Biomolecular mimicry in the actin cytoskeleton: mechanisms underlying the cytotoxicity of kabiramide C and related macrolides

This study characterizes the interactions between kabiramide C (KabC) and related macrolides and actin and establishes the mechanisms that underlie their inhibition of actin filament dynamics and cytotoxicity. The G-actin-KabC complex is formed through a two-step binding reaction and is extremely stable and long-lived. Competition-binding studies show that KabC binds to the same site on G-actin as Gelsolin domain 1 and CapG. KabC also binds to protomers within F-actin and results in the severing and capping of the (+) end; these studies suggest that free KabC and related macrolides act as biomimetics of Gelsolin. The G-actin-KabC complex binds to the (+) end of a growing filament, where it functions as a novel, unregulated, (+)-end capper and is largely responsible for the inhibition of motility and cytokinesis in approximately 10 -100 nM KabC-treated cells. KabC and related macrolides are useful probes to study the regulation of the actin filament (+) end and may lead to new therapies to treat diseases of the actin cytoskeleton.     

Efficacy of 'Gamadent' toothpaste on the healing of gingival tissues: a preliminary report

The aim of this randomised, parallel, double-blind study, in which 28 adult patients diagnosed with chronic gingivitis or early stages of chronic periodontitis were recruited, was to evaluate the efficacy of 'Gamadent' toothpaste compared to a placebo toothpaste. 'Gamadent' toothpaste has all the basic constituents of a toothpaste with the addition of a sea cucumber extract (SCE) of the species Stichopus sp. 1 to improve the healing potential of tissues. The placebo has the same basic constituents minus the extract. Out of the 28 patients, 14 were placed in the test group who used the 'Gamadent' toothpaste, and 14 patients were placed in the control group (2 control subjects defaulted and were excluded), who brushed using the placebo toothpaste. The longitudinal study was carried out over a period of 3 months with assessments made at baseline, 1 month, 2 months and 3 months after conventional therapy at the baseline visit. The clinical parameters used during the trial were Plaque Index (PI), Gingival Index (GI), Papilla Bleeding Index (PBI) and Probing Pocket Depth (PPD). A predetermined number of sites on a molar, premolar, canine and an incisor were examined and evaluated in each quadrant. After the baseline assessment, the patients had full mouth scaling and debridement as well as oral hygiene instructions. Patients were instructed to brush their teeth twice a day with the toothbrush provided (Oral-B plus, size 35) and toothpaste (test or control), using the Bass technique. At the 1-month assessment, there were significant mean reductions to baseline mean values in PI (P < 0.005) and GI (P < 0.001) in the test group as compared to the control group. At the end of the 2-month interval, significant reductions were observed in PI, PBI and PPD (P < 0.001). By the end of 3 months, there were significant differences in the mean reduction of all the parameters i.e. PI, PBI, GI and PPD (P < 0.001), between the test and control sites. In conclusion, 'Gamadent' toothpaste provided noteworthy benefits, producing statistically significant improvement in all clinical parameters compared to the placebo during the healing phase after conventional initial therapy.     

Dissemination and proliferation of neural stem cells on the spinal cord by injection into the fourth ventricle of the rat: a method for cell transplantation

We examined the distribution of hippocampus-derived neural stem cells on the spinal cord surface for up to 3 weeks following injection through the fourth ventricle. The injected cells were disseminated as tiny spots on the pia mater of the spinal cord and proliferated into large cell-clusters. On both the dorsal and ventral side, cell clusters increased in number rapidly up to 5 days after injection and thereafter decreased gradually due to the coalition of neighbouring clusters. Concomitantly, individual cell clusters continuously increased in size, occupying almost 50% of the spinal cord surface. Cell attachment was usually found around blood vessels, along which cells invaded into the spinal cord. In the injured site, cells migrated into the lesion and were integrated into the spinal cord tissue, some of which had differentiated into astrocytes 1-2 weeks after injection. BrdU-uptake experiments demonstrated that the transplanted cells proliferated within the host cerebrospinal fluid. These results indicate that application of neural stem cells through the ventricle is an effective method to disseminate cells all over the spinal cord and that they can migrate and be integrated into the injured spinal cord.     

The inherent characteristics and DNA polymorphism of Vibrio cholerae and other vibrios

Objective To investigate the inherent characteristics of Vibrio cholerae (V.cholerae) and other vibrios and their relationship.Methods Polymerase chain reaction (PCR), DNA sequence analysis, randomly amplified polymorphic DNA (RAPD) analysis and average linkage cluster analysis were used to study 3 isolates of V.cholerae strains O139, three isolates O1 biot ype El Tor, four isolates O1 biotype classical and 3 other vibrios.Results V.cholerae O139 contained the genomic sequences of ctx A2- B as well as V.cholerae O1.V.cholerae and others vibrios were divided into 4 groups by fingerprint patterns of RAPD, that is ① V.cholerae O139 and V.cholerae O1 El Tor; ② V.cholerae O1 classical; ③ V.para heamolyticus and V.vulnificus and ④ V.flluvialis.V.cholerae O139 DNA fingerprint of RAPD was consistent with the El Tor biotype: average linkage cluster distance was 0, and slightly different from the classical b iotype, with a distance of 2.07.It was much more different from vibrio par aheamolyticus and others, with a distance of 6.76-8.54Conclusion V.cholerae and other vibrios are polymorphic in inherent characteristics. The inherent characteristics of V.cholerae O139 are the same as El Tor b iotype.O139 may have evolved from the El Tor biotype.The inherent char acteristics of vibrio paraheamolyticus are the same as vibrio vulnificus.     

Comparison of techniques to reduce residential lead dust on carpet and upholstery: the new jersey assessment of cleaning techniques trial

High-efficiency particulate air (HEPA) filtered vacuum cleaners are recommended by the U.S. Department of Housing and Urban Development for cleaning lead-contaminated house dust. We performed a randomized field study to determine whether a conventional (non-HEPA) vacuum cleaner could achieve cleaning results comparable with those of a HEPA vacuum cleaner. We compared the lead loading reductions of these two vacuum cleaners in a total of 127 New Jersey homes of lead-exposed children. We used wet towelettes and a vacuum sampler to collect lead dust from carpets and upholstery before and after vacuum cleaning. The vacuum sampling data showed that the HEPA and non-HEPA vacuum cleaners resulted in 54.7% (p = 0.006) and 36.4% (p = 0.020) reductions in lead loading, respectively, when used on soiled carpets, although the overall difference in lead loading reduction between the two vacuum cleaners was not statistically significant (p = 0.293). The wipe sampling data did not show any significant lead loading reduction for either of the vacuum cleaners, suggesting that both vacuum cleaners fail to clean the surfaces of carpet effectively, considering that wipe sampling media simulate surface contact. On upholstery, the wipe sampling data showed a significant reduction in lead loading for the non-HEPA vacuum cleaner (22.2%, p = 0.047). Even with the significant reduction, the postcleaning lead loadings on upholstery were similar to those on carpets. The similar lead loading results for carpets and upholstery indicate that soiled upholstery may be as important a source of childhood lead exposure as carpets.     

散发性结直肠癌患者5号染色体杂合缺失分析

目的：探讨散发性结直肠癌患者5号染色体上与抑癌基因相关的杂合缺失（LOH）情况,并探讨新的抑癌基因位点,方法：对83例散发性结直肠癌患者基因组DNA,以15个不同荧光标记的高度多态性微卫星引物（平均遗传距离12．67cm)扩增相应的微卫星位点,用ABI PRISM 377测序仪进行基因扫描,统计各位点杂合缺失率。结果：在15个微卫星位点中,平均杂合缺失率为25．80％,5p中最高为D5S416,占48．15％,5q中最高为D5S471,占38．71％,D5S471周围的3个位点（D5S428,D5S2027 和 D5S2115）也存在高频的杂合缺失（＞30．00％）,结论：5号染色体上存在着高频的杂合缺失,其中5q13.3-31.1区域中,有与结直肠癌发生密切相关的APC,MCC,CTNNA1及IL家族等基因,而在5p15.1上的D5S416的杂合缺失率高达48．15％,此区域至今尚未发现与结直肠癌相关的基因位点,估计可能有未知的抑癌基因存在。     

前列腺癌E和N型钙粘附素的表达及意义

背景与目的：E－钙粘附素表达缺失与许多种癌密切相关,而最近在乳腺癌的研究中发现N－钙粘附素的反常表达在引起癌细胞的浸润及转移方面有着比E－钙粘附素缺失更为明显而直接的作用。本研究拟探讨前列腺癌中E和N－钙粘附素的表达与癌分级、分期及前列腺特异抗原（prostate specific antigen,PSA)的关系。方法：采用免疫组织化学染色法检测56例前列腺癌标本E和N－钙粘附素的表达。结果：E－钙粘附素阳性表达24例（43％）,阴性表达32例（57％）;N－钙粘附素表达阴性18例（32％）,阳性38例（68％）,E－钙粘附素表达缺失或N－钙粘附素阳性表达与肿瘤恶性程度及分期呈正相关（P均＜0．01）;与血清总PSA（T－PSA）和游离PSA（F－PSA）无明显相关性,而与F－PSA／T－PSA比值呈正相关（P＜0．01）。结论：E－钙粘附素和N－钙粘附素与前列腺癌的发生、发展明显相关,可以作为判断前列癌恶性程度及预后的指标。     

肿瘤细胞系血管内皮生长因子及其受体共表达的研究

背景与目的：血管内皮生长因子（vascular endothelial growth factor,VEGF)旁分泌在肿瘤血管新生中的作用已得到证实,但其自分泌作用尚不清楚。本研究的目的是分析VEGF及其受体（Flt-1和KDR）基因在恶性肿瘤细胞系中的共表达。方法：以看家基因为内标,采用半定量逆转录－聚合酶链反应分析VEGF及其受体基因在30种肿瘤细胞系和4种内皮细胞中的表达水平。结果：在29种肿瘤细胞系和3种内皮细胞系检测到中度以上的VEGF基因表达,而人脐静脉内皮细胞仅有低表达;Flt-1基因表达分别见于50％（6／12）的血液肿瘤,28％（5／18）的实体瘤细胞和2种内皮细胞;仅在16．7％（2／12）的血液肿瘤,33．3％（6／18）实体瘤细胞和2种内皮细胞检测到KDR基因表达;而ECV304细胞并无Flt-1或KDR基因的表达。结论：VEGF基因高表达是肿瘤细胞的重要特征,而VEGF及其受体共表达表明肿瘤细胞系中存在自分泌途径。     

应用抑制消减杂交技术筛选人肾癌差异表达新基因

背景与目的：认识肾癌差异表达基因有助于阐明肾癌发生,发展的分子机制。但至今有关肾癌差异基因尤其肾癌特异相关基因的研究仍不令人满意,本实验应用抑制消减杂交技术筛选入肾癌组织与正常肾组织间差异表达的新基因,以期克隆出新的肾癌特异相关基因。方法：以肾癌组织mRNA为检测对象（Tester)。正常肾组织mRNA为驱赶者（Driver)。构建cDNA消减文库,随机挑取文库克隆进行酶切及测序,所得结果在GenBank中做同源性比对分析。对感兴趣的片段进行电子定位确定其在染色体的位置,用Northern blot,半定量RT-PCR方法检测新基因在肾癌组织与正常肾组织中的差异表达。结果：文库包含414个阳性克隆;随机挑取280个克隆提取质粒并酶切分析,其中265个有插入片段;将其中80个克隆进行测序,初步显示28、158、170、249号4个克隆为新基因片段,电子定位表明上述4个基因分别位于染色体21q^22,4q^15.3,9q^34,22q^11.2。已在GenBank中登录（BM181083,BI784487,BI863835,BI863386）,对其中28、170号克隆用Northern杂交,半定量RT-PCR检测,证实新基因在肾癌组织中表达较正常肾组织显著增高。结论：抑制消减杂交技术是筛选,克隆肾癌差异表达新基因的有效手段;筛选到的新基因片段为进一步克隆其全长,研究基因功能提供了实验基础。