Estimates of total polychlorinated biphenyl (PCB) compounds in soils/sediments by hydrogenolysis to dicyclohexyl.

A method to determine the total PCB content by hydrogenolysis (hydrodechlorination and hydrogenation) of chlorinated biphenyl compounds was extended to natural particulate matrices (soil and sediment). The contaminated soil was suspended in hexane in the presence of Pd/gamma-Al2O3 in a hydrogen atmosphere then permitted to react for one hour at 65 degrees C. Dicyclohexyl, recovered in the hexane, was quantified by gas chromatography mass spectrometry. The reaction was very efficient for soil/sediment in hexane suspension and virtually complete provided that excess catalyst was added to samples that were burdened with higher PCB loadings prior to reaction otherwise some partial hydrogenation of biphenyl was also observed. The proposed method was validated with the analysis of five certified reference materials.

Extractions of polychlorinated biphenyl (PCB) compounds from surfactant suspension/soil extracts with dechlorination on-line.

Polychlorinated biphenyl (PCB) formulation (Aroclor 1242 or 1248)-surfactant (Brij 97 or Triton CF54) emulsions (0.1-1.0%, v/v) were extracted with supercritical carbon dioxide (scCO2). The declinations curve that resulted for each loading of PCB substrate was accurately modelled as a single-exponential decay, and the half-life [t1/2, 10.76 min +/- 2% (Brij 97) or 10.0 min +/- 14% (Triton CF54)] was independent of the level of loading. When the extraction was combined with on-line dechlorination, t1/2 was increased to 17.62 min +/- 6% or 16.46 min +/- 5%, respectively The dechlorination reactor contributed appreciably to the back-pressure of the system so that, under identical scCO2 head pressures, the flow rate at the exit of the system was reduced from 1500 mL min-1 (as decompressed gas) to 900 mL min-1. When corrected for the difference in flow rates, the declination curves in the absence and presence of the reactor became virtually identical. For a surfactant suspension from a soil that was field-burdened with only 6 ppm PCBs, extended operation (extraction-dechlorination) for 15 h, during which the substrate suspension was replaced every 30 min, caused no loss of the dechlorination efficiency; however, for 1% (v/v) Aroclor 1242 or 1248 in surfactant suspension, the reactor gradually lost reactivity over 5 h of continued operation. However, the reactivity could be restored virtually completely by purging the reactor column with scCO2 for 3 h or washing the column at ambient temperature with 30 mL of methanol-water (7 + 3, v/v). Mass spectrometry of the reaction products indicated that the principal products included biphenyl and toluene, but methylated benzenes and phenols were also present.

Approaches to soil remediation by complexometric extraction of metal contaminants with regeneration of reagents.

Complexometric equilibrations were performed with six chelating reagents to mobilise Cu, Mn, Pb and Zn from a contaminated urban soil. The metal-laden aqueous extract was treated with sodium diethyldithiocarbamate (DEDTC) to precipitate the heavy metals from solution while liberating the chelating reagent. The aqueous supernatant fraction was then re-combined with the soil particulates to extract more pollutants. A sparing quantity of EDTA (ethylenediaminetetraacetic acid; 10 mmol) mobilised 32-54% of the 5 mmol of heavy metals from the soil with three cycles but only 0.1 and 1.0% of the iron and magnesium, respectively, was removed. Whereas DPTA (1,3-diamino-2-hydroxypropane-N,N,N',N'-tetraacetic acid) and citric acid also mobilised each of the heavy metals to some extent and continued to extract these metals during all three cycles, the DTPA (diethylenetriamine pentaacetic acid), although efficient initially, could not be recycled with these conditions. ADA [N-(2-acetamido)iminodiacetate] and SCMC [(S)-carboxymethyl-L-cysteine] were selective for copper and zinc but mobilised only Cu when recycled. An alternate means of regenerating the chelating reagent involved treatment of the aqueous extract with magnesium (Mg0) granules. Excess HEDC [bis(2-hydroxyethyl)dithiocarbamate] mobilised appreciable quantities (19-57%) of heavy metals from the soil and retained its complexing activity when recycled. An appreciable fraction of the mobilised Pb and Cu and a portion of the Zn were cemented to the surfaces of the excess magnesium whereas virtually all of the Fe and Mn was removed from solution as insoluble hydroxides.

Approaches to the remediation of a polychlorinated biphenyl (PCB) contaminated soil--a laboratory study.

A soil that had been historically contaminated with Aroclor 1242, 1248, 1254 and 1260 was decontaminated by two surfactant-mediated cleaning procedures that had been chosen to mimic ex-situ washing and in-situ soil flushing processes. A preliminary screening selected four surfactants (from 17 commercial formulations) for their ability to mobilise PCBs from the soil while suffering minimal losses to the supercritical carbon dioxide (scCO2) that was used in a separate back-extraction procedure. The mobilisation was enhanced, with minimal foam formation, by the presence of 17% (v/v) IBMK in the surfactant suspension. Each of the four surfactants, at 1, 3, or 5% (v/v) concentration, was evaluated by (i) 15 successive 10 min sonication-filtrations and (ii) continuous soil column flushing during 20 h. Each filtrate from (i) and samples, taken at hourly intervals, from (ii) were analysed for their PCB and surfactant content. Both extraction procedures mobilised PCBs efficiently when extended for longer periods and were modelled accurately as the sum of a constant and single-term exponential increase to a maximum. The predicted number of replicate stages required to mobilise 50% of the toxicants (t50) varied from 7 to 3 for sonication-washing of the soil (10 g) or from 6.8 to 2.8 h for column flushing of 30 g soil and decreased as the concentration of surfactant in the aqueous phase was increased. The combined PCB-laden aqueous suspensions were then back-extracted efficiently with scCO2 and the eluate was dechlorinated quantitatively as it traversed a short, heated column of silver-iron bimetallic mixture.

Enzymatic digestion-high-pressure homogenization prior to slurry introduction graphite furnace atomic absorption spectrometry for selenium determination in plant and animal tissues.

Homogenization using a new flat valve homogenizer in combination with enzymatic digestion with a crude protease was investigated as a means of releasing Se compounds from zoological and botanical matrixes prior to slurry introduction GFAAS. Timed trials with four zoological certified reference materials (CRMs), three botanical reference materials (RMs), and a food crop indicated that Se release into 5% (v/v) ethanol-0.03 M TRIS containing 20 mg of protease was quantitative after homogenization or became quantitative within 1 h of digestion at 60 degrees C. For each of the zoological RMs (whole egg powder, dogfish muscle, and dogfish liver), three passes through the homogenizer in the presence of protease provided a quantitative release of selenium, and incubation with the enzyme was not necessary. No separation of the Se between the liquid phase and the particulate phase was evident even after several days of subsequent storage at 4 degrees C. The botanical matrixes (three milled wheat RMs and a rapeseed sample) were more resistant to selenium release and required up to 1 h of digestion with protease at 60 degrees C. Alternatively, 10 passes through the homogenizing valve (in the presence of the enzyme) resulted in the quantitative release of analyte.

Slurry preparation by high-pressure homogenization for the determination of heavy metals in zoological and botanical certified reference materials and animal feeds by electrothermal atomic absorption spectrometry.

High-pressure homogenization was evaluated for the preparation of slurries suitable for the determination by ETAAS of Cr, Cu, Fe, Mn, Ni and Se in soft organ tissues (liver and kidney), certified reference materials of biological and botanical origin and animal feeds. Frozen fresh organ tissue, (2 g) or certified reference material or dried, ground plant material (0.1 g) was blended, at high speed with 20 ml of ethanol-water (1 + 9 v/v) containing 0.25% m/m of tetramethylammonium hydroxide and the resulting mixture was subjected to homogenization at 38.9 MPa. After four passes through the homogenizer, the resulting solution was suitable for analysis by ETAAS. Capping the flat valve head of the homogenizer with a ruby disc appreciably reduced (but did not eliminate) metal contamination introduced by the processing. Homogenization of botanical reference materials or dried animal feeds resulted in preparations with variable amounts of residual fibres and particulate matter in the resulting suspensions. Nonetheless, all the Cu and Mn and virtually all of the Fe had been transferred to the supernatant fraction and remained with that fraction for at least 10 d. The addition of EDTA to the solvent modestly increased the mobilization of Fe from the matrix but also increased the contamination from the homogenizer. The slopes of the calibration curves generated by the method of standard additions were not significantly different from those of calibration curves generated with aqueous standards in a homogenized blank indicating that there was no significant matrix effect for any of the analytes in the nine reference materials, liver or kidney or the five animal feed samples and that aqueous standards could be used to calibrate the instrumental response.

Slurry preparation by high-pressure homogenization for cadmium, copper and lead determination in cervine liver and kidney by electrothermal atomic absorption spectrometry.

Homogenization with a flat valve homogenizer in combination with high-speed blending was evaluated for the preparation of slurries suitable for the ETAAS determination of cadmium, copper and lead concentrations in six SRMs and in frozen cervine liver and kidney. Fresh tissue (approximately 2 g) or powdered SRM (approximately 0.1 g) was dispersed, at high speed, in 20 ml of ethanol-water (1 + 9 v/v) containing 0.25% m/m tetramethylammonium hydroxide. The resulting suspension was passed through a high-pressure flat valve homogenizer. Determinations performed on the resulting homogenate, provided estimates for Cd, Pb and Cu concentrations that were within 27, 23 and 18% of the certified values, respectively, for the six SRMs. In all instances, the experimental results did not differ significantly from the certified values. For frozen tissues there was good agreement between the concentrations as determined by slurry homogenization-ETAAS and conventional digestion-ICP-MS. In addition, no significant differences were detected between the slopes of the calibration curves for external standards and standard additions to homogenized sample (SRMs or fresh tissue). Moreover, replicate determinations of analyte concentrations in slurries at various times post-preparation did not detect any segregation of the homogenates during 6 d. For these matrices at least, short-term sample storage had no discernible effect on the analyte apparent concentrations. The applicability of the process was limited only by the levels of contaminating Pb and Cu introduced into the sample by the homogenizer.

Metal speciation by supercritical fluid extraction with on-line detection by atomic absorption spectrometry.

A silica flame-in-tube interface is described for the sensitive detection, by AAS, of As, Cd, Cu, Mn, Pb, Se, or Zn in supercritical (SC) fluid extractor eluate. In operation, analyte metal in aqueous medium is derivatized by in situ complexation with tetrabutylammonium dibutyldithiocarbamate (TBADB-DTC) and the product complex is mobilized into SC-CO2. The extraction process is equally efficient whether the mobile phase is presaturated with complexing agent during a static preequilibration stage of the process or this reagent is solubilized dynamically as the mobile phase traverses a saturation vessel placed in series with the extraction vessel. SC-CO2 extractor eluate is nebulized into a diffused flame maintained within the upper region of the flame tube and the optical tube of the interface. Optimal flame conditions maintained with separate flows of O2 and H2 to the base of the flame tube are slightly reducing for aqueous and SC-CO2 mobile phases but slightly oxidizing for a methanolic mobile phase. For each analyte element, limits of detection were subnanogram to low picogram if standard was flow injected into the mobile phase. These sensitivities permitted differences in the rates of mobilization of analyte metal from different matrices to be explored as a technique for probing the interactions of the analyte metal with the matrix. A portion of the total Zn burden of fresh bovine liver slurry was rapidly mobilized in the absence of complexing agent, and the remainder was solubilized more rapidly than the Zn in a freeze-dried standard reference material of this tissue.

Immunoelectrophoretic pattern of native mucosal intracellular glycoproteins of hog healthy and drug-intoxicated stomachs and of hog body fluids.

Naturally occurring glycoproteins have been extracted from fundic and antral mucosal tissue of the hog stomach by means of nondegrading techniques. Major and retarded glycoprotein fractions separated by gel filtration were further dissociated from appreciable amounts of noncovalently bound proteins by CsCl density gradient centrifugation. Antisera to glycoprotein fractions of fundic and antral regions of the stomach were prepared in rabbits. The major fractions from both gastric regions have similar molecular mass (approximately 2 x 10(6)), sedimentation coefficient (approximately 31.5 s), and specific viscosity (approximately 1.6). Purified fractions from each region were further separated into two subfractions by affinity chromatography on wheat germ lectin. Glycoprotein subfractions from antrum and fundus differ appreciably in their carbohydrate and amino acids content, share antigenic determinants, but do not cross-react with anti-hog serum protein antisera. Further diversity in native mucin glycoproteins was observed by the use of one-(D) and two-dimensional (2D) immunoelectrophoresis; subfractions that cross-react with specific anti-hog gastric glycoproteins were found to contain three or more components. D-Immunoelectrophoretic analyses demonstrated (1) in vivo degradation of glycoprotein components of the major fundic fraction isolated from mucosal tissue of alcohol/acetyl salicylate-intoxicated hog stomachs and (2) in vitro catabolism of major fundic glycoproteins by corresponding mitochondrial lysosomal (ML) acid hydrolases. Furthermore, 2D-immunoelectrophoretic analyses showed that (1) hog synovial fluid and plasma proteins have similar prosthetic moieties as either reacted with anti-hog serum proteins antisera. Nonetheless, locations, shapes, and staining intensities of the immunoprecipitate lines differed, which is indicative of different structures of the carbohydrate moieties of components of synovial fluid and plasma proteins, and (2) only a minor fraction of hog cerebrospinal fluid cross-reacted with anti-hog serum protein antisera. This is contrary to the generally accepted deduction based on high-resolution 2D-electrophoresis, indicative of different compositional patterns of plasma and cerebrospinal fluids.

Acute-phase plasma protein response to cholera intoxication in healthy and diabetic rats.

The aim of the present study is twofold: to establish the response of hepatic machinery of plasma protein biosynthesis to cholera intoxication, and to examine the same response of alloxan-diabetic hepatocytes with minimal capacity of synthesis of plasma proteins. Direct lesion of hepatic plasma membranes via ip administration of cholera toxin to male rats resulted in a typical acute-phase response (APR) of plasma proteins, which had regressed to levels similar to those of healthy controls approximately at 240 h postintoxication. The d 2 response to a single 0.16 mg/kg body weight dose was typified by a 23% reduction in the level of albumin, but a 6- and 24-fold increase in the levels of fibrinogen and alpha-1-acid glycoproteins, respectively. This response was similar (in direction but not in magnitude) to the acute-phase reaction to a simple subcutaneous administration of carrageenan. The intoxication was accompanied by a massive leakage, into the peritoneal cavity, of plasma fluid, which embraced the complete profile of acute-phase reactants. A three-step mechanism is proposed to account for the observations as follows: (1) There is a rapid formation of a stable complex between subunit B of the toxin and ganglioside GM1 of hepatic plasma membrane. An APR is induced in response to the alteration(s) of hepatic plasma membranes. (2) The release, from the choleragen-membrane complex, of polypeptide A1 and its subsequent penetration of the hepatic membrane result in both activation of adenylate cyclase and increased vascular permeability of hepatic membranes. This leads, in turn, to exudation of components of plasma fluid in the peritoneal cavity of intoxicated rats. An alternate rationale for this exudation is the slow leakage of plasma proteins out of the blood vascular system (possibly through microvesicles) into the peritoneal cavity of cholera intoxicated rats. The spectrum of acute-phase hepatic secretory components was mirrored in the corresponding peritoneal exudate. (3) The increased hepatic membrane flow provides the continued renewal of plasma membrane proteins required for its eventual repair by either endocytosis or sloughing off the toxin-bound membrane segments into the circulatory system, thus producing regression of APR. Livers of diabetic rats, an already established model in terms of APR, responded to ip administration of cholera toxin by increased biosynthesis of the identified plasma proteins and a marked reduction in total free-glucose in serum.(ABSTRACT TRUNCATED AT 400 WORDS)

Partially hepatectomized rats: a model for the study of the effect of toxins on the plasma protein profiles of nascent hepatocytes.

A useful framework is proposed for unifying the synthesis of plasma proteins and their degradation by, or release from, liver cells of intact and partially hepatectomized rats, in which synthesis and release of acute-phase plasma proteins occur in synchrony with the internalization and catabolism of plasma and extracellular proteins. The catabolism of proteins and other hepato-intracellular glycoproteins during sepsis or trauma is essential to provide constituent amino acids and carbohydrates for the synthesis of acute-phase plasma proteins. Increases in the plasma levels of acute-phase response proteins in sham-operated rats reached a maximum between 1 and 2 d after mock surgery, and had returned virtually to control levels within 6 d. By contrast, acute-phase proteins in the plasma of partially hepatectomized rats were decreased by 10-20% of their initial values after 24 h. A maximum acute-phase response on d 7 after the operation was characterized by an increase of 181, 445, and 19% for alpha-1-acid glycoprotein, hepatoglobin, and hemopexin, whereas other acute-phase proteins remained below control levels, for example, by 11, 25, and 38% for albumin, transferrin, and prealbumin, respectively. This delayed response suggests that the nascent liver cells had inherited the capacity of the parent cells to respond to inflammatory signal and had synthesized acute-phase plasma proteins. Accordingly, a time frame for the application of toxin to nascent hepatocytes is suggested. An increased activity (300 +/- 50%) for both bound and free neuraminidase in remnant liver tissue 19 h post partial hepatectomy suggested that hepatic regenerating factor(s) were produced in liver tissue via the hepatic bound and/or free neuraminidase-mediated desialylation of humoral substrates. By contrast, circulating levels of lysosomal enzymes alpha-fucosidase and beta-N-acetyl-D-glucosaminidase were increased marginally after 24 h but had returned nearly to control levels after 7 d, suggesting that lysosomal acid hydrolases do not play a major role in regenerative DNA synthesis, mitosis, or in the synthesis of acute-phase plasma proteins.

Abiotic transformations and decomposition kinetics of 4-carbamoyl-2'-[(hydroxyimino)methyl]-1,1'-(oxydimethylene)-bis(pyridin ium chloride) in aqueous phosphate buffers.

The rate of disappearance of 4-carbamoyl-2'-[(hydroxyimino)methyl]-1,1'-(oxydimethylene) bis (pyridinium chloride) (HI-6) from aqueous phosphate buffers (pH 3.0-9.1) was both pH and temperature sensitive. In midrange buffers (pH 6.0-9.1, mu = 0.2 M) at 37, 25, or 4 degrees C the decomposition followed first-order kinetics consistent with hydroxide-promoted decomposition of the un-ionized drug or with hydrolysis of the ionized oxime anion to result in 4-carbamoyl-2'-hydroxy-1,1'-(oxydimethylene)bis(pyridinium) cation (intermediate 1). The subsequent conversion of intermediate 1 to 4-carboxy-2'-hydroxy-1,1'-(oxydimethylene)bis(pyridinium) cation (intermediate 2) followed higher order kinetics which were consistent with either acid- or base-promoted hydrolysis of the B-ring amide functionality. After approximately 138 days in the dark, the sum of the residual HI-6, intermediate 1, and intermediate 2 in the crude decomposition mixture accounted for 89.9 +/- 10.0% of the initial substrate. Minor byproducts included 4-carbamoyl-2'-carboxy-1,1'-(oxydimethylene)bis(pyridinium) cation, 2-pyridinealdoxime, 2-pyridinecarboxaldehyde, 2-hydroxypyridine, isonicotinamide, isonicotinic acid, and traces of cyanide. In addition, 2-cyanopyridine appeared to be a transient intermediate in more alkaline media. In total, this drug resembles other mono- and bis(pyridinium) aldoximes in terms of the decomposition routes in aqueous solutions at intermediate pHs.

Determination of arsenobetaine, arsenocholine, and tetramethylarsonium cations by liquid chromatography-thermochemical hydride generation-atomic absorption spectrometry.

A novel high-performance liquid chromatography-atomic absorption spectrometry (HPLC-AAS) interface based on thermochemical hydride generation has been developed and optimized for the determination of arsenobetaine [(CH3)3As+CH2COOH], arsenocholine [(CH3)3As+CH2CH2OH], and tetramethylarsonium [(CH3)4As+] cations. In this quartz interface, the methanolic HPLC eluent was nebulized by thermospray effect and pyrolyzed in a methanol/oxygen kinetic flame and the analytes were thermochemically derivatized to the hydride derivative in the presence of excess hydrogen. The volatile derivative was then transported to a cool diffusion H2/O2 flame atomizer. The fact that arsenic pentoxide was also derivatized, and that no signal was observed in the absence of postthermospray hydrogen or the absence of cool diffusion flame, corroborated the thermochemically mediated arsine-generation mechanism. Factorial models predicting the performance of the interface at different levels of five selected variables suggested that (a) both reverse- and normal-phase HPLC eluents were compatible with the interface and (b) the performance of this system was relatively insensitive (less than 50% variation in response) to changes over wide ranges in the operating parameters. At concentrations up to 10-fold excess, potential interferents [(CH3)3S+, (CH3)3Pb+] did not affect, significantly, the postulated thermochemical hydride generation (THG) process. However, a 10-fold molar excess of (CH3)3Se+ decreased the response of the analyte by 48%. Virtually identical responses were observed for equimolar amounts of tetramethylarsonium, arsenocholine, arsenobetaine [As(-III)], and dimethylarsinic acid [As(III)]. Arsenic pentoxide [As(V)] was detected with 75% efficiency, relative to the response of the organoarsenic compounds.(ABSTRACT TRUNCATED AT 250 WORDS)

Kinetics, distribution, and biotransformation of the chemical HI-6 in the rat, dog, and rhesus monkey.

Disposition of the bis-pyridinium mono-oxime, HI-6, following intramuscular injection in rats (200 mg/kg bw), beagle dogs (10 and 50 mg/kg bw), and rhesus monkeys (50 mg/kg bw) revealed that the oxime was absorbed rapidly and completely from the site of injection, was distributed rapidly in the tissues, and that tissue concentrations decreased below the limits of detection by 4 h after treatment. No overt signs of toxicity were observed in any species at the concentrations given. Tissue analysis for HI-6 and degradation products was conducted by extraction followed by ion-pair, reverse phase, HPLC chromatography. The estimated plasma half-life values were 20, 40-55, and 25-30 min for rats, dogs, and monkeys, respectively. HI-6 and the degradation products were excreted via the urine. A marked species difference in disposition was observed in that HI-6 selectively accumulated in the diaphragmatic muscle of the rat to a level 10- to 20-fold higher than the level in blood plasma, whereas in the dog and monkey, diaphragmatic concentrations were comparable with those in the plasma. Three degradation products of HI-6 were detected in the plasma of the three species. One excreted product formed spontaneously since it was also detected in buffered solutions used for abiotic stability studies. The second product, the picolinic acid analog of HI-6, appeared to be metabolically formed in vivo. A third product remains unidentified.

On the genesis of gastric haemorrhage.

An hypothesis involving a three step mechanism to account for the initiation of gastric lesions is described. The mechanism necessitates: (a) A drop in the internal energy (ATP) of the mucosal cells of the stomach upon being subjected to stress; either pathological or psychological. (b) Membranes of mucosal "suicidal sacs" containing potent lysosomal acid-hydrolases are rendered fragile and burst, thus releasing hydrolytic acid-hydrolases into the cytoplasm of the mucosal cells as the latter develop an energy deficit under stress. (c) Gastric mucosal cell necrosis, via the degradation of cytoplasmic and mucinous gastric glycoproteins by these lysosomal acid- hydrolases and subjection of the submucosal tissue to the corrosive effects of the luminal fluid containing hydrochloric acid and pepsin, i.e., initiation of gastric haemorrhage. The above mechanism is a general one that describes events associated with the development of gastric lesions regardless of the factor(s) or the agent(s) initiating gastric mucosal haemorrhage.

Study of hepatotoxicity in isolated perfused liver versus cultures of rat hepatocytes.

Isolated perfused liver and cultures of rat hepatocytes were assessed for the quantitative evaluation of hepatotoxicity. Release of de novo biosynthesized plasma proteins and acid hydrolases into perfusion or culture media was taken as an indication of the integrity of hepatocytes in both systems. The activities of six acid hydrolases, alpha-L-fucosidase, alpha-D-galactosidase, beta-D-galactosidase, beta-D-N-acetylgalactosaminidase, beta-D-N-acetylglucosaminidase, and cathepsin D, were assayed in collagenase-segregated hepatocytes and in monolayer cultures of rat liver cells obtained via collagenase perfusion of rat liver. In situ, liver perfusion with collagenase led to a loss of 45 +/- 5% of the total acid hydrolase activity in the mitochondrial-lysosomal pellet of the liver cells with concomitant increase of these enzymes in the cytosol. In monolayer cultures over a period of 30 h, increased activity of cathepsin D, beta-D-galactosidase, and beta-D-N-acetylglucosaminidase in the mitochondrial-lysosomal pellet and the cytosol fraction was evident with concurrent biosynthesis of plasma proteins. The use of radioactive tracing techniques with the isolated perfused liver revealed that the rate of catabolism of intracellular protein was approximately 5 times that of plasma protein synthesis. Both methods described here are suitable for the study of the effects of toxins on the function of hepatocytes.

Inhibition by the mushroom toxins alpha-amanitin and phalloidin of hepatopoietin-induced 3H-thymidine incorporation into rat liver DNA and of plasma protein production in hepatocyte cultures.

In primary cultures of rat hepatocytes the induction of 3H-thymidine uptake into DNA of liver cells by the liver cell proliferation factor hepatopoietin demonstrates that this factor is active not only in vivo but also in vitro. Addition of the mushroom toxins alpha-amanitin or phalloidin to liver cell culture decreased the uptake of 3H-thymidine into hepatocytes (in the absence or presence of hepatopoietin) as well as the attachment of the hepatocyte cultures. Mushroom toxins also inhibited the production of plasma proteins in hepatocyte cultures. The inhibition, observed at toxin concentrations from 10(-5) to 10(-7) M, was dose-dependent. At low concentrations of phalloidin the inhibition appears to be selective for certain proteins.