Shock avoidance conditioning and 3H-leucine uptake in a simple vertebrate system.

Myelencephalic grass frogs were trained to avoid shock to a forelimb, in the paradigm of Horridge. Forty-five min after training, these animals reached the criterion for conditioning faster and with fewer mistakes. Yoked control animals exhibited a slight learning deficit 45 min after receiving unavoidable shocks. Thirty min after training there was no difference in total protein content in the neuraxes of trained and yoked animals, but trained animals incorporated relatively more ³H-leucine into presumptive protein. The incorporated radio-activity was largely confined to the half of the neuraxis ipsilateral to the trained limb, but was not consistently confined to any 1 level of the neuraxis. The simplicity of this behavior and the relatively simple neuronal circuitry mediating it recommend this as a useful vertebrate model system for the study of macromolecular correlates of learning.     

Immune deficiency following thermal trauma is associated with apoptotic cell death

Thermal injury-associated specific immune deficiency occurs despite indicators of systemic activation of the lymphoid compartment. We investigated the possibility that postburn immune failure and T cell activation are causally related through activation-induced (apoptotic) cell death. The relationship between the cellular immune response and cell mortality was examined in cultures of peripheral blood mononuclear cells (PBMC) from 14 immunosuppressed patients with extensive burns (35–90% total body surface area). Impaired cellular immunity coincided with significantly reduced cell viability as ascertained by propidium iodide staining and dye reduction assays. Following stimulation with the mitogenic lectin, phytohemagglutinin (PHA), the majority of DNA in patient cultures was fragmented, suggesting the occurrence of apoptotic cell death. Even without stimulation a portion of patient cells was apoptotic as indicated by oligonucleosomal bands on agarose gel electrophoresis. Exogenous interleukin-2 or phorbol ester markedly reduced constitutive as well as PHAinduced DNA fragmentation.In situ demonstration of DNA strand breaks in freshly isolated patient PBMC, by a TdT-based labeling technique, confirmed that a larger fraction (up to 60%) of circulating lymphocytes was undergoing apoptosis on the periphery. These novel observations suggest that apoptosis may play a major role in thermal injury-related cellular immunodeficiency.     

Familial testicular cancer: interest in genetic testing among high-risk family members.

PURPOSE: This study is part of an ongoing National Cancer Institute multidisciplinary, etiologically-focused, cross-sectional study of Familial Testicular Cancer (FTC). The current report targets interest in clinical genetic testing for susceptibility to FTC. METHODS: Demographics, knowledge, health beliefs, and psychological and social factors were evaluated as covariates related to interest in genetic testing. RESULTS: The majority (66%) of 229 participants (64 affected men, 66 unaffected men, and 99 women) from 47 multiple-case FTC families expressed interest in having a genetic test within 6 months, should such a test become available. Interest was similar among the three subgroups mentioned above. Worries about insurance discrimination based on genetic test results were associated with a significantly lower interest in testing. Alternatively, participants were more likely to be interested in genetic testing if they were younger and had higher levels of family support, a physician's recommendation supporting testing, cancer distress, and a need for information to inform the health care of their children. CONCLUSIONS: This study reveals social and relationship factors that FTC survivors and their relatives considered important when contemplating the use of new genetic technologies. This is the first study describing hypothetical interest in genetic testing for familial testicular cancer.     

Hepatic iron overload in birds: Analytical and morphological studies

Hepatic iron content was determined in post mortem specimens from a wide range of avian species collected over a 12-month period. The majority (> 90%) of these specimens (n = 40) showed high iron content (up to 12 mg Fe/g tissue). The highest concentrations were associated with fibrosis and regenerative nodules. Dietary analysis indicated that the iron intake was not excessive, suggesting that iron-loading was due to enhanced intestinal absorption.     

Flow cytometric leucocyte counts

A flow cytometric method was evaluated for performing total leucocyte counts on bovine blood. Fifty blood samples from 19 healthy Holstein cows were analysed on a flow cytometer. The method involved diluting blood with either hypotonic or isotonic saline solution, lysing the red blood cells, and performing a 2-parameter analysis on the basis of cell size and cellular granularity. Leucocyte numbers were determined by creating a window on dot plots of cell size (determined by forward light scatter) vs cellular granularity (determined by the logarithm of side light scatter). Total leucocyte counts determined by flow, cytometer with either diluent were lower (p<0.01) than counts determined by use of an electronic particle counter. The correlations between electronic particle counts and flow cytometric counts using isotonic or hypotonic diluents were 0.857 and 0.458, respectively. The determination of total leucocyte counts using flow cytometry of a blood sample diluted in isotonic saline and treated to lyse red blood cells shows potential as a way for counting leucocytes.