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Biomedical subjects

K M Welch

Publications and source records attributed to K M Welch.

257 records · Page 15Linked to original sources
PubMedDate not supplied

Cathecholamine and 5-hydroxytryptamine levels in ischemic brain. Influence of p-chlorophenylalanine.

The effect of ischemia on catecholamine and 5-hydroxytryptamine (5-HT) levels in brain cortex was examined in the gerbil stroke model. Unilateral common carotid artery occlusion produced bilateral decrease in cortical dopamine levels in gerbils both symptomatic and asymptomatic of cerbral ischemia. The 5-HT progressively decreased only in the occluded hemisphere of ischemic animals. In p-chlorophenylalanine (PCPA)-treated gerbisl, dopamine decreased only in the occluded hemisphere of symptomatic animals, but norepinephrine became decreased bilaterally compared with controls. The 5-HT decrease was twice that seen in untreated animals. It is suggested that these results indicate initial release together with reduced synthesis of monoamines in ischemic brain. The incidence of ischemia induced by carotid occlusion decreased from 44% to 26% in PCPA-treated animals, which also suggests that depletion of 5-HT available for neuronal release prior to the induction of ischemia may reduce stroke incidence by limiting impairment of collateral vasocapacitance. PCPA pretreatment did not influence the development of edema in the occluded hemisphere of ischemic animals once ischemia was established.

Animals↗
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Pathophysiological correlates of cerebral ischemia the significance of cellular acid base shifts.

In vivo 31-Phosphorus nuclear magnetic resonance (31PNMR) spectroscopy was used to study regional high energy phosphate, and phospholipid metabolism together with intracellular pH in patients with acute hemispheric ischemic stroke. The pH of ischemic brain progressed from acidosis to alkalosis. Acidosis was correlated with metabolic deterioration. Alkalosis was correlated with poor neurological outcome. Hyperglycemia worsened acidosis and metabolic breakdown. Therapeutic control of systemic glucose levels and cerebral acidosis should be evaluated in acute stroke.

Acid-Base Equilibrium↗
PubMedDate not supplied

Platelet as a model to test autonomic function in migraine.

In order to evaluate the role of the sympathetic autonomic nervous system (SANS) in common migraine we measured platelet catecholamine levels in a group of patients and in control subjects after 1 and 30 min of supine rest. Common migraine patients showed, at 1 min of supine rest, higher platelet norepinephrine (NE) content in comparison with the controls. This result may reflect a decreased release of platelet dense bodies in migraineurs. The same patients showed after 30' of supine rest a hardly significant increase of platelet NE levels in contrast to the clearly significant increase found in controls. These findings support the hypothesis of sympathetic hypofunction in migraine.

Adult↗
PubMedDate not supplied

Truncated analogues of endothelin and sarafotoxin are selective for the ETB receptor subtype.

The sarafotoxins (SRTXs) are a family of 21-amino acid bicyclic peptides that are structurally similar to the potent vasoconstrictors, the endothelins (ETs). SRTX-6c exhibits high selectivity for the ETB receptor subtype over the ETA subtype. This selectivity may be a result of a modification at positions 9 or 13, which are Glu9 and Asn13 in SRTX-6c and Lys9 and Tyr13 in ET-1. The truncated linear endothelin [Ala11,15]ET-18-21 was also on ETB receptor-selective ligand with 6-nM binding affinity. Therefore, a series of truncated endothelin/sarafotoxin (8-21) hybrid analogues were prepared, varying the amino acid at residues 9 and/or 13. These peptides were assayed for binding in tissues selectively expressing either the ETA or the ETB receptor subtypes. All linear analogues showed poor ETA binding, while ETB affinity was sequence dependent. Monocyclic 11-15 disulfide-containing analogues failed to bind to either ETA or ETB receptors at concentrations of up to 10 microM.

Amino Acid Sequence↗