Significance of dietary folate intake,homocysteine levels and MTHFR 677 C>T genotyping in South African patients diagnosed with depression: test development for clinical application

Low folate intake in the presence of the functional MTHFR 677 C > T (rs1801133) polymorphism is an important cause of elevated homocysteine levels previously implicated in major depressive disorder (MDD) and many other chronic diseases. In this study the clinical relevance and inter-relationship of these aspects were evaluated in 86 South African patients diagnosed with MDD and 97 population-matched controls participating in a chronic diseases screening program. A questionnaire-based clinical and nutrition assessment was performed, homocysteine levels determined, and all study participants genotyped for MTHFR 677 C > T (rs1801133) using allele-specific TaqMan technology. The folate score was found to be significantly lower in the patient group compared to controls (p?=?0.003) and correlated with increased body mass index (BMI), particularly in females with MDD (p?=?0.009). BMI was significantly higher in the MDD patients compared with controls after adjustment for age and sex (p?=?0.015), but this association was no longer significant after further adjustment for the level of folate intake in the diet. In MDD patients but not controls, the minor T-allele of MTHFR 677 C > T was associated with increased BMI (p?=?0.032), which in turn correlated significantly with increased homocysteine levels. The significant association between BMI and homocysteine levels was observed in both the MDD patient (p?=?0.049) and control (p?=?0.018) study groups. The significantly higher homocysteine levels observed in MDD patients compared to controls after adjustment for age and sex (p?=?0.030), therefore appears to be mediated by the effects of MTHFR 677 C > T and low folate intake on BMI. Detection of the low-penetrance MTHFR 677 C > T mutation reinforces the importance of folate intake above the recommended daily dose to prevent or restore dysfunction of the methylation pathway.     

人脂肪干细胞复合脱细胞软骨基质支架在生物反应器中构建组织工程软骨

目的:观察人脂肪干细胞复合脱细胞软骨基质支架在生物反应器中初步构建组织工程软骨的可行性。方法:实验于2005-04/2006-05在解放军总医院骨科研究所完成。脂肪组织和关节软骨均来自膝关节置换术中切除的组织,并经患者知情同意。关节软骨冻干后经粉碎机粉碎,过筛,选取25～38μm大小的软骨微粒。在样品中先加入2.5g/L胰蛋白酶,37℃消化24h,再加入1%Triton X-100震荡72h。将软骨微粒和蒸馏水按1∶3的比例混合后滴加在模板中,置入冷冻干燥机冻干后行紫外线交联。紫外线照射8h完成。最后经25kGy 60Co辐照灭菌完成支架制备。取膝关节置换术中切除的髌下脂肪垫,酶消法获得脂肪干细胞,扩增后复合于脱细胞软骨基质制成圆柱状三维支架上(细胞密度5×1010L-1),置于生物反应器中进行诱导培养,同时设静态培养组作为对照,3周后观测大体形态和组织学形态变化,同时进行组织化学(包括番红花O,阿利新蓝染色)和Ⅱ型胶原免疫组织化学分析。结果:生物反应器组诱导培养3周苏木精-伊红染色显示支架结构消失,只有中心区域残存少量支架结构;静态培养组支架结构尚存在,有少量基质分泌。番红花O染色显示生物反应器组细胞外有大量蛋白聚糖沉积,阿利新蓝染色表明有软骨特异性蛋白多糖的聚集;而静态培养组只有部分区域染色且淡于生物反应器组。Ⅰ型胶原免疫组化的结果显示,在生物反应器组细胞能够合成大量软骨细胞特异性胶原成分,而静态培养组呈弱阳性。结论:生物反应器培养明显促进了脂肪干细胞的增殖与软骨分化,是体外构建组织工程软骨的良好方法。     

Aven‐mediated checkpoint kinase control regulates proliferation and resistance to chemotherapy in conventional osteosarcoma

Conventional high‐grade osteosarcoma is the most common primary bone sarcoma, with relatively high incidence in young people. In this study we found that expression of Aven correlates inversely with metastasis‐free survival in osteosarcoma patients and is increased in metastases compared to primary tumours. Aven is an adaptor protein that has been implicated in anti‐apoptotic signalling and serves as an oncoprotein in acute lymphoblastic leukaemia. In osteosarcoma cells, silencing Aven triggered G₂ cell‐cycle arrest; Chk1 protein levels were attenuated and ATR–Chk1 DNA damage response signalling in response to chemotherapy was abolished in Aven‐depleted osteosarcoma cells, while ATM, Chk2 and p53 activation remained intact. Osteosarcoma is notoriously difficult to treat with standard chemotherapy, and we examined whether pharmacological inhibition of the Aven‐controlled ATR–Chk1 response could sensitize osteosarcoma cells to genotoxic compounds. Indeed, pharmacological inhibitors targeting Chk1/Chk2 or those selective for Chk1 synergized with standard chemotherapy in 2D cultures. Likewise, in 3D extracellular matrix‐embedded cultures, Chk1 inhibition led to effective sensitization to chemotherapy. Together, these findings implicate Aven in ATR–Chk1 signalling and point towards Chk1 inhibition as a strategy to sensitize human osteosarcomas to chemotherapy. Copyright © 2015 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Human naive and memory CD4+ T cell repertoires specific for naturally processed antigens analyzed using libraries of amplified T cells

The enormous diversity of the naive T cell repertoire is instrumental in generating an immune response to virtually any foreign antigen that can be processed into peptides that bind to MHC molecules. The low frequency of antigen-specific naive T cells, their high activation threshold, and the constrains of antigen-processing and presentation have hampered analysis of naive repertoires to complex protein antigens. In this study, libraries of polyclonally expanded naive T cells were used to determine frequency and antigen dose–response of human naive CD4⁺ T cells specific for a variety of antigens and to isolate antigen-specific T cell clones. In the naive repertoire, T cells specific for primary antigens, such as KLH and Bacillus anthracis protective antigen, and for recall antigens, such as tetanus toxoid, cytomegalovirus, and Mycobacterium tuberculosis purified protein derivative, were detected at frequencies ranging from 5 to 170 cells per 10⁶ naive T cells. Antigen concentrations required for half-maximal response (EC50) varied over several orders of magnitude for different naive T cells. In contrast, in the memory repertoire, T cells specific for primary antigens were not detected, whereas T cells specific for recall antigens were detected at high frequencies and displayed EC50 values in the low range of antigen concentrations. The method described may find applications for evaluation of vaccine candidates, for testing antigenicity of therapeutic proteins, drugs, and chemicals, and for generation of antigen-specific T cell clones for adoptive cellular immunotherapy.The naive T cell repertoire is extraordinarily diverse because it contains an enormous number of distinct T cell clones, each represented by only a few cells (Goldrath and Bevan, 1999). Upon antigenic stimulation in secondary lymphoid organs, rare antigen-specific naive T cells undergo clonal expansion and differentiate to effector and memory cells (Jenkins et al., 2001; Kaech and Ahmed, 2001; Sallusto et al., 2004). Thus, the memory T cell repertoire contains a collection of expanded T cell clones that reflect the antigenic experience of the individual. Molecular studies indeed established that the TCR diversity is at least 100-fold lower in the memory compared with the naive repertoire (Arstila et al., 1999).The identification and characterization of antigen-specific T cells in the naive repertoire is of fundamental relevance to understanding the process of clonal selection and of practical relevance to predicting the immunogenicity of vaccines and therapeutic proteins. Human peptide-specific CD8⁺ T cells can be directly identified using soluble peptide/MHC class I tetramers (Altman et al., 1996). However, because of the low frequency of naive T cell precursors, this method can be successfully used only in special cases when the frequency is exceptionally high, such as for a Melan-A/MART-1 peptide bound to HLA-A2 (Pittet et al., 1999; Dunbar et al., 2000). Several laboratories have also developed human MHC class II multimers to detect peptide-specific memory CD4⁺ T cells (Novak et al., 1999; Meyer et al., 2000; Cameron et al., 2002; Lemaitre et al., 2004; Moro et al., 2005), but no data are yet available as to whether these multimers can be used to identify naive CD4⁺ T cells. More recently, a method based on MHC tetramers followed by magnetic bead enrichment was used to identify antigen-specific CD4⁺ and CD8⁺ T cells in naive mice (Hataye et al., 2006; Moon et al., 2007; Obar et al., 2008). Using this method, it has been estimated that the frequency of CD4⁺ T cells specific for epitopes within ovalbumin, I-E α chain, or Salmonella typhimurium varies from 20 to 200 cells per mouse, whereas the frequency of CD8⁺ T cells specific for ovalbumin or viral peptides varies from 80 to 1,200 cells per mouse. These figures are consistent with those previously estimated using an indirect method based on adoptive transfer of TCR transgenic T cells (McHeyzer-Williams and Davis, 1995; Butz and Bevan, 1998; Blattman et al., 2002; Stetson et al., 2002; Whitmire et al., 2006).In spite of several advantages, the MHC multimer technology is not generally applicable in view of the large numbers of MHC alleles and of the requirement of an a priori knowledge of the peptide sequence. In addition, MHC tetramers can assess only one epitope at a time and may identify cells that bind, but do not recognize, the naturally processed antigen. An alternative approach is to prime naive T cells in vitro using antigen-pulsed DCs. Using this method, it has been shown that antigen-specific CD8⁺ T cells can be isolated after consecutive rounds of in vitro antigenic stimulation and enrichments (Ho et al., 2006; Wolfl et al., 2007). However, because of the extensive in vitro selection, this method is not suitable to study the human naive repertoire.With the aim of developing a method to study the human naive T cell repertoire, we set up a novel in vitro T cell assay that is based on the screening of libraries of polyclonally expanded naive CD4⁺ T cells. The assay was used to determine frequency, antigen dose–response, and epitope specificity of human naive CD4⁺ T cells specific for a variety of antigens, to isolate representative T cell clones from the naive CD4⁺ repertoire, and to compare antigen-specific T cells in the naive and memory T cell compartments.     

败血症病人死亡危险性预评估方法的探讨

目的:探索可早期预测严重败血症病人死亡的临床和实验室指标或系统模型。方法:对ICU连续收治的26例严重败血症病人行前瞻性观察28天,分析其死亡的相关临床和实验室指标。结果:共有14人(54％)死亡,多死于第1周内(74％)。根据循环中的细胞间粘附分子-1水平能早期预测其脏器衰竭和死亡。一些临床指标水平在死亡病人与生存病人之间差别较大,其中包括血总胆红素、pH值、红细胞压积、氧合指数、动静脉血氧差、四项SIRS指标和一些血流动力学指标等。结论:综合上述指标可以尝试建立起了一个能够早期评估病人死亡可能性的积分系统。     

耐一线药物及注射药物对耐多药结核病治疗效果的影响

背景和目的:最近的研究结果表明,对其他一线药物和注射类药物(如卡那霉素、卷曲霉素)等耐药是影响耐多药结核病(MDR-TB)患者治疗效果的独立危险因素.本研究旨在明确耐其他一线药物和注射类药物对韩国不合并人免疫缺陷病毒(HIV)感染的MDR-TB患者临床疗效的影响.方法:采用回顾性队列研究分析1996年1月至2005年12月首尔国家大学附属医院治疗的211例MDR-TB患者治疗效果,排除7例丢失和7例迁出,对197例患者进行了最终分析.     

Activity of guard cell anion channel SLAC1 is controlled by drought-stress signaling kinase-phosphatase pair

In response to drought stress the phytohormone ABA (abscisic acid) induces stomatal closure and, therein, activates guard cell anion channels in a calcium-dependent as well as-independent manner. Two key components of the ABA signaling pathway are the protein kinase OST1 (open stomata 1) and the protein phosphatase ABI1 (ABA insensitive 1). The recently identified guard cell anion channel SLAC1 appeared to be the key ion channel in this signaling pathway but remained electrically silent when expressed heterologously. Using split YFP assays, we identified OST1 as an interaction partner of SLAC1 and ABI1. Upon coexpression of SLAC1 with OST1 in Xenopus oocytes, SLAC1-related anion currents appeared similar to those observed in guard cells. Integration of ABI1 into the SLAC1/OST1 complex, however, prevented SLAC1 activation. Our studies demonstrate that SLAC1 represents the slow, deactivating, weak voltage-dependent anion channel of guard cells controlled by phosphorylation/dephosphorylation.