Acquisition and reversal of taste/tactile discrimination after forebrain noradrenaline depletion

Two experiments were performed to assess the role of noradrenaline (NA) on the acquisition of an aversively motivated discrimination task and its reversal. A conditioned taste aversion procedure was used. The NA depletions were achieved through two different pharmacological means: systemic N-2-chloroethyl-N-ethyl-2-bromo-benzylamine (DSP4) and destruction of the dorsal noradrenergic bundle (DNAB) with 6-hydroxydopamine. Both procedures caused marked reductions of NA in the frontal cortex and hippocampus. In neither of the studies (Experiment 1, DSP4, and in Experiment 2, DNAB) were there any significant changes between controls and NA-depleted rats in either the rate of acquisition of the original discrimination (Phase 1) or the subsequent reversal (Phase 2). This occurred irrespective of which of the two stimuli (a taste cue, i.e., saccharin presented in bottles with nozzles that do not have ball bearings, "silent bottles," or a tongue-tactile cue, i.e., water in bottles with nozzles that had ball bearings "noisy bottles") initially was used as the conditioned stimulus (CS1, i.e., the stimulus first followed by contingent administration of lithium chloride, and later, in Phase 2, followed by saline injections). Thus NA does not appear to be critically involved in the acquisition and reversal of a taste/tactile discrimination task. The significance of forebrain NA for other discrimination tasks is discussed.     

Design and validation of a job-exposure matrix to silica

OBJECTIVE: To develop a population-based matrix of job-exposure to crystalline silica in Brazil and to estimate its validity. METHODS: An epidemiologist and an industrial hygienist developed a matrix of job-exposure in four stages: coding of occupation variable; coding of industry variable; consensual exposure classification between researchers; and estimate of registered workforce in 1995 for each level of exposure. The cross-tabulation of the variables industry (25 columns) and occupation (347 lines) resulted in 8,675 cells, classified according to silica exposure in four levels: non-exposed, possibly exposed, probably exposed, and definitively exposed. For validating the job-exposure matrix, five industries (mining and quarrying, construction, foundry, management of technical personal and textiles), were re-coded according to exposure by external experts. Reliability of the study and external experts was evaluated by agreement measured using kappa analysis. RESULTS: The job-exposure matrix showed high coding agreement, ranging from 64.0% for foundry to 94.0% for mining. Kappa analysis showed good agreement in mining (0.9), and low or average for other sectors (ranging from 0.1 to 0.5). High specificity was found in foundry (86.5%) and mining (100.0%). Construction had 56% specificity. CONCLUSIONS: The study job-exposure matrix showed good accuracy and seems to be appropriate for estimating silica exposure among Brazilian workers.     

The case for strategic international alliances to harness nutritional genomics for public and personal health

Nutrigenomics is the study of how constituents of the diet interact with genes, and their products, to alter phenotype and, conversely, how genes and their products metabolise these constituents into nutrients, antinutrients, and bioactive compounds. Results from molecular and genetic epidemiological studies indicate that dietary unbalance can alter gene-nutrient interactions in ways that increase the risk of developing chronic disease. The interplay of human genetic variation and environmental factors will make identifying causative genes and nutrients a formidable, but not intractable, challenge. We provide specific recommendations for how to best meet this challenge and discuss the need for new methodologies and the use of comprehensive analyses of nutrient-genotype interactions involving large and diverse populations. The objective of the present paper is to stimulate discourse and collaboration among nutrigenomic researchers and stakeholders, a process that will lead to an increase in global health and wellness by reducing health disparities in developed and developing countries.     

A patterned macular dystrophy with yellow plaques and atrophic changes.

Three middle-aged male patients are described with a peculiar patterned dystrophy of the macula. The basic lesions are discrete yellow plaques typically confined to the macular area and radiating from the fovea. They appear to be located at the level of the retinal pigment epithelium (RPE). With the passage of time some of the yellow plaques altered in extent and configuration, and atrophic changes appeared or extended. Visual acuity and electrophysiological tests are either normal or only moderately affected. The lesions appear to be distinct from the patterned dystrophies of the retina already described and from other conditions characterised by yellow or white deposits at the level of the RPE.