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Biomedical subjects

A W Goode

Publications and source records attributed to A W Goode.

At least 73 records · Page 4Linked to original sources

Carnitine metabolism in livers and hearts of 48h-starved rats: the contribution of fat and carbohydrate to acylcarnitine formation.

The work investigated the effects of administration of 2-tetradecylglycidate (TDG), an inhibitor of mitochondrial long-chain fatty acid oxidation, alone or in combination with glucose, on concentrations of free and acylated carnitine in livers and hearts of 48 h-starved rats. The only significant effect of TDG in the heart was to decrease [short-chain acylcarnitine]. This demonstrates that in heart, fat oxidation is linked to the formation of short-chain acylcarnitine. Cardiac [short-chain acylcarnitine] was not significantly decreased by TDG if the rats were also administered glucose, suggesting that acyl CoA derived from glucose may be used for short-chain acylcarnitine formation in TDG-treated rats. TDG significantly decreased in [free carnitine]. No changes in [short-chain acylcarnitine] were observed. This indicates that formation of short-chain acylcarnitine in liver is not determined by the rates of fat oxidation. It was calculated that at least 63% of the acyl-groups esterified to carnitine were generated by intramitochondrial beta-oxidation. The effects of glucose and TDG on hepatic concentrations of free and long-chain acylcarnitine were additive, suggesting that extramitochondrial fat oxidation can contribute to acylcarnitine formation in liver.

Animals↗

Effect of hyperthyroidism on hepatic lipogenesis in rats: studies in vivo and in vitro.

Lipogenic rates (measured with 3H2O) in hepatocytes from fed or starved euthyroid rats were similar in magnitude to those measured in livers in vivo. Hepatic lipogenesis in vivo in fed triiodothyronine (T3)-treated rats was greater than in fed control rats, but rates in vitro were only 16% of those of control rats. It is concluded that hepatic lipogenesis in vivo in T3-treated rats utilizes precursors from extrahepatic tissues. Glycogen depletion of hepatocytes from fed control rats decreased lipogenesis, and rates were then similar to those in hepatocytes from fed T3-treated rats. Addition of lactate (2 mmol/l) and pyruvate (0.2 mmol/l) had little stimulatory effect on lipogenesis in hepatocytes from fed control rats, but increased lipogenesis in glycogen-depleted hepatocytes (by 86%), hepatocytes from starved rats (by 25%) and hepatocytes from T3-treated rats (by 60%). In the presence of lactate and pyruvate, 3-mercaptopicolinate (3-MPA) (an inhibitor of gluconeogenesis) did not affect lipogenesis in hepatocytes from fed control rats but substantially increased lipogenesis in hepatocytes from starved euthyroid rats or fed hyperthyroid rats. Thus, in hepatocytes from starved euthyroid rats or fed hyperthyroid rats gluconeogenesis competes with lipogenesis for available precursors (lactate and pyruvate). In contrast, in fed rats carbon flux is predominantly towards lipogenesis. Effects of 3-MPA in the presence of lactate and pyruvate were much less in glycogen-depleted cells from fed rats than in hepatocytes from starved or T3-treated rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Measurement of total body nitrogen and oxygen by irradiation with cyclotron neutrons and 'delayed' gamma ray counting.

Measurement of total body nitrogen is assuming increasing importance in the nutritional evaluation of seriously ill patients. Nitrogen has been previously measured either by counting (i) the annihilation radiation from 13N immediately after neutron irradiation with 14 MeV neutrons or (ii) the 'prompt' gamma rays from thermal neutron capture by 14N during irradiation with 14 MeV neutrons or with those produced by isotopic sources or a cyclotron. The present work describes studies into the feasibility of measuring 13N produced by irradiation with a neutron beam from the MRC Cyclotron. A complication of this method is that 13N is also produced in a reaction with 16O. Direct measurement of oxygen by use of the reactions 16O(n, p)16N or 16O(n, 2n)15O enables this interference to be estimated. The former reaction is possible with both 14 meV and cyclotron-produced neutrons but the 7.1 s half-life of 16N requires detectors to be placed in or very close to the irradiation site. In our particular circumstances this is not possible but the more energetic cyclotron neutron spectrum allows the production of 15O which has a half-life of 2.05 min and can be measured in a remote whole-body counter. A disadvantage with the cyclotron beam, in comparison with 14 MeV neutrons, is that a higher dose is required for similar accuracy. A reproducibility of about 4% is obtained with a dose equivalent of 0.01 Sv.

Body Composition↗

Effects of hyperthyroidism on stimulation of [1-14C]oleate oxidation to 14CO2 in isolated hepatocytes from fed rats by the catecholamines, vasopressin, and angiotensin II.

Possible effects of adrenaline, noradrenaline, vasopressin, and angiotensin II to increase 14CO2 production from [1-14C]oleate were examined in hepatocytes from fed L-triiodothyronine (T3)-treated or control rats. Rates of 14CO2 production were decreased and rates of ketogenesis increased in hepatocytes from T3-treated rats. These changes were accompanied by a marked shift of the 3-hydroxybutyrate:acetoacetate concentration ratio towards acetoacetate. Rates of glucose and lactate release were decreased. Whereas the Ca2+-mobilizing hormones increased 14CO2 production from [1-14C]oleate by 64-84% with hepatocytes from control rats, they increased 14CO2 production from [1-14C]oleate by on 24-32% with hepatocytes from T3-treated rats. The magnitude of the response to the Ca2+-mobilizing hormones in hepatocytes from T3-treated rats was increased by the addition of 3-mercaptopicolinate, an inhibitor of phosphoenolpyruvate carboxykinase, to the incubation medium (increases of 52-88%). In the presence of 3-mercaptopicolinate, the 3-hydroxybutyrate:acetoacetate concentration ratio in hepatocytes from fed, T3-treated rats was similar to that in hepatocytes from control rats in the absence of 3-mercaptopicolinate. The results demonstrate that hyperthyroidism per se does not lead to a loss of sensitivity, in terms of oleate oxidation, either to the catecholamines or to vasopressin and angiotensin II. The impaired ability of hepatocytes from T3-treated rats to respond to these hormones is a consequence of decreased net glycolytic flux or a more oxidized mitochondrial redox state.

Angiotensin II↗

Early time course of the acute phase protein response in man.

The rate at which the acute phase protein response occurred after both major and minor surgery was explored. Increases in the plasma concentration of C-reactive protein (CRP), alpha-1-acid glycoprotein (alpha 1 AG) and fibrinogen were not detected until 6-8 h after the initial incision. The peak concentration of CRP occurred at 48 h and that of fibrinogen at 96 h; alpha 1 AG concentrations rose rapidly until 48 h followed by little change until about 120 h. Although there was widespread variation in the concentrations of individual proteins in patients, severity of injury did not seem to have a significant effect on the time course of the change. Plasma cortisol concentration and the total white blood cell count (WBC) reached their peaks before the acute phase proteins, cortisol at 6 h and WBC at 12 h.

C-Reactive Protein↗

Purgative abuse associated with reversible cachexia, hypogammaglobulinaemia, and finger clubbing.

Laxative abuse may cause systemic and metabolic changes, but cachexia has not been reported as a predominant feature. A patient with finger clubbing and extreme wasting recovered when senna intake was stopped and nutritional care provided. A diagnosis had been made of acquired common variable hypogammaglobulinaemia with absence of circulating B lymphocytes. The immunological abnormalities were corrected after senna intake was stopped and lean body mass restored.

Agammaglobulinemia↗

The effect of surgery with carbohydrate infusion on circulating triiodothyronine and reverse triiodothyronine.

The blood levels of thyrotrophin (TSH), thyroxine (T4), triiodothyronine (T3), and reverse triiodothyronine (rT3) were measured in a group of patients undergoing cholecystectomy and receiving 2000 kcal of glucose daily throughout the study. TSH changes suggested a peroperative peak followed by a fall and subsequent rise. T4 showed no significant changes. T3 fell and rT3 rose postoperatively, with a highly significant fall in the T3/rT3 ratio (p less than 0.001). Surgery and carbohydrate deprivation separately result in similar changes. However, the demonstration of the changes after injury despite adequate carbohydrate intake strongly suggests that they are a primary response to surgery and not a secondary response to the normal consequential fall in caloric and carbohydrate intake. The changes could be an appropriate adaptation to the changed metabolic requirements.

Adult↗

Nutritional status of patients undergoing valve replacement by open heart surgery.

In 10 patients undergoing heart-valve replacement with cardiopulmonary bypass total-body potassium was measured non-invasively with a whole-body monitor, and this measurement was used to derive the lean body mass as an index of the nutritional status. From measurements made before operation and on the 7th postoperative day, the metabolic response to surgery was found to be equivalent to a negative nitrogen balance of 10.8 g of nitrogen a day (50% greater than that calculated from conventional nitrogen-balance studies). 4 patients had a mean preoperative potassium depletion of 17.2%, and this was associated with increased morbidity. Well-nourished patients had a mean postoperative hospital stay of 16 days, whereas those in a depleted state before operation had an increased morbidity, as measured by their mean postoperative stay of 30 days. More attention needs to be given to the preoperative nutritional status of patients undergoing heart-valve replacement.

Cardiopulmonary Bypass↗

The skeleton in space.

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Bone Resorption↗