Effect of inhalation exposure to toluene on the activity of organic anion transporting polypeptide (Oatp) using pravastatin as a probe drug in rats.

1. Toluene, used as a pure substance or in solvent mixtures, is the cause of occupational exposures of large numbers of workers in the world. The organic anion transporting polypeptides (OATP: human; Oatp: rodents) are drug carriers which have been frequently associated to drug-drug interactions. The objective of this study was to evaluate the influence of inhalation exposure to toluene in Oatp in vivo activity using pravastatin as a probe drug in rats. 2. Male Wistar rats ((n = 6 per sampling time) were exposed to 85 mg/m3 toluene by inhalation or air in a nose only exposure system for 6 h/d, 5 d/week during 4 weeks, in order to simulate the occupational exposure to toluene at level slightly above the occupational exposure limit proposed by the American Conference of Governmental Industrial Hygienists (ACGIH). After 4 weeks of exposure, animals received a single dose of 20 mg/kg pravastatin orally. 3. Areas under concentration × time curves extrapolated to infinite (AUC0-∞) were calculated by Gauss Laguerre quadrature. Non-exposed animals showed AUC0-∞ of 726.0 (261.8) ng h/mL for pravastatin and rats exposed to toluene 85 mg/m3 showed AUC0-∞ of 681.8 (80.1) ng h/mL [data presented as mean (standard error of the mean)]. No significant difference was observed in pravastatin kinetic disposition between groups in terms of 95% confidence interval for the difference between means. 4. Toluene exposure by inhalation did not change the in vivo activity of Oatp evaluated by pravastatin kinetic disposition in rats.

Diazepam influences urinary bioindicator of occupational toluene exposure.

In the present study, we investigated the influence of diazepam (DZP) on the excretion of TOL by examining their urinary metabolites, hippuric acid (HA) and ortho-cresol (o-C). Male Wistar rats were exposed to TOL (20ppm) in a nose-only exposure chamber (6h/day, 5days/week for 6 weeks) with simultaneous administration of DZP (10mg/kg/day). Urinary o-C levels were determined by GC-MS, while HA, creatinine (CR), DZP and its metabolite, nordiazepam, were analysed by HPLC-DAD. The results of a Mann-Whitney U test showed that DZP influenced the urinary excretion of o-C (p<0.05). This pioneering study revealed that there was an interaction between DZP and TOL, probably by the inhibition of the CYP isoforms (CYP2B6, CYP2C8, CYP2E1, and CYP1A2) involved in the oxidative metabolism of the solvent. This is relevant information to be considered in the biomonitoring of occupational toluene exposure.

Impact of inhalational exposure to ethanol fuel on the pharmacokinetics of verapamil, ibuprofen and fluoxetine as in vivo probe drugs for CYP3A, CYP2C and CYP2D in rats.

Occupational toxicology and clinical pharmacology integration will be useful to understand potential exposure-drug interaction and to shape risk assessment strategies in order to improve occupational health. The aim of the present study was to evaluate the effect of exposure to ethanol fuel on in vivo activities of cytochrome P450 (CYP) isoenzymes CYP3A, CYP2C and CYP2D by the oral administration of the probe drugs verapamil, ibuprofen and fluoxetine. Male Wistar rats exposed to filtered air or to 2000 ppm ethanol in a nose-only inhalation chamber during (6 h/day, 5 days/week, 6 weeks) received single oral doses of 10 mg/kg verapamil or 25 mg/kg ibuprofen or 10 mg/kg fluoxetine. The enantiomers of verapamil, norverapamil, ibuprofen and fluoxetine in plasma were analyzed by LC-MS/MS. The area under the curve plasma concentration versus time extrapolated to infinity (AUC(0-∞)) was calculated using the Gauss-Laguerre quadrature. Inhalation exposure to ethanol reduces the AUC of both verapamil (approximately 2.7 fold) and norverapamil enantiomers (>2.5 fold), reduces the AUC(0-∞) of (+)-(S)-IBU (approximately 2 fold) and inhibits preferentially the metabolism of (-)-(R)-FLU. In conclusion, inhalation exposure of ethanol at a concentration of 2 TLV-STEL (6 h/day for 6 weeks) induces CYP3A and CYP2C but inhibits CYP2D in rats.

Analysis of ibuprofen enantiomers in rat plasma by liquid chromatography with tandem mass spectrometry.

A sensitive and selective method for the analysis of ibuprofen enantiomers by LC-MS/MS was developed and validated for the purpose of application in pharmacokinetic studies in small experimental animals. Aliquots of 200 µL plasma were submitted to liquid-liquid extraction with hexane/diisopropylether (50:50 v/v) in acid pH. Separation was accomplished in a Chirex® 3005 (250 × 4.6 mm, 5 µm) column at 25°C with a mobile phase that consisted of 0.01 M ammonium acetate in methanol at a flow rate of 1.1 mL/min. The mass spectrometer consisted of an ESI interface operating at negative ionization mode and multiple reaction monitoring. The transitions 205 > 161 and 240 > 197 were monitored for ibuprofen enantiomers and fenoprofen (internal standard), respectively. Method validation included the evaluation of the matrix effect, stability, linearity, lower LOQ, within-run and between-run precision, and accuracy. The lower LOQ was 25 ng/mL for each ibuprofen enantiomer, and the calibration curves showed good linearity in the range 0.025-50 µg/mL. The method was successfully applied in the investigation of pharmacokinetic disposition of ibuprofen enantiomers in rats treated orally with 25 mg/kg of the racemate. Enantioselective kinetic disposition was observed with accumulation of (+)-(S)-ibuprofen in rats following single oral administration.

Influence of gasoline inhalation on the enantioselective pharmacokinetics of fluoxetine in rats.

Fluoxetine is used clinically as a racemic mixture of (+)-(S) and (-)-(R) enantiomers for the treatment of depression. CYP2D6 catalyzes the metabolism of both fluoxetine enantiomers. We aimed to evaluate whether exposure to gasoline results in CYP2D inhibition. Male Wistar rats exposed to filtered air (n = 36; control group) or to 600 ppm of gasoline (n = 36) in a nose-only inhalation exposure chamber for 6 weeks (6 h/day, 5 days/week) received a single oral 10-mg/kg dose of racemic fluoxetine. Fluoxetine enantiomers in plasma samples were analyzed by a validated analytical method using LC-MS/MS. The separation of fluoxetine enantiomers was performed in a Chirobiotic V column using as the mobile phase a mixture of ethanol:ammonium acetate 15 mM. Higher plasma concentrations of the (+)-(S)-fluoxetine enantiomer were found in the control group (enantiomeric ratio AUC((+)-(S)/(-)-(R)) = 1.68). In animals exposed to gasoline, we observed an increase in AUC(0-∞) for both enantiomers, with a sharper increase seen for the (-)-(R)-fluoxetine enantiomer (enantiomeric ratio AUC((+)-(S)/(-)-(R)) = 1.07), resulting in a loss of enantioselectivity. Exposure to gasoline was found to result in the loss of enantioselectivity of fluoxetine, with the predominant reduction occurring in the clearance of the (-)-(R)-fluoxetine enantiomer (55% vs. 30%).

Simultaneous analysis of the enantiomers of verapamil and norverapamil in rat plasma by liquid chromatography-tandem mass spectrometry.

An enantioselective micromethod for the simultaneous analysis of verapamil (VER) and norverapamil (NOR) in plasma was developed, validated and applied to the study of the kinetic disposition of VER and NOR after the administration of a single oral dose of racemic-VER to rats. VER, NOR and the internal standard (paroxetine) were extracted from only 100-microL plasma samples using n-hexane and the enantiomers were resolved on a Chiralpak AD column using n-hexane:isopropanol:ethanol:diethylamine (88:6:6:0.1) as the mobile phase. The analyses were performed in the selected reaction monitoring mode. Transitions 456>166 for VER enantiomers, 441>166 for NOR enantiomers and 330>193 for the internal standard were monitored and the method had a total chromatographic run time of 12 min. The method allows the determination of VER and NOR enantiomers at plasma levels as low as 1.0 ng/mL. Racemic VER hydrochloride (10mg/kg) was given to male Wistar rats by gavage and blood samples were collected from 0 to 6.0 h (n=6 at each time point). The concentration of (-)-(S)-VER was three folds higher than (+)-(R)-VER, with an AUC ratio (-)/(+) of 2.66. Oral clearance values were 12.17 and 28.77 L/h/kg for (-)-(S)-VER and (+)-(R)-VER, respectively. The pharmacokinetic parameters of NOR were not shown to be enantioselective.

[Effect of a novel soy fermented product enriched with isoflavones and calcium on bone tissue of rats]. / Efeito de um novo produto fermentado de soja, enriquecido com isoflavonas e cálcio, sobre o tecido osseo de ratas.

The objective was to evaluate the effect of soy fermented product intake on the corporal weight and bone tissue of ovariectomized mature rats. This product was fermented with Enterococcus faecium and Lactobacillus jugurti and enriched with isoflavones and calcium. The animals were divided in 5 groups: sham-ovariectomized; ovariectomized; ovariectomized treated with soy fermented product enriched with isoflavones and calcium; ovariectomized treated with soy fermented product enriched with calcium and ovariectomized treated with non-fermented product enriched only with calcium. In order to evaluate the effect of the tested product on bone tissue (femur and tibia), the following parameters were analyzed: length; mechanical assay of three points; density (Archimedes principle); mineral content; calcium content; measure of the trabecular widths. The corporal weight of group treated with soy fermented product containing isoflavones and calcium showed no statistical difference from sham-ovariectomized group and trabecular widths tended to have larger than ovariectomized group. However, there was no significant difference to the other evaluated parameters in result of the diverse treatments. Thus, soy fermented product enriched with isoflavones and calcium inhibited the increasing of corporal weight caused by ovariectomy and revealed a tendency to trabecular protection after castration.

Efeito de um novo produto fermentado de soja, enriquecido com isoflavonas e cálcio, sobre o tecido ósseo de ratas / Effect of a novel soy fermented product enriched with isoflavones and calcium on bone tissue of rats

O objetivo deste estudo foi avaliar o efeito da ingestao de um produto a base de soja, fermentado com Enterococcus faecium e Lactobacillus jugurti, enriquecido com isoflavonas e cálcio sobre o peso corpóreo e sobre o tecido ósseo de ratas maduras ovariectomizadas. Os animais foram divididos em 5 grupos: pseudo-ovariectomizados, ovariectomizados, ovariectomizados que ingeriram produto fermentado de soja enriquecido com isoflavonas e cálcio, ovariectomizados que ingeriram produto fermentado de soja enriquecido com cálcio e ovariectomizados que ingeriram produto não fermentado enriquecido com cálcio. Tíbias e fêmures foram utilizados para análise do comprimento ósseo; ensaio mecânico de flexao de três pontos; densidade óssea (princípio de Arquimedes); conteúdo mineral ósseo; conteúdo de cálcio ósseo e medida das larguras das trabéculas. A ingestao do produto fermentado de soja enriquecido com isoflavonas e cálcio apesar de nao ter exercido efeitos nos parâmetros como comprimento, densidade, conteúdo mineral, conteúdo de cálcio e carga máxima suportada, foi capaz de evitar o aumento de peso corpóreo causado pela ovariectomia, além de ter demonstrado uma tendência à proteçao das trabéculas, prevenindo a reduçao da largura das mesmas ocasionada pela castraçao

Determination of acetonitrile and cyanide in rat blood: application to an experimental study.

Methods were developed for the analysis of acetonitrile and its metabolite cyanide in the blood of rats exposed to acetonitrile. Acetonitrile was analyzed by the headspace technique coupled to gas chromatography with detection by flame ionization, and cyanide was analyzed by high-performance liquid chromatography with fluorescence detection (lambdaex = 418 nm and lambdaem = 460 nm) after derivatization of the ion with naphthalene 2,3-dicarboxyaldehyde and taurine. The quantitation limits of the methods for the analysis of acetonitrile and cyanide were 4.875 microg/mL and 0.025 microg/mL, respectively. The coefficients of variation of 10% or less obtained for intra- and interassay precision indicate the precision of these analytical methods and the systematic errors, all less than 5%, indicate that the methods are quite accurate. The methods were applied to an experimental study after the animals received acetonitrile at the doses of 2 mmol/kg or 5 mmol/kg.

Avaliaçäo da exposiçäo ocupacional a solventes e a material particulado em procedimentos de repintura automotiva / Evaluation of occupational exposure for solvents and total aerosol in procedures of automotive paint

Foi avaliada a exposiçäo profissional a solventes e a material particulado, através de amostragem pessoal, de 26 pintores ocupados em oficinas de repintura automotiva. Simultaneamente, foram coletadas amostras de urina pré e pós-exposiçäo dos pintores, para determinaçäo das concentraçöes de creatinina e dos ácidos hipúrico e metil-hipúrico (Grupo Exposto), bem como de um grupo de indivíduos näo expostos a soventes (Grupo Controle), pareados por idade. O objetivo foi verificar a quais solventes os pintores estavam expostos, a magnitude da exposiçäo a solventes e a material particulado, e as correlaçöes entre a concentraçäo dos produtos de biotransformaçäo na urina com a concentraçäo dos precursores e do conjunto de solventes no ar.

Biomonitorizaçäo das exposiçöes ocupacionais / Biological monitoring of ocupational exposure

A monitorizaçäo biológica da exposiçäo a agentes químicos é fator relevante de prevençäo das doenças ocupacionais. O presente trabalho aborda, sucintamente, aspectos conceituais da biomonitorizaçäo e de sua importância em Saúde Ocupacional

Indicadores biológicos de exposiçäo aos metais / Biological parameters of occupational exposures to metals, including reference and biological limit values, are briefly reported in this paper

Säo abordados sucintamente os principais indicadores biológicos de exposiçäo aos metais, valores de referência e limites biológicos

Indicadores biológicos de exposiçäo aos praguicidas / Biological parameters of pesticides exposures

Säo apresentados os principais indicadores biológicos de exposiçäo, valores de referência e limites de tolerância biológicos dos seguintes praguicidas: compostos organofosforados, compostos carbamatos, compostos ciclodienos, lindano, DDT, pentaclorofenol, 2,4-D, dinitro-o-cresol e compostos etileno-bis-ditiocarbamatos

A simple method for the colorimetric determination of thiocyanate in urine

Utilizou-se o reativo de Pettigrew e Fell para a padronizaçäo de método colorimétrico de doseamento de tiocianato na urina. Os pigmentos e as proteínas normalmente presentes na urina foram removidos pela eluiçäo da amostra em coluna contendo silicagel G 60 e florisil. O eluato é tratado com bromo e a reaçäo final é obtida com o reagente piridina -1,4 - fenilenodiamina, sendo a absorbância do corante formado determinada no comprimento da onda correspondente ao ponto isosbéstico da reaçäo (520 nm). A curva de calibraçäo é linear até 16 mg/l

Comparaçäo de dois métodos para determinaçäo da atividade da colinesterase plasmática / Comparation between two methods to determine the plasmatic cholinesterase activity

Em se tratando de intoxicaçäo por praguicidas derivados de compostos fosforados ou carbamatos, o efeito tóxico imediato, quando näo tiver como mecanismo a alteraçäo direta nos receptores colinérgicos pós-sinápticos, será o mesmo, proveniente da inibiçäo da acetilcolinesterase. Visando uma avaliaçäo rápida desse índice biológico de exposiçäo (atividade da colinesterase plasmática), foi executada uma série de análises por dois métodos diferentes. O método do pH Stat (PICKERING & PICKERING, 1971) apresentou média e desvio-padräo de 3,18 ñ 0,63 e 2,59 ñ 0,6 *mol/min/ml; enquanto o método eletrométrico (MICHEL, 1949) apresentou média e desvio-padräo de 1,01 ñ 0,21 e 0,87 ñ 0,24 pH/h, respectivamente, para os sexos masculino e feminino. Utilizando o método do pH Stat os coeficientes de variaçäo (C.V.) foram de 20 e 23%; enquanto para o método eletrométrico os C.V. foram de 21 e 27%, respectivamente, para os sexos masculino e feminino. Os coeficientes de correlaçäo entre os dois métodos foram 0,842 e 0,889, respectivamente, para os sexos masculino e feminino. Com relaçäo à urgência, o método de MICHEL (1949) despende 1 hora no mínimo, enquanto o pH Stat pode confirmar ou näo a inibiçäo reprodutibilidade e sensibilidade, o método de PICKERING & PICKERING é cerca de 2,5 vezes mais econômico que o de MICHEL. Por outro lado, deve-se ressaltar que o método do pH Stat é mais trabalhoso, portanto, exige-se maior perícia do técnico.

Teores de metais no cabelo de crianças com idade até 7 anos / Metal contents in hair of children until 7 years old

Concentraçäo de chumbo, cobre, zinco,cálcio, ferro e magnésio, foram determinadas em 144 amostras de cabelo de crianças, aparentemente normais, com idade até 7 anos, subdivididas em 5 faixas etárias iguais para cada sexo

O mercúrio na odontologia / Mercury in odontology

Os cirurgöes-dentistas e auxiliares aos manipularem o mercúrio elementar, no preparo de amálgamas, estäo expostos ao referido metal. 60,4% dos profissionais cirurgiöes-dentistas, e 59,1% das auxiliares apresentaram teores urinários superiores a 10 ug/L

Reaçäo do tecido subcutâneo do rato ao implante de uma liga binária do sistema cobre-alumínio: avaliaçäo dos níveis séricos de cobre / Reaction of rat subcutaneous tissue to the implantation of a binary CuAl alloy: evaluation of the seric levels of copper

Os autores estudaram a reaçäo do tecido subcutâneo do rato ao implante de uma liga do sistema cobre/alumínio. Avaliaram, também, os níveis séricos de cobre. Os animais foram sacrificados às 48 e 72 horas, 7, 21 e 60 dias pós-operatórios. A análise do cobre sérico foi realizada através de espectrofotometria de absorçäo atômica