Effect of HS and cysteine homeostasis disturbance on ciprofloxacin sensitivity of Escherichia coli in cystine-free and cystine-fed minimal medium.

Endogenous HS has been proposed to be a universal defense mechanism against different antibiotics. Here, we studied the role of HS transiently generated during ciprofloxacin (CF) treatment in M9 minimal medium with sulfate or produced by E. coli when fed with cystine.

Regulation of Cysteine Homeostasis and Its Effect on Sensitivity to Ciprofloxacin in LB Medium.

Cysteine and its derivatives, including HS, can influence bacterial virulence and sensitivity to antibiotics. In minimal sulfate media, HS is generated under stress to prevent excess cysteine and, together with incorporation into glutathione and export into the medium, is a mechanism of cysteine homeostasis. Here, we studied the features of cysteine homeostasis in LB medium, where the main source of sulfur is cystine, whose import can create excess cysteine inside cells.

Influence of Growth Medium Composition on Physiological Responses of to the Action of Chloramphenicol and Ciprofloxacin.

The ability of hydrogen sulfide (HS) to protect bacteria from bactericidal antibiotics has previously been described. The main source of HS is the desulfurization of cysteine, which is either synthesized by cells from sulfate or transported from the medium, depending on its composition. Applying electrochemical sensors and a complex of biochemical and microbiological methods, changes in growth, respiration, membrane potential, SOS response, HS production and bacterial survival under the action of bactericidal ciprofloxacin and bacteriostatic chloramphenicol in commonly used media were studied.

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.

Study of antioxidant activity of fodder grasses using microbial test systems.

Aim: To measure the biological activities of extracts of fodder grasses Onobrýchis arenária, Galéga orientális and Rhaponticum carthamoides that are commonly planted in Europe, Middle East and eastern Africa.

Methods And Results: Microbial test-systems based on Escherichia coli BW25113 that allow measurement of gene expression, growth and survival, biofilm formation (BF) in combination with the standard chemical procedures were used. The extracts studied had radical scavenging and metal-chelating activities and induced expression of antioxidant genes via generation of hydrogen peroxide.

Tannic and gallic acids alter redox-parameters of the medium and modulate biofilm formation.

Tannic (TA) and gallic (GA) acids are known to have both anti- and prooxidant properties however recently they have been described as potential anti-biofilm agents although their mechanisms of action on bacterial cells remain obscure. The aim of our research was to elucidate the role of prooxidant actions of these plant phenolic compounds in bactericidal effects and biofilm formation. In our experiments, both compounds demonstrated strong oxidative properties that altered activity of stress regulons and contributed to decrease of CFU and ability of cells to maintain membrane potential.

Medicinal plant extracts can variously modify biofilm formation in Escherichia coli.

Low concentrations of black tea and water extracts from medicinal plants Arctostaphylos uva-ursi, Vaccinium vitis-idaea, Tilia cordata, Betula pendula and Zea mays stimulated biofilm formation in Escherichia coli BW25113 up to three times. Similar effect was observed for tannic acid and low concentrations of quercetin. In contrast, the extract from Urtica dioica reduced biofilm production.

Medicinal plant extracts variously modulate susceptibility of Escherichia coli to different antibiotics.

Antioxidant activity of green and black tea and extracts of medicinal plants and their ability to modulate antibiotic susceptibility in Escherichia coli were studied. Among a number of extracts tested the maximal capacity to scavenge DPPH radicals and chelate iron in chemical tests was found in green and black tea, Arctostaphylos uva-ursi and Vaccinium vitis-idaea. These extracts contained high level of polyphenols and in aerobic conditions exhibited prooxidant features, producing H2O2 and inducing expression of the katG gene encoding catalase HPI in E.

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).

[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.

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.

[Effect of heparin on the ultrastructure of the fascicular and reticular zones of the adrenal cortex of rats].

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.

[Comparison of subcellular changes in the adrenocortical glomerular zone induced by heparin and its diuretic effect].

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.

[Histoautoradiographic study of thymidine-3H incorporation into the parenchymal nuclei of the kidneys and other organs in rats with nephrotoxic nephritis].

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.

[Age and the course of nephrotoxic nephritis in rats].

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.

[Effect of heparin on the activity of liver microsome oxidative enzyme systems in healthy rats and rats with experimental glomerulonephritis].

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].

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.

[Functional and structural myocardial changes in experimental glomerulonephritis].

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.

[Subcellular changes in rat myocardium in nephrotoxic glomerulonephritis].

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].

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.