Randomised-controlled trial of a web-based dietary intervention for patients with type 2 diabetes mellitus: Study protocol of myDIDeA

<p>Abstract</p> <p>Background</p> <p>The potential of web-based interventions in dietary behaviour modification of the diabetics has not been fully explored. We describe the protocol of a 12-month match-design randomised controlled trial of a web-based dietary intervention for type 2 diabetic patients with primary aim to evaluate the effect of the intervention on their dietary knowledge, attitude and behaviour (KAB). The secondary objective of this study is to improve the participants' dietary practices, physical measurements and biomarkers.</p> <p>Methods/Design</p> <p>A minimum total sample of 82 Type 2 diabetics will be randomised, either to the control group, who will receive the standard diabetes care or the e-intervention group, who will participate in a 6-month web-based dietary intervention in addition to the standard care. The dietary recommendations are based on existing guidelines, but personalised according to the patients' Stages of Change (SOC). The participants will be followed up for 6 months post-intervention with data collection scheduled at baseline, 6-month and 12-month.</p> <p>Discussion</p> <p>We are aiming for a net improvement in the KAB score in participants of the e-intervention group, besides investigating the impact of the e-intervention on the dietary practices, physical measurements and blood biomarkers of those patients. The successful outcome of this study can be a precursor for policy makers to initiate more rigorous promotion of such web-based programmes in the country.</p> <p>Trial registration</p> <p>Clinicaltrials.gov <a href="http://www.clinicaltrials.gov/ct2/show/NCT01246687">NCT01246687</a></p

Structure and Stability of the Spinach Aquaporin SoPIP2;1 in Detergent Micelles and Lipid Membranes

Background: SoPIP2;1 constitutes one of the major integral proteins in spinach leaf plasma membranes and belongs to the aquaporin family. SoPIP2;1 is a highly permeable and selective water channel that has been successfully overexpressed and purified with high yields. In order to optimize reconstitution of the purified protein into biomimetic systems, we have here for the first time characterized the structural stability of SoPIP2;1. Methodology/Principal Finding: We have characterized the protein structural stability after purification and after reconstitution into detergent micelles and proteoliposomes using circular dichroism and fluorescence spectroscopy techniques. The structure of SoPIP2;1 was analyzed either with the protein solubilized with octyl-beta-D-glucopyranoside (OG) or reconstituted into lipid membranes formed by E. coli lipids, diphytanoylphosphatidylcholine (DPhPC), or reconstituted into lipid membranes formed from mixtures of 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPE), 1-palmitoyl-2-oleoyl-phosphatidylethanolamine (POPE), 1-palmitoyl-2-oleoyl-phosphatidylserine (POPS), and ergosterol. Generally, SoPIP2;1 secondary structure was found to be predominantly a-helical in accordance with crystallographic data. The protein has a high thermal structural stability in detergent solutions, with an irreversible thermal unfolding occurring at a melting temperature of 58 degrees C. Incorporation of the protein into lipid membranes increases the structural stability as evidenced by an increased melting temperature of up to 70 degrees C. Conclusion/Significance: The results of this study provide insights into SoPIP2;1 stability in various host membranes and suggest suitable choices of detergent and lipid composition for reconstitution of SoPIP2;1 into biomimetic membranes for biotechnological applications

Thermal denaturation of SoPIP2;1.

<p>It can be visualized by SDS-PAGE since large aggregates are formed that cannot enter the gel. After incubation at room temperature the normal bands corresponding to monomeric, dimeric, trimeric and tetrameric SoPIP2;1 are evident. No aggregates were found at 50°C whereas at the melting point, 58°C, as determined by CD, part of the protein was aggregated. At 65°C the aggregation was complete. The samples were incubated at the indicated temperatures (25–65°C) for 10 minutes before sample loading buffer was added followed by 10 minutes incubation at room temperature. St, standard with indicated Mw in kDa in the left side of the gel.</p

MRE at 222 nm as a function of temperature.

<p>SoPIP2;1 in OG micelles (•), <i>E. coli</i> lipid membranes (□), POPE∶POPC∶POPS∶Ergosterol ( o) and POPE∶POPC (◊).</p

Summary of the SoPIP2;1 secondary structure results.

<p>Summary of the SoPIP2;1 secondary structure results.</p

Fluorescence intensity at the maximum of the emission spectra as a function of temperature.

<p>The protein reconstituted in detergent micelles show one principal transitions in comparison with the protein reconstituted in lipid membranes where at least three different transitions can be observed. Fluorescence intensity values are normalized to the higher intensity value observed with the protein in micelles suspension at 20°C.</p

Fluorescence spectroscopy analysis of the protein ternary structure behavior.

<p>A) Cartoons illustrating the Trp residues (green) position in the protein ternary structure SoPIP2;1. The structure derives from the PDB file 1Z98 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0014674#pone.0014674-TornrothHorsefield1" target="_blank">[22]</a> using VMD software is shown in i <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0014674#pone.0014674-Humphrey1" target="_blank">[50]</a>, an illustration of the protein position in detergent micelles in ii and in lipid bilayers in iii. B) Thermal unfolding of SoPIP2;1 monitored by tryptophan fluorescence. To the left, the protein is reconstituted into OG micelles and to the right the protein is reconstituted into <i>E. coli</i> lipid membranes. Temperatures are represented by the grayscale colors from black, 20°C to very light gray, 95°C.</p

Far-UV CD spectra of SoPIP2;1.

<p>The measurements were obtained at 20°C in phosphate buffer, pH 7.5, NaCl 150 mM containing 1% OG and in different lipid membranes.</p

Thermal unfolding of the secondary structure of SoPIP2;1.

<p>Protein was reconstituted in A) OG micelles, B) <i>E. coli</i> lipid membranes, C) POPE∶POPC∶POPS∶Ergosterol membranes and D) POPE∶POPC membranes. Temperatures are represented by the grayscale colors from black, 20°C to very light gray, 95°C.</p