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Biomedical subjects

M G Walker

Publications and source records attributed to M G Walker.

72 records · Page 4Linked to original sources
PubMedDate not supplied

Limitations of in-vitro labeling of endothelial cells with indium-111 oxine.

Indium-111 oxine labeling is widely used as a marker of endothelial cell attachment to vascular prostheses. The long term effect of labeling human adult endothelial cells (HAECs) with this isotope has not been determined. In this study the viability of labeled HAECs, leakage of isotope from labeled cells and adherence of circulating isotope to fibronectin coated prostheses were investigated over 24 h. The effect of incubation time on labeling efficiency was also assessed. There were significant differences in cell viability between the labeled and unlabeled groups beyond 4 h (p < 0.005, 2-tailed, unpaired t-test). In the control group cell numbers increased by 42% while in the labeled group this had decreased by 20% at 24 h. Spontaneous leakage increased with time but was maximal in the first 2 h. Adherence of circulating isotope to fibronectin coated expanded polytetrafluoroethylene (ePTFE) grafts was minimal but was significantly greater to gelatin impregnated Dacron (GEL-SEAL) beyond 1 hour (p < 0.05). Incubation times greater than 5 minutes during labeling do not significantly improve labeling efficiency, and may contribute to toxicity by prolonging exposure to oxine. Indium-111 oxine labeling of HAECs is a suitable technique for acute studies of endothelial cell kinetics up to 4 h, but its use in chronic studies may lead to significant underestimations of cell retention.

Bioprosthesis↗
PubMedDate not supplied

A functioning multichannel auditory nerve stimulator. A preliminary report on two human volunteers.

This paper is a brief progress report on our work with two volunteers, each with 4 electrodes placed in his auditory nerve. We are performing stimulation studies to find out if multielectrode stimulation is more effective as a communication aid than single-electrode stimulation, and to gain insights on stimulus coding of environmental sound using sophisticated digital signal processing techniques.

Audiometry↗
PubMedDate not supplied

Combined intravenous and oral pentoxifylline in the treatment of peripheral vascular disease. A clinical trial.

Sixteen patients with severe occlusive vascular disease of the lower extremities were randomised to receive a five day course of combined intravenous and oral Pentoxifylline followed by three months oral treatment only, or identical treatment with a matching placebo. Nine patients received active Pentoxifylline, and 7 placebo, Follow-up by regular clinical examination and haemoreological assessment revealed a marked improvement in claudication distance and an increase in red cell deformability in those receiving Pentoxifylline, there being no change in those receiving placebo. Although both of the above parameters were improved by the treatment, there did not appear to be a direct correlation between red cell deformability and claudication distance in individual patients. A combination of intravenous and oral Pentoxifylline therapy results in an increase in both claudication distance and red cell deformability, but the former may not te a direct consequence of the latter.

Administration, Oral↗
PubMedDate not supplied

A clinical trial of Gingkco Biloba Extract in patients with intermittent claudication.

Thirty-seven patients with stage 2 peripheral vascular disease were randomised to receive a six month course of Gingkco Biloba Extract (Tanakan) or matching placebo. Assessment, by claudication distance, A/B ratio, Doppler ankle pressure response to exercise together with recovery time, and a 10 cm analogue scale (LAS) estimation of maximal pain severity, was performed before treatment, and at 6, 12 and 24 weeks. LAS scores were significantly improved after 24 weeks in patients receiving EgB, but not placebo. Claudication distance was significantly increased by Egb. Although claudication distance also increased in the placebo group, this was not significant. A/B ratio and Doppler ankle responses to exercise did not show any significant change in either group at any time interval, nor did the post exercise recovery time. Gingkco Biloba Extract is a safe and effective method of improving walking distance and reducing pain severity in patients with intermittent claudication, although Doppler studies have failed to suggest any gross improvement in the perfusion of the ischaemic leg.

Double-Blind Method↗