活体牦牛人工培植牛黄药理作用的研究

本文采用比较药理学的研究方法,将培植耗牛黄与天然牛黄在同等条件下进行了生物活性的考察,研究结果表明,培植牦牛黄与天然牛黄具有镇静、抗惊厥。解热及抗炎症作用,二者的作用强度与毒性也相似,认为培植牦牛黄的药效与天然牛黄基本相似,同样可供药用。     

Pharmacological Characterization and Autoradiographic Localization of Histamine H2 Receptors in Human Brain Identified with [125I]Iodoaminopotentidine

125I-Aminopotentidine (125I-APT), a reversible probe of high specific radioactivity and high affinity and selectivity for the H2 receptor, was used to characterize and localize this histamine receptor subtype in human brain samples obtained at autopsy. On membranes of human caudate nucleus, specific 125I-APT binding at equilibrium revealed a single component, with a dissociation constant of 0.3 nM and maximal capacity of about 100 fmol/mg of protein. At 0.2 nM, 125I-APT specific binding, as defined with tiotidine, an H2-receptor antagonist chemically unrelated to iodoaminopotentidine, represented 40-50% of the total. Specific 125I-APT binding was inhibited by a series of typical H2-receptor antagonists that displayed apparent dissociation constants closely similar to corresponding values at the reference biological system, i.e., guinea pig atrium. This indicates that the pharmacology of the H2 receptor is the same in the human brain as on this reference system. However, histamine was about 10-fold more potent in inhibiting 125I-APT binding to membranes of human brain than of guinea pig brain. 125I-APT binding was also inhibited by amitriptyline and mianserin, two antidepressant drugs, in micromolar concentrations corresponding to effective plasma concentrations of treated patients. The distribution of H2 receptors was established autoradiographically with 125I-APT on a series of coronal sections of human brain after assessing the pharmacological specificity of the labeling. The highest density of 125I-APT sites was found in the basal ganglia, various parts of the limbic system, e.g., hippocampus or amygdaloid complex, and the cerebral cortex. H2 receptors displayed a laminar distribution in cerebral cortex and hippocampal formation. A low density of sites was found in cerebellum as well as in hypothalamus, the brain area where all the perikarya and the largest number of axons of histaminergic neurons are found. The widespread distribution of H2 receptors in the human brain is consistent with the alleged modulatory role of histamine mediated by this subtype of receptor.     

An ecological approach to biosystem thermodynamics

The general attributes of ecosystems are examined and a naturally occurring reference ecosystem is established, comparable with the isolated system of classical thermodynamics. Such an autonomous system with a stable, periodic input of energy is shown to assume certain structural characteristics that have an identifiable thermodynamic basis. Individual species tend to assume a state of least dissipation; this is most clearly evident in the dominant species (the species with the best integration of energy acquisition and conservation). It is concluded that ecosystem structure results from the antagonistic interaction of two nearly equal forces. These forces have their origin in the Principle of Most Action (least dissipation or least entropy production) and the universal Principle of Least Action. Most action is contingent on the equipartitioning of the energy available, through uniform interaction of similar individuals. The trend to Least action is contingent on increased dissipation attained through increasing diversity and increasing complexity. These principles exhibit a basic asymmetry. Given the operation of these opposing principles over evolutionary time, it is argued that ecosystems originated in the vicinity of thermodynamic equilibrium through the resonant amplification of reversible fluctuations. On account of the basic asymmetry the system was able to evolve away from thermodynamic equilibrium provided that it remained within the vicinity of ergodynamic equilibrium (equilibrium maintained by internal work, where the opposing forces are equal and opposite).At the highest level of generalization there appear to be three principles operating: i) maximum association of free-energy and materials; ii) energy conservation (deceleration of the energy flow) through symmetric interaction and increased homogeneity; and iii) the principle of least action which induces acceleration of the energy flow through asymmetrical interaction. The opposition and asymmetry of the two forces give rise to natural selection and evolution.     

The shortening and action potential of the cortex in the main pulvinus ofMimosa pudica

The shortening and action potential of the upper and lower cortices of the main pulvinus ofMimosa pudica were recorded simultaneously. The shortening and action potential were observed only in the lower cortex. The extensibility and the excitability of the cortex are discussed.     

中医药的抗炎机制在治疗肝纤维化中的作用

肝脏是人体腹腔内最大的实体器官,对维持机体的基本生理功能起着至关重要的作用。肝脏疾病是威胁人类健康的常见病多发病。全球约有10%人口受到不同程度的肝脏疾病的危害,其中,肝纤维化往往成为这些疾病的晚期病理特征。由于肝纤维化的发病机制复杂,尚无有效的合成类药物能够治疗肝纤维化。中药治疗肝纤维化具有多靶点和副作用小的优势。本文综述了肝纤维化的病理特征与诱发炎症的关系,讨论了中药治疗肝纤维化的单味中药、传统配方及其化学活性成分的抗炎症机制。     

Microengineered systems with iPSC-derived cardiac and hepatic cells to evaluate drug adverse effects

Hepatic and cardiac drug adverse effects are among the leading causes of attrition in drug development programs, in part due to predictive failures of current animal or in vitro models. Hepatocytes and cardiomyocytes differentiated from human induced pluripotent stem cells (iPSCs) hold promise for predicting clinical drug effects, given their human-specific properties and their ability to harbor genetically determined characteristics that underlie inter-individual variations in drug response. Currently, the fetal-like properties and heterogeneity of hepatocytes and cardiomyocytes differentiated from iPSCs make them physiologically different from their counterparts isolated from primary tissues and limit their use for predicting clinical drug effects. To address this hurdle, there have been ongoing advances in differentiation and maturation protocols to improve the quality and use of iPSC-differentiated lineages. Among these are in vitro hepatic and cardiac cellular microsystems that can further enhance the physiology of cultured cells, can be used to better predict drug adverse effects, and investigate drug metabolism, pharmacokinetics, and pharmacodynamics to facilitate successful drug development. In this article, we discuss how cellular microsystems can establish microenvironments for these applications and propose how they could be used for potentially controlling the differentiation of hepatocytes or cardiomyocytes. The physiological relevance of cells is enhanced in cellular microsystems by simulating properties of tissue microenvironments, such as structural dimensionality, media flow, microfluidic control of media composition, and co-cultures with interacting cell types. Recent studies demonstrated that these properties also affect iPSC differentiations and we further elaborate on how they could control differentiation efficiency in microengineered devices. In summary, we describe recent advances in the field of cellular microsystems that can control the differentiation and maturation of hepatocytes and cardiomyocytes for drug evaluation. We also propose how future research with iPSCs within engineered microenvironments could enable their differentiation for scalable evaluations of drug effects.     

The Naphthoquinone Diospyrin Is an Inhibitor of DNA Gyrase with a Novel Mechanism of Action

Tuberculosis and other bacterial diseases represent a significant threat to human health. The DNA topoisomerases are excellent targets for chemotherapy, and DNA gyrase in particular is a well-validated target for antibacterial agents. Naphthoquinones (e.g. diospyrin and 7-methyljuglone) have been shown to have therapeutic potential, particularly against Mycobacterium tuberculosis. We have found that these compounds are inhibitors of the supercoiling reaction catalyzed by M. tuberculosis gyrase and other gyrases. Our evidence strongly suggests that the compounds bind to the N-terminal domain of GyrB, which contains the ATPase active site, but are not competitive inhibitors of the ATPase reaction. We propose that naphthoquinones bind to GyrB at a novel site close to the ATPase site. This novel mode of action could be exploited to develop new antibacterial agents.     

Inhibition of the First Step in Synthesis of the Mycobacterial Cell Wall Core,Catalyzed by the GlcNAc-1-phosphate Transferase WecA,by the Novel Caprazamycin Derivative CPZEN-45

Because tuberculosis is one of the most prevalent and serious infections, countermeasures against it are urgently required. We isolated the antitubercular agents caprazamycins from the culture of an actinomycete strain and created CPZEN-45 as the most promising derivative of the caprazamycins. Herein, we describe the mode of action of CPZEN-45 first against Bacillus subtilis. Unlike the caprazamycins, CPZEN-45 strongly inhibited incorporation of radiolabeled glycerol into growing cultures and showed antibacterial activity against caprazamycin-resistant strains, including a strain overexpressing translocase-I (MraY, involved in the biosynthesis of peptidoglycan), the target of the caprazamycins. By contrast, CPZEN-45 was not effective against a strain overexpressing undecaprenyl-phosphate–GlcNAc-1-phosphate transferase (TagO, involved in the biosynthesis of teichoic acid), and a mutation was found in the tagO gene of the spontaneous CPZEN-45-resistant strain. This suggested that the primary target of CPZEN-45 in B. subtilis is TagO, which is a different target from that of the parent caprazamycins. This suggestion was confirmed by evaluation of the activities of these enzymes. Finally, we showed that CPZEN-45 was effective against WecA (Rv1302, also called Rfe) of Mycobacterium tuberculosis, the ortholog of TagO and involved in the biosynthesis of the mycolylarabinogalactan of the cell wall of M. tuberculosis. The outlook for WecA as a promising target for the development of antituberculous drugs as a countermeasure of drug resistant tuberculosis is discussed.     

Dynamin Isoforms Decode Action Potential Firing for Synaptic Vesicle Recycling

Presynaptic nerve terminals must maintain stable neurotransmission via synaptic vesicle membrane recycling despite encountering wide fluctuations in the number and frequency of incoming action potentials (APs). However, the molecular mechanism linking variation in neuronal activity to vesicle trafficking is unknown. Here, we combined genetic knockdown and direct physiological measurements of synaptic transmission from paired neurons to show that three isoforms of dynamin, an essential endocytic protein, work individually to match vesicle reuse pathways, having distinct rate and time constants with physiological AP frequencies. Dynamin 3 resupplied the readily releasable pool with slow kinetics independently of the AP frequency but acted quickly, within 20 ms of the incoming AP. Under high-frequency firing, dynamin 1 regulated recycling to the readily releasable pool with fast kinetics in a slower time window of greater than 50 ms. Dynamin 2 displayed a hybrid response between the other isoforms. Collectively, our findings show how dynamin isoforms select appropriate vesicle reuse pathways associated with specific neuronal firing patterns.