Assessment of Contribution of Curie-Spin Mechanism in Proton Relaxation During Aggregation Process of Hemoglobin S
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Applied Magnetic Resonance
ORIGINAL PAPER
Assessment of Contribution of Curie‑Spin Mechanism in Proton Relaxation During Aggregation Process of Hemoglobin S C. Cabal1,2 · M. Lores1 · V. I. Chizhik3 · S. O. Rabdano3 · J. C. García‑Naranjo1 Received: 29 April 2020 / Revised: 1 July 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract Previous works showed a significant increase in the rotational correlation time of the water bound to the hemoglobin S during the aggregation process under sickle cell disease. In this case, the contribution of “Curie-Spin” relaxation mechanism to proton relaxation may be expected. The Curie-Spin relaxation mechanism has been well described theoretically but only a few experimental evidences have been presented. Based on the reported correlation times, the contribution of the Curie-spin relaxation mechanism to proton relaxation times ( T1 and T2 ) has been estimated in comparison with the contribution of the dipole–dipole relaxation mechanism at the extreme stages of the aggregation process of the hemoglobin S. This contribution is about 25% and 50% in the spin–spin relaxation rates at the magnetic field of 1.5 T during the latent and ending stages of the aggregation process, respectively. At lower magnetic fields, this mechanism gives an insignificant contribution. The contribution to the spin–lattice relaxation is negligible even at 1.5 T. In particular, this relaxation mechanism should be taken into account when interpreting experiments related to MRI.
1 Introduction The potentials of the magnetic resonance methods in the research of the biomedical systems have been well-known. Nuclear magnetic relaxation plays an important role in the investigations of molecular mobility in those objects [1]. Many diseases are associated with the existence of molecular aggregates. The polymerization (aggregation) of the hemoglobin S (HbS) is the underlying molecular process in sickle cell * S. O. Rabdano [email protected] 1
Biophysics and Medical Physics Center, University of Oriente, Santiago de Cuba, Cuba
2
Faculty of Physics, Havana University, Havana, Cuba
3
Saint Petersburg State University, St. Petersburg, Russia
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disease (SCD) that is distributed worldwide [2]. The aggregation process of HbS starts at low oxygenation pressure inside the red blood cell. After some time, called “delay time”, irreversible molecular aggregates of the HbS are formed. In connection with these modifications, the red blood cells produce some disorders in the microcirculation and the hemodynamics conducing to the painful vaso-occlusive crisis [2–9]. Many techniques have been used to monitor the polymerization processes and the proton magnetic relaxation method has reached noticeable successes in studying them [4–9]. An adequate understanding of the mechanisms of the relaxation processes, associated with molecular agglutination, is very important for the development of new diagnostic and therapeutic strategies. The HbS aggregation proces
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