长春新碱诱导建立人结肠癌多药耐受性小鼠模型及MDR1和MRP1基因表达

目的建立人结肠癌多药耐受性动物模型并初步探索其耐药机制。方法结合体内外诱导方法建立人结肠癌多药耐受性动物模型,利用VCR和CTX的肿瘤抑制实验评价其MDR特性;利用real-time PCR和West-ern blotting等方法分析其P-gp/MDR1和MRP1基因和蛋白的表达。结果肿瘤抑制实验结果显示,MDR和敏感型结肠癌模型的肿瘤生长速度差异不显著,MDR结肠癌动物模型对于VCR和CTX的耐药性均有较大程度的提高;表达分析结果显示,人结肠癌MDR动物模型的P-gp/MDR1表达水平有较大提高,而MRP1表达没有显著变化。结论人结肠癌多药耐受性动物模型具有较好的多药耐受性,其多药耐受性表型主要是由于P-gp/MDR1过量表达所导致。     

三种啮齿类动物非酒精性脂肪肝形成及机制探讨

目的 分析物种差异对NAFLD模型复制的影响,探讨不同鼠种NAFLD形成及其机制.方法 长爪沙鼠、SD大鼠、ICR小鼠各20只,按种属随机分为对照组及模型组,对照组给予普通饲料,模型组给予高脂饲料.16周后,观察肝脏HE及Mallory三色染色病理变化,计算肝指数,检测血清血脂(CHO、TG、LDL-c、HDL-c)、肝功能(GOP、GPT)及肝组织中抗氧化酶(SOD、GSH-PX、CAT)活性及羟脯氨酸(Hyp)、丙二醛(MDA)、游离脂肪酸(FFA)水平.结果 与对照组比较,各模型组:沙鼠Hyp、CHO、TG、LDL-c、HDL-c、肝指数、GOP、GPT、MDA、FFA均升高,SOD、GSH-PX、CAT活性降低(P＜0.05,P＜0.01),肝脏出现纤维化;大鼠CHO、肝指数、GOP、GPT、FFA、SOD活性升高,MDA含量、GSH-PX、CAT活性降低(P ＜0.05,P＜0.01),有局灶性脂肪肝炎;小鼠CHO、LDL-c、HDL-c、肝指数、CAT活性升高,MDA含量降低(P ＜0.05,P＜0.01),肝脏病理正常.结论 三种动物在脂质代谢、肝功能、氧化应激等方面有显著的差异,并形成了不同的NAFLD模型:沙鼠形成伴高TG、CHO血症的肝纤维化模型、大鼠形成伴高CHO血症的局灶性脂肪肝炎模型、小鼠形成高胆固醇血症模型但肝脏未发生明显的病理改变.     

黑线毛足鼠年龄和种群密度与肝毛细线虫感染率的关系

2004—2005年,在内蒙古锡林郭勒盟阿巴嘎旗和东乌珠穆沁旗研究了肝毛细线虫病对黑线毛足鼠种群感染情况,分析肝毛细线虫对黑线毛足鼠的感染率与鼠体年龄以及种群密度的关系。结果表明,黑线毛足鼠达到一定的年龄(或体质量)才可感染肝毛细线虫病,最低感染个体体质量为14.6g。肝毛细线虫对低龄鼠的感染检出率比较低,而对成体鼠感染检出率较高,其感染率和感染度均随着个体年龄的增长而增高(感染率与年龄:r=0.97,P<0.05;感染度与年龄:r=0.93,P<0.05)。此外,黑线毛足鼠体质量与肝毛细线虫感染率和感染度也存在显著的相关关系(感染率与体质量:r=0.99,P<0.05;感染度与体质量:r=0.95,P<0.05),黑线毛足鼠的种群密度则对肝毛细线虫的感染率(r=0.27,P>0.05)和平均感染度(r=0.41,P>0.05)没有明显的影响,其感染率可能与地区不同有关。     

Assessment of organochlorine pesticides and metals in ring‐tailed lemurs (Lemur catta) at Beza Mahafaly Special Reserve,Madagascar

Like most of Madagascar's endemic primates, ring‐tailed lemurs (Lemur catta) face a number of threats to their survival. Although habitat loss is of greatest concern, other anthropogenic factors including environmental contamination may also affect lemur health and survival. In this study, we examined ring‐tailed lemurs from the Beza Mahafaly Special Reserve (BMSR), southern Madagascar for exposure to organochlorine (OC) pesticides and metals and examined differences in contaminant concentrations between sexes and among age groups, troops, and habitats. A total of 14 pesticides and 13 metals was detected in lemur blood (24 individuals) and hair (65 individuals) samples, respectively. p,p′‐DDT, heptachlor, aldrin, heptachlor epoxide, endrin aldehyde, and endrin were among the most prevalent pesticides detected. Surprisingly, the persistent metabolite of p,p′‐DDT, p,p′‐DDE, was not detected. The most commonly detected metals were aluminum, zinc, boron, phosphorus, silicon, and copper, whereas metals considered more hazardous to wildlife (e.g. arsenic, cadmium, lead, selenium, vanadium) were not found above detection limits. Overall, concentrations of OC pesticides and metals were low and similar to those considered to be background concentrations in other studies examining the ecotoxicology of wild mammals. Few inter‐sex, ‐age, ‐troop, and ‐habitat differences in contaminant concentrations were observed, suggesting a uniform distribution of contaminants within the reserve. Several statistically significant relationships between lemur body size and contaminant concentrations were observed, but owing to the lack of supportive data regarding contaminant exposure in wild primates, the biological significance of these findings remains uncertain. Results of this study document exposure of ring‐tailed lemurs at BMSR to multiple OC pesticides and metals and provide essential baseline data for future health and toxicological evaluations of lemurs and other wild primates, especially those in regions with expanding agricultural and mining operations. Am. J. Primatol. 71:998–1010, 2009. © 2009 Wiley‐Liss, Inc.     

DNA damage, homology-directed repair, and DNA methylation

To explore the link between DNA damage and gene silencing, we induced a DNA double-strand break in the genome of Hela or mouse embryonic stem (ES) cells using I-SceI restriction endonuclease. The I-SceI site lies within one copy of two inactivated tandem repeated green fluorescent protein (GFP) genes (DR-GFP). A total of 2%–4% of the cells generated a functional GFP by homology-directed repair (HR) and gene conversion. However, ~50% of these recombinants expressed GFP poorly. Silencing was rapid and associated with HR and DNA methylation of the recombinant gene, since it was prevented in Hela cells by 5-aza-2′-deoxycytidine. ES cells deficient in DNA methyl transferase 1 yielded as many recombinants as wild-type cells, but most of these recombinants expressed GFP robustly. Half of the HR DNA molecules were de novo methylated, principally downstream to the double-strand break, and half were undermethylated relative to the uncut DNA. Methylation of the repaired gene was independent of the methylation status of the converting template. The methylation pattern of recombinant molecules derived from pools of cells carrying DR-GFP at different loci, or from an individual clone carrying DR-GFP at a single locus, was comparable. ClustalW analysis of the sequenced GFP molecules in Hela and ES cells distinguished recombinant and nonrecombinant DNA solely on the basis of their methylation profile and indicated that HR superimposed novel methylation profiles on top of the old patterns. Chromatin immunoprecipitation and RNA analysis revealed that DNA methyl transferase 1 was bound specifically to HR GFP DNA and that methylation of the repaired segment contributed to the silencing of GFP expression. Taken together, our data support a mechanistic link between HR and DNA methylation and suggest that DNA methylation in eukaryotes marks homologous recombined segments.     

Specific dechlorinase activity in lindane degradation by Streptomyces sp. M7

Synthesis of dechlorinase in Streptomyces sp. M7 was induced when the microorganism was grown in the presence of lindane (γ-hexachlorocyclohexane) as the only carbon source. Activity of cells grown with lindane was about four and half times higher compared to cells grown with glucose. Maximum dechlorinase activity was observed at 30°C in alkaline conditions pH (7.9) and the enzyme did not show cation dependency. Sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed one differential band with a molecular weight similar to serum albumin (M _r 66,200), which corresponded to polynucleotide phosphorylase, an enzyme that plays an important role in the regulation system and could be involved in the regulation of the dechlorinase gene. Detected in cell-free extracts were γ-pentachlorocyclohexene and 1,3,4,6-tetrachloro-1,4-cyclohexadiene, both being products of the dechlorinase activity. This is the first time that the presence of an enzyme with dechlorinase activity has been demonstrated in an actinomycete strain isolated in Tucumán, Argentina. Characteristics of this enzyme revealed that Streptomyces sp. M7 could be useful in the future in bioremediation of soil or as a biosensor.     

Reporting of Quantitative Protein Electrophoresis in Australia and New Zealand: a Call for Standardisation

Background

The lack of guidelines on reporting standards for protein electrophoresis may have led to significant differences in reports from different laboratories.

Objective

To determine the extent of variation in reporting of protein electrophoresis results in Australia and New Zealand.

Method

Questionnaires were distributed to laboratories throughout Australia and New Zealand asking about protein electrophoresis practices and reporting.

Results

Extensive variation was found in the following reporting practices: (a) units for urine Bence Jones protein (BJP); (b) reporting absence of a paraprotein rather than a normal pattern; (c) numerical reporting of all protein fractions or only the paraprotein; (d) warning of possible inaccuracy in the serum immunoglobulin result of the paraprotein type; (e) co-migration of a paraprotein with a normal serum protein; (f) use of a confirmatory test when a known paraprotein is no longer detectable.

Conclusions

A working party should be established to make recommendations on the reporting of protein electrophoresis. Implementation of such recommendations should reduce both report variation between laboratories and the risk of misinterpretation of reports.     

Cell cycle related proteins in hyperplasia of usual type in breast specimens of patients with and without breast cancer

Background  

Hyperplasia of usual type (HUT) is a common proliferative lesion associated with a slight elevated risk for subsequent development of breast cancer. Cell cycle-related proteins would be helpful to determine the putative role of these markers in the process of mammary carcinogenesis. The aim of this study was to analyze the expression of cell cycle related proteins in HUT of breast specimens of patients with and without breast cancer, and compare this expression with areas of invasive carcinomas.