A case of merbromin (Mercurochrome) intoxication possibly resulting in aplastic anemia

A patient is described who appeared to be suffering from mercury intoxication caused by local application of merbromin to an operation wound and who developed aplastic anemia, which we ascribed to merbromin.

Arsenic neurotoxicity--a review

Arsenic (As) is one of the oldest poisons known to men. Its applications throughout history are wide and varied: murder, make-up, paint and even as a pesticide. Chronic As toxicity is a global environmental health problem, affecting millions of people in the USA and Germany to Bangladesh and Taiwan. Worldwide, As is released into the environment by smelting of various metals, combustion of fossil fuels, as herbicides and fungicides in agricultural products. The drinking water in many countries, which is tapped from natural geological resources, is also contaminated as a result of the high level of As in groundwater. The environmental fate of As is contamination of surface and groundwater with a contaminant level higher than 10 particle per billion (ppb) as set by World Health Organization (WHO). Arsenic exists in both organic and inorganic species and either form can also exist in a trivalent or pentavalent oxidation state. Long-term health effects of exposure to these As metabolites are severe and highly variable: skin and lung cancer, neurological effects, hypertension and cardiovascular diseases. Neurological effects of As may develop within a few hours after ingestion, but usually are seen in 2-8 weeks after exposure. It is usually a symmetrical sensorimotor neuropathy, often resembling the Guillain-Barré syndrome. The predominant clinical features of neuropathy are paresthesias, numbness and pain, particularly in the soles of the feet. Electrophysiological studies performed on patients with As neuropathy have revealed a reduced nerve conduction velocity, typical of those seen in axonal degeneration. Most of the adverse effects of As, are caused by inactivated enzymes in the cellular energy pathway, whereby As reacts with the thiol groups of proteins and enzymes and inhibits their catalytic activity. Furthermore, As-induced neurotoxicity, like many other neurodegenerative diseases, causes changes in cytoskeletal protein composition and hyperphosphorylation. These changes may lead to disorganization of the cytoskeletal framework, which is a potential mechanism of As-induced neurotoxicity.

Mechanism of arsenic-induced neurotoxicity may be explained through cleavage of p35 to p25 by calpain

In recent studies we have demonstrated that arsenic (As) metabolites change the composition of neuronal cytoskeletal proteins in vivo and in vitro. To further examine the mechanism of arsenic-induced neurotoxicity with various arsenate metabolites (iAsV, MMAV and DMAV) and arsenite metabolites (iAsIII, MMAIII and DMAIII), we investigated the role of the proteolytic enzyme calpain and its involvement in the cleavage of p35 protein to p25, and also mRNA expression levels of calpain, cyclin-dependent kinase 5 (cdk5) and glycogen synthase kinase 3 beta (gsk3ss). A HeLa cell line transfected with a p35 construct (HeLa-p35) was used as a model, since all other proteins such as calpain, CDK5 and GSK3beta are already present in HeLa cells as they are in neuronal cells. HeLa-p35 cells were incubated with various As metabolites and concentrations of 0, 10 and 30 microM for duration of 4 h. Subsequently the cells were either lysed to study their relative quantification levels of these genes or to be examined on their p35-protein expression. P35-RNA expression levels were significantly (p<0.01) increased by arsenite metabolites, while p35 protein was cleaved to p25 (and p10) after incubation with these metabolites. The cleavage of p35 is caused by calcium (Ca2+) induced activation of calpain. Inhibition of calpain activity by calpeptin prevents cleavage of p35 to p25. These results suggest that cleavage of p35 to p25 by calpain, probably As-induced Ca2+-influx, may explain the mechanism by which arsenic induces its neurotoxic effects.

Arsenic metabolites affect expression of the neurofilament and tau genes: An in-vitro study into the mechanism of arsenic neurotoxicity

Neurological studies indicate that the central (CNS) and peripheral nervous system (PNS) may be affected by arsenic (As). As-exposed patients show significantly lower nerve conduction velocities (NCVs) in their peripheral nerves in comparison to healthy subjects. As may play a role in the disruption of neuroskeletal integrity, but the mechanisms by which it exerts a toxic effect on the peripheral and central nervous system are still unclear. In the present study, we examined the neurotoxic effects of various arsenic metabolites (iAs(III), iAs(V), MMA(V) and DMA(V)) on two different cell lines derived from the peripheral (ST-8814) and central (SK-N-SH) nervous system. The effects of the arsenic metabolites were examined on the relative quantification levels of the cytoskeletal genes, neurofilament-light (NEFL), neurofilament-medium (NEF3), neurofilament-heavy (NEFH) and microtubule-associated protein-tau (MAPT), using real-time PCR. Our results show that iAs(III) and iAs(V) have no significant effects on either cell lines. On the other hand, MMA(V) and DMA(V) cause significant changes in expression levels of NEF3 and NEFL genes, while the expression level of the NEFH gene is significantly increased in both cell lines.

Arsenic-induced toxicity: effect on protein composition in sciatic nerve

Exposure to arsenic compounds may lead to skin and lung cancer and various disorders such as vascular disease and peripheral neuropathy in humans. Peripheral arsenic neurotoxicity has been demonstrated clinically and in electrophysiological studies. Patients intoxicated with arsenic show neurological symptoms in their feet and hands. These patients show significantly lower nerve conduction velocities (NCVs) in their peripheral nerves in comparison with controls. The mechanism of arsenic peripheral nervous system (PNS) toxicity, however, has never been described before. This is the first study to investigate the toxicity of arsenic on the PNS. Male Wistar rats were exposed to arsenite given as a single dose i.v. After sacrifice, sciatic nerves were excised and the protein composition was analysed. Protein analysis of sciatic nerves showed disappearance of neurofilament and fibroblast proteins in rats treated with arsenite doses of 15 and 20 mg/kg in comparison with the control groups. Some fibroblast protein bands had disappeared in the 20-mg/kg dose group. The analysed neurofilament-M and -L proteins decreased dose dependency over time. arsenic affects the composition of proteins in the rat sciatic nerve, especially the neurofilaments. The reduction of signals in Western blot analysis reveals changes in cytoskeletal composition, which may well lead to neurotoxic effects in vivo.

Evaluation of a procedure to assess the adverse effects of illicit drugs

The assessment procedure of new synthetic illicit drugs that are not documented in the UN treaty on psychotropic drugs was evaluated using a modified Electre model. Drugs were evaluated by an expert panel via the open Delphi approach, where the written score was discussed on 16 items, covering medical, health, legal, and criminalistic issues of the drugs. After this face-to-face discussion the drugs were scored again. Taking the assessment of ketamine as an example, it appeared that each expert used its own scale to score, and that policymakers do not score deviant from experts trained in the medical-biological field. Of the five drugs evaluated by the panel, p-methoxy-metamphetamine (PMMA), gamma-hydroxybutyric acid (GHB), and 4-methylthio-amphetamine (MTA) were assessed as more adverse than ketamine and psilocine and psilocybine-containing mushrooms. Whereas some experts slightly adjusted during the assessment procedure their opinion on ketamine and PMMA, the opinion on mushrooms was not affected by the discussion held between the two scoring rounds. All experts rank the five drugs in a similar way on the adverse effect scale i.e., concordance scale of the Electre model, indicating unanimity in the expert panel with respect to the risk classification of these abused drugs.

Effects of dose, sex, and long-term abstention from use on toxic effects of MDMA (ecstasy) on brain serotonin neurons

BACKGROUND

3,4-methylenedioxymethamphetamine (MDMA or ecstasy) is a popular recreational drug that has been shown to damage brain serotonin neurons in high doses. However, effects of moderate MDMA use on serotonin neurons have not been studied, and sex differences and the long-term effects of MDMA use on serotonin neurons have not been identified. We investigated the effects of moderate and heavy MDMA use, sex differences, and long-term effects of MDMA use on serotonin neurons in different brain regions.

METHODS

By means of flyers posted in "rave" venues in Amsterdam, the Netherlands, we recruited 15 moderate MDMA users, 23 heavy MDMA users, 16 ex-MDMA users who had stopped using MDMA for more than 1 year, and 15 controls who claimed never to have used MDMA. We studied the effects of MDMA on brain serotonin neurons using 123iodine-2beta-carbomethoxy-3beta-(4-iodophenyl) tropane ([123I]beta-CIT)-a radioligand that binds with high affinity to serotonin transporters. Density of binding (expressed as a ratio of region-of-interest binding over binding in the cerebellum) was calculated by single-photon-emission computed tomography (SPECT).

FINDINGS

We saw significant effects of group and group by sex (p=0.041 and p=0.022, respectively) on overall [123I]beta-CIT binding ratios. In heavy MDMA users, significant decreases in overall binding ratios were seen in women (p<0.01) but not men (p=0.587). In female ex-MDMA users, overall densities of serotonin transporters were significantly higher than in heavy MDMA users (p=0.004), but not higher than in controls (p=0.524).

INTERPRETATION

Our results indicate that heavy use of MDMA is associated with neurotoxic effects on serotonin neurons, that women might be more susceptible than men, and that MDMA-induced neurotoxic changes in several brain regions of female ex-MDMA users are reversible.

Cortical serotonin transporter density and verbal memory in individuals who stopped using 3,4-methylenedioxymethamphetamine (MDMA or "ecstasy"): preliminary findings

BACKGROUND

Although the popular drug 3,4-methylenedioxymethamphetamine (MDMA or "ecstasy") has been shown to damage brain serotonin (5-HT) neurons in animals, the fate and functional consequences of 5-HT neurons after MDMA injury are not known in humans. We investigated the long-term effects of MDMA use on cortical 5-HT neurons in humans and memory function, because brain 5-HT has been implicated in memory function.

METHODS

Twenty-two recent MDMA users, 16 ex-MDMA users who had stopped using MDMA for more than 1 year, and 13 control subjects. The effects of MDMA use on cortical 5-HT neurons was studied by means of single-photon emission computed tomography with iodine 123-labeled 2beta-carbomethoxy-3beta-(4-iodophenyl) tropane ([(123)I]beta-CIT) by quantification of brain 5-HT transporter densities. Verbal memory performance was assessed with the Rey Auditory Verbal Learning Test.

RESULTS

Mean cortical [(123)I]beta-CIT-labeled 5-HT transporter density was significantly lower in recent MDMA users than in controls (1.17 vs. 1.28 [-9%]) but not in ex-MDMA users (1.24 vs. 1.28 [-3%]). Recent and ex-MDMA users recalled significantly fewer words than did controls on the immediate recall (47.0 and 48.0 vs 60.0, respectively; P =.001) as well as the delayed recall (9.8 and 10.1 vs. 13.1, respectively; P =.003). Greater use of MDMA was associated with greater impairment in immediate verbal memory. However, memory performance was not associated with [(123)I]beta-CIT binding to cortical 5-HT transporters or duration of abstinence from MDMA.

CONCLUSION

The present study suggests that, while the neurotoxic effects of MDMA on 5-HT neurons in the human cortex may be reversible, the effects of MDMA on memory function may be long-lasting.

Loss of homotypic epithelial cell adhesion by selective N-cadherin displacement in bismuth nephrotoxicity

The nephrotoxicity of single high doses of bismuth (Bi)-containing therapeutic drugs is characterized morphologically by detachment of proximal tubular epithelial cells (PTECs) from each other, followed by cell death. We investigated whether Bi nephrotoxicity is mediated by changes in the distribution of proteins involved in intercellular adhesion. A nephrotoxic dose of colloidal bismuth subcitrate (CBS; 3.0 mmol Bi/kg) was orally administrated to 10 female Wistar rats. After 1 h, N-cadherin had disappeared from the adherence junctions of vital PTECs, whereas ZO-1, a tight junction marker, remained present at the cell-cell border until cell death occurred after 3 h. E-Cadherin, absent in PTECs, remained absent. Exposure of the renal epithelial cell lines NRK-52E and LLC-PK1 to 400 microM Bi(3+) also resulted in the disappearance of N-cadherin expression after 1 h, whereas ZO-1, E-cadherin, and Desmoplakin expression did not resolve before cell death at 24 h, thus confirming in vivo results. Our results are the first to indicate that Bi-induced death of PTECs is preceded by redistribution of N-cadherin and the disruption of homotypic cell adhesion.

Stereochemical metabolism of styrene in volunteers

OBJECTIVES

To study the stereochemistry of styrene metabolism in volunteers, and its interindividual variability.

METHODS

Twenty healthy male volunteers (aged 18-37 years) were exposed to 360 mg/m3 styrene for 1 h while they performed 50 W physical exercise. Venous blood was drawn during and for up to 2 h after exposure. Urine was collected at time-intervals up to 24 h after exposure. The following parameters were determined: styrene, free and conjugated styrene glycol (SG) in blood, and conjugated SG, mandelic acid (MA) and phenylglyoxylic acid (PGA) in urine.

RESULTS

Average pulmonary retention of styrene was 62%. Excretion of the acidic metabolites MA and PGA accounted for 58% of the pulmonary uptake. The average maximum concentration (Cmax) and area under the curve (AUC) of free (R)-SG in blood were 1.3 and 1.7 times higher than those of (S)-SG respectively; the half-life of (R)-SG was longer (82 vs 62 min, P < 0.005). Cmax and AUC of the conjugated SG enantiomers in blood did not differ, but again half-life for (R)-SG was longer (72 vs 64 min, P < 0.05). Cumulative excretion and renal clearance of conjugated (S)-SG in urine were three and four times higher, respectively, than that of (R)-SG. Cumulative excretion of (S)-MA was 1.6 times higher than (R)-MA. Interindividual differences in the kinetic parameters of the metabolites were two- to threefold.

CONCLUSIONS

The enantiomeric excess found was different for each metabolite under study, implying different enantioselectivity and/or enantiospecificity of the enzymes and carrier-proteins involved in the biotransformation and excretion. The use of these metabolites as biological indicators for prediction of the enantiomeric excess of the toxic metabolite styrene-7,8-oxide (SO) is therefore not justified. Interindividual differences in the stereochemical metabolism of styrene are moderate.

Metabolic capacity and interindividual variation in toxicokinetics of styrene in volunteers

The aim of the present study was to assess the interindividual variation in styrene toxicokinetics and to correlate this variation with the individual metabolic capacity for cytochrome P450 (CYP), CYP2E1, CYP1A2 and CYP2D6. Twenty male volunteers were exposed on separate occasions to 104+/-3 and 360+/-20 mg/m3 of styrene for 1 h while performing 50 W physical exercise on a bicycle ergometer. Styrene concentrations in blood and mandelic (MA) and phenylglyoxylic acid (PGA) in urine were measured. The metabolic capacity was assessed by phenotyping with chlorzoxazone (CYP2E1), caffeine (CYP1A2), dextromethorphan (CYP2D6) and antipyrine (CYP450). In addition, for the main styrene-metabolising enzyme, CYP2E1, genotyping for the genetic polymorphisms of the gene was performed. The average pulmonary retention of styrene was 62 +/- 7% at both exposure concentrations, and the 24-h excretion of MA and PGA accounted for 58% of the dose at both concentrations. The interindividual variation in styrene kinetics ranged from 19% for the terminal half-life (t(1/2,beta)) of styrene to 41% for the cumulative excretion of MA and PGA. However, no correlation between the apparent blood clearance of styrene (CLapp), t(1/2,beta) of styrene or excretion of MA and PGA on one hand, and the individual metabolic capacity on the other hand was found. Although other explanations cannot be excluded, this lack of correlation might be due to the high apparent blood clearance (1.4 l/min) of styrene, indicating that styrene metabolism is liver-blood-flow-dependent.

Bismuth overdosing-induced reversible nephropathy in rats

Overdosing of colloidal bismuth subcitrate (CBS), used to treat peptic ulcers and Helicobacter pylori infections, has been reported to result in serious, though reversible, nephrotoxicity in humans. However, little is known about the nature of the renal damage induced by bismuth (Bi), and no well-described experimental model exists. Single large oral CBS doses (0.75, 1.5, and 3.0 mmol Bi/kg) were administered to three groups of 20 female Wistar rats. A control group (n = 20) received only the vehicle. Standard kidney function parameters, urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG) and the Bi content were monitored in blood, urine, liver, and kidneys for 14 days. A dose of 3.0 mmol Bi/kg, 100 times the daily therapeutic dose, caused kidney damage within 6 h as detected by proteinuria, glucosuria, and elevated plasma urea and plasma creatinine levels. The kidneys of all animals, except two that died, recovered functionally within 10 days. At a dose of 1.5 mmol Bi/kg, clinical parameters changed less and normalized within 48 h, whereas a dose of 0.75 mmol Bi/kg induced no changes. Histological evaluation revealed that the S3 tubular segment necrotized first with additional necrotization of the S1/S2 segment when more Bi was absorbed. The lesions were accompanied by interstitial infiltrates of CD45+ leukocytes. In summary, we developed a rat model for Bi-induced reversible nephropathy. A large single oral overdose of CBS administered to Wistar rats led to damage to the proximal tubule, especially in the last segment.

Effects of 2,5-hexanedione on calpain-mediated degradation of human neurofilaments in vitro

2,5-Hexanedione (2,5-HD), the neurotoxic metabolite of n-hexane, can structurally modify neurofilaments (NF) by pyrrole adduct formation and subsequent covalent cross-linking. 2,5-HD also induces accumulations of NF within the pre-terminal axon. We examined whether exposure of NF to 2,5-HD affected NF degradation. Two different models were used: (1) NF-enriched cytoskeletons isolated from human sciatic nerve were incubated with 2,5-HD in vitro and (2) differentiated human neuroblastoma cells (SK-N-SH) were exposed to 2, 5-HD in culture prior to isolation of cytoskeletal proteins. The cytoskeletal preparations were subsequently incubated with calpain II. The amount of NF-H and NF-L remaining after proteolysis was determined by SDS-PAGE and quantitative immunoblotting. NF-M proteolysis could not be quantified. Incubation of sciatic nerve cytoskeletal preparations with 2,5-HD resulted in cross-linking of all three NF proteins into high molecular weight (HMW) material with a range of molecular weights. Proteolysis of the NF-H and NF-L polypeptides was not affected by 2,5-HD-exposure. Degradation of the HMW material containing NF-H or NF-L was retarded when comparing with degradation of the NF-H and NF-L polypeptides, respectively, from control samples, but not as compared to the corresponding NF polypeptides from 2,5-HD-treated samples. Exposure of SK-N-SH cells to 2,5-HD also resulted in considerable cross-linking of NF. No differences were found between the proteolytic rates of NF-L and NF-H from exposed cells as compared with those subunits from control cells. Moreover, degradation of cross-linked NF-H was not different from monomeric NF-H. In conclusion, whether 2,5-HD affects calpain-mediated degradation of cross-linked NF proteins will depend on which model better reflects NF cross-linking as occurring in 2, 5-HD-induced axonopathy. However, with both models it was demonstrated that exposure of NF proteins to 2,5-HD without subsequent cross-linking is not adequate to inhibit NF proteolysis in vitro by added calpain.

Gas chromatography-electron capture determination of styrene-7,8-oxide enantiomers

The enantiomers of styrene-7,8-oxide (phenyloxirane, SO) were determined using a method based on base catalysed hydrolysis with sodium methoxide. The oxirane ring opening resulted in formation, without racemisation, of the enantiomeric pairs of the two regional isomers, 2-methoxy-1-phenylethanol and 2-methoxy-2-phenylethanol. The structure of these regional isomers was confirmed by gas chromatography-mass spectrometry (GC-MS) and proton nuclear magnetic resonance (1H-NMR). To improve sensitivity of determination, the formed methoxy alcohols were subsequently derivatised with pentafluoropropionic anhydride enabling electron capture detection. This derivatization proceeded also without racemisation and the formed pentafluoropropionyl derivatives were separated on two serially coupled columns, a non-chiral AT 1705 and a chiral CP Chirasil-Dex-CB. As internal standard 2S,3S-(-)-2-methyl-3-phenyloxirane was used. The limit of quantitation of the method was 0.2 microM. The repeatability of the method was assessed at two concentration levels (2.5 and 25 microM) and ranged from 6 to 9% for both enantiomers. The method was applied to the determination of the rate and enantioselectivity of the cytochrome P-450 dependent oxidation of styrene to SO enantiomers in human liver microsomes.

Metabolism of styrene-7,8-oxide in human liver in vitro: interindividual variation and stereochemistry

Styrene is an industrial solvent which is mainly oxidized by cytochrome P450 to an electrophilic, chiral epoxide metabolite: styrene-7,8-oxide (SO). SO has cytotoxic and genotoxic properties; the (R)-enantiomer is more mutagenic to Salmonella typhimurium TA 100 in the Ames test than the (S)-enantiomer. Detoxication proceeds via microsomal epoxide hydrolase (mEH). Interindividual differences in mEH activity as well as differences in mEH enantioselectivity are important factors for toxic effects of SO. To study the extent of the interindividual variation, microsomal preparations of 20 human livers were incubated with (R)- and (S)-SO separately (1-2000 microM) and Michaelis-Menten kinetics were determined. In addition, samples were genotyped for two genetic polymorphisms of the mEH gene. V(max), K(m) and V(max)/K(m) values of both enantiomers differed three- to fivefold between the livers. No association of the enzyme constants with the genetic polymorphisms of the epoxide hydrolase gene was found. Hydrolysis of the styrene oxide enantiomers proceeded in an enantioselective manner, with the (S)-enantiomer having an approximately six times higher K(m) and five times higher V(max) than the (R)-enantiomer. In vivo, both SO enantiomers are formed; therefore, time course incubations with racemic SO were carried out in vitro to investigate possible interactions between the enantiomers. When racemic SO was used as a substrate, the (R)-enantiomer acted as an inhibitor on the hydrolysis of the (S)-enantiomer. These results indicate that mEH-mediated hydrolysis of SO is subject to appreciable interindividual variation and that hydrolysis of the more toxic enantiomer is favored.

Bismuth biokinetics and kidney histopathology after bismuth overdose in rats

Bismuth induced nephrotoxicity has been reported to occur after acute overdoses of Bi-containing therapeutic drugs. We studied the development of bismuth induced nephropathy and bismuth biokinetics in rats. Bismuth nephropathy was induced in 33 young adult female Wistar rats weighing ca. 175 g by feeding them a single overdose of colloidal bismuth subcitrate containing 3.0 mmol Bi/kg at (t = 0). Control animals (n = 7) were fed the vehicle only. The animals were sacrificed after 1-48 h. Plasma creatinine increased from 51 +/- 6 micromol/l at t = 0 to 550 +/- 250 micromol/l after 48 h in the experimental group. The S3 segment of the proximal tubule showed epithelial cell vacuolation after 1 h and necrosis after 3 h. Cells of the S1/S2 segment demonstrated vacuolation after 6 h and necrosis after 12 h. Biokinetics of bismuth in blood could best be described with a one-compartment model characterized by an absorption half-life of 0.32 h and an elimination halflife of 16 h. The peak concentration of about 7.0 mg Bi/l was reached after 2 h. In conclusion, cells of the S3 segment of the proximal tubule necrotized first after an oral colloidal bismuth subcitrate overdose and biokinetics of Bi in blood was best described by a one-compartment model.

Craving patterns in methadone maintenance treatment with dextromoramide as adjuvant

A study was performed to establish the effect on opiate craving among six long-term opiate-dependent subjects in methadone maintenance treatment. Subjects currently stabilised on methadone, received 5 or 10 mg dextromoramide besides methadone. During the study the usual methadone dose was diminished according to the individual subject's expectation of the effect of dextromoramide addition. A clear drug-effect relationship between the increment of dextromoramide plasma concentration and decrement of opiate craving could be seen. A craving increase before drug administration was seen in three cases. The results could imply beneficial effects of a short-acting opiate on diminishing craving in opiate addicts who are difficult to stabilise with methadone maintenance treatment.

Fluoride enhances the effect of aluminium chloride on interconnections between aggregates of hippocampal neurons

The role of fluoride in aluminium neurotoxicity was studied using an in vitro system of cultured hippocampal neurons from foetal rats. Sodium fluoride (50 microM) and aluminium chloride (12.5 microM) were administered alone or in a specific combination (50 + 12.5 microM) in a 14-day culture in a chemically defined medium before staining of neurofilaments. Neuronal aggregates interconnected by neuritic fibers were detected light microscopically in control cultures. The aggregates and the fibers stained positive for neurofilament proteins. In cultures treated with aluminium chloride the development of the interconnecting fibers was affected, resulting in a fusion pattern of the aggregates. This phenomenon was enhanced when sodium fluoride was given together with aluminum chloride. It was concluded that aluminium interferes with the metabolism of the neuronal cytoskeleton and that this interference is potentiated by fluoride.

[Clinical and toxicologic aspects of the use of Ecstasy]

Methylenedioxymethamphetamine (MDMA, the active compound of ecstacy (XTC) tablets) is a psychoactive amphetamine congener which in humans has a stimulatory effect and enhances feelings of openness and solidarity. MDMA is neurotoxic in animals. It depletes axonal serotonin stores, it inhibits serotonin synthesis by inhibiting tryptophan hydroxylase, and it inhibits the reuptake of serotonin into the neuron. These events lead to destruction of serotonergic axon terminals in animal brain. Selective serotonin reuptake inhibitors protect against the neurotoxic effects of MDMA. Binding of (+)[11C]McN-5652, a selective neuroligand for the serotonin transporter, is decreased in the brains of XTC-users. This indicates that XTC damages serotonergic axon terminals in human brain, also. We strongly advise against the use of XTC as the long-term clinical consequences are not known. In man, somatic life-threatening complications after XTC use include hyperthermia, hyponatraemia and liver failure. Psychiatric complications include psychosis, depression, panic disorder, and impulsive behaviour. The chronic psychosis responds poorly to therapy.

Mercury exposure of maroon workers in the small scale gold mining in Suriname

Suriname is experiencing a revival of small scale gold mining activities, with about 10,000 to 15,000 workers involved in 1996. The estimated production in 1995 is at least 10,000 kg crude gold. Gold is extracted with mercury and methods used are comparable with those described for gold mining in the Amazon Basin. Since no data exist on the internal mercury exposure of workers in Suriname a study was performed. A group of mercury-exposed Maroons, who are principally involved in the mining located in the tropical rainforest, is compared with nonexposed Maroons living in a non-gold mining area. Blood and urine samples of both groups were analyzed for total mercury using an atomic absorption spectrometer with an FIAS hydride system. In the study 28 exposed and 17 controls with a comparable mean age (P=0.544; exposed 27+/-7.2 years, n=26; controls 26+/-7.7 years, n=17), all males, participated. The urine levels for both groups differ statistically significantly from each other (P<0.001; exposed mean 27.5+/-21.1 microg/g creatinine; controls mean 5. 2+/-2.9 microg/g creatinine). This is, however, not the case with the blood levels (P=0.036: exposed mean 18.1+/-11.0 microg/L, n=25; controls mean 26.8+/-14.6 microg/L, n=16). In contrast with blood the urine total mercury levels in this study confirm, on a group basis, exposure to mercury as described for individuals working in the gold mining in the Amazon Basin.

Intestinal absorption of aluminum: effect of sodium and calcium

Aluminum (Al) is recognized as a toxin in patients with deficient renal function. Moreover, Al may play a role in some neurodegenerative diseases. It is hypothesized that more than one intestinal absorption mechanism exists for Al, related to various intraluminal chemical species, and that Al shares intestinal transport routes for essential inorganic substances due to similarities in their chemical speciation characteristics. The purpose of the present investigation was to study the effects of ionic Na (0-120 mmol/l) and Ca (0-10 mmol/l), alone and in combination, on the intestinal absorption of ionic Al (20 and 30 mmol/l). A previously standardized method of perfusion of rat small intestine was used, combined with serial blood sampling. Mucosal uptake and systemic appearance of Al in the blood were monitored during 1 h perfusion, together with Na and Ca; the metals were given as the chloride. The intestinal absorption of Na and Ca was taking place according to previously reported mechanisms. A one-sided negative interaction was shown to exist between Ca and Al resp. Al and Na during both mucosal uptake and systemic appearance; Ca interacts negatively with Na during systemic appearance, but enhances mucosal uptake of Na. It may be speculated that Al mimicks Ca in its Na-dependent intestinal passage.

Serum aluminium levels of workers in the bauxite mines

BACKGROUND/OBJECTIVE

Aluminium is produced from the mineral bauxite. Occupational exposure is reported during the industrial processing of aluminium and is associated with pulmonary and neurotoxicity. However, data on exposure and toxicity of workers in the open bauxite mining industry do not exist. Therefore, a study was performed to explore aluminium exposure in employees involved in this bauxite mining process in a Surinam mine.

METHODS/DESIGN

A group of workers occupationally exposed to aluminium in an open bauxite mine were compared with a group of nonexposed wood processors. Serum aluminium was analyzed using atomic absorption spectrometry Data from the clinical chemistry of the blood and a questionnaire were used to explore determinants for aluminium exposure.

RESULTS

No significant difference between serum aluminium in the exposed (4.4 +/- 2.0 micrograms/L, n = 27) and control group (5.1 +/- 1.5 micrograms/L, n = 27) was detected. For the serum concentration of the clinical chemical variables (calcium, citrate, and creatinine), a statistically significant difference was computed (p < or = 0.02) between the exposed and control group. All levels were slightly higher in the exposed group; no statistically significant correlations with serum aluminium were found.

CONCLUSIONS

In this study, serum aluminium values were in the normal range, no significant difference between the groups could be detected despite long-term occupational exposure.

[Relation between mercury and Alzheimer's disease?]

Mercury from dental silver amalgam has been suggested to be linked with Alzheimer's disease. The percentage in the population (formerly) possessing amalgam restorations exceeds that of Alzheimer patients. Therefore, low levels of mercury in the brain are unlikely to cause the disease. However, studies indicating increased levels of mercury in Alzheimer brains compared to controls have been criticised. In contrast, it has been proven that an inherited trait accounts for a minor proportion of Alzheimer's patients. Moreover, education--or related psychosocial factors--instead of amalgam has been found to be associated with the disease. Therefore, it does not seem warranted as yet to conclude that mercury is an etiological factor in Alzheimer's disease.

Dermal absorption of vaporous and liquid 2-methoxyethanol and 2-ethoxyethanol in volunteers

OBJECTIVES

To estimate dermal absorption of vaporous and liquid 2-methoxyethanol (ME) and 2-ethoxyethanol (EE) in volunteers.

METHODS

Five volunteers (two men and three women) were dermally exposed to vaporised and liquid ME and EE. Dermal exposure on an area of about 1000 cm2 (forearm and hand) to vapours of ME and EE (4000 mg/m3 ME and 3700 mg/m3 EE) lasted for 45 minutes. Duration of exposure to liquid ME and EE on an area of 27 cm2 (forearm) was 15 minutes. Dermal uptake was assessed by measurement of the main metabolites in urinary methoxyacetic acid (MAA) and ethoxyacetic acid (EAA). For each volunteer, excretion of metabolites was compared with a reference inhalatory exposure.

RESULTS

Mean (SD) absorption rates of ME and EE vapour were 36 (11) and 19 (6) cm/h respectively. The mean (SD) absorption rates of the liquid ME and EE amounted to 2.9 (2.0) and 0.7 (0.3) mg/cm2.h.

CONCLUSIONS

Vaporised and liquid ME and EE are readily absorbed through the skin. In the combined inhalatory and dermal exposure when whole body surface is exposed to vapour, the uptake through the skin is estimated to be 55% of the total uptake of ME and 42% of EE. Dermal uptake resulting from skin contact of both hands and forearms (about 2000 cm2) with liquid ME and EE for 60 minutes would exceed inhalatory uptake of the eight hour occupational exposure limit by 100 times at 16 mg/m3 of ME and 20 times at 19 mg/m3 of EE. The substantial skin uptake of ME and EE indicates that in assessing the health risks biological monitoring and use of biological exposure indices are preferable to environmental monitoring.

Dermal absorption of cis-1,3-dichloropropene vapour: human experimental exposure

1. The relevance of skin absorption of cis-1,3-dichloropropene (cis-1,3-DCP) vapour as a route of entry compared to inhalatory uptake has been assessed in human volunteers under controlled exposure conditions. 2. Five adults (four males and one female) were dermally exposed on the forearm and hand during 45 min to 86 mg/m3 cis-1,3-DCP. 3. Dermal uptake was assessed by determination of the main cis-1,3-DCP metabolite in urine: the mercapturic acid conjugate of cis-1,3-DCP (cis-1,3-DCP-MA). 4. When whole-body dermal exposure to vapour is compared to inhalatory exposure, the uptake through the skin is estimated to be about 2-5% of the inhalatory absorption.

A method for the simultaneous identification and quantitation of five superwarfarin rodenticides in human serum

A high-performance liquid chromatographic method with ultraviolet (UV) and fluorescence detection was developed for the analysis of one indandione and four hydroxycoumarin anticoagulant rodenticides in human serum. The superwarfarin rodenticides, chlorophacinone, bromadiolone, difenacoum, brodifacoum, and difethialone, can be identified and quantitated simultaneously with this method. After adding a buffer (pH 5.5), the anticoagulants were extracted from serum with chloroform-acetone. The organic phase was separated and evaporated to dryness, and the residue was subjected to chromatographic analysis. The anticoagulants were separated by reversed-phase chromatography and detected by UV absorption at 285 nm and by fluorescence at an excitation wavelength of 265 nm and an emission wavelength of 400 nm. Extraction efficiencies from 55 to 131% were obtained. The within-run precision ranged from 2.0 to 7.1% for UV detection and from 0.0 to 4.8% for fluorescence detection. Between-run precision ranged from 1.3 to 16.0% for UV detection and from 1.8 to 9.0% for fluorescence detection. The anticoagulants can be quantitated at serum concentrations down to 3-12 ng/mL for fluorescence detection and down to 20-75 ng/mL for UV detection. No interferences were observed with the related compounds warfarin and vitamin K1.

Determination of 2,5-hexanedione, a metabolite of n-hexane, in urine: evaluation and application of three analytical methods

Three methods for the determination of 2,5-hexanedione (2,5-HD) in urine were compared in order to assess their applicability for toxicokinetic studies and biological monitoring of occupational exposure to n-hexane. Two of them were based on derivatization, followed by gas chromatography and electron-capture detection. Of these two, one is a modification of the other, already published, method. The third one involves direct extraction of 2,5-HD followed by gas chromatography and flame-ionization detection. To determine 2,5-HD in urine of workers occupationally exposed to n-hexane, the most straightforward method, direct extraction of 2,5-HD from urine, has been proven to be the most suitable. However, in case of very low concentrations of 2,5-HD in urine, or analysis of small samples of blood, e.g. in kinetic studies, it is necessary to use a more sensitive procedure. The sensitivity of the methods based on the derivatization of 2,5-HD followed by electron-capture detection, was, as expected, much higher in terms of analytical reliability. By using these methods, however, precautions are necessary to avoid a matrix effect.

Absorption of bismuth from several bismuth compounds during in vivo perfusion of rat small intestine

Evaluation of the amount of bismuth (Bi) absorbed from the gastrointestinal tract is important for assessment of the possible risks associated with the use of Bi compounds in the treatment of gastrointestinal disorders. We compared the absorption of Bi from media containing the equivalent of 1 g of elemental Bi from either Bi subnitrate (BSN), Bi subsalicylate (BSS), colloidal Bi subcitrate (CBS), Bi chloride (BiCl3), or Bi citrate (BCit) by an in vivo perfusion system of rat small intestine. The intestinal absorption was < 1% for all compounds, but higher from BCit and CBS than from BSN, BSS, and BiCl3. The dose dependency of Bi absorption from both CBS and BiCl3 in citrate buffer showed a nonlinear relationship between the concentration of Bi in perfusate and the concentration of Bi in blood after 60 min.

Sensitivity to 2,5-hexanedione of neurofilaments in neuroblastoma cell line SK-N-SH increases during differentiation

The effect of 2,5-hexanedione (2,5-HD) on the distribution of the neurofilamental (NF) proteins and vimentin was examined in human neuroblastoma cell line SK-N-SH with immunocytochemical methods. Retinoic acid (10 microM) induced differentiation into neuronal cells resulting in the outgrowth of processes and synthesis of NF proteins in the majority of the cells. A minority (4%) differentiated as large fibroblasts. Cells were exposed to 0-10 mM 2,5-HD for 3 days. In neuronal cells a concentration-dependent accumulation of NF proteins was detected as a spherical structure in the perikaryon. Neurofilaments in differentiated SK-N-SH cells were more susceptible to 2,5-HD than NF in undifferentiated cells, as the effects were observed at much lower 2,5-HD concentrations. In contrast, no accumulation of vimentin was detected in the fibroblastic cells.

Phenytoin parahydroxylation is not impaired in patients with young-onset Parkinson's disease

Impaired hepatic detoxification capacity by cytochrome P450 subsystems has been implicated in the pathogenesis of Parkinson's disease. We have demonstrated that hepatic parahydroxylation of phenytoin (PHT) is impaired in patients with late-onset Parkinson's disease. In the present study, we have investigated the hypothesis that PHT parahydroxylation is even more impaired in patients with young-onset Parkinson's disease (age at onset before 40 years). We determined PHT parahydroxylation capacity in 21 patients with young-onset Parkinson's disease and 15 healthy age-matched controls. PHT parahydroxylation capacity was assessed by measuring the ratio of PHT to its major metabolite p-hydroxyphenyl-phenylhydantoin in serum 6 h after an oral test dose of 300 mg PHT. PHT parahydroxylation did not differ significantly between patients and controls. These results argue against the hypothesis that impaired activity of the cytochrome P450 isoenzyme responsible for PHT parahydroxylation is involved in the etiology of Parkinson's disease.

Giant axonal degeneration: scanning electron microscopic and biochemical study of scalp hair

Tightly curled 'frizzy' hair is a pathognomonic sign of giant axonal degeneration (GAD). The present study compares the morphological structure of the scalp hair of a GAD patient with that of her parents and first-degree relatives with the aid of scanning electron microscopy. The comparison included plaited hair of two age-matched controls, in order to exclude mechanical plaiting artifacts. Trichorrhexis nodosa and fringing of the cut ends were exclusively found in the patient's hair. Longitudinal grooving was also frequently seen in hair of normal persons. Assay of carbon (C), sulfur (S) and nitrogen (N) contents of the patient's hair was normal, but the S:N ratio was significantly reduced, as compared with her relatives. However, comparison with a control group of non-related healthy volunteers showed no difference.

Dermatitis in bulb growers

A damaged skin forms a health hazard in flower-bulb growers as it enables higher permeation rates for pesticides than normal skin. Therefore, an investigation was performed into the skin condition of 103 bulb growers and 49 controls. Contact dermatitis of the hands was of the same order (11 and 10%) in both groups. However, minor signs of dermatitis were seen more often in bulb growers (30 versus 8%, p < 0.05). Most growers had contact with narcissus sap during the investigation. This irritant sap, as well as many other skin contacts with irritants such as hyacinth dust and pesticides, seemed to be responsible for many skin complaints. Contact sensitization was suspected in 19 growers and 3 controls. Patch tests showed that contact sensitization existed to pesticides in probably 10, and to flower-bulb extracts in 4 growers. Reactions to propachlor were not regarded as very reliable as the test concentration seemed to be marginally irritant. There were only a few allergic reactions to narcissus (3) and tulip (2) and none to hyacinth. This investigation showed that minor irritant contact dermatitis was frequent in bulb growers, and indicated that contact sensitization to pesticides and bulbs seemed to be a less frequent but important cause of dermatitis.

Analysis for bismuth in tissue by electrothermal atomic absorption spectrometry

We developed a simple method for the analysis of bismuth (Bi) in biological tissue, using wet digestion for sample pretreatment. Bi was determined by electrothermal atomic absorption spectrometry with platinum as a matrix modifier to decrease the volatility of Bi. The furnace program included a gas stop for sensitivity enhancement. Analytical performance was established for Bi in kidney, liver, brain, and bone. As little as 25 ng/g wet weight can be detected in the most concentrated digests. Homogenization of bone was necessary before digestion, and its matrix showed the strongest interference. In rats exposed orally to colloidal bismuth subcitrate for 14 days, the metal could be detected in liver, kidney, and spleen but not in brain and bone. In the tissues of 12 patients who died from non-Bi-related causes, no Bi were present in kidney in the other 2.

Analysis for bismuth in tissue by electrothermal atomic absorption spectrometry

We developed a simple method for the analysis of bismuth (Bi) in biological tissue, using wet digestion for sample pretreatment. Bi was determined by electrothermal atomic absorption spectrometry with platinum as a matrix modifier to decrease the volatility of Bi. The furnace program included a gas stop for sensitivity enhancement. Analytical performance was established for Bi in kidney, liver, brain, and bone. As little as 25 ng/g wet weight can be detected in the most concentrated digests. Homogenization of bone was necessary before digestion, and its matrix showed the strongest interference. In rats exposed orally to colloidal bismuth subcitrate for 14 days, the metal could be detected in liver, kidney, and spleen but not in brain and bone. In the tissues of 12 patients who died from non-Bi-related causes, no Bi were present in kidney in the other 2.

Effect of citric acid and maltol on the accumulation of aluminum in rat brain and bone

Deposition of aluminum in the body is responsible for the development of dialysis-related diseases in patients with renal dysfunction and may play a role in the development of certain neurodegenerative disorders. Although citric acid is known to be a strong enhancer of gastrointestinal absorption of aluminum, its effect on aluminum distribution and accumulation is not yet clear. Maltol has been shown to increase the neurotoxicity of aluminum, but little is known about its effect on aluminum deposition in the body. To elucidate the role of citric acid and maltol in aluminum accumulation and toxicity, rats were loaded intraperitoneally during a 7-day period with different amounts of aluminum chloride in absence or presence of citric acid or maltol before analysis of aluminum in serum, brain, bone, and urine. Coadministration of citric acid led to relatively reduced serum levels, as compared with aluminum and aluminum-maltol treatment. This is explained by both tissue elimination and enhanced renal elimination. Only at the highest aluminum dose (8 mg/kg body weight) was an enhancing effect of citric acid on accumulation of aluminum in brain observed; no effect on bone aluminum was seen. Furthermore, it was seen that citric acid alters the distribution pattern of aluminum. This may be explained by the postulation of a characteristic aluminum citrate species in serum. Administration of citric acid may increase this aluminum fraction in serum, thereby inducing an alteration of the distribution pattern. Maltol was shown to be a strong enhancer of aluminum accumulation in serum, brain, and bone. The rise of aluminum in these target tissues was dose dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of biological monitoring parameters for occupational exposure to toluene

A survey was conducted in a rotogravure printing plant with inhalatory and percutaneous exposure to toluene. Workers (n = 9) were followed for 2 consecutive days and the frequency and duration of skin contact with toluene were monitored. In order to assess percutaneous absorption an airstream helmet was worn during one day. Urine and exhaled air samples were collected simultaneously 5 times each day for toluene (urine and breath) and hippuric acid (urine). The mean (personal air sampling) exposure concentration was between 30 mg/m3 and 600 mg/m3. The best biological monitoring parameter of external exposure (without a helmet) was the concentration toluene in exhaled air 8 h after work (r = 0.99). While wearing the airstream helmet the relationship between external exposure (measured in the helmet) and concentrations in exhaled air and urine deviated from the preceding relations. This was likely the result of the high body burden and not of skin contact with toluene. Skin contact with toluene (usually by cleaning of the hands) was limited to 0-30 minutes a day, with an average of about 5 minutes. During experimental exposure (n = 6) in which the hands were washed with toluene for 5 minutes the toluene in exhaled air (max after 1040 min) clearly demonstrated skin absorption of toluene. The next morning 0.1 mg/m3 toluene was still detectable; this was less than the concentration measured the next morning in exhaled air of workers: between 0.5 and 10 mg/m3.

Increased neurotoxicity of arsenic in methylenetetrahydrofolate reductase deficiency

A 16-year-old girl from Surinam presented with mental deterioration and severe paraparesis with areflexia and bilateral Babinski signs. Laboratory examination showed a hyperhomocysteinemia that was caused by 5,10-methylene-tetrahydrofolate reductase (MTHFR) deficiency. In addition, urine samples contained large amounts of arsenic. An open bag with the pesticide copper acetate arsenite was found to be the source of exposure. In remethylation defects such as MTHFR deficiency, the concentration of methyldonors is severely reduced. As arsenic is detoxified by methylation, we suggest that the MTHFR deficiency in this girl might explain the fact that of all family members exposed to arsenic, only she developed severe clinical signs and symptoms of arsenic poisoning.

Increased metallothionein in the liver and kidney of patients with amyotrophic lateral sclerosis

To evaluate the putative role of metals and trace elements in the pathogenesis of classic amyotrophic lateral sclerosis, we studied the metallothionein levels in liver and kidney samples obtained at autopsy from 24 patients with amyotrophic lateral sclerosis and 18 controls. To assay metallothioneins and copper, cadmium, and zinc bound to metallothioneins, we used high-performance liquid chromatography directly coupled to flame atomic absorption spectrometry. Total cadmium, zinc, and copper concentrations were determined separately with the use of graphite furnace atomic absorption spectrometry with Zeeman background correction. The median liver metallothionein level was 60.3 mg/kg (range, 9 to 318 mg/kg) in the patients with amyotrophic lateral sclerosis and 12.6 mg/kg (range, 0 to 104.5 mg/kg) in the controls. In the kidney, median metallothionein levels were 126.9 mg/kg (range, 44 to 387 mg/kg) in the patients with amyotrophic lateral sclerosis and 64 mg/kg (range, 13.1 to 187 mg/kg) in the controls. Total zinc, cadmium, and copper concentrations, as measured by atomic absorption spectrometry, were not significantly different in patients vs controls. Our finding of elevated metallothionein levels in organs from patients with amyotrophic lateral sclerosis may indicate an increased exposure to metals.

Development of a therapeutic procedure for bismuth intoxication with chelating agents

Although bismuth poisoning is still a rare phenomenon, the increasing use of bismuth-containing drugs warrants a systematic approach to the treatment of bismuth overdose. An effective method of enhancing the elimination of toxic amounts of bismuth from the body has not been reported. Therefore we performed a study to select the best chelator to treat bismuth poisoning. Dimercaprol (BAL), meso-2,3-dimercaptosuccinic acid (DMSA), D,L-2,3-dimercapto-propane-I-sulfonic acid (DMPS), D-penicillamine (D-PEN), N-acetyl-D,L-penicillamine (Ac-PEN), thiopronine (TP), sodium-calcium edetate (EDTA) and deferoxamine (DFO) were tested with an in vitro model of equilibrium dialysis and an in vivo model of rats poisoned with bismuth. The rats (n = 6 per substance tested) were treated with the chelators in intraperitoneal doses of 250 mumol/kg.day for 3 consecutive days. Afterward, tissue and blood samples were collected. Bismuth concentrations were determined with electrothermal atomic absorption spectrometry in serum, buffer, urine, blood, brain, kidney, liver, spleen, and bone. Using in vitro results, we constructed a ranking of chelating agents; it appeared not to predict the in vivo results. The dithiol compounds (DMPS, DMSA and BAL) were effective in most organs (especially in kidney and liver) resulting in a higher elimination of bismuth in urine by DMPS and BAL. BAL was the only chelator effective in lowering brain bismuth concentrations, whereas treatment with EDTA resulted in increased brain bismuth levels. For D-PEN and DFO, no effects could be demonstrated. For clinical practice, DMSA and DMPS may well be the chelators of choice; the application of BAL should be reserved for very severe cases of poisoning because of its own toxicity.

Accumulation of aluminium in rat liver: association with constituents of the cytosol

Aluminium (Al) accumulation occurs in the liver of renal patients and in patients on parenteral nutrition. Human hepatotoxicity is not proven. The role of the liver in storage and biotransformation of Al and in development of osteo- and neurotoxicity is not clarified as yet. The aim of the present investigation was to study the storage of Al in total liver and in subcellular liver fractions, and its association with soluble cytosolic molecular species. Therefore, rats were loaded with Al prior to liver fractionation by ultracentrifugation, and equilibrium gel filtration chromatography of the cytosol, using a previously described method for Al speciation in serum. Al accumulated dose-dependently in liver and subcellular liver fractions, the lowest levels occurring in the cytosol. A dose-dependent elevation of Al in the blood was also observed. Gelfiltration of the cytosol indicated that Al was associated with a low molecular weight form which was not a citrate complex, and a high molecular weight form, which was larger than transferrin. No induction of and association with metallothionein occurred.

Analysis of bismuth in serum and blood by electrothermal atomic absorption spectrometry using platinum as matrix modifier

Bismuth-containing medicines have been used for years, but there is a lack of clinically applicable methods for measuring bismuth in body fluids. We describe a sensitive, accurate and precise method for analysis of bismuth in blood and serum, which is suitable both for monitoring purposes and for further investigations into the biokinetics and safety of bismuth. Bismuth was quantitated with electrothermal atomic absorption spectrometry with Zeeman background correction. In the furnace programme a cool-down step was introduced and platinum was used as a matrix modifier. Recovery for 40 micrograms/l is 93.7 +/- 4.6% (mean +/- SD) from serum and 92.8 +/- 5.4% from blood; within-day precision (n = 10) at 40 micrograms/l is 3.2% for serum and 4.2% for blood. Day-to-day precision at 40 micrograms/l (n = 10) was 4.5% for serum and 4.0% for blood. The detection limit is 0.7 microgram/l for serum and 1.0 microgram/l for blood. Blood samples have to be collected in glass tubes and stored at -20 degrees C.

Renal damage in mice after sequential cisplatin and irradiation: the influence of prior irradiation on platinum elimination

Doses of 4-6 mg kg-1 c-DDP given 6 months before renal irradiation caused only a modest increase in functional radiation damage (DEF 1.1). These effects could be explained by additive toxicities and the damage was much less than when c-DDP was given 3-6 months after irradiation. Pharmacokinetic studies did not demonstrate any decrease in the rate of platinum elimination after previous low-dose renal irradiation.

Biological effect monitoring of occupational exposure to 1,3-dichloropropene: effects on liver and renal function and on glutathione conjugation

A prospective study was performed in the Dutch flower bulb culture to investigate the possible effects of subchronic exposure to the soil fumigant 1,3-dichloropropene (DCP) on liver and kidney function and on glutathione conjugation capacity in blood. Urine spot samples and venous blood samples from 14 workers applying DCP (applicators) were taken at the start of the season in July, and after the season in October. The parameters of liver function measured were: alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase, gamma-glutamyltranspeptidase, and total bilirubin (conjugated and unconjugated). Total bilirubin was significantly decreased from 9.5 before to 7.0 mumol/l after the season. In combination with an increase in serum gamma-glutamyltranspeptidase activity from 12.5 to 19.5 U/l this indicates moderate hepatic enzyme induction. To study renal function, creatinine and beta 2-microglobulin in serum, and beta 2-microglobulin, albumin, alanine aminopeptidase, beta-galactosidase, and retinol binding protein in urine were measured. The glomerular function parameters albumin in urine and creatinine in serum changed significantly during the season: albumin concentration increased from 5.2 to 7.6 mg/l, whereas creatinine concentration [corrected] decreased from 93.0 to 87.5 mumol/l. The tubular function parameter retinol binding protein also increased in concentration from 20.0 to 26.9 micrograms/l. Therefore, a subclinical nephrotoxic effect of subchronic exposure to DCP cannot be excluded. Effects on glutathione conjugation capacity were studied by measuring erythrocyte glutathione S-transferase activity and blood glutathione concentrations. The activity of glutathione S-transferase in erythrocytes was significantly decreased from 4.7 before to 3.3 U/g haemoglobin after the season. The same was true for the blood glutathione concentrations, which decreased from 0.93 to 0.82 mM.(ABSTRACT TRUNCATED AT 250 WORDS)