Streptococcal pyrogenic exotoxin B cleaves human S-adenosylhomocysteine hydrolase and induces hypermethioninemia

Group A Streptococcus is a common pathogen that causes pharyngitis, impetigo, myositis, and lethal streptococcal toxic shock syndrome. Streptococcal pyrogenic exotoxin B (SPE B) is strongly associated with the severity of disease. SPE B is a cysteine protease and matures itself by autocatalysis. We found that SPE B was directly associated with human S-adenosylhomocysteine hydrolase (AdoHcyase), an essential factor for a delayed-type immune response. AdoHcyase protein levels and enzymatic activities were significantly higher in human cells infected with the Streptococcus pyogenes SW510 speB mutant strain than in cells infected with the NZ131 wild-type strain. SPE B also inactivated AdoHcyase, shown by a decrease in homocysteine, the main product of AdoHcyase. We found that in vivo and in vitro, SPE B induced hypermethioninemia, which is caused by an AdoHcyase defect. We also found that AdoHcyase is a substrate of SPE B cysteine protease. SPE B, therefore, potentially causes immunosuppression by cleaving AdoHcyase.     

肠缺血再灌注大鼠肺及血液白细胞介素6、白细胞介素8和肿瘤坏死因子α变化与辅酶Q10的干预

目的:观察大鼠肠缺血再灌注时肺及血液白细胞介素6、白细胞介素8和肿瘤坏死因子α的变化以及辅酶Q10的影响。方法:实验于2006-12/2007-02在滨州医学院药理学实验室和免疫学实验室(山东省重点学科三级实验室)完成。①实验分组:清洁级健康Wistar大鼠30只,体质量290～390g,随机数字表法分为假手术组、肠缺血再灌注组,辅酶Q10处理组(缺血再灌注 辅酶Q10),每组10只。②实验方法:建立肠缺血再灌注模型,钝性分离肠系膜上动脉的根部,假手术组不作其他处理;肠缺血再灌注组再灌前30min时经股静脉注入生理盐水10mL/kg;辅酶Q10处理组再灌前30min时经股静脉注入辅酶Q1010mg/kg。③实验评估:酶联免疫吸附法(ELISA)检测各组动物血液、肺组织匀浆及肺泡灌洗液中的白细胞介素6、白细胞介素8和肿瘤坏死因子α含量;光镜下观察肺组织形态学变化。肺泡灌洗液沉渣进行白细胞计数和分类。结果:纳入大鼠30只,均进入结果分析。①肺组织形态学变化:假手术组肺组织无病理改变;肠缺血再灌注组肺间质明显水肿,中性粒细胞浸润,有少量的出血和纤维蛋白渗出;辅酶Q10处理组肺间质轻度水肿,少量的中性粒细胞。②肺泡灌洗液白细胞计数组间无显著性差异,多形核细胞分类肠缺血再灌注组明显高于假手术组(P<0.05),而辅酶Q10处理组与其他两组间差异无显著性意义(P>0.05)。③各组动物血液、肺组织匀浆及肺泡灌洗液中的白细胞介素6、白细胞介素8和肿瘤坏死因子α含量:与假手术组比较,肠缺血再灌注组血液、肺组织匀浆及肺泡灌洗液中白细胞介素6、白细胞介素8和肿瘤坏死因子α显著升高(P<0.05或P<0.01)。与肠缺血再灌注组比较,辅酶Q10处理组血液、肺组织匀浆和肺泡灌洗液中白细胞介素6含量显著降低(P<0.05);白细胞介素8和肿瘤坏死因子α含量在血液中显著降低(P<0.05);而在肺组织匀浆中含量未见显著降低(P>0.05);在肺泡灌洗液中含量亦未见显著降低(P>0.05)。结论:辅酶Q10可能通过抑制白细胞介素6、白细胞介素8和肿瘤坏死因子α炎性因子的释放,对大鼠肠缺血再灌后肺损伤有一定的保护作用。     

足球运动过程中择时补充糖与乳清蛋白对体能的影响

目的:已有证实,在足球运动中根据人体生物节律特点,选择适宜的时间补充营养,提高机体体能,获得最佳效益.实验拟进一步验证择时补充低聚糖与乳清蛋白(4:1)饮料对大学生足球运动员体能的影响.方法:试验于2006-05/08在湛江师范学院完成.选择湛江师范学院业余男子足球队队员16名,集中足球训练年限为二三年.详细告知所有受试者参与本试验的目的、实施过程、要求与注意事项,并获得受试者同意与配合.①试验分组:将16名队员随机分为试验组和对照组,每组8名.两组年龄、身高、体质量差异均无显著性.②试验方法:在备战2006年广东省第7届大学生运动会期间,两组运动员每天均完成相同的训练计划,训练6次/周,3h/次.训练期间,采用单盲法试验组每天训练前、后1 h内共补充“低聚糖 乳清蛋白“(4:1)饮料800 mL(含乳清蛋白25 g),并在训练日临睡前补充乳清蛋白25 g;对照组则补充相同颜色、气味的纯净水,临睡前不补充任何能量营养素,服用时间与试验组一致,试验时间为12个周.③试验评估:两组运动员均于试验前后分别在800-Ergometer功率自行车进行最大摄氧量、无氧能力及身体素质指标的测试.结果:纳入业余男子足球队队员16名,均进入结果分析.①试验前后试验组和对照组最大吸氧量值分别提高了6.18%(P＞0.05)和11.09%(P＜0.05);运动后心率的恢复在恢复期第3分钟和第5分钟差异出现显著性(P＜0.05),而且,试验组运动员的心率在递增负荷运动后恢复较快.②对照组和试验组无氧功最大值在试验后分别增加12.19%(P＜0.05)和16.97%(P＜0.05),最大功率时间分别缩短5.81%(P＞0.05)和6.02%(P＞0.05);与对照组比较,试验组试验后最大无氧功率、平均功率值及最大无氧功率时间分别提高5.81%(P＜0.05)、5.06%(P＜0.05)和3.7%(P＞0.05).③试验前后对照组和试验组自身对比,除反应柔韧素质体前屈的测试结果无显著变化外,其他身体素质测试结果均有不同程度的提高.对照组5x25 m折返跑和12 min跑测试结果的变化有统计学意义(P＜0.05);试验组试验前后身体素质测试除I llmois灵敏测验、体前屈和变换跑的结果无统计学意义(P＞0.05)外,其他测试结果有显著性差异(P＜0.05).结论:择时联合补充低聚糖加乳清蛋白能提高足球运动过程中机体的无氧能力和有氧能力,并促进体能的恢复.     

Expression of human interleukin-3 (multi-CSF) is restricted to human lymphocytes and T-cell tumor lines

While the cellular sources for granulocyte-macrophage colony- stimulating factor (GM-CSF) are known to be widely distributed among several cell types, interleukin-3 (IL-3) gene expression has been demonstrated in only certain T-cell clones and in blood mononuclear cells stimulated with phytohemagglutinin (PHA) and phorbol-myristate- acetate (PMA). To determine which blood cells were responsible for this expression, we fractionated PHA/PMA-stimulated mononuclear cells and identified T lymphocytes as the source of IL-3 mRNA. Low-level IL-3 expression was detected as well in several stimulated human T-cell lines. Hematopoietic stromal cells such as fibroblasts and endothelial cells could not be induced to express IL-3 mRNA. The kinetics of IL-3 mRNA induction in mononuclear cells and lymphocytes stimulated with PHA/PMA or anti-CD3 monoclonal antibody (MoAb) and interleukin-1 (IL-1) were similar to those observed for GM-CSF expression.     

The effect of recombinant GM-CSF on the recovery of monkeys transplanted with autologous bone marrow

The regulatory function of recombinant human granulocyte-macrophage colony stimulating factor (rhGM-CSF) on granulocyte production in vivo was evaluated in an autologous bone marrow transplantation model using rhesus monkeys. Monkeys were exposed to 9.0 Gy total body irradiation and then transplanted with 5.0 x 10(7) low-density bone marrow cells/kg. Alzet miniosmotic pumps were subcutaneously implanted to deliver rhGM-CSF at a rate of 50,400 U/kg/d. Minipumps, containing either rhGM-CSF or saline, were implanted between zero and five days after transplantation for seven days. Kinetic recoveries of peripheral blood cells after either saline or rhGM-CSF treatment were compared. Treatment with rhGM-CSF accelerated the recovery of neutrophils. Neutrophils in rhGM-CSF-treated animals recovered to 80% (3.4 x 10(3)/mm3) pre-irradiation control levels by day 20, in comparison with only 33% (0.9 x 10(3)/mm3) recovery for saline control monkeys. In addition, the recovery of neutrophils was enhanced over that of the controls, reaching 140% v 70% on day 30. Another prominent feature of rhGM-CSF-treated monkeys was the accelerated recovery of platelets, reaching near 50% normal levels by day 24 in comparison with 20% of normal levels for controls. The infusion of rhGM-CSF was shown to be an effective regulator of early hematopoietic regeneration, leading to the accelerated recovery of both neutrophils and platelets and then providing a consistent sustained increase of neutrophils even in the absence of rhGM-CSF.     

Host origin of the human hematopoietic microenvironment following allogeneic bone marrow transplantation

The origin of marrow stromal cells post allogeneic bone marrow transplantation (BMT) was studied. Two groups of patients receiving HLA- identical marrow grafts from sex mismatched siblings were included in the study: the first group (eight patients) received conventional marrow grafts and the second group (ten patients) received stromal cell and T cell depleted grafts. All patients showed hematopoietic engraftment with donor cells. Marrow aspirates obtained from these patients were used to establish stromal layers in long-term marrow cultures (LTMC) for 4 to 6 weeks. In both groups, karyotype analysis of nonhematopoietic cultured stromal cells showed host origin even as late as day 760 posttransplantation. Immunofluorescence methods using monoclonal antibodies against components of fibroblasts, macrophages, and endothelial cells, showed that the composition of stromal layers was similar to those obtained from normal controls. Our data indicate that marrow stromal progenitors capable of proliferation are nontransplantable and do not originate from a hematopoietic-stromal common progenitor.     

Photoradiation models for the clinical ex vivo treatment of autologous bone marrow grafts

To assess the potential of photoradiation therapy for the in vitro purging of residual tumor cells from autologous bone marrow (BM) transplants, we studied normal marrow and tumor cell clonogenicity in response to different light-activated compounds by using the fluorescent dyes dihematoporphyrin ether (DHE) and merocyanine-540 (MC- 540). After photoradiation of cells with white light, both DHE and MC- 540 showed high cytocidal activity toward lymphoid and myeloid neoplastic cells but had a significantly lesser effect on normal granulocyte-macrophage (CFU-GM), erythroid (BFU-E), and mixed colony- forming (CFU-GEMM) progenitor cells. Acute promyelocytic leukemia (HL- 60), non-B, non-T, CALLA-positive acute lymphoblastic leukemia (Reh), and diffuse histocytic B cell lymphoma (SK-DHL-2) cell lines were exposed to different drug concentrations in combination with white light at a constant illumination rate of 50,000 lux. With DHE doses varying from 2.0 to 2.5 micrograms/mL and MC-540 concentrations of 15 to 20 micrograms/mL, clonogenic tumor cells could be reduced by more than 4 logs when treated alone or in mixtures with normal irradiated human marrow cells. However, preferential cytotoxicity towards neoplastic cells was highly dependent on the mode of light activation. MC-540 had no substantial effect on malignant lymphoid (SK-DHL-2) and myeloid (HL-60) cells and on normal marrow myeloid (CFU-GM) precursors when drug incubation was performed in the dark and followed by light exposure of washed cells. Equal doses of MC-540 (15 to 20 micrograms/mL) could preferentially eliminate tumor cells under conditions of simultaneous light and drug treatment (30 minutes at 37 degrees C). When using DHE (2.5 micrograms/mL), 29.3%, 46.8%, and 27.5% of normal marrow CFU-GM, BFU-E, and CFU-GEMM, respectively, were spared after sequential drug and light exposure of cells, whereas simultaneous treatment reduced both normal (CFU-GM) and neoplastic cells below the limits of detection. In summary, our results indicate the usefulness of various photoradiation models for the ex vivo treatment of leukemic and lymphomatous bone marrow autografts.     

Frequent deletion of p16INK4a/MTS1 and p15INK4b/MTS2 in pediatric acute lymphoblastic leukemia

The tandemly linked p16INK4aMTS1 and p15INK4b/MTS2 genes on chromosome 9, band p21 encode proteins that function as specific inhibitors of the cyclin D-dependent kinases CDK4 and CDK6. This locus undergoes frequent bi-allelic deletion in human cancer cell lines, suggesting that the encoded proteins may function as tumor suppressors. However, more recent analysis of primary tumor samples has shown a much lower frequency of abnormalities affecting this region, raising doubt over the importance of these proteins in human malignancies. Hemizygous deletions and rearrangements of chromosome 9, band p21, are among the most frequent cytogenetic abnormalities detected in pediatric acute lymphoblastic leukemia (ALL), occurring in approximately 10% of cases. To determine if the p16INK4a/p15INK4b locus might be the target of these chromosomal lesions, we analyzed both genes in primary clinical samples from 43 pediatric ALL patients using interphase fluorescence in situ hybridization, Southern blot analysis, and the polymerase chain reaction. Deletions of p16INK4a/p15INK4b were identified in 18 of 20 cases with cytogenetically observed abnormalities of 9p and 5 of 23 with apparently normal chromosomes 9p, with the majority containing bi- allelic deletions (16 homozygous/7 hemizygous). Although most homozygous deletions involved both genes, Southern blot analysis showed an interstitial deletion in a single case that was confined to p16INK4a, suggesting that p15INK4b was not the critical target gene in this case. Sequence analysis of both p16INK4a and p15INK4b in all seven cases with hemizygous deletions failed to show mutations within the coding regions of the retained alleles. In this select group of patients, deletion of p16INK4a/p15INK4b was associated with T-cell phenotype, nonhyperdiploid karyotype (< 50 chromosomes), and poor event- free survival. These findings indicate that deletion of the p16INK4a/p15INK4b locus is one of the most common genetic abnormalities so far detected in pediatric ALL, and that loss of one or more of these cell cycle kinase inhibitors is important in leukemogenesis.     

Immunolocalization of beta 1 integrins in platelets and platelet- derived microvesicles

Human platelets contain several adhesion receptors belonging to the integrin superfamily. At least three beta 1 integrins are present on platelets and have been shown to mediate platelet adhesion to collagen, fibronectin, and laminin. To study the cellular localization of the beta 1 integrins in platelets, we produced a polyclonal antibody by immunization of goat 172 with purified beta 1 subunit from HPB-ALL cells. Antibody 172 (Ab172) specifically immunoblotted a 135-Kd protein in a lysate of whole platelets. The reactivity of Ab172 with platelet membrane proteins was further determined by immunoprecipitation of lysates of surface-radioiodinated platelets. Ab172 immunoprecipitates, resolved by nonreducing/reducing two-dimensional sodium dodecyl sulfate- polyacrylamide gel electrophoresis consisted of three labeled proteins with migrational properties of platelet glycoprotein (GP)Ia, GPIc and GPIIa. Neither GPIIb/IIIa nor the vitronectin receptor were immunoprecipitated by Ab172, confirming a lack of cross-reactivity with the beta 3 integrins in platelets. Immunofluorescence studies using Ab172 were performed to investigate the cellular distribution of beta 1 integrins in platelets. Fluorescent labeling of intact cells demonstrated the presence of beta 1 antigen on the surface of resting cells. Permeabilization of platelets with Triton X-100 showed the presence of an intracellular pool of beta 1 antigen. Double-label experiments using Ab172 and AP-2 (anti-GPIIb/IIIa) showed identical labeling patterns, suggesting a similar subcellular distribution for these integrins. Following thrombin stimulation, permeabilized cells showed a centralized clearing of both beta 1 antigen and GPIIb/IIIa as well as an intensification of surface labeling for beta 1 antigen. These findings suggest the translocation of intracellular beta 1 antigen to the platelet surface as a result of thrombin stimulation. Because platelet-derived microvesicles have been reported to contain GPIIb/IIIa, we investigated the possible distribution of beta 1 integrins in these structures. Microvesicles, produced as a result of platelet activation, were labeled with Ab172, suggesting the distribution of beta 1 integrins in these structures as well as in intact cells.