Role for BLM in replication-fork restart and suppression of origin firing after replicative stress

Mutations in BLM give rise to Bloom's syndrome, a genetic disorder associated with cancer predisposition and chromosomal instability. Using a dual-labeling system in isolated chromosome fibers, we show that the BLM protein is required for two aspects of the cellular response to replicative stress: efficient replication-fork restart and suppression of new origin firing. These functions require the helicase activity of BLM and the Thr99 residue targeted by stress-activated kinases.     

Ultrasound biomicroscopy permits in vivo characterization of zebrafish liver tumors

Zebrafish are a valuable vertebrate model to study carcinogenesis, but noninvasive imaging is challenging because adult fish are not transparent. Here we show that tumors could be readily detected in vivo using high-resolution microscopic ultrasound in zebrafish. We successfully obtained tissue perfusion calculations and cellular aspirates, and analyzed tumor progression and response to treatment. Ultrasound biomicroscopy allows longitudinal studies of tumor development and real-time assessment of therapeutic effects in zebrafish.     

Nucleolar targeting of 5S RNA in Xenopus laevis oocytes: Somatic-type nucleotide substitutions enhance nucleolar localization

In Xenopus laevis oocytes, 5S RNA is stored in the cytoplasm until vitellogenesis, at which time it is imported into the nucleus and targeted to nucleoli for ribosome assembly. This article shows that throughout oogenesis there is a pool of nuclear 5S RNA which is not nucleolar-associated. This distribution reflects that of oocyte-type 5S RNA, which is the major 5S RNA species in oocytes; only small amounts of somatic-type, which differs by six nucleotides, are synthesized. Indeed, ³²P-labeled oocyte-type 5S RNA showed a degree of nucleolar localization similar to endogenous 5S RNA (33%) after microinjection. In contrast, ³²P-labeled somatic-type 5S RNA showed significantly enhanced localization, whereby 70% of nuclear RNA was associated with nucleoli. A chimeric RNA molecule containing only one somatic-specific nucleotide substitution also showed enhanced localization, in addition to other somatic-specific phenotypes, including enhanced nuclear import and ribosome incorporation. The distribution of ³⁵S-labeled ribosomal protein L5 was similar to that of oocyte-type 5S RNA, even when preassembled with somatic-type 5S RNA. The distribution of a series of 5S RNA mutants was also analyzed. These mutants showed various degrees of localization, suggesting that the efficiency of nucleolar targeting can be influenced by many discrete regions of the 5S RNA molecule. J. Cell. Biochem. 69:490–505, 1998. © 1998 Wiley-Liss, Inc.     

高压蒸汽灭菌对钛合金内植入物的疲劳的影响

分析了制约骨折手术成功的因素,一是钛合金内植人物经受长期反复高压蒸汽灭菌造成材料疲劳引起断裂;二是AO手术的引起应力集中和疲劳断裂。提出了发展骨内固定植入物的建议。     

后腹腔镜肾囊肿去顶减压术治疗成人型多囊肾的疗效观察

目的评价后腹腔镜肾囊肿去顶减压术治疗多囊肾的临床疗效。方法2005年1月至2009年12月期间,行后腹腔镜肾囊肿去顶减压术的ADPKD患者17例,于术后1月、6月进行随访,观察患者的腰腹部胀痛情况、血压、血清肌酐、GFR的变化。结果腰腹部胀痛、血压明显低于术前,但随着时间推移,效果有所减弱;血清肌酐、GFR无变化。结论对于单侧症状明显的多囊肾患者,行后腹腔镜肾囊肿去顶减压术能改善腰腹部胀痛及血压。     

肝脏注射醋酸引起局部坏死的实验研究

本实验的目的是证实醋酸可引起肝局部坏死,并且作用强于无水乙醇。对鼠肝局部注射醋酸后,从大体及组织学改变观察局部坏死情况并寻找最适浓度。结果发现醋酸可引起注射局部坏死完全,与周围分界非常清晰,其中５０％醋酸引起的坏死区平均直径最大,且明显优于无水乙醇。提示醋酸可以作为一种制剂,用于局部注射治疗肝癌。     

体外循环心内直视手术中甲基强的松龙对肺保护作用的临床研究

目的：研究在体外循环心脏手术中应用甲基强的松龙的肺保护效果。方法：2000年1月至2001年5月,85例患者在体外循环中应用了甲基强的松龙,作为研究组;1996年9月至1999年12月,143例患者未在体外循环中应用甲基强的松龙,作为对照组。两组病例均静脉复合麻醉,气管插管,中度低温,中深度血液释释,应用冷晶体心肌保护液进行心肌保护。结果：研究组患者体外循环结束时的气道压力、肺泡-动脉血氧分压差的升高幅度和机械通气时间明显少于对照组患者。结论：在体外循环心内直视手术中应用甲基强的松龙,可有效减轻肺损伤,取得良好的肺保护效果。     

双能X线吸收法骨密度仪测试原理浅析

骨质疏松症是当前越来越受到人们重视的一种病。本文简要的介绍了骨密度仪的种类和双能X线的检测工作原理。     

A Novel Syndrome of Episodic Muscle Weakness Maps to Xp22.3

We describe a family with a novel disorder characterized by episodic muscle weakness and X-linked inheritance. Eight males in three generations demonstrate the characteristic features of the disorder. Episodes of severe muscle weakness are typically precipitated by febrile illness and affect the facial and extraocular musculature, as well as the trunk and limbs, and resolve spontaneously over a period of weeks to months. Younger members of the family are normal between episodes but during relapses show generalized weakness, ptosis, and fluctuations in strength. In some cases, fatigability can be demonstrated. The proband has late-onset chronic weakness and fatigability. The clinical phenotype has features suggestive both of the congenital myasthenic syndromes and of ion-channel disorders such as the periodic paralyses. We have localized the responsible gene to chromosome Xp22.3, with a maximum two-point LOD score of 4. 52 at a recombination fraction of.0, between OACA2 and DXS9985.     

Direct membrane insertion of voltage-dependent anion-selective channel protein catalyzed by mitochondrial Tom20.

Insertion of newly synthesized proteins into or across the mitochondrial outer membrane is initiated by import receptors at the surface of the organelle. Typically, this interaction directs the precursor protein into a preprotein translocation pore, comprised of Tom40. Here, we show that a prominent beta-barrel channel protein spanning the outer membrane, human voltage- dependent anion-selective channel (VDAC), bypasses the requirement for the Tom40 translocation pore during biogenesis. Insertion of VDAC into the outer membrane is unaffected by plugging the translocation pore with a partially translocated matrix preprotein, and mitochondria containing a temperature-sensitive mutant of Tom40 insert VDAC at the nonpermissive temperature. Synthetic liposomes harboring the cytosolic domain of the human import receptor Tom20 efficiently insert newly synthesized VDAC, resulting in transbilayer transport of ATP. Therefore, Tom20 transforms newly synthesized cytosolic VDAC into a transmembrane channel that is fully integrated into the lipid bilayer.