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1.
Metabolism ; 30(1): 18-26, Jan. 1981.
Artigo em Inglês | MedCarib | ID: med-12087

RESUMO

The possibility that insufficient glucose production or availability of gluconeogenic substrates could account for fasting hypoglycemia was investigated in three children with epinephrine deficiency. Each had been born the smaller of discordant identical twins, and the unaffected twins served as controls. Fasting plasma glucose production was measured by constant infusion of U-[13]C-glucose under steady-state conditions and was compared with availability of potential glucose sources estimated from respiratory calorimetry and excretory nitrogen. The average rate of glucose production was 2.6 mg/kg/min in the affected twins after they became symptomatic and 2.9 mg/kg/min in the control twins after comparable fasting. Plasma alanine was lower in the affected twins during this interval (average: 0.11 mM versus 0.16 mM), but not earlier prior to decreased plasma glucose; alanine correlated with plasma glucose in a similar way in both groups (r = 0.77). Plasma urea production was 0.30 versus 0.15 mg urea N/kg/min. The calculated availability of potential gluconeogenic amino acids was 1.2 versus 0.6 mg/kg/min. Availability of glycerol, estimated from respiratory calorimetry was 0.4 mg/kg/min in both groups. In two of the twin pairs, net oxidation of carbohydrate (glycogen) was, by design, relatively small under these conditions (0.1 and 0.4 mg/kg/min in the affected and control twins, respectively). Gluconeogenesis therefore accounted for the majority of glucose production. The unaccounted remaining major gluconeogenic source is assumed to be recycled substrates from unoxidized pyruvate. Infusion of excess alanine in these two pairs increased plasma glucose and glucose production similarly in both the affected and control twins. This change was associated with an abnormally large increase in plasma alanine. In the third twin pair, net oxidation of carbohydrate was greater in the affected twin (1.8 versus 1.3 mg/kg/min) and possible glucose sources exceeded total glucose production during hypoglycemia. Earlier during fasting, net oxidation of carbohydrate in this twin was 5.8 mg/kg/min versus 3.1 mg/kg/min in the control. Plasma glucose production measured simultaneously was 4.3 versus 3.8 mg/kg/min, being less than the rate of carbohydrtae oxidation in the affected twin. It is concluded that the abnormal fasting metabolism observed in these children with decreased epinephrine was not primarily a consequence of deficient glucose production or lack of potential gluconeogenic substrates. Initial persistent oxidation of glycogen and subsequent increased utilization of protein during hypoglycemia indicate failure to conserve these limited net sources of pyruvate(AU)


Assuntos
Humanos , Gravidez , Pré-Escolar , Criança , Masculino , Feminino , Peso ao Nascer , Glicemia/biossíntese , Epinefrina/diagnóstico , Hipoglicemia/metabolismo , Gêmeos , Gêmeos Monozigóticos , Alanina/sangue , Aminoácidos/metabolismo , Jejum , Gluconeogênese , Glicogênio/metabolismo , Cinética , Oxirredução , Ureia/sangue
2.
West Indian med. j ; 24(3): 150-9, Sept. 1975.
Artigo em Inglês | MedCarib | ID: med-11124

RESUMO

Using the open chest dog with the heart in situ, the influences upon the cardiac glycogen by fasting, anacardium occidentale, and ouabain were studied. Fasting elevated the cardiac glycogen while intravenous infusion of glucose did not increase the cardiac glycogen. Anacardium occidentale elevated the cardiac glycogen after a slow intravenous infusion. The depletion of cardiac glycogen occurred concurrently with the onset of ectopic beats due to ouabain toxicity, and the toxic dose of ouabain was significantly increased in relation to the high cardiac glycogen. The stress of cardiac surgery significantly depleted the glycogen content of the human heart, and this depletion was not related to trauma or the time the patient was on cardio-pulmonary by-pass. It is concluded that: (a) anacardium occidentale protects against ouabain arrhythmias by elevating the cardiac glycogen, (b) there is a critical cardiac glycogen level below which ouabain readily becomes toxic, and (c) surgery on the heart in the human depletes its glycogen stores (AU)


Assuntos
21003 , Humanos , Cães , Glicogênio/metabolismo , Coração/efeitos dos fármacos , Ouabaína/toxicidade , Plantas Medicinais , Cirurgia Torácica , /metabolismo , Ouabaína/antagonistas & inibidores , Extratos Vegetais/farmacologia , Árvores , Jamaica
5.
Clin Sci ; 39(3): 375-82, Sept. 1970.
Artigo em Inglês | MedCarib | ID: med-14569

RESUMO

Metabolic acidosis was induced by feeding ammonium chloride to rats which were maintained on a carbohydrate diet for 48h. Fasting blood glucose was the same in acidotic and control animals, but there was an increase in liver glycogen in the former. Muscle glucogen was unchanged. In vitro glycogenesis was the same in liver slices from normal rats when incubated at a range of pH from 6.90 to 7.40. The peak blood glucose in response to intraperitoneal injections of glucagon was the same in control and acidotic rats. The rate of disappearence of glucose was slower in acidotic rats both after the glucagon induced hyperglycaemia and after intravenously injected glucose. Liver phosphorylase, total glycogen synthetase and the I form of this enzyme were unchanged in acidosis. The data are compatible with the hypothesis that in the acidotic rat there is a block in glycolysis-possibly at the phosphofructokinase step (Summary)


Assuntos
Ratos , 21003 , Feminino , Técnicas In Vitro , Acidose/metabolismo , Carboidratos/metabolismo , Cloreto de Amônio/farmacologia , Acidose/induzido quimicamente , Glicemia , Glicogênio/metabolismo , Glicogênio Hepático/metabolismo , Fígado/enzimologia
7.
J Pediatr ; 76(1): 75-81, Jan. 1970.
Artigo em Inglês | MedCarib | ID: med-12429

RESUMO

Total body potassium, muscle potassium, magnesium, and glycogen have been estimated in infants while they were malnourished, during recovery, and in several after they were fully recovered. Muscle potassium was curvilinearly related to the total body potassium. Muscle magnesium was reduced, and the potassium/magnesium ratio was depressed in children with low muscle potassium values, implying differential loss of muscle potassium. Muscle potassium was linearly related to muscle glycogen. Twenty-four-hour urinary excretion of creatinine was measured; by assuming that 1 mg. of creatinine was derived from 20 Gm. of muscle, calculations of muscle mass were made. In children with a total body potassium over 40 mEq. per kilogram of body weight, muscle potassium contributed approximately one half of the total body potassium; this ratio decreased significantly when body potassium fell to very low values. (AU)


Assuntos
Humanos , Criança , Deficiências Nutricionais/metabolismo , Glicogênio/análise , Magnésio/análise , Músculos/análise , Potássio/análise , Desnutrição Proteico-Calórica/fisiopatologia , Potássio/metabolismo , Creatinina/urina
8.
Clin Sci ; 37(3): 631-42, Dec. 1969.
Artigo em Inglês | MedCarib | ID: med-12466

RESUMO

Carbohydrate metabolism was studied in Jamaican children who had been admitted to hospital with protein-calorie malnutrition. Analysis of liver biopsies showed that levels of protein and glycogen were low in malnutrition and rose with recovery. Hepatic glucose-6-phosphatase was elevated in malnutrition but phosphorylase levels were normal. In the malnourished child there was normal hepatic glycogenolysis as shown by a normal blood glucose response to intravenous glucagon without any detectable rise in blood pyruvate and lactate. Fasting levels of blood lactate as well as lactate-pyruvate ratios rose with recovery from malnutrition. Galactose tolerance tests showed a delayed disappearance of injected galactose, but the maximum increase in blood glucose after galactose injection was the same in all clinical states. Glucose disappearance was delayed after both glucagon and galactose. Muscle glycogen was initially reduced, but there was a markeed "overshot" to supranormal levels during the recovery phase. (AU)


Assuntos
Humanos , Lactente , Carboidratos/metabolismo , Deficiências Nutricionais/metabolismo , Glicemia/análise , Galactose/metabolismo , Glucagon/farmacocinética , Teste de Tolerância a Glucose , Glucose-6-Fosfatase/análise , Glucosiltransferases/análise , Glicogênio/análise , Fígado/análise , Fígado/enzimologia , Glicogênio Hepático/análise , Glicogênio Hepático/metabolismo , Injeções Intravenosas , Jamaica , Lactatos/sangue , Taxa de Depuração Metabólica , Músculos/análise , Proteínas/análise , Piruvatos/sangue
10.
West Indian med. j ; 11(1): 12-14, Mar. 1962.
Artigo em Inglês | MedCarib | ID: med-10340

RESUMO

Pilot experiments to assess changes in R.N.A. and glycogen levels in the livers of rats fed aqueous extracts of Crotalaria fulva are described. (AU)


Assuntos
Ratos , 21003 , RNA/efeitos dos fármacos , Glicogênio/metabolismo
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