Factors Contributing to Troponin Exchange in Myofibrils and in Solution

The troponin complex in a muscle fiber can be replaced with exogenous troponin by using a gentle exchange procedure in which the actin–tropomyosin complex is never devoid of a full complement of troponin (Brenner et al. (1999) Biophys J 77: 2677–2691). The mechanism of this exchange process and the factors that influence this exchange are poorly understood. In this study, the exchange process has now been examined in myofibrils and in solution. In myofibrils under rigor conditions, troponin exchange occurred preferentially in the region of overlap between actin and myosin when the free Ca²⁺ concentration was low. At higher concentrations of Ca²⁺, the exchange occurred uniformly along the actin. Ca²⁺ also accelerated troponin exchange in solution but the effect of S1 could not be confirmed in solution experiments. The rate of exchange in solution was insensitive to moderate changes in pH or ionic strength. Increasing the temperature resulted in a two-fold increase in rate with each 10°C increase in temperature. A sequential two step model of troponin binding to actin–tropomyosin could simulate the observed association and dissociation transients. In the absence of Ca²⁺ or rigor S1, the following rate constants could describe the binding process: k ₁ = 7.12 M^–1s^–1, k _–1 = 0.65 s^–1, k ₂ = 0.07 s^–1, k _–2 = 0.0014 s^–1. The slow rate of detachment of troponin from actin (k _–2) limits the rate of exchange in solution and most likely contributes to the slow rate of exchange in fibers.     

Protection by a taurine supplemented diet from lead-induced deficits of long-term potentiation/depotentiation in dentate gyrus of rats in vivo

Previous studies have demonstrated that synaptic plasticity, which includes long-term potentiation (LTP) and depotentiation (DP) in hippocampus, is important for learning and memory. The purpose of this study is to evaluate the effect of taurine via drinking water on the lead-induced impairments of LTP and DP in rat dentate gyrus (DG) in vivo. The experiments were carried out in four groups of rats (control, lead-exposed, control and lead-exposed with a taurine-supplement diet, respectively). The input-output (I/O) function, excitatory postsynaptic potential (EPSP) and population spike (PS) amplitude were measured in the DG area of adult rats (60-90 days) in response to stimulation applied to the lateral perforant path. The results show that: 1. chronic lead exposure impaired LTP/DP measured on both EPSP slope and PS amplitude in DG area of the hippocampus; 2. in control rats, taurine had no effect on LTP/DP; 3. the amplitudes of LTP/DP of lead-exposed group were significantly increased by applying taurine. These results suggest that dietary taurine supplement could protect rats from the lead-induced impairments of synaptic plasticity and might be a preventive medicine to cure the cognitive deficits induced by lead.     

体外免疫制备抗大肠癌循环抗原的单克隆抗体

用带结肠癌HRT-18细胞株的BALB/c(nu/nu)小鼠的血清,体处免疫BALB/c小鼠的脾细胞.再与Sp2/0细胞融合,经免疫荧光法在人结肠癌石蜡切片上筛选出一组抗结肠癌的单克隆抗体;A15-6,C13-11,H16-8。间接免疫酶法显示这组单抗对结肠癌的阳性率为69％-72％。免疫组化的特点为:癌巢分泌物及其接触的细胞膜顶端多为阳性反应,其他部位呈阴性反应。3抗体对其他类型的组织无反应。可见,这是一组针对血液循环中肿瘤相关抗原的单克隆抗体,有较好的器官特异性,可能有益于大肠癌的临床血清学检测。     

Genes of the LMP/TAP cluster are associated with the human autoimmune disease vitiligo

Genes within the class II region of the major histocompatibility complex (MHC), including genes involved in antigen processing and presentation, have been reported to be associated with several autoimmune diseases. We report here that the LMP/TAP gene region is significantly associated with vitiligo, a disorder in which biochemical defects and/or autoimmune destruction cause melanocyte loss and resulting skin depigmentation. Case/control analyses revealed genetic association of vitiligo in Caucasian patients with an early age of onset with the transporter associated with antigen processing-1 (TAP1) gene. A family-based association method revealed biased transmission of specific alleles from heterozygous parents to affected offspring for the TAP1 gene, as well as for the closely linked LMP2 and LMP7 genes encoding subunits of the immunoproteasome. No association with vitiligo was found for the MECL1 gene, which encodes a third immunoproteasome subunit and is unlinked to the MHC class II region. These results suggest a possible role for the MHC class I antigen processing and/or presentation pathway in the antimelanocyte autoimmune response involved in vitiligo pathogenesis.     

Composition of TCR-CD3 complex in human intestinal intraepithelial lymphocytes: lack of Fc{varepsilon}Rl{gamma} chain

Human intestinal intraepithelial lymphocytes (DEL) are a uniquepopulation of predominantly CD8ß⁺ TCRß⁺lymphocytes and, to a lesser extent, TCR⁺ lymphocytes that proliferatepoorly to anti-CD3 mitogenic signals but display significantcytolytic activity. Studies in mouse model systems have shownthat the chain of the high-CD3 affinity receptor for IgE (FcRl)may substitute for the chain in the TCR-CD3 complex of iIEL.This has suggested that the functional properties of these cellsmay be associated with an altered composition of the TCR-CD3complex. We therefore analyzed the TCR-CD3 complex of normalhuman iIEL. One-and two-dimensional non-reducing/reducing SDS-PAGEanalysis of CD3, CD3, CD3, and FcRr chain immunopreclpitatesof cell surface radiolabeled proteins with subunit-specificantibodies revealed a TCR-CD3 complex without associated FcRrchains. Thus, normal human NEL contain a TCR-CD3 complex thatconsists predominantly of , homodimers in association with theß TCR and CD3, and , similar to the majority of peripherallymphocytes. This indicates that the distinct properties ofhuman DEL are not associated with substitutions of the FcRlchain in the TCR-CD3 complex.     

腹腔镜结直肠癌手术中转开腹列线图预测模型的构建

目的分析腹腔镜结直肠癌手术发生中转开腹的危险因素,建立列线图预测模型指导临床决策,并分析其短期预后影响。方法收集2017年5月至2020年5月西安交通大学第一附属医院行腹腔镜手术的764例结直肠癌患者的病例资料,分为中转开腹组(60例)及腹腔镜组(704例)。采用Logistic回归分析中转开腹的独立危险因素,并用R语言构建中转开腹列线图预测模型。通过受试者工作特征曲线(ROC)下面积评估列线图预测模型效能。通过绘制校准图进行一致性检验。并比较两组患者术中及术后恢复情况。结果本研究共纳入患者764例,其中60例发生中转开腹,中转开腹率为7.9%(60/764)。肿瘤位置位于直肠[比值比(OR)=1.846,P<0.05)]、美国麻醉医生协会(ASA)评分Ⅲ、Ⅳ级(OR=2.381,P<0.05)、腹部手术史(OR=3.652,P<0.01)、肿瘤长径≥5 cm(OR=2.704,P<0.05)和体重指数(OR=1.109,P<0.05)是发生中转开腹的独立危险因素,上述数据差异均有统计学意义。成功构建列线图预测模型,模型ROC曲线下面积为0.794。校正曲线显示预测结果与实际结果有较好的重合度。中转开腹组手术时间高于腹腔镜组(210 min比190 min,Z=-2.670,P<0.05);中转开腹组出血量高于腹腔镜组(170 ml比120 ml,Z=-6.018,P<0.01);中转开腹组术后住院天数高于腹腔镜组(10 d比9 d,Z=-2.134,P<0.05)。中转开腹组肠梗阻发生率高于腹腔镜组[10.0%(6/60)比4.3%(15/704),χ²=4.055,P<0.05];伤口感染率高于腹腔镜组[15.0%(9/60)比4.7%(33/704),χ²=11.318,P<0.05],上述数据差异均有统计学意义。结论肿瘤位置位于直肠、ASA评分Ⅲ、Ⅳ级、腹部手术史、肿瘤长径≥5 cm和体重指数是腹腔镜结直肠癌手术发生中转开腹的独立危险因素,据此建立的预测模型具有可靠的预测能力。     

Novel glucose-lowering drugs for non-alcoholic fatty liver disease

BACKGROUNDThe efficacy of novel glucose-lowering drugs in treating non-alcoholic fatty liver disease (NAFLD) is unknown.AIMTo evaluate the efficacy of glucose-lowering drugs dipeptidyl peptidase-4 (DPP-4) inhibitors, glucagon-like peptide-1 receptor agonists (GLP-1 RAs), and sodium-glucose cotransporter 2 (SGLT2) inhibitors in treating NAFLD and to perform a comparison between these treatments.METHODSElectronic databases were systematically searched. The inclusion criteria were: Randomized controlled trials comparing DPP-4 inhibitors, GLP-1 RAs, or SGLT2 inhibitors against placebo or other active glucose-lowering drugs in NAFLD patients, with outcomes of changes in liver enzyme [alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST)] from baseline.RESULTSNineteen studies were finally included in this meta-analysis. Compared with placebo or other active glucose-lowering drug treatment, treatment with DPP-4 inhibitors, GLP-1 RAs, and SGLT2 inhibitors all led to a significant decrease in ALT change and AST change from baseline. The difference between the DPP-4 inhibitor and SGLT2 inhibitor groups in ALT change was significant in favor of DPP-4 inhibitor treatment (P < 0.05). The trends of reduction in magnetic resonance imaging proton density fat fraction and visceral fat area changes were also observed in all the novel glucose-lowering agent treatment groups.CONCLUSIONTreatment with DPP-4 inhibitors, GLP-1 RAs, and SGLT2 inhibitors resulted in improvements in serum ALT and AST levels and body fat composition, indicating a beneficial effect in improving liver injury and reducing liver fat in NAFLD patients.     

Liver transplantation: would it be the best and last chance of cure for hepatocellular carcinoma with major venous invasion?

BackgroundHepatocellular carcinoma (HCC) with portal vein tumour thrombus (PVTT) signifies advanced disease, whether LT confers any survival superiority over resection remains uncertain.MethodsA propensity score matched (PSM) analysis of liver transplantation (LT) and liver resection (LR) for HCC with PVTT was performed.ResultsA consecutive series of 88 patients who received either LT (10 DDLTs and 3 LDLTs) or LR (n=75) respectively were recruited. Before PSM, the LT group has a higher MELD score (17.3 vs. 7.8, P<0.001), lower serum AFP levels (96 vs. 2,164 ng/mL, P=0.017) and smaller tumour size (4 vs. 10 cm, P<0.001). The 5-year overall survival for LT and LR were 55.4% and 15.9% respectively (P=0.007). After matching for serum AFP levels and tumour size, 1-, 3- and 5-year overall survival for LT were 81 ng/mL, 3.9 cm, 80%, 70% and 70% and the corresponding rates for LR were 1,417 ng/mL, 5.3 cm, 51.8%, 19,6% and 9.8% (P value =0.12, 0.27 and 0.009 respectively).ConclusionsLT is associated with significantly better oncological outcomes in HCC patients with PVTT involving the lobar or segmental level. A modest expansion of selection criteria to include small HCC with segmental PVTT should be considered.     

环甲膜前部的测量及其临床意义

本文观测了40例成人尸体环甲膜前部的高度、上下宽度和血管分布：（1）环甲膜前部的高度和上、下宽度，男性分别为11．4±1.8mm、11．2±1．2mm和4．8±1．6mm；女性分别为9．6±1．7mm、9.9±1.9mm和3．7±1．1mm。男性各值均大于女性（P＜0．05）。（2）环甲动脉起自甲状腺上动脉前支，行至环甲膜前部上1／3者占94％。建议：（1）环甲膜切开术选用气管套管外径男性不应大于10mm，女性不应大于9mm；（2）横行切开环甲膜应在此膜的下份靠近环状软骨进行，以免损伤环甲动脉。     

侗族左交臂人群的掌纹分析

目的　对湖南侗族左扣手人群的掌纹分布特点进行研究 ,积累侗族群体遗传学与民族学资料。方法用油墨拓印法捺印手纹 ,放大镜下观察分析。结果侗族左交臂人的普通型及过渡Ⅱ型掌褶纹的百分率存在明显的性差 (p <0 0 1) ;TH/I1区及I3 区的真实花纹出现率在左右手之间存在明显差异 (p <0 0 5或p <0 0 1)。过渡Ⅰ型掌褶纹的百分率与对照组比较存在明显的差异 (p <0 0 5 )。结论湖南侗族左交臂人群的掌纹有其自身的特征