Dietary protein and chronic toxicity of 1,2-dimethylhydrazine fed to mice.

1,2-Dimethylhydrazine-HCl (DMH-2HCl) is derived from the natural toxin cycasin, and is extensively used to induce cancers in experiments with rodents. We examined the toxicity of DMH-2HCl, incorporated into purified diets varying in protein, to determine concentrations compatible with long-term survival in B6C3H1 mice. Initial studies showed single-dose oral LD50 values (95% confidence intervals) of 26 (18-32) mg DMH-2HCl/kg body weight for males, and 60 (53-65) for females.

The implementation of a knowledge-based Pathology Hypertext under HyperCard.

A knowledge-based Hypertext of Pathology integrating videodisc-based images and computer-generated graphics with the textual cognitive information of an undergraduate pathology curriculum has been developed. The system described in this paper was implemented under HyperCard during 1988 and 1989. Three earlier versions of the system that were developed on different platforms are contrasted with the present system.

Computers and videodiscs in pathology education: ECLIPS as an example of one approach.

We have enumerated ways in which the evolving computer and videodisc technologies are being used in pathology education and discussed in some detail the particular use with which we are most familiar, text management. While it is probably premature to speculate as to how these technologies will ultimately affect pathology education, one recent trend--the convergence that seems to be developing between those working on expert consulting systems and those working primarily on educational applications--will probably influence this impact substantially. We believe that we are moving, from opposite directions, toward the same end result, namely, the use of machine intelligence to facilitate and augment human learning.

Immunologic cross-reactions between the specifically localizing cells (SLC) generated in response to sheep RBC and the red cells of other species.

Some of the lymphoid cells selectively incorporating radioactive thymidine 3 days after primary immunization with SRBC which are capable of specifically localizing in the lymph nodes of adoptively immunized syngeneic recipients challenged with SRBC (SLC-SRBC)2 are also capable of specifically localizing in lymph nodes challenged with the red blood cells of a varieth of other mammalian species. The one nonmammalian RBC tested, CRBC, failed to cross-react with SRBC by this parameter even qualitatively, although it remains possible that a feeble cross-reaction might be demonstrated with large enough experimental groups. As expected, the magnitude of the observed cross-reactions seems to vary inversely with the phylogenetic distance between the species, with ORBC showing the strongest cross-reaction (41 to 49%), ARBC showing the weakest (8 to 13%), and BRBC and HRBC occupying intermediate positions (13 to 20%).