Nuclear Overhauser effect as a probe of molecular structure, dynamics and order of axially reorienting molecules in membranes.

The location, orientation, order and dynamics of cholesterol in model membranes have been well characterized, therefore cholesterol is an ideal molecule for developing new methods for studying structured molecules undergoing rapid axially symmetric reorientation. The use of (13)C filtering via short contact cross polarization transfer to (1)H allows the recovery of the weak cholesterol (1)H magic angle spinning NMR signals from beneath the strong phospholipid background in bicelles composed of chain perdeuterated dimyristoyl phosphatidylcholine/dicaproyl phosphatidylcholine/[3,4-(13)C]-cholesterol. Measurements of the nuclear Overhauser enhancement for (1)H nuclei located in the first ring of cholesterol are interpreted in terms of a simple two motion model consisting of axial reorientation, with a correlation time τ∥, and a slower reorientation of the diffusion axis relative to the bilayer normal, with correlation time τ⊥. This approach can be extended to other molecules which undergo rapid axial reorientation such as small membrane associated peptides.

A regulatory toolbox of MiniPromoters to drive selective expression in the brain.

The Pleiades Promoter Project integrates genomewide bioinformatics with large-scale knockin mouse production and histological examination of expression patterns to develop MiniPromoters and related tools designed to study and treat the brain by directed gene expression. Genes with brain expression patterns of interest are subjected to bioinformatic analysis to delineate candidate regulatory regions, which are then incorporated into a panel of compact human MiniPromoters to drive expression to brain regions and cell types of interest. Using single-copy, homologous-recombination "knockins" in embryonic stem cells, each MiniPromoter reporter is integrated immediately 5' of the Hprt locus in the mouse genome. MiniPromoter expression profiles are characterized in differentiation assays of the transgenic cells or in mouse brains following transgenic mouse production. Histological examination of adult brains, eyes, and spinal cords for reporter gene activity is coupled to costaining with cell-type-specific markers to define expression. The publicly available Pleiades MiniPromoter Project is a key resource to facilitate research on brain development and therapies.

[Nursing process for patients treated with negative pressure therapy afther severe foottrauma]. / Proces sestrinske skrbi kod pacijenata lijecenih negativnim tlakom nakon teske ozljede stopala.

Foot injuries inflicted by firearms and high pressure washing machines cause distortion of psychophysical and biomechanical characteristics with decrease of ability to satisfy the basic human needs and existing mode of living. Treatment with negative pressure accelerates wound healing process and recovery. Nursing role is significant in all these problems, which arise as patient reaction to the severe trauma. With the extensive surgical procedures required and nursing intervention, the actual and potential patient problems are minimized or eliminated, as evidenced from the good functional and esthetic results, and resuming independence and usual daily activities.

Drosophila O-GlcNAc transferase (OGT) is encoded by the Polycomb group (PcG) gene, super sex combs (sxc).

O-linked N-acetylglucosamine transferase (OGT) reversibly modifies serine and threonine residues of many intracellular proteins with a single beta-O-linked N-acetylglucosamine residue (O-GlcNAc), and has been implicated in insulin signaling, neurodegenerative disease, cellular stress response, and other important processes in mammals. OGT also glycosylates RNA polymerase II and various transcription factors, which suggests that it might be directly involved in transcriptional regulation. We report here that the Drosophila OGT is encoded by the Polycomb group (PcG) gene, super sex combs (sxc). Furthermore, major sites of O-GlcNAc modification on polytene chromosomes correspond to PcG protein binding sites. Our results thus suggest a direct role for O-linked glycosylation by OGT in PcG-mediated epigenetic gene silencing, which is important in developmental regulation, stem cell maintenance, genomic imprinting, and cancer. In addition, we observe rescue of sxc lethality by a human Ogt cDNA transgene; thus Drosophila may provide an ideal model to study important functional roles of OGT in mammals.

Small molecule interaction with lipid bilayers: a molecular dynamics study of chlorhexidine.

Chlorhexidine (CHX) is an effective anti-bacterial agent whose mode of action is thought to be the disruption of the cell membrane. We tested the capability of the Slipids all atom force fields using data from neutron scattering and NMR experiments on the drug chlorhexidine in a 1,2-dimyrisoyl-3-sn-phosphatidylcholine (DMPC) membrane. Since it is not known what the charge of the CHX molecule is inside an apolar environment, a neutral, as well as a +1 and +2 charge model for the molecule were created and tested at several concentrations. This study shows that the location of CHX is minorly dependent on concentration, and dominantly reliant on the charge. The effect of adding CHX to DMPC is a thinning of the membrane, thus increasing the area per lipid.

Location of chlorhexidine in DMPC model membranes: a neutron diffraction study.

Chlorhexidine (CHX) is an effective anti-bacterial agent whose mode of action is thought to be the disruption of the cell membrane. It is known to partition into phospholipid bilayers of aqueous model-membrane preparations. Neutron diffraction data taken at 36 degrees C on the location of CHX in phosphatidylcholine (PC) bilayers is presented. The center of mass of the deuterated hydrocarbon chain of CHX is found to reside 16A from the center of the bilayer in 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (14:0-14:0PC). This places the drug near the glycerol backbone of the lipid, and suggests a mode of action whereby the molecule is bent in half and inserts wedge-like into the lipid matrix. This mechanism is distinct from detergent-like mechanisms of membrane disruption and more similar to some anti-microbial peptide action, where peptides insert obliquely into the bilayer headgroup region to disrupt its structure.