Biomedical subjects
G W Thomas
Publications and source records attributed to G W Thomas.
Stereotactic radiosurgery: does Australia need it?
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Comparison of labetalol, clonidine and diazoxide intravenously administered in severe hypertension.
Diazoxide, clonidine and labetalol, administered intravenously in fixed doses, were used to treat 30 episodes of severe hypertension in 27 patients. Labetalol in a fixed dose of 100 mg proved ineffective treatment. Diazoxide 300 mg and clonidine 300 micrograms were comparable in effectiveness. Drowsiness was a common side effect with administration of clonidine (in six of 10 patients) and severe hypotension occurred in one patient who was given diazoxide.
Salmonella paratyphi B in cattle.
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The International Grenfell Association. Part II: the benefits of Newfoundland's entry into Confederation.
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The International Grenfell Association: its role in northern Newfoundland and Labrador. Part I: the early days.
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Reduced renin activity in essential hypertension: a reappraisal.
The apparent suppression of plasma renin activity in essential hypertensive patients compared to normotensive controls prompted an examination of factors which might be responsible for this difference in people taken from a blood pressure screening survey. Plasma renin activity was lower in 89 previously untreated "hypertensive" subjects than in an equal number of age- and sex-matched "controls" from the same community. The rise in plasma renin activity on standing or after frusemide was proportional to the resting level, and it was generally less in hypertensives, but small or absent responses were also seen in those with normal blood pressure. There was no evidence for a "low renin sub-group" among the hypertensives. Plasma renin activity fell with both increasing age and increasing arterial pressure. A low renin activity is more likely to be a consequence of hypertension than to be associated with its cause.
Hypertension and raised serum lipids.
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Scalp tingling in patients on labetalol.
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Reduced plasma renin activity in essential hypertension: effects of blood pressure, age and sodium.
1. Supine plasma renin activity and its responsiveness to erect posture and frusemide were reduced in fifty-one patients with essential hypertension, compared with fifty-one age- and sex-matched control subjects. 2. Twenty-four hour urinary sodium excretion was similar in hypertensive patients nad control subjects. 2. Twenty-four hour urinary sodium excretion was similar in hypertensive patients and control subjects, but after intravenous frusemide hypertensive patients excreted significantly less sodium. 3. A significant inverse relationship between plasma renin activity and diastolic blood pressure was demonstrated in hypertensive patients and in normotensive control subjects. 4. A significant inverse relationship between plasma renin activity and age, independent of blood pressure, was shown in hypertensive patients and control subjects. 5. It is concluded that the reduced renin values found in essential hypertension are, in part, the result of the elevated blood pressure acting on the kidney.
Renin unresponsiveness and the effects of oxprenolol, methyldopa and spironolactone in pateints with essential hypertension.
Plasma renin activity (PRA), supine, erect and post-frusemide (1 mg/kg IV) was studied in 51 patients with previously untreated essential hypertension and their age- and sex-matched normotensive controls. Supine PRA, and the rise in PRA in response to the erect posture and frusemide, were significantly less in hypertensives compared to controls. When the hypertensives were arbitrarily divided into lower, mid, and upper subgroups according to supine PRA, the renin responsiveness was similar in each subgroup but significantly less in hypertensives compared to controls, subdivided in the same way. This does not support the existence of a separate "low renin" subgroup. The low supine PRA and reduced response to stimulation appears to be a feature of patients with essential hypertension. Thirty-nine of these hypertensives entered a double-blind cross-over drug trial of oxprenolol, methyldopa and spironolactone. All three drugs were equally effective in lowering the systolic and diastolic blood pressures in all three renin subgroups. Spironolactone caused a greater fall in systolic pressure in the lower renin group than in the other groups. Oxprenolol was the best tolerated drug, with only 5% of patients withdrawing due to side-effects compared to 13% on spironolacone and 29% on methyldopa.
Massive spinal cord infarction due to vascular invasion by reticulum cell sarcoma.
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A model system for direct in vivo measurement of absorbed nutrients in portal venous blood. Applicability to alcohol studies.
In order to investigate the in vivo effect of alcohol on intestinal absorption and on other factors which influence the rate of appearance of nutrients into the portal venous system, an experimental system has been developed in which separate cannulas have been implanted in the duodenum and portal vein of the rat. Following recovery from surgical procedures, unanesthetized animals may be administered nutrients directly into the duodenum, with and without alcohol, and the rate of appearance of nutrients in the portal system may be monitored by rapid sampling of the portal blood. Potential applicability of this experimental animal is demonstrated by the kinetics obtained with an amino acid, L-phenylalanine, both in the presence and the absence of alcohol.
Surgery in the sub-Arctic: a thoracic surgeon's odyssey.
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Pancreatitis in northern Newfoundland and Labrador: a 20-year review of the Grenfell Regional Health Services experience.
A retrospective review of the Grenfell Regional Health Services experience with pancreatitis over a 20-year period (1968-1987) has been presented. The small number of cases in this series precludes meaningful statistical analysis, however, in general, one can state that native peoples are represented in this study in roughly the same proportion as they are represented in the population served. We have demonstrated that pancreatitis in its chronic form does occur in the Inuit of Northern Labrador. Given the prominent role that alcohol abuse plays in the social and behavioral ills of Labrador's native peoples as reflected in the high incidence of family violence, accidental deaths, and suicides, one might anticipate a disproportionately high incidence of pancreatitis and its chronic sequelae among the Inuit. The answer to this seeming paradox may be found through future study of the nature of the alcohol consumed, its pattern of consumption or of genetically-determined differences in the metabolism of alcohol and its toxic effects within the body, of differences in the composition of pancreatic secretions, or of environmental and dietary factors.
Salmonellae in effluent waters and river sites in North Yorkshire.
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