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| 2. |
- Blanco, A, et al.
(författare)
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Progress in timing Resistive Plate Chambers
- 2004
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 535:1-2, s. 272-276
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Tidskriftsartikel (refereegranskat)abstract
- Timing RPCs are Resistive Plate Chambers made with glass and metal electrodes separated by precision spacers. Typical gas gaps are a few hundred micrometers wide. Such counters were introduced in 1999 and have since reached timing accuracies below 50 ps sigma with efficiencies above 99% for MIPs. Applications in high-energy physics have already taken place with several more under study. Some recent developments include the extension of the counting rate capability by over one order of magnitude, to 25 kHz/cm(2), with time resolutions below 100 ps sigma. A prototype RPC-based Positron Emission Tomograph yielded a reconstructed point-source resolution of 0.6 mm FWHM and a modified timing RPC design, featuring 50 mum pitch anode strips, allowed to reach extremely good position resolution for hard X-rays in digital readout mode. An analytically solvable model has allowed us to clarify the basic factors influencing the time resolution.
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| 4. |
- Strömblad, Staffan, et al.
(författare)
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Loss of p53 compensates for alpha(v)-integrin function in retinal neovascularization
- 2002
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 277:16, s. 13371-13374
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Tidskriftsartikel (refereegranskat)abstract
- alpha(v)-Integrin antagonists block neovascularization in various species, whereas 20% of alpha(v)-integrin null mice are born with many normal looking blood vessels. Given that blockade of alpha(v)-integrins during angiogenesis induces p53 activity, we utilized p53 null mice to elucidate whether loss of p53 can compensate for av-integrin function in neovascularization of the retina. Murine retinal vascularization was inhibited by systemic administration of an alpha(v)-integrin antagonist. In contrast, mice lacking p53 were refractory to this treatment, indicating that neovascularization in normal mice depends on alpha(v)-integrin-mediated suppression of p53. Blockade of alpha(v)-integrins during neovascularization resulted in an induction of p21(CIP1) in wild type and, surprisingly, in p53 null retinas, indicating that alpha(v)-integrin ligation regulates p21(CIP1) levels in a p53-independent manner. In conclusion, we demonstrate for the first time an in vivo intracellular mechanism for compensation of integrin function and that p53 and alpha(v)-integrins act in concert during retinal neovascularization.
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| 7. |
- Copello, J A, et al.
(författare)
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Differential activation by Ca2+, ATP and caffeine of cardiac and skeletal muscle ryanodine receptors after block by Mg2+.
- 2002
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Ingår i: Journal of Membrane Biology. - : Springer Science and Business Media LLC. - 0022-2631 .- 1432-1424. ; 187:1, s. 51-64
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Tidskriftsartikel (refereegranskat)abstract
- The block of rabbit skeletal ryanodine receptors (RyR1) and dog heart RyR2 by cytosolic [Mg2+], and its reversal by agonists Ca2+, ATP and caffeine was studied in planar bilayers. Mg2+ effects were tested at submaximal activating [Ca2+] (5 microM). Approximately one third of the RyR1s had low open probability ("LA channels") in the absence of Mg2+. All other RyR1s displayed higher activity ("HA channels"). Cytosolic Mg2+ (1 mM) blocked individual RyR1 channels to varying degrees (32 to 100%). LA channels had residual P(o) <0.005 in 1 mM Mg2+ and reactivated poorly with [Ca2+] (100 microM), caffeine (5 mM), or ATP (4 mM; all at constant 1 mM Mg2+). HA channels had variable activity in Mg2+ and variable degree of recovery from Mg2+ block with Ca2+, caffeine or ATP application. Nearly all cardiac RyR2s displayed high activity in 5 microM [Ca2+]. They also had variable sensitivity to Mg2+. However, the RyR2s consistently recovered from Mg2+ block with 100 microM [Ca2+] or caffeine application, but not when ATP was added. Thus, at physiological [Mg2+], RyR2s behaved as relatively homogeneous Ca2+/caffeine-gated HA channels. In contrast, RyR1s displayed functional heterogeneity that arises from differential modulatory actions of Ca2+ and ATP. These differences between RyR1 and RyR2 function may reflect their respective roles in muscle physiology and excitation-contraction coupling.
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| 8. |
- Ismail, AA, et al.
(författare)
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Incidence of limb fracture across Europe: Results from the European Prospective Osteoporosis Study (EPOS)
- 2002
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Ingår i: Osteoporosis International. - : Springer Science and Business Media LLC. - 1433-2965 .- 0937-941X. ; 13:7, s. 565-571
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this population-based prospective study was to determine the incidence of limb fracture by site and gender in different regions of Europe. Men and women aged 50-79 years were recruited from population registers in 31 European centers. Subjects were invited to attend for an interviewer-administered questionnaire and lateral spinal radiographs. Subjects were subsequently followed up using an annual postal questionnaire which included questions concerning the occurrence of new fractures. Self-reported fractures were confirmed where possible by radiograph, attending physician or subject interview. There were 6451 men and 6936 women followed for a median of 3.0 years. During this time there were 140 incident limb fractures in men and 391 in women. The age-adjusted incidence of any limb fracture was 7,3/1000 person-years [pyrs] in men and 19 per 1000 pyrs in women, equivalent to a 2,5 times excess in women. Among women, the incidence of hip, humerus and distal forearm fracture, though not 'other' limb fracture, increased with age, while in men only the incidence of hip and humerus fracture increased with age. Among women, there was evidence of significant variation in the occurrence of hip, distal forearm and humerus fractures across Europe, with incidence rates higher in Scandinavia than in other European regions. though for distal forearm fracture the incidence in east Europe was similar to that observed in Scandinavia. Among men, there was no evidence of significant geographic variation in the occurrence of these fractures. This is the first large population-based study to characterize the incidence of limb fracture in men and women over 50 years of age across Europe. There are substantial differences in the descriptive epidemiology of limb fracture by region and gender.
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