Polymorphisms of the endothelial nitric oxide synthase (NOS3) gene in preeclampsia: a candidate-gene association study

<p>Abstract</p> <p>Background</p> <p>The endothelial nitric oxide synthase gene (<it>NOS3</it>) has been proposed as a candidate gene for preeclampsia. However, studies so far have produced conflicting results. This study examines the specific role of variants and haplotypes of the <it>NOS3 </it>gene in a population of Caucasian origin.</p> <p>Methods</p> <p>We examined the association of three common variants of the <it>NOS3 </it>gene (4b/a, T-786C and G894T) and their haplotypes in a case-control sample of 102 patients with preeclampsia and 176 women with a history of uncomplicated pregnancies. Genotyping for the <it>NOS3 </it>variants was performed and odds ratios and 95% confidence intervals were obtained to evaluate the association between <it>NOS3 </it>polymorphisms and preeclampsia.</p> <p>Results</p> <p>The single locus analysis for the three variants using various genetic models and a model-free approach revealed no significant association in relation to clinical status. The analysis of haplotypes also showed lack of significant association.</p> <p>Conclusions</p> <p>Given the limitations of the candidate-gene approach in investigating complex traits, the evidence of our study does not support the major contributory role of these common <it>NOS3 </it>variants in preeclampsia. Future larger studies may help in elucidating the genetics of preeclampsia further.</p

Evidence for the adaptation of protein pH-dependence to subcellular pH

<p>Abstract</p> <p>Background</p> <p>The availability of genome sequences, and inferred protein coding genes, has led to several proteome-wide studies of isoelectric points. Generally, isoelectric points are distributed following variations on a biomodal theme that originates from the predominant acid and base amino acid sidechain pKas. The relative populations of the peaks in such distributions may correlate with environment, either for a whole organism or for subcellular compartments. There is also a tendency for isoelectric points averaged over a subcellular location to not coincide with the local pH, which could be related to solubility. We now calculate the correlation of other pH-dependent properties, calculated from 3D structure, with subcellular pH.</p> <p>Results</p> <p>For proteins with known structure and subcellular annotation, the predicted pH at which a protein is most stable, averaged over a location, gives a significantly better correlation with subcellular pH than does isoelectric point. This observation relates to the cumulative properties of proteins, since maximal stability for individual proteins follows the bimodal isoelectric point distribution. Histidine residue location underlies the correlation, a conclusion that is tested against a background of proteins randomised with respect to this feature, and for which the observed correlation drops substantially.</p> <p>Conclusion</p> <p>There exists a constraint on protein pH-dependence, in relation to the local pH, that is manifested in the pKa distribution of histidine sub-proteomes. This is discussed in terms of protein stability, pH homeostasis, and fluctuations in proton concentration.</p

Qualitative research methods in neurosurgery: an unexplored avenue.

OBJECTIVE: Explore the value and potential of qualitative research to neurosurgery and provide insight and understanding to this underused methodology. BACKGROUND: The definition of qualitative research is critically discussed and the heterogeneity within this field of inquiry explored. The value of qualitative research to the field of neurosurgery is articulated through its contribution to understanding complex clinical problems. DISCUSSION: To resolve some of the misunderstanding of qualitative research, this paper discusses research design choices. We explore approaches that use qualitative techniques but are not, necessarily, situated within a qualitative paradigm in addition to how qualitative research philosophy aids researchers to conduct interpretive inquiry that can reveal more than simply what was said by participants. Common research designs associated with qualitative inquiry are introduced, and how complex analysis may contribute more in-depth insights is explained. Approaches to quality are discussed briefly to support improvements in qualitative methods and qualitative manuscripts. Finally, we consider the future of qualitative research in neurosurgery, and suggest how to move forward in the qualitative neurosurgical evidence base. CONCLUSION: There is enormous potential for qualitative research to contribute to the advancement of person-centred care within neurosurgery. There are signs that more qualitative research is being conducted and that neurosurgical journals are increasingly open to this methodology. While studies that do not engage fully within the qualitative paradigm can make important contributions to the evidence base, due regard should be given to immersive inquiry within qualitative paradigms to allow complex, in-depth, investigations of the human experience

Molecular basis for temperature sensing by an RNA thermometer

Regulatory RNA elements, like riboswitches, respond to intracellular signals by three-dimensional (3D) conformational changes. RNA thermometers employ a similar strategy to sense temperature changes in the cell and regulate the translational machinery. We present here the first 3D NMR structure of the functional domain of a highly conserved bacterial RNA thermometer containing the ribosome binding site that remains occluded at normal temperatures (30°C). We identified a region adjacent to the Shine–Dalgarno sequence that has a network of weak hydrogen bonds within the RNA helix. With the onset of heat shock at 42°C, destabilisation of the RNA structure initiates at this region and favours the release of the ribosome binding site and of the start codon. Deletion of a highly conserved G residue leads to the formation of a stable regular RNA helix that loses thermosensing ability. Our results indicate that RNA thermometers are able to sense temperature changes without the aid of accessory factors

The Accuracy of Generalized Born Forces

Generalized Born (GB) models play an important role in biomolecular dynamics simulations. The issue of the accuracy of solvation forces computed according to these models has not been investigated in much detail to the best of our knowledge. Optimal atomic radii have been derived for most used force fields in order to reproduce molecular dynamics results under the Poisson\u2013Boltzmann (PB) continuum model. In principle, if optimized radii are used, the PB model reproduces well MD simulations. For this reason in this contribution, we consider the most used GB model implementations in publicly available molecular dynamics simulation softwares and assess the accuracy of GB solvation forces compared to the reference PB ones. The results show that current implementations that compute forces by pairwise summations correlate very well with PB forces if judicious choice of model parameters is performed. The latter can be obtained by linear fitting of solvation self-energies computed by the most accurate GBR6 GB model