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Query: UMLS:C0851341 (infestation)
 10,121 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We examined the response of selected animal performance, endocrine, immune, and metabolic factors from 13 steers (254+/-6.1 kg) with and without a lone star (Amblyomma americanum) tick burden during progressive days of the tick feeding cycle. Steers were randomly assigned to either non-treated controls or treated with 300 adult pair of A. americanum per animal. Animals were weighed and blood sampled on days -7, 0, 10, 14, 21, 28, and 35 relative to tick treatment. Tick treatment did not affect (P<0.1) animal performance. Experimental day did (P<0.05) affect body weight gain and dry matter intake. Tick treatment did not affect (P<0.1) metabolic indicators. Experimental day affected (P<0.05) IGF1 and lactate, tended to affect cortisol (P<0.07), but did not affect (P<0.1) glucose concentrations. Tick treatment did not significantly (P<0.1) affect growth hormone receptor (GHR) mRNA in liver, but liver tissue from treated animals had numerically lower GHR mRNA than did tissue from control animals. Day had a significant (P<0.05) effect on liver GHR mRNA. There was a significant treatment by day interaction (P<0.05) for liver IGF1 gene expression, as IGF1 mRNA was reduced in tick-treated cattle versus control cattle on day 35. Overall, liver IGF1 gene expression was lower (P<0.05) in tick than in control animals while there was no effect (P>0.1) due to day. Within the tick-treated group, correlations were found between quantitative female tick feeding characteristics and host metabolic indicators. Feeding by adult female lone star ticks did cause acute stress in growing beef steers on a moderate plane of nutrition as indicated by some physiologic indicators. In particular there may be longer term effects on the somatotrophic axis in the liver which could affect subsequent (i.e. feedlot) performance. It is not known how these observed effects would be manifest under a lower plane of nutrition, as is common and may become more so within the current native range of A. americanum. Other acute effects due to tick feeding may have been masked by the effects of handling and invasive sampling. Non-invasive experimental procedures are called for in order to study the effects of a stressor such as arthropod infestation on grazing animals. Future research efforts will be aimed at non-invasively elucidating the effects of tick stress on grazing animals under various nutritional environments.
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PMID:Effects of a lone star tick (Amblyomma americanum) burden on performance and metabolic indicators in growing beef steers. 2060 19

The trichothecene mycotoxin deoxynivalenol (DON) is produced in wheat, barley and corn following infestation by the fungus Fusarium in the field and during storage. Colloquially known as "vomitoxin" because of its emetic effects in pigs, DON has been associated with human gastroenteritis. Since DON is commonly detected in cereal foods, there are significant questions regarding the risks of acute poisoning and chronic effects posed to persons ingesting this trichothecene. A further challenge is how to best manage perceived risks without rendering critical food staples unavailable to an ever-expanding world population. In experimental animal models, acute DON poisoning causes emesis, whereas chronic low-dose exposure elicits anorexia, growth retardation, immunotoxicity as well as impaired reproduction and development resulting from maternal toxicity. Pathophysiologic effects associated with DON include altered neuroendocrine signaling, proinflammatory gene induction, disruption of the growth hormone axis, and altered gut integrity. At the cellular level, DON induces ribotoxic stress thereby disrupting macromolecule synthesis, cell signaling, differentiation, proliferation, and death. There is a need to better understand the mechanistic linkages between these early dose-dependent molecular effects and relevant pathological sequelae. Epidemiological studies are needed to determine if relationships exist between consumption of high DON levels and incidence of both gastroenteritis and potential chronic diseases. From the perspective of human health translation, a particularly exciting development is the availability of biomarkers of exposure (e.g. DON glucuronide) and effect (e.g. IGF1) now make it possible to study the relationship between DON consumption and growth retardation in susceptible human populations such as children and vegetarians. Ultimately, a fusion of basic and translational research is needed to validate or refine existing risk assessments and regulatory standards for this common mycotoxin.
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PMID:Deoxynivalenol: mechanisms of action, human exposure, and toxicological relevance. 2079 30