A multicompartment mathematical model of cancer stem cell-driven tumor growth dynamics.

Tumors are appreciated to be an intrinsically heterogeneous population of cells with varying proliferation capacities and tumorigenic potentials. As a central tenet of the so-called cancer stem cell hypothesis, most cancer cells have only a limited lifespan, and thus cannot initiate or reinitiate tumors. Longevity and clonogenicity are properties unique to the subpopulation of cancer stem cells. To understand the implications of the population structure suggested by this hypothesis--a hierarchy consisting of cancer stem cells and progeny non-stem cancer cells which experience a reduction in their remaining proliferation capacity per division--we set out to develop a mathematical model for the development of the aggregate population. We show that overall tumor progression rate during the exponential growth phase is identical to the growth rate of the cancer stem cell compartment. Tumors with identical stem cell proportions, however, can have different growth rates, dependent on the proliferation kinetics of all participating cell populations. Analysis of the model revealed that the proliferation potential of non-stem cancer cells is likely to be small to reproduce biologic observations. Furthermore, a single compartment of non-stem cancer cell population may adequately represent population growth dynamics only when the compartment proliferation rate is scaled with the generational hierarchy depth.

Effect of Alzheimer's training on multicultural personal care aides.

This article reports on the first 2 years of an ongoing project that examined the efficacy of a 10-hour dementia training provided to entry-level personal care aide (PCA) trainees from the Hispanic, White, African American, and Asian communities in New York City. Participants were enrolled in a 90-hour PCA training program offered by the New York City Department for the Aging and were either recipients of public assistance, displaced employees from September 11, or recent immigrants to the United States from China. Classes were conducted in Spanish, English, and Mandarin/ Cantonese. An 11-item Knowledge of Alzheimer's Disease instrument was developed for the purposes of this project and administered before and after the dementia training and at 3 months following graduation. All groups, regardless of language, showed a significant increase in knowledge of Alzheimer's disease at the conclusion of the training and retention of this knowledge at 3 months follow-up. Age was strongly correlated with an increase in knowledge, while gender and education were not.