PubMed Health⌕ Search

Biomedical subjects

T McCall

Publications and source records attributed to T McCall.

5 recordsLinked to original sources
PubMed1998

Adaptation of the fluid percussion injury model to the mouse.

Fluid percussion injury (FPI) is a well-characterized experimental model of traumatic brain injury (TBI) in the rat. Many pathophysiologic consequences and mechanisms of recovery after TBI rely on neurochemical pathways that can be examined in genetically altered mice. Therefore, FPI applied to mice may be a useful experimental tool to investigate TBI at the molecular level. In the present study, we establish FPI as a viable model of TBI in the mouse by characterizing acute neurological, histopathological, and behavioral changes. Right-sided parasagittal FPI or sham treatment was administered in male C57BL/6 mice. Acute neurological evaluation revealed righting reflexes in the injured animals (p < 0.001). Deficits in spatial learning and memory were observed in the Morris water maze (MWM) 5 and 6 days after injury. A novel MWM data analysis protocol is described. The injured group (n = 18) demonstrated impaired performance in the MWM during acquisition (p < 0.05) and probe trials (p < 0.025) compared to sham animals (n = 16). At 7 days postinjury, glial fibrillary acidic protein immunohistochemistry revealed intense cortical, callosal, and hippocampal gliosis. The modified Gallyas silver degeneration stain consistently labeled cell bodies and terminals throughout the ipsilateral cortex, axons in the gray matter-white matter interface above the corpus callosum and within the corpus callosum bilaterally, and terminals and fibers in the thalamus bilaterally. Additionally, the mouse FPI model described is immediately employable in labs already using the FPI rat model with no modifications to a pre-existing FPI apparatus.

Animals↗
PubMed1997

Relating formulation variables to in vitro dissolution using an artificial neural network.

The purpose of this paper was to investigate the effect of several experimental variables on the ability of a neural network to predict in vitro dissolution rate as a function of product formulation changes. Neural network software was trained with sets of hypothetical and experimental data consisting of 4-15 formulations with known in vitro drug dissolution profiles and the ability of the trained model to recognize patterns was validated against similar formations not used to train the neural network. The effect of selected variables, e.g., number of hidden-layer nodes and iterations, as well as the use of replicate or mean data on the accuracy of the predictions was investigated. The importance of optimizing the number of hidden-layer nodes and iterations was demonstrated. The prediction error increased for validation data sets that were outside the range of the training data set. Accurate predictions were obtained with as few as four formulations in the training set, provided the formulations were carefully chosen, and the number of formulation variables were small. Also, limiting the validation set to one formulation was not sufficient to validate the neural network model. Increasing the size of the training set, or replication of the input and output data, also provided more accurate predictions. The neural network accurately predicted in vitro drug release provided the neural network variables were optimized, and the training and validation data sets were appropriately selected.

Acetaminophen↗
PubMed1992

The role of free radicals as mediators of endothelial cell injury in hyperhomocysteinemia.

Hyperhomocysteinemia has been suggested as a potent new risk factor for premature cardiovascular disease. Homocsyteine can induce endothelial cell injury but the mechanism is not understood. The purpose of this study was to evaluate the role of free radicals as potential causes of endothelial cell injury in a case-control study of obligate heterozygotes for cystathionine beta-synthase deficiency. Firstly, free radical production as measured by neutrophil chemiluminescence in obligate heterozygotes for cystathionine beta-synthase deficiency was compared with age- and sex-matched normal subjects. Secondly, the response of the cellular antioxidant system was examined by measuring the enzymes superoxide dismutase and glutathione peroxidase, their cofactors (selenium, copper), vitamin E and vitamin A in heterozygotes and normal subjects. Analyses of neutrophil chemiluminescence, vitamin A and E, glutathione peroxidase, selenium and copper showed no difference between heterozygotes and controls. While superoxide dismutase activity was higher in heterozygotes than normal subjects, the difference did not reach statistical significance and the hypothesis of excess free radical production as a mechanism of injury was not confirmed. However, further examination of superoxide dismutase activity in a larger number of subjects would be of interest.

Adult↗