Effect of oyster mushroom (Pleurotus ostreatus) on pathological changes in dimethylhydrazine-induced rat colon cancer.

The effect of 5% of dried oyster mushroom (Pleurotus ostreatus) in the diet on the dimethylhydrazine (DMH)-induced colon carcinogenesis was studied in male Wistar rats. DMH in a dose of 20 mg/kg of body weight was applied to animals once a week during a period of 12 weeks. Mushroom diet was applied either after treatment with DMH for another 21 weeks or during the whole experiment. Mushroom diet reduced significantly the incidence of lymphoid hyperplasia foci when mushroom was supplemented during the whole experiment. Tumour lesions could be characterized either as carcinoma in situ, or as infiltrating adenocarcinoma. Mushroom diet did not affect significantly the incidence of tumours. Nevertheless, a reduction in total number of tumours was observed in both groups of animals fed mushroom diet. A significant reduction of the number of tumour foci of the type carcinoma in situ was observed in animals fed the oyster mushroom during the whole experiment. Also these animals had the significantly lower number of aberrant crypt foci. Mushroom diet reduced the ornithine decarboxylase activity in the colon and in the liver when oyster mushroom diet was administered during the whole experiment.

Dose- and time-dependent hypocholesterolemic effect of oyster mushroom (Pleurotus ostreatus) in rats.

The effect of the dose of oyster mushroom in the diet (1.0, 2.5, and 5.0%) and of the period of application (8, 16, 28, and 52 wk) on cholesterol accumulation in blood and body organs was studied in weanling male Wistar rats fed a diet containing 0.3% cholesterol. Reduction of cholesterol in serum and body organs was found to be dependent on the amount of dietary oyster mushroom administered. A negative correlation between the mushroom dose and cholesterol level was found after 8 and 28 wk of feeding (r=-0.9821 and -0.9803, respectively; P < 0.02 for both cases). The dose of 1% oyster mushroom did not affect cholesterol levels in serum or body organs. A significant reduction of cholesterol levels was observed in serum (31-46%) and liver (25-30%) at a dose of 5% of oyster mushroom for all periods. Reduced cholesterol content in very low-density lipoproteins (VLDL) was also observed at this level. The highest dose of oyster mushroom induced a decrease in conjugated diene levels in erythrocytes and an increase in the levels of reduced glutathione in the liver and stimulated the activities of catalase and glutathione peroxidase in the liver in the final period of the experiment.

Effect of mushroom Pleurotus ostreatus and isolated fungal polysaccharide on serum and liver lipids in Syrian hamsters with hyperlipoproteinemia.

In Syrian hamsters, a diet with 44% of the calories being fat and containing 52 mg cholesterol (C)/100 g induced an accumulation of blood plasma and liver C and triacylglycerol (TG). In these animals, we studied the effect of dried whole mushroom (Pleurotus ostreatus, 2% in the diet, 6-mo experiment) and ethanol-insoluble residue and structurally defined fungal polysaccharide, both isolated from the mushroom (in both cases, 4% in the diet, 2-mo experiments) on C and TG concentration in serum and liver. Whole mushroom effectively retarded the increase in C and TG in both serum and liver throughout the experiment. The mushroom also reduced the content of all lipids in lipoproteins with densities of less than 1.006 to less than 1.063 g/ml. Very-low-density lipoproteins played a substantial role in the decrease (65-80%) in serum lipids. As a result, the lipoprotein concentration of the specified density classes was reduced by 45-60%, and the concentration of the serum lipoprotein pool was reduced by 40%. Neither the chemical composition of high-density lipoproteins nor their serum concentration was affected by the mushroom. Ethanol-insoluble mushroom residue did not significantly affect serum lipid levels, but it reduced liver TG content. Fungal polysaccharide lowered the C content in serum and liver.

The mushroom Pleurotus ostreatus accelerates plasma very-low-density lipoprotein clearance in hypercholesterolemic rat.

The administration of a diet containing 5% of dried oyster mushroom to male Wistar rats fed a cholesterol diet (0.3%) shortly after weaning for 8 weeks reduced cholesterol levels in the serum and liver by 27 and 33%, respectively and increased the fractional turnover rate of 125I-very-low-density lipoproteins (VLDL) by more than 30%.

Dose-dependent hypocholesterolaemic effect of oyster mushroom (Pleurotus ostreatus) in rats.

A highly significant negative correlation (r=-0.981, p < 0.001) between the amount of oyster mushroom (Pleurotus ostreatus) in the diet and cholesterol levels in the serum has been found in male Wistar rats fed shortly after weaning by a a diet with 0.3% cholesterol. The addition of 1.0, 2.5 and 5.0% of oyster mushroom to the diet reduced the levels of serum cholesterol by 11, 31 and 46%, respectively. The diet containing 5% of oyster mushroom suppressed cholesterol accumulation in the liver and increased the fraction of cholesterol carried by high-density lipoproteins.

Protein synthesis in growing and adult rats on casein and gluten nutrition.

Male weaning rats were put on a diet with a physiological nutrient combination adjusted for age, milk casein (E/N = 0.79) and wheat gluten (E/N = 0.30) being the sources of protein. The net protein ratio (NPR) was evaluated weekly until 140 days of age. On days 70 and 140, L-(U-14C)-tyrosine was administered intraperitoneally and 12 h later specific tyrosine activity was determined in the protein fraction of liver and muscle by measuring the incorporation of the labeled amino acid in order to assess protein synthesis over the corresponding time period. Regression lines describing the relationship between animals' weight, age and protein source suggested that the daily weight increase was 6.99 g between days 30-77, 2.97 g between days 77-105 and 0.64 g between days 105-140. Muscle tyrosine levels in rapidly growing animals aged 70 days were 91.0 micrograms/g/12 h for casein and 65.6 micrograms/g/12 h for gluten. Liver tyrosine levels were 336.4 and 189.6 micrograms/g/12 h, respectively. The differences observed at this age were highly significant. In adult animals (140 days old) there were non-significant differences between tyrosine levels in the casein- and gluten-fed groups. The isotope study clearly showed that protein synthesis was reduced in growing and developing animals on vegetable nutrition, which is deficient in essential amino acids, (especially the limiting amino acid lysine, crucial for the utilization of all other amino acids in peptide chain synthesis). The low rate of amino acid utilization found in animals younger than 105 days is consistent with the findings obtained by the isotope method.

Effect of oyster fungus (Pleurotus ostreatus) on serum and liver lipids of Syrian hamsters with a chronic alcohol intake.

The authors studied the effect of oyster fungus (Pleurotus ostreatus) (2% dried fruiting bodies in a standard diet) on the serum and liver lipids of growing male Syrian hamsters with a chronic alcohol intake (a 15% aqueous solution). After eight weeks' alcohol intake there was an increase in their serum cholesterol, triacylglycerol (TG) and phospholipid (PL) concentration, 40 - 60% of which was accounted for by an increase in the very low density lipoprotein (VLDL) concentration. The proportion of VLDL in the lipoprotein pool rose by almost 15%, whereas the proportion of high density lipoproteins (HDL) fell. The simultaneous administration of the fungus in the diet reduced the cholesterol level below the value in the control animals not given any alcohol. Both the serum TG and the VLDL concentration fell by 30%, but neither the chemical composition and concentration of the HDL nor the cholesterol concentration were affected. The addition of the fungus to the diet completely abolished the increase induced in the liver cholesterol and TG concentration by the chronic intake of alcohol.

Hypocholesterolemic effect of ascorbic acid in maturity-onset diabetes mellitus.

A significantly lower vitamin C concentration has been found in the blood and particularly in the leukocytes of hypercholesterolemic diabetic patients than of healthy blood donors. Ascorbic acid administered in a dose of 500 mg per day for 12 months to metabolically stabilized hypercholesterolemic subjects with maturity-onset diabetes mellitus (diabetic diet without insulin or diabetic drugs) brought about a striking decline of cholesterolemia and a moderate decline of triglyceridemia. The serum lipid level in the control group given placebo remained unaltered. A daily administration of 500 mg of ascorbic acid for six months failed to affect the fasting level of serum immunoreactive insulin. It is assumed that the long-term administration of ascorbic acid to maturity-onset diabetics removed the tissue ascorbate deficiency and improved the liver ability to compensate the increased endogenous synthesis of cholesterol by its enhanced transformation to bile acids.

[The effect of a vegetarian diet on protein and fat metabolism values in rats of various ages]. / Vplyv rastlinnej výzivy na niektoré hodnoty metabolizmu bielkovín a tukov u potkanov v rôznom veku.

Male len rats at the age of 30-140 days were administered a diet with an optimum content of nutrients in dependence on their age in which the source of proteins was this: milk casein (essential acid to nonessential acid ratio E/N = 0.79), soya (defatted and without inhibitors of digestive enzymes, E/N = 0.73), wheat gluten (E/N = 0.30), and their mixture (with one-third portions of each protein, E/N = 0.54). The dietary protein values were adjusted to optimum values according to the quality with respect to casein (without amino acid fortification). Protein utilization (net protein ratio NPR) was determined in weekly intervals, triacylglycerol and cholesterol concentrations in the blood serum were determined on the 70th and 140th day of age. A proteosynthesis rate was determined isotopically as L-/U-14C/-tyrosine incorporation in the protein fractions of liver and muscle in 12 hours after intraperitoneal application of the isotope in the rats in the period of rapid growth and in the adult rats on a casein--gluten diet. The isotopically determined values of tyrosine in the liver and muscles are significantly lower for the age of 70 days and gluten diet in comparison with the casein values. The proteosynthesis rate at the age of 140 days is identical. A direct relation was also found between protein utilization and the values of the amino acid score of limiting amino acids AS and the potential biological value of the diet BHp in growing rats at the age of 30-98 days (AS-K/Met + Cys/2/67, S/Met + Cys/2/63, G/Lys/28, mixture/Met + Cys/2/67; BHp-K 70.0; S 65.1; G 54.1; mixture 77.0; NPR/70 days/-K 2.00; S 1.48; G 1.22; mixture 2.07). In adult rats (from the age of 105 days) the utilization of the diet from vegetable sources is equalized with the utilization of the diet from animal sources, hence it does not depend on the aminogram quality. The results demonstrate the insufficiency of vegetable sources of food with respect to proteosynthesis and the content of limiting amino acids (decisive for the synthesis of peptide chains) in the period of the organism development. In adult rats the values of the aminograms of food vegetable sources are sufficiently high with respect to the lower rate of proteosynthesis (not for the growth but for the organism maintenance, tissue regeneration).(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of fatty acid composition, cadmium and vitamin E intake on prooxidative-antioxidative state of rat liver.

The effect of cadmium intake (100 micrograms/kg body weight/day as cadmium chloride over a period of three months) on the prooxidative-antioxidative state of liver was studied in 30 days old weaned male rats. Animals were fed a nutritionally balanced lacto-vegetable diet containing high-quality amino acid mixture (casein + gluten 1:1), lipids in form of either pork fat PF (% of polyunsaturated fatty acids PUFA = 11.9; unsaturation index UI = 72), margarine MA (% PUFA = 21.9; UI = 98), or soybean oil SO (% PUFA = 61.2; UI = 156) and vitamin E at amount of 60 mg/kg of food (groups PF, PF + Cd, MA, MA + Cd, SO, SO + Cd) or 600 mg (groups PF + Cd + E, MA + Cd + E, SO + Cd + E) in form of alpha-tocopheryl acetate. The following parameters were measured: conjugated dienes of fatty acids (CD), activities of superoxide dismutase (SOD), catalase (CAT) (as relative generation of H2O2) and glutathione peroxidase (GSH-Px). A direct relation between lipoperoxidation values and unsaturation index of lipids was found both in spontaneous (PF, MA, SO-control) and cadmium-induced generation of free oxygen radicals. Cadmium intake resulted in a disbalance in prooxidative-antioxidative processes which was manifested in a significant increase of CD in all fat sources (the degree of increase was directly proportional to UI and PUFA), in similar values of relative H2O2 generation and in a nonsignificant increase of GSH-Px in animals with most developed lipoperoxidation (SO). A tenfold increase in the administered dose of vitamin E restored a prooxidative-antioxidative equilibrium disturbed by cadmium intake in the liver of rats fed the diet with animal fat (PF + Cd + E) and margarine (MA + Cd + E) (reduction of CD to the level of control groups, decrease of relative generation of H2O2-significant in MA). In animals fed with soybean oil, a vitamin E-induced reduction of CD was significantly over the control level simultaneously with significant stimulation of GSH-Px activity. No changes in H2O2 generation together with CD levels and GSH-Px activity indicated that a synergic effect of several antioxidants is essential in the case of high lipoperoxidation. Presented results are important with respect to possible control or regulation of the equilibrium between prooxidative and antioxidative processes by nutrition.

[The effect of n-3 fatty acid administration on selected indicators of cardiovascular disease risk in patients with type 2 diabetes mellitus]. / Vplyv podávania n-3 mastných kyselín na vybrané ukazovatele kardiovaskulárnych rizík u pacientov s diabetom mellitus II. typu.

BACKGROUND: Serum triacylglycerols (TG), VLDL, HDL, fatty acid and eicosanoid spectrum are among the factors determining the risk of cardiovascular complications in NIDDM. N-3 polyunsaturated fatty acids (PUFA) are expected to have beneficial effects on these factors. In NIDDM patients there have however been previously reported (late 1980s) some adverse effects. OBJECTIVES: Our aim was to verify the effects of n-3 PUFA in NIDDM patients using relatively low dosage. METHODS: The investigated group included 21 NIDDM patients with dyslipoproteinemia type IV. The patients were treated for 28 days with 1.7 g EPA (eicosapentaenoic acid) + 1.15 g DHA (docosahexaenoic acid)/day (10 capsules/day of MAXEPA, Seven Seas U.K.). The lipoproteins were measured using the BIO-LACHEMA kits, the fatty acid spectrum in phospholipids was determined by gas chromatography and prostanoids (after their separation) were measured by RIA methods. MAIN RESULTS AND CONCLUSIONS: After the MAXEPA treatment there has been a strong decrease in TG (p < 0.005) and VLDL (p < 0.002) serum levels, accompanied by a significant increase in HDL (p < 0.02). The final-to-baseline TG ratio in individual patients negatively correlated with the relative percentage of EPA in phospholipids after the treatment (p < 0.03; r = -0.474). There was no significant change in serum total cholesterol, fasting glycaemia and glycosylated hemoglobin. There was a slight, but statistically already significant (p < 0.05), rise in LDL. The relative percentage of EPA, docosapentaenoic acid and DHA in serum phospholipids increased sharply (p < 0.001, p < 0.001, p < 0.001). The increase of n-3 PUFA in individual patients was linked with the decrease in n-6 PUFA (p < 0.001; r = -0.686). The spectrum of the latter has changed also very markedly. The prostacyclin PGI2-to-thromboxane TxA2 ratio increased significantly (p < 0.001). Beneficial effects of n-3 fatty acids have prevailed and this kind of treatment seems very encouraging also in NIDDM patients. The results are logically compatible with other authors' results pattern formed in 1990s. A slight rise in serum LDL needs a more detailed discussion since only its phenotype B ("small dense LDL particles") has been recently found to be atherogenic. (Tab. 2, Fig. 5, Ref. 15.)

[Regulation of cholesterol metabolism with dietary addition of oyster mushrooms (Pleurotus ostreatus) in rats with hypercholesterolemia]. / Regulácia metabolizmu cholesterolu hlivou ústricovitou (Pleurotus ostreatus) v diéte u potkana s hypercholesterolémiou.

BACKGROUND: It is generally accepted that lowering of serum cholesterol levels reduces the risk of atherosclerosis. Identification and characterization of natural substances with hypocholesterolemic activity useful in dietetic prevention or treatment of hypercholesterolemia is still relevant in countries with persistent progression of hypercholesterolemia. Addition of oyster mushroom (Pleurotus ostreatus), an industrially produced wood-rotting fungus, to the diet effectively reduced cholesterol accumulation in serum and liver of rats fed a cholesterol diet. The aim of a series of experiments was to explain the biochemical mechanism of this effect. METHODS AND RESULTS: Male Wistar rats fed a cholesterol (0.3%) diet shortly after weaning for a period of 8-10 weeks were used in the experiments. The addition of 5% of dried oyster mushroom to the diet had following effects: reduction of cholesterol level both in serum (5.12 +/- 0.55 vs. 3.44 +/- 0.16 mmol/l, p < 0.02) and liver (241 +/- 12 vs. 113 +/- 11 mmol/kg, p < 0.001); redistribution of cholesterol in favour of high-density lipoproteins; reduced production of very-low-density lipoproteins (135 +/- 7 vs. 96.5 +/- 5 mumol/h/kg, p < 0.001); reduced cholesterol absorption (61.2 +/- 2 vs. 53 +/- 2%, p < 0.02) and reduced HMG-CoA activity in liver (137 +/- 16 vs. 86 +/- 9 pmol/min/mg proteins, p < 0.02). Simultaneously, an increase in 7 alfa-hydroxylase activity in liver (17 +/- 1 vs. 22 +/- 1 pmol/min/mg proteins. p < 0.02) and bile acid excretion (7 +/- 0.9 vs. 11 +/- 0.5 mg/day/rat, p < 0.02) was observed. (Values shown are means +/- SEM.) CONCLUSIONS: Biochemical mechanism of hypocholesterolemic effect of oyster mushroom on cholesterol-fed rats includes reduced production of cholesterol-rich very-low-density and low-density lipoproteins which principally determine cholesterol levels in serum. This effect is related to decreased absorption and biosynthesis of cholesterol together with increase in cholesterol catabolism and excretion of degradation products-bile acids.

Oyster mushroom (Pleurotus ostreatus) reduces the production and secretion of very low density lipoproteins in hypercholesterolemic rats.

Oyster mushroom (Pleurotus ostreatus) reduced the production and secretion of nascent very low density lipoproteins in hypercholesterolemic rats. In male Wistar rats (initial body weight about 70 g) fed a semisynthetic diet with 0.3% of cholesterol, the addition of 5% of powdered oyster mushroom (Pleurotus ostreatus) to the diet reduced after 8 weeks the level of serum cholesterol (by 36%) and accumulation of cholesterol and triglycerides in liver (by 51 and 32%, respectively). The decreased levels of serum cholesterol were caused to the same extent by reduction of cholesterol content in very low density lipoproteins (VLDL) and in low density lipoproteins (LDL) (by 53 and 47%, respectively). Biosynthesis of all structural lipids of VLDL (phospholipids, cholesterol, triglycerides) in liver and incorporation of de novo synthesized lipids into secreted nascent VLDL (measured by simultaneous application of Na-acetate-1-14 C and Triton WR 1339 which inhibits peripheral lipolysis) was reduced by application of diet with oyster mushroom.

Mechanism of hypocholesterolemic effect of oyster mushroom (Pleurotus ostreatus) in rats: reduction of cholesterol absorption and increase of plasma cholesterol removal.

The content of cholesterol in the serum and liver of male Wistar rats fed, for the period of 8 weeks shortly after weaning, a diet containing 0.3% of cholesterol was reduced by 33 and 27% by the addition of 5% of dried oyster mushroom powder. Although the level of serum triacylglycerols was not affected by oyster mushroom, their content in liver of rats on mushroom diet was reduced by 41%. Very-low-density lipoproteins and low-density lipoproteins participated by 55 and 38%, respectively, in the total reduction of serum cholesterol. Cholesterol content in high-density lipoproteins was not significantly affected by oyster mushroom. Cholesterol absorption as determined by dual-isotope plasma ratio method was significantly reduced by 14% with oyster mushroom diet. Similarly, this diet increased by 42% the fractional catabolic rate of cholesterol determined by the analysis of decay curve of [4-14C]cholesterol.