Faculty Bibliography

Introduction Most persons on hemodialysis (HD) are older, and many have trouble with walking and self-care. Yet data are sparse on how mobility is shaped by personal factors such as motivation in this group. Our goal was to identify what personal factors impact the mobility of older adults on HD. Methods We included 1) older adults on HD (inclusion criteria: >=60 years; on outpatient HD) and 2) care partners (inclusion criteria: >=18 years; routinely helping an older adult on HD). Each had a single in-person assessment. We administered the Short Physical Performance Battery (SPPB, range 0-12 points) to assess mobility, and audio-recorded one-on-one semi-structured key informant interviews regarding personal factors for mobility. Unless requested, older adults and care partners were interviewed separately. Transcripts underwent descriptive and focused coding; the codebook was revised iteratively until consensus on all code definitions was reached. We identified codes that were personal factors using International Classification of Function criteria. A combined inductive and deductive approach extracted major themes. Results We enrolled 31 older adults on HD (42% female, 50% Black) with a mean age of 72.5+/-8.1(S.D.) years and a mean history on HD for 4.6+/-3.5 years. For the older adults on HD, mean SPPB was 3.6+/-2.8 points. Twelve care partners enrolled (75% female, 50% Black) with a mean age of 53.8+/-15.7 years. TheTable lists the themes that emerged. Conclusion Our diverse sample of older adults on HD had poor mobility, and had a mean SPPB score that is associated with 20% one-year mortality in other groups. They want mobility and independence, but mobility frequently flutuates, causing distress. They and their care partners have learned to be flexible in their expectations. Future studies should incorporate these insights in interventions to improve the mobility of older adults on HD

Human umbilical vein endothelial cells in culture (HUVEC) express receptors for urokinase-type plasminogen activators (u-PA). The immunochemical nature of this receptor and its relationship to u-PA receptors expressed by other cell types is unknown. Cross-linking active site-blocked u-PA to HUVEC lead to an increase in its apparent molecular mass by approximately 40 Kd. The predominant u-PA binding protein isolated from whole cell detergent extracts migrated with a molecular mass of approximately 36 Kd using affinity chromatography. In contrast, when only cell surface proteins were radiolabeled before extraction, the predominant labeled u-PA binding protein isolated migrated with a molecular mass of approximately 46 Kd. Several pieces of evidence suggested that the difference in molecular mass between these two u-PA binding proteins resulted from glycosylation of a single receptor protein. First, a polyclonal antibody against u-PA receptor isolated from phorbol myristate acetate (PMA) stimulated U-937 cells reacted with both the 36- and 46-Kd proteins on Western blotting. Second, the size of the unmodified receptor was estimated by amplifying a full-length cDNA for u-PA receptor from an endothelial cell cDNA library using the polymerase chain reaction (PCR) and oligonucleotide primers corresponding to the DNA sequence of the receptor cloned from transformed human fibroblasts (Roldan et al, EMBO J 9:467, 1990). The size of the cDNA (approximately 1,054 base pairs, bp) and the presence of a single 1.4-kilobase (Kb) mRNA transcript on Northern blot analysis predict an unglycosylated receptor protein of approximately 35 Kd. Third, synthesis of 35S-labeled 46-Kd cell surface receptor protein was inhibited when the cells were grown in the presence of tunicamycin, while the synthesis of the 36-Kd species was unaffected. Moreover, the apparent molecular mass of purified surface-labeled receptor (approximately 46 Kd) was reduced by N-glycanase. These studies suggest that the u-PA receptor on the surface of HUVEC is a glycoprotein derived from a protein of approximately 35 Kd which is similar immunologically to u-PA receptors on other cell types.

Multivariate linear discriminant function analysis on maximal exercise treadmill and angiographic data from 500 men with definite angina, 584 men with probable angina and 267 men with nonspecific chest pain identified independent predictors of presence and extent of coronary disease. We used the discriminant function to develop a clinical risk index and a clinical and exercise risk index for each patient subset. Probability curves were generated to predict the presence and extent of coronary disease. In definite angina cases, exercise testing provided more diagnostic information than clinical data alone. However, in the 10% of cases with the smallest risk indexes, half of the patients had coronary disease and one-quarter had multivessel disease. In men with probable angina, exercise testing added substantially more diagnostic information than clinical data. The probability of multivessel disease was reduced to less than 10% for 30% of patients with probable angina, an important diagnostic contribution. Exercise testing in men with nonspecific chest pain was of limited value because disease prevalence was already low.