Durotactic control within a 3D collagen matrix

INTRODUCTION: While matrix stiffness has been implicated in cell adhesion and migration, most studies have focused on the effects of substrate stiffness in 2D. This work describes a novel continuous stiffness gradient model for studying such processes in 3D

Constipation in children

Constipation in children is a universal problem, occurring in 0.7-28% of the population. The exact aetiology is unknown, but the majority of children have a functional, rather than organic, aetiology. Symptoms associated with constipation include abdominal pain, a poor appetite and faecal incontinence, all of which interfere with the quality of life of the child and his or her family. Early intervention with appropriate management is necessary to prevent ongoing sequelae. Once an organic cause has been excluded, a programme of intervention should be implemented, namely evacuation of any faecal mass present, followed by regular maintenance therapy to encourage evacuation of a daily soft stool for at least 2-3 months, prior to gradual withdrawal. Emotional support, exercise and dietary modification are linked to the therapy and will ensure a successful outcome. Failure to implement the protocol may result in ongoing problems in up to 50% of children as theyenter adulthood

Flow-distributed spikes for Schnakenberg kinetics

This is the post-print version of the final published paper. The final publication is available at link.springer.com by following the link below. Copyright @ 2011 Springer-Verlag.We study a system of reaction–diffusion–convection equations which combine a reaction–diffusion system with Schnakenberg kinetics and the convective flow equations. It serves as a simple model for flow-distributed pattern formation. We show how the choice of boundary conditions and the size of the flow influence the positions of the emerging spiky patterns and give conditions when they are shifted to the right or to the left. Further, we analyze the shape and prove the stability of the spikes. This paper is the first providing a rigorous analysis of spiky patterns for reaction-diffusion systems coupled with convective flow. The importance of these results for biological applications, in particular the formation of left–right asymmetry in the mouse, is indicated.RGC of Hong Kon

The discolouration of human teeth from archaeological contexts: Elemental analysis of a black tooth from a Roman cranium recovered from the River Witham, Lincoln, UK.

A human cranium was recovered from the River Witham, Lincoln, UK, at Stamp End Lock during a police operation in 2002. Although extensive trauma was noted, the skull was not of forensic interest since radiocarbon dating revealed that the individual had lived during the Roman occupation of Lincoln, almost 2,000 years ago. The skull had unusual black “metallic” staining on the occlusal surfaces of the teeth. As this kind of staining is relatively uncommon, it was investigated to determine the possible cause. An individual tooth was subjected to two elemental analyses: inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX). A small sample of modern teeth was also analysed for comparison to determine “normal” ranges of certain elements. Analysis of the ancient tooth shows very high levels of manganese (275 µg/g) and iron (1540 µg/g) compared to modern teeth values (1.90 µg/g Mn and 40.81 µg/g Fe). These results were consistent with the black staining arising from iron and manganese infiltrating bone and dental tissue from the depositional environment, and not a consequence of diet, pathological process or cultural practices

Posttranslational modification of a neurofilament protein during axoplasmic transport: implications for regional specialization of CNS axons

The possibility that proteins are modified during axoplasmic transport in central nervous system axons was examined by analyzing neurofilament proteins (200,000, 140,000, and 70,000 mol wt) along the mouse primary optic pathway (optic nerve and optic tract). The major neurofilament proteins (NFPs) exhibited considerable microheterogeneity. At least three forms of the “ 140,000” neurofilament protein differing in molecular weight by SDS PAGE (140,000-145,000 mol wt) were identified. The “140,000” proteins, and their counterparts in purified neurofilament preparations, displayed similar isoelectric points and the same peptide maps. The “140,000” NFPs exhibited regional heterogeneity when consecutive segments of the optic pathway were separately examined on polyacrylamide gels. Two major species (145,000 and 140,000 mol wt) were present along the entire length of the optic pathway. The third protein (143,000 mol wt) was absent proximally but became increasingly prominent in distal segments. After intravitreal injection of [(3)H]proline, newly synthesized radiolabeled proteins in the “140,000” mol wt region entered proximal mouse retinal ganglion cell (RGC) axons as two major species corresponding to the 145,000 and 14,000 mol wt NFPs observed on stained gels. When transported NFPs reached more distal axonal regions (30 d postinjection or longer), a 143,000 mol wt protein appeared that was similar in isoelectric point and peptide map to the 145,000 and 140,000 mol wt species. The results suggest that (a) the composition of CNS neurofilaments, particularly the “140,000” component, is more complex than previously recognized, that (b) retinal ganglion cell axons display regional differentiation with respect to these cytoskeletal proteins, and that (c) structural heterogeneity of “140,000” NFPs arises, at least in part, from posttranslational modification during axoplasmic transport. When excised but intact optic pathways were incubated in vitro at pH 7.4, a 143,000 NFP was rapidly formed by a calcium-dependent enzymatic process active at endogenous calcium levels. Changes in major proteins other than those in the 145,000-140,000 mol wt region were minimal. In optic pathways from mice injected intravitreally with L-[(3)H]proline, tritiated 143,000 mol wt NFP formed rapidly in vitro if radioactively labeled NFPs were present in distal RGC axonal regions (31 d postinjection). By contrast, no 143,000 mol wt NFP was generated if radioactively labeled NFPs were present proximally in RGC axons (6 d postinjection). The enzymatic process that generates 143,000 mol wt NFP in vitro, therefore, appears to have a nonuniform distribution along the RGC axons. The foregoing results and other observations, including the accompanying report (J. Cell Biol., 1982, 94:159-164), imply that CNS axons may be regionally specialized with respect to structure and function

Some rare presentations of hydatid cysts: two case reports

Hydatid disease is a considerable health problem worldwide. Two case reports of relatively uncommon presentations of the disease are presented

Introducing stable microgrooves in to fluid-leaving surface of plastic compressed collagen by embossing

Micropatterning of polymers is a technique used in tissue engineering to create additional features on the surface usually to manipulate cell behaviour. However, methods used for fabrication of such features on the surface of synthetic polymers are not always suitable for natural polymers. Here we describe a method of embossing developed for plastic compressed collagen constructs. Plastic compression (PC) of collagen is a technique that allows cell-independent fabrication of dense, tissue-like collagen constructs without compromising viability of resident cells (1). Method of PC creates potential anisotropy of the opposite surfaces – stiffer fluid leaving (closest to the blotting elements) and more elastic non-fluid leaving surface. We hypothesized that embossing into these surfaces will give more stable features on the fluid-leaving surface (FLS) as opposed to non fluid-leaving surface (NFLS). Objectives were to develop methods of embossing onto both surfaces, assess these features and to determine stability of the embossed pattern over time with and without cells. Slow-dissolving phosphate-based glass fibers were used as the embossing template in this study as fiber diameter and spacing is easily controlled

Endoscopic injection sclerotherapy for bleeding varices in children with intrahepatic and extrahepatic portal venous obstruction: Benefit of injection tract embolisation

Background. The outcome of sclerotherapy for bleeding oesophagealvarices may be influenced by injection technique. In a previous study at our institution, sclerotherapy was associated with a high re-bleeding rate and oesophageal ulceration. Embolisation of the injection tract was introduced in an attempt to reduce injectionrelated complications.Methods. To determine the outcome and effectiveness of injectiontract embolisation in reducing injection-related complications, weretrospectively reviewed a series of 59 children who underwent injection sclerotherapy for oesophageal varices (29 for extrahepatic portal vein obstruction (EHPVO) and 30 for intrahepatic disease) in our centre.Results. Sclerotherapy resulted in variceal eradication in only 11.8% of the children (mean follow-up duration: 38.4 months). Variceal eradication with sclerotherapy alone was achieved in 20.7% and 3.3% of EHPVO and intrahepatic disease patients, respectively. Injection tract embolisation was successful in reducing the number of complications and re-bleeding rates. Complications that arose included: transient pyrexia (16.7%); deep oesophageal ulcers (6.7%); stricture formation (3.3%); and re-bleeding before variceal sclerosis (23%).Conclusion. Injection sclerotherapy did not eradicate oesophageal varices in most children. Injection tract embolisation by sclerosant was associated with fewer complications and reduced re-bleeding rates

Optimal scan strategies for future CMB satellite experiments

The B-mode polarisation power spectrum in the Cosmic Microwave Background (CMB) is about four orders of magnitude fainter than the CMB temperature power spectrum. Any instrumental imperfections that couple temperature fluctuations to B-mode polarisation must therefore be carefully controlled and/or removed. We investigate the role that a scan strategy can have in mitigating certain common systematics by averaging systematic errors down with many crossing angles. We present approximate analytic forms for the error on the recovered B-mode power spectrum that would result from differential gain, differential pointing and differential ellipticity for the case where two detector pairs are used in a polarisation experiment. We use these analytic predictions to search the parameter space of common satellite scan strategies in order to identify those features of a scan strategy that have most impact in mitigating systematic effects. As an example we go on to identify a scan strategy suitable for the CMB satellite proposed for the ESA M5 call. considering the practical considerations of fuel requirement, data rate and the relative orientation of the telescope to the earth. Having chosen a scan strategy we then go on to investigate the suitability of the scan strategy