Browsing by Subject "pH"

Now showing 1 - 5 of 5
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    Comparing Bedside Methods of Determining Placement of Gastric Tubes in Children
    (Wiley, 2014-01) Cirgin Ellett, Marsha L.; Cohen, Mervyn D.; Croffie, Joseph M. B.; Lane, Kathleen A.; Austin, Joan K.; Perkins, Susan M.; IU School of Nursing
    Purpose The purpose of this study was to compare the accuracy and predictive validity of pH, bilirubin, and CO2 in identifying gastric tube placement errors in children. Design and Methods After the tube was inserted into 276 children, the CO2 monitor reading was obtained. Fluid was then aspirated to test pH and bilirubin. Results Lack of ability to obtain tube aspirate was the best predictor of NG/OG placement errors with a sensitivity of 34.9% and a positive predictive value of 66.7%. Measuring pH, bilirubin, and CO2 of tube aspirate was less helpful. Practice Implications Health care providers should suspect NG/OG tube misplacement when no fluid is aspirated.
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    The effect of pH levels on nonlatex vs latex interarch elastics
    (Allen Press, 2011) Sauget, Paul S.; Stewart, Kelton T.; Katona, Thomas R.; Orthodontics and Oral Facial Genetics, School of Dentistry
    Objective: To evaluate the force decay characteristics of nonlatex vs latex interarch elastics within the normal range of salivary pH levels. Materials and methods: Two nonlatex groups and one latex quasi-control group were tested. Elastics were stretched to 15 mm and were held for 10 seconds (baseline), 4 hours, 8 hours, and 12 hours in artificial saliva solutions with pH levels of 5.0, 6.0, and 7.5. Force magnitudes were measured at 25 mm of activation. Each specimen was used once. Measurements were assessed using three-way analysis of variance (ANOVA). Results: The three-way interaction between group, pH, and time was not significant (P = .13); the group-by-pH interaction also was not significant (P = .70). However, pH-by-time (P = .0179) and group-by-time (P = .0001) interactions were significant. American Orthodontics nonlatex generated significantly higher loads than Auradonics nonlatex. American Orthodontics nonlatex produced significantly higher forces than American Orthodontics latex at 4, 8, and 12 hours, but not at 10 seconds. American Orthodontics latex was significantly stronger than Auradonics nonlatex at 10 seconds, but not at 4, 8, and 12 hours. Conclusions: No clinically significant correlation between pH and force decay was observed.
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    Enamel demineralization and remineralization under plaque fluid-like conditions – a QLF study
    (Karger, 2011) Lippert, Frank; Butler, A.; Lynch, R. J. M.; Department of Cariology, Operative Dentistry and Dental Public Health, School of Dentistry
    The present study investigated de- and remineralization in enamel lesions under plaque fluid (PF)-like conditions using quantitative light-induced fluorescence (QLF). Preformed lesions were exposed to partially saturated lactic acid solutions, varying in pH and fluoride concentration ([F]) based on a 5 × 3 factorial study design (0/0.1/0.5/1.5/4 ppm F; pH 4.9/5.2/5.5). Average fluorescence loss (ΔF) was monitored for 11 days. Subsequently, lesions were demineralized in a partially saturated acetic acid solution for two 24-hour periods. Data were analyzed using repeated measures analysis of covariance. Lesions exposed to PF at 4 ppm F and pH 5.5 showed not only the most remineralization (ΔΔF = 28.2 ± 14.0%) for all groups after 11 days, but also the most demineralization (ΔΔF = –19.3 ± 13.5%) after subsequent acetic acid exposure. Increased [F] resulted in more remineralization, regardless of pH. Higher pH values resulted in more remineralization. No remineralization was observed in lesions exposed to F-free solutions, regardless of pH. Remineralization was noticeable under the following conditions: pH 4.9 – [F] = 4 ppm, pH 5.2 – [F] ≧ 1.5 ppm, and pH 5.5 – [F] ≧ 0.5 ppm. Overall, [F] had a stronger effect on remineralization than pH. Subsequent demineralization showed that little protection was offered by PF-like solutions, and further demineralization compared with baseline was observed on lesions not remineralized initially. [F] had a stronger effect on net mineral change than pH. The present study has shown that QLF is a valuable tool in studying lesion de- and remineralization under PF-like conditions, where [F] was shown to be more important than pH.
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    In Vivo Renal Tubule pH in Stone-Forming Human Kidneys
    (Mary Ann Liebert, Inc., 2020-02) Borofsky, Michael S.; Handa, Rajash K.; Evan, Andrew P.; Williams, James C., Jr.; Bledsoe, Sharon; Coe, Fredric L.; Worcester, Elaine M.; Lingeman, James E.; Urology, School of Medicine
    Introduction: There is evidence that patients with a history of ileostomies, who produce acidic urine and form uric acid or calcium oxalate stones, may plug some collecting ducts with calcium phosphate (CaP) and urate crystals. This is a paradoxical finding as such minerals should not form at an acid pH. One possible explanation is the presence of acidification defects due to focal damage to inner medullary collecting duct and Bellini duct (BD) cells. We sought to further investigate this hypothesis through direct measurement of ductal pH in dilated BDs in patients with ileostomies undergoing percutaneous nephrolithotomy (PCNL) for stone removal. Methods: After obtaining institutional review board approval, we used a fiber-optic pH microsensor with a 140-μm-diameter tip to measure intraluminal pH from the bladder, saline irrigant, and dilated BDs of patients undergoing PCNL. Results: Measurements were taken from three patients meeting inclusion criteria. Measured pH of bladder urine ranged from 4.97 to 5.58 and pH of saline irrigant used during surgery ranged from 5.17 to 5.75. BD measurements were achieved in 11 different BDs. Mean intraductal BD pH was more than 1 unit higher than bulk urine (6.43 ± 0.22 vs 5.31 ± 0.22, p < 0.01). Conclusions: This is the first evidence for focal acidification defects within injured/dilated BDs of human kidneys producing highly acidic bulk phase urine. These results may help explain the paradoxical finding of CaP and urate plugs in dilated ducts of patients with stone-forming diseases characterized by highly acidic urine.
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    Measuring pH of the Coxiella burnetii Parasitophorous Vacuole
    (Wiley, 2017-11) Samanta, Dhritiman; Gilk, Stacey; Microbiology and Immunology, School of Medicine
    Coxiella burnetii is the causative agent of human Q fever, a zoonotic disease that can cause a debilitating, flu‐like illness in acute cases, or a life‐threatening endocarditis in chronic patients. An obligate intracellular bacterial pathogen, Coxiella survives and multiplies in a large lysosome‐like vacuole known as the Coxiella parasitophorous vacuole (CPV). A unique characteristic of the CPV is the acidic environment (pH ∼5.0), which is required to activate Coxiella metabolism and the Coxiella type 4 secretion system (T4SS), a major virulence factor required for intracellular survival. Further, inhibiting or depleting vacuolar ATPase, a host cell protein that regulates lysosomal pH, inhibits intracellular Coxiella growth. Together, these data suggest that CPV pH is an important limiting factor for Coxiella growth and virulence. This unit describes a method to determine CPV pH using live cell microscopy of a pH–sensitive fluorophore conjugated to dextran. This technique is useful to measure changes in CPV pH during infection or in response to drug treatment.