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1.  Concurrent Change in Dehydroepiandrosterone Sulfate and Functional Performance in the Oldest Old: Results From the Cardiovascular Health Study All Stars Study 
The correlation between dehydroepiandrosterone sulfate (DHEAS) decline and age led to the hypothesis that DHEAS might be a marker of primary aging, though conflicting data from observational studies of mortality do not support this. We evaluated concurrent DHEAS and functional decline in a very old cohort to test if DHEAS change tracks with functional change during aging.
DHEAS and functional performance (gait speed, grip strength, Modified Mini-Mental State Examination [3MSE] score, and digit symbol substitution test [DSST] score) were measured in 1996–1997 and 2005–2006 in 989 participants in the Cardiovascular Health Study All Stars study (mean age 85.2 years in 2005–2006, 63.5% women and 16.5% African American). We used multivariable linear regression to test the association of DHEAS decline with functional decline.
After adjustment, each standard deviation decrease in DHEAS was associated with greater declines in gait speed (0.12 m/s, p = .01), grip strength (0.09 kg, p = .03), 3MSE score (0.13 points, p < .001), and DSST score (0.14 points, p = .001) in women only. Additional adjustment for baseline DHEAS attenuated the association with grip strength but did not alter other estimates appreciably, and baseline DHEAS was unassociated with functional decline.
In this cohort of very old individuals, DHEAS decline tracked with declines in gait speed, 3MSE score, and DSST score, but not grip strength, in women independent of baseline DHEAS level. DHEAS decline might be a marker for age-associated performance decline, but its relevance is specific to women.
PMCID: PMC2920580  PMID: 20466773
Aging; Biomarker; Dehydroepiandrosterone sulfate; Function
2.  Planning Models for Tuberculosis Control Programs 
Health Services Research  1971;6(2):144-164.
A discrete-state, discrete-time simulation model of tuberculosis is presented, with submodels of preventive interventions. The model allows prediction of the prevalence of the disease over the simulation period. Preventive and control programs and their optimal budgets may be planned by using the model for cost-benefit analysis: costs are assigned to the program components and disease outcomes to determine the ratio of program expenditures to future savings on medical and socioeconomic costs of tuberculosis. Optimization is achieved by allocating funds in successive increments to alternative program components in simulation and identifying those components that lead to the greatest reduction in prevalence for the given level of expenditure. The method is applied to four hypothetical disease prevalence situations.
PMCID: PMC1067333  PMID: 4999448
3.  Technical aspects of the Staphylococcus aureus teichoic acid antibody assay: gel diffusion and counterimmunoelecrophoretic assays, antigen preparation, antigen selection, concentration effects, and cross-reactions with other organisms. 
Journal of Clinical Microbiology  1981;13(2):293-300.
Because variable results are being reported from laboratories performing the teichoic acid antibody assay in patients with serious infections due to Staphylococcus aureus, we have thoroughly reviewed all technical aspects of the test. This paper reports on the importance of agar and antigen preparation in standardizing results of the assay and reducing the prevalence of false-negative and -positive tests. Once standardized, the counterimmunoelectrophoretic method is as accurate as the gel diffusion method for both initial screening and generating titers; practically, however, unless numerous tests are to be performed, the gel diffusion technique will suffice for most purposes. The cell wall of the Lafferty strain of S. aureus was used as the standard antigen in assays for serum antibodies. We studied whether it is an appropriate antigen and found that antibody titers obtained with the Lafferty strain antigen were, in three patients with endocarditis, the same as those obtained with antigens from the individual blood stream isolates. We have also confirmed that pooled human gamma globulin can be used, by back titration against newly prepared lots of antigen, to select optimal antigen concentration and is as good as more specific, higher titer serum specimens for that purpose. Finally, cell wall antigens from Staphylococcus epidermidis and a variety of streptococci may react with normal human sera, but such antigens are distinct by immunoprecipitation from those from S. aureus.
PMCID: PMC273780  PMID: 6782119

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