Experimental brain tumours in dogs

Zusammenfassung Durch wiederholte i.v. Injektionen von gelöstem Methylnitrosoharnstoff werden bei 4 Hunden intrazerebrale Geschwülste induziert. Damit ist der Beweis erbracht, dass dieser Stoff nicht nur bei Nagetieren, sondern auch bei grösseren Säugetieren Geschwülste des Zentralnervensystems verursachen kann.     

Effect of calcium and temperature on histamine release from pig lung by compound 48/80

Zusammenfassung Es zeigt sich, dass die anaphylaktische Histaminausschüttung Calcium benötigt und bei neidriger Temperatur vollkommen gehemmt wird. Bei Zugabe der Substanz 48/80 erweist sich die dadurch hervorgerufene Histaminausschüttung als dosisabhängig und benötigt kein extrazelluläres Calcium. Die Reaktion wird bei niedriger Temperatur (4°C) nur teilweise gehemmt. Sie kann daher nicht als zweckmässiges Modell für das Studium der anaphylaktischen Histaminausschüttung der Lunge angesehen werden.

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This investigation was supported by United States Public Health Service Grants Nos. OH-00304 and HE-14179.     

Brain homeostasis: VEGF receptor 1 and 2—two unequal brothers in mind

Vascular endothelial growth factors (VEGFs), initially thought to act specifically on the vascular system, exert trophic effects on neural cells during development and adulthood. Therefore, the VEGF system serves as a promising therapeutic target for brain pathologies, but its simultaneous action on vascular cells paves the way for harmful side effects. To circumvent these deleterious effects, many studies have aimed to clarify whether VEGFs directly affect neural cells or if the effects are mediated secondarily via other cell types, like vascular cells. A great number of reports have shown the expression and function of VEGF receptors (VEGFRs), mainly VEGFR-1 and -2, in neural cells, where VEGFR-2 has been described as the major mediator of VEGF-A signals. This review aims to summarize and compare the divergent roles of VEGFR-1 and -2 during CNS development and homeostasis.     

Whisker movements evoked by stimulation of single pyramidal cells in rat motor cortex

Neuronal activity in the motor cortex is understood to be correlated with movements, but the impact of action potentials (APs) in single cortical neurons on the generation of movement has not been fully determined. Here we show that trains of APs in single pyramidal cells of rat motor cortex can evoke long sequences of small whisker movements. For layer-5 pyramids, we find that evoked rhythmic movements have a constant phase relative to the AP train, indicating that single layer-5 pyramids can reset the rhythm of whisker movements. Action potentials evoked in layer-6 pyramids can generate bursts of rhythmic whisking, with a variable phase of movements relative to the AP train. An increasing number of APs decreases the latency to onset of movement, whereas AP frequency determines movement direction and amplitude. We find that the efficacy of cortical APs in evoking whisker movements is not dependent on background cortical activity and is greatly enhanced in waking rats. We conclude that in vibrissae motor cortex sparse AP activity can evoke movements.     

用脸谱图对太子河本溪市区段河流沉积物中重金属污染进行评价的研究

本文将沉积学原理及国际上新发展的两种重金属污染评价方法与多变量的图表示法——脸谱图相结合,对太子河本溪市区段河道沉积物中重金属的污染状况及潜在生态危害进行了综合性的评价研究。从脸谱图上可以直观地看出各采样点重金属的污染情况和潜在生态危害程度。从研究结果可以看出,太子河本溪市区段河道沉积物中重金属的污染是很严重的。     

Einfluss der Ionenstärke auf das Immunpräzipitationsvermögen von Amphibien-Antikörpern

Summary Precipitating antibodies of amphibia are more dependent on the ionicity of the buffer system than the well known rabbit antibodies.