In Vitro Retina as an Experimental Model of the Central Nervous System

Abstract Methods are described for isolating adult rabbit retina and maintaining it in a medium designed to resemble CSF. Morphologic, metabolic, and electrophysiologic measurements obtained on the in vitro retinas showed that they remained in a nearly physiological state for at least 8 h, and even after 2 days in vitro they still exhibited a high level of metabolic activity and electrical responsiveness to light. Physiological activity was modified by photic stimulation, and data are presented to document changes in metabolism in response to the changes in function. The isolated retina appears to offer a number of unusual advantages for studying relationships between function and metabolism in organized mammalian central nervous tissue     

Unnoticed ingestion of dislodged fixed prosthesis in an elderly patient

doi: 10.1111/j.1741‐2358.2010.00408.x
Unnoticed ingestion of dislodged fixed prosthesis in an elderly patient     

Hindmarsh-Rose神经模型的混沌控制

应用稳定性准则的混沌控制方法控制单个Hindmarsh-Rose神经元模型的混沌发放峰序列和混沌爆发运动。通过对膜电压的非线性连续-时间反馈干扰的输入,将混沌运动控制到5峰／爆发（5spikes/burst）轨道上,该轨道嵌入在混沌吸引子内。数值模拟结果显示该方法在控制HR神经元模型方面是有效的。     

Information-Theoretic Analysis of the Dynamics of an Executable Biological Model

To facilitate analysis and understanding of biological systems, large-scale data are often integrated into models using a variety of mathematical and computational approaches. Such models describe the dynamics of the biological system and can be used to study the changes in the state of the system over time. For many model classes, such as discrete or continuous dynamical systems, there exist appropriate frameworks and tools for analyzing system dynamics. However, the heterogeneous information that encodes and bridges molecular and cellular dynamics, inherent to fine-grained molecular simulation models, presents significant challenges to the study of system dynamics. In this paper, we present an algorithmic information theory based approach for the analysis and interpretation of the dynamics of such executable models of biological systems. We apply a normalized compression distance (NCD) analysis to the state representations of a model that simulates the immune decision making and immune cell behavior. We show that this analysis successfully captures the essential information in the dynamics of the system, which results from a variety of events including proliferation, differentiation, or perturbations such as gene knock-outs. We demonstrate that this approach can be used for the analysis of executable models, regardless of the modeling framework, and for making experimentally quantifiable predictions.     

斜纹猫蛛生物学特性的观察

对斜纹猫蛛的生物学特性进行观察,结果表明,斜纹猫蛛在鲁东南沿海地区一年发生一代,以不同的若蛛在松树翘皮下、枝叶基部和杂草丛中越冬,翌年4月上旬出蛰活动,若（幼）蛛经7龄,5月上旬开始羽化成蛛,5月中旬开始产卵,卵期13.9d,若（幼）蛛期341.5d,成蛛期40.6d,雌雄比为3：1。成蛛日捕食松大蚜6.056头,是多种害虫的天敌。该蛛的发生与自然灾害、海拔高度、天敌等关系密切。封山育林,禁止使用化学农药是保护成若蛛、扩大繁殖的关键。     

Tupaia Belangeri as an Experimental Animal Model for Viral Infection

Tupaias, or tree shrews, are small mammals that are similar in appearance to squirrels. The morphological and behavioral characteristics of the group have been extensively characterized, and despite previously being classified as primates, recent studies have placed the group in its own family, the Tupaiidae. Genomic analysis has revealed that the genus Tupaia is closer to humans than it is to rodents. In addition, tupaias are susceptible to hepatitis B virus and hepatitis C virus. The only other experimental animal that has been demonstrated to be sensitive to both of these viruses is the chimpanzee, but restrictions on animal testing have meant that experiments using chimpanzees have become almost impossible. Consequently, the development of the tupaia for use as an animal infection model could become a powerful tool for hepatitis virus research and in preclinical studies on drug development.     

Exergy as an indicator: Observations of an aquatic ecosystem model

Exergy is considered as a goal function or ecological orientor. Normally at the edge of oscillation exergy reaches to its maximum value when the ecosystem had no adaptation on it. To study the variation of exergy in different states of ecosystem, a simple three species (phytoplankton, zooplankton and fish) food chain model has been considered. From the model it is shown that the system moves from steady state to chaotic state by decreasing zooplankton body volume in turn increasing its grazing rate. By the property of self-adaptability the system tries to overcome this situation. Two such possible processes are described here: (i) by the toxic effect of phytoplankton and (ii) by reducing half saturation constant of fishes. In both this cases exergy value reduces and the system reaches to stable state. Through the analysis of exergy variation in all these situations this paper shows that the system chose the process in which the reduction of exergy will be the minimum.     

Model Construction and Model Examination on the Basis of Simulated Selection

By reason nonlinear relations founded between selection differential and realised selection response we have been made investigations about variants of the genetic-statistical model, which include this nonlinearity. The variations of the model would not only referred to the postulate pattern of the connection between phenotype, genotype and environment but also enclosed the postulate assumption about the distribution of the variates. In an investigated special case the linear model equation P = G ± e was held, however the distributions of P and G were defined over a limited range in one direction. For P we have defined a modified normal distribution and the distribution of the random vector (G, e) non normal regarded with cov (G, e) ≠ 0, By means of a solution set of an integral equation a density function of the random vector (P, G) has been received, in which the expectation of the selection response of the usual genetic-statistical model approximate is included as a special case. The genetical parameters has been derived, which result from changed model. However their representation was only possible partially as an integral function. A subsequent paper informs of the examination this mode! variants, which depend on a parameter of the nonlinearity c.     

Biological evolution as an expression of body-plan potentialities.

A growing bulk of recent data from different fields as molecular biology, developmental biology, genetics, paleontology and phylogenetics shows that organisms play a more active role in their evolution than what postulated by the random variation-natural selection paradigm of the neo-Darwinian synthesis. Organisms show during development and morphogenesis autopoietic processes which are related to their body-plan potentialities. These potentialities are expressed through regulatory networks in which a plastic genome participates together with proteins and other substances in an epigenetic space. The epigenetic systems which arise from this interaction may be inherited and then assume a significant role in evolution becoming the source of new acquired characters. The acquisition of new traits through the epigenetic systems is influenced directly by environmental cues. If this process is coherent with the environmental demands it co-operates with natural selection in organism adaptation. An outstanding role in this context may be played by phenotypic plasticity if, as emerges in recent views, it may constitute a general basis for genetic assimilation processes.     

On the Calibration of an Autonomous Model of the Biological Population of the Tundra Lemming

Biophysics - An autonomous model of a phenomenological type was designed for a biological population of lemmings in complex studies of tundra communities. The population dynamics is described in...     

二白杨一些生物学和生态学特性的观察

二白杨(Populus gansuensis)是甘肃省河西地区广泛栽培的一种乔木,有人称它为河西地区造林中的“王牌树种”。二白杨的造林成活率很高,一般都在90%以上。生长非常迅速,年平均高生长1—1.8m,胸径生长为1.5—3.4cm,比钻天杨(Populus pyramidalis)与小叶杨(P．simonii)生长都快。它对环境条件的适应性比较强,在壤质、沙壤质、沙质、沙砾质等不同土壤质地中都能生长。比较耐干旱,耐干热风以及耐风沙流的袭击,也耐一定程度的土壤盐渍化。通过形态解剖和水分生理的试验研究看出,二白杨的旱生结构比较显著,如叶子的表面积与体积比值较小,角质层较厚,栅栏组织和输导组织都比较发达。它的水分生理也表现出对干旱环境有较强的适应能力,如束缚水以及束缚水与自由水的比值比较高,持水力比较强,蒸腾失水较少,水分亏缺也比较小。综上所述,我们认为二白杨是一个优良的造林树种,值得大力提倡用二白杨造林。     

3D Reconstruction of the Human Airway Mucosa In Vitro as an Experimental Model to Study NTHi Infections

We have established an in vitro 3D system which recapitulates the human tracheo-bronchial mucosa comprehensive of the pseudostratified epithelium and the underlying stromal tissue. In particular, we reported that the mature model, entirely constituted of primary cells of human origin, develops key markers proper of the native tissue such as the mucociliary differentiation of the epithelial sheet and the formation of the basement membrane. The infection of the pseudo-tissue with a strain of NonTypeable Haemophilus influenzae results in bacteria association and crossing of the mucus layer leading to an apparent targeting of the stromal space where they release large amounts of vesicles and form macro-structures. In summary, we propose our in vitro model as a reliable and potentially customizable system to study mid/long term host-pathogen processes.     

狗牙根营养繁殖体对模拟水淹的生物学响应

研究了水淹条件下狗牙根(Cynodon daetylon)繁殖体的形态特征和生物量的变化及其水淹后的恢复状况.结果表明,水淹深度的增加会诱导植株茎快速增高,而叶片数则明显下降.水淹时间对植株叶片数、茎直径、茎与根长比的影响显著,而对分枝数、茎长、根长、茎节数不显著.植株地上部生物量和总生物量随着水淹时间的延长而显著减少,但地下部生物量的变化不显著.所有实验处理的植株水淹后都能存活且恢复生长.但水淹对恢复期植株的生长仍有影响,植株的茎长、根长、分枝数、直径、叶片数、叶长、宽度以及叶的长宽比都随水淹时间的延长而显著减少,但茎节数与叶片数的差异不显著.根、茎、叶生物量和植株总生物量也随着水淹时间的延长而减少.实验表明狗牙根繁殖体通过延长茎长、改变叶形和减少生物量等方式对水淹显示出较强的耐受能力.     

Simulated acute hemorrhage through lower body negative pressure as an activator of the hypothalamic-pituitary-adrenal axis

While insulin induced hypoglycemia is the principle method of producing hypothalamic-pituitary-adrenal stress response, the mechanism by which this occurs may be different from that produced by other stressors. In a pilot study, we explored ways to standardize lower body negative pressure (LBNP), as a simulator of hemorrhage, to determine its utility for future studies of hypothalamic-pituitary-adrenal (HPA) axis function. Reduced atmospheric pressure of -40 mmHg applied at the level of the iliac crests during LBNP rapidly lowers blood pressure in most subjects, simulating acute hemorrhage. In 6 normal subjects, ACTH and cortisol values were measured before, during and after the application LBNP at 0800, 1600 and 2300 hours in the baseline state and at 1600 hours on the day following 1 mg of dexamethasone. Peak ACTH values of 60-250 pg/ml occurred 2 to 10 minutes after the cessation of the stimulus in subjects experiencing presyncope or having a systolic or diastolic blood pressure decrease of greater than 20 mmHg with a rise in pulse of 30 beats per minute or more. There was no significant difference between ACTH responses at different times of day. Peak cortisol values of 25-30 micrograms/dl occurred 15-20 minutes after cessation of the stimulus. In all subjects, administration of dexamethasone greatly attenuated the ACTH response and decreased but did not ablate the cortisol response. In conclusion, these data indicate that LBNP may be used to simulate hemorrhage as a stimulus of the HPA axis. HPA axis changes occur only when physiologic evidence of hypovolemic stress is present. Dexamethasone may be used to modulate the response to this stress paradigm.     

Biological uptake of influent organic matter as an electron donor for denitrification by activated sludge

To preserve organic materials in the sludge required for denitrification, a study was made with a contact process. The contactor, when operated with a short retention time (30 min), gave incomplete metabolism of organic matter. With 64% of the influent soluble COD (SCOD) was adsorbed to activated sludge within 30 min. The specific mass of organic matter uptaken was 55 mg SCOD/g Mixed Liquor Suspended Solids that enhanced the denitrification efficiency up to 63% in the following denitrification step.