Effect of Changes in the Redox Status on Biofilm Formation in Escherichia coli.

Changes in the redox balance in the medium and in Escherichia coli cells significantly affect the ability of bacteria to form biofilms. An increase in the level of aeration in the culture of wild-type bacteria led to a 3-fold decrease in the mass of biofilms. Mutants lacking components of the glutathione and thioredoxin redox systems, as well as transporters involved in the transmembrane cycling of glutathione, demonstrated increased biofilm formation ability. The effect of exogenous glutathione on biofilm formation depended on the culturing conditions. The addition of 0.1-1 mM Trolox (a water-soluble analog of vitamin E) was accompanied by a 30-40% reduction in biofilm formation.

Influence of plant polyphenols and medicinal plant extracts on antibiotic susceptibility of Escherichia coli.

AIMS: To investigate the influence of polyphenols and plant extracts on the susceptibility of Escherichia coli to antibiotics. METHODS AND RESULTS: Susceptibility of E. coli to antibiotics in the presence of extracts and polyphenols was estimated by the determination of the minimum inhibitory concentrations (MICs). To study gene expression, we used strains of E. coli carrying fusions between promoters of genes katG, sodA, iucC and structural ß-galactosidase gene. Treatment with polyphenols and some plant extracts significantly decreased the antibacterial effects of antibiotics, to a larger extent, ciprofloxacin. The most remarkable protective effect was observed for the extracts of Chamerion (Epilobium) angustifolium, Filipendula vulgaris, Tanacetum vulgare and Serratula coronata. These extracts increased the MICs of ciprofloxacin by four and more times. In case of kanamycin, extracts of Artemisia austriaca and Artemisia pontica increased MICs by four and eight times, respectively. Polyphenol quercetin also caused protective effect against ciprofloxacin, increasing the MIC by four times. A positive correlation was found between protective effects of polyphenols and extracts and their antioxidant activity. CONCLUSION: Medicinal plant extracts and polyphenols may protect cells of E. coli against antibiotic toxicity. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this study may be used to enhance the efficiency of antibacterial therapies.

Assessment of anti-oxidant activity of plant extracts using microbial test systems.

AIMS: To evaluate the anti-oxidant properties of extracts from 20 medicinal herbs growing in western Siberia using microbial test systems and different in vitro methods. METHODS AND RESULTS: In vivo anti-oxidant activity of extracts was evaluated for their capacity to protect bacteria, Escherichia coli, against bacteriostatic and bactericidal effects of H(2)O(2) and menadione, and action on anti-oxidant gene expression. In vitro anti-oxidant activity has been examined by a number of methods including: the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH(*))-scavenging assay, chelating activity and capacity to protect plasmid DNA against oxidative damage. In addition, total polyphenol content was determined. The extracts of Fragaria vesca, Rosa majalis, Pentaphylloides fruticosa, Alchemilla vulgaris and Pulmonaria mollis possessed the highest levels of anti-oxidant activity in vivo and in vitro. The protective properties were more closely related to the DPPH(*) radical-scavenging activity, tannin content and action on anti-oxidant gene expression than to other parameters. CONCLUSION: The extracts of medicinal plants may have anti-oxidant effects on bacteria simultaneously through several different pathways, including direct inhibition of reactive oxygen species, iron chelation and anti-oxidant genes induction. SIGNIFICANCE AND IMPACT OF THE STUDY: Using microbial test systems, we revealed herbs that may be used as potential sources of natural anti-oxidants.

[The antioxidant characteristics of medicinal plant extracts from Western Siberia].

An antioxidant activity of the water-alcohol extracts of leaves of ten herbs from Western Siberia was studied. In vivo the capability of extracts to protect cells of Escherichia coli against the bacteriostatic action of H2O2 and the influence of the extracts on the expression of the antioxidant gene katG coding catalase-hydroperoxidase I were investigated. In vitro the radical-binding activity with DPhPG (1,1-diphenyl-2-picrylhydrazyl radical), the chelating capability with ferrozine, and total composition of flavonoids and tannins were determined. The extracts of Filipendula stepposa and Limonium gmelinii were characterized by the highest antioxidant activity. According to data, the test extracts could have an antioxidant effect on bacteria in different ways at once including the direct inhibition of ROS (reactive oxygen species), iron ion chelation and antioxidant gene induction.

[Effect of heparin on the ultrastructure of the fascicular and reticular zones of the adrenal cortex of rats]. / Vliianie geparina na ul'trastrukturu puchkovoi i setchatoi zon nadpochechnikov krys.

The effect of a prolonged use of heparin on the ultrastructure of the zona fasciculata and zona reticulosa of the adrenal cortex was studied in experiment. Heparin was injected subcutaneously to laboratory male rats at a daily dose of 5 mg/kg. The animals were decapitated on the 5th, 10th, 30th and 60th days after heparin administration, 20 and 50 days after 10-day use of the drug and 30 days after 30-day use. In the first days of use heparin stimulated the secretory activity of cells of the zona fasciculata and zona reticulosa of the adrenal cortex. The ultrastructure of the internal area of the zona fasciculata and zona reticulosa indicated the suppression of adrenocorticocytes during the use of heparin for 30 days. In 60-day administration of heparin the ultrastructure of adrenocorticocytes was closer to the control though in cells of the zona fasciculata the content of glycogen exceeded the normal one. In cancelling the drug the adrenal structure got back to normal rather slowly.

[Comparison of subcellular changes in the adrenocortical glomerular zone induced by heparin and its diuretic effect]. / Sopostavlenie subkletochnykh izmenenii v klubochkovoi zone kory nadpochechnikov, vyzvannykh vedeneim geparina, s ego diureticheskim deistviem.

The experiments were carried out on 420 non-inbred male rats. Heparin was injected subcutaneously in doses of 2.5, 5 and 10 mg/kg a day. The animals were decapitated on the 1st, 5th, 10th, 30th and 60th day after the drug administration, as well as 20 and 50 days following 10-day heparin injection and 30 days after 30-day use of the drug. Changes, developed in the adrenocortical glomerular zone after a long-term heparin administration, were studied by means of light and electron microscopy. Morphological data were compared with the changes, that occurred in spontaneous diuresis and the running water- and saline-induced diuresis or natriuresis. The initial heparin-produced ultrastructural changes in the adrenocortical glomerular zone cells indicate the hormone synthesis and release activation, accompanied by a decrease in spontaneous diuresis and natriuresis and the development of high renal sensitivity to antidiuretic hormone. Morphological signs of a decrease in the glomerular zone hormone-forming cell activity are seen in the adrenals after prolonged heparin use (by the 10th day). Spontaneous diuresis proportion continuously rises but does not correlate with natriuresis. The renal response to antidiuretic hormone changes and sensitivity to adrenaline are reduced. From the 30th day the cholesterol depot tends to gradual restoration. Ultrastructural of the adrenocortical glomerular zone returns to normal quite slowly after the drug withdrawal.

[Histoautoradiographic study of thymidine-3H incorporation into the parenchymal nuclei of the kidneys and other organs in rats with nephrotoxic nephritis]. / Gistoavtoradiograficheskoe issledovanie vkliucheniia timidina-3H v iadra parenkhimy pochek i drugikh organov krys s nefrotoksicheskim nefritom.

The features of changes in the index of thymidine-3H incorporation into the renal parenchyma in nephrotoxic nephritis are compared to other organs. In the kidneys the index of incorporation inthe epithelial cells of the renal cortex was 7.5-fold and in the brain cortex epithelium 15-fold as increased, respectively. The number of labeled glomerular cells was 2.5-fold as increased. In glomerulonephritis, the index of thymidine-3H incorporation in the epithelium of the adrenals, liver, goiter gland and small intestine lowered within 30-80% from normal.

[Age and the course of nephrotoxic nephritis in rats]. / Nekotorye vozrastnye osobennosti techeniia nefrotoksicheskogo nerfrita u krys.

In experiments on two groups of mongrel rats (4 weeks old and 4 months old) with induced nephrotoxic nephritis it was revealed that in comparison with adult rats the course of nephritis in ratlings was characterized by lesser proteinuria, selective in nature, by lesser reducticn of endogenous creatinine clearance and diuresis. The acido- and ammo-niogenesis decreased in ratlings and adult rats to the same extent. Morphological changes in the kidneys of ratlings were less pronounced than in adult animals, and were mostly localized in the convoluted tubules. The level of DNA-synthetic activity of the epithelial nuclei of the glomeruli prevailed over this index of the convoluted tubules epithelium. The weight index of the kidneys increased less in ratlings with nephritis than in adult rats. beta-lipoproteinemia in ratlings increased 8 times. Normalization of the urine and blood indices occurred more rapidly in ratlings than in adult rats.

[Effect of heparin on the activity of liver microsome oxidative enzyme systems in healthy rats and rats with experimental glomerulonephritis]. / Vliianie geparina na aktivnost' okislitel'nykh fermentnykh sistem mikrosom pecheni u zdorovykh krys i krys s éksperimental'nym gloverulonefritom.

In experiments on mongrel rats it was found that heparin in doses of 2, 5, and 10 mg/kg had an inducing effect on the oxidative systems of hepatic microsomes: hexenal test period was shortened, cytochrome P450 content increased, relative liver weight rose; the activity of histochemically-detectable NAD-enzymes of hepatocytes became greater. Heparin was capable of considerable (2-3-fold) stimulation of antitoxic activity of the liver reduced in experimental glomerulonephritis. The effect of heparin on the antitoxic function of the liver did not correlate with its effect, on the blood coagulation system.

[Experimental study of azathioprine in nephrotoxic nephritis in rats]. / Eksperimental'noe izuchenie azatioprina pri nefrotoksicheskom nefrite u krys.

In tests conducted with 165 mongrel sexually mature and immature rats it is shown that azathioprine used in nephrotoxic nephritic improves the general condition, reduces the edema of subcutaneous cellular tissues, as well as the intensity of proteinuria and helps retaining its selective type, lessens the degree of hypo- and dpsproteinemia and, especially, of hyper-beta-lipoproteinemia; in the kidneys the pathomorphological changes characteristic of nephritis become less marked. Azathioprine does not influence the process of acido-and ammoniogeness in the tubuloar system of the nephron, nor does it modify diuresis. The effect of azathioprine is most spectacular in the acive phase of developing nephritis. In rattlings with nephritis theaction af azathioprine in regard to a number of factors (proteins, beta-lipoproteids, gamma-globulins of the blood) is somewhat stronger than in the sexually mature rats.

[Functional and structural myocardial changes in experimental glomerulonephritis]. / Funktsional'no-strukturnye izmeneniia miokarda pri éksperimental'nom glomerulonefrite.

Functional structural changes in the myocardium in different developmental phases of nephrotoxic glomerulonephritis were studied in rats. Electrocardiography, electron microscopy, and biochemical study of respiration, linked with oxidative phosphorylation, by polarography in the fraction of mitochondria isolated by differential centrifugation were employed. In experimental glomerulonephritis the ECG shifts were attended with diminished oxidative phosphorylation in the myocardial mitochondria, destructive changes in the cardiomyocytes (disorganization of mitochondria, myofibrils, endoplasmic reticulum), loosening and swelling of the basilar membranes, and changes and swelling in the capillaries and interstitium. The functional structural changes in the heart are reversible in character but persist for a longer period of time than the clinical manifestations of glomerulonephritis.

[Subcellular changes in rat myocardium in nephrotoxic glomerulonephritis]. / Subkletochnye izmeneniia v miokarde krys pri nefrotoksicheskom glomerulonefrite

Disorganization of the mitochondria, myofibrillae, sarcolemma, intra- and intercellular edema, swelling and pyknosis of the endothelium, capillary obstruction by the blood elements, thickening of the basal membranes were revealed in the myocardium of rats with Mazugi nephritis. The maximum changes were observed on the 10--20th day after the onset of the reproduction of glomerulonephritis; the intracellular regenerative processes became intensified from the 20th day. There was a correlation in the dynamics of the subcellular histological and clinical manifestations of glomerulonephritis.

[The state of several indices of non-specific immunity in rats with nephrotoxic glomerulonephritis]. / Sostoianie nekotorykh pokazatelei nespetsificheskogo immuniteta pri nefrotoksicheskom glomerulonefrite

Changes in the interferon reaction of leukocytes, bactericidal property of the blood serum against the E. coli and streptococcus, the activity of beta-lysins in experimental nephrotoxic glomerulonephritis reproducible with the aid of heterogenous nephrotoxic serum in mongrel male rats were studied. This model permitted to trace the changes in the nonspecific protection mechanisms depending on the pathological process in the kidneys. In nephrotoxic glomerulonephritis the most pronounced changes were seen in the interferon reaction of leukocytes: it decreased up to 90% in comparison with the normal depending on the duration of the disease. In difference from this the changes in the anti-bacterial immunity indices were observed at the period of marked nephrotic process activity.