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121.
A case of precursor B-cell lymphoma of unusual location in the mandible is presented. Clinical features as well as technical examinations led to the misdiagnosis of chronic osteomyelitis. Only immunohistological examination of intraoperatively taken biopsies was able to reveal the true diagnosis. High-dose chemotherapy was started and full remission could be achieved. 相似文献
122.
Viruses are ubiquitous components of marine ecosystems and are known to infect unicellular phycoerythrin-containing cyanobacteria belonging to the genus Synechococcus. A conserved region from the cyanophage genome was identified in three genetically distinct cyanomyoviruses, and a sequence analysis revealed that this region exhibited significant similarity to a gene encoding a capsid assembly protein (gp20) from the enteric coliphage T4. The results of a comparison of gene 20 sequences from three cyanomyoviruses and T4 allowed us to design two degenerate PCR primers, CPS1 and CPS2, which specifically amplified a 165-bp region from the majority of cyanomyoviruses tested. A competitive PCR (cPCR) analysis revealed that cyanomyovirus strains could be accurately enumerated, and it was demonstrated that quantification was log-linear over ca. 3 orders of magnitude. Different calibration curves were obtained for each of the three cyanomyovirus strains tested; consequently, cPCR performed with primers CPS1 and CPS2 could lead to substantial inaccuracies in estimates of phage abundance in natural assemblages. Further sequence analysis of cyanomyovirus gene 20 homologs would be necessary in order to design primers which do not exhibit phage-to-phage variability in priming efficiency. It was demonstrated that PCR products of the correct size could be amplified from seawater samples following 100x concentration and even directly without any prior concentration. Hence, the use of degenerate primers in PCR analyses of cyanophage populations should provide valuable data on the diversity of cyanophages in natural assemblages. Further optimization of procedures may ultimately lead to a sensitive assay which can be used to analyze natural cyanophage populations both quantitatively (by cPCR) and qualitatively following phylogenetic analysis of amplified products. 相似文献
123.
NH Horwitz 《Canadian Metallurgical Quarterly》1997,41(6):1442-1445
124.
Fluoride tolerance of laying hens 总被引:1,自引:0,他引:1
Myogenic precursor cells withdraw irreversibly from the cell cycle as they differentiate into mature myotubes. Cell cycle exit occurs early during the differentiation program and is required for normal expression of the contractile phenotype. Differentiated myocytes also display a decreased propensity to undergo apoptotic cell death. The upregulation of the cyclin-dependent kinase inhibitor p21 and the dephosphorylation of retinoblastoma protein (pRb) appear to be critical regulatory events for the establishment of both the postmitotic and apoptosis-resistant states. The coordinated regulation of cell proliferation and death provides the developing embryo with a mechanism for controlling muscle mass and thereby the size of individual motor units. 相似文献
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