Muscle-specific expression of the smyd1 gene is controlled by its 5.3-kb promoter and 5'-flanking sequence in zebrafish embryos.

Zebrafish SmyD1 is a SET and MYND domain-containing protein that plays an important role in myofiber maturation and muscle contraction. SmyD1 is required for myofibril organization and sarcomere assembly during myofiber maturation. Whole-mount in situ hybridization revealed that smyd1 mRNAs are specifically expressed in skeletal and cardiac muscles in zebrafish embryos. However, it is unknown if smyd1 is expressed in other striated muscles, such as cranial and fin muscles, and moreover, the regulatory elements required for its muscle-specific expression. We report here the analyses of smyd1 expression using smyd1-gfp transgenic zebrafish. smyd1-gfp transgenic zebrafish were generated using the 5.3-kb smyd1 promoter and its 5'-flanking sequence. GFP expression was found in the skeletal and cardiac muscles of smyd1-gfp transgenic embryos. GFP expression appeared stronger in slow muscles than fast muscles in transgenic zebrafish larvae. In addition, GFP expression was also detected in cranial and fin muscles of smyd1-gfp transgenic zebrafish larvae. In situ hybridization confirmed smyd1 mRNA expression in these tissues, suggesting that the expression of the smyd1-gfp transgene recapitulated that of the endogenous smyd1 gene. Deletion analysis revealed that the 0.5-kb sequence in the proximal promoter of smyd1 was essential for its muscle specificity. Together, these data indicate that smyd1 is specifically expressed in most, if not all, striated muscles, and the muscle specificity is controlled by the 5.3-kb promoter and flanking sequences.     

免疫耐受机制研究进展

免疫耐受是机体免疫系统在接触某种抗原后所产生的对该抗原特异性免疫无应答状态,是免疫应答的一种特殊形式,免疫应答的复杂性决定了免疫耐受诱导的复杂性和困难性.随着免疫学的发展,人们对免疫耐受产生机制有了较多的认识.本文对免疫耐受与细胞凋亡、调节性T细胞及树突状细胞的研究进展进行综述.     

纳曲酮对移植排异反应的抑制作用

以小鼠心肌组织异位移植和混合淋巴细胞反应为整体和离体模型，观察了阿片受体阻断剂纳曲酮对移植排异反应的影响。结果显示：给动物从术前开始腹腔注射纳曲酮共１０天（每日二次，每次５ｍｇ／ｋｇ）可明显延长移植心肌组织的存活时间；加入纳曲酮（１０－４～１０－８ｍｏｌ／Ｌ）对混合淋巴细胞反应有抑制作用并呈量效关系。同时还观察到，给正常小鼠腹腔注射纳曲酮３天以上，可引起动物脾细胞由ＣｏｎＡ诱导的淋巴细胞转化反应受抑制。以上结果说明纳曲酮可抑制移植排异反应，此作用有可能是通过阻断内源性阿片肽所致。     

转染survivin反义mRNA对Jurkat淋巴瘤细胞生长和化疗敏感性的影响

目的 研究转染survivin反义mRNA对Jurkat淋巴瘤细胞生长的影响以及转染后淋巴瘤细胞对化疗药物的敏感性。方法 构建survivin反义mRNA真核表达质粒pcDNA3．1-反义（As）survivin;利用脂质体转染法将其转入高表达survivin mRNA T淋巴母细胞淋巴瘤Jurkat细胞系,用逆转录聚合酶链反应（RT—PCR）、免疫组织化学SP法、Western印迹法检测细胞中survivin表达;用细胞计数、流式细胞术（FCM）检测其细胞生长曲线、细胞凋亡指数,并进行光镜、电镜形态学观察;并对转染pcDNA3．1-Assurvivin前后Jurkat细胞分别加入4-羟基-环磷酰胺（CTX）、甲氨蝶呤（MTX）72h后,常规MTT检测细胞存活率。结果 RT—PCR检测转染pcDNA3．1-Assurvivin后48h、5和6周Jurkat细胞survivin mRNA表达,发现survivin mRNA表达皆低于对照组;转染后survivin蛋白表达也明显降低。转染pcDNA3．1-Assurvivin后Jurkat细胞生长倍增时间（52h）明显延长;用FCM检测细胞凋亡发现,转染pcDNA3．1-Assurvivin后Jurkat细胞凋亡指数[20．2％（48h）]明显高于对照组（转染空质粒和未转染组,2．1％和1．3％）;5和6周为6．2％和6．8％,明显高于未转染细胞（1．3％和1．0％）。光镜、电镜观察见转染细胞出现较多凋亡细胞及一些变性肿胀细胞;MTT检测结果显示Jurkat细胞转染前后,经化疗药物4-羟基-环磷酰胺和甲氨蝶呤作用,转染细胞的抑制率明显大于未转染组,差异有统计学意义（P〈0．05）。结论 survivin基因对Jurkat细胞系的生长起着重要的作用,抑制survivin基因表达在T淋巴母细胞淋巴瘤治疗中可能有重要的意义,该基因似可能作为治疗的靶点。     

The vitamin D content of fortified milk and infant formula.

BACKGROUND. The fortification of milk and infant formula with vitamin D has had an important role in eliminating rickets in children and osteomalacia in adults. A recent outbreak of vitamin D intoxication caused by drinking milk fortified with excess vitamin D has led to questions about the level of vitamin D in milk from other producers. METHODS. We used high-performance liquid chromatography to measure vitamin D in samples of 13 brands of milk with various fat contents and 5 brands of infant formula purchased at random from local supermarkets in five Eastern states. RESULTS. Only 12 (29 percent) of the 42 samples of the 13 brands of milk and none of the 10 samples of the 5 brands of infant formula contained 80 to 120 percent of the amount of vitamin D stated on the label. Twenty-six of the 42 milk samples (62 percent) contained less than 80 percent of the amount claimed on the label. No vitamin D was detected in 3 of the 14 samples of skim milk tested (lower limit of assay, 4.7 IU per quart [5.0 IU per liter]). One milk sample labeled as containing vitamin D2 (ergocalciferol) contained vitamin D3 (cholecalciferol). Seven of the 10 samples of infant formula contained more than 200 percent of the amount stated on the label; the sample with the highest concentration contained 419 percent of the stated amount. None of the samples of infant formula contained less than the amount stated. CONCLUSIONS. Milk and infant-formula preparations rarely contain the amount of vitamin D stated on the label and may be either underfortified or overfortified. Since both underfortification and overfortification are hazardous, better monitoring of the fortification process is needed.     

家兔腓肠肌在电刺激下力学行为的实验研究

目的 获得肌肉收缩力学特性与其电生理特性间的实验关系。方法 用肌电仪发出不同波宽、不同强度的脉冲电流，对家兔的胫神经进行刺激，记录其复合动作电位及收缩力。结果 得到了收缩力与各种肌电信号的实验关系曲线。结论收缩力与刺激电流之间呈正相关关系、与复合动作电位幅值(CAMP)之间呈线性关系，且收缩力与肌电积分值之间也呈较好的线性关系。     

ZNF268, a novel kruppel-like zinc finger protein, is implicated in early human liver development

The advancement in gene knockout and transgenesis have brought about enormous improvement in our understanding of mouse embryogenesis in the past decade or so. On the other hand, relatively little is known about human embryogenesis due largely to the lack of easy access to human embryos and tissues for biomedical studies. We have previously isolated a novel zinc finger gene, ZNF268, from a 3-week-old human embryo cDNA library in an effort to identify genes important for human embryonic development. To investigate the potential involvement of ZNF268 in human embryogenesis, we report here the spatial and temporal regulation of its expression during development. Northern blot and Western blot analyses revealed that ZNF268 is expressed in early embryos, predominantly, if not exclusively, in fetal liver with little detectable expression in other fetal organs. Interestingly, unlike most zinc finger proteins, ZNF268 protein was found to be localized mainly in the cytoplasm of embryonic hepatocytes. This subcellular localization was substantiated by the localization of EGFP-ZNF268 fusion protein overexpressed in the transfected COS7 cells. These results suggest that ZNF268 plays a role in early human liver development most likely by functioning through a cytoplasmic mechanism.     

P2x7 deficiency suppresses development of experimental autoimmune encephalomyelitis

Background  

The purinergic receptor P2x7 is expressed on myeloid cells as well as on CNS glial cells, and P2x7 activation has been shown to increase both glial and T-cell activation. These properties suggest a role in the development of autoimmune disease including multiple sclerosis.     

V3 sequence analysis and biological characterization of HIV-1 isolates from asymptomatic and early symptomatic Tanzanian individuals

The aim of this study was to determine HIV-1 V3 sequences, in vitro biological characteristics and co-receptor usage of virus isolates from Tanzania. Virus was isolated from 14 of 17 samples investigated. Four of the isolates induced syncytia in MT-2 cells and used the CXCR4 co-receptor, while the remaining 10 isolates used the CCR5 co-receptor characteristic of non-MT-2 tropic viruses. One of the four MT-2 tropic isolates also used the CCR5 and CCR3 co-receptors. Proviral DNA was detected in all 14 isolates and PCR products were subjected to DNA sequencing. Unambiguous V3 amino acid sequences were obtained from 11 amplificates. Phylogenetic analysis indicated that these sequences were divergent and clustered in HIV-1 subtypes A, C or D. Sequences from the viruses that induced syncytia in MT-2 cells presented characteristic V3 phenotype-associated amino acids. Results of co-receptor analysis are in concordance with the isolate phenotype as determined by replication and induction of syncytia in MT-2 cells. The considerable diversity illustrated by a limited number of isolates from Tanzania is in accordance with reports from other regions of Africa.