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Since these sheets are available for most countries, they provide a set of data that are comparable across countries and regions of the world WHO, b. Diarrhoea was reproduced in 1-day-old cockerels fed contaminated grain from the affected households. The consumption of pickled vegetables heavily infested with various Aspergillus and Fusarium spp. However, in rabbits, maternal toxicity was observed at a daily dose given by gavage in water as low as 0.
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Fumonisin B 1 is the diester of propane-1,2,3-tricarboxylic acid and 2 S -amino S ,16 R -dimethyl-3 S ,5 R ,10 R ,14 S ,15 R -pentahy-droxyeicosane in which the C and C hydroxy groups are esterified with the terminal carboxy group of propane-1,2,3-tricarboxylic acid Bezuidenhout et al. Fumonisin B 2 is the C deoxy analogue of fumonisin B 1 in which the corresponding stereogenic centres on the eicosane backbone have the same configuration Bezuidenhout et al. Ceramide synthase recognizes both the amino group sphingoid-binding domain and the tricarboxylic acid side-chains fatty acyl-coenzyme A domain of fumonisin B 1.
Coenin epidemiological survey in India indicated that consumption of unleavened bread prepared from mouldy sorghum or maize resulted in a gastrointestinal disease characterized by abdominal pain, borborymi, and diarrhoea.
Akt is part of the anti-apoptotic phosphatidylinositol 3 kinase cell survival pathway Dudek et al. In short-term studies with mice, rats, and rabbits, disruption of sphingolipid metabolism, as shown by statistically significant increases in the free sphinganine concentration, occurred at doses at or below those that cause liver or kidney lesions Table 1; for review, see Riley et al. The diet that caused the most pronounced liver lesions consisted of maize, beans, a salt mixture, and imifino.
Evidence in vitro and in vivo indicates that fumonisin B 1 can damage DNA indirectly by increasing oxidative stress Atroshi et al. Hence, analytical methods and surveys have been developed mainly for these two toxins.
Additionally, it was assumed that the existence of a limit would have no effect on the distribution of fumonisins in maize below that limit, i. In rat liver, fumonisin B 1 induced changes in phospholipids and their fatty acid composition that markedly affected the many cell functions that may contribute to its toxicity and carcinogenicity. In a survey of the production of fumonisins B 1 and B 2 by 40 toxic Fusarium isolates, the toxins were produced only by F.
Fumonisin B 1 inhibits the biosynthesis of the glycosylphosphatidylinositol-anchored folate transporter in vitro, and folate deficiency is associated with an increased risk for neural tube defects.
From 18 months onwards, some hepatocyte nodules showed dysplasia and nuclear atypia characteristic of preneoplastic changes, a few of which were transformed into hepatocellular carcinoma. Altered prostaglandin and arachidonic acid-induced cytotoxicity. In this scenario, the per-capita consumption of all grains was combined with the distribution of fumonisin intakes.
Females were more sensitive than males to these effects. A variety of preneoplastic and neoplastic hepatic lesions were observed in the samples collected. Although the antibodies used in ELISAs are raised against fumonisin B 1they generally have significant but lower cross-reactivity with fumonisins B 2 and B 3.
The lesser toxicity of hydrolysed fumonisin B 1 in rat liver is not due to reduced absorption. Steeping maize in water, which is a step in wet milling, was also effective in reducing the concentrations of fumonisins B 1 and B 2 in maize, but sulfur dioxide delayed toxin extraction from the contaminated grain Canela et al. Briefly, 10 batches with a wide range of fumonisin concentrations were selected. Changes in the balance of the various cell regulatory molecules, such as those found in the livers of rats fed diets containing fumonisin B 1are likely to be involved in induction of a growth differential in which the growth of initiated cells is selectively stimulated and cancer develops.
Only those individuals in areas where maize is regularly and heavily contaminated would fall into the high end of the distribution of intake of fumonisins in this scenario.
Nevertheless, disruption of lipid metabolism, membrane structure, and signal transduction pathways mediated by lipid second messengers appear to be important in all the proposed mechanisms of action. In rainbow trout, fumonisin B 1 was not a complete carcinogen, but there was a close correlation between promotion of hepatocarcinogenicity caused by aflatoxin B 1 and the concentration of free sphinganine in liver Carlson et al.
Consumption of alcohol does not explain the geographical and ethnic variations, as dietary patterns and tribal customs in Kenya vary considerably Gatei et al. In contrast to the study of Van Rensburg et al. Nassmixture of opium, lime, and ash, risk factor in men.
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The toxicological profiles of these toxins are very similar to that of fumonisin B 1. In rodents, the toxicity of fumonisin B 1 depends on the strain and sex. The concentrations of fumonisins in maize-based foods were high in both the Transkei and Hebei Province Sydenham et al. A frequency distribution of the concentrations of fumonisins in maize was derived from available data in and published as part of an assessment of human intake of fumonisins in the Netherlands de Nijs et al.
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Models or processes not summarized previously WHO, a are shown in bold. Hepatotoxicity is usually observed at doses lower than those that induce the pulmonary oedema. Second, alterations in the N-6 fatty acid desaturase pathway and the subsequent decrease in long-chain polyunsaturated fatty acids would result in a more rigid membrane structure.
However, de Nijs found no margin of safety for a sensitive sub-population, patients with coeliac disease, and the approach could not be used to derive an estimate of the probability of harm. A complete review of the literature on this subject is beyond the scope of this monograph, cvenin the interested reader is referred to WHO a and reviews by Merrill et al.
Selected biochemical mechanisms for the toxicity of fumonisin B 1 in animal models in which the proposed biochemical action has been shown to be related to specific effects.