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91.
关于牙周炎定义标准   总被引:3,自引:0,他引:3  
牙周病学研究中牙周炎定义标准的差别给相似研究间的比较带来了很大的困扰,甚至同一数据根据不同牙周炎定义标准得出不同的结论。因此牙周炎定义标准的统一已是众望所归。本文就流行病学研究中不同牙周炎定义标准、分度标准进行综述。  相似文献   
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The gerbil is a rodent considered a good model for studies of prostatic morphophysiology under different experimental conditions. Studies involving castration and steroidal blockers of aged gerbils showed that the glandular epithelium persists after long-term therapy, preventing the organ atrophy. Thus, the objective of this study was to evaluate the phenotypic characteristics and behavior of prostatic epithelial cells that remained after different periods of hormone ablation in aged gerbils. The identification of elements that influenced the survival of this cell type was performed by morphometric, nuclear phenotypes, ultrastructural and immune histochemical analysis. The most significant responses to treatment, by analyzing morphometric features, were observed during the first three time points (day 1, day 3, and day 7), after which there appeared to be an adjustment of the gland to the hormone ablation. All treatments led to changes in the state of chromatin condensation, DNA methylation pattern and phenotypic changes indicated cell senescence. Additionally, an increase in the basal cells seemed to guarantee self-renewal properties to the epithelium. These data indicate that changes occur at many levels, including gene expression and nuclear architecture in the epithelial cells, when aging and steroidal blockade are associated. These aspects are important when considering castration-resistant prostate cancer, a malignant tumor posing difficult therapeutic intervention.  相似文献   
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The use of synthetic biological systems in research, healthcare, and manufacturing often requires autonomous history-dependent behavior and therefore some form of engineered biological memory. For example, the study or reprogramming of aging, cancer, or development would benefit from genetically encoded counters capable of recording up to several hundred cell division or differentiation events. Although genetic material itself provides a natural data storage medium, tools that allow researchers to reliably and reversibly write information to DNA in vivo are lacking. Here, we demonstrate a rewriteable recombinase addressable data (RAD) module that reliably stores digital information within a chromosome. RAD modules use serine integrase and excisionase functions adapted from bacteriophage to invert and restore specific DNA sequences. Our core RAD memory element is capable of passive information storage in the absence of heterologous gene expression for over 100 cell divisions and can be switched repeatedly without performance degradation, as is required to support combinatorial data storage. We also demonstrate how programmed stochasticity in RAD system performance arising from bidirectional recombination can be achieved and tuned by varying the synthesis and degradation rates of recombinase proteins. The serine recombinase functions used here do not require cell-specific cofactors and should be useful in extending computing and control methods to the study and engineering of many biological systems.  相似文献   
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The longevity gene clk-1/coq7 encodes an enzyme that is essential for the biosynthesis of coenzyme Q (CoQ) in mitochondria and regulates the lifespan and behavioral timing in Caenorhabditis elegans and the chronological lifespan in fission yeast. However, whether the mammalian clk-1/coq7 ortholog (clk-1) regulates these phenotypes in mammals remains to be fully evaluated due to the embryonic lethality of clk-1-deficient (clk-1(-/-)) mice. To investigate whether clk-1 regulates biological functions, such as growth and heartbeat, through CoQ in mouse embryos, we cultivated the cells and hearts of clk-1(-/-) mouse embryos at embryonic day 10.5 (E10.5) for at least 10 days in the presence of fetal bovine serum. In embryonic cells, cardiomyocytes, and hearts, the growth and heart rates were significantly slowed in clk-1(-/-) compared with wild-type or heterozygous mouse tissues. Moreover, frequent apoptosis and a significant reduction in mitochondrial functions, including membrane potential and ATP production, were observed in the clk-1(-/-) cells and hearts. The slowed growth and heart rates and the reduced mitochondrial function of clk-1(-/-) embryonic cells and hearts in culture were almost completely rescued by the administration of exogenous CoQ(10). The results indicate that clk-1 regulates growth and heart rates through CoQ-mediated mitochondrial functions in mouse embryos.  相似文献   
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Due to a lack of available size‐matched liver grafts from children, most pediatric recipients are transplanted with technical variant grafts from adult donors. Size requirements for these grafts are not well defined, and consequences of mismatched graft sizes in pediatric liver transplantation are not known. Existing formulas for calculation of a standard liver volume are mostly derived from adults disregarding the age‐related percentual liver weight changes in children. In this study, we aimed to establish a formula for general use in children to calculate the standard liver volume. In a second step, the formula was applied in pediatric patients undergoing liver transplantation at our institution between 2000 and 2010 (n = 377). Analysis of a large number (n = 388) of autopsy data from children by regression analysis revealed a best fit for two formulas: “Formula 1,” children 0 to ≤1 year (n = 246): standard liver volume [ml] = ?143.062973 +4.274603051 * body length [cm] + 14.78817631 * body weight [kg]; “Formula 2,” children >1 to <16 years (n = 142): standard liver volume [ml] = ?20.2472281 + 3.339056437 * body length [cm] + 13.11312561 * body weight [kg]. In comparison with children receiving size‐matched organs, we found an elevated risk of liver graft failure in children transplanted with a small‐for‐size graft, whereas large‐for‐size organs seem to have no negative impact.  相似文献   
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