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121.
Appel H Kuon W Kuhne M Hülsmeyer M Kollnberger S Kuhlmann S Weiss E Zeitz M Wucherpfennig K Bowness P Sieper J 《Journal of immunology (Baltimore, Md. : 1950)》2004,173(11):6564-6573
Crystallographic studies have suggested that the cysteine at position 67 (Cys(67)) in the B pocket of the MHC molecule HLA-B*2705 is of importance for peptide binding, and biophysical studies have documented altered thermodynamic stability of the molecule when Cys(67) was mutated to serine (Ser(67)). In this study, we used HLA-B27.Cys(67) and HLA-B27.Ser(67) tetramers with defined T cell epitopes to determine the contribution of this polymorphic, solvent-inaccessible MHC residue to T cell recognition. We generated these HLA-B27 tetramers using immunodominant viral peptides with high binding affinity to HLA-B27 and cartilage-derived peptides with lower affinity. We demonstrate that the yield of refolding of HLA-B27.Ser(67) molecules was higher than for HLA-B27.Cys(67) molecules and strongly dependent on the affinity of the peptide. T cell recognition did not differ between HLA-B27.Cys(67) and HLA.B27.Ser(67) tetramers for the viral peptides that were investigated. However, an aggrecan peptide-specific T cell line derived from an HLA-B27 transgenic BALB/c mouse bound significantly stronger to the HLA-B27.Cys(67) tetramer than to the HLA-B27.Ser(67) tetramer. Modeling studies of the molecular structure suggest the loss of a SH ... pi hydrogen bond with the Cys-->Ser substitution in the HLA-B27 H chain which reduces the stability of the HLA-B27/peptide complex. These results demonstrate that a solvent-inaccessible residue in the B pocket of HLA-B27 can affect TCR binding in a peptide-dependent fashion. 相似文献
122.
Prototype foamy virus envelope glycoprotein leader peptide processing is mediated by a furin-like cellular protease, but cleavage is not essential for viral infectivity 下载免费PDF全文
Duda A Stange A Lüftenegger D Stanke N Westphal D Pietschmann T Eastman SW Linial ML Rethwilm A Lindemann D 《Journal of virology》2004,78(24):13865-13870
Analogous to cellular glycoproteins, viral envelope proteins contain N-terminal signal sequences responsible for targeting them to the secretory pathway. The prototype foamy virus (PFV) envelope (Env) shows a highly unusual biosynthesis. Its precursor protein has a type III membrane topology with both the N and C terminus located in the cytoplasm. Coexpression of FV glycoprotein and interaction of its leader peptide (LP) with the viral capsid is essential for viral particle budding and egress. Processing of PFV Env into the particle-associated LP, surface (SU), and transmembrane (TM) subunits occur posttranslationally during transport to the cell surface by yet-unidentified cellular proteases. Here we provide strong evidence that furin itself or a furin-like protease and not the signal peptidase complex is responsible for both processing events. N-terminal protein sequencing of the SU and TM subunits of purified PFV Env-immunoglobulin G immunoadhesin identified furin consensus sequences upstream of both cleavage sites. Mutagenesis analysis of two overlapping furin consensus sequences at the PFV LP/SU cleavage site in the wild-type protein confirmed the sequencing data and demonstrated utilization of only the first site. Fully processed SU was almost completely absent in viral particles of mutants having conserved arginine residues replaced by alanines in the first furin consensus sequence, but normal processing was observed upon mutation of the second motif. Although these mutants displayed a significant loss in infectivity as a result of reduced particle release, no correlation to processing inhibition was observed, since another mutant having normal LP/SU processing had a similar defect. 相似文献
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125.
Jürgen Rheinlaender Jun-Xian Shen Heiner Römer 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2006,192(4):389-397
Pair formation in the bushcricket Gampsocleis gratiosa is achieved through acoustic signalling by the male and phonotactic approaches of the female towards the calling song. On
a walking belt in the free sound field, females tracked the position of the speaker broadcasting the male calling song with
a remarkable precision, deviating by no more than 10 cm in either direction from the ideal course. Starting with stimulus
angles of 6–10° the females significantly turned to the correct side, and with stimulus angles greater than 25° no incorrect
turns were made. Using neurophysiological data on the directionality of the ear we calculated that with such stimulus angles
the available binaural intensity difference is in the order of 1–2 dB. We developed a dichotic ear stimulation device for
freely moving females with a cross-talk barrier of about 50 dB, which allowed to precisely apply small binaural intensity
differences. In such a dichotic stimulation paradigm, females on average turned to the tronger stimulated side starting with
a 1 dB difference between both ears. The significance of such a reliable lateralization behaviour with small interaural intensity
differences for phonotactic behaviour under natural conditions is discussed. 相似文献
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127.
Appel H Loddenkemper C Grozdanovic Z Ebhardt H Dreimann M Hempfing A Stein H Metz-Stavenhagen P Rudwaleit M Sieper J 《Arthritis research & therapy》2006,8(5):R143-7
Ankylosing spondylitis (AS) is a chronic inflammatory disease which affects primarily the sacroiliac joints and the spine.
In patients with active disease, magnetic resonance imaging (MRI) of the spine shows areas of bone marrow edema, the histopathological
equivalent of which is unknown. In this study we correlate inflammation in the spine of patients with AS as revealed by histological
examination with bone marrow edema as detected by MRI. We have compared the histopathological findings of zygapophyseal joints
from 8 patients with AS (age: 30 to 64, disease duration 7 to 33 years) undergoing spinal surgery with findings in MRI. For
histopathological analysis, we quantified infiltrates of CD3+, CD4+ and CD8+ T cells as well as CD20+ B cells immunohistochemically.
Bone marrow edema was evaluated in hematoxylin and eosin stained sections and quantified as the percentage of the bone marrow
area involved. All patients with AS showed interstitial mononuclear cell infiltrates and various degrees of bone marrow edema
(range from 10% to 60%) in histopathological analysis. However, in only three of eight patients histopathological inflammation
and edema in the zygapophyseal joints correlated with bone marrow edema in zygapophyseal joints of the lumbar spine as detected
by MRI. Interestingly, two of these patients showed the highest histological score for bone marrow edema (60%). This first
study correlating histopathological changes in the spine of patients with AS with findings in MRI scans suggests that a substantial
degree of bone marrow inflammation and edema is necessary to be detected by MRI. 相似文献
128.
Barth M Rickelt S Noffz E Winter-Simanowski S Niemann H Akhyari P Lichtenberg A Franke WW 《Cell and tissue research》2012,348(2):295-307
The interstitial cells of cardiac valves represent one of the most frequent cell types in the mammalian heart. In order to provide a cell and molecular biological basis for the growth of isolated valvular interstitial cells (VICs) in cell culture and for the use in re-implantation surgery we have examined VICs in situ and in culture, in fetal, postnatal and adult hearts, in re-associations with scaffolds of extracellular matrix (ECM) material and decellularized heart valves. In all four mammalian species examined (human, bovine, porcine and ovine), the typical mesenchymal-type cell-cell adherens junctions (AJs) connecting VICs appear as normal N-cadherin based puncta adhaerentia. Their molecular ensemble, however, changes under various growth conditions insofar as plakophilin-2 (Pkp2), known as a major cytoplasmic plaque component of epithelial desmosomes, is recruited to and integrated in the plaques of VIC-AJs as a major component under growth conditions characterized by enhanced proliferation, i.e., in fetal heart valves and in cell cultures. Upon re-seeding onto decellularized heart valves or in stages of growth in association with artificial scaffolds, Pkp2 is - for the most part - lost from the AJs. As Pkp2 has recently also been detected in AJs of cardiac myxomata and diverse other mesenchymal tumors, the demonstrated return to the normal Pkp2-negative state upon re-association with ECM scaffolds and decellularized heart valves may now provide a safe basis for the use of cultured VICs in valve replacement surgery. Even more surprising, this type of transient acquisition of Pkp2 has also been observed in distinct groups of endothelial cells of the endocardium, where it seems to correspond to the cell type ready for endothelial-mesenchymal transition (EMT). 相似文献
129.
Mapping a songbird fauna with pupils How to induce pupils aged 13 to 14 years to successfully map the songbird fauna of a city park? The mapping project took place within 1.5 hours on an April morning. Pupils were organized as small working groups using maps, binoculars, and field guides produced by themselves. The project had been prepared by a 6 lesson course. Results were later discussed with nature conservancy officials. Pupils having participated in the project displayed increased knowledge of birds and motivation to observe them. 相似文献
130.
V Gallo JP Mackenbach M Ezzati G Menvielle AE Kunst S Rohrmann R Kaaks B Teucher H Boeing MM Bergmann A Tjønneland SO Dalton K Overvad ML Redondo A Agudo A Daponte L Arriola C Navarro AB Gurrea KT Khaw N Wareham T Key A Naska A Trichopoulou D Trichopoulos G Masala S Panico P Contiero R Tumino HB Bueno-de-Mesquita PD Siersema PP Peeters S Zackrisson M Almquist S Eriksson G Hallmans G Skeie T Braaten E Lund AK Illner T Mouw E Riboli P Vineis 《PloS one》2012,7(7):e39013