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Biomedical subjects

W S Harris

Publications and source records attributed to W S Harris.

At least 91 records · Page 5Linked to original sources
PubMed1980

Noninvasive assessment of left ventricular effects of hydralazine in heart failure.

In order to develop a noninvasive means for following left ventricular responses to hydralazine, we measured the systolic time intervals serially in 6 patients with heart failure. Without affecting heart rate or arterial pressure, hydralazine lengthened the left ventricular ejection time relative to the heart rate (LVETc) 19 +/- 7 msec (p < 0.05) and shortened the preejection period 23 +/- 3 msec (p < 0.001), restoring it to normal in 4 patients. The data suggest that preejection period shortening and LVETc lengthening provide the basis for a noninvasive method of assessing the effects of hydralazine on left ventricular performance in heart failure.

Adult↗
PubMed1979

Bile acid metabolism in ascorbic acid-deficient guinea pigs.

Sterol balance techniques have been used to determine the effect of short-term ascorbic acid (AA) deprivation on bile acid excretion in the guinea pig. The effects of a brief (2-week) AA deficiency on bile acid pool sizes and the activity of the rate controlling enzyme in bile acid biosynthesis have been determined. It was found that, while food intake and body weight were not affected by the short-term AA deficiency, liver AA levels had fallen to 25% of control levels. At the same time, the rate of excretion of bile acids and the size of the bile acid pool were both reduced by about 50% in guinea pigs deficient in AA. These results were supported by a decrease in the activity of cholesterol 7 alpha-hydroxylase in the deficient animals. It is concluded that an AA deficiency will significantly impair bile acid metabolism independent of any side effects of clinical scurvy.

Animals↗
PubMed1977

Intracerebroventricular taurine in rabbits: effects of normal body temperature, endotoxin fever and hyperthermia produced by PGE1 and amphetamine.

1. Intracerebroventricular (I.C.V.) injections of taurine into rabbits resting at an ambient temperature (Ta) of 10 degrees or 23 degrees C caused hypothermia but at 30 degrees C ambient temperature, rectal temperature was unchanged. 2. An I.C.V. bolus of 0=5 mg taurine immediately followed by a slow infusion of taurine (0-01--0-2 mg/min) into rabbits at 23 degrees C ambient temperature caused sedation and peripheral vasodilation and blocked the febrile response to Salmonella typhosa endotoxin (1 microng/kg i.v.). Sustained fevers, characteristic of fevers caused by central administration of pyrogens, developed after taurine infusions were stopped. Control infusions of taurine at the same rates in the same rabbits when they were afebrile had little effect on rectal temperature. 3. An I.C.V. injection of 0-5 mg taurine reduced the hyperthermia caused by prostaglandin E1 (PGE1; 2 microng) given I.C.V. A dose of 5-0 mg not only blocked PGE1 hyperthermia but also caused marked hypothermia. 4. Bilateral injections of taurine into the preoptic/anterior hypothalamic region, at sites where injections of Salmonella typhosa endotoxin caused long-lasting fevers, had no effect on rectal temperature. Similar injections into the reticular substance of the medulla oblongata, in the region believed to be concerned with a secondary temperature control function, were also without effect on body temperature. 5. Taurine (0-5 and 5-0 mg, I.C.V.) had no consistent effect on hyperthermia induced by amphetamine (2 mg/kg, I.V.) 6. We conclude that the hypothermic effect of taurine is not due to an action on the central neurone pool or pools concerned with the integrative control of thermoregulatory effectors. This amino acid appears to inhibit neuronal activity in efferent pathways which control peripheral vasomotor tone and heat production and to depress the level of arousal. Taurine delays the onset and extends the duration of endotoxin-induced fever, perhaps by two separate action: by inhibiting activity in central thermoregulatory pathways and by promoting accumulation of endogenous pyrogen in the brain.

Amphetamines↗
PubMed1977

Coronary sinus blood flow and sampling for detection of unrecognized myocardial ischemia and injury.

Fifteen patients were studied to detect unrecognized intraoperative ischemia or necrosis in perioperative myocardial infarction (MI) associated with coronary bypass. Simultaneous arterial and coronary sinus blood samples were analyzed for lactate and both total and MB-CPK. Coronary sinus flow measurements were done coincident with sampling in seven patients. Five had perioperative MI diagnosed by positive pyrophosphate scan and electrocardiogram. Although normal initially (mean 19 +/- 5.0%), lactate extraction after thoracotomy, before aortic cross-clamping, became abnormal in 12 patients with more pronounced abnormality in those with perioperative MI (-19 +/- 9.0%). Net efflux of lactate was higher in perioperative MI (mean 0.6 +/- 0.2 vs 0.016 +/- 0.04 mM/L) than in non-MI patients. All patients had detectable total and MB-CPK (mean 295 and 31 IU/L, respectively) and all those with coronary disease had a positive arterial-coronary sinus gradient for MB-CPK (mean 9 IU/L). Perioperative MI patients had a higher gradient than non-MI patients (mean 25 vs 2 IU/L) and with one exception that gradient exceeded 5-7 IU/L. It is concluded that severe ischemia before aortic cross-clamping precedes perioperative MI and may contribute to release of CPK into coronary sinus blood. Improvement in the techniques of anesthesia and intraoperative myocardial preservation are suggested.

Adult↗
PubMed1977

Cystoid macular edema following intraocular lens implantation.

This presentation recounts the original description of CME and the more recent developments associated with intravenous fluorescein angiography in its study and diagnosis. The work of previous authors to show the incidence of CME and its possible prognosis are reviewed. Our findings in a retrospective study agree with the other authors and show that there is no particular increase in CME following intraocular lens implantation regardless of the type of surgical procedure used. It is established that vitreous loss does increase the incidence of CME. A prospective study with routine intravenous fluorescein at six weeks is presented and shows an incidence that is below that found by other authors when it was performed following routine intracapsular cataract extraction.

Cysts↗
PubMed1976

Effects of hypoxia and Freon 12 on mechanics of cardiac contraction.

Data are presented which indicate that the mechanism of tension depression and subsequent recovery from dichlorodifluoromethane (Freon 12), an aerosol gas recently described as a potent cardiac depressant agent, differs from that of hypoxia. To analyze these differences, 22 rat papillary muscles, contracting isometrically in a myograph, were studied during and subsequent to 15-min interventions of of hypoxia. Freon 12 with adequate oxygenation, or Freon 12 combined with hypoxia. During each of the three interventions the developed force (F) was markedly depressed, while peak shortening velocity (Vpm) was selectively more depressed by Freon and Freon combined with hypoxia than by hypoxia alone. While hypoxia shortened the time to peak force (TTP) and one-half relaxation time (RT1/2) markedly, Freon 12 with adequate oxygenation slightly shortened RT1/2 (P is less than 0.001) but failed to shorten TTP significantly. In contrast, Freon 12 administered during hypoxia shortened TTP and RT1/2 significantly (P is less than 0.001), more than did hypoxia or Freon 12 alone. Posthypoxic prolongation of TTP and RT1/2 was not seen during recovery from Freon 12. This prolongation was depressed during recovery from Freon 12 given either during hypoxia or during recovery from hypoxia. The results indicate that Freon 12 and hypoxia act synergically, although the mechanisms through which they mediate their actions on myocardial tissue are not identical.

Animals↗