Deletion of Brca2 exon 27 causes hypersensitivity to DNA crosslinks,chromosomal instability,and reduced life span in mice

The Brca2 tumor-suppressor gene contributes to genomic stability, at least in part by a role in homologous recombinational repair. BRCA2 protein is presumed to function in homologous recombination through interactions with RAD51. Both exons 11 and 27 of Brca2 code for domains that interact with RAD51; exon 11 encodes eight BRC motifs, whereas exon 27 encodes a single, distinct interaction domain. Deletion of all RAD51-interacting domains causes embryonic lethality in mice. A less severe phenotype is seen with BRAC2 truncations that preserve some, but not all, of the BRC motifs. These mice can survive beyond weaning, but are runted and infertile, and die very young from cancer. Cells from such mice show hypersensitivity to some genotoxic agents and chromosomal instability. Here, we have analyzed mice and cells with a deletion of only the RAD51-interacting region encoded by exon 27. Mice homozygous for this mutation (called brca2(lex1)) have a shorter life span than that of control littermates, possibly because of early onsets of cancer and sepsis. No other phenotype was observed in these animals; therefore, the brca2(lex1) mutation is less severe than truncations that delete some BRC motifs. However, at the cellular level, the brca2(lex1) mutation causes reduced viability, hypersensitivity to the DNA interstrand crosslinking agent mitomycin C, and gross chromosomal instability, much like more severe truncations. Thus, the extreme carboxy-terminal region encoded by exon 27 is important for BRCA2 function, probably because it is required for a fully functional interaction between BRCA2 and RAD51.     

一种改良的抗氧化活性测定方法

活性氧自由基在生物体内参与生理，病理过程并起重大作用，在筛选和评价抗氧化药物时，越来越需要一种快速，简便，价廉而又可靠的抗氧化活性测定方法，本文发展了一种具备了上述优点新方法，ＳＯＤ（超氧化物歧化酶）及其模拟物的工作已有很多，很多文献报道了其活性一；Ｃｕ（Ⅱ）。本文着重研究了另一个金属辅基，Ｚｎ＾２＋并且发现了Ｚｎ＾２＋独特的，但为人们忽视了的；抗氧化活性加强作用。     

Modes of hantavirus transmission in a population of <Emphasis Type="Italic">Clethrionomys rufocanus bedfordiae</Emphasis> inferred from mitochondrial and microsatellite DNA analyses

Summary. To elucidate the mode of transmission of Puumala-related hantavirus in a population of gray red-backed voles, Clethrionomys rufocanus bedfordiae, in Hokkaido, Japan, we analyzed the kin structure and dispersal patterns of individual voles using microsatellite and mitochondrial DNA markers. Siblings or dam/offsprings was identified within the population based on the relatedness calculation with the microsatellite data. The pairwise relatedness values obtained could reveal kinship among all vole individuals within the population. Based on the assessment of kinship, we did not find a positive relationship between hantavirus transmission and close kinship. Males infected with the hantavirus carried a relatively uncommon mitochondrial haplotype. However, these infected males shared low relatedness values and were not considered closely related, i.e., they were not siblings or parent/offspring. These observations imply that hantavirus transmission in the vole population may not be related to close kinship but by random horizontal infection.     

Additive Antinociception between Intrathecal Sildenafil and Morphine in the Rat Formalin Test

The possible characteristics of spinal interaction between sildenafil (phosphodiesterase 5 inhibitor) and morphine on formalin-induced nociception in rats was examined. Then the role of the opioid receptor in the effect of sildenafil was further investigated. Catheters were inserted into the intrathecal space of male Sprague-Dawley rats. For induction of pain, 50 µL of 5% formalin solution was applied to the hind-paw. Isobolographic analysis was used for the evaluation of drug interaction between sildenafil and morphine. Furthermore, naloxone was intrathecally given to verify the involvement of the opioid receptor in the antinociception of sildenafil. Both sildenafil and morphine produced an antinociceptive effect during phase 1 and phase 2 in the formalin test. The isobolographic analysis revealed an additive interaction after intrathecal delivery of the sildenafil-morphine mixture in both phases. Intrathecal naloxone reversed the antinociception of sildenafil in both phases. These results suggest that sildenafil, morphine, and the mixture of the two drugs are effective against acute pain and facilitated pain state at the spinal level. Thus, the spinal combination of sildenafil with morphine may be useful in the management of the same state. Furthermore, the opioid receptor is contributable to the antinocieptive mechanism of sildenafil at the spinal level.     

A locus for spondylocarpotarsal synostosis syndrome at chromosome 3p14

Spondylocarpotarsal synostosis syndrome is a rare autosomal recessive disorder characterised by vertebral fusions, frequently manifesting as an unsegmented vertebral bar, as well as fusions of the carpal and tarsal bones.

In a study of three consanguineous families and one non-consanguineous family, linkage analysis was used to establish the chromosomal location of the disease gene. Linkage analysis localised the disease gene to chromosome 3p14. A maximum lod score of 6.49 (q = 0) was obtained for the marker at locus D3S3532 on chromosome 3p. Recombination mapping narrowed the linked region to the 5.7 cM genetic interval between the markers at loci D3S3724 and D3S1300. A common region of homozygosity was found between the markers at loci D3S3724 and D3S1300, defining a physical interval of approximately 4 million base pairs likely to contain the disease gene.

Identification of the gene responsible for this disorder will provide insight into the genes that play a role in the formation of the vertebral column and joints.

     

α2-巨球蛋白基因I1000V多态性与散发阿尔茨海默氏病的关联研究

目的近年来有研究发现α2-巨球蛋白基因(α2-macroglobulin，A2M)Ile1000Val多态与阿尔茨海默氏病(Alzheimer’s disease，AD)发病有关联，但也有相悖的研究结果报道。因此．我们利用较大的样本，观察了A2M基因Ile1000Val多态在广州及成都地区汉族老年人中的分布，并探讨其与散发AD的相关性。方法以广州地区257例散发AD患者和242名正常老年人、成都地区112例散发AD患者和113名正常老年人为对象进行病例一对照研究。用聚合酶链反应一限制性片段长度多态性方法分析A2M基因11000V多态性和载脂蛋白E基因(apolipoprotelnE，apoE)多态性。结果(1)在两地合并样本中，AD患者与对照组中等位基因A2M-1000V的频率分别为7．7％与8．7％，广州与成都地区AD患者与对照组中A2M基因I1000V多态的分布差异无统计学意义。(2)散发AD无论按是否伴有apoE—ε4或按发病年龄分成不同亚组后，A2M基因I1000V多态的分布在病例组与对照组之间差异无统计学意义。结论广州与成都汉族人群中A2M基因I1000V多态与散发AD不具有关联。     

促肝细胞生长素诱导人肝癌细胞（BEL－7402）凋亡

本文从细胞学、ＤＮＡ凝胶电泳、流式细胞术三方面研究促肝细胞生长素（ｐＨＧＦ）在体外对肝癌细胞增殖活性的影响。结果表明：ｐＨＧＦ对肝癌ＢＥＬ－７４０２细胞增殖有抑制作用，并存在剂量和时间相关性。其４８ｈ的半数抑制浓度（ＩＤ５０）为０．３７ｍｇ／ｍｌ±０．０４ｍｇ／ｍｌ。而３７℃灭活的ｐＨＧＦ对ＢＥＬ－７４０２细胞增殖在１５ｈ无抑制作用，在２４和４８ｈ抑制作用很弱（ＩＤ５０＞１．５ｍｇ／ｍｌ）。ＤＮＡ凝胶电泳结果表明，ｐＨＧＦ可诱导ＢＥＬ７４０２细胞产生细胞凋亡（Ａｐｏｐｔｏｓｉｓ）。流式细胞术（ＦＣＭ）结果显示：ｐＨＧＦ抑制ＢＥＬ－７４０２细胞增殖过程是先使细胞停留在Ｇ０／Ｇ１期，继而诱导细胞产生凋亡。后两项结果均显示ｐＨＧＦ对人肝癌细胞凋亡的诱导里时间和剂量相关性。     

84例周围血管病的足甲襞微循环观察

对84例周围血管病(脉管炎68例,静脉炎16例)和25例正常健康人进行了足甲襞微循环的对比观察。结果:患病组足甲襞微循环的血管形态、流态、管周状态均较正常健康组有明显差异(P<0.01)。提示:更接近病变部位的局部微循环观察更能代表病变的程度,对临床医生判断病情、选择用药和疗效观察都有很大帮助和参考价值。