Adrenergic activation of triiodothyronine production in brown adipose tissue

There are several mechanisms by which homeothermic animals increase heat production, including shivering, sympathetic nervous system activation and stimulation of thyroid hormone secretion. Studies in rats have shown that increased sympathetic activity causes increased heat production in brown adipose tissue (BAT) after cold exposure or food ingestion. Acute cold exposure also increases circulating thyroid hormones which in turn stimulate cellular metabolism through induction of various enzymes. Most metabolic effects of thyroxine (T4) are thought to be due to the triiodothyronine (T3) which is produced from T4 by a process of 5' monodeiodination. There are two enzymes responsible for this reaction: type I, or propylthiouracil (PTU)-sensitive iodothyronine deiodinase (5'D-I), which is reduced in hypothyroidism, stimulated in hyperthyroidism and probably provides most of the circulating T3 in the adult rat. Type II 5'-deiodinase (5'D-II) is characteristic of brain and pituitary, is increased by thyroidectomy, is not inhibited by PTU and provides 50-80% of the intracellular T3 in these two tissues. Recently, 5'D-II activity was identified in interscapular BAT. As the sympathetic nervous system influences the metabolic activation of BAT, we have studied the effects of noradrenaline and acute cold exposure on BAT 5'D-II. We report here that both noradrenaline and cold exposure increase BAT 5'D-II through alpha 1-adrenergic receptors, whereas depletion of catecholamines with alpha-methyl-p-tyrosine (MPT) prevents the effect of cold but not that of noradrenaline. These results suggest that the sympathetic nervous system may increase T3 production in rats by stimulating BAT 5'D-II. By increasing metabolic rate, this rise in T3 would enhance the thermogenic response to sympathetic stimulation.     

世界各国网格建设展望

网格技术的发展实现了计算资源、数据资源、信息资源、知识资源、专家资源的全面共享，引起了世界各国的高度关注。美国、英国、法国、日本以及韩国等纷纷投巨资用于网格技术的开发与应用，我国也已启动了“中国国家网格”建设项目，开始了一些前瞻性的研究工作。     

Induction of the proteolytic activity of a membrane protein in Plasmodium falciparum by phosphatidyl inositol-specific phospholipase C

Membrane anchoring of proteins by a covalently attached glycosyl-phosphatidylinositol moiety has been reported in many different eukaryotic cells including parasite protozoa. The diversity of proteins in which this phospholipid attachment is found suggests that it is functionally important and perhaps also functionally pleiotropic. Studies on the Thy-1 antigen of murine lymphocytes indicate that it can facilitate the lateral mobility of membrane proteins. It can also permit the rapid and specific release of the anchored proteins from the membrane following cleavage by a phosphatidylinositol-specific phospholipase C (PI-PLC). Here we show that this type of anchoring may be involved in the regulation of an enzymatic activity. PI-PLC releases a Plasmodium falciparum membrane protein of relative molecular mass (Mr) 76K (p76) from intact merozoites or isolated schizont membranes and induces a proteolytic activity associated with its soluble form. Endogenous activation of the proteolytic activity of p76 appears to occur at the end of the schizogony and could initiate a cascade of biochemical events associated with merozoite maturation.     

Hypercalcitonemia in pernicious anemia

Summary Gastrin has been suggested as a natural secretogogue of the hormone calcitonin. We have found hypercalcitonemia in 55% of patients with pernicious anemia, and the gastrin levels, although usually increased, did not correlate.     

生产过程实时监控软件系统

实时监控软件是一个完整的系统,应包括在线的功能系统和离线的辅助支持系统。本文介绍了一个火力发电厂安全监测系统,叙述了其组成、工作环境、性能和系统生成情况。文章还就一般的安全监测软件系统的有关问题进行了论述。     

纤维水泥砂浆的阻裂机理

主要研究墙体抹面水泥砂浆因温差变化发生微观和宏观裂缝 ,甚至扩展的多发病 ,进而阐述抹面纤维水泥砂浆阻止温差裂缝的机理 ,并说明某种规格 ,而且具有一定量纤维的纤维水泥砂浆是可以减少 ,阻止或消除温差变化引发的裂缝。这是很有经济、技术和实用价值的     

Anti-muscarinic activity of a family of C11N5 compounds isolated from Agelas sponges.

In a search for potential target sites for C11N5 compounds obtained from marine sponges of the genus Agelas we evaluated their interaction with muscarinic acetylcholine receptors from rat brain membranes. In competition experiments with 3H-QNB these compounds displayed the following rank order of potency: sceptrin greater than oroidin greater than or equal to dibromosceptrin greater than or equal to clathrodin. Sceptrin (50 microM) was shown to be a competitive inhibitor of 3H-QNB binding as revealed by Scatchard analysis. The results demonstrate the ability of these compounds to interact with multiple target molecules in the micromolar range.     

Nucleolar changes in spinal ganglion neurons during the course of axon regeneration

Résumé L'écrasement du nerf sciatique du rat modifie de plusieurs manières les nucléoles des neurones ganglionnaires rachidiens correspondants. Tandis que le volume de la pars amorpha augmente considérablement, le filament nucléolaire ou nucleolonema s'allonge, sa disposition est plus lâche, et sa coloration devient moins évidente. Ce processus atteint son maximum 15 jours après le résection du nerf et il est négligeable 60 jours plus tard. Les changements du nucleolonema et de la pars amorpha pourraient être en rapport avec la synthèse cytoplasmatique.

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Supported by grant No. AF 313-64 of the U.S. Air Force Office of Scientific Research.     

Formation of 5-hydroxytryptophol by blood platelets after thrombin and reserpine

Summary A new method for preparing semisynthetic penicillin is based on the reaction of organic acids with N,N-dimethylchloroformiminum chloride followed by condensation with salts of 6-aminopenicillanic acid. The method is very simple and has a broad application.