幼儿舌脱落细胞形态与口气关系的研究分析

目的：比较分析高口气值组和低口气值组幼儿舌脱落细胞形态计量学参数及分类计数上的差异,探讨口气是否影响舌粘膜上皮细胞的角化、凋亡过程。方法：3—5岁幼儿40名,其中高口气值纽幼儿20名,低口气值纽幼儿20名,取舌背中1／3脱落细胞,制作细胞涂片、H．E染色。应用计算机图像分析系统对舌脱落细胞进行形态计量学检测和分类计数。结果：高口气值组幼儿的舌脱落细胞的各类细胞的细胞形态较低口气值组幼儿小,且细胞核也更小。中层细胞、完全角化细胞计数在两组间的差异无统计学意义（P〉0．05）,高口气值组角化前细胞计数明显高于低口气值纽（P〈0．01）,而高口气值组不全角化细胞计数明显低于低口气值组（P〈0．01）。结论：高口气值组幼儿的舌脱落细胞较小,细胞角化程度较低,凋亡速度较慢。     

白花蛇舌草对人胃癌细胞MNK-45线粒体膜电位及凋亡相关基因表达的影响*

目的: 探讨白花蛇舌草(注射液)对人胃癌细胞MNK-45线粒体膜电位及凋亡相关基因表达的影响。方法: 将人胃癌细胞MNK-45分成4组,每组设置3个复孔,对照组为未加入白花蛇舌草的MNK-45细胞,3组实验组分别加入终浓度为20、30、40 μg/ml白花蛇舌草的MNK-45细胞,各组在5％的CO₂培养箱中孵育48 h后,利用激光共聚焦显微镜下观察细胞形态变化,流式细胞术检测线粒体膜电位,qRT-PCR检测Cytochrome C (Cyt c)、caspase3和caspase9基因的表达变化,Western blot检测Cytochrome C (Cyt c)、caspase3和caspase9蛋白的表达变化。结果: 与对照组相比,终浓度为20、30、40 μg/ml的各白花蛇舌草处理组,其MNK-45细胞的线粒体膜电位均明显降低(P＜0.01),Cyt c、caspase3和caspase9的基因表达均明显上调(P＜0.01)、蛋白表达也均显著升高(P＜0.05或 P＜0.01),40 μg/ml的白花蛇舌草处理组的表现最佳。结论: 在终浓度为20~40 μg/ml的范围内,白花蛇舌草能够降低人胃癌MNK-45细胞线粒体膜电位, 诱导细胞凋亡,并可上调Cyt c、caspase3和caspase9基因表达。     

葡萄糖对体外培养椎间盘髓核细胞的影响

目的:探讨葡萄糖对体外培养髓核细胞的生物学特性的影响。方法:酶消化法分离培养正常椎间盘髓核细胞。对照组:DF12+20%FBS培养液(葡萄糖浓度1000mg/L)、无糖组:无糖DMEM+20%FBS(葡萄糖浓度0mg/L)培养液培养髓核细胞。HE染色观察细胞形态变化,计数板计数细胞总数,台盼蓝染色计算髓核细胞活性比率,流式细胞仪检测细胞凋亡率,Hoechst33258染色观察凋亡细胞核的变化。结果:两组培养液培养细胞形态大体正常,并无明显变化。对照组细胞总数明显多于无糖组。细胞活性率对照组也高于无糖组。Hoechst33258染色凋亡细胞,凋亡细胞核内可见致密的颗粒状和块状荧光,细胞核形态不规则,少数细胞核碎裂,部分细胞核呈月牙形。结论:葡萄糖对椎间盘髓核细胞的增殖及凋亡有显著的影响。     

十八碳二烯酸对神经胶质瘤细胞增殖与凋亡的影响及其机制

目的:探索十八碳二烯酸(ODA)抑制神经胶质瘤细胞增殖与促凋亡作用及其机制。方法:取培养的人神经胶质瘤细胞(细胞密度2×10⁶ cells/L)分为溶剂对照组(给予DMSO,含量为30μl/L)、5-FU组(含量10 mg/L)和十八碳二烯酸组(设0.3、0.6、1.2 mg/L三个剂量组)。用台盼蓝、噻唑蓝(MTT)检测ODA对神经胶质瘤细胞的毒性作用,用酶联免疫吸附法(ELISA)检测神经胶质瘤细胞P53、PI3K、P21、PKB/Akt、caspase-9蛋白表达水平。结果:(1)光学显微镜细胞计数显示：ODA低、中、高剂量组和5-FU组细胞增殖抑制率比溶剂对照组显著升高(P<0.01),与5-FU组相比差异无统计学意义(P>0.05)。(2)MTT检测结果显示：与溶剂对照组相比,ODA低、中、高剂量组和5-FU组细胞增殖抑制率显著升高(P<0.01);与5-FU组相比,仅ODA高剂量组细胞增殖抑制率显著增加(P<0.01)。(3)流式细胞仪检测结果显示：与溶剂对照组相比,ODA低、中、高剂量组和5-FU组G₀/...     

纳米ZnO对人肺上皮细胞BEAS-2B细胞增殖和凋亡的影响

目的:探讨纳米ZnO对人肺上皮细胞BEAS-2B细胞增殖、凋亡的影响及分子机制。方法:用终浓度为3、6、12μg/ml的纳米ZnO处理BEAS-2B细胞12 h和24 h,对照组未加入纳米ZnO,各设3复孔,CCK-8法检测细胞活力,分析半致死浓度。筛选3、6μg/ml纳米ZnO处理BEAS-2B细胞24 h,各设3复孔,倒置显微镜观察细胞形态,Hochest33342染色观察细胞核,AO染色及扫描电镜观察细胞凋亡形态,流式细胞术检测活性氧水平、细胞周期进程、细胞凋亡;Western blot检测Bcl-2、Bax蛋白表达水平。结果:与对照组相比,纳米ZnO处理组细胞活力显著下降(P<0.01),处理24 h时IC₅₀为6.13μg/ml;纳米ZnO处理细胞24 h后,3μg/ml和6μg/ml组的活性氧水平显著升高(P<0.05,P<0.01)。6μg/ml处理组细胞周期阻滞于G2/M期、染色质固缩凝集、出现凋亡小体、细胞凋亡率显著增加(P<0.01)、Bcl-2蛋白表达显著降低(P<0.05)、Bax蛋白表达显著升高(P<0...     

长爪沙鼠发情周期规律与判定方法

目的研究长爪沙鼠发情周期,揭示发情规律,优化判定方法。方法连续18 d采集50只长爪沙鼠阴道上皮脱落细胞涂片,采用角化细胞计数法研究长爪沙鼠发情周期规律。比较瑞氏染色、HE染色和直接镜检判定发情周期4个时相的优缺点。结果长爪沙鼠的发情周期有稳定型、不稳定型、假孕三种类型。其中稳定型占68.6%,发情周期为(106.3±35.0)h,可分为4个时相。4个时相角化细胞的比例分别为发情前期(13.5±7.8)%、发情期(86.7±9.9)%、发情后期(27.9±12.8)%和发情间期(3.3±2.8)%。结论角化细胞计数能准确地判定长爪沙鼠的发情周期及各个时相。直接镜检法能快速反映阴道脱落细胞的形态。     

变应性鼻炎鼻黏膜组织重塑的研究及转化生长因子β1 在鼻黏膜中 的表达*

目的:探讨变应性鼻炎(allergic rhinitis AR)鼻黏膜组织是否存在重塑并检测与组织重塑密切相关的转化生长因子β1(TGF-β1)在AR患者鼻黏膜组织中的表达及意义。方法:取健康自愿者、轻度间歇性AR患者、重度持续性AR患者的中鼻甲黏膜组织各10例。苏木素伊红(HE)染色法观察嗜酸细胞浸润并测定上皮损伤情况;阿辛蓝-过碘酸-希夫(AB-PAS)染色法计数杯状细胞数;三色胶原(MT)染色测定细胞外基质沉积面积百分比。酶联免疫吸附试验(ELISA)测定组织中TGF-β1的表达。结果:①对照组无明显嗜酸细胞浸润,两鼻炎组较多嗜酸细胞浸润(P<0.01),②轻度AR组中仅上皮细胞损伤1级比对照组明显(P<0.01),重度AR组上皮损伤1、2、3级均比对照组明显(P<0.01),③两鼻炎组杯状细胞数明显多于对照组(P值均<0.01),④与对照组相比,轻度AR组胶原沉积面积增多,但无统计学意义(P>0.05),重度AR组明显增多(P<0.01),⑤TGF-β1在两鼻炎组黏膜中的表达均比对照组显著增高(P<0.01);重度AR组TGF-β1的表达均比轻度AR组增高,具有统计学意义(P<0.05)。结论:AR的鼻黏膜组织发生了重塑,表现为:上皮细胞损伤,杯状细胞化生,细胞外基质沉积,重度AR患者的鼻黏膜重塑更强,更广泛。TGF-β1积极参与了AR鼻黏膜组织的重塑过程。     

二苯乙烯苷抑制过氧化氢诱导的人脐静脉内皮细胞凋亡

目的:研究二苯乙烯苷(TSG)对过氧化氢(H2O2)诱导人脐静脉内皮细胞(HUVECs)凋亡的保护作用。方法:运用四甲基偶氮唑盐还原法(MTT法)和流式细胞术筛选建立细胞凋亡模型的H2O2合适浓度以及检测不同浓度TSG对H2O2诱导HUVECs的增殖率和凋亡率;Hoechst33258染色观察细胞凋亡形态。结果:MTT及流式法筛选300μmol/L为H2O2作用于细胞的最适凋亡浓度。MTT和流式结果显示,与H2O(2300μmol/L)损伤组比较,10μmol/L与100μmol/LTSG预处理组细胞的增殖率增加(P<0.05),凋亡率显著降低(P<0.01);Hoechst33258染色观察TSG能降低H2O2诱导的细胞凋亡,使细胞凋亡数减少。结论:TSG能抑制H2O2诱导的HUVECs凋亡,从而起到保护血管内皮细胞的作用。     

氨磷汀对氧糖剥夺引起的PC12 细胞缺血再灌注损伤的保护作用研究

目的:研究氨磷汀对体外培养的神经元样细胞的缺血再灌注损伤的保护作用,为其最终用于临床脑缺血的治疗打下基础。方法:体外培养的PC12细胞氧糖剥夺4h后复氧复糖,给予不同浓度的氨磷汀处理,20h后镜下观察细胞形态学变化,用MTT和LDH检测细胞活力和损伤情况,免疫荧光染色观察凋亡细胞,流式细胞仪计数凋亡细胞的比例。结果:高浓度氨磷汀对正常PC12细胞活力有抑制作用(P<0.05),而低浓度则无。氨磷汀可以提高缺血再灌注损伤PC12细胞活力(P<0.05),减少LDH释放(P<0.05),保护细胞正常形态,抑制细胞凋亡(P<0.05)。结论:氨磷汀对氧糖剥夺引起的神经元样细胞的缺血再灌注损伤具有保护作用。     

热疗联合奥沙利铂对SW480细胞增殖和凋亡的影响

目的:观察奥沙利铂联合热疗对人结肠癌细胞SW480增殖及凋亡的影响,确定联合用药的效果,为临床方案提供参考。方法:采用MTT(四唑盐)法检测热疗、奥沙利铂及联合用药对细胞增殖的影响;瑞士吉姆萨染色法观察细胞形态;流式细胞仪检测细胞凋亡和周期;Western blot检测Bax、Bcl-2以及Caspase8蛋白表达量变化;q PCR检测Bax、Bcl-2以及Caspase8 m RNA的积累。结果:热疗联合奥沙利铂可以显著抑制细胞增殖,与对照组相比,热疗组、化疗组、联合组细胞凋亡率分别为16.2%、20.5%和36.1%,具有显著性差异(P0.01);细胞学形态中,热疗组细胞发生皱缩,化疗组细胞膜破裂;化疗将细胞阻滞在G2/M期,热疗和联合组将细胞阻滞S期;Western blot和qPCR显示Bax/Bcl-2比值上升,Caspase8表达量增加,联合组三种蛋白的表达量均与对照组具有显著性差异(P0.01)。结论:热疗联合奥沙利铂可以显著促进细胞凋亡,提高治疗效果,为结肠癌的治疗提供参考。     

Volatile sulphur compounds and pathways of L-methionine catabolism in Williopsis yeasts

Volatile sulphur compounds (VSCs) are important to the food industry due to their high potency and presence in many foods. This study assessed for the first time VSC production and pathways of L: -methionine catabolism in yeasts from the genus Williopsis with a view to understanding VSC formation and their potential flavour impact. Five strains of Williopsis saturnus (var. saturnus, var. subsufficiens, var. suavolens, var. sargentensis and var. mrakii) were screened for VSC production in a synthetic medium supplemented with L: -methionine. A diverse range of VSCs were produced including dimethyl disulphide, dimethyl trisulphide, 3-(methylthio)-1-propanal (methional), 3-(methylthio)-1-propanol (methionol), 3-(methylthio)-1-propene, 3-(methylthio)-1-propyl acetate, 3-(methylthio)-1-propanoic acid (methionic acid) and ethyl 3-(methylthio)-1-propanoate, though the production of these VSCs varied between yeast strains. W. saturnus var. saturnus NCYC22 was selected for further studies due to its relatively high VSC production. VSC production was characterised step-wise with yeast strain NCYC22 in coconut cream at different L: -methionine concentrations (0.00-0.20%) and under various inorganic sulphate (0.00-0.20%) and nitrogen (ammonia) supplementation (0.00-0.20%), respectively. Optimal VSC production was obtained with 0.1% of L: -methionine, while supplementation of sulphate had no significant effect. Nitrogen supplementation showed a dramatic inhibitory effect on VSC production. Based on the production of VSCs, the study suggests that the Ehrlich pathway of L: -methionine catabolism is operative in W. saturnus yeasts and can be manipulated by adjusting certain nutrient parameters to control VSC production.     

Exfoliation of gastric pit-parietal cells into the gastric lumen associated with a stimulation of isolated rat gastric mucosa in vitro: a morphological study by the application of cryotechniques

It is clinicopathologically important to elucidate the cell kinetics for the maintenance of normal gastric epithelium. In a rat gastric mucosa isolated after stimulation, a number of cells were exfoliated into the gastric lumen of the pit region. The present study was undertaken to clarify the origin of exfoliated cells and their histochemical profiles by taking the advantages of cryotechniques. As results, most of the exfoliated cells were identified as pit-parietal cells labeled with both peanut-lectin and anti-H+/K+-ATPase antibody. Quantitative analysis verified a time-dependent increase in the number of exfoliated cells in the gastric mucosa isolated after stimulation. The exfoliated cells exhibited a diffuse intracellular staining for E-cadherin, suggesting a dissociation of the adhesion molecule prior to the cell exfoliation. It should be noted that most of the exfoliated cells were negative to the apoptotic markers (TUNEL staining and caspase-3). Ultrastructurally, autophagosome-like structures consisting of H+/K+-ATPase positive membranes were frequently seen in the exfoliated pit-parietal cells. In addition, the pit-parietal cell exfoliation was accompanied by sealing of their basal portion with the cytoplasmic processes of adjacent surface mucous cells. The present morphological findings provide a new insight into the cell kinetics in the gastric epithelium in vitro.     

The inter-relationship between anchorage independence and tumorigenicity in early cultures of oral keratinocytes

This study examines the expression of anchorage independence and tumorigenicity in early cultures of oral rat keratinocytes. The epithelial cell lines originated from the palatal and the lingual mucosa of rats that had been painted with the carcinogen 4-nitroquinoline N-oxide. The colony forming efficiency (CFE) in gel culture of the cell lines derived from five squamous cell carcinomas of the tongue and palate predominantly increased with passage in culture. Carcinoma-derived cell lines that had a relatively high CFE (greater than 2.5%) formed tumours when transplanted to athymic mice, but cells in which the CFE was less than 2.5% were non-tumorigenic. Keratinocytes from a dysplastic palatal lesion were immortal, anchorage dependent and non-tumorigenic. A lingual papilloma cell line consistently expressed a very low CFE but was tumorigenic at the higher culture passages. The results show that the routine passage of cells in culture leads to the emergence of the anchorage independent and tumorigenic phenotypes in keratinocytes of malignant origin and, further, suggest that anchorage independence and tumorigenicity may exist as distinct phenotypes, with anchorage independence preceding tumorigenicity.     

Crypt architecture of tonsilla lingualis in the monkey,Macaca fascicularis

Summary Crypts of the lingual tonsil were investigated in 10 male and female Macaca fascicularis by use of correlated light and scanning-electron microscopy. Counting of crypt openings provided an estimate of the total number of respective crypto-lymphatic units, which were found to range from 20 to 39. Crypt openings appeared in three distinct morphological varieties, i.e. circular, oval or slit-like. Tonsillar units existed individually or were arranged in a rosary fashion below a slit-like mucosal fold serving as a common exit. Although the crypt epithelium was generally non-keratinized, individual cells showing a surface pattern similar to that of the keratinized cells could be encountered. The crypt epithelium was frequently fragmented and showed heavy mononuclear cell infiltration and surface discontinuities, with lymphoid cells coming in contact with luminal contents. The crypt lumen either appeared as a simple epithelial invagination or existed as a complex, cavernous pouch with many blind-ending diverticula. The lumen contained a mixture of exfoliated epithelial cells, leucocytes and bacteria. The secretory ducts of the posterior lingual glands opened occasionally at various levels into the crypt lumina or independently to the exterior.     

Ionizing radiation alters Fas antigen ligand at the cell surface and on exfoliated plasma membrane-derived vesicles: implications for apoptosis and intercellular signaling

Resident proteins that reside on the plasma membrane are continually exfoliated from the cell surface. Exfoliation is a selective, energy-dependent process that mediates intercellular communication. Ionizing radiation modulates the expression of many plasma membrane-bound growth regulators, including the "death" ligand, TNFSF6 (formerly known as FasL, CD95L). Here we report that ionizing radiation induces dose-dependent up-regulation of TNFSF6 on plasma membranes purified from SW620 cells, a TNFSF6-expressing colon cancer cell line. Serum-free medium conditioned by exposed and control cells was collected and exfoliated vesicles were obtained by ultracentrifugation. Western blot analysis of vesicles from unexposed cells and from cells treated with 10 Gy showed increased amounts of TNFSF6 compared to that on vesicles from unexposed cells. Cells treated with 4 Gy released vesicles having a low level of TNFSF6 on their surface relative to that on vesicles exfoliated from unexposed cells. When assayed for bioactivity, vesicles from unexposed cells induced the greatest level of apoptosis in TNFRSF6 (formerly known as FAS) receptor-bearing Jurkat cells (cell surviving fraction of 43.7 +/- 6.1; P < 0.05), followed by vesicles collected from cells treated with 4 Gy (79.6 +/- 2.6%; P < 0.05). Despite having a high level of TNFSF6 by Western analysis, vesicles collected from cells exposed to 10 Gy display minimal biological activity (77.9 +/- 3.2%; P < 0.05), suggesting that modification of the vesicle-associated ligand has occurred. Our results indicate that ionizing radiation increases the level of TNFSF6 exfoliated on extracellular vesicles. The data may provide a mechanism for abscopal and bystander effects after irradiation.     

义齿口臭的相关因素研究

目的:探讨义齿口臭的的相关因素。方法:选择62例无牙周疾病且全身健康(心血管系统疾病除外)的上颌义齿修复者,鼻闻法检查口臭程度(OR值),使用便携式口气测量仪(halitosis)测量VSCs量,记录义齿使用时间、菌斑指数(plaque index,PLI)。结果:Spearman相关分析法显示口臭值与义齿使用时间、PLI存在正相关(r=0.73,r=0.52,P<0.01),义齿口臭OR值与VSCs量存在正相关(r=0.62,p<0.01),义齿使用时间与PLI也有一定的相关性(r=0.259,P<0.05)。结论:口臭值、VSCs量与聚甲基丙烯酸脂基托义齿使用时间、PLI均有关系,义齿口臭的气体成份不完全同于其它口源性口臭。     

Flow cytometric enrichment for respiratory epithelial cells in sputum.

BACKGROUND: Induced sputum, in contrast to bronchoscopic biopsies and lavages, is an easily obtained source of biological specimens. However, obtaining abnormal exfoliated cells for detailed molecular studies is limited because respiratory epithelial cells comprise only about 1% of sputum cell populations. METHODS: We developed a multiparameter flow sorting strategy to purify epithelial cells from nonepithelial sputum cells, using anti-cytokeratin antibody AE1/AE3 to recognize human epithelial cells and DAPI to stain DNA. We excluded cells with a high degree of side-scatter, which were composed predominantly of squamous cells and contaminating macrophages. The remaining cytokeratin-positive respiratory epithelial cells were then sorted based on anti-cytokeratin (PE) vs DNA (DAPI) parameters. RESULTS: In this proof of principle study, the AE1AE3 cytokeratin/DNA flow sorting strategy enriched rare diploid respiratory epithelial cells from an average of 1.1% of cells in unsorted induced sputum samples to average purities of 42%. Thus, AE1AE3 flow-sorting results in a 38-fold enrichment of these cells. CONCLUSIONS: We report a multiparameter flow cytometric assay to detect and enrich rare respiratory epithelial cells from induced sputum samples to average purities of 42%. With further development, this methodology may be useful as part of a molecular screening approach of populations at high risk for lung cancer.     

Immune and proliferative cellular responses to Helicobacter pylori infection in the gastric mucosa of Mexican children

BACKGROUND: Helicobacter pylori infection occurs mostly during childhood, but few studies on this age group have addressed the innate immune and the proliferative response to this infection. Mexico has a high H. pylori prevalence in children, but a low risk of gastric cancer. The aim of this work was to study the cellular responses of the gastric mucosa to this infection in Mexican children. METHODS: Antral and corpus gastric biopsies were obtained from 44 H. pylori-infected children (mean age 12 +/- 3.2 years) and 44 uninfected children (mean age 10 +/- 3 years). Mucosal cellular responses were studied by immunohistochemistry, using anti-Ki67 antibodies for proliferation studies, antihuman tryptase for mast cells, and antihuman CD68 for macrophages. T and B lymphocytes were stained with a commercial integrated system. The intensity of cellular responses was estimated histologically using the software KS300. RESULTS: Epithelium proliferation and infiltration of macrophages and T and B lymphocytes were significantly higher in H. pylori-infected than in uninfected children. A balanced increase of CD4, CD8, and CD20 lymphocytes was observed in infected children. However, activated mast cells were decreased, and infiltration of neutrophil and mononuclear cells was low. Epithelial proliferation was associated with polymorphonuclear infiltration but not with infiltration of macrophages or lymphocytes. Inflammation and proliferation was higher in CagA (+)-infected children. CONCLUSIONS: Mexican children respond to H. pylori infection with a low inflammatory response, a balanced increase of T and B lymphocytes, and a high regenerative activity.     

Urinary Amino Acid Alterations in 3-Year-Old Children with Neurodevelopmental Effects due to Perinatal Dioxin Exposure in Vietnam: A Nested Case-Control Study for Neurobiomarker Discovery

In our previous study of 3-year-old children in a dioxin contamination hot spot in Vietnam, the high total dioxin toxic equivalent (TEQ-PCDDs/Fs)-exposed group during the perinatal period displayed lower Bayley III neurodevelopmental scores, whereas the high 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-exposed group displayed increased autistic traits. In autistic children, urinary amino acid profiles have revealed metabolic alterations in the amino acids that serve as neurotransmitters in the developing brain. Therefore, our present study aimed to investigate the use of alterations in urinary amino acid excretion as biomarkers of dioxin exposure-induced neurodevelopmental deficits in highly exposed 3-year-old children in Vietnam. A nested case-control study of urinary analyses was performed for 26 children who were selected from 111 3-year-old children whose perinatal dioxin exposure levels and neurodevelopmental status were examined in follow-up surveys conducted in a dioxin contaminated hot spot. We compared urinary amino acid levels between the following 4 groups: (1) a high TEQ-PCDDs/Fs and high TCDD-exposed group; (2) a high TEQ-PCDDs/Fs but low TCDD-exposed group; (3) a low TEQ-PCDDs/Fs exposed and poorly developed group; and (4) a low TEQ-PCDDs/Fs exposed and well-developed group. Urinary levels of histidine and tryptophan were significantly decreased in the high TEQ-PCDDs/Fs and high TCDD group, as well as in the high TEQ-PCDDs/Fs but low TCDD group, compared with the low TEQ-PCDDs/Fs and well-developed group. However, the ratio of histidine to glycine was significantly lower only in the high TEQ-PCDDs/Fs and high TCDD group. Furthermore, urinary histidine levels and the ratio of histidine to glycine were significantly correlated with neurodevelopmental scores, particularly for language and fine motor skills. These results indicate that urinary histidine is specifically associated with dioxin exposure-induced neurodevelopmental deficits, suggesting that urinary histidine may be a useful marker of dioxin-induced neurodevelopmental deficits and that histaminergic neurotransmission may be an important pathological contributor to dioxin-mediated neurotoxicity.