Dose dependency of γ-H2AX formation in the rat urinary bladder treated with genotoxic and nongenotoxic bladder carcinogens

We previously reported that immunostaining for γ-H2AX, a biomarker of DNA damage, in the rat urinary bladder is useful for early detection of bladder carcinogens in 28-day toxicity studies. Here, we aimed to examine the dose dependency of γ-H2AX formation in the urinary bladder of rats. Male F344 rats (aged 6 weeks) were orally administered N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN; 0%, 0.0001%, 0.001%, 0.01%, 0.02%, or 0.05% in drinking water), a genotoxic bladder carcinogen, and melamine (0%, 0.3%, 1.0%, or 3.0% in the diet), a nongenotoxic bladder carcinogen, for 2 days or 4 weeks. Immunohistochemical analysis showed that γ-H2AX- and Ki67-positive epithelial cells in the bladder urothelium were significantly increased, with a clear dose dependency, in both BBN- and melamine-treated groups. Additionally, γ-H2AX formation was detected from the lower-dose group, without increased Ki67 expression or histopathologic findings. The ratios of γ-H2AX-positive cells at week 4 in both BBN- and melamine-treated groups were higher than those on day 2, indicating the time-dependent increase in γ-H2AX formation. Immunofluorescence double-staining revealed that γ-H2AX single-positive cells without Ki67 expression were often found in the urothelium of BBN-treated rats, whereas most γ-H2AX-positive cells were Ki67-positive in the melamine group. Our results demonstrated that γ-H2AX formation in the urinary bladder increased in a clear dose-dependent manner and that γ-H2AX immunostaining has the potential to detect bladder carcinogens after a 2-day administration. Furthermore, the association of genotoxic mechanisms in bladder carcinogenesis could be determined by analyzing the colocalization of γ-H2AX and Ki67 in the urothelium.     

In vitro cytotoxicity and morphological assessment of smoke from polymer combustion in human lung derived cells (A549)

The application of polymer and composites in building and modern transport interiors raises concerns of potential health hazards during combustion. Cytotoxicity and morphological assessment of smoke from polymer combustion in human lung derived cells (A549) has been investigated. A laboratory scale vertical tube furnace was used for the generation of combustion products. A range of materials used in the building and transport industry including high density-polyethylene (HDPE), polypropylene (PP), polycarbonate (PC), and polyvinyl chloride (PVC), fiberglass reinforced polymers (FRPs), and melamine faced plywood (MFP) were studied. The exposure of combustion toxicants to human lung cells (A549) at the air/liquid interface was acquired using a Harvard Navicyte Chamber. Cytotoxic effects on human cells were assessed based on cell viability using a selected in vitro cytotoxicity assays, including NRU (neutral red uptake) and ATP (adenosine triphosphate). Morphological assessment on the effects of combustion products in human lung cells from selected materials including PVC, FRP and MFP was assessed using scanning electron microscopy (SEM). The volatile organic compounds from thermal decomposition products were identified using ATD-GCMS (Automatic Thermal Desorption Gas Chromatography Mass Spectrometry). NOAEC (No Observable Adverse Effect Concentration), IC(10) (10% inhibitory concentration), IC(50) (50% inhibitory concentration), and TLC (Total Lethal Concentration) values (mg/l) were generated. The following toxicity ranking was observed from the most toxic material to the least toxic using the NRU assay: PVC>PP>HDPE>PC >FRP-10>MFP>FRP-16; and the ATP assay: PVC>HDPE>PP>FRP-10>FRP-16>MFP>PC. The method described here could potentially be an alternative to current fire toxicity standards.     

三聚氰胺对SD胎鼠肾脏致病性研究

目的:研究三聚氰胺在SD大鼠胚胎发育过程中对胎鼠肾的致病性.方法:将加只SD孕鼠随机分为4个三聚氰胺组和1个对照组,用浓度分别为360、480、600、720mg/(kg·d)三聚氰胺悬液连续灌胃,对照组灌胃2ml蒸馏水.生产后采用ELISA法检测新生鼠血液和肾脏中三聚氰胺含量,常规HE染色观察新生鼠肾组织的病理变化....     

三聚氰胺污染奶粉致双肾结石婴幼儿2年后随访分析

目的：探讨三聚氰胺污染奶粉致双肾结石对婴幼儿生长发育的影响。方法：对2008年7～10月治疗的50例三聚氰胺双肾结石患儿（双肾结石组）进行2年后随访。随访包括泌尿系超声检查、肾功能检查、尿常规,同时记录身高、体重、临床症状及并发症情况。选取50例无三聚氰胺污染奶粉喂养史的正常儿童作为对照组,比较两组间的相关参数差异。结果：41例患儿得到成功随访。28例带石出院患儿中21例结石消失,5例变小,1例无明显变化,另1例变大。15例出院时仍有双侧或单侧肾积水患儿中9例消失,5例减轻及1例无明显变化。双肾结石组患儿补钙的比例明显低于对照组（P〈O．05）,身高偏低的比例明显高于对照组（P〈O．05）,体重差异无统计学意义（P〉O．05）。随访时未发现泌尿系占位性病变。结论：三聚氰胺污染奶粉致双肾结石患儿2年后随访显示,泌尿系统发育及生长发育未见明显影响。     

Timing and route of exposure affects crystal formation in melamine and cyanuric exposed male and female rats: Gavage vs. feeding

Effects of the dosing matrix and timing on the onset of renal crystal formation were evaluated in male and non-pregnant female rats (Fisher 344) exposed to both melamine (MEL) and cyanuric acid (CYA) for 28 days. Rats were fed ground feed containing 60 ppm MEL and 60 ppm CYA, (5 mg/kg bw/day equivalent), or exposed via oral gavage to carboxymethylcellulose containing 5 mg/kg bw MEL followed by 5 mg/kg bw CYA either consecutively (<1 min apart) or delayed 45 min after MEL. Staggered gavage exposure to MEL/CYA caused extensive renal crystal formation as compared to when the two compounds were administered consecutively or in feed. Treatment related effects included reduced weight gain, feed consumption, and testicular weight and increased kidney weight, water consumption and urine output. Animals from the staggered MEL/CYA gavage exposure group became ill and were removed after 9 days of exposure. Approximately 1 week after the initiation of exposure microscopic urinalysis revealed MEL/CYA crystals in both groups of gavaged animals but not in the MEL/CYA feed treatment groups. Urinary crystals were smaller (10 μm) in animals consecutively gavaged. In contrast the urinary crystals were larger (20–40 μm) and frequently clumped in the animals in the staggered gavage group.     

Depletion of melamine and cyanuric acid in serum from catfish Ictalurus punctatus and rainbow trout Onchorhynchus mykiss

Melamine and its triazine analogs, such as cyanuric acid, have been used to artificially inflate protein content both in animal feed ingredients, as well as in milk products produced for human consumption. We report here a LC–MS/MS method to quantify and confirm melamine and cyanuric acid in serum from channel catfish and rainbow trout with a limit of quantification of 0.8 μg/mL. The method was applied to serum samples from a residue depletion study in which fish were given a single oral dose of 20 mg/kg body weight melamine, cyanuric acid, or both compounds together. Samples were taken at 1, 3, 7, 14, and 28 days (an additional 42 day was added for trout). When given alone or in combination with cyanuric acid, melamine residues were highest on day 1 in both catfish and trout. Cyanuric acid was only quantifiable at day 1 in trout when given alone, and not at all in catfish. The serum half life of melamine in catfish was 1.50–1.62 days and 3.09–3.67 days in trout. This work highlights the differences of depletion kinetics in fish, which can be measured in days, as compared to the depletion in mammals, measured in hours.     

不同剂量化学纯三聚氰胺诱发SD大鼠尿结石的比较

目的:探讨建立不合并肾损害的尿结石模型。方法:100只雄性SD大鼠,随机分5组,空白对照组、化学纯三聚氰胺0.4～0.7 g.kg-1.d-1组,连续给药20,30 d,观察比较结石形成率、肾功能损害情况。结果:0.4,0.5 g.kg-1.d-1化学纯三聚氰胺给药20,30 d,膀胱结石率最高,20 d分别为60%,50%,30 d分别为50%,60%,两组及与0.6,0.7 g.kg-1.d-1组、空白对照组比较有显著性差异(P<0.05);膀胱结石形成率与剂量、时间不成线形关系;各组比较仅0.4 g.kg-1.d-1组肾和膀胱指数、肌酐、尿素氮、尿酸与空白对照组比较,无显著性差异。结论:化学纯三聚氰胺0.4 g.kg-1.d-1给药20 d对肾脏几乎不造成损害,SD大鼠膀胱结石率达60%,可建立不合并肾损害的尿结石模型。     

三聚氰胺对大鼠肾脏毒性损害的超声表现与病理所见的对照研究

目的喂食大鼠含三聚氰胺的饲料后观察其肾脏损害的超声表现与病理所见。方法 SD大鼠随机分为两组,每组20例,第1组为正常对照组,给予正常维持鼠料20天;第2组为研究组,喂食掺有三聚氰胺的鼠料20天。每组完成饲养后先做超声检查,观察大鼠肾脏的形态、大小、皮质厚度、实质回声情况及肾内是否有结石形成,然后留取尿液、静脉血做相关检验,最后解剖大鼠,留取双侧肾脏标本,使用福尔马林浸泡,待病理切片观察。结果正常对照组超声表现、生化结果及病理所见未见异常改变。研究组超声显示20只大鼠的40个肾脏实质部回声增强,肾内均可见散在多发的细小强回声结石影,较大者位于集合系统内,伴有声影;8个肾脏出现积水;实验室检查,研究组所有大鼠均出现结晶尿,液相色谱仪检测均检出三聚氰胺、三聚氰酸和尿酸成分;20只大鼠尿素升高,10只肌酐增高,14只出现二氧化碳结合率降低;研究组有不同程度病理损害,典型表现有肾组织广泛淤血伴灶性出血,肾小管伴有点状坏死及成纤维细胞增生,数个肾小管内可见黄绿色针状扇形排列结晶体,相应肾小管扩张,部分区域间质内可见淋巴细胞浸润。结论三聚氰胺可引起大鼠肾脏病理损害,并可导致结石形成,沉积于肾脏,造成肾损害,在超声图像上有相应表现。     

食用受三聚氰胺污染婴幼儿奶粉致婴幼儿泌尿系统结石病例的流行病学特征

目的掌握受三聚氰胺污染婴幼儿奶粉所致泌尿系结石的流行病学特征,为制定防治对策提供科学依据。方法根据医院提供的病儿信息搜索调查对象,通过入户调查和医院调查相结合的方法,按统一调查表进行调查,采用描述流行病学方法,分析患儿性别、年龄、地区分布、喂养史及B超检查等流行病学调查指标。结果调查335例患儿,男女性别比为。平均年龄：36月龄以下的患儿占。分布在全市7个县区,均有奶制品喂养史,其中食用＂三鹿＂品牌294人,占87.76%;从出生开始吃153人,占45.67%;0～12月龄发病146人,占43.58%。结论 3岁以下的泌尿系结石患儿均有奶粉喂养史,开始吃奶粉年龄越小,越容易得结石;发病年龄以0～12月龄为主。     

三聚氰胺污染奶粉致泌尿系结石的logistic回归分析

【摘要】 目的 通过对三聚氰胺污染奶粉致泌尿系结石的流行病学调查,探讨该病发生的危 险因素,为预防该病提供比较可靠的依据。方法 采用1:2配对病例对照研究,26例三聚氰 胺污染奶粉致泌尿系结石患儿为研究对象,以性别为匹配因素,且年龄相差不超过1岁的三 聚氰胺非泌尿系结石者为对照组。自制调查问卷,进行单因素及多因素条件logistic回归分 析。结果 一级亲属泌尿系结石史、婴儿期污染奶粉喂养史及服用钙剂OR值分别为12.321、 6.792、3.454,饮水OR值为0.359。结论　一级亲属泌尿系结石史、婴儿期污染奶粉喂养史、 及服用钙剂为危险因素,饮水为保护因素。