| 1. |
- Buttle, David J, et al.
(författare)
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Human sputum cathepsin B degrades proteoglycan, is inhibited by a2-macroglobulin and modulated by neutrophil elastase cleavage of cathepsin B precursor and cystatin C
- 1991
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Ingår i: Biochemical Journal. - 0264-6021. ; 276, s. 325-331
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Tidskriftsartikel (refereegranskat)abstract
- The high-Mr alkali-stable form of cathepsin B was purified from purulent human sputum. It was shown to solubilize proteoglycan monomer entrapped in polyacrylamide at a rate comparable with that of human lysosomal cathepsin B. Like the enzyme from lysosomes, sputum cathepsin B was bound by human alpha 2-macroglobulin, which inhibited its action on proteoglycan. Cystatin C in purulent sputum was shown to be the N-terminally truncated form generated by neutrophil elastase cleavage, and sputum cathepsin B was only weakly inhibited by recombinant cystatin C that had been cleaved by neutrophil elastase in vitro. Addition of neutrophil elastase to mucoid sputum led to a 5-fold increase in cathepsin B activity concomitant with a lowering in Mr of the cysteine proteinase from 40,000 to 37,000, i.e. the size of the active enzyme purified from purulent sputum. It is concluded that the high-Mr form of cathepsin B present in purulent sputum is a functional proteinase, unlike similar forms of the enzyme secreted by mammary gland in organ culture. The activity of cathepsin B in sputum is modulated by neutrophil elastase, by a combination of inhibitor inactivation and zymogen activation.
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| 2. |
- Michiels, J. J. M., et al.
(författare)
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Dielectric response in insulators: A wave-vector- and frequency-dependent model
- 1994
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Ingår i: Physical Review B. - 1550-235X. ; 50, s. 11386-11386
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Tidskriftsartikel (refereegranskat)abstract
- We have calculated a random-phase-approximation-type expression for the dielectric response function of several large-band-gap insulators using a development of the model suggested by Fry. This model should be good for systems with well-localized valence-electron functions and flat valence-electron bands. We show that in this model it is a minor approximation to use spherically symmetric bands in the integration over reciprocal space. This allows simple and fast evaluations of our expressions, thus avoiding Brillouin-zone integrations and summations over band indices. The results of our calculations are compared with ab initio data on static dielectric matrices from Baldereschi, with model calculations on the static dielectric function from Rezvani and Friauf and with electron-energy-loss spectra for LiF from Fields et al., using only one fit parameter. In addition, the Johnson f-sum rule is tested for this model. We also verify that our approximation gives the correct singular behavior of the (0,K) matrix elements.
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| 3. |
- Abeysekera, John D.A., et al.
(författare)
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Ergonomics in developing countries
- 1990
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Ingår i: Advances in industrial ergonomics and safety 2. - : Taylor and Francis Group. - 0850667488 ; , s. 771-778
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Konferensbidrag (refereegranskat)
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| 4. |
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| 5. |
- Chapman Jr., Harold A., et al.
(författare)
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Identification of cystatin C, a cysteine proteinase inhibitor, as a major secretory product of human alveolar macrophages in vitro
- 1990
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Ingår i: The American Review of Respiratory Disease. - : American Thoracic Society. - 0003-0805. ; 141:3, s. 698-705
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Tidskriftsartikel (refereegranskat)abstract
- The major inhibitor of the cysteine class of proteinases found in human body fluids, such as spinal fluid, milk, and seminal plasma, is cystatin C. In this study we show that human bronchoalveolar fluid also contains cystatin C and examine cystatin C expression by alveolar macrophages in vitro. Immunoprecipitation of extracts of metabolically labeled cells and immunoblotting of cellular extracts and culture media show that cystatin C is synthesized as a 14 (+/- 0.5) kilodalton (kD) protein and that greater than 90% of the protein is released as the 14 kD product into the culture supernatant (26.5 +/- 6.8 ng per 10(6) cells per 24 h). Cystatin C is not one of the most abundant proteins secreted during the first 24 h in vitro, representing approximately 10 to 12% of the total protein released by normal nonsmoker macrophages. Alveolar macrophages obtained from cigarette smokers or nonsmoker macrophages exposed to zymosan in vitro released 10 to 55% less cystatin C than nonsmoker macrophages. We also assayed culture supernatants from macrophages of smokers and nonsmokers for functional cystatin C. Supernatants of nonsmoker macrophages inhibited cathepsin B-like amidolytic activity in a fluorometric assay at pH 5.5. The inhibition was blocked by adsorption with Sepharose-coupled cystatin C antibodies and the inhibitor subsequently recovered from the Sepharose beads. In contrast, supernatants from smoker macrophages had obvious cathepsin B-like activity.(ABSTRACT TRUNCATED AT 250 WORDS)
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| 6. |
- Diederichs, J., et al.
(författare)
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Critical currents in Tl-2122 and Y-124 sinters under high hydrostatic pressure
- 1991
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Ingår i: Superconductor Science and Technology, volume 4, Special Issue 1S. - Bristol : Adam Hilger. - 0750301082 ; , s. S97-S99
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Konferensbidrag (refereegranskat)abstract
- Utilizing AC susceptibility measurements the authors have investigated the inter and intragranular properties of selected bulk materials under hydrostatic pressures to 3.5 GPa. A single phase Tl2CaBa2Cu2O8 sample with superconducting transition temperature Tc approximately=107 K shows a clear maximum in Tc(P) at approximately 2.2 GPa coupled with a nearly twofold increase to 3 GPa of the intergranular critical current density JcJ near Tc. The second sample, a YBa2Cu4O8 sinter, shows a large linear increase in Tc with pressure (+5.5 K/GPa) as well as a fivefold increase JcJ to 3 GPa. Applying a critical state model, the authors find that Tc(P) varies as lambda g-2(P), where lambda g is the intragranular (London) penetration depth.
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| 7. |
- Dou, S.X., et al.
(författare)
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Improvement of critical current density in the Bi-Pb-Sr-Ca-Cu-O system through hot isostatic pressing
- 1990
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Ingår i: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 167:5-6, s. 525-528
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Tidskriftsartikel (refereegranskat)abstract
- The effects of hot isostatic pressing (HIPing) on densification and the superconducting properties of the Bi-Pb-Sr-Ca-O system were investigated. A relative density up to 95% and a critical current density greater than 1100 A/cm2 at 77 K were achieved through HIPing at 650°C for 2 h under 200 MPa argon. Under these conditions, the product gave a value of Jc four times that without HIPing. To was unaffected by HIPing for samples encapsulated with a combination of glass and silver tubes. However, To was suppressed from 103 K to 86 K for samples encapsulated with stainless steel and silver tubes while Jc increased from 260 A/ cm2 to 1086 A/cm2 during HIPing, indicating that the weak links were significantly improved. A new minor phase, having a composition of Bi/Pb/Sr/Ca/Cu=0.58/2.8/3.0/2.1/1.1, was observed in HIPed samples but its effect on Jc is not clear
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| 8. |
- Ioannidis, John, et al.
(författare)
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IP-based protocols for mobile internetworking
- 1991
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Ingår i: SIGCOMM '91 Proceedings of the conference on Communications architecture & protocols. - New York, NY, USA : Association for Computing Machinery (ACM). ; , s. 235-245
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Konferensbidrag (refereegranskat)
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| 9. |
- Ioannidis, John, et al.
(författare)
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IP-based Protocols for Mobile Internetworking
- 1991
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We consider the problem of providing network access to hosts whose physical location changes with time. Such hosts cannot depend on traditional forms of network connectivity and routing because their location, and hence the route to reach them, cannot be deduced from their IP address. We present protocols that seamlessly integrate mobile hosts into the current IP networking infrastructure. They are primarily targeted at supporting a campus environment with mobile computers, but also extend gracefully to accomodate hosts moving between different networks. The key feature is the dependence on ancillary machines to track the location of the mobile hosts. Our protocols are designed to react quickly to changing topologies, to scale well, and not to place an overwhelming burden on the network.
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| 10. |
- Ion, John, et al.
(författare)
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Laser transformation hardening of low alloy hypoeutectoid steel
- 1992
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Ingår i: Materials Science and Technology. - : Informa UK Limited. - 0267-0836 .- 1743-2847. ; 8:9, s. 799-804
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Tidskriftsartikel (refereegranskat)abstract
- The principles of laser transformation hardening were investigated using a low alloy special steel having a microstructure of pearlite and proeutectoid ferrite. Temperature fields and phase transformations were modelled. Particular attention was paid to increases of the Ac1 and Ac3 transformation temperatures owing to the rapid thermal cycles produced by laser heating. Dissolution of proeutectoid ferrite is shown to control the formation of a homogeneous hardened case. Experimental data are in good agreement with the predictions of the model. A diagram was constructed which describes the case geometry and microstructure in terms of the process variables and is an aid to optimising practical processing parameters. The models are flexible and may be used for laser transformation hardening of other ferrous alloys having inhomogeneous microstructures.
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