Arthropod envenomations.

Millions of arthropods surround us every day, but only a few are medically harmful. Knowledge of the habits and habitats of known venomous arthropods is certainly advisable for the prudent person in areas of known infestation as a preventive measure. Arthropod envenomations probably produce much less mortality than previously thought, but the potential for severe effects of direct envenomation or allergic response exists with some species, and these events must be approached as true medical emergencies.

Evaluating exposures to plants.

Exposures to plants generate an exceptional amount of public concern, especially plant ingestions by children. Most clinical problems, however, involve older age groups as a result of experimentation with or overt abuse of plant parts and extracts. Of mounting concern is the sometimes uninformed and massive use of herbal preparations, currently widely available and in popular vogue.

Reptile envenomations.

Venomous reptiles are distributed in select habitats in temperate and tropical areas of the world with few geographical exceptions, and have adapted to not only terrestial existence, but to arboreal and aquatic environments as well. Venomous snakes are found in the families Colubridae (fixed and rear fanged snakes), Elapidae (fixed and front fang snakes), Hydrophiidae (sea snakes), Viperidae (Old World vipers) and Crotalidae (pit vipers). Venomous lizards are found in the United States and Mexico, and comprise the family Helodermatidae.

Envenomation by the scorpion Centruroides sculpturatus.

Envenomation by the scorpion C. sculpturatus can be life threatening. The action of the venom is to produce prolonged and excessive firing of neuronal axons which results in a wide variety of signs and symptoms.

Electrophysiology and morphology of the developing hippocampus of fetal rabbits.

The pyramidal neurons of fetal rabbit hippocampus were studied using intracellular electrophysiological techniques in in vitro slice preparations. Correlative light and electron microscopic analyses were carried out on hippocampus during the 21st through the 29th day of fetal gestation. In intracellular experiments, neurons with all-or-none action potentials and near-adult level resting potentials were found even in the youngest preparations.

Development of rabbit hippocampus: anatomy.

The postnatal development of the CA1 region of rabbit hippocampus was studied using a variety of light and electron microscopic (EM) techniques. Nissl and Golgi stains showed high cellular density, small cell soma area, and sparse dendritic branching in neurons of immature animals (less than 1 week old); dendritic spines were also relatively infrequent during this period. Cell branching and spine frequency reached near-adult levels by 3 weeks, with the major area of hippocampal expansion seen in the apical dendritic layer.