Identifying the neural circuitry of alcohol craving and relapse vulnerability

With no further intervention, relapse rates in detoxified alcoholics are high and usually exceed 80% of all detoxified patients. It has been suggested that stress and exposure to priming doses of alcohol and to alcohol-associated stimuli (cues) contribute to the relapse risk after detoxification. This article focuses on neuronal correlates of cue responses in detoxified alcoholics. Current brain imaging studies indicate that dysfunction of dopaminergic, glutamatergic and opioidergic neurotransmission in the brain reward system (ventral striatum including the nucleus accumbens) can be associated with alcohol craving and functional brain activation in neuronal systems that process attentional relevant stimuli, reward expectancy and experience. Increased functional brain activation elicited by such alcohol-associated cues predicted an increased relapse risk, whereas high brain activity elicited by affectively positive stimuli may represent a protective factor and was correlated with a decreased prospective relapse risk. These findings are discussed with respect to psychotherapeutic and pharmacological treatment options.     

Geographical variation in temporal and spatial vocalization patterns of male harbour seals in the mating season

In the aquatically mating harbour seal, Phoca vitulina, oestrous females show marked differences in spatial and temporal distribution between geographical areas. This suggests that the males' display behaviour may also vary between areas. We recorded male vocalizations in two areas, the Moray Firth and Orkney, U.K. In the Moray Firth, females haul out on a few intertidal sandbars and travel along predictable routes to forage at sea. In Orkney, female haul out sites are much less influenced by tidal availability and females are much more dispersed. In the Moray Firth, males vocalized only during a short mating season, from 1 July to 12 August. Vocalizations varied significantly with the tide, the peak at high tide clearly coinciding with the period when most females were in the water. In contrast, vocalizations in Orkney were significantly related to both tidal and diel patterns. We suggest that the timing of male vocalizations reflects differences in female availability between sites. In the inner Moray Firth, vocalizations were heard throughout the females' range, whereas vocalizations in Orkney were heard only in two discrete areas. However, at both sites the density of vocalizing males was highest in narrow channels and/or along predictable female travel routes. Therefore, males clearly adapt their temporal and spatial behaviour patterns to variations in female distribution and density. These results suggest that male mating strategies in aquatically mating pinnipeds are more variable than was previously envisaged. Copyright 1999 The Association for the Study of Animal Behaviour.     

Directed formation of chromosomal deletions in Salmonella typhimurium : targeting of specific genes induced during infection

In vivo expression technology (IVET) has resulted in the isolation of more than 100 Salmonella typhimurium genes that are induced during infection. Many of these in vivo induced (ivi) genes, as well as other virulence genes, are clustered in regions of the chromosome that are specific for Salmonella and are not present in Escherichia coli (e.g., pathogenicity islands). It would be desirable to be able to delete such putative virulence regions of the chromosome, and if the deletion removes genes that play a role in pathogenesis subsequent efforts can then be focused on individual genes that reside within that region. We therefore have developed a strategy for constructing chromosomal deletions which are not limited in size, have defined endpoints with a selectable marker at the joint point, and are not dependent on prior knowledge of sequences contained within the deleted region. Such deletion strategies can be applied to almost any bacterium with homologous recombination and to plasmid-based mutational systems where homologous recombination is not desired or feasible. Received: 6 October 1997 / Accepted: 30 December 1997     

Infection of a goat with a tick-transmitted Ehrlichia from Georgia, U.S.A., that is closely related to Ehrlichia ruminantium.

We detected a novel tick-transmitted Ehrlichia in a goat following exposure to lone star ticks (Amblyomma americanum) from a park in the metropolitan area of Atlanta, GA, U.S.A. Nineteen days after infestation with field-collected adult ticks, the goat developed a fever of two days duration, which coincided with mild clinical pathologic changes and the presence of DNA from a novel Ehrlichia in peripheral blood. The goat transmitted ehrlichiae to uninfected nymphal A. americanum that fed upon the goat, and the ticks maintained the pathogen transstadially. Five months after exposure, immunosuppression of the goat resulted in transient ehrlichemia with transmission of ehrlichiae to feeding ticks. Sequencing and phylogenetic reconstructions of the 16S rRNA, gltA, map1, map2, and ribonuclease III genes suggest the agent might be a divergent strain of Ehrlichia ruminantium, the agent of heartwater, or a new, closely related species. Convalescent serum from the goat reacted with the MAP-1 protein of E. ruminantium and with whole-cell Ehrlichia chaffeensis antigen. DNA from the novel Ehrlichia was detected in 5/302 field-collected adult A. americanum from the park. Our data suggest that A. americanum is a natural vector and reservoir of this Ehrlichia and that domestic goats can be reservoirs. The geographic range of the agent and its pathogenicity to humans and livestock needs to be evaluated.     

Studies on rat brain acyl-coenzyme A hydrolase (short chain).

A mitochondrial short chain acyl-CoA hydrolase, purified 1375-fold from rat brain, has a molecular weight of approximately 1.55 × 10⁵, a pH optimum of 8.1, an ionic strength optimum for activity and stability of 100–300 mM, is product activated by acetate and inhibited by DL-lipoic acid (K_i ? 5 μM) and 0.1 M orthophosphate (>50%). Acetyl, propionyl, butyryl, succinyl, acetoacetyl, malonyl and octanoyl-CoA are substrates. The highest maximum velocity and product activation was observed with acetyl-CoA as substrate.     

The epidemiology of heartwater: Establishment and maintenance of endemic stability

Although heartwater (Cowdria ruminantium infection) is one of the most economically important tick-borne diseases of sub-Saharan Africa, its epidemiology he's remained poorly understood until recently. New data, suggesting that heartwater is present in an endemically stable state in much of sub-Saharan Africa and demonstrating vertical transmission of Cowdria ruminantium in the field, have altered previously accepted views on heartwater epidemiology. In this paper, Sharon Deem and colleagues present an overview of the epidemiology of heartwater based on recent studies, discuss the factors that make endemic stability possible, make recommendations for future directions in research, and provide a foundation for the development of epidemiological models.     

Stress tolerance in transgenic tobacco seedlings that overexpress glutathione S-transferase/glutathione peroxidase

Overexpression of a tobacco glutathione S-transferase with glutathione peroxidase activity (GST/GPX) in transgenic tobacco (Nicotiana tabacum L.) enhanced seedling growth under a variety of stressful conditions. In addition to increased GST and GPX activity, transgenic GST/GPX-expressing (GST+) seedlings had elevated levels of monodehydroascorbate reductase activity. GST+ seedlings also contained higher levels of glutathione and ascorbate than wild-type seedlings and the glutathione pools were more oxidized. Thermal or salt-stress treatments that inhibited the growth of wild-type seedlings also caused increased levels of lipid peroxidation. These treatments had less effect on the growth of GST+ seedling growth and did not lead to increased lipid peroxidation. Stress-induced damage resulted in reduced metabolic activity in wild-type seedlings while GST+ seedlings maintained metabolic activity levels comparable to seedlings grown under control conditions. These results indicate that overexpression of GST/GPX in transgenic tobacco seedlings provides increased glutathione-dependent peroxide scavenging and alterations in glutathione and ascorbate metabolism that lead to reduced oxidative damage. We conclude that this protective effect is primarily responsible for the ability of GST+ seedlings to maintain growth under stressful conditions.     

A limited survey of aflatoxins and fumonisins in retail maizebased products in the UK using immunoassay detection

A total of 27 maize-based products destined for human consumption were collected from retail outlets within the city of Glasgow in the UK and were analysed for the presence of aflatoxins using immunoaftinity column chromatography with fluorescence detection and for fumonisins by competitive ELISA. Aflatoxins were detected at a trace level below 4 in eight (30%) of the 27 samples tested, no sample contained aflatoxins at a high level although one sample of sweetcorn did contain aflatoxins at a level of 5-10 Fumonisins were detected in eight (30%) of the samples at levels from 1 to 8mgkg^-1 and a further eight samples contained fumonisin at a level below 1 mgkg^-1 but above the detectable level. The highest concentration of fumonisins was found in a sample of fine corn meal at 8-12mgkg^-1.