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Effects of fetal genotype and uterine environment on placental development in equids 总被引:1,自引:0,他引:1
Measurement of the concentrations of equine chorionic gonadotrophin (eCG) in the serum of pregnant mares and Jenny donkeys carrying normal intraspecies and hybrid interspecies pregnancies suggested that the production of this hormone may be influenced by parental gene imprinting. Specifically, a differential expression of maternal and paternal genes may control the size and secretory activity of the structures that secrete eCG, the fetal endometrial cups. However, bisection of an interspecies mule embryo followed by transfer of the resulting demi-embryos and other intact mule embryos to horse and donkey recipients resulted in striking differences in the size, secretory activity and lifespan of the endometrial cups in two types of surrogate mother. This finding has therefore demonstrated the ability of uterine factors to alter profoundly the development and characteristic phenotype of the specialized invasive chorionic girdle portion of the equine trophoblast that gives rise to the endometrial cups. 相似文献
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A case of hypertrophic osteopathy is described in a mare with a vague history of abdominal discomfort over the preceding 12 months. Bony swellings were obvious in the pastern area of both forelegs. There was a dysgerminoma of the left ovary that had metastasised to several abdominal lymph nodes and had infiltrated the posterior vena cava. There was no gross thoracic involvement although there was histologic evidence of tumour metastasis in pulmonary arterioles. 相似文献
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Patricia Shipley 《AI & Society》1995,9(1):57-79
Health and safety at work is a moral imperative, but the debates emphasise only the economic and legal sides. Drawing on case material from working with VDUs and other forms of modern technology it is shown that loss of control over their immediate work processes can be stressful and potentially harmful to responsible operators. Autonomy and freedom in work process control enhances the power that workers have to protect their health. It is suggested that unquestioned divisive and dualistic practices at workplaces are a potent and unnecessary reason for this problem.A human being can only survive in the Age of Machinery if the ethical norms of life are held sacred. This Shamanist protest at the destructive power of evil, as expressed in theCurse Upon Iron, stands forth prominently in a society in moral crisis. 相似文献
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TE Williams CK Meshul NJ Cherry NM Tiffany FP Eckenstein WR Woodward 《Canadian Metallurgical Quarterly》1996,370(2):147-158
Basic fibroblast growth factor (bFGF), a member of the heparin-binding growth factor family, is present in relatively high levels in the brain where it may play an important role in the maintenance, repair, and reorganization of the tissue. Although bFGF is associated mainly with astrocytes throughout most of the central nervous system (CNS), a narrow but prominent band of pyramidal neurons, which coincides with the CA2 subregion of Ammon's horn in the hippocampus, stains intensely for bFGF. In order to gain an understanding of which cells express bFGF and whether or not BFGF is a good marker for CA2 neurons, we have used a mouse monoclonal antibody directed against recombinant human bFGF to characterize the distribution and localization of bFGF expression in the hippocampus. We find that about one-quarter of the neurons in CA2 are bFGF positive, and they appear smaller and have more irregular-shaped nuclei than their unstained counterparts. In addition, all glial fibrilary acidic protein (GFAP)-positive astrocytes in the hippocampus stain for bFGF, and the distribution of these astrocytes is heterogeneous in the hippocampus. Finally, in both astrocytes and CA2 pyramidal neurons, bFGF immunoreactivity is localized primarily in the nucleus and to a lesser extent in the cytoplasm and processes of stained cells. 相似文献
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JM Ensink WR Klein A Barneveld AS van Miert AG Vulto 《Canadian Metallurgical Quarterly》1996,138(11):253-256
To evaluate the side effects of oral pivampicillin and trimethoprim/ sulphadiazine, 200 horses receiving these antimicrobial agents were studied. The horses received either trimethoprim/ sulphadiazine (30 mg/kg twice daily) or pivampicillin (25 mg/kg twice daily) for three or more days. No adverse effects other than loose faeces and diarrhoea were detected. The risk of diarrhoea was significantly less after the oral administration of pivampicillin (3 per cent) than after trimethoprim/ sulphadiazine (7 per cent). Horses whose appetite was reduced appeared to be predisposed to develop diarrhoea after the administration of either oral antimicrobial agent. 相似文献