Hypochlorite converts cysteinyl-dopamine into a cytotoxic product: A possible factor in Parkinson's Disease.

The dopamine oxidation product cysteinyl-dopamine has attracted attention as a contributor to the death of dopaminergic neurons in Parkinson's disease. Treatment of cysteinyl-dopamine with hypochlorite yields an even more cytotoxic product. This product has potent redox-cycling activity and initiates production of superoxide in PC12 cells. Taurine, which scavenges hypochlorite, protects PC12 cells from cysteinyl-dopamine but not from the hypochlorite product, suggesting that the product, not cysteinyl-dopamine itself, is toxic. Furthermore, rotenone, which enhances expression of the hypochlorite-producing enzyme myeloperoxidase, increases the cytotoxicity of cysteinyl-dopamine but not of the hypochlorite product. This suggests that dopamine oxidation to cysteinyl-dopamine followed by hypochlorite-dependent conversion to a cytotoxic redox-cycling product leads to the generation of reactive oxygen species and oxidative stress and may contribute to the death of dopaminergic neurons.

Constructivist learning of anatomy: gaining knowledge by creating anatomical casts.

Educators are encouraged to provide inquiry-based, collaborative, and problem solving activities that enhance learning and promote curiosity, skepticism, objectivity, and the use of scientific reasoning. Making anatomical casts or models by injecting solidifying substances into organs is an example of a constructivist activity for achieving these goals. This report describes a student-implemented protocol for making postmortem anatomical casts of the bronchial tree and coronary arteries of rats using Silastic® sealant. The teacher facilitated this process by asking leading questions to guide the students toward the development of their own conclusions. This relatively simple and inexpensive procedure has important applications for the constructivist approach to study cardiovascular and respiratory morphology.