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Biomedical subjects

B Johansson

Publications and source records attributed to B Johansson.

At least 361 records · Page 20Linked to original sources
PubMed1994

Supercritical fluid extraction of polychlorinated biphenyls from lyophilized fish tissue.

A method for the rapid interference free analysis of polychlorinated biphenyl congeners (chlorinated biphenyls, CBs) in lyophilized fish tissue is presented. The method was developed on a lyophilized tuna muscle tissue that contained 2.8% lipid (dry mass based), and native CB concentrations in the range of 3-84 ng/g. Sample preparation was made by supercritical fluid extraction using pure CO2 as extraction fluid. Analysis by high-resolution gas chromatography-electron-capture detection analysis was carried out with on-column injection on two parallel coupled columns, a 60 m DB-17 column and a series combination of a 25 m SIL-8 column and a 25 m HT-5 column. Supercritical fluid extraction was compared with Soxhlet extraction and found to give quantitative recoveries, detection limits of 0.5-2 ng/g and standard deviations of less than 5% on average. The developed method was confirmed on nine different lyophilized fish samples which contained 6.1-26.5% lipid (dry mass based), and native CB concentrations in the range 0.8-134 ng/g.

Animals↗
PubMed1994

Karyotypic pattern of pancreatic adenocarcinomas correlates with survival and tumour grade.

The relationship between cytogenetic findings and clinicohistopathological parameters was assessed in 29 patients with pancreatic adenocarcinoma. Karyotypic analysis revealed normal karyotypes (N) in 8 carcinomas and abnormal karyotypes (A) in 21. Within the A group, 8 cases had simple chromosome abnormalities (As), i.e., only one numerical or structural aberration, whereas 13 had complex changes with multiple numerical and structural abnormalities (Ac). No significant differences between the N and A groups were detected in terms of tumour grade, clinical stage, type of surgery performed, tumour site or size or the patient's age and survival. A correlation analysis between groups As and Ac revealed a significant difference with regard to grade, poorly differentiated carcinomas being more frequent in the Ac group. Patients in the Ac group had also a significantly shorter survival time than those in the As group. None of the other potentially prognostic parameters, i.e., grade, tumour site, stage and type of surgery performed, correlated significantly with clinical outcome.

Adenocarcinoma↗
PubMed1994

Evidence for functionally important adenosine A2a receptors in the rat hippocampus.

Adenosine A2a receptors are not confined to dopamine-rich areas of the brain, since thermocycling analysis shows that adenosine A2a receptor mRNA is expressed also in the hippocampus (CA1, CA3 and dentate gyrus) and cerebral cortex. The expression of A2a mRNA in three main areas of the hippocampus was confirmed by in situ hybridization; A2a mRNA expression was mainly localized in the pyramidal and granular cells, the same hippocampal regions that showed adenosine A1 receptor mRNA expression. Receptor autoradiographic studies with [3H]CGS 21680 (30 nM), a selective adenosine A2a receptor agonist, showed specific binding sites in the hippocampus. The density of [3H]CGS 21680 binding was greatest in the stratum radiatum of the CA1 area, followed by the stratum oriens of the cornu Ammonis, stratum radiatum of the CA3 are and supra-granular layer of the dentate gyrus. This anatomical distribution of [3H]CGS 21680 binding was similar to the pattern of [3H]CHA binding in the hippocampus. Electrophysiological studies in the Schaffer fibers/CA1 pyramids showed that upon activation of the A2a receptors with CGS 21680 (10 nM) the ability of the adenosine A1 receptor agonist, CPA, to inhibit neuronal activity was significantly attenuated. These results show functionally important co-expression and co-localization of adenosine A2a and A1 receptors in the hippocampus. The results also suggest that adenosine A2a receptor-mediated neuromodulation is not confined to the basal ganglia, but is more widespread throughout the nervous system.

Adenosine↗