| 1. |
- Fu, Michael, 1963, et al.
(författare)
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Gi-mediated muscarinic adenylyl cyclase inhibition in timolol-treated stunned porcine myocardium.
- 1994
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Ingår i: Acta physiologica Scandinavica. - 0001-6772. ; 151:3, s. 291-9
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Tidskriftsartikel (refereegranskat)abstract
- The Gi-mediated muscarinic receptor-adenylyl cyclase system was examined in stunned myocardium induced by either three or five brief ischaemic periods after beta-adrenoceptor blockade by timolol (0.1 mg kg-1). The mid-left anterior descending coronary artery was occluded for 2, 10 and 2 min in four pigs, and for 2, 2, 5, 10 and 2 min in four other pigs. All the ischaemic periods were separated by 30 min of reperfusion and the biopsies were obtained 60 min after the last ischaemic period. Segment length function was measured in the ischaemic region and in the control region supplied by the left circumflex artery. In the two groups, the percentage systolic shortening was reduced equally, to 59 +/- 9 and 58 +/- 10% of control in the region subjected to ischaemia and only minimally in the control region. The biopsies from the stunned region from both groups showed: (1) no change in either the affinity for carbachol or the number of binding sites of the muscarinic receptors; (2) no alterations in messenger RNA encoding for the alpha subunit-2 of the inhibitory guanine nucleotide binding protein, as demonstrated by northern blot and solution hybridization; (3) no change in membrane-bound inhibitory guanine nucleotide binding protein, as shown by enzyme immunoassay utilizing a specific anti-peptide antibody, and (4) unchanged inhibition of stimulated adenylyl cyclase activity. These results suggest that there is an intact inhibitory guanine nucleotide binding protein-mediated muscarinic receptor adenylyl cyclase system in the stunned porcine myocardium.
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| 2. |
- Kröll, Stefan, et al.
(författare)
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Intensity dependent photon echo relaxation in rare earth doped crystals
- 1990
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Ingår i: Physical Review B (Condensed Matter). - 0163-1829. ; 41:16, s. 11568-11571
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Tidskriftsartikel (refereegranskat)abstract
- Photon-echo-relaxation measurements made on the 3H4-3P0 transition of 0.01 at. % Pr3+:YAG (where YAG represents yttrium aluminum garnet), 3H4-1D2 transition in 0.1 at. % Pr3+:YAlO3, and 7F0-5D0 transition in 0.25 at. % Eu3+:YAlO3 show that the photon-echo relaxation rate increases when the intensities of the excitation pulses are increased. Although a part of the relaxation-rate increase in Pr3+:YAG may be attributed to an instantaneous spectral diffusion (ISD) in which the presence of excited neighboring Pr3+ ions change the local field and the absorption frequency of the rare-earth ions, our data deviate significantly from the ISD-model predictions. An additional intensity-dependent relaxation mechanism is required to explain the results.
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| 3. |
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| 4. |
- Xu, E. Y, et al.
(författare)
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Nanosecond image processing using stimulated photon echoes
- 1990
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Ingår i: Optics Letters. - 0146-9592. ; 15:10, s. 562-564
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Tidskriftsartikel (refereegranskat)abstract
- Processing of two-dimensional images on a nanosecond time scale is demonstrated using the stimulated photon echoes in a rare-earth-doped crystal (0.1 at. \% Pr3$+$:LaF3). Two spatially encoded laser pulses (pictures) resonant with the 3P0-3H4 transition of Pr3$+$ were stored by focusing the image pulses sequentially into the Pr3$+$:LaF3 crystal. The stored information is retrieved and processed by a third read pulse, generating the echo that is the spatial convolution or correlation of the input images. Application of this scheme to high-speed pattern recognition is discussed.
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