Alpha-methylacyl-CoA racemase/P504S overexpression in colorectal carcinoma is correlated with tumor differentiation.

Alpha-methylacyl-CoA racemase (AMACR)/P504S is an enzyme involved in the metabolism of branched-chain fatty acids. Little is known about correlation of AMACR expression with colorectal carcinoma (CRC) differentiation and prognosis. We investigated the expression of AMACR in 106 cases of primary CRC, and in 47 lymph nodes with metastatic CRC by immunohistochemical analysis. These cases were divided into 3 groups according to the histologic differentiation of the primary tumors. group A included 50 cases of histologically well and moderately differentiated CRCs, 20 of these with lymph node metastasis; group B included 23 cases of well and moderately differentiated CRCs, histologically similar to group A, except these tumors had small foci (less than 20%) of high-grade carcinoma, and 10 of these had lymph node metastasis; group C included 33 cases of poorly differentiated adenocarcinoma and undifferentiated carcinoma, 17 with lymph node metastasis. The results showed the overall positive rates of expression in primary and metastatic CRCs were 59.4% and 46.8%, respectively. Expression in groups A (76.0%) and B (69.6%) was much higher than that in group C (27.3%). In group B, although overexpression of AMACR in primary tumors was similar to that of group A, it was only seen in 30.0% of group B metastatic tumors, which was similar to the rate of expression in group C (23.5%). In contrast, rates of expression in group A primary and metastatic tumors were similar (80.0% and 75.0%). Positive staining for AMACR in benign epithelium adjacent to tumor was rare (<2%). No relation was found between AMACR expression and overall survival. Our findings support the view that the expression of AMACR in CRC is correlated with tumor differentiation.     

中国汉族人与美国高加索白人膝关节几何形态的比较

背景:有研究显示中国人膝关节胫骨近端前后径和横径均小于美国高加索人,所以在膝关节形态学方面存在一定差异,因此常发生进口假体系统应用于国人后出现匹配度不高的现象。目的:测量中国人和美国人股骨远端、胫骨近端的几何形态学参数,比较其差异。方法:选择北京清华长庚医院骨科拟行前交叉韧带重建的中国汉族患者50例,以及美国匹兹堡大学运动医学中心拟行前交叉韧带重建的高加索白人后裔患者40例,对90例受试者膝关节进行CT扫描,使用AW Volume Share 5软件进行三维重建,利用Geomagic软件对胫骨近端和股骨远端的各项参数进行测量。结果与结论:①股骨近端测量参数中,中国人的外侧胫骨平台内外径小于美国人(P=0.027),外侧胫骨平台后倾角大于美国人(P<0.05);两组间胫骨平台内外径、内侧胫骨平台外径、内侧胫骨平台前后径、外侧胫骨平台前后径与内侧胫骨平台后倾角比较差异均无显著性意义(P>0.05);②股骨远端测量参数中,中国人的股骨远端横径、外侧髁内外径、内侧髁前后径、外侧髁前后径及髁间窝高度均小于美国人(P<0.05),股骨外翻角大于美国人(P<0.05);两组间内侧髁内外径、髁间窝宽度及滑车沟宽度比较差异无显著性意义(P>0.05);③结果表明,中国人与美国人在膝关节形态学的多个参数存在差异,有必要针对中国人设计更为个体化的膝关节假体。     

SAGE遗传分析系统的功能及应用

SAGE是集多功能于一体的医学遗传学群体与家系资料计算机分析系统。本文概述SAGE系统的主要功能及应用环境。重点介绍了FCOR2和TDTEX两个功能模块的数学原理和使用方法。应用TDTEX模块 ,我们发现微卫星标记 85ca与小儿失神症存在连锁不平衡 ,提示在该位点附近存在小儿失神症的易感基因     

旋转叶轮血泵的发展与展望

主要从结构设计、轴承密封设计、控制系统设计三个方面介绍了旋转叶轮血泵技术的最新发展 ,并对其发展趋势做出了展望。     

Effects of the degree of deacetylation on the physicochemical properties and Schwann cell affinity of chitosan films

Chitosan is a potential material for the preparation of nerve repair conduits. In order to find a better chitosan for the application in peripheral nerve regeneration, the effects of the degree of deacetylation (DD) on the physicochemical properties and Schwann cell affinity of chitosan films have been evaluated. Six kinds of chitosan samples with similar molecular weight, but various DD in a range from 70.1 to 95.6% were prepared from one stock chitosan material and fabricated into films. X-ray diffraction analysis showed that there were more crystalline regions in the higher DD chitosan films. Swelling and mechanical property measurements revealed that the swelling index of chitosan films decreased and their elastic modulus and tensile strength increased with the increase in DD. The adsorption amount of fibronectin and laminin on chitosan films was measured by means of enzyme-linked immunosorbent assay (ELISA). Culture of adult rat Schwann cells on the films showed that the chitosan films with higher DD provided better substrata for Schwann cell spreading and proliferation. In conclusion, DD of chitosan plays an important role in their physicochemical properties and affinity with Schwann cells. The results suggest that chitosan with a DD higher than 90% is considered as a promising material for application in peripheral nerve regeneration.     

Association of E-cadherin, matrix metalloproteinases, and tissue inhibitors of metalloproteinases with the progression and metastasis of hepatocellular carcinoma.

Molecular markers can provide additional information to traditional histomorphological evaluation for the assessment of tumor progression and predicting the likelihood of invasion and metastasis in various types of malignancies. We studied the association of E-cadherin, matrix metalloproteinases (MMPs), and tissue inhibitors of metalloproteinase with the progression and metastasis of hepatocellular carcinoma. Tissue microarray including six normal livers, 14 cirrhotic livers, 39 macroregenerative nodules, 16 dysplastic nodules, 22 grade I hepatocellular carcinomas, 43 grade II hepatocellular carcinomas, seven grade III hepatocellular carcinomas, and 10 metastatic hepatocellular carcinomas were stained immunohistochemically with antibodies against MMPs -1, -2, -3, -7, -9, tissue inhibitors of metalloproteinase-1, -2, -3, and E-cadherin. The intensities of staining were scored manually by two pathologists and verified by the Chromavision Automated Cellular Imaging System. Compared with normal liver, cirrhotic liver had significantly lower E-cadherin and tissue inhibitors of metalloproteinase-1 but higher MMP-1 and -7, which suggest a more favorable environment for tumor invasion and metastasis. Grade I and grade II hepatocellular carcinomas demonstrated high E-cadherin and decreased MMP-3 and -9, which may explain the rarity of extrahepatic metastasis in low-grade hepatocellular carcinomas despite the high circulatory volume of the liver. The histological progression from dysplastic nodule to well-differentiated hepatocellular carcinoma and to less differentiated tumors was associated with a gradual decrease in tissue expression of E-cadherin, tissue inhibitors of metalloproteinase-2 and -3. Metastatic hepatocellular carcinomas showed significantly lower level of tissue inhibitors of metalloproteinase-1, -2, -3 but higher level of MMP-7. These data suggest that tissue expression of E-cadherin, certain MMPs, and tissue inhibitors of metalloproteinases could be useful markers to predict the progression and metastasis of hepatocellular carcinoma.     

Downregulation of tonic GABA currents following epileptogenic stimulation of rat hippocampal cultures

Deficits in GABAergic inhibitory transmission are a hallmark of temporal lobe epilepsy and have been replicated in animal and tissue culture models of epilepsy. GABAergic inhibition comprises phasic and tonic inhibition that is mediated by synaptic and extrasynaptic GABA_A receptors, respectively. We have recently demonstrated that chronic stimulation with cyclothiazide (CTZ) or kainic acid (KA) induces robust epileptiform activity in hippocampal neurons both in vitro and in vivo . Here, we report a downregulation of tonic GABA inhibition after chronic epileptogenic stimulation of rat hippocampal cultures. Chronic pretreatment of hippocampal neurons with CTZ or KA resulted in a marked reduction in GABAergic inhibition, as shown by a significant decrease in whole-cell GABA currents and in the frequency of miniature inhibitory postsynaptic currents (mIPSCs). Interestingly, synaptically localized GABA_A receptors remained relatively stable, as evidenced by the unaltered amplitude of mIPSCs, as well as the unchanged punctate immunoreactivity of γ2 subunit-containing postsynaptic GABA_A receptors. In contrast, tonic GABA currents, assessed either by a GABA_A receptor antagonist bicuculline or a selective extrasynaptic GABA_A receptor agonist THIP, were significantly reduced following epileptogenic stimulation. These results reveal a novel form of neural plasticity, that epileptogenic stimulation can selectively downregulate extrasynaptic GABA_A receptors while leaving synaptic GABA_A receptors unchanged. Thus, in addition to synaptic alteration of GABAergic transmission, regulation of tonic inhibition may also play an important role during epileptogenesis.     

Synthesis and thermal properties of poly(enaminonitriles) containing flexible ether units

Poly(enaminonitriles) containing flexible alkyl ether units were prepared by reacting p-bis(1-chloro-2,2-dicyanovinyl)benzene with various α,ω-bis(4-aminophenoxy)alkanes in N-methyl-2-pyrrolidone (NMP). All the polymers are soluble in polar aprotic solvents such as N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N,N-dimethylacetamide (DMAc) and NMP as well as in common organic solvents such as tetrahydrofuran and acetone. High molecular weight polymers possessing inherent viscosities in the range of 0.82–1.20 dL/g were obtained and tough films were cast from a DMF solution. They showed a large exotherm around 340°C attributable to the chemical changes of the dicyanovinyl group. Thermogravimetric analyses exhibited a good thermal stability with a 10% weight loss around 450°C and 73–88% residual weight at 500°C under nitrogen.     

Kinetics of the polymerization of isoprene with isopropoxyneodymium dichloride/triethylaluminium binary lanthanide catalyst system

The kinetics of the polymerization of isoprene with the heterogeneous rare earth catalyst system isopropoxyneodymium dichloride/triethylaluminium (Nd(OPrⁱ)Cl₂-AlEt₃) was examined in a specially designed dilatometer. The rate of polymerization is expressed as R_p ≈ ?d[M]/dt = k[Nd]^1.40 [M]. The main kinetical parameters such as the concentration of active propagating chain, the efficiency of lanthanide catalyst used (ELCU), the absolute rate constant of propagation as well as the average life time of growing chains, were determined at 30°C, 40°C, 45°C and 50°C.