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1.
Summary The influence of antibody absorption procedures and proteolytic pre-treatment of formaldehyde-fixed placental tissue on the localization of pregnancy-associated plasma protein A by immunoperoxidase technique was examined.Apparently monospecific IgG fraction of the anti-plasma protein applied directly on fixed tissue resulted in staining of connective tissue and a thin apical rim of the syncytiotrophoblast. Further absorption of the antibody with foetal connective tissue abolished this staining reaction. Pre-treatment of the fixed placental tissue with trypsin prior to application of the antibody, which had been absorbed with connective tissue, resulted in staining within the cytoplasm of the syncytiotrophoblast exclusively. Identical staining was seen when this IgG preparation was used directly on frozen placental tissue.The results point to the importance of the specificity of the antibody preparations and of proteolytic unmasking of epitopes when fixed tissues are used for localization studies of pregnancy-associated plasma protein A by immunoperoxidase technique. 相似文献
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Lasse Ryhänen Elaine M.L. Tan Sirpa Rantala-Ryhänen Jouni Uitto 《Archives of biochemistry and biophysics》1982,215(1):230-236
Chick embryo sterna, which actively synthesize type II procollagen, were pulse-labeled with radioactive proline; protein synthesis was then inhibited by unlabeled proline and cycloheximide. After the inhibition of protein synthesis, several amino acids, polyamines, or structurally related compounds were added to the incubation medium. The conversion of procollagen, first to two intermediates, pC-collagen and pN-collagen, and then to collagen, was monitored by sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis. The addition of 50 mm β-alanine, arginine, asparagine, glutamine, hydroxylysine, lysine, or ornithine, as well as agmatine, ?-aminocaproic acid, S-2-aminoethylcysteine, cadaverine, canavanine, putrescine, or spermine clearly inhibited the removal of the carboxy-terminal extension and pC-collagen accumulated; the removal of the amino-terminal extension was not affected. The inhibition of the conversion was reversible and unaffected by fetal calf serum. The results suggest that the conversion of type II procollagen to collagen requires at least two separate proteinases for the removal of amino-terminal and carboxy-terminal extensions. The results further suggest that naturally occurring molecules may be used to modulate the rate of conversion of procollagen to collagen, and development of analogs of these compounds may provide the means to interfere with excessive deposition of collagen in diseases with tissue fibrosis. 相似文献
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Olivia Sveidahl Johansen Tao Ma Jakob Bondo Hansen Lasse Kruse Markussen Renate Schreiber Laia Reverte-Salisa Hua Dong Dan Ploug Christensen Wenfei Sun Thorsten Gnad Iuliia Karavaeva Thomas Svava Nielsen Sander Kooijman Cheryl Cero Oksana Dmytriyeva Yachen Shen Maria Razzoli Shannon L. O’Brien Zachary Gerhart-Hines 《Cell》2021,184(13):3502-3518.e33
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Lasse Ruokolainen 《PloS one》2013,8(8)
Natural populations experience environmental conditions that vary across space and over time. This variation is often correlated between localities depending on the geographical separation between them, and different species can respond to local environmental fluctuations similarly or differently, depending on their adaptation. How this emerging structure in environmental correlation (between-patches and between-species) affects spatial community dynamics is an open question. This paper aims at a general understanding of the interactions between the environmental correlation structure and population dynamics in spatial networks of local communities (metacommunities), by studying simple two-patch, two-species systems. Three different pairs of interspecific interactions are considered: competition, consumer–resource interaction, and host–parasitoid interaction. While the results paint a relatively complex picture of the effect of environmental correlation, the interaction between environmental forcing, dispersal, and local interactions can be understood via two mechanisms. While increasing between-patch environmental correlation couples immigration and local densities (destabilising effect), the coupling between local populations under increased between-species environmental correlation can either amplify or dampen population fluctuations, depending on the patterns in density dependence. This work provides a unifying framework for modelling stochastic metacommunities, and forms a foundation for a better understanding of population responses to environmental fluctuations in natural systems. 相似文献
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Margit S. Müller Linea F. Obel Helle S. Waagepetersen Arne Schousboe Lasse K. Bak 《Neurochemical research》2013,38(6):1260-1265
The polyether antibiotic ionomycin is a common research tool employed to raise cytosolic Ca2+ in almost any cell type. Although initially thought to directly cause physicochemical translocation of extracellular Ca2+ into the cytosol, a number of studies have demonstrated that the mechanism of action is likely to be more complex, involving modulation of intrinsic Ca2+ signaling pathways. In the present study we assessed the effect of ionomycin on primary cultures of murine cerebellar astrocytes. Ionomycin concentrations ranging from 0.1 to 10 μM triggered a biphasic increase in cytosolic Ca2+, consisting of an initial peak and a subsequent sustained plateau. The response was dependent on concentration and exposure time. While the plateau phase was abolished in the absence of extracellular Ca2+, the peak phase persisted. The peak amplitude could be lowered significantly by application of dantrolene, demonstrating involvement of Ca2+-induced Ca2+-release (CICR). The plateau phase was markedly reduced when store-operated Ca2+-entry (SOCE) was blocked with 2-aminoethoxydiphenyl borate. Our results show that ionomycin directly affects internal Ca2+ stores in astrocytes, causing release of Ca2+ into the cytosol, which in turn triggers further depletion of the stores through CICR and subsequently activates SOCE. This mechanistic action of ionomycin is important to keep in mind when employing it as a pharmacological tool. 相似文献
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Lasse P. Räsänen Mika E. Mononen Eveliina Lammentausta Miika T. Nieminen Jukka S. Jurvelin Rami K. Korhonen 《Computer methods in biomechanics and biomedical engineering》2016,19(11):1225-1240
Site-specific variation of collagen fibril orientations can affect cartilage stresses in knee joints. However, this has not been confirmed by 3-D analyses. Therefore, we present a novel method for evaluation of the effect of patient-specific collagen architecture on time-dependent mechanical responses of knee joint cartilage during gait. 3-D finite element (FE) models of a human knee joint were created with the collagen architectures obtained from T2 mapped MRI (patient-specific model) and from literature (literature model). The effect of accuracy of the implementation of collagen fibril architecture into the model was examined by using a submodel with denser FE mesh. Compared to the literature model, fibril strains and maximum principal stresses were reduced especially in the superficial/middle regions of medial tibial cartilage in the patient-specific model after the loading response of gait (up to ?413 and ?26%, respectively). Compared to the more coarsely meshed joint model, the patient-specific submodel demonstrated similar strain and stress distributions but increased values particularly in the superficial cartilage regions (especially stresses increased >60%). The results demonstrate that implementation of subject-specific collagen architecture of cartilage in 3-D modulates location- and time-dependent mechanical responses of human knee joint cartilage. Submodeling with more accurate implementation of collagen fibril architecture alters cartilage stresses particularly in the superficial/middle tissue. 相似文献