The Role of Antioxidant Systems in the Response of Escherichia colito Heat Shock

Shifting the temperature from 30 to 45°C in an aerobic Escherichia coliculture inhibited the expression of the antioxidant genes katG, katE, sodA, and gor.The expression was evaluated by measuring -galactosidase activity in E. colistrains that contained fusions of the antioxidant gene promoters with the lacZoperon. Heat shock inhibited catalase and glutathione reductase, lowered the intracellular level of glutathione, and increased its extracellular level. It also suppressed the growth of mutants deficient in the katG-encoded catalase HPI, whereas the sensitivity of the wild-type andsodA sodBmutant cells to heat shock was almost the same. In the E. coliculture adapted to growth at 42°C, the content of both intracellular and extracellular glutathione was two times higher than in the culture grown at 30°C. The temperature-adapted cells grown aerobically at 42°C showed an increased ability to express the fused katG–lacZgenes.     

Connection of HindIII-polymorphism in the lipoprotein lipase gene with myocardial infarct and life span in elderly ischemic heart disease patients

Allele and genotype frequencies of the HindIII polymorphism of the lipoprotein lipase (LPL) gene were studied in patients with myocardial infarction (MI) and stable angina of effort (SAE), including long-lived people (over 90). The polymorphism proved to be associated with MI and with the life span, genotype H+/H+ being predisposing to MI and allele H- being protective. The allele and genotype frequencies of long-lived people differed significantly from the Hardy-Weinberg proportions and from those of SAE patients aged up to 90. An excess of heterozygotes in this group suggests a selective pressure which eliminates homozygotes. Possibly, heterozygotes H+/H- have an adaptive advantage, which provides for their longevity.     

A noninvasive approach to studying fetal cells for prenatal diagnosis of chromosomal aneuploidies

Fetal cells isolated from maternal peripheral blood during the second trimester of pregnancy were analyzed. Blood samples were centrifuged in a Ficoll-Paque gradient, the mononuclear cell fraction was isolated and stained with fluorescent monoclonal antibodies against glycophorine A (GPA + PE), transferrin (CD71 + FITC), and Hoechst 33342. Fluorescence-activated cell sorting (FACS) was conducted on a Vantage flow cytofluorimeter (Becton Dickinson). Fluorescence in situ hybridization (FISH) with Y chromosome-specific DNA probe revealed fetal cells that exhibited Y signal in all 20 blood samples obtained from women pregnant with healthy male fetuses. The concentration of these fetal cells averaged about 1.34% and ranged from 0.1 to 4.2% in different blood samples. In six cases, blood samples were obtained from pregnant women, in which prenatal cytogenetic analysis revealed various fetal aneuploidies. Using FISH with DNA probes specific for chromosomes X, 18, and 13/21, Fetal cells with chromosomal aberrations were detected in these six maternal blood samples at a concentration from 1.5 to 5.6% (on average 3.7%). These results indicate the possibility of a new noninvasive approach, which is safe for both mother and fetus when used for isolation of fetal cells from pregnant women's blood samples and prenatal diagnosis of a broad spectrum of fetal cell chromosomal aberrations.     

Examination of the reaction of fully reduced cytochrome oxidase with hydrogen peroxide by flow-flash spectroscopy

The reaction of cytochrome c oxidase with hydrogen peroxide has been of great value in generating and characterizing oxygenated species of the enzyme that are identical or similar to those formed during turnover of the enzyme with dioxygen. Most previous studies have utilized relatively low peroxide concentrations (millimolar range). In the current work, these studies have been extended to the examination of the kinetics of the single turnover of the fully reduced enzyme using much higher concentrations of peroxide to avoid limitations by the bimolecular reaction. The flow-flash method is used, in which laser photolysis of the CO adduct of the fully reduced enzyme initiates the reaction following rapid mixing of the enzyme with peroxide, and the reaction is monitored by observing the absorbance changes due to the heme components of the enzyme. The following reaction sequence is deduced from the data. (1) The initial product of the reaction appears to be heme a(3) oxoferryl (Fe(4+)=O(2)(-) + H(2)O). Since the conversion of ferrous to ferryl heme a(3) (Fe(2+) to Fe(4+)) is sufficient for this reaction, presumably Cu(B) remains reduced in the product, along with Cu(A) and heme a. (2) The second phase of the reaction is an internal rearrangement of electrons and protons in which the heme a(3) oxoferryl is reduced to ferric hydroxide (Fe(3+)OH(-)). In about 40% of the population, the electron comes from heme a, and in the remaining 60% of the population, Cu(B) is oxidized. This step has a time constant of about 65 micros. (3) The third apparent phase of the reaction includes two parallel reactions. The population of the enzyme with an electron in the binuclear center reacts with a second molecule of peroxide, forming compound F. The population of the enzyme with the two electrons on heme a and Cu(A) must first transfer an electron to the binuclear center, followed by reaction with a second molecule of peroxide, also yielding compound F. In each of these reaction pathways, the reaction time is 100-200 micros, i.e., much faster than the rate of reaction of peroxide with the fully oxidized enzyme. Thus, hydrogen peroxide is an efficient trap for a single electron in the binuclear center. (4) Compound F is then reduced by the final available electron, again from heme a, at the same rate as observed for the reduction of compound F formed during the reaction of the fully reduced oxidase with dioxygen. The product is the fully oxidized enzyme (heme a(3) Fe(3+)OH(-)), which reacts with a third molecule of hydrogen peroxide, forming compound P. The rate of this final reaction step saturates at high concentrations of peroxide (V(max) = 250 s(-)(1), K(m) = 350 mM). The data indicate a reaction mechanism for the steady-state peroxidase activity of the enzyme which, at pH 7.5, proceeds via the single-electron reduction of the binuclear center followed by reaction with peroxide to form compound F directly, without forming compound P. Peroxide is an efficient trap for the one-electron-reduced state of the binuclear center. The results also suggest that the reaction of hydrogen peroxide to the fully oxidized enzyme may be limited by the presence of hydroxide associated with the heme a(3) ferric species. The reaction of hydrogen peroxide with heme a(3) is very substantially accelerated by the availability of an electron on heme a, which is presumably transferred to the binuclear center concomitant with a proton that can convert the hydroxide to water, which is readily displaced.     

Effect of L-lysine-alpha-oxidase on skin carcinoma induced by methylcholanthrene in mice]

Effect of enzyme L-lisyne-a-oxidase in complex with gel (Sakap) on carcinoma of the skin of mice induced by methylcholantrene was studied. Gel application once daily during 3 weeks decreased carcinoma dimensions on 40 per cent.     

The immunoregulatory and allergy-associated cytokines in the aetiology of the otitis media with effusion

Inflammation in the middle ear mucosa, which can be provoked by different primary factors such as bacterial and viral infection, local allergic reactions and reflux, is the crucial event in the pathogenesis of otitis media with effusion (OME). Unresolved acute inflammatory responses or defective immunoregulation of middle inflammation can promote chronic inflammatory processes and stimulate the chronic condition of OME. Cytokines are the central molecular regulators of middle ear inflammation and can switch the acute phase of inflammation in the chronic stage and induce molecular-pathological processes leading to the histopathological changes accompanying OME. In this review we present cytokines identified in otitis media, immunoregulatory [interleukin (IL)-2, IL-10, transforming growth factor-beta]) and allergy associated (IL-4, IL-5, granulocyte-macrophage colony-stimulating factor), as crucial molecular regulators, responsible for chronic inflammation in the middle ear and the chronic condition of OME.     

Polar Constituents of Brown Seaweed Colpomenia peregrina (Sauv.) Hamel from the Black Sea

GC-MS of trimethylsilyl derivatives of the compounds present in the butanolic extract of biomass of brown seaweed Colpomenia peregrina from the Black Sea aided in identification of 24 components, including aliphatic hydroxy and keto and aromatic acids, glycerol, mannitol, floridoside, and monosaccharides. The polysaccharide composition of the biomass was also studied, with high sodium alginate and laminaran contents and a comparatively low level of fucoidan being revealed. The polysaccharides were isolated from the biomass by fractional extraction and purified by precipitation or ion exchange chromatography. The structures of alginic acid and laminaran were deduced from ¹³C NMR spectra and confirmed, in the case of laminaran, by methylation analysis. The sodium alginate was shown to contain more guluronic (G) than mannuronic acid (M) residues, the M/G ratio being 0.48. Laminaran was demonstrated to be a -glucan with 1 3 linkages in its backbone and 1 6 linkages in its branching points, which is characteristic of brown algae. Fucoidan turned out to be a complex heteropolysaccharide containing, in addition to fucose and sulfate, other neutral monosaccharides and uronic acids.     

The alternative oxidase of Yarrowia lipolytica mitochondria is unable to compete with the cytochrome pathway for electrons

The activity of the cyanide-resistant alternative oxidase (pathway) of Y. lipolytica mitochondria was studied as a function of the activity of the major, cyanide-sensitive, cytochrome pathway. The contribution of the alternative oxidase to the total respiration of mitochondria was evaluated by measuring the rate of oxygen consumption in the presence of cyanide (an inhibitor of the cytochrome pathway). The potential activity of the cytochrome pathway was evaluated spectrophotometrically, by measuring the oxidation rate of cytochrome c by ferricyanide, which accepts electrons from complex III (cytochrome c) of this pathway. The oxidation of succinate by mitochondria in the presence of ferricyanide and cyanide was accompanied by oxygen consumption due to the transfer of electrons through the alternative pathway. The subsequent addition of ADP or FCCP (an uncoupler of oxidative phosphorylation in the cytochrome pathway) completely inhibited the consumption of oxygen by the mitochondria. Under these conditions, the inhibition of the alternative pathway by benzohydroxamic acid failed to affect the transfer of electrons from cytochrome c to ferricyanide. Benzohydroxamic acid did not influence the rate of ferricyanide reduction by the cytochrome pathway occurring in controlled state 4, nor could it change the phosphorylation quotient ATP/O upon the oxidation of various substrates. These findings indicate that the alternative pathway is unable to compete with the cytochrome respiratory chain for electrons. The alternative pathway transfers only electrons that are superfluous for the cytochrome chain.