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Biomedical subjects

C G Swahn

Publications and source records attributed to C G Swahn.

71 records · Page 4Linked to original sources
PubMed1990

Positron emission tomographic measurements of cerebral glucose utilization using [1-11C]D-glucose.

Regional CMRglc was measured in seven healthy volunteers with positron emission tomography using [1-11C]D-glucose. Regional CBF was measured using [11C]fluoromethane. The arteriovenous differences of unlabeled glucose and oxygen together with 11C metabolites were also measured. In addition to the loss of [11C]CO2, a loss of acidic 11C metabolites was also detected. A three-compartment model was applied to the tracer data in the time interval 0-24 min. After correction for the loss of 11C metabolites, the tracer method gave an average CMRglc of 26.4 +/- 1.9 (SD) mumol/100 g/min, close to the value obtained with the Fick principle. After correction for the loss of [11C]CO2 only, the tracer method gave 23.6 +/- 2.1 mumol/100 g/min, compatible with (1/6) CMRO2, obtained with the Fick principle. These results and the time course of the loss of acidic 11C metabolites are consistent with the presence of nonoxidative metabolism of glucose that causes an early loss of mainly [11C]lactate after a bolus injection of the tracer. This implies that [1-11C]D-glucose measures the rate of glucose oxidation rather than the total CMRglc. The experiments using [1-11C]D-glucose were compared to five analogous experiments using [U-11C]D-glucose together with [15O]H2O as a flow tracer. After correction for the loss of [11C]CO2, the two glucose tracers gave similar global values of CMRglc and other parameters associated with glucose utilization, but with labeling in the carbon-1 position, the loss of [11C]CO2 was substantially delayed and the contrast between gray and white matter was improved.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗
PubMed1988

CSF creatinine in schizophrenia.

Concentrations of creatinine in cerebrospinal fluid (CSF) from schizophrenic patients and healthy control subjects were determined by a liquid chromatographic method. The concentration of creatinine in CSF from schizophrenic patients was lower (42.8 nmol/ml) than that of the controls (54.4 nmol/ml). The concentration of creatinine was correlated to the levels of homovanillic acid and 5-hydroxyindoleacetic acid. Treatment of the schizophrenic patients with sulpiride (800 mg daily), but not with chlorpromazine, elevated the concentration of creatinine in the CSF.

Adult↗
PubMed1985

Gas chromatographic-mass spectrometric determination of myo-inositol in human cerebrospinal fluid.

The concentration of free myo-inositol in CSF was determined with a gas chromatographic-mass spectrometric method using deuterated myo-inositol as an internal standard after conversion to the hexa-O-acetyl derivative with acetic anhydride and pyridine. Twenty microliters of CSF is sufficient for the analysis which has a coefficient of variation of 9%. Identical analytical results were obtained on two different mass numbers. Schizophrenic patients were compared with healthy control persons. In addition, patients with rheumatoid arthritis or with neurological illnesses were studied. No consistent differences related to the illness could be found. The mean concentration of myo-inositol was about 25 micrograms/ml. Treatment of schizophrenic patients with chlorpromazine or sulpiride had no significant effect on the concentration of myo-inositol in CSF.

Adult↗
PubMed1984

Determination of 1-methylimidazole-4-acetic acid in brain tissue from rat and mouse.

The concentration of the histamine metabolite 1-methylimidazole-4-acetic acid was determined in brain tissue from rat and mouse with a gas chromatographic-mass spectrometric method. Mouse brain contained 1.7-3.2 nmol/g, depending on the strain. The concentration in cerebrum from Sprague-Dawley rats was 1.2 nmol/g, whereas cerebellum contained 0.24 nmol/g. The concentration of tele-methylhistamine in mouse brain was 1.4-2.2 nmol/g. The concentration of 1-methylimidazole-4-acetic acid in rat brain after death did not change significantly during 2 h at room temperature.

Animals↗
PubMed1984

Pharmacokinetics in baclofen overdose.

The pharmacokinetics of baclofen analyzed by gas chromatography mass spectrometry in a massive intoxication case (baclofen 1230 mg orally) is presented. In contrast to earlier reports, no increase in the plasma half-life of elimination of baclofen could be observed (t1/2 = 4.58 hours). On the contrary, we found an increased plasma clearance (Clpl = 0.368 l/kg) in this highly intoxicated patient compared to the kinetics usually found in healthy subjects.

Absorption↗
PubMed1983

Identification and determination of 1-methylimidazole-4-acetic acid in human cerebrospinal fluid by gas chromatography-mass spectrometry.

A method for the quantification of 1-methylimidazole-4-acetic acid in human CSF was developed. Methylimidazole-acetic acid was identified and quantitated in CSF. The method involves concentration of the compound on a cation exchanger, extraction of the methyl ester with ethyl acetate, and preparation of a heptafluorobutyryl derivate of the methyl ester, which is finally purified by chromatography on silica gel and quantitated by gas chromatography-mass spectrometry with the deuterated analogue as internal standard. The coefficient of variation at 1 ng/ml was 13%. The limit of sensitivity was about 0.2 ng/ml. The concentration of methylimidazole-acetic acid in lumbar CSF from healthy volunteers was below 1 ng/ml. Ventricular CSF contained higher concentrations than lumbar fluid. The existence of a rostrocaudal concentration gradient was established. There was a correlation between the concentration of methylimidazole-acetic acid and tele-methylhistamine in CSF. The concentration of methylimidazole-acetic acid in lumbar CSF from schizophrenic patients, patients with subarachnoidal haemorrhage, or patients with rheumatic disease was in the range of that in healthy volunteers.

Gas Chromatography-Mass Spectrometry↗
PubMed1981

Concentrations of baclofen in serum and breast milk from a lactating woman.

A lactating woman with spastic paraplegia was given 94 mumol (20 mg) of baclofen orally to study the transport of the drug into breast milk. The concentration of baclofen in serum and milk was determined with a gas chromatographic--mass spectrometric method. The elimination curves in serum and milk showed a similar course, the elimination from milk being delayed about 3 h relative to serum. The total amount of baclofen excreted in the milk during 24 h was about one thousandth of the ingested dose.

Adult↗
PubMed1978

Sex differences in psychoneuroendocrine reactions to examination stress.

Sex differences in adaptation and coping were studied by comparing neuroendocrine and psychological functions in male and female high-school students during 2--3 hr of routine school work (control condition) and a 6-hr matriculation examination (stress condition). In the control condition sex differences were slight and nonsignificant. During examination stress, the urinary excretion of cortisol, adrenaline, noradrenaline, and 3-methoxy-4-hydroxy-phenylethylene glycol (MOPEG or MHPG) increased in both sexes, but to a consistently greater extent in the male group, significantly so for adrenaline and MOPEG. Both sexes performed equally well in the examination, but self-reports showed that feelings of success and confidence were common among males, whereas feelings of discomfort and failure dominated in the female group. High discomfort correlated with poor performance in the males but with good performance in the females.

Achievement↗
PubMed1976

Determination of conjugated monoamine metabolites in brain tissue.

Levels of free and conjugated monoamine metabolites were analysed in brain tissue of rat and man. In the rat the conjugates were mainly of the sulfate ester type. The levels of conjugated dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) constituted 40--50% of the total amount of the metabolites. 4-Hydroxy-3-methoxy-phenylglycol (HMPG) and 5-hydroxy-3-indoleacetic acid (5-HIAA) were present as conjugates in 90 and 10% of the total levels. Chlorpromazine treatment resulted in an elevation of both the free and the conjugated forms of the dopamine metabolites and HMPG. In a human caudate nucleus obtained at autopsy both DOPAC and HMPG were present in the free form and as sulfate and glucuronide conjugates. The major dopamine metabolite found in this human brain was HVA. This metabolite and 5-HIAA occurred predominantly as free metabolites.

3,4-Dihydroxyphenylacetic Acid↗
PubMedDate not supplied

PET study of the M1-agonists [11C]xanomeline and [11C]butylthio-TZTP in monkey and man.

Xanomeline, a substituted TZTP, is a new M1 selective muscarinic agonist in clinical trials for Alzheimer's disease. The brain uptake of [11C]xanomeline and the analog [11C]butylthio-TZTP was examined by positron emission tomography (PET). Radioactivity accumulated most markedly in the neocortex and the striatum. Pharmacological characterization in vitro and in cynomolgus monkeys in vivo by PET indicated specific [11C]butylthio-TZTP binding to muscarinic receptors and to sigma-1 recognition sites. More than 5% of the radioactivity was in the human brain 5 min after i.v. injection of [11C]xamomeline or [11C]butylthio-TZTP. This high brain uptake may be clinically advantageous in the sense that substituted TZTP may induce central muscarinic agonist effects at a dose level for which there is a low risk of peripheral side-effects.

Adult↗