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Biomedical subjects

G E Thompson

Publications and source records attributed to G E Thompson.

At least 73 records · Page 4Linked to original sources
PubMed1978

Acute cold exposure and the metabolism of glucose and some of its precursors in the liver of the fed and fasted sheep.

Measurements of total body oxygen consumption, visceral and hepatic blood flow, oxygen consumption, exchanges of amino acids, lactate, pyruvate and glucose were made on sheep fed 3--6 h or 21 h before the experiment and exposed for 3 h to a neutral environment (15 degrees C) or a cold environment (0.5 to 4 degrees C with clipped coat and wind speed 2 m.s-1). Recent feeding significantly increasedd the total oxygen consumption and the oxygen consumption of the viscera and liver. No general release of amino acids from the viscera or uptake by the liver after feeding was detected although the arterial plasma concentration of essential amino acids did increase significantly after feeding. The plasma concentration of most non-essential amino acids also increased except that of glycine, which decreased significantly. Cold exposure increased the total oxygen consumption and reduced the respiratory quotient significantly. Release of amino acids from the viscera was stimulated by cold exposure. There was a variable increase in the hepatic uptake of lactate and alanine when the sheep were fasted and cold-exposed. The liver's glucose output doubled and the blood (arterial) glucose concentration significantly increased in the cold.

Amino Acids↗
PubMed1978

Hypotensive anesthesia for total hip arthroplasty: a study of blood loss and organ function (brain, heart, liver, and kidney).

The authors attempted to determine whether hypotensive anesthesia or the method of inducing hypotension has any effect on postoperative brain, liver, or kidney function and myocardial status following total hip arthroplasty. Thirty patients were anesthestized with halothane-nitrous oxide for total hip arthroplasty and randomly assigned to one of three groups. In two groups mean arterial blood pressure was decreased to 50 torr by high inspired concentrations of halothane (n = 90) or sodium nitroprusside (n = 12). In the third group (n = 9) mean blood pressure was maintained within 20% of control. Intraoperative blood losses decreased from 1,183 +/- 172 ml in the normotensive group to 406 +/- 102 ml and 326 +/- 41 ml in the halothane and nitroprusside hypotensive groups, respectively. Neither method of inducing hypotension nor hypertensive technique affected the results of postoperative tests of cerebral, hepatic, or renal function and myocardial status. These tests were performed before anesthesia and operation and at intervals in the postoperative course. In this small group of patients, deliberate hypotension for total hip arthroplasty added no morbidity and significantly shortened operating time, decreased blood loss, and decreased the number of blood transfusions needed.

Aged↗
PubMed1977

Factors determining dosages of amide-type local anesthetic drugs.

The physical status of the patient (sex, age, weight, height, and underlying disease) has been thought to influence the dosage of local anesthetic drugs that can be injected without causing a systemic toxic reaction, but this belief is not supported by statistically significant data. Furthermore, previous studies of plasma levels of bupivacaine and mepivacaine showed no correlation between dosage and physical status, even when maximum dosages recommended by pharmaceutical companies were exceeded. This study of 9,287 regional blocks, using the statistical tests of multiple regression and chi square, substantiates that the occurrence of systemic toxic reactions in adults does not correlate with dosages and/or physical status of the patient when 400 mg or less of bupivacaine, 450 mg or less of etidocaine, or 500 mg or less of mepivacaine is used. Therefore, the study questions the maximum dosages established for certain local anesthetic drugs, as well as the method by which such dosages were established.

Anesthesia, Epidural↗
PubMed1977

Bupivacaine (Marcaine): an evaluation of its tissue and systemic toxicity in humans.

In countries other than the U.S.A., dosages of bupivacaine have been limited to 100 mg without epinephrine and 150 mg with epinephrine. A review of 7,688 regional block procedures employing bupivacaine in concentrations of 0.25, 0.5, and 0.75%, and in dosages as high as 600 mg, indicated that such stringent restrictions: (1) are unwarranted, (2) make comparisons with other local anesthetic agents difficult, and (3) are in need of revision.

Adolescent↗
PubMed1977

Effect of cold exposure on mammary circulation oxygen consumption and milk secretion in the goat.

1. Measurements of milk secretion, mammary oxygen consumption and blood flow, cardiac output and blood pressure have been made in lactating goats exposed to a thermoneutral environment and to two levels of cold stress which were sufficient to raise total body oxygen consumption by an average of 18 and 46% above that in a thermoneutral environment. 2. Mammary blood flow and oxygen consumption were not appreciably affected by the milder cold stress but fell to 63 and 70%, respectively, of their thermoneutral value in the moderately cold environment. Resistance to blood flow through the udder was increased by this level of cold stress and the gland took a smaller fraction of an increased cardiac output. 3. Both levels of cold exposure caused a reduction in milk secretion, to 80 and 40% of its thermoneutral value in the mild and moderate cold respectively. The amount of milk secreted per unit volume of blood flowing through the gland decreased as the severity of the cold stress increased. 4. Voluntary food intake was not affected by the change in environmental temperature but the intake of water was reduced to 55% of the thermoneutral value during mild cold exposure and to 40% of the thermoneutral value during the moderate cold stress. 5. It is concluded that a reduction in blood flow to the mammary gland could be one of several possible mechanisms underlying the depression of milk secretion during cold exposure.

Animals↗
PubMed1977

Resistance to toxaphene by the Bont tick, Amblyomma hebraeum (Koch).

A series of in vitro and in vivo trials confirmed resistance by the three-host Bont tick, Amblyomma hebraeum (Koch), to Toxaphene in the Cape, Natal and Transvaal Provinces of the Republic of South Africa, and in Swaziland and Transkei. Resistance was present in 80 of 97 field strains examined. Lindane and DDT resistance was present in the one field strain tested. The results of comparative in vivo hand spraying and plunge dipping trials confirmed those of the larval in vitro tests, thus validating the usefulness of this latter technique for identifying changes of susceptibility in field tick strains to ixodicides. Selection of Toxaphene resistance in A. hebraeum occurred within a period of four years when a 14-day interval of treatment was used continuously. The presence of all three tick instars in all stages of engorgement at the time of each treatment under this regimen is thought to have enhanced this selection.

Drug Resistance↗
PubMed1976

The distribution of blood flow between individual muscles and non-muscular tissues in the hind limb of the young ox (Bos taurus): values at thermoneurality and during exposuer to cold.

1. The radioactive microspheres method was used to measure the distribution of blood flow in the hind leg in conscious young steers exposed to thermoneutral and moderately cold environments. Simultaneous measurement of total leg blood flow allowed calculation of blood flow (ml. 100 g tissue-1 min-1) to individual muscles and the major non-muscular tissues in the leg. 2. In the thermoneutral environment, leg blood flow was distributed approximately according to tissue weight, so that about 65% went to muscle and the remainder to bone, skin, connective tissue and fat; 1-7-11-5% of the injected dose of microspheres was found in the lungs, indicating the presence of functioning arteriovenous anastomoses in the leg. 3. During cold exposure leg blood flow increased two-and-a-half fold and 91% of this increase was due to increased blood flow in muscle. This was accompanied by substantial decreases in both total and capillary blood flow in leg skin in three of the four animals. 4. Values for resting tissue blood flow to the six largest individual leg muscles were compared, as well as that for tissue blood flow to the remaining leg muscle. Blood flow in the three large upper thigh muscles (biceps femoris, semimembranosus and semitendinosus) was about half that in muscles in the rest of the leg. 5. Cold exposure caused a threefold increase in total leg muscle blood flow, but the only individual muscles to respond substantially in all four animals were the vastus lateralis and the rectus femoris. Comparison of results from individual animals suggested a relation between total leg blood flow and the number of muscles (apart from vastus lateralis and rectus femoris) involved in shivering. Leg adipose tissue blood flow also increased significantly in the cold.

Adipose Tissue↗
PubMed1975

Acute cold exposure and the metabolism of blood glucose, lactate and pyruvate, and plasma amino acids in the hind leg of the fed and fasted young ox.

1. Young steers were fed either 3-4 or 20 h before exposure to a thermoneutral or a moderately cold environment. Measurements were made of total oxygen consumption (total V 0-2), respiratory quotient (rq), blood packed cell volume (PCV), and hind-leg blood flow (leg Q) and oxygen uptake (leg VO-2). The arteriovenous differences in whole blood glucose, lactate and pyruvate, and individual amino acid and urea concentrations across the leg were also measured. Net exchange and fractional uptake of these metabolites by the leg were calculated from these results. 2. Cold exposure doubled total VO-2, significantly decreased RQ and significantly increased PCV. Leg Q and leg VO-2 increased 3- to 5-fold and 4- to 13-fold respectively in both feeding groups. Arterial blood glucose increased slightly but significantly in both 20 h- and 3 h-fed steers. There was a substantial increase in mean net leg uptake of glucose in both feeding groups. This was much greater in the 20 h-fed group because of the significant increase in fractional uptake occurring only in this group. Cold did not significantly affect arterial blood lactate or pyruvate levels, but the net leg output of lactate found in both feeding groups in thermoneutrality was increased in the 20 h-fed steers, and reversed to a net uptake in the 3 h-fed animals. Cold caused a small but significant decrease in the total plasma amino acid level in the 20 h-fed but not in the 3 h-fed group; individual amino acid levels or leg uptakes were not affected. 3. Feeding before the experiment caused a significant increase in RQ. Leg Q, leg uptake of glucose and leg output of lactate increased after feeding in the thermoneutral environment only. Arterial pyruvate increased significantly, but net leg output was not significantly affected by feeding. Arterial plasma concentration of several individual, but not of total amino acids, increased significantly in both environments, and the net output of many individual amino acids in the 20 h-fed steers was decreased or reversed to a net uptake in the 3 h-fed group in thermoneutrality only. 4. The results suggest that blood glucose could be a significant fuel for oxidation in shivering skeletal muscle in young steers, and that output of amino acids from skeletal muscle could not contribute significantly to this increased glucose supply by hepatic gluconeogenesis.

Acclimatization↗
PubMed1975

Changes in the metabolism of the shivering hind leg of the young ox during several days of continuous cold exposure.

The effect of 4 days of continuous exposure to a cold environment on blood flow in, and oxygen and energy substrate uptake by the shivering hind leg has been studied in young steers. The animals shivered throughout the period of cold exposure and total oxygen consumption (total VO2) remained 40-50% greater than VO2 during thermoneutrality. Leg blood flow (leg Q) and oxygen uptake (leg VO2) increased two- and four-fold respectively on the first day of cold. Both had declined significantly by the final day, leg Q to a level 37% greater than, and leg VO2 to about double, pre-cold levels. The change in the relationships of leg Q and leg VO2 to total VO2 was examined by linear regression analysis, which suggested that the changing contribution of leg VO2 to total VO2 was entirely due to changes in leg Q, rather than in the arteriovenous difference in blood oxyhaemoglobin saturation across the leg. The net uptakes by the leg of free fatty acids (FFA), acetate, glucose and lactate all increased on the first day of cold. Both glucose and acetate uptakes were greater on day 4 than on day 1 in the cold, in spite of the lower leg VO2, but net uptakes of FFA and lactate were considerably lower. The decrease in net uptake of FFA is attributed mainly to an increase in the rate of lipolysis and release of FFA from fat depots in the leg, because of the associated progressive increase in the release of glycerol and oleic acid from the leg. The molar ratios of net carbohydrate substrate, acetate and FFA uptakes to leg VO2 are compared. The results suggest that tissues other than the leg muscles become increasingly important as sites of heat production, and that there are changes in the utilization of glucose, acetate and FFA by shivering muscle, during prolonged cold exposure.

Acetates↗
PubMed1975

The hepatic uptake of individual free fatty acids in sheep during noradrenaline infusion.

Hepatic portal and arterial blood flow and the net hepatic uptake of individual free fatty acids (FFA) were measured in sheep during intravenous infusions of saline and noradrenaline (2 mu kg-minus 1 min-minus 1). During noradrenaline infusion in FFA increased in the circulating (arterial) plasma in amounts oleate greater than palmitate greater than stearate. Changes in the hepatic uptake of FFA opposed these changes in plasma FFA composition; the hepatic uptake of oleate increased more than that of palmitate, and the uptake of stearate fell slightly, but not significantly.

Animals↗