A proton relaxation enhancement investigation of the binding of fatty acid spin labels to human serum albumin

Proton relaxation enhancement (PRE) values for fatty acid spin labels bound to human serum albumin have been investigated using the inversion-recovery method at 24 MHz. At 0.1 mM protein concentration and a label-to-protein ratio of one-to-one, the PRE value for 12-Doxylsterate-albumin complex is 7.8 +/- 2.3, whereas the PRE values for 5-Doxylstearate and 16-Doxylstearate-albumin complexes are 1.5 +/- 0.6 and 1.7 +/- 0.7, respectively. Addition of 10-fold excess of stearic acid reduced the PRE values nearly to 1, indicating that the strong enhancements arise from direct binding of fatty acid spin labels to human serum albumin. PRE values for all three labels exhibit maxima as a function of the label-to-protein ratio, suggesting multiple binding sites for fatty acid spin labels with labels in the tightest binding sites not resulting in the most effective relaxation. Based on the rates of reduction of ESR signal amplitudes by sodium ascorbate, the difference in PRE values for the three fatty acid spin labels bound to albumin is attributed to the difference in water accessibility of the nitroxide moieties at various positions along the acyl chain, being greater at the C-12 position than at C-5 or C-16 position. The PRE value of 8 for 12-Doxylstearate bound to human serum albumin indicates that this complex may be a suitable paramagnetic contrast agent for in vivo NMR imaging.     

Autoimmune reactions in patients with M-component and peripheral neuropathy.

A study of 17 patients with autoimmune axonal or demyelinating peripheral neuropathy in combination with M-component is described. The M-component was associated with MGUS (monoclonal gammopathy of undetermined significance) in 12 patients, CLL in one patient, WaldenstrÖm's disease in one patient, and myeloma in three patients. Immunohistological examination with direct and indirect fluorescence showed binding of antibodies to nerve structures of the same class and light chain as seen in the M-component. In five cases of IgM M-component, the demyelinating neuropathy was caused by binding of the IgM M-protein and complement C3b to myelin-associated glycoproteins (MAG). In 12 cases with axonal neuropathy, binding of IgG to the connective tissue of the peri- and endoneurium was found in 50% of cases, IgM in five cases, and IgD in one case. None of the patients had central nervous system (CNS) symptoms. The clinical and therapeutic difficulties are discussed; only two patients with an acute course responded to immunosuppression. A marked co-expression of other autoimmune phenomena is interpreted in the light of cross-reactions between the autoantibody and similar tissue autoantigens.     

Exercise and older adults

The benefits of regular physical activity in older persons are numerous and well established. Regular physical activity in older adults is associated with an overall improvement in health, functional capacity, quality of life, and independence. Many questions arise for healthcare providers regarding an older person’s ability and motivation to be physically active. The healthcare provider has a unique opportunity to assess the older client’s incentives, preferences, and abilities for physical activities, as well as to prescribe a safe, appropriate, and enjoyable exercise plan. The exercise precription can be simple yet thorough enough to ensure benefits in an older person’s health and functional capacity.