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41.
The homeobox gene Otx2 is a mouse cognate of the Drosophila orthodenticle gene, which is required for development of the brain, rostral to rhombomere three. We have investigated the mechanisms involved in this neural function and specifically the requirement for Otx2 in the visceral endoderm and the neuroectoderm using chimeric analysis in mice and explant recombination assay. Analyses of chimeric embryos composed of more than 90% of Otx2-/- ES cells identified an essential function for Otx2 in the visceral endoderm for induction of the forebrain and midbrain. The chimeric studies also demonstrated that an anterior neural plate can form without expressing Otx2. However, in the absence of Otx2, expression of important regulatory genes, such as Hesx1/Rpx, Six3, Pax2, Wnt1 and En, fail to be initiated or maintained in the neural plate. Using explant-recombination assay, we could further demonstrate that Otx2 is required in the neuroectodem for expression of En. Altogether, these results demonstrate that Otx2 is first required in the visceral endoderm for the induction, and subsequently in the neuroectoderm for the specification of forebrain and midbrain territories.  相似文献   
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Aiming at finding out the ergonomics conditions of the nursing personnel in a hospital admission unit, the authors utilized as a methodological presupposition the search for a global experienced work situation through the analysis of some elements as: the man (nursing worker); the work activity (prescribed duty, real activities and work position) and the environment (temperature, noise and illumination). The authors selected the Cardiology admission unit for the site of their research. The results verified that the nursing workers the mentioned unit face problems related to salaries, work installations, relationship, work organization, levels of formation and the activities executed. The authors suggested some recommendations.  相似文献   
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The three members of the morbillivirus genus that infect wildlife in ecosystems where domestic animals occur are rinderpest, peste des petits ruminants (PPR) and canine distemper. Data on the relative susceptibility of species of the Order Artiodactyla for rinderpest have been obtained from historical records of outbreaks. Rinderpest in wildlife has only occurred in equatorial and eastern Africa since the great pandemic of 1889-1897. The distributions, densities and population dynamics of susceptible species in this region are described. There has only been one recorded outbreak of PPR in wildlife but the possibility of its occurrence in the future now that it is present in many parts of west and eastern Africa is discussed. Wild carnivora are not likely to be important maintenance hosts for canine distemper but the disease is of significance in free-ranging carnivores and particularly in small populations of endangered susceptible wildlife species. It is also of great significance in zoo populations.  相似文献   
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Toxoplasma gondii infection, like malaria, is sensitive to inhibition by artemisinin (ART). Mechanisms of action for ART in malaria treatment have been proposed, but little is known about its effects in T. gondii infection. To better understand its inhibitory effects on T. gondii, mutants resistant to ART were selected by progressive culture in permissive levels of the drug. Five clonal isolates were established and characterized. The isolates were approximately 65-fold less sensitive to ART than is the parental RH and showed cross-resistance to the ART derivatives dihydroartemisinin and artemether. In addition to ART resistance, 1 clone (C9) formed morphologically unusual parasitophorous vacuoles and another (A2) was avirulent for mice and protected mice from challenge with the wild type. These clonal T. gondii mutant isolates will be useful for the study of not only the mechanism of action of ART but also parasite vacuole biology and virulence factors.  相似文献   
45.
Videolaparoscopic cholecystectomy is considered the treatment of choice for simple cholelithiasis. Now many surgeons consider the laparscopic procedure usable also in the complicated biliary lithiasis like acute cholecystitis and choledocholithiasis. The authors report their recent experience of the laparoscopic treatment of biliary lithiasis, regarding 221 non-selected patients (69% symptomatic cholelithiasis, 20% chronic cholecystitis, 4.5% acute cholecystitis, 4.5% coledocolithiasis, 2% hydrops). The diagnostic-therapeutic protocol and the results are described and compared with the beginning of their experience, when they treated only symptomatic gallbladder stone disease, and with the reports of the literature. The authors concluded that the laparoscopic procedure is a good chance for the surgeon in the treatment of all cases of benign biliary disease. But, in particular for patients with choledocholithiasis, he has be able to know all the diagnostic and therapeutic possibilities, to choose the best in every single case.  相似文献   
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Components of the airspace-lining material may contribute to the local regulation of immune function within the lung. We report here that recombinant rat pulmonary surfactant-associated protein D (SP-D) inhibits the lectin- and anti-CD3-stimulated proliferation of human PBMCs. Inhibition was associated with a decreased production of IL-2, and the addition of human rIL-2 blocked the inhibitory action of SP-D. These effects were not inhibited by maltose, indicating that the inhibitory activity was not dependent upon the lectin activity of SP-D. Studies employing mutant SP-D lacking N-linked sugars or defective in multimerization further indicated that inhibition was not dependent upon cellular interactions with the N-linked oligosaccharide on SP-D or the oligomerization of trimeric SP-D subunits. Although a peptide containing an inverted DGR showed similar IL-2-dependent effects on anti-CD3-stimulated proliferation, deletion of the conserved DGRDGR sequence near the amino-terminal end of the collagen domain did not decrease the suppressive activity of SP-D. We hypothesize that SP-D can dampen lymphocyte responses to exogenous stimuli and protect the lung against collateral immune-mediated damage.  相似文献   
48.
The mutants of Saccharomyces cerevisiae assigned to complementation group G199 are deficient in mitochondrial respiration and lack a functional cytochrome oxidase complex. Recombinant plasmids capable of restoring respiration were cloned by transformation of mutants of this group with a yeast genomic library. Sequencing indicated that a 2.1-kb subclone encompasses the very end (last 11 amino acids) of the PET111 gene, the COX7 gene and a new gene (YMR255W) of unknown function that potentially codes for a polypeptide of 188 amino acids (about 21.5 kDa) without significant homology to any known protein. We have shown that the respiratory defect corresponding to group G199 is complemented by plasmids carrying only the COX7 gene. The gene YMR255W was inactivated by one-step gene replacement and the disrupted strain was viable and unaffected in its ability to grow in a variety of different test media such as minimal or complete media using eight distinct carbon sources at three pH values and temperatures. Inactivation of this gene also did not affect mating or sporulation.  相似文献   
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