NO介质在大鼠红藻氨酸诱导癫痫发作中的作用

目的：进一步探讨脑内一氧化氮(NO)介质(NO或NO衍生物)在复杂部分性及全身强直阵挛性癫痫发作中的作用。方法：采用红藻氨酸(KA)诱导大鼠癫痫发作,以NO合酶抑制剂L-硝基精氨酸(L-NNA)或NO前体L-精氨酸(L-Arg)予以预处理,观察其癫痫发作行为及海马结构内NO含量(NO2^-/NO3^-)的变化。结果：给予大鼠惊厥剂量KA(10mg/kg),15min时出现湿狗样抖动(WDS),1～3h出现全身痉挛;经L-NNA(50mg/kg)或L-Arg(40mg/kg)预处理的大鼠,注射相同剂量的KA后,其癫痫行为发生明显变化,L-NNA预处理的大鼠癫痫发作行为明显加重,表现为全身痉挛的潜伏期缩短、时间延长、死亡率提高;L-Arg预处理的大鼠癫痫发作行为减弱,WDS和全身痉挛的潜伏期均延长,发作程度减轻、时间缩短,观察时间内无一例死亡。KA给药后30min海马结构内的NO2^-/NO3^-含量迅速增多,7d时仍持续增高;与NS预处理组相比,经L-Arg预处理的动物,KA给药后3h及3d,其NO2^-/NO3^-浓度升高明显。结论：兴奋诱导性癫痫发作过程中内源性NO介质的变化可能具有重要的抗发作作用。     

NYD-SP16, a novel gene associated with spermatogenesis of human testis

By hybridizing human adult testis cDNA microarrays with human adult and embryo testis cDNA probes, a novel human testis gene NYD-SP16 was identified. NYD-SP16 expression was 6.44-fold higher in adult testis than in fetal testis. NYD-SP16 contains 1595 base pairs (bp) and a 762-bp open reading frame encoding a 254-amino acid protein with 73% amino acid sequence identity with the mouse testis homologous protein. The NYD-SP16 gene was localized to human chromosome 5q14. The deduced structure of the NYD-SP16 protein contains one transmembrane domain, which was confirmed by GFP/NYD-SP16 fusion protein expression in the cytomembrane of the transfected human choriocarcinoma JAR cells, suggesting that it is a transmembrane protein. Multiple tissue distribution indicated that NYD-SP16 mRNA is highly expressed in the testes and pancreas, with little or no expression elsewhere. Further analysis of abnormal expression in infertile male patients revealed complete absence of NYD-SP16 in the testes of patients with Sertoli-cell-only syndrome and variable expression in patients with spermatogenic arrest. Homologous gene expression in mouse testis was confirmed in spermatogenic cells by in situ hybridization. The results of cDNA microarray, in situ hybridization, and semiquantitative polymerase chain reaction in mouse testis of different stages indicated that NYD-SP16 expression is developmentally regulated. These results suggest that the putative NYD-SP16 protein may play an important role in testicular development/spermatogenesis and may be an important factor in male infertility.     

A human TERT C-terminal polypeptide sensitizes HeLa cells to H2O2-induced senescence without affecting telomerase enzymatic activity

We have constructed a 27-kDa hTERT C-terminal polypeptide (hTERTC27) devoid of domains required for telomerase activity and demonstrated that it is capable of nuclear translocation/telomere-end targeting. Here we showed that expression of a low level of hTERTC27 renders hTERT positive HeLa cells sensitive to H(2)O(2)-induced oxidative stress and subsequent cell senescence. The senescence-associated gene, the cyclin/cdk inhibitor p21(Waf1), was up-regulated. This occurs without changing the expression of endogenous hTERT, causing significant telomere shortening or inhibiting telomerase activity. Results from this study suggest for the first time that in addition to telomerase activity, the C-terminus of hTERT also plays a role in hTERT-mediated cellular resistance to oxidative stress.     

Purification and characterization of nitric oxide synthase from Staphylococcus aureus

We previously reported the presence of nitric oxide synthase (NOS) in Staphylococcus aureus ATCC6538P whose activity was induced by methanol. In the present study, the methanol-induced NOS was purified 900-fold from S. aureus by means of Mono Q ion exchange column, 2',5'-ADP-agarose affinity column, and Superdex 200HR gel permeation column chromatography. The purified bacterial NOS showed two protein bands with 67 and 64 kDa molecular mass on SDS-PAGE. However, the molecular mass of the NOS was 135 kDa on Superdex 200HR gel permeation column chromatography, indicating that the native enzyme exists as a heterodimer. This bacterial NOS had K(m) value of 13.4x10(-6) M for L-arginine and V(max) of 35.3 nmol min(-1) mg(-1) protein. In addition, reduced nicotinamide adenine dinucleotide phosphate, flavin adenine dinucleotide, flavin mononucleotide, tetrahydrobiopterin, calmodulin and Ca(2+) were required as cofactors in the conversion of L-arginine to L-citrulline, and NOS inhibitors selectively inhibited the activity of the purified NOS.     

Damage formation and repair efficiency in the p53 gene of cell lines and blood lymphocytes assayed by multiplex long quantitative polymerase chain reaction

We examined ultraviolet (UV) irradiation and cisplatin treatment damage formation and repair efficiency in the p53 tumor suppressor gene of various cultured cell lines and lymphocytes using a nonradioactive multiplex long quantitative polymerase chain reaction (QPCR) assay, which amplified a 7-kb fragment of the target gene and a 500-bp fragment of the template control to successfully increase the sensitivity and reliability of the assay. The multiplex long QPCR detected a lesion frequency of 0.63 lesions/10kb/10J/m(2) in the p53 gene of fibroblast cells. In addition, the multiplex long QPCR assay detected pronounced differences in the repair of UV damage in the p53 gene among repair-proficient CRL-1475 cells and repair-deficient XP-A and XP-C cells. The multiplex long QPCR assay was also evaluated as a sensitive assay for the detection of DNA damage induced by cisplatin. The data indicated that the lesion frequency in the p53 gene was 1.27-1.75 times higher in the H23 cisplatin-sensitive cell than in the H1435 cisplatin-resistant cell at the IC(70) dose. After 8-h and 24-h repair periods, only 13 and 75% of cisplatin-induced damage had been removed in the H23 cells, whereas these values were 92 and 100% in the H1435 cells. In addition, our data indicate that multiplex long QPCR is a sensitive method for validly estimating repair in freshly isolated lymphocytes. The results suggest that the current protocol of the multiplex long QPCR method can be used to assess the damage formation and repair efficiency of various agents at biologically relevant doses and to allow a more precise determination of gene-specific repair in disease susceptibility and drug resistance in epidemiological studies.     

灰树花胞外多糖的结构及免疫调节活性

对灰树花胞外多糖A组分(EXGFP-A)进行结构分析和免疫活性的研究。结构分析结果表明,EXGFP-A是一种主要含有葡萄糖的吡喃型中性多糖。气相结果说明EXGFP-A的单糖组成为鼠李糖、阿拉伯糖、木糖、甘露糖、葡萄糖、半乳糖,摩尔比为0.28∶0.31∶0.30∶0.06∶7.98∶0.61。MTT(3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazo-lium bromide)比色实验表明,当EXGFP-A浓度为80μg/m L,作用48 h时,RAW264.7细胞增殖指数达到最大值,为137.5%。吖啶橙(AO)染色结果表明EXGFP-A能够激活RAW264.7细胞,增强细胞内部核酸代谢水平。EXGFP-A在一定浓度范围内,可以提高RAW264.7细胞中NO的释放量,上调细胞内TNF-α、IL-1β、IL-6、IL-12、IFN-γ细胞因子以及细胞中iNOS的mRNA水平的表达。结果表明,EXGFP-A具有一定的免疫调节活性,为灰树花胞外多糖的结构分析和应用提供了科学依据。