Alterations in Electrolyte and Trace-Element Concentrations During Simulated Extracorporeal Blood Circulation

In our studies with simulated extracorporeal blood circulation we observe damaging effects on blood cells, especially under oxygenating conditions. In order to characterize these effects we also analysed electrolyte and trace-element concentrations in plasma during and after simulated extracorporeal blood circulation. Highest resorption effects for magnesium and highest desorption effects for calcium, copper and iron are found with oxygen gas flow in the system. Membrane permeability for electrolytes seems to be induced as well. Cellular damage due only to mechanical stress within the perfusion system can be neglected.     

Effects of peptides: a cross-listing of peptides and their central actions published in the journal Peptides from 1994 through 1998.

Effects of peptides on the central nervous system are presented in two ways so as to provide a cross-listing. In the first table, the peptides are listed alphabetically. In the second table, the central nervous system effects are arranged alphabetically. No longer can there be any doubt that peptides affect the central nervous system, sometimes in several ways.     

中国昆虫生态学研究的透视

<正> 昆虫生态学在我国是通过几十年来密切结合农、林、牧实际,解决生产中不断提出的重大问题而发展起来的。随着研究问题不断深入,交叉学科不断渗透,使昆虫生态学在生物学宏观领域中成为迅速发展的一门学科。现将7个主要领域研究的动态加以评述。     

放牧对草原土壤的影响

介绍了放牧对草原土壤物理性质 (容重、渗透率 )、化学性质 (有机质、N素 )和微生物的影响。由于草原土壤系统本身的复杂性、滞后性和弹性 ,放牧对土壤性质的影响不尽相同。一般而言 ,随放牧强度的增大 ,动物践踏作用的增强 ,土壤孔隙分布的空间格局发生变化 ,土壤的总孔隙减少 ,特别是大孔隙 (>5 0μm)和较大中等孔隙 (9～ 5 0μm)减少 ,使土壤容重增加 ,土壤的渗透阻力加大 ,土壤的保水和持水能力下降。但在有机质含量很低的沙质土壤中 ,超载过牧 ,造成有机质含量降低 ,土壤的团粒结构减少 ,稳定性团聚体减少 ,土壤结构遭到破坏 ,使得土壤容重反而降低。土壤有机质和放牧之间存在复杂的相互关系 ,土壤有机质对放牧的响应受多种因素的影响 ,这些因素包括植被和土壤的初始状况 ;环境因素 ,特别是水分和温度 ;放牧历史 (强度、频率、持续时间和动物类型 )。同时 ,土壤有机质含量低的土壤比含量高的土壤更易受放牧的影响 ,而使有机质发生变化。土壤微生物量碳是最具活性的土壤碳库 ,对环境的变化敏感 ,能较早地指示生态系统功能的变化。当考虑时间尺度时 ,高强度放牧对土壤肥力有负面的影响 ,短期内 ,由于加速了养分的循环效率 ,产生有利的影响 ,但长期无管理的超载放牧必然造成系统物质 (资源 )输入和输     

Sphingosine 1-phosphate as a novel immune regulator of dendritic cells

Although originally described as an intracellular second messenger, sphingosine 1-phosphate (S1P) has recently been shown to be involved in several physiological and pathological functions as an extracellular mediator. S1P receptors are widely expressed and thought to regulate important functions in cell signalling. Recently, the role of S1P on the immune system has evoked great interest. In particular, several aspects of the effects on antigen-presenting cells (APCs) as dendritic cells (DC) in mice and humans have been reported. In this review, we focus on the role played by S1P on the DC system and its effects in immune-related pathological states.     

Sphingosine 1-phosphate as a novel immune regulator of dendritic cells

Although originally described as an intracellular second messenger, sphingosine 1-phosphate (S1P) has recently been shown to be involved in several physiological and pathological functions as an extracellular mediator. S1P receptors are widely expressed and thought to regulate important functions in cell signalling. Recently, the role of S1P on the immune system has evoked great interest. In particular, several aspects of the effects on antigen-presenting cells (APCs) as dendritic cells (DC) in mice and humans have been reported. In this review, we focus on the role played by S1P on the DC system and its effects in immune-related pathological states.     

The joint evolution of lifespan and self‐fertilization

In Angiosperms, there exists a strong association between mating system and lifespan. Most self‐fertilizing species are short‐lived, and most predominant or obligate outcrossers are long‐lived. This association is generally explained by the influence of lifespan on the evolution of the mating system, considering lifespan as fixed. Yet, lifespan can itself evolve, and the mating system may as well influence the evolution of lifespan, as is suggested by joint evolutionary shifts of lifespan and mating system between sister species. In this paper, we build modifier models to study the joint evolution of self‐fertilization and lifespan, including both juvenile and adult inbreeding depression. We show that provided that inbreeding depression affects adult survival, self‐fertilization is expected to promote evolution towards shorter lifespan, and that the range of conditions under which selfing can evolve rapidly shrinks as lifespan increases. We study the effects of inbreeding depression affecting various steps in the life cycle and discuss how extrinsic mortality conditions are expected to affect evolutionary associations. In particular, we show that selfers may sometimes remain short‐lived even in a very stable habitat, as a strategy to avoid the deleterious effects of inbreeding.     

The endocannabinoid system: a revolving plate in neuro-immune interaction in health and disease

Studies of the last 40 years have brought to light an important physiological network, the endocannabinoid system. Endogenous and exogenous cannabinoids mediate their effects through activation of specific cannabinoid receptors. This modulatory homoeostatic system operates in the regulation of brain function and also in the periphery. The cannabinoid system has been shown to be involved in regulating the immune system. Studies examining the effect of cannabinoid-based drugs on immunity have shown that many cellular and cytokine mechanisms are modulated by these agents, thus raising the hypothesis that these compounds may be of value in the management of chronic inflammatory diseases. The special properties of endocannabinoids as neurotransmitters, their pleiotropic effects and the impact on immune function show that the endocannabinoid system represents a revolving plate of neural and immune interactions. In this paper, we outline current information on immune effects of cannabinoids in health and disease.     

Intra- and interspecific density dependence mediates weather effects on the population dynamics of a plant–insect herbivore system

Temperature and precipitation are two major factors determining arthropod population densities, but the effects from these climate variables are seldom evaluated in the same study system and in combination with inter- and intraspecific density dependence. In this study, I used a 19 year time series on plant variables (shoot height and flowering incidence) and insect density in order to understand direct and indirect effects of climatic fluctuations on insect population densities. The study system includes two closely related leaf beetle species (Galerucella spp.) and a flower feeding weevil Nanophyes marmoratus attacking the plant purple loosestrife Lythrum salicaria. Results suggest that both intraspecific density dependence and weather variables affected Galerucella population densities, with interactive effects of rain and temperature on insect densities that depended on the timing relative to insect life cycles. In spring, high temperatures increased Galerucella densities only when combined with high rain, as low rain implies a high drought risk. Low temperatures are only beneficial if combined with little rain, as high rain cause chilly and wet conditions that are bad for insects. In summer, interactive effects of rain and temperature are different because high temperatures and little rain cause drought that induce wilting in plants, thus reducing food availability for the leaf feeding larvae. In contrast, the density of the flower feeding weevil was less affected by temperature and precipitation directly, and more indirectly interspecific density dependent effects through reduced resource availability caused by previous Galerucella damage.     

A high throughput system for long term application of intermittent cyclic hydrostatic pressure on cells in culture

The process of bone remodeling is governed by mechanical stresses and strains. Studies on the effects of mechanical stimulation on cell response are often difficult to compare as the nature of the stimuli and differences in parameters applied vary greatly. Experimental systems for the investigation of mechanical stimuli are mostly limited in throughput or flexibility and often the sum of several stimuli is applied. In this work, a flexible system that allows the investigation of cell response to isolated intermittent cyclic hydrostatic pressure (icHP) on a high throughput level is shown. Human bone derived cells were cultivated with or without mechanical stimulus in the presence or absence of chemical cues triggering osteogenesis for 7-10 days. Cell proliferation and osteogenic differentiation were evaluated by cell counting and immunohistochemical staining for bone alkaline phosphatase as well as collagen 1, respectively. In either medium, both cell proliferation and level of differentiation were increased when the cultures were mechanically stimulated. These initial results therefore qualify the present system for studies on the effects of isolated icHP on cell fate and encourage further investigations on the details behind the observed effects.     

Maternal transfer of antibodies in vertebrates: trans-generational effects on offspring immunity

Maternal effects by which females provide their offspring with non-genetic factors such as hormones, nutrients and antibodies can have an important impact on offspring fitness. In vertebrates, maternal antibodies (matAb) are transferred from the mother, via the placenta, egg yolk or milk during lactation to offspring until they are 2 weeks (birds), 4-10 weeks (rodents) and 9 months (humans) old, respectively. matAb transfer can have direct effects on offspring growth rate in birds and rodents, probably by passively protecting the newborn from common pathogens before their endogenous immune system has matured. Indirect long-term effects of matAb transfer on the offspring's own immunity can be synergistic, if matAb act as antigen templates of the accumulated immunological experience of the mother and educate the newborn's immune system. However, it may also be suppressive if matAb reduce antigen presentation to the newborn resulting in antigen-specific blocking of offspring endogenous immunity. Our aim is to review the mechanisms and direct effects of matAb transfer in vertebrates with an emphasis on birds, outline a framework for research on the long-term effects of matAb on the endogenous immune system of the mature offspring and encourage ecological and evolutionary studies of matAb transfer in non-domesticated animals.     

Dissecting the effects of nitrate, sucrose and osmotic potential on Arabidopsis root and shoot system growth in laboratory assays

Studying the specific effects of water and nutrients on plant development is difficult because changes in a single component can often trigger multiple response pathways. Such confounding issues are prevalent in commonly used laboratory assays. For example, increasing the nitrate concentration in growth media alters both nitrate availability and osmotic potential. In addition, it was recently shown that a change in the osmotic potential of media alters the plant's ability to take up other nutrients such as sucrose. It can also be difficult to identify the initial target tissue of a particular environmental cue because there are correlated changes in development of many organs. These growth changes may be coordinately regulated, or changes in development of one organ may trigger changes in development of another organ as a secondary effect. All these complexities make analyses of plant responses to environmental factors difficult to interpret. Here, we review the literature on the effects of nitrate, sucrose and water availability on root system growth and discuss the mechanisms underlying these effects. We then present experiments that examine the impact of nitrate, sucrose and water on root and shoot system growth in culture using an approach that holds all variables constant except the one under analysis. We found that while all three factors also alter root system size, changes in sucrose and osmotic potential also altered shoot system size. In contrast, we found that, when osmotic effects are controlled, nitrate specifically inhibits root system growth while having no effect on shoot system growth. This effectively decreases the root : shoot ratio. Alterations in root : shoot ratio have been widely observed in response to nitrogen starvation, where root growth is selectively increased, but the present results suggest that alterations in this ratio can be triggered across a wide spectrum of nitrate concentrations.     

Reliability Analysis of the Electrical Control System of Subsea Blowout Preventers Using Markov Models

Reliability analysis of the electrical control system of a subsea blowout preventer (BOP) stack is carried out based on Markov method. For the subsea BOP electrical control system used in the current work, the 3-2-1-0 and 3-2-0 input voting schemes are available. The effects of the voting schemes on system performance are evaluated based on Markov models. In addition, the effects of failure rates of the modules and repair time on system reliability indices are also investigated.     

Presence and functional regulation of cannabinoid receptors in immune cells.

In the last 30 years studies on drug-abusing humans and animals injected with cannabinoids, as well as in vitro models employing immune cell cultures, have demonstrated that marijuana and cannabinoids are immunomodulators. Both types of cannabinoid receptors, CB1 and CB2, have been found in immune cells, suggesting they are important in mediating the effects of cannabinoids on the immune system. This article reviews the data on the function and distribution of cannabinoid receptors in the immune system and their involvement in the immunomodulatory effect of these substances.     

The endocannabinoid system in normal and pathological brain ageing

The role of endocannabinoids as inhibitory retrograde transmitters is now widely known and intensively studied. However, endocannabinoids also influence neuronal activity by exerting neuroprotective effects and regulating glial responses. This review centres around this less-studied area, focusing on the cellular and molecular mechanisms underlying the protective effect of the cannabinoid system in brain ageing. The progression of ageing is largely determined by the balance between detrimental, pro-ageing, largely stochastic processes, and the activity of the homeostatic defence system. Experimental evidence suggests that the cannabinoid system is part of the latter system. Cannabinoids as regulators of mitochondrial activity, as anti-oxidants and as modulators of clearance processes protect neurons on the molecular level. On the cellular level, the cannabinoid system regulates the expression of brain-derived neurotrophic factor and neurogenesis. Neuroinflammatory processes contributing to the progression of normal brain ageing and to the pathogenesis of neurodegenerative diseases are suppressed by cannabinoids, suggesting that they may also influence the ageing process on the system level. In good agreement with the hypothesized beneficial role of cannabinoid system activity against brain ageing, it was shown that animals lacking CB1 receptors show early onset of learning deficits associated with age-related histological and molecular changes. In preclinical models of neurodegenerative disorders, cannabinoids show beneficial effects, but the clinical evidence regarding their efficacy as therapeutic tools is either inconclusive or still missing.     

噪声和高温对机体健康影响的复合效应

当今社会随着经济和科技的发展,多种有害职业因素往往共同存在于同一岗位。复合因素对机体健康影响的相互作用包括四种情况:协同作用、相加作用、拮抗作用和无关作用。噪声和高温作为有害的职业因素常存在于同一岗位,那么噪声复合高温对机体健康会产生怎样的影响,这两种环境因素是否存在复合效应?文献报道不一。噪声和高温联合对听觉系统、心血管系统、神经系统的影响可能表现为协同、相加、拮抗和无关作用,对呼吸系统的影响表现为拮抗作用,目前,研究结果不一致主要原因是实验条件和暴露方法的不一致。我们认为将来的研究热点集中在噪声和高温联合产生复合效应的条件及剂量反应关系研究、机制及防治措施研究,噪声和高温联合对其他系统如消化、免疫系统是否存在复合效应也值得深入研究。     

The placebo effect and the autonomic nervous system: evidence for an intimate relationship

For many subjectively experienced outcomes, such as pain and depression, rather large placebo effects have been reported. However, there is increasing evidence that placebo interventions also affect end-organ functions regulated by the autonomic nervous system (ANS). After discussing three psychological models for autonomic placebo effects, this article provides an anatomical framework of the autonomic system and then critically reviews the relevant placebo studies in the field, thereby focusing on gastrointestinal, cardiovascular and pulmonary functions. The findings indicate that several autonomic organ functions can indeed be altered by verbal suggestions delivered during placebo and nocebo interventions. In addition, three experimental studies provide evidence for organ-specific effects, in agreement with the current knowledge on the central control of the ANS. It is suggested that the placebo effects on autonomic organ functions are best explained by the model of 'implicit affordance', which assumes that placebo effects are dependent on 'lived experience' rather than on the conscious representation of expected outcomes. Nevertheless, more studies will be needed to further elucidate psychological and neurobiological pathways involved in autonomic placebo effects.     

Repeated insect defoliation effects on growth, nitrogen acquisition, carbohydrates, and root demography of poplars

Large-scale outbreaks of defoliating insects are common in temperate forests. The effects of defoliation on tree physiology are expected to cascade through the entire forest ecosystem, altering carbon, nitrogen, and water fluxes, and subsequently affecting nitrogen cycling and plant-herbivore interactions. If these post-defoliation changes are largely driven by N deficiency, tree root system responses to defoliation should be central to regulating the long-term effects of defoliation; N fertilization should reverse the effects. We examined these phenomena in a 3-year large-scale replicated manipulative field experiment in a hybrid poplar plantation, where we regulated defoliation by gypsy moths as well as nitrogen availability. To our knowledge, this is the first manipulative field experiment at this scale to examine the effects of severe insect defoliation on whole-tree physiology. Defoliation decreased tree growth and increased the rate of top dieback in the stand. Defoliation led to transient declines in carbon allocation to starch in fine roots, trunk, and twigs in the year of heaviest defoliation. Root production and root mortality were unaffected by the heaviest defoliation, but nitrate and ammonium uptake were strongly depressed. N fertilization increased tree growth, but did not alter defoliation effects on starch accumulation or top dieback. Defoliation and fertilization treatments did not interact. In this system, defoliation effects on tree recovery of leaf nitrogen lost to herbivory were primarily driven by effects on nitrogen uptake, rather than effects on root production or mortality.     

Inducible expression of encephalomyocarditis virus 3C protease activity in stably transformed mouse cell lines.

An inducible expression vector system has been developed to facilitate the study of the effects of individual virus gene products on cell function. The vector utilizes the mouse metallothionein promoter carried on the bovine papillomavirus genome. Conditions which optimize the induced expression of open reading frames inserted downstream from the mouse metallothionein promoter have recently been described. In this communication we describe the use of this system to clone and express the encephalomyocarditis virus 3C protease in cultured mouse cells. Stably transformed cell lines could be induced to produce levels of 3C protease activity comparable to those observed during normal virus infection. In spite of this, no effects on cellular protein synthesis rate or membrane permeability were observed. It was also discovered that 3C protease as well as 3C protease-containing polyproteins are turned over. This was true not only in the induced cell clones, but also during the normal course of encephalomyocarditis virus infection, as well as in translation systems in vitro. This phenomenon was highly specific for this family of polypeptides, perhaps explaining their apparent lack of cytotoxic effects.