Nonheme iron in sickle erythrocyte membranes: association with phospholipids and potential role in lipid peroxidation

Previous studies documented the abnormal association of heme and heme proteins with the sickle RBC membrane. We have now examined RBC ghosts and inside-out membranes (IOM) for the presence of nonheme iron as detected by its formation of a colored complex with ferrozine. Sickle ghosts have 33.8 +/- 18.2 nmol nonheme iron/mg membrane protein, and sickle IOM have 4.3 +/- 3.0 nmol/mg. In contrast, normal RBC ghosts and IOM have no detectable nonheme iron. The combination of heme and nonheme iron in sickle IOM averages nine times the amount of membrane- associated iron in normal IOM. Kinetics of the ferrozine reaction show that some of this nonheme iron on IOM reacts slowly and is probably in the form of ferritin, but most (72% +/- 18%) reacts rapidly and is in the form of some other biologic chelate. The latter iron compartment is removed by deferoxamine and by treatment of IOM with phospholipase D, which suggests that it represents an abnormal association of iron with polar head groups of aminophospholipids. The biologic feasibility of such a chelate was demonstrated by using an admixture of iron with model liposomes. Even in the presence of tenfold excess adenosine diphosphate, iron partitions readily into phosphatidylserine liposomes; there is no detectable association with phosphatidylcholine liposomes. To examine the bioavailability of membrane iron, we admixed membranes and t-butylhydroperoxide and found that sickle membranes show a tenfold greater peroxidation response than do normal membranes. This is not due simply to a deficiency of vitamin E, and this is profoundly inhibited by deferoxamine. Thus, while thiol oxidation in sickle membranes previously was shown to correlate with heme iron, the present data suggest that lipid peroxidation is related to nonheme iron. In control studies, we did not find this pathologic association of nonferritin, nonheme iron with IOM prepared from sickle trait, high-reticulocyte, postsplenectomy, or iron-overloaded individuals. These data provide additional support for the concept that iron decompartmentalization is a characteristic of sickle RBCs.     

Adult physical activity behavior: a trend analysis

One of the health objectives for the nation is to have 60% of adults 18-64 years regularly active in vigorous physical activity by 1990. In this paper an effort is made to determine whether American society is making satisfactory progress toward this goal. Two independent databases are analyzed: time diaries collected from a national sample of American adults in 1981; and the Simmons Market Research Bureau, Inc., survey undertaken in 1984. Participation of adults 25-64 in moderate to vigorous activities that included racquet sports, swimming, hiking, bicycling, skiing, jogging, outdoor gardening, skating, etc. is compared between the two time periods. After adjusting for social desirability bias the results indicated there were a similar number of non-participants of the activities analyzed in 1981 and 1984. There was, however, an increase in the number of adults participating occasionally in vigorous activity, although, there did not appear to be any increase in the number who were regularly active, i.e. at least 3 days/week. Thus, while there are indications that adults 25-64 years are adopting more vigorous activity, less than 20% were regular enough in 1984 for improvements in cardiovascular functioning to occur. Unless there were dramatic increases in the activity status of adults 18-24 years of age which was not assessed in this study, the 1990 goal is unlikely to be met.     

Non-ulcerative fungal keratitis diagnosed by posterior lamellar biopsy*

We report a case of Fusarium solani keratitis which highlights the difficulties often associated with management of fungal corneal infections. This case demonstrates several unusual and interesting features: the occurrence of deep fungal pathology after superficial injury, the difficulties encountered in attempting to isolate and identify the causative organism, and the protracted course taken by an organism often noted to be rapidly destructive. These features necessitated an individual approach to therapy, employing unconventional medical and surgical techniques to achieve a satisfactory outcome     

Study of IgM aggregation in serum of patients with macroglobulinemia.

The effect of solvent conditions on the aggregation of IgM in serum specimens from patients with macroglobulinemia was studied by a turbidimetric procedure. Aggregation of IgM varied considerably among the samples and was affected by a number of experimental parameters. In general, IgM aggregation was more pronounced under acidic conditions and in solvents with low ionic strength. The presence of water-miscible organic solvents also promoted aggregation. Based on these studies, it was concluded that the major force involved in the formation of immunoglobulin aggregates in the serum of patients with macroglobulinemia was electrostatic, rather than hydrophobic, interactions. A number of additives known to prevent protein aggregation were evaluated for their effectiveness in inhibiting IgM aggregation. The only additives that were shown to inhibit or reduce IgM aggregation were charged molecules, such as arginine, sodium chloride, ethylenediamintetraacetic acid and quaternary ammonium beta-cyclodextrin. Some of these charged additives were also effective in dissociating the IgM aggregates once they were formed, even in the presence of detergent.     

Reliability of grip strength, walking time and button test performed according to a standard protocol

Excellent interobserver and intraobserver reliability (reproducibility) was seen for the grip strength, walking time and button test measures in 40 patients with rheumatoid arthritis (RA), when measurement was performed according to a standard protocol. Evidence of reliability, coupled with the observation that baseline measures predict longterm morbidity and mortality in individual patients, suggests that these measures might be more widely used in general rheumatologic care.     

Intracanalicular arachnoid cyst mimicking acoustic neuroma: CT and MRI.

A patient with a surgically proven intracanalicular arachnoid cyst was studied using computed tomography, magnetic resonance imaging, and air CT cisternography. The lesion had a similar radiographic appearance to acoustic neuroma and therefore, although rare, must be considered in the differential diagnosis of intracanalicular mass lesions. We report a case in which examination was performed, in evaluating the lesion, utilizing high-resolution air CT cisternography and magnetic resonance imaging (MRI).