内皮抑素抑制SKOV3细胞生长及其在裸鼠皮下移植瘤中的作用机制

目的:探讨内皮抑素对卵巢癌SKOV3细胞及其荷瘤鼠卵巢癌组织的生长作用及机制。方法:MTT法观测内皮抑素对体外SKOV3细胞的抑制作用,透射电镜观察细胞凋亡、免疫细胞化学检测SKOV3;细胞中bcl-2和bax蛋白表达;将SKOV3细胞移植至裸鼠皮下,观察内皮抑素对皮下移植瘤生长的影响;TUNEL和电镜法观察肿瘤细胞的凋亡,免疫组织化学和RT-PCR法检测瘤组织中bcl-2和bax的表达。结果:内皮抑素具有体外抑制SKOV3细胞增殖的作用(P<0．01);能诱导SKOV3细胞凋亡,但对bcl-2和bax的表达无明显影响。内皮以抑素能抑制裸鼠皮下移植瘤的生长(P<0．05);其中bcl-2的表达低于对照组,而bax表达无明显改变。结论:内皮抑素具有抑制SKOV3细胞及皮下移植瘤生长的作用,其机制可能与诱发细胞凋亡和调节bcl-2／bax表达相关。     

Functional genomics may allow accurate categorization of the benzimidazole fungicide benomyl: lack of ability to act via steroid-receptor-mediated mechanisms

Although benomyl and its metabolite carbendazim have been shown to adversely affect male reproduction, the mechanisms of action do not appear to involve the endocrine system. However, few studies have been conducted using currently proposed tests specifically focused on endocrine disruption. Here, potential estrogen- and androgen-mediated activity of benomyl was therefore investigated in vitro and in vivo. Benomyl and carbendazim proved negative for agonistic and antagonistic activity in reporter gene assays for the human estrogen receptor alpha and androgen receptor. In uterotrophic and Hershberger assays using Crj:CD(SD)IGS rats, benomyl (100, 300 or 1000 mg/kg/day, p.o., N = 6) did not exert agonistic effects. However, the highest dose decreased uterine weights in the uterotrophic assay, and decreased weights of some androgen-related tissues of castrated rats receiving a testosterone propionate (TP, 0.2 mg/kg) injection in the Hershberger assay; the effects were less severe than those with p,p'-DDE (100 mg/kg/day). When 4 mg/kg/day of TP was injected, decrease of organ weights due to benomyl was attenuated but still observed. Thus, its influence in some tissues was more potent than that of p,p'-DDE. Benomyl had no apparent effects on serum androgen levels. Microarray analysis of the gene expression profile in the ventral prostate of TP-injected castrated rats treated with benomyl indicated clear differences from the patterns observed with p,p'-DDE and flutamide. Taken together, these findings suggest the decreased organ weights observed in vivo to be caused by mechanisms that are not steroid-receptor-mediated, such as interfering with assembly of microtubules by benomyl. The study furthermore suggests that functional genomics may provide a reliable evidence for accurate categorization of test chemicals.     

Effect of subcutaneous administration of dalteparin on lupus anticoagulant assays

INTRODUCTION: Treatment with unfractionated heparin (UH) is known to affect screening tests for lupus anticoagulant (LA). False positive test results are common because confirmatory steps lack sufficient specificity to distinguish between LA and the presence of heparin. In this study, we wanted to see if therapeutic levels of low-molecular weight heparin (LMWH) may cause false positive tests for LA or alter the LA test results in LA-positive patients. We also wanted to evaluate the need to include heparin-neutralizing agents in the reagents. MATERIALS AND METHODS: Six healthy subjects without LA and six LA-positive patients were given 100 IU/kg dalteparin subcutaneously (s.c.). Samples for three in-house and two commercially available LA tests were taken before and 4 h after the injection. LA test results were calculated as normalized screening/confirm ratios or as recommended by the manufacturers. RESULTS: With both healthy subjects and LA patients, only small and clinically unimportant differences in mean clotting times and final test results were seen 4 h after subcutaneous dalteparin injections, at anti-FXa activities within the therapeutic range. CONCLUSIONS: Our study with dalteparin suggests that LMWH therapy with plasma concentrations within the therapeutic range does not cause false positive tests for LA when normalized screening/confirm ratios are applied; nor do test results for LA-positive patients seem to be significantly altered. Heparin-neutralizing agents did not influence test performance.     

Spheroid Preparation from Hanging Drops: Characterization of a Model of Brain Tumor Invasion

BACKGROUND: The use of three-dimensional in vitro models of brain tumor invasion has provided a system for reconstructing some of the cellular microenvironments present in the tumor mass. While spheroids of murine and human astrocytoma cells can be prepared using spinning cultures, spheroid preparation using many cell lines is not amenable to this method. We have developed a reproducible system of creating implantable spheroids that is applicable to different cell lines, and is independent of cell line characteristics. METHODS: For murine and human brain tumor cell lines, 20 microl drops containing predetermined cell concentrations were suspended from the lids of culture dishes and the resulting aggregates were transferred to culture dishes base-coated with agar. The two-dimensional aggregates formed three-dimensional spheroids on the non-permissive agar substrate, and were then implanted into three-dimensional collagen I gels and the invasive activity assessed. The invasive activity of C6 and U251 spheroids prepared by hanging drops was compared to spheroids of similar size prepared by spinner culture. RESULTS: The hanging drop method produced implantable spheroids capable of sustained invasion using all cell lines tested. Most cell lines required initial hanging drop cell concentrations of 45,000 cells/drop, suspension times of 48, and 72 h on agar. C6 spheroids had the same invasive capacity regardless of the model utilized, however U251 spheroids produced by hanging drops had significantly increased invasion compared to those prepared by spinner culture. Only spheroids prepared by spinner culture showed histological evidence of central necrosis. CONCLUSIONS: This model represents a reproducible approach to the preparation of implantable spheroids with invasive potential that compares with those produced using spinner culture. The use of hanging drops broadens the applicability of three-dimensional in vitro assays examining brain tumor invasiveness.     

Octamethylcyclotetrasiloxane exhibits estrogenic activity in mice via ERalpha

Octamethylcyclotetrasiloxane (D4) is a low molecular weight cyclic silicone used in the synthesis of larger silicone polymers and in the formulation of a variety of personal care products. The effects of oral D4 exposure in mice on serum estradiol levels, uterine wet weight, and uterine peroxidase activity were investigated. Additionally, in vitro estrogen receptor binding activity was evaluated. Serum estradiol levels decreased in a dose-dependent manner after exposure to 100 mg/kg to 1000 mg/kg D4. Studies with adrenalectomized animals demonstrated that the decreased serum estradiol levels were not due to elevated serum corticosterone levels. Uterine wet weights in ovariectomized mice were significantly increased in a dose-dependent manner by exposure to 250-1000 mg of D4/kg, but not by exposure to other silicone compounds tested (hexamethylcyclotrisiloxane, decamethylcyclopentasiloxane, decamethyltetrasiloxane, and octaphenylcyclotetrasiloxane). Uterine peroxidase activity, a marker for estrogenic activity, was also significantly increased in D4-exposed mice, but not in mice exposed to the other siloxanes. Pretreating mice with the estrogen receptor antagonist ICI 182,780 completely blocked the D4-induced increase in uterine weight, and ovariectomized estrogen receptor-alpha knockout mice showed no increases in uterine weights when orally exposed to D4 or estradiol. In an in vitro estrogen receptor binding assay, D4 showed significant competition with (3)H-estradiol for binding to estrogen receptor-alpha, but not estrogen receptor-beta. The data presented here indicate that D4 has weak estrogenic activity, and that these effects are mediated through estrogen receptor-alpha.     

Multisite evaluation of a new dipstick for albumin, protein, and creatinine

The goal of our study was to perform a multisite evaluation of a new urine dipstick called Multistix PROtrade mark (Bayer, Elkhart, IN), which has reagent pads for the simultaneous assay of urinary albumin, protein, and creatinine. Patients' urine specimens were assayed at four sites with these dipsticks and with the familiar Bayer Multistix 10SG dipsticks for protein. The new dipstick pads for albumin are impregnated with bis (3',3"-diiodo-4',4"-dihydroxy-5',5"-dinitrophenyl)-3,4,5,6-tetrabromo-sulfonephthalein (DIDNTB) dye. These dipsticks also have a novel pad that estimates urinary creatinine using the peroxidase activity of the copper-creatinine complex. We determined the interlaboratory agreement of these dipsticks by comparing dipstick results to values obtained by quantitative analytical methods. We found that dividing the dipsticks' albumin or protein results by the creatinine concentration reduced the number of false-positive albumin or protein values observed in concentrated urines, and reduced the number of false negatives in dilute urines. The ratio of albumin to creatinine, or protein to creatinine gives a better measure of albumin or protein excretion. Compared to reading by eye, the dipstick results agreed better with the quantitative assays when they were read by a reflectometer (Bayer Clinitek).     

Receptor-mediated gene delivery to HepG2 cells by ternary assemblies containing cationic liposomes and cationized asialoorosomucoid

Unilamellar cationic liposomes have been prepared from an equimolar mixture of 3beta[N',N'-dimethylaminopropane)-carbomoyl] cholesterol (Chol-T), a higher homologue of 3beta[N',N'-dimethylaminoethane)-carbomoyl] cholesterol (DC-Chol), and dioleoylphosphatidyl-ethanolamine. The DNA binding capabilities of Chol-T and Chol-T/DOPE liposomes have been demonstrated in lipid impregnated paper-DNA binding assays and gel retardation experiments, respectively. These liposomes have been combined with pRSVL plasmid DNA and N-ethyl-N'-(3-trimethylpropylammonium) carbodiimide iodide modified asialoorosomucoid (Me+ CDI urea-AOM) to generate ternary electrostatic assemblies intended for selective entry into cells displaying the galactose-specific lectin. This effect has been evaluated in the human hepatocellular carcinoma cell line HepG2 in which high levels of luciferase activity were achieved (up to 1.84 x 10(7) relative light units/mg protein) after transfection with complexes containing liposomes (1-3 microg), Me+CDI urea-AOM (2 microg), and DNA (0.5 microg) in 0.5 mL culture medium. Transfections conducted in the presence of free asialoorosomucoid afforded much lower luciferase activity (up to 1.5 x 10(5) relative light units/mg protein) confirming that DNA uptake was predominantly via asialoorosomucoid receptor-mediated endocytosis. We concluded therefore that modular complexes used in our study display the carbohydrate moiety of the glycoprotein component prominently, thus permitting interaction of terminal galactose units with their cognate receptors on the cell membrane.