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Degradation Leads (degradation + lead)

Distribution by Scientific Domains

Medical Sciences	60%

Selected Abstracts

Relationship between antithrombotic activities of fucans and their structure

DRUG DEVELOPMENT RESEARCH, Issue 4 2000
Catherine Boisson-Vidal
Abstract A low molecular weight fucan fraction extracted from the brown seaweed Ascophyllum nodosum was previously shown to exhibit dose-related venous antithrombotic activity with an ED80 of about 20 mg/kg, 2 h after a single subcutaneous injection HCII (Colliec et al. [1991] Thromb Res 64:143,154; Mauray et al. [1995] Thromb Haemast 74:1280,1285). Its activity was comparable to that of a low molecular weight heparin (Dalteparin®). This fucan fraction is one of several, with a range of different structure parameters, prepared by degradation of the whole native fucan. These low molecular weight fractions were compared using a Wessler stasis thrombosis model in rabbits and by determination of their in vitro and ex vivo anticoagulant activities. Intravenous administrations of these fractions reduced thrombosis in a dose-dependent manner. Partial removal of sulfate groups and/or partial degradation lead to a significant decrease in their anticoagulant and antithrombotic activities. The integrity of the regular pattern of sulphation of the fucoidan is necessary for antithrombotic activity. Drug Dev. Res. 51:216,224, 2000. © 2001 Wiley-Liss, Inc. [source]

Glycosphingolipid lysosomal storage diseases: therapy and pathogenesis

NEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 5 2002
M. Jeyakumar
Paediatric neurodegenerative diseases are frequently caused by inborn errors in glycosphingolipid (GSL) catabolism and are collectively termed the glycosphingolipidoses. GSL catabolism occurs in the lysosome and a defect in an enzyme involved in GSL degradation leads to the lysosomal storage of its substrate(s). GSLs are abundantly expressed in the central nervous system (CNS) and the disorders frequently have a progressive neurodegenerative course. Our understanding of pathogenesis in these diseases is incomplete and currently few options exist for therapy. In this review we discuss how mouse models of these disorders are providing insights into pathogenesis and also leading to progress in evaluating experimental therapies. [source]

Effects of permafrost degradation on woody vegetation at arctic treeline on the Seward Peninsula, Alaska

PERMAFROST AND PERIGLACIAL PROCESSES, Issue 2 2003
Andrea H. Lloyd
Abstract Permafrost degradation leads to substantial changes in soil thermal and hydrologic characteristics. We investigated the effects of changes in active layer thickness and soil drainage on vegetation distribution near the arctic treeline on the Seward Peninsula, Alaska. We measured active layer thickness, soil moisture, density of tall shrub species, cover of low shrub species, and reconstructed white spruce establishment history along transects across the banks of a network of thaw ponds. We found that active layer thickness did not vary along our transects, but soils on thaw pond banks were significantly drier than those on level tundra or in thaw-pond channels. Thaw-pond banks were the only sites in which trees successfully established, and shrub communities on thaw-pond banks were taller and more dominated by tall shrub species like willow and shrub birch. The data suggest that the establishment of tree and tall shrub species at the arctic treeline can be limited by the availability of well-drained microsites, and the response of these species to regional climatic changes will be constrained by the availability of such microsites and thus contingent upon further degradation of the permafrost. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Habitat selection and sampling design for ecological assessment of heterogeneous ponds using macroinvertebrates

AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 7 2009
Cristina Trigal-Domínguez
Abstract 1.Habitat heterogeneity has many implications in ecological assessment studies. On one hand it provides varying niches for organisms, increasing diversity. On the other hand, the inherent spatial variability of structurally complex systems may overlap with ecological condition making it difficult to disentangle the effects of perturbation. This study investigated the combined and single effects of habitat and pond condition on the macroinvertebrate assemblages of 35 ponds located in north-west Spain and spanning a range of water quality and habitat characteristics. 2.Macroinvertebrate communities and several environmental variables were sampled in the summer of 2004 or 2003. Samples were collected from four dominant habitats (vegetated shores, shores without vegetation, submerged vegetation, bare sediments) following a time-limited sampling. Non-metric multidimensional scaling and two-way crossed ANOSIM were used to investigate the taxonomic and functional differences in macroinvertebrate assemblage structure among habitats (four types) and pond conditions (optimal, good, moderate, poor, very poor). To investigate the individual and combined effects of pond condition and habitat on several diversity measures GLM models were used. In addition, the accuracy of two sampling designs , stratified and multihabitat , was compared using the CVs of seven macroinvertebrate attributes. 3.Results showed that macroinvertebrate communities differed significantly, albeit weakly, among habitat types and pond condition categories. In particular, the abundance of several Chironomidae genera, rarefied richness and Shannon index decreased both in perturbed systems and bare sediments, whereas no marked differences occurred between shores and submerged vegetation. 4.We suggest that a multihabitat approach together with the use of community attributes not (or slightly) affected by habitat type will provide more comparable results across ponds than a stratified approach or observation of the whole community, especially in ponds where degradation leads to habitat loss.Copyright © 2009 John Wiley & Sons, Ltd. [source]

Novel role for ,-adrenergic signalling in skeletal muscle growth, development and regeneration

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 3 2010
James G Ryall
Summary 1. In adult mammals, skeletal muscle mass is maintained through a precise balance of protein synthesis and protein degradation, whereas during development cellular (not protein) turnover predominates. When protein balance is shifted towards synthesis, skeletal muscle hypertrophy ensues. In contrast, increased protein degradation leads to skeletal muscle atrophy. Insulin-like growth factor (IGF)-I is among the best documented of the growth factors and regulates skeletal muscle mass by increasing protein synthesis and decreasing protein degradation. However, an IGF-I-independent growth pathway has been identified that involves the activation of ,-adrenoceptors and subsequent skeletal muscle growth, development and hypertrophy. 2. Although the importance of ,-adrenergic signalling in the heart has been well documented and continues to receive significant attention, it is only more recently that we have started to appreciate the importance of this signalling pathway in skeletal muscle structure and function. Studies have identified an important role for ,-adrenoceptors in myogenesis and work from our laboratory has identified a novel role for ,-adrenoceptors in regulating skeletal muscle regeneration after myotoxic injury. In addition, new data suggest that ,-adrenoceptors are markedly upregulated during differentiation of C2C12 cells. 3. It is now clear that ,-adrenoceptors play an important role in regulating skeletal muscle structure and function. Importantly, a clearer understanding of the pathways regulating skeletal muscle mass may lead to the identification of novel therapeutic targets for the treatment of muscle wasting disorders, including sarcopenia, cancer cachexia and the muscular dystrophies. [source]