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T I maps of phantoms containing the samples of pure serum or Mn(II)-doped serum at pH = 2 were imaged by 1.5 T and 1 T MR Imagers. The /'1 measurements made for the determination of the paramagnetic increase were carried out before and after adding ascorbic acid. The difference of the 1/T~ in samples with and without ascorbic acid was evaluated as the paramagnetic contribution (PMC) of serum iron. As iron content of serum varied from iron deficient to iron overload, the PMC values increased from 0.93 to 0.565 s -~ at 1.5 T and from 0.103 to 0.609 s -~ at 1 T. For confirmative purposes, serum iron of each sample was determined from the paramagnetic contribution and also by an autoanalyzer. The contents of serum iron determined from PMC were in good agreement with those by the autoanalyzer and also with the literature. The data suggest that the paramagnetic contribution of serum iron can be measured by MRI.

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The water proton relaxation rate enhancement of Mn(II) bound to bovine serum albumin (BSA) and the association constant for manganese to BSA have already been determined, but such determinations have not been done for human serum albumin (HSA) and other human serum proteins and also for human serum. In this work, NMR T1 values in aqueous solutions of serum proteins and serum were measured versus increasing concentration of Mn(II). Proton relaxation rate enhancements (ε*) caused by different manganese concentrations were determined for each solution and 1/ε* was fitted against concentrations of Mn(II). Proton relaxation rate enhancements (εb) of Mn(II) bound to albumin, γ-globulin, (α+β)- globulins and serum were found to be 13.69, 3.09, 8.62, and 10.87, respectively. Free and bound manganese fractions, resulted from each addition of Mn(II) to the sample, were determined by using corresponding (ε*) and the εb values. Association constants for Mn(II) to HSA and γ-globulin were calculated as 1.84 x 104 ᴍ-1 and 2.35 x 104 ᴍ-1, respectively. Present data suggest that the proton relaxation rate enhancement of Mn(II) in serum is caused by Mn(II) bound to various serum constituents. Data also suggest that association constants for Mn(II) to γ-globulin are nearly the same as that to HSA.

Macromolecular crowding is a general phenomenon of biological systems, and the evaluation of a correlation time for a specific molecule is difficult when the molecular crowding exists. The determination of an effective correlation time may therefore give useful insights into molecular dynamics of such systems. In this work, the relaxation rates in the mixture of D2O (80%) and cystic fluid (20%) were measured with a NMR operating at 400 MHz for three types of cysts (non-infected radicular, infected radicular and hemorrhagic). The effective correlation times (τvalues) were then determined by using a formula derived from the observed relaxation rates. Theτvalue of the infected cyst was found to be longer than those of the others for the studied cases. The present data suggest that an effective correlation time for fluids with macromolecular crowding can be determined from NMR relaxation measurements.