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Biomedical subjects

R G Clark

Publications and source records attributed to R G Clark.

At least 127 records · Page 7Linked to original sources
PubMed1982

Effects of anti-oxytocin serum in Brattleboro rats.

Brattleboro rats were housed singly in metabolic cages and continuously infused with saline. Timed urine collections were analyzed for Na+ and K+; oxytocin (OT)-like material was estimated by RIA. OT infusions reduced urine flow and increased Na+ output. Urinary Na+/K+ ratios rose during OT infusion, falling below control values after infusion. Passive immunization with an OT antiserum reduced but did not prevent these renal effects of OT. In a second experiment, immunization had no effect on daily urine volume or Na+ output, even though high titers were achieved and excretion of endogenous OT-like material was reduced. We conclude that endogenous OT has little effect on Na+ excretion in these rats, although pharmacological doses of OT produced their known natriuretic effect.

Animals↗
PubMed1981

The influence of high and low sodium intakes on post-operative antidiuresis.

There remains some doubt over the influence of intravenous fluid and electrolyte therapy on the development of postoperative hyponatraemia. We believe the effect of varying sodium intakes on fluid balance during both the early antidiuresis phase and the later postoperative period has received insufficient emphasis. Therefore, the effects of intravenous regimens, containing either 450 mmol/24 h of sodium (saline group) or no sodium (dextrose group), on salt and water balance, plasma sodium and plasma water concentrations have been studied in two groups of 6 patients undergoing upper abdominal surgery. Hyponatraemia was not seen in the saline group but marked salt (+ 1023 mmol) and water retention (+ 3509 ml) were seen by day + 4. The dextrose group became relatively hyponatraemic (131.8 mmol/l) by day +1 but, following a phase of fluid retention during the 24 h following surgery, they developed negative fluid balance with some recovery of plasma sodium levels. This study confirms the importance of the sodium content of intravenous fluids both on the early development of hyponatraemia and on water and salt balance during the later postoperative period.

Adult↗
PubMed1980

Multiple atrial dysrhythmias in a horse.

A variety of atrial dysrhythmias including paroxysmal atrial tachycardia, atrial tachycardia with 2nd-grade atrioventricular block, atrial fibrillation, and atrial flutter developed in a 5-year-old Quarter Horse gelding. Quinidine and propranolol were not successful in restoring normal sinus rhythm. Sinus rhythm was re-established during digoxin therapy, but later reverted to atrial dysrhythmia. At necropsy, multiple, discrete pale areas were found on both atria and the interatrial myocardium. Histologic examination of these lesions demonstrated myocytolysis and replacement by fibrous connective tissue.

Animals↗
PubMed1980

Repair of digital flexor tendon lacerations in the horse, using carbon fiber implants.

Flexible medical grade carbon fiber was surgically implanted in tenectomized or lacerated superficial and deep digital flexor tendons of 13 horses (7 clinical cases and 6 experimental), ranging in age from 15 months to 10 years and weighing 300 to 500 kg. The 6 experimental horses were euthanatized at 30-, 45-, 60-, and 90-day intervals for gross and histologic evaluation of the results. Three of the experimental horses served as their own controls. Of the 7 clinically affected horses, 3 were euthanatized because they developed laminitis or the wound failed to heal. The remaining 4 horses in that group were discharged; 3 returned to their previous activities, and 1 was unavailable for follow-up. Carbon fiber produced a structure of approximately the same size and function as a normal tendon. Histologically, the fibroblasts and collagen fibers organized and aligned themselves in the early stages of healing. The implants appeared grossly and histologically to produce a cosmetically acceptable, strong, and functional tendon.

Animals↗
PubMed1980

Arterial hypertension and hypertrophic pulmonary osteopathy associated with aortic valvular endocarditis in a dog.

A 5-year-old spayed female Doberman Pinscher was referred for clinical evaluation following two acute episodes of lameness, lethargy, and respiratory dyspnea. The femoral pulse had a bounding "water-hammer" quality. Arterial blood pressures were 280 mm of Hg to greater than 300 mm of Hg during systole and approximately 40 mm of Hg during diastole. Systolic blood pressure was lowered to 210 mm of Hg, using prazosin. Radiography revealed extensive pulmonary interstitial markings and smooth subperiosteal expansions of the long bones indicative of hypertrophic pulmonary osteopathy. Despite symptomatic treatment, the dog's health gradually deteriorated, and it died 9 days after referral. Necropsy revealed vegetative endocarditis of the aortic valve. Insufficiency of the aortic valve was believed to be responsible for the systolic hypertension and the hypertrophic pulmonary osteopathy.

Animals↗
PubMed1978

Postoperative amino acid infusions: an appraisal.

Amino acid infusions either as a 7 per cent solution or as an isotonic 3.5 per cent solution produce a nitrogen-sparing effect in the postoperative period. The nitrogen-sparing effect is independent of the concentration and rate of infusion of the amino acid solution; or of any changes in plasma substrate and hormone concentrations. These solutions have no advantage over conventional intravenous therapy with isotonic glucose and saline solutions and there is no indication for their routine use in the management of postoperative patients.

Abdomen↗
PubMed1978

The treatment of perforated duodenal ulcer.

The prognosis of 189 patients with a perforated duodenal ulcer was analysed. There were three treatment groups, non-operative, simple closure and definitive ulcer surgery. The prognosis of the patients was analysed in terms of the chronicity of the ulcer. Perforations occurring in acute duodenal ulcers have an excellent prognosis, with similar results in each group in this series. All perforations of chronic duodenal ulcers should be treated by emergency surgery.

Acute Disease↗