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Biomedical subjects

R Shields

Publications and source records attributed to R Shields.

At least 55 records · Page 3Linked to original sources
PubMed1977

Ammonia absorption from the canine colon after portacaval shunt.

Ammonia absorption was studied from Thirty-Vella colon loops in 6 dogs. Four underwent an end-to-side portacaval shunt and it was shown that absorption of ammonia from the colon significantly increased postoperatively. Absorption of ammonia from various solutions was also measured before and after portacaval shunt and it was shown taht absorption was increased from a high pH solution and from a solution with a high bicarbonate content and reduced from a low pH, low osmolality and high osmolality solution. Increased deposits of stainable iron were demonstrated in the livers of dogs following portacaval shunt.

Ammonia↗
PubMed1977

Cells regulate their proliferation through alterations in transition probability.

The proliferation of 3T3, 3T6 and SV3T3 cells was examined by time lapse cinephotography under a number of different growth conditions. It was found that the frequency distributions of intermitotic times of cells with widely different proliferation rates are qualitatively and quantitatively explained by the transition probability model of the cell cycle (Smith and Martin, '73). The behaviour of quiescent cells was characterized by very low values of the transition probability. No "out of cycle" or GO compartment of cells was detectable. From a consideration of these results and those in the literature it appears that the rate of cell proliferation is determined by the value of the "transition probability" (P), and that it is the biochemical manifestation of this parameter that regulates cell growth in vitro and in vivo.

Animals↗
PubMed1976

Influence of staphylococcal enterotoxin on water and electrolyte transport in the small intestine.

The direct and indirect effects of staphylococcal enterotoxins A and C on the flux of water, sodium, and potassium have been studied in paired Thiry Vella fistulae in dogs. Administration of toxin resulted in a significant decrease in absorption, both in the loop to which the toxin had been administered and its pair. This decrease in absorption was associated with a decrease in movement out of the lumen, movement into the lumen remaining relatively unchanged. The mechanism of action of staphylococcal enterotoxins is discussed, and comparisons made with other enterotoxins.

Animals↗
PubMed1976

Effect of galactose and sugar substitutes on blood insulin levels in normal and obese individuals.

Eighteen male patients between the ages of 25 and 50 were given on a double blind randomized basis (A) 40 gms. galactose (B) 50 gms. arabinogalactan and 0.11 gm. sodium saccharin (C) 2 gm. methyl cellulose and 0.083 gm. sodium saccharin and (D) 4 gm. galactose, all in 200 ml water. Blood glucose, galactose and insulin levels were determined during a six hour period before and after ingestion. The three first mentioned solutions tasted equally sweet, the fourth was essentially tasteless. None of these feedings altered plasma insulin or glucose levels. It appears that in contrast to other conclusions reached by earlier investigators sweet taste is unable to induce insulin secretion through neurogenic pathways.

Adult↗
PubMed1975

Clinical and experimental studies on adenine, various nucleosides and their analogs in hematology.

In red blood cells as well as in platelets there appears to be a decrease in adenine nucleotides during storage under blood bank conditions. This can be decreased by use of anticoagulant preservatives with higher phosphate content than the standard ACD solution, through the addition of adenine and inosine. Maintenance of higher ATP levels appears to be related to longer circulating life span after transfusion into patients in the case of red blood cells but not platelets. Inosine and more alkaline preservative medium also contribute to the maintenance of 2,3-DPG levels in red blood cells, and with it to the maintenance of normal hemoglobin dissociation curves and thus oxygen-carrying capacity. Certain nucleoside analogs may contribute to the preservation of platelets and of whole blood by their platelet-aggregation inhibitory activity. Platelet-aggregation inhibitors may also be useful in preventing thromboembolic episodes with potentially greater safety than anticoagulants.

Adenine↗
PubMed1975

The effect of raising the concentration of potassium in the blood or intestinal lumen on the transport of potassium in the dog intestine.

The rates of transport of potassium, sodium and water across the intestinal mucosa of Thiry-Vella fistulas of colon and ileum, were studied in dogs in two experimental situations; (1) following intravenous infusion of potassium (15 mEg) over 30 minutes and (2) during variations in the intraluminal concentration of potassium in the range 0.8-16.0 mEg/l. Following intravenous infusion of potassium the rates of potassium secretion into the colon were usually increased; the rates of sodium and water absorption were either unchanged or decreased. The unidirectional rate of movement of potassium into the lumen increased as the concentration difference across the mucosa increased; the movement of potassium in the opposite direction remained relatively constant. The undirectional movement of sodium and water into the lumen of the colon also increased but to a lesser extent. The effect on potassium transport in the ileum was not so marked. With increase in the intraluminal concentration of potassium there was a decrease in the rate of net potassium secretion in both colon and ileum. The rates of net absorption of sodium and water were not significantly altered. Unidirectional potassium movement into the body increased in all the ileal fistulas.

Animals↗
PubMed1975

Controlled clinical trial comparing early with interval cholecystectomy for acute cholecystitis.

The traditional management of acute cholecystitis is initial conservative treatment with antibiotics followed by elective cholecystectomy. Although early cholecystectomy has often been advocated, there has been only one randomized controlled clinical trial comparing the two methods of treatment. This paper reports the preliminary results of such a trial in which 32 patients have been studied so far. Of the 17 patients managed conservatively, there was a misdiagnosis in 2 (11-8 per cent). In the remaining 15 patients with acute cholecystitis 3 (20 per cent) required urgent operation because of failure of medical treatment. Elective cholecystectomy was not technically difficult. Of the 15 patients treated by early cholecystectomy, there was a misdiagnosis in 1 (6-8 per cent). Surgery was technically difficult in 2 patients but cholecystectomy was possible in all. The former 2 patients required blood transfusion, but in the remainder the estimated blood loss was only slightly more than in the elective group. There was no mortality in either group nor any complication directly attributable to the biliary surgery. The incidence of minor postoperative complications was only slightly greater in those treated by early operation. The length of postoperative stay was similar in both groups but those treated conservatively spent an average of 11 more days in hospital. The preliminary results indicate that those treated by early cholecystectomy spend less time in hospital and avoid the complications of failed conservative treatment without the added risk of increased postoperative mortality and major complications.

Acute Disease↗
PubMed1975

Postprandial osmotic and fluid changes in the upper jejunum after truncal vagotomy and drainage in man.

The changes in osmotic pressure and the degree of marked dilution in the jejunal lumen after a hypertonic meal, have been studied in patients after truncal vagotomy and drainage, with and without diarrhoea, using an intraluminal intubation technique. The results suggest that neither the emptying of a hyperosmotic load from the stomach, nor its subsequent dilution in the jejunum have an important role in post-vagotomy diarrhoea.

Chromium Radioisotopes↗