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Biomedical subjects

T Burton

Publications and source records attributed to T Burton.

4 recordsLinked to original sources

Effects of cicletanine on haemodynamics, arrhythmias and extent of necrosis during coronary ligation in rabbits.

1. The effects of cicletanine on arrhythmias, haemodynamics and extent of necrosis during myocardial ischaemia were investigated in rabbits subjected to coronary ligation. 2. Cicletanine increased cardiac output prior to coronary occlusion (P < 0.01) but had no other significant haemodynamic effects at this time and did not significantly alter heart rate, blood pressure or cardiac output during 30 min of ischaemia or 30 min of reperfusion. 3. Ventricular fibrillation and mortality were greater in control (65% and 60% respectively) than treated animals (15.4% and 15.4%, P < 0.01). 4. The extent of myocardial necrosis expressed as a percentage of the area at risk was also reduced by cicletanine from 61 +/- 8% in controls to 37 +/- 6% (P < 0.05). 5. These findings indicate that cicletanine attenuates arrhythmias and preserves myocardium in the early phase of ischaemia and this effect appears to be independent of an established antihypertensive action.

Animals

Discordant segregation of Na+,K(+)-adenosine triphosphatase alleles and essential hypertension.

OBJECTIVES: To determine whether the alpha 2 and or beta 1 isoforms of the Na+,K(+)-adenosine triphosphatase (Na+,K(+)-ATPase) are involved in the pathogenesis of essential hypertension. DESIGN: Segregation analysis of polymorphic DNA markers was used to test the involvement of Na+,K(+)-ATPase in essential hypertension. PARTICIPANTS: Children with persistent hypertension having one parent with essential hypertension were included in the study. Criteria for persistent hypertension were blood pressure readings with systolic and/or diastolic levels exceeding the 95th percentile based upon age and sex. The diagnosis of hypertension for adults, including parents and older siblings, was confirmed using criteria recommended in the 1988 report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure. RESULTS: In three essential hypertensive families consisting of 18 members including 11 hypertensives, several obligate recombinants between the Na+,K(+)-ATPase alpha 2 isoform marker and the hypertension phenotype were observed. Similarly, in one hypertension family consisting of four members, obligate recombinants between the beta 1 isoform marker and the disease were observed. CONCLUSIONS: The discordant segregation of the alpha 2 and beta 1 isoform markers and essential hypertension suggests that neither the Na+,K(+)-ATPase alpha 2 nor beta 1 isoform genes play a primary role in the pathogenesis of hypertension in the families studied.

Adult

Aortic smooth muscle cells express and secrete vascular endothelial growth factor.

We examined whether cultured bovine aortic smooth muscle (ASM) cells express VEGF. RNA blot analysis of total cellular RNA derived from ASM cells demonstrates the expression of the VEGF gene. ASM cells release in the medium a VEGF-like endothelial cell mitogen which binds to heparin-sepharose and has an apparent molecular weight of 40-45 kDa as assessed by an HPLC gel filtration column. Consistent with VEGF, this mitogen does not stimulate the proliferation of ASM cells. Immunoblot analysis of the bioactive material with an antibody specific for VEGF demonstrates the presence of a major immunoreactive band with an apparent molecular mass of 23 kDa and a minor band with a molecular mass of approximately 18 kDa, in reducing conditions. The major band has very similar apparent molecular weight as the 165 amino-acid species of human recombinant VEGF of folliculo-stellate cells derived VEGF. These data demonstrate the expression and synthesis of VEGF by cultured ASM cells and suggest that the 164 amino-acid species is the predominant molecular form of the growth factor secreted by such cells. VEGF released by ASM cells may play a paracrine role in the maintenance of the integrity of the endothelial lining or in the abnormal proliferation of the vasa vasorum which takes place in atherosclerosis.

Animals