Search

Your search keyword '"Hafner, D"' showing total 415 results
Start Over Author "Hafner, D"
415 results on '"Hafner, D"'

112. Elektrophysiologische Wirkungen von K+ und Mg2+ im Hypoxiemodell.

Author

Borchard, U., Berger, F., Hafner, D., Hermsen, D., and Picker, O.

Abstract

Copyright of Herz is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
1997
Full Text
View/download PDF

114. Classification and action of antiarrhythmic drugs.

Author

Borchard, U., Berger, F., and Hafner, D.

Abstract

A great number of antiarrhythmic drugs is available for the treatment of tachyarrhythmias. The classiffication of these drugs according to their action on different ionic channels of cardiac cells is discussed and summarized. Furthermore, drugs are characterized with respect to their mechanism of action on membrane currents and their action in different cardiac tissues. From the results, strategies may be developed which represent the basis for clinical application of antiarrhythmic drugs. [ABSTRACT FROM PUBLISHER]

Published
1989
Full Text
View/download PDF

115. The pharmacokinetics of ticarcillin/clavulanate acid in neonates.

Author

Fricke, G., Doerck, M., Hafner, D., Horton, R., and Kresken, M.

Abstract

The pharmacokinetics of a 25:1 combination of ticarcillin and clavulanate were studied in nine pre-term and seven full-term neonates. Pre-term neonates with a gestational age ranging from 30 to 36 weeks received 83.3 mg of ticarcillin and 3.3 mg of clavulanate per kg bw and full-term neonates with a gestational age from 39 to 43 weeks received 100 mg of ticarcillin and 4 mg of clavulanate per kg bw 8-hourly, each by a slow infusion over 10 min. Serum was sampled 15, 30, 60, 120, 240 and 480 min after the first dose and trough samples were additionally obtained on the fourth day of treatment The patients were allocated to Groups 1–3 on the basis of the pharmacokinetic characteristics obtained. Group 1 comprised seven full-term babies. Group 2 contained seven pre-term neonates with a birth weight between 1915 and 2650 g and Group 3 consisted of two pre-term neonates of low birth weight (1400 g and 1640 g). Mean (± s.e.) pharmacokinetic characteristics of Group 1 patients for ticarcillin were: Cmax = 404.9 mg/1 (36.0); T½= 2.68 h (0.23); AUC = 1287 h.mg/1 (69); Vd =266 ml/kg (28) and for clavulanate: Cmax = 15.0 mg/1 (1.2); T½=1.39 h (0.12); AUC= 30.1 h.mg/1 (1.7); Vd = 263 ml/kg (22). Corresponding parameters for Group 2 patients for ticarcillin were: Cmax 278.7 mg/1 (304); T½ = 4.20 h (0.49); AUC = 1107 h.mg/1 (57); Vd = 338 ml/kg (35) and for clavulanate: Cmax = 8.4 mg/1 (0.56); T½ = 2.56 h (0.18); AUC = 271 h.mg/1 (20); Vd = 414 ml/kg (29). Drug accumulation was not observed in patients of Groups 1 and 2. Each of the two patients of Group 3 presented a pharmacokinetic profile which was considerably different from those observed in Groups 1 and 2. While in patients of the latter group the peak serum concentrations were achieved at 15–30 min after the end of infusion, these concentrations occurred between 120 and 240 min in one of the Group 3 patients. In the other Group 3 patient a remarkable drug accumulation was noted but was not associated with clinical or laboratory evidence of toxicity. These data show that ticarcillin and clavulanic acid in these dose ranges achieved adequate peak and trough concentrations in pre-term and full-term neonates. [ABSTRACT FROM PUBLISHER]

Published
1989

127. H1-receptor reserves in guinea-pig left atria, trachea and pig coronary artery as identified by phenoxybenzamine

Author

Rappen-Cremer, E., Borchard, U., Hafner, D., and Berger, F.

Abstract

H1-receptor reserves in guinea-pig left atria, trachea and pig coronary arteries were calculated by the use of phenoxybenzamine (Pba), a β-haloalkylamine that irreversibly blocks the H1-receptor response to histamine or 2-(2-pyridyl)-ethylamine (PEA). Equieffective concentrations of the H1-agonist in the absence (A) and presence (A′) of Pba were evaluated from concentration-response curves. By plotting the reciprocal values 1/A versus 1/A′ the amount of H1-receptors not occupied by the agonist was calculated. The size of the H1-receptor reserve could be estimated by comparison of the receptor occupation with the corresponding effect. Furthermore, the dissociation constants for histamine, PEA, Pba and the pD′2-values for Pba were determined for the different tissues. 5% and 6% H1-receptor occupation is necessary to achieve a half maximal contraction of the trachea with the agonists histamine and PEA, respectively. Only 0.5% H1-receptor occupation is needed for the half maximal positiv inotropic effect of histamine in left atria, while 5.5% of the H1-receptors have to be accupied using PEA as an agonist in this tissue. In the coronary artery of the pig 50% of the maximal contraction can be achieved by stimulation of 15.1% of the H1-receptors with histamine.

Published
1989
Full Text
View/download PDF

128. Inhibition of pacemaker current by the bradycardic agent ZD 7288 is lost use-dependently in sheep cardiac Purkinje fibres

Author

Berger, F., Borchard, U., Gelhaar, R., Hafner, D., and Weis, T.M.

Abstract

The inhibition of the pacemaker current (if) in sheep cardiac Purkinje fibres by ZD 7288 [4-(N-ethyl-N-phenylamino)-1,2-dimethyl-6-(methylamino)pyrimidinium chloride] is lost use-dependently. This disinhibition of if was investigated by using the two-microelectrode voltage-clamp technique. The pulse protocol consisted of a rest period (holding potential of about -50 mV, 1–10 µmol/l ZD 7288) followed by a train of test pulses (potential negative to -100 mV, stimulation frequency 0.05 Hz). At the beginning of the first test pulse there was an immediate reduction of if but inhibition was lost during continued stimulation. Activation of if is sigmoidal and the early delay in current activation was prolonged from 33 ms (no ZD 7288) to 424 ms (10 µmol/l ZD 7288). Therefore hardly any disinhibition occurred during short test pulses (0.5 s). During longer test pulses (5 s, -120 mV, 10 µmol/l) disinhibition developed with a time constant of about 2 s. The inhibition of if by ZD 7288 was lost voltage-dependently. With 10 µmol/l ZD 7288 the half-maximal disinhibition occurred at -92 mV and the slope factor of the disinhibition/voltage curve (Boltzmann relation) was 4.8 mV. The voltage-dependent disinhibition could be abolished largely by extracellular application of protease (0.5 mg/ml, 7 min). After prior disinhibition, reinhibition at the holding potential (about -50 mV) followed a bi-exponential time course indicating that inhibition may be produced by a fast (t=0.7 min) and a slow component (t=20–30 min). Increasing ZD 7288 concentration from 1 to 10 µmol/l accelerated reinhibition, mainly by an increase of the amplitude (A) of the fast component. The ratio Afast/AsIow was 0.399 at 1 µmol/l and 2.65 at 10 µmol/1 ZD 7288. The reinhibition of if was unchanged by shifting the holding potential from -50 mV to -20 mV Trials to wash out the effects of 10 µmol/l ZD 7288 gave two results. The inhibition of if was slightly reversed after a wash-out of 1.5 h with drug-free solution. A second effect of the drug, the fast reinhibition, could be completely removed by washout. In summary if is inhibited by ZD 7288 at membrane potentials at which the virtual if gate is closed. Disinhibition occurs during long-lasting hyperpolarization but will hardly be operative in unclamped fibres under physiological conditions.

Published
1995
Full Text
View/download PDF

132. MAGIC contributions to the 32nd International Cosmic Ray Conference

Author

Aleksic, J., Alvarez, E. A., Antonelli, L. A., Antoranz, P., Asensio, M., Backes, M., Barrio, J. A., Bastieri, D., Becerra Gonzalez, J., Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Borla Tridon, D., Braun, I., Bretz, T., Canellas, A., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Dazzi, F., Angelis, A., Caneva, G., Cea Del Pozo, E., Lotto, B., Delgado Mendez, C., Diago Ortega, A., Doert, M., Dominguez, A., Dominis Prester, D., Dorner, D., Doro, M., Eisenacher, D., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., Lopez, R. J. Garcia, Garczarczyk, M., Garrido, D., Giavitto, G., Godinovic, N., Hadasch, D., Hafner, D., Herrero, A., Hildebrand, D., Hohne-Monch, D., Hose, J., Hrupec, D., Jogler, T., Kellermann, H., Klepser, S., Krahenbuhl, T., Krause, J., Kushida, J., La Barbera, A., Lelas, D., Leonardo, E., Lindfors, E., Lombardi, S., Lopez, M., Lopez-Oramas, A., Lorenz, E., Makariev, M., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martinez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Moldon, J., Moralejo, A., Munar-Adrover, P., Nieto, D., Nilsson, K., Orito, R., Otte, N., Oya, I., Paneque, D., Paoletti, R., Pardo, S., Paredes, J. M., Partini, S., Perez-Torres, M. A., Persic, M., Peruzzo, L., Pilia, M., Pochon, J., Prada, F., Prada Moroni, P. G., Elisa Prandini, Gimenez, I. Puerto, Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribo, M., Rico, J., Rissi, M., Rugamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, S. N., Sillanpaa, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Spiro, S., Stamatescu, V., Stamerra, A., Steinke, B., Storz, J., Strah, N., Suric, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzic, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Treves, A., Uellenbeck, M., Vankov, H., Vogler, P., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., and Zanin, R.

133. Information is Power: Intrinsic Control via Information Capture

Author

Nicholas Rhinehart, Wang, J., Berseth, G., Co-Reyes, J. D., Hafner, D., Finn, C., and Levine, S.

Subjects
FOS: Computer and information sciences, Computer Science - Machine Learning, Artificial Intelligence (cs.AI), Computer Science - Artificial Intelligence, Machine Learning (cs.LG)
Abstract

Humans and animals explore their environment and acquire useful skills even in the absence of clear goals, exhibiting intrinsic motivation. The study of intrinsic motivation in artificial agents is concerned with the following question: what is a good general-purpose objective for an agent? We study this question in dynamic partially-observed environments, and argue that a compact and general learning objective is to minimize the entropy of the agent's state visitation estimated using a latent state-space model. This objective induces an agent to both gather information about its environment, corresponding to reducing uncertainty, and to gain control over its environment, corresponding to reducing the unpredictability of future world states. We instantiate this approach as a deep reinforcement learning agent equipped with a deep variational Bayes filter. We find that our agent learns to discover, represent, and exercise control of dynamic objects in a variety of partially-observed environments sensed with visual observations without extrinsic reward., Comment: NeurIPS 2021

134. VizieR Online Data Catalog: MAGIC map of 1E 2259+586 (Aleksic+, 2013)

Author

Aleksic, J., Antonelli, L. A., Antoranz, P., Asensio, M., Barres Almeida, U., Barrio, J. A., Becerra Gonzalez, J., Bednarek, W., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Borla Tridon, D., Thomas Bretz, Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Da Vela, P., Dazzi, F., Angelis, A., Caneva, G., Cea Del Pozo, E., Lotto, B., Delgado Mendez, C., Diago Ortega, A., Doert, M., Dominis Prester, D., Dorner, D., Doro, M., Eisenacher, D., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., Garcia Lopez, R. J., Garczarczyk, M., Garrido Terrats, D., Gaug, M., Giavitto, G., Godinovic, N., Gonzalez Munoz, A., Gozzini, S. R., Hadamek, A., Hadasch, D., Hafner, D., Herrero, A., Hose, J., Hrupec, D., Huber, B., Jankowski, F., Jogler, T., Kadenius, V., Klepser, S., Knoetig, M. L., Krahenbuhl, T., Krause, J., Kushida, J., La Barbera, A., Lelas, D., Leonardo, E., Lewandowska, N., Lindfors, E., Lombardi, S., Lopez, M., Lopez-Coto, R., Lopez-Oramas, A., L Orenz, E., Makariev, M., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martinez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Moldon, J., Moralejo, A., Munar-Adrover, P., Niedzwiecki, A., Nieto, D., Nilsson, K., Nowak, N., Orito, R., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Partini, S., Persic, M., Pilia, M., Pochon, J., Prada, F., Prada Moroni, P. G., Prandini, E., Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribo, M., Rico, J., Rugamer, S., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Saggion, A., Schweizer, T., Shore, S. N., Sillanpaa, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Spiro, S., Stamatescu, V., Stamerra, A., Steinke, B., Storz, J., Sun, S., Suric, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzic, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Uellenbeck, M., Vogler, P., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., Zanin, R., and Rea, N.

Catalog

Books, media, physical & digital resources
See catalog results