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Biomedical subjects

R Dawson

Publications and source records attributed to R Dawson.

At least 163 records · Page 9Linked to original sources
PubMed1978

The effects of dietary nitrogen level on the collagen of rat skin.

1. Male rats of approximately 120 g body-weight were maintained on a commercial stock diet containing 204 g crude protein (nitrogen x 6.25)/kg, a hydroxyproline-free high-protein (HP) diet containing 200 g casein/kg as the only protein source, or a low-protein (LP) diet containing 40 g casein/kg. After 6 weeks on these diets half of each group was transferred to a non-protein (NP) diet and the experiment was continued for a further 6 weeks. Animals from each group were killed at 4 d, 3 weeks and 6 weeks after the transfer to the NP diet. 2. Throughout the experiment the urinary excretion of N, hydroxyproline and creatinine, and the content and solubility of the skin collagen were determined. 3. When compared with a control group killed at the beginning of the experiment the rats maintained on the LP diet showed an increase of 25% in total N content of the skin but collagen content increased by 100%. Rats transferred from the HP to the NP diet lost both N and collagen from the skin, but those transferred from the LP to the NP diet lost N but increased the collagen content by 42%. 4. Protein deprivation brought about marked changes in the solubility of the skin collagen, suggesting an increase in the rate of maturation of skin collagen.

Animals↗
PubMed1977

Fibrinolytic response to surgery. Labile and stable patterns and their relevance to post-operative deep venous thrombosis.

Fibrinolytic activity after elective abdominal surgery was studied in 53 middle-aged cancer-free patients. The pattern of their response demonstrated both stable and labile populations. In 10 of the 13 patients in whom fibrinolytic activity fell rapidly to below 5-6 units, deep venous thrombosis (D.V.T.) developed on the first postoperative day. This suggests that reduced fibrinolytic activity after operation is involved in the establishment of postoperative D.V.T. and that the incidence of early thrombosis could be reduced by enhancement of postoperative levels of fibrinolytic activity.

Clot Retraction↗
PubMed1976

Effect of intermittent compression of the arms on deep venous thrombosis in the legs.

Despite the presence of venostasis in the legs, intermittent compression of the arms during and after surgery reduced the incidence of deep venous thrombosis (D.V.T.) in the legs to half that in control patients and maintained blood fibrinolytic activity at preoperative values. It is suggested that the release of fibrinolytic activators is essential to the prophylactic action of pneumatic leggings.

Aged↗
PubMed1975

The effect of dieldrin-contaminated feed on rat hepatic microsomal epoxide hydrase and aryl hydrocarbon hydroxylase.

Adult male rats were exposed to dieldrin-contaminated rations. The hydroxylation of benzpyrene (AHH) and hydration of styrene oxide (EH) by the hepatic microsomal fraction were followed. At dieldrin levels of 5 to 25 ppm for one week, the EH activity increased from 19% to 115% above control levels respectively. Animals exposed to 25 ppm developed elevated EH activities after a few days, with a maximum increase of 2.5 times control levels after two weeks. AHH activity was not elevated over control levels at any dose or time studied. Slight but significant increases in levels of cytochrome P-450 were observed. Pentobartibal sleeping time was decreased to 61% of control levels after exposure to 20 ppm dieldrin-contaminated food for 7 days. Two days of intraperitoneal administration of technical grade dieldrin, analytical grade dieldrin and analytical grade aldrin gave similar increases in EH activity within this group. Again, no changes in AHH activity were seen.

Aldrin↗
PubMed1970

The deep end.

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Emergency Service, Hospital↗
PubMedDate not supplied

Reverse-phase separation and electrochemical detection of neuropeptides.

The reverse-phase separation of neuropeptides using isocratic conditions is described. Each component of the mobile phase was examined for its ability to influence the separation of complex mixtures of neuropeptides. Manipulation of buffer strength, pH, organic modifier and column type provided sufficient flexibility to resolve closely related neuropeptides. Amperometric detection of oxidizable amino acids in the peptide sequence of a number of endogenous neuropeptides proved suitable for the identification of peptide standards and quantification of neural lobe arginine vasopressin and striatal methionine enkephalin.

Animals↗