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PubMedDate not supplied

Oxidative stress in the pathogenesis of nonalcoholic fatty liver disease, in rats fed with a choline-deficient diet.

BACKGROUND/AIM: The pathogenesis of Nonalcoholic Fatty Liver Disease remains largely unknown, but oxidative stress seems to be involved. The aim of this study was to evaluate the role of oxidative stress in experimental hepatic steatosis induced by a choline-deficient diet. METHODS: Fatty liver disease was induced in Wistar rats by a choline-deficient diet. The animals were randomized into three groups: I (G1) and II (G2), n=6 each--fed with a choline-deficient diet for four and twelve weeks respectively; Group III (control-G3; n=6)--fed with a standard diet for twelve weeks. Samples of plasma and liver were submitted to biochemical, histological and oxidative stress analysis. Variables measured included serum levels of aminotransferases (AST, ALT), cholesterol and triglycerides. Oxidative stress was measured by lucigenin-enhanced luminescence and the concentration of hydroperoxides (CE-OOH-cholesteryl ester) in the liver tissue. RESULTS: We observed moderate macro- and microvesicular fatty change in periportal zones G1 and G2 as compared to controls (G3). In G2, fatty change was more severe. The inflammatory infiltrate was scanty and no fibrosis was seen in any group. There was a significant increase of AST and triglycerides in G1 and G2 as compared to control group G3. The lucigenin-amplified luminescence (cpm/mg/min x 10(3)) was significantly increased in G1 (1393-/+790) and G2 (7191-/+500) as compared to controls (513-/+170), p<0.05. The concentrations of CE-OOH were higher in G1 (5.7-/+0.9 nmol/mg protein) as compared to control (2.6-/+0.7 nmol/mg protein), p<0.05. CONCLUSION: 1) Oxidative stress was found to be increased in experimental liver steatosis; 2) The production of reactive oxygen species was accentuated when liver steatosis was more severe; 3) The alterations produced by oxidative stress could be an important step in the pathogenesis of nonalcoholic fatty liver disease.

Alanine Transaminase↗
PubMed1964

INFLUENCE OF NEOMYCIN AND INGESTED ENDOTOXIN IN THE PATHOGENESIS OF CHOLINE DEFICIENCY CIRRHOSIS IN THE ADULT RAT.

Two groups of adult rats fed a choline-deficient diet supplemented with neomycin in their drinking water for 250 or 350 days were protected against the development of liver fibrosis and cirrhosis. At the termination of the study these animals weighed more than others not receiving neomycin. This difference in weight did not appear to be caused by a growth-promoting effect of neomycin but rather reflected the increased severity of liver disease and a resultant weight loss in animals not receiving neomycin. Protection by neomycin was cancelled when Salmonella typhosa endotoxin was added to the drinking water. It was concluded that the protective effect of neomycin was mediated by an alteration in the intestinal microflora resulting in a reduction in the numbers of organisms contributing to intraluminal endotoxin. In the presence of choline deficiency, absorption of intraluminal endotoxin may contribute to the development of fibrosis and cirrhosis.

Animals↗
PubMed1987

Comparative effects of choline chloride and phosphatidylcholine on plasma and liver lipid levels in rats fed a choline-deficient high cholesterol diet.

The effects of dietary choline chloride and phosphatidylcholine (PC) on plasma and liver lipid levels were investigated with rats fed a choline-deficient high cholesterol diet. The plasma cholesterol level significantly increased as the dietary level of choline chloride was increased. The addition of PC to the choline-free diet also resulted in an increase in the plasma cholesterol level, but the magnitude of the increase was significantly lower than that by choline chloride. There was no difference, on the other hand, in the effect of choline chloride and PC on the plasma triglyceride level. The contents of cholesterol and triglyceride in the liver markedly decreased in rats fed a diet containing PC at a high level. The fecal excretion of neutral sterol significantly increased by the addition of PC at a high level, but not at a low level. The results indicate that the plasma cholesterol level, but not triglyceride, is differentially influenced by dietary choline chloride and PC, and that PC has both hyper- and antihypercholesterolemic effects when compared with a choline-free diet and a diet supplemented with choline chloride, respectively.

Animals↗
PubMed1977

Influence of dietary fat on fatty livers of choline-deficient rats.

Our purpose was to evaluate the influence of type of dietary fat on nature and severity of liver lipid changes induced in male weanling rats by low choline diets. Beef tallow, a blend of tallow and safflower oil (SO) each provided 48% of total energy value of a control diet and a low choline diet. Livers from choline-deficient rats fed tallow, blend, or SO diets contained approximately 4.5, 5, and 2.5 times as much lipid, respectively, as livers from corresponding control groups. Liver lipids from rats fed SO diets as compared with those from rats fed tallow diets contained lower percentages of saturated and monounsaturated fatty acids, and higher percentages of polyunsaturated fatty acids. Values for groups fed blend diets were intermediate, except for 18:0 and 20:4 in the control group. Choline deficiency resulted in significant increases in proportions of the predominant fatty acid(s) of the dietary fat in liver lipids (but not in fat pad lipids) at the expense of 18:0 and 20:4. Ratios of 16:0 to 18:0 in both liver and fat pad lipids were greater in choline-deficient than in corresponding control groups, probably reflecting greater fatty acid synthesis.

Animals↗
PubMedDate not supplied

[Vitamin B 12 metabolism and the status of sulfhydryl groups in protein-choline deficiency in rats. Effects of methyl- and adenosylcobalamins].

The effect of low protein choline-deficient diet on total vitamin B12 content and individual cobalamin level in the blood serum and liver of rats was determined. Moreover the total and non-protein SH-group content and glutathione transferase activity in the liver of rats were studied. Total cobalamin content increased in the blood serum, but it did not change in the liver of rats fed choline-deficient low protein diet. Total and non-protein SH-group level as well as glutathione transferase activity in the liver decreased significantly. The causes of changes revealed are discussed. Methylcobalamin (but not adenosylcobalamin) administration normalized individual cobalamin level in the blood serum. Administration of both methylcobalamin and adenosyl-cobalamin resulted in total SH-group content restoration whereas non-protein SH-group level and glutathione transferase activity were restored only in methylcobalamin-treated rats.

Animals↗
PubMedDate not supplied

Choline deficiency causes reversible hepatic abnormalities in patients receiving parenteral nutrition: proof of a human choline requirement: a placebo-controlled trial.

BACKGROUND: Previous studies have shown that plasma free choline concentrations are significantly decreased in many long-term home total parenteral nutrition (TPN) patients. Furthermore, low choline status has been associated with both hepatic morphologic and hepatic aminotransferase abnormalities. A preliminary pilot study suggested choline-supplemented TPN may be useful in reversal of these hepatic abnormalities. METHODS: Fifteen patients (10 M, 5 F) who had required TPN for > or =80% of their nutritional needs were randomized to receive their usual TPN (n = 8), or TPN to which 2 g choline chloride had been added (n = 7) for 24 weeks. Baseline demographic data were similar between groups. Patients had CT scans of the liver and spleen, and blood for plasma free and phospholipid-bound choline, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, gamma glutamyl transferase (GGT), bilirubin, serum lipids, complete blood count (CBC), and chemistry profile obtained at baseline, and weeks 2, 4, 6, 12, 16, 20, 24, and 34. CT scans were analyzed for Hounsfield unit (HU) densities. RESULTS: There were no significant differences in any measured parameters after 2 weeks. However, at 4 weeks, a significant difference in liver HU between groups was observed (13.3+/-5.0 HU [choline] vs 5.8+/-5.2 HU [placebo], p = .04). This significant trend continued through week 24. Recurrent hepatic steatosis and decreased HU were observed at week 34, 10 weeks after choline supplementation had been discontinued. A significant increase in the liver-spleen differential HU was also observed in the choline group (10.6+/-6.2 HU [choline] vs 1.3+/-3.3 HU [placebo], p = .01). Serum ALT decreased significantly (p = .01 to .05) in the choline group vs placebo at weeks 6,12, 20, and 24. Serum AST was significantly decreased in the choline group by week 24 (p = .02). The serum alkaline phosphatase was significantly reduced in the choline group at weeks 2, 12, 20, 24, and 34 (p = .02 to 0.07). Total bilirubin was normal in these patients and remained unchanged during the study. Serum GGT tended to decrease more in the choline group, but the greater decrease was not statistically significant. CONCLUSIONS: Choline deficiency is a significant contributor to the development of TPN-associated liver disease. The data suggest choline is a required nutrient for long-term home TPN patients.

Adult↗
PubMed1978

Immunological studies on CTP:phosphocholine cytidylyltransferase from the livers of normal and choline-deficient rats.

Chickens were immunized with the purified low-molecular-weight form of CTP:phosphocholine cytidylyltransferase from rat liver cytosol. The antiserum was obtained and fractionated to yield immunoglobulin. The antibodies specifically inhibited the enzymatic activity of the partially purified low-molecular-weight form of the enzyme from pH 6.0 to 8.5. Antibodies against the low-molecular-weight form of the enzyme cross-reacted with the high-molecular-weight form of the enzyme from cytosol as well as with the cytidylyltransferase associated with the microsomal fraction. The antibodies were used for the immunochemical determination of the amount of cytosolic phosphocholine cytidylyltransferase in the livers of normal and choline-deficient rats. The amount of enzyme in rat liver cytosol was not changed for at least 18 days of choline deficiency. The decrease in specific activity of the enzyme in choline-deficiency may be caused by factors other than adaptive changes in the level of enzyme.

Animals↗
PubMed1993

Phosphatidylcholine peroxidation and liver cancer in mice fed a choline-deficient diet with ethionine.

A high incidence of hepatocellular carcinoma (HCC) was observed in mice fed a choline-deficient diet containing 0.1% ethionine (CDE) for 19 months. HCC was present in 85% of CDE mice and in 22% of choline-deficient (CD) mice not receiving ethionine. This strong hepatocarcinogenicity of the CDE diet was concomitant with a severe decrease in plasma and liver alpha-tocopherol (Toc) to 60 and 35%, respectively, of those contained in choline-supplemented (CS) control mice. We previously found that this dietary-induced HCC was preceded at 4-week feeding by a depletion of Toc and a remarkable increase of phosphatidylcholine hydroperoxide (PCOOH) in the livers of CDE mice. When HCC was prominent in CDE mice, PCOOH was still elevated. Mouse glutathione S-transferase (GST) M II isozyme, which is related to rat GST-P form, a positive marker for rat hepatic preneoplastic and neoplastic lesions, revealed an inverse histochemical pattern as that seen in rats (i.e., the HCC lesions tended to decreased staining). The aforementioned results taken together indicate that decreases in Toc and enhanced PC peroxidation are important events in CDE-induced mice liver tumors.

Animals↗
PubMed1995

Choline deficiency: a cause of hepatic steatosis during parenteral nutrition that can be reversed with intravenous choline supplementation.

Patients receiving long-term total parenteral nutrition (TPN) develop hepatic steatosis as a complication. Our previous studies have shown this to be caused, at least in part, by choline deficiency. We studied four patients (1 man, 3 women) aged 50 +/- 13 years who had low plasma-free choline concentrations 4.8 +/- 1.7 (normal, 11.4 +/- 3.7 nmol/mL). The patients had received TPN for 9.7 +/- 4.7 years. They received parenteral nutrition solutions containing choline chloride (1 to 4 g/d) for 6 weeks. Abdominal computed tomography (CT) was performed at baseline, biweekly during the choline supplementation, and 4 weeks after discontinuation of choline. During choline administration, the plasma-free choline concentration increased into the normal range within 1 week in all four patients and remained at or above the normal range for all 6 weeks, but decreased back to baseline when choline supplementation was discontinued. Hepatic steatosis resolved completely, as estimated by CT. Liver density increased from -14.2 +/- 22.3 Hounsfield units (HU) to 8.4 +/- 10.3 HU at week 2 (P = .002); 9.6 +/- 10.7 HU at week 4 and 13.1 +/- 7.3 HU at week 6, as determined by the liver-spleen CT number difference obtained by the subtraction of the average spleen CT number (in HU) from the average liver CT number. This improvement continued up to 4 weeks after choline supplementation (13.8 +/- 2.8 HU). Hepatic steatosis was shown to have recurred in one patient after 10 weeks of return to choline-free parenteral nutrition. The hepatic steatosis associated with parenteral nutrition can be ameliorated, and possibly prevented, with choline supplementation. Therefore, choline may be an essential nutrient for patients who require long-term parenteral nutrition.

Adult↗
PubMed1998

Choline deficiency induces apoptosis and decreases the number of eosinophilic preneoplastic foci in the liver of OXYS rats.

Choline deficiency (CD) was previously shown to trigger apoptosis in rat hepatocytes in culture and in vivo. In the present study we investigated the effects of short-term withdrawal of choline from the diet on the expression of putative preneoplastic foci in OXYS rats, an inbred strain with an inherited overproduction of free radicals. Animals were fed a defined, choline-sufficient (CS, control) or choline-deficient (CD) diet for 6 weeks. Eosinophilic, glutathione S-transferase (pi class) (+) preneoplastic foci were found in histologic sections of control OXYS rat liver. CD caused a 60% decrease in the number of eosinophilic foci per liver section (27.0+/-6.1 vs. 10.6+/-4.6 foci/section) compared to CS controls. Apoptotic bodies were detected in 0.18+/-0.03% of hepatocytes in CD livers compared to 0.05+/-0.009% of hepatocytes in controls. Cells which exhibited an apoptotic morphology in hematoxylin and eosin-stained sections were TUNEL-positive, confirming the induction of apoptosis. Also in CD animals compared to controls, there was an increased expression of p27Kip1 protein, and a reduction in PCNA nuclear labeling and the number of mitotic figures, consistent with an inhibition of cell proliferation in the livers of CD animals. This study shows that the liver of OXYS rats with an inherited overgeneration of free radicals retains sensitivity to CD, and that this p53-independent trigger of apoptosis can decrease the number of eosinophilic foci in the livers of these animals.

Animals↗
PubMed2006

Roles of phosphatidylinositol 3-kinase and osteopontin in steatosis and aminotransferase release by hepatocytes treated with methionine-choline-deficient medium.

Feeding mice a methionine and choline-deficient (MCD) diet serves as an experimental animal model for nonalcoholic steatohepatitis (NASH). In the present study we examined the effect of exposing AML-12 hepatocytes to MCD culture medium in regard to mechanisms of steatosis and alanine amino-transferase (ALT) release. Cells exposed to MCD medium developed significant and progressive steatosis from 6 to 24 h and also had significantly increased loss of ALT into the medium at 18 and 24 hours of incubation. No increased oxidative injury or cell death was observed. Osteopontin (OPN) mRNA in cells and protein expression in medium were significantly increased during 6-24 hours of incubation. MCD medium treatment also resulted in activation of PI3-kinase by 30 minutes and its downstream target p-Akt within 1hour of incubation. Steatosis was associated with increased expression of microsomal triglyceride transfer protein (MTTP) mRNA and increased ALT release with over expression of ALT mRNA, all of which were completely prevented by inhibition of PI3-kinase (LY294002). Blocking OPN signaling by treating with anti-OPN or anti-beta3-integrin antibody prevented the increased ALT release while only partially prevented the increased ALT mRNA expression, but had no effect on either steatosis or MTTP expression. In conclusion, incubation of cultured hepatocytes with MCD medium results in cellular steatosis and OPN dependent ALT release. PI3-kinase plays a central role in signaling the MCD medium-induced steatosis and increased OPN expression, whereas OPN appears to play a role in signaling hepatocyte ALT release but not steatosis.

Animals↗
PubMed1985

Effects of the irreversible ornithine decarboxylase inhibitor, alpha-difluoromethylornithine, aflatoxin B1, and choline deficiency on hepatocarcinogenesis.

Liver carcinogenesis was induced in rats by aflatoxin B1 (AFB1) enhanced by a choline-deficient diet. In Experiment 1, the ornithine decarboxylase inhibitor, alpha-difluoromethylornithine (DFMO), was administered by gavage to one group only during AFB1 administration; another group received DFMO during AFB1 administration and for 2 months after carcinogen administration. These two groups were compared to two control groups, one given AFB1 and fed the choline-deficient diet and another fed the deficient diet only. In a second experiment, DFMO was administered at a concentration of 2% in the water for 3 weeks and then at 1% for the remainder of the study. Rats from each group in Experiment 1 were killed at 2, 8, and 10 months after AFB1 administration and the development of tumors was followed by histology; autoradiography of [3H]thymidine incorporation into DNA; enzyme histochemistry; and alpha-fetoprotein determination. The group given DFMO during AFB1 administration was not significantly different from the AFB1-treated control group at 2 and 8 months after AFB1 administration. However, at 10 months following AFB1 and DFMO administration, the [3H]thymidine-labeling index and glucose-6-phosphatase staining were significantly increased. This group had three animals bearing hepatocellular carcinomas as compared to none in the controls. The group given DFMO for 2 months after AFB1 administration had a significantly depressed growth rate 2 months later, but this difference was not apparent after 8 months. After 10 months, there was a significantly increased [3H] thymidine-labeling index and increased volume fraction of gamma-glutamyltranspeptidase in the AFB1-DFMO-treated group as compared to the controls. DFMO appeared to inhibit growth under some conditions, but if administration was discontinued after AFB1 exposure, it appeared to enhance tumorigenesis. In Experiment 2, where a larger dose of AFB1 was used and DFMO was administered in the water from start to finish of the experiment, DFMO inhibited tumor induction and depressed the appearance of markers examined during carcinogenesis. These data indicate that the regimen used for DFMO administration can markedly affect tumor induction.

Aflatoxin B1↗
PubMed1997

Choline deficiency causes increased localization of transforming growth factor-beta1 signaling proteins and apoptosis in the rat liver.

Dietary restriction is known to decrease cell proliferation and increase apoptosis in the liver; however, the role of withdrawal of single dietary factors on cells of the liver is less well understood. In this study, we investigated the effects of short-term choline deficiency (CD; also for choline deficient) on cell survival, proliferation and the expression of proteins related to the transforming growth factor-beta1 (TGF-beta1) growth-inhibitory signaling pathway in the liver. In animals fed a CD diet for 6 weeks, classical apoptotic bodies were detected in 0.28 +/- 0.04% of hepatocytes in CD livers compared to 0.096 +/- 0.006% of hepatocytes in control rats fed a choline-sufficient (CS) diet. These classical apoptotic cells exhibited DNA fragmentation when probed with an in situ end-labeling immunohistochemical method; TUNEL-positive nuclei were also seen in hepatocytes in CD livers which had accumulated large amounts of lipid, consistent with the known DNA-damaging effects of CD. In CS control livers, TGF-beta1 protein was found only in bile duct epithelium and nonparenchymal-type cells, and not in hepatocytes. However, the majority of hepatocytes in the CD liver expressed high levels of TGF-beta1 protein, as well as TGF-beta1 receptor types I and II. Nuclear localization of p27Kip1 protein, which may link TGF-beta1 expression to apoptosis, showed a 10-fold increase in CD hepatocytes (4.1 +/- 1.1 vs. 0.35 +/- 0.04% of cells) compared to controls. In addition, there was a 5-fold increase (0.54 +/- 0.031 vs. 0.011 +/- 0.007% of cells) in the mitotic index in CD-compared control livers. We conclude that feeding a CD diet for 6 weeks induces apoptosis in hepatocytes in the whole rat liver and that this form of cell death appears to be mediated, in part, by TGF-beta1 and related proteins.

Activin Receptors, Type I↗
PubMed1995

Nicotinamide megadosing increases hepatic poly(ADP-ribose) levels in choline-deficient rats.

Previous work in our laboratory has shown that dietary megadoses of nicotinamide, used in the prevention of diabetes, cause increases in hepatic poly(ADP-ribose). Poly(ADP-ribose) is synthesized from NAD+ by a nuclear enzyme, poly(ADP-ribose)polymerase, which is activated by DNA strand breaks. The nicotinamide-induced increase in poly(ADP-ribose) could result from an increase in substrate, NAD+, or the induction of strand breaks in DNA. Strand breaks may result from the depletion of single carbon groups, through the excretion of methylated derivatives of nicotinamide. To differentiate between these mechanisms, a 3 x 3 factorial experiment was conducted in which rats were fed diets containing various supplements of choline bitartrate (0, 2, 20 g/kg diet) and nicotinamide (0, 1, 2 g/kg diet). At the conclusion of treatments, blood NAD+ and liver lipid, NAD+ and poly(ADP-ribose) levels were determined. Choline deficiency caused the characteristic accumulation of fat in the liver at all levels of nicotinamide. In choline deficient rats, nicotinamide supplements further increased liver lipid concentration. Blood and liver NAD+ concentrations were increased by nicotinamide supplementation, irrespective of choline status. In contrast, liver poly(ADP-ribose) levels were increased by nicotinamide supplementation only in choline deficient rats. These results show that nicotinamide-induced increases in poly(ADP-ribose) levels appear to be dependent on decreased methyl donor status and suggest that adequate choline status is important for preventing some deleterious effects of nicotinamide treatment.

Animal Nutritional Physiological Phenomena↗
PubMed1952

Protection against fatal renal injury due to choline deficiency by renal decapsulation.

Decapsulation of the left kidney through a lumbar incision immediately prior to placing young rats on a choline-deficient diet afforded a significant degree of protection against animal mortality, compared with that which occurred as a result of the deficiency in the control groups. Decapsulation also was effective in reducing greatly the renal injury which developed in the decapsulated kidneys, as judged by a comparison of the decapsulated kidneys with the contralateral undecapsulated kidneys of the same animals. Decapsulation through an abdominal incision also was efficacious. Decapsulation after 4 or 5 days on the deficient diet, at which time relatively early renal lesions were present in most of the animals, afforded little if any protection. Experiments in which the usual adhesions between the decapsulated kidneys and surrounding tissues were prevented by covering the decapsulated kidneys with artificial capsules demonstrated that protection due to decapsulation could occur in the absence of adhesions. Renal denervation without removal of the renal capsule was not associated with a decrease in renal damage or animal mortality. Possible mechanisms of the protective effect of renal decapsulation in choline deficiency are discussed.

Animals↗
PubMed1986

Choline deficiency and chemical carcinogenesis.

We have reviewed the current status of our knowledge concerning the biologic effects of dietary choline (lipotrope) deficiency in modifying chemical carcinogenesis in experimental animals and discussed its possible mechanisms. Choline deficiency produces various pathologic lesions, involving virtually every organ of the body, as a result of a decrease in phospholipid and acetylcholine synthesis and in the supply of labile methyl groups. The liver is the only organ in which a relationship has been consistently demonstrated between choline deficiency and chemically induced tumors. The deficient diet enhances the initiating potency of several carcinogens and acts as a strong cocarcinogen. Diet also exerts a strong promoting effect, though the possibility that it is a complete carcinogen cannot be ruled out. Phase I enzymes of the carcinogen metabolizing system are uniformly depressed by choline deficiency, but very little information is available regarding the effects of diet on Phase II enzymes that detoxify carcinogen metabolites. Possible modifications of carcinogen-induced DNA damage and their repair processes have not been adequately scrutinized. Solid evidence suggests that feeding a choline-deficient diet leads to enhanced liver cell proliferation, an inadequate supply of methyl groups for transmethylation reactions, and membrane lipid peroxidation. Induced cell proliferation and hypomethylation of DNA may alter the state of gene expression, including that of specific cellular oncogenes. Lipid peroxidation may alter the structure and function of membrane receptors related to liver cell growth or may directly damage cellular DNA. Thus these alterations, individually or in combination, could play a critical role in the diet-induced modification of chemical carcinogenesis.

Animals↗
PubMed1996

Choline deficiency induces apoptosis in SV40-immortalized CWSV-1 rat hepatocytes in culture.

Immortalized CWSV-1 rat hepatocytes, in which p53 protein is inactivated by SV40 large T antigen, had increased numbers of cells with strand breaks in genomic DNA (terminal dUTP end labeling) when grown in 0 Micron choline (67-73% of cells) than when grown in 70 Micron choline (2-3% of cells). Internucleosomal fragmentation of DNA (DNA ladders) was detected in cells grown with 5 Micron and 0 Micron choline for 72h. Cells treated with 0 or 5 Micron choline for 72h detached from the substrate in high numbers (58% of choline deficient cells vs. 1.4% of choline sufficient cells detached) exhibited a high incidence of apoptosis (apoptotic bodies were seen in 55-75% of cells; 67-73% had DNA strand breaks), and an absence of mitosis and proliferating cell nuclear antigen (PCNA) expression. Cells undergoing DNA fragmentation had functioning mitochondria. At 24h, cells grown in 0 or 5 Micron choline synthesize DNA more rapidly than those grown in 70 Micron choline. By 72h, the cells grown in 0 or 5 Micron choline were forming DNA much more slowly than control cells (assessed by thymidine incorporation, PCNA expression, and mitotic index). Western blot analysis showed that p53 in the nucleus of cells was detected in direct association with SV40 T-antigen, and was therefore likely to be inactive. We conclude that choline deficiency kills CWSV-1 hepatocytes in culture by inducing apoptosis via what may be a p53-independent process, and that this process begins in viable cells before they detach from the culture dish.

Animals↗