Living arrangements and nutrient intakes of healthy women age 65 and older: a study in Manhattan, Kansas.

One hundred healthy women over age 65 were recruited for a study to determine differences in nutrient intakes by living arrangement and to examine the effect of demographic characteristics, health habits, and social contacts on nutrient intakes. There were significant differences (p < 0.05) in the mean intakes for calcium and riboflavin between women living alone and women living with a spouse. There were no significant differences in health habits by living arrangement, but women living alone were more likely to have fewer social contacts than women living with a spouse (x2 = 38.25; p < 0.001). Education, physical activity, and smoking were the most important predictors of nutrient intakes.

Dry-reagent strips used for determination of theophylline in serum.

A reagent strip for quantifying theophylline in serum or plasma has been developed for use with the Apoenzyme Reactivation Immunoassay System (ARIS) with the Ames Seralyzer reflectance photometer. The test takes 80 s and involves comparison with a two-point calibration line, which can validly be stored in the instrument for two weeks. Results for theophylline in clinical serum samples correlate well (r greater than 0.98) with results by liquid chromatography, fluoroimmunoassay, and enzyme immunoassay procedures. The within-run CV for four concentrations of controls ranged from 3.5 to 6%; the between-run CVs ranged from 3 to 5%. This assay for use in therapeutic drug monitoring is convenient, rapid, and simple, and thus is appropriate for use in emergency rooms, physician's offices, and small laboratories.

Solid-phase chemistry: Its principles and applications in clinical analysis.

A review is given of the development of solid-phase reaction systems (test papers, impregnated-fibre systems, multi-layer film systems) for rapid field and laboratory testing in clinical analysis.

Solid-phase colorimetric determination of potassium.

A nonpolar organic film (plasticized polyvinyl chloride) containing the ionophore valinomycin was incubated with an aqueous solution containing potassium ion and a detectable anion (erythrosin B). The amount of erythrosin B retained by the film after washing could be measured by absorbance or reflectance, and was directly related to the potassium concentration. This dye-binding method is quantitative for potassium and is suitable for both aqueous and serum-based solutions. There was no interference by sodium in the range found in serum. Several polyvinyl chloride plasticizers and anionic dyes and some other ionophores were found to be useful. The anion binding is thought to be restricted to the surface.

Effects of pressure on visible spectra of complexes of myoglobin, hemoglobin, cytochrome c, and horse radish peroxidase.

The spectra of the ferric form of most heme proteins [metmyoglobin, methemoglobin, horse radish peroxidase (EC 1.11.1.7), and ferricytochrome c at pH 1.5] are converted from high-spin (open crevice) structure to low-spin (closed crevice) form under pressure. Pressures up to 8000 kg/cm2 (780 MPa) have no effect on the spectra of high-spin ferro- and ferricytochrome c, which have a closed crevice structure at pH 7.0. Spectra of deoxy-ferromyoglobin and deoxy-ferrohemoglobin are reduced in intensity, but pressure does not change the positions of the absorption maxima. Cyanide ion prevents pressure-induced spectral changes in metmyoglobin and methemoglobin up to 8000 kg/cm2. Carbon monoxide (with a high affinity for the ferro heme iron) has a similar effect on ferromyoglobin and ferrohemoglobin. The pressure required to cause spectral changes in the heme proteins falls in the order, cytochrome c (pH 7.0) greater than horse radish peroxidase greater than myoglobin greater than hemoglobin. We have calculated a volume change of --50 cm3/mol associated with the configurational change accompanying the reformation of the iron-methionine bond in cytochrome c at low pH.

Volume changes in binding of ligands to methemoglobin and metmyoglobin.

The volume changes for the binding of various ligands to metmyoglobin and methemoglobin have been determined from the effect of pressure on the binding constants (for metmyoglobin) and by direct dilatometry (for methemoglobin). The volume changes associated with the binding of cyanide and azide ions to methemoglobin are pH-dependent. The volume change for the binding reaction is evidently affected by the same subtle structural variations that have been judged to be present from the variation with pH of enthalpy and entropy for the binding reactions in these proteins. Hydration changes and spin state changes which have been postulated to be linked with structural variations in these proteins must be pH-dependent.

Water proton magnetic resonance studies of normal and sickle erythrocytes. Temperature and volume dependence.

The temperature and cell volume dependence of the NMR water proton line-width, spin-lattice, and spin-spin relaxation times have been studied for normal and sickle erythrocytes as well as hemoglobin A and hemoglobin S solutions. Upon deoxygenation, the spin-spin relaxation time (T2) decreases by a factor of 2 for sickle cells and hemoglobin S solutions but remains relatively constant for normal cells and hemoglobin A solutions. The spin-lattice relaxation time (T1) shows no significant change upon deoxygenation for normal or sickle packed red cells. Studies of the change in the NMR linewidth, T1 and T2 as the cell hydration is changed indicate that these parameters are affected only slightly by a 10-20% cell dehydration. This result suggests that the reported 10% cell dehydration observed with sickling is not important in the altered NMR properties. Low temperature studies of the linewidth and T1 for oxy and deoxy hemoglobin A and hemoglobin S solutions suggest that the "bound" water possesses similar properties for all four species. The low temperature linewidth ranges from about 250 Hz at -15 degrees C to 500 Hz at -36 degrees C and analysis of the NMR curves yield hydration values near 0.4 g water/g hemoglobin for all four species. The low temperature T1 data go through a minimum at -35 degrees C for measurements at 44.4 MHz and -50 degrees C for measurements at 17.1 MHz and are similar for oxy and deoxy hemoglobin A and hemoglobin S. These similarities in the low temperature NMR data for oxy and deoxy hemoglobin A and hemoglobin S suggest a hydrophobically driven sickling mechanism. The room temperature and low temperature relaxation time data for normal and sickle cells are interpreted in terms of a three-state model for intracellular water. In the context of this model the relaxation time data imply that type III, or irrotationally bound water, is altered during the sickling process.