Heterogeneity of HLA-A2 in Asia-Oceanic populations

HLA-A2 is one of the most common yet most diversified HLA antigens with 17 subtypes so far identified at the molecular level. A2 subtyping may have significant impact on clinical medicines. We developed a PCR/SSO-based comprehensive typing protocol for HLA-A and investigated the distribution of A2 alleles in regional ethnic groups. A2 was detected with high frequencies in most study populations. A total of 480 A2+ samples were identified and subtyped. The gene frequencies of A2 ranged from 34% in Chinese, 29% in Australian Caucasoids, 21% in Polynesians, 14% in Javanese and 13% in Australian Aborigines. However, in Melanesians and Micronesians A2 was absent. Six A2 alleles were found in the present experiments including A^*0201, 0203, 0205, 0206, 0207 and 0210. In Aborigines all the A2+ donors were typed as 0201. In Caucasoids A^*0201 accounted for 95% of A2+ samples though other three subtypes A^*0203, 0205 and 0207 were also detected. Extraordinary A2 heterogeneity was observed in Asia-Pacific populations where A^*0201 has become a minority. In Chinese all the six A2 alleles were discovered with A^*0201, 0203, 0206 and 0207 as the four major ones. In Javanese A2 was equally divided into A^*0201, 0203 and 0206 while in Polynesians A2 is overwhelmingly dominated by the oriental A^*0206 (71%). Our study also showed that comprehensive DNA matching for A2 would eliminate most A mismatches in the unrelated-donor transplantation in study populations.     

人肿瘤细胞与正常细胞内微管的PAP免疫酶细胞化学观察

我们利用兔抗微管蛋白抗体和兔抗辣根过氧化物酶(HRP)抗血清制备的HRP—抗HRP(PAP)复合物,建立了微管的PAP免疫酶细胞化学方法。应用此法观察到人食管癌ECa 109、胃癌SGC 7901,乳腺癌MCF 7和成骨肉瘤OS 732细胞间期胞质微管减少或消失,只有大量弥散分布的微管蛋白棕色反应产物,在微管组织中心(MTOC)附近十分密集,而正常成纤维细胞和胎儿胃粘膜上皮细胞间期,都有发达的胞质微管结构(CMTC)。在分裂期,这些肿瘤细胞都显示纺锤体微管,与正常细胞比较无明显差异。本研究应用PAP方法进一步证明,以前用免疫荧光细胞化学方法观察到的人肿瘤细胞间期胞质微管缺陷的特征。除去低温(4℃)或秋水仙酰胺处理后,解聚的CMTC又可恢复,表明本方法与免疫荧光染色法,同样具有很高的特异性。本工作在细胞固定及免疫反应的某些步骤上有所改进。     

Peripheral nerve regeneration by microbraided poly(L-lactide-co-glycolide) biodegradable polymer fibers

Tiny tubes with fiber architecture were developed by a novel method of fabrication upon introducing some modification to the microbraiding technique, to function as nerve guide conduit and the feasibility of in vivo nerve regeneration was investigated through several of these conduits. Poly(L-lactide-co-glycolide) (10:90) polymer fibers being biocompatible and biodegradable were used for the fabrication of the conduits. The microbraided nerve guide conduits (MNGCs) were characterized using scanning electron microscopy to study the surface morphology and fiber arrangement. Degradation tests were performed and the micrographs of the conduit showed that the degradation of the conduit is by fiber breakage indicating bulk hydrolysis of the polymer. Biological performances of the conduits were examined in the rat sciatic nerve model with a 12-mm gap. After implantation of the MNGC to the right sciatic nerve of the rat, there was no inflammatory response. One week after implantation, a thin tissue capsule was formed on the outer surface of the conduit, indicating good biological response of the conduit. Fibrin matrix cable formation was seen inside the MNGC after 1 week implantation. One month after implantation, 9 of 10 rats showed successful nerve regeneration. None of the implanted tubes showed tube breakage. The MNGCs were flexible, permeable, and showed no swelling apart from its other advantages. Thus, these new poly(L-lactide-co-glycolide) microbraided conduits can be effective aids for nerve regeneration and repair and may lead to clinical applications.     

Differential IL-12 responsiveness of T cells but not of NK cells from tumor-bearing mice in IL-12-responsive versus -unresponsive tumor models

While IL-12 administration induces tumor regression through stimulating T cells in tumor-bearing mice, this IL-12 effect is observed in some but not all tumor models. The present study aimed to compare IL-12 responsiveness of T cells from tumor-bearing mice in IL-12-responsive (CSA1M and OV-HM) and -unresponsive (Meth A) tumor models. Tumor regression in IL-12-responsive tumor models required the participation of T cells, but not of NK1.1(+) cells. Because a NK1.1(+) cell population was the major producer of IFN-gamma, comparable levels of IFN-gamma production were induced in IL-12-responsive and -unresponsive tumor-bearing mice. This indicates that the amount of IFN-gamma produced in tumor-bearing individuals does not correlate with the anti-tumor efficacy of IL-12. In contrast, IL-12 responsiveness of T cells differed between the responsive and unresponsive models: purified T cells from CSA1M/OV-HM-bearing or Meth A-bearing mice exhibited high or low IL-12 responsiveness respectively, when evaluated by the amounts of IFN-gamma produced in response to IL-12. T cells from CSA1M- or OV-HM-bearing but not from Meth A-bearing mice exhibited enhanced levels of mRNA for the IL-12 receptor (IL-12R). These results indicate that a fundamental difference exists in IL-12 responsiveness of T cells between IL-12-responsive and -unresponsive tumor models, and that such a difference is associated with the expression of IL-12R on T cells.     

A tctex1-Ca2+ channel complex for selective surface expression of Ca2+ channels in neurons

Voltage-gated Ca(2+) channels (VGCCs) are important in regulating a variety of cellular functions in neurons. It remains poorly understood how VGCCs with different functions are sorted within neurons. Here we show that the t-complex testis-expressed 1 (tctex1) protein, a light-chain subunit of the dynein motor complex, interacts directly and selectively with N- and P/Q-type Ca(2+) channels, but not L-type Ca(2+) channels. The interaction is insensitive to Ca(2+). Overexpression in hippocampal neurons of a channel fragment containing the binding domain for tctex1 significantly decreases the surface expression of endogenous N- and P/Q-type Ca(2+) channels but not L-type Ca(2+) channels, as determined by immunostaining. Furthermore, disruption of the tctex1-Ca(2+) channel interaction significantly reduces the Ca(2+) current density in hippocampal neurons. These results underscore the importance of the specific tctex1-channel interaction in determining sorting and trafficking of neuronal Ca(2+) channels with different functionalities.     

Cloning and spatial and temporal expression of the zebrafish dopamine D1 receptor.

Dopamine plays important roles in the regulation of central nervous system (CNS) development and functions. In vertebrates, two families of dopamine receptors, collectively known as dopamine D1 and D2 receptors, have been identified. Recently, dopamine receptors have been targeted by pharmacological and therapeutic studies of neurological disorders, such as Parkinson's disease. Here, we report a study on the molecular characterization of dopamine D1 receptor in zebrafish (Danio rerio). We cloned the full-length cDNA of a zebrafish dopamine D1 receptor, designated as drd1. The sequence of drd1 shares high homology to the sequences of dopamine D1 receptors in mammalian, amphibian, and other fish species. drd1 is expressed in the CNS. The first drd1 expression was observed at approximately 30 hours postfertilization, at which time the expression was seen in the developing diencephalon and hindbrain. In developing retinas, the expression of drd1 was detected in the inner nuclear layer with the exception of the marginal zones. In adult retinas, drd1 expression was detected in most cell types in the inner and outer nuclear layers as well as ganglion cell layer. Differential expression of drd1 in developing and adult retinas may play various roles in regulating visual system functions.     

Genetic diversity of the outer surface protein C gene of southern Borrelia isolates and its possible epidemiological,clinical, and pathogenetic implications

The ospC genes of 20 southern Borrelia strains were sequenced. The strains consisted of B. burgdorferi sensu stricto, B. andersonii, B. bissettii, one undescribed genospecies, MI-8, and one probably new Borrelia species, TXW-1. A high degree of similarity exists between B. burgdorferi sensu stricto and B. bissettii and between B. bissettii and B. andersonii. Lateral transfers of the ospC gene probably occurred between B. burgdorferi sensu stricto and B. bissettii and between B. bissettii and B. andersonii. Internal gene recombination appears to occur among them. The highest degree of genetic diversity among them was observed in the two variable domains (V1 and V2), semivariable domain (SV), and the species-specific epitopes (between amino acids 28 and 31). Differences in ospC sequences among southern strains reflect diversity at the strain and genospecies levels. MI-8, which was recognized as an undescribed genospecies in our previous reports, remains distinguishable in our current analysis of ospC genes and is distinct from B. burgdorferi sensu stricto. Interestingly, another undescribed southern isolate, TXW-1, was not amplified under various PCR conditions. Compared to European B. burgdorferi sensu stricto strains, American B. burgdorferi sensu stricto strains show greater genetic heterogeneity. Southern B. burgdorferi sensu stricto, B. andersonii, and B. bissettii isolates were intermixed with each other in the phylogenetic trees. In the derived trees in our work, at least one southeastern strain of B. burgdorferi, MI-2, most closely aligns with a so-called invasive cluster that possesses many proven human-invasive strains. Transmission experiments show that MI-2 and the strains in this group of southern spirochetes are able to infect mice and hamsters and that the typical vector of Lyme disease, Ixodes scapularis, can acquire the spirochetes from infected mammals. Currently, strain MI-2 appears to be the only southern isolate among the 20 we analyzed that clusters with an OspC invasive group and thus might be invasive for humans.     

损毁单侧黑质-纹状体通路的大鼠SVZ、纹状体和黑质神经前体细胞的变化

研究成年大鼠脑室下区 (SVZ)神经前体细胞 (neural precursors)在黑质 -纹状体通路损伤后的反应 ,本研究用 6-羟多巴胺单侧纹状体注射以损毁黑质 -纹状体通路 ,损毁 10 d后腹腔注射 Brd U ,连续 4d,每日两次 ;在 SVZ、纹状体和黑质部位用免疫组化方法检测 Brd U、nestin以及 GFAP阳性细胞。结果显示 :(1) 6-羟多巴胺损毁黑质 -纹状体通路后 ,伤侧 SVZ的 Brd U阳性细胞数明显增多 ,并成簇分布 ;nestin和 GFAP阳性细胞数也增多 ,但以 GF AP阳性细胞增多明显 ;(2 )伤侧纹状体可见大量 Br-d U、GFAP以及少量 nestin阳性细胞分布 ,而健侧只有少量 GFAP阳性细胞 ;(3 )伤侧可见 Brd U阳性细胞在 SVZ和纹状体之间呈条带样分布 ;(4 )伤侧黑质除酪氨酸羟化酶阳性神经元减少外 ,未见 Brd U、GFAP和 nestin阳性细胞表达。上述结果表明 ,6-羟多巴胺损毁黑质 -纹状体通路后 ,SVZ神经前体细胞活动增强 ,有向纹状体迁移的趋势。