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Digitale Medien

Light-induced Mn2+ influx in Limulus ventral photoreceptors (1998)

Hsiao, H. S. ; Payne, R.

Springer

Journal of comparative physiology 183 (1998), S. 193-202

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ISSN: 1432-1351

Schlagwort(e): Key words Fura-2 ; Fluorescence ; Limulus ventral photoreceptors ; Mn2+ ; Calcium influx

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Medizin

Notizen: Abstract In contrast to insect species, light-activated influx of divalent ions into Limulus ventral photoreceptors has proven difficult to demonstrate. We used the quench of the fluorescent indicator dye, fura-2, to measure Mn2+ influx. Limulus ventral photoreceptors were injected with fura-2 and excited at 360 nm. When the photoreceptors were bathed in 1 mmol · l−1 Mn2+, an approximately 1% per 10 s decline in the fura-2 fluorescence during intervals between 50-ms flashes was taken as a measure of Mn2+ entry in darkness. Fluorescence decline during 10-s flashes was used to monitor Mn2+ entry during the photoresponse. During the 10-s flashes we observed a small rapid decline of the fura-2 fluorescence even in the absence of Mn2+. This reflected a contamination of the fluorescence signal arising from light-induced release of intracellular calcium stores. A subsequent slower decline in fluorescence during the 10-s flash, amounting to approximately 9% per 10 s, was only observed in the presence of extracellular Mn2+ and was attributed to Mn2+ influx. This light-activated influx was not through voltage-gated calcium channels since it persisted under voltage clamp, was not stimulated by depolarizing current injections, nor blocked by NiCl2. Depletion of internal calcium stores by cyclopiazonic acid treatment did not accelerate Mn2+ influx.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s003590050247

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Digitale Medien

Axial and Total-Body Bone Densitometry Using a Narrow-Angle Fan-Beam (2000)

Mazess, R. B. ; Hanson, J. A. ; Payne, R. ; [weitere]

Springer

Osteoporosis international 11 (2000), S. 158-166

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ISSN: 1433-2965

Schlagwort(e): Key words:Body composition – Bone density – Densitometry – Femur – Spine – Total body

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract: We assessed a new dual-energy bone densitometer, the PRODIGY, that uses a narrow-angle fan-beam (4.5°) oriented parallel to the longitudinal axis of the body (i.e., perpendicular to the usual orientation). High-resolution scans across the body can be stepped at 17 mm intervals. The energy-sensitive array detector uses cadmium zinc telluride, which allowed rapid photon counting. Spine and femur scans required 30 s, and total-body scans required 4–5 min; the dose was only 3.7 mrem and 0.04 mrem respectively, or about 5 to 10 times lower than conventional fan-beam densitometry. We found only a small influence of soft-tissue thickness on bone mineral density (BMD) results. There was also a small ( ± 1%) influence of height above the tabletop on BMD results. A software correction for object height allowed a first-order correction for the large magnification effects of position on bone mineral content (BMC) and area. Consequently, the results for BMC and area, as well as BMD, with PRODIGY corresponded closely to those obtained using the predecessor DPX densitometer, both in vitro and in vivo; there was a generally high correlation (r= 0.98–0.99) for BMD values. Spine and femur values for BMC, area and BMD averaged within 0.5% in vivo (n= 122), as did total-body BMC and BMD (n= 46). PRODIGY values for total-body lean tissue and fat also corresponded within 1% to DPX values. Regional and total-body BMD were measured with 0.5% precision in vitro and 1% precision in vivo. The new PRODIGY densitometer appears to combine the low dose and high accuracy of pencil-beam densitometry with the speed of fan-beam densitometers.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/PL00004178

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Digitale Medien

Investigation into the interactions of metals and metal ions in polymer matrices (1986)

Payne, R. ; Fritz, G. ; Naarmann, H.

Weinheim : Wiley-Blackwell

Angewandte Makromolekulare Chemie 144 (1986), S. 51-72

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ISSN: 0003-3146

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Beschreibung / Inhaltsverzeichnis: Es wurde die Dispersion von Solen einiger übergangsmetalle (Gold, Eisen(III)-oxid · H2O, Chromhydroxid) in einem wasserlöslichen Polymeren (PVA 4-88) untersucht und von den daraus hergestellten Filmen ein Vergleich ihrer mechanischen und elektrischen Eigenschaften gemacht. In Erweiterung auf nichtwäßrige Lösungsmittel (Dimethylformamid, Tetrahydrofuran) wurden die Wechselwirkungen von mehrwertigen Metallionen (Fe(III), Al(III), Ti(IV), Zr(IV), Pd(O), Ag(O), Au-Sole) mit einem spezifischen metallkomplexierenden Polymeren (Polyacrylamidoxim) und einem Blockcopolymeren, das Styrol und Butadien (Buna BL 6533) enthält, untersucht.

Notizen: The dispersion of transition metal sols (gold, ferric hydrous oxide, chromium hydroxide) in a water soluble polymer (PVA 4-88) was investigated and from the films produced, a comparison made of their mechanical and electrical properties. Extending to non aqueous solvents (dimethylformamide, tetrahydrofuran) interactions of polyvalent metal ions (Fe(III), Al(III), Ti(IV), Zr(IV), Pd(0), Ag(0), Au sols) with a specific metal complexing polymer (poly(acrylamideoxime)) and a block copolymer containing styrene and butadiene (Buna BL 6533) were investigated.

Zusätzliches Material: 3 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/apmc.1986.051440105

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