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Biomedical subjects

B Woodward

Publications and source records attributed to B Woodward.

At least 127 records · Page 7Linked to original sources
PubMed1972

Facilitation and inhibition of cell groups within the superior cervical ganglion of the rabbit.

1. The patterns of facilitation and inhibition of the S(a) and S(b) components of the post-ganglionic compound action potential after a single conditioning stimulus were different and dependent on stimulus parameters.2. With submaximal conditioning and test stimuli, the S(a) component showed a phase of early facilitation (40-75 msec after the conditioning stimulus) followed by a prolonged tail of facilitation. With maximal stimuli, early facilitation and late facilitation (700-2000 msec after the conditioning stimulus) were separated by a phase of inhibition or relative inhibition, most pronounced 100-300 msec after the conditioning stimulus.3. During early facilitation, a submaximal S(a) response was facilitated by 33.1 +/- 3.9%, while a maximal S(a) response was facilitated by 14.5 +/- 2.9%.4. Providing preganglionic C fibres were excited, facilitation of the S(b) component remained relatively constant for 40-500 msec after the conditioning stimulus, with no phase of inhibition.5. Early facilitation of submaximal S(a) responses was greatest when the conditioning stimulus excited about 50% of the preganglionic B fibres, but that of maximal responses was greatest when the conditioning stimulus excited all the B fibres. The preganglionic C fibres modulated facilitation of the S(a) component. Maximal facilitation of this component was associated with depression of the S(b) component.6. Submaximal S(a) responses are more strongly inhibited than maximal S(a) responses 200 msec after a conditioning stimulus. The C fibre pathway seems able to modulate the degree of inhibition of the S(a) ganglion cells.7. A neuronal model with divergent and convergent preganglionic B and C fibres supplying S(a) ganglion cells is consistent with the results. The preganglionic input is able to vary the size of the subliminal fringe. The S(b) component is in part due to the S(a) ganglion cells firing to their C fibre input.

Action Potentials↗
PubMedDate not supplied

Chemiluminescence measurements of xanthine oxidase and xanthine dehydrogenase activity in four types of cardiovascular cell.

The activity and location of xanthine oxidase (EC.1.2.3.2.) and xanthine dehydrogenase (EC.1.2.1.37) have been measured using luminol-enhanced chemiluminescence in four types of cell from the cardiovascular system (neonatal and adult rat cardiac myocytes, rat aortic vascular smooth muscle cells, rat cardiac fibroblasts and human umbilical vein endothelial cells). The detection system developed was both rapid and reproducible and could be used on sub-milligram quantities of cells. Xanthine oxidase was located primarily in cells derived from the vasculature and especially in endothelial cells, as was xanthine dehydrogenase. Only neonatal myocytes had more dehydrogenase activity than oxidase. The significance of the location and activity of these enzymes is discussed in relation to the pathology of myocardial ischaemia, arrhythmogenesis and microvascular disorders.

Animals↗
PubMedDate not supplied

Retroviral gene transfer into porcine keratinocytes following improved methods of cultivation.

We embarked on a program examining the application of cultured epithelial sheets to skin wounds in pigs using retroviral gene transfer as a means to follow the grafted cells. In the past similar studies have been hampered by an inability to grow porcine keratinocytes without seeding at an extremely high density. In this study we found that excellent results could be achieved with Opti-MEM-1 (Gibco BRL Life Technologies) containing 1 per cent foetal calf serum, 0.5 mM Ca2+ and no other growth factors or stimulants. Keratinocytes were plated on gamma-irradiated 3T3 feeders on surfaces which had previously been coated with rat tail collagen I. Keratinocyte cultures were established at a seeding density of 5 x 10(4) cm-2. The yield of cells from 1 cm2 of skin was sufficient to set up a 75 cm2 flask. Cultures reached 80-90 per cent confluence in 7-10 days, after which they were passaged 1:3 multiple times, taking 3-4 days to reach the same confluency. Allowing cultures to remain confluent for 1 week was sufficient to allow Dispase removal of an intact sheet. Using these techniques porcine keratinocytes were transduced at an average frequency of 25.3 per cent (+/- 14.0 SEM) with the retroviral vector MFG lacZ nls by growth on the gamma-irradiated retroviral producer line GP + envAm12.

Animals↗
PubMedDate not supplied

Medical record confidentiality and data collection: current dilemmas.

Author discusses current data collection and data disclosure practices that threaten medical record confidentiality. She raises concerns about the reidentification of ostensibly deidentified patient information and discusses measures for protecting confidentiality in a research setting.

Biomedical Research↗