Regional and subcellular distribution of enzymes of branched-chain amino acid metabolism in brains of normal and diabetic rats

Branched-chain-amino-acid:alpha-ketoglutarate transaminase and branched-chain alpha-ketoacid dehydrogenase have been assayed in brains of control and of streptozotocin-induced diabetic rats. Enzyme activities were measured in five distinct regions of the brain: cerebellum, pons + medulla, midbrain, thalamus + hypothalamus, and telencephalon. Subcellular distribution of these enzymes in whole brain was assessed by fractionating brain homogenate into cytoplasm, free mitochondria, and synaptosomes. The following enzymes were used as markers: lactate dehydrogenase for cytoplasm, glutamate dehydrogenase for mitochondria, and glutamate decarboxylase for synaptosomes. The activity of the branched-chain amino acid transaminase in all brain regions was considerably higher than that of the branched-chain alpha-ketoacid dehydrogenase. While the highest activity of the transaminase occurred in brain-stem regions, the highest activity of the dehydrogenase was present in cerebellum and telencephalon. Diabetes did not affect the activity of the transaminase, but it caused a decrease in the total activity of the dehydrogenase in midbrain and in thalamus + hypothalamus. The transaminase was localized in the cytoplasmic fraction of whole brain, while the dehydrogenase was enriched in the free mitochondria.     

Fate of corticotrophins in an isolated adrenal-cell bioassay and decrease of peptide breakdown by cell purification

1. The fate of corticotrophins in a trypsin-dispersed rat adrenal-cell assay system was investigated with a view to establishing whether differences in the rate of inactivation might contribute to potency differences observed between analogues. 2. Corticotrophin-(1-24)-tetracosapeptide and to a lesser extent synthetic 1-39 corticotrophins were found to be inactivated during incubation with cell suspension. 3. Peptide fragments were isolated by using [[(3)H(2)]Tyr(23)]corticotrophin-(1-24)- tetracosapeptide as a marker. The fragments indicate a peptidase with a predominantly tryptic specificity. 4. The peptidase is present in the extracellular fluid and is released from cells when they are damaged. 5. Cells were fractionated on an albumin gradient. Cells from the zona fasciculata and the zona intermedia or reticularis were present in fractions which produced fluorogenic steroids in response to corticotrophin. 6. Purification of the cells by centrifugation through albumin decreased degradation by peptidases, so that if the assay is carried out with a dilute suspension of purified cells peptide breakdown should not affect the observed potencies of adrenocorticotrophin analogues. 7. No binding of [[(3)H(2)]Tyr(23)]corticotrophin-(1-24)- tetracosapeptide to cells could be detected at low concentrations of the peptide. This indicated that less than 120 receptors/cell are occupied during stimulation by a dose that would elicit approx. 80% of the maximal response.     

Control of glycogen levels in brain

Abstract— Prolonged (6 hr) anaesthesia with phenobarbital in mice or rats results in a doubling or tripling of brain glycogen. Increases were also observed if high levels of plasma glucose were maintained for 6 hr. In alloxan diabetes brain glycogen was not elevated in spite of the high plasma glucose concentrations. However, administration of insulin to such diabetic animals, together with enough glucose to maintain high plasma levels, resulted in at least a doubling of brain glycogen in 6 hr. Phenobarbital can still increase brain glycogen in diabetic animals. In all of the conditions associated with increased glycogen deposition, increases were found in the ratio of brain glucose to plasma glucose. Cerebral glucose-6-P levels were also increased whereas there were no substantial changes in levels of UDP-glucose or glucose-1,6-diphosphate.     

The incidence of double-yolked eggs in relation to improvement in egg production

Summary The production of double-yolked eggs and its relation to other egg production traits has been summarized over a period of thirty years for a closed flock selected for gains in total egg production.The number of double-yolked eggs per pullet as well as the percentage of pullets laying at least one double-yolked egg have increased rather steadily, although it is evident that the trait possesses no selective advantage. Pullets which laid double-yolked eggs showed earlier sexual maturity and superiority in egg production but it is clear that the corresponding genetic correlations are low or negligible.The heritability of the trait increased with its level of incidence and is sufficiently high that selection should increase the incidence to a level permitting further study of multiple ovulation.

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Zusammenfassung An einer für eine Steigerung der Ei-Produktion ausgewählten Herde Weißer Leghornhühner wurde der Anfall von Eiern mit zwei Dottern und ihre Beziehung zu anderen Merkmalen der Ei-Produktion für einen Zeitraum von 30 Jahren zusammengestellt.Die Anzahl doppeldottriger Eier je Hühnchen und der Prozentsatz Hühnchen, die wenigstens ein doppeldottriges Ei legten, ist ziemlich konstant geblieben, wenn auch dieses Merkmal offensichtlich keinen Selektionswert hat. Hühnchen, die Eier mit zwei Dottern legten, zeigten eine frühere Geschlechtsreife und eine höhere Ei-Produktion, aber es ist klar, daß die entsprechenden genetischen Korrelationen niedrig sind.Die Erblichkeit des Merkmals stieg mit seinem Auftreten, sie ist hoch genug, daß eine Selektion das Auftreten noch steigern könnte, um eine weitere Untersuchung der mehrfachen Ovulation zu ermöglichen.

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Dedicated to Professor Hans Stubbe on the occasion of his 65^th birthday.     

Microscopic Examination of Stools After Partial Gastrectomy

The present study was undertaken to determine the frequency with which undigested meat fibres in the stool could be found after partial gastrectomy. A sample of stool was examined in 61 patients who had undergone a partial gastrectomy and in 92 control patients. The age ranges and average ages of both groups were similar. The stools of 77 of the 92 control patients contained well-digested meat fibres, 14 showed partially digested fibres, and one patient had completely undigested meat fibres. In the postgastrectomy group, 44 of 61 patients had well-digested meat fibres and 17 showed partially digested fibres in their stools. None showed undigested fibres. The present study demonstrated that the finding of undigested meat fibres is as infrequent in postgastrectomy patients as in control patients. If undigested meat fibres are found in the stools of postgastrectomy patients, it is suggestive of pancreatic exocrine insufficiency.