Clinical and molecular characterization of a re-established line of sheep exhibiting hemophilia A.

Background: Large animal models that accurately mimic human hemophilia A (HA) are in great demand for developing and testing novel therapies to treat HA.

Objectives: To re-establish a line of sheep exhibiting a spontaneous bleeding disorder closely mimicking severe human HA, fully characterize their clinical presentation, and define the molecular basis for disease.

Patients/methods: Sequential reproductive manipulations were performed with cryopreserved semen from a deceased affected ram.

Male germ-line cells are at risk following direct-injection retroviral-mediated gene transfer in utero.

The recent observation of vector sequences in the semen of men undergoing clinical gene therapy for hemophilia has highlighted the need to evaluate the risk of inadvertent germ-line transduction in a clinically relevant animal model. In the present study, we used three different approaches to investigate whether the germ line is at risk of inadvertent alteration following in utero retroviral gene transfer in the clinically relevant, random-bred sheep model. First, we conducted breeding studies.

Gestational age of recipient determines pattern and level of transgene expression following in utero retroviral gene transfer.

The direct vector injection approach was used in the fetal sheep model of in utero gene therapy to determine the effects of the recipient gestational age on the efficacy and pattern of liver, lung, and brain transduction and transgene expression. The livers contained foci of transgene-expressing hepatocytes and demonstrated an inverse correlation between recipient age and hepatocyte transduction/transgene expression, with higher levels of gene transfer/expression early in gestation and lower levels late in gestation. Conversely, the percentage of transgene-expressing cells within the lungs of these same animals increased with gestational age, with the majority of transduction occurring in epithelium and fibroblasts.

Verotoxin-producing Escherichia coli in sheep grazing an irrigated pasture or arid rangeland forages.

Worldwide, verotoxin-producing Escherichia coli (VTEC) have been recognized as the cause of many sporadic cases or major outbreaks of human illnesses involving consumption of contaminated meat, especially beef. Although sheep products have not been linked to reported human illnesses, their role as a food safety risk factor should not be ignored. The objective of this study was to assess VTEC prevalence in two groups of ewes (20 each) grazing an irrigated pasture or arid range in a western United States environment (Nevada) over 1 year (summer of 1999 to summer of 2000).

Carbohydrate fermentation and nitrogen metabolism of a finishing beef diet by ruminal microbes in continuous cultures as affected by ethoxyquin and(or) supplementation of monensin and tylosin.

Long-term feedlot studies have shown positive effects (i.e., improved ADG and reduced morbidity and mortality) of dietary supplementation with ethoxyquin (AGRADO).