Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Oxygen Compounds”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 253 records · Page 14Linked to original sources
PubMed1999

Synthesis of heterobicyclic nitrogen systems bearing the 1,2,4-triazine moiety as anti-HIV and anticancer drugs: Part I.

Some new heterobicyclic nitrogen systems bearing the 1,2,4-triazine moiety (3-22) have been achieved by treatment of 3-amino-5,6-disubstituted-1,2,4-triazines 2a-h with some cyclic and acyclic oxygen compounds followed by heterocyclization. Structures of the products have been deduced by elemental analysis and spectral data. Significant anti-HIV and anticancer activities were observed in vitro for some members of the series, where compounds 5 and 18 showed a moderate activity.

Anti-HIV Agents↗
PubMedDate not supplied

[Effect of gas phase composition on formation of hydrocarbons by Desulfovibrio desulfuricans].

Changes in the synthesis of extracellular metabolic products generated by sulfate-reducing bacteria Desulfovibrio desulfuricans grown on a lactate-containing mineral medium in the presence of H2 and CO2 at various volume ratios in the gaseous phase were studied. An increase in the amount of extracellular products synthesized by the bacteria was observed at an H2/CO2 ratio of 3:1. High concentrations of molecular hydrogen (80-95%) in the presence of 5-20% CO2 facilitated the synthesis of hydrocarbons (alkanes) whose highest concentrations were produced at an H2/CO2 ratio of 9:1. An increase in the initial CO2 concentration in the gaseous phase above 20% increased the amount of oxygenated compounds in the culture.

Carbon Dioxide↗
PubMedDate not supplied

The essential oil composition of Thymus tosevii and Thymus macedonicus from Bulgaria.

Essential oils composition of Thymus tosevii Velen. and Thymus macedonicus (Deg. et Ur.) Ronn. from Bulgaria were examined by analytical GC and GC-MS techniques. 39 components were separated in the oil of T. tosevii and 22 of them were identified, representing 94.37% of the oil. The most abundant constituents were: terpinyl acetate (43.59%), thymol (11.43%) and nerol (11.72%). More than 70 components were separated in the essential oil of T. macedonicus, 35 were identified, representing 96.03% of the oil. The major components were geranyl acetate (30.00%) and terpinyl acetate (17.30%), followed by lower amounts of nerol (14.25%), linalool (12.94%) and thymol (4.14%). Both examined taxa contained essential oils composed mainly from monoterpene oxygenate compounds while the fractions of monoterpene hydrocarbons as well as sesquiterpene components were very low.

Bulgaria↗
PubMed1992

An 1,2,3-triazole derivative bioisoster of a potent in vitro prostaglandin synthesis inhibitor: preparation and biological activity.

This paper reports the preparation of the triazole ester 10, a methylenic bioisoster of an oxygenated compound A, effective inhibitor of the prostaglandin synthesis in vitro. Biological evaluation of 10 and of the corresponding acid 9 shows that the compounds maintain a good enzymatic inhibitory activity compared with indomethacin and aspirin.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMedDate not supplied

[Urinary MTBE as biological marker of exposure to traffic exhaust fumes].

Methyl tert-butyl ether (MTBE) is an oxygenated compound added to Italian fuel in quantity of about 3% v/v. In the present study the excretion of urinary MTBE (U-MTBE) was evaluated as biomarker of exposure to traffic exhaust fumes. With this aim 127 Milan urban policemen, working as traffic wardens, were investigated. Spot urine samples were obtained prior to and at the end of the work shift, in different seasons. Median U-MTBE varied from 74 to 164 ng/L (range 60-657 ng/L). Comparing the pre-shift and end-shift samples an increase of about 14% in the U-MTBE level during the workshift was observed. An influence of the different seasons was observed, with lower values in spring and higher values in winter. Smoking did not affect the excretion of U-MTBE. The results of this study suggest that U-MTBE is a sensitive and specific marker for the assessment of exposure to traffic exhaust fumes.

Adult↗
PubMed1991

[Cigarette smoke and bronchoepithelium].

Cigarette smoke is known to generate active oxygen species such as O2- and H2O2, and contains a variety of irritants capable of reducing the ciliary beat frequency (CBF). While acute cilio-inhibitory action of cigarette smoke no longer needs to be proved, little is known about the contribution of active oxygen compounds in cigarette smoke on the cilio-inhibitory action. Using cultured rabbit tracheal epithelium in vitro and CBF and the time to ciliostasis were measured by a microphoto-oscillation technique. An extract of cigarette smoke was made by bubbling smoke through 5 ml phosphate buffer saline (PBS) for 5 min. Smoke extract alone (a concentration of 10% and 20%) gave ciliostasis after 37 +/- 6 min and 17 +/- 2 min, respectively. Significantly less toxic was smoke extract (a concentration of 10% and 20%) containing 200 micrograms/ml superoxide dismutase (SOD) and 200 micrograms/ml catalase, and the time to ciliostasis were 62 +/- 5 min and 24 +/- 1 min, respectively. There was no significant difference in terms of the time to ciliostasis between 20% smoke extract alone and 20% smoke extract containing inactivated 200 micrograms/ml SOD and 200 micrograms/ml catalase (22 +/- 2 min vs. 23 +/- 3 min). The effect of smoke extract on transcellular transport of fluorescein Dextran through cultured canine bronchial epithelium was also discussed.

Animals↗
PubMed1991

[Interaction between blood and dialysis membrane].

During contact between blood and dialysis membrane after the first 20-30 minutes of haemodialysis there occur the complement activation, ++intra-dialysis thrombocytopenia and leucopenia, especially neutropenia following their degranulation, which results in liberation of a number of proteases and inflammatory reaction mediators and an increased production of active oxygen compounds and peroxide radicals. This is followed by the appearance of thrombocyte-leucocyte aggregates and a decrease of ++intra-dialysis lung diffusion capacity. The clinical consequences of the blood-dialysis membrane interaction exhibit an increased permeability of pulmonic capillaries, pulmonic hypertension and hypoxemia, which might bring about vasogenic respiratory distress syndrome. The remote consequence is dialytic amyloidosis that follows increased generation and accumulation of beta 2-microglobulin. All of the above disturbances occur with cuprophan membranes more significantly that with other dialysis membranes. The blood--dialysis membrane interaction also incorporates the anaphylactic reactions, in some cases occurring when the new dialyzers are used, due to hypersensitivity to ethylene oxide used in sterilisation and the changes due to tissular accumulation of plastieizers rinsed out of the biomaterials during haemodialysis.

Cell Degranulation↗
PubMed1991

[Functional PMN defects in young periodontal patients].

Peripheral blood polymorfonuclear leukocytes (PMN) are activated by the contact with opsonized bacteria. Metabolic activation of PMN is associated with a remarkable increase in the respiratory burst and generates high energy oxygen compounds which are responsible for the bactericidal activity of neutrophils and for their ability to produce luminol-dependent chemiluminescence (CL). The CL phenomenon is measured by an automated and computerized photoluminometer (Berthold LB950) in whole blood, stimulated with opsonized zymosan. This whole blood method of CL has been applied to the investigation of PMN functional defects in early-onset periodontopatic patients.

Adolescent↗
PubMed1990

[Polyunsaturated fatty acid preparations available on the Danish market. Composition and oxidative stability].

The emerging interest in essential polyunsaturated fatty acids has resulted in a number of products available in the Danish market. These products contain essential fatty acid oils rich in n-6 and n-3 fatty acids. The quality of these products plays a major role in planning prophylactic and clinical studies. This investigation therefore illustrates the quality and the contents of undesirable oxygenated compounds--peroxides and polymeric/oxidative components. Intake of these undesirable substances can theoretically contribute to the development of cancer. It is therefore of utmost importance to be aware of the quality of the product especially when relatively large doses are employed for a considerable period. Our results show that the oxidation values of the fish oil products are much higher than vegetable oils. Furthermore we observed higher amounts of polymerised/oxidised components in Pikasol although the peroxide value was relatively low. Okholm's fish oil and cod liver oil contain higher amounts of undesirable gadoleic and cetoleic acids. A quality control from the authorities is desirable as the consumer has only the producer's/importer's "assurances" to rely on and these are not always in accordance with the real facts.

Denmark↗
PubMed1989

[Alteration of the erythrocyte membrane skeleton by oxidative damage].

In order to assess the alterations mediated by oxidative agents in physiological and pathological conditions, polyacrylamide gel electrophoresis was performed with dodecyl sodium sulphate of red cell membranes previously subjected to oxidative stress with malonyl dialdehyde generation. The alterations of the normal proteic profile observed were related to the concentration and time of exposure to hydrogen peroxide. The red cell membranes were also treated with the following: (1) increasing doses of hydrogen peroxide with and without peroxidase, and (2) supernatant of neutrophils stimulated with digitonin or activated zymosan. No alterations of the membrane skeleton were appreciated under H2O2 treatment; on the contrary, severe alterations appeared after incubation with H2O2 + peroxidase, giving rise to several peptides with different molecular weight. Striking derangement of the proteic structure was induced by activated neutrophils, which was ascribed to release of proteolytic enzymes and activated oxygen compounds.

Electrophoresis, Polyacrylamide Gel↗
PubMed1988

Inhibitory effect of retinoic acid on the respiratory burst of adult and cord blood neutrophils and macrophages: potential implication to bronchopulmonary dysplasia.

Infants suffering from bronchopulmonary dysplasia (BPD) are known to have low levels of vitamin A, a factor which may be implicated in the pathogenesis of the condition. The ability of retinoic acid (RA) (one of the active forms of vitamin A) to influence the production of superoxide anion (02-) and hydrogen peroxide (H2O2) by stimulated human adult or cord blood neutrophils and macrophages has been studied. RA was found to inhibit the O2- and H2O2 production in a dose-dependent manner. The time required for maximal inhibition was 30 min for neutrophils and 24 h for macrophages. Although cord blood neutrophils produced larger quantities of O2- and H2O2 both with and without RA, the degree of inhibition was similar in both adult and neonatal cells (40-60%). The results suggest that retinoic acid may prevent neutrophil and macrophage mediated lung damage by inhibiting the production of toxic oxygen compounds, especially in BPD conditions.

Adult↗
PubMed1987

Leukocytes and the risk of ischemic diseases.

Predictive indexes for atherosclerotic risk are imperfect, suggesting that there are predictive factors not commonly considered. Such a factor may be the white blood cell (WBC) count. Epidemiologic studies have shown correlations between the WBC count and the risk of myocardial infarction and stroke. The risk of acute myocardial infarction is approximately four times as great in persons with WBC counts high in the normal range (greater than 9000/microL [9 X 10(9)/L]) as in persons with WBC counts low in the normal range (less than 6000/microL [6 X 10(9)/L]); only 50% to 65% of the excess risk of the high-count individuals is explainable by tobacco smoking (which covaries with WBC count). A high WBC count also predicts greater risk of reinfarction and of in-hospital death. Less rigorously studied, the constitutional neutropenia of Yemenite Jews appears to afford protection against atherosclerotic disease. Among WBC types, the strongest epidemiologic association has been with the neutrophil count. Such a predictive value of WBC count is plausible and satisfying, because WBCs make a major contribution to the rheologic properties of blood; alter adhesive properties under stress--including the stress of ischemia, enhancing their rheologic importance; and participate in endothelial injury, both acutely and chronically, by adhering to endothelium and damaging it with toxic oxygen compounds and proteolytic enzymes. Techniques newly developed or under development may allow us to refine the predictive value of the WBC count by combining it with measures of cell activation and/or activatability.

Blood Vessels↗
PubMedDate not supplied

Identification of in vitro metabolites of delta 1-tetrahydrocannabinol formed by human livers.

Metabolism of delta 1-tetrahydrocannabinol (delta 1-THC) in humans, has been studied in vitro with the 10,000g supernatant fraction of three human livers. One of the livers (H-13) showed very high enzyme activity compared to the other two. The metabolites were characterized by their mass spectra and in most cases by comparison of their mass spectra and chromatographic properties with those of available synthetic references. The metabolic pattern was similar in all three livers, with 7-hydroxy-delta 1-THC as the most abundant metabolite. Furthermore, they all formed compounds oxygenated in the 6-position. Sidechain oxygenation was most pronounced with H-13, whereas trace mounts of 7-hydroxy-epoxide were formed by livers H-13 and H-15.

Adult↗
PubMed1983

Comparative studies on antibody and lectin-dependent macrophage-mediated tumor lysis.

Three characteristics of the mechanisms of antibody-dependent macrophage-mediated cytolysis (ADMC) and lectin-dependent macrophage-mediated cytolysis (LDMC) in a C3H/He mouse-MM46 syngeneic tumor system were compared: the role of divalent cations, the effect of cyclic nucleotides, and the role of protease and oxygen compounds as lytic substances. Mg++, but not Ca++, was required for ADMC but neither was required for LDMC. Ca++ inhibited both LDMC and ADMC. Dibutyryl cyclic adenosine 3',5'-monophosphate (cAMP) and its agonists, such as cholera toxin, prostaglandin E1 (PGE1) and E2 (PGE2), inhibited ADMC, but had no effect on LDMC. Dibutyryl cyclic guanosine 3',5'-monophosphate (cGMP) had no effect on either ADMC or LDMC. Isoproterenol and isobutylmethylxanthine had no effect on either ADMC or LDMC. Protease inhibitors, such as pepstatin, bestatin, chymostatin, elastatinal, leupeptin, and bovine pancreatic trypsin inhibitor, did not affect either ADMC or LDMC. Tosylphenylalanyl-chloromethylketone inhibited both ADMC and LDMC, and also inhibited macrophage-tumor cell contact in both systems. Neither catalase nor superoxide dismutase clearly inhibited either ADMC or LDMC. The different sensitivities of ADMC and LDMC to pharmacological agents suggest that these two types of mediator-dependent macrophage-mediated cytolysis have partly different cytolytic processes as well as different recognition sites.

Animals↗
PubMed1981

The effect of oxidant injury on the lymphocyte membrane and functions.

We have studied the effect of oxidant stress on the lymphocyte membrane and lymphocyte functions. Lymphocyte cultures were incubated with xanthine oxidase and xanthine, an enzyme system known to generate several highly reactive oxygen compounds. We demonstrated that these lymphocytes were viable after exposure to an in vitro oxidant stress. However, there was a marked reduction in their ability to bind SRBCs and to form caps after Con A stimulation. These lymphocytes also demonstrated a delay in PHA-induced LBT, with maximal response occurring at 5 days instead of 3 days. Catalase, a hydrogen peroxide scavenger, protected lymphocytes from this injury, implicating hydrogen peroxide as the causative agent. Another lymphocyte membrane-related function, the ability to stimulate or respond in MLC, was not impaired after oxidant injury. These results demonstrate that after in vitro oxidant injury, lymphocytes may have alterations in the cell membrane and impaired function.

B-Lymphocytes↗
PubMed1984

Effects of manganese on the nervous system.

The acute effect of manganese on the synaptosomal sodium-dependent choline uptake was studied. Manganese (Mn) revealed a mixed competitive-noncompetitive inhibition of the choline uptake, at Mn concentrations in the mM range. We do not believe that lack of choline for transmitter synthesis is of importance in Mn poisoning. Manganese chloride intubation of neonatal rats resulted in reduced homovanillic acid content in the striatum and hypothalamus. No other alteration in the dopamine or serotonin metabolism was revealed. A mechanism of cytotoxic action of manganese is discussed in terms of its transition metal properties and interaction with reactive oxygen compounds which result in the production of substances that alkylate or oxidize the cellular thiols.

Animals↗