Construction and evaluation of drug-metabolizing cell line for bioartificial liver support system.

Focusing on drug metabolism in liver, we constructed and evaluated a drug-metabolizing bioartificial liver (BAL) support system. In a previous study, we constructed ammonia-metabolizing CHO and hepatoma-derived HepG2 cell lines by recombination of the glutamine synthetase (GS) gene. For further mimicking of liver metabolism, the human hepatoma-derived cell line HepG2 was transformed by the pBudCE-GS-CYP3A4 vector, which contains GS and drug-metabolizing CYP 3A4 genes. The constructed GS-3A4-HepG2 cell line showed 3A4 activity higher than that of human primary hepatocytes. The drug-metabolizing activity of BAL (BAL clearance) was evaluated using this cell line. The estimated clearance was higher than that of the human hepatocyte system.

2,3-Dimercapto-1-propanol does not alter the porphobilinogen synthase inhibition but decreases the mercury content in liver and kidney of suckling rats exposed to HgCl2.

Heavy metals have received great attention as environmental pollutants mainly because once introduced in the biological cycle they are incorporated in the food chain. Especially the mercury toxicity due to a diversity of effects caused by different chemical species should be emphasized. Heavy metal intoxication has been treated with chelating agents such as 2,3-dimercapto-1-propanol (BAL). However, the efficacy of this treatment is questionable due to the lack of specific effect on the toxic metal. The present study examined the effects of HgCl2 exposure (five doses of 5.0 mg/kg between ages 8 to 12 days) on physiological parameters, on porphobilinogen synthase activity, and on mercury content in liver, kidneys and brain from suckling rats. The effect of BAL (one dose of 12.5-75 mg/kg) applied 24 hr after mercury intoxication on these parameters was also investigated. The results demonstrate that HgCl2 intoxication induced a decrease of corporal weight gain as well as brain weight and an increase in renal weight. The inhibition of porphobilinogen synthase from liver and kidney, is still significant and was not modified by subsequent BAL treatment. However, BAL altered two effects induced by mercury: increase in death percentage and decrease in mercury contents in liver and kidney. The increase of mortality induced by mercury was not promoted by metal redistribution to brain nor by the increase of porphobilinogen synthase inhibition induced by metal. More investigations are necessary to determine if the different effects of BAL on intoxication by metals are possibly related to other tissues and/or if the probable metal-chelating complex formed is more toxic than the metal itself.

Gas chromatographic-mass spectrometric determination of british anti-lewisite in plasma.

British anti-Lewisite (BAL) (2,3-dimercapto-1-propanol) is a potential therapeutic compound when used against the effects of cutaneous sulfur mustard, and a method for its determination in plasma has been developed. BAL and the internal standard (IS) ethane dithiol were isolated from plasma samples through solid-phase extraction and then reacted with 1-pentafluoropropionylimidazole, forming stable pentafluoropropionyl derivates that are sensitive to gas chromatographic-mass spectrometric analysis. Examination of concentration versus peak-area ratios of the BAL and IS derivatives demonstrated the method to be linear over a concentration range of 0.48 to 124 ng/mL in plasma when fit to a weighted (1/y2) least-squares regression. Correlation coefficients were 0.9943 to 0.9995 for six runs, and coefficients of variation (CV) were 2.5 to 8.7% over the eight concentrations tested. The intra- and interday accuracy and precision of this method was measured by examining six groups of eight unknown test samples (n = 6). Intraday accuracy, as expressed by percent error, was found to range from -15.4 to 0.21%, whereas the precision, expressed as %CV, was less than 9.8% over all sample concentrations. Interday test unknown sample results were similar in that the accuracy was shown to be -7.1 to 0.4%, and precision was 4.7 to 9.5%. BAL levels in frozen plasma (-70 degrees C) remained constant for more than 14 days with a CV of less than 10% for the eight concentrations tested. The data indicate that the method will provide accurate and precise determination of BAL at concentrations down to approximately 1 ng/mL in plasma. This procedure has been applied to determine preliminary time-concentration profile studies of BAL in the hairless guinea pig.

Are we ready to replace dimercaprol (BAL) as an arsenic antidote?

1 Dimercaprol (BAL), 2,3-dimercaptopropanesulphonate sodium (DMPS) and meso-2,3-dimercaptosuccinic acid (DMSA) are effective arsenic antidotes, but the question which one is preferable for optimal therapy of arsenic poisoning is still open to discussion. Major drawbacks of BAL include (a) its low therapeutic index, (b) its tendency to redistribute arsenic to brain and testes, for example, (c) the need for (painful) intramuscular injection and (d) its unpleasant odour. 2 The newer antidotes DMPS and DMSA feature low toxicity and high therapeutic index. They can be given orally or intravenously due to their high water solubility. While these advantages make it likely that DMPS and DMSA will replace BAL for the treatment of chronic arsenic poisoning, acute intoxication-especially with lipophilic organoarsenicals-may pose a problem for the hydrophilic antidotes, because their ionic nature can adversely affect intracellular availability. 3 This article focuses on aspects dealing with the power of BAL, DMPS, and DMSA to mobilize tissue-bound arsenic in various experimental models, such as monolayers of MDCK (= Madin-Darby canine kidney) cells from dog kidney, isolated perfused liver from guinea-pigs, and perfused jejunal segments from rat small intestine. 4 The results show that hydrophilic DMPS and DMSA may fail to rapidly and completely remove arsenic that has escaped from the extracellular space across tight epithelial barriers. However, owing to their low toxicity, which allows larger doses to be applied, and the potential modification of their pharmacokinetics by means of inert oral anion-exchange resins, DMPS and DMSA may advantageously replace BAL whenever intervention time is not critical. With severe intoxication by organic arsenicals, when the point-of-no-return is a limiting factor, BAL may still have a place as an arsenic antidote.

The importance of 2,3-dimercaptopropinol (British anti-lewisite, BAL) in the trypanocidal activity of topical melarsoprol.

Both melarsomine dichlorhydrate (mel Cy, Cymelarsan) and melarsen oxide can be dissolved in dimethylsulfoxide and converted into a gel by the addition of hydroxypropylcellulose. When Trypanosoma brucei brucei-infected mice are treated topically with these gels the circulating trypanosomes are rapidly cleared from the circulation but the infections relapse soon after the last application. However, when these two compounds are allowed to react with 2,3-dimercaptopropinol (British anti-lewisite, BAL) and form "melarsoprol" their efficacy, especially in the case of mel Cy, is restored to that of commercial melarsoprol (Arsobal) and trypanosomes in the central nervous system (CNS) can be eliminated. This would indicate that the dimercaptopropinol portion of the molecule does not act solely as an "antidote" to arsenic toxicity, but also plays an important role in the absorption of melarsoprol through the skin and/or blood-brain barrier into the CNS and/or into the trypanosome.

Subcellular localization of gold in suprarenal testicle and thyroid glands after injection of allochrysine in rats.

Gold injected under the form of anti-rheumatoid polyarthritis soluble solutions provokes, as observed by electron microscope, a deposit of crystalline micro-needles in different tissues, like in cells of adrenal and suprarenal glands, in Leydig cells of the testicles, in isolated thyrocytes and in thyroid endothelial cells. They are present as bundles, often of incurvated type, of high electron-density, present in lysosomes, which contain moreover a hyaline, emptied vesicle. These structures are named "aurosomes". The microanalysis, using the MS 46 (Cameca) and the Camebax (MBX) demonstrates that these crystalline structures are composed by gold associated with sulphur, and not with phosphate.

A comparative study of the influence of vicinal dithiols and a dithiocarbamate on the biliary excretion of cadmium in rat.

The effect of two vicinal dithiols, 2,3-dimercaptopropan-1-ol (BAL) and N-(2,3-dimercaptopropyl)phthalamidic acid (DMPA), and a dithiocarbamate, sodium N-(4-methoxybenzyl)-D-glucamine dithiocarbamate (MeOBGDTC), on the biliary excretion of cadmium was examined in rats. Tissue cadmium levels were also determined following the measurements of biliary excretion of cadmium. At 30 min after the injection of CdCl2.2.5H2O (1 mg/kg, iv) each rat was given 400 mumol/kg ip of one of the compounds, BAL, DMPA or MeOBGDTC. While all the compounds increased the biliary excretion of cadmium, the most effective was MeOBGDTC, whose administration resulted in a 580% increase in biliary cadmium content. The effectiveness of the MeOBGDTC may be due to the presence of both nonpolar and nonionizing polar groups attached to nitrogen. MeOBGDTC was able to mobilize cadmium to the bile even after the occurrence of the synthesis of metallothionein and the incorporation of the cadmium into it. An attempt was also made to determine the chemical nature of the Cd-MeOBGDTC complex present in the bile by comparing a newly synthesized authentic sample of Cd(MeOBGDTC)2 complex with the hot dioxane extract of the freeze-dried bile samples using thin-layer chromatography and proton NMR. The results suggested that cadmium excreted in the bile in part, is complexed to MeOBGDTC and glutathione.