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排序方式: 共有222条查询结果,搜索用时 15 毫秒
1.
OBJECTIVE: The objective of this study is to evaluate the effect of amalgam bonding on the stiffness of teeth weakened by cavity preparation. METHODS: Strain gages were bonded to maxillary premolars. The rigidity was tested by applying a load to a sequence of sound, prepared and restored teeth as follows: sound tooth, MOD preparation, amalgam restoration, amalgam removed recovering the MOD preparation, bonded amalgam restoration, bonded amalgam removed recovering the MOD preparation, bonded composite restoration. The relative stiffness (RS) and relative deformation (RD) of each condition for each cusp to that of the sound tooth was determined. RESULTS: The premolar cusps were deformed 1.80, 2.14, and 2.32 times more than the cusps of the sound tooth for the three succeeding MOD preparations. For these three preparations, the stiffness of the premolar cusps was 0.58, 0.48, and 0.46 relative to a stiffness of 1.00 for the sound tooth. The deformation was 1.77, 1.27, and 1.16 for the non-bonded amalgam, the bonded amalgam, and the bonded composite, respectively, corresponding to a mean RS of 0.59, 0.80, and 0.88. The calculated mean stiffness parameter C (standard deviation) was 2.6% (6.9) for the amalgam restoration, 62.5% (12.8) for the bonded amalgam restoration, and 77.8% (15.8) for the bonded composite restoration. The stiffness parameter C measured the extent to which the procedure returned the stiffness of the restored tooth to the original stiffness of the intact tooth (100%). SIGNIFICANCE: Cavity preparation reduced the stiffness and weakened the tooth. Restoring the prepared tooth with unbonded amalgam did not restore the lost tooth stiffness. Restoring the prepared tooth with bonded amalgam or with bonded composite recovered a significant portion of the lost tooth stiffness. It was concluded that bonding amalgam to tooth structure could partly restore the strength and rigidity lost by the cavity preparation. This might lead to a reduction in cuspal flexure and the incidence of tooth fracture due to fatigue. 相似文献
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Mohamed Labib Salem Abdel-Aziz A. Zidan Randa Ezz El-Din El-Naggar Mohamed Attia Saad Mohamed El-Shanshory Usama Bakry Mona Zidan 《Human immunology》2021,82(1):36-45
BackgroundRelapse remains a critical challenge in children with acute lymphoblastic leukemia (ALL). The emergence of immunoregulatory cells, including myeloid-derived suppressor cells (MDSCs), and T regulatory (Treg) cells, has been considered one potential mechanism of relapse in children with ALL.AimThis study aimed to address the microRNAs (miRNAs) related to MDSCs and Treg cells and to explore their targeted immunoregulatory pathways.MethodsAffymetrix microarray was used for global miRNA profiling in B-ALL pediatric patients before, during, and after induction of chemotherapy. Bioinformatics analysis was performed on MDSCs and Treg cells-related dysregulated miRNAs, and miR-Pathway analysis was performed to explore their targeted immunoregulatory pathways.Results516 miRNAs were dysregulated in ALL patients as compared to the healthy donor. Among them, 13 miRNAs and 8 miRNAs related to MDSCs and Treg cells, respectively, were common in all patients. Besides, 12 miRNAs were shared between MDSCs and Treg cells; 4 of them were common in all patients. Four immune-related pathways; TNF, TGF-β, FoxO, and Hippo were found implicated.ConclusionOur pilot study concluded certain miRNAs related to MDSCs and Treg cells, these miRNAs were linked to immunoregulatory pathways. Our results open avenues for testing those miRNA as molecular biomarkers for the immunosuppressive tumor microenvironment. 相似文献
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Dovrat S Figer A Fidder HH Neophytou P Fireman Z Geva R Zidan J Flex D Meir SB Friedman E 《Familial cancer》2005,4(4):291-294
Germline mutations in DNA mismatch repair (DNA-MMR) genes, mainly hMlh1 and hMsh2, underlie Hereditary Non-Polyposis Colorectal Cancer (HNPCC). Germline hMSH6 gene mutations have been reported in a small subset of HNPCC families. In the present study, ethnically diverse individuals
with HNPCC and HNPCC-like features were genotyped for hMsh6 germline mutations using exon-specific PCR, DGGE, and DNA sequencing. The study encompassed 92 individuals representing 88
unrelated families who were previously analyzed for Msh2 and Mlh1 mutations: Jewish Ashkenazim (n = 44), non-Ashkenazim (n = 27), Israeli Moslem-Arab (n = 15), Druze (n=3), and Cypriot non-Jews (n = 3). Of the study population, 71 had colon cancer (CRC), mean age at diagnosis was 50.9±13.2 years (range16–73 years), 5
had endometrial cancer (two with concurrent CRC), (mean 43.6±3.26 years, range 38–45 years), and unaffected individuals (n = 18) were first degree relatives within HNPCC families and were genotyped at a mean age of 48.3±11.7 years (range 30–69 years).
Of the 92 individuals analyzed, none showed a truncating hMsh6 mutation, and 6 (6.6%) harbored one of three germline missense mutations: a previously reported one (V878A), and two novel
mutations (V509A, S227I). The pathogenic significance of these three missense mutations is yet unclear. In addition, 5 polymorphisms
were detected, 2 of which were novel.
We conclude that the rate of pathogenic hMsh6 mutations in HNPCC families of Jewish and Mediterranean origin is low, and that mutations in other genes probably account
for the phenotype in these families. 相似文献
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Gal I Gershoni Baruch R Haber D Dagan E Eisenberg-Barzilai S Zidan J Friedman E 《Familial cancer》2004,3(1):11-14
Few mutations have been described in BRCA1 and BRCA2 in high-risk non-Ashkenazi Jews. In a Libyan family the 1100delAT BRCA1 mutation was detected and the 8765delAG BRCA2 mutation was previously described in two Jewish-Yemenite-families. In this study, the rate of these mutations in high-risk Jews of North African and Yemenite origin was assessed, and the BRCA1 -linked haplotype of Jewish and non-Jewish 1100delAT mutation carriers were compared. Genotyping included 64 high-risk Yemenite women (tested only for the BRCA 2 mutation) and 147 high-risk North African women, tested for both mutations. PCR amplification was followed by either restriction enzyme digestion or DGGE or dHPLC analyses and direct sequencing. For haplotyping, 5 BRCA1 -linked markers were used. Neither the 1100delAT BRCA1 nor the 8765delAG BRCA2 mutations were detected in any non-Ashkenazi individual. The haplotype of the non-Jewish 1100delAG mutation carrier differed from that of the Jewish-Libyan mutation carriers. We conclude that both1100delAT BRCA1 and 8765delAG BRCA2 mutations occur rarely in high-risk non-Ashkenazi Jews, and while the latter seems to be a founder mutation in some populations, the former occurs on a different background in ethnically diverse families. 相似文献
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Bayoumi AE Pérez-Pertejo Y Zidan HZ Balaña-Fouce R Ordóñez C Ordóñez D 《Ecotoxicology and environmental safety》2003,55(1):19-23
Cytotoxicity of two insect growth regulators, diflubenzuron, a benzoylphenylurea derivative that inhibits the synthesis of new chitin in target organisms, and pyriproxyfen, an insect juvenile hormone analogue, were tested on CHO-K1 cultures, using the neutral red incorporation assay. Both compounds displayed cytotoxic effects that rise with time exposure. The presence of either fetal calf serum or bovine serum albumin diminished significantly the cytotoxicity of both compounds, thus pointing to a strong protein binding. In addition, extensive metabolization with rat liver submitochondrial fraction gave rise to metabolites less toxic than the parent compounds, implying the relative safety of both diflubenzuron and pyriproxyfen in mammals. 相似文献
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Knowledge of the effects of different product and process variability on microparticle characterization is essential for the successful development, optimization, and scale-up of an encapsulation process. In the current research, the qualitative application of the Lasentec focused beam reflectance (FBRM) system for online monitoring of microparticle size distribution was demonstrated. lasentec particle vision and measurement (PVM) images were also employed to follow up the steps of microparticle formation and ripening. The drug entrapment efficiency and drug release characteristics were found to be dependent on the polymer, drug, and surfactant concentrations. DSC, FTIR, and XRD data revealed that the drug was compatible with the matrix forming polymer in the solid state. As indicated from the chord count data, FBRM was sensitive to the amount of the solid materials and the number of microparticles formed. Linear relationships with good correlations were obtained between polymer, drug, and surfactant levels and the disappearance rate of 5 to 36.8, 18.4 to 135.9, and 63 to 398 µm chord length fractions. Upon organic solvent evaporation, PVM imaging detected various stages of microemulsion droplets, sheath formation, and solidification with subsequent microparticle hardening. This study illustrated the utility of FBRM and PVM in monitoring the progress of particle formation during drug encapsulation. 相似文献