Phosphatases IX. Differences in sialic acid content of rat liver alkaline phosphatase isoenzymes

Zusammenfassung Die Heterogeneität der alkalischen Phosphatase in der Rattenleber wird beschrieben. Anodische und kathodische Isoenzyme unterscheiden sich unter anderem durch ihre Reaktion auf die Neuraminidase Behandlung.

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V. Volek, J. tpán, E. Beneová andF. Hemanský, Sb. lék. in print (1973).     

Action of isothiocyanates on germinating plants

Zusammenfassung Es wurde ein inhibitorischer Effekt des Allylisothiocyanates auf die Keimung von Erbsen, Weizen und Raps beobachtet, und dabei die Veränderungen des Stickstoff- und Zuckermetabolismus verfolgt: Isothiocyanate setzen die Atmung und anaerobe Glykolyse um etwa 30% herab und legen die Proteosynthese vollständig still.     

A common polymorphism of the growth hormone receptor is associated with increased responsiveness to growth hormone

Growth hormone is used to increase height in short children who are not deficient in growth hormone, but its efficacy varies largely across individuals. The genetic factors responsible for this variation are entirely unknown. In two cohorts of short children treated with growth hormone, we found that an isoform of the growth hormone receptor gene that lacks exon 3 (d3-GHR) was associated with 1.7 to 2 times more growth acceleration induced by growth hormone than the full-length isoform (P < 0.0001). In transfection experiments, the transduction of growth hormone signaling through d3-GHR homo- or heterodimers was approximately 30% higher than through full-length GHR homodimers (P < 0.0001). One-half of Europeans are hetero- or homozygous with respect to the allele encoding the d3-GHR isoform, which is dominant over the full-length isoform. These observations suggest that the polymorphism in exon 3 of GHR is important in growth hormone pharmacogenetics.     

A biologically active analogue of oxytocin not containing a disulfide group

Zusammenfassung Die Synthese eines Analogen des Deamino-oxytocins, in dem ein Schwefelatom der Disulfidbrücke durch eine Methylengruppe ersetzt ist (I,X = CH₂,R=H), wird beschrieben. Die Verbindung hat oxytocinähnliche biologische Wirkungen.     

Enhancement of H3-norepinephrine accumulation in rat vas deferens by cocaine,imipramine, and desmethylimipramine

Résumé La cocaïne, l'imipramine, la desméthylimipramine et la guanéthidine ont provoqué une accumulation accrue de la noradrénaline tritiée dans le vas deferens du rat, dans des conditions expérimentales où elles inhibaient fortement cette accumulation dans le cur. La réserpine et le métaraminol n'ont pas montré cet effet. La question se pose de savoir si l'accroissement observé est dû à une augmentation de la captation nette de la noradrénaline ou à un échange accru de la noradrénaline exogène et endogène au niveau des terminaisons nerveuses sympathiques du vas deferens.     

A saturable receptor for 32P-inositol-1,4,5-triphosphate in hepatocytes and neutrophils

Several receptors for neurotransmitters, hormones and growth factors cause accelerated phosphodiesteratic breakdown of polyphosphoinositides when activated. One of the soluble products of this reaction, inositol-1,4,5-trisphosphate (Ins(1,4,5)P3) is thought to act as a second messenger signalling the release of Ca2+ from intracellular stores. In support of this hypothesis, several studies have shown that Ins(1,4,5)P3 releases sequestered Ca2+ from permeable cells and microsomes. On the basis of certain structural requirements for Ca2+-releasing activity by inositol phosphates, it has been postulated that Ins(1,4,5)P3 acts by binding to a specific intracellular receptor, probably on a component of the endoplasmic reticulum. Here we report that 32P-Ins(1,4,5)P3 binds to a specific saturable site in permeabilized guinea pig hepatocytes and rabbit neutrophils, and that the properties of this binding site suggest that it is the physiological receptor for Ins(1,4,5)P3.     

烧结?Al?B4C 复合材料的往复滑动磨损性能

采用粉末冶金法制备了不同 B₄C 含量（1wt%、6wt%、15wt% 和 30wt%）的碳化硼增强铝基复合材料（Al?B₄C），并研究了 B4C 含量对其力学性能和摩擦学行为的影响。在7 N载荷下， Al?30B₄C 复合材料的密度最高 (~2.54 g/cm3)、孔隙率最低 (4%)、维氏硬度最高 (HV ~75)、重量损失最低 (0.4 mg) 和比磨损率最低 (0.00042 mm3/ (N·m))，与纯铝相比，硬度提高167%，失重降低75.8%，比磨损率降低76.7%。此外，磨损表面的扫描电镜图像显示，Al?B₄C复合材料在7 N载荷下的最窄磨损槽为0.85 mm，主要磨损机制为磨粒磨损机制。根据摩擦分析，表面之间的摩擦系数随着碳化硼含量的增加和外加载荷的减少而增加。总之，就 Al?B₄C 复合材料的摩擦学和力学性能而言，B₄C 是一种有效的增强材料。