Spread of cobalt from a cortical epileptic lesion induced by a cobalt-gelatine implant into the frontal cortex of the rat

Summary The spread of cobalt ions from cobalt induced epileptic foci in rats has been investigated. Atomic absorption spectrophotometry and heavy-metal histochemistry reveal cobalt ions spread very widely from the focus. Biochemical and physiological consequences for this model of epilepsy are discussed.     

The CorA family: Structure and function revisited

The CorA family is a group of ion transporters that mediate transport of divalent metal ions across biological membranes. Metal ions are essential elements in most cellular processes and hence the concentrations of ions in cells and organelles must be kept at appropriate levels. Impairment of these systems is implied in a number of pathological conditions. CorA proteins are abundant among the prokaryotic organisms but homologues are present in both human and yeast. The activity of CorA proteins has generally been associated with the transport of magnesium ions but the members of the CorA family can also transport other ions such as cobalt and nickel. The structure of the CorA from Thermotoga maritima, which also was the first structure of a divalent cation transporter determined, has opened the possibilities for understanding the mechanisms behind the ion transport and also corrected a number of assumptions that have been made in the past.     

The influence of cobalt on the endoplasmatic reticulum of the horse bean (Vicia faba L.)

Summary The exogeneous application of cobalt induces the differentiation of membrane complexes of the endoplasmic reticulum. After longer acting of cobalt these membranes are dilated and later destroyed. This fact can manifest itself also in some disturbances of the cell division.     

The influence of cobalt on the endoplasmatic reticulum of the horse bean (vicia faba l.).

The exogeneous application of cobalt induces the differentiation of membrane complexes of the endoplasmic reticulum. After longer acting of cobalt these membranes are dilated and later destroyed. This fact can manifest itself also in some disturbances of the cell division.     

Demonstration of cobalt in histological sections using ion microanalysis by high mass resolution : application to the study of experimental chronic epilepsy in the rat]

Cobalt is specifically detected in ion microanalysis by high mass resolution. This method allows detection of the remaining cobalt in histological sections of Rat's cortex, after treatment by topic application of cobalt powder and demonstrates a diffusion of the metal into the epileptic area.     

A novel effect of cobalt treatment on calcium-dependent responses of the cockroach salivary gland

Summary After incubation in calcium-free solutions containing cobalt, the readmission of calcium caused prolonged but reversible hyperpolarization of acinar cells of cockroach salivary glands and prolonged fluid secretion. It is suggested that cobalt treatment increases the permeability of the acinar cell membrane to calcium.Acknowledgments. We are indebted to the Medical Research Council for support.     

Biosynthesis of cobalamin (vitamin B12): a bacterial conundrum

The biosynthesis of cobalamin (vitamin B12) is described, revealing how the concerted action of around 30 enzyme-mediated steps results in the synthesis of one of Nature's most structurally complex 'small molecules'. The plethora of genome sequences has meant that bacteria capable of cobalamin synthesis can be easily identified and their biosynthetic genes compared. Whereas only a few years ago cobalamin synthesis was thought to occur by one of two routes, there are apparently a number of variations on these two pathways, where the major differences seem to be concerned with the process of ring contraction. A comparison of what is currently known about these pathways is presented. Finally, the process of cobalt chelation is discussed and the structure/function of the cobalt chelatase associated with the oxygen-independent pathway (CbiK) is described.     

钴及其化合物一维纳米材料的制备研究进展

本文介绍了钴及其化合物一维纳米材料,如纳米线、纳米棒和纳米管的制备方法及其最新研究进展,包括热分解法、模板法、分子自组装、固相合成法和化学溶液法等。并预测了未来的可能的发展方向。     

Forecasting outcomes in spread betting markets: can bettors use ‘quarbs’ to beat the book?

In this paper, we examine a relatively novel form of gambling, spread (or index) betting that overlaps with practices in conventional financial markets. In this form of betting, a number of bookmakers quote bid–offer spreads about the result of some future event. Bettors may buy (sell) at the top (bottom) end of a spread. We hypothesize that the existence of an outlying spread may provide uninformed traders with forecasting information that can be used to develop improved trading strategies. Using data from a popular spread betting market in the United Kingdom, we find that the price obtaining at the market mid‐point does indeed provide a better forecast of asset values than that implied in the outlying spread. We further show that this information can be used to develop trading strategies leading to returns that are consistently positive and superior to those from noise trading. Copyright © 2005 John Wiley & Sons, Ltd.     

Information processing along the course of a visual interneuron

Summary Locust ocellar retinal cells are innervated by giant second order cells, 2 mm long, which show discrete zones of integration along their course, including a major zone in the axonal length of the neuron. The complex synaptic arrangements which exist between higher-order afferent and efferent cells and these second order cells along their course suggests that transmission takes place by the electrotonic spread of slow potentials. The size and accessibility of these visual interneurons offers a unique preparation for examining mechanisms of graded synaptic transmission.     

Asymmetry in the link between the yield spread and industrial production: threshold effects and forecasting

We analyse the nonlinear behaviour of the information content in the spread for future real economic activity. The spread linearly predicts one‐year‐ahead real growth in nine industrial production sectors of the USA and four of the UK over the last 40 years. However, recent investigations on the spread–real activity relation have questioned both its linear nature and its time‐invariant framework. Our in‐sample empirical evidence suggests that the spread–real activity relationship exhibits asymmetries that allow for different predictive power of the spread when past spread values were above or below some threshold value. We then measure the out‐of‐sample forecast performance of the nonlinear model using predictive accuracy tests. The results show that significant improvement in forecasting accuracy, at least for one‐step‐ahead forecasts, can be obtained over the linear model. Copyright © 2004 John Wiley & Sons, Ltd.     

Conditional volatility forecasting in a dynamic hedging model

This paper addresses several questions surrounding volatility forecasting and its use in the estimation of optimal hedging ratios. Specifically: Are there economic gains by nesting time‐series econometric models (GARCH) and dynamic programming models (therefore forecasting volatility several periods out) in the estimation of hedging ratios whilst accounting for volatility in the futures bid–ask spread? Are the forecasted hedging ratios (and wealth generated) from the nested bid–ask model statistically and economically different than standard approaches? Are there times when a trader following a basic model that does not forecast outperforms a trader using the nested bid–ask model? On all counts the results are encouraging—a trader that accounts for the bid–ask spread and forecasts volatility several periods in the nested model will incur lower transactions costs and gain significantly when the market suddenly and abruptly turns. Copyright © 2005 John Wiley & Sons, Ltd.     

Information processing along the course of a visual interneuron.

Locust ocellar retinal cells are innervated by giant second order cells, 2 mm long, which show discrete zones of integration along their course, including a major zone in the axonal length of the neuron. The complex synaptic arrangements which exist between higher-order afferent and efferent cells and these second order cells along their course suggests that transmission takes place by the electrotonic spread of slow potentials. The size and accessibility of these visual interneurons offers a unique preparation for examining mechanisms of graded synaptic transmission.     

Activation and specificity of alkaline phosphatase of a mineralizing collagen-rich system

Alkaline phosphatase from tibia tendon of Meleagris gallopavo L. was highly purified. The enzyme activation by different ions was measured. Mg2+ showed a high activation with a broader spectrum of phosphomonoester hydrolization. The in vivo Mg2+ concentration was an optimum for in vitro activation.     

The effects of triaminopyrimidine on the short circuit current and transmembrane potentials of the isolated rat visceral yolk sac in vitro

Summary Intracellular potentials in the cells from 17.5-day old rat visceral yolk sacs were measured by a glass microelectrode. When penetrated from the maternal side, the cells have potentials of about 50.2±1.9 mV (inside negative) which were reduced by increasing the external K⁺ concentration and increased by removing Na⁺ ions from the bathing fluid. Triaminopyrimidine (TAP) which inhibited Na⁺ transport caused a dose-dependent depolarization of the cell membrane. The depolarization was dependent on the presence of extracellular Ca²⁺ ions. It is proposed that TAP may inhibit Na⁺ transport by increasing the intracellular concentration of calcium ions.This work was supported by the University of Hong Kong (grant number 335. 034.5105).Acknowledgment. Triaminopyrimidine was synthesized by Dr. Barbara Roth of the Wellcome Research Laboratories.     

Decomposition of toxic and environmentally hazardous 2,3,7,8-tetra-chlorodibenzo-p-dioxin by gamma irradiation

The decomposition of the toxic and environmentally hazardous 2378-TCDD by gamma irradiation was studied and successfully used to decontaminate laboratory wastes containing small quantities of this chemically and biologically stable compound. The method makes use of gamma irradiation from a commercial 60cobalt facility at high dose levels (1000 kGy) to break down the compound into nontoxic products. Irradiation also decomposed 2378-TCDD in contaminated soil from the Seveso accident.     

Decompoisition of toxic and environmentally hazardous 2,3,7,8-tetra-chlorodibenzo-p-dioxin by gamma irradiation

Summary The decomposition of the toxic and environmentally hazardous 2378-TCDD by gamma irradiation was studied and successfully used to decontaminatge laboratory wastes containing small quantities of this chemically and biological stable compound. The method makes use of gamma irradiation from a commercial⁶⁰cobalt facility at high dose levels (100 kGy) to break down the compound into notoxic products. Irradiation also decomposed 2378-TCDD in contaminated soil from the Seveso accident.     

Responses of skeletal muscle fibres to lanthanide ions. Dependence of the twitch response on ionic radii

Summary A study of the effects of the lanthanide series of ions on toad skeletal muscle fibres reveals that they a) inhibit the twitch response, b) exhibit a marked dependence on ionic radius, and c) apparently exert their effects on the sarcolemma.This research was supported by grants from the National Heart Foundation of Australia and from the National Health and Medical Research Council. The authors would like to thank Dr Keith Ellis for his suggestion of the standardization procedure for the lanthanide ions.     

Presence of lectin-like substances in the basement membrane of the human kidney glomerulus]

Crude extracts from the human glomerular basement membranes solubilized by pepsin or bacterial collagenase agglutinate normal or transformed human cells. Cytoagglutination is inhibited by N-acetyl-osamines. These properties are reminiscent of lectins. When agglutinated cells are incubated for an additional 20 hrs. period in minimal serum free medium but in presence of these basement membrane extracts, they attach to the glass and spread out.     

Evaluation of oral vaccination against mouse-typhoid in a new animal model

Summary In a simple, new animal model the spread of mouse-typhoid within a mouse-colony was studied and oral vaccination against this disease was evaluated. Live vaccine was superior to inactivated vaccine.