Signs of cerebral hypoxia in hyperventilation

Zusammenfassung Passive Hyperventilation anästhesierter und immobilisierter Katzen führt zu signifikanter Erhöhung des Laktat-Pyruvat-Quotienten in Zerebrospinalflüssigkeit und Gehirngewebe. Wegen der Verbindung zwischen Laktat/Pyruvat- und NADH/NAD⁺-System ist somit anzunehmen, dass Hyperventilation (CO₂-Druck unter 20–25 mm Hg) zu zerebraler Hypoxie führt.     

Effect of dibutyryl cyclic AMP on cerebral energy charge and electrocorticographic activity in rats under asphyxic hypoxia]

In Rats anesthetized with pentobarbital and submitted to brief asphyxic episodes, intracerebroventricular administration of dibutyryl cyclic AMP inhibits the decrease of energy charge, delays the disappearance of electrocorticographic activity (E Co G) and shortens the recovery time of E Co G.     

Why do patients with respiratory muscle paralysis require artificial hyperventilation?

Summary The primary reason for the need of hyperventilation in patients with respiratory paralysis is the insufficiency of the inhibitory Hering-Breuer reflex. The artificial distension of the lungs with normal tidal volume cannot inhibit the respiratory centre in contrast to the normal state.     

Why do patients with respiratory muscle paralysis require artificial hyperventilation?

The primary reason for the need of hyperventilation in patients with respiratory paralysis is the insufficiency of the inhibitory Hering-Breuer reflex. The artificial distension of the lungs with normal tidal volume cannot inhibit the respiratory centre in contrast to the normal state.     

原发性上腹部癌转移48例CT征象

目的提高CT诊断原发性上腹部癌肿转移的重要性的认识。方法啬顾性分析48例经手术、病理证实的有上腹部转移的原发性癌肿的CT表现。结果原发性上腹部癌肿转移的CT征象,主要有上腹部淋巴结转移,邻近脏器的侵犯及血道转移等。结论CT对原发性上腹部癌肿转移有很大诊断价值。     

Epidermal sensitivity to hypoxia in the lugworm

Summary Physiological and anatomical data support the idea that in the caudal epidermis of the lugworm,Arenicola marina (L.), there are chemoreceptors detecting variations of oxygen partial pressure in the ambient water.This research was partly supported by a C.N.R.S. grant, AI No. 582 085. We thank Dr P. Dejours and Dr J. Taxi for helpful comments and discussion, Mrs S. Dejours for editing the English of this paper, M.F. Baucher, A. Dorme, F. Kleinbauer, the staff of the Station Biologique de Roscoff and the Service de Microscopie Electronique, C.N.R.S., boulevard Raspail, Paris, for technical assistance.     

Imaging of oxygen and hypoxia in cell and tissue samples

Molecular oxygen (O₂) is a key player in cell mitochondrial function, redox balance and oxidative stress, normal tissue function and many common disease states. Various chemical, physical and biological methods have been proposed for measurement, real-time monitoring and imaging of O₂ concentration, state of decreased O₂ (hypoxia) and related parameters in cells and tissue. Here, we review the established and emerging optical microscopy techniques allowing to visualize O₂ levels in cells and tissue samples, mostly under in vitro and ex vivo, but also under in vivo settings. Particular examples include fluorescent hypoxia stains, fluorescent protein reporter systems, phosphorescent probes and nanosensors of different types. These techniques allow high-resolution mapping of O₂ gradients in live or post-mortem tissue, in 2D or 3D, qualitatively or quantitatively. They enable control and monitoring of oxygenation conditions and their correlation with other biomarkers of cell and tissue function. Comparison of these techniques and corresponding imaging setups, their analytical capabilities and typical applications are given.     

基于交通流特征的可变信息板布局优化方法

为了引导交通流的合理分布并确定城市路网中可变信息板的布局方案,本文提出了一种基于路段交通流特征信息量评估的可变信息板布局优化方法。利用图论对城市路网进行描述,建立了基于信息熵的路段交通流特征信息量评估模型。并结合实际路网的拓扑结构特性,设计了可变信息板布局方案的初步生成方法。12节点的网络实例验证显示:该布局方法是有效的,且便于交通管理者所理解。同时,提出的交通流特征提取方法具有较强的应用性,可为道路规划与安全评估提供基础信息。     

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.     

Influence of hypoxia on contractility and calcium uptake in rabbit aorta

Summary The influence of hypoxia on noradrenaline (NA)-induced contractions and⁴⁵Ca uptake has been studied on isolated rabbit aortae. Hypoxia significantly decreased the contractility of aortic strips. NA stimulation resulted in increased or decreased⁴⁵Ca uptake by normoxic or hypoxic specimens, respectively. Relating⁴⁵Ca movement with mechanical activity, the results suggest that decrease in Ca⁺⁺ uptake may be mechanism for hypoxic relaxation of aortic smooth muscle.The author acknowledges facilities at the Wellcome Surgical Research Institute, University of Glasgow, U.K. Much of this work was in collaboration with Drs Sheila Jennett and J.D. Pickard.     

Effect of hypoxia on glycolysis in isolated fetal rat heart]

Glycolysis was assessed in the isolated foetal Rat in hypoxia. Measurements were made of glucose uptake, lactate output, C14 glucose incorporation into glycogen and tissular levels of ATP, PCr, glycogen and lactate. Glycolysis was stimulated by hypoxia to a greater extent in the young foetal heart of 16.5 days post coitum than in the foetal heart at term. Thus high energy phosphates were maintained at a higher level in the younger heart. The results are discussed in relation to the high resistance to hypoxia of the foetal heart.     

Adrenal responses to hypoxia and hypercapnia in the young calf

Summary Quantitative analysis of adrenal responses to moderate hypoxia and hypercapnia in the conscious calf shows that the sensitivity of the adrenal cortical response far exceeds that of the adrenal medulla.Acknowledgment. This work has been supported by grants from the Agricultural Research Council, the Medical Research Council and the Wellcome Trust. We are also indebted to Dr D. M. Burley (CIBA) for his continued support.     

The response of human skeletal muscle tissue to hypoxia

Hypoxia refers to environmental or clinical settings that potentially threaten tissue oxygen homeostasis. One unique aspect of skeletal muscle is that, in addition to hypoxia, oxygen balance in this tissue may be further compromised when exercise is superimposed on hypoxia. This review focuses on the cellular and molecular responses of human skeletal muscle to acute and chronic hypoxia, with emphasis on physical exercise and training. Based on published work, it is suggested that hypoxia does not appear to promote angiogenesis or to greatly alter oxidative enzymes in skeletal muscle at rest. Although the HIF-1 pathway in skeletal muscle is still poorly documented, emerging evidence suggests that muscle HIF-1 signaling is only activated to a minor degree by hypoxia. On the other hand, combining hypoxia with exercise appears to improve some aspects of muscle O₂ transport and/or metabolism.     

The immune suppressive effect of hypoxia on chicken embryos

Zusammenfassung Die Immunreaktion von Hühnerembryonen konnte durch stimulierte Höhenbehandlung (hypoxischer Stress) unterdrückt werden, während die Immunreaktion von Junghühnern nicht beeinflusst wurde. Dies macht wahrscheinlich, dass Hypoxia die Differenzierung pluripotentieller Stammzellen nach Immunozyten verhindert.     

Cyclic nucleotide levels in the perfused rat heart subjected to hypoxia

Summary Isolated rat hearts were subjected to hypoxic perfusion on a recirculating Langendorff apparatus. Following a 30-min-period of aerobic stabilization the hearts were perfused for 30 min with media equilibrated with 84% N₂, 12% O₂ and 4% CO₂. At the end of the hypoxic period myocardial concentrations of cyclic AMP and cyclic GMP were determined by radioimmunoassay. Exposure to hypoxia resulted in a significant increase in cyclic AMP (p<0.01) and a decrease in cyclic GMP (p<0.05) as compared to hearts perfused for 60 min with media gassed with 96% O₂, 4% CO₂.Acknowledgment. We gratefully acknowledge the excellent technical assistance provided by Mrs Inger O. Boggs and Miss Patricia C. Hannigan. This work was supported in part by U. S. Public Health Service grant HL 14661 from the National Heart and Lung Institute, and by a grant from the Central Ohio Heart Chapter.