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- Wang, W, et al.
(författare)
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Stimulatory activity of anti-peptide antibodies against the second extracellular loop of human M2 muscarinic receptors.
- 2000
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Ingår i: Chinese medical journal. - 0366-6999. ; 113:10, s. 867-71
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To study the activity of anti-peptide antibodies against the second extracellular loop of human M2 muscarinic receptors on cAMP production and inward calcium currents (Ica) in guinea pig ventricular myocytes. A comparison was also made with those of a muscarinic receptor agonist. METHODS: cAMP content was determined by radioimmunoassay and the Ica in guinea pig single ventricular cells were recorded by the whole-cell patch clamp technique. RESULTS: Both the muscarinic receptor agonist, carbachol (Carb 10 mumol/L), and anti-peptide antibodies (Abs 100 nmol/L) could decrease basal cAMP levels (by 46.9% +/- 4.2% and 60.2% +/- 4.6%, respectively) and basal Ica. Both Carb (10 mumol/L) and Abs (100 nmol/L) could also inhibit the isoprenaline-induced (Iso 0.8 mumol/L) increases in cAMP production (from 108.2 +/- 7.0 to 88.4 +/- 7.2 pmol/mg.protein/min for Carb and 88.6 +/- 5.1 pmol/mg.protein/min for Abs, respectively) and the increases in Ica. The muscarinic receptor antagonist atropine (Atr) was able to prevent these effects of Carb and Abs. CONCLUSIONS: Anti-peptide antibodies against an epitope located in the second extracellular loop of human M2 muscarinic receptors, similar to muscarinic receptor agonist, could decrease the basal Ica and beta-receptor agonist stimulated increase of Ica by decreasing the basal and beta-receptor agonist stimulated increase of cAMP production, and therefore could have an effect on their target receptor. These results further suggest that autoimmunity may participate in the pathogenesis of human cardiomyopathy and the second extracellular loop of human M2 muscarinic receptor could be the main immunodominant region.
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- Fu, X, et al.
(författare)
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Oxytocin-induced oscillations of cytoplasmic Ca2+ in human myometrial cells.
- 2000
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Ingår i: Acta Obstetricia et Gynecologica Scandinavica. - 0001-6349 .- 1600-0412. ; 79:3
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: To investigate the mechanisms of oxytocin (OT) induced oscillations of the cytoplasmic Ca2+ concentration ([Ca2+]i) in cultured human myometrial cells.METHODS: [Ca2+]i was measured in individual myometrial cells by dual wavelength spectrophotofluorometry using the fluorescent indicator fura-2. Myometrium was obtained at abdominal hysterectomy (n=8) and during cesarean section (n=7).RESULTS: OT (10-300 nM) typically induced [Ca2+]i oscillations with frequencies in the 0.6-0.8/min range. There were no obvious differences in the responses of cells taken from non-pregnant and term pregnant women. The frequency and amplitude of the oscillations were not significantly affected by OT concentrations up to 300 nM. The amplitude of the oscillations decreased in the presence of the voltage-dependent Ca2+ channel antagonist verapamil and gradually disappeared in Ca2+-free medium. The oscillations were further blocked by the inorganic Ca2+ antagonist La3+ and by the intracellular Ca2+-ATPase inhibitor 2.5-di-tert-butylhydroquinone (DTBHQ). Caffeine inhibited the OT-induced oscillations in a concentration-dependent manner. DTBHQ and high concentrations of OT made [Ca2+]i remarkably sensitive to changes in the external Ca2+ concentration.CONCLUSIONS: The results indicate that OT-induced [Ca2+]i oscillations in human myometrial cells are due to inositol 1,4,5-trisphosphate-mediated release of intracellular Ca2+ combined with capacitative as well as voltage-dependent influx of the ion.
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- Fu, Y, et al.
(författare)
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Photocurrents of 14 mu m quantum-well infrared photodetectors
- 2003
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Ingår i: Journal of Applied Physics. - : American Institute of Physics. - 0021-8979 .- 1089-7550. ; 93:12, s. 9432-9436
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Tidskriftsartikel (refereegranskat)abstract
- We study the factors that determine photogenerated carriers and response wavelengths of photocurrents of long wavelength (similar to14 mum) quantum well (QW) infrared photodetectors (QWIPs). The material structures of QWIPs are first characterized by the photoluminescence measurements (PL). By calculating the density of photogenerated carriers in the continuum above the energy barriers using the PL calibrated QWIP structures, we have demonstrated that due to the sample quality, the photocarriers can be either in miniband states (Bloch states in the multiple quantum wells), or they transport from one quantum well to the next in the form of running waves. By including possible scattering processes at the QWIP working temperature to link the theoretically calculated photocarrier density with the experimentally measured photocurrent, it is shown that the width of the photocurrent peaks of 14 mum GaAs/AlGaAs QWIPs under investigation is determined by the optical phonon emissions of photocarriers. We have further calculated the densities of photocarriers in the QWIPs reported in the literature. It is shown that the Bloch wave boundary conditions are appropriate for QWIPs with narrow QWs, whereas running wave boundary conditions are appropriate for wide QWs.
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- Liu, Jing-fu, et al.
(författare)
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Ionic liquids/water distribution ratios of some polycyclic aromatic hydrocarbons
- 2004
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Ingår i: Journal of Chemical and Engineering Data. - : American Chemical Society (ACS). - 1520-5134 .- 0021-9568. ; 49:5, s. 1422-1424
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Tidskriftsartikel (refereegranskat)abstract
- By using the shake-flask procedure, the distribution ratios (D) at infinite dilution and 298.1 K of 15 polycyclic aromatic hydrocarbons (PAHs) between room-temperature ionic liquids, 1-alkyl-3-methylimiazolium hexafluorophosphates ([CnMIM] [PF6], n = 4 and 8), and water were determined. The log D values are in the range of 3.34-4.36, which increased very slowly with the molar mass of PAHs.
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- Zhu, Bin, et al.
(författare)
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LiF-MgF2 composite electrolyte for advanced ceramic fuel cells : structure, electrical properties and applications
- 2002
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Ingår i: Solid State Ionics. - 0167-2738 .- 1872-7689. ; 148:04-mar, s. 583-589
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Tidskriftsartikel (refereegranskat)abstract
- The two-phase composite, LiF-MgF2, has been discovered to have high ionic conductivity within a wide composition range, e.g., 10(-2)-10(-1) S cm(-1) at 600-800 degreesC, which is several orders of magnitude higher than that of pure LiF or MgF2. In addition, the activation energy of the composite is much lower than that of the pure phases. The remarkable conductivity enhancement as well as the low activation energy is attributed to the composite effect, i.e., the conduction takes place mainly in the interfacial region between LiF and MgF2 grains. The agreements of conductivity derived from two different methods, impedance spectra and fuel cell characterisation, in combination of the ESR results, show a possibility that proton (plus hydride ion) conduction dominates the electrical conduction in the LiF-MgF2 system under the H-2/air fuel cell environments.
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