An automated continuous-flow assay for serum sorbitol dehydrogenase activity and its use in experimental liver damage

Molecular Profiling of Hepatocellular Carcinoma in Mice with a Chronic Deficiency of HepaticS-Adenosylmethionine: Relevance in Human Liver Diseases

S-adenosylmethionine arises as a central molecule in the preservation of liver homeostasis as a chronic hepatic deficiency results in spontaneous development of steatohepatitis and hepatocellular carcinoma. In the present work, we have attempted a comprehensive analysis of proteins associated with hepatocarcinogenesis in MAT1A knock out mice using a combination of two-dimensional electrophoresis and mass spectrometry, to then apply the resulting information to identify hallmarks of human HCC. Our results suggest the existence of individual-specific factors that might condition the development of preneoplastic lesions. Proteomic analysis allowed the identification of 151 differential proteins in MAT1A-/- mice tumors. Among all differential proteins, 27 changed in at least 50% of the analyzed tumors, and some of these alterations were already detected months before the development of HCC in the KO liver. The expression level of genes coding for 13 of these proteins was markedly decreased in human HCC. Interestingly, seven of these genes were also found to be down-regulated in a pretumoral condition such as cirrhosis, while depletion of only one marker was assessed in less severe liver disorders.

Subacute inhalation toxicity of a medium-boiling coal liquefaction product (154-378 degrees C) in the rat [Part III]

The short-term inhalation toxicity of a medium-boiling coal liquefaction product (CLP) was investigated in the rat. Groups of 5 male and 5 female Sprague-Dawley rats were exposed to CLP aerosols at 25 mg/m3 (low dose) or 100 mg/m3 (high dose) 6 h/d, 5 d/w, for 4 wk. The control group was exposed to filtered air while the positive control received diesel fuel aerosols at 100 mg/m3. Male rats exposed to high-dose CLP aerosols exhibited growth depression and increased hepatic aminopyrine demethylase activity compared to control animals. High-dose females had decreased hemoglobin content and hematocrit values. These biochemical and hematological effects were not observed in animals of either sex treated with the diesel fuel. No other biochemical and hematological changes were observed. Mild histological changes occurred in the liver and thyroid of rats treated with CLP and diesel fuel aerosols. Based on the data presented, inhalation of CLP aerosols resulted in toxicological effects that were similar to those caused by dermal exposure.

Dermal toxicity of a medium-boiling (154-378 degrees C) coal liquefaction product in the rat--Part I

The subchronic dermal toxicity of a medium-boiling coal liquefaction product (CLP, 154-378 degrees C) was investigated in the rat. CLP was applied to the shaved backs of rats at dose levels of 50, 100, 200, or 400 mg/kg body weight.d, 7 d/wk for a period of 13 wk. Control groups received 0.4 ml/kg of normal saline. Signs of dermal irritation were observed at sites of application in males dosed at 200 and 400 mg/kg body weight and were characterized by thickened, focally necrotic and ulcerative skin. All animals survived the full length of the treatment period. Growth depression was observed in males at all dose levels, but no significant decrease in weight gain was observed in females. An increase in liver/body weight ratios was observed in all treatment groups of both sexes. The organ/body weight ratios for the spleen, heart, kidney, and brain were also increased in the upper dose groups of both sexes. Treatment with CLP caused a dose-dependent decrease in hemoglobin and packed cell volume in both sexes of all dose groups. The number of erythrocytes was decreased and that of neutrophils was increased in some CLP-treated groups of both sexes. There was a mild myeloid hyperplasia with increased myeloid/erythroid ratios in the 200- and 400-mg/kg groups of both sexes. Hepatic microsomal ethoxyresorufin deethylase activity was increased in all treatment groups of females, and in males dosed at 100 mg/kg and higher. In the renal tubules mild treatment-related histological changes occurred, which consisted of eosinophilic inclusions, increased cytoplasmic volume, and pyknosis. These changes were noted in the high-dose groups of both sexes. These data indicate that the medium-boiling CLP could produce systemic toxicity when applied dermally at 50 mg/kg body weight.d.

Toxicological response and its reversibility in rats fed Lake Ontario or Pacific coho salmon for 13 weeks

Lake Ontario coho salmon were known to contain a mixture of chemical contaminants. A previous study demonstrated that rats fed the Lake Ontario fish-supplemented diet for 28 days exhibited mild biochemical and histological changes. The purpose of the present study was to determine the effects due to a longer term of exposure and the reversibility of these effects. Growth rate and food consumption were not affected by feeding the animals with Lake Ontario or Pacific fish-supplemented diets for 13 weeks. No deaths were observed. Decreased spleen weights were observed in groups of males fed 1.45%, 5.8% Lake Ontario and 2.9% Pacific diet. After a 13 week recovery the spleen weights returned to normal. Decreased serum potassium was observed in male rats fed 2.9% Lake Ontario diet, and all levels of Pacific diet for 13 weeks, and was not evident following maintenance on normal diet. Serum glucose was not affected by the 13-week period of treatment, however; a reduction in this parameter occurred in male rats fed the two highest doses of Lake Ontario diet and all doses of Pacific diet following the 13-week recovery period. Minor hematological changes occurred only in the male rats fed either Lake Ontario or Pacific diet following a 13 week recovery period and included reduced marrow myeloid cells and myeloid/erythroid ratio. Hepatic microsomal ethoxyresorufin deethylase activity was significantly increased in rats ingesting Lake Ontario diet. Mild histological changes occurred in the liver and thyroid of the treated males, and in the liver and kidney of the treated females. These changes were attributed to the chemical residues and/or the fish diet. Data presented here indicated that the Lake Ontario fish-supplemented diet can cause mild biochemical, hematological and histological changes but most of these were reversible when exposure was terminated.

Toxicity of trichlorotoluene isomers: a 28-day feeding study in the rat

Groups of 10 male and 10 female rats were fed alpha,alpha,alpha-, alpha,2,6- or 2,3,6- trichlorotoluene (TCT) in their diet at 0, 0.5, 5.0, 50 or 500 ppm for 28 days. Growth rate and food consumption were not affected by treatment. No deaths occurred. Significant increases in liver weights were observed in male rats fed 5.0 and 500 ppm 2,3,6-TCT. Mild serum biochemical changes occurred in male rats. These included increased SDH activities in the groups fed 5.0 and 50 ppm alpha, alpha, alpha-TCT, and 5.0 ppm 2,3,6-TCT. Alpha, alpha, alpha-TCT at 500 ppm caused elevated LDH activities in male rats. Hepatic microsomal aminopyrine N-demethylase activities were increased in male rats fed 500 ppm alpha,2,6-TCT. Hematological parameters were not affected by treatment. Mild histological changes were seen in the liver, kidney and thyroid of treated rats. Data presented here suggest that alpha, alpha, alpha-, alpha,2,6- and 2,3,6-TCT possess a low order of oral toxicity in the rat.

Toxicity of 1,2,3,4-, 1,2,3,5- and 1,2,4,5-tetrachlorobenzene in the rat: results of a 90-day feeding study

Tetrachlorobenzenes (TCB) are industrial chemicals which have been used as intermediates for chemical synthesis and for electrical insulation. Recently TCB residues have been found in Great Lakes fish. The present study was designed to determine the subchronic toxicity of these compounds. Groups of 15 male and 15 female rats were fed diets containing 0, 0.5, 5.0, 50 or 500 ppm of each of 1,2,3,4-, 1,2,3,5- and 1,2,4,5-TCB for 13 weeks. Rats fed 500 ppm 1,2,4,5-TCB exhibited significant increases in liver and kidney weight. 1,2,4,5-TCB at the highest dose level caused a significant increase in serum cholesterol levels. Hepatic microsomal aminopyrine demethylase and aniline hydroxylase activities were induced by this compound at 50 and 500 ppm in the males, and 500 ppm in the females. Moderate to severe histological changes occurred in the liver and kidney of rats fed the three TCB isomers but the 1,2,4,5-isomer caused the most severe lesions. 1,2,4,5-TCB accumulated in fat and liver in a dose-dependent manner. Results indicate that 1,2,4,5-TCB is the most toxic isomer of the three and accumulates in liver and fat in a dose-dependent manner.

Comparative toxicity of 1,2,3,4-, 1,2,4,5-, and 1,2,3,5-tetrachlorobenzene in the rat: results of acute and subacute studies

Groups of 10 male and 10 female rats were dosed orally with 1,2,3,4-, 1,2,4,5-, or 1,2,3,5-tetrachlorobenzene (TCB) at levels that ranged from 200 to 4000 mg/kg, and were observed clinically for 14 d. LD50 values for 1,2,3,4-, 1,2,4,5-, and 1,2,3,5-TCB were found to be 1470, 3105, and 2297 mg/kg, respectively, in male rats. In females, the LD50 values were found to be 1167 and 1727 mg/kg for 1,2,3,4- and 1,2,3,5-TCB, respectively. Clinical signs of toxicity included depression, flaccid muscle tone, prostration, piloerection, loose stool, hypothermia, dacryorrhea, coma, and death. In a subacute study, groups of 10 males and 10 females were fed diets containing 0, 0.5, 5.0, 50, or 500 ppm 1,2,3,4-, 1,2,4,5-, or 1,2,3,5-TCB for 28 d. No deaths or clinical signs of toxicity were observed, and neither growth rate nor food consumption was affected. At 500 ppm, 1,2,4,5- but not 1,2,3,4- or 1,2,3,5-TCB caused a significant increase in the liver weight and serum cholesterol of male and female rats. Hepatic microsomal aniline hydroxylase and ethoxyresorufin deethylase were induced by 500 ppm 1,2,4,5-TCB. Hepatic microsomal aminopyrine demethylase activity was increased by the administration of this compound at 50 ppm and higher in males and at 500 ppm in the females. Rats fed 1,2,3,4- and 1,2,3,5-TCB at 500 ppm also showed a significant increase in aminopyrine demethylase activity. Moderate to severe histological changes were found in the liver, thyroid, kidney, and lungs of rats fed 500 ppm 1,2,4,5-TCB. Histological changes in the tissues produced by the administration of the 1,2,3,4- and 1,2,3,5-isomer were mild even at the highest dose levels. Tissue residue data showed that 1,2,4,5-TCB accumulated at much higher levels than the other two isomers. The results suggest that the position of chlorine substitution can affect the tissue accumulation and toxicity of chlorinated benzenes in rats.

A teratological assessment of four trihalomethanes in the rat

Four trihalomethanes were administered by gavage to Sprague-Dawley rats from day 6 to day 15 of gestation. Chloroform (Ch) was administered at levels of 100, 200 and 400 mg/kg and bromoform (Br), bromodichloromethane (BDCM) and chlorodibromomethane (CDBM) were administered at levels of 50, 100 or 200 mg/kg/day. A separate control was used for each compound. Maternal weight gain was depressed in all groups receiving Ch and at the highest dose levels of BDCM and CDBM. Ch administration caused decreased maternal hemoglobin and hematocrit values at all dose levels and also produced increased serum inorganic phosphorus and cholesterol at the highest dose. Liver enlargement was observed at all dose levels of Ch but in no other treatment groups. Evidence of a fetotoxic response was observed with Ch, CDBM and Br but not BDCM. No dose-related histopathological changes were observed in either mothers or fetuses as a result of treatment. None of the chemicals tested produced any teratogenic effects.

Acute and subacute toxicity of octachlorostyrene in the rat

This study was designed to investigate the acute and subacute toxicity of octachlorostyrene (OCS), a demonstrated environmental pollutant in fish from the Great Lakes and off the Norwegian coast in Europe. In an acute study, groups of 10 male rats were given by gavage single doses of OCS at 1300, 1690, 2190, 2850, or 3710 mg/kg and killed 14 d later. Octachlorostyrene at a dose of 1690 mg/kg and higher caused increased liver weight, increased hepatic microsomal aniline hydroxylase and aminopyrine demethylase activities, and increased serum cholesterol and uric acid levels. Only mild histological changes were seen in the thyroid of the treated animals. In a subacute study, groups of 10 male and female rats were fed diets containing 0.5, 5.0, 50 or 500 ppm OCS for 28 d. Growth rate and food consumption were not affected by treatment. Liver hypertrophy and hepatic microsomal enzyme induction were observed in animals fed 50 ppm OCS or higher. Elevations in serum cholesterol, total protein, potassium, and sorbitol dehydrogenase (SDH) occurred in rats fed the 500 ppm diet. Histological changes occurred in the liver and thyroid of rats exposed to as low as 5.0 ppm OCS. The OCS residues accumulated in the fat and liver in a dose-dependent manner. These data suggest that OCS can produce biochemical and histological changes in rats after administration of a single oral dose and/or when fed in the diet.

Toxicity of trihalomethanes: I. The acute and subacute toxicity of chloroform, bromodichloromethane, chlorodibromomethane and bromoform in rats

In an acute study, groups of 10 male and 10 female rats were given single oral doses of chloroform, bromodichloromethane (BDCM), chlorodibromomethane (CDBM), or bromoform and were observed for clinical symptoms for the following 14 days. Median lethal doses (LD 50) of the four trihalomethanes were found to be between 848 and 1388 mg/kg. Some groups which survived the treatment for 14 days showed reduced food intake, growth retardation and increased liver and kidney weight. Elevated serum cholesterol levels were observed in the surviving male rats treated with chloroform and CDBM, and in the females treated with chloroform. Decreased liver protein content occurred in male but not female rats fed chloroform and bromoform. In contrast, increase aniline hydroxylase activity was observed in female rats fed chloroform but not bromoform. Hematological values which were altered by the four trihalomethanes were hemoglobin, hematocrit, RBC, WBC, neutrophil and lymphocyte counts. Treatment-related histologic changes were observed in the liver and kidney of rats. These changes were qualitatively and quantitatively similar for the four trihalomethanes. These data indicate that trihalomethanes at large single oral doses can produce a wide range of toxic changes in the rat. In a subacute study, groups of 10 male rats were fed four trihalomethanes at 0, 5, 50 or 500 ppm in their drinking water for 28 days. The growth rate and food intake were not affected by treatment. A slight increase in relative kidney weight was observed in the groups fed 5 ppm chloroform; 500 ppm bromoform, 5 and 500 ppm BDCM. The animals fed the highest dose of chloroform showed decreased neutrophils. Serum biochemical parameters and hepatic microsomal enzyme activities were not altered by any of the four trihalomethanes. No histopathological changes were seen in the tissues examined.

Reversibility of the toxicological changes induced by photomirex and mirex

Photomirex (8-monohydromirex) is a known environmental contaminant. In a previous 28-day and 90-day study, photomirex was shown to cause a number of biochemical and histological alterations in male rats. The present study was undertaken to determine the reversibility of those changes and to compare both effects and reversibility with the present compound mirex. Male rats were fed diets containing 0, 0.05, 0.5, 5.0 and 50 ppm photomirex and 5 ppm or 50 ppm mirex for 28 days. Ten animals/group were killed at this time and the remainder placed on clean feed. Ten animals/group were killed after another 12, 24, and 48 weeks. The lower body weight gain in animals fed 50 ppm photomirex and 50 ppm mirex observed after 28 days on the test was not evidence after 12 weeks on the clean diet or thereafter. Reduced food consumption produced by these groups persisted for 12 weeks but not 24 weeks. Liver hypertrophy was observed in the 5.0-ppm and 50-ppm photomirex groups after 28 days and persisted in the highest dose group for 24 weeks on clean diet. Elevated serum sorbitol dehydrogenase activity was observed in the 50-ppm photomirex group and persisted for 12 weeks on clean diet. Histological changes in liver and thyroid were present up to 48 weeks on clean diet, whereas treatment-related testicular changes observed after 28 days were not evident after 12 weeks. Significant residues of photomirex were still evident in all tissues examined up to 48 weeks postexposure in the 50-ppm photomirex group. The data indicate that photomirex and mirex are extremely persistent compounds and can result in a variety of biochemical and histological changes long after exposure has ceased.

Ninety-day toxicity of photomirex in the male rat

Photomirex (8-monohydromirex) is a demonstrated environmental contaminant and was observed in previous short-term studies to produce lesions in the liver, thyroid and testes of male rats. The present study was undertaken to confirm those observations and to determine the effects after a longer period of exposure. Male rats were fed photomirex for 13 weeks at levels of 0.20, 1.0, 5.0, 25 and 125 ppm in the diet. Deaths were observed in animals receiving the highest dose. Decreased body weight gain and food intake were also observed in that group. Liver weights were increased at 5.0 ppm photomirex and higher. Photomirex caused changes in several biochemical parameters including serum sorbitol dehydrogenase and hepatic aniline hydroxylase activities. Dose-related histological abnormalities were observed in the thyroid and liver starting at the lowest dose level. These results confirm earlier findings and show that photomirex is a potent hepato- and thyrotoxin.