| 1. |
- Dunham, I, et al.
(författare)
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The DNA sequence of human chromosome 22
- 1999
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 402:6761, s. 489-495
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Leung, P S, et al.
(författare)
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Angiotensin II receptors: localization of type I and type II in rat epididymides of different developmental stages.
- 1997
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Ingår i: The Journal of membrane biology. - 0022-2631. ; 157:1, s. 97-103
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies from our laboratory have provided evidence for the existence of a local renin-angiotensin system in the rat epididymis. Evidence has also accumulated, indicating that locally formed angiotensin II from the rat epididymis may play a paracrine and/or autocrine role in regulating epididymal electrolyte and fluid transport. In the present study, specific anti-peptide antibodies against the second extracellular loops of angiotensin II type I (AT1) and type II (AT2) receptors were used to localize immunocytochemically these receptors in the rat cauda epididymides of three developmental stages, namely, immature (2-week), early mature (6-week) and fully mature (10-week). The immunostaining intensity for AT1 receptors was found to be stronger than that for AT2 receptors throughout rat epididymides of all stages. However, the immunostaining for both AT1 and AT2 receptors observed in the fully mature rat epididymis was much more intense than that observed in the epididymides of the two younger stages. While the immunostaining for both AT1 and AT2 receptors in the younger rat epididymides appeared to be distributed in both basal and apical regions, the immunostaining in the fully mature epididymis was predominantly localized in the basal region. The present finding of the differential patterns of angiotensin II receptor immunoreactivity in three different stages of the rat epididymis may reflect the fine tuning of rat epididymal function by angiotensin II, acting as a paracrine or autocrine agent, during the course of development.
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| 3. |
- Chan, H C, et al.
(författare)
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Angiotensin II receptor type I-regulated anion secretion in cystic fibrosis pancreatic duct cells.
- 1997
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Ingår i: The Journal of membrane biology. - 0022-2631. ; 156:3, s. 241-9
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Tidskriftsartikel (refereegranskat)abstract
- The beta-adrenergic (cAMP-dependent) regulation of Cl- conductance is defective in cystic fibrosis (CF). The present study explored alternative regulation of anion secretion in CF pancreatic ductal cells (CFPAC-1) by angiotensin II (AII) using the short-circuit current (ISC) technique. An increase in ISC could be induced in CFPAC-1 cells by basolateral or apical application of AII in a concentration-dependent manner (EC50 at 3 microm and 100 nm, respectively). Angiotensin receptor subtypes were identified using specific antagonists, losartan and PD123177, for AT1 and AT2 receptors, respectively. It was found that losartan (1 microm) could completely inhibit the AII-induced ISC, whereas, PD123177 exerted insignificant effect on the ISC, indicating predominant involvement of AT1 receptors. The presence of AT1 receptors in CFPAC-1 cells was also demonstrated by immunohistochemical studies using specific antibodies against AT1 receptors. Confocal microscopic study demonstrated a rise in intracellular Ca2+ upon stimulation by AII indicating a role of intracellular Ca2+ in mediating the AII response. Depletion of intracellular but not extracellular pool of Ca2+ diminished the AII-induced ISC. Treatment of the monolayers with a Cl- channel blocker, DIDS, markedly reduced the ISC, indicating that a large portion of the AII-activated ISC was Cl--dependent. AII-induced ISC was also observed in monolayers whose basolateral membranes had been permeabilized by nystatin, suggesting that the ISC was mediated by apical Cl- channels. Our study indicates an AT1-mediated Ca2+-dependent regulatory mechanism for anion secretion in CF pancreatic duct cells which may be important for the physiology and pathophysiology of the pancreas.
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| 4. |
- Leung, P S, et al.
(författare)
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Angiotensin II receptors, AT1 and AT2 in the rat epididymis. Immunocytochemical and electrophysiological studies.
- 1997
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Ingår i: Biochimica et biophysica acta. - 0006-3002. ; 1357:1, s. 65-72
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Tidskriftsartikel (refereegranskat)abstract
- Previous work from our laboratory has provided evidence for the presence of a tissue renin-angiotensin system in the rat epididymis. In the current investigation, the regional localization of angiotensin II receptors, type I (AT1) and type II (AT2) was studied immunocytochemically using specific anti-peptide antibodies against the second extracellular loops of AT1 and AT2 receptors, and pharmacologically using specific receptor antagonists in conjunction with the short-circuit current technique. The immunocytochemical results showed that AT1 and AT2 immunoreactivities were predominantly localized in the basal region of the epididymal epithelium. Electrophysiological studies using the short-circuit current technique demonstrated a stimulatory effect of basolaterally applied angiotensin II on the epididymal electrogenic ion transport. This effect was inhibitable by the addition of AT1 antagonist, losartan but not by AT2 antagonist, PD123177, indicating a functional role of AT1 in epididymal electrolyte transport. The present finding suggests that angiotensin II receptors may play an important role in the regulation of epididymal function.
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| 5. |
- Leung, P S, et al.
(författare)
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Differential gene expression of angiotensin II receptor subtypes in the epididymides of mature and immature rats.
- 1998
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Ingår i: Life sciences. - 0024-3205. ; 62:5, s. 461-8
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies have suggested that epididymal and sperm functions are subject to control by a local renin-angiotensin II system (RAS) in the rat epididymis. Type-1 angiotensin II receptor, AT1 and type-2 receptor, AT2 were localized in epididymal epithelium, indicating that RAS may act in a paracrine or autocrine fashion to regulate fluid secretion, probably through the basally placed membrane-bound AT1 protein as revealed by immunocytochemical and electrophysiological studies. In the present work, the expression of the angiotensin II receptor subtypes in the rat epididymis was showed by western blot analysis and reverse-transcription polymerase chain reaction (RT-PCR) using specific primers for the angiotensin II receptor subtypes. Western blot analysis showed the expression of AT1 receptor in the rat epididymis. Results from RT-PCR, using specific primers based on the corresponding angiotensin II receptor subtype genes for AT1a, AT1b and AT2 , demonstrated the differential expression of mRNAs from these receptor subtypes in the epididymides of mature and immature rats. Both the genes for AT1a and AT1b, but not that for AT2, are predominantly expressed in the epididymides of mature rat. In contrast, only AT1a and AT2 were highly expressed in the epididymides of immature rat. These results suggest that the expression of type-1 and type-2 angiotensin II receptor subtypes are developmentally regulated. Type-1 subtype may play a role in regulation of electrolyte and fluid transport in mature rat whereas type-2 subtype may be important in growth and development in the immature rat.
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| 6. |
- Meng, Y, et al.
(författare)
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Estimation of the directions of arrival of spatially dispersed signals in array processing
- 1996
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Ingår i: IEE PROCEEDINGS-RADAR SONAR AND NAVIGATION. - : IEE-INST ELEC ENG. - 1350-2395. ; 143:1, s. 1-9
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The problem of estimating the DOA of spatially distributed signals is examined. A mathematical model is first established by making some reasonable assumptions. The correlation matrix of a distributed signal is then derived. The important properties of th
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| 7. |
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