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PubMed2005

Evaluation of the interface between one-bottle adhesive systems and dentin by Goldner's trichrome.

PURPOSE: To evaluate the hybrid layers in interfaces between dentin and six contemporary one-bottle adhesive systems using a nondestructive differential staining micro-technique. METHODS: The adhesive systems used in this study were divided to three groups based on hydrophilic/hydrophobic component ratios (i.e. ability to dissolve in water), from highest to lowest as follows: Group 1 (Dentastic UNO.DUO, PermaQuick PQ1) > Group 2 (One-Step, Primer&Bond NT) > Group 3 (Optibond Solo, Single Bond). The occlusal third of the crown was removed from 36 extracted, unerupted human 3rd molars. Smear layers were created by abrading the dentin with 600 grit SiC under water. The exposed dentin was treated with one of the adhesive systems per manufacturer's instructions. After 24 hours in water, 3-5 microm thin sections of the adhesive/dentin (adhesive/dentin ) interface were cut with a microtome and stained with Goldner's trichrome. Stained thin sections from each prepared tooth were imaged with light microscopy. RESULTS: The thickness and color difference of adhesive/dentin interfaces among these one-bottle adhesive systems were clearly visualized. The width of the hybrid layers varied, ranged from 4.1-9.2 microm for six adhesive systems. The color differences in the stained sections are reflected to the extent and degree to which the adhesive envelops the exposed collagen. Among these six bonding systems, resin encapsulation of collagen varied from highest to lowest as follows: Group 1 (UNO, PQ1) > Group 2 (OS, PBNT) > Group 3 (OP, SB). The differences in collagen encapsulation are dependent on the adhesive composition, or the ability to tolerate water during the infiltration of the wet demineralized matrix.

Azo Compounds↗
PubMed1994

Shear bond strength of a composite resin after delayed bonding to a polymerised dentine bonding system.

Polymerised adhesive may serve as a temporary sealant on prepared dentine surfaces and may be used as a precursor to the final bonding of a resin restoration. This procedure may, however, have an adverse effect on the strength of the final bond. This study was undertaken on 40 extracted human molar teeth to assess the effect of delayed bonding on the shear bond strength of a composite resin luted with a luting resin to abraded dentine treated with the Scotchbond Multi-Purpose (SMP) Bonding System (3M). No significant difference (p = 0.969) could be demonstrated between shear bond strengths achieved after immediate and delayed bonding to the polymerised Scotchbond Multi-Purpose adhesive.

Analysis of Variance↗
PubMed2005

Estrogenic activity of impurities in industrial grade bisphenol A.

The estrogenicities of 10 compounds found as impurities in industrial grade bisphenol A (BPA) were measured by yeasttwo-hybrid assays incorporating the human estrogen receptor alpha(hERalpha) orthe medaka fish (Oryziaslatipes) estrogen receptor alpha (medERalpha). Five impurities showed greater activity than BPA itself in an agonist assay for hERalpha. p-Cumylphenol, the most active of the impurities in the hERalpha assay, was 12 times as active as BPA. The REC10 (10% relative effective concentration: 10% of the activity of 10(-8)M 17,B-estradiol) was 710 nM. Five impurities showed greater activity than BPA in an agonist assay for medERa: 4,4'-(1,3-dimethylbutylidene) bisphenol and 2-(4'-hydroxy-phenyl)-2,4,4-trimethylchroman were nearly equipotent and 9 times as active as BPA, and the REC10 values of these compounds in the medERalpha assay were 280 and 320 nM, respectively. Comparison of the experimentally determined estrogenicities of mixtures of BPA and 4,4'-(1,3-dimeth-ylbutylidene) bisphenol and those calculated by the concentrations addition (CA) method confirmed the suitability of the method for the prediction of the estrogenicities of the mixtures of BPA and its phenolic analogues. The measured estrogenicities of four samples of industrial grade BPA and laboratory grade (pure) BPA were not significantly different in either the hERalpha assay or the medERalpha assay (p > 0.05 in each case). We conclude that the impurities in industrial grade BPA, although some are of much higher estrogenic activity than BPA itself, do not significantly increase the estrogenicity of the industrial compound and therefore do not increase possible adverse health effects from such activity.

Animals↗
PubMed2026

Bisphenols and their role in female infertility and hormone-related cancer.

Various types of external chemicals can disrupt the endocrine system, interfering with normal hormone function and causing a broad spectrum of negative health effects. Endocrine-disrupting chemicals (EDCs) are a diverse group of natural and synthetic chemicals that are known to contaminate the environment. It is postulated that these agents can contribute to the development of many diseases, including infertility and cancer, because of their ability to interfere with estrogen receptors (ERs). Bisphenols (BPs) are a group of compounds that belong to EDCs, the most common of which is bisphenol A (BPA). Due to restrictions on the use of BPA in industry, analogues such as bisphenol S (BPS) and bisphenol F (BPF) have been introduced. However, some reports indicate that BPA analogues also have negative effects on the endocrine system in both humans and animals because of their structural similarity. This review summarises current knowledge related to BPA, its analogues and their role in female infertility and hormone-related cancers. Furthermore, this review also points to the problem of exposure to more than one estrogenic agent and highlights the importance of considering exposure to multiple chemicals when assessing health effects and setting daily limits.

Humans↗
PubMed2004

Impurities in industrial grade 4,4'-isopropylidene diphenol (bisphenol A): possible implications for estrogenic activity.

Fifteen trace impurities, including a novel cyclohexene derivative, have been identified and quantified in samples of an industrial grade of the oestrogen-active compound 4,4'-isopropylidene diphenol (bisphenol A). All of these compounds, like bisphenol A itself, possess phenolic hydroxyl groups para to other substituents and all thus might also have oestrogenic properties. Published studies on the endocrine disrupting properties of bisphenol A have not considered potentially active impurities but full assessment of the oestrogenicity of bisphenol A, as it is used commercially, will become possible when adequate supplies of these compounds are available through synthesis.

Benzhydryl Compounds↗
PubMed2006

Simultaneous determination of the endocrine disrupting compounds nonylphenol, nonylphenol ethoxylates, triclosan and bisphenol A in wastewater and sewage sludge by gas chromatography-mass spectrometry.

An integrated analytical method for the simultaneous determination of 4-n-nonylphenol (4-n-NP), nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO), bisphenol A (BPA) and triclosan (TCS) in wastewater (dissolved and particulate phase) and sewage sludge was developed based on gas chromatography-mass spectrometry. Chromatographic analysis was achieved after derivatization with bis(trimethylsilyl)trifluoroacetamide (BSTFA). Extraction from water samples was performed by solid-phase extraction (SPE). The optimization of SPE procedure included the type of sorbent and the type of the organic solvent used for the elution. Referred to solid samples, the target compounds were extracted by sonication. In this case the optimization of the extraction procedure included the variation of the amount of the extracted biomass, the duration and the temperature of sonication and the type of the extraction organic solvent. The developed extraction procedures resulted in good repeatability and reproducibility with relative standard deviations (RSDs) less than 13% for all the tested compounds for both types of samples. Satisfactory recoveries were obtained (>60%) for all the compounds in both liquid and solid samples, except for 4-n-NP, which gave recoveries up to 35% in wastewater samples and up to 63% in sludge samples. The limits of detection (LODs) of the target compounds varied from 0.03 (4-n-NP) to 0.41 microg l(-1) (NP2EO) and from 0.04 (4-n-NP) to 0.96 microg kg(-1) (NP2EO) for liquid and solid samples, respectively. The developed methods were successfully applied to the analysis of the target compounds in real samples.

Endocrine Disruptors↗
PubMed1999

A parameter for detecting estrogenic exposure in the copepod Acartia tonsa.

Literature on the basic endocrinology of crustaceans, such as crab, lobster and shrimp, suggest that estrogens, e.g., 17beta-estradiol, are stimulating hormones in female sexual maturation and egg production in crustaceans. The copepod Acartia tonsa, has continuous egg production. A profile of the egg production per time unit through the maturation of this species may be used as an expression of the degree of maturation of the female internal reproductive organs. Comparison of control profiles with profiles of estrogen-exposed copepods may thus demonstrate that estrogen exposure results in a steeper maturation profile. The proposed endpoint was identified by exposing copepods to the natural estrogen 17beta-estradiol and the antropogenic estrogen bisphenol A. Both compounds produced significant effects at 23 and 20 microg/L, respectively. Since bisphenol A is traditionally believed to be less estrogenic than 17beta-estradiol, the nonestrogen 2, 3-dichlorophenole was tested at 13.6 microg/L (molar concentration equal to 23 microg/L 17beta-estradiol) to test if the response is a general nonestrogenic toxic stress effect. The 2,3-dichlorophenole produced no effect.

Animals↗
PubMed2000

Determining relative estrogenicity by quantifying vitellogenin induction in rainbow trout liver slices.

Precision cut tissue slices, by modeling the entire organ, are a valuable tool for studying protein induction or inhibition by test chemicals. This manuscript describes parameters to quantify relative estrogenicity of chemicals in rainbow trout liver slices by measuring vitellogenin (Vg) induction, a well-characterized biomarker of estrogen receptor signal transduction. Hank's medium (phenol-red free) supplemented with Hepes, sodium bicarbonate, and 1% bovine serum albumin was utilized. The experimental parameters were optimized using 1000 nM 17beta-estradiol, a potent estrogen in rainbow trout that induces Vg production in vivo. The addition of trout serum and retention of the media was essential, probably to allow for the accumulation of Vg in the slices and media. Histological examination and ATP analyses indicated no toxicity in control or 17beta-estradiol-treated liver slices after 120 h. Induction was 4-fold greater with 25% serum containing media compared to media with 10% serum. We observed Vg induction as great as 500-fold over controls at 96 h in liver slices and media containing 25% serum and 1000 nM 17beta-estradiol. Controls without 17beta-estradiol, incubated in media with 10 or 25% serum, exhibited no detectable Vg production, indicating that the induction seen was not from the media or serum. We observed that 48 h was required for significant Vg induction in the media and liver slices. Maximum induction in slices occurred at 96 h, whereas media Vg levels continued to increase to 120 h, suggesting a time delay between Vg production and excretion by the liver. The feasibility of this model to detect weak environmental estrogens was determined with 0-250 microM o,p'DDE and bisphenol A. Both compounds induced Vg in this model with EC50 values of 10(4) and 2x10(5) higher than E(2), respectively. Our results indicate the importance of media, serum, and time selection for optimal Vg induction. This model allows for the determination of relative estrogenicity of chemicals in a controlled in vitro system while utilizing the advantages of precision cut slice technology.

Adenosine Triphosphate↗
PubMed2004

Bisphenol a glucuronidation and excretion in liver of pregnant and nonpregnant female rats.

In male rats challenged with the environmental estrogen bisphenol A, the compound is highly glucuronidated in the liver and is excreted largely into the bile. Given that in pregnancy the microsomal glucuronidation toward bisphenol A is attenuated, we hypothesized that elimination of bisphenol A from the liver may be reduced in pregnancy. This study was conducted to trace the elimination of bisphenol A in female rats, especially in pregnancy. In Sprague-Dawley rats, 1.5 mumol of bisphenol A was perfused into the liver via the portal vein. In both the male and the nonpregnant female, the infused bisphenol A was glucuronidated, then the resultant glucuronide was excreted mainly into the bile. In pregnant rats, however, bilious excretion of bisphenol A glucuronide was 60% of that observed in nonpregnant rats, and venous excretion increased reciprocally. During 1-h perfusion, total excretion of the glucuronide from the liver of male, nonpregnant female, and pregnant rats was 889.5 +/- 69.6, 1256.7 +/- 54.8, and 1038.8 +/- 33.3 nmoles, respectively. In Eisai hyperbilirubinemic rats (EHBR), perfusion of the liver with bisphenol A enabled us to determine that multidrug resistance-associated protein (MRP)2-mediating transport is the mechanism behind excretion of the glucuronide into the bile. The expression of MRP2 has been reported to be noticeably reduced in pregnancy. These results suggest that bisphenol A elimination by hepatic glucuronidation is slightly less in pregnancy than in non-pregnancy and that in pregnancy, more bisphenol A glucuronide is eliminated to the vein because of reduced MRP2 expression.

Animals↗
PubMed2003

Simple and rapid analysis of endocrine disruptors in liquid medicines and intravenous injection solutions by automated in-tube solid-phase microextraction/high performance liquid chromatography.

A simple and rapid method was developed for analyzing contamination of endocrine disruptors in liquid medicines and intravenous injection solutions. Endocrine disrupting compounds such as bisphenol A (BPA), alkylphenols and phthalates were quantitated by on-line in-tube solid-phase microextraction coupled with high performance liquid chromatography (in-tube SPME/HPLC) with UV detection. The liquid medicines and intravenous injection solutions could be used directly without any pretreatment, and the BPA, alkylphenols and phthalates in these solutions were automatically analyzed. The limits of quantification for these compounds were 1-10 ng/ml. Recoveries of these compounds spiked to the intravenous injection solutions was over 80%, except for some phthalates. Di-n-butyl phthalate (DBP) was detected at a concentration of 7-60 ng/ml in most intravenous injection solutions in plastic containers, but it was not detected in solutions in glass bottles. Diethyl phthalate, di-n-propyl phthalate, DBP and di-2-ethylhexyl phthalate (DEHP) were also detected in syrup, lotion and eye drops in plastic containers. On the other hand, BPA and alkylphenols were not detected at all in these solutions. DEHP contamination from an administration set increased when total vitamin formulation was added to the infusion solution. DEHP was easily leached from polyvinyl chloride tubing by polysorbate 80. The in-tube SPME/HPLC method is simple, rapid and automatic, and it provides a useful tool for the screening and determination of endocrine disruptor contamination in liquid medicines and intravenous injection solutions.

Autoanalysis↗
PubMed2000

Detection of bisphenol-A in dental materials by gas chromatography-mass spectrometry.

The xenoestrogenic substance bisphenol-A is widely used as a synthetic precursor of resin monomers, such as bisphenol-A diglycidyl methacrylate. Reports describing the release of bisphenol-A from polymerized resin into saliva have aroused considerable concern regarding exposure to xenoestrogen by dental treatment. The purpose of the present study was to demonstrate a reliable methodology of detecting the trace amounts of bisphenol-A in dental materials. Bisphenol-A was separable from bisphenol-A diglycidyl methacrylate, which is often employed as the principal dimethacrylate monomer, by selective extraction with a Sep-Pak C18 cartridge. Using this extraction method in combination with a gas-chromatography mass-spectrometry, we have obtained evidence that all unpolymerized materials used in this study were contaminated with bisphenol-A. Quantitative analysis using a deuterium-labeled compound as an internal standard revealed bisphenol-A contents in commercial dental materials ranging from < 1 microgram/g material to about 20 micrograms/g material. The polymerized dental materials released up to 91.4 ng bisphenol-A/g material into phosphate buffered saline during 24-h incubation. These results indicate that bisphenol-A can be released from dental materials, however the leachable amount would be less than 1/1000 of the reported dose (2 micrograms/kg body weight/day) required for xenoestrogenisity in vivo.

Benzhydryl Compounds↗
PubMed2004

Simultaneous determination of isoflavones and bisphenol A in rat serum by high-performance liquid chromatography coupled with coulometric array detection.

A method for simultaneous detection and quantification is presented to determine the presence of isoflavones and bisphenol A in a biological sample. A coulometric array detector was used with reversed-phase high-performance liquid chromatography (HPLC). Daidzein (1), glycitein (2), genistein (3) and their glucoside conjugates, daidzin (4), glycitin (5) and genistin (6), were measured as phytochemicals. Also assayed here was equol (7), a metabolite from compound 1, and bisphenol A (8), an industrial chemical that acts as an endocrine disrupter. All chemicals were simultaneously detected by using a 600-mV single detection voltage with high efficacy. A mixture of 1, 3 and 8 was orally administered to rats, and the levels of these three chemicals in the serum were clearly increased after a 4 kU beta-glucuronidase treatment. The levels of compounds 1 and 3 in the serum were detected at 1665 and 2040 ng/ml, while 8 was at a low level of 417 ng/ml. Compound 7 in the serum was not detected until after enzymatic hydrolysis (72 ng/ml). These results suggest that this analytical method would be useful for metabolic and pharmacokinetic studies on isoflavones and bisphenol A.

Administration, Oral↗
PubMed2003

Preparation of uniformly sized molecularly imprinted polymers for phenolic compounds and their application to the assay of bisphenol A in river water.

Uniformly sized molecularly imprinted polymers, which can recognize bisphenol A (BPA), have been prepared by a multi-step swelling and polymerization method using BPA or a structurally related analogue of BPA [p-t-octylphenol (OP) or p-t-butylphenol (BP)] as the template molecule, 4-vinylpyridine as the functional monomer, and ethylene glycol dimethacrylate as the cross-linker. The BP-imprinted polymer showed higher molecular recognition ability for BPA than the OP-imprinted polymer. The BPA- and BP-imprinted polymers were applied for the assay of a trace amount of BPA in river water using column-switching HPLC with fluorescence detection: A BPA-imprinted polymer was used for removal of BPA from the pretreatment eluent as the trap column, and a BP-imprinted polymer was used for selective pretreatment and enrichment of BPA in river water as the pretreatment column. The calibration graph, constructed from peak area data plotted versus BPA concentration, was linear with a correlation coefficient of >0.999 in the concentration ranges of 25-1000 ppt. The limit of quantitation was 25 ppt with a 5-ml injection. The column-switching HPLC system was successfully applied for the assay of BPA in river water.

Benzhydryl Compounds↗
PubMed2000

Analysis of major components and bisphenol A in commercial Bis-GMA and Bis-GMA-based resins using high performance liquid chromatography.

The purpose of this study was to examine the quality of commercially available Bis-GMA because concerns about Bis-GMA and Bis-GMA-based resins have been recently expressed in dentistry. Four major components and bisphenol A, which is a compound of recent controversy, were quantitatively analyzed using high performance liquid chromatography (HPLC) in three commercial Bis-GMA and six Bis-GMA-based composite resins. The contents of genuine Bis-GMA, Iso-bis-GMA, Bis-GMA-H, and Bis-GMA-M as well as the total content of the four monomers were 45.7-57.5%, 19.9-26.2%, 1.8-5.0%, 0.6-15.0% and 83.7-85.6% in the commercial Bis-GMAs, or 3.8-9.1%, 1.7-4.3%, 0.1-0.5%, 0.1-2.0% and 5.8-14.0% in composite resins, respectively. There were some differences in the composition of the major components between domestic and foreign materials. Bisphenol A contents in the unpolymerized composite resins were 1.5-10.2 micrograms/g resin.

Benzhydryl Compounds↗
PubMed2004

Monitoring of estrogens, pesticides and bisphenol A in natural waters and drinking water treatment plants by solid-phase extraction-liquid chromatography-mass spectrometry.

A multi-residue analytical method has been developed for the determination of various classes of selected endocrine disruptors. This method allows the simultaneous extraction and quantification of different estrogens (estradiol, estrone, estriol, estradiol-17-glucuronide, estradiol diacetate, estrone-3-sulfate, ethynyl estradiol and diethylstilbestrol), pesticides (atrazine, simazine, desethylatrazine, isoproturon and diuron), and bisphenol A in natural waters. In the method developed, 500 ml of water are preconcentrated on LiChrolut RP-18 cartridges. Further analysis is carried out by liquid chromatography-mass spectrometry (LC-MS) using atmospheric pressure chemical ionisation (APCI) in the positive ion mode for determination of pesticides and electrospray in the negative ionisation mode for determination of estrogens and bisphenol A. Recoveries for most compounds were between 90 and 119%, except for bisphenol A (81%) and diethylstilbestrol (70%), with relative standard deviations below 20%. Limits of detection ranged between 2 and 15 ng/l. The method was used to study the occurrence of the selected pollutants in surface and groundwater used for abstraction of drinking water in a waterworks and to evaluate the removal efficiency of the different water treatments applied. Water samples from the river, the aquifer, and after each treatment stage (sand filtration, ozonation, activated carbon filtration and post-chlorination) were taken monthly from February to August of 2002. The presence in river water of atrazine, simazine, diuron and bisphenol A were relatively frequent at concentrations usually below 0.1 microg/l. Lower levels, below 0.02 microg/l, were usual for isoproturon. Estrone-3-sulfate and estrone were detected occasionally in the river. Most of the compounds were completely removed during the water treatment, especially after activated carbon filtration.

Benzhydryl Compounds↗