Effects on efficiency and consumption of 14C-glucose and 14C-hexanoate in arrested and beating atria of guinea pigs.
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The glycine conjugates of isocaproic, 4-methylhexanoic, 7-hydroxyoctanoic and 8-hydroxyoctanoic acids have been identified in the urine of children with medium-chain acyl-CoA dehydrogenase (MCAD) deficiency using gas chromatography-mass spectrometry of the trimethylsilyl derivatives. A quantitative study showed that the glycine conjugates of isocaproic and 4-methylhexanoics acids were excreted during acute episodes and in smaller amounts when subjects were asymptomatic. The glycine conjugates of 7-hydroxyoctanoic and 8-hydroxyoctanoic acids were detectable during acute episodes. None of the conjugates was detected in controls or controls receiving a diet containing medium-chain triglycerides. It is suggested that the glycine conjugates of isocaproic acid and 4-methylhexanoic acid are metabolites of branched-chain fatty acids and that they are specific for MCAD deficiency.
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The present work is concerned with the aroma of hybrids between raspberry (Rubus idaeus, L.) and arctic bramble (Rubus arcticus, L.). Analyses of the volatiles were performed in three stages. The carbonyl compounds were determined as 2,4-dinitrophenylhydrazones, the volatile acids and the neutral components separately in a combined gas chromatography-mass spectrometer components separately in a combined gas chromatograph-mass spectrometer using glass capillary columns. Over 70 compounds were identified in the aroma concentrates of the hybrids. The major components included acetic and hexanoic acids, trans 3-penten-1-ol, 2-heptanol, 3-methyl-2-buten-1-ol, benzyl alcohol and linalool. 2,5-Dimethyl-4-methoxy-2,3-dihydro-3-furanone together with alpha and beta-ionones, characteristic compounds of arctic bramble and raspberry, respectively, were found in the hybrids in much lower concentrations than in the parent berries. Percentage concentrations of the main components in the volatile oils, together with their approximate concentrations in the press juices, were determined. The contents of the corresponding compounds in arctic bramble and in raspberry are also given.
There is disagreement among in vitro fertilization (IVF) programs as to the need to administer exogenous progesterone to support the luteal phase of patients undergoing embryo transfer after IVF. We examined the effect on pregnancy rates of Proluton, 50-mg daily injections given on days 7-16 following oocyte recovery, in 186 women undergoing IVF treatment using a combined stimulation regime of clomiphene and human menopausal gonadotropin (hMG). One group was deliberately selected for treatment on the possible criterion of luteal-phase deficiency and two other groups were randomly selected into a treatment and a control group. No effect on pregnancy rate was noted in any of these groups. These results indicate that extension of the luteal phase with exogenous progesterone is unlikely to have a significant effect on increasing the pregnancy rate in IVF programs using similar treatment regimes.
Two cases of successful pregnancy and delivery by patients with ovarian failure are reported. In both cases ova were donated by the sister of the patient. A high degree of success (two pregnancies in three attempts) is discussed, as is the significance of simplified pretransfer "priming" and very early withdrawal of exogenous hormonal support.
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Insulin release and 86Rb efflux were studied in perifused rat islets exposed in vitro to alloxan (2 mmol/l) for 5 min. At a low glucose concentration, alloxan transiently increased 86Rb efflux. Alloxan immediately and completely abolished the secretory response to glucose (15 mmol/l) and markedly delayed the reduction in 86Rb efflux normally produced by the sugar. 3-O-methylglucose (20 mmol/l) provided complete protection against the alteration of 86Rb efflux and partial protection against the inhibition of insulin release. Immediately after alloxan treatment, glyceraldehyde, alpha-ketoisocaproic acid and tolbutamide still induced a rapid release of insulin, but the late phase normally stimulated by glyceraldehyde and alpha-ketoisocaproic acid was inhibited. If islets were exposed to glyceraldehyde or tolbutamide 15 min after alloxan treatment, the rapid insulin release was also markedly impaired. Alloxan failed, however, to affect the ability of these three stimuli to reduce 86Rb efflux from islet cells. Glucose oxidation and utilization were decreased in alloxan-treated islets and 3-O-methylglucose protected against this effect. The results show that the glucose recognition system in B-cells is the most rapidly and severely affected by alloxan. The drug also alters the response to other secretagogues, the insulin releasing properties of which can be impaired without alteration of their ability to reduce 86Rb efflux.
In perifused pancreatic islets, the fluorescence of oxidized flavoproteins (FAD) was recorded continuously. Elevation of glucose concentration in the medium form 0 or 5 mM to 20 mM led to decrease in FAD-fluorescence beginning 10 sec after change of medium. L-leucine (10 mM), (+/-)-B-BCH (20 mM) and alpha-ketoisocaproic acid (10 mM) caused typical kinetics of FAD-fluorescence decrease. The results are interpreted to indicate rapid changes of the functional state of B-cell mitochondria induced by the above-mentioned stimulators of insulin release.
The effects of alpha-ketoisocaproate (KIC, 10 mmol/l) on glucagon and insulin release were studied in the in vitro perfused rat pancreas. The experiments were performed at low glucose concentration (3.3 mmol/l) in the absence or presence of arginine (10 mmol/l). In all the experiments KIC induced a marked and not rapidly reversible inhibition of glucagon release. This inhibition was more pronounced in the absence (76 percent) than presence of arginine (61 percent). These inhibitory patterns closely duplicated those which were seen in parallel experiments which included a rise in the concentration of glucose (from 3.3 to 11.1 mmol/l). KIC was also a potent stimulator of insulin release. The results are compatible with the view that the intracellular metabolism of KIC and glucose plays an essential role in the regulation of glucagon release by exogenous substrates.
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