Mechanistic Observations on the Role of the Stannous Ion in Caries Lesion De- and Remineralization

2016 ◽  
Vol 50 (4) ◽  
pp. 378-382 ◽  
Author(s):  
Frank Lippert
Keyword(s):  
Factorial Design ◽  
Surface Hardness ◽  
Acid Resistance ◽  
Design Studies ◽  
Mineral Distribution ◽  
Caries Lesion ◽  
Stannous Ion ◽  
Ph Dependent

Two mechanistic, laboratory, factorial design studies were conducted to investigate the effect of the stannous ion (Sn2+) in the absence or presence of fluoride on caries lesion de- and remineralization. Study I was concerned with determining changes in mineral distribution of subsurface lesions, whereas study II investigated changes in surface hardness of surface-softened lesions as a function of pH. Study I showed that Sn2+ modulates the effects of fluoride by preventing lamination. Study II revealed that the effect of Sn2+ on rehardening is pH dependent. Neither study demonstrated synergy between Sn2+ and fluoride, yet interactions were observed. Sn2+ does interfere with remineralization to some extent although it provided acid resistance. The role of Sn2+ in the caries process is complex.

The role of gas flow distributions on CO2 mineralization within monolithic cemented composites: coupled CFD-factorial design approach

2021 ◽  
Author(s):  
Iman Mehdipour ◽  
Gabriel Falzone ◽  
Dale Prentice ◽  
Narayanan Neithalath ◽  
Dante Simonetti ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Factorial Design ◽  
Material Properties ◽  
Gas Flow ◽  
Design Approach ◽  
Processing Conditions ◽  
Gas Processing ◽  
Co2 Mineralization

Optimizing the spatial distribution of contacting gas and the gas processing conditions enhances CO2 mineralization reactions and material properties of carbonate-cementitious monoliths.

scholarly journals The role of organic sulphur in the copper-molybdenum-S interrelationship in ruminant nutrition

1975 ◽  
Vol 34 (3) ◽  
pp. 411-420 ◽  
Author(s):  
N. F. Suttle
Keyword(s):  
Factorial Design ◽  
Basal Diet ◽  
Sodium Sulphate ◽  
Ruminant Nutrition ◽  
Normal Range ◽  
Organic S ◽  
Treatment Variation ◽  
Inorganic Sulphur ◽  
Design Experiments

1. The ability of organic and inorganic sulphur to influence the copper and molybdenum metabolism of sheep was compared in a series of three 2 × 2 factorial design experiments. In each experiment, four groups of five to seven hypocupraemic ewes were repleted with a basal diet supplemented with 6 mg Cu/kg and containing S and Mo at one of two concentrations, 1 or 4 g S and 0.5 or 4.5 mg Mo/kg respectively. Sodium sulphate (Expt 1), methionine (Expt 2) or cysteine (Expt 3) were used as the S sources. Cu and Mo concentrations in plasma were estimated in each experiment and in Expt 3 the concentrations of Cu in liver and Mo in urine were also estimated.2. The effects of the three S sources on Cu and Mo metabolism were similar. Repletion of the plasma Cu pool was unaffected by Mo alone, reduced by S alone and totally inhibited by Mo + S. Plasma Mo was greatly increased by Mo supplements, slightly decreased by S supplements and unaffected by Mo and S supplements given together.3. In Expt 3 the treatments were found to affect urinary Mo and plasma Mo in a similar manner; S prevented dietary Mo from increasing Mo excretion. The only group to show a significant repletion of the liver Cu pool was that given Mo alone.4. Supplementation of the diet with organic S significantly reduced the within-treatment variation in plasma Cu and Mo, liver Cu and urinary Mo.5. It is suggested that variations in dietary S and Mo within the normal range for herbage affect the Cu and Mo metabolism of the grazing animal, and that total S rather than inorganic S is the more useful measurement in the context of the Cu–Mo–S interrelationship.

pH‐Dependent Degradation of Layered Black Phosphorus: Essential Role of Hydroxide Ions

2018 ◽  
Author(s):  
Siyu Zhang ◽  
Xuejiao Zhang ◽  
Lei Lei ◽  
Xue‐Feng Yu ◽  
Jingwen Chen ◽  
...  
Keyword(s):  
Essential Role ◽  
Black Phosphorus ◽  
Ph Dependent

scholarly journals The dual role of candida glabrata drug:H+ antiporter CgAqr1 (ORF CAGL0J09944g) in antifungal drug and acetic acid resistance

2013 ◽  
Vol 4 ◽  
Author(s):  
Catarina Costa ◽  
André Henriques ◽  
Carla Pires ◽  
Joana Nunes ◽  
Michiyo Ohno ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Candida Glabrata ◽  
Acid Resistance ◽  
Dual Role ◽  
Antifungal Drug ◽  
Acetic Acid Resistance

scholarly journals Conformational Destabilization of Immunoglobulin G Increases the Low pH Binding Affinity with the Neonatal Fc Receptor

2015 ◽  
Vol 291 (4) ◽  
pp. 1817-1825 ◽  
Author(s):  
Benjamin T. Walters ◽  
Pernille F. Jensen ◽  
Vincent Larraillet ◽  
Kevin Lin ◽  
Thomas Patapoff ◽  
...  
Keyword(s):  
Binding Affinity ◽  
Hydrogen Exchange ◽  
Dissociation Constants ◽  
Conformational Dynamics ◽  
Fc Receptor ◽  
Salt Bridges ◽  
Neonatal Fc Receptor ◽  
Intermolecular Contacts ◽  
Ph Dependent

Crystallographic evidence suggests that the pH-dependent affinity of IgG molecules for the neonatal Fc receptor (FcRn) receptor primarily arises from salt bridges involving IgG histidine residues, resulting in moderate affinity at mildly acidic conditions. However, this view does not explain the diversity in affinity found in IgG variants, such as the YTE mutant (M252Y,S254T,T256E), which increases affinity to FcRn by up to 10×. Here we compare hydrogen exchange measurements at pH 7.0 and pH 5.5 with and without FcRn bound with surface plasmon resonance estimates of dissociation constants and FcRn affinity chromatography. The combination of experimental results demonstrates that differences between an IgG and its cognate YTE mutant vary with their pH-sensitive dynamics prior to binding FcRn. The conformational dynamics of these two molecules are nearly indistinguishable upon binding FcRn. We present evidence that pH-induced destabilization in the CH2/3 domain interface of IgG increases binding affinity by breaking intramolecular H-bonds and increases side-chain adaptability in sites that form intermolecular contacts with FcRn. Our results provide new insights into the mechanism of pH-dependent affinity in IgG-FcRn interactions and exemplify the important and often ignored role of intrinsic conformational dynamics in a protein ligand, to dictate affinity for biologically important receptors.

Effects of Color and Trait Anxiety on State Anxiety

1978 ◽  
Vol 46 (3) ◽  
pp. 855-858 ◽  
Author(s):  
Robert A. Reeves ◽  
Ed M. Edmonds ◽  
Dollie L. Transou
Keyword(s):  
Individual Differences ◽  
Factorial Design ◽  
Trait Anxiety ◽  
State Anxiety ◽  
The State ◽  
Color Condition ◽  
State Trait Anxiety Inventory ◽  
Trait Theory ◽  
The Relationship

A 2 (trait anxiety) × 4 (color) factorial design was used to determine the effects of red, green, yellow, and blue on state anxiety as a function of high and low trait anxiety. The State-Trait Anxiety Inventory was used to assess both trait (A-Trait) and state (A-State) anxiety for the 10 students assigned to each of the eight treatment combinations. High A-Trait students were significantly more anxious while viewing blue, red, and green than were the low A-Trait students and blue produced significantly more state anxiety than did either yellow or green. These results are consistent with state-trait theory and indicate that the effects of color on state anxiety may be confounded with trait anxiety unless the levels of A-Trait are equivalent for each color condition. The role of cultural and individual differences in the relationship between color and emotion and implications for research are discussed.

The Role of Power Distance and Explanation Facility in Online Bargaining Utilizing Software Agents

2011 ◽  
pp. 73-90
Author(s):  
John Lim
Keyword(s):  
Factorial Design ◽  
Task Performance ◽  
Interaction Effect ◽  
Power Distance ◽  
Software Agents ◽  
Research Perspective ◽  
Online Transactions ◽  
Main Effects ◽  
Factorial Design Experiment

Online transactions have become increasingly popular and deserve greater attention from a research perspective. Whereas there are various aspects of online transactions, this study specifically examined an online bargaining scenario utilizing software agents. User’s performance and attitudes were studied in a 2x2 factorial-design experiment. The independent variables were power distance (a dimension of culture)-for reasons associated with increasing and irresistible globalization, and explanation facility-for its conjecturable benefits in helping users to better understand and work with their software agents. Results showed these factors to have an interaction effect on task performance; as well, explanation facility exhibited main effects on trust and satisfaction. The findings have implications for system designers and builders; they also help managers in tailoring their expectations on what technology can deliver-under which conditions.

scholarly journals Deacidification by FhlA-dependent hydrogenase is involved in urease activity and urinary stone formation in uropathogenic Proteus mirabilis

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Wen-Yuan Lin ◽  
Shwu-Jen Liaw
Keyword(s):  
Proteus Mirabilis ◽  
Urease Activity ◽  
Stone Formation ◽  
Large Subunit ◽  
Acid Resistance ◽  
Urinary Stone ◽  
Potential Strategy ◽  
Ph Range ◽  
Tract Infections

Abstract Proteus mirabilis is an important uropathogen, featured with urinary stone formation. Formate hydrogenlyase (FHL), consisting of formate dehydrogenase H and hydrogenase for converting proton to hydrogen, has been implicated in virulence. In this study, we investigated the role of P. mirabilis FHL hydrogenase and the FHL activator, FhlA. fhlA and hyfG (encoding hydrogenase large subunit) displayed a defect in acid resistance. fhlA and hyfG mutants displayed a delay in medium deacidification compared to wild-type and ureC mutant failed to deacidify the medium. In addition, loss of fhlA or hyfG decreased urease activity in the pH range of 5–8. The reduction of urease activities in fhlA and hyfG mutants subsided gradually over the pH range and disappeared at pH 9. Furthermore, mutation of fhlA or hyfG resulted in a decrease in urinary stone formation in synthetic urine. These indicate fhlA- and hyf-mediated deacidification affected urease activity and stone formation. Finally, fhlA and hyfG mutants exhibited attenuated colonization in mice. Altogether, we found expression of fhlA and hyf confers medium deacidification via facilitating urease activity, thereby urinary stone formation and mouse colonization. The link of acid resistance to urease activity provides a potential strategy for counteracting urinary tract infections by P. mirabilis.

scholarly journals Role of the virulence plasmid in acid resistance of Shigella flexneri

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Chang Niu ◽  
Jing Yang ◽  
Hongsheng Liu ◽  
Yong Cui ◽  
Huijie Xu ◽  
...  
Keyword(s):  
Shigella Flexneri ◽  
Acid Resistance ◽  
Virulence Plasmid
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