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G Stöcklin

Publications and source records attributed to G Stöcklin.

66 records · Page 4Linked to original sources
PubMed1980

Myocardial imaging and metabolic studies with [17-123I]iodoheptadecanoic acid.

After intravenous administration of the stearic acid analogue [17-123I]iodoheptadecanoic acid (I-123 HA), myocardial metabolism was studied in ten normal individuals, eight patients with coronary artery disease and three patients with congestive heart failure. High-quality images were obtained in sequential scintigraphy of I-123 metabolically bound in myocardial tissue. Infarcted zones as well as ischemic regions are indicated by reduced tracer uptake. Iodine-123 in the blood pool and interstitial space consists mainly of radioiodide that is liberated by fatty-acid metabolism and was corrected for. Using the proposed correction not only are the images improved but the uptake and elimination of the I-123 in the myocardial cells can be followed. The average disappearance half-time of I-123 HA from the myocardium of normal persons was 24 +/- 4.7 min. In patients with coronary artery disease significant differences between myocardial regions were observed.

Adult↗
PubMed1979

Long-chain F-18 fatty acids for the study of regional metabolism in heart and liver; odd-even effects of metabolism in mice.

In view of the potential usefulness of fluorine-tagged fatty acids in the study of regional metabolism in the heart and liver, the time courses of uptake and release of 9,10-[18F]fluorostearic acid, 2-[18F]fluorostearic acid, 16-[18F]fluorohexadecanoic acid, 17-[18F]fluoroheptadecanoic acid have been investigated in several organs of NMRI mice. Whereas 2-[18F]fluorostearic acid shows very little uptake in the heart muscle but an increasing accumulation in the liver, the fatty acids with the F-18 label in the middle or at the end of the carbon chain exhibit uptake and elimination behavior similar to that of the analogous C-11-labeled compounds. After rapid concentration in the heart within 1 min, clearance takes place with fast and slow components. 16-[18F]fluorohexadecanoic acid and 17-[18F]fluoroheptadecanoic acid have different half-times of elimination. These differences are also reflected by the fact that nearly all the activity present in the heart can be recovered as fluoride(F-18) in the case of 17-[18F]fluoroheptadecanoic acid, whereas practically no fluoride was found among the metabolites of 16-[18F]fluorohexadecanoic acid. Similar differences were observed for the F-18 activity in bone. The results can be interpreted in terms of the odd-even rule: beta oxidation of even-numbered fatty acids ends up with [18F]fluoroacetic acid, whereas the odd-numbered fatty acids give rise to beta-[18F]fluoropropionic acid. Only in the latter case does dehalogenation take place leading to free fluoride, whereas fluoroacetic acid undergoes further reactions in the citric acid cycle.

Animals↗
PubMed1979

Accumulation of radioiodinated L-alpha-methyltyrosine in pancreas of mice: concise communication.

L-3-iodo-alpha-methyltyrosine, labeled with either I-131 or I-123, has a high pancreatic specificity in mice. A pancreas-to-liver ratio of 8.6 +/- 2.7 is observed during the first hour after i.v. injection. Accumulation is also prominent in the kidneys, but excretion of the radioagent is rapid, 50% of the activity being eliminated during 90 min. Compared with L-[75Se]selenomethionine, the compound currently used for pancreatic imaging, L-3-[123I]or[131I]iodo-alpha-methyltyrosine has a higher pancreas-to-liver ratio, a shorter physical half-life and biological half-time, and better decay characteristics.

Animals↗
PubMed1978

Quantitative ESR-studies of decay-produced radicals in 5-iododeoxyuridine labeled with 125I, 131I or tritium: role of the Auger effect.

In view of the enhanced biological damage caused by the "Auger nuclide" iodine-125, we have carried out quantitative ESR-studies of the radical formation in polycrystalline 5-iododoeoxyuridine (IUdR) resulting from the following internal or external radiation sources: (1) Decay of 3H, 125I or 131I in labeled IUdR; (2) Lanthanum K-photons corresponding to the K-edge of iodine; (3) 60Co gamma-rays. The results clearly indicate that inner shell ionization with its accompanying Auger effect as caused by the lanthanum K X-ray produces about 30% more free radicals per unit dose absorbed than 60Co gamma-rays, when considering the long-lived secondary radicals. Similarly, the concentration of free radicals is by about 30% higher in 125I- than in 131I-labeled IUdR at comparable doses. In the case of 3H-labeled IUdR the dose curve is almost identical with that observed for 125I-labeled IUdR. The results are discussed in terms of a localized radiation damage from low energy electrons.

Cobalt Radioisotopes↗
PubMed1978

Comparative evaluation of fatty acids labeled with C-11, Cl-34m, Br-77, and I-123 for metabolic studies of the myocardium: concise communication.

Various long-chain fatty acids have been labeled with C-11, Cl-34m, Br-77, and I-123 and evaluated for their potential application in measuring myocardial metabolism in vivo. Comparative studies of the kinetics of accumulation and clearance from the heart muscle of mice indicate that the extraction of omega-halofatty acids is more efficient than that of alpha-halofatty acids. Among the omega-halofatty acids, the highest uptake is observed for the 17-iodoheptadecanoic acid, which shows an extraction behavior almost identical to that of [1-11C] palmitic acid, although with a higher radioactivity level in blood due to the release of free iodide.

Animals↗
PubMed1978

Decay-induced incorporation of tritium into nucleosides in aqueous solutions.

In view of environmental and biological implications, the decay-induced incorporation of tritium from T2 into nucleosides in aqueous solutions has been studied by chromatographic methods. It could be shown that at T2 concentrations of about 1 to 2 mCi/ml, labeling of thymidine or deoxyuridine mainly occurs via the 3HeT+ decay ion rather than via beta--radiolysis. In a saturated solution of thymidine, the number of thymidine molecules labeled per tritium decay (L-value) is only 8 X 10(-4), concomitantly 0.6 HTO molecules are also formed, together with CH3T (L = 0.2) and an unidentified organic product (L = 10(-3). Compared to identical concentrations of HT and HTO in aqueous deoxyuridine solutions, the labeling efficiency of T2 is an order of magnitude higher.

Deoxyuridine↗
PubMed1977

Chemical and biological consequences of beta-decay. Part 2.

In Part 1 of this article physical and chemical effects of beta-decay in labelled molecules were reviewed and their potential importance for breaking predetermined and specific bonds were pointed out. After incorporation of labelled biomolecules in living systems, such as viruses, phages or cells, the radioactive decay of the label alters the biological behaviour of the system, in the extreme case causing loss of the ability to reproduce, the extent of these consequences depending strongly on the type of radioisotope. Now Part 2 includes a brief discussion of biological effects associated with beta-decay emphasizing the relative importance of local transmutation and internal radiation effects from the decay of 3H, 14C, 32P, 33P, 35S and 125I. Attempt is also made, whenever possible at the present stage of understanding, to correlate biological effects with chemical processes on a molecular level.

Animals↗
PubMed1977

Chemical and biological consequences of beta-decay. Part 1.

Radioactive decay in a labelled molecule leads to specific chemical and biological consequences which are due to local transmutation effects such as recoil, electronic excitation, build-up of charge states and change of chemical identity, as well as to internal radiolytic effects. In the present paper these effects are reviewed emphasizing the relation of the chemical alterations on a molecular level to the biological manifestation. Potential importance of this type of research for biomedical applications is pointed out. In part 1 we review the underlying physical and chemical principles and consequences of beta-decay of 3H, 14C, 32P, 33P, 35S and 125I for gaseous and simple condensed organic systems. Part 2 which will appear in the next issue will include the discussion of biological effects associated with beta-decay.

Bromodeoxyuridine↗
PubMed1975

Fixation, retention and exhalation of carrier-free 11C-labeled carbon monoxide by man.

Carrier-free 11C-labeled carbon monoxide was produced by proton irradiation of a nitrogen gas flow target via the 14N(p, alpha)11C process followed by on-line reduction of the predominantly formed 11C-carbon dioxide with a yield of 0.4 mCi/muAmin. After appropriate quality control about 2 mCi of carrier-free 11C-carbon monoxide in 500 ml on nitrogen gas were inhaled by test subjects in one breath. The 11C-activity distribution was then followed in vivo by scanning above thorax, head, liver, thigh and os sacrum; simultaneously the 11c-activity of the blood was also followed by batch measurement. The data indicate that part of the 11C-activity migrates from the blood into the intercellular space, while another part is exhaled. The 11C-activity leaves the individual organs with a biological half-life ranging from about 120 to 200 min, a time which is short as compared to the one observed for 51Cr-labeled erythrocytes. A radio gas chromatographic analysis of the exhaled air showed that the 11C-activity leaves the body exculsively in the form of 11C-labeled carbon monoxide. Consequently, metabolism of the 11CO into 11CO2 or other compounds can be excluded.

Carbon Monoxide↗
PubMed1975

Production of short-lived radioisotopes for medical applications using high-energy reactions at JULIC.

The advantages of high energy nuclear reactions for the production of some special short-lived carrier-free radionuclides for allication in nuclear medicine are outlined. The routine production of 11C (T = 20.3 min), 123I (T = 13.3 h) and 28Mg (T = 21.1 h) at the Julich Isochronous Cyclotron JULIC via the 12C(p,pn) 11C-, 127I(d,6n) 123Xe(beta+, EC) 123I- and 27Al(alpha,3p) 28Mg-reaction, respectively, is described. Some areas of fast labelling and its applications are given.

Nuclear Medicine↗