No abstract

The proton spin-lattice and spin-spin magnetic relaxation times ate investigated at 4 MHz in samples of hemoglobin A and S with intracellular concentrations, at 36 ~ and during spontaneous deoxygenation. Magnetic relaxation behaves differently in the solutions of hemoglobin A and S. The possible causes of this behavior are discussed: changes in molecular mobility, the variations of' hemoglobin magnetism, and the appearance of microinhomogeneities in the solutions of hemoglobin S at the end of the polymerization process.

Abstraet. The microviscosity and the protein rotational correlation time are analyzed in samples of hemoglobin A and hemoglobin S with the intracellular concentration at 36 •C and during spontaneous deoxygenation. With this purpose, we use glutathione and carbonmonoxy hemoglobin labeled with 4-maleimido-2,2,6,6-tetramethyl-piperidine-l-oxyl (TEMPO) as probes and 4-maleimido TEMPO bound to the hemoglobin (A and S) asa spin label. The saturation transfer electron paramagnetic resonance experiment showed a sigmoidal behavior, and an increase (about twice) of the hemoglobin rotational correlation time and microviscosity during the polymerization process of hemoglobin S. The delay time determined by this method coincides with that obtained in proton magnetic resonance experiments. These results help to explain the temporal behavior of the proton relaxation times obtained in samples of hemoglobin A and S under the same experimental eonditions.

The delay time of the Hb S polymerization process was investigated in 63 patients with sickle cell disease during steady state and 10 during painful crisis starting from spin-spin proton magnetic resonance (PMR) time behavior measured at 36 degrees C and during spontaneous deoxygenation. We found a significant decrease of delay time as a result of the crisis (36 +/- 10%) and two well-differentiated ranges of values for each state: 273-354 min for steady state and 166-229 min for crisis with an uncertainty region of 15%. It is possible to use PMR as an objective and quantitative method in order to differentiate both clinical conditions of the sickle cell patient, but a more clear differentiation can be established comparing the delay time (td) value of one patient during crisis with his own td value during steady state.

The antisickling action on polymerization of 4-hydroxy-3-metoxybenzaldehyde (Vanillin) was demonstrated in vivo in a double blind, placebo-controlled clinical therapeutic trial performed in 30 patients (11 belonging to the control group), through the increment of the delay time (td). The td was observed in the kinetic curve of the polymerization of the Hb S solution at 26 degrees C and pH 7.4. The kinetics of the Hb S aliquots was monitored by measuring the proton spin-spin magnetic relaxation time (T2) at 4 MHz. The kinetic curve families of the control group showed similarities and the td values remained constant during the 8 weeks of the study. This was not so for the patients treated with Vanillin, for which the td increased on average 1.6 times. On the other hand, the relative variation of drepanocytes observed by the Simple Test decreased 24.50% Both results indicate a decrease in the effectiveness of the polymerization process.