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Biomedical subjects

R I Woods

Publications and source records attributed to R I Woods.

At least 19 recordsLinked to original sources
PubMed2003

A note on the fetal-infant mortality problem.

This paper considers the age pattern of mortality between conception and first birthday. It highlights the various problems that still limit our understanding of the ways in which the age components of mortality are associated, especially during the perinatal period. A mathematical function is fitted which captures the interaction between six mortality components for a typical high mortality society, one in which the infant mortality rate is 150 per thousand live births. This experiment helps to clarify the need to link infant with fetal mortality, to conduct further research on the level of risk in each component, and to consider the cumulative early-age mortality profile in its entirety.

Fetal Death↗
PubMed1992

Hypertrophy of rat extensor digitorum longus muscle injected with bupivacaine. A sequential histochemical, immunohistochemical, histological and morphometric study.

Histochemical, immunohistochemical, histological and morphometric properties of bupivacaine-injected rat skeletal muscle were studied at times spanning the complete course of degeneration and regeneration to establish when, if ever, 'normality' is reached. This was achieved in a sequence of measurements made on the same series of rat fast-twitch extensor digitorum longus muscle (EDL), of the fibre type composition, myosin heavy chain content, fibre size, connective tissue content and myofibril size at 1-2 h and 2, 4, 8, 11, 21, 40, 60, 80 and 180 d after treatment. By 2 d after injection 86% of the fibres had undergone necrosis. A rapid restoration of histochemical, immunohistochemical and morphometric properties then occurred, being apparently complete by 21 d after injection. A pattern of ongoing changes recognised when regeneration was essentially 'complete' are reminiscent of changes that occur in muscles following compensatory hypertrophy produced by synergist ablation. These changes included an increase in muscle weight, a decline in normalised peak twitch and tetanic tensions, and normalised force in response to different stimulation frequencies (Rosenblatt, 1992), an increase in the relative number of type I fibres and of fibres reacting with the slow myosin heavy chain antibody, an increase in whole muscle cross-sectional area, an increase in type I and type II fibre cross-sectional area and diameter, an increase in myofibril cross-sectional area, density, number, and area fraction, and an increase in the relative proportion of intramuscular connective tissue collagen. This suggests that the EDL muscle is being made to do more active work and is being influenced by passive forces (stretch) imposed on it. These changes appeared permanent: they stabilised at about 60 d after injection and were maintained for at least the next 120 d.

Animals↗
PubMed1982

A new morphological procedure for viewing microvessels: a scanning electron microscopic study of the vasculature of small intestine.

The present study details a new method for the exposure and viewing of individual microvessels located within the small intestine of rats. This procedure will selectively and consistently remove the outer muscle layers and underlying submucosa of the intestinal wall and thereby expose a variety of arterioles in their normal location within the tissue, with their normal relationship to each other undisturbed. The small intestine of the rat was initially fixed by vascular perfusion with 2.5% glutaraldehyde in 0.1 M cacodylate/HCL buffer, reinfused with heparinized whole blood, removed from the animal, and secured to a dissecting petri dish for further fixation. Subsequently, the external muscularis was dissected from the sample which exposed the submucosa. In order to remove the connective tissue elements from this layer and uncover the submucosal vasculature, the samples were first transferred to a solution of 30% potassium hydroxide for 2-5 minutes and then to a final digesting solution containing collagenase. Thereafter, the samples were routinely processed for light microscopy and for scanning (SEM) or transmission (TEM) electron microscopy. Examination of the samples revealed excellent preservation of the three-dimensional organization of the arteriolar wall with minimal membrane damage. This new technique now makes it possible to visualize the shape and position of individual smooth muscle cells along arterioles of differing size and branching order.

Animals↗
PubMed1977

Changes in sizes of the adrenaline-containing vesicles and their cores in frog cardiac sympathetic nerves after pharmacological treatments.

The sizes of adrenergic vesicles and their cores, as made visible by an acrylic aldehyde in sodium dichromate fixative, have been measured in electron micrographs of the sympathetic nerves amongst the frog's ventricular muscle. The animals were either normal or previously treated with drugs expected to affect the catecholamine content of the heart. The sympathetic nerves contain two overlapping populations of vesicles. A graphical method was used to separate these and determine the mean diameter of each population. The distribution of vesicles between the 'large' and 'small' populations is variable in normal animals. No changes could be detected in the experimental animals. The mean size of the 'large' vesicles is variable in normal animals. No changes could be detected in the experimental animals. Four injections of 5-hydroxydopamine caused a 5.8% increase in the diameter of the 'small' vesicles. No other treatment produced significant changes in vesicle size. Four injections of 5-hydroxydopamine caused a 50% increase in the diameter of the cores of the 'small' vesicles. Two injections of reserpine caused a 20% reduction in the diameter of the visible cores in the 'small' vesicles, and 34% of the vesicles lost their cores entirely. One injection of 6-hydroxydopamine or ten injections of alpha-methyl-tyrosine caused small reductions in 'small' core diameter. It is postulated that core formation in adrenergic nerves under these conditions is not solely dependent on their catecholamine content, but on this and another factor which may be part of the storage complex.

Animals↗