Experimental nutritional cirrhosis in the rat. Influence of choline, vitamin E, and dietary fat on triglyceride metabolism and the development of cirrhosis and ceroid.
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Oval cells and duct-like structures produced in the livers of rats fed N-2-fluorenylacetamide in a choline-devoid diet differ from bile ducts produced after feeding 4,4'-diaminodiphenylmethane. Rapid elevations of serum alpha-fetoprotein (AFP) occur after feeding N-2-fluorenylacetamide in a choline-devoid diet; no elevations of AFP are seen during 4,4'-diaminodiphenylmethane feeding. The duct-like structures associated with oval cells frequently contain AFP and albumin and are faintly delineated by laminin, whereas normal bile ducts and ducts induced by 4,4'-diaminodiphenylmethane do not contain AFP or albumin and are delineated by an intensely staining layer of laminin. Zones of oval cell proliferation label intensely for fibronectin, whereas zones of bile duct proliferation label much less intensely. It is concluded that the "tubuloform degeneration" seen after carcinogen exposure does not necessarily represent differentiation to true bile duct structures and that oval cells may neither derive from nor differentiate into bile ducts. Oval cells have characteristics more like fetal hepatocytes than ductular cells and may represent a "stem cell"-like population with potential for loss of growth control and malignant transformation.
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Feeding of choline-devoid (CD) diet and dietary administration of phenobarbital (PHB) are efficient promoters of liver carcinogenesis in the rat. Furthermore, inclusion of PHB in a CD diet results in a synergistic effect, inasmuch as the promoting action of their combination is greater than the sum of those exerted by either agent alone. To investigate the mechanism(s) of action of the two promoters, liver DNA synthesis and liver cell proliferation were studied in rats fed a CD diet, a choline-supplemented diet, or the same diets to which 0.06% PHB was added. DNA synthesis was determined by [3H]thymidine incorporation into DNA and autoradiography, and cell proliferation was determined by mitosis counts. Feeding the CD diet caused an increase of both DBA synthesis and cell proliferation over those present in rats fed the choline-supplemented diet. Inclusion of PHB in the CD diet, on the other hand, inhibited DNA synthesis and cell proliferation. These results indicate that stimulation of cell proliferation per se may not be a sufficient condition for an agent to act as a promoter of liver carcinogenesis.
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1. A bioassay for acetylcholine (Ach), with a sensitivity of 0.1 picomoles in 30 microliters (microliter) (Fig. 3), was developed using the powerful musculature of the common leech (Haemopis sanguisuga). 2. Ach was extracted from a pool of ganglia with sodium tetraphenylborate in 3-heptanone and analysed using gas chromatography. The chromatograph confirmed that the "Ach like effect" measured with bioassay was due to acetylcholine and not to one of its derivatives (Fig. 5 and 6). 3. An incubation chamber for perfusing the isolated superior cervical ganglion of the rat is described, with which it is possible to do electrophysiological experiments and to sample the Ach lost or released by the ganglion (Fig. 2). 4. Using this system, the results obtained from the resting or stimulated rat ganglion incubation in-vitro, were similar to those obtained with the cat ganglion perifused in situ. 5. Experiments were also performed to investigate the effect of removing the two precursors of Ach, glucose (Table I) and choline (Fig. 9), from the incubation medium.
An electron microscopic, immunocytochemical, and enzyme cytochemical analysis of the previously established oval cell lines OC/CDE 6 and OC/CDE 22 was performed to characterize the phenotype and differentiation patterns of long-term cultures of oval cells. It was found that alpha-fetoprotein, albumin, and cytokeratin 19 are present in all cultured cells. This indicates that oval cells constitute a population of immature cells expressing features of the antigenic phenotype of both the hepatocyte and bile ductular cell lineages. An electron microscopic examination revealed a gradual alteration in the ultrastructure of oval cells toward hepatocyte-like cells. The majority of the oval cells were positive for glucose-6-phosphatase activity. A particularly striking observation was that oval cells were heterogeneous in terms of peroxisome content. Only about 50% of the oval cells had peroxisomes in the cytoplasm, these cells probably being part of the hepatocyte lineage. The other cultured cells did not reveal catalase activity and probably represented cells committed to the bile ductular cell lineage. An addition of clofibrate to the culture medium resulted in a marked peroxisome proliferation in all oval cells, indicating that oval cells might be able to change their differentiation pathway depending on environmental influence toward the hepatocyte lineage. It is most intriguing that in oval cells with abundant cytoplasm peroxisome proliferation was accompanied by proliferation of the smooth endoplasmic reticulum (this is a morphological marker of mature hepatocytes). Taken together, our findings suggest that within the oval cell lines OC/CDE 6 and OC/CDE 22 cells undergoing a morphological and functional differentiation along the hepatocyte and bile ductular cell lineages are present.
OBJECTIVE: To assess the effect of four regimens of antibiotics (compared with a control regimen of distilled water) given orally on gut decontamination, bacterial translocation, and mortality in acute necrotising pancreatitis in mice. DESIGN: Randomised experimental study. SETTING: University hospitals, USA and Italy. MATERIALS: 150 young Swiss Webster mice. INTERVENTION: All mice were fed a diet deficient in choline and supplemented with ethionine. They were then randomised to be given by gavage (36 hours after starting the diet): distilled water (controls, group 1); aztreonam along (group 2); neomycin, erythromycin, metronidazole (group 3); polymyxin B and amikacin (group 4); polymyxin B, amikacin, amphotericin B (group 5). 20 Mice in each group were treated for 10 days, and the remaining 10 in each group were killed after 3 days. MAIN OUTCOME MEASURES: Survival, and qualitative and quantitative cultures of the liver, lungs, pancreas and caecum. RESULTS: The best survival rate during the first 7 days was in group 5, but by day 10 there was no difference among the groups. All the antibiotic regimens reduced the number of bacteria in the caecum and all but aztreonam alone (group 2) reduced the rate of translocation of both Gram negative and Gram positive bacteria to all organs studied. Translocation of yeast occurred in those animals in groups 2, 3, and 4 in which there was overgrowth of fungi in the caecum. CONCLUSION: Gram negative and Gram positive organisms and fungi may have an important role in infective morbidity and mortality in acute pancreatitis, and selective decontamination with polymyxin B, amikacin, amphotericin B reduced the incidence of translocation related infections and early mortality in mice with acute necrotising pancreatitis.
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In an attempt to clarify the role of oval cells in the emergence of hepatocellular carcinoma, we fed rats a choline-free diet containing 0%, 0.05% or 0.1% ethionine. The incidence and nature of premalignant and malignant hepatic lesions were then related to the degree of oval cell proliferation. Intake of choline-free diet alone for up to 12 mo was associated with minimal oval cell proliferation; cholangiofibrosis, hepatocellular nodules and hepatocellular carcinoma were observed in 55%, 23% and 14% of the animals, respectively. When rats were given the choline-free diet with 0.05% ethionine, proliferation of oval cells was more pronounced; after a 6- to 12 mo feeding period, cholangiofibrosis (57%) was again observed. However, hepatocellular nodules (91%) and hepatocellular carcinoma (74%) were the most common lesions seen with this feeding regimen. Finally, rats fed the choline-free diet with 0.1% ethionine had massive oval cell proliferation and progressive loss of parenchymal liver tissue. Most of these animals died before they had consumed the choline-free diet with 0.1% ethionine for 12 mo. Rats in this group (96%) exhibited large and numerous cholangiofibrotic lesions, but hepatocellular nodules and carcinoma were not detected. In all animals of each experimental group, hyperplastic bile duct cells in areas of cholangiofibrosis and oval cells were positive for cytokeratin 19, an intermediate filament protein present only in bile duct cells in normal liver. Hepatocellular nodules and hepatocellular carcinoma were invariably negative for cytokeratin 19. We interpret these findings to suggest that oval cells are not involved in the histogenesis of hepatocellular carcinoma.(ABSTRACT TRUNCATED AT 250 WORDS)
Apolipoprotein B (apo B) synthesis in fatty liver was described in this review. Apo B synthesis has not been intensively studied in fatty liver. Recently, we demonstrated that hepatic apo B mRNA level increased in two experimental models of fatty liver. Davidson et al. reported that apo B mRNA editing was enhanced in fatty liver induced by refeeding after fasting. However, further investigation is needed to clarify whether alteration in apo B gene regulation participates in development of fatty liver.
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