A database for evaluating the toxicological risk of pesticides.

This study of Overtox-DB, a computerized database for managing chemical toxicity data, is a product of the application of typical methodologies regarding information science and computer technology. The methodology applied can be reduced to three-basic elements: the collection of requirements, design, and achievement. Overtox-DB was developed by defining technological elements for managing data and its structure and by identifing the procedures and methodologies for data storage, retrieval, distribution, and standardization of many kinds of test data stored in the same format. The program stores data about chemical identification, physical and chemical properties, toxicological tests, mutagenicity, teratogenicity, carcinogenicity, and a bibliography of chemical compounds. Overtox-DB consists of five modules: experimental and bibliographic, data collection, molecular data collection, data search, and data report. The Overtox-DB user responds to a simplified set of query commands and boolean operators that interact with the system to retrieve different toxicological data (the majority of fields are defined as search fields and identify the test system, results of the assays, administration route, dose, etc.). The collected information provides an analytical characterization of biological activities for many compounds and identifies evidence possibly lacking in experimental approaches. Indeed, this database could permit a comparative evaluation with other substances and can be used for structure-activity relationship studies.

An analytical short- and long-term memory model of presynaptic plasticity.

A mathematical model, called the Learning Gate Model (LGM), that describes phenomena responsible for biological synaptic plasticity, is presented. The functionality of the model are mainly based on the work of Kandel and colleagues on the most elementary forms of learning observed in the Aplysia Californica marine mollusc. In particular, emphasis is placed on the double temporal dynamics of synaptic plasticity and the temporal specificity of classical conditioning. By properly modeling the effect of the binding of Ca++ ions to the serotonin-sensitive adenylate cyclase enzyme, it is shown how a positively accelerated learning curve can be obtained for sensitization and classical conditioning. Phenomena of spontaneous recovery and second-order conditioning are reproduced through simulations. Mathematical analyses of the temporal trace of conditioned stimulus and of the Short-Term Memory steady state are also given.

Self-report of right-left confusion in college men and women.

Self-report questionnaires of difficulty in right-left discrimination and handedness were given to 575 male and 607 female undergraduates. Significantly more men and lefthanders reported having right-left confusion frequently or all the time. The validity of such self-report measures in predicting actual performance on right-left discrimination tasks is questioned since the results, at least as a function of handedness, depended on the question asked.

The course of development of glucose intolerance in the monkey (Macaca mulatta).

Longitudinal studies of the rhesus monkey reveal a syndrome of diabetes mellitus in those that become middle-aged and obese. The sequence of events in the development of the disease progresses from normoinsulinemia with normoglycemia through stages of hyperinsulinemia followed by below normal insulin levels with hyperglycemia and glycosuria. We believe the rhesus to be an excellent nonhuman primate model for maturity-onset diabetes in humans.

Feeding behavior in monkeys with and without lesions of the hypothalamus.

In monkeys (Macaca mulatta) without hypothalamic lesions, food intake was found to increase with increasing age and body weight; however, food intake per kilogram body weight showed a decline over the same period of time. As the animals became older, the amount of food intake converted to body weight decreased dramatically (feeding efficiency). Water intake was shown to be closely coupled to food intake. Both daily food and water-intake data were highly reliable over a period of years. Monkeys with ventromedial hypothalamic lesions exhibited hyperphagia and increased feeding-efficiency ratios and eventual obesity. The obese animals developed symptoms of diabetes mellitus. Animals with lesions restricted primarily to the arcuate nucleus showed no hyperphagia but increased feeding efficiency. These animals exhibited decreased growth hormone release and a transitory elevation of serum insulin.