Does child weight influence how mothers report their feeding practices?

Objectives. The present study aimed to ascertain whether parental reports of their feeding practices are associated with independent observations of these behaviours, and whether the reliability of maternal report depends upon the child's weight. Methods. A total of 56 mothers and their children ate a lunch to satiety which was videotaped and coded for maternal use of control during feeding. Mothers also completed questionnaires about their feeding practices and children were weighed and measured. Results. Maternal reports of controlling feeding practices were poorly related to independent observations of these behaviours in the laboratory. However, there was a significant interaction between child BMI z score and observed pressure to eat in predicting maternally reported pressure to eat. There was also a significant interaction between child BMI z score and observed maternal restriction with food in predicting maternally reported restriction. When decomposed, these interactions suggested that only mothers of relatively underweight children were accurate at reporting their use of pressure to eat when compared to independent observations. For mothers of relatively overweight children there was a significant negative relationship between observed and reported restriction over food. Conclusions. Overall there was poor correspondence between maternal reports and independent observations of the use of controlling feeding practices. Further research is needed to replicate these findings and to ascertain whether parents who are inaccurate at reporting their use of these feeding practices are unaware that they are using controlling feeding practices or whether they are responding in socially desirable ways to questionnaires assessing their feeding behaviour. © 2011 Informa Healthcare

Conformational dynamics is more important than helical propensity for the folding of the all alpha-helical protein Im7

Im7 folds via an on-pathway intermediate that contains three of the four native α-helices. The missing helix, helix III, is the shortest and its failure to be formed until late in the pathway is related to frustration in the structure. Im7H3M3, a 94-residue variant of the 87-residue Im7 in which helix III is the longest of the four native helices, also folds via an intermediate. To investigate the structural basis for this we calculated the frustration in the structure of Im7H3M3 and used NMR to investigate its dynamics. We found that the native state of Im7H3M3 is highly frustrated and in equilibrium with an intermediate state that lacks helix III, similar to Im7. Model-free analysis identified residues with chemical exchange contributions to their relaxation that aligned with the residues predicted to have highly frustrated interactions, also like Im7. Finally, we determined properties of urea-denatured Im7H3M3 and identified four clusters of interacting residues that corresponded to the α-helices of the native protein. In Im7 the cluster sizes were related to the lengths of the α-helices with cluster III being the smallest but in Im7H3M3 cluster III was also the smallest, despite this region forming the longest helix in the native state. These results suggest that the conformational properties of the urea-denatured states promote formation of a three-helix intermediate in which the residues that form helix III remain non-helical. Thus it appears that features of the native structure are formed early in folding linked to collapse of the unfolded state

Use of the lambda Red recombinase system to rapidly generate mutants in Pseudomonas aeruginosa

<p>Abstract</p> <p>Background</p> <p>The Red recombinase system of bacteriophage lambda has been used to inactivate chromosomal genes in various bacteria and fungi. The procedure consists of electroporating a polymerase chain reaction (PCR) fragment that was obtained with a 1- or 3-step PCR protocol and that carries an antibiotic cassette flanked by a region homologous to the target locus into a strain that expresses the lambda Red recombination system.</p> <p>Results</p> <p>This system has been modified for use in <it>Pseudomonas aeruginosa</it>. Chromosomal DNA deletions of single genes were generated using 3-step PCR products containing flanking regions 400–600 nucleotides (nt) in length that are homologous to the target sequence. A 1-step PCR product with a homologous extension flanking region of only 100 nt was in some cases sufficient to obtain the desired mutant. We further showed that the <it>P. aeruginosa </it>strain PA14 non-redundant transposon library can be used in conjunction with the lambda Red technique to rapidly generate large chromosomal deletions or transfer mutated genes into various PA14 isogenic mutants to create multi-locus knockout mutants.</p> <p>Conclusion</p> <p>The lambda Red-based technique can be used efficiently to generate mutants in <it>P. aeruginosa</it>. The main advantage of this procedure is its rapidity as mutants can be easily obtained in less than a week if the 3-step PCR procedure is used, or in less than three days if the mutation needs to be transferred from one strain to another.</p

In-cell NMR in E. coli to Monitor Maturation Steps of hSOD1

In-cell NMR allows characterizing the folding state of a protein as well as posttranslational events at molecular level, in the cellular context. Here, the initial maturation steps of human copper, zinc superoxide dismutase 1 are characterized in the E. coli cytoplasm by in-cell NMR: from the apo protein, which is partially unfolded, to the zinc binding which causes its final quaternary structure. The protein selectively binds only one zinc ion, whereas in vitro also the copper site binds a non-physiological zinc ion. However, no intramolecular disulfide bridge formation occurs, nor copper uptake, suggesting the need of a specific chaperone for those purposes

Solution structure of a repeated unit of the ABA-1 nematode polyprotein allergen of ascaris reveals a novel fold and two discrete lipid-binding sites

Parasitic nematode worms cause serious health problems in humans and other animals. They can induce allergic-type immune responses, which can be harmful but may at the same time protect against the infections. Allergens are proteins that trigger allergic reactions and these parasites produce a type that is confined to nematodes, the nematode polyprotein allergens (NPAs). These are synthesized as large precursor proteins comprising repeating units of similar amino acid sequence that are subsequently cleaved into multiple copies of the allergen protein. NPAs bind small lipids such as fatty acids and retinol (Vitamin A) and probably transport these sensitive and insoluble compounds between the tissues of the worms. Nematodes cannot synthesize these lipids, so NPAs may also be crucial for extracting nutrients from their hosts. They may also be involved in altering immune responses by controlling the lipids by which the immune and inflammatory cells communicate. We describe the molecular structure of one unit of an NPA, the well-known ABA-1 allergen of Ascaris and find its structure to be of a type not previously found for lipid-binding proteins, and we describe the unusual sites where lipids bind within this structur

Assessing the context of health care utilization in Ecuador: A spatial and multilevel analysis

<p>Abstract</p> <p>Background</p> <p>There are few studies that have analyzed the context of health care utilization, particularly in Latin America. This study examines the context of utilization of health services in Ecuador; focusing on the relationship between provision of services and use of both preventive and curative services.</p> <p>Methods</p> <p>This study is cross-sectional and analyzes data from the 2004 National Demographic and Maternal & Child Health dataset. Provider variables come from the Ecuadorian System of Social Indicators (SIISE). Global Moran's I statistic is used to assess spatial autocorrelation of the provider variables. Multilevel modeling is used for the simultaneous analysis of provision of services at the province-level with use of services at the individual level.</p> <p>Results</p> <p>Spatial analysis indicates no significant differences in the density of health care providers among Ecuadorian provinces. After adjusting for various predisposing, enabling, need factors and interaction terms, density of public practice health personnel was positively associated with use of preventive care, particularly among rural households. On the other hand, density of private practice physicians was positively associated with use of curative care, particularly among urban households.</p> <p>Conclusions</p> <p>There are significant public/private, urban/rural gaps in provision of services in Ecuador; which in turn affect people's use of services. It is necessary to strengthen the public health care delivery system (which includes addressing distribution of health workers) and national health information systems. These efforts could improve access to health care, and inform the civil society and policymakers on the advances of health care reform.</p

Pancreatitis and pancreatic cancer in two large pooled case–control studies

The association between duration of pancreatitis and pancreatic cancer has not been well characterized in large population-based studies. We conducted detailed analyses to determine the association between pancreatitis onset and pancreatic cancer risk. Data from two case–control studies of pancreatic cancer (n = 4515) in the San Francisco Bay Area and the M.D. Anderson Cancer Center were pooled for analysis (1,663 cases, 2,852 frequency-matched controls). Adjusted odds ratios (OR) were estimated using a random-effects model. In the pooled multivariable model, history of pancreatitis was associated with a 7.2-fold increased risk estimate for pancreatic cancer [95% confidence interval (CI): 4.0, 13]. The risk estimate was nearly 10-fold in participants aged &lt;55 years (OR = 9.9, 95% CI: 3.5, 28). A shorter temporal history of pancreatitis was more closely associated with pancreatic cancer than was a longer temporal history: &lt;3 years (OR = 29, 95% CI: 12, 71), 3–10 years (OR = 2.6, 95% CI: 1.5, 5.6), and &gt;10 years (OR = 1.8, 95% CI: 0.7, 4.5, p trend &lt; 0.001). A short temporal history of pancreatitis was highly associated with pancreatic cancer, suggesting that pancreatitis may be an early manifestation of pancreatic cancer in some individuals. Pancreatic cancer should be considered in the differential diagnosis of individuals with an episode of pancreatitis

NMR Characterizations of the Ice Binding Surface of an Antifreeze Protein

Antifreeze protein (AFP) has a unique function of reducing solution freezing temperature to protect organisms from ice damage. However, its functional mechanism is not well understood. An intriguing question concerning AFP function is how the high selectivity for ice ligand is achieved in the presence of free water of much higher concentration which likely imposes a large kinetic barrier for protein-ice recognition. In this study, we explore this question by investigating the property of the ice binding surface of an antifreeze protein using NMR spectroscopy. An investigation of the temperature gradient of amide proton chemical shift and its correlation with chemical shift deviation from random coil was performed for CfAFP-501, a hyperactive insect AFP. A good correlation between the two parameters was observed for one of the two Thr rows on the ice binding surface. A significant temperature-dependent protein-solvent interaction is found to be the most probable origin for this correlation, which is consistent with a scenario of hydrophobic hydration on the ice binding surface. In accordance with this finding, rotational correlation time analyses combined with relaxation dispersion measurements reveals a weak dimer formation through ice binding surface at room temperature and a population shift of dimer to monomer at low temperature, suggesting hydrophobic effect involved in dimer formation and hence hydrophobic hydration on the ice binding surface of the protein. Our finding of hydrophobic hydration on the ice binding surface provides a test for existing simulation studies. The occurrence of hydrophobic hydration on the ice binding surface is likely unnecessary for enhancing protein-ice binding affinity which is achieved by a tight H-bonding network. Subsequently, we speculate that the hydrophobic hydration occurring on the ice binding surface plays a role in facilitating protein-ice recognition by lowering the kinetic barrier as suggested by some simulation studies