Magnetic resonances in biomedical research

Abstract

Prikazana je primjena metoda magnetskih rezonancija - elektronske magnetske rezonancije (EPR) i nuklearne magnetske rezonancije (NMR) u biomedicinskim istraživanjima. Opisani su primjeri istraživanja u kojima se metoda EPR koristi za određivanje mikrogeografije aktivnog centra enzima acetilkolinesteraze i mjerenje konformacijskih promjena pod utjecajem kolinergičnih supstancija, za proučavanje promjena u fluidnosti staničnih membrana pod utjecajem neurotoksina, za određivanje transporta kokarcinogena, forbolestera kroz stanične membrane, te transporta molekula kroz tkiva s pomoću gradijenta magnetskog polja. Opisani primjeri istraživanja metodom NMR odnose se na njenu primjenu za proučavanje metaboličkih osobina skeletnih mišića, karakterizaciju tumora mozga in vitro i moguću dijagnozu tumora i raznih drugih patoloških stanja in vivo.Magnetic resonances are spectroscopic methods by which some structural changes and metabolic processes in biological systems can be followed on the molecular level. There are two main types of magnetic resonance methods: nuclear magnetic resonance (NMR) and electron paramagnetic (spin) resonance (EPR or ESR). By NMR are followed the atomic nuclei with the magnetic moment; in biological systems these are usually lH, 13C, 31P. By EPR are followed paramagnetic centres in biological systems; these are ions of the transition metal group (Fe3+, Cu2+, Mn2+), which appear as cofactors of the enzymes, or free radicals, which are intermediates in biochemical reactions. Instead of paramagnetic centres, which are native in biological systems, very often the molecules with a free radical are incorporated into the system - spin labels or spin probes. Centres with the magnetic moment serve as markers conveying the information about the metabolic f recesses in biological systems and about the changes in these processes in pathological conditions or under the influence of biologically active substances. In this work several typical applications of EPR and NMR in biomedical research are described showing a great variety of issues where magnetic resonances can be used. EPR experiments, Study of the microgeography of acetylcholinesterase active centre and the conformational changes of this centre under the influence of cholinergic substances. Changes in cell membrane fluidity under the influence of neurotoxins. Transport of cocarcinogens, forbolesters, through the cell membrane. Application of magnetic field gradient to the investigation of transport through the tissues. NMR experiments: Application of 1H-NMR to characterization of brain tumours in vitro and possible application of NMR tomography in vivo to diagnosis of tumours and other pathological conditions. Application of 31P-NMR for investigation of metabolic properties of skeletal muscles