Ethanol and the benzodiazepine-GABA receptor-ionophore complex

Ethanol has a pharmacological profile similar to that of classes of drugs like benzodiazepines and barbiturates, which enhance GABAergic transmission in the mammalian CNS. Several lines of behavioral, electrophysiological and biochemical studies suggest that ethanol may bring about most of its effects by enhancing GABAergic transmission. Recently, ethanol at relevant pharmacological concentrations has been shown to enhance GABA-induced 36Cl-fluxes in cultured spinal cord neurons, synaptoneurosomes and microsacs. These enhancing effects of ethanol were blocked by GABA antagonists. Ro15-4513, an azido analogue of classical BZ antagonist Ro15-1788, reversed most of the behavioral effects of ethanol and other effects involving 36Cl-flux studies. The studies summarized below indicate that most of the pharmacological effects of ethanol can be related to its effects on GABAergic transmission.     

Ethanol and the benzodiazepine-GABA receptor-ionophore complex

Summary Ethanol has a pharmacological profile similar to that of classes of drugs like benzodiazepines and barbiturates, which enhance GABAergic transmission in the mammalian CNS. Several lines of behavioral, electrophysiological and biochemical studies suggest that ethanol may bring about most of its effects by enhancing GABAergic transmission. Recently, ethanol at relevant pharmacological concentrations has been shown to enhance GABA-induced³⁶Cl-fluxes in cultured spinal cord neurons, synaptoneurosomes and microsacs. These enhancing effects of ethanol were blocked by GABA antagonists. Ro15-4513, an azido analogue of classical BZ antagonist Ro15-1788, reversed most of the behavioral effects of ethanol and other effects involving³⁶Cl-flux studies. The studies summarized below indicate that most of the pharmacological effects of ethanol can be related to its effects on GABAergic transmission.     

Amnesic effects of intravenous diazepam and lorazepam.

The amnesic effects of 2 benzodiazepine drugs, diazepam (Valium) and lorazepam (Ativan), have been investigated. Some of the effects were similar to those of certain clinical amnesic syndromes. The effects were more extensive than previous work has indicated.     

不同物理环境对体外培养动物细胞的影响

本文介绍了生物物理领域中不同物理环境对体外培养的动物细胞增殖方面的研究进展。着重介绍了各种电磁场对不同细胞增殖的影响；失重、超重刺激对细胞增殖的影响；激光照射对细胞增殖的影响；以及不同力学环境对细胞分裂、增殖的影响。     

Antiarrhythmic peptide has no direct cardiac actions

The electrophysiologic, inotropic, and muscarinic effects of antiarrhythmic peptide (AAP) were examined in canine cardiac Purkinje fibers, ferret papillary muscle, and canine cardiac membranes, respectively. Aside from a prolongation of time to peak force in papillary muscle, no biologically significant effects of AAP could be determined in any preparation, suggesting that its antiarrhythmic effects are not mediated by direct membrane actions.     

Low-dose radiation accelerates aging of the T-cell receptor repertoire in CBA/Ca mice

While the biological effects of high-dose-ionizing radiation on human health are well characterized, the consequences of low-dose radiation exposure remain poorly defined, even though they are of major importance for radiological protection. Lymphocytes are very radiosensitive, and radiation-induced health effects may result from immune cell loss and/or immune system impairment. To decipher the mechanisms of effects of low doses, we analyzed the modulation of the T-cell receptor gene repertoire in mice exposed to a single low (0.1 Gy) or high (1 Gy) dose of radiation. High-throughput T-cell receptor gene profiling was used to visualize T-lymphocyte dynamics over time in control and irradiated mice. Radiation exposure induces “aging-like” effects on the T-cell receptor gene repertoire, detectable as early as 1 month post-exposure and for at least 6 months. Surprisingly, these effects are more pronounced in animals exposed to 0.1 Gy than to 1 Gy, where partial correction occurs over time. Importantly, we found that low-dose radiation effects are partially due to the hematopoietic stem cell impairment. Collectively, our findings show that acute low-dose radiation exposure specifically results in long-term alterations of the T-lymphocyte repertoire.     

Histamine receptor-mediated signaling during development and brain function in adulthood

Histamine might have an important role in brain development. However, most studies have focused on short-term effects of histamine receptor-mediated signaling on brain function in adulthood. Little is known about the potential long-term effects of histamine receptor-mediated signaling during development on brain function in adulthood. We hypothesize that increased postsynaptic histamine receptor-mediated signaling during development has detrimental effects on brain function in adulthood. Our data support this hypothesis. In the developing mouse brain, histamine H3 receptor blockade, which increases histamine release, has detrimental sex-dependent effects on object recognition, spatial learning in the water maze, and pre-pulse inhibition in adulthood. Our data also support the hypothesis that histamine mediates the detrimental long-term sex-dependent effects of methamphetamine exposure early in life on these brain functions in adulthood. Therefore, increased efforts are warranted to carefully evaluate the effects of drugs that directly or indirectly affect histamine receptor-mediated signaling during development on cognitive function later in life.     

Polyphenolic phytochemicals – just antioxidants or much more?

Polyphenolic phytochemicals are ubiquitous in plants, in which they function in various protective roles. A ‘recommended’ human diet contains significant quantities of polyphenolics, as they have long been assumed to be ‘antioxidants’ that scavenge excessive, damaging, free radicals arising from normal metabolic processes. There is recent evidence that polyphenolics also have ‘indirect’ antioxidant effects through induction of endogenous protective enzymes. There is also increasing evidence for many potential benefits through polyphenolic-mediated regulation of cellular processes such as inflammation. Inductive or signalling effects may occur at concentrations much lower than required for effective radical scavenging. Over the last 2 – 3 years, there have been many exciting new developments in the elucidation of the in vivo mechanisms of the health benefits of polyphenolics. We summarise the current knowledge of the intake, bio-availability and metabolism of polyphenolics, their antioxidant effects, regulatory effects on signalling pathways, neuro-protective effects and regulatory effects on energy metabolism and gut health. Received 14 May 2007; received after revision 27 June 2007; accepted 24 July 2007     

Antiarrhythmic peptide has no direct cardiac actions

Summary The electrophysiologic, inotropic, and muscarinic effects of antiarrhythmic, peptide (AAP) were examined in canine cardiac Purkinje fibers, ferret papillary muscle, and canine cardiac membranes, respectively. Aside from a prolongation of time to peak force, in papillary muscle, no biologically significant effects of AAP could be determined in any, preparation, suggesting that its antiarrhythmic, effects are not mediated by direct membrane actions.     

Anticholinesterase-like activity by oriental hornet (Vespa orientalis) venom and venom sac extract.

Oriental hornet venom or venom sac extract produces pharmacological and toxicological effects typical of anticholinesterase agents. The effects produced in animals can be counteracted by atropine and heparin.     

Modification of the effect of cardio-accelerator nerve stimulation in dogs by clonidine and several alpha-adrenolytics]

In dogs anaesthetized with pentobarbital (30 mg. kg -1 i.v.), clonidine (0,01 mg.kg-1 i.v.) reduced the tachycardia induced at low frequencies by stimulation of the cardiac nerve. The effects of some alpha-adrenoceptor blocking agents on this effect have been studied. Small doses of yohimbine (0.3 mg. kg-1 i.v.) or piperoxan (0.3 mg. kg-1 i.v.) increased the effects of the stimulation and in addition antagonized the inhibitory effects of clonidine and reversed the pressor response to adrenaline. Thymoxamine (1 mg.kg-1 i.v.) and prazosin (1 mg.kg-1 i.v.) did not increase the effect of the stimulation of the cardiac nerve, but reduced the effect of clonidine. ARC239 (0.05 mg.kg-1) reversed the pressor response to adrenaline but even at high doses did not increase the effects of the stimulation of the cardiac nerve or the effects of clonidine. These observations afford further evidence for a dissimilarity between pre and post-synaptic alpha-adrenoceptors.     

Anticholinesterase-like activity by oriental hornet (Vespa orientalis) venom and venom sac extract

Summary Oriental hornet venom or venom sac extract produces pharmacological and toxicological effects typical of anticholinesterase agents. The effects produced in animals can be counteracted by atropine and heparin.     

外来物种水葫芦的生态环境效应

任何外来物种均是“双刃剑”，其带来的生态环境效应有利有弊。在当前全面否定外来物种的形势下，如何正确客观评估水葫芦这样的外来种的生态环境效应成为一项迫切工作。本文从辩证的角度出发，论述水葫芦的生态环境效应(正、负)。水葫芦二十世纪初引入中国后作为家禽饲料推广养植，带来了牲畜饲料、改良水质、抑制藻类、供作绿肥、沤制沼气、栽培草菇等积极的生态环境效应，也带来了阻塞航道、影响水产养殖产量和质量、降低水体物种丰富度，破坏水体生物多样性、污染水体、加剧富营养化、使用后的二次污染等生态环境负效应。引种前缺乏对外来物种理性而全面的认识是水葫芦危害的根源，而引种后缺乏有效监控与管理则是水葫芦危害及其扩大化的根本，强化水葫芦的生态效应特别是负效应与生态控制技术开发的深入研究是目前有效规避水葫芦危害的关键。生物控制、水体生态系统调控、人为干预以及合理利用等综合措施应是水葫芦生态控制的重点。     

Forecasting value‐at‐risk with a parsimonious portfolio spillover GARCH (PS‐GARCH) model

Accurate modelling of volatility (or risk) is important in finance, particularly as it relates to the modelling and forecasting of value‐at‐risk (VaR) thresholds. As financial applications typically deal with a portfolio of assets and risk, there are several multivariate GARCH models which specify the risk of one asset as depending on its own past as well as the past behaviour of other assets. Multivariate effects, whereby the risk of a given asset depends on the previous risk of any other asset, are termed spillover effects. In this paper we analyse the importance of considering spillover effects when forecasting financial volatility. The forecasting performance of the VARMA‐GARCH model of Ling and McAleer (2003), which includes spillover effects from all assets, the CCC model of Bollerslev (1990), which includes no spillovers, and a new Portfolio Spillover GARCH (PS‐GARCH) model, which accommodates aggregate spillovers parsimoniously and hence avoids the so‐called curse of dimensionality, are compared using a VaR example for a portfolio containing four international stock market indices. The empirical results suggest that spillover effects are statistically significant. However, the VaR threshold forecasts are generally found to be insensitive to the inclusion of spillover effects in any of the multivariate models considered. Copyright © 2008 John Wiley & Sons, Ltd.     

Végétalisation de l'œuf de l'oursinParacentrotus lividus par le chloramphénicol

Summary Chloramphenicol, an inhibitor of protein synthesis, causes a strong vegetalization of whole larvae of sea urchinParacentrotus lividus. Combination of chloramphenicol and lithium causes a stronger vegetalization than either of these agents alone. Chloramphenicol suppresses the animalizing effects of Evans blue and zinc ions. The effects of chloramphenicol are compared with those of lithium and phenazone. It is suggested that vegetalizing effects of chloramphenicol are connected with its inhibitory action on protein synthesis and the perturbations of ribonucleic acid metabolism.     

考虑光照影响的静态图像感兴趣区域提取

考虑光照对感兴趣区域提取的影响,提出了一种新的基于边缘的感兴趣区域提取算法.该算法基于二维离散小波变换去除了光照对感兴趣区域的影响;并通过对所采集的边缘像素点评价进一步去除了光照在感兴趣区域产生的阴影边缘.将该算法运用于长途客车过道区域的提取.实验结果表明,提出的算法不仅能实现多种情况下的感兴趣区域的自动准确的提取,还能避免光照的影响     

Brain homeostasis: VEGF receptor 1 and 2—two unequal brothers in mind

Vascular endothelial growth factors (VEGFs), initially thought to act specifically on the vascular system, exert trophic effects on neural cells during development and adulthood. Therefore, the VEGF system serves as a promising therapeutic target for brain pathologies, but its simultaneous action on vascular cells paves the way for harmful side effects. To circumvent these deleterious effects, many studies have aimed to clarify whether VEGFs directly affect neural cells or if the effects are mediated secondarily via other cell types, like vascular cells. A great number of reports have shown the expression and function of VEGF receptors (VEGFRs), mainly VEGFR-1 and -2, in neural cells, where VEGFR-2 has been described as the major mediator of VEGF-A signals. This review aims to summarize and compare the divergent roles of VEGFR-1 and -2 during CNS development and homeostasis.     

Innervation and control of the heart of a gastropod,Rapana

Summary The innervation and control of the heart of a prosobranch mollusc,Rapana thomasiana, were studied. Acetylcholine was found to be an inhibitory neurotransmitter. Both serotonin and FMRFamide (Phe-Met-Arg-Phe-NH₂) showed excitatory effects on the heart; FMRFamide had greater inotropic and more regulatory chronotropic effects than serotonin. The effects of serotonin were blocked by methysergide, while the effects of FMRFamide and of stimulating the excitatory cardiac nerves were not blocked. Stimulation of circumesophageal ganglia elicited a slow enhancement of heart beat together with body movement. This enhancement was blocked by methysergide. Serotonin was considered to act at the heart as a local neurohormone. Although the mechanism of action of FMRFamide is still not yet clarified, it is possible that FMRFamide plays a physiological role as a cardioregulatory substance, as indicated by the physiological and histological findings.     

The buzz on caffeine in invertebrates: effects on behavior and molecular mechanisms

A number of recent studies from as diverse fields as plant–pollinator interactions, analyses of caffeine as an environmental pollutant, and the ability of caffeine to provide protection against neurodegenerative diseases have generated interest in understanding the actions of caffeine in invertebrates. This review summarizes what is currently known about the effects of caffeine on behavior and its molecular mechanisms in invertebrates. Caffeine appears to have similar effects on locomotion and sleep in both invertebrates and mammals. Furthermore, as in mammals, caffeine appears to have complex effects on learning and memory. However, the underlying mechanisms for these effects may differ between invertebrates and vertebrates. While caffeine’s ability to cause release of intracellular calcium stores via ryanodine receptors and its actions as a phosphodiesterase inhibitor have been clearly established in invertebrates, its ability to interact with invertebrate adenosine receptors remains an important open question. Initial studies in insects and mollusks suggest an interaction between caffeine and the dopamine signaling pathway; more work needs to be done to understand the mechanisms by which caffeine influences signaling via biogenic amines. As of yet, little is known about whether other actions of caffeine in vertebrates, such as its effects on GABA_A and glycine receptors, are conserved. Furthermore, the pharmacokinetics of caffeine remains to be elucidated. Overall behavioral responses to caffeine appear to be conserved amongst organisms; however, we are just beginning to understand the mechanisms underlying its effects across animal phyla.