Prospect for enzyme therapy in glycogenosis II variants: a study on cultured muscle cells

Summary Impairment of skeletal muscle function is the common feature of distinct clinical forms of glycogenosis type II. In the present study, muscle cultures from different patients were used to investigate the cause of clinical heterogeneity and the feasibility of enzyme replacement therapy. The activity of acid -glucosidase appears to be the primary factor in determining the extent of lysosomal glycogen storage in muscle, and thereby the clinical severity of the disease. Neutral -glucosidases do not seem influencial. Correction of the enzymatic defect was achieved in skeletal muscle cultures from patients by administration of a high-uptake form of acid -glucosidase, purified from human urine. The enzyme reaches the lysosomes, including the glycogen storage vacuoles, and the lysosomal glycogen content is reduced to control level. In normal muscle cells 20% of the total cellular glycogen pool is segregated in lysosomal compartments. This percentage is higher than in fibroblasts, which may partly explain why muscles are more prone to store glycogen. The relevance of this study for enzyme therapy is discussed.     

Cotinine determination by immunoassays may be influenced by other nicotine metabolites

Polyclonal rabbit anticotinine antiserum, which can be used for biomonitoring nicotine uptake by the determination of cotinine in body fluids, was checked by a competitive ELISA for its cross-reactivity with nine nicotine metabolites. The highest percentage of relative crossreactivity (about 30%) was observed with trans-3-hydroxycotinine, a metabolite which is known to be excreted in 3-fold higher amounts than cotinine in the urine of human smokers. Therefore, it is possible that cotinine determinations performed by immunochemical methods — especially in urine — may yield overestimated cotinine concentrations.     

DFNA54, a third locus for low-frequency hearing loss

Nonsyndromic hereditary hearing impairment (NSHHI) is a highly heterogeneous disorder with more than 90 loci mapped, of which nearly one-half of the responsible genes are identified. In dominant NSSHI hearing loss is typically biased towards the high frequencies while low-frequency hearing loss is unusual. Only two NSHHI loci, DFNA1 and DFNA6/14/38, are associated with predominantly low- frequency loss. We mapped the loci harboring the gene responsible for autosomal dominant low-frequency hearing loss in a multigenerational family. The pedigree of a Swiss family with low-frequency hearing loss was established. Using genomic DNA, DFNA1 and DFNA6/14/38 were excluded by linkage analysis or by direct sequencing of the responsible gene. Genome-wide linkage analysis was performed using commercially available microsatellite markers. Two-point linkage analysis demonstrated linkage to chromosome 5q31, the locus for DFNA15, with a lod score of 6.32 at recombination fraction =0 for marker D5S436. Critical recombinations were seen at markers D5S1972 and D5S410. Sequencing of the corresponding gene POU4F3 yielded no pathogenic mutation segregating with the affected members. In addition to Wolfram syndrome gene 1 (DFNA6/14/38) and diaphanous (DFNA1) there is evidence for a third gene involved in low-frequency hearing loss located at DFNA15. Because of the differences in auditory phenotype and the absence of pathogenic mutation in the coding region of POU4F3 it is likely that there is a second gene in 5q31, designated DFNA54, associated with NSHHI.     

Homologous recombination in the fission yeast Schizosaccharomyces pombe: different requirements for the rhp51+, rhp54+ and rad22+ genes

The Schizosaccharomyces pombe rhp51 ⁺ , rad22 ⁺ and rhp54 ⁺ genes are homologous to RAD51, RAD52 and RAD54 respectively, which are indispensable in the recombinational repair of double-strand breaks (DSBs) in Saccharomyces cerevisiae. The rhp51Δ and rhp54Δ strains are extremely sensitive to ionizing radiation; the rad22Δ mutant turned out to be much less sensitive. Homologous recombination in these mutants was studied by targeted integration at the leu1-32 locus. These experiments revealed that rhp51Δ and rhp54Δ are equally impaired in the integration of plasmid molecules (15-fold reduction), while integration in the rad22Δ mutant is only reduced by a factor of two. Blot-analysis demonstrated that the majority of the leu⁺ transformants of the wild-type and rad22Δ strains have integrated one or more copies of the vector. Gene conversion events were observed in less than 10% of the transformants. Interestingly, the relative contribution of gene conversion events is much higher in a rhp51Δ and a rhp54Δ background. Meiotic recombination is hardly affected in the rad22Δ mutant. The rhp51Δ and rhp54Δ strains also show minor deficiencies in this type of recombination. The viability of spores is 46% in the rad22Δ strain and 27% in the rhp54Δ strain, as compared with wild-type cells. However, in the rhp51Δ mutant the spore viability is only 1.7%, suggesting an essential role for Rhp51 in meiosis. The function of Rhp51 and Rhp54 in damage repair and recombination resembles the role of Rad51 and Rad54 in S. cerevisiae. Compared with Rad52 from S. cerevisiae, Rad22 has a much less prominent role in the recombinational repair pathway in S. pombe. Received: 20 July 1996     

Mapping of sporulation-specific functions in the yeast syntaxin gene<Emphasis Type="Italic"> SSO1</Emphasis>

The yeast Saccharomyces cerevisiae has two closely related plasma membrane syntaxins, Sso1p and Sso2p, which together provide an essential function in vegetative cells. However, Sso1p is also specifically needed during sporulation; and this function cannot be provided by Sso2p. We used fusions between SSO1 and SSO2 to map the sporulation-specific function of SSO1. We found that the two N-terminal -helices Ha and Hb of Sso1p are important for sporulation, since it is reduced 8-fold for fusions where Ha and Hb are derived from Sso2p. In contrast, the C-terminal half of Sso1p does not seem to be specifically required for sporulation. Surprisingly, we further found that the 3 untranslated region (3UTR) of SSO1 is essential for sporulation. Western blots failed to reveal a preferential expression of Sso1p in sporulating cells, indicating that effects on gene expression are unlikely to explain why the SSO1 3UTR is needed for sporulation.Communicated by S. Hohmann     

CD54和LFA-1的相互作用在6A8α-甘露糖苷酶表达抑制的JurkatT细胞的黏附性增强中的作用

目的研究CD54和LFA-1的相互作用在6A8 α-甘露糖苷酶表达抑制的Jurkat细胞(AS)的黏附性增强中的作用。方法用细胞凝集试验确证AS细胞间黏附的增强，用细胞与细胞间黏附分子-1-人IgG的Fc片段(ICAM-1-Fc)的黏附试验和阻断性抗CD11a抗体的阻断试验研究CD54-LFA-1的作用，用单克隆抗体MEM-148检测As细胞LFA-1亲和力的变化，用单克隆抗体NKI-L16检测AS细胞LFA-1亲合力的变化，用鬼笔环肽染色细胞骨架，用Jurkat-Raji细胞间的作用作模型研究6A8α-甘露糖苷酶表达抑制对T和B细胞间黏附的影响，用ConA结合试验检测细胞中蛋白质N-糖基化的变化。结果(1)AS细胞间的黏附性增强主要与CD54及CD11a表达的增强相关，也与LFA-1亲和力的增高相关；(2)AS细胞的细胞骨架发生重排；(3)As细胞与Raji细胞间的黏附也增强；(4)ConA与AS细胞的结合增强。结论CD54和LFA-1的相互作用在AS Jurkat T细胞的黏附性增强中起重要作用。细胞骨架重排也可能起作用。As细胞的蛋白质发生了N-糖基化修饰。     

不同烧结温度对双相钙磷陶瓷颗粒材料介孔结构及其成骨性能的影响

目的通过体内外实验检测不同烧结温度下制备的不同介孔直径双相钙磷陶瓷（biphasic calcium phosphate，BCP）颗粒材料成骨能力差异，为筛选具备更好临床应用参数的 BCP 材料提供依据。方法将羟基磷灰石（hydroxyapatite，HA）及 β-磷酸三钙（β-tricalcium phosphate，β-TCP）以 8∶2 比例混合后，分别在 1 050、1 150 及 1 250℃ 下烧制 3 h 制备 3 种 BCP 材料（分别设为材料1、2、3），比表面积测试法（Brunauer-Emmett-Teller test，BET）测量材料的颗粒内部孔隙率及介孔直径、体积、面积，X 线衍射（X-ray diffraction，XRD）评估材料组成成份，扫描电镜观察材料微观表面形态。体外将第 3 代 SD 大鼠 BMSCs 与各材料共培养 7 d（分别设为 A、B、C 组），扫描电镜观察细胞黏附情况，鬼笔环肽染色观察 BMSCs 贴附于材料表面后的形态，细胞计数试剂盒 8 法检测细胞增殖活性。体内建立比格犬异位成骨模型：取 9 只比格犬，于每只犬双侧竖脊肌内制作 9 个肌袋，将肌袋随机分为 3 组（每组 3 个/只），A、B、C 组分别置入材料 1、2、3。术后 1、2、3 个月分别麻醉 3 只比格犬取材行 HE、Masson 及番红固绿染色，计算 BCP 间隙中的成骨面积比；行实时荧光定量 PCR（real-time fluorescence quantitative PCR，qRT-PCR）检测成骨相关基因 ALP、骨桥蛋白（osteopontin，OPN）、骨钙素（osteocalcin，OC）的表达。结果BET 检测示随烧结温度增加，颗粒内部孔隙率无明显变化，但介孔直径、体积及面积逐渐减小；XRD 检测示 3 种材料均可见 HA 及 β-TCP 两种 X 线衍射波；扫描电镜观察示 3 种材料表面有广泛分布的微孔，孔间有空隙相连。体外实验示 BMSCs 在 3 种材料表面黏附、增殖，B、C 组材料的细胞生物相容性优于 A 组。体内实验结果示，术后 2 个月开始 3 种材料颗粒孔隙内即可见明显的骨样组织沉积。各组成骨面积比随时间延长均增加，术后 2、3 个月 A 组成骨面积比显著高于 B、C 组，1 个月时显著高于 B 组（P<0.05）。qRT-PCR 检测示，A 组成骨相关基因表达在 2 个月时出现峰值，B、C 组各成骨相关基因表达随时间延长逐渐增加。术后 1 个月 A 组 ALP 和 OPN mRNA 相对表达量显著高于 B、C 组，术后 2 个月 A 组 OC mRNA 相对表达量显著高于 B、C 组，术后 3 个月 B、C 组 ALP mRNA 相对表达量及 B 组 OPN mRNA 相对表达量显著高于 A 组（P<0.05）；其余各时间点各组间比较各基因 mRNA 相对表达量差异均无统计学意义（P>0.05）。 结论不同烧结温度下制备的 BCP 材料，其介孔直径随温度增加而减小。不同介孔直径的 BCP 材料异位成骨能力存在差异，其中直径为 12.57 nm 的 BCP 材料能更早激活成骨基因，具备更强的成骨能力。介孔直径可作为一个优化 BCP 材料成骨能力的指标。     

雌激素和异黄酮类药物对内皮细胞粘附分子CD54表达的影响

为探讨雌激素和异黄酮类药物对内皮细胞粘附分子CD54表达的影响,作者采用10ng/ml肿瘤坏死因子(TNFα)处理人脐静脉内皮细胞6小时,并加用不同浓度的异黄酮(WZ1,WZ2)和雌激素(WZ3,WZ4)进行干预48小时,而后用流式细胞仪定量测定细胞表面粘附分子CD54的表达,并进行统计学分析.结果:①10ng/ml的TNFα可使内皮细胞表面粘附分子CD54的表达升高4倍,与对照组相比具有统计学差异(P＜0.05);②10-10mol/L、10-8mol/L、10-6mol/L异黄酮和异卟黄酮对由TNFα诱导的内皮细胞的CD54表达有轻度促进作用;③哌嗪雌酚酮和雌二醇预处理内皮细胞48小时后再加TNFα激活,内皮细胞表面CD54平均荧光强度与单纯TNFα组相比下降明显(P＜0.05),各浓度组之间不具统计学差异(P＞0.05).以上结果提示:异黄酮和异卟黄酮对内皮细胞粘附分子CD54的表达无抑制作用;哌嗪雌酚酮和雌二醇可在一定程度上抑制CD54的表达,从而为抗粘附疗法提供了一条新思路.     

~(60)Co γ射线照射后血管内皮细胞CD54表达变化及PDTC的干预作用

 目的　研究血管内皮细胞在受60 Coγ射线照射后粘附分子CD5 4的表达与单核样细胞在血管内皮细胞上粘附变化的关系 ,观测抗氧化剂PDTC预处理对CD5 4表达及白细胞粘附的影响。方法　培养的ECV30 4细胞接受 16Gy60 Coγ放射线照射后不同时点 ,检测视黄酸诱导的单核样HL 6 0细胞在内皮细胞上的粘附数量 ,内皮细胞CD5 4mRNA及蛋白表达 ,核转录因子κBDNA结合活性以及抗氧化剂PDTC预处理对上述指标的影响。结果　照射后 8h ,HL 6 0细胞粘附数较对照显著上升 ,2 4h时较对照增加 77%。受照后 2h ,CD5 4mRNA水平较对照增加 36 % ,2 4h增加 182 %。照射后 4～ 32h ,CD5 4蛋白表达较对照增加 6 6 %～ 2 6 8%。NF κB DNA结合活性在照射后 2h达峰值 ,较对照增高 97%。PDTC预作用后 2h ,NF κB DNA结合活性较未处理组下降了 4 4 % ,作用后 4h ,CD5 4mRNA表达量下降 35 % ,同时HL 6 0细胞粘附数减少 2 6 %。结论　CD5 4表达上调是60 Coγ射线照射引起单核细胞在内皮细胞上...