Chromosomal location of the human gene for DNA polymerase beta.

Inhibition studies indicate that DNA polymerase beta has a synthetic role in DNA repair after exposure of mammalian cells to some types of DNA-damaging agents. The primary structure of the enzyme is highly conserved in vertebrates, and nearly full-length cDNAs for the enzyme were recently cloned from mammalian cDNA libraries. Southern blot analysis of DNA from a panel of human-rodent somatic cell hybrids, using portions of the cDNA as probe, indicates that the gene for human DNA polymerase beta is single copy and located on the short arm or proximal long arm of chromosome 8 (8pter-8q22). A restriction fragment length polymorphism (RFLP) was detected in normal individuals by using a probe from the 5' end of the cDNA, and this RFLP probably is due to an insertion or duplication of DNA in 20-25% of the population. This restriction site can be used as one marker for chromosome 8 genetic linkage studies and for family studies of traits potentially involving this DNA repair gene.     

静脉注射同种异体骨髓间充质干细胞对血管性痴呆大鼠海马区脑组织形态及微管相关蛋白2表达的影响

目的:骨髓间充质干细胞移植进入脑组织后,能否影响脑组织的形态及微管相关蛋白2的表达从而改善痴呆状态下的认知功能?观察静脉注射同种异体骨髓间充质干细胞后,血管性痴呆模型大鼠脑海马CA1区脑组织形态及微管相关蛋白2的变化。方法:实验于2004-08/2005-05在解放军第二军医大学完成。①实验动物:健康雄性SD大鼠60只,随机数字表法分为细胞移植组、模型对照组、假手术组,20只/组。②实验方法:另取20只大鼠用于体外分离、培养扩增骨髓间充质干细胞,传至第2代时加入BrdU进行标记,制备单细胞悬液,调整细胞浓度为3×109L-1。细胞移植组、模型对照组采用双侧颈总动脉结扎法建立血管性痴呆动物模型,假手术组仅暴露双侧颈总动脉但不结扎。造模后4周,细胞移植组尾静脉注射骨髓间充质干细胞悬液1mL,模型对照组注射等量磷酸盐缓冲液,假手术组不进行尾静脉注射。③实验评估:细胞移植后4周,苏木精-伊红染色检测各组大鼠脑海马CA1区脑组织形态变化,免疫荧光染色观察经BrdU标记的骨髓间充质干细胞示踪情况,免疫组织化学染色检测脑海马CA1区微管相关蛋白2的表达。结果:细胞移植组5只大鼠死亡,模型对照组3只大鼠死亡,假手术组均进入结果分析。①脑海马CA1区锥体细胞形态变化:细胞移植组和模型对照组CA1区锥体细胞较假手术组排列稀疏、紊乱,细胞肿胀、脱失,核固缩,但细胞移植组细胞排列较模型对照组规则,且细胞肿胀、脱失及核固缩较模型对照组减轻。②脑海马内骨髓间充质干细胞的示踪:细胞移植后4周,大鼠脑海马内可见被绿色荧光标记的骨髓间充质干细胞。③脑海马CA1区微管相关蛋白2的表达:与假手术组比较,细胞移植组及模型对照组脑海马CA1区锥体细胞层微管相关蛋白2阳性产物的吸光度值均明显降低(P<0.05);细胞移植组明显高于模型对照组(P<0.05)。结论:静脉注射骨髓间充质干细胞能够使血管性痴呆大鼠脑海马CA1区神经元损伤及脱失减轻,并使微管相关蛋白2表达增加。     

Acute haemorrhagic oedema of infancy, a benign variant of leucocytoclastic vasculitis

Acute haemorrhagic oedema of infancy (AHEI) is an acute leucocytoclastic vasculitis affecting infants and young children. It has a striking appearance of large purpuric skin lesions in a target-like pattern and marked oedema mainly on the face, auricles and extremities. In some patients there is mucosal involvement as well. We present five patients with skin lesions characteristic of AHEI with no visceral involvement and complete resolution within 7-14 days. In three of our five cases, histopathological examination was performed, and demonstrated typical leucocytoclastic vasculitis. Although sometimes confused with Schönlein- Henoch purpura, we suggest that AHEI should be regarded as a separate entity. Clinical criteria for diagnosis are proposed.     

内啡肽－morphiceptin的构象和量子力学研究

本文用分子动力学方法对内啡肽ｍｏｒｐｈｉｃｅｐｔｉｎ（Ｔｙｒ１Ｐｒｏ２Ｐｈｅ３Ｐｒｏ４ＮＨ２）进行了构象研究。所得结果与１Ｈ，１３ＣＮＭＲ和其它实验方法的结果一致，证明我们的构象搜索方法有效。量子力学计算表明此多肽和吗啡在空间和电性上非常相近。因此，它们应作用于同一受体     

维生素C片剂分解动力学研究

在相对湿度小于临界相对湿度的条件下,在温度为60～90℃、相对湿度为60～80%范围内测定了维生素C片剂的色泽(以相对反射率R表示)变化速率,含量C变化速率及片剂溶液的色泽(以透光率T表示)变化速率。三者的表观速率常数k与热力学温度T和相对湿度RH的关系通式为k=k’exp(-E/RT)exp(mRH),k’和m为常数,E为表观活化能。不同速率常数的k’,m和E值均不同。     

维生素C粉末分解动力学研究

在有氧避光条件下,用恒温恒湿加速试验法,研究了在相对湿度小于临界相对湿度时,维生素C粉末的表观变色速率常数k_c与温度、湿度的关系为:k_c=k′exp(-E_a/RT)exp(m′RH),k′与m′为常数,RH为相对湿度,E_a为活化能。RH<70%时的E_a=104.33 kJ·mol^-1。还研究了在各种相对湿度下维生素C粉末含量变化的曲线方程为:C=N/(1+Btⁿ),速率方程为:k_d为分解反应的表现速率常数,N为原始百分含量,C为时间t的含量,B与n为常数。RH为97,93与79.5%时的E_a分别为86.87,88.22与202.64 kJ·mol^-1。     

角质的免疫组织化学定位在头颈肿瘤病理论断中的应用

本研究报告100例头颈正常及肿瘤组织石蜡切片的角质抗体定位。结果表明上呼吸、消化道之被覆上皮、涎腺导管、耵聍腺及中耳上皮、毛囊及汗腺等上皮组织均阳性,而间叶组织则为阴性。鳞癌、基底细胞癌等上皮源性肿瘤均为阳性。再次肯定了角质抗体定位的诊断价值。     

Polychlorinated dibenzofurans (PCDFs): correlation between in vivo and in vitro structure-activity relationships

Fifteen polychlorinated dibenzofuran (PCDF) congeners were administered in a dose-response fashion to immature male Wistar rats and ED50 values for body weight loss, thymic atrophy and the induction of the hepatic microsomal cytochrome P-448-dependent monooxygenases, aryl hydrocarbon hydroxylase (AHH) and 4-chlorobiphenyl hydroxylase were determined. There was an excellent correlation between the in vivo quantitative structure-activity relationships for these PCDFs and their in vitro activities as AHH inducers in rat hepatoma H-4-II E cells and as ligands for the 2,3,7,8-TCDD receptor protein. A comparison of isomers which differ at all 4 positions in the dibenzofuran ring system indicated that chlorine substitution at each position contributed differentially to the overall molecular activity [C-3 (or C-7) greater than C-2 (or C-8) greater than C-4 (or C-6) greater than C-1 (or C-9)]. There was also an excellent linear correlation between a plot of the -log ED50 for body weight loss vs. -log EC50 for in vitro AHH induction (correlation coefficient, r = 0.96) and -log ED50 for thymic atrophy vs. -log EC50 for in vitro AHH induction (correlation coefficient, r = 0.88). Since body weight loss and thymic atrophy in the rat are representative toxic responses to PCDFs and related toxic halogenated aryl hydrocarbons, the correlations noted above support the use of the in vitro AHH induction assay as a short term quantitative test system for this class of toxic halogenated aryl hydrocarbons.     

Polychlorinated dibenzofurans (PCDFs): effects of structure on binding to the 2,3,7,8-TCDD cytosolic receptor protein, AHH induction and toxicity

The effects of structure on the activity of 26 polychlorinated dibenzofurans (PCDFs) as competitive ligands for the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) rat hepatic cytosolic receptor protein were determined in a dose-response fashion. The ED50 values for these compounds varied 100 000-fold and the most active PCDFs were substituted in the 2,3,7 and 8 lateral positions; the ED50 for the most active PCDF, 2,3,4,7,8-pentachlorodibenzofuran was 1.5 X 10(-8) M which was only slightly less active than 2,3,7,8-TCDD (1.0 X 10(-8) M). A comparison of the binding affinities of several isomer pairs also indicated the relative importance of chlorine substitution at C-4 (or C-6) compared to C-1 (or C-9). Moreover, for some isomers it is apparent that C-4 (or C-6) substituents are more active than lateral substituents for facilitating ligand binding to the receptor protein. This is illustrated by the relative binding potencies of the following isomer pairs: 1,2,4,6,7-/1,2,4,7,8 = 19.2; 2,6,7-/2,3,8- = 2.2; 1,3,6-/1,3,8- = 19. Most of the PCDF structure-activity effects noted above were also observed for the induction of aryl hydrocarbon hydroxylase (AHH) and ethoxyresorufin O-deethylase (EROD) in rat hepatoma H-4-II-E cells in culture. The most active compounds were also substituted in the lateral 2,3,7 and 8 positions and a comparison of C-4 (or C-6) vs. C-1 (or C-9) substituted PCDFs confirmed the higher induction potencies for most of the former group of compounds. The in vitro quantitative structure-activity data were complemented by in vivo studies which determined the relative activities of selected PCDFs as inducers of hepatic microsomal cytochrome P-448 dependent monooxygenases and their effects on body weight gain and thymus weights in immature male Wistar rats. The results indicated that for 2 series of isomers, namely the 2,3,4,7,8-, 1,2,4,7,8- and 1,2,4,7,9-pentachlorodibenzofurans and the 2,3,7,8-, 2,3,4,8- and 1,2,4,8-tetrachlorodibenzofurans, their biologic and toxic potencies were dependent on one major structural factor, the number of lateral chloro substituents. These results support the proposed role of the cytosolic receptor protein in mediating the biologic and toxic effects of the PCDFs.