Publications by authors named "Katrice King"

2 Publications

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Child's play: Harnessing play and curiosity motives to improve child handwashing in a humanitarian setting.

Int J Hyg Environ Health 2019 03 13;222(2):177-182. Epub 2018 Sep 13.

Department for Disease Control, London School of Hygiene and Tropical Medicine, Keppel St, Bloomsbury, London, WC1E 7HT, UK.

In humanitarian emergency settings there is need for low cost and rapidly deployable interventions to protect vulnerable children, in- and out-of-school, from diarrhoeal diseases. Handwashing with soap can greatly reduce diarrhoea but interventions specifically targeting children's handwashing behaviour in humanitarian settings have not been tested. Traditional children's handwashing promotion interventions have been school-focused, resource-intensive and reliant on health-based messaging. However, recent research from non-humanitarian settings and targeting adults suggests that theory-based behaviour change interventions targeting specific motives may be more effective than traditional handwashing interventions. In this proof-of-concept study we test, for the first time, the distribution of a modified soap bar, designed to appeal to the motives of play and curiosity, in a household-level, rapidly deployable, handwashing promotion intervention for older children in a humanitarian setting - an internally displaced persons camp in Iraqi Kurdistan. Out of five total blocks within the camp, one was assigned to intervention and one to control. 40 households from each assigned block were then randomly chosen for inclusion in the study and the practice of handwashing with soap at key times was measured at baseline and four weeks after intervention delivery. Children in intervention households received transparent soaps with embedded toys, delivered within a short, fun, and interactive household session with minimal, non-health-based, messaging. The control group received plain soap delivered in a short standard, health-based, hygiene promotion session. At the 4-week follow-up, children in the intervention group were 4 times more likely to wash their hands with soap after key handwashing occasions than expected in the counterfactual (if there had been no intervention) based on the comparison to children in the control group (adjusted RR = 3.94, 95% CI 1.59-9.79). We show that distributing soaps with toys embedded inside, in a rapidly deployable intervention, can improve child handwashing behaviour in a humanitarian emergency context. Further studies are needed to determine the longer-term behavioural and health impact of such an intervention when delivered at a greater scale in a humanitarian context.
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http://dx.doi.org/10.1016/j.ijheh.2018.09.002DOI Listing
March 2019

Ionization properties of phosphatidylinositol polyphosphates in mixed model membranes.

Biochemistry 2009 Oct;48(40):9360-71

Department of Biological Sciences, Kent State University, Kent, Ohio 44242, USA.

Phosphatidylinositol polyphosphate lipids (phosphoinositides) form only a minor pool of membrane phospholipids but are involved in many intracellular signaling processes, including membrane trafficking, cytoskeletal remodeling, and receptor signal transduction. Phosphoinositide properties are largely determined by the characteristics of their headgroup, which at physiological pH is highly charged but also capable of forming hydrogen bonds. Many proteins have developed special binding domains that facilitate specific binding to particular phosphoinositides, while other proteins interact with phosphoinositides via nonspecific electrostatic interactions. Despite its importance, only limited information is available about the ionization properties of phosphoinositides. We have investigated the pH-dependent ionization behavior of all three naturally occurring phosphatidylinositol bisphosphates as well as of phosphatidylinositol 3,4,5-trisphosphate in mixed phosphoinositide/phosphatidylcholine vesicles using magic angle spinning (31)P NMR spectroscopy. For phosphatidylinositol 3,5-bisphosphate, where the two phosphomonoester groups are separated by a hydroxyl group at the 4-position, the pH-dependent chemical shift variation can be fitted with a Henderson-Hasselbalch-type formalism, yielding pK(a)(2) values of 6.96 +/- 0.04 and 6.58 +/- 0.04 for the 3- and 5-phosphates, respectively. In contrast, phosphatidylinositol 3,4-bisphosphate [PI(3,4)P(2)] as well as phosphatidylinositol 4,5-bisphosphate [PI(4,5)P(2)] show a biphasic pH-dependent ionization behavior that cannot be explained by a Henderson-Hasselbalch-type formalism. This biphasic behavior can be attributed to the sharing of the last remaining proton between the vicinal phosphomonoester groups. At pH 7.0, the overall charge (including the phosphodiester group charge) is found to be -3.96 +/- 0.10 for PI(3,4)P(2) and -3.99 +/- 0.10 for PI(4,5)P(2). While for PI(3,5)P(2) and PI(4,5)P(2) the charges of the individual phosphate groups in the molecule differ, they are equal for PI(3,4)P(2). Differences in the charges of the phosphomonoester groups can be rationalized on the basis of the ability of the respective phosphomonoester group to form intramolecular hydrogen bonds with adjacent hydroxyl groups. Phosphatidylinositol 3,4,5-trisphosphate shows an extraordinary complex ionization behavior. While at pH 4 the (31)P NMR peak of the 4-phosphate is found downfield from the other two phosphomonoester group peaks, an increase in pH leads to a crossover of the 4-phosphate, which positions this peak eventually upfield from the other two peaks. As a result, the 4-phosphate group shows a significantly lower charge at pH values between 7 and 9.5 than the other two phosphomonoester groups. The charge of the respective phosphomonoester group in PI(3,4,5)P(3) is lower than the corresponding charge of the phosphatidylinositol bisphosphate phosphomonoester groups, leading to an overall charge of PI(3,4,5)P(3) of -5.05 +/- 0.15 at pH 7.0. The charge of all investigated phosphoinositides at pH 7.0 is equal or higher than the corresponding charge of soluble inositol polyphosphate headgroup analogues, which is the opposite of what is expected on the basis of simple electrostatic considerations. This higher than expected headgroup charge can be rationalized with mutual intermolecular hydrogen bond formation. Measurements using different concentrations of PI(4,5)P(2) in the lipid vesicles (1, 5, and 20 mol %) did not reveal any significant concentration-dependent shift of the two phosphomonoester peaks, suggesting that PI(4,5)P(2) is clustered even at 1 mol %.
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http://dx.doi.org/10.1021/bi9008616DOI Listing
October 2009