Prolactin delays hair regrowth in mice

Mammalian hair growth is cyclic, with hair-producing follicles alternating between active (anagen) and quiescent (telogen) phases. The timing of hair cycles is advanced in prolactin receptor (PRLR) knockout mice, suggesting that prolactin has a role in regulating follicle cycling. In this study, the relationship between profiles of circulating prolactin and the first post-natal hair growth cycle was examined in female Balb/c mice. Prolactin was found to increase at 3 weeks of age, prior to the onset of anagen 1 week later. Expression of PRLR mRNA in skin increased fourfold during early anagen. This was followed by upregulation of prolactin mRNA, also expressed in the skin. Pharmacological suppression of pituitary prolactin advanced dorsal hair growth by 3.5 days. Normal hair cycling was restored by replacement with exogenous prolactin for 3 days. Increasing the duration of prolactin treatment further retarded entry into anagen. However, prolactin treatments, which began after follicles had entered anagen at 26 days of age, did not alter the subsequent progression of the hair cycle. Skin from PRLR-deficient mice grafted onto endocrine-normal hosts underwent more rapid hair cycling than comparable wild-type grafts, with reduced duration of the telogen phase. These experiments demonstrate that prolactin regulates the timing of hair growth cycles in mice via a direct effect on the skin, rather than solely via the modulation of other endocrine factors

Advanced Security Infrastructures for Grid Education

This paper describes the research conducted into advanced authorization infrastructures at the National e-Science Centre (NeSC) at the University of Glasgow and their application to support a teaching environment as part of the Dynamic Virtual Organisations in e-Science Education (DyVOSE) project. We outline the lessons learnt in teaching Grid computing and rolling out the associated security authorisation infrastructures, and describe our plans for a future, extended security infrastructure for dynamic establishment of inter-institutional virtual organisations (VO) in the education domain

A microfluidic device for array patterning by perpendicular electrokinetic focusing

This paper describes a microfluidic chip in which two perpendicular laminar-flow streams can be operated to sequentially address the surface of a flow-chamber with semi-parallel sample streams. The sample streams can be controlled in position and width by the method of electrokinetic focusing. For this purpose, each of the two streams is sandwiched by two parallel sheath flow streams containing just a buffer solution. The streams are being electroosmotically pumped, allowing a simple chip design and a setup with no moving parts. Positioning of the streams was adjusted in real-time by controlling the applied voltages according to an analytical model. The perpendicular focusing gives rise to overlapping regions, which, by combinatorial (bio) chemistry, might be used for fabrication of spot arrays of immobilized proteins and other biomolecules. Since the patterning procedure is done in a closed, liquid filled flow-structure, array spots will never be exposed to air and are prevented from drying. With this device configuration, it was possible to visualize an array of 49 spots on a surface area of 1 mm2. This article describes the principle, fabrication, experimental results, analytical modeling and numerical simulations of the microfluidic chip.\ud \ud \ud \u

Using non-covalent complexes to direct the fragmentation of glycosidic bonds in the gas phase† ††Gas Phase Ion Chemistry of Biomolecules, Part 39.

AbstractAn investigation of the gas phase chemistry of proton bound oligosaccharide (S)–ligand (L) non-covalent complexes, [S + H + L]+ has been carried out using electrospray ionization (ESI) and tandem mass spectrometry in a quadrupole ion trap. When subjected to collision-induced dissociation (CID), these [S + H + L]+ complexes undergo a range of reactions that can be broadly classified into three main types: (1) Simple dissociation into the individual monomers; (2) cleavage of the oligosaccharide to form B-type sequence ions; (3) cleavage of the ligand species. The second type of reaction is particularly interesting as it can produce a “ladder series” of [Bx + L]+ ions via ligand induced oligosaccharide bond cleavage. This novel gas phase reaction greatly simplifies the sequencing of oligosaccharides. Both the oligosaccharide and ligand were found to influence the type of reaction pathway observed, with the “ladder series” of [Bx + L]+ ions being favored for permethylated oligosaccharides and for bifunctional ligands. Cytosine is a particularly good ligand at facilitating the formation of [Bx + L]+ ions. Analogies with condensed phase chemistry of sugars is made and a potential mechanism for ligand induced oligosaccharide bond cleavage is proposed

Revisiting Hele-Shaw dynamics to better understand beach evolution

Wave action, particularly during storms, drives the evo lution of beaches. Beach evolution by non-linear break ing waves is poorly understood due to its three-dimensional character, the range of scales involved, and our limited understanding of particle-wave interactions. We show how a novel, three-phase extension to the classic “Hele-Shaw” laboratory experiment can be designed that creates beach morphologies with breaking waves in a quasi-two-dimensional setting. Our thin Hele-Shaw cell simplifies the inherent complexity of three-phase dynamics: all dynamics become clearly visible and measurable. We show that beaches can be created in tens of minutes by several types of breaking waves, with about one-second periods. Quasi-steady beach morphologies emerge as function of initial water depth, at-rest bed level and wave-maker frequency. These are classified mathematically and lead to beaches, berms and sand bars

Defining the limitations of measurements from Doppler spectral recordings

AbstractPurpose:The purpose of this study was to determine whether Doppler measurements of peak velocity and four other quantitative measures of spectral shape are affected significantly by the site of the Doppler recording in relation to the location of the maximum stenosis.Method: Continuous-wave and pulsed Doppler recordings were made distal to a 70% (area reduction or 45% diameter reduction) asymmetric stenosis in an in vitro flow model under steady and pulsatile flow conditions. Recordings were taken at six different locations proximal and distal to the stenosis. A photochromic dye technique was used to visualize the actual flow field in the model.Results: Distal to the stenosis, the flow visualization results demonstrated a strong radial and axial variation of the velocity field and thus explained why the Doppler measurements of peak frequency and spectral broadening were strongly dependent on the recording site. The peak frequency was maximum within the throat of the stenosis and returned to the prestenotic value five tube diameters distal to the stenosis. Other measurements of spectral broadening and spectral shape varied greatly depending on the location of the recording site in the poststenotic region. Higher order spectral moments such as the coefficient of kurtosis were found to exhibit large temporal variability, which makes them inappropriate as diagnostic indicators.Conclusions: Because of the complex nature of the poststenotic flow field, these results clearly demonstrate that no single Doppler measurement can accurately quantify the severity of a stenosis. Of the Doppler measurements only peak velocity is related to the severity of stenosis. Reproducible peak velocity measurements are obtained only if the Doppler sample volume is positioned at or very near the throat of the stenosis and at an appropriate radial site that may not necessarily be at the center of the vessel. (J Vasc Surg 1996;24:34-45.

Structural studies on the extracellular polysaccharides of the red algae Porphyridium cruentum and Porphyridium aerugineum

Investigations of the mucilages exuded by the red seaweeds Porphyridlum cruentum and P. aerugineum revealed many similarities between them. Both contained D-xylose, D-glucose, D- and L-galactose, 3-0-methylxylose, 3- and 4-0-methylgalactose, and D-glucuronic acid. In P. cruentum the approximate molar proportions are 3:1:2.5:0.13:0.13:0.8 and in P. aerugineum 1.7:1.0:1.1:0&dot;3:0.6:0&dot;5. In addition P. cruentum mucilage contained a 2-0-methylhexose (0.13) and 2-0-methylglucuronic acid (0.2) whereas P. aerugineum mucilage was devoid of these two sugars, but contained 2,4-di-0-methylgalactose (0.3). This is the first time methylated sugars have been reported as constituents of these mucilages. Both polysaccharides contained about 10 half ester sulphate and appeared to be linked to about 5% protein. Attempted fractionation into homopolysaccharides was unsuccessful. The separation and characterisation of oligosaccharides containing glucose, galactose and xylose; glucose and galactose; and glucose and xylose confirmed that single polydisperse heteropolysaccharides are present. Methylation and periodate oxidation studies revealed that the glucuronic acid is 1,3-linked and is attached solely to C-3 of B-galactose in both mucilages. The 2-0-methylglucuronic acid in P. cruentum is linked to C-4 of L-galactose. Xylose, glucose and galactose are present in both mucilages as end group 1,3- and 1,4 linked residues with the galactose and glucose also present as 1,3,4 linked branch points. Desulphation and infrared studies indicate that the half ester sulphate may be located at C-6 of 1,3-linked hexose units and at C-2 and/or C-3 of 1,4 linked units. If this is so then in P. aerugineum mucilage the units must be in the unfavourable conformation. Molecular weight determinations on Sepharose 4-B of the original mucilages, the methylated materials and the polyalcohols before and after cleavage of the acetal linkages indicated a molecular weight of6 6.4 x 10 for P. cruenturn and 5 x 10 for P. aerugineum. Methylationand periodate oxidation caused considerable degradation of the polymers. The partially hydrolysed polyalcohols have molecular weights (confirmedby high pressure liquid chromatography) of about 30,000.In spite of the considerable similarity of these exudates, that from P. aerugineum has about ten times the viscosity of that from P. cruentum. It is tentatively suggested that this is connected with the different conformation of some of the sulphated residues which would alter the shape of the macromolecule. Also included in this thesis are structural studies on a purified fucoidan (Appendix I), methylation of starch extracted from Chroomonas salina (Appendix II) and a preliminary investigation of the polysaccharides from the red algae Constantinea subulifera and c simplex (Appendix III).<p

Analysis by x-ray microtomography of a granular packing undergoing compaction

Several acquisitions of X-ray microtomography have been performed on a beads packing while it compacts under vertical vibrations. An image analysis allows to study the evolution of the packing structure during its progressive densification. In particular, the volume distribution of the pores reveals a large tail, compatible to an exponential law, which slowly reduces as the system gets more compact. This is quite consistent, for large pores, with the free volume theory. These results are also in very good agreement with those obtained by a previous numerical model of granular compaction.Comment: 4 pages, 4 figures. Latex (revtex4). to be published in Phys. Rev.

Reduction and Emergence in Bose-Einstein Condensates

A closer look at some proposed Gedanken-experiments on BECs promises to shed light on several aspects of reduction and emergence in physics. These include the relations between classical descriptions and different quantum treatments of macroscopic systems, and the emergence of new properties and even new objects as a result of spontaneous symmetry breaking