Decorin inhibits MMP13 gene expression in human chondrocytes: an in vitro study

目的 体外原代细胞培养人正常关节软骨细胞,观察不同浓度的外源性核心蛋白聚糖(decorin,DCN)对软骨细胞基质金属蛋白酶13(matrix metalloproteases 13,MMP13)表达的影响.方法 采用胰蛋白酶和Ⅱ型胶原酶结合消化法分离培养人透明软骨细胞,观察体外培养的软骨细胞形态,阿尔新蓝染色和Ⅱ型胶原免疫组化鉴定透明软骨细胞,从基因水平(实时定量PCR)检测不同浓度的外源性DCN(对照组:0,A组:2.5μg/ml,B组:25 μg/ml,C组:250 μg/ml)作用下透明软骨细胞对MMP13、X型胶原(Collagen X)表达的影响.结果 ①正常透明软骨细胞培养呈多角型,扁平状,换液培养5d时,细胞呈多边形、星形等,排列紧密呈“铺石板”样.②本法分离培养的原代透明软骨细胞的阿尔新蓝染色和Ⅱ型胶原免疫组化均为阳性.③随着外源性DCN浓度(0～250μg/ml)的不断增大,Collagen X的表达明显降低(P＜0.01),且成剂量依赖关系(A:0.78±0.03,B:0.71±0.04,C:0.63±0.01),MMP13的表达则在DCN高浓度组(250 μg/ml)时明显降低(0.85±0.02,P＜0.01).结论 外源性DCN抑制透明软骨细胞的Collagen X的表达且成剂量依赖关系,高浓度(250μg/ml)对MMP13的表达起明显抑制作用.表明外源性DCN可能通过抑制透明软骨细胞肥大化抑制软骨细胞MMP13的表达.     

Study on Toughening and Temperature Sensitivity of Polyurethane Cement (PUC)

Polyurethane cement (PUC) is now commonly used in the reinforcement of old bridges, which exhibit various issues such as poor toughness, temperature-sensitive mechanical properties, and brittle failure. These problems can lead to the failure of the reinforcement effect of the PUC on old bridges in certain operating environments, leading to the collapse of such reinforced bridges. In order to alleviate these shortcomings, in this study, the toughness of PUC is improved by adding polyvinyl alcohol (PVA) fiber, carbon fiber, and steel fiber. In addition, we study the change law of the flexural strength of PUC between −40 °C and +40 °C. The control parameters evaluated are fiber type, fiber volume ratio, and temperature. A series of flexural tests and scanning electron microscope (SEM) test results show that the flexural strength first increases and then decreases with the increase in the volume-doping ratio of the three fibers. The optimum volume-mixing ratios of polyvinyl alcohol (PVA) fiber, carbon fiber, and steel fiber are 0.3%, 0.04% and 1%, respectively. Excessive addition of fiber will affect the operability and will adversely affect the mechanical properties. The flexural strength of both fiber-reinforced and control samples decreases with increasing temperature. Using the flexural test results, a two-factor (fiber content, temperature) BP neural network flexural strength prediction model is established. It is verified that the model is effective and accurate, and the experimental value and the predicted value are in good agreement.     

Microstructure and Phase Evolution of Ti-Al-C-Nb Composites Prepared by In Situ Selective Laser Forming

In the present work, a novel Ti-Al-C-Nb composite was prepared using in situ selective laser forming (ISLF). The formation mechanism of the Ti-Al-C-Nb bulks, which were synthesized using elemental titanium, aluminum, and carbon (graphite) powders via ISLF techniques, was investigated. The results showed that the Ti₃Al and TiC phases were the dominant synthesis products during the chemical reactions, and these occurred during the ISLF process. The size of the fine nanoscale crystal TiC grains could reach 157 nm at an energy level of 60 J/mm³. The porous structure of the ISLF specimens was disclosed, and an open porosity of 20–44% was determined via the scanning speed and the laser power. Both the high dynamic viscosity and the reactions of the raw powders led to the generation of a considerable number of pores, whereas the specimen processed using 45 W and 100 mm/s possessed the lowest degree of open porosity.     

First-Principles Study of Silicon–Tin Alloys as a High-Temperature Thermoelectric Material

Silicon–germanium (SiGe) alloys have sparked a great deal of attention due to their exceptional high-temperature thermoelectric properties. Significant effort has been expended in the quest for high-temperature thermoelectric materials. Combining density functional theory and electron–phonon coupling theory, it was discovered that silicon–tin (SiSn) alloys have remarkable high-temperature thermoelectric performance. SiSn alloys have a figure of merit above 2.0 at 800 K, resulting from their high conduction band convergence and low lattice thermal conductivity. Further evaluations reveal that Si_0.75Sn_0.25 is the best choice for developing the optimum ratio as a thermoelectric material. These findings will provide a basis for further studies on SiSn alloys as a potential new class of high-performance thermoelectric materials.     

超声生物显微镜对慢性低眼压诊断和治疗的动态监测

目的:一组以UBM诊断为基础的慢性低眼压患者,经眼压、裂隙灯显微镜、眼底检查、UBM3~6mo的动态监测,了解低眼压的恢复情况,不同治疗方法的效果,说明UBM在低眼压诊断和治疗中的作用。方法:慢性低眼压45眼(眼压≤8mmHg),平均眼压为5.59(2~8)mmHg,病史超过1mo。所有患者均进行常规眼科检查,包括视力、裂隙灯、眼压检查、前房角镜、间接检眼镜、UBM检查,治疗分为药物组和手术组,于治疗后1wk;1,3和6mo进行随访检查。结果:经UBM检查有24眼(53%)为钝伤性低眼压,主要为睫状体脉络膜脱离;16眼(36%)为各种内眼手术后所致的低眼压;1例(0.04%)患者为风湿性心脏病继发双眼葡萄膜炎。基线眼压与治疗后随访眼压比较,均存在显著性差异(P<0.01)。末次眼压和基线眼压之间无相关性,而和病史及发病年龄均呈强的负相关性。42眼(93%)UBM检查有形态学结构改变,睫状体异常占87%。药物组和手术组的基线眼压分别为5.91和4.95mmHg,存在显著性差异(P<0.05),药物组病史明显长于手术组,而手术组发病年龄明显低于药物组,随访的末次眼压分别为10.42和11.25mmHg,无显著性差异。结论:经治疗两组眼压均有显著提高,手术组的患者病情明显重于药物组,治疗前眼压低,发病年龄小,但治疗后眼压效果相似。UBM无论在低眼压的诊断,还是治疗后监测中均有非常重要的作用。     

Purified protein derivative skin testing on HIV/AIDS patients and logistic regression analysis of its risk factors

Objective: To understand the reactivity of purified protein derivative skin test(PPD test) in HIV-infected persons and to determine the influential factors associated with PPD. Methods: 174 HIV/AIDS patients registered in the local center for disease control and prevention(CDC) participated this study from April to June in 2006. Questionnaire, CD4 count and thoracic roentgenogram were performed for all participants. Results: In this study, response rate of questionnaires was 83.65%. The majority of these participants had a different degree of immunodeficiency that accounted for 93.64%. Female patients had a higher CD4 count than that of males. The total positive rate of PPD was 38.15%. Analysis of single factor in our study indicated that CD4 count, previous tuberculosis history, tuberculosis contact history and thoracic roentgenogram manifestation of patients were related to their PPD diameters. Further analysis of multiple factors also supports the previous conclusion that CD4 count and previous tuberculosis history of patients were risk factors in the PPD test. Conclusion: The PPD test of HIV/AIDS patients could be affected by several factors. For persons infected with HIV, the confirmation of latent tuberculosis infection (LTBI) should be considered the combination effect of previous MTB infection and body cellular immune function.     

血浆D-二聚体早期诊断急性肠系膜缺血性疾病的价值研究

目的 评判血浆D-二聚体项目指标实行于急性肠系膜缺血性疾病患者早期诊断过程中的诊断意义。方法 该文报告中将2018年4月—2020年9月广州新市医院急诊科予以诊断的31例急性肠系膜缺血性疾病患者纳入试验组具体评估资料,并将同时间段接受健康检查的31例健康体检人员纳入参照组具体评估资料,两个组别都予以血浆D-二聚体项目指标测定,统计各个组别不同时间血浆D-二聚体项目指标检测所得数值,对比临床具体诊断结果和血浆D-二聚体项目指标检测具体结果。结果 试验组入院第1 d、入院第7 d、入院第10 d血浆D-二聚体项目指标检测所得数值对比参照组体检当天对应结果情况升高,差异有统计学意义（P <0.05）,试验组入院第7 d、入院第10 d血浆D-二聚体项目指标检测所得数值对比本组入院第1 d对应结果情况降低,差异有统计学意义（P <0.05）,试验组入院第10 d血浆D-二聚体项目指标检测所得数值对比本组入院第7 d对应结果情况降低,差异有统计学意义（P <0.05）;将临床具体诊断结果用作评估标准,血浆D-二聚体项目指标对于早期判断急性肠系膜缺血性疾病的诊断敏感性是77.42...     

急性颅脑损伤后血清内源性类洋地黄物质含量变化

目的 探讨颅脑损伤后血清内源性类洋地黄物质（ＥＤＬＳ）含量变化及其机理和临床意义。方法 采用放免法检测６３例急性颅脑外伤患者血清ＥＤＬＳ浓度变化,对其中１９便作动态观测,１６例行手术前后对比,２３例与预后进行相关分析。结果 不同程度脑外伤皇２４小时内血清ＥＬＤＳ均升高,以轻伤组最为典型;随着损伤程度的加剧,少数病例ＥＤＬＳ不变甚至下降,术后或随伤情的恢复,ＥＤＬＳ多同步下降,不同病病理类型的脑损伤     

The Contribution of Cdc2 in Rotenone-Induced G2/M Arrest and Caspase-3-Dependent Apoptosis

Neuronal cell cycle reentry maintained in a G2-like state before cell death, has been confirmed in dopaminergic neurons of patients with Parkinson's disease (PD). Caspase-3 is a final effector in apoptotic dopaminergic neurons in patients. The association of aberrant G2/M regulation with caspase-3 dependent apoptosis remains to be elucidated. Cell division cycle protein 2 (Cdc2) is a key player in G2/M transition in mitotic cells. Although the deregulation of Cdc2 correlated with the control of apoptosis in neurons, the molecular pathway by which Cdc2 involves in apoptosis is not clear. In a rotenone-based cell model of PD, we demonstrated that rotenone arrested cell cycle at G2/M phase and activated caspase-3 both in cytoplasm and nucleus. The decreased activity of Cdc2 by roscovitine or rotenone enhanced G2/M arrest. The increased cells in G2/M arrest by rotenone upregulated the expression of Cdc2. Suppression of Cdc2 expression downregulated cleaved caspase-3/9 and delayed cell apoptosis. Used together, the upregulation of Cdc2 contributes to rotenone-induced caspase-3/9-dependent apoptosis, which is associated with the enhancement of G2/M arrest. Our results suggest the deregulation of Cdc2 as a transition between cell cycle arrest and cell death.