Glycolipid transfer protein and intracellular traffic of glucosylceramide

Glycolipid transfer protein (GL-TP), a nonglycosylated protein with a molecular weight of 22,000 K, has been purified from pig brain. The protein transfers, by a carrier mechanism, glycolipids with a beta-glucosyl or beta-galactosyl residue directly linked to either ceramide or diacylglycerol. GL-TP appears to be present in most animal cells, and evidence has been obtained which indicates that it is a cytoplasmic protein. Little is known about the function of GL-TP. Current evidence indicates that glycosphingolipid glycosylation occurs at the luminal side of the Golgi apparatus, except for the glucosylation of ceramide, which has been shown to occur at the cytoplasmic side of the Golgi or endoplasmic membrane. It appears most likely that GL-TP participates in the intracellular traffic of glucosylceramide.     

Defining the resistance to oxygen transfer in tissue hypoxia

Studies of O2 supply in freshly isolated adult mammalian cells provide new insight into the factors that limit mitochondrial oxygenation in vivo. Of particular importance, mitochondria are present at high densities and often in apparent clusters, both of which contribute to local O2 gradients under hypoxic conditions. Current evidence indicates that the mitochondrial distribution is a component of the differentiated phenotype of adult mammalian cells and that specific motors and anchoring mechanisms are present to allow redistribution in response to developmental, physiological and pathological challenges. To compare the importance of resistance to O2 transfer under different conditions and at different sites along the supply path in vivo, a simple mathematical expression of relative resistance to O2 supply is introduced. Under various pathophysiological conditions, this resistance increases in specific regions of the pulmonary, circulatory or cellular supply path and results in O2 deficiency in the mitochondria. Regardless of cause, the relative resistance increases dramatically in the vicinity of mitochondrial clusters during hypoxia.     

Isolierung der tuberkulinaktiven Proteine aus dem Tuberkulin mit Hilfe von Dextran-Gel

Summary By filtering heated filtrates of the cultures ofMycobacterium tuberculosis human, bovine and avian type respectively through the dextran-gel Sephadex 50, it is possible to separate the tuberculoproteins from the other inactive constituents in a simple manner.     

In vitro induction of vegetative buds by tobacco smoke condensate

Zusammenfassung Es wird gezeigt, dass wasserlösliche Extrakte aus Tabakrauchkondensaten vegetative Keimlinge auf Kallusstücken aus Stämmen von haploiden Tabakpflanzen (Nicotiana tabacum) induzieren und dass der gleiche Effekt mit Kinetin und 3-Indolessigsäure erzielt werden kann.

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This study was carried out under contract No. 12-14-100-341(73) with the Agricultural Research Service, U.S. Department of Agriculture, administered by the Eastern Utilization Research Development Division, Philadelphia.

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The authors are thankful to Dr.R. B. Griffith, Director, Tobacco and Health Research Institute, University of Kentucky, for critical review of this paper and valuable suggestions.     

Possible involvement of indolamines in the glycogenic effect of the convulsant methionine sulfoximine in rat brain.

The aim of the present investigation was to look for the mechanisms causing disturbances in carbohydrate metabolism during the action of the epileptogenic agent methionine sulfoximine. The levels of glucose, glycogen, and indolamines were measured in seven different regions of rat brain. Methionine sulfoximine induced a decrease in serotonin level which was roughly dose-dependent. There were no obvious changes in tryptophan and 5-hydroxyindoleacetic levels in any area. Methionine sulfoximine induced the known increase in glucose and glycogen levels. The direct precursor of serotonin. 5-hydroxytryptophan, and benserazide (a decarboxylase inhibitor) were then injected into rats in association with methionine sulfoximine. In this case, methionine sulfoximine failed to induce seizures. Moreover, the serotonin level was unchanged and the carbohydrate content did not significantly increase. There was only a rise in 5-hydroxyindoleacetic acid level. This work shows a striking parallelism between serotonin decrease and glycogen increase.     

Demonstration of electron-dense material within ‘empty’ synaptic vesicles in the CNS of rat

Summary A method for demonstration of electron-dense particles within electron lucent synaptic vesicles from various regions of CNS of rat is described. On the basis of the controls a visualization of protein substance is detected.