XIVE种植体即刻植入即刻负重的临床观察

目的：评价XIVE种植体在上颌外伤前牙区即刻种植即刻负重修复的临床效果。方法：对26例前牙区单颗或多颗无法保留的外伤残根拔除后,即刻植入XIVE种植体,并即刻负重修复。种植体扭矩控制在35Ncm左右,初期稳定性良好。平均四到五个月后行永久修复。在植入后1、2、4个月对其进行临床及影像学检查。结果：32枚种植体有2枚种植体2周后出现松动,一个月后脱落,其余30枚均在预期时间内形成良好骨性愈合,最终完成修复。结论：上颌前牙区单颗或多颗牙外伤,残根无法保留者,行即刻种植即刻负重修复是可行。早期种植修复有利于减缓牙槽骨的吸收,保留软硬组织的形态,缩短疗程。     

Increase in Alphaproteobacteria in association with a polychaete,Capitella sp. I,in the organically enriched sediment

We conducted bioremediation experiments on the organically enriched sediment on the sea floor just below a fish farm, introducing artificially mass-cultured colonies of deposit-feeding polychaete, Capitella sp. I. To clarify the association between the Capitella and bacteria on the efficient decomposition of the organic matter in the sediment in the experiments, we tried to identify the bacteria that increased in the microbial community in the sediment with dense patches of the Capitella. The relationship between TOC and quinone content of the sediment as an indicator of the bacterial abundance was not clear, while a significant positive correlation was found between Capitella biomass and quinone content of the sediment. In particular, ubiquinone-10, which is present in members of the class Alphaproteobacteria, increased in the sediment with dense patches of the Capitella. We performed denaturing gradient gel electrophoresis (DGGE) analyses to identify the alphaproteobacterial species in the sediment with dense patches of the worm, using two DGGE fragments obtained from the sediment samples and one fragment from the worm body. The sequences of these DGGE fragments were closely related to the specific members of the Roseobacter clade. In the associated system with the Capitella and the bacteria in the organically enriched sediment, the decomposition of the organic matter may proceed rapidly. It is very likely that the Capitella works as a promoter of bacteria in the organically enriched sediment, and feeds the increased bacteria as one of the main foods, while the bacteria decompose the organic matter in the sediment with the assistance of the Capitella.     

Bacillus subtilis bacteriophage SPP1-encoded gene 34.1 product is a recombination-dependent DNA replication protein

SPP1-encoded replication and recombination proteins, involved in the early steps of the initiation of concatemeric DNA synthesis, have been analyzed. Dimeric G34.1P exonuclease degrades, with a 5' to 3' polarity and in a Mg2+-dependent reaction, preferentially linear double-stranded (ds) DNA rather than single-stranded (ss) DNA. Binding of the replisome organizer, G38P, to its cognate sites (oriDNA) halts the 5' to 3' exonucleolytic activity of G34.1P on dsDNA. The G35P recombinase increases the affinity of G34.1P for dsDNA, and stimulates G34.1P activity on dsDNA, but not on ssDNA. Then, filamented G35P promotes limited strand exchange with a homologous sequence. The ssDNA binding protein, G36P, protects ssDNA from the G34.1P exonuclease activity and stimulates G35P-catalyzed strand exchange. The data presented suggest a model for the role of G34.1P during initiation of sigma replication: G38P bound to oriDNA might halt replication fork progression, and G35P, G34.1P and G36P in concert might lead to the re-establishment of a unidirectional recombination-dependent replication that accounts for the direction of DNA packaging.     

Mechanical modulation of molecular signals which regulate anabolic and catabolic activity in bone tissue

Identifying the molecular mechanisms that regulate bone's adaptive response to alterations in load bearing may potentiate the discovery of interventions to curb osteoporosis. Adult female mice (BALB/cByJ) were subjected to catabolic (disuse) and anabolic (45 Hz, 0.3g vibration for 10 min/day) signals, and changes in the mRNA levels of thirteen genes were compared to altered indices of bone formation. Age-matched mice served as controls. Following 4 days of disuse, significant (P = 0.05) decreases in mRNA levels were measured for several genes, including collagen type I (-55%), osteonectin (-44%), osterix (-36%), and MMP-2 (-36%) all of which, after 21 days, had normalized to control levels. In contrast, expression of several genes in the vibrated group, which failed to show significant changes at 4 days, demonstrated significant increases after 21 days, including inducible nitric oxide synthase (iNOS) (39%, P = 0.07), MMP-2 (54%), and receptor activator of the nuclear factor kB ligand (RANKL) (32%). Correlations of gene expression patterns across experimental conditions and time points allowed the functional clustering of responsive genes into two distinct groups. Each cluster's specific regulatory role (formation vs. resorption) was reinforced by the 60% suppression of formation rates caused by disuse, and the 55% increase in formation rates stimulated by mechanical signals (P < 0.05). These data confirm the complexity of the bone remodeling process, both in terms of the number of genes involved, their interaction and coordination of resorptive and formative activity, and the temporal sensitivity of the processes. More detailed spatial and temporal correlations between altered mRNA levels and tissue plasticity may further delineate the molecules responsible for the control of bone mass and morphology.     

Mechanical regulation of HB-GAM expression in bone cells

Bone adaption upon mechanical stimulation is accompanied by changes in gene expression. In this context we investigated the influence of mechanical loading on heparin binding growth associated molecule (HB-GAM) expression, an extracellular matrix molecule which in cell culture has been shown to stimulate the differentiation of osteoblasts. We obtained information on the participating signal transduction pathways using a mitogenic loading regimen. Specific inhibitors of various signal transduction pathways were added to loaded cells and to unloaded controls. By semi-quantitative PCR studies we demonstrated a rapid decrease of HB-GAM expression in primary osteoblasts and SaOs-2 cells by 20-30% upon mechanical loading within 30min. We showed that the RGD-integrin interaction is involved in the regulation of HB-GAM expression. Furthermore, integrity of the cytoskeleton, stretch-activated, and voltage-sensitive Ca(2+) channels as well as gap junctional communication are necessary for the downregulation of HB-GAM expression by mechanical loading.     

Candida biofilms on implanted biomaterials: a clinically significant problem

In recent years there has been an increasing appreciation that microbial biofilms are ubiquitous, which has resulted in a number of studies on infectious diseases from a biofilm perspective. Biofilms are defined as structured microbial communities that are attached to a surface and encased in a matrix of exopolymeric material. A wide range of biomaterials used in clinical practice have been shown to support colonization and biofilm formation by Candida spp., and the increase in Candida infections in the last decades has almost paralleled the increase and widespread use of a broad range of medical implant devices, mainly in populations with impaired host defenses. Formation of Candida biofilms has important clinical repercussions because of their increased resistance to antifungal therapy and the ability of cells within biofilms to withstand host immune defenses. Further recognition and understanding of the role of Candida biofilms in human infection should help in the clinical management of these recalcitrant infections.     

Mechanical integrin stress and magnetic forces induce biological responses in mesenchymal stem cells which depend on environmental factors

The control of mesenchymal stem cells (MSC) by physical cues is of great interest in regenerative medicine. Because integrin receptors function as mechanotransducers, we applied drag forces to β1 integrins on the apical surface of adherent human MSC. In addition to mechanical forces, the technique we used involved also the exposure of the cells to an inhomogeneous magnetic field. In order to assess the influence of the substrate on cell adhesion, cells were cultured on plain tissue culture polystyrene (TCP) or on coated well plates, which allowed only adhesion to embedded fibronectin or RGD peptides. We found that the expression of collagen I, which is involved in osteogenesis, and VEGF, a factor which stimulates angiogenesis, increased as a result of short-term mechanical integrin stress. Whereas, collagen I expression was stimulated by mechanical forces when the cells were cultured on fibronectin and RGD peptides but not on TCP, VEGF expression was enhanced by physical stimulation on TCP. The study further revealed that magnetic forces enhanced Sox 9 expression, a marker of chondrogenesis, and reduced the expression of ALP. Concerning the intracellular mechanisms involved, we found that the expression of VEGF induced by physical forces depended on Akt activation. Together, the results implicate that biological functions of MSC can be stimulated by integrin-mediated mechanical forces and a magnetic field. However, the responses of cells depend strongly on the substrate to which they adhere and on the cross-talk between integrin-mediated signals and soluble factors.     

口腔种植外科相关颌骨解剖学研究进展

目前,种植义齿修复已经成为牙列缺损、缺失患者的最佳修复方式。通过对颌骨的精确测量,可获得种植手术所需相关解剖资料,为种植体的选择、设计及口腔种植手术的实施提供重要的参考。本文就口腔种植义齿相关的颌骨解剖测量进展作一综述。     

大杯香菇辐射选育新株系数量性状的因子分析

对20个大杯香菇品种和辐射选育新株系的数量性状进行因子分析.结果表明,20个大杯香菇品种和辐射选育新株系的18个数量性状,可提取为7个公因子,其累积方差贡献率达91.85 %,代表了所有性状绝大部分相关信息.按照主因子所包含的性状及其所反映的生物学、营养学和酶学含义,可把7个主因子命名并按方差贡献大小顺序排列为：促长因子1、CAT活性因子2、营养质量因子3、MDA因子7、化学评分因子4、氨基酸比值系数分因子5、粗壮因子6.从主因子出发进行大杯香菇辐射育种,可以加大目标性状的针对性的选择效率,比较容易获得综合数量性状优良的新品种.     

Simultaneous saccharification and ethanol fermentation at high corn stover solids loading in a helical stirring bioreactor

The higher ethanol titer inevitably requires higher solids loading during the simultaneous enzymatic saccharification and fermentation (SSF) using lignocellulose as the feedstock. The mixing between the solid lignocellulose and the liquid enzyme is crucially important. In this study, a bioreactor with a novel helical impeller was designed and applied to the SSF operation of the steam explosion pretreated corn stover under different solids loadings and different enzyme dosages. The performances using the helical impeller and the common Rushton impeller were compared and analyzed by measuring rheological properties and the mixing energy consumption. The results showed that the new designed stirring system had better performances in the saccharification yield, ethanol titer, and energy cost than those of the Rushton impeller stirring. The mixing energy consumption under different solids loadings and enzyme dosages during SSF operation were analyzed and compared to the thermal energy in the ethanol produced. A balance for achieving the optimal energy cost between the increased mixing energy cost and the reduced distillation energy cost at the high solids loading should be made. The potentials of the new bioreactor were tested under various SSF conditions for obtaining optimal ethanol yield and titer. Biotechnol. Bioeng. 2010. 105: 718–728. © 2009 Wiley Periodicals, Inc.