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  • 1
    Electronic Resource
    Electronic Resource
    Transport of small organic cations in the rat liver (1996)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 354 (1996), S. 320-326 
    Details
    ISSN: 1432-1912
    Keywords: Rat liver ; Transport of organic cations ; OCT1 ; Type I hepatic transport of cationic drugs ; 1-Methyl-4-phenylpyridinium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The kidneys and the liver are the principal organs for the inactivation of circulating organic cations. Recently, an organic cation transporter (OCT1) has been cloned from rat kidney. In order to answer the question whether OCT1 is involved also in hepatic uptake of organic cations, the pharmacological characteristics of organic cation transport in hepatocytes were compared to the characteristics of transiently expressed OCT1. Primary cultures of rat hepatocytes avidly accumulated the small organic cation 3H-1-methyl-4-phenylpyridinium (3H-MPP+). At equilibrium, the hepatocytes accumulated 3H-MPP+ 56-fold. Initial rates of specific 3H-MPP+ transport in hepatocytes were saturable. The half-saturating concentration was 13 μmol/l. 3H-MPP+ transport was sensitive to quinine (Ki = 0.79 μmol/l) and cyanine863 (Ki = 0.097 µmol/l). Quinine and cyanine863 are known inhibitors of type I hepatic transport of cationic drugs and of renal excretion of organic cations, respectively. To compare the functional characteristics of 3H-MPP+ transport in hepatocytes with those of OCT1, OCT1 has been heterologously expressed and characterized in a mammalian cell line (293 cells). Initial rates of 3H-MPP+ transport were saturable, the Km being 13 μmol/l. The rank order of inhibitory potencies of various inhibitors was almost identical in hepatocytes and 293 cells transiently transfected with OCT1. There was a positive correlation between the Ki's for the inhibition of 3H-MPP+ transport in isolated hepatocytes and transfected 293 cells (r = 0.85; P〈0.01; n = 8). The results indicate that OCT1 is functionally expressed not only in the kidney but also in hepatocytes where it is responsible for the transport of small organic cations which, in the past, have been classified as type I substrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00171063
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  • 2
    Electronic Resource
    Electronic Resource
    High CO2 content of fluid inclusions in gold mineralisations in the Ashanti Belt, Ghana: a new category of ore forming fluids? – a reply (1998)
    Springer
    Mineralium deposita 33 (1998), S. 320-322 
    Details
    ISSN: 1432-1866
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001260050152
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  • 3
    Electronic Resource
    Electronic Resource
    Experiments on the Richtmyer-Meshkov instability of an air/SF6 interface (1995)
    Springer
    Shock waves 4 (1995), S. 247-252 
    Details
    ISSN: 1432-2153
    Keywords: Richtmyer-Meshkov instability ; Flow visualization ; Experiment ; Shock tube ; Turbulent mixing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics , Technology
    Notes: Abstract Results of flow visualization experiments of an impulsively accelerated plane interface between air and SF6 are reported. The shock tube used for the experiments has a larger test section than in previous experiments. The larger extent of uniform test flow relative to nonuniform boundary-layer flow permits unambiguous interpretation of flow-visualization photographs, and the influence of shock-wave/boundary-layer interactions is no longer dominant. The strong wall vortex observed in previous studies is not observed in these experiments. It is found that the thin membrane, which forms the initially plane interface, has a significant influence on the initial growth rate of the interface thickness. However, the measured growth rates after the first reflected shock are independent of membrane configuration and are in good agreement with analytical predictions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01416035
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  • 4
    Electronic Resource
    Electronic Resource
    Na Absorption Across Endometrial Epithelial Cells is Stimulated by cAMP-dependent Activation of an Inwardly Rectifying K Channel (1997)
    Springer
    The journal of membrane biology 160 (1997), S. 119-126 
    Details
    ISSN: 1432-1424
    Keywords: Key words: K secretion — Na channel — Epithelial ion transport — Uterus — PGF2α
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract. Previous studies in our laboratory have shown that Na absorption across the porcine endometrium is stimulated by PGF2α and cAMP-dependent activation of a barium-sensitive K channel located in the basolateral membrane of surface epithelial cells. In this study, we identify and characterize this basolateral, barium-sensitive K conductance. Porcine uterine tissues were mounted in Ussing chambers and bathed with KMeSO4 Ringer solution. Amphotericin B (70 μm) was added to the luminal solution to permeabilize the apical membrane and determine the current-voltage relationship of the basolateral K conductance after activation by 100 μm CPT-cAMP. An inwardly rectifying current was identified which possessed a reversal potential of −53 mV when standard Ringer solution was used to bathe the serosal surface. The K:Na selectivity ratio was calculated to be 12:1. Administration of 5 mm barium to the serosal solution completely inhibited the current activated by cAMP under these conditions. In addition to these experiments, amphotericin-perforated whole cell patch clamp recordings were obtained from primary cultures of porcine surface endometrial cells. The isolated cells displayed an inwardly rectifying current under basal conditions. This current was significantly stimulated by CPT-cAMP and blocked by barium. These results together with our previous studies demonstrate that cAMP increases Na absorption in porcine endometrial epithelial cells by activating an inwardly rectifying K channel present in the basolateral membrane. Similar patch clamp experiments were conducted using cells from a human endometrial epithelial cell line, RL95-2. An inwardly rectifying current was also identified in these cells which possessed a reversal potential of −56 mV when the cells were bathed in standard Ringer solution. This current was blocked by barium as well as cesium. However, the current from the human cells did not appear to be activated by cAMP, indicating that distinct subtypes of inwardly rectifying K channels are present in endometrial epithelial cells from different species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002329900301
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  • 5
    Electronic Resource
    Electronic Resource
    NAD-dependent malate dehydrogenase and glyceraldehyde 3-phosphate dehydrogenase isoenzymes play an important role in dark metabolism of various plastid types (1998)
    Springer
    Planta 205 (1998), S. 359-366 
    Details
    ISSN: 1432-2048
    Keywords: Key words:Capsicum (fruit plastids) ; Dark metabolism ; Glyceraldehyde 3-phosphate dehydrogenase ; Malate dehydrogenase ; Malate valve ; Spinacia (chloroplasts)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Chloroplasts isolated from spinach (Spinacia oleracea L.) leaves and green sweet-pepper (Capsicum annuum L. var. grossum (L.) Sendt.) fruits contain NADP-dependent malate dehydrogenase (MDH; EC 1.1.1.82) and the bispecific NAD(P)-glyceraldehyde 3-phosphate dehydrogenase (GAPDH; EC 1.2.1.13). The NADP-dependent MDH and GAPDH are activated in the light, and inactive in the dark. We found that chloroplasts possess additional NAD-dependent MDH activity which is, like the NAD-dependent GAPDH activity, not influenced by light. In heterotrophic chromoplasts from red sweet-pepper fruits, the NADP-dependent MDH and the NAD(P)-GAPDH isoenzymes disappear during the developmental transition and only NAD-specific isoforms are found. Spinach chloroplasts contain both NAD/H and NADP/H at significant concentrations. Measurements of the pyridine dinucleotide redox states, performed under dark and various light conditions, indicate that NAD(H) is not involved in electron flow in the light. To analyze the contribution of NAD(H)-dependent reactions during dark metabolism, plastids from spinach leaves or green and red sweet-pepper fruits were incubated with dihydroxyacetone phosphate (DHAP). Exogenously added DHAP was oxidized into 3-phosphoglycerate by all types of plastids only in the presence of oxaloacetate, but not with nitrite or in the absence of added electron acceptors. We conclude that the NAD-dependent activity of GAPDH is essential in the dark to produce the ATP required for starch metabolism; excess electrons produced during triose-phosphate oxidation can selectively be used by NAD-MDH to form malate. Thus NADPH produced independently in the oxidative pentose-phosphate pathway will remain available for reductive processes inside the plastids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050331
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  • 6
    Electronic Resource
    Electronic Resource
    Angiotensin converting enzyme inhibitors block mitogenic signalling pathways in rat cardiac fibroblasts (1999)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 359 (1999), S. 394-399 
    Details
    ISSN: 1432-1912
    Keywords: Key words Angiotensin II ; ACE inhibition ; Moexiprilat ; Enalaprilat ; Cardiac fibroblast ; Mitogen ; activated protein kinases (MAPKs) ; Signal transducer and activator of transcription (STAT)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We studied the effects of angiotensin converting enzyme (ACE) inhibitors on angiotensin II (Ang II) induced growth related signalling pathways in neonatal rat cardiac fibroblasts. In BrdU proliferation assays, Ang II (10–9–10–7 M) stimulated cardiac fibroblast growth in a dose-dependent fashion (maximum at 10–7 M, 5.22 ± 0.01-fold, n = 9). 2-2-(1-(ethoxycarbonyl)-3-phenylpropyl)-[amino-oxopropyl]-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline-3 carboxylic acid (moexiprilat) led to a dose-dependent inhibition of the Ang II induced cardiac fibroblast growth. A less pronounced effect on cellular proliferation was seen with the ACE inhibitor enalaprilat. To elucidate the mechanisms involved in this direct antiproliferative effect of ACE inhibitors in cardiac fibroblasts, we studied the activation of mitogen-activated protein kinases [MAPKs: extracellular signal-regulated kinases 1 and 2 (ERK1/2) and p38-MAPK] and JAK/STAT (janus kinases/signal transducer and activator of transcription) signal transduction pathways. Ang II (10–7 M) caused an increase in MAPKs activity with an increased phosphorylation of ERK1/2 (1.7-fold) and p38-MAPK (3.6-fold). This effect was completely inhibited by moexiprilat (10–7 M) and enalaprilat (10–7 M). Stimulation with Ang II (10–7 M) also led to an increased phosphorylation of STAT3, which is one of the key effector proteins in the JAK/STAT signalling pathway. This effect was also completely inhibited by moexiprilat (10–7 M) and enalaprilat (10–7 M). These data show that the ACE inhibitors moexiprilat and enalaprilat inhibit Ang II induced proliferation of cardiac fibroblasts according to their relative potency of ACE inhibition in vitro. This novel effect of ACE inhibitors is accompanied by blocking the Ang II induced activation of several intracellular signal transduction pathways (ERK1/2, p38-MAPK and STAT3).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00005366
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  • 7
    Electronic Resource
    Electronic Resource
    Transcatheter Radiofrequency Ablation for Congenital Junctional Ectopic Tachycardia in Infancy (1997)
    Springer
    Pediatric cardiology 18 (1997), S. 447-450 
    Details
    ISSN: 1432-1971
    Keywords: Key words: Radiofrequency ablation — Congenital junctional ectopic tachycardia — Pediatric arrhythmia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Congenital junctional ectopic tachycardia (JET) is a difficult to treat arrhythmia with a variably poor response to pharmacologic intervention. We report on the successful treatment of a 17-day-old infant with JET via transcatheter radiofrequency ablation of the arrhythmogenic focus resulting in resolution of the tachycardia and maintenance of normal atrioventricular nodal function. Transcatheter radiofrequency ablation techniques should be considered in infants with life-threatening arrhythmia recalcitrant to standard forms of drug therapy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002469900228
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  • 8
    Electronic Resource
    Electronic Resource
    Lung Perfusion Patterns After Bidirectional Cavopulmonary Anastomosis (Hemi-Fontan Procedure) (1997)
    Springer
    Pediatric cardiology 18 (1997), S. 191 -196 
    Details
    ISSN: 1432-1971
    Keywords: Key words: Lung perfusion — Bidirectional cavopulmonary anastomosis (hemi-Fontan procedure)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Perfusion lung scans were performed immediately prior to Fontan procedure in 45 patients with a functional single ventricle who underwent the hemi-Fontan procedure as an intermediate stage between the initial palliative shunt procedure and the final complete Fontan anastomosis. Symmetric pulmonary blood flow (PBF) distribution was found in 27% of patients, whereas moderately to severely abnormal PBF distribution was found in 35% of patients. The achieved systemic aortic saturation following the hemi-Fontan procedure was not affected by these abnormalities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002469900146
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  • 9
    Electronic Resource
    Electronic Resource
    High CO2 content of fluid inclusions in gold mineralisations in the Ashanti Belt, Ghana: a new category of ore forming fluids? (1997)
    Springer
    Mineralium deposita 32 (1997), S. 107-118 
    Details
    ISSN: 1432-1866
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Fluid inclusions were studied in samples from the Ashanti, Konongo-Southern Cross, Prestea, Abosso/Damang and Ayanfuri gold deposits in the Ashanti Belt, Ghana. Primary fluid inclusions in quartz from mineralised veins of the Ashanti, Prestea, Konongo-Southern Cross, and Abosso/Damang deposits contain almost exclusively volatile species. The primary setting of the gaseous (i.e. the fluid components CO2, CH4 and N2) fluid inclusions in clusters and intragranular trails suggests that they represent the mineralising fluids. Microthermometric and Raman spectroscopic analyses of the inclusions revealed a CO2 dominated fluid with variable contents of N2 and traces of CH4. Water content of most inclusions is below the detection limits of the respective methods used. Aqueous inclusions are rare in all samples with the exception of those from the granite-hosted Ayanfuri mineralisation. Here inclusions associated with the gold mineralisation contain a low salinity (〈6 eq.wt.% NaCl) aqueous solution with variable quantities of CO2. Microthermometric investigations revealed densities of the gaseous inclusions of 0.65 to 1.06 g/cm3 at Ashanti, 0.85 to 0.98 g/cm3 at Prestea, up to 1.02 g/cm3 at Konongo-Southern Cross, and 0.8 to 1.0 g/cm3 at Abosso/Damang. The fluid inclusion data are used to outline the PT ranges of gold mineralisation of the respective gold deposits. The high density gaseous inclusions found in the auriferous quartz at Ashanti and Prestea imply rather high pressure trapping conditions of up to 5.4 kbar. In contrast, mineralisation at Ayanfuri and Abosso/Damang is inferred to have occurred at lower pressures of only up to 2.2 kbar. Mesothermal gold mineralisation is generally regarded to have formed from fluids characterized by H2O 〉 CO2 and low salinity ( ±  6 eq.wt.%NaCl). However, fluid inclusions in quartz from the gold mineralisations in the Ashanti belt point to distinctly different fluid compositions. Specifically, the predominance of CO2 and CO2 〉〉 H2O have to be emphasized. Fluid systems with this unique bulk composition were apparently active over more than 200␣km along strike of the Ashanti belt. Fluids rich in CO2 may present a hitherto unrecognised new category of ore-forming fluids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001260050078
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  • 10
    Electronic Resource
    Electronic Resource
    Life-history patterns of two Southern CaliforniaNebalia species (Crustacea: Leptostraca): the failure of form to predict function (1996)
    Springer
    Marine biology 127 (1996), S. 131-141 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Laboratory and field studies onNebalia hessleri andN. daytoni off the toast of San Diego, Southern California, showed that although morphologically similar, the habitats, behavior, and natural history of these two species are surprisingly different. In laboratory experiments, Bach species avoided the other's habitat (sand and mats of macrophyte detritus), and in the field, transplanted individuals failed to survive in the other species' habitat.N. hessleri, which inhabits subtidal mats of macrophyte detritus, survived and reproduced well in the laboratory, was iteroparous, and a large percentage of adults were male. This species occurred at very high densities in the field, and ate essentially everything offered in the laboratory, with a diet in the field consisting largely of plant detritus and carrion. The other species,N. daytoni, differed in nearly every way, it inhabited organically impoverished sands, survived poorly in the laboratory, was apparently semelparous, and a small percentage of the adult population was male.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00993653
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