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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of chemical & engineering data 33 (1988), S. 10-12 
    ISSN: 1520-5134
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish diseases 10 (1987), S. 0 
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 106 (1988), S. 13-28 
    ISSN: 1432-1424
    Keywords: cell potential ; amiloride ; sodium transport ; reversal potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Knowledge of the voltage dependencies of apical and basolateral conductances is important in determining the factors that regulate transcellular transport. To gain this knowledge it is necessary to distinguish between cellular and paracellular currents and conductances. This is generally done by sequentially measuring transepithelial current/voltage (I t /V t ) and conductance/voltage (g t /V t ) relationships before and after the abolition of cellular sodium transport with amiloride. Often, however, there are variable time-dependent and voltage-dependent responses to voltage perturbation both in the absence and presence of amiloride, pointing to effects on the paracellular pathway. We have here investigated these phenomena systematically and found that the difficulties were significantly lessened by the use of an intermittent technique, measuringI t andg t before and after brief (〈10 sec) exposure to amiloride at each setting ofV t .I/V relationships were characterized by these means in frog skins (Rana pipiens, Northern variety, andRana temporaria). Cellular current,I c , decreased with hyperpolarization (larger serosa positive clamps) ofV t . DerivedI c /V t relationships betweenV t =0 and 175 mV (serosa positive) were slightly concave upwards. Because values of cell conductance,g c , remained finite, it was possible to demonstrate reversal ofI c . Values of the reversal potentialV' averaged 156±14 (sd,n=18) mV. Simultaneous microelectrode measurements permitted also the calculation of apical and basolateral conductances,g a andg b . The apical conductance decreased monotonically with increasing positivity ofV t (andV a ). In contrast, in the range in which the basolateral conductance could be evaluated adequately (V t 〈125 mV),g b increased with more positive values ofV t (andV b ). That is, there was an inverse relation betweeng b and cellular current at the quasi-steady state, 10–30 sec after the transepithelial voltage step.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 90 (1986), S. 89-96 
    ISSN: 1432-1424
    Keywords: frog skin ; membrane potential ; voltage clamp ; K+ depolarization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary In studies of apical membrane current-voltage relationships, in order to avoid laborious intracellular microelectrode techniques, tight epithelia are commonly exposed to high serosal K concentrations. This approach depends on the assumptions that high serosal K reduces the basolateral membrane resistance and potential to insignificantly low levels, so that transepithelial values can be attributed to the apical membrane. We have here examined the validity of these assumptions in frog skins (Rana pipiens pipiens). The skins were equilibrated in NaCl Ringer's solutions, with transepithelial voltageV t clamped (except for brief perturbations ΔV t) at zero. The skins were impaled from the outer surface with 1.5m KCl-filled microelectrodes (R el〉30 MΩ). The transepithelial (short-circuit) currentl i and conductanceg t=−ΔI t/ΔV t, the outer membrane voltageV o (apical reference) and voltage-divider ratio (F o=ΔV o/ΔV t), and the microelectrode resistanceR el were recorded continuously. Intermittent brief apical exposure to 20 μm amiloride permitted estimation of cellular (c) and paracellular (p) currents and conductances. The basolateral (inner) membrane conductance was estimated by two independent means: either from values ofg i andF o before and after amiloride or as the ratio of changes (−ΔI c/ΔV i) induced by amiloride. On serosal substitution of Na by K, within about 10 min,I c declined andg t increased markedly, mainly as a consequence of increase ing p. The basolateral membrane voltage (V i(=−V o) was depolarized from 75±4 to 2±1 mV [mean±sem (n=6)], and was partially repolarized following amiloride to 5±2 mV. The basolateral conductance increased in high serosal K, as estimated by both methods. Essentially complete depolarization of the basolateral membrane and increase in its conductance in response to high [K] were obtained also when the main serosal anion was SO4 or NO3 instead of Cl. On clampingV t over the range 0 to +125 mV in K2SO4-depolarized skins, the quasi-steady-stateV o V t relationship was linear, with a mean slope of 0.88±0.03. The above results demonstrate that, in a variety of conditions, exposure to high serosal K results in essentially complete depolarization of the basolateral membrane and a large increase in its conductance.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 92 (1986), S. 37-46 
    ISSN: 1432-1424
    Keywords: frog skin ; cell Na activity ; membrane potential ; Na pump flux ; Na microelectrodes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Cell Na activity,a Na c , was measured in the short-circuited frog skin by simulaneous cell punctures from the apical surface with open-tip and Na-selective microelectrodes. Skins were bathed on the serosal surface with NaCl Ringer and, to reduce paracellular conductance, with NaNO3 Ringer on the apical surface. Under control conditionsa Na c averaged 8±2mm (n=9,sd). Apical addition of amiloride (20 μm) or Na replacement reduceda Na c to 3mm in 6–15 min. Sequential decreases in apical [Na] induced parallel reductions ina Na c and cell current,I c . On restoring Na after several minutes of exposure to apical Na-free solutionI c rose rapidly $$(\tilde〈 30\sec )$$ to a stable value whilea Na c increased exponentially, with a time constant of 1.8±0.7 min (n=8). Analysis of the time course ofa Na c indicates that the pump Na flux is linearly related toa Na c in the range 2–12mm. These results indicate thata Na c plays an important role in relating apical Na entry to basolateral active Na flux.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 85 (1985), S. 143-158 
    ISSN: 1432-1424
    Keywords: frog skin ; anions and sodium transport ; membrane potential ; K activity ; pump current ; constant current source
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Cell K activity,a k, was measured in the short-circuited frog skin by simultaneous cell punctures from the apical surface with open-tip and K-selective microelectrodes. Strict criteria for acceptance of impalements included constancy of the open-tip microelectrode resistance, agreement within 3% of the fractional apical voltage measured with open-tip and K-selective microelectrodes, and constancy of the differential voltage recorded between the open-tip and the K microelectrodes 30–60 sec after application of amiloride or substitution of apical Na. Skins were bathed on the serosal surface with NaCl Ringer and, to reduce paracellular Cl conductance and effects of amiloride on paracellular conductance, with NaNO3 Ringer on the apical surface. Under control conditionsa k r was nearly constant among skins (mean±SD=92±8mM, 14 skins) in spite of a wide range of cellular currents (5 to 70 μA/cm2). Cell current (and transcellular Na transport) was inhibited by either apical addition of amiloride or substitution of Na by other cations. Although in some experiments the expected small increase ina k r after inhibition of cell current was observed, on the average the change was not significant (98±11mM after amiloride, 101±12mM after Na substitution), even 30 min after the inhibition of cell current. The membrane potential, which in the control state ranged from −42 to −77 mV, hyperpolarized after inhibition of cell current, initially to −109±5mV, then depolarizing to a stable value (−88±5mV) after 15–25 min. At this time K was above equilibrium (E k=98±2mV), indicating that the active pump mechanism is still operating after inhibition of transcellular Na transport. The measurement ofa k r permitted the calculation of the passive K current and pump current under control conditions. assuming a “constant current source” with almost all of the basolateral conductance attributable to K. We found a significant correlation between pump current and cell current with a slope of 0.31, indicating that about one-third of the cell current is carried by the pump, i.e., a pump stoichiometry of 3Na/2K.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-2323
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Entre janvier 1983 et décembre 1986, nous avons traité 9 patients ayant un kyste du cholédoque (âges extrêmes: 2 ans 4 mois et 36 ans). Les symptômes étaient douleur dans l'hypocondre droit (n=9), angiocholite (n=7), et ictère (n=6). Une masse dans l'hypocondre était palpable chez 7 patients et 5 présentaient une lithiase biliaire associée. Le diagnostic a été établi par la cholangiographie intraveineuse et l'échographie. Tous les patients ont eu une incision sous-costale droite. Le diamètre du kyste du cholédoque allait de 4.5 à 7 cm. Après avoir disséqué le kyste en le séparant de l'artère hépatique et de la veine porte, on a sectionné le cholédoque audessus du duodénum et fermé le bout distal avec des points séparés. Le canal hépatique commun a été sectionné juste audessus du confluent supérieur et une plastie d'agrandissement a été réalisée grâce à une incision longitudinale du canal hépatique gauche. Une anse jéjunale de 30 cm a ensuite été isolée et montée à travers le mésocôlon transverse à droite des vaisseaux coliques derrière le duodénum pour être anastomosée en haut avec le confluent hépatique et en bas avec le 2e duodénum. L'anastomose hépatojéjunale a été réalisée en un plan par des points séparés au fil résorbable. Pendant la période d'observation (1 à 4 ans), il n'y a eu ni mort ni complication grave: aucun patient n'a présenté angiocholite, fièvre, ou douleur. En période postopératoire, tous les patients ont subi des examens de laboratoire, une échographie, une scintigraphie au Tc 99m, et un transit baryté oesogastroduodénal. Ces examens ont montré une fonction hépatique et une excrétion biliaire satisfaisantes et l'absence de tout reflux duodénojéjunobiliaire.
    Abstract: Resumen En el período desde enero de 1983 hasta diciembre de 1986, fueron tratados 9 pacientes (edades entre 2 años y 4 meses y 36 años) con quistes coledocianos. Los síntomas principales fueron el dolor en el cuadrante superior derecho del abdomen (n=9), colangitis ascendente (n=7), e ictericia (n=6). Se palpaba masa en el cuadrante superior derecho en 7 pacientes y 5 exhibían cálculos biliares. El diagnóstico fue establecido mediante colangiografía intravenosa y ultrasonografía. La operacion fue realizada a través de laparotomía subcostal derecha. El diámetro del quiste coledociano varió entre 4.5 y 7 cm. El quiste y el canal colédoco fueron disecados de la arteria hepática y de la vena porta. El colédoco fue seccionado por encima del duodeno y su cabo distal fue cerrado con suturas interrumpidas. El colédoco fue seccionado por debajo de la confluencia de los canales hepáticos y su diámetro aumentado mediante la sección longitudinal del canal hepático izquierdo. Un segmento aislado de yeyuno de 30 cm de longitud fue pasado a través del mesocolon transverso por la derecha de los vasos cólicos medios y por detrás del duodeno para ser interpuesto entre la confluencia hepática y la segunda porción del duodeno. La anastomosis bilio-yeyunal fue realizada en una capa con suturas interrumpidas absorbibles. No hubo mortalidad ni complicaciones sérias en el período de seguimiento (uno a cuatro años). Ningún paciente desarrolló colangitis, fiebre, o dolor. Todos los pacientes fueron estudiados postoperatoriamente con pruebas bioquímicas, ultrasonografía, DISIDA con Tc 99m, y trago de bario. Se demostró buena función hepática, adecuada excreción biliar, y ausencia de reflujo duodenoyeyunal.
    Notes: Abstract From January, 1983 to December, 1986, a total of 9 patients, ranging in age from 2 years and 4 months to 36 years, with choledochal cysts were treated. Symptoms were right upper quadrant pain (n=9), ascending cholangitis (n=7), and jaundice (n=6). A right upper quadrant mass was palpable in 7 patients and gallstones were present in 5 patients. Diagnosis was established by intravenous cholangiogram and ultrasound. The operation was performed through a right subcostal laparotomy. The choledochal cyst diameter ranged from 4.5 to 7 cm. The cyst and the common duct were dissected from the hepatic artery and portal vein. The choledochus was sectioned above the duodenum and the distal end was closed by interrupted sutures. The common duct was divided below the hepatic confluence and the diameter enlarged by longitudinal section of the left hepatic duct. A 30-cm-long segment of isolated jejunum was passed through the transverse mesocolon to the right of the middle colic vessels and behind the duodenum and then interposed between the hepatic confluence and the second portion of the duodenum. Biliary-jejunal anastomosis was performed in 1 layer with interrupted absorbable stitches. No mortality or serious complications occurred during follow-up (1–4 years). No cholangitis, fever, or pain have developed. All patients were studied postoperatively by biochemical test, ultrasonography, Tc 99m DISIDA, and barium meal swallow. Good liver function and biliary excretion, and absence of duodeno-jejuno biliary reflux were demonstrated.
    Type of Medium: Electronic Resource
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  • 9
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    Unknown
    Madrid : Periodicals Archive Online (PAO)
    Revista internacional de sociología. [ser.2]:46:3 (1988:jul./sept.) 325 
    ISSN: 0034-9712
    Topics: Sociology
    Notes: NUMERO MONOGRAFICO: NUEVAS TECNOLOGIAS Y CONSUMO
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Archiv der Mathematik 52 (1989), S. 155-158 
    ISSN: 1420-8938
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
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