Chronic ethanol intake promotes double gluthatione S-transferase transforming growth factor-alpha-positive hepatocellular lesions in male Wistar rats

The chronic ethanol intake influence on the gluthatione S-transferase (GST-P) and transforming growth factor alpha (TGF-alpha) expression in remodeling/persistent preneoplastic lesions (PNLs) was evaluated in the resistant hepatocyte model. Male Wistar rats were allocated into five groups: G1, non-treated, fed water and chow ad libitum; G2, non-treated and pair-fed chow (restricted to match that of G3 group) and a maltodextrin (MD) solution in tap water (matched ethanol-derived calories); G3, fed 5% ethanol in drinking water and chow ad libitum; G4, diethylnitrosamine (DEN, 200 mg/kg, body weight) plus 200 parts per million of 2-acetylaminofluorene (2-AAF) for 3 weeks and pair-fed chow (restricted to match that of G5 group) and an MD solution in tap water (matched ethanol-derived calories); G5, DEN/2-AAF treatment, fed ethanol 5% and chow ad libitum. All animals were subjected to 70% partial hepatectomy at week 3 and sacrificed at weeks 12 or 22, respectively. Liver samples were collected for histological analysis or immunohistochemical expression of GST-P, TGF-alpha and proliferating cell nuclear antigen or zymography for matrix metalloproteinases-2 and -9. At the end of ethanol treatment, there was a significant increase in the percentage of liver area occupied by persistent GST-P-positive PNLs, the number of TGF-alpha-positive PNLs and the development of liver tumors in ethanol-fed and DEN/2-AAF-treated groups (G5 versus G4, P < 0.001). In addition, ethanol feeding led to a significant increase in cell proliferation mainly in remodeling and persistent PNLs with immunoreactivity for TGF-alpha at week 22 (P < 0.001). Gelatinase activities were not altered by ethanol treatment. The results demonstrated that ethanol enhances the selective growth of PNL with double expression of TGF-alpha and GST-P markers.

Antiulcerogenic effect and cytotoxic activity of semi-synthetic crotonin obtained from Croton cajucara Benth.

Trans-dehydrocrotonin, the major diterpene isolated from the bark of Croton cajucara, has good antiulcerogenic activity which, however, is accompanied by toxic effects. on the basis of these results, a semi-synthetic crotonin, named 4SRC, was prepared to determine whether this substance has similar antiulcerogenic activity with lower or no toxicity. The natural crotonin was also isolated from the bark of C. cajucara but was not used due to the small amount obtained. The cytotoxic effect of semi-synthetic crotonin, expressed as cell viability, was assessed in (a) lung fibroblast cell line (V79) derived from Chinese hamsters, a system commonly used for cytotoxicity studies, and (b) rat hepatocytes isolated from male Wistar rats. After treatment, cell viability was determined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide reduction (MTT reduction), total acid content and neutral red uptake assays. To evaluate V79 cell viability, different concentrations of semi-synthetic crotonin were incubated with the cells. To evaluate the antiulcerogenic effects of semi-synthetic crotonin (50, 100 and 200 mg/kg), we used the models of gastric ulcer induced by ethanol/HCl, stress, indomethacin/bethanechol, and ethanol in male Swiss mice and male Wistar rats. The substance had an IC50 = 500 muM in the neutral red uptake and MTT reduction tests and an IC50 = 200 muM in the nucleic acid content test. With regard to hepatocyte viability after treatment with semi-synthetic crotonin at different concentrations, semi-synthetic crotonin had an IC50 = 10-500 muM in the nucleic acid content and MTT reduction tests and an IC50 = 120 muM in the neutral red uptake test. In another experiment, V79 cells were incubated with the metabolites produced by hepatocytes treated with different concentrations of semi-synthetic crotonin. After a 4-h incubation, semi-synthetic crotonin had an IC50 = 500 muM in the MTT reduction and neutral red uptake tests and an IC50 = 370 muM in nucleic acid content test. The substance had significant antiulcerogenic activity in all models studied, suggesting the presence of a possible antisecretory effect combined with a cytoprotective effect. For this reason, the effect of semi-synthetic crotonin was also evaluated on biochemical parameters of gastric juice and gastric wall mucus, both obtained from pylorus-ligated mice. No significant differences were observed in these parameters between semi-synthetic crotonin-treated and control animals. The results obtained with semi-synthetic crotonin are promising, with a significant preventive effect against gastric ulcer induced by different agents. Our data also show that semi-synthetic crotonin was less toxic than dehydrocrotonin and that the cytotoxic effects decreases with the time that isolated hepatocytes were in culture. (C) 2003 Elsevier B.V. B.V. All rights reserved.

Cytotoxicity of fipronil on mice liver cells

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Liver dysfunction in patients bitten by Crotalus durissus terrificus (Laurenti, 1768) snakes in Botucatu (State of São Paulo, Brazil)

Os autores estudaram 32 doentes picados por serpentes venenosas, sendo 16 picados por Bothrops spp. e 16 por Crotalus durissus terrificus. Trinta doentes eram do sexo masculino e dois do feminino com idades variando entre 8 e 63 anos (méda 33±15). A prova da retenção da bromosulfaleína apresentou-se aumentada na maioria dos doentes picados por serpentes Crotalus durissus terrificus. Houve correlação positiva entre a retenção da bromosulfaleína e os níveis séricos de alanina aminotransferase e entre alanina e aspartato aminotransferase apenas nos doentes do grupo Crotalus. Um dos doentes evoluiu para o óbito e apresentou no exame anatomopatológico do fígado degeneração hidrópica e lesões mitocondriais. Os autores concluem que as alterações hepáticas são causadas por pelo menos dois mecanismos a saber: lesão mitocondrial por efeito do veneno crotálico; efeito das citoquinas, especialmente a interleucina-6.

Dose- and sex-related carcinogenesis by N-bis(2-hydroxypropyl)nitrosamine in Wistar rats

An initiation-promotion medium-term bioassay for detection of chemical carcinogens, developed in the male F344 rat, uses 0.1% N-bis(2-hydroxypropyl)nitrosamine (DHPN) among five genotoxic chemicals for the initiation of carcinogenesis in multiple organs. To establish this bioassay in the Wistar strain, the effects of two dose levels of DHPN were evaluated on the main DHPN rat target organs: lung, thyroid gland, kidneys and liver. Four groups of male and female animals were studied: Control--untreated group; Multi-organ initiated group (also referred to as DMBDD, based on the initials of the five initiators)-treated sequentially with N-diethylnitrosamine (DEN, i.p.), N-methyl-N-nitrosourea (MNU, i.p.), N-butyl-N-(4-hydroxy butyl)nitrosamine (BBN, drinking water), N, N'-dimethylhydrazine (DMH, s.c.) and DHPN (drinking water) for 4 weeks; a third group treated with 0.1% DHPN in drinking water for 2 weeks and the last group treated with 0.2% DHPN in drinking water for 4 weeks. The animals were sacrificed after 30 weeks. DHPN at 0.2% induced preneoplasia in the liver and kidneys of rats of both sexes, the number and area of the putative preneoplastic liver glutathione S-transferase-positive hepatocyte foci being significantly increased in these animals. It also induced benign and malignant tumors in female and in male rats. However, there was no relationship between the increased incidence of preneoplastic lesions and tumor development in the 0.2% DHPN-exposed groups of both sexes. DHPN at 0.1% induced only a few preneoplastic lesions in the liver and kidney and no tumors in both male and female rats. A clear dose and sex-related carcinogenic activity of DHPN was registered, although Wistar rats of both sexes showed a relative resistance to the carcinogenic activity of this compound.

The effects of ochratoxin/aluminosilicate interaction on the tissues and humoral immune response of broilers

This study aimed to evaluate the effect of dietary ochratoxin, in the presence or absence of aluminosilicate, on the histology of the bursa of Fabricius, liver and kidneys, and on the humoral immune response of broilers vaccinated against Newcastle disease virus. The exposure of birds to 2 p. p. m. ochratoxin, in the presence or absence of aluminosilicate, reduced their humoral immune response and the number of mitotic cells in the bursa. The relative weight of the livers of the birds exposed to this toxin was increased and, microscopically, there was hepatocyte vacuolation and megalocytosis with accompanying hyperplasia of the biliary epithelium. The kidneys showed hypertrophy of the renal proximal tubular epithelium, with thickening of the glomerular basement membrane. Aluminosilicate did not ameliorate the deleterious effects of the ochratoxin.

Squalene does not exhibit a chemopreventive activity and increases plasma cholesterol in a Wistar rat hepatocarcinogenesis model

The eventual chemopreventive effect of squalene (SQ), a triterpene present in olive oil, was evaluated when administered to Wistar rats during a period comprising the initiation and selection/promotion of the resistant hepatocyte (RH) model of hepatocarcinogenesis. During 8 consecutive wk, animals received by gavage SQ (100 or 150 mg/100 g body weight) dissolved in corn oil (CO) daily. Animals treated with only CO and submitted to the RH model were used as controls. Treatments with SQ did not result in inhibition of macroscopically visible hepatocyte nodules (P > 0.05) or of hepatic placental glutathione S-transferase-positive preneoplastic lesions (PNL; P > 0.05). Hepatic cell proliferation and apoptosis indexes were not different (P > 0.05) among the different experimental groups, both regarding PNL and surrounding normal tissue areas. There were no significant differences (P > 0.05) among comets presented by rats treated with the two SQ doses or with CO. on the other hand, SQ increased total plasma cholesterol levels when administered at both doses (P < 0.05). This indicates that the isoprenoid was absorbed. Thus, SQ did not present chemopreventive activity during hepatocarcinogenesis and had a hypercholesterolemic effect, suggesting caution when considering its use in chemoprevention of cancer.

Liver lesions produced by aflatoxins in Rana catesbeiana (bullfrog)

This study describes alterations induced in Rana catesbeiana (bullfrog) liver after extended dietary exposure to aflatoxins (AFs). Bullfrogs of both sexes were fed for 120 days a commercial chow blended with a rice bran-based mixture of Al's containing 667.0, 11.65, 141.74, and 3.53 mg/kg of AFs B1, B2, G1, and G2, respectively. Animals were sacrificed on study days 45, 90, and 120. Severe and progressive liver lesions with structural collapse, increased hepatocyte and biliary duct cell proliferation, appearance of basophilic hepatocytes, and diffuse scarring, were observed at all time points. There were no quantitative alterations in the liver melanomacrophage centers of the AFs-exposed animals. Increased amounts of lipid hydroperoxides, indicative of ongoing oxidative stress, were more evident in the Addutor magnum muscle than in the AFs-damaged livers. No tumors were found in the R. catesbeiana livers after 120 days of exposure to relatively high doses of AFs. (c) 2006 Elsevier B.V. All rights reserved.

Cytotoxicity of monocrotaline in isolated rat hepatocytes: Effects of dithiothreitol and fructose

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Foamy macrophages in the liver of cattle fed Brachiaria brizantha hay

Liver and lymph nodes injuries characterized by clusters of foamy macrophages, some of them containing birefringent crystals, were observed in cattle fed on Brachiaria brizantha hay. The cattle were from an experimental group poisoned with Senecio brasiliensis known to cause hepatic fibrosis and hepatocyte megalocytosis. One of the animals developed photosensitivity but the exact cause wasn't determined since both plants were fed. The foamy macrophages were present from the 30th d of feeding. Early appearance of these lesions may be particular to the animal specie used or due to the presence of both toxic plants.

Diferenciação hepatocítica de células-tronco mesenquimais da medula óssea humana

Some recent articles have reported that mesenchymal stem cells (MSCs) can be induced to express hepatocyte markers by transplanting them into animal models of liver damage, or by in vitro culture with growth factors and cytokines. In this study, the aim is to evaluate the behavior of MSCs subjected to induction of hepatocyte differentiation. The MSCs were isolated from the bone marrow of 4 normal donors, characterized and subjected to both in vitro and in vivo induction of hepatocyte differentiation. The in vitro induced cells showed morphological changes, acquiring hepatocyte-like features. However, the immunophenotype of these cells was not modified. The induced cells exhibited no increase in albumin, cytokeratin 18 or cytokeratin 19 transcripts, when analyzed by real-time RT-PCR. The expression of albumin, cytokeratin 18 and alpha fetoprotein was also unchanged, according to immunofluorescence tests. In vivo, the MSC demonstrated a potential to migrate to damaged liver tissue in immunodeficient mice. Taken together, the results suggest that bone marrow MSCs are incapable of in vitro differentiation into hepatocytes by the approach used here, but are capable of homing to damaged hepatic tissue in vivo, suggesting a role for them in the repair of the liver. This contribution to tissue repair could be associated with a paracrine effect exerted by these cells.

Avaliação morfométrica dos hepatócitos de ratos diabéticos tratados com neem (azadirachta indica a. juss) e estreptozootocina 6 ch

The effects of extracts from Azadirachta indica A. Juss and streptozotocin, in extreme high dilutions in dinamized systems, on hepatocyte morphometry of rats with diabetes mellitus induced by streptozotocin were evaluated. Some parameters presented significant differences among the experimental groups, but the effect of treatments to make better or worse the consequences of diabetes mellitus on liver was not detected using only the hepatocyte morphometry. The morphometric analysis evidenced that the white control group presented the highest mean values for nucleus and cytoplasm parameters, with the exception of the nuclear shape factor. However, this situation did not imply the diabetes mellitus was the cause of drastic reduction in these values, since the literature describes lower measurements for rats from the control group (non-diabetic rats).

Intoxicação experimental por Ipomoea asarifolia em ovinos: achados clínicos, laboratoriais e anatomopatológicos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Qualidade da água e histopatologia de órgãos de peixes provenientes de criatórios do município de Itapecuru Mirim, Maranhão

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Immediate graft histological assay, post pig's liver transplantation

PURPOSE: To describe the vascular and tissue histopathological changes in seven sequential experimental liver transplantations in pigs. METHODS: Fourteen female pigs, Sus domesticus species, with body mass between 5 and 8 kg were utilized. After the end of all anastomoses of the graft implantation in the receptor, the animal was monitored for 30 minutes, and at its end one of the biopsies was collected for histological analysis. The histological criteria utilized were: lytic hepatocyte necrosis, density of septal and portal inflammatory infiltrated, sinusoidal congestion and hemorrhage. The analysis was performed separately for the portal region in zone 1, 2 and 3. RESULTS: Among the structural changes undergone by the graft, those with greater frequency and intensity were vascular congestion and steatosis, which stood out in transplantations 5, 6 and 7. CONCLUSIONS: The technique demonstrated vascular alterations represented by vasocongestion, edema and minimum inflammatory reaction. In relation to the parenchyma, was observed macrovacuolar pan-acinar steatosis, focal lytic and occasional hemorrhages, beyond the accumulation of hemosiderin in Kuppfer's cells.