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Dental Caries: Resistance Factors — Fluorides
Published in Lars Granath, William D. McHugh, Systematized Prevention of Oral Disease: Theory and Practice, 2019
Stephen H. Y. Wei, Jan Ekstrand
Enamel surface is amphoteric and can bind both acidic protein groups at the calcium sites at the crystal surface and basic protein groups at the phosphate sites.56 Fluoride can act as an efficient inhibitor of binding of acidic proteins to hydroxy-apatite. This inhibition is due to the competition for positive calcium sites on the enamel surface. This may explain the reduced amount of plaque and bacterial accumulation on enamel surfaces following the use of fluoride mouthrinses. It appears also that a stannous fluoride rinse is much more effective in inhibiting plaque accumulation than sodium fluoride, ammonium fluoride, and MFP, probably because of the synergistic effect between the tin ion and the fluoride ion.57
Fingernail cortisol as a marker of chronic stress exposure in Indigenous and non-Indigenous young adults
Published in Stress, 2020
Belinda Davison, Gurmeet R. Singh, Victor M. Oguoma, James McFarlane
Samples were analyzed in duplicate by liquid chromatography–mass spectrometry using the method of Ionita et al. (2009) with minor modifications as follows (Ionita, Fast, and Akhlaghi, 2009). Briefly, a Shimadzu UPLC and 8050 triple quadrupole mass spectrometer equipped with a heated electrospray ionization source (HESI) operating in positive ion mode were used. The samples (10 ul) were separated using a Kinetex 2.6 u Evo C18 column (2.1 × 50 mm 2 u particle size; Phenomenex, Lane Cove, NSW, Australia). Samples were eluted with a gradient from 10% to 100% methanol with 0.2 mM ammonium fluoride over 6 min. Cortisol eluted with a retention time of 2.5 min, and quantitative analysis was performed in multiple reaction monitoring mode (MRM) of the most abundant product ions (m/z 363.2 > 121.2 & 309.3). The calibration curve demonstrated a linear relationship (r2 > 0.995) between the 25 ug/ml and 40 pg/ml with detection limits of cortisol <0.4 pg. The inter and intra assay coefficients of variation were determined to be 4.7%.
Hair cortisol and cortisone as markers of stress in Indigenous and non-Indigenous young adults
Published in Stress, 2019
Belinda Davison, Gurmeet R Singh, James McFarlane
Samples were analyzed in duplicate by LC/MS/MS using the method of Ionita, Fast, and Akhlaghi (2009) with minor modifications as follows. The samples were separated using a Kintetex 2.6 u Evo C18 column (2.1 × 50 mm 2 µm particle size) (Phenomenex). Samples were eluted with a gradient from 10% to 100% methanol with 0.2 mM ammonium fluoride over 6 minutes. Cortisone and cortisol eluted with a retention time of 2.1 and 2.5 min, respectively, and quantitative analysis was performed in multiple reaction monitoring mode (MRM) of the two most abundant product ions (m/z 361 > 163.1 & 121.1 and 363.2 > 121.2 & 309.3). The inter-assay and intra-assay coefficients of variation were determined to be 4.9% and 2.7%, respectively. The results were expressed as pg/mg.
A precise, sensitive and stable LC-MSMS method for detection of picomolar levels of serum aldosterone
Published in Scandinavian Journal of Clinical and Laboratory Investigation, 2018
Margrete Lie, Ketil Thorstensen
Mobile phase A consisted of 5 mM ammonium fluoride in water, and mobile phase B was 5 mM ammonium fluoride in methanol. The flow rate was 0.4 ml/min. Aldosterone and the corresponding internal standard eluted at 2.7 minutes in a non-linear gradient, as shown in Table 1. Total runtime was 5.5 min for each sample.