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1.
A method for the preparation of intact rat hepatocytes in high yield was first described in 1969. The procedure involved digestion of hepatic tissue by perfusion of the liver with crude collagenase; later, purified collagenase without other enzymic additions was shown to be ineffective. Recently it has been discovered that the combination of purified collagenase plus elastase is superior to crude collagenase in that it consistently provides high yields of undamaged hepatocytes. The isolated hepatocyte preparation has proved particularly useful for the study of mechanisms responsible for long-range interactions within the cell. These can be studied over prolonged time courses and in the presence of graded concentrations of specific inhibitors. Studies of this kind have demonstrated a close relationship between cytoplasmic metabolic flows and mitochondrial forces and have also revealed that the cytoplasmic and mitochondrial free NAD-linked redox potentials are maintained by energy-dependent reactions.  相似文献   

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近30年来广东省土壤pH值的时空变化   总被引:31,自引:0,他引:31  
基于广东省第二次土壤普查(20世纪80年代)以及2002—2007年广东省土壤pH数据,对期间土壤pH的时空变化进行了研究.结果表明:研究期间,广东省土壤pH空间分布格局基本一致;除珠江三角洲和清远、韶关部分地区土壤为弱碱性外,其他地区土壤以酸性为主;土壤pH变化整体表现为酸化,土壤pH平均值由5.70降至5.44.除潮土pH变化以增大为主外,其他土壤类型的pH均呈降低趋势,以赤红壤、水稻土和红壤pH的降幅尤为严重,石灰土pH值的降低趋势和降低面积比例均最明显.广东省土壤酸化主要受土壤本身特性和酸雨等自然因素以及不合理施肥和城市化等人为因素的影响;另外,由于工业化和矿山开发,还导致局部地区土壤pH值有所上升.  相似文献   

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When the UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR) was established in the mid-1970s, it represented an innovative institutional formula in terms of its structure and the manner in which scientists were convened from both developed and developing countries to address some of the world's most neglected parasitic diseases. A review of TDR's historical record sheds light not only on some important milestones in tropical-disease research, but also on how future challenges could be approached and hopefully surmounted.  相似文献   

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The present state of streptokinase treatment at a "moderately high dose" was presented. Based on the experience accumulated, recommendations were given for improvement of the thrombolytic therapy.  相似文献   

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2006年中国植物科学若干领域重要研究进展   总被引:4,自引:0,他引:4  
在我国经济持续稳定发展的背景下,国家通过各种研究计划(如973计划、863项目、NSFC等)和国家知识创新体系等形式大力支持具有国家战略需求的基础研究,使植物科学研究飞速发展并受到国际同行的高度重视。体现在我国不少科学家担任国际学术组织负责人或重要国际期刊编委,如许智宏院士担任国际植物组(The International Association for Plant Tissue Culture and Biotechnology,IAPTC & B;)  相似文献   

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Almost 30 years ago, neuropeptide Y (NPY) was discovered as a sympathetic co-transmitter and one of the most evolutionarily conserved peptides abundantly present all over the body. Soon afterward, NPY's multiple receptors were characterized and cloned, and the peptide's role in stress was first documented. NPY has proven to be pivotal for maintaining many stress responses. Most notably, NPY is known for activating long-lasting vasoconstriction in many vascular beds, including coronary arteries. More recently, NPY was found to play a role in stress-induced accretion of adipose tissue which many times can lead to detrimental metabolic changes. It is however due to its prominent actions in the brain, one of which is its powerful ability to stimulate appetite as well as its anxiolytic activities that NPY became a peptide of importance in neuroscience. In contrast, its actions in the rest of the body, including its role as a stress mediator, remained, surprisingly underappreciated and not well understood. Our research has focused on that other, "peripheral" side of NPY. In this review, we will discuss those actions of NPY on the cardiovascular system and metabolism, as they relate to adaptation to stress, and attempt to both distinguish NPY's effects from and integrate them with the effects of the classical stress mediators, glucocorticoids, and catecholamines. To limit the bias of someone (ZZ) who has viewed the world of stress through the eyes of NPY for over 20 years, fresh insight (DH) has been solicited to more objectively assess NPY's contributions to stress-related diseases and the body's ability to adapt to stress.  相似文献   

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林戈  卢光琇 《生命科学》2010,(12):1200-1207
1978年第一例试管婴儿诞生以及随后近30多年来该领域不断取得的突破性进展,促进了以体外受精为基础的辅助生殖技术在临床的广泛应用,并取得了很好的疗效。本文将系统回顾近30多年来辅助生殖技术在临床和实验室两方面建立的包括:控制性超排卵、序贯培养、精子胞浆内注射以及植入前遗传学诊断和筛查等主要技术突破,并对医源性多胎、新技术的安全性等目前存在的主要问题及可能的解决方案进行探讨。  相似文献   

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Embryonic stem (ES) cells are pluripotent cells isolated from an early embryo and grown as a cell line in tissue culture. Their discovery came from the conjunction of studies in human pathology, mouse genetics, early mouse embryo development, cell surface immunology and tissue culture. ES cells provided a crucial tool for manipulating mouse embryos to study mouse genetics, development and physiology. They have not only revolutionized experimental mammalian genetics but, with the advent of equivalent human ES cells, have now opened new vistas for regenerative medicine.  相似文献   

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Microtubules are not like other polymers. Whereas polymers such as F-actin will grow continuously as long as the subunit concentration is high enough, a steadily growing microtubule can suddenly shrink even when there is ample αβ-tubulin around. This remarkable behavior was discovered in 1984 when Tim Mitchison and Marc Kirschner deduced that microtubules switch from growth to shrinkage when they lose their GTP caps. Here, I review the canonical explanation of dynamic instability that was fleshed out in the years after its discovery. Many aspects of this explanation have been recently subverted, particularly those related to how GTP-tubulin forms polymers and why GTP hydrolysis disrupts them. I describe these developments and speculate on how our explanation of dynamic instability can be changed to accommodate them.  相似文献   

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This paper reviews the contribution of P. Gadal’s group to the study of phosphoenolpyruvate carboxylase (PEPC) in plants. It highlights how molecular biology and genetics have helped to advance our understanding of the PEPC multigene family, including evolutionary aspects, and the regulatory mechanisms controlling the expression of the gene encoding the photosynthetic isoform of C4 plants. Preliminary experiments using plant transformation with the aim of determining the role of PEPC isoforms in different physiological contexts and to improve crop yield are also reported.  相似文献   

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