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  • Digitale Medien  (17)
  • 1980-1984  (4)
  • 1970-1974  (12)
  • 1890-1899  (1)
  • 1
    Digitale Medien
    Digitale Medien
    An experimental investigation of the pressure and concentration dependence of muonic Coulomb capture and cascade in gases (1983)
    Springer
    The European physical journal 311 (1983), S. 259-266 
    Details
    ISSN: 1434-601X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Muonic Coulomb capture ratios and x-ray intensity patterns in four binary mixtures of the gases N2, Ne, Ar, Kr, and Xe have been measured at three atomic ratios. An influence of the concentration has been established. The Lyman series intensity patterns of pure N2, Ne, Ar, Kr, and Xe were measured at pressures between 0.4 and 51 bar and found to depend on the pressure. Possible explanations are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01415679
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  • 2
    Digitale Medien
    Digitale Medien
    Growth kinetics of mammalian embryos during the stage of differentiation (1972)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 272 (1972), S. 169-181 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Embryonic Growth ; DNA ; RNA ; Nuclei
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In order to get insight into the synthesis rates occuring in mammalian embryos during the phase of differentiation, wet and dry weight as well as DNA-, RNA-, and nitrogen content of the whole implantation site (day 7 to 10 of gestation) and of the embryos (day 11 to 14) have been determined. Growth of the whole implantation site (day 7 to 10) proceeds almost linearly: Within a 24-h period the weight increases about 2-fold. The growth of the embryos, however, is found to be different in each 24-h period between day 8 and 14. All synthesis processes proceed at an extremely rapid rate between day 9 and 12 of gestation. The weight of embryos shows a 6-fold rise between day 11 and 12, the increase being even more pronounced on the preceding days. Growth and increase in cell mass are essentially due to cell division, since DNA content and weight change in a parallel way. Data on the nitrogen content per embryo show that the protein synthesis keeps pace with the rapid cell division. Using pure nuclear fractions isolated from 11- to 14-day-old embryos the average distribution of RNA within the cells can be estimated. The increase in the number of cells within a 24-h period is calculated from the average DNA content per embryo and the average DNA content per nucleus measured in isolated nuclei. The DNA content per nucleus of 12- to 14-day-old rat embryos is found to be almost twice (12±0.5 pg) that of diploid nuclei (6.7–7.2 pg). This inducates that a high percentage of the cells are in the late S-phase or in the G2-phase. The growth rate of the embryos between day 8 and 14 of gestation is calculated from the 24-h rate of increase in cell number which is obtained either biochemically or in the earlier stage of embryonic development with morphological studies. Some peculiarities of the duration of the cell cycle of the rapidly growing tissue are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00508767
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  • 3
    Digitale Medien
    Digitale Medien
    Effect of cyclophosphamide pretreatment of pregnant animals on the activity of nuclear DNA-dependent RNA-polymerases in different parts of rat embryos (1973)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 277 (1973), S. 71-88 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Cyclophosphamide ; Embryonic Development ; DNA-Dependent RNA Polymerases
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary On day 13+0 h of gestation rats received 10 mg/kg cyclophosphamide i.p. 3, 9, and 24 h after administration of the drug the activities of the DNA-dependent RNA polymerase reactions were measured in the whole embryo and in parts of it (head, upper and lower extremities and trunk). The activities of these enzymes were correlated with the increase in the RNA content of these tissues. A relationship was established light and electron microscopically between the biochemical results and the specific alterations which occur in different structures of the embryonic tissue. The results of these investigations show that: 1. cyclophosphamide leads-in dependency on the time-to a decrease or increase in the Mn++- and/or Mg++-stimulated RNA polymerase reactions in isolated cell nuclei of individual parts of the embryo 2. alterations in the enzyme activities of individual parts of the embryo are not detected when the enzyme activity of the whole embryo is measured at the early day 13 of gestation 3. towards the end of gestation malformations can be demonstrated only in those parts of the embryo, where 24 h after the administration of cyclophosphamide the enzyme pattern shows a highly significant deviation from that of the controls and where cell necroses can be demonstrated light and electron microscopically. Moreover, in the nucleolus of the neuroepithelium segregation of its components takes place which correlates well with the decreased r-RNA polymerase activity. In this paper a disturbance of the transcription mechanisms is discussed as being the primary mode of action of cyclophosphamide in cell metabolism.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00498786
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  • 4
    Digitale Medien
    Digitale Medien
    Correlated changes in neuronal cerebral rat brain RNA synthesis and hypo- and hypermotoric disorders induced by 6-aminonicotinamide (6-AN) (1980)
    Springer
    Experimental brain research 38 (1980), S. 173-179 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Neuronal cerebral and cerebellar RNA synthesis ; Motor activity ; RNA initiation sites
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The nicotinamide antagonist 6-aminonicotinamide (6-AN) administered to rats prior to the second postnatal week drastically affected their motoric activity by producing consecutive reversible hypo- and hypermotoric stages. To obtain information on the validity of the putative link of correlated changes in brain RNA synthesis and motoric activity, neuronal and nonastrocytic glial cerebral and cerebellar in vitro RNA synthesis was determined during the hypo- and hypermotoric stages induced by in vivo administration of 6-AN given on the 7th day of a rat's life. Significant changes were apparent in the rate of neuronal cerebral and cerebellar RNA synthesis coinciding with the different phases of motor activity. However, only the changes in neuronal cerebral RNA synthesis were directly proportional to the changing pattern of motor activity. Measurement of the total number of RNA initiation sites present in neuronal cerebral chromatin, which was isolated during the phase of reduced and elevated muscular activity, revealed that the drug-induced changes in neuronal cerebral RNA synthesis could be directly attributed to a genetically repressed or activated state of the corresponding neuronal chromatin fraction. Nevertheless, although there was evidence suggesting a connection between changes in neuronal cerebral RNA synthesis and corresponding changes in muscular activity it was difficult to deduce any direct relationship between parameters owing to the absence of a convincing biological assay for assessing the role of RNA in motor function.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00236738
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  • 5
    Digitale Medien
    Digitale Medien
    Effect of respiratory acidosis on heart and circulation in cats, pigs, dogs and rabbits (1972)
    Springer
    Research in experimental medicine 158 (1972), S. 308-320 
    Details
    ISSN: 1433-8580
    Schlagwort(e): Respiratory Acidosis ; Cardiovascular Effects ; Sympathomimetic Amines ; Species Differences ; Respiratorische Acidose ; Kreislauf ; Sympathomimetica ; Speciesunterschiede
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung An Katzen, Hunden, Kaninchen und Hausschweinen wurden in Pentobarbitalnarkose nach Muskelrelaxation mit Alloferin® bei geschlossenem Thorax die Auswirkungen einer akuten respiratorischen Acidose auf den Kreislauf sowie dessen Reaktion auf Pharmaka untersucht. 1. BeiKatzen undSchweinen steigen in respiratorischer Acidose Herzfrequenz, dp/dtmax und Blutdruck an; beiKaninchen bleiben dp/dtmax und Blutdruck nahezu unverändert. BeiHunden hingegen sinken Schlagfrequenz, dp/dtmax und Blutdruck in Acidose ab. Untersuchungen an Katzen, die mit Reserpin vorbehandelt waren, zeigten, daß eine respiratorische Acidose einen negativ inotropen und blutdrucksenkenden Eigeneffekt besitzt. Nach Vorbehandlung mit Phenoxybenzamin verursacht eine respiratorische Acidose bei Katzen einen Blutdruckabfall sowie einen Anstieg von dp/dtmax. Nach Vorbehandlung mit Pindolol verursacht eine Acidose eine Abnahme von Frequenz und dp/dtmax, während der Blutdruck konstant bleibt. Am unvorbehandelten Tier wird der negativ inotrope Effekt einer Acidose offenbar durch eine Stimulierung des sympathischen Nervensystems überdeckt, die bei Katzen und Schweinen am ausgeprägtesten ist. 2. DieWirkung sympathomimetischer Amine auf Herz und Kreislauf ist bei allen 4 untersuchten Tierarten in Acidose abgeschwächt, wobei die Abschwächung bei den Tieren mit der stärksten sympathischen Stimulation am ausgeprägtesten ist. 3. Biochemische Untersuchungen an Hunden und Katzen ergaben, daß in Acidose K+, Mg2+, anorganisches Phosphat und Glucose im Serum ansteigen, während der Magnesiumgehalt des Herzmuskels abnimmt.
    Notizen: Summary In closed chest cats, dogs, rabbits and pigs, anaesthetized with pentobarbital and relaxed with diallylnortoxiferinium dichloride the effects of a respiratory acidosis on heart and circulation as well as their reaction to sympathomimetic amines were studied. 1. Incats andpigs a respiratory acidosis causes a rise of frequency, dp/dtmax of the left ventricle and systolic blood-pressure. Inrabbits an acidosis causes no significant alteration of blood-pressure and dp/dtmax. Indogs frequency, dp/dtmax and blood-pressure decline in acidosis. In cats pretreated withreserpine a respiratory acidosis causes a negative inotropic effect and a declining of blood-pressure. After pretreating cats withphenoxybenzamine in acidosis there results a decrease of blood-pressure, but a rise of dp/dtmax and frequency; after pretreating withpindolol in acidosis dp/dtmax and frequency decline, but blood-pressure remains unaltered. 2. The effectiveness of sympathomimetic amines on heart and circulation is diminished in acidosis. This diminution is most significant in those animals (cat, pig) with the most augmented sympathetic tonus in acidosis, but experiments performed with reserpinized cats indicated that the augmented sympathetic tonus can not be the only cause for the diminished efficiency of adrenergic stimulant amines in acidosis. 3. Biochemical studies performed in acidosis showed a rise of K+, Mg2+, inorganic phosphate and glucose in serum and a decrease of Mg2+ in the heart muscle.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01852214
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  • 6
    Digitale Medien
    Digitale Medien
    Der Einfluß des Blut-pH auf die Toxicität herzwirksamer Glykoside (1972)
    Springer
    Research in experimental medicine 159 (1972), S. 65-74 
    Details
    ISSN: 1433-8580
    Schlagwort(e): Cardioactive glycosides ; Respiratory acidosis ; Alcalosis ; β-sympatholytic drugs ; Herzwirksame Glykoside ; Respiratorische Acidose ; Alkalose ; β-Sympathicolytica
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung An narkotisierten Katzen wurde der Einfluß des Blut-pH auf die Toxicität herzwirksamer Glykoside untersucht. An isolierten Vorhofpräparaten wurden in Ergänzung hierzu Versuche mit Änderung des pH der Tyrodelösung durchgeführt. 1. An Katzen wird durch eine respiratorische Acidose (pH 7,0) die Toxicität des Digitoxins, Digoxins und k-Strophanthins signifikant erhöht; dabei ist die Toxicität des Digitoxins stärker erhöht als die des Digoxins und k-Strophanthins. 2. Vorbehandlung mit Reserpin oder Practolol vermindert die Toxicität des Digitoxins in Acidose wesentlich stärker als bei normalem pH. 3. Eine durch Tris-Infusion erzeugte Alkalose von pH 7,6 bewirkt keine Änderung, eine durch Infusion von NaHCO3 erzeugte Alkalose von pH 7,6 verursacht eine geringfügige Steigerung der Digitoxintoxicität. 4. Am isolierten Vorhofpräparat des Meerschweinchens ist die Toxicität des Digitoxins, Digoxins und k-Strophanthins bei pH-Werten der Tyrodelösung von 7,0 und 7,8 nicht signifikant verschieden.
    Notizen: Summary In anaesthetized cats the influence of blood-pH on the toxicity of cardiac glycosides was studied. In isolated guinea pigs atrias further experiments were performed by changing the pH of the tyrode solution. 1. In cats with respiratory acidosis (pH 7.0) the toxicity of digitoxin, digoxin and k-strophanthin is enhanced — thereby the toxicity of digitoxin is more enhanced than that of digoxin and k-strophanthin. 2. Pretreatment with reserpine or practolol diminishes the toxicity of digitoxin in acidosis more than at normal blood-pH. 3. An alcalosis of pH 7.6, produced by the infusion of tris causes no change, an alcalosis of pH 7.6 produced by the infusion of NaHCO3 causes a small increase of the toxicity of digitoxin. 4. In the isolated guinea pigs atria the toxicity of digitoxin, digoxin and kstrophanthin is not different at pH 7.0 and 7.8 of the tyrode solution.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01852143
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  • 7
    Digitale Medien
    Digitale Medien
    Activity of some enzymes of nucleic acid metabolism in developing rat liver (1972)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 274 (1972), S. 385-393 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Liver Development ; Thymidine Kinase ; DNA Polymerase ; RNA Polymerases
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The increase in DNA, RNA, and nitrogen as well as the activity of some enzymes involved in nucleic acid metabolism were measured during liver development. During the perinatal period (day 18 of gestation until birth) high activities of thymidine kinase and DNA polymerase were found which decline in the early suckling period, whereas the activities of the DNA-dependent RNA polymerases show a slow continuous increase. During the juvenile period (starting about 4 weeks after birth) the values of all enzymes studied approximate to those measured in liver tissue of adult animals. The correlation of these enzymes with the growth kinetics of liver tissue is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00501275
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  • 8
    Digitale Medien
    Digitale Medien
    Studies on the problem of “aerobic glycolysis” occuring in mammalian embryos (1971)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 268 (1971), S. 235-241 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Aerobic Glycolysis ; Embryonic Metabolism ; Glucose Metabolism ; Aerobe Glykolyse ; Stoffwechsel embryonalen Gewebes ; Glucose-Stoffwechsel
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01020078
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  • 9
    Digitale Medien
    Digitale Medien
    Studies on the teratogenic phase specificity of actinomycin D in the rat (1972)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 275 (1972), S. 31-44 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Embryonic Development ; Actinomycin D ; DNA-dependent RNA Polymerases
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In order to elucidate the phase specificity of the embryo-lethal and teratogenic action of actinomycin D (day 5–10 of gestation) rats received 3H-actinomycin D at different times of gestation. The distribution of the radioactivity in the fetus and the placenta was measured. Moreover, the effects of actinomycin D on the RNA polymerase reactions in isolated nuclei of the decidual and fetal tissue were studied. The biochemical results were correlated electron microscopically with specific alterations occurring in different structures of the total implantation sites. These studies show that the time-dependent embryo-lethal and teratogenic effects of actinomycin D result from a lesion of the embryo and the decidua. The effects of the decidua occur at an earlier time and are more pronounced as compared to those of the embryo. Since the decidua is significant for the nutrition of the embryo till closure of the yolk-sac and beginning of the yolk-sac circulation (day 10 of gestation), the direct effects of actinomycin D on the embryo are intensified by the lesion of the decidua. After day 10 of gestation till the beginning of the placental function 3H-actinomycin D passes over to the embryo. But the concentration-even after a dose of 1 mg/kg-does not suffice to inhibit in vivo RNA polymerase reactions in isolated nuclei.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00505066
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  • 10
    Digitale Medien
    Digitale Medien
    Influence of steroid replacement therapy on rat embryos of hypophysectomised mother animals (1971)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 271 (1971), S. 103-110 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Embryonic Development ; DNA Polymerase ; Hypophysectomy ; Sex Hormones
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The effects of estrone plus progesterone on embryonic survival were studied in hypophysectomised pregnant rats. Replacement therapy commenced 24 h prior to the ablation of the pituitary which was performed on day 6 of pregnancy. The number of viable fetuses was correlated with increasing amounts of progesterone from 24 to 84 mg/kg given in concert with a constant dose of 4 μg/kg estrone. As judged by the DNA content of the 14-day-old embryos, growth retardation was linked to the reduction of the progesterone levels. No visible malformations were recorded although the experimental period covered the phase of organogenesis. On the other hand, when measuring in isolated nuclei of 14-day-old rat embryos the activity of DNA polymerase, an enzyme the activity of which can be correlated to a certain extent to embryonic growth, it becomes obvious that after treatment with estrone in combination with low (24 or 36 mg/kg) or too high doses (84 mg/kg) of progesterone the correlation between DNA content of the embryos and DNA polymerase activity per cell diverges. This result may point to a cellular malfunction not disclosed by the macroscopic appearance of the embryos at this stage. So it can be concluded that embryonic growth and differentiation processes might be directly dependent on maternal gonadal hormones, at least till day 12 of pregnancy.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01002175
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