双酚A和对-壬基酚雌激素受体的竞争性结合

目的　用雌激素受体竞争性结合试验检测双酚A(BPA)、对 -壬基酚 (p -NP)的雌激素样活性。 方法　将SD大鼠进行人工卵巢去除术 ,饥饿受体 14d后提取子宫胞浆雌激素受体 (ER) ,受体蛋白定量 ,作雌二醇 (E2 )非标记配体饱和分析 ,以确定E2 的IC50 。随后进行BPA和 p -NP的竞争性取代实验 ,观察BPA ,p -NP是否能与3 H -E2竞争性结合大鼠子宫胞浆ER。结果　E2 的IC50 是 1× 10 -9mol/L ,BPA、p -NP的IC50 分别为 2 0 8× 10 -5mol/L和2 6 6R10 -5mol/L ,BPA、p -NP的相对结合亲和力系数 (RBA)分别为 0 0 0 4 8和 0 0 0 38,BPA与ER的结合能力稍高于 p -NP。 结论　BPA和 p -NP结合ER是发挥其雌激素样效应机制中的重要因素     

17β-雌二醇对子宫内膜癌细胞增殖及p38表达的影响

目的:探讨不同浓度的17β-雌二醇(E2)对雌激素受体(ER)阴性的JEC细胞和ER阳性的Ishikawa子宫内膜腺癌细胞系细胞的增殖及细胞内p38蛋白表达的影响。方法:选用人子宫内膜腺癌细胞系JEC和Ishikawa进行体外培养,加入含不同浓度E2培养液,以四甲基偶氮唑蓝(MTT)比色法和激光共聚焦扫描显微镜(CLSM)的方法,观察子宫内膜腺癌细胞系JEC和Ishikawa细胞的增殖活性及P-p38的表达。结果:①MTT法观察细胞增殖:10-7、10-8和10-9 mol/L E2作用JEC细胞4、5天后OD值与对照组比较有差异(P<0.05),其中10-7 mol/L E2组在第5天OD值与对照组比较差异较显著(P<0.01);而不同浓度E2作用Ishikawa细胞均能促进增殖(P<0.05)。②共聚焦显微镜测定细胞内P-p38蛋白的表达:10-7 mol/L的E2作用JEC 4、5天后可使细胞内P-p38表达增加,平均荧光强度值与对照组相比有统计学意义(P<0.05);10-7 mol/L的E2作用Ishikawa 3、4天后P-p38表达增加,与不加E2对照组比较差异有统计学意义(P<0.05)。结论:子宫内膜腺癌细胞系JEC细胞和Ishikawa细胞均可受到雌激素的调控,一定浓度的雌激素能促进ER阴性JEC细胞和ER阳性的Ishikawa细胞增殖,且均能使细胞内P-p38表达增加。     

镉通过类雌激素样作用促进人乳腺癌MCF-7细胞增殖

[目的]研究镉对人乳腺癌MCF-7细胞增殖及雌激素受体(estrogen receptor,ER)蛋白表达水平的影响及其可能机制。[方法]用1×10~(-6)、1×10~(-7)、1×10~(-8)、1×10~(-9)、1×10~(-10)、1×10~(-11) mol/L的17β-雌二醇(后称雌激素)培养不同来源的A、B两株MCF-7细胞4 d,应用CCK8法筛选敏感细胞株并确定雌激素促细胞增殖作用最强的浓度。用1×10~(-6)、1×10~(-7)、1×10~(-8)、1×10~(-9)、10~(-10)、1×10~(-11) mol/L的镉溶液染毒敏感细胞株,确定镉促进细胞增殖的最大浓度。设置阴性对照组(去雌激素培养液)、实验组(1×10~(-8) mol/L镉)、阳性对照组(1×10~(-9) mol/L雌激素),通过克隆形成实验检测镉对MCF-7细胞集落形成能力的影响。利用ER抑制剂(ICI182780)初步探讨镉致细胞增殖的可能机制,增设实验抑制剂组(1×10~(-8) mol/L镉+1×10~(-7) mol/L ER抑制剂)、阳性抑制剂组(1×10~(-9) mol/L雌激素+1×10~(-7) mol/L ER抑制剂),通过CCK8法、流式细胞术和Western blot分别检测各组的细胞增殖率、细胞周期S期比例和ER表达水平。[结果]实验所用B株MCF-7细胞为雌激素敏感细胞株,且当雌激素浓度为1×10~(-9) mol/L时,对MCF-7细胞的促进增殖作用[(203.55±36.65)%]最大(P0.001)。与阴性对照组(100%)相比,1×10~(-8)~1×10~(-10) mol/L镉溶液可促进MCF-7细胞增殖[(163.78±31.90)%~(176.88±10.06)%](P0.001)。1×10~(-8) mol/L镉可促进细胞集落形成(P0.05),增加细胞S期比例(P0.001),提高细胞ER蛋白表达水平(P0.001)。与实验组相比,加入ER抑制剂能够抑制镉对MCF-7细胞的促增殖作用[由(135.17±23.96)%降至(107.66±7.64)%](P0.01),抑制镉诱导的细胞S期比例增加[由(24.17±0.53)%降至(12.36±0.43)%](P0.001),拮抗镉诱导的ER表达增加[由(56.19±3.67)%降至(38.84±1.04)%](P0.05)。[结论]镉可以促进人乳腺癌细胞MCF-7增殖和ER表达,这种作用可被ER抑制剂所抑制,提示镉可能具有雌激素样作用。     

壳聚糖对围绝经期大鼠E_2、P及子宫ERα的影响

目的:观察壳聚糖对围绝经期大鼠血清E2、P及ERα的影响。方法:将30只11～12月龄健康雌性Wista大鼠随机分为壳聚糖组、空白对照组和雌激素对照组各10只。壳聚糖组灌胃壳聚糖1 500 mg/kg,雌激素组灌胃补佳乐1.2 mg/kg,对照组灌胃3 ml双蒸水,每天灌胃一次,连续30天后处死大鼠。用酶联免疫吸附试验法测血清中E2和P的含量;免疫组织化学SABC法检测子宫ERα的表达情况。结果:壳聚糖组大鼠血清E2、P的含量及ERα的平均光密度分别为(59.83±17.24)ng/L、(89.72±15.20)ng/L及(0.064±0.004),高于空白对照组的(44.52±7.28)ng/L、(51.23±7.30)ng/L及(0.052±0.005),E2、ERα的平均光密度低于雌激素对照组的(74.00±6.85)ng/L、(0.079±0.004),差异有统计学意义(P<0.05)。结论:壳聚糖可以提高围绝经期大鼠血清E2和P的含量,增加ERα的表达。     

氯化汞雌激素样作用及其机制的实验研究

目的评价氯化汞(HgCl2)的雌激素样作用及其作用机制.方法从体内和体外两个水平,观察不同浓度的HgCl2对MCF-7人乳腺癌细胞增殖作用、去卵巢SD大鼠子宫的诱导增生作用、过氧化物活力的变化及对雌激素结合雌激素受体的影响.结果 10-6～10-9 mol/L的HgCl2均可引起MCF-7人乳腺癌细胞增殖,10-7 mol/L的HgCl2使MCF-7人乳腺癌细胞增殖达最大.每天0.04、0.20及1.00 mg/kg连续3 d腹腔注射HgCl2能刺激大鼠子宫增生和过氧化物酶活力增加;但HgCl2不影响雌二醇(E2)与雌激素受体结合.结论 HgCl2可能通过雌激素受体介导而表现出雌激素样作用,但不与E2竞争结合雌激素受体.     

吗啡对子宫内膜基质细胞增殖及ERmRNA表达的影响

目的研究吗啡对雌激素诱导的体外培养的人子宫内膜基质细胞的增殖作用及其ERmRNA表达的影响. 方法体外分离培养人子宫内膜腺上皮细胞和基质细胞,并通过免疫细胞化学的方法进行鉴定;将基质细胞给予17-β雌三醇或/和吗啡及纳洛酮干预,观察细胞的生长增殖情况;通过RT-PCR 的方法半定量分析吗啡对基质细胞的雌激素受体ERmRNA表达的影响. 结果第一代传代的基质细胞各组接种密度间比较,差异无显著性(P＞0.05).接种用药第1、3、5、7、天进行细胞计数,细胞数较对照组增加,E+Mor组细胞数较E2组降低,差异有显著性(P ＜0.01).E+ M+N组与E2组比较,差异无显著性(P＞0.05);ER 与内参照β-actin 分别在469 bp和348 bp处出现特征性条带.雌激素组、吗啡组与对照组比较,差异有显著性 (P＜0.05),E+Mor组与对照组比较,差异无显著性(P ＞0.05).吗啡作用24 h呈剂量依赖性抑制基质细胞ERmRNA的表达,3组吗啡的终浓度分别为1×10-6 mol/L、1×10-5 mol/L、1×10-4 mol/L,经Spearman等级相关检验,r=-0.946,差异有显著性(P＜0.01). 结论外源性阿片类药物吗啡可以直接抑制雌激素对人子宫内膜基质细胞的促增殖作用,其机制可能是影响了雌激素受体mRNA的表达.     

拟除虫菊酯对大鼠脑代谢型谷氨酸受体结合的影响

目的　比较两型拟除虫菊酯 (pyrethroid ,PY)类农药对大鼠脑代谢型谷氨酸受体(mGluR)结合功能的影响。方法　应用放射性配基受体结合试验在体外测定溴氰菊酯 (DM )和氯菊酯 (PM )对大鼠大脑皮层和海马突触膜mGluR结合功能的影响。结果　DM分别在 2× 10 -6、2× 10 -5、2× 10 -4 mol/L和 2× 10 -10 、2× 10 -8、2× 10 -6、2× 10 -4 mol/L剂量范围内直接增加大鼠大脑皮层和海马突触膜氚标记的谷氨酸 (3H Glu)与mGluR的特异结合量 ,分别为 :(10 7.6± 7.7)、(112 .4± 9.6 )、(115 .4± 12 .2 )fmol/mgpro .和 (15 9.8± 16 .9)、(16 6 .9± 2 0 .9)、(183.8± 2 1.2 )、(193.8± 2 5 .8)fmol/mgpro .;PM在 2× 10 -8～ 2× 10 -4 mol/L剂量范围内对大脑皮层突触膜3H Glu与mGluR的特异结合量无明显影响 ,在 2× 10 -6、2× 10 -4 mol/L时直接增加海马突触膜3H Glu与mGluR的特异结合量 ,分别为 :(173.8± 2 0 .1)、(180 .9± 2 4.3 )fmol/mgpro .。 结论　DM和PM均可不同程度地影响海马突触膜mGluR的结合功能 ,带氰基的DM比不带氰基的PM更容易增加大鼠脑mGluR的特异结合量     

局部振动对家兔外周血中脂质过氧化的影响

[目的 ]探讨局部振动对家兔脂质过氧化的影响。 [方法 ]将家兔随机分为低强度组 (接振强度 3 .0 3m/s2 ) ,中强度组 (接振强度 6.13m/s2 ) ,高强度组 (接振强度 12 .2 5m/s2 )和 1个对照组 ,分别于接振 10、2 0、3 0d测定各组家兔血中MDA浓度、SOD活力和GSH Px活力。 [结果 ]接振后 10、2 0、3 0d的MDA浓度分别为 :低强度组 ( 3 .77± 0 .3 4) μmol/L、( 4 .16± 0 .3 0 ) μmol/L、( 4 .3 9± 0 .3 1) μmol/L ;中强度组 ( 4 .12± 0 .3 5 ) μmol/L、( 4 .3 8± 0 .3 4) μmol/L、( 4 .5 4± 0 .42 ) μmol/L ;高强度组 ( 4 .13± 0 .3 2 ) μmol/L、( 4 .5 8± 0 .47) μmol/L、( 4 .99± 0 .70 ) μmol/L。SOD活力分别为 :低强度组 ( 82 994± 10 70 1)U/L、( 86113± 860 2 )U/L、( 8873 7± 75 48)U/L ;中强度组 ( 880 5 0± 9196)U/L、( 915 13± 7114 )U/L、( 93 60 8± 8842 )U/L ;高强度组 ( 895 5 3± 12 677)U/L、( 942 46± 14 480 )U/L、( 963 19± 13 981)U/L。GSH Px活力分别为 :低强度组 ( 780 4± 846)U/L、( 82 5 9± 414 )U/L、( 842 7± 2 90 )U/L ;中强度组 ( 82 11± 765 )U/L、( 8465± 462 )U/L、( 90 76± 75 3 )U/L ;高强度组 ( 8984± 63 9)U/L、( 93 0 2± 62 5 )U/L、(     

溴氰菊酯对原代培养大鼠星形胶质细胞存活率和胞内游离钙浓度的影响

目的　观察溴氰菊酯 (DM)对原代培养大鼠神经星形胶质细胞存活率及胞内游离钙离子浓度 ([Ca2 + ]i)的影响。方法　以锥虫蓝染料排斥试验检测细胞染DM后存活率的变化 ;以Fura 2 /AM为荧光指示剂 ,RF 5 30 1PC荧光分光光度计测定细胞内 [Ca2 + ]i的变化。结果　 1× 10 -5mol/L组染毒DM 72h后细胞存活率下降为 91.9% ,与对照组的差异有显著性 (P <0 .0 5 ) ,1× 10 -4mol/L组DM染毒4、12、4 8、72h后细胞存活率分别为 89.0 %、84 .8%、81.2 %和 79.2 % ,差异有显著性 (P <0 .0 1) ;1× 10 -7、1× 10 -6、1× 10 -5mol/L组DM染毒 5min后胞内 [Ca2 + ]i分别上升至 (45 1.4± 4 2 .3)、(5 36 .9± 4 7.5 )、(870 .9± 10 0 .5 )nmol/L ,与染毒前及对照组比 ,差异有显著性 (P <0 .0 1)。以后各染毒组胞内 [Ca2 + ]i逐渐下降 ,15min时 1× 10 -8、1× 10 -7、1× 10 -6、1× 10 -5mol/L染毒组胞内 [Ca2 + ]i分别降至 (12 4 .3± 6 .0 )、(131.3± 19.1)、(118.9± 1.4 )、(136 .6± 3.8)nmol/L ,与染毒前及对照组比差异均有显著性 (P <0 .0 5或P <0 .0 1)。结论　DM在体外可降低神经胶质细胞的存活率并短时升高胞内 [Ca2 + ]i。     

苏州市部分学龄前儿童血铅、镉及红细胞游离原卟啉水平

目的　了解苏州市区学龄前儿童体内血铅、血镉的水平 ,以确定当前暴露水平。方法　对苏州市区 2所幼儿园 1 2 0名学龄前儿童分别采用石墨炉原子吸收与荧光分光光度法测定末梢血血铅、镉及红细胞游离原卟啉 (FEP)含量。结果　 1 2 0名学龄前儿童体内血铅、镉及红细胞FEP均值的 95%可信限分别为 ( 0 .32± 0 .2 6 ) μmol/L ,5.6× 1 0 - 3 μmol/L(几何均数 ) ,( 0 .4 6± 0 .32 ) μmol/L ,整体水平在正常范围内 ,部分儿童的血铅超过 0 .4 83μmol/L。 结论　在当前的暴露水平下 ,仍有部分儿童存在触铅的可能     

Improvement of a sensitive enzyme-linked immunosorbent assay for screening estrogen receptor binding activity

A competitive enzyme-linked immunosorbent assay (ELISA) with estrogen receptor (alpha) and a fluorescence depolarization method with Full-Range Beacon were examined as estrogen receptor binding assays to prescreen endocrine-disrupting chemicals (EDCs). In this study, because it is difficult to measure the receptor binding ability of sparingly water-soluble chemicals using these methods, the competitive enzyme immunoassay was further modified for improved sensitivity by changing the operational parameters, such as receptor concentration, ligand concentration, and the reaction temperature. The method was applied to 10 test chemicals, including alkylphenols and bisphenol A (BPA). The diethylstilbestrol (DES) relative binding affinity (RBA) of ELISA kit was set equal to 1 (RBA = IC50/IC50 of DES). The RBAs of BPA, 4-nonylphenol (p-NP), and 4-t-octylphenol (p-t-OP) are 5386, 8619. and 8121 before using the improved competitive enzyme immunoassay and 883, 699, and 2832 using improved it respectively. Mixtures of BPA, p-NP, and p-t-OP gave results that the estrogen binding affinities of these chemicals are additive or slightly more than additive.     

美金刚对敌敌畏染毒大鼠脑组织NMDA受体的保护作用

目的　研究美金刚对敌敌畏染毒大鼠脑组织N 甲基 D 天冬氨酸 (NMDA)受体的保护作用及其治疗有机磷农药中毒的机制。方法　雄性SD大鼠用 2 5mg/kg敌敌畏染毒 ,再用美金刚 5、15、45mg/kg治疗 ,观察大鼠中毒症状出现强度与时间 ;染毒后 16h测定大鼠全血和脑组织乙酰胆碱酯酶 (AChE)活力及NMDA受体活性。结果　美金刚 15、45mg/kg治疗组大鼠中毒症状出现时间分别为 (18.40± 1.14 )、(2 1.40±1.52 )min ,较敌敌畏组 [(16.75± 1.62 )min]明显延长 ;肌颤强度分别为 1.60± 1.14、0 .80± 0 .84,较敌敌畏组(2 .85± 0 .3 7)明显减轻 ;症状总评分分别为 8.80± 1.79、9.0 0± 2 .2 4,较敌敌畏组 (14 .60± 1.70 )明显改善。美金刚对敌敌畏染毒大鼠全血和脑组织AChE活力均未见明显影响。敌敌畏染毒大鼠脑组织NMDA受体密度减少、亲和力下降 ,其Bmax和Kd值分别为 (0 .46± 0 .0 6)pmol/mgpro、(75.55± 7.87)nmol/L ,分别较阴性对照组 [(0 .62± 0 .0 4)pmol/mgpro、(3 7.3 7± 4.17)nmol/L]下降和上升。 5、15mg/kg美金刚可拮抗敌敌畏染毒对大鼠脑组织NMDA受体的影响 ,这两组的Bmax值分别为 (0 .55± 0 .0 7)、(0 .64± 0 .0 7)pmol/mgpro ,Kd值分别为 (3 8.68± 4.54)、(3 2 .58± 3 .90 )nmol/L。美金刚 45m     

Effects of analogues and drugs on arginine vasopressin receptor binding in rat renal tubular basolateral membrane

The methods of basolateral membrane isolation from rat kidney and 3H-AVP receptor assay using this basolateral membrane preparation were established. Then, the effects of analogues and drugs on AVP-receptor binding were studied. Specific 3H-AVP binding was inhibited by LVP, dDAVP and oxytocin in that order. Among the various agonistic or antagonistic drugs to AVP (fluoride, cyclophosphamide, mechlorethamine, chlorpropamide), only chlorpropamide inhibited 3H-AVP binding to the membrane. The Kd value calculated by Scatchard analysis was 1.30 +/- 0.28 nM (n = 4, M +/- SD), and it was increased to 2.69 +/- 0.32 nM (n = 5, M +/- SD) by adding 1 mM of chlorpropamide, while Bmax was unchanged. Our data show that 1 mM chlorpropamide decreases receptor affinity for AVP, and alters AVP-receptor binding in a competitive manner.     

A yeast assay based on the gilthead sea bream (teleost fish) estrogen receptor β for monitoring estrogen mimics

A yeast (Saccharomyces cerevisiae)-based assay was developed and tested with steroids and chemicals (mostly pesticides). The induction of β-galactosidase activity was strictly dependent on the presence of seabream (Sparus aurata) βa estrogen receptor (sbERβa) and substances known to have estrogenic activity. 17β-Estradiol (E₂) and diethylstilbestrol (DES), both agonists, were most active and the antagonist tamoxifen (TAM) was 14-fold less active than E₂. Among the chemicals tested bisphenol-A was most active, followed by pentachlorophenol and naphthalene. Ligand-binding assays with recombinant sbERβa and sbERα revealed that sbERβa binds E₂ with 6.5-fold higher affinity than sbERα, confirming the selection of a high sensitive receptor for the yeast assay. DES, ICI 182,780, estrone and TAM had higher relative binding affinity to E2 in sbERα than sbERβa, although there was no difference in IC50 for these steroids between the two receptors. These results reveal the usefulness of using the yeast-based receptor assay for detecting chemical interaction with steroid receptors from contaminated samples.     

Interaction of stilbene compounds with human and rainbow trout estrogen receptors

Compounds with stilbene structures are widely used as pharmaceuticals and personal care products (PPCPs) and are present in plants. A suite of stilbene-related compounds, including PPCPs and plant-derived compounds were tested in vitro for interactions with the human and rainbow trout estrogen receptors and in vivo with rainbow trout using vitellogenin levels as a biomarker. Among the compounds with antagonistic activity, the common structural similarity was (in addition to the stilbene backbone) the presence of 4-hydroxy substitution. Stilbene-related compounds found to act as inhibitors at the estrogen receptor included the plant-derived compound resveratrol and two formulations of fluorescent whitening agents used in detergents, 4,4'-bis(2-sulfostyryl)biphenyl and diaminostilbene-1. In the yeast estrogenicity screening assay, the concentrations which caused a 50% inhibition in estrogenic response (IC50s) with the human estrogen receptor ranged from 2.56 x 10(-6) to 2.56 x 10(-6) M. In the rainbow trout estrogen receptor assay, the IC50s ranged from 7.75 x 10(-8) to 1.11 x 10(-5) M. However, in the in vivo rainbow trout vitellogenin assay, tamoxifen was the only stilbene of the compounds tested to have a significant effect as an inhibitor of estrogenicity.     

番茄红素高压处理后抗乳腺癌细胞增殖的研究

目的:研究番茄红素高压后的组分变化及通过体外研究,观察不同组分番茄红素的抗人乳腺癌细胞活性。方法:采用HPLC法和UV-vis法分析高压后番茄红素组分变化。采用噻唑蓝(MTT)法考察不同结构的番茄红素对雌激素受体阴性(ER-)人乳腺癌细胞MDA-MB-435S的增殖抑制作用。结果:(1)番茄红素高压处理(300MPa,8min,10℃)后总量变为原来的56.3%,顺式异构体比例从0.3%提高到10.05%。(2)番茄红素对MDA-MB-435S细胞的增殖抑制作用有剂量-效应关系和时间-效应关系。未处理番茄红素IC50为22.4μmol/L;高压后番茄红素IC50为13.6μmol/L。(3)高压后番茄红素对乳腺癌细胞的增殖抑制作用增强。在浓度为10μmol/L时,4d后,高压后番茄红素对细胞的抑制率是未处理番茄红素的1.9倍。结论:番茄红素顺式异构体的抗乳腺癌细胞活性大于反式异构体,有关机制值得进一步研究。     

Brain neurotensin receptors in mice bred for differences in sensitivity to ethanol

The hypothesis that some of ethanol's acute effects are mediated via neurotensinergic systems was investigated by characterizing neurotensin (NT) receptors in mice (LS and SS) selectively bred for differences in sensitivity to ethanol. [3H]Neurotensin binding in brain membranes from both mouse lines was specific, saturable, reversible, and linear with protein concentrations. Subcellular localization studies showed specific NT binding to be concentrated in the microsomal/synaptosomal fractions. Scatchard analyses of [3H]NT binding indicated similar KD values for membranes from various brain regions of LS and SS mice. However, Bmax values in frontal cortex, cerebellum, and striatum were greater in SS than in LS mice. In competitive binding studies IC50 values were lower for NT8-13 than for NT1-13, and IC50 values for NT1-8, NT1-11, D-Trp11-NT, and D-Tyr11-NT were greater than 1000 nM. Association and dissociation rate constants for [3H]NT and resulting KD values (0.8 nM) were similar for LS and SS brain membranes. Ethanol, in vitro, had no effect on NT binding characteristics, but as expected various cations markedly increased KD values.     

Reverse triiodothyronine nuclear binding in rat brain

Reverse triiodothyronine (rT3) had been believed biologically inactive, but recently we demonstrated nuclear binding sites for rT3 in human placenta. In this study we examined rT3 binding sites in rat brain. Male Wistar normal rats aged 2, 4 and 9 weeks were killed and the brain was removed for rT3 binding assay. In another series, male Wistar rats weighing about 40g were divided into two groups: group 1 (rickets group), kept on our original rachitogenic diet and group 2, kept on standard diet. After 28 days on either diet they were killed and the brain was removed for assay. Cerebral nuclear protein was extracted with 0.4M KCl buffer. In normal 2 week-old rats specific binding sites for rT3 were detected in all parts of the brain, but at 7 weeks of age the density of the binding sites was decreased and at 9 weeks it is almost 0. Scatchard analysis performed in rachitic rats showed a curvilinear pattern, suggesting two sets of receptors existing in brain tissue; in cerebral cortex one with a association constant (Ka) of 1.07 X 10(8)M-1 and a limited capacity (Bmax) of 0.75 X 10(-15) moles/mg tissue and the other with Ka = 4.93 X 10(6), Bmax = 12.1 X 10(-15), and in thalamus including hypothalamus, one with Ka = 1.00 X 10(8), Bmax = 1.00 X 10(-15) and the other with Ka = 4.57 X 10(6) and Bmax = 18.6 X 10(-15).     

In vitro cytotoxicity testing of airborne formaldehyde collected in serum-free culture media

The purpose of this study was to identify a suitable sampling model for on-site toxicity assessment of soluble air contaminants such as formaldehyde, a well known industrial and indoor air contaminant. The in vitro cytotoxicity of formaldehyde, the selected model for soluble air contaminants, was studied using the MTS (tetrazolium salt) assay in two carcinoma cell lines, A549 epithelial lung and HepG2 hepatocarcinoma, and in skin fibroblasts. The cytotoxic effects of airborne formaldehyde were evaluated using test atmospheres in concentrations below 10 ppm (12.3 mg/m3), generated by a dynamic diffusion method and bubbled (0.3 L/min) through serum-free culture media for one or four hours. Human cells were treated with formaldehyde air samples, and cell viability was determined after four hours incubation. In parallel, the concentration of airborne formaldehyde was monitored, using the 3500 NIOSH method. Cell viability of the HepG2 cells exposed to formaldehyde air samples (8.75 ppm x 4 h) was reduced to less than 50% (31.6 +/- 1.24%). The HepG2 cell lines were found to be more sensitive (IC50 = 103.79 +/- 23.55 mg/L) to formaldehyde than both A549 cell lines (IC50= 198.36 +/- 9.54 mg/L) and skin fibroblasts (IC50 = 196.68 +/- 36.73 mg/L) (P < 0.01). An average of 96.8% was determined for collection efficiency of formaldehyde in serum-free culture media. The results of this study suggest that absorption of soluble air contaminants, such as formaldehyde, in serum-free culture media can be used as a suitable sampling model for on-site toxicity assessments.     

A yeast estrogen screen for examining the relative exposure of cells to natural and xenoestrogens.

Xenoestrogens, such as o,p'-DDT and octyl phenol (OP), have been associated with reproductive abnormalities in various wildlife species. Xenoestrogens mimic the natural estrogen 17 beta-estradiol and compete for binding to the estrogen receptor. Even though the affinity of o,p'-DDT and OP for the estrogen receptor is approximately 1000-fold lower than 17 beta-estradiol, the actions of xenoestrogens could be enhanced if their bioavailability in serum were greater than 17 beta-estradiol. To test this hypothesis, the yeast estrogen screen (YES) was created by expressing human estrogen receptor (hER) and two estrogen response elements (ERE) linked to the lacZ gene. The beta-galactosidase activity of the YES system was significantly increased after treatment with 17 beta-estradiol or the xenoestrogens diethylstilbestrol (DES), o,p'-DDT, and OP but not with vehicle, antiestrogen ICI 164,384, dexamethasone, or testosterone. To determine whether serum proteins affected the bioavailability of natural estrogens compared to xenoestrogens, albumin, sex hormone binding globulin (SHBG), or charcoal-stripped serum were added to the YES system and beta-galactosidase activity assayed. Albumin and SHBG decreased beta-galactosidase activity in the presence of estradiol to a greater extent than DES, o,p'-DDT, and OP. Human and alligator charcoal-stripped serum were also effective at selectively reducing beta-galactosidase activity in the presence of estradiol compared to xenoestrogens. Human serum was more effective than alligator serum in reducing beta-galactosidase activity in the presence of xenoestrogens, indicating that serum may serve as a biomarker for sensitivity to xenoestrogens. Selective binding of 17 beta-estradiol by proteins in serum indicates that certain xenoestrogens may exert greater estrogenicity than originally predicted. The estrogenic potency of a compound involves its binding affinity, bioavailability in serum, and persistence in the environment. Our data demonstrate the utility of the YES system for identifying and characterizing environmental estrogens.