Disease relevance of water

• When the reaction catalyzed by 5-oxoprolinase of Pseudomonas putida was carried out to 90% completion in H2(18)O, the residual 5-oxoproline was found to contain 18O in the amide carbonyl oxygen atom [1].
• Mass spectral analysis of the dehydration products of the oxygen-18-containing trans-dihydrodiol metabolites indicated that 7-Cl-BA 3S,4R-epoxide and 7-Cl-BA 8R,9S-epoxide were the predominant enantiomeric intermediates [2].
• Subjects remained healthy, no problems of clinical or metabolic significance appeared, body weight remained constant, and body composition indices (lean body mass by H2(18)O dilution and creatinine excretion) and basal metabolic rate did not change [3].
• Conversion of aniline into pyrocatechol by a Nocardia sp.; incorporation of oxygen-18 [4].
• Sixteen patients with advanced chronic obstructive pulmonary disease (COPD) and stable chronic respiratory failure (pO2 less than 60 mm Hg, pCO2 greater than 45 mm Hg) were given 2-3 L/min oxygen 18 hours/day for 3 weeks [5].

High impact information on water

• Hydrolysis of styrene oxide-adducted hemoglobin in H2(18)O at neutral pH yielded 18O incorporation results that suggest this mechanism of hydrolysis is operant to a minor degree in styrene oxide-hemoglobin ester adducts [6].
• After the multiple turnover reaction in H2(18)O, the enzyme was digested with lysyl endopeptidase, and the molecular masses of the peptide fragments formed were measured by an ionspray mass spectrometer [7].
• Maximal velocities and oxygen-18 exchange catalyzed by H64A HCA II showed that nearly all of the proton transfer with this mutant proceeded through the imidazole buffer [8].
• The absence of phospholipid acylation-deacylation cycles in isolated mitochondria is demonstrated by the absence of 18O incorporation from H2(18)O into phospholipid acylester carbonyl groups, confirming conclusions arrived at from marker enzyme data by a definitive independent approach [9].
• Acyl turnover of rat hepatocyte phospholipids and triacylglycerols was assessed by incubating the cells in media containing 40% H2(18)O and measuring the time-dependent incorporation of 18O into ester carbonyls by gas chromatography-mass spectrometry of hydrogenated methyl esters [10].

Biological context of water

• Kinetics of oxygen-18 exchange between inorganic phosphate and water catalyzed by myosin subfragment 1, using the 18O shift in 31P NMR [11].
• The first evidence for exchange of 18O between H2(18)O and a nitrosation intermediate occurring after the enzyme-nitrosyl complex, presumably an enzyme-bound nitrosamine, has been obtained [12].
• In five patients, body composition was determined after recovery by means of H2(18)O dilution [13].
• Exposure of AM to hyperoxia (60% and 95% oxygen, 18 h) in control media increased LDH release and impaired phagocytic activity for yeast; however, similar hyperoxic exposures in iron-supplemented media significantly increased the cells' LDH release and decreased phagocytosis [14].
• Anomalous oxygen-18 exchange during ATP synthesis in oxidative phosphorylation [15].

Anatomical context of water

• The measurement of whole body water by H2(18)O dilution in newborn pigs [16].
• An oxygen-18 dilution method was used to calculate percentage body fat [17].
• Deuterium and oxygen-18 measurements on microliter samples of urine, plasma, saliva, and human milk [18].
• When the substrates were incubated with the CYP3A4-expressed microsomes under oxygen-18 gas phase, atmospheric oxygen was incorporated into 35% of 7-oxo-Delta(8)-THC formed from 7alpha-OH-Delta(8)-THC, but only 12% of 7-oxo-Delta(8)-THC formed from 7beta-OH-Delta(8)-THC [19].
• We used the (18)O isotope, permitting analytical separation of H2(18)O from the (18)O isotope, as well as quantification of regional oxidative metabolism by measuring the tissue residue of oxidation water in the rabbit myocardium [20].

Associations of water with other chemical compounds

• The presence of oxygen-18 in these molecules can be detected either by nuclear magnetic resonance (using the oxygen-18 effect on the carbon-13 chemical shift of the carboxyl carbon) or by mass spectrometry (comparing the ions at three and five units above the molecular weight with that one unit above) [21].
• In the present study, the nature of the reactive intermediates leading to dopamine beta-monooxygenase inactivation by beta- chlorophenethylamine has been investigated employing kinetic deuterium isotope effects and oxygen- 18 labeling as tools [22].
• Conversely, if carbonic anhydrase is present and highly active, oxygen exchange between CO2 and cellular H2O will occur more rapidly than carboxylation, and the [13C] malate formed will contain little or no oxygen-18 above the natural abundance level [21].
• Extensive incorporation of oxygen-18 at position O4 of the pyrimidine nucleus results from exchange between H218O and nucleosides or bases in 1N HC1 at 100 degrees [23].
• (2) The flash-induced O2 and CO2 production by photosystem II was followed simultaneously with membrane inlet mass spectrometry under approximately 15% H2(18)O enrichment [24].

Gene context of water

• Incubation of CYP2C9 under oxygen-18 gas showed that all HETEs had incorporated oxygen-18 to the same degree [25].
• Flavopiridol analogues, thio- and oxoflavopiridols which contain a sulfur (16) or oxygen (18) atom linker between a chromone ring and the hydrophobic side chain, are selective cyclin-dependent kinase 1 (CDK1) inhibitors with an IC(50) of 110 and 130 nM [26].
• Calculated frequencies obtained for two model systems have been compared to experimental resonance Raman spectra of oxidized A. thaliana sulfite oxidase catalytically cycled in both H2(16)O and H2(18)O [27].
• The origins of the alkynyl, acyl, and ketonyl ligands of 2-4 were determined by isotopic labeling experiments with D2O and H2(18)O [28].
• Solvent deuterium isotope effects in the catalysis of oxygen-18 exchange by human carbonic anhydrase II [29].

Analytical, diagnostic and therapeutic context of water

• Oxygen-18 isotope labeling showed that water is the source of the oxygen atoms in the molecular oxygen evolved, and so this system is a functional model for photosynthetic water oxidation [30].
• Ozone dose and effect in humans and rats. A comparison using oxygen-18 labeling and bronchoalveolar lavage [31].
• We describe a compact ultrafiltration system for the removal of pyrogens and bacteria from water labeled with the stable isotopes of deuterium and oxygen-18 [32].
• The different patterns of enzymatic cleavage of diadenosine polyphosphates, ApnAs, where n = 3-5, have been established by fast atom bombardment mass spectrometry, FAB MS, of the nucleotide products formed in the presence of H2(18)O [33].
• We determined the percentage of body fat (%BF) by isotope dilution [oxygen-18 (H(2)(18)O) and deuterium oxide ((2)H(2)O)] and anthropometry in 71 healthy, urban Chinese adults aged 35-49 y [body mass index (BMI) 18-35 kg/m(2)] [34].

References