Screening for Malignant Hyperpyrexia

The methods used to screen patients for malignant hyperpyrexia at present are not sufficiently accurate. This paper reports more specific methods of detecting patients liable to develop malignant hyperpyrexia. A motor-point muscle biopsy is performed for histopathological examination and to detect muscle contracture in vitro after exposure to halothane and suxamethonium.     

Insulin Secretion in Malignant Hyperpyrexia

An increased glucose-induced insulin response has been observed in patients susceptible to malignant hyperpyrexia. This raises the possibility that the membrane abnormality present in the calcium-storing membranes in the muscle cell in malignant hyperpyrexia may be present also in the beta cell of the pancreas.     

Identification of Susceptibility to Malignant Hyperpyrexia

While the serum level of creatine phosphokinase is useful as a screening test for malignant hyperpyrexia it does not provide certain identification of susceptible individuals. A much more accurate prediction may be made by pharmacological testing in vitro of muscle biopsy specimens. Individuals susceptible to malignant hyperpyrexia have muscle with heightened sensitivity to halothane, caffeine, succinylcholine, potassium chloride, and temperature change. Use of this test allows separation of susceptible individuals from those not at risk in families of patients who have experienced malignant hyperpyrexia.     

Anaesthetic-induced Malignant Hyperpyrexia: A Suggested Method of Treatment

Experiments in susceptible Landrace pigs have shown that procaine blocks the initiation of anaesthetic-induced malignant hyperpyrexia by both halothane and succinylcholine. Pretreatment with curare prevents only the trigger action of succinylcholine. In a preliminary study procaine was used to treat the established syndrome in five pigs, two of which survived. On the basis of these findings a treatment regimen can be suggested for patients who develop malignant hyperpyrexia.     

Biochemical and Molecular Genetic Basis of Hydrogenases

Hydrogenases catalyse the reversible reduction of protons to molecular hydrogen. Applied research is focused on structure and catalytic function under the aspect of hydrogen formation. In this review we summarize the current knowledge about properties and physiological roles of hydrogenases in pro- and eukaryotes and compile molecular genetical data about structural features of prokaryotic hydrogenases. Finally, prospects are given for the possible application of hydrogenases or ‘hydrogenase-like catalysts’ in energy production.     

Hyperpyrexia During Anaesthesia

Work in pigs has shown that malignant hyperpyrexia during anaesthesia may occur without suxamethonium having been given. A virtually constant feature in reported cases and in our own observations is that all subjects developing hyperpyrexia had received nitrous oxide and halothane.     

Biochemical Basis of Obligate Autotrophy in Nitrosomonas europaea

The specific activities of isocitric dehydrogenase, alpha-ketoglutaric dehydrogenase, succinic dehydrogenase, malic dehydrogenase, and reduced nicotinamide adenine dinucleotide (NADH) oxidase were determined in extracts of Nitrosomonas europaea and compared with the corresponding values for Anacystis nidulans and autotrophically grown Hydrogenomonas eutropha. In common with other obligate autotrophs and in contrast to facultative autotrophs, Nitrosomonas extracts lacked alpha-ketoglutaric dehydrogenase and KCN-sensitive NADH oxidase activity and had low succinic dehydrogenase activity. The Nitrosomonas NADH oxidase appeared to be of the peroxidase type.     

Biochemical and Molecular Basis of Pesticide Degradation by Microorganisms

Abstract

Fungal arachidonic acid (ARA)-rich oil is an important microbial oil that affects diverse physiological processes that impact normal health and chronic disease. In this article, the historic developments and technological achievements in fungal ARA-rich oil production in the past several years are reviewed. The biochemistry of ARA, ARA-rich oil synthesis and the accumulation mechanism are first introduced. Subsequently, the fermentation and downstream technologies are summarized. Furthermore, progress in the industrial production of ARA-rich oil is discussed. Finally, guidelines for future studies of fungal ARA-rich oil production are proposed in light of the current progress, challenges and trends in the field.     

Biochemical Basis of Obligate Autotrophy in Blue-Green Algae and Thiobacilli

Differential rates of incorporation of sugars, organic acids, and amino acids during autotrophic growth of several blue-green algae and thiobacilli have been determined. In obligate autotrophs (both blue-green algae and thiobacilli), exogenously furnished organic compounds make a very small contribution to cellular carbon; acetate, the most readily incorporated compound of those studied, contributes about 10% of newly synthesized cellular carbon. In Thiobacillus intermedius, a facultative chemoautotroph, acetate contributes over 40% of newly synthesized cellular carbon, and succinate and glutamate almost 90%. In the obligate autotrophs, carbon from pyruvate, acetate, and glutamate is incorporated into restricted groups of cellular amino acids, and the patterns of incorporation in all five organisms are essentially identical. These patterns suggest that the tricarboxylic acid cycle is blocked at the level of alpha-ketoglutarate oxidation. Enzymatic analyses confirmed the absence of alpha-ketoglutarate dehydrogenase in the obligate autotrophs, and also revealed that they lacked reduced nicotinamide adenine dinucleotide oxidase, and had extremely low levels of malic and succinic dehydrogenase. These enzymatic deficiencies were not manifested by the two facultative chemoautotrophs examined. On the basis of the data obtained, an interpretation of obligate autotrophy in both physiological and evolutionary terms has been developed.     

超干种子耐贮藏性的细胞学及生理生化基础

种子超干贮藏是近年来种子生物学研究和植物种质资源保存领域的研究热点。本文综述了种子超干贮藏研究的进展 ,包括 :(1)超干种子的细胞和亚细胞结构变化 ;(2 )超干处理对种子水分状态的影响以及与劣变反应速率的关系 ;(3)超干种子中的自由基伤害和有毒物质的积累 ;(4)超干种子中的内源抗氧剂 ;(5 )糖类物质以及两性物质对极度脱水种子细胞的保护。此外 ,还对此领域的研究进行了展望     

Biochemical Basis of Resistance of Tobacco Callus Tissue Cultures to Hydroxyphenylethylamines

It has been reported that hydroxyphenylethylamines, such as tyramine and octopamine, are toxic to tobacco (Nicotiana tabacum L.) callus cultures grown in the presence of auxins, whereas calli grown in the presence of cytokinins and crown gall cultures are resistant to these amines (P. Christou and K.A. Barton [1989] Plant Physiol 89: 564-568). In an attempt to understand the underlying mechanism of this resistance, we compared the fates of tyramine in tyramine-sensitive and tyramine-resistant tobacco tissue cultures (cv Xanthi nc). The very rapid formation of black-colored oxidation products from tyramine in sensitive tissues suggested that the toxicity might be caused by the oxidation of tyramine by phenol oxidases present in the tissues or released into the medium after subculture. This was confirmed through many indirect procedures (effect of exogenously added tyrosinase, induction of polyphenol oxidase [PPO] activity by auxin, etc.). The study of tyramine structure-activity relationships further suggested that the toxicity of tyramine might be due to the formation of indolequinones after oxidation by PPO. Subculture of calli grown on 2,4-dichlorophenoxyacetic acid in a medium containing benzyladenine triggered a slow decrease in PPO activity and dramatic increases in peroxidase and tyramine hydroxycinnamoyl transferase (THT) activities. THT was undetectable in calli grown on 2,4-dichlorophenoxyacetic acid but very active in tyramine-resistant crown gall cultures. Moreover, when [3H]tyramine was fed in vivo to tyramine-resistant tissues, it was rapidly integrated into cell walls in the wound periderm formed at the periphery of the calli. Both the conjugation of tyramine and its integration into cell walls could compete with the formation of toxic quinones and therefore play a part in the resistance. Thus, it seems likely that the control of the toxicity of hydroxyphenylethylamines by cytokinins results primarily from changes in the metabolism and the compartmentation of these amines.