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Biomedical subjects

J R Walton

Publications and source records attributed to J R Walton.

At least 73 records · Page 4Linked to original sources
PubMed1975

Cell models in the study of mechanisms of toxicity.

Cell models, particularly in vitro systems, allow studies of toxicological mechanisms to be made under controlled conditions. One way that such mechanisms can be studied is by determining the reproducible changes that toxins induce, at the electron microscopic level, in the structure of cultured cells. A detailed description of such a study is given and includes preparation of the cell model, treatment of the cells, assessment of toxin-induced changes, and some general conclusions derived from experiments with this cell model. Other models which have been used for toxicological studies are also discussed with reference to advantages, limitations and potential applications.

Adult↗
PubMed1975

The systematic appraisal of cellular injury.

From a study of the ultrastructural effects of numerous injuries agents on cultured kidney and liver cells, a check-list has been drawn up which summarizes all of the changes observed in subcellular components. The checklist resembles a multiple-choice test. Its use would permit greater standardization among workers reporting ultrastructural alterations observed in injured cells. It would also increase the objectivity with which cell injury can be assessed by electron microscopy. The checklist is suitable for use in computer-based programs designed to characterize types of cellular injury and for seeking correlations in ultrastructural changes arising from different forms of treatment.

Cell Nucleus↗
PubMed1975

Activity of minocycline against Acinetobacter calcoaceticus var. anitratus (syn. Herellea vaginicola) and Serratia marcescens.

The activity of minocycline and tetracycline against 23 isolates of Acinetobacter calcoaceticus var. anitratus (syn. Herellea vaginicola) and 178 strains of Serratia marcescens was determined by disk and microdilution methods. The results indicate that minocycline is highly active against this species of Acinetobacter, all but one strain being inhibited by 0.007 mug of the antibiotic per ml. Tetracycline was also active, though to a lesser degree, against A. calcoaceticus. Of the 178 strains of S. marcescens tested, only seven (3.9%) had a minimum inhibitory concentration of 2 mug or less of minocycline per ml. Tetracycline was less active than minocycline against S. marcescens; with 2 mug of tetracycline per ml, only 2 of 152 (1.3%) strains were inhibited. At concentrations of 8 and 16 mug of minocycline per ml, which can be achieved in the urine with the usual doses, 44.9 and 63.5% of S. marcescens strains were inhibited, which implies its possible usefulness for the therapy of urinary tract infection due to this organism.

Acinetobacter↗
PubMed1975

Indirect consequences of low-level use of antimicrobial agents in animal feeds.

Antibiotics may be classified as "therapeutic" or "feed" depending on their use for treatment of disease or for promotion of growth in animals. The mechanism of growth promotion is largely unknown, but it has been shown that the specific feed additive causes defined lesions in the cell wall of Escherichia coli. This effect may sensitize the bacteria to the action of therapeutic drugs. Damage to the bacterial cell wall may also cause the bacteria to be more susceptible to the body defense mechanisms. One form of stress may be defined in terms of a disturbance of intestinal flora brought on by relocation, group mixing, change of diet, or travel. Prolonged feeding of antimicrobial agents to animals has not been shown to be responsible for the current high level of R factors in the intestinal tract of man.

Animal Feed↗