Renowned virologist and member of the prestigious National Academy of Science, Peter Duesberg has argued that AIDS is not caused by HIV, but is the result of recreational and anti-HIV drugs. In this PBL case, students read Duesberg's 1999 article in Science magazine titled "HIV is Not the Cause of AIDS" as well as a response to it titled "HIV Causes AIDS" by medical researchers Dr. William A. Blattner and colleagues. Students work in groups to identify the issues as well as any terms or concepts they don't understand, then research these out of class to pool their information as they learn about AIDS and HIV.

Thirty-one-year-old Eric has begun to show signs of the debilitating and fatal neuromuscular disease, amyotrophic lateral sclerosis, also known as Lou Gehrig's disease. Students follow Eric as he is examined by his physician and then a specialist, undergoes a series of tests, and eventually is given the devastating prognosis. He is also given the news that a group of prominent scientists has begun human trials with embryonic stem cell therapy, which may offer a possible cure for his condition, and that he can participate in the experiment if he wishes. Students research and then prepare oral presentations on the perspectives of a variety of experts Eric might wish to consult as he weighs the science and ethics of his decision.

This case examines the hormonal control of the development and maturation to adulthood and the role of stress hormones in that developmental process. The case was adapted from results summarized in Maggioncalda and Sapolsky's (2002) article in Scientific American. It presents evidence for why an unusual adaptation for reproduction in subordinate male primates may have evolved as a means of reducing stress. Students are presented with data from the published studies and asked to analyze and interpret the results to formulate hypotheses. Initially developed for an upper division endocrinology course, the case has been used in an upper division comparative anatomy-physiology course, and could be used in an animal behavior or behavioral ecology course.

In this case study, students analyze a scientific study, first by analyzing news articles reporting on the research and then by reading the original research article. In working through the case, students identify the basic elements of a scientific study; evaluate the study and offer suggestions for improvement; analyze the appropriateness of the headlines of news articles in relation to their content; and compare the accuracy of information offered to the public in a news article with the information presented in a scientific paper. Designed for an introductory course in biological sciences for non-majors, the case could be used in any course that includes the study of the scientific method as well as in a scientific journalism course.

This case study on the chemistry of cocaine is in the form of a classroom discussion between a professor and her students about cocaine, its addictive properties, a search for an addiction treatment, and the chemistry involved in the synthesis of cocaine in its various forms. The case can be used to teach nucleophilic addition reactions, nucleophilic acyl substitution, and cocaine metabolism. In addition, it provides students with experience in locating, reading, and analyzing a research paper. The case was designed for the second course in a two-course sequence in undergraduate organic chemistry, but it could be adapted for medicinal chemistry classes.

This case explores the aggressive mimicry behavior of the femme fatale firefly - female fireflies in the genus Photuris that mimic the flash pattern of females in the genus Photinus in order to lure Photinus males to their death. The case consists of a series of fictionalized field book entries that are based on an article by J.E. Lloyd that originally appeared in Science in 1965, as well as a series of handouts that the instructor presents to the students for analysis and discussion in class in a progressive disclosure format.

This case study discusses conservation corridors as a means to reduce the problems of population size and isolation in a fragmented habitat. In an interrupted format, students learn what a corridor is, consider how nature preserves and corridors function, and analyze data from an article in Ecology on the use of corridors by various plant and animal species. As written, this case reviews and applies several topics from an introductory ecology and evolution class (population genetics, population ecology and island biogeography) to the problem of protecting species in fragmented habitats. It could be modified for use in environmental or conservation biology courses.

This interrupted case study presents published data on the effect of coyote removal in Texas. It was designed to help students in introductory level biology courses understand trophic level relationships and the role of keystone species. Students interpret data presented graphically and predict how changes at one trophic level may affect populations and communities at other trophic levels.

In this case study, students examine data from a number of published studies of the effects of Pacific salmon on freshwater and riparian ecosystems. The case focuses on the interesting phenomenon of spawning salmon acting as nutrient conveyor belts, transporting nutrients from the ocean upstream into freshwater spawning areas and, in some cases, even onto land, reversing the more-typical downstream movement of nutrients. As students work at analyzing and interpreting graphical data, they will also increase their understanding of the principles of biogeochemical cycling and gain an appreciation for the interconnectedness of different types of ecosystems. The topic is appropriate for any course covering ecosystem ecology including, for example, general ecology, freshwater or marine ecology, and environmental science.

This interdisciplinary case study is designed to interest general biology students as well as students of psychology and health studies. The study introduces us to the Greens, a family with a recently diagnosed autistic child. Students engage in a variety of activities to learn about the possible causative explanation for autism, its diagnosis, and treatment. A final activity is an optional writing exercise exploring the idea that there is intrinsic value in all persons' experiences, including those who are "different."

In this case study, students are given information regarding an advertisement claiming that listening to the classical music in the advertised CD set will enhance a person's cognitive skills and creativity. Students evaluate the claims and the evidence cited to support them, and then determine how they themselves might independently verify the claims. The case combines several approaches, including a directed case approach with the use of journal articles combined with lecture, individual assignments, and small group work. It was developed for a research methods course in psychology.

In this interrupted case study, students work in teams to interpret behavioral data with respect to evolutionary biology. Specifically, the case examines the behavior of alarm calling in a certain type of squirrel, Belding's ground squirrel, which was first reported by Paul Sherman in Science magazine in 1977. The case is appropriate for use in animal behavior, ecology, evolutionary biology, or introductory biology courses.

This case study was developed for a first-semester foundations course for biology majors. It is based on two conflicting reports in the scientific literature on the status of nanobacteria as living organisms in order to explore basic concepts related to the biological definition of life and the process of scientific investigation. In addition to engaging students with these topics, the case highlights the ambiguities inherent in science, and creates a forum for debate and discussion regarding the ability to arrive at "right answers."

This case study follows a young couple that is consulting with a genetic counselor about their plans to have a child. Because of their family history with cystic fibrosis, they are concerned about their chances of having a child with this genetic disease. The case study reviews the basics of Mendelian and molecular genetics in humans, briefly examines the possibilities and limitations of genetic testing, and introduces students to online databases, including OMIM, a catalog of human genetic traits. The case also requires students to practice the scientific method, including hypothesis development, experimental design, and the analysis of primary research articles. Although developed for use as an introductory unit to an upper-level genetics course, the case could be adapted for an introductory biology course, perhaps as a closing exercise to a unit on molecular genetics.

This interrupted case study is based on current research involving the global transport of polychlorinated biphenyls (PCBs). Students are asked to propose several hypotheses and experiments in an attempt to determine how PCBs are transferred globally. As the case unfolds, it becomes clear that the transport mechanism is more complicated than scientists first thought. The case requires minimal background knowledge and is suitable for major and non-major courses in biology, chemistry, and environmental science.

A longstanding belief that has it roots in Native American folklore is that the crushed leaves of jewelweed (Impatiens capensis) relieve the skin's allergic reaction to the toxin of poison ivy (Toxicodendron radicans). This case was developed for an introductory majors or non-majors biology or plant class. It first examines students' conceptions about the rash of poison ivy, what in the plant causes the rash, and how the body responds to the toxin. Then students in small groups plan an experiment using the scientific method to test the ability of jewelweed to reduce the reaction. Following a comparison of experimental designs from different groups, data from a scientific paper is presented for interpretation and analysis. An important outcome of this case is that students recognize the need for evaluating myths and misconceptions using scientific evidence.

This case study is based on the landmark paper by Paxton et al. (1996) that uncovered some of the mechanisms of protection against HIV infection. Using a progressive disclosure format, students are guided to suggest hypotheses, predict the outcomes of experiments, and compare their predictions with the paper's results. Developed for a first-year non-majors biology course, the case is appropriate for introducing students to the immune system and the human immunodeficiency virus.

"Ed Cramer" is a 47-year-old mechanical engineer who is being treated for venous thromboembolism. He was 45 when he first developed a blood clot in the lower part of his left leg and had to be hospitalized for five days. A year later, he developed a second blood clot, which almost killed him. This case study explores the physiology and treatment of venous thromboembolism, a condition which kills 60,000 people each year in the United States. The case was developed for use in graduate-level courses in medicine and pharmacy.

In this case study, students write their own "evolution stories" based on information taken from a review article by Paul Sereno on the evolution of dinosaurs published in Science magazine. In the process, they learn to distinguish between the three major groups of dinosaurs based on physical characteristics; trace the ancestry of individual dinosaur species; and interpret a complex evolutionary tree that includes extinctions, speciation events, and changes in the number of taxa over time. The case was designed for use in non-majors introductory science courses, but could also be used in majors' courses.