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941.
153 regional lymph nodes obtained during surgical operations because of cancer of various cites from 50 cancer patients were studied. Failure of local immunity is explained by the following factors: 1) depletion of T-cell population with a decrease of activated lymphocyte-killers; 2) high activity of B-cell population able to block T-cell cytotoxic effect; 3) deficiency of T-suppressors and T-helpers; 4) a decrease of macrophages-monocytes of phagocytic capacity; 5) high activity of dendritic reticular cells stimulating transformation of B-lymphocytes and low activity of interdigitating reticulocytes determining T-cell immunity stimulation.  相似文献   
942.
Rabies enzootics in southern Africa are associated with two genetically distinct groups of viruses, thought to be adapted to two different sets of host species. The virus groups are referred to as the canid biotype (infecting carnivores of the family Canidae) and the viverrid biotype (infecting carnivores of the subfamily Viverrinae). Cross- or spillover infections of one biotype into the host range of the other are thought to occur from time to time. However, very little is known about this phenomenon and its role in the epidemiology of rabies in southern Africa. We have investigated spillover by monoclonal antibody and nucleic acid sequence analysis of a wide range of virus isolates. Although the inverse had been documented, this report constitutes the first evidence of spillover of canid biotype viruses into viverrid hosts. Our genetic analysis was focused specifically on the G-L intergenic region of the virus genome, thought to be a remnant or pseudogene and it was indicated that, with respect to this region of the genome, spillover does not influence the phylogeny of virus isolates.  相似文献   
943.
The Japanese pufferfish Fugu rubripes has a 400 Mb genome with high gene density and minimal non-coding complexity, and is therefore an ideal vertebrate model for sequence comparison. The identification of regions of conserved synteny between Fugu and humans would greatly accelerate the mapping and ordering of genes. Fugu C9 was cloned and sequenced as a first step in an attempt to characterize the region in Fugu homologous to human chromosome 5p13. The 11 exons of the Fugu C9 gene share 33% identity with human C9 and span 2.9 kb of genomic DNA. By comparison, human C9 spans 90 kb, representing a 30-fold difference in size. We have also determined by cosmid sequence scanning that DOC-2, a tumour suppresser gene which also maps to human 5p13, lies 6-7 kb from C9 in a head-to-head or 5' to 5' orientation. These results demonstrate that the Fugu C9/DOC-2 locus is a region of conserved synteny. Sequence scanning of overlapping cosmids has identified two other genes, GAS-1 and FBP, both of which map to human chromosome 9q22, and lie adjacent to the Fugu C9/DOC-2 locus, indicating the boundary between two syntenic regions.  相似文献   
944.
A 67-year-old man with metastatic melanoma and chronic lymphocytic leukemia was inadvertently given a vaccinia melanoma oncolysate vaccination. He developed progressive vaccinia at the site of inoculation. The lesion started to heal only when he was treated with ribavirin. Vaccinia immune globulin was administered and appeared to help control the initial lesion and limit the development of satellite lesions.  相似文献   
945.
Owing to the complexity of the parathyroid hormone's metabolic interactions, clinical hypoparathyroidism is one of the most difficult of all endocrine disorders to treat. Therefore, causative treatment of this disorder by transplantation of parathyroid glands is highly desirable. We have recently documented the long-term in vivo function of iso- and allotransplanted rat parathyroid tissue without systemic immunosuppression in an animal model. In view of the potential clinical use of this method, human parathyroid tissue has been microencapsulated and transplanted over the highest immunological barrier. In a controlled, long-term animal study in the parathyroidectomized rat, the effect of microencapsulation on xenotransplanted human parathyroid tissue was evaluated over 30 weeks (native and microencapsulated parathyroid tissue = 40 rats respectively). Functionally, human parathyroid tissue was able to replace that of the rat. All animals that had received microencapsulated parathyroid tissue were normocalcemic for 16 weeks; 27/40 at the end of the study. In contrast, serum calcium concentrations dropped to post-parathyroidectomy levels within 4 weeks in those animals that had received native tissue only. Histologic evaluation of the explanted, functionally successful xenografts showed vital parathyroid tissue inside intact microcapsules surrounded by a small rim of fibroblasts. Avital fibrotic remnants were demonstrated in animals with non-encapsulated parathyroid tissue. Thus, we have established the feasibility of microencapsulation of human parathyroid tissue, preserving its viability over long periods in vivo even if xenotransplanted. In combination with an improved tissue culture method, transplantation of human parathyroid tissue and maintenance of its physiological function is reproducibly achieved without postoperative systemic immunosuppression over the highest transplantation barrier. This may be a crucial step towards the first clinical application of this method.  相似文献   
946.
Recently, a T-to-A transversion creating an 8-base mononucleotide tract in the APC gene, resulting in substitution of lysine for isoleucine at codon 1307 (I1307K), was found in a subset of Ashkenazi Jews. This sequence variant was most frequent in colorectal cancer patients with a positive family history of colorectal cancer. To determine whether the I1307K variant plays a role in colorectal or breast cancer predisposition in the Norwegian population, we have analyzed blood samples from 210 colorectal cancer patients and 183 breast cancer patients by PCR and direct sequencing. Thirty-seven of the colorectal cancer patients had a positive family history of cancer. Among the breast cancer patients, 24 had a family history of colorectal cancer and 75 a family history of breast and/or ovarian cancer. Only one colorectal cancer patient who belonged to a Jewish family was found to carry the A variant. Our data show that the I1307K variant is rare in the Norwegian population and should not be viewed as a candidate for susceptibility testing for colorectal cancer.  相似文献   
947.
Thrombin, a serine protease with a central role in thrombosis and hemostasis, is also a specific agonist for a variety of cellular responses in osteoblasts and stimulates bone resorption in organ culture. Cultured osteoblast-like cells express the proteolytically activated thrombin receptor, but the significance of this finding in vivo remains unknown. Immunohistochemistry was used to investigate the normal tissue distribution of the proteolytically activated thrombin receptor in developing rat bones and associated tissues. In hind limbs, the receptor was first observed on embryonic day 16 and became more abundant within the limb as gestation progressed. Thrombin receptor staining was detected on osteoblasts, macrophages, muscle cells, and endothelial cells, but not osteoclasts. Similarly, osteoblasts in developing calvariae stained positively for the thrombin receptor. The pattern of receptor expression by primary osteoblast cultures and freshly isolated macrophages and osteoclasts corresponded to that observed in vivo. The observed pattern of thrombin receptor expression in bone cells supports the hypothesis that cell-mediated thrombin-induced bone resorption is mediated by osteoblasts.  相似文献   
948.
949.
BACKGROUND: It has been proposed that Streptomyces malonyl CoA: holo acyl carrier protein transacylases (MCATs) provide a link between fatty acid and polyketide biosynthesis. Two recent studies have provided evidence that the presence of MCAT is essential for polyketide synthesis to proceed in reconstituted minimal polyketide synthases (PKSs). In contrast to this, we previously showed that the holo acyl carrier proteins (ACPs) from type II PKSs are capable of catalytic self-malonylation in the presence of malonyl CoA, which suggests that MCAT might not be necessary for polyketide biosynthesis. RESULTS: We reconstituted a homologous actinorhodin (act) type II minimal PKS in vitro. When act holo-ACP is present in limiting concentrations, MCAT is required by the synthase complex in order for polyketide biosynthesis to proceed. When holo-ACP is present in excess, however, efficient polyketide synthesis proceeds without MCAT. The rate of polyketide production increases with holo-ACP concentration, but at low ACP concentration or equimolar AC:KS:CLF (KS, ketosynthase; CLF, chain length determining factor) concentrations this rate is significantly lower than expected, indicating that free holo-ACP is sequestered by the KS/CLF complex. CONCLUSIONS: The rate of polyketide biosynthesis is dictated by the ratio of holo-ACP to KS and CLF, as well as by the total protein concentration. There is no absolute requirement for MCAT in polyketide biosynthesis in vitro, although the role of MCAT during polyketide synthesis in vivo remains an open question. MCAT might be responsible for the rate enhancement of malonyl transfer at very low free holo-ACP concentrations or it could be required to catalyse the transfer of malonyl groups from malonyl CoA to sequestered holo-ACP.  相似文献   
950.
The sudden and unforeseen death of a child in the first two years, usually happening during a sleeping period, is known as cot death. As cot death is a very tragic and dramatic experience for the family, it is important to reduce its incidence. In the period between 1972 and 1987, the number of cot deaths initially increased, but during the last decade a substantial reduction could be observed. This fluctuation can be connected with the position in which the baby is put to sleep. From 1970 the prone sleeping position was strongly recommended. Since then, the number of cot death cases increased. From 1987, a causal relationship between the prone sleeping position and cot death was suspected. As a result the prone sleeping position was strongly advised against. A reduction of cot death cases was then observed. By now, the role of many other factors in cot death has been perceived. The risk of cot death is increased if these factors act at the same time. Some of these factors that promote cot death come from the child's environment and can be influenced when kept in mind. Apart from the prone or side sleeping position, heat congestion, unsafe bed material and smoking in the presence of the child substantially increase the risk of cot death. The main recommendations of the committee which drew up the Dutch consensus report on prevention of cot death are therefore aimed at avoiding the above mentioned risk factors. Continuation of research is necessary to further reduce the current number of some 50 cases of cot death which happen yearly in the Netherlands.  相似文献   
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