Time course of enzyme induction in liver and kidneys and absorption, distribution and elimination of 1,4-dichlorobenzene in rats

Time course of enzyme induction was measured in Fischer344 rats treated daily at 150 and 600 mg 1,4-dichlorobenzene (1.4-DCB)/kg p.o. up to 28 days. The monoxygenases 7-ethoxycoumarin O-deethylase (ECOD), 7-ethoxyresorufin O-deethylase (EROD) and aldrin epoxidase (ALD) as well as the phase II enzymes; epoxide hydrolase (EH), glutathione S-transferase (GS-T) and glucuronyl transferase (GLU-T) were dose-dependently induced in the liver of males and females. A pronounced induction in the kidneys was measured at 600 mg/kg only for ECOD. After single oral administration of 100 and 1000 mg/kg bw and feeding of 100 and 1000 ppm (corresponding to approximately 10 and 100 mg/kg bw) to male Wistar rats for 28 days, the time course of 1,4-DCB and 2,5-DCP concentrations was investigated in plasma, adipose, hepatic and renal tissue. In addition, total urinary excretion of 2,5-DCP was determined. After single application, 1,4-DCB and 2,5-DCP were rapidly eliminated from the plasma and tissues, 40-60% of the dose administered was excreted as 2,5-DCP in the urine. There were no indications of cumulative effects after a feeding period of 28 days. The concentrations decreased in all tissues until the 7th day of study. Thereafter, there seems to be a steady state until the 28th day. A total of 7 days after the end of exposure, no more residues could be detected. Following long-term inhalation (450 and 3000 mg/m3) 1,4-DCB concentrations were highest in adipose tissues at 6 months followed by a marked decline at 18 months. 1,4-DCB and 2,5-DCP concentrations in plasma and liver were much lower but again with a peak at 6 months. When compared with published human data on measurements in plasma, urine, liver and adipose tissue the results suggest that there should be no hazard for the general population.     

Variation in chlorobenzoate catabolism by Pseudomonas putida P111 as a consequence of genetic alterations

Pseudomonas putida P111 is able to utilize a broad range of monochlorinated, dichlorinated, and trichlorinated benzoates. The involvement of two separate dioxygenases was noted from data on plasmid profiles and DNA hybridization. The benzoate dioxygenase, which converts 3-chlorobenzoate (3-CB), 4-CB, and benzoate to the corresponding catechols via reduction of a dihydrodiol, was shown to be chromosomally coded. The chlorobenzoate-1,2-dioxygenase that converts ortho-chlorobenzoates to the corresponding catechols without the need of a functional dioldehydrogenase was shown to be encoded on plasmid pPB111 (75 kb). Cured strains were unable to utilize ortho-chlorobenzoates for growth. DNA hybridization data indicated that catabolism of the corresponding chlorocatechols was coded on chromosomal genes. Maintenance of plasmid pPB111 was dependent on the presence of ortho-chlorobenzoates in the growth media. A unique variant of P111 (P111D), able to grow on 3,5-dichlorobenzoate (3,5-DCB), was obtained by continuous subculturing from media containing progressively lower and higher concentrations of 3-CB and 3,5-DCB, respectively. The low frequency of segregants able to grow on 2,5-DCB, 2,3-DCB, and 2,3, 5-trichlorobenzoate was evident by lag periods greater than 200 h. Continued subculture on 3,5-DCB resulted in the formation of new plasmid pPH111 (120 kb), which was homologous to pPB111. A probe from the clc operon, which encodes for the chlorocatechol pathway, hybridized to plasmid pPH111 and to the chromosome of the wild-type strain P111 but not to its plasmid pPB111 nor to the chromosome of strain P111A, which had lost the ability to utilize chlorobenzoates.(ABSTRACT TRUNCATED AT 250 WORDS)     

Urinary thiodiacetic acid. A selective biomarker for the cytochrome P450-catalyzed oxidation of 1,2-dibromoethane in the rat

1,2-Dibromoethane (1,2-DBE) is a carcinogenic compound that is metabolized both by cytochrome P450 (P450) and glutathione S-transferase (GST) enzymes, and that has been used by us as a model compound to study interindividual variability in biotransformation reactions. In this study, the excretion of thiodiacetic acid (TDA) and S-(2-hydroxyethyl)-N-acetyl-l-cysteine (2-HEMA) were measured in the urine of rats dosed with 1,2-DBE, and experiments were performed to investigate to what extent P450 and GST enzymes contribute to the formation of TDA. To this end, CYP2E1, the main P450 isoenzyme catalyzing the oxidation of 1,2-DBE, was inhibited using disulfiram and diallylsulfide. Significant inhibition of CYP2E1, as confirmed by inhibition of the hydroxylation of chlorzoxazone, as well as inhibition of the formation of TDA from 1,2-DBE, was observed upon pretreatment of rats with these inhibitors, indicating that the P450-catalyzed oxidation of 1,2-DBE plays the major role in the TDA formation. No significant excretion of TDA was observed after administration of intermediate products of the GST pathway [i.e. S-(2-hydroxyethyl)glutathione and 2-HEMA], indicating that the GST-catalyzed metabolism of 1,2-DBE does not contribute to a significant extent to the formation of TDA. The results of this study show that TDA is specifically formed by P450 metabolites of 1,2-DBE, whereas the conjugation of 1,2-DBE to glutathione by GST enzymes does not contribute to the formation of TDA. TDA, excreted in urine, may thus be used as a biomarker of exposure to 1,2-DBE selectively reflecting the P450-catalyzed oxidation. In addition to 2-HEMA and S-[2-(N7-guanyl)ethyl]-N-acetyl-l-cysteine, TDA may be a valuable tool for biomonitoring and mechanistic studies into the metabolism and toxicity of 1,2-DBE.     

drp, a novel protein expressed at high cell density but not during growth arrest

In this study the disposition of 1,2-[14C]dibromoethane (1, 2-[14C]DBE) was investigated in male Wistar rats. 1,2-DBE is a cytotoxic and carcinogenic compound that has been used as an additive in leaded gasoline and as a fumigant. 1,2-[14C]DBE was administered orally or iv. Radioactivity was recovered (mostly within 48 hr after administration) in urine (75-82% of the dose), feces (3.2-4% of the dose), and expired air (0.53-7.2% of the dose). One hundred-sixty-eight hours after administration of 1,2-[14C]DBE, most of the radioactivity in tissues was found in the liver, lungs, and kidneys (<1% of the dose) and the red blood cells (0.3% of the dose). Identified urinary metabolites were S-(2-hydroxyethyl)mercapturic acid, thiodiacetic acid, and thiodiacetic acid sulfoxide, together accounting for, on average, 78% of the total amount of radioactivity in urine. In addition to S-(2-hydroxyethyl)mercapturic acid, thiodiacetic acid, and thiodiacetic acid sulfoxide, several compounds were anticipated as potential urinary metabolites of 1,2-DBE, i.e. S-(carboxymethyl)mercapturic acid, S-(2-hydroxyethyl)thioacetic acid, S-(2-hydroxyethyl)thiopyruvic acid, S-(carboxymethyl)thiopyruvic acid, S-(2-hydroxyethyl)thiolactic acid, and S-(carboxymethyl)thiolactic acid. All of the postulated urinary metabolites were synthesized and searched for in urine samples. None of these metabolites could be detected in urine, however. The data obtained in the present study might be useful for risk assessment and biomonitoring studies of 1,2-DBE and will also be used to further validate a physiologically based pharmacokinetic model for 1, 2-DBE in rats and humans that was recently developed.     

Nomograms of the fetal lateral ventricles using transvaginal sonography

An HPLC-UV method for the simultaneous identification of amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine (MDA) and 3,4-methylenedioxymethamphetamine (MDMA) in urine is described. It includes a rapid extraction procedure of the 4 analogs from urine using Extrelut 3 columns, derivatization with sodium 1,2-naphthoquinone-4-sulphonate (NQS) to obtain highly chromophoric UV-VIS derivatives, and a final HPLC analysis using an ion-pair reversed-phase technique with eluent monitoring at 480 nm. Structural characterization of the derivatives obtained by mass spectrometry is reported. Recoveries of the amphetamines were in the range 80-85% at concentrations of 300 ng/ml. Practical detection limits were 40-60 ng/ml (S/N ratio = 10) for all derivatives. The chromatographic peaks of the NQS derivatized amphetamines are fairly narrow and well resolved. The method is simple, rapid, quite sensitive, and specific for convenient confirmation of preliminary positive results obtained with immunoassays.     

Absorption, disposition kinetics, and metabolic pathways of cyclohexene oxide in the male Fischer 344 rat and female B6C3F1 mouse

Cyclohexene oxide (CHO) is a monomer intermediate used in the synthesis of pesticides, pharmaceuticals, and perfumes. Although CHO has a variety of industrial uses where direct human exposure is possible, very little is known about its fate in the body. Therefore, the objectives of this study were to determine the absorption, distribution, metabolism, and excretion of cyclohexene oxide after oral, intravenous, and dermal exposure in male Fischer 344 rats and female B6C3F, mice. After intravenous administration of [14C]CHO (50 mg/kg), CHO was rapidly distributed, metabolized, and excreted into the urine. Plasma concentrations of CHO rapidly declined and were below the limit of detection within 60 min. Average (+/- SD) values for terminal disposition half-life, apparent volume of distribution at steady-state, and systemic body clearance were: 19.3 +/- 1.6 min; 0.44 +/- 0.08 liter/kg; and 31.3 +/- 0.5 ml/kg * min, respectively. After oral administration of [14C]CHO (10 and 100 mg/kg), it was found that 14C-equivalents were rapidly excreted in the urine of both species. At 48 hr, the majority of the dose (73-93%) was recovered in urine, whereas fecal elimination accounted for only 2-5% of the dose. At no time after oral administration was parent CHO detected in the blood. However, its primary metabolite cyclohexane-1,2-diol was present for different lengths of time depending on the dose. Four metabolites were detected and identified in mouse urine by MS: cyclohexane-1,2-diol; cyclohexane-1,2-diol-O-glucuronide; N-acetyl-S-(2-hydroxycyclohexyl)-L-cysteine; and cyclohexane-1,2-diol-O-sulfate. The sulfate conjugate was not present in rat urine. Topical application of [14C]CHO (60 mg/kg) provided poor absorption in both species. The majority of 14C-equivalents applied dermally were recovered from the charcoal skin trap (approximately 90% of the dose). Only 4% of the dose was absorbed, and the major route of elimination was via the urine. To evaluate the toxicity of CHO, animals were given daily doses of CHO orally and topically for 28 days. No statistically significant changes in final body weights or relative organ weights were noted in rats or mice treated orally with CHO up to 100 mg/kg or up to 60 mg/kg when given topically. Very few lesions were found at necropsy, and none were considered compound related. In conclusion, regardless of route, CHO is rapidly eliminated and excreted into the urine. Furthermore, after either oral or dermal administration, it is unlikely that CHO reaches the systemic circulation intact due to its rapid metabolism, and is therefore unable to cause toxicity in the whole animal under the test conditions used in this study.     

Identification of two major F2 isoprostanes, 8,12-iso- and 5-epi-8, 12-iso-isoprostane F2alpha-VI, in human urine

Isoprostanes (iPs) are nonenzymatic, free radical-derived compounds isomeric with enzymatically formed eicosanoids such as prostaglandins, leukotrienes, and thromboxanes. One group formed by the auto-oxidation of arachidonic acid, the F2-iPs, consists of four classes of isomers of prostaglandin F2alpha (PGF2alpha). They are relatively abundant in human urine. This fact, along with their chemical stability and excellent characteristics for quantitation by gas chromatography/mass spectrometry, has made them attractive indices of oxidative stress in humans. We developed a specific assay using gas chromatography/mass spectrometry for the first identified F2-iP, iPF2alpha-III (previously called 8-iso-PGF2alpha or 8-epi-PGF2alpha), which demonstrated the utility of monitoring a specific isomer. Recently, we described an assay for another isomer, iPF2alpha-VI, which is present in urine in greater concentration than iPF2alpha-III and which is particularly amenable to quantitation. We now describe the identification in human urine of two more isomers, 8,12-iso-iPF2alpha-VI and 5-epi-8, 12-iso-iPF2alpha-VI, using high performance liquid chromatography/tandem mass spectrometry and gas chromatography/mass spectrometry. These compounds are each present in approximately 5-fold greater concentrations than iPF2alpha-VI (approximately 20-fold greater than iPF2alpha-III). They share the unique chemical characteristics of class VI compounds, which make them attractive targets for quantitation by gas chromatography/mass spectrometry and immunoassay development.     

Protease activation during nitric oxide-induced apoptosis: comparison between poly(ADP-ribose) polymerase and U1-70kDa cleavage

Nitric oxide (NO) promotes apoptotic cell death in the mouse macrophage cell line RAW 264.7 and in the human promyelocytic leukaemia cell line U937, which exemplifies p53-dependent and p53-independent executive death pathways. Here, we followed the cleavage of two caspase substrates during NO-intoxication, assaying poly(ADP-ribose) polymerase and U1-70kDa small ribonucleoprotein (U1-70kDa) degradation. By using pharmacological inhibitors, we found that Z-aspartyl-2,6-dichlorobenzoyloxymethylketone (Z-Asp-CH2-DCB; 100 microM), a caspase-like protease inhibitor, completely blocked S-nitrosoglutathione (GSNO)-induced apoptosis in both RAW 264.7 and U937 cells (IC50 = 50 microM for RAW 264.7 macrophages vs. IC50 = 33 microM for U937 cells). Notably, a characterized caspase-3 (Ac-DEVD-CHO) inhibitor left NO-induced DNA fragmentation and the appearance of an apoptotic morphology unaltered, although completely blocking caspase-3 activity. However, Z-Asp-CH2-DCB suppressed protease-mediated U1-70kDa cleavage and DNA fragmentation in parallel. In contrast, poly(ADP-ribose) polymerase cleavage in U937 cells was only delayed by Z-Asp-CH2-DCB, while poly(ADP-ribose) polymerase digestion in RAW 264.7 macrophages proceeded unaltered. We further compared U1-70kDa and poly(ADP-ribose) polymerase cleavage in stably Bcl-2 transfected RAW 264.7 macrophages. Rbcl2-2, a Bcl-2 overexpressing clone, suppressed DNA fragmentation and U1-70kDa digestion in response to GSNO, although allowing delayed but complete poly(ADP-ribose) polymerase degradation. Conclusively, poly(ADP-ribose) polymerase cleavage not causatively coincided with the appearance of other apoptotic parameters. Our results suggest that NO-induced apoptosis demands a Z-Asp-CH2-DCB inhibitable caspase activity, most likely distinct from caspase-3 and caspase-1. NO-mediated executive apoptotic signaling results in U1-70kDa and poly(ADP-ribose) polymerase cleavage. Whereas U1-70kDa digestion closely correlates to the occurrence of apoptotic parameters such as DNA fragmentation or an apoptotic morphology, poly(ADP-ribose) polymerase-breakdown does not.     

Structural analysis of phosphatidylcholines of Yoshida ascites hepatoma and liver cells from host rats fed a control and an essential fatty acid-deficient diet

In order to study the effect of a dietetic manipulation on the phospholipid molecular structure of a poorly differentiated tumor, the phosphatidylcholines from Yoshida hepatoma cells (AH130) grown either in essential fatty acid deficient or control rats were analyzed comparatively to those from the host livers. Due to essential fatty acid deficiency, the host rat liver exhibited an increased level of mono-unsaturated 1,2-diacyl-sn-glycero-3-phosphocholines, a reduced level of the species contained linoleic acid, and the substitution of tetra- and polyunsaturated-1,2-diacyl-sn-glycero-3-phosphocholines with equivalent amounts of species containing eicosatrienoic acid. The structural analysis of the phosphatidylcholines from Yoshida hepatoma cells grown either in control or essential fatty acid deficient rats revealed the occurrence of 1-alkyl-2-acyl- together with 1,2-diacyl-sn-glycero-3-phosphocholines. The alkyl chains of ether-linked phosphatidylcholines were mainly constituted by 18 : 1, while the acyl chains were characterized by a high level of linoleic and arachidonic or eicosatrienoic acids. The 1,2-diacyl-sn-glycero-3-phosphocholines of the Yoshida hepatoma cells grown in control rats, when compared to those of the liver, showed a higher level of 1,2-disaturated, an increased proportion of mono-unsaturated and a lower proportion of tetra- and polyunsaturated species. In addition, the hepatoma cells showed the occurrence of high proportions of reverse isomeric and random species, such as 1-oleoyl-2-palmitoyl-, 1,2-dioleoyl-, 1-oleoyl-2-linoleoyl- and 1-linoleoyl-2-oleoyl-sn-glycero-3-phosphocholines, scarcely represented in the liver. Growth of Yoshida hepatoma cells in essential fatty acid deficient rats resulted in :(i) the disappearence of 1,2-diacyl-sn-glycero-3-phosphocholines containing linoleic acid; (ii) the substitution of tetra- and and polyunsaturated 1,2-diacyl-sn-glycero-3-phosphocholines with small quantities of species containing eicosatrienoic acid; (iii) an increase of of monounsaturated species, mainly 1-stearoyl-2-oleoyl- and 1-palmitoyl-2-palmitoleoyl-sn-glycero-3-phosphocholines; (iv) a remarkable increase of 1,2-dioleoyl-sn-1,2-dioleoyl-sn-glycero-3-phosphocholine.     

Seasonal effects on concentrations of monomethylformamide in urine samples

Eleven du Pont operators participated in a special dimethylformamide metabolite (monomethylformamide, MMF) urine monitoring study to investigate a possible seasonal influence on urine metabolite concentrations. Variables considered included urine volume, MMF concentration, MMF mass, urine specific gravity, and ambient temperature. Statistical analysis revealed a 13% reduction in urine volume under hot weather conditions as a cause of increased MMF concentrations. A correction for this change in urine volume should be made subjectively.     

The characterization of cell death induced by 1-(3-C-ethynyl-beta-D-ribo-pentofuranosyl) cytosine (ECyd) in FM3A cells

The characterization of cell death induced by 1-(3-C-ethynyl-beta-D- ribopentofuranosyl) cytosine (ECyd), a potent inhibitor of RNA synthesis, was performed using mouse mammary tumor FM3A cells in vitro. Accompanied with the cell death induced by ECyd (3.0 muM) -treatment, about 100-200 kbp-sized and internucleosomal DNA fragmentation were observed by orthogonal-field-alternation gel electrophoresis (OFAGE) and conventional gel electrophoresis, respectively. Protease inhibitors, carbobenzoxy-L-aspart-1-yl[(2,6-dichlorobenzyl)oxy]methane (Z-Asp-CH2-DCB), N alpha-p-tosyl-L-lysine chloromethyl ketone (TLCK) and N-p-tosyl-L-phenylalanine chloromethyl ketone (TPCK), effectively blocked the cell death, suggesting that the proteases inhibited by Z-Asp-CH2-DCB, TLCK or TPCK were involved in the process of cell death.     

Benzoolysis of diacylglycerophosphocholines: dephosphorylation and sequential formation of isomeric reaction products

Benzoolysis experiments are reported in which diacylglycerophosphocholine is heated at 100 degrees C with benzoic anhydride for variable periods of time. It is shown that more than 90% of the phospholipid is dephosphorylated after 5 h of heating. Lipid extracts of the reaction mixture contained 1,2- and 1,3-diacylglycerobenzoate and 1,2- and 1,3-diacylglycerol in nearly constant isomer ratios of about 3:1 and 1:2, respectively, independent of the heating and extraction time. The total amount of isomeric diacylglycerobenzoates increased more slowly with increasing heating time that corresponded with the dephosphorylation rate, complete benzoylation being attained only after a 15 h heating period. The total amount of isomeric diacylglycerols went through a maximum after about 4 h and vanished after 15 h of heating. Addition of 4-dimethylaminopyridine subsequent to the heating period resulted in rapid and complete benzoylation of dephosphorylated phospholipid. However, the ratio of 1,2- to 1,3-diacylglycerobenzoate then found in the lipid extract depended on heating time, changing from less than 1:1 to about 3:1 upon an increase of heating time from 1 to 15 h. The results are interpreted in terms of two consecutive reactions. In a relatively fast first step, a dephosphorylated intermediate is formed, which in the molten benzoic anhydride, is slowly benzoylated. The intermediate yields diacylglycerols upon extraction in the absence of 4-dimethylaminopyridine and diacylglycerobenzoates upon extraction in the presence of 4-dimethylaminopyridine.     

Urinary metabolites of amixetrine in man and in the dog

The urinary metabolites of N-(2-phenyl-2-isoamyloxy) ethyl-pyrrolidine-hydrochloride (amixetrine) studied in man and in the dog demonstrated a comparable mode of transformation of the drugs for both species. The principal metabolites of amixetrine isolated from urine and purified with the aid of chromatographic techniques were identified by IR, NMR and mass spectrometry. Untransformed amixetrine and (1,2-phenyl-1-hydroxy)ethylpyrrolidine were found in small quantities. In man, as in the dog, the principal metabolite coming from an omega-1-oxidation of the isoamyl chain corresponded to 2-phenyl-2-butoxy-(3-methyl-3-ol)ethyl-pyrrolidine.     

Metabolism of tetramethrin isomers in rat: IV. Tissues responsible for formation of reduced and hydrated metabolites

1. To identify the sites of formation of the reduced metabolites, 3-hydroxy-cyclohexane-1,2-dicarboximide (3-OH-HPI-1 and -2), 1,2-cyclohexanedicarboxylic acid (TCDA) and 1-hydroxy-1,2-cyclohexanedicarboxylic acid (1-OH-HPA), in rat treated with 14C-labelled (1RS, trans)-tetramethrin, [3,4,5,6-tetrahydrophthalimidomethyl (1RS, trans)-chrysanthemate], bile-duct cannulated animals were orally or intravenously administered 14C-labelled 3,4,5,6-tetrahydrophthalimide (TPI) or 3,4,5,6-tetrahydrophthalic acid (THPA), precursors of these metabolites, and bile, urine and faeces were collected for analysis. 2. 3-OH-HPI-1 and 3-OH-HPI-2, which are cis-form reduced metabolites, and 1-OH-HPA were detected in bile and urine samples of the bile-cannulated rat treated intravenously and orally with 14C-labelled TPI, indicating their formation in tissues or blood. TCDA, a trans-form reduced metabolite, was not detected in bile, urine or faeces of the bile-cannulated rat treated intravenously with 14C-THPA, but was found in the faeces after oral application, indicating formation in the gastrointestinal tract. 3. To clarify whether 1-OH-HPA is produced from THPA via TCDA (hydroxylation via reduction) or by direct addition of H2O to its double bond (hydration), rats were orally administered 14C-labelled TCDA, and metabolites in urine and faeces were analysed. The observed lack of 1-OH-HPA indicated formation by direct addition of H2O to the double-bond of THPA. 4. To specify which tissues form reduced and hydrated metabolites, in vitro metabolism studies were carried out. Reduction to the cis-form was found to take place in blood cells, reduction to the trans-form took place in the gastrointestinal tract contents, and hydration took place in the liver and the intestinal tract contents.     

Using analog baselines to assess the effects of naltrexone on self-injurious behavior

Healthy male and female human volunteers were exposed to 50 ppm or 100 ppm trichloroethylene (Tri) by inhalation for 4 h. Blood and urine samples were taken at various times before, during, and after the exposure period for analysis of glutathione (GSH), related thiols and disulfides, and GSH-derived metabolites of Tri. The GSH conjugate of Tri, S-(1,2-dichlorovinyl)glutathione (DCVG), was found in the blood of all subjects from 30 min after the start of the 4-h exposure to Tri to 1 to 8 h after the end of the exposure period, depending on the dose of Tri and the sex of the subject. Male subjects exposed to 100 ppm Tri exhibited a maximal content of DCVG in the blood at 2 h after the start of the exposure of 46.1 +/- 14.2 nmol/ml (n = 8), whereas female subjects exposed to 100 ppm Tri exhibited a maximal content of DCVG in the blood at 4 h after the start of the exposure of only 13.4 /- 6.6 nmol/ml (n = 8). Pharmacokinetic analysis of blood DCVG concentrations showed that the area under the curve value was 3.4-fold greater in males than in females, while the t1/2 values for systemic clearance of DCVG were similar in the two sexes. Analysis of the distribution of individual values indicated a possible sorting, irrespective of gender, into a high- and a low-activity population, which suggests the possibility of a polymorphism. The mercapturates N-acetyl-1,2-DCVC and N-acetyl-2,2-DCVC were only observed in the urine of 1 male subject exposed to 100 ppm Tri. Higher contents of glutamate were generally found in the blood of females, but no marked differences between sexes were observed in contents of cyst(e)ine or GSH or in GSH redox status in the blood. Urinary GSH output exhibited a diurnal variation with no apparent sex- or Tri exposure-dependent differences. These results provide direct, in vivo evidence of GSH conjugation of Tri in humans exposed to Tri and demonstrate markedly higher amounts of DCVG formation in males, suggesting that their potential risk to Tri-induced renal toxicity may be greater than that of females.     

Biological monitoring of cadmium exposure and renal effects in a population group residing in a polluted area in China

In an area of China, not previously studied in detail concerning cadmium pollution and possible adverse effects on the kidney of exposed populations, concentrations of cadmium in urine as an indicator of renal accumulation of cadmium was studied and related to indicators of renal dysfunction in order to examine if a relationship could be documented. Cadmium concentrations in urine were analysed by graphite furnace atomic absorption spectrometry and urinary beta-2 microglobulin (UBM) and albumin (UALB) were measured as indicators of renal dysfunction, Rice samples and urine samples were obtained from three areas in Zhejiang province, China, representing a highly exposed area, a medium exposed area and a control area, respectively. Cadmium concentrations in rice were 3.70, 0.51 and 0.072 mg/kg for the heavily, medium polluted areas and the control area, respectively. Cadmium concentrations in urine (geometric means) were 10.7, 1.62 and 0.40 micrograms/l in the high, medium and control areas respectively. There was a clear increase in UBM and UALB in the heavily exposed group in comparison to the control group and a slight increase in the medium exposed group. There was a statistically significant dose-response relationship between cadmium in urine and beta 2-microglobulin excretion in urine, which is similar to what has previously been reported in other countries. The findings constitute the first report concerning a dose-response relationship in this population group in Zhejiang province in China.     

Evidence of participation of the soluble tumor necrosis factor receptor I in the host response to intrauterine infection in preterm labor

PROBLEM: This study was conducted to determine whether: (1) the soluble tumor necrosis factor receptor I (sTNF-rI) is present in human amniotic fluid, neonatal urine, and the feto-maternal plasma; (2) there are changes in the concentration of the sTNF-rI in amniotic fluid with gestational age; and (3) microbial invasion of the amniotic cavity (in term and preterm parturition) is associated with changes in amniotic fluid sTNF-rI concentrations. METHOD: Amniotic fluid was retrieved by amniocentesis from 185 women classified into 11 groups according to gestational age (midtrimester, preterm gestation, and term), the presence or absence of labor, spontaneous rupture of membranes and microbial invasion of the amniotic cavity. sTNF-rI was assayed with a sensitive and enzyme-linked immunosorbent assay (ELISA) validated for amniotic fluid. In addition, sTNF-rI concentrations were determined in fetal blood obtained by cordocentesis in preterm gestations (N = 24) or at the time of delivery after spontaneous labor at term (N = 10). sTNF-rI concentrations were also measured in maternal venous and cord blood and neonatal urine (n = 13). RESULTS: sTNF-rI was found to be present in all amniotic fluid samples, maternal blood and fetal blood and neonatal urine samples; sTNF-rI concentrations were higher in the midtrimester than at term (mean +/- SD: 36.2 +/- 12.2 ng/ml versus mean +/- SD: 5.56 +/- 5.72 ng/ml [P < .05]); patients with preterm labor and microbial invasion of the amniotic cavity (with intact or with ruptured membranes) had significantly higher amniotic fluid concentrations of sTNF-rI than patients without microbial invasion; in the absence of microbial invasion, parturition (both term and preterm) was not associated with changes in amniotic fluid concentrations of sTNF-rI; neonatal urine contained the highest concentrations of sTNF-rI of all biological fluids assayed including maternal and neonatal/fetal blood and amniotic fluid. CONCLUSIONS: It was concluded that sTNF-rI is a physiologic constituent of amniotic fluid, as well as of the fetal and maternal plasma; that amniotic fluid sTNF-rI concentrations decrease as a function of gestional age and increases in the concentration of the sTNF-rI are part of the host response to intrauterine infection in preterm parturition.     

Quantitative urine cultures do not reliably detect renal candidiasis in rabbits

The significance of quantitative urine cultures in patients at risk for hematogenous disseminated candidiasis is controversial. While various concentrations of Candida spp. in urine have been suggested as critical cutoff points in the diagnosis of renal candidiasis, other investigators consider quantitative cultures less critical in diagnosing upper tract infections. To determine the significance of quantitative urine cultures in renal candidiasis, we studied serial quantitative urinary cultures of Candida albicans in a rabbit model of hematogenous infection. Of 197 urine samples from 34 infected animals, 144 were culture positive, with a sensitivity of 73.1% for urine cultures and a lower limit of detection of 10 CFU/ml. The yield of urine cultures varied according to severity and duration of infection. The mean renal and urinary concentrations of C. albicans from rabbits with subacute candidiasis differed significantly from those from rabbits with acute candidiasis (P = 0.013 and P < or = 0.001, respectively). During the first 4 days of subacute renal candidiasis, more than one-half of all urine cultures were negative for C. albicans. Only 12 (8.1%) of 148 urine cultures in animals with subacute renal candidiasis had concentrations of > 10(3) CFU/ml, 2.7% had concentrations of > 10(4) CFU/ml, and none were > or = 10(5) CFU/ml. By comparison, all urine cultures from the animals with lethal acute renal candidiasis had higher concentrations of C. albicans and were positive throughout the course of infection. Urinary concentrations of C. albicans were not predictive of the amount of Candida in the kidney (r < or = 0.49) and did not correlate with survival (r = 0.0232). However, the renal concentration of C. albicans (in CFU/gram) inversely correlated with the duration of survival (in days) of rabbits with renal candidiasis (r = 0.76; P < 0.001). These findings indicate that a negative urine culture in rabbits does not preclude the presence of renal candidiasis. The interpretation of a urine culture positive at any concentration, on the other hand, must involve an analysis of the risk factors for renal candidiasis, for any urinary concentration of C. albicans may reflect kidney infection.     

Lidocaine in the horse: its pharmacological effects and their relationship to analytical findings

Lidocaine is a local anaesthetic agent that is widely used in equine medicine. It is also an Association of Racing Commissioners International (ARCI) Class 2 foreign substance that may cause regulators to impose substantial penalties if residues are identified in post race urine samples. Therefore, an analytical/pharmacological database was developed for this drug. Using our abaxial sesamoid local anaesthetic model, the highest no-effect dose (HNED) for the local anaesthetic effect of lidocaine was determined to be 4 mg. Using enzyme-linked immunosorbent assay (ELISA) screening, administration of the HNED of lidocaine to eight horses yielded peak serum and urine concentrations of apparent lidocaine of 0.84 ng/mL at 30 min and 72.8 ng/mL at 60 min after injection, respectively. These concentrations of apparent lidocaine are readily detectable by routine ELISA screening tests (LIDOCAINE ELISA, Neogen, Lexington, KY). ELISA screening does not specifically identify lidocaine or its metabolites, which include 3-hydroxylidocaine, dimethylaniline, 4-hydroxydimethylaniline, monoethylglycinexylidine, 3-hydroxymonoethylglycinexylidine, and glycinexylidine. As 3-hydroxylidocaine is the major metabolite recovered from equine urine, it was synthesized, purified and characterized, and a quantitative mass spectrometric method was developed for 3-hydroxylidocaine as recovered from horse urine. Following subcutaneous (s.c.) injection of the HNED of lidocaine, the concentration of 3-hydroxylidocaine recovered from urine reached a peak of about 315 ng/mL at 1 h after administration. The mean pH of the 1 h post dosing urine samples was 7. 7, and there was no apparent effect of pH on the amount of 3-hydroxylidocaine recovered. Within the context of these experiments, the data suggests that recovery of less than 315 ng/mL of 3-hydroxylidocaine from a post race urine sample is unlikely to be associated with a recent local anaesthetic effect of lidocaine. Therefore these data may be of assistance to industry professionals in evaluating the significance of small concentrations of lidocaine or its metabolites in postrace urine samples. It should be noted that the quantitative data are based on analytical methods developed specifically for this study, and that methods used by other laboratories may yield different recoveries of urine 3-hydroxylidocaine.     

Hearing improvement after resection of cerebellopontine angle meningioma: case study of the preoperative role of transient evoked otoacoustic emissions

OBJECTIVE: The present study was initiated to investigate the validity of cadmium (Cd) and lead (Pb) in urine in comparison with the metals in blood as a biological marker of nonoccupational exposure of general populations to these metals as environmental pollutants. DESIGN: Peripheral blood samples, morning spot-urine samples, and 24-h total food duplicate samples were collected from 107 nonsmoking women (aged 30-59 years) in four urban and rural survey sites in Korea. METHODS: Portions of the samples were digested by heating in the presence of mineral acids, and the digests were analyzed for Cd and Pb by graphite furnace atomic absorption spectrophotometry. The metal concentrations in urine were adjusted for creatinine concentration and a specific gravity of 1.016. The analyte levels were evaluated on an individual basis (n = 107) and also on a group basis, i.e., in terms of geometric means for the survey sites (n = 4). RESULTS: Cd in urine correlated with Cd in blood on an individual as well as survey-site basis and tended to correlate with Cd in food duplicates on a group basis. The correlation of Pb in urine with Pb in blood was weaker than that of Cd in urine with Cd in blood when evaluated on an individual and survey-site basis. Pb in urine correlated with Pb in food duplicates either weakly or even negatively when examined on a survey-site basis. CONCLUSIONS: Cd in urine proved to be valid as a biological marker of environmental exposure of general populations, whereas less support was obtained for Pb in urine as an exposure marker.