表面粗糙度对牙科银汞合金抗折力的影响

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．     

妥卡尼对豚鼠心室肌细胞钙电流和钾电流的抑制作用

利用酶分散的成年豚鼠心室肌细胞和全细胞电压钳技术,研究了妥卡尼(tocainide)对心室肌细胞钙电流(I_ca)、延迟整流钾电流(I_k)和ATP敏感性钾电流(Ik,ATP)的作用。结果表明,妥卡尼对I_ca和I_k均显示浓度相关的抑制作用,妥卡尼50umol·L^-1对I_ca和I_k的抑制率分别为16%和3%。这可能是妥卡尼有效抑制室上性心动过速和缩短心肌动作电位平台期的重要机制。     

Interleukin-6 is not involved in the interleukin-1-induced production of colony-stimulating factors by human bone marrow stromal cells and fibroblasts

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.     

Cryptic structural lesions in refractory partial epilepsy: MR imaging and CT studies

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.     

Sequential administration of recombinant human interleukin-3 and granulocyte-macrophage colony-stimulating factor after autologous bone marrow transplantation for malignant lymphoma: a phase I/II multicenter study

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.     

In vivo administration of antibody to interleukin-5 inhibits increased generation of eosinophils and their progenitors in bone marrow of parasitized mice

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.     

Long-term leukemia-initiating capacity of a CD34-subpopulation of acute myeloid leukemia

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.     

High levels of T lymphocyte activation in Leishmania-HIV-1 co-infected individuals despite low HIV viral load

Background

Anti-viral prophylaxis is used to prevent the transmission of influenza. We studied serological confirmation of 2009 Influenza A (H1N1) infections during oseltamivir prophylaxis and after cessation of prophylaxis.

Methods

Between 22 Jun and 16 Jul 09, we performed a cohort study in 3 outbreaks in the Singapore military where post-exposure oseltamivir ring chemoprophylaxis (75 mg daily for 10 days) was administered. The entire cohort was screened by RT-PCR (with HA gene primers) using nasopharyngeal swabs three times a week. Three blood samples were taken for haemagglutination inhibition testing - at the start of outbreak, 2 weeks after completion of 10 day oseltamivir prophylaxis, and 3 weeks after the pandemic's peak in Singapore. Questionnaires were also administered to collect clinical symptoms.

Results

237 personnel were included for analysis. The overall infection rate of 2009 Influenza A (H1N1) during the three outbreaks was 11.4% (27/237). This included 11 index cases and 16 personnel (7.1%) who developed four-fold or higher rise in antibody titres during oseltamivir prophylaxis. Of these 16 personnel, 8 (3.5%) were symptomatic while the remaining 8 personnel (3.5%) were asymptomatic and tested negative on PCR. Post-cessation of prophylaxis, an additional 23 (12.1%) seroconverted. There was no significant difference in mean fold-rise in GMT between those who seroconverted during and post-prophylaxis (11.3 vs 11.7, p = 0.888). No allergic, neuropsychiatric or other severe side-effects were noted.

Conclusions

Post-exposure oseltamivir prophylaxis reduced the rate of infection during outbreaks, and did not substantially increase subsequent infection rates upon cessation. Asymptomatic infections occur during prophylaxis, which may confer protection against future infection. Post-exposure prophylaxis is effective as a measure in mitigating pandemic influenza outbreaks.