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Oxide Concentration (oxide + concentration)

Distribution by Scientific Domains
Medical Sciences88%

Kinds of Oxide Concentration

  • nitric oxide concentration
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    Selected Abstracts

    Chronologic Changes of Nitric Oxide Concentration in the Cochlear Lateral Wall and Its Role in Noise-Induced Permanent Threshold Shift

    THE LARYNGOSCOPE, Issue 5 2008
    Yuh-Shyang Chen MD
    Abstract Objective: The objective of this study was to investigate the chronologic changes of nitric oxide (NO) concentration in the cochlear lateral wall and to explore its possible role in permanent threshold shift (PTS) after intense noise exposure. Materials and Methods: Seventeen guinea pigs were subjected to a single continuous exposure to broadband white noise at 105 ± 2 dB sound pressure level (SPL) for 40 hours and were divided into four groups according to various postnoise recovery periods. Another 12 guinea pigs were not exposed to noise and served as controls. The hearing status of all animals was evaluated with auditory brainstem responses (ABR) evoked by condensation "click" sounds. ABR were recorded both prior to noise exposure and immediately before killing the animal. After death, NO concentration in the cochlear lateral wall was directly measured with an NO/ozone chemiluminescence technique. Results: An approximately 1.7-fold increase in NO concentration was observed immediately postnoise exposure, which persisted for up to 28 days. The threshold of ABR elevation (mean, 30 dB SPL) peaked immediately after cessation of noise exposure and gradually resolved to a PTS (mean, 14.5 dB SPL) 56 days after noise exposure when NO concentration had returned to its prenoise exposure level. Conclusion: Noise-induced threshold shift, which resolved to a mild PTS, can be partially attributed to NO elevation in the cochlear lateral wall. Our results revealed a nonlinear correlation between ABR recovery and depletion of NO, indicating that the mechanisms of NO changes in the cochlear lateral wall may be more complicated than previously conceived and that other pathophysiologic mechanisms may also play important roles in noise-induced PTS. [source]

    Kinetic studies of hydrazine and 2-hydroxyethylhydrazine alkylation by 2-chloroethanol: Influence of a strong base in the medium

    INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 6 2009
    V. Goutelle
    To optimize yields, the study of reaction kinetics related to the synthesis of 2-hydroxyethylhydrazine (HEH) obtained from the alkylation of N2H4 by 2-chloroethanol (CletOH) was carried out with and without sodium hydroxide. In both cases, the main reaction of HEH formation was followed by a consecutive, parallel reaction of HEH alkylation (or dialkylation of N2H4), leading to the formation of two isomers: 1,1-di(hydroxyethyl)hydrazine and 1,2-di(hydroxyethyl)hydrazine. In this study, hydrazine and hydroxyalkylhydrazine alkylations followed SN2 reactions triggered directly by CletOH or indirectly in the presence of a strong base by ethylene oxide, an intermediate compound. The kinetics was studied in diluted mediums by quantifying HEH and CletOH by gas chromatography and gas chromatography coupled with mass spectrometry (GC-MS). The activation parameters of each reaction and the influence of a strong base present in the medium on the reaction mechanisms were established. A global mathematical treatment was applied for each alternative. It allowed modeling the reactions as a function of reagent concentrations and temperature. In the case of direct alkylation by CletOH, simulation was established for semi-batch and batch syntheses and was confirmed in experiments for concentrated mediums (1.0 M , [CletOH]0 , 3.2 M and 15.7 M , [N2H4]0 , 18.8 M). Simulation therefore permits the prediction of the instantaneous concentration of reagents and products, in particular ethylene oxide concentration in the case of indirect alkylation, which must be as weak as possible. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 382,393, 2009 [source]

    Nitric oxide increases dramatically in air exhaled from lung regions with occluded vessels

    ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 3 2003
    E. Fernández-Mondéjar
    Background:, We observed dramatic changes in exhaled nitric oxide concentration (,NOE) during wedge measurements, and hypothesised that occlusion and redistribution of pulmonary blood flow affects NOE. Methods:, We inflated the balloon of the pulmonary artery catheter and measured NOE and central hemodynamics in closed chest anesthetised pigs (n = 11) ventilated with hyperoxic gas (fraction of inspired oxygen [FIO2] = 0.5), before and during lung injury, and in open chest anesthetised pigs (n = 17) before and during left lower lobar (LLL) hypoxia (FIO2 0.05), and during hyperoxic (FIO2 0.8) ventilation of the other lung regions (HL). Results:, In the closed chest pigs NOE increased from 2.0 (0.9) to 3.4 (2.0) p.p.b. (P < 0.001) during wedge, and returned to 2.0 (1.0) p.p.b. when the balloon was deflated. The increase in mean pulmonary artery pressure (MPaP) during wedge was small and insignificant (P > 0.07). When the balloon was inflated in the right pulmonary artery in the open chest pigs, the perfusion of the HL decreased from 2.57 (0.58) to 2.34 (0.55) l min,1 (P < 0.001), and NOEHL increased from 2.5 (0.9) to 6.2 (3.2) p.p.b. (P < 0.001). The perfusion of the LLL increased from 0.33 (0.26) to 0.54 (0.34) l min,1 (P < 0.001), and NOELLL decreased from 1.7 (0.6) to 1.5 (0.5) p.p.b. (P < 0.001). Neither lung injury nor LLL hypoxia had any influence on ,NOE (P > 0.07) during wedge. The correlation coefficient (R2) was 0.66 between changes in regional blood flow and ,NOE, and 0.37 between changes in MPaP and ,NOE. Conclusions:, Nitric oxide concentration increases dramatically from lung regions with occluded vessels, whereas changes in MPaP have minor effects on NOE. This is an important fact to consider when comparing NOE within or between studies, and indicates a possible marker of diseases with occluded lung vessels. [source]

    Elevated alveolar nitric oxide concentration after environmental challenge in hypersensitivity pneumonitis

    RESPIROLOGY, Issue 4 2010
    Toshihiro SHIRAI
    ABSTRACT We describe a 57-year-old male patient admitted to hospital with hypersensitivity pneumonitis (HP) that resolved without treatment. The total and alveolar nitric oxide (NO) concentrations were measured on initial admission and after re-exposure to his home environment. Following environmental exposure he became ill again, alveolar NO concentration was increased to the same level as on initial admission and impaired pulmonary function and radiologic abnormalities were found. It suggested a diagnosis of environmentally induced HP. The clinical value of measuring alveolar NO as an acute-phase reactant in HP is demonstrated in this patient. [source]

    A low oxygen consumption pneumatic ventilator for emergency construction during a respiratory failure pandemic,

    ANAESTHESIA, Issue 3 2010
    D. Williams
    Summary The UK influenza pandemic plan predicts up to 750 000 additional deaths with hospitals prioritising patients against inadequate resources. We investigated three prototype low-cost, gas-efficient, pneumatic ventilators in a test lung model at different compliance and rate settings. Mean (SD) oxygen consumption was 0.913 (0.198) and 1.119 (0.267) l.min,1 at tidal volumes of 500 ml and 700 ml respectively. Values of FIo2 increased marginally as lung compliance reduced, reflecting the increased ventilator workload and consequent increased enrichment of breathing gas by waste oxygen from the pneumatic mechanism. We also demonstrated that a stable nitric oxide concentration could be delivered by this design following volumetric principles. It is possible to make a gas-efficient ventilator costing less than £200 from industrial components for use where oxygen is available at 2-4 bar, with no pressurised air or electrical requirements. Such a device could be mass-produced for crises characterised by an overwhelming demand for mechanical ventilation and a limited oxygen supply. [source]

    Response of periodontal ligament fibroblasts and gingival fibroblasts to pulsating fluid flow: nitric oxide and prostaglandin E2 release and expression of tissue non-specific alkaline phosphatase activity

    JOURNAL OF PERIODONTAL RESEARCH, Issue 6 2000
    M. T. M. Van Der Pauw
    The capacity of the periodontal ligament to alter its structure and mass in response to mechanical loading has long been recognized. However, the mechanism by which periodontal cells can detect physical forces and respond to them is largely unknown. Besides transmission of forces via cell-matrix or cell-cell interactions, the strain-derived flow of interstitial fluid through the periodontal ligament may mechanically activate the periodontal cells, as well as ensure transport of cell signaling molecules, nutrients and waste products. Mechanosensory cells, such as endothelial and bone cells, are reported to respond to a flow of fluid with stimulated prostaglandin E2(PGE2) and nitric oxide production. Therefore, we examined the PGE2 and nitric oxide response of human periodontal ligament and gingival fibroblasts to pulsating fluid flow and assessed the expression of tissue non-specific alkaline phosphatase activity. Periodontal ligament and gingival fibroblasts were subjected to a pulsating fluid flow (0.7±0.02 Pa, 5 Hz) for 60 min. PGE2 and nitric oxide concentrations were determined in the conditioned medium after 5, 10, 30 and 60 min of flowing. After fluid flow the cells were cultured for another 60 min without mechanical stress. Periodontal ligament fibroblasts, but not gingival fibroblasts, responded to fluid flow with significantly elevated release of nitric oxide and decreased expression of tissue non-specific alkaline phosphatase activity. In both periodontal ligament and gingival fibroblasts, PGE2 production was significantly increased after 60 min of flowing. Periodontal ligament fibroblasts, but not gingival fibroblasts, produced significantly higher levels of PGE2 during the postflow culture period. We conclude that human periodontal ligament fibroblasts are more responsive to pulsating fluid flow than gingival fibroblasts. The similarity of the early nitric oxide and PGE2 responses to fluid flow in periodontal fibroblasts with bone cells and endothelial cells suggests that these three cell types possess a similar sensor system for fluid shear stress. [source]

    Exhaled nitric oxide in asthmatic and non-asthmatic children: Influence of type of allergen sensitization and exposure to tobacco smoke

    PEDIATRIC ALLERGY AND IMMUNOLOGY, Issue 5 2001
    Mario Barreto
    Asthmatic bronchial inflammation is associated with increased nitric oxide concentrations in exhaled air (eNO). Recent data suggest that this effect arises from atopy. Our aim in this study was to find out whether atopy and sensitization to particular allergens influences eNO levels. A total of 213 subjects (41 asthmatics and 172 controls) (96 boys and 117 girls, 7.3,14 years of age) were studied. Parents completed a questionnaire that sought information on their children's respiratory symptoms and exposure to tobacco smoke. Subjects underwent skin-prick tests for the following common allergens: Dermatophagoides pteronyssinus (Dpt), cat fur, Aspergillus fumigatus, Alternaria tenuis, mixed grass, mixed tree pollen, Parietaria officinalis, egg, and cow's milk. eNO was collected in 1-l mylar bags (exhaled pressure 10 cmH2O, flow 58 ml/s) and analyzed by using chemiluminescence. Atopic and non-atopic children without a history of chronic respiratory symptoms had a similar geometric mean eNO (atopics, n = 28, 11.2 p.p.b.; non-atopics, n = 96, 10.0 p.p.b.; mean ratio 1.1, 95% confidence interval [CI]: 0.7,1.6). Conversely, atopic asthmatic subjects had significantly higher eNO values than non-atopic asthmatic subjects (atopics, n = 25, 24.8 p.p.b.; non-atopics, n = 16, 11.4 p.p.b.; mean ratio 2.2, 95% CI: 1.2,3.9, p=,0.000). In children with rhinitis alone (n = 15) and those with lower respiratory symptoms other than asthma (n = 33), eNO increased slightly, but not significantly, with atopy. eNO levels correlated significantly with Dpt wheal size (r = 0.51) as well with the wheal size for cat, mixed grass, and Parietaria officinalis (r = 0.30,0.29), and with the sum of all wheals (r = 0.47) (p=,0.000). Subjects sensitized only for Dpt (but not those subjects sensitized only for grass pollen or other allergens) showed significantly higher eNO levels than non-atopic subjects (16.4 p.p.b. vs. 10.2 p.p.b., mean ratio 1.6, 95% CI: 1.1,2.3, p=,0.002). In asthmatic subjects, Dpt sensitization markedly increased eNO levels (Dpt- sensitized subjects: 28.0 p.p.b.; Dpt- unsensitized subjects: 12.2 p.p.b.; mean ratio 2.3, 95% CI: 1.5,3.5, p=,0.000). Non-asthmatic Dpt- sensitized subjects also had significantly higher eNO values than non-asthmatic, non- Dpt -sensitized subjects (14.2 p.p.b. vs. 10.1 p.p.b.; mean ratio 1.4, 95% CI: 1.1,1.9, p=,0.008). No difference was found between eNO levels in asthmatic subjects and control subjects exposed or unexposed to tobacco smoke. In conclusion, eNO concentrations are high in atopic asthmatic children and particularly high in atopic asthmatics who are sensitized to house-dust mite allergen. [source]

    Predictors of improved seminal parameters and fertility after varicocele repair in young adults

    ANDROLOGIA, Issue 5 2009
    M. Rodriguez Peña
    Summary The aim of our study was to determine hormonal or biochemical markers in patients with clinically palpable left varicocele but without a history of infertility, with especial emphasis on nitric oxide, related with improved seminal parameters after varicocelectomy. Semen samples were obtained from 202 patients with left varicocele grade II or III. Nitric oxide levels in seminal plasma were determined by the Griess technique. Testicular volume was determined ultrasonographically in both testes and hormonal profile was measured. The post-operative sperm concentration increased significantly in patients with normal sperm count or moderate oligozoospermia, but we did not find an increment in sperm count in patients with mild and severe oligozoospermia after surgery. The mean percentage of normal motility significantly increased after surgery, but we did not observe a significant increment in morphologically normal sperm count and testicular volume after varicocele repair. Moreover, we did not find any correlation between nitric oxide concentrations and severity of oligozoospermia, asthenozoospermia or abnormal sperm morphology in this population. It is concluded that in the general male population, varicocele repair is not associated with an improved semen profile in all cases. We did not observe a significant correlation between nitric oxide concentrations and semen profile. [source]

    Effects of pneumoperitoneum with or without colostomy on rat colonic anastomotic healing

    ANZ JOURNAL OF SURGERY, Issue 3 2004
    Hedef Özgün
    Background: Elevated intra-abdominal pressure and colostomy have adverse effects on colonic anastomoses. The aim of the present study was to investigate the effects of laparoscopic colon surgery with and without diverting colostomy on healing of colonic anastomoses in an experimental model. Methods: Thirty-six male rats were divided into three equal groups: group 1, control (colonic anastomosis and anaesthesia for 180 min only); group 2, 180 min pneumoperitoneum and colonic anastomosis; and group 3, similar to group 2 with a proximal colostomy. On day 7, bursting pressures, tissue hydroxyproline and nitric oxide concentrations and histopathological inflammation scores were determined and compared. Results: Mean bursting pressures were higher in the control group than the two pneumoperitoneum groups (P = 0.0003). Mean tissue hydroxyproline concentrations showed no difference (P > 0.05). Mean tissue nitric oxide concentrations were significantly increased in the control group (P = 0.0013). Histopathological scores demonstrated increased inflammatory response in group 3 compared to the controls (P = 0.0009). Conclusion: Pneumoperitoneum delays collagen maturation and impairs anastomotic strength in the colon. Following pneumoperitoneum, performance of a diverting loop colostomy to protect the anastomosis will not have additional detrimental effects on anastomotic healing. [source]