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31.
32.
目的比较不同表面粗糙度的牙科银汞合金试件的断裂载荷,探讨试件表面状况对脆性牙科材料抗折力的影响。方法制作直径10mm、厚2mm的圆盘形银汞试件48个.随机分成4组,其中3组分别以220、400、1200号SiC砂纸双面磨平.另一组不经打磨.表面保持试件制作完毕后的自然状态。每组随机抽取5个试件,置于粗糙度测试仪上测量表面粗糙度。试件于(23±1)。C空气中保存7d后置于30%玻璃纤维加强尼龙6.6基底上以20mm直径不锈钢球加载进行赫兹压痕试验,记录初始断裂载荷值并进行统计分析。结果未经打磨、220号、400号、1200号SiC砂纸打磨的试件的表面粗糙度平均值分别为1.77、1.99、1.28、0.66μm,断裂载荷值分别为(656.1±44.1)、(644.9±57.9)、(678.3±40.4)、(721.1±60.1)N。随着粗糙度的降低,初始断裂载荷值逐渐增加,1200号砂纸打磨组与未经打磨组和220号砂纸打磨组之间差异有统计学意义(P〈0.05)。结论脆性材料试件的表面粗糙度对其抗折能力有一定影响. 相似文献
33.
Ross AA; Cooper BW; Lazarus HM; Mackay W; Moss TJ; Ciobanu N; Tallman MS; Kennedy MJ; Davidson NE; Sweet D 《Blood》1993,82(9):2605-2610
Although peripheral blood stem cell collections (PBSC) are thought to have less tumor involvement than bone marrow (BM), the incidence of circulating tumor cells in patients with breast cancer has not been widely investigated. We prospectively investigated the incidence and viability of tumor cell involvement in PBSC and BM collections from breast cancer patients undergoing high-dose chemotherapy/hematopoietic stem cell transplantation. Paired samples of PBSC and BM from 48 patients were analyzed using an immunocytochemical technique that detects one epithelial-derived tumor cell per 5 x 10(5) mononuclear cells. Immunostained tumor cells were detected in 9.8% (13/133) PBSC specimens from 9/48 (18.7%) patients and in 62.3% (38/61) BM specimens from 32/48 (66.7%) patients, a significantly higher rate than in PBSC (P < .005). The geometric mean concentration of tumor cells in contaminated PBSC specimens was 0.8/10(5) mononuclear cells (range 0.33 to 2.0/10(5)) compared with 22.9/10(5) mononuclear cells in BM (range 1 to 3,000/10(5), P < .0001). In culture experiments, clonogenic tumor colonies grew in 21/26 immunocytochemically positive specimens. No tumor colony growth was detected in 30/32 immunocytochemically negative specimens. Immunocytochemical detection of tumor involvement in BM and PBSC correlated significantly with in vitro clonogenic growth (P < .0001). We conclude that PBSC contain fewer tumor cells than paired BM specimens from patients with advanced breast cancer and that these tumor cells appear to be capable of clonogenic growth in vitro. 相似文献
34.
Schaafsma MR; Fibbe WE; Van Damme J; Duinkerken N; Ralph P; Kaushansky K; Altrock BW; Willemze R; Falkenburg JH 《Blood》1989,74(8):2619-2623
Interleukin-6 (IL-6) is a multifunctional cytokine that plays a role in regulation of hematopoiesis. Because IL-6 is coinduced with colony- stimulating factors (CSFs) by various cell types in response to stimulation with IL-1, we investigated whether IL-6 is involved in the IL-1-induced production of CSF by human bone marrow (BM) cells in long- term culture or human fibroblasts. We showed that IL-6 does not induce CSF production by these cells. Neither addition of exogenous IL-6 nor neutralization of endogenous production of IL-6 by an anti-IL-6 monoclonal antibody (MoAb) diminished the IL-1-induced colony- stimulating activity (CSA), indicating that IL-6 did not act synergistically with IL-1. Finally, IL-6 did not influence the kinetics of IL-1-induced CSA production by human fibroblasts. We conclude that IL-6, either alone or in combination with IL-1, does not induce CSF production by human BM stromal cells or fibroblasts. 相似文献
35.
Cryptic structural lesions in refractory partial epilepsy: MR imaging and CT studies 总被引:4,自引:0,他引:4
Ormson MJ; Kispert DB; Sharbrough FW; Houser OW; Earnest F th; Scheithauer BW; Laws ER Jr 《Radiology》1986,160(1):215-219
Results of contrast material-enhanced computed tomography (CT) and T2-weighted spin-echo magnetic resonance (MR) imaging were correlated with pathologic findings in 25 patients treated surgically for refractory partial epilepsy. Of 12 lesions present, ten (83%) were detected by MR imaging and seven (58%) by CT scanning. Of nine low-grade gliomas, eight were detected by MR imaging and four by CT scanning. One posttraumatic scar and one case of temporal lobe atrophy were better demonstrated by MR imaging. A small, thrombosed arteriovenous malformation was the only lesion detected by CT scanning but not by MR imaging. No lesions were detected in 13 patients with mild gliosis and one patient with a 1.2-cm grade 1 astrocytoma. Although more sensitive than CT for detection of structural lesions in patients with refractory partial epilepsy, MR imaging resulted in a 25% false-negative diagnostic rate when a repetition time of 2,000 msec and echo time of 60 msec were used. Multi-echo imaging with at least one long echo time may be needed to increase the sensitivity of MR imaging in these patients. 相似文献
36.
体外培养的肝细胞有多种临床用途〔1〕。其中将肝细胞置入特殊的生物反应器,构建生物人工肝(bioartificialliver,BAL)支持系统有重要的临床价值。有研究报道,细胞聚集成多细胞的球体(spheriod)更类似于体内条件;并且可在有限的容积内高密度地培养肝细胞〔2〕。因此,我们实验构建人、猪肝细胞球体,并比较肝细胞普通培养与球体培养蛋白分泌功能的变化。1.材料和方法:试剂:Dubecco′s磷酸盐缓冲液;Hank′s平衡盐;ITS(胰岛素,运铁蛋白和硒,insulin,transfer… 相似文献
37.
Fay JW; Lazarus H; Herzig R; Saez R; Stevens DA; Collins RH Jr; Pineiro LA; Cooper BW; DiCesare J; Campion M 《Blood》1994,84(7):2151-2157
Preclinical studies of recombinant human interleukin-3 (rhIL-3) and granulocyte-macrophage colony-stimulating factor (rhGM-CSF) have shown enhancement of multilineage hematopoiesis when administered sequentially. This study was designed to evaluate the safety, tolerability, and biologic effects of sequential administration of rhIL- 3 and rhGM-CSF after marrow ablative cytotoxic therapy and autologous bone marrow transplantation (ABMT) for patients with malignant lymphoma. Thirty-seven patients (20 patients with non-Hodgkin's lymphoma and 17 patients with Hodgkin's disease) received one of four different treatment regimens before ABMT. Patients were entered in one of four study groups to receive rhIL-3 (2.5 or 5.0 micrograms/kg/day) administered by subcutaneous injection for either 5 or 10 days starting 4 hours after the marrow infusion. Twenty-four hours after the last dose of rhIL-3, rhGM-CSF (250 micrograms/m2/d as a 2-hour intravenous infusion) administration was initiated. rhGM-CSF was administered daily until the absolute neutrophil count (ANC) was > or = 1,500/microL for 3 consecutive days or until day 27 posttransplant. The most frequent adverse events in the trial included nausea, fever, diarrhea, mucositis, vomiting, rash, edema, chills, abdominal pain, and tachycardia. Three patients were removed from the study because of chest, skeletal, and abdominal pain felt to be probably related to study drug. Four patients died during the study period because of complications unrelated to either rhIL-3 or rhGM-CSF. The median time to recovery of neutrophils (ANC > or = 500/microL) and platelets (platelet count > or = 20,000/microL) was 14 and 15 days, respectively. There were fewer days of platelet transfusions than seen in historical control groups using rhGM-CSF, rhG-CSF, or rhIL-3 alone. In addition, there were fewer days of red blood cell transfusions compared with historical controls using no cytokines or rhGM-CSF. These data indicate that the sequential administration of rhIL-3 and rhGM-CSF after ABMT is safe and generally well-tolerated and results in rapid recovery of multilineage hematopoiesis. 相似文献
38.
39.
Rennick DM; Thompson-Snipes L; Coffman RL; Seymour BW; Jackson JD; Hudak S 《Blood》1990,76(2):312-316
Bone marrow of mice parasitized with Nippostrongylus brasiliensis showed increased numbers of eosinophils as early as 4 days after infection. By day 7, their bone marrow also contained elevated numbers of progenitors that form small eosinophil colonies (20 to 50 cells) in soft agar cultures supplemented with interleukin-5 (IL-5). However, when mice were infused with anti-IL-5 antibodies at the time of infection, the number of recognizable eosinophils present in bone marrow remained low and eventually dropped below normal levels. The antibody treatment also prevented increased generation of IL-5- responsive precursors capable of differentiating into mature eosinophils in liquid culture and inhibited the generation of progenitor cells capable of forming small eosinophil colonies or clusters in soft agar cultures. The results of these in vivo experiments directly show that IL-5 is an essential regulatory molecule required for the bone marrow-dependent phase of a parasite-induced eosinophilia. 相似文献
40.
Long-term leukemia-initiating capacity of a CD34-subpopulation of acute myeloid leukemia 总被引:2,自引:1,他引:2
Terpstra W; Prins A; Ploemacher RE; Wognum BW; Wagemaker G; Lowenberg B; Wielenga JJ 《Blood》1996,87(6):2187-2194
Acute myeloid leukemia (AML) proliferation in vivo is maintained by a small fraction of progenitor cells. These cells have been assumed to express an immature phenotype and to produce most colony-forming units (CFU-AML). For one case of AML (French-American-British [FAB] M1, normal cytogenetics), we examined the capacity of the CD34+ (25% of unseparated AML cells) and CD34- fractions to initiate leukemia in severe combined immunodeficient (SCID) mice. In addition, the production of CFU-AML and nucleated cells (NC) of these subsets was investigated in long-term bone marrow culture (LTBMC). The frequencies of cobblestone area-forming cells (CAFC) were also estimated; early appearing cobblestone areas (CAs) are indicative of relatively mature progenitors and late CAs represent the progeny of primitive progenitors. In mice transplanted with CD34- (98% pure) or CD34+ (98% pure) grafts, similar AML cell growth was seen throughout an observation period of 106 days. The capacity to establish long-term growth from the CD34- cells was confirmed by renewed outgrowth after retransplantation. In vitro, the CD34- fraction contained both immature and mature CAFCs and produced high numbers of CFU-AML and NC in LTBMC. The CD34+ fraction produced only small numbers of CFU-AML, NC, and mature CAFCs. Therefore, the expression of CD34 and the content of CFU- AML were not associated with long-term growth of AML. However, similar frequencies of primitive CAFCs were observed in both fractions. Thus, both CD34- and CD34+ subsets of this AML sample contained immature progenitors with the capacity to initiate long-term AML growth as characterized in vivo (in SCID mice) as well as in vitro (in CAFC assay), indicating asynchrony between functional and immunophenotypical maturation of AML progenitor cell compartments. 相似文献