MTT比色法检测人肿瘤细胞辐射敏感性的体外研究

目的 探讨MTT比色法在人肿瘤细胞辐射敏感性检测中的价值.方法 用1、2、4和8 Gy的γ射线照射肝癌细胞(HepG2)、食管癌细胞(EC-9706)和乳腺癌细胞(MCF-7),观察存活分数(SF)和平均致死剂量(D0).结果 γ射线剂量为2、4、8 Gy时,HepG2 和EC-9706的SF均显著低于MCF-7(P＜0.05、＜0.01);D0值HepG2 (2.36 Gy)＜EC-9706(2.70 Gy)＜MCF-7(3.95 Gy).HepG2 辐射敏感性最高,MCF-7最低.结论 MTT法检测人肿瘤细胞辐射敏感性简便、快捷且准确性较高,对指导临床个体化放疗有重要作用.     

Myristoylation alone is sufficient for PKA catalytic subunits to associate with the plasma membrane to regulate neuronal functions

Myristoylation is a posttranslational modification that plays diverse functional roles in many protein species. The myristate moiety is considered insufficient for protein–membrane associations unless additional membrane-affinity motifs, such as a stretch of positively charged residues, are present. Here, we report that the electrically neutral N-terminal fragment of the protein kinase A catalytic subunit (PKA-C), in which myristoylation is the only functional motif, is sufficient for membrane association. This myristoylation can associate a fraction of PKA-C molecules or fluorescent proteins (FPs) to the plasma membrane in neuronal dendrites. The net neutral charge of the PKA-C N terminus is evolutionally conserved, even though its membrane affinity can be readily tuned by changing charges near the myristoylation site. The observed membrane association, while moderate, is sufficient to concentrate PKA activity at the membrane by nearly 20-fold and is required for PKA regulation of AMPA receptors at neuronal synapses. Our results indicate that myristoylation may be sufficient to drive functionally significant membrane association in the absence of canonical assisting motifs. This provides a revised conceptual base for the understanding of how myristoylation regulates protein functions.

Myristoylation is a major type of posttranslational modification that occurs at the N terminus of a myriad of proteins (1–4). Depending on the target, myristoylation can contribute to the structure, stability, protein–protein interactions, and subcellular localization of the modified proteins (2–4). In particular, myristoylation often facilitates protein association with the membrane. However, it is thought that, with an acyl chain of only 14 carbons, myristate confers insufficient energy for stable association of a protein with the membrane (5, 6). Subsequent studies have shown that a second membrane-affinity motif, such as a stretch of basic residues or a second lipid modification, is required for the membrane association of several myristoylated proteins (reviewed in refs. 2–4). When the second membrane-affinity motif is removed or neutralized, either physiologically or via mutagenesis, the membrane localization of the protein is disrupted. Thus, the canonical view is that myristoylation alone is not sufficient to provide a functionally significant association of a protein with the plasma membrane, even though myristoylation has been observed to be associated with reconstituted lipid bilayers (7).Myristoylation was first discovered in the catalytic subunit of protein kinase A (PKA) (1, 8), which is a primary mediator of the second messenger cAMP that plays diverse essential roles in nearly all organisms, from bacteria to humans. At rest, PKA is a tetrameric protein that consists of two regulatory subunits (PKA-Rs) and two catalytic subunits (PKA-Cs). PKA holoenzymes are anchored to specific subcellular locations via the binding of PKA-R with A-Kinase anchoring proteins (9–12). In the presence of cAMP, PKA-C is released from PKA-R and becomes an active kinase (8, 13–16).Despite being myristoylated, PKA-C is thought to function as a cytosolic protein because of its high solubility (14, 15). Consistently, a PKA-C mutant with disrupted myristoylation has been shown to support the phosphorylation of certain substrates and to maintain several PKA functions in heterologous cells (17). Structural studies found that the PKA-C myristoylation is folded into a hydrophobic pocket, and it was proposed that this myristoylation serves a structural role (18–20). This view has started to shift based on recent reports showing that activated PKA-C can associate with the membrane in a myristoylation-dependent manner (16, 21, 22), including in neurons. However, the extent to which PKA-C associates with the plasma membrane in living cells and its functional significance are not known. Furthermore, as discussed above, myristolyation-mediated membrane association is thought to require a second-membrane motif. The identity of this second membrane-affinity motif has not been determined. Therefore, we set out to address these questions.     

PPARα配体对泡沫细胞炎性介质分泌的影响

目的在证实泡沫细胞有过氧化物酶体增殖物激活受体α（PPARα）表达的基础上,探讨其配体对泡沫细胞炎性介质分泌的影响。方法体外诱导THP-1单核细胞分化为巨噬细胞,给予oxLDL进一步诱导其转变为泡沫细胞,应用RT-PCR检测PPARα基因表达;PPARα配体氯贝丁酯（50μmol/L）干预后用ELISA法测定泡沫细胞培养上清液中IL-6、TNF-α、MMP-2、MMP-9浓度,Gelatin Zymography测定MMPs活性。结果巨噬细胞转化为泡沫细胞后其PPARα基因表达无显著变化;氯贝丁酯可显著抑制泡沫细胞IL-6、TNF-α（P<0.05）、MMP-9（P<0.01）的分泌,抑制MMP-9的活性,对MMP-2的分泌和活性无影响。结论PPARα配体抑制致动脉粥样硬化炎性因子的分泌,减少基质金属蛋白酶的释放并抑制其活性,对防治粥样硬化有利。     

Angiotensin II type 1a receptor signals are involved in the progression of heart failure in MLP-deficient mice.

BACKGROUND: Angiotensin II (AT) is implicated in the development of cardiac remodeling, which leads to heart failure, and pharmacological inhibition of the AT type 1 (AT1) receptor has improved mortality and morbidity in patients of heart failure. The aim of this study was to elucidate the role of the AT1 receptor in disease progression in muscle LIM protein (MLP)-deficient mice, which are susceptible to heart failure because of defective function of mechanosensors in cardiomyocytes. METHOD AND RESULTS: Hearts from MLP knockout (MLPKO) mice and MLP-AT1a receptor double knockout (DKO) mice were analyzed. MLPKO hearts showed marked chamber dilatation with cardiac fibrosis and reactivation of the fetal gene program. All of these changes were significantly milder in the DKO hearts. Impaired left ventricular (LV) contractility and filling were alleviated in DKO hearts. However, the impaired relaxation and downregulated expression of sarcoplasmic reticulum calcium-ATPase 2 were unchanged in DKO hearts. CONCLUSIONS: The AT1a receptor is involved in progression of LV remodeling and deterioration of cardiac function in the hearts of MLPKO mice. These results suggest that blockade of the receptor is effective in preventing progression of heart failure in dilated cardiomyopathy.     

153例老年初治肺结核临床分析

目的　探讨老年初治肺结核诊治和管理措施。方法　对老年肺结核与青年肺结核进行比较分析。结果　 (1)老年肺结核比青年肺结核咯血、乏力、盗汗明显少 ;(2 )结核菌素试验阴性高 ,但两组痰结核菌阳性率差异不明显 (p>0 .0 5 )。(3)前者病灶≥3肺野者明显多 ,而空洞病变两组差异不显著 (p>0 .0 5 )。 (4) I组中三药、四药联合化疗近期 X线好转率、痰菌阴转率也差异不明显 (p>0 .0 5 )。结论　对老年肺结核治疗应选用个体化方案 ,三化方案仍是可取的。同时应重视合并症的治疗及加强管理     

急性冠状动脉综合征患者基质金属蛋白酶9基因多态性

目的 探讨基质金属蛋白酶9基因C1562T多态性与中国南方汉族人群冠心病的关系.方法 对经冠状动脉造影证实的急性冠状动脉综合征患者150例(急性冠状动脉综合征组)、稳定型心绞痛患者110例(稳定型心绞痛组)和同期冠状动脉造影阴性、排除冠心病诊断的患者70例(对照组)进行研究,采用酶联免疫吸附试验测定血浆基质金属蛋白酶9水平,采用聚合酶链反应-限制片长多态性技术分析基质金属蛋白酶9基因中C1562T基因多态性,比较各组的基因型和等位基因频率.结果 急性冠状动脉综合征组血浆基质金属蛋白酶9水平明显高于稳定型心绞痛组(P＜0.05)和对照组(P＜0.01),而稳定型心绞痛组与对照组比较,差异无统计学意义(P＞0.05).急性冠状动脉综合征组基质金属蛋白酶9基因CT、CT TT基因型频率以及T等位基因频率均高于对照组和稳定型心绞痛组(P＜0.05或0.01),稳定型心绞痛组与对照组各基因型和等位基因频率分布差异无统计学意义(P＞0.05).C1562T位点CT/TT基因型患者血浆基质金属蛋白酶9水平显著高于CC基因型患者(P＜0.01).结论 基质金属蛋白酶9基因C1562T多态性可能与中国南方汉族人群急性冠状动脉综合征有关,1562T等位基因是动脉粥样硬化斑块不稳定性的易感基因.     

胆道联合静脉超声造影在恶性梗阻性黄疸中的价值

目的:评价胆道联合静脉超声造影检查在恶性梗阻性黄疸治疗中的临床价值。方法:43例患者经增强CT或MRI诊断为恶性梗阻性黄疸,在手术前行经皮经肝胆管穿刺置管,并予以常规超声、静脉超声造影和胆道超声造影检查。以手术结果为金标准,分析常规超声、静脉超声造影、胆道超声造影、胆道联合静脉超声造影对恶性梗阻性黄疸的诊断符合率。结果:43例患者中,常规超声、静脉超声造影、胆道超声造影、胆道联合静脉超声造影的诊断符合率分别为72.1%(31/43)、83.7%(36/43)、81.4%(35/43)及93.0%(40/43)。其中胆道联合静脉超声造影的诊断符合率明显优于常规超声(P=0.021),而单独的静脉或胆道超声造影与常规超声之间的差异无统计学意义(P=0.194和0.307)。结论:胆道联合静脉超声造影可全面评估梗阻部位胆管的腔内和腔外的情况,提高超声对恶性梗阻性黄疸诊断符合率,有效判断手术的可切除性,具有较好的临床价值。     

A meta-analysis of the associations between the Q141K and Q126X ABCG2 gene variants and gout risk

Background: Gout is an inflammatory disease in which genetic factors play a role. ABCG2 is a urate transporter, and the Q141K and Q126X variants of ABCG2 have been associated with a risk of developing gout, though previous studies of these associations have been inconsistent. Therefore, we conducted a meta-analysis to explore the relationship between these genetic variants and gout. Methods: We examined 8 electronic literature databases. In total, 9 eligible articles on the associations between the Q141K (rs2231142) and Q126X (rs72552713) variants and gout risk, including 11 case-control studies were selected. We used odds ratios (OR) and 95% confidence intervals (CI) to assess the strength of these relationships in dominant, recessive, and co-dominant models. Results: This study included 6652 participants (2499 gout patients and 4153 controls). The Q141K variant was found to significantly increase the risk of gout in Asians (dominant model: OR=2.64, 95% CI=2.04-3.43, P=0.02 for heterogeneity; recessive model: OR=3.19, 95% CI=2.56-3.97, P=0.28 for heterogeneity; co-dominant model: OR=1.37, 95% CI=1.18-1.59, P=0.09 for heterogeneity) and other populations (dominant model: OR=1.85, 95% CI=1.20-2.85, P<0.0001 for heterogeneity; recessive model: OR=3.78, 95% CI=2.28-6.27, P=0.19 for heterogeneity; co-dominant model: OR=1.48, 95% CI=1.26-1.74, P=0.19 for heterogeneity). The Q126X variant also significantly increased the risk of gout in Asians (dominant model: OR=3.87, 95% CI=2.07-7.24, P=0.06 for heterogeneity). Conclusions: These results suggest associations between the rs2231142 and rs72552713 ABCG2 gene polymorphisms and gout risk, which led to unfavorable outcomes. However, studies with larger sample sizes and homogeneous populations should be performed to confirm these results.     

Identification of a novel miRNA-target gene regulatory network in osteosarcoma by integrating transcriptome analysis

Osteosarcoma remains a leading cause of cancer death in children and young adolescents. Although the introduction of multiagent chemotherapy, survival rates have not improved in two decades. Therefore, it is urgently needed to know the details regarding molecular etiology to driving therapeutic inroads for this disease. In this study we performed an integrated analysis of miRNA and mRNA expression data to explore the dysregulation of miRNA and miRNA-target gene regulatory network underlying OS. 59 differentially expressed miRNAs were identified, with 28 up-regulated and 31 down-regulated miRNAs by integrating OS miRNA expression data sets available. Using miRWalk databases prediction, we performed an anticorrelated analysis of miRNA and genes expression identified by a integrated analysis of gene expression data to identify 109 differently expressed miRNA target genes. A novel miRNA-target gene regulatory network was constructed with the miRNA-target gene pairs. miR-19b-3p, miR-20a-5p, miR-124-3p and their common target CCND2, the nodal points of regulatory network, may play important roles in OS. Bioinformatics analysis of biological functions and pathways demonstrated that target genes of miRNAs are highly correlated with carcinogenesis. Our findings may help to understand the molecular mechanisms of OS and identify targets of effective targeted therapies for OS.