Search results

Filter

Filetype

Your search for "*" yielded 530826 hits

Observation of structural anisotropy and the onset of liquidlike motion during the nonthermal melting of InSb

The melting dynamics of laser excited InSb have been studied with femtosecond x-ray diffraction. These measurements observe the delayed onset of diffusive atomic motion, signaling the appearance of liquidlike dynamics. They also demonstrate that the root-mean-squared displacement in the [111] direction increases faster than in the [110] direction after the first 500 fs. This structural anisotropy

Proghrelin-derived peptides influence the secretion of insulin, glucagon, pancreatic polypeptide and somatostatin: A study on isolated islets from mouse and rat pancreas.

Proghrelin, the precursor of the orexigenic and adipogenic peptide hormone ghrelin, is synthetized in endocrine (A-like) cells in the gastric mucosa. During its cellular processing, proghrelin gives rise to the 28-amino acid peptide desacyl ghrelin, which after octanoylation becomes active acyl ghrelin, and to the 23-amino acid peptide obestatin, claimed to be a physiological opponent of acyl ghre

Symmetries of quantum graphs and the inverse scattering problem

The Schrodinger equation on a graph together with a set of self-adjoint boundary conditions at the vertices determine a quantum graph. If the graph has one or more infinite edges one can associate a scattering matrix to the quantum graph. It is proved that if such a graph has internal symmetries then the boundary conditions, and hence the self-adjoint operator describing the quantum system, in gen

Bone-marrow-derived cells contribute to the recruitment of microglial cells in response to beta-amyloid deposition in APP/PS1 double transgenic Alzheimer mice

The role of microglia recruited from bone marrow (BM) into the CNS during the progression of Alzheimer's disease (AD) is poorly understood. To investigate whether beta-amyloid (Abeta) associated microglia are derived from blood monocytes, we transplanted BM cells from enhanced green fluorescent protein expressing mice into young or old transgenic AD mice and determined the engraftment of BM-derive

Early attachment of leucocytes, platelets and fibrinogen in endothelial cell-seeded Dacron venous conduits

BACKGROUND: There is a need for prosthetic venous conduits in surgery for trauma, cancer and thrombotic disease. Such conduits in use today have a low patency rate, leaving room for much improvement. METHODS: This experimental study investigated the dynamics of the early attachment of radiolabelled platelets, leucocytes and fibrinogen to endothelial cell-seeded Dacron venous conduits in sheep. Gra

Solar mean magnetic field variability: A wavelet approach to Wilcox Solar Observatory and SOHO/Michelson Doppler Imager observations

Solar mean magnetic field (SMMF) measurements from the Wilcox Solar Observatory and with the SOHO/MDI instrument are described and analyzed. Even though two completely different methods of observation are used, the two data sets obtained show a strong similarity. Using continuous wavelet transforms, SMMF variability is found at a number of temporal scales. Detected SMMF signals with a 1–2 year per

Measurements of the optical properties of tissue in conjunction with photodynamic therapy

A simple optical dosimeter was used to measure the light intensity in rat liver and muscle in vivo with fibers positioned at different depths to investigate whether the light penetration changed during photodynamic therapy (PDT). The results were then correlated with measurements of the three optical-interaction coefficients mu(s), mu(a), and g for wavelengths in the range 500-800 nm for PDT-treat

Annual routines of non-migratory birds: optimal moult strategies

In a periodically changing environment it is important for animals to properly time the major events of their life in order to maximise their lifetime fitness. For a non-migratory bird the timing of breeding and moult are thought to be the most crucial. We develop a state-dependent optimal annual routine model that incorporates explicit density dependence in the food supply. In the model the birds

Transgressive oolites onlapping a Silurian rocky shoreline unconformity, Gotland, Sweden.

Stratigraphical relationships, facies and petrographical evidences define a rocky shoreline in the Late Wenlock of Gotland. The major facies-elements forming the rocky shoreline are 1) several subaerially exposed reefs, which were eroded during falling base-level and which form the topography, and 2), onlap of oolite grainstones which were deposited during the subsequent rise of the base-level. Fi

Cloning and functional characterization of a phospholipid:diacylglycerol acyltransferase from Arabidopsis

A new pathway for triacylglycerol biosynthesis involving a phospholipid:diacylglycerol acyltransferase (PDAT) was recently described (Dahlqvist A, Stahl U, Lenman M, Banas A, Lee M, Sandager L, Ronne H, Stymne S, [2000] Proc Natl Acad Sci USA 97: 6487-6492). The LRO1 gene that encodes the PDAT was identified in yeast (Saccharomyces cerevisiae) and shown to have homology with animal lecithin:choles

Lipids as cofactors in protein folding: Stereo-specific lipid-protein interactions are required to form HAMLET (human alpha-lactalbumin made lethal to tumor cells).

Proteins can adjust their structure and function in response to shifting environments. Functional diversity is created not only by the sequence but by changes in tertiary structure. Here we present evidence that lipid cofactors may enable otherwise unstable protein folding variants to maintain their conformation and to form novel, biologically active complexes. We have identified unsaturated C18 f

Carrier medium exchange through ultrasonic particle switching in microfluidic channels

This paper describes a method, utilizing acoustic force manipulation of suspended particles, in which particles in a laminar flow microchannel are continuously translated from one medium to another with virtually no mixing of the two media. During the study, 5-mum polyamide spheres suspended in distilled water, spiked (contaminated) with Evans blue, were switched over to clean distilled water. Mor

Experimental and theoretical evidence of overcharging of calcium silicate hydrate

Electrokinetic measurements such as electrophoresis may show an inversion of the effective surface charge of colloidal particle called overcharging. This phenomenon has been studied by various theoretical approaches but up to now very few attempts of confrontation between theory and experiment have been conducted. In this work we report electrophoretic measurements as well as Monte Carlo simulatio

A high-density putative monomeric mucin is the major [(35)S]labelled macromolecular product of human colorectal mucins in organ culture.

We have studied the biosynthesis of mucins in organ cultures of human colon using isopycnic density-gradient centrifugation following pulse labelling with [35S]sulphate and [3H]-D-glucosamine. A high-density [35S]sulphate labelled component, of larger size than MUC2 monomers, appeared in the tissue and also in the medium. It was not degraded by reduction, trypsin digestion, digestion with chondroi

Malignant lesions in the ventral prostate of alloxan-induced diabetic rats

The aim of this study was to evaluate the changes caused by chronic diabetes in the rat ventral prostate and to establish a correlation between diabetes and the development of prostatic lesions. Male rats received alloxan (42 mg/kg b.w.) to induce diabetes. Ninety days after diabetes diagnosis, animals were sacrificed and the ventral prostate was removed and prepared for general and immunohistoche

Role of Aromatic Side Chains in the Binding of Volatile General Anesthetics to a Four-alpha-helix Bundle.

Currently, the mechanism by which anesthesia occurs is thought to involve the direct binding of inhaled anesthetics to ligand-gated ion channels. This hypothesis is being studied using four--helix bundles as model systems for the transmembrane domains of the natural "receptor" proteins. This study concerns the role in anesthetic binding played by aromatic side chains in the binding cavity of a fou