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Several Laboratories (several + laboratory)
Selected AbstractsA collaborative study to establish the 7th International Standard for Factor VIII ConcentrateJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 1 2005S. Raut Summary., A candidate concentrate, preparation N (99/678), was assayed and calibrated, as a potential replacement, against four established factor (F) VIII concentrate standards: the current WHO 6th International Standard (IS) (97/616), the previous 5th IS (88/640), the Mega 1 standard and Ph. Eur. BRP Batch 2 standard, in a collaborative study involving 38 laboratories. All laboratories were instructed to use the ISTH/SSC recommendations, including predilution of concentrates in FVIII-deficient plasma. Several laboratories performed more than one assay method and altogether there were 27 sets of assays with the one-stage method, 31 with the chromogenic method, and 18 with both methods. There was good agreement between laboratories using each of the two methods for comparison of preparation N against the four established standards, with overall potencies by one-stage and chromogenic methods differing only by less than 2%. However, there were significant differences in potencies relative to the different standards, ranging from 10.1 IU per ampoule against the Ph. Eur.BRP2 to 11.4 against the WHO 6th IS. Accelerated degradation studies showed that the proposed standard is very stable, with a predicted loss of activity per year of less than 0.001% at the recommended storage temperature of ,20 °C. Various options for potency of preparation N were considered by the participants and by members of the ISTH/SSC FVIII/FIX Subcommittee. In November 2003, preparation N (NIBSC 99/678) was proposed to and accepted by the Expert Committee on Biological Standardization of the World Health Organization to be the 7th International Standard for Factor VIII Concentrate with an assigned potency of 11.0 IU per ampoule. [source] Evidence for a vicious cycle of exercise and hypoglycemia in type 1 diabetes mellitusDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 2 2004A. C. Ertl Abstract Exercise is a cornerstone of diabetes management as it aids in glycemic control, weight management, reducing blood pressure, and improving the quality of life of patients. Unfortunately, owing to the complexity and difficulties of regulating exogenous insulin in a physiologic manner during exercise, physical activity often results in hypoglycemia in patients with type 1 diabetes mellitus (type 1 DM). When glucose levels fall below threshold glycemic levels, neuroendocrine, autonomic nervous system (ANS), and metabolic glucose counterregulatory mechanisms are activated. These hypoglycemic counterregulatory mechanisms in type 1 DM can be blunted irreversibly by disease duration or by acute episodes of prior stress. These reduced (or absent) counterregulatory responses result in a threefold increase in severe hypoglycemia when intensive glycemic control is implemented in type 1 DM 1. Much recent work has been focused on determining the in vivo mechanisms responsible for causing the increased incidence of severe hypoglycemia in type 1 DM. Studies from several laboratories have demonstrated the role played by episodes of antecedent hypoglycemia in producing blunted glucose counterregulatory responses during subsequent exposures of hypoglycemia. Until recently, the mechanisms responsible for exercise related hypoglycemia in type 1 DM have been attributed to relative or absolute increases of insulin levels or incomplete glycogen repletion after physical activity. Owing to the qualitative similarity of neuroendocrine, ANS, and metabolic responses to hypoglycemia and exercise, we have hypothesized that neuroendocrine and ANS counterregulatory dysfunction may also play an important role in the pathogenesis of exercise-related hypoglycemia in type 1 DM. Vicious cycles can be created in type 1 DM, where an episode of hypoglycemia or exercise can feed forward to downregulate neuroendocrine and ANS responses to a subsequent episode of either stress, thereby creating further hypoglycemia (Figure 1). This article will review the recent work that has studied the contribution of counterregulatory dysfunction to exercise-induced hypoglycemia in type 1 DM. Copyright © 2004 John Wiley & Sons, Ltd. 1. Reciprocal vicious cycles may be created in type 1 diabetes mellitus (type 1 DM), whereby an episode of hypoglycemia or exercise can feed forward to downregulate neuroendocrine and autonomic nervous system responses to a subsequent episode of either stress, thereby creating further hypoglycemia [source] Mutagenic repair of DNA interstrand crosslinksENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 6 2010Xi Shen Abstract Formation of DNA interstrand crosslinks (ICLs) in chromosomal DNA imposes acute obstruction of all essential DNA functions. For over 70 years bifunctional alkylators, also known as DNA crosslinkers, have been an important class of cancer chemotherapeutic regimens. The mechanisms of ICL repair remains largely elusive. Here, we review a eukaryotic mutagenic ICL repair pathway discovered by work from several laboratories. This repair pathway, alternatively termed recombination-independent ICL repair, involves the incision activities of the nucleotide excision repair (NER) mechanism and lesion bypass polymerase(s). Repair of the ICL is initiated by dual incisions flanking the ICL on one strand of the double helix; the resulting gap is filled in by lesion bypass polymerases. The remaining lesion is subsequently removed by a second round of NER reaction. The mutagenic repair of ICL likely interacts with other cellular mechanisms such as the Fanconi anemia pathway and recombinational repair of ICLs. These aspects will also be discussed. Environ. Mol. Mutagen., 2010. © 2010 Wiley-Liss, Inc. [source] Neurotransmitter and neuromodulatory mechanisms at peripheral arterial chemoreceptorsEXPERIMENTAL PHYSIOLOGY, Issue 6 2010Colin A. Nurse The control of breathing depends critically on sensory inputs to the central pattern generator of the brainstem, arising from peripheral arterial chemoreceptors located principally in the carotid bodies (CBs). The CB receptors, i.e. glomus or type I cells, are excited by chemical stimuli in arterial blood, particularly hypoxia, hypercapnia, acidosis and low glucose, which initiate corrective reflex cardiorespiratory and cardiovascular adjustments. Type I cells occur in clusters and are innervated by petrosal afferent fibres. Synaptic specializations (both chemical and electrical) occur between type I cells and petrosal terminals, and between neighbouring type I cells. This, together with the presence of a wide array of neurotransmitters and neuromodulators linked to both ionotropic and metabotropic receptors, allows for a complex modulation of CB sensory output. Studies in several laboratories over the last ,20 years have provided much insight into the transduction mechanisms. More recent studies, aided by the development of a co-culture model of the rat CB, have shed light on the role of neurotransmitters and neuromodulators in shaping the afferent response. This review highlights some of these developments, which have contributed to our current understanding of information processing at CB chemoreceptors. [source] Inhibition of tumour invasion and angiogenesis by epigallocatechin gallate (EGCG), a major component of green teaINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 6 2001Young D. Jung Epidemiological studies have suggested that consumption of green tea may decrease cancer risk. In addition, abundant pre-clinical data from several laboratories have provided convincing evidence that polyphenols present in green tea afford protection against cancer in both in vivo and in vitro studies. Recently, epigallocatechin gallate (EGCG), a putative chemopreventive agent and a major component of green tea, was reported to inhibit tumour invasion and angiogenesis, processes that are essential for tumour growth and metastasis. Understanding the basic principles by which EGCG inhibits tumour invasion and angiogenesis may lead to the development of new therapeutic strategies, in addition to supporting the role of green tea as a cancer chemopreventive agent. [source] FHA Domains as Phospho-Threonine Binding Modules in Cell SignalingIUBMB LIFE, Issue 1 2003Andrew Hammet Abstract Forkhead-associated (FHA) domains are present in <200 diverse proteins in all phyla from bacteria to mammals and seem to be particularly prevalent in proteins with cell cycle control functions. Recent work from several laboratories has considerably improved our understanding of the structure and function of these domains that were virtually unknown a few years ago, and the first disease associations of FHA domains have now emerged. FHA domains form 11-stranded beta-sandwiches that contain some 100-180 amino acid residues with a high degree of sequence diversity. FHA domains act as phosphorylation-dependent protein-protein interaction modules that preferentially bind to phospho-threonine residues in their targets. Interestingly, point mutations in the human CHK2 gene that lead to single-residue amino acid substitutions in the FHA domain of this cell cycle checkpoint kinase have been found to cause a subset of cases of the Li-Fraumeni multi-cancer syndrome. IUBMB Life, 55: 23-27, 2003 [source] Drug targeting by macromolecules without recognition unit?JOURNAL OF MOLECULAR RECOGNITION, Issue 5 2003Ferenc Hudecz Abstract his review will summarize available information on the ability of macromolecular conjugates containing no specific recognition motifs to deliver anthracyclines (daunomycin, adriamycin) or methotrexate to target cells such as tumour cells or macrophages. Conjugates with natural (proteins, DNA, carbohydrates) and synthetic macromolecules (linear and branched chain poly-,-amino acids, non-biodegradable DIVEMA, HPMA etc.) will be reviewed. Experimental data from several laboratories indicate that these conjugates are taken up by cells mainly by fluid-phase or adsorptive endocytosis. It is believed that these processes do not involve ,specific receptors'. Two examples of methotrexate and daunomycin conjugates will be discussed to show the effect of the chemical structure of branched chain polypeptides on the uptake and antitumour or antiparasitic (Leishmania donovani infection) efficacy of conjugates. Copyright © 2003 John Wiley & Sons, Ltd. [source] Advances in laser technology for isolated attosecond pulse generationLASER PHYSICS LETTERS, Issue 4 2009C. Vozzi Abstract In this review we report on recent advances in laser technology, which have contributed to the fast development of attosecond science. In particular we will concentrate on two experimental methods for the generation of high-peak-power, fewoptical-cycle laser pulses with controlled electric field, which are crucial for the generation of isolated attosecond pulses. The first method is the hollow-fiber compression technique, introduced in 1996 and now routinely used in several laboratories. So far, isolated attosecond pulses have been generated by using few-cycle pulses produced by such compression technique, in combination with active stabilization of the carrier-envelope phase. More recently, few-cycle pulses tunable in the infrared region have been generated by optical parametric amplification with passive stabilization of the carrier-envelope phase. Such parametric sources represent excellent drivers for the generation of harmonic radiation with an extended cutoff, and offer the possibility to extend attosecond science towards the soft-X rays region. Finally, we will briefly discuss the basic elements of attosecond metrology. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Single photon fluorescent microlithography for live-cell imagingMICROSCOPY RESEARCH AND TECHNIQUE, Issue 1 2010Darío Kunik Abstract Using fluorescent dyes to trigger the polymerization of a commercial polyurethane resin allows a rapid fabrication of micrometer and submicrometer sized fluorescent structures by one-photon absorption. Here, we show that standard He,Ne lasers emitting at 632.8 nm can be used to start the photopolymerization and that very low laser power is required. This procedure allows the fabrication of fiduciary fluorescent references on standard glass coverslips, mica sheets, or gold-coated coverslips for laser scanning or standard fluorescent microscopy. The biocompatibility of the polymerized resin with cells in culture was tested by growing Xenopus melanophores and a standard laser scanning microscope was used to demonstrate that it is possible to use equipment readily available in several laboratories. We show that fluorescent structure with less than 10 nm in height may be used as references in fluorescence microscopy allowing a smooth environment for cell growth. Different dyes were tested and the conditions for one-photon polymerization were outlined. Microsc. Res. Tech. 2009. © 2009 Wiley-Liss, Inc. [source] Opportunities afforded by the study of unmyelinated nerves in skin and other organsMUSCLE AND NERVE, Issue 6 2004William R. Kennedy MS Abstract Neurological practice is mainly focused on signs and symptoms of disorders that involve functions governed by myelinated nerves. Functions controlled by unmyelinated nerve fibers have necessarily remained in the background because of the inability to consistently stain, image, or construct clinically applicable neurophysiological tests of these nerves. The situation has changed with the introduction of immunohistochemical methods and confocal microscopy into clinical medicine, as these provide clear images of thin unmyelinated nerves in most organs. One obvious sign of change is the increasing number of reports from several laboratories of the pathological alterations of cutaneous nerves in skin biopsies from patients with a variety of clinical conditions. This study reviews recent methods to stain and image unmyelinated nerves as well as the use of these methods for diagnosing peripheral neuropathy, for experimental studies of denervation and reinnervation in human subjects, and for demonstrating the vast array of unmyelinated nerves in internal organs. The new ability to examine the great variety of nerves in different organs opens opportunities and creates challenges and responsibilities for neurologists and neuroscientists. Muscle Nerve 756,767, 2004 [source] ORIGINAL ARTICLE: Presence of Antisperm Antibodies Reactive with Peptide Epitopes of FA-1 and YLP12 in Sera of Immunoinfertile WomenAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 6 2008Jessica Williams Problem Recent studies in several laboratories are focused on delineating sperm antigens that are relevant to fertility and examining involvement of antibodies to these antigens in human immunoinfertility. Our laboratory has characterized two such antigens, namely fertilization antigen (FA-1) and YLP12 dodecamer sequence that are involved in sperm-oocyte binding. The present study was conducted to examine the occurrence of isoantibodies to various peptide epitopes of human and murine FA-1 antigen and YLP12 peptide in sera of immunoinfertile and fertile women. Method of study Sera from 67 immunoinfertile and 19 fertile women were collected. Various peptides based up on human and murine FA-1 antigen and YLP12 were synthesized, and examined for immunoreactivity with these sera by using ELISA. Four immunodominant sequences, two each from human (hFA-182-97aa and hFA-1200-219aa) and mouse (mFA-12-19aa and mFA-1117-136aa) FA-1 antigen, were selected for the present study. Another human FA-1 sequence, hFA-1220-240aa, that was not in the immunodominant region was used as a control. Results For human FA-1 peptides, 41.8% of the immunoinfertile sera reacted positively (,2 SD units) with hFA-182-97aa, 24.6% (16/65) with hFA-1200-219aa, and 3% (2/66) with hFA-1220-240aa peptide. For two murine FA-1 peptides, 41.7% (25/60) of the immunoinfertile sera reacted positively with mFA-12-19aa, and 41.5% (27/65) with mFA-1117-136aa peptide. For the YLP12 dodecamer peptide, 43.3% (29/67) of the immunoinfertile sera reacted positively. None of the sera from fertile women reacted positively with any of these peptides. Conclusion In conclusion, our data indicate that the immunoinfertile women have circulating isoantibodies against at least two immunodominant peptide epitopes of human and murine FA-1 antigen and YLP12 peptide sequence. These peptides may find clinical application in the specific diagnosis and treatment of female infertility and contraceptive vaccine development. [source] Localization and imaging of local shunts in solar cells using polymer-dispersed liquid crystalsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 4 2001Jan Schmidt An easy-to-use technique for the localization and imaging of local shunts in solar cells is introduced. The method is based on temperature-sensitive polymer-dispersed cholesteric liquid crystal foils, covering the reverse-biased solar cell. The unique optical properties of the cholesteric liquid crystal, known as selective reflection, render the local shunts of a solar cell visible as a color distribution in the foil, which is directly correlated with the spatial shunt distribution. The novel method is applied to several laboratory and commercial silicon solar cells and its high sensitivity is demonstrated. Copyright © 2001 John Wiley & Sons, Ltd. [source] | |||||||||||||