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PubMed2001

Oxidative processes in human promonocytic cells (THP-1) after differentiation into macrophages by incubation with Chlamydia pneumoniae extracts.

Human monocytes differentiated into macrophages by Chlamydia pneumoniae were able to oxidize blood lipoproteins, as discovered by Kalayoglu et al. (1998). Using a model of human promonocytic cells (THP-1), the cells were differentiated into macrophages by preincubation with C. pneumoniae extract, and further stimulated by phorbol myristate acetate. In these conditions, the differentiated cells oxidized a thiol compound and released superoxide anion as demonstrated respectively by gas liquid chromatography and electron spin resonance. The thiol oxidation and superoxide anion release were inhibited by diphenyliodonium, a NADPH oxidase and NOsynthase inhibitor, proving that the respiratory burst and the NOsynthase were involved in the oxidation processes occurring in the differentiated THP-1. The role of H(2)O(2) (derived from superoxide anion) was indicated by the enhancing effect of a peroxidase on the thiol oxidation. The presence of alpha-tocopherol in the surrounding medium strongly diminished the oxidation of the thiol target.

Anti-Bacterial Agents↗
PubMed2001

Metabolic modelling of full-scale biological nitrogen and phosphorus removing wwtp's.

This paper evaluates the experiences with modelling full-scale biological phosphorus and nitrogen removing wastewater treatment plants. For the simulation, we used a metabolic phosphorus model integrated in ASM2d, further referred to as TUDP-model. It was found that the metabolic model for bio-P removal can be applied for modelling full-scale wwtp's, without extensive parameter adjustments. A stepwise modelling approach was proposed. Only three specific parameters were calibrated. Two parameters, the inert fraction in the influent and the actual anoxic sludge fraction will need calibration for all systems. Parameter sensitivity analyses showed that the sensitivity of operational data, often considered as known input data, is high. The model kinetics were found less sensitive. This will in general be the case for all low-loaded wwtp's recorded in their pseudo-steady state. Based on mass balance calculations, operational data and measurements were evaluated. Since all terms on a phosphorus balance can be measured, errors in operational data (e.g. SRT and flow rates) become very apparent in P-removal models (ASM2d, TUDP). We suggest using the P-balance in general for wwtp modelling, as a check on data consistency. This study showed that considering operational data per definition as known input data is not justified. Therefore, operational data should be evaluated, or considered in model calibration over the use of kinetic and stoichiometric parameters.

Aerobiosis↗
PubMed2005

Heterocyclic thionates as a new class of bridging ligands in oxo-centered triangular cyclopentadienylchromium(III) complexes.

The interactions of the benzothiazolate complex, CpCr(CO)(2)(SCSN(C(6)H(4))) (2), and the tetrazole thiolate complex, CpCr(CO)(3)(eta(1)-SCN(4)Ph) (3), with controlled amounts of Me(3)OBF(4) and (MeO)(2)SO(2), respectively, produced the corresponding mu(3)-oxo trinuclear thionate-bridged complexes, [Cp(3)Cr(3)(mu(2)-OH)(mu(3)-O)(mu(2)-eta(2)-SCSN(C(6)H(4)))(2)](5)BF(4) (45%) and [Cp(3)Cr(3)(mu(2)-OH)(mu(3)-O)(mu(2)-eta(2)-SCN(4)Ph)(2)](9)(MeOSO(3)) (53%), together with their respective free dimethylated thiolate ligands, [MeSCSNMe(C(6)H(4))](4)BF(4) and (Me(2)SCN(4)Ph)(8)MeOSO(3). The reaction of 3 with Me(3)OBF(4) resulted in the isolation of a binuclear complex, [Cp(2)Cr(2)(mu-OH)(mu-eta(2)-SCN(4)Ph)(2)](7)BF(4) (43%), and (8)BF(4) (27%). The reaction of the thiopyridine complex, CpCr(CO)(2)(SPy) (4), with I(2) also produced a similar mu(3)-oxo complex 10 (31%), together with CpCrI(2)(THF) (11) and the disulfide (SPy)(2). Similar reactions with 2 and 3 and I(2) yielded species 5 and 7, together with 11 and disulfides derived from their respective ligands. Cyclic voltammograms recorded in solutions of 5 and 9 indicated that the compounds could be reduced and oxidized at very similar potentials. An EPR spectrum characteristic of a compound with axial symmetry was obtained for 9 at 7 K. Single-crystal X-ray diffraction analyses confirmed that species 7 is dinuclear, whereas 5 and 9 are structural trinuclear analogues, each containing a mu(3)-oxo central core.

Chromium↗
PubMed2004

Modulation by flavonoids of DNA damage induced by estrogen-like compounds.

Reactive oxygen species (ROS) are produced by a wide variety of exogenous chemicals and metabolic processes and cause a broad spectrum of damage to biological systems. As a consequence, ROS react with DNA, among many other biological targets, disrupting its structure and functionality. Estrogen-like compounds mediate DNA damage by ROS generation, implying that their effects can be modulated by antioxidants such as catalase, superoxide dismutase, and vitamin C. We examined DNA damage in human lymphocytes and sperm after treatment with four estrogen-like compounds (beta-estradiol, diethylstilbestrol, daidzein, and genistein) and its modulation by flavonoids (quercetin and kaempferol) using the Comet assay. The results indicated that quercetin and kaempferol reduced the DNA damage produced in sperm and lymphocytes by the four estrogenic compounds. The flavonoids also reduced the DNA damage induced by hydrogen peroxide, which was used as a positive control. Our results demonstrate that the antioxidant properties of flavonoids can protect the integrity of human sperm and lymphocyte DNA from ROS induced by estrogenic compounds.

Antineoplastic Agents↗
PubMed2004

Isolation and characterization of Xanthobacter polyaromaticivorans sp. nov. 127W that degrades polycyclic and heterocyclic aromatic compounds under extremely low oxygen conditions.

Two bacterial strains, 127W and T102, were isolated from anoxic crude oil tank sludge as effective degraders of dibenzothiophene (DBT), a model sulfur containing heterocyclic aromatic compound in crude oil. Strain 127W was more tolerant to oxygen limitation than T102 and was capable of degrading two- and three-ring polycyclic and heterocyclic aromatic compounds under both aerobic and low oxygen conditions. Strain 127W degraded 0.082, 0.055, and 0.064 mM of DBT, naphthalene, and anthracene, respectively, in one week with dissolved oxygen < or =0.2ppm (0.006 mM). Degradation by 127W cell-free extracts for DBT was increased by addition of sodium hydrogencarbonate under this oxygen concentration. Phylogenetic analysis of the 16S rRNA gene sequence and physiological characteristics indicate that the strains 127W and T102 belong to new species of the genus Xanthobacter and Pseudomonas stutzeri, respectively. We propose X. polyaromaticivorans sp. nov. 127W.

Biodegradation, Environmental↗
PubMed1997

Magnesium inhibits nickel-induced genotoxicity and formation of reactive oxygen.

Nickel compounds are recognized to cause nasal and lung cancers. Magnesium is an effective protector against nickel-induced carcinogenesis in vivo, although its mechanisms of protection remain elusive. The effects of magnesium carbonate on the cytotoxicity and genotoxicity induced by nickel subsulfide were examined with respect to the inhibition of cell proliferation, micronuclei formation, DNA-protein cross-link formation, and intranuclear nickel concentration. The generation of reactive oxygen by nickel chloride was also analyzed by observing 8-hydroxy-deoxyguanosine formation from deoxyguanosine in the presence and absence of magnesium chloride. The suppression of up to 64% of the proliferation of BALB/3T3 fibroblasts by nickel subsulfide (1 microgram/ml) was reversed by magnesium. The nickel compound increased not only the number of micronuclei but also the amount of DNA-protein cross-links examined with CHO and BALB/3T3 cells, respectively. These genotoxic effects of nickel were again lessened by magnesium carbonate. In addition, the cellular accumulation of nickel increased 80-fold with nickel subsulfide treatment and decreased with magnesium carbonate treatment. Nickel also enhanced 8-hydroxy-deoxyguanosine formation in the presence of H2O2 and ascorbic acid, where magnesium played another suppressive role. In fact, inhibition by magnesium was still observed even in the absence of nickel treatment. These results suggest that the protective role of magnesium in nickel-induced cytotoxicity and genotoxicity can be attributed to its ability to reduce either the intracellular nickel concentration or reactive oxygen formation.

Animals↗
PubMed1999

Routine disinfection of patients' environmental surfaces. Myth or reality?

We have evaluated the need for daily disinfection of environmental surfaces not contaminated by biological fluids, in patient areas of a medical unit with two wings [North (N) and South (S)] at the University Hospitals of Geneva, Switzerland. Weekly bacteriological monitoring of surfaces was carried out at random (N = 1356 samples). In the S wing (control), we used detergent/disinfectant for daily cleaning of the floors and furniture. In the N wing we began by using a detergent for floors and furniture; after four weeks the results suggested changing to a rotation of detergent, dust attracting disposable dry mops and disinfectant. During this period the furniture was cleaned with an active oxygen-based compound. The average differences in contamination before and after cleaning floors were (mean reduction in bacterial counts and 95% confidence intervals; CI95): disposable mops: 92.7 cfu/24 cm2 (CI95; 74-112), active oxygen based compound 111.1 (90-133), and quaternary ammonium compound -0.6 (-27-26). Use of detergent alone was associated with a significant increase in bacterial colony counts: on average by 103.6 cfu (CI95 73-134). The quaternary ammonium compound was inadequate for disinfecting bathrooms and toilets but the active oxygen based compound was satisfactory. For furniture, there was a significant reduction in bacterial counts with both the methods using disinfectants. As the detergent was contaminated, by using it alone for cleaning, we were actually seeding surfaces with bacteria. A total of 1117 patients was studied and we observed no change in the incidence of nosocomial infections during the four months of the trial. In conclusion, uncontrolled routine disinfection of environmental surfaces does not necessarily make it safe for the patient and could seed the environment with potential pathogens.

Analysis of Variance↗
PubMed2002

Yield prediction and stoichiometry of multi-step biodegradation reactions involving oxygenation.

Microorganisms can initiate the degradation of organic compounds by oxygenation reactions that require the investment of energy and electrons. This diversion of energy and electrons away from synthesis reactions leads to decreased overall cell yields. A thermodynamic method was developed that improves the accuracy of cell yield prediction for compounds degraded through pathways involving oxygenation reactions. This method predicts yields and stoichiometry for each step in the biodegradation pathway, thus enabling modeling a multi-step biodegradation process in which oxygenations occur and intermediates may persist. EDTA and benzene biodegradation are presented as examples. The method compares favorably with other yield prediction methods while providing additional information of yields for intermediates produced in the degradation pathway.

Benzene↗
PubMed1988

Partition of portal-drained visceral net flux in beef steers. 1. Blood flow and net flux of oxygen, glucose and nitrogenous compounds across stomach and post-stomach tissues.

1. Blood from chronic indwelling catheters in the caudal aorta and anterior mesenteric, gastrosplenic and hepatic portal veins was used to measure blood flow and net flux of oxygen, glucose and nitrogenous compounds across hepatic portal-drained viscera (PDV), post-stomach (anterior mesenteric-drained viscera (MDV] and stomach tissues of two beef steers (390 kg mean live weight). 2. Steers were fed in sequence on (1) chopped lucerne (Medicago sativa) hay (twelve meals/d), (2) chopped lucerne hay (two meals/d) and (3) a pelleted concentrate diet containing 780 g ground maize/kg (two meals/d). The lucerne hay and concentrate contained 26.5 and 16.8 g nitrogen/kg respectively. 3. Five measurements of net flux (blood flow multiplied by venous-arterial concentration differences (VA] were obtained hourly on 2 d for each dietary regimen, beginning 0.5 h before feeding at 08.00 hours. Blood flow was measured by downstream dilution of p-aminohippurate (PAH). 4. Blood flow across MDV averaged 42% of PDV blood flow (665 litres/h). 5. Net use of O2 across MDV accounted for 51% of net PDV use of O2 (920 mmol/h). This disproportionate use of O2 in relation to blood flow was due to greater VA for O2 across MDV than across stomach tissues. Dietary regimen had no effect on the proportions of PDV blood flow and net O2 consumption attributable to MDV or stomach tissues. 6. When lucerne was given, net glucose use across MDV represented 69% of PDV use (35 mmol/h). When concentrate was given, MDV glucose use switched to net absorption (29 mmol/h), reducing net PDV glucose use to 1 mmol/h. 7. When concentrate was given, net MDV absorption of alpha-amino-N (AAN) increased from 98 to 190 mmol/h, yet net PDV absorption (101 mmol/h) was not affected. Net stomach AAN flux increased from -7 to -69 mmol/h when concentrate was given, negating the increase in net MDV absorption. 8. Net absorption of ammonia-N across MDV represented 28 and 52% of net PDV absorption when lucerne and concentrate were given respectively. Net NH3-N absorption across PDV was lower when lucerne was given than when concentrate was given (295 v. 154 mmol/h), reflecting lower dietary N intake (153 v. 83 g/d). Net MDV absorption of NH3-N was not affected by diet. Net removal of blood urea-N (BUN) across PDV (101 mmol/h) was not affected by diet. Across MDV, BUN removal was lower when concentrate was given than when lucerne was given (32 v. 77 mmol/h).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2005

Assessment of baseline toxicity of mono-cyclic aromatic compounds by pseudomonas initial oxygen uptake assay.

The objective of this study was to develop quantitative structure-activity relationships (QSARs) for the toxicity of mono-cyclic aromatic compounds in the Pseudomonas putida initial oxygen uptake assay. The QSARs were developed using response-surface based on descriptors for chemical hydrophobicity (logP) and electrophilicity (LUMO). The model log (Ki(-1)=0.434 (+/-0.011) log P-0.389 (+/-0.013) LUMO - 2.13(+/-0.031); n=155, r2=0.941, r2(adj)=0.940, s=0.119, F=1206 led us to conclude that the polar and non-polar narcotics were statistically indistinguishable. Pentafluorophenol, pentachlorophenol and most dinitrophenols classified as weak acid respiratory uncouplers in literature fit well into this model when they were treated as their corresponding phenoxides. This latter result suggests that the action mechanism of these phenols should be reevaluated.

1-Octanol↗
PubMedDate not supplied

Repair of oxidative DNA damage in vitro: a tool for screening antioxidative compounds.

Reactive oxygen species (ROS) provoke the formation of base DNA alterations that are processed by an excision step of the lesion followed by a repair synthesis and ligation step to restore the strand continuity. We have reported previously the detection of DNA adducts by an in vitro chemiluminescence DNA repair synthesis assay (Salles et al., 1995) which allows the measurement of repair synthesis by cell-free extracts in damaged plasmid DNA adsorbed on sensitized microplate wells. The 3D (DNA damage detection) assay was performed in the presence of biotin-dUTP which was incorporated during the repair synthesis step. The extent of repair synthesis was measured in an ELISA reaction with ExtrAvidin-horse radish peroxidase and chemiluminescence detection. The 3D assay allows detection of any type of base alterations including base oxidation. Interestingly, under controlled production of ROS a screening procedure of antioxidants might be carried out with the 3D assay. By taking advantage of plasmid DNA adsorption, oxidative base damage can be recognized by the Escherichia coli Fpg protein which was detected in an ELISA reaction with specific antibody and chemiluminescence measurement (4D assay). With the sceening procedure of antioxidative compounds in mind, the development of such assays and their drawbacks are discussed.

Antioxidants↗