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  • 1
    Electronic Resource
    Electronic Resource
    Brain kinetics of 11 C-labelled L-tryptophan and 5-hydroxy-L-tryptophan in the Rhesus monkey (1992)
    Springer
    Journal of neural transmission 88 (1992), S. 1-10 
    Details
    ISSN: 1435-1463
    Keywords: 5-Hydroxy-(β-11 C)-L-tryptophan ; monkey ; positron emission tomography ; enzyme inhibition ; decarboxylation rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 5-Hydroxy-L-tryptophan labelled with 11 C is introduced as a tracer for the in vivo assessment of brain serotonin synthesis in the Rhesus monkey using positron emission tomography, PET. Increasing radioactivities were seen in the striatal area in contrast to that seen in other brain regions. Following 11 C-labelled L-tryptophan an even spread of brain radioactivity was seen. This selective increase most probably results from the decarboxylation of tracer and retention of formed products since no striatal increase of radioactivity was seen when 5-hydroxy-L-tryptophan labelled with 11 C in the carboxy-position was administered. Furthermore, pretreatment of the monkey with a centrally active decarboxylase inhibitor (NSD 1015,10 mg/kg) did not lead to increased striatal radioactivities after the administration of 5-hydroxy-(β-11C)-L-tryptophan. The selective utilization of the radiotracer in the striatal area increased with a rate constant calculated to be 0.0055 ± 0.0015 min−1 (n = 5) using the surrounding brain as reference area. A non-significant influence of radiolabelled metabolites to the rate constants measured was shown after pretreatment of the monkeys with selective and non-selective monoamine oxidase inhibitors, respectively. These results may give a basis for the use of the new tracer 5-hydroxy-(β-11 C)-L-tryptophan in PET-studies of brain serotonin metabolism in health and disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01245032
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  • 2
    Electronic Resource
    Electronic Resource
    Regional brain kinetics of 6-fluoro-(β-11C)-L-dopa and (β-11C)-L-dopa following COMT inhibition. A study in vivo using positron emission tomography (1992)
    Springer
    Journal of neural transmission 87 (1992), S. 15-22 
    Details
    ISSN: 1435-1463
    Keywords: (β-11C)-L-dopa ; 6-fluoro-(β-11C)-L-dopa ; positron emission tomography ; catechol-O-methyl transferase ; monkeys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The regional brain kinetics of (β-11C)-L-dopa and 6-fluoro-(β-11C)-L-dopa was measured in six Rhesus monkeys using positron emission tomography (PET). Radioactivity accumulated specifically in the striatal region and the increase in L-dopa-derived radioactivity utilization with time was calculated using surrounding brain as a reference area, this being devoid of dopaminergic activity. The rate constant for selective striatal utilization i.e. grossly decarboxylation was 0.0110 ± 0.0007 (S.D) and 0.0057 ± 0.0006 min1 for (β-11C)-L-dopa and 6-fluoro-(β-11C)-L-dopa, respectively. After pre-treatment of the monkeys with the peripherally and centrally active catecholamine-O-methyl transferase (COMT) inhibitor Ro 40-7592 10 mg/kg, the decarboxylation rate remained unchanged (0.0112 ± 0.0015 min-1) for (β11C)-L-dopa, whereas an increase in rate was measured for 6-fluoro-(β-11C)L-dopa (0.0092 ± 0.0015 min−1). Differences in the distribution of radiolabelled metabolites i.e. the corresponding O-methyl-L-dopa in the reference area is most probably the reason for the difference in calculated decarboxylation rate seen between the radiotracers. The higher decarboxylation rate measured for 6-fluoro-(β-11C)-L-dopa after blockade of COMT shows that the radiolabelled metabolites i.e. 6-fluoro-O-methyl-(β-11C)-L-dopa significantly contributes to background radioactivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01253107
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  • 3
    Electronic Resource
    Electronic Resource
    Are the effects of noradrenaline, adrenaline and dopamine infusions on $$\dot VO_2 $$ and metabolism transient?and metabolism transient? (1995)
    Springer
    Intensive care medicine 21 (1995), S. 50-56 
    Details
    ISSN: 1432-1238
    Keywords: Noradrenaline ; Adrenaline ; Dopamine ; Oxygen consumption ; Blood pressure ; Heart rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective To determine whether noradrenaline, adrenaline and dopamine have persistent on $$\dot VO_2 $$ and metabolism. Design Descriptive laboratory investigation. Setting Laboratory of the Department of Anaesthesiology at a University Hospital. Subjects 9 volunteers. Intervention $$\dot VO_2 $$ and the plasma concentration of glucose and free fatty acids were measured prior to and during a 4 h infusion of saline (control), noradrenaline (0.14 μg/kg min) adrenaline (0.08 μg/kg min) or dopamine (7 μg/kg min),n=9 each. $$\dot VO_2 $$ was measured using an open circuit gas exchange system. Measurements and main results $$\dot VO_2 $$ increased from 250±22 ml/min to 280±38 ml/min during noradrenaline, to 298±30 ml/min during adrenaline and to 292±39 ml/min during dopamine infusion. The plasma glucose concentration increased from 6.2±0.6 mmol/l to 8.8±0.8 mmol/l, 13.2±1.4 and 7.3±0.4 mmol/l during infusion of noradrenaline, adrenaline or dopamine, respectively. The plasma free fatty acid concentration increased from 0.28±0.10 mmol/l to 0.79±0.21 mmol/l during noradrenaline and to 0.52±0.09 mmol/l during dopamine. In contrast, free fatty acid values averaged baseline values at the end of the adrenaline infusion after an initial increase to 0.72±0.31 mmol/l. Conclusions Administration of noradrenaline, adrenaline or dopamine resulted in persistent increases in $$\dot VO_2 $$ in volunteers. With the exception of the transient adrenaline effect on fatty acids the metabolic actions were steady during 4 h of adrenergic stimulation. Since the adrenergic effect on $$\dot VO_2 $$ is persistent over time a similar action in patients (e.g. septic shock) during treatment with adrenoceptor agonists may be important. Thus, an increase in $$\dot VO_2 $$ during therapy may not only reflect an oxygen debt but also a pharmacodynamic action of adrenoceptor mediated calorigenic and metabolic induction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02425154
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  • 4
    Electronic Resource
    Electronic Resource
    Comparison of epinephrine and dopamine during cardiopulmonary resuscitation (1989)
    Springer
    Intensive care medicine 15 (1989), S. 432-438 
    Details
    ISSN: 1432-1238
    Keywords: Cardiopulmonary resuscitation ; Asphyxial and fibrillatory cardiac arrest ; Epinephrine ; Dopamine ; Porcine model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effectiveness of epinephrine and dopamine for restoring spontaneous circulation after asphyxial or fibrillatory cardiac arrest was compared using a porcine model. Asphyxial arrest: 7 animals received 45 μg/kg epinephrine, 7 animals 2.5 mg/kg dopamine, the remaining 7 animals received no drug treatment. All 7 animals given epinephrine could be resuscitated after 174±53 s, spontaneous circulation could be restored in only 3 of 7 animals given dopamine after 487±63 s and in none of the control animals could spontaneous circulation be established. Ventricular fibrillation: 7 animals were defibrillated without either mechanical measures or drug therapy. The following doses were given before defibrillation and after starting mechanical measures to separate groups of 7 animals each: 45 μg/kg epinephrine, 2.5 mg/kg dopmaine, or no drug therapy. In the absence of either drug or mechanical measures and with mechanical measures only, spontaneous circulation could not be established in any of the cases. After administration of epinephrine, defibrillation and restoration of spontaneous circulation was achieved in 6 of 7 animals in 667±216 s, with dopamine, all the animals could be successfully resuscitated in the shorther time of 174±85 s. Epinephrine was found to be superior to dopamine in the treatment of asphyxial arrest whereas dopamine was found to be better in the management of ventricular fibrillation, probably by improving the balance between myocardial oxygen supply and demand.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00255598
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  • 5
    Electronic Resource
    Electronic Resource
    Positron emission tomographic studies on aromatic L-amino acid decarboxylase activity in vivo for L-dopa and 5-hydroxy-L-tryptophan in the monkey brain (1993)
    Springer
    Journal of neural transmission 94 (1993), S. 127-135 
    Details
    ISSN: 1435-1463
    Keywords: 5-Hydroxy-L-(β-11 C)tryptophan ; L-(β-11 C)DOPA ; positron emission tomography ; aromatic amino acid decarboxylase ; monkeys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The regional brain kinetics following 5-hydroxy-L-(β-11 C)tryptophan and L-(β-11 C)DOPA intravenous injection was measured in twelve Rhesus monkeys using positron emission tomography (PET). The radiolabelled compounds were also injected together with various doses of unlabelled 5-hydroxy-L-tryptophan or L-DOPA. The radioactivity accumulated in the striatal region and the rate of increased utilization with time was calculated using a graphical method with back of the brain as a reference region. The rate constants for decarboxylation were 0.0070 ± 0.0007 (S. D) and 0.0121±0.0010min−1 for 5-hydroxy-L-(β-11C)tryptophan and L-(β-11 C)DOPA, respectively. After concomitant injection with unlabelled 5-hydroxy-L-tryptophan, the rate constant of 5-hydroxy-L-(β-11 C)tryptophan decreased dose-dependently and a 50 percent reduction was seen with a dose of about 4mg/kg of unlabelled compound. A decreased utilization rate of L-(β-11 C)DOPA was seen only after simultaneous injection of 30 mg/kg of either L-DOPA or 5-hydroxy-L-tryptophan. This capacity limitation was most likely interpreted as different affinity of the striatal aromatic amino acid decarboxylase for L-DOPA and 5-hydroxy-L-tryptophan, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01245006
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