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.

A novel and simple colorimetric assay for human serum lipase.

A new and simple colorimetric method for human serum lipase [EC 3.1.1.3] assay has been developed, using 2,3-dimercaptopropan-1-ol tributyroate as a substrate, 5,5'-dithiobis(2-nitro-benzoic acid) as a chromogenic reagent, phenylmethylsulfonyl fluoride as an inhibitor of serum esterases, and sodium dodecylsulfate as a lipase activator. The method requires only 50 micron1X2 of serum sample and a reaction time of less than 30 min. The method is reproducible and sensitive enough to measure low levels of lipase activity in normal and abnormal sera. The gel filtration of serum samples on a Sephadex G-200 column gave one peak of lipase activity, when measured by the present method, and the molecular weight of the enzyme was identical with that of lipase of human pancreatic origin, confirming the specificity of this new method for the serum lipase.

Mobilization of heavy metals by newer, therapeutically useful chelating agents.

Four chelating agents that have been used most commonly for the treatment of humans intoxicated with lead, mercury, arsenic or other heavy metals and metalloids are reviewed as to their advantages, disadvantages, metabolism and specificity. Of these, CaNa2EDTA and dimercaprol (British anti-lewisite, BAL) are becoming outmoded and can be expected to be replaced by meso-2,3-dimercaptosuccinic acid (DMSA, succimer) for treatment of lead intoxication and by the sodium salt of 2,3-dimercapto-1-propanesulfonic acid (DMPS, Dimaval) for treating lead, mercury or arsenic intoxication. Meso-2,3-DMSA and DMPS are biotransformed differently in humans. More than 90% of the DMSA excreted in the urine is found in the form of a mixed disulfide in which each of the sulfur atoms of DMSA is in disulfide linkage with an L-cysteine molecule. After DMPS administration, however, acyclic and cyclic disulfides of DMPS are found in the urine. The Dimaval-mercury challenge test holds great promise as a diagnostic test for mercury exposure, especially for low level mercurialism. Urinary mercury after Dimaval challenge may be a better biomarker of low level mercurialism than unchallenged urinary mercury excretion.

A colorimetric microplate assay method for high throughput analysis of lipase activity.

The present work describes a colorimetric microplate assay for lipase activity based on the reaction between 5,5'-dithiobis(2-nitro benzoic acid) (DTNB) and the hydrolysis product of 2,3-dimercapto-1-propanol tributyrate (DMPTB). Reaction mixtures containing DTNB, DMPTB, and lipase were prepared in microplate wells, and the absorbance at 405nm was recorded after incubation at 37 degrees C for 30 min. A linear relationship was obtained in the range of 0.1-1 U of lipase activity by this method. The reaction conditions were also optimized for the range of 0.01-0.1 U or 1-10 U. When assaying crude tissue extracts, the reaction of DTNB with non-specific reducing agents created a major source of error. However, this error was corrected by the use of blank samples that did not contain DMPTB.

In vivo and in vitro effect of chelating agents on drug metabolizing enzymes of the rat.

Rats given calcium disodium ethylenediaminetetraacetic acid (CaNa2EDTA), diethylenetriaminepentaacetic acid (DTPA), dimercaprol, p-aminosalicylic acid (PAS), or d-penicillamine (penicillamine) i.p. for 7 successive days showed a significant decrease in the activity of hepatic microsomal benzphetamine N-demethylase. There was no appreciable change in the microsomal cytochrome P-450 concentration. In vitro incubation of the chelating drugs with liver microsomes isolated from rats pre-treated with phenobarbital caused no significant loss of the hemoprotein. The decreased rate of benzphetamine metabolism in microsomal preparations from rats, pretreated with the chelating drugs, may be attributed partly to hepatic depletion of essential trace elements by the chelating drugs.

[Hepatitis secondary to a gold salt overdose]. / Hépatite secondaire à un surdosage en un sel d'or.

The authors report the case of a 51-year-old woman who developed cholestatic and cytolytic hepatitis after an overdose of sodium aurothiopropanol sulfonate 1.1 g, namely 300 mg gold metal. Liver biopsy demonstrated cholestasis, centrolobular steatosis and portal fibrosis. Electron microscopy showed abundant lipo-pigments in the hepatic and cellular cells, as well as myelinic bodies. Gold analysis by atomic absorption spectroscopy showed a level of 22.76 micrograms per ml in the plasma and a level of 2.16 micrograms per g in the liver. Chelating agents increased the urinary gold excretion, but were without effect on the course of hepatitis. Dimercaptopropanol seemed to favor the occurrence of other gold salt side-effects and penicillamine increased the hepatic cytolysis. The patient recovered without sequelae.

Reaction of the catalytic cysteine of betaine aldehyde dehydrogenase from Pseudomonas aeruginosa with arsenite-BAL and phenylarsine oxide.

Betaine aldehyde dehydrogenase (BADH) catalyses the irreversible oxidation of betaine aldehyde to glycine betaine with the concomitant reduction of NAD(P)(+) to NAD(P)H. In the opportunistic pathogen Pseudomonas aeruginosa, this enzyme (PaBADH) could be an antimicrobial target. Several aldehyde dehydrogenases (ALDHs) are inactivated by arsenite in the presence of a low molecular thiol, a finding that was interpreted as a demonstration of the existence of vicinal thiols in these enzymes. As part of our studies on the susceptibility to chemical modification of the catalytic cysteine (C286) of PaBADH, we treated the enzyme with two arsenical reagents widely used to inhibit enzymes that have vicinal thiols: sodium m-arsenite plus 2,3-dimercaptopropanol (arsenite-BAL) and phenylarsine oxide (PAO). Here we report that they readily and reversibly inactivate PaBADH, even though the four cysteine residues of this enzyme (C286, C353, C377, and C439) are far from each other in the three-dimensional structure. Modification of PaBADH by both reagents was reversible by an excess of a dithiol (dithiothreitol), but only the PAO-modified enzyme could be reactivated by a monothiol (2-mercaptoethanol). C286 is the reactive residue as indicated by the following findings: (i) betaine aldehyde and NADP(+) afforded full protection against enzyme inactivation; (ii) the mutant proteins C353A, C377A, and C439A showed similar inactivation kinetics that the wild-type enzyme, and (iii) pretreatment of PaBADH with arsenite-BAL prevented irreversible inactivation by N-ethylmaleimide. Our results confirm previous findings on other ALDHs, and indicate that these vicinal thiol-specific reagents readily react with certain monothiols, such as the one of the catalytic cysteinyl residue of ALDHs. As arsenicals are being recently used to treat certain cancers, human ALDHs, even those not having conformationally vicinal thiols, may be unsuspected targets in these treatments.

Distribution and excretion of the mercury chelating agent sodium 2,3-dimercaptopropane-1-sulfonate in the rat.

The distribution and excretion of sodium 2,3-dimercapto-1,3 14C-propane-1-sulfonate as dependent on time has been studied in the rat. The highest concentration is found in the kidneys, the lowest in the brain. The excretion is very rapid (T1/2 = 19 min) and follows a monoexponential curve during the first hour after administration. This holds for plasma and most of the organs too. The apparent distribution volume of the radioactivity is equivalent to the volume of the extracellular water. After oral administration, 30-40% is absorbed from the gut. The results lead to the conclusion that a fraction of the drug is weakly bound to plasma- and membrane-proteins. They are discussed with respect to the treatment of heavy metal poisoning.

[Penetration and binding strength of cadmium and its complexes with dithiols in cells]. / Proniknovenie i prochnost' sviazyvaniia kadmiia i ego kompleksov s ditiolami v kletkakh.

It was shown in experiments with three types of cells (dog red cells, hepatic cells of newborn Wistar rats, and culture of the renal epithelium of Vero monkeys) that cadmium in complexes with dimercaptoethanol penetrates the cells in an 8-33-fold greater amounts than free cations of metal. Unithiol increases cadmium penetration in the cells by 1.6-3 times only. The strength of cadmium binding with dimercaptopropranolol in the cells is greater than that with unithiol and free cations. Albumin limits penetration of free cations of cadmium and of complexes with dimercaptothiol to a greater degree than that of cadmium complexes with unithiols. The reasons for the differences revealed are discussed.

On the reactivity of metallothioneins with 5,5'-dithiobis-(2-nitrobenzoic acid).

Rat liver and horse kidney metallothioneins react with 5,5'-dithiobis-(2-nitrobenzoic acid) (Nbs2) to release 5-thio-2-nitrobenzoate and metal ions. The reactions are slow and exhibit biphasic kinetics with each process having an empirical rate law of the form: rate - k[RSM] X [Nbs2] + k'[RSM], where RSM represents mental-bound thiolate groups. The pseudo-first-order rates are insensitive to pH but are modified in guanidine hydrochloride solution. Rat liver metallothioneins of variable zinc, copper and cadmium composition react similarly and give observable thiol/total metal ratios in good agreement with stoichiometries of SH/(Cd + Zn) of 3 and SH/Cu of 1. A model complex cadmium-2,3-dimercaptopropanol, resembles the proteins in its reaction with Nbs2.

Increased level of exhaled nitric oxide and up-regulation of inducible nitric oxide synthase in patients with primary lung cancer.

Monocyte-macrophage series have an important role in host surveillance against cancer. The cytotoxic/cytostatic activity of macrophages is, to a great extent, attributed to the up-regulation of inducible nitric oxide synthase (iNOS) and production of nitric oxide (NO). Here, in 28 patients with primary lung cancer and 20 control subjects, we measured the concentration of exhaled NO and nitrite in epithelial lining fluid (ELF) using a chemiluminescence NO analyser, and studied NOS expression in alveolar macrophages (AM) and lung tissues by flow cytometry; immunohistochemical analysis was also undertaken. The mean fluorescence intensity (FI) of iNOS expression in AM was significantly increased in patients with lung cancer (tumour side 263.5 +/- 15.2 FI, normal side 232.4 +/- 18.6 FI; n = 28) compared with that in control subjects (27.3 +/- 3.2 FI; n = 20, P< 0.001). The level of exhaled NO from cancer patients (16.9 +/- 0.9 p.p.b.; n = 28) was significantly higher than that in the control group (6.0 +/- 0.5 p.p.b.; n = 20, P < 0.001). The level of nitrite was also significantly higher in ELF from cancer patients (tumour side 271.1 +/- 28.9 nM and normal side 257.4 +/- 19.6 nM vs control subjects 32.9 +/- 4.1 nM; P< 0.001). The intensity of iNOS expression in AM was correlated with the level of exhaled NO (rs = 0.73, n = 76, P< 0.001) and the nitrite released in ELF (rs = 0.56, n = 76, P< 0.001). The nitrite generation of cultured AM from patients with lung cancer was significantly enhanced compared with that of control subjects after culture for 24 h (tumour side 5.75 +/- 0.69 and normal side 5.68 +/- 0.58 microM per 106 cells vs control group 38.3 +/- 3.6 nM per 106 cells; P< 0.001). The distribution of iNOS was identified in AM, tumour-associated macrophages, endothelium, chondrocytes, airway epithelium of both lungs and malignant cells (adenocarcinoma and alveolar cell carcinoma) of cancer patients. cNOS was labelled in alveolar macrophages, endothelial cells and nerve elements from lung tissue. Our results indicate that, in patients with primary lung cancer, the production of NO from alveolar macrophages was increased as a result of the up-regulation of iNOS activity. The increased NO production was not specific to the tumour side and might be attributed to the tumour-associated non-specific immunological and inflammatory processes of the host.

Diaminopimelate decarboxylase of sporulating bacteria.

The meso-diaminopimelate (DAP) decarboxylase of Bacillus licheniformis, a pyridoxal phosphate-requiring enzyme, was stabilized in vitro by 0.15 m sodium phosphate buffer (pH 7.0) containing 1 mm 2,3-dimercaptopropan-1-ol, 100 mug of pyridoxal phosphate per ml, and 3 mm DAP. When the meso-DAP concentration was varied, the enzyme in cell-free extracts of B. licheniformis exhibited Michaelis-Menten kinetics. Pyridoxal phosphate was the only pyridoxine derivative which acted as a cofactor. The enzyme was subject to both inhibition and repression by l-lysine. The inhibitory effect of lysine was on the K(m) (meso-DAP). A maximum repression of about 20% was obtained. No significant inhibition or activation was produced by cadaverine, dipicolinic acid, phenylalanine, pyruvate, ethylenediamine-tetraacetate, adenosine triphosphate, adenosine diphosphate, or adenosine monophosphate. When B. licheniformis was grown in an ammonium lactate-glucose-salts medium, an increase in DAP decarboxylase specific activity occurred during cellular growth with a maximal specific activity at the end of the exponential phase. As soon as growth ceased, the specific activity of the enzyme decreased to approximately one-half of the maximal specific activity and remained at this level thereafter. When B. cereus was grown in complex media, there was an increase in DAP decarboxylase specific activity up to the end of the exponential phase. Thereafter, the specific activity decreased to a nondetectable level in 4 hr. Dipicolinic acid synthesis was first detected 15 min later and was essentially complete after an additional 2.5 hr. The significance of the disappearance of DAP decarboxylase in B. cereus was discussed with regard to control of dipicolinic acid and spore mucopeptide biosynthesis.

Lipolytic activity of ricin from Ricinus sanguineus and Ricinus communis on neutral lipids.

The present study was carried out with a view of determining ricin lipolytic activity on neutral lipids in emulsion and in a membrane-like model. Using 2,3-dimercapto-1-propanol tributyrate (BAL-TC(4)) as substrate, the lipolytic activity of ricin was found to be proportional to ricin and substrate concentrations, with an apparent K(m) (K(m,app)) of 2.4 mM, a k(cat) of 200 min(-1) and a specific activity of 1.0 unit/mg of protein. This work was extended to p-nitrophenyl (pNP) fatty acid esters containing two to twelve carbon atoms. Maximum lipolytic activity was registered on pNP decanoate (pNPC(10)), with a K(m,app) of 3.5 mM, a k(cat) of 173 min(-1) and a specific activity of 3.5 units/mg of protein. Ricin lipolytic activity is pH and galactose dependent, with a maximum at pH 7.0 in the presence of 0.2 M galactose. Using the monolayer technique with dicaprin as substrate, ricin showed a lipolytic activity proportional to the ricin concentration at 20 mN/m, which is dependent on the surface pressure of the lipid monolayer and is detectable up to 30 mN/m, a surface pressure that is of the same order of magnitude as that of natural cell membranes. The methods based on pNPC(10) and BAL-TC(4) hydrolysis are simple and reproducible; thus they can be used for routine studies of ricin lipolytic activity. Ricin from Ricinus communis and R. sanguineus were treated with diethyl p-nitrophenylphosphate, an irreversible serine esterase inhibitor, and their lipolytic activities on BAL-TC(4) and pNPC(10), and cytotoxic activity, were concurrently recorded. A reduction in lipolytic activity was accompanied by a decrease in cytotoxicity on Caco2 cells. These data support the idea that the lipolytic activity associated with ricin is relevant to a lipase whose activity is pH and galactose dependent, sensitive to diethyl p-nitrophenylphosphate, and that a lipolytic step may be involved in the process of cell poisoning by ricin. Both colorimetric tests used in this study are sensitive enough to be helpful in the detection of possible lipolytic activities associated with other cytotoxins or lectins.

Oleic acid-induced pulmonary injury in rats: potential role of sulfidopeptide leukotrienes.

Lung injury following intravenous oleic acid is characterized by pulmonary edema, leukopenia and hypoxemia. Because leukotrienes can increase permeability and cause leukocyte adherence, we evaluated their potential role in oleic acid-induced lung injury in the anesthetized rat using a selective LTD4/E4 antagonist, LY171883. 99mTc-albumin and 99mTc-red blood cells (99mTc-RBC) were used to measure changes in the pulmonary permeability index and intravascular space by non-invasive scintigraphy. Intravenous oleic acid (0.06 ml/kg) increased the pulmonary permeability index 11 (P less than 0.01) and 5.8 fold (P less than 0.01) at 5 and 50 min after its injection compared to baseline, but had no effect on mean pulmonary arterial pressure or pulmonary distribution of 99mTc-RBC. Oleic acid also induced arterial hypoxemia, and increased bronchoalveolar lavage-fluid levels of immunoreactive (i) leukotriene LTC4 from 0.40 +/- 0.14 ng/ml to 2.27 +/- 0.55 ng/ml (mean +/- S.E.M., n = 4, P less than 0.05) and iLTB4 (from 0.42 +/- 0.05 ng/ml to 1.91 +/- 0.63 ng/ml, n = 5-7, P less than 0.01). LY171883 attenuated the elevated permeability by 24% and 68% at 5 (P less than 0.05) and 50 min (P less than 0.01), but did not alter the hypoxemia. These results support the hypothesis that oleic acid elevates leukotriene levels which may increase pulmonary vascular permeability. Furthermore, they suggest that the prevention of elevated pulmonary vascular permeability and edema may be necessary, but are clearly not sufficient to prevent arterial hypoxemia following oleic acid injury in the rat.

[Ultrastructural and microanalytic study of gold depots in the synovial membrane of man and animals during treatment with sodium aurothiopropanol sulfonate]. / Etude ultrastructurale et microanalyse des dépôts d'or dans la membrane synoviale chez l'homme et chez l'animal au cours des traitements par l'aurothiopropanol-sulfonate de sodium.

In inflammatory rheumatism treated by gold therapy synoviocytes A are stuffed with gold salt deposits leading to a therapeutic thesaurismosis. These deposits are localized in lysosomes, then called aurosomes. However they may be rarely near collagen fibers or free, particularly in ankylosing spondylitis synovitis. Their structural morphological aspect is the same in several human rheumatic diseases and in rabbit experimental arthritis whatever the gold salt used. In such deposits, microprobe analysis shows gold and sulphur. This latter is probably given by the cell. Therapeutic effect of gold salts may imply the effect of the thiol moiety and the gold metal one.

[Lysosomotropism and anti-inflammatory action of gold salts]. / Lysosomotropisme et action anti-inflammatoire des sels d'or.

Gold salts have been widely used in the past 70 years in the treatment of various connective tissue diseases and more particularly in rheumatoid arthritis. However their mechanism of action remains poorly understood. Gold salts are transported in the blood linked with several serum proteins including immunoglobulins. Methods of analytical electron microscopy (Castaing probe) have shown that gold is actively concentrated in the lysosomes of various cell types, including the proximal tubular cells of the kidney and certain bone marrow cells. These data, together with those provided by biochemical techniques, suggest that sodium aurothiopropanol sulfonate modifies the stability of lysosome membranes. In the present study it is shown that the stability of kidney lysosomes of treated rats was increased by 42.4 per cent after treatment for 3 days. This protective action was also seen when lysosomes were subjected to lysis by digitonin. The protective effect of gold salts on the lysosomal membrane may be explained by the formation of chemical complexes between gold and sulfhydryl groups present in the membrane, resulting in stable mercaptic bonds. These findings suggest that the increase in stability of lysosomal membranes plays a significant role in the anti-inflammatory action of gold salts.