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  • man  (5)
  • Positron annihilation  (3)
  • Springer  (8)
  • 2005-2009
  • 1985-1989
  • 1980-1984
  • 1975-1979  (8)
  • 1965-1969
  • 1975  (8)
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  • Springer  (8)
Years
  • 2005-2009
  • 1985-1989
  • 1980-1984
  • 1975-1979  (8)
  • 1965-1969
Year
  • 1
    Electronic Resource
    Electronic Resource
    Positron decay in polymers: Molecular weight dependence in polystyrene (1975)
    Springer
    Applied physics 7 (1975), S. 171-174 
    Details
    ISSN: 1432-0630
    Keywords: Positron annihilation ; Polymers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The decay time τl ofo-Ps by the electron pickoff process has been measured in polystyrene as a function of molecular weight. For samples below their glass transition temperature τl is essentially independent of $$\bar M_n $$ . In the low molecular weight region, $$\bar M_n〈 850$$ , τl increased with decreasing $$\bar M_n $$ in line with earlier theoretical predictions. The overall behaviour reflects closely the dependence of free volume on $$\bar M_n $$ . The effects of molecular motion on τl are examined and it is concluded that the decay time is insensitive to such motions in polystyrene below the melting point, in contrast to what is observed in polytetrafluoroethylene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00936020
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  • 2
    Electronic Resource
    Electronic Resource
    First measurements of positronium total scattering cross sections (1975)
    Springer
    Applied physics 5 (1975), S. 383-384 
    Details
    ISSN: 1432-0630
    Keywords: Positron annihilation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A new type of experiment has been devised in which ortho-positronium diffusion to the metal walls of a series of parallel-sided cells is studied by measuring the annihilation lifetimes. Experimental results are subjected to an analysis in which two parameters are varied to give a best fit, one of the two parameters being the scattering cross section. The method requires a number of systematic corrections which have still to be worked out. Preliminary cross section values for helium, argon and isobutane are 0.017 πa 0 2 , 0.09 πa 0 2 , and 0.54 πa 0 2 , respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00928029
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  • 3
    Electronic Resource
    Electronic Resource
    Correlation between increased dopamine-β- hydroxylase activity and catecholamine concentration in plasma: Determination of acute changes in sympathetic activity in man (1975)
    Springer
    European journal of clinical pharmacology 8 (1975), S. 181-188 
    Details
    ISSN: 1432-1041
    Keywords: Sympathetic activity ; plasma catecholamine concentration ; dopamine-β-hydroxylase activity ; graded physical exercise ; heart rate ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In 11 healthy untrained volunteers the increase in plasma dopamine-β-hydroxylase (DBH) activity during graded physical exercise has been examined as a true measure of increased activity of the sympathetic nervous system. The correlation between DBH activity, catecholamine concentration (CA) in plasma and heart rate was studied. When work on an electrically braked bicycle ergometer was gradually increased from 12.5 to 100, 200 and 300 watts there was a linear increase in DBH activity and heart rate; the increase in CA concentrations followed an exponential function. The peak values for DBH activity and CA concentration in plasma after the 300 watt work load (as percentages of the resting levels) were 130±3% and 820±71%, respectively; the adrenaline concentration in plasma increased only to 150±19% (p〉0.05). There were significant correlations between heart rate and work load, DBH and work load and log CA and work load. The data imply direct correlations between heart rate and DBH, heart rate and log CA and DBH and log CA. The exponential increase in noradrenaline concentration in plasma might be due either to a greater net “overflow” from sympathetic nerve endings, and/or to increased secretion by the adrenal medulla. In the latter case, the release of noradrenaline would not be accompanied by secretion either of adrenaline or DBH. After work ceased there were sharp falls in heart rate and CA concentration, which indicate an immediate drop in sympathetic activity. DBH activity in plasma returned to normal very slowly; it reached half maximum values after 20 – 22 min. It is concluded that increased sympathetic activity in man can be estimated in vivo as changes in DBH and/or CA concentration in plasma. In contrast, a rapid decrease in sympathetic activity is directly reflected only by a rapid fall in the plasma concentrations of CA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00567112
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  • 4
    Electronic Resource
    Electronic Resource
    Excretion of norephedrine by man after oral administration of oxyfedrine (1975)
    Springer
    European journal of clinical pharmacology 8 (1975), S. 161-166 
    Details
    ISSN: 1432-1041
    Keywords: Oxyfedrine ; norephedrine ; man ; urinary excretion ; sympathomimetic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary After oral administration of oxyfedrine to healthy volunteers, norephedrine was identified in the urine by thin layer chromatography and gas liquid chromatography and mass spectrography. 30 hours after single oral doses of 8, 16 or 24 mg of oxyfedrine, about 4, 8 and 9 mg, respectively, of norephedrine were found in the urine, i.e. on a molar base 75–100% of the dose was excreted as norephedrine. The peak of excretion occurred within 2–4 hours after administration of the drug. No accumulation of oxyfedrine and/or its metabolite was observed after administration of 16 mg of oxyfedrine t.i.d. for three days. It could not be decided whether oxyfedrine was metabolized to norephedrine by liver enzymes, as in rats, or was spontaneously degraded to norephedrine, e.g. in duodenal fluid before absorption. 30–150 min after oral oxyfedrine (24 mg) norephedrine was demonstrable in duodenal fluid. Thus, in addition to the directβ-sympathomimetic effects of oxyfedrine, it may also have indirect sympathomimetic effects because of the noradrenaline-releasing properties of its metabolite norephedrine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00567109
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  • 5
    Electronic Resource
    Electronic Resource
    Induction of drug metabolism in man after rifampicin treatment measured by increased hexobarbital and tolbutamide clearance (1975)
    Springer
    European journal of clinical pharmacology 9 (1975), S. 219-227 
    Details
    ISSN: 1432-1041
    Keywords: Rifampicin ; induction of drug metabolism ; hexobarbital kinetics ; tolbutamide kinetics ; plasma concentrations ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Five healthy volunteers took 1.2 g rifampicin daily for 8 days, and before and afterwards each received hexobarbital (7.32 mg/kg) and tolbutamide (20 mg/kg) by i.v. infusion on two consecutive days. The plasma concentrations of the two drugs were determined during and after infusion. The average elimination half-life of hexobarbital had decreased from 325 to 122 min and of tolbutamide from 418 to 183 min following rifampicin treatment. It was calculated that the metabolic clearance of hexobarbital had increased about three-fold and that of tolbutamide more than two-fold. Significant changes in the distribution kinetics of the two drugs were not observed. The results suggest that rifampicin is capable of inducing drug metabolism in man, which leads to an increased rate of elimination of drugs that undergo biotransformation in the liver.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00614021
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of dixyrazine and methaqualone on the sleep pattern in normal man (1975)
    Springer
    European journal of clinical pharmacology 8 (1975), S. 227-231 
    Details
    ISSN: 1432-1041
    Keywords: Dixyrazine ; methaqualone ; etodroxizine ; Isonox® ; sleep stages ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Whole night EEG and polygraphic recordings were made in ten young, healthy, male volunteers after dixyrazine (12.5 mg, 25 mg, 50 mg), methaqualone (250 mg) and Isonox® (methaqualone 250 mg + etodroxizine 50 mg). A total of 156 recording nights (36 adaptation nights were not included in the analyses) were scored for different sleep stages according to accepted criteria. The smallest dose of dixyrazine (12.5 mg) had no significant effect upon sleep pattern: the larger doses (25 mg and 50 mg) caused significant decreases in REM-sleep during the first nights of administration. The decrease disappeared during the following two nights of treatment. No withdrawal effects were seen. Methaqualone also caused moderate depression of REM-sleep during the first night of treatment, and this effect, too, disappeared during prolonged administration. Isonox® (methaqualone + etodroxizine) had a somewhat stronger surpressive effect upon REM-sleep than methaqualone alone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00567120
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  • 7
    Electronic Resource
    Electronic Resource
    Positron annihilation in ionic crystals (1975)
    Springer
    Applied physics 6 (1975), S. 21-23 
    Details
    ISSN: 1432-0630
    Keywords: Positron annihilation ; Ionic crystals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Positron lifetime measurements were made on Ca2+ doped NaCl, Ba2+ doped NaCl and X-ray- and additively-coloured KCl crystals. In the NaCl(Ca) system a correlation which could be approximated by a power equation was found between the dopant concentration and the positron annihilation parameters. In the NaCl(Ba) system the decay parameters do not change significantly as expected and no significant difference in the decay parameters of the coloured and uncoloured crystals could be found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00883544
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  • 8
    Electronic Resource
    Electronic Resource
    Distribution and elimination kinetics of carbamazepine in man (1975)
    Springer
    European journal of clinical pharmacology 8 (1975), S. 91-96 
    Details
    ISSN: 1432-1041
    Keywords: Carbamazepine ; pharmacokinetics ; man ; diphenylhydantoin ; phenobarbital ; plasma binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Carbamazepine (2.7–3 mg/kg) was administered orally as an alcoholic solution (50% v/v) to eight healthy volunteers. Two of the subjects were also given 50 mg and 100 mg of carbamazepine in alcoholic solution and 200 mg as a tablet. Plasma concentrations, which were analysed by mass fragmentography, reached a maximum 1 – 7 hours after dosing, and then declined monoexponentially with half-lives ranging from 24 to 46 hours. The half-lives were independent of dose. The apparent distribution volume ranged from 0.79 to 1.40 l/kg. It was found that 72% of carbamazepine was bound to plasma proteins with little interindividual variation, and this was not influenced by the presence of diphenylhydantoin or phenobarbital in therapeutic concentrations. The pharmacokinetic parameters calculated from single oral doses were used to predict the steady-state plasma concentration expected after treatment with multiple doses of 200 mg three times daily. The predicted steady-state concentration was 2 – 3 times higher than that reported in patients undergoing chronic treatment with carbamazepine at this dose level, i.e. the pharmacokinetics of carbamazepine apparently change during multiple dosing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00561556
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