase this concentration. Endothelin may be a mediator in the pathogenesis of acute renal failure.
3851. In praise of peroxidation.
Free-radical-mediated lipid peroxidation has become closely associated with destructive biochemical processes and, more recently, with disease. Its potential survival value may be overlooked.
3852. Microbiological look at urodynamic studies.
作者: S R Payne.;A G Timoney.;S T McKenning.;D den Hollander.;L J Pead.;R M Maskell.
来源: Lancet. 1988年2卷8620期1123-6页
Urine samples were cultured for aerobic, fastidious, and anaerobic bacteria in 88 patients (66 F, 22 M) before and after standard urodynamic investigations. 37 of 42 women with detrusor instability, and 14 of 17 women with stress incontinence, had evidence of bacteriuria with aerobic or fastidious bacteria before investigation, as did 6 of 13 men with bladder outflow obstruction. 8 men (36%) acquired bacteriuria with aerobic bacteria after investigation, compared with 10 women (15%). Recalcitrant, irritative urinary symptoms in women may be caused by an underlying infection, the urodynamic changes being secondary. In men who have urodynamic studies, antibiotic prophylaxis should be considered.
3856. Are current dietary guidelines for young children a prescription for overfeeding?
作者: A M Prentice.;A Lucas.;L Vasquez-Velasquez.;P S Davies.;R G Whitehead.
来源: Lancet. 1988年2卷8619期1066-9页
New estimates for the energy requirements of young children have been derived by combining the energy deposited during growth with measurements of total energy expenditure obtained by use of the new doubly-labelled water (2H2(18)O) method in 355 healthy infants aged 0-3 years. The resultant values of 110, 95, 85, 83, 83, 84, and 85 kcal/kg/day at 1, 3, 6, 9, 12, 24, and 36 months, respectively, are substantially lower than current Department of Health and Social Security and FAO/WHO/UNU recommended dietary allowances. Evidence from diet surveys suggests that changes in infant feeding practices are largely responsible for the apparent reduction in energy requirements. Dietary guidelines may need to be reappraised, to avoid overfeeding of infants.
3859. Antihypertensive treatment, myocardial infarction, and nocturnal myocardial ischaemia.
Patients with critical coronary stenoses or hypertrophied ventricles have impaired coronary vasodilator reserve and are at greatest risk of myocardial ischaemia or infarction if subendocardial perfusion pressure falls below the lower threshold of bloodflow autoregulation. During sleep, antihypertensive treatment may cause coronary artery perfusion pressure to fall below these limits in such patients. Unrecognised nocturnal hypotension may be one reason why treatment has not diminished the risk of myocardial infarction in patients with hypertension.
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