Genetic toxicology testing of Di(2-ethylhexyl) terephthalate

Di(2-ethylhexyl) terephthalate (DEHT) is a commercially produced chemical (Kodaflex® DOTP) that is used as a general purpose, low-volatility plasticizer for polyvinyl chloride and other polymeric materials. Less than 30 million kilograms of DEHT are produced annually. DEHT is isomeric with di(2-ethylhexyl) phthalate (DEHP), a nongenotoxic rodent carcinogen whose mode of action has been suggested to derive from its ability to produce hepatocellular proliferation and/or hepatic peroxisome proliferation. Thus it is important to know the behavior of DEHT in genotoxicity assays in order to compare it with that of DEHP and other phthalate ester plasticizers. It is known from previously published studies that rats fed DEHT in the diet at 2,000 mg/kg produce urine that is negative in the Ames Salmonella bacterial mutagenicity assay in the presence and absence of induced rat liver S-9 and in the presence and obsence of β-glucuronidase/aryl sulfatase. Reported here are the results of direct testing of DEHT in the Ames plate incorporation assay, the Chinese hamster ovary/hypoxanthine guanine phosphoribosyl transferase (CHO/HGPRT) in vitro mammalian cell mutagenicity assay, and an in vitro chromosome aberrations assay using CHO cells. The results for mono(ethylhexyl) terephthalate (MEHT), a metabolite of DEHT, in the Ames Salmonella bacterial mutagenicity assay are also presented. All test results for both DEHT and MEHT were found to be negative, and it is therefore concluded that DEHT, like its isomeric relative DEHP, is not genotoxic. © 1994 Wiley-Liss, Inc.     

Pigmentary changes in rat oral mucosa following antimalarial therapy

Pharmacogenic pigmentation of the oral mucosa has been reported following the use of a number of anti-malarial drugs. The nature and distribution of the pigment is inconclusive in the literature. The aim of the present study was to document pigment deposition within the oral mucosa of DA rats following prolonged chloroquine and pyrimethamine administration. The drugs were given as a combined dosage and separately to different groups via stomach gavage tube. After 12 weekly administrations the palatal mucosa was examined histochemically and ultrastructurally for changes in numbers and size of active melanocytes using the dopa-oxidase technique. The serum was analysed for changes in ACTH and testosterone levels. Morphometric analysis of cells incubated for dopa-oxidase showed a significant increase in the size of dopa positive cells with both drugs but an increase in the number of active melanocytes with chloroquine only. Serum levels of ACTH remained unchanged with both drugs but pyrimethamine caused an elevation in testosterone.     

New reference allelic ladders to improve allelic designation in a multiplex STR system

This paper reports the composition of a new reference allelic ladder mixture for use with a multiplex DNA profiling system consisting of six short tandem repeat loci. The loci included in this mixture are HUMTH01, D21S11, D18S51, D8S1179, HUMVWAF31/A, HUMFIBRA/FGA and an amelogenin sex test. Sequence analysis of individual ladder alleles was carried out and allelic designations made in accordance with the recommendations of the International Society of Forensic Haemogenetics (1992; 1994). A series of rare alleles which increase the range of alleles previously reported were identified. By including some of the rare alleles into the ladder marker system, we have significantly improved the ability to identify new alleles in unknown samples. Received: 12 August 1997 / Received in revised form: 7 November 1997     

Surfactant-induced cell toxicity and cell lysis. A study using B16 melanoma cells

The effects of a variety of detergents (non-ionic, ionic and bile derivatives) on B16 melanoma cells have been examined. Two main effects can be clearly differentiated: loss of cell viability and cell lysis. Under our conditions, cell-surfactant interaction is highly dependent on the nature of the amphiphile (more specifically, on its critical micellar concentration). Loss of cell viability occurs at surfactant concentrations below the critical micellar concentration, i.e. the incorporation of detergent monomers into the cell membranes is enough to impair their barrier function, so that Trypan Blue is no longer actively secreted outside the cell. On the other hand, cell lysis only occurs at or near the critical micellar concentration of the detergent, i.e. when the bilayer-micelle transition may take place. Comparative studies using B16 cells and phospholipid vesicles indicate that the amount of detergent required to induce cell lysis is the same that produces disruption of the lipid bilayer. Thus, our results suggest that membranes are the primary target for the toxicologic effects of surfactants on cells. Moreover, they provide a rationale for the interpretation of other studies in this field: previous results from different laboratories are shown to fit very well our data.     

p38丝裂原活化蛋白激酶在糖尿病大鼠神经病理性痛中的作用

目的探讨p38丝裂原活化蛋白激酶（p38MAPK）在链脲菌素诱导的糖尿病大鼠神经病理性痛中的作用。方法雌性Wistar大鼠31只，3月龄，体重180～220g，随机分为3组：对照组（C组，n=10）、糖尿病神经病理性痛组（D组，n=11）和p38MAPK抑制剂组（Ⅰ组，n=10）。D组、Ⅰ组单次腹腔注射链脲菌素65mg／kg制备糖尿病模型。糖尿病模型制备成功后，Ⅰ组尾静脉注射p38MAPK抑制剂SB203580 0．5mg／kg，1次／周，连续4周；C组和D组尾静脉注射等体积的生理盐水。给药4周后，测定机械缩足反应阈值（MWT）、左侧坐骨神经传导速率（NCV）、背根神经节（DRG）和脊髓的磷酸化p38MAPK水平。结果与C组比较，D组、Ⅰ组MWT下降，NCV减慢，伴有脱髓鞘现象，DRG和脊髓的磷酸化p38MAPK水平升高；与D组比较，Ⅰ组MWT升高，NCV增快，脱髓鞘程度减轻，DRG和脊髓的磷酸化p38MAPK水平下降。结论p38MAPK信号转导通路参与了糖尿病大鼠神经病理性痛的形成。     

The apical border plaque in chronic adult periodontitis. An ultrastructural study. I. Morphology, structure, and cell content.

THIS STUDY CONCERNS THE APICAL BORDER (AB) plaque in relation to chronic adult periodontitis (AP). Fifty-six teeth from 24 patients with AP were examined by transmission electron microscopy (TEM). The AB was not discrete with islands of bacteria in the so-called plaque-free zone (PFZ). Coronal to the AB, the established plaque commonly consisted of three to four layers of Gram-positive and Gram-negative cocci, rods, filaments, and spirochetes and a superficial layer, mainly of spirochetes, but including filaments, "test tube brush," and "corn-cob" formations. The most apical apparently intact organisms in the PFZ were in bacterial islands or in isolation and were predominantly Gram-negative cocci and rods, with occasional other morphotypes. The most apical microorganisms were invariably ghost cells. A cuticle of varying thickness and structure was present at the plaque/tooth interface. It was concluded that there was a limited range of intact bacterial morphotypes in the apical border plaque in chronic periodontitis.     

部分背根切断对备用背根节NT-3表达的影响

目的　探讨部分去背根后备用背根节 (L6 )各类细胞NT 3及其mRNA的含量变化。　方法　对成年雄性猫行单侧部分背根切断术 (切除一侧L1 ～L5,L7～S2 DRG ,保留L6 为备用根 )。取正常组一侧和术后 3d及 7d组手术侧的L6 DRG制作 2 0 μm厚冰冻切片 ,分别用NT 3抗体及NT 3cRNA探针行免疫组织化学及原位杂交染色。观察NT 3及其mRNA在DRG各类细胞的分布 ,测定NT 3及其mRNA在神经元和卫星细胞的光密度值 ,所得数据用q检验进行统计分析。　结果　部分去背根后 ,各时相备用背根节大神经元内NT 3的光密度值较正常者进行性减少 ,(P <0 0 5 ) ,而NT 3mRNA的光密度值术后 3d减少 ,7d回升至近正常者水平。比较之 ,小神经元和卫星细胞NT 3及其mRNA的光密度值进行性增多 (P <0 0 5 )。　结论　部分背根切断对备用背根节各类细胞NT 3表达的影响不同 ,其功能意义可能与NT 3参与脊髓Ⅱ板层可塑性有关     

甲氨喋呤对胶原诱导性关节炎大鼠滑膜骨桥蛋白和整合素αVβ3表达的影响

目的 探讨甲氨喋呤对胶原诱导性关节炎(collagen-induced arthritis,CIA)大鼠滑膜骨桥蛋白(osteopontin,OPN)及其受体整合素αvβ3表达的影响及其作用机制.方法 建立CIA大鼠模型,分为模型组和甲氨喋呤(MTX)组,后者用MTX进行干预治疗;采用免疫组织化学染色技术检测滑膜组织OPN和整合素αvβ3的表达,ELISA方法检测血清TNF-α水平.结果 ① CIA模型组和MTX组大鼠的滑膜OPN、整合素αvβ3表达均明显高于正常大鼠对照组(均为P<0.01);与模型组比较,MTX组OPN和整合素αVβ3的表达减少(均为P<0.01). ②正常对照组和MTX组大鼠血清TNF-α水平显著性低于模型组大鼠(均为P<0.01).结论 滑膜OPN和整合素αvβ3异常表达在CIA发病中具有重要意义.MTX通过下调滑膜OPN和整合素αvβ3的表达,降低血清TNF-α水平从而达到治疗CIA的作用.     

ETV6/RUNX1 fusion at diagnosis and relapse: some prognostic indications

This study was undertaken in order to compare the interphase and metaphase cytogenetics of 28 patients with ETV6/RUNX1 positive acute lymphoblastic leukemia, at diagnosis and relapse. The median time to relapse was 26 months. The significant fusion positive population heterogeneity revealed at interphase by a commercial probe for ETV6/RUNX1 fusion has not been described before. Six diagnostic samples had a single abnormal population; others had up to five each, which differed in the numbers of RUNX1 signals, and in the retention or loss of the second ETV6 signal. In contrast, the number of fusion signals was more constant. At relapse, there were fewer populations; the largest or unique clone was sometimes a re-emergence of a minor, diagnostic one, with a retained copy of ETV6 and the most RUNX1 signals. Abnormal, fusion negative clones were identified in bone marrow samples at extra-medullary relapse. Variant three or four-way translocations, which involved chromosomes 12 and 21, were prominent among the complex rearrangements revealed by metaphase FISH. The frequency of their occurrence at diagnosis and reappearance at relapse, sometimes accompanied by minor clonal evolution, was another new observation. Other recurrent cytogenetic features included a second copy of the fusion signal in six cases, partial duplication of the long arm of the X chromosome in two cases, and trisomy 10 in three cases. In comparing our data with previously reported cases, a picture is beginning to emerge of certain diagnostic features, which may provide circumstantial evidence of an increased risk of relapse.     

Localization of class i histocompatibility molecule assembly by subfractionation of the early secretory pathway

Class I molecules of the major histocompatibility complex bind peptides derived from cytosolic proteins and display them on the cell surface. This function alerts cytotoxic T cells to the presence of intracellular pathogens. Class I molecule assembly requires the association of the heavy chain with β₂-microglobulin, accompanied by peptide loading via specific transporters. This study localizes where these assembly steps take place, using monoclonal antibodies recognizing class I molecules in different assembly states to analyze subcellular fractions of the early secretory pathway. The distribution of peptide-loaded class I molecules was more localized than the distribution of the total pool of class I molecules in the early secretory pathway. Loaded molecules colocalized with the peptide transporter, free heavy chains, and the chaperone calnexin in high density rough endoplasmic reticulum (RER) membranes. These data suggest that subunit assembly and peptide acquisition occur at the same intracellular site. Class I molecules also localized to less dense subfractions of the early secretory pathway, which contained comparatively less peptide-loaded molecules than the high density RER fractions, at steady state. Following a 15 °C temperature block, class I molecules accumulated in these less dense membrane fractions, indicating that these fractions represent the intermediate compartment where empty class I molecules are trapped in mutant cells. In the presence of cycloheximide, a pool of class I molecules recycling to the RER was detected, suggesting empty molecules recycle to acquire peptide.