Biomedical subjects
Publications and source records attributed to M Sanders.
One hundred and four infants and children were included in a comparative study of anesthesia with either enflurane or halothane. Induction and recovery were significantly shorter with enflurane than with halothane. There was little difference between the drugs in respect of their postoperative sequelae.
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Sodium extrusion (J(out) (Na)) was measured across the gills of rainbow trout, Salmo gairdneri, adapted to sea water (SW) using a gill-irrigation system of small volume. The potential difference (TEP) was also measured under similar conditions. J(out) (Na) was usually between 100-250 microeq (100 g)(-1) h(-1), about an order of magnitude faster than in fresh water (FW)-adapted trout, but slower than has been reported for any other marine teleost. The TEP was between 10-11 mV, body fluids positive to SW. When the external medium was changed from SW to FW J(out) (Na) was reduced to about 25 % of the initial value, and the TEP was reduced by 40-50 mV (i.e. body fluids negative by 30-40 mV). Addition of either Na(+) or K(+) in SW concentrations reversed the changes; J(out) (Na) increased and the gill repolarized. The electrical behavior and sodium efflux in irrigated trout gill is qualitatively the same as has been reported for unanaesthetized, free-swimming fish of other species. Thus, the irrigated gill provides an adequate model for studying the mechanism of sodium extrusion in marine teleosts.
Sodium efflux (J(out) (Na)) across the irrigated trout gill was rapid in sea water (SW), but only about 25 % as large in fresh water (FW). The difference correlated with a change in the potential difference across the gill (TEP). The latter was about +10 mV (blood positive) in SW, but -40 mV in FW. Both flux and electrical data indicated that gills in this fish are permeable to a variety of cations including Na(+), K(+), Mg(2+), choline, and Tris. They are less permeable to anions; P(Na):P(K):P(Cl) was estimated to be 1:10:0.3, and P(Cl) > P(gluconate). The TEP was shown to be a diffusion potential determined by these permeabilities and the extant ionic gradients in SW, FW as well as in other media. J(out) (Na) appeared to be diffusive in all of the experiments undertaken. Exchange diffusion need not be posited, and the question of whether there is an active component remains open.
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Total and regional myocardial blood flow was measured in miniature pigs at rest and during two levels of treadmill exercise, including maximal exercise. Exercise increased the myocardial blood flow in a linear manner with heart rate (r = 0.87). At rest the endocardial/epicardial blood flow ratio was significantly greater than unity with flow favoring the endocardium. Exercise failed to appreciably alter the distribution of coronary blood flow. Thus the myocardium was capable of further dilatation and perfusion of blood without compromising endocardial flow even during the most severe level of exercise when maximal heart rates were attained.
Theodor Leber became famous for his dissertation on the ocular circulation in 1865 at the youthful age of twenty-five. He was Professor of Ophthalmology at Goettingen between 1870 and 1890 and at Heidelberg University between 1890 and 1910. By presenting his original descriptions of the disorders that bear his name, this article commemorates the death, seventy-five years ago, of a founder of ophthalmic research.
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OBJECTIVE: We investigated whether the effects on cardiovascular reactivity of social support from an audience member depend only on the behavior of that person or also depend on the relationship between the audience and the actor. That is, is there any added reduction in physiological response if the person who is nodding and smiling supportively is also a friend? METHOD: Ninety subjects gave a speech to an observer. In two of the conditions, this observer was a confederate of the experimenter and a stranger to the subject. This confederate acted in either a supportive or neutral manner during the speech. In the final condition, this observer was a friend, brought by the subject, who was then trained to show support in the same manner as the supportive confederate. The comparison of the two confederate conditions tested the effect of support, holding the relationship constant. The comparison of friend and confederate supportive conditions tested the effect of the relationship, holding the supportive behaviors constant. All participants were female. RESULTS: Both supportive conditions produced significantly smaller cardiovascular increases than the confederate-neutral condition, and the friend-supportive condition produced significantly smaller systolic blood pressure increases than the confederate-supportive (friend-supportive: 7.9 mm Hg: confederate-supportive: 14.9 mm Hg; confederate-neutral: 22.9 mm Hg). Differences for diastolic pressure and heart rate were not significant, although the data followed the same pattern. CONCLUSIONS: Social support from a friend attenuated cardiovascular reactivity in a laboratory setting to a greater degree than support from a stranger. The subjects' construal of the supportive behaviors can have an effect on reactivity, over and above the effects of the actual behaviors themselves.
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