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排序方式: 共有1674条查询结果,搜索用时 15 毫秒
1.
F. Schmidutz Y. Agarwal P.E. Müller B. Gueorguiev R.G. Richards C.M. Sprecher 《Journal of biomechanics》2014
Cementless surface replacement arthroplasty (CSRA) of the shoulder was designed to preserve the individual anatomy and humeral bone stock. A matter of concern in resurfacing implants remains the stress shielding and bone remodeling processes. The bone remodeling processes of two different CSRA fixation designs, conical-crown (Epoca RH) and central-stem (Copeland), were studied by three-dimensional (3-D) finite element analysis (FEA) as well as evaluation of contact radiographs from human CSRA retrievals. FEA included one native humerus model with a normal and one with a reduced bone stock quality. Compressive strains were evaluated before and after virtual CSRA implantation and the results were then compared to the bone remodeling and stress-shielding pattern of eight human CSRA retrievals (Epoca RH n=4 and Copeland n=4). FEA revealed for both bone stock models increased compressive strains at the stem and outer implant rim for both CSRA designs indicating an increased bone formation at those locations. Unloading of the bone was seen for both designs under the central implant shell (conical-crown 50–85%, central-stem 31–93%) indicating high bone resorption. Those effects appeared more pronounced for the reduced than for the normal bone stock model. The assumptions of the FEA were confirmed in the CSRA retrieval analysis which showed bone apposition at the outer implant rim and stems with highly reduced bone stock below the central implant shell. Overall, clear signs of stress shielding were observed for both CSRAs designs in the in vitro FEA and human retrieval analysis. Especially in the central part of both implant designs the bone stock was highly resorbed. The impact of these bone remodeling processes on the clinical outcome as well as long-term stability requires further evaluation. 相似文献
2.
As part of the development of carbon-coated prosthetic devices, the adhesion of thin carbon films to metallic substrates has been studied. The bond strength of carbon films about 5000 A thick on Ti-6A1-4V and stainless steel was measured in a pull test and found to be greater than 4700 psi. Auger electron spectroscopy showed a reactive film/substrate interface. The ultimate bond strength was found to be dependent on the substrate and the deposition parameters. 相似文献
3.
Three pathogenic strains of Pseudomonas phaseolicola (strain 1 and 3 virulent and strain 5 weakly virulent) were tested for their toxic activity. All three strains produced detectable amounts of toxin in vitro. Cultural conditions and length of incubation greatly influenced toxin production. Maximum amount of toxin was produced at 20°C and pH 6.5. Glycerol served as the best carbon source and 1-cysteine as the best amino acid for toxin production. 相似文献
4.
Adult male Wistar rats were exposed to methylisocyanate (MIC, 3.2 mg/l, single inhalation exposure for 8 min under static condition) or ethyl methanesulphonate (EMS, 150 mg/kg, single ip dose) for the assessment of germ cell mutagenicity and reproductive effects. Sequential matings of treated males with normal females on days 1-7, 8-14 and 15-21 post-exposure did not indicate any induction of dominant lethal mutation (increased frequency of preimplantation losses and early fetal deaths) by MIC but it was significantly induced by EMS as compared to respective controls. Males, necropsied after 21 days of exposure, showed no effect of MIC on epididymal sperm density and morphology. EMS also had no effect on sperm density but it significantly induced morphological abnormalities in sperm as compared to untreated controls. There was an acute and transitional reduction in reproductive performance (10-21%) of MIC-exposed males during days 1-14 post-exposure followed by recovery to the normal level during days 15-21 post-exposure. The progeny of MIC-exposed males was also normal in terms of litter size, litter weight, neonatal survival and body weight gain in litters up to 10 days post-partem. It is concluded with the evidence at hand that the observed failure of MIC to cause germ cell mutagenicity is related to its poor biodistribution to the target site(s) and a transient reduction in the reproductive performance of MIC-exposed males is a result of general stress and disconsolate copulation. 相似文献
5.
Beena Punnamoottil Carl Herrmann Salvatore D'Aniello Altuna Akalin Thomas S. Becker Silke Rinkwitz 《Developmental biology》2010,340(2):269-531
Hox genes are key regulators of anterior-posterior axis patterning and have a major role in hindbrain development. The zebrafish Hox4 paralogs have strong overlapping activities in hindbrain rhombomeres 7 and 8, in the spinal cord and in the pharyngeal arches. With the aim to predict enhancers that act on the hoxa4a, hoxb4a, hoxc4a and hoxd4a genes, we used sequence conservation around the Hox4 genes to analyze all fish:human conserved non-coding sequences by reporter assays in stable zebrafish transgenesis. Thirty-four elements were functionally tested in GFP reporter gene constructs and more than 100 F1 lines were analyzed to establish a correlation between sequence conservation and cis-regulatory function, constituting a catalog of Hox4 CNEs. Sixteen tissue-specific enhancers could be identified. Multiple alignments of the CNEs revealed paralogous cis-regulatory sequences, however, the CNE sequence similarities were found not to correlate with tissue specificity. To identify ancestral enhancers that direct Hox4 gene activity, genome sequence alignments of mammals, teleosts, horn shark and the cephalochordate amphioxus, which is the most basal extant chordate possessing a single prototypical Hox cluster, were performed. Three elements were identified and two of them exhibited regulatory activity in transgenic zebrafish, however revealing no specificity. Our data show that the approach to identify cis-regulatory sequences by genome sequence alignments and subsequent testing in zebrafish transgenesis can be used to define enhancers within the Hox clusters and that these have significantly diverged in their function during evolution. 相似文献
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Bahare Shokoohian Babak Negahdari Hamidreza Aboulkheyr Es Manuchehr Abedi-Valugerdi Kaveh Baghaei Tarun Agarwal Tapas Kumar Maiti Moustapha Hassan Mustapha Najimi Massoud Vosough 《Journal of cellular and molecular medicine》2021,25(18):8602-8614
Hepatocellular carcinoma (HCC), the most common type of liver cancer, is usually a latent and asymptomatic malignancy caused by different aetiologies, which is a result of various aberrant molecular heterogeneity and often diagnosed at advanced stages. The incidence and prevalence have significantly increased because of sedentary lifestyle, diabetes, chronic infection with hepatotropic viruses and exposure to aflatoxins. Due to advanced intra- or extrahepatic metastasis, recurrence is very common even after radical resection. In this paper, we highlighted novel therapeutic modalities, such as molecular-targeted therapies, targeted radionuclide therapies and epigenetic modification-based therapies. These topics are trending headlines and their combination with cell-based immunotherapies, and gene therapy has provided promising prospects for the future of HCC treatment. Moreover, a comprehensive overview of current and advanced therapeutic approaches is discussed and the advantages and limitations of each strategy are described. Finally, very recent and approved novel combined therapies and their promising results in HCC treatment have been introduced. 相似文献
9.
Md. Javed Equbal Preeti Srivastava Gopal Prasad Agarwal Jahar Kanti Deb 《Applied microbiology and biotechnology》2013,97(17):7755-7766
The industrially important species of corynebacteria viz. Corynebacterium acetoacidophilum appear to be alternative hosts for recombinant protein production; despite many efforts, a strong promoter-based system in corynebacteria has not been established so far. Described here is a T7 promoter-based expression system which was functional in both gram-positive C. acetoacidophilum and gram-negative Escherichia coli in an external inducer independent manner. This is the very first report of a T7 expression system for Corynebacterium sp. Also, it is a useful addition in the existing T7 expression systems of E. coli. 相似文献
10.
The spontaneous organization on a substrate of nanoparticles (NPs) nucleated in a laser-generated plasma results in self-assembling due to both direct specific interactions and to indirect ambient-mediated ones. A number of well-differentiated film morphologies are observed, from isolated NPs to percolated island structures. The distribution of the width of gaps between NPs, or islands formed upon NP coalescence in two representative percolated Au films, is lognormal, indicating that the growth process is random. A finer inspection of similar surface morphologies allows to correlate regularity in gap sizes and surface coverage to differences in film performance as substrates for surface-enhanced Raman spectroscopy. 相似文献