Problem-based Learning: Potential and Implementation Issues

This study addresses the issues associated with the application of problem-based learning, examines the key design dimensions of a problem-based learning course and considers the implications of problem-based learning for learners and educators.     

Biological Basis of Chemical Carcinogenesis: Insights from Benzene

Benzene is one of the best studied of the known human carcinogens. It causes leukemia in humans and a variety of solid tumors in rats and mice. Decades of research on benzene metabolism, pharmacokinetics, cytotoxicity, genotoxicity, and carcinogenicity in vivo and in vitro are starting to converge on a small set of overlapping hypotheses about the most probable biological mechanisms of benzene toxicity and carcinogenicity. Although there is still room for surprises, it seems likely that the ultimate answer to the mystery of how benzene exerts its multiple effects will consist of elaborations and extensions of one or more of the current hypotheses. This paper reviews benzene health effects and biology, showing how various aspects of metabolism and cytotoxicity fit together with genotoxic and nongenotoxic effects to help explain how benzene may cause cancer. Its goals are: (i) to introduce the qualitative biological background needed for detailed quantitative dose-response modeling of benzene cancer risks; and (ii) to survey a rapidly evolving area of research that shows promise of producing fundamental insights into the mechanisms of toxicity and carcinogenesis for several chemicals--benzene and perhaps phenols, catechols, and other hydroxylated ring hydrocarbons--in the decade ahead.     

MARRIAGE AND FAMILY THERAPISTS AND THE CLERGY: A NEED FOR CLINICAL COLLABORATION, TRAINING, AND RESEARCH

This article calls for greater collaboration between clergy and marriage and family therapists. It spells out the reasons for potenial collaboration and suggests some specific ways it can occur. Marriage and family therapists acknowledge the highest rates of religious involvement of any metntal health profession, placing them in a unique position to be involved in the continuing education of clergy. There is a clear need for research to understand how marriage and family therapists and clergy can more effectively work together. The dearth of research, training, and collaboration between the two vocations is all the more unfortunate given the clear evidence of the importance of religion in the personal lives of the clients we serve.     

Random Drug Testing and Religion*

Research recently has begun to examine the link between religion and social control. It has been noted that religion, in particular Protestant conservatism, does play a role in shaping public opinion, and as a result, public policy on crime, crime control, and justice. The present research examines the issue of public support for random drug testing by focusing on the role of religion, specifically religious affiliation, in shaping public opinion. Analysis of survey data from a city in the Southwest identifies two separate dimensions of public support for random drug testing–a utilitarian dimension that is grounded in safety concerns, along with a normative dimension that reflects conservative moral beliefs, including a concern with the “evil” of drugs. Evidence from the data also indicates that conservative Protestants, compared to liberal-moderate Protestants, Catholics, and those with no affiliation, display higher levels of normative-based support for random drug testing. Researchers are encouraged to further explore the role of religion in shaping public support for the development of drug policies and other more general social control policies.     

Extending the Stochastic Two-Stage Model of Carcinogenesis to Include Self-Regulation of the Nonmalignant Cell Population

One of the challenges of introducing greater biological realism into stochastic models of cancer induction is to find a way to represent the homeostatic control of the normal cell population over its own size without complicating the analysis too much to obtain useful results. Current two-stage models of carcinogenesis typically ignore homeostatic control. Instead, a deterministic growth path is specified for the population of "normal" cells, while the population of "initiated" cells is assumed to grow randomly according to a birth-death process with random immigrations from the normal population. This paper introduces a simple model of homeostatically controlled cell division for mature tissues, in which the size of the nonmalignant population remains essentially constant over time. Growth of the nonmalignant cell population (normal and initiated cells) is restricted by allowing cells to divide only to fill the "openings" left by cells that die or differentiate, thus maintaining the constant size of the nonmalignant cell population. The fundamental technical insight from this model is that random walks, rather than birth-and-death processes, are the appropriate stochastic processes for describing the kinetics of the initiated cell population. Qualitative and analytic results are presented, drawn from the mathematical theories of random walks and diffusion processes, that describe the probability of spontaneous extinction and the size distribution of surviving initiated populations when the death/differentiation rates of normal and initiated cells are known. The constraint that the nonmalignant population size must remain approximately constant leads to much simpler analytic formulas and approximations, flowing directly from random walk theory, than in previous birth-death models.(ABSTRACT TRUNCATED AT 250 WORDS)     

Problem characteristics, decision processes and evaluation activity: a preliminary study of mental health center directors

This article reports on the results of a preliminary study on the characteristics of problems and problem solving in mental health centers. The major findings were that directors were generally quite satisfied both with the available level of information intended to help them make decisions, and with their ability to make good, even optimal, decisions. Much of this confidence resulted from the use of assumptions about the problems which reduced the need for empirical information. The problem solving process was highly dynamic and interactive, with changes over time in the characteristics of problems, constraints and alternative solutions. The directors played an active role in attempting to foster and influence the direction of many of these instabilities. Some implications for evaluation and research are discussed.