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Biomedical subjects

R Weeks

Publications and source records attributed to R Weeks.

27 records · Page 2Linked to original sources
PubMed1983

Effects of trimazosin and prazosin on blood pressure and on pressor responses to phenylephrine in rats.

As part of an ongoing investigation into the cardiovascular properties of trimazosin, 99 male Sprague-Dawley rats were anesthetized and cannulas were placed in jugular veins for administration of drugs. The rats were injected with phenylephrine and then treated with either solvent, diazoxide, prazosin, or trimazosin. Blood pressure and heart rate were measured by a pressure transducer and a biotachometer, respectively; both were recorded continuously. Preliminary results indicate that trimazosin was less potent but more efficacious in lowering blood pressure than was prazosin and caused less blockade of the alpha-1-adrenoceptors even when its hypotensive effect exceeded that of prazosin. The differences in hypotensive potency and in alpha-1-receptor blockade are consistent with the fact that trimazosin has less affinity than does prazosin for alpha-1-receptors in vitro. The greater efficacy of trimazosin, compared to prazosin, is further evidence that in addition to alpha-1-receptor blockade, another mechanism contributes to the hypotensive effect of trimazosin. This mechanism has yet to be elucidated.

Animals↗
PubMed1981

Outbreak of acute pulmonary histoplasmosis in members of a wagon train.

In August 1980, an outbreak of acute pulmonary histoplasmosis occurred among participants in a wagon train as it traveled through eastern Tennessee. Of the 85 people on the train 69 (81 percent) had evidence of infection with Histoplasma capsulatum. Fifty-four people had symptomatic disease. The source of infection was traced to the site of a former winter blackbird roost in Charleston, Tennessee, that had been partially cleared five years earlier to make a park. Fourteen of 25 soil samples from this site were culture-positive for H. capsulatum. This is the first reported outbreak to involve a large migrant group. The outbreak is unusual in that exposure occurred without excavation, construction or tree-cutting at the site.

Adult↗
PubMed1977

Functions of the centre section (trunk) of the corpus callosum in man.

The case is reported of a patient in whom the middle sagittal third of the corpus callosum had been removed for the treatment of an underlying angioma. The special advantages of the case are that the patient is a young, relatively healthy person of normal IQ. The angioma had not interfered with interhemispheric transmission and the patient was described as neurologically normal before operation. After operation left-side neglect and extensive somatic disconnection were seen. A change in the balance between the hemispheres for handedness and ear superiority in dichotic listening was observed. The patient developed an aphasia after operation characterized by a simplification of language, the inavailability of complex ideas and emotional communication. He showed a disorder of memory--'autopragmatic amnesia'--in whice. The patient showed disorders of visuo-spatial transfer. These symptoms are thought to typify a syndrome of the centre trunk region of the corpus callosum, to follow as a direct function of the operation performed upon the callosum, and to illustrate the function of this region of the brain.

Adult↗
PubMedDate not supplied

The hypotensive effect of trimazosin is not caused solely by alpha 1-adrenoceptor blockade.

Trimazosin is a quinazoline antihypertensive agent structurally related to the selective alpha 1-adrenoceptor blocker prazosin. Trimazosin has been shown previously to have less affinity for alpha 1-adrenoceptors than prazosin. In the present study we compared the hypotensive potency and efficacy of the two agents, and their effects on pressor responses to phenylephrine in anesthetized dogs. We also determined the effect of trimazosin administered during a maximum hypotensive response to prazosin, and of sodium nitroprusside administered after trimazosin or prazosin. Compared with prazosin, trimazosin was a less potent but more efficacious hypotensive agent. At doses which caused equal or even greater hypotensive effects than those caused by prazosin, trimazosin caused less inhibition of pressor responses to phenylephrine. When administered during a maximum hypotensive response to prazosin, trimazosin caused an additional fall in pressure. These results clearly demonstrate an additional action of trimazosin beyond blockade of alpha 1-adrenoceptors. Both trimazosin and prazosin augmented the hypotensive effect of sodium nitroprusside, but only trimazosin enhanced its relaxant effect on isolated rat aorta. Thus we conclude that in addition to alpha 1-adrenoceptor blockade, another mechanism contributes to the hypotensive effect of trimazosin, and we speculate that elevation of cyclic GMP levels in vascular smooth muscle may be related to this additional mechanism.

Adrenergic alpha-Antagonists↗