人体寰椎横韧带拉伸性能的实验研究

目的：研究人体寰椎横韧带的拉伸性能。方法：新鲜寰椎标本８例,制备成拉伸试件,进行定速率单向拉伸至横韧带断裂。结果：寰椎横韧带平均最大载荷为３１１．６Ｎ,最大变形量为６．０ｍｍ,刚度为７２．９Ｎ／ｍｍ。结论：寰椎侧块间的分离超过６．０ｍｍ,就可存在横韧带断裂。     

IL—6转基因表达诱导大肠癌细胞凋亡

通过分子克隆技术将ＩＬ－６基因导入大肠癌细胞ＨＴ－２９，建立了目的基因转导株ＨＴ－２９ＩＬ－６细胞，该转导株接种子裸鼠皮下后，与非转导株相比，长出肿瘤的时间延后，最终瘤径明显较小，而且移植瘤标本镜下可见大量的核固缩，核染色质加深，核断裂等凋亡细胞，用携带ＩＬ－６基因的重组逆转病毒液感染大肠癌细胞Ｌｏｖｏ后，仅以１．２５μｍｏｌ／Ｌ的ＶＵＭＯＮ－２６（简称ＶＭ－２６）即可诱导该转染株发生明显凋亡，而     

Magnetic and electrical stimulation of undulating nerve fibres: a simulation study

Mathematical models of myelinated nerve fibres are highly stylized abstractions of real nerve fibres. For example, nerve fibres are usually assumed to be perfectly straight. Such idealizations can cause discrepancies between theoretical predictions and experimental results. One well-known discrepancy is that the currently used models predict (contradictory to experimental findings) that an activation of nerve fibres is not possible with a pure transverse electric field. This situation occurs when a magnetic coil is placed symmetrically above a straight nerve fibre for magnetic nerve stimulation, or when an anode and a cathode are placed equidistantly on a line perpendicular to the fibre in the case of electrical stimulation. It is shown that this discrepancy does not occur if the physiological undulation of peripheral nerve fibres is included in the models. Even for small undulation amplitudes (e.g. 0.02 mm), it is possible to activate the fibre in these positions. For physiological undulations, as found in the literature, and favourable (off-centre) positions, the typical reduction of the thresholds is in a range between one and five, compared with perfectly straight fibres.     

Human acetylator genotype: Relationship to colorectal cancer incidence and arylamine N-acetyltransferase expression in colon cytosol

Polymorphic expression of arylamine N-acetyltransferase (EC 2.3.1.5) may be a differential risk factor in metabolic activation of arylamine carcinogens and susceptibility to cancers related to arylamine exposures. Human epidemiological studies suggest that rapid acetylator phenotype may be associated with higher incidences of colorectal cancer. We used restriction fragment length polymorphism analysis to determine acetylator genotypes of 44 subjects with colorectal cancer and 28 non-cancer subjects of similar ethnic background (i.e., approximately 25% Black and 75% White). The polymorphic N-acetyltransferase gene (NAT2) was amplified by the polymerase chain reaction from DNA templates derived from human colons of colorectal and non-cancer subjects. No significant differences inNAT2 allelic frequencies (i.e., WT, M1, M2, M3 alleles) or in acetylator genotypes were found between the colorectal cancer and non-cancer groups. No significant differences inNAT2 allelic frequencies were observed between Whites and Blacks or between males and females. Cytosolic preparations from the human colons were tested for expression of arylamine N-acetyltransferase activity. Although N-acetyltransferase activity was expressed for each of the arylamines tested (i.e., p-aminobenzoic acid, 4-aminobiphenyl, 2-aminofluorene, -naphthylamine), no correlation was observed between acetylator genotype and expression of human colon arylamine N-acetyltransferase activity. Similarly, no correlation was observed between subject age and expression of human colon arylamine N-acetyltransferase activity. These results suggest that arylamine N-acetyltransferase activity expressed in human colon is catalyzed predominantly by NAT1, an arylamine N-acetyltransferase that is not regulated byNAT2 acetylator genotype. The ability to determine acetylator genotype from DNA derived from human surgical samples should facilitate further epidemiological studies to assess the role of acetylator genotype in various cancers.     

Characterization of four newly established human colorectal adenocarcinoma cell lines from Chinese patients.

Four colon adenocarcinoma cell lines, CC-M2, CC-M3, CC-M4, and CC-M2NM, have been established from surgical specimens of 18 unselected patients without the use of "feeder" cells and additional growth factors (e.g., insulin, hydrocortisone, etc.) in the culture medium. The methods of primary cultivation of tissue explants are described. Studies of determination of morphology, growth curve, plating efficiency, chromosomal analysis, CEA and beta-HCG synthesis, and tumorigenicity, were done to characterize the cell lines. Significant variations have been found in one of the four cell lines, both in vitro and in vivo studies. There are distinct phenotypes in the established cell lines which may be useful in studying the cell differentiation and progression of colorectal cancer.     

AT基因突变与食管癌及结肠癌的关系

目的 :探讨共济失调毛细血管扩张症 (AT)基因突变与食管癌及结肠癌发病的关系。方法 :运用PCR SSCP及DNA同位素测序等技术 ,对 17例食管癌和 15例结肠癌患者的AT基因第 41～ 5 1外显子进行突变检测。结果 :15例结肠癌标本的SSCP带型与正常对照组织无差异 ;17例食管癌标本中有 1例SSCP带型比正常对照组织多一条带 ,测序发现 ,该例标本在AT基因第 49外显子发生单碱基缺失。结论 :AT基因突变可能与某些类型的食管癌发病有关 ,但尚不能判断与结肠癌的相关性     

结肠癌P糖蛋白和p53蛋白表达的关系

目的 探讨Ｐ糖蛋白（Ｐ－ｇｐ０和Ｐ５３蛋白在结肠腺癌中的表达意义。方法 应用免疫组织化学方法检测术前进行化疗的１４０例结肠癌组织中的多药耐药基因产物Ｐ－ｇｐ和Ｐ５３蛋白的表达。结果 Ｐ－ｇｐ和Ｐ５３在结肠癌中的表达为２３．５７％（３３／１４０）和４０％（５６／１４０）。Ｐ－ｇｐ表达与结肠癌的组织学类型,浸润深度和淋巴结转移状况无关（Ｐ〉０．０５）,而Ｐ５３除与淋巴结转移状况有关外（Ｐ〈０．０５）,     

人侵袭性结肠癌细胞内质网的超微结构

目的：观察在细胞中占在中心地位的内质网在人侵袭性结肠癌细胞中的超微结构特点。方法：收集外科手术切除的结肠癌标本,应用透射电镜技术观察高分化和低分化人侵袭性结肠癌细胞内质网结构。结果：高分化癌细胞呈柱状,排列较整齐。细胞质中的内质网呈多种形状,并常出现不规则扩张。细胞壁底侧的舌状伪足中可见内质网呈囊泡样;分化癌细胞排列拉散,有的几乎与其他细胞脱离,细胞中的内质网减少;有的内质网与质膜融合,但有向外分泌内含物的趋势。结论：观察到的不同分化程度的人侵袭性结肠癌细胞内质网结构特点将可能成为诊断结肠癌的形态学依据。     

强的松龙.葡聚糖连接物在大鼠胃肠道内容物中的水解

观察强的松龙．葡聚糖连接物的结肠定向释放特性。方法通过将所合成的强的松龙．葡聚糖连接珠与大鼠胃肠道不同部位内容物稀释液一起孵育,观察强的松龙的释放情况。结果在１６０ｍｉｎ的卵育过程中,强的松龙．葡聚糖连接物的在胃肠道上部内容物中水解释放出少量强的松龙及强的椴龙琥珀酸半酯,最在释放量小于３μｍｏｌ．Ｌ＾－１;而在胃肠道下部内容物中水解释放出大量强的松龙及强的松龙琥珀酸半酯最大释放量为１４μｍｏｌ．Ｌ