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1.
When monocytes isolated from human blood adhere to glass substratum, actin- and vinculin-containing punctate plaques rapidly appear at the ventral surface of the cells. We show here that highly purified human leukocyte interferon (IFN) can inhibit formation of these adhesion plaques in a dose-dependent manner. Complete inhibition was obtained when 300 IU/ml IFN were added into the cell-seeding medium. Plaques already formed in the absence of IFN were only partially affected by subsequent addition of IFN into the culture medium. Prevention by IFN of the formation of the adhesion plaques was associated with loosened attachment of the cells to the substratum. Effect of IFN on cellular morphology was complex. At higher doses, IFN added to the cultures within 24 h of seeding almost completely inhibited the differentiation of monocytes to macrophages and most of the cells remained rounded. At lower doses, however, an enhancement of the bipolar spreading was seen and the end result was a culture with predominantly elongated fibroblastoid cells. The latter cells, unlike the fibroblastoid cells in untreated monocyte-macrophage cultures, were completely devoid of the actin plaques, while the reorganization of vimentin-type intermediate filaments took place in a normal manner. These results further support the view that the actin- and vinculin-containing plaques have a role in mediating firm adherence of human monocytes to growth substratum. 相似文献
2.
Ismo Virtanen Jouni Lohi Taneli Tani Hannu Sariola Robert E. Burgeson Veli-Pekka Lehto 《The Histochemical journal》1996,28(9):643-650
Summary In recent studies, the α2 chain of laminin (Ln) has been suggested to be the only laminin α chain expressed in mouse and human
thymus. We have now used chain-specific monoclonal antibodies and indirect immunofluorescence microscopy to study the expression
of laminin chains in samples of foetal and 6-year-old human thymus. The subepithelial basement membrane of the capsule of
foetal 16- to 18-week thymus presented a bright immunoreactivity for Ln α1, α3, β1, β3 and γ1 chains but not for α2 chain,
suggesting the expression of laminins-1 and-5. Most cortical and medullary epithelial cells, including Hassall's corpuscles,
however, lacked laminin immunoreactivity. Immunoreactivity for Ln β2 chain was only seen in basal laminae of larger blood
vessels. In thymic specimens from 6-year-old children, immunoreactivity for the laminin α1, α3, β1, β3 and γ1 chains was invariably
found in subepithelial basement membrane of the capsule and that for laminin α2 chain was now also distinct but more heterogeneous.
Furthermore, the thymic subepithelial basement membrane of the capsule at all stages showed immunore-activity for collagen
type VII, forming the anchoring fibres in epithelial basement membranes. The subcapsular thymic epithelium also showed immunoreactivity
for the BP 230 antigen and β4 integrin subunit, both components of hemidesmosomes. The present results show that the thymic subepithelial basement membrane
of the capsule presents properties which are commonly seen in stratified and combined epithelia, and are compatible with suggestions
of the antigenic similarity of thymic epithelial cells and keratinocytes. 相似文献
3.
Three-dimensional structure of endo-1,4-beta-xylanase II from Trichoderma reesei: two conformational states in the active site. 总被引:6,自引:0,他引:6
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The three-dimensional structure of endo-1,4-beta-xylanase II (XYNII) from Trichoderma reesei has been determined by X-ray diffraction techniques and refined to a conventional R-factor of 18.3% at 1.8 A resolution. The 190 amino acid length protein was found to exist as a single domain where the main chain folds to form two mostly antiparallel beta-sheets, which are packed against each other in parallel. The beta-sheet structure is twisted, forming a large cleft on one side of the molecule. The structure of XYNII resembles that of Bacillus 1,3-1,4-beta-glucanase. The cleft is an obvious suggestion for an active site, which has putative binding sites for at least four xylose residues. The catalytic residues are apparently the two glutamic acid residues (Glu86 and Glu177) in the middle of the cleft. One structure was determined at pH 5.0, corresponding to the pH optimum of XYNII. The second structure was determined at pH 6.5, where enzyme activity is reduced considerably. A clear structural change was observed, especially in the position of the side chain of Glu177. The observed conformational change is probably important for the mechanism of catalysis in XYNII. 相似文献
4.
Lina Assad Melvin M. Schwartz Ismo Virtanen Victor E. Gould 《Virchows Archiv. B, Cell pathology including molecular pathology》1993,63(1):307-316
Frozen samples of minimal change glomerulopathy (MCG), and of membranous, segmental and diffuse lupus glomerulonephritis (MGN,
SGN, DLGN) were studied to assess the distribution of tenascin (Ten), and the extradomains A and B (EDA-and EDB-) and oncofetal
(Onc-) isoforms of cellular fibronectin (cFn). Cryosections were immunostained by the ABC method with specific monoclonal
antibodies. In MCG, mesangial Ten and EDA-cFn reactions were increased. In MGN, mesangial Ten and EDA-cFn staining was enhanced
except in segmental scars; convincing reactions were seen in cases with membranous transformation; spikes stained strongly.
In SGN, variably intense staining for Ten and all cFn isoforms was seen in glomerular necrosis, proliferation and crescents;
parietal epithelium EDA-cFn staining was noted. In DLGN, strong and extensive mesangial Ten and EDA-cFn staining was seen
as were focal EDB-and Onc-cFn reactions. Parietal cells with and without crescents stained variably with all Mabs. Obsolete
glomeruli were unreactive save for rare periglomerular Ten rims. Interstitial inflammation and fibrosis in MGN, SGN and DLGN
had moderate to strong Ten and EDA-cFn staining with rare traces of EDB-and Onc-cFn. We conclude that enhanced Ten and EDA-cFn
is a potentially reversible response to glomerular injury whereas the expression of EDB-and Onc-cFn apparently result from
necrosis and/or cellular proliferation which lead to scarring. And, while mesangial cells are the major source of these molecules,
epithelial cells might also partake in their synthesis. 相似文献
5.
Carola Tilgmann Ismo Ulmanen 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1996,684(1-2)
The protein purification strategies used for obtaining homogeneous rat and human soluble catechol-O-methyltransferase (S-COTM) polypeptides are reviewed. Expression and purification of recombinant rat and human S-COMT in Escherichia coli and for human S-COMT in baculovirus-infected insect cells made it possible to elucidate the S-COMT polypeptides in more detail. The application of these purification methods has allowed the crystallization of the rat S-COMT protein and the analysis of the kinetic properties of the enzyme in great detail. The availability of the pure S-COMT protein together with the structural data has also greatly enhanced the development of more potent COMT inhibitors. 相似文献
6.
Interactions between cells and basement membrane components are crucial for the regulation of epithelial cell differentiation and polarization. We have studied by immunohistochemical methods the distribution of integrin adhesion proteins and some of their basement membrane ligands in foetal (16--19 weeks) and adult thyroid follicular epithelia. A diffuse immunoreactivity for only 3, v and 1 integrins was found in foetal follicular epithelium, whereas in adult follicular epithelium these integrins were expressed basally in a polarized manner. Additionally, 3 integrin was seen in a more basolaterally confined manner in adult follicular epithelium. Among basement membrane components, laminin 1, 1, 1 and 2 chains were found in epithelial basement membranes of the foetal thyroid gland, suggestive of the presence of laminins-1 and -3. In contrast, the basement membranes of adult follicular epithelium presented a much weaker immunoreactivity for the laminin 2 chain. Furthermore, immunoreactivity for the laminin 2 chain was occasionally seen in adult thyroid glands, apparently confined to myofibroblasts. Immunoreactivity for type IV collagen 1 and 2 (IV) chains was found in follicular basement membranes of foetal as well as adult thyroid gland. The results suggest that during maturation of foetal thyroid follicular epithelium a distinct polarization of integrins takes place. In mature thyroid follicular epithelium, the presumable adhesion-mediating integrin complexes are 31, v1 and/or v3 mediating adhesion to laminin-1 (1-1- 1) and type IV collagen trimer 12 (IV) 相似文献
7.
8.
Kaarina Matilainen Esa A. M?ntysaari Martin H. Lidauer Ismo Strandén Robin Thompson 《PloS one》2013,8(12)
Estimation of variance components by Monte Carlo (MC) expectation maximization (EM) restricted maximum likelihood (REML) is computationally efficient for large data sets and complex linear mixed effects models. However, efficiency may be lost due to the need for a large number of iterations of the EM algorithm. To decrease the computing time we explored the use of faster converging Newton-type algorithms within MC REML implementations. The implemented algorithms were: MC Newton-Raphson (NR), where the information matrix was generated via sampling; MC average information(AI), where the information was computed as an average of observed and expected information; and MC Broyden''s method, where the zero of the gradient was searched using a quasi-Newton-type algorithm. Performance of these algorithms was evaluated using simulated data. The final estimates were in good agreement with corresponding analytical ones. MC NR REML and MC AI REML enhanced convergence compared to MC EM REML and gave standard errors for the estimates as a by-product. MC NR REML required a larger number of MC samples, while each MC AI REML iteration demanded extra solving of mixed model equations by the number of parameters to be estimated. MC Broyden''s method required the largest number of MC samples with our small data and did not give standard errors for the parameters directly. We studied the performance of three different convergence criteria for the MC AI REML algorithm. Our results indicate the importance of defining a suitable convergence criterion and critical value in order to obtain an efficient Newton-type method utilizing a MC algorithm. Overall, use of a MC algorithm with Newton-type methods proved feasible and the results encourage testing of these methods with different kinds of large-scale problem settings. 相似文献
9.
Frank Borg Maria Finell Ismo Hakala Mika Herrala 《Journal of electromyography and kinesiology》2007,17(5):622-634
In an experiment, we combined force plate measurements and surface EMG in studying quiet and perturbed standing, involving MS (Multiple sclerosis) and controls. The aim of this paper is to report the results thus obtained on the relation between filtered gastrocnemius (GA) EMG and the anterior-posterior center-of-pressure (A/P COP) coordinate. The main finding is the good correspondence between A/P COP and the filtered GA EMG in the low frequency range. The EMG envelope was calculated using a zero-lag filter. Combining this with time shifts around 250-350 ms produced a high correlation (85.5+/-8.4%) between the GA-EMG envelope and the A/P COP. This EMG-COP relation was closest when using a low cut-off frequency value around 1 Hz in calculating the EMG envelope. Based on this filtering procedure we estimated the average EMG-COP time shift to be 283+/-43 ms between the GA-EMG envelope and A/P COP (which "lags" behind EMG envelope). This shift is consistent with the 1 Hz cut-off and phase shift produced by a corresponding critically damped second-order filter, and is about twice the corresponding twitch time. These results suggest that GA is to a large extent responsible for the phasic control of the anterior-posterior balance during quiet standing. A small difference (p<0.03) was found between mean time shift thus obtained for controls (n=4) and MS (n=6) while sway area showed a major difference (p<0.01). The paper also compares three alternative filters for numerical calculation of the EMG-envelope. 相似文献
10.