High-dose glucocorticoids increases the expression of mineralocorticoid receptor in vascular endothelial cells.

OBJECTIVE: To explore the role of glucocorticoid new mechanism to observe the expression of glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) with lipopolysaccharide (LPS) and dexamethasone (Dex) in human umbilical vein endothelial cells (HUVEC). MATERIALS AND METHODS: LPS "injured" endothelial cells with Dex for "treatment", and then detected the expression of glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) in the endothelial cells by RT-PCR and immunohistochemistry. RESULTS: With high dose (10-6 mol/L) of Dex to stimulate cell 3h, GRmRNA no significant changes in the expression, 6h began to decrease, 12h peak, 24h recovered nearly the level before stimulation. Using different concentrations of Dex and 100 ng/ml LPS stimulation, HUVEC MRmRNA expression was decreased, and high dose (10-6 mol/L) of Dex to stimulate cell 3h, MRmRNA no significant changes in expression, and GRmRNA The difference is that the expression began to increase 6h, 12h, peaked, 24h rebound near the level before stimulation. Immunohistochemistry results consistent with the RT-PCR. CONCLUSIONS: Large dose of DEX (10-6 mol/l) up-regulated the expression of MR and GR in the reduction of the contrast exactly. GC induced the expression of GR and MR in different changes of stress injury of the body may be a regulatory mechanism, and indicate one new mechanism of glucocorticoid exist.

Establishing a 'Physician's Spiritual Well-being Scale' and testing its reliability and validity.

The purpose of this study was to develop a Physician's Spiritual Well-Being Scale (PSpWBS). The significance of a physician's spiritual well-being was explored through in-depth interviews with and qualitative data collection from focus groups. Based on the results of qualitative analysis and related literature, the PSpWBS consisting of 25 questions was established. Reliability and validity tests were performed on 177 subjects. Four domains of the PSpWBS were devised: physician's characteristics; medical practice challenges; response to changes; and overall well-being. The explainable total variance was 65.65%. Cronbach α was 0.864 when the internal consistency of the whole scale was calculated. Factor analysis showed that the internal consistency Cronbach α value for each factor was between 0.625 and 0.794 and the split-half reliability was 0.865. The scale has satisfactory reliability and validity and could serve as the basis for assessment of the spiritual well-being of a physician.

Biodistribution of phenylboric acid derivative entrapped lipiodol and 4-borono-2-18F-fluoro-L-phenylalanine-fructose in GP7TB liver tumor bearing rats for BNCT.

A new phenylboric acid derivative entrapped lipiodol (PBAD-lipiodol) was developed as a boron carrier for the boron neutron capture therapy (BNCT) of hepatoma in Taiwan. The biodistribution of both PBAD-lipiodol and BPA-fructose was assayed in GP7TB hepatoma-bearing rat model. The highest uptake of PBAD-lipiodol was found at 2h post injection. The application of BNCT for the hepatoma treatment in tumor-bearing rats is suggested to be 2-4h post PBAD-lipiodol injection.

Heating efficiency improvement by using a spherically-concaved sectored array in focused ultrasound thermal therapy.

Focus splitting by using sector-sectioned phased arrays is one of effective methods to increase the necrosed volume in single sonication and to reduce the total treatment time in large tumor treatment. However, the split focus contains less concentrated energy and severer focal beam distortion, which limits its usefulness in practical treatments. In this study, we proposed a new heating strategy by combining sonications of strongly-focused and split-focused patterns to increase the heating efficiency. Theoretical predictions and ex-vivo tissue experiments showed that thermal lesions can be enlarged in dimensions after applying the proposed strategy. This may provide a useful way to solve current obstacles in low heating efficiency of split-focus sonications that attempted to shorten the total treatment time in current clinical application.

Dietary fat and garlic oil independently regulate hepatic cytochrome p(450) 2B1 and the placental form of glutathione S-transferase expression in rats.

The individual and combined effects of dietary fat and garlic oil on two drug-metabolizing enzymes, cytochrome P(450) 2B1 and the placental form of glutathione (GSH) S-transferase (PGST), in rat liver were examined in this study. Rats were fed a low corn oil, high corn oil or high fish oil diet and received various amount of garlic oil (0, 30, 80, 200 mg/kg body) orally three times per week for 6 wk. The fat energy in the low and high fat diets accounted for 11.6 and 45.7% of total energy, respectively. Final body weights did not differ among the three dietary fat groups and were not affected by garlic oil treatment. The fatty acid profile in hepatic phospholipids revealed higher eicosapentaenoic acid [20:5(n-3)] and docosahexaenoic acid [22:6(n-3)] levels in the fish oil-fed group than in the low and high corn oil-fed groups (P < 0.05). In contrast, the corn oil-fed groups had greater hepatic phospholipid arachidonic acid [20:4(n-6)] levels (P < 0.05). Both dietary fat and garlic oil significantly affected hepatic cytochrome 7-pentoxyresorufin O-dealkylase (PROD) activity and GST activity toward ethacrynic acid. Rats fed the high fish oil diet had 85 and 51% higher PROD activity compared with those fed the low or the high corn oil diet, respectively (P < 0.05). The GST activity in the high fish oil and the high corn oil groups was 33 and 18% higher than that in the low corn oil group (P < 0.05), respectively, and the GST activity in rats fed the high fish oil diet was higher than in those fed the high corn oil diet (P < 0.05). Garlic oil dose-dependently increased GST activity. No interaction between dietary fat and garlic oil on PROD or GST activity was noted. Northern and Western blot analysis revealed that dietary fish oil increased both cytochrome P(450) 2B1 and PGST mRNA and protein levels. Cytochrome P(450) 2B1 and PGST mRNA and protein levels were also dose-dependently increased by garlic oil treatment. The effects of garlic oil and dietary fat on P(450) 2B1 and PGST mRNA and protein expression were independent. These results indicate that dietary fat and garlic oil independently modulate P(450) 2B1 and PGST expression at transcriptional and/or post-transcriptional stages.

Comparison of the effect of fish oil and corn oil on chemical-induced hepatic enzyme-altered foci in rats.

The effects of fish oil and corn oil diets on diethylnitrosamine initiation/phenobarbital promotion of hepatic enzyme-altered foci in female Sprague-Dawley rats were investigated. Groups of 12 rats were initiated with diethylnitrosamine (15 mg/kg) at 24 h of age. After weaning, they received diets containing either 13.5% fish oil plus 1. 5% corn oil or 15% corn oil for 24 weeks. Rats fed fish oil had significantly greater liver weight, relative liver weight, spleen weight, and relative spleen weight than rats fed corn oil (p < 0.05). Hepatic phospholipid fatty-acid profile was significantly affected by the type of dietary lipid. The rats fed fish oil had significantly greater hepatic phospholipid 20:5 and 22:6 than rats fed corn oil; in contrast, the rats fed corn oil had significantly greater hepatic phospholipid 18:2 and 20:4 than rats fed fish oil (p < 0.05). Rats fed fish oil had significantly lower hepatic vitamin E and PGE(2) content but significantly greater hepatic lipid peroxidation than rats fed corn oil (p < 0.05). The hepatic levels of antioxidant enzymes (GSH reductase and GST) were significantly greater in rats fed fish oil than in rats fed corn oil (p < 0.05). Except for PGST-positive foci (foci area/tissue area), all the other foci parameters (GGT-positive foci area/tissue area, GGT-positive foci no./cm(2), GGT-positive foci no./cm(3), PGST-positive foci no. /cm(2), and PGST-positive foci no./cm(3)) measured in the fish oil group were 10-30% of those in the corn oil group (p < 0.05). Analyses of Pearson correlation coefficient revealed a positive correlation between hepatic GGT- or PGST-positive foci number (no. /cm(2)) and PGE(2) content (r = 0.66, P = 0.01; r = 0.56, P = 0.02, respectively) but a negative correlation between GGT- and PGST-positive foci (no./cm(2)) and lipid peroxidation (r = -0.8, P = 0.0006; r = -0.58, P = 0.01, respectively), GSH/(GSH + GSSG) ratio (r = -0.61, P = 0.05; r = -0.4, P = 0.14, respectively), GSH reductase (r = -0.75, P = 0.002; r = -0.53, P = 0.02, respectively), and GST activities (r = -0.65, P = 0.01; r = -0.44, P = 0.07, respectively). Similar correlation between foci number (no./cm(3)) and PGE(2), lipid peroxidation, GSH/(GSH + GSSG) ratio, GSH reductase, and GST activities were obtained. The results of this study show that dietary fish oil significantly inhibited hepatic enzyme-altered foci formation compared with corn oil in rats. These results suggest that the possible mechanisms involved in this process are the stimulation of hepatic detoxification system, changes in membrane composition, inhibition of PGE(2) synthesis, the enhancement of GSH-related antioxidant capacity, and the enhancement of lipid peroxidation by fish oil.

Autoantibody against oxidized low-density lipoproteins may be enhanced by cigarette smoking.

A total of 59 healthy male subjects (32 smokers and 27 nonsmokers) who had no reported systemic disease and did not take alcohol and vitamin supplementation were included. The levels of autoantibody to oxidized low-density lipoproteins (ox-LDL) in smokers and age-matched nonsmokers were compared. The plasma levels of antioxidants that can affect the formation of ox-LDL were also measured, and correlation analyses between anti ox-LDL IgG and plasma antioxidants, controlling for age and body mass index (BMI), were performed. Plasma alpha-tocopherol and uric acid concentrations of nonsmokers (2.78+/-1.09 microg/mg total lipid and 6.96+/-1.69 mg/dl, respectively) were significantly higher than those of smokers (1.68+/-0.48 microg/mg total lipid and 6.15+/-1.14 mg/dl, respectively) (P<0.05). Although plasma ascorbate and retinol levels were not significantly different between smokers and nonsmokers, smokers older than 45 years old had significantly lower plasma ascorbate levels (0.32+/-0.17 mg/dl) than age-matched nonsmokers (0. 53+/-0.14 mg/dl) (P=0.036). Higher level of plasma anti ox-LDL IgG was noted in the group of smokers compared with nonsmokers (515+/-409 mU/ml vs. 407+/-268 mU/ml, respectively) under the statistic method of Chi-Square test (P=0.049). A significant negative correlation was found between plasma anti ox-LDL IgG and alpha-tocopherol in the combined population as well as in the smoker group (r=-0.26, p=0.047; r=-0.48, p=0.006; respectively). However, there was no correlation between plasma anti ox-LDL IgG and the levels of other antioxidants. These results suggest that reduced concentrations of alpha-tocopherol are associated with cigarette smoking. The significantly negative correlation between plasma anti ox-LDL IgG and alpha-tocopherol in the entire study population as well as in the smoker group suggests that plasma alpha-tocopherol may be partially effective if not totally at protecting LDL from oxidative damage caused by cigarette smoking and dietary supplementation with alpha-tocopherol may provide a protective effect against LDL oxidation, especially in smokers.

Suppression of altered hepatic foci development by a high fish oil diet compared with a high corn oil diet in rats.

Effects of low corn oil, high corn oil, and high fish oil diets on altered hepatic foci development in female Sprague-Dawley rats were investigated. Rats assigned to Groups 1-4 were initiated with saline as the control and those assigned to Groups 5-7 were initiated with diethylnitrosamine (DEN 15 mg/kg) at 24 hours of age. After weaning, all rats, except those in Group 1, received 500 ppm phenobarbital (PB) in their diet as tumor promoter for three months. Altered hepatic foci development was significantly lower in DEN-initiated rats fed the high fish oil + PB diet than in DEN-initiated rats fed the high corn oil + PB diets. Liver weight and relative liver weight were significantly greater in rats fed the high fish oil + PB diet than in rats fed the other diets, and hepatic biotransformation/detoxification enzyme activities were greater in rats fed the fish oil + PB diets than in rats fed the other diets. These results suggest that the effect of a high fish oil diet on altered hepatic foci may occur through regulation of hepatic biotransformation/detoxification enzyme activities, leading to alteration in the tumor-promoting action of PB. Dietary lipid significantly affected the hepatic phospholipid fatty acid composition of rats. n-3 polyunsaturated fatty acids were incorporated into membrane phospholipid at the expense of n-6 polyunsaturated fatty acids. A high fish oil diet caused greater oxidative stress in rats, as measured by plasma vitamin E level, red blood cell glutathione status, liver lipid peroxidation, and hepatic glutathione reductase activity. Pearson's correlation analysis indicated that the foci number was negatively correlated to the liver thiobarbituric acid-reactive substance and 7-pentoxyresorufin O-dealkylase activity, and the foci area was negatively correlated to the liver thiobarbituric acid-reactive substance activity (p < 0.05) in rats of groups that developed foci. These results suggest that the type of dietary lipid is the more important determinant for gamma-glutamyl transpeptidase-positive foci development than the amount of dietary lipid when rats consumed approximately the same amount of calories in all the dietary groups, and the underlying mechanisms may be partially ascribed to the antioxidant/oxidation status and biotransformation/detoxification system of rats.

Lack of effect of dietary alpha-tocopherol on chemically induced hepatocarcinogenesis in rats.

We investigated the effects of alpha-tocopherol on diethylnitrosamine (DEN) initiation-phenobarbital (PB) promotion of hepatic foci in female Sprague-Dawley rats. Groups of eight rats were initiated with DEN (15 mg/kg) at 24 hours of age. After weaning, they received diets containing 500 ppm PB and various concentrations of alpha-tocopherol, deficient (0 ppm), adequate (100 ppm), and supplemented (5,000 ppm), for 24 weeks. Rats fed alpha-tocopherol-supplemented diets had significantly greater hepatic alpha-tocopherol levels than those fed alpha-tocopherol-deficient or -adequate diets (p < 0.05). Liver lipid peroxidation (measured as thiobarbituric acid-reactive substances) was significantly greater in rats fed alpha-tocopherol-deficient diets than in those fed alpha-tocopherol-adequate or -supplemented diets (p < 0.05). The dietary alpha-tocopherol level had no significant effect on the ratios of reduced glutathione (GSH) to oxidized GSH or reduced GSH to total GSH in the liver or on the plasma prostaglandin E2 concentration or on the activities of hepatic cytosolic and particulate protein kinase C. Rats fed alpha-tocopherol-adequate or -supplemented diets had significantly greater hepatic glutathione S-transferase, GSH reductase, and GSH peroxidase activities than those fed alpha-tocopherol-deficient diets (p < 0.05). The dietary alpha-tocopherol level did not significantly affect the formation of hepatic gamma-glutamyl transpeptidase- and placental glutathione S-transferase-positive foci. These results suggest that alpha-tocopherol does not influence hepatic foci formation and that reactive oxygen species may not be the underlying mechanism of hepatic foci formation in this DEN initiation-PB promotion model of hepatocarcinogenesis.

Enterovesical fistula: experiences with 41 cases in 12 years.

BACKGROUND: A retrospective analysis of enterovesical fistula treated at Chang Gung Memorial Hospital was conducted to determine the optimal diagnosis and management of this disease. METHODS: The records of 41 patients who presented from 1984 to 1996 and had a final diagnosis of enterovesical fistula were retrospectively reviewed. The etiology, symptoms on presentation, diagnostic tools, and modality of treatment were analyzed. RESULTS: The majority of these cases were associated with malignancy (38, 92.7%), and the others with diverticulitis (2, 4.9%) and iatrogenic causes (1, 2.4%). In those with malignancy, 15 patients (39.5%) were found to have tumor recurrence. The most frequent symptom in enterovesical fistula was fecaluria (58.5%), followed by abdominal pain (22%) and dysuria (14.6%). Diagnostic tools included the barium enema, cystography, and cystoscopy; these methods could identify the fistula in 63.2%, 60%, and 53.8% of the patients, respectively. Methods of management included diversion only (39%), one-stage fistula repair (36.6%), and watchful surveillance (24.4%). CONCLUSION: Enterovesical fistula should be considered if fecaluria, pneumaturia, or persistent non-specific urinary tract infection present as the initial complaint. A thorough surgery for a possible underlying malignancy is mandatory when confronted with enterovesical fistula, since the incidence of inflammatory bowel disease is low in this area. An abdominal computer tomography (CT) scan, barium enema, and cystogram can be useful diagnostic tools. Treatment of this entity should be individualized according to each patients clinical status.

alpha-Tocopherol acetate supplementation enhances rat hepatic cytochrome PROD activity in the presence of phenobarbital induction.

Hepatic cytochrome P-450 enzymes play important roles in bioactivation of chemical carcinogens, biotransformation of many endogenous compounds, and detoxification of numerous xenobiotics. These enzyme activities have been shown to be regulated by various dietary factors. In our previous study, hepatic cytochrome pentoxyresorufin O-dealkylase (PROD) activity was decreased in rats fed an alpha-tocopherol acetate-deficient diet compared with rats fed alpha-tocopherol acetate-adequate or -supplemented diets. The objective of the present study was to investigate whether the modulatory effect of dietary alpha-tocopherol acetate on hepatic cytochrome PROD activity is influenced by the presence of phenobarbital. Weanling male Sprague-Dawley rats were fed the AIN-76 diet for four days, fasted for two days, then fed semipurified diets that were alpha-tocopherol acetate deficient, adequate, or supplemented with 5 and 15 g/kg alpha-tocopherol acetate for four days. Liver and plasma alpha-tocopherol concentrations were dose dependently regulated by dietary alpha-tocopherol acetate level. Inhibition of lipid peroxidation by dietary alpha-tocopherol acetate was dose dependent. Hepatic total cytochrome P-450 content was significantly greater in rats fed diets supplemented with 5 and 15 g/kg alpha-tocopherol acetate than in rats fed an alpha-tocopherol-adequate diet (p < 0.05). Hepatic cytochrome PROD activity was significantly greater in rats fed diets supplemented with 5 and 15 g/kg alpha-tocopherol acetate than in rats fed alpha-tocopherol acetate-deficient and -adequate diets (p < 0.05). These results suggest that, in the presence of phenobarbital, dietary alpha-tocopherol acetate efficiently affects tissue alpha-tocopherol levels and inhibits lipid peroxidation and that diets supplemented with 5 or 15 g/kg alpha-tocopherol acetate enhance hepatic cytochrome PROD activity compared with alpha-tocopherol acetate-deficient or -adequate diets.

Effect of dietary lipid on gamma-glutamyl transferase-positive foci during hepatocarcinogenesis in rats.

The effect of dietary lipid on gamma-glutamyl transferase-positive (GGT-positive) foci was investigated. Female Sprague-Dawley rats were dosed with diethylnitrosamine (15 mg/kg) at 24 h of age. After weaning, they were fed nutritionally complete semipurified diets for 3 months. Rats fed 15% corn oil had significantly lower hepatic phospholipid eicosapentaenoate and docosahexaenoate than rats fed 7.5% corn oil plus 7.5% fish oil, 5% corn oil plus 10% fish oil (P < 0.05). However, rats fed 15% corn oil had significantly greater hepatic phospholipid arachidonate than rats fed the other two diets (P < 0.05), suggesting that n-3 polyunsaturated fatty acids were incorporated into hepatic phospholipid at the expense of n-6 polyunsaturated fatty acids. Hepatic PGF2alpha content was significantly greater in rats fed 15% corn oil than in rats fed the other two diets (P < 0.05). Rats fed fish oil had significantly lower hepatic vitamin E content than rats fed corn oil (P < 0.05). Hepatic lipid peroxidation (TBARS) tended to increase with increased dietary fish oil (P < 0.05). Dietary lipid did not influence GGT-positive foci area or number. In conclusion, dietary lipid affected hepatic PGF2alpha production, however, showed no effect on GGT-positive foci area and number. This may suggest that PGF2alpha is not the underlying mechanism for GGT-positive foci during hepatocarcinogenesis.

Amount and type of dietary lipid modulate rat hepatic cytochrome P-450 activity.

The influence of the amount and type of dietary lipid on rat hepatic cytochrome P-450 activities in the presence and absence of inducer administration was investigated. Weanling male Sprague-Dawley rats were fed fat-free or 20% beef tallow, olive oil, corn oil, linseed oil, or menhaden oil diets in combination with one of the following three treatments: no inducer, intraperitoneal injection of phenobarbital (75 mg/kg body wt) for three consecutive days before they were killed, or intragastric administration of acetone (5 ml/kg) one day before they were killed. Twenty percent linseed oil and menhaden oil diets induced the highest level of activity among the different fat types in the presence of phenobarbital and acetone. Cytochrome P-450IIB1 activity was induced to a significantly greater extent by acetone administration in conjunction with the 20% menhaden oil diet than in conjunction with the other dietary oils (p < 0.05). In the presence of acetone, 20% beef tallow, 20% linseed oil, and 20% menhaden oil diets significantly induced cytochrome P-450IIE1 activity compared with the fat-free diet (p < 0.05). In conclusion, cytochrome P-450IIB1 and P-450IIE1 activities in rats were significantly increased by specific inducers, and dietary lipid was necessary for this effect. Diets supplemented with linseed and menhaden oils were most effective in inducing this activity.

No inhibition of gamma-glutamyl transpeptidase-positive foci by vitamin E with or without phenobarbital.

The effect of vitamin E on gamma-glutamyl transpeptidase-positive foci, with or without phenobarbital, was investigated. Groups of six female Sprague-Dawley rats were initiated with diethylnitrosamine (15 mg/kg) at 24 hours of age. After weaning, they were fed diets with 10% (wt/wt) fish oil; the diets contained 0, 5,000 or 15,000 ppm vitamin E supplementation with or without phenobarbital (500 ppm) for six months. Phenobarbital significantly increased liver weight and liver weight as a percentage of body weight (p < 0.05), suggesting a liver hypertrophic effect of phenobarbital. Phenobarbital significantly decreased hepatic phospholipid arachidonate, eicosapentaenoate, and docosahexaenoate (p < 0.05); this may indicate that phenobarbital stimulates phospholipase A2 activity and results in the increased release of polyunsaturated fatty acids from phospholipids and the decrease of hepatic phospholipid polyunsaturated-to-saturated fat ratio. In rats fed phenobarbital, hepatic vitamin E content was lower than in rats fed no phenobarbital; this suggests that phenobarbital causes oxidative stress or induces enzymes that metabolize the vitamin. Phenobarbital exposure significantly increased hepatic prostaglandin F2 alpha and glutathione S-transferase activity (p < 0.05). Vitamin E did not influence hepatic gamma-glutamyl transpeptidase-positive foci area and number with or without phenobarbital, and phenobarbital showed a strong promoting action on enzyme-altered hepatic foci.

Corn oil enhances gamma-glutamyl transpeptidase-positive foci development in the presence of phenobarbital during hepatocarcinogenesis in rats.

We investigated the effects of type of dietary fat and phenobarbital on gamma-glutamyl transpeptidase-positive foci development. Four groups of six female Sprague-Dawley rats were initiated with diethylnitrosamine (15 mg/kg) at 24 hours of age. After weaning, they were fed nutritionally complete semipurified diets containing 15% corn oil or 5% corn oil + 10% fish oil and supplemented with 5,000 ppm vitamin E with or without phenobarbital (500 ppm) for three months. Dietary fish oil significantly increased hepatic phospholipid eicosapentaenoate and docosahexaenoate concentrations and decreased arachidonate concentration compared with 15% corn oil (p < 0.05). Corn oil (15%) significantly increased hepatic prostaglandin F2 alpha concentration compared with 10% fish oil (p < 0.05). Phenobarbital significantly stimulated glutathione S-transferase activity in both dietary fat groups (p < 0.05). In the absence of phenobarbital, type of dietary fat showed no effect on hepatic gamma-glutamyl transpeptidase-positive foci development. However, in the presence of phenobarbital, 15% corn oil significantly enhanced gamma-glutamyl transpeptidase-positive foci development compared with 10% fish oil (p < 0.05). Phenobarbital showed a strong tumor-promoting action in both dietary groups. In conclusion, there was an interaction between type of dietary fat and phenobarbital on gamma-glutamyl transpeptidase-positive foci development during hepatocarcinogenesis in rats.

Regulatory effects of dietary n-3 and n-6 lipids on plasma and hepatic lipid levels, liver cell number and microsomal protein content in spontaneously hypertensive rats.

Weanling male spontaneously hypertensive rats were fed semipurified diets containing either corn or fish oil for 8 weeks. Rats fed on fish oil diet had significantly lower plasma triglyceride, total cholesterol and HDL-cholesterol levels than rats fed on corn oil diet (P < 0.05). Moreover, rats fed on fish oil diet had significantly lower liver total lipid and triglyceride concentrations than rats fed on corn oil diet (P < 0.05). Dietary lipids were reflected in plasma fatty acid composition. Rats fed on fish oil diet had significantly greater plasma eicosapentaenoate (EPA) and docosahexaenoate (DHA) (n-3 PUFAs) with an accompanying decrease in plasma linoleate (LA) and arachidonate (AA) (n-6 PUFAs), in comparison with the rats fed corn oil (P < 0.05). Those results would suggest that the n-3 PUFAs were incorporated into plasma lipids at the expense of the n-6 PUFAs. Rats fed on corn oil diet had significantly greater liver DNA content than rats fed on fish oil diet (P < 0.05), thereby implying that the n-3 PUFAs in fish oil had an inhibitory effect on liver cell proliferation. Furthermore, rats fed on fish oil diet had significantly greater hepatic microsomal protein content than rats fed on corn oil diet (P < 0.05), indicating that fish oil exerted a stimulatory effect on hepatic microsomal enzymes.

Blood pressure-lowering effect of fish oil is independent of thromboxane A2 level in spontaneously hypertensive rats.

Whether the alterations in the synthesis of thromboxane A2 (TXA2) is the direct mechanism underlying the blood pressure-lowering effect of fish oil was investigated in this study. Six groups of 11 male spontaneously hypertensive rats were fed semipurified diets containing corn or fish oils and graded levels (50, 5000 or 15,000 ppm) of dietary vitamin E for 8 weeks. Plasma TXA2, assayed by RIA, was significantly greater in the corn oil group than in the fish oil group (P < 0.05). Compared to 50 ppm dietary vitamin E, 5000 and 15 000 ppm dietary vitamin E, respectively, significantly decreased plasma TXA2 (P < 0.05). Systolic, mean or diastolic blood pressure, evaluated by the tail cuff method, were significantly higher in the corn oil group than in the fish oil group (P < 0.05). However, vitamin E had no effect on blood pressure. No relationship between TXA2 and blood pressure was found. Experimental results indicated that the alterations in the synthesis of TXA2 were not the direct antihypertensive effect of fish oil.

The detection of S-glutathionation of hepatic carbonic anhydrase III in rats treated with paraquat or diquat.

Protein S-glutathionation has been demonstrated to be one of the cellular responses under oxidative stress and may be involved in many cellular metabolisms. In this study, the effect of redox cycling bipyridylium compounds, paraquat and diquat, on this protein modification was investigated. Male Sprague-Dawley rats were administered i.p. either paraquat at 20 or 40 mg/kg body wt. or diquat at 85 or 170 mg/kg body wt., respectively. The liver was examined at different time points for taking the measurement of the S-glutathionation of carbonic anhydrase III (CA III), thiobarbituric acid-reactive substances (TBARS), vitamin E depletion, glutathione (GSH) and glutathione disulfide (GSSG) contents. The extent of S-glutathionation of CA III was chosen as a marker and was determined by a method combining isoelectric focusing analysis with immunoblotting. Those results indicated that paraquat and diquat significantly increased the generation of TBARS and showed a time-dependent response. The significant effect on vitamin E depletion was only obtained in rats treated with a high dose of diquat for 2 h. Hepatic cellular GSSG contents did not increase but tended to decrease all of the treatments. Although oxidative damage was actually generated in liver, based on the increase of TBARS generation and vitamin E depletion, no increase of CA III S-glutathionation was observed. We propose that the reason for this observation under this circumstance is probably due to the reversible characteristic of CA III S-glutathionation, which has been demonstrated in our previous study (Chai et al., 1991) Arch. Biochem. Biophys. 384, 270-278) and named as dethiolation.

Inhibition of protein thiol modification in hepatocytes isolated from rats supplemented with vitamin E under oxidative stress.

This study examined the effect of vitamin E on maintaining the protein reactive thiols under oxidative stress. Hepatocytes were prepared from male Sprague-Dawley rats fed diets containing three levels of vitamin E (0,100 and 15,000 mg/kg) for 12 wk. Cells were isolated by collagenase perfusion and treated with 0.5 Him tert-butyl hydroperoxide (t-BuOOH) after 24 hr in culture. Carbonic anhydrase III (CA III) having two reactive thiols that can react with GSH under oxidative stress was chosen as the study subject. CA III S-glutathionation was measured by isoelectric focusing/immunoblotting. Results indicated that thiol modification of CA III was induced by t-BuOOH and the pattern of modification was dependent on the vitamin E status. With t-BuOOH treatment, CA III S-glutathionation was quickly induced and the maximum modification was achieved at 3 min in cells isolated from rats fed high levels of vitamin E; however, modification was continuously increased and reached the maximum at 9 min of vitamin E-normal or -deficient cells. Following the maximum modification, a reversion occurred (dethiolation); the rate of reversion was also related to vitamin E status. As shown by image analysis, twofold more (40 v. 20%) CA III was modified in vitamin E-deficient hepatocytes than in cells from rats fed high vitamin E. Glutathione was also abruptly converted to the oxidized state at 3 min in all cells, then gradually reverted to the reduced state. As with the dethiolation of CA III, the rate of glutathione disulfide reduction was correlated to vitamin E status. The production of thiobarbituric acid-reactive substances corresponded to vitamin E status as well and was significantly inhibited in cells from rats fed high vitamin E. These results suggest that vitamin E not only inhibits lipid peroxidation but also plays a role in maintaining the protein thiols under oxidative stress.

Effects of vitamin E deficiency and dietary linoleate on serum thromboxane synthesis in male sprague-dawley rats.

The aim of the present study was to examine whether vitamin E deficiency and dietary linoleate had additive or synergistic effects on serum thromboxane (TX) status and therefore on thrombogenesis. Eight groups of five male weaning Sprague-Dawley rats were fed semipurified diets containing 3.5 or 18.4% of energy from linoleate (en% linoleate) and 0, 100, 5000, 15,000 ppm vitamin E for 8 weeks. Rats fed no vitamin E had the lowest serum vitamin E while rats fed 15,000 ppm vitamin E had the highest serum vitamin E (p < 0.05). Serum 18:2, n-6 (linoleic acid; LA) and 20:4, n-6 (arachidonic acid; AA) were significantly greater in the 18.4 en% linoleate group than in the 3.5 en% linoleate group (p < 0.05). Serum TXA2, measured as its stable metabolite TXB2, was significantly greater in the vitamin E-deficient rats than in the vitamin E-adequate and vitamin E-supplemented rats (p < 0.05). Serum lipid peroxidation, measured as thiobarbituric acid reactive substances (TBARS), was significantly greater in the 0 and 100 ppm vitamin E groups than in the 5000 and 15,000 ppm vitamin E groups (p < 0.05). No interaction between dietary linoleate and vitamin E deficiency on serum TX status was found. However, it seemed that vitamin E deficiency had a more potent effect on TX synthesis than dietary linoleate. The result suggested that vitamin E deficiency may be prothrombogenic via its effect on TX synthesis.