Biomedical subjects
Publications and source records attributed to L V Kravchenko.
The present paper review the current knowledge on principal mycotoxins of confirmed or potential relevance in human health with respect to occurrence, toxicology and risk assessment.
Oral treatment with lycopene (per os) in doses of 10 or 50 mg/kg for 2 weeks led to accumulation of lycopene in the liver, liver microsomes, and blood plasma, increased total plasma antioxidant activity, inhibited LPO in the liver, and decreased solubilization of lysosomal enzymes. Lycopene had no effect on ex vivo resistance of liver microsomes to LPO and activities of antioxidant enzymes in the liver.
Lycopine in concentrations of 0.5-50 microM suppressed LPO in microsomes induced by NADPH-Fe(2+) and by ascorbic acid-Fe(2+). Lycopine in a concentration of 20 microM completely prevented the decrease in the rate of benz[a]pyrene hydroxylation and activation of p-nitrophenyl-UDP-glucuronosyl transferase caused by LPO induction in microsomes.
Incubation of rat liver microsomes with preparations of grape flavonoids, dihydroquercetin, and silibinin increased their resistance to lipid peroxidation induced by NADPH-Fe2+. This was manifested in less pronounced accumulation of lipid peroxidation products and changes in activity of microsomal enzymes induced by lipid peroxidation. In vitro antioxidant activity of grape flavonoids markedly surpassed that of dihydroquercetin and silibinin. Addition of flavonoids into fodder led to moderate, statistically significant, and similar increase in the resistance of rat liver microsomes to ex vivo induced lipid peroxidation.
Inclusion of a biologically active food supplement (BAS) "Rekicen RD" in rat Wistar ration in percentage 5% result in reduction of toxic action of a trichothecene mycotoxin T-2 toxin. The changes of daily increase in body weight of animals, of relative internal weight, of serum enzyme activity, of not sedimentated activity of lysosomal enzymes and of activity of enzymes of a xenobiotic metabolism in a liver were expressed in a lesser degree. It is possible that a protective action of BAS is related with high adsorption capacity of wheat bran in BAS composition and with their possible influence on activity of enzymes participating in detoxification T-2 toxin (UDP-glucuronosyltransferase).
The rats were fed with the Genetically Modified Sugar Beet line 77 (Monsanto Ko, USA) 10 g/rat/day for 1 month. Their blood, urea and liver were investigated to measure total protein and glucose levels, aminotransferase and alkaline phosphatase activities, pH, creatinine level as well as hepatic enzyme activity of the I and II phases of xenobiotic metabolism and whole and non-sedimentated lysosomal enzyme activities and activity of antioxidant system.
The rats were fed with the Suger from the Genetically Modified Suger Beet line 77 (Monsanto Ko, USA) 3 g/rat/day for 3 months. Their blood, urea and liver were investigated to measure total protein and glucose levels, aminotransferase and alkaline phosphatase activities, pH, creatinine level as well as hepatic enzyme activity of the I and II phases of henobiotic metabolism and whole and non-sedimentated lysosomal enzyme activities and activity of antioxidant system.
The distribution zearalenon (ZL) in products of processing of contaminated wheat, barley and maize grains was is investigated. Results of the data analysis on the investigation of an actual nutrition of the population in Russia is presented; the share of products of processing of contaminated wheat, barley and maize grains as part of the total ration was determined Varied values of Maximum Acceptable Concentration (MAC) of ZL based on the obtained results are offered: 1 mg/kg--for wheat, barley and maize grains; 0.2 mg/kg--for main products of grain processing, viz flour and groats. The application of these MAC-values for ZL ensures the conformity between the ones for raw materials and for products of processing of raw materials, as well as the limitation of the maximum possible ZL--intake within the bounds of Acceptable Daily Intake (ADI) for a man.
The maintenance of male Wistar rats on semi-synthetic diets containing oxidized flaxseed oil for 4 weeks caused decrease in serum total antioxidant activity, significant suppression of microsomal UDP-glucuronosyl transferase activity and benzpyrene hydroxylase activity, increase in reduced glutathione level and catalase activity of liver. Supplementation of diets with 0.05% of soy isoflavones has resulted in normalization of investigated characteristics.
Experiments on Wistar rats showed that feeding a ration containing 0.1% concentrate of food indoles (indole-3-carbinole and ascorbigen) for 3 weeks increased activity of phases I and II xenobiotic metabolism enzymes in the liver and intestinal mucosa and weakened the toxic effects of trichothecene T-2 mycotoxin. Activity of the key enzymes of T-2 detoxification, microsomal carboxylesterase and UDP-glucuronosyl transferase, was 1.5-2-fold higher in rats receiving T-2 toxin against the background of indole-enriched diet compared to toxin-treated rats kept on standard ration.
The rats were fed with the flour of corn from genetically modified corn MON 810 and from genetically modified corn GA 21 (Monsanto Co, USA) 3 g/rat/day for 6 months. Their blood, urea and liver were investigated to measure total protein and glucose levels, aminotransferase and alkaline phosphatase activities, pH, creatinine level as well as hepatic enzyme activity of the I and II phases of xenobiotic metabolism and whole and non-sedimentated lysosomal enzyme activities, the level of processes of lipids peroxidation and activity of antioxidant system.
Association between traits for hormonal status and nodulation in the mutants of pea Pisum sativum L. with abnormal nodulation and original forms was analyzed. The sensitivity of plant tissues to exogenous phytohormones and changes in the concentration of the major auxin, indolyl-3-acetic acid, in plant roots during interaction with rhizobia were examined. Association between Nod(++)-phenotype and auxin balance was revealed: the supernodulating mutants were more sensitive to auxin treatment than the parental cultivars. Mutations in the sym8 gene, in contrast to those in the sym5 gene, had no effect on plant hormonal status. The level of indolyl-3-acetic acid during interaction with rhizobia depended on the time after inoculation and plant genotype. The mutations affecting nodulation were suggested to change auxin level in roots.
The enrichment of a diet of rats by flavonoids of milk thistle, Silybum marianum, reduced toxicity of T-2 toxin and was accompanied by reduction of a degree of change of total and nonsedimentable activity of lysosomal enzymes and microsomal xenobiotic metabolizing enzymes.
Subacute toxicity of T-2 toxin in rats was characterized by a primary defeat of liver, thymus, spleen and intraorgan arteries. In 75% of animals found out increase of the size and adipose infiltration of a liver, in all animals--reduction of the size of thymus (sharp) and spleen (moderate) and pronounced hypoplasia of lymphoid tissue. In the majority of rats vacuolation of cytoplasma of smooth-muscular walls of coronary and intrarenal arteries was revealed. In animals received T-2 toxin against a background of a diet with addition a flour from seeds of milk thistle with high contents of flavonoids, described morphological changes were expressed to a lesser degree and were observed less often. Moderate periportal adipose infiltration of a liver was revealed in 30% of animals, occupancy by cells of lymphoid tissue increased, the quantity and sizes of vacuoles in walls of vessels decreased.
The role of tomato seed and root exudate sugars as nutrients for Pseudomonas biocontrol bacteria was studied. To this end, the major exudate sugars of tomato seeds, seedlings and roots were identified and quantified using high-performance liquid chromatographic (HPLC) analysis. Glucose, fructose and maltose were present in all studied growth stages of the plant, but the ratios of these sugars were strongly dependent on the developmental stage. In order to study the putative role of exudate sugar utilization in rhizosphere colonization, two approaches were adopted. First, after co-inoculation on germinated tomato seeds, the root-colonizing ability of the efficient root-colonizing P. fluorescens strain WCS365 in a gnotobiotic quartz sand-plant nutrient solution system was compared with that of other Pseudomonas biocontrol strains. No correlation was observed between the colonizing ability of a strain and its ability to use the major exudate sugars as the only carbon and energy source. Secondly, a Tn5lacZ mutant of P. fluorescens strain WCS365, strain PCL1083, was isolated, which is impaired in its ability to grow on simple sugars, including those found in exudate. The mutation appeared to reside in zwf, which encodes glucose-6-phosphate dehydrogenase. The mutant grows as well as the parental strain on other media, including tomato root exudate. After inoculation of germinated sterile tomato seeds, the mutant cells reached the same population levels at the root tip as the wild-type strain, both alone and in competition, indicating that the ability to use exudate sugars does not play a major role in tomato root colonization, despite the fact that sugars have often been reported to represent the major exudate carbon source. This conclusion is supported by the observation that the growth of mutant PCL1083 in vitro is inhibited by glucose, a major exudate sugar, at a concentration of 0.001%, which indicates that the glucose concentration in the tomato rhizosphere is very low.
The rats were fed with albuminous concentrate from the genetically modified soybean 40-3-2 ("Monsanto Co", USA) 1.25 g/rat/day for 5 months. Their blood, urea and liver were investigated to measure total protein and glucose levels, aminotransferase and alkaline phosphatase activities, pH, relative density and creatinine level in the urea, as well as hepatic enzyme activity of the I and II phases of xenobiotic metabolism, and the whole and non-sedimentated lysosomal enzyme activities. The lasting albuminous concentrate supplementation from the genetically modified soybean to the rat's diet has been shown to modify hepatocyte membrane function and enzymatic activity within physiological standards. It was not harmful to the adaptation systems.
The influence of selenium excess and deficiency on the activity of xenobiotic metabolizing enzymes and the metabolism of mycotoxin deoxynivalenol (DON) in rats was studied. Wistar male rats were fed for 6 weeks semi-synthetic diets containing 0.2, 1.0 or 5.0 ppm selenium. For induction of selenium deficiency the weanling rats were fed for 6 weeks diet containing < or = 0.02 ppm selenium. The activity of selenium-dependent glutathione peroxidase was reduced in the liver of selenium-deficient rats by 93% at 42 days. DON, its de-epoxy metabolite DOM-1, DON and DOM-1 glucuronides were analyzed by reverse-phase HPLC in urine and feces after the single oral dose of DON (8 mg/kg). Selenium-supplemented (5 ppm) diet increased by 2-3 times formation and elimination of DON and DOM-1 glucuronides in urine. Selenium-deficient diet decreased formation of DOM-1, but increased significantly total excretion of DON and DON glucuronides. The activity of GT1 and GT2 forms of UDP-glucuronosyltransferase, an enzyme principally responsible for glucuronidation, was two times higher in the liver of rats fed both selenium-supplemented and selenium-deficient diets.
The occurrence of deoxynivalenol (DON) and zearalenone in 495 samples of food wheat, barley and rye collected from different regions of Russia, and in 633 samples of fresh harvested wheat from Krasnodar region in 1993 and 1994 was surveyed. DON was detected in 97% of fresh harvested wheat samples in 1993, exceeding maximum tolerated level MTL) in 69% of samples analyzed. 23% of fresh harvested wheat samples were positive for DON and only in 5% of samples investigated DON concentration exceed MTL in 1994. Zearalenone was found in low concentrations in 3 of 154 wheat samples analyzed. Surveys of food wheat, barley and rye samples have shown that 23%, 7% and 3% of lots were positive for DON, respectively, in 1993. DON concentration exceed MTL in 14% of food wheat samples. The frequency of DON contamination of the 1994 food wheat samples was 6%. No mycotoxins were found in the 1994 food barley and rye samples analyzed. Almost all DON contaminated lots of food grain were collected from North Caucasus region.