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Biomedical subjects

T H Kent

Publications and source records attributed to T H Kent.

53 records · Page 3Linked to original sources
PubMed1966

Fluorescent-antibody and histological study of vaccinated and control monkeys challenged with Shigella flexneri.

Formal, Samuel B., (Walter Reed Army Institute of Research, Washington, D.C.), T. H. Kent, S. Austin, and E. H. LaBrec. Fluorescent-antibody and histological study of vaccinated and control monkeys challenged with Shigella flexneri. J. Bacteriol. 91:2368-2376. 1966.-Groups of monkeys were fed four doses of a living Escherichia coli-Shigella flexneri 2a hybrid strain, and, together with control animals, were challenged with virulent S. flexneri 2a. Two experiments were carried out; in the first, the animals were challenged 10 days after and in the second, 1 month after the last vaccine dose was administered. At 48 hr after challenge, tissues were removed from the vaccinated and control animals, and examined by use of histological and fluorescent-antibody techniques. The results of this study demonstrate that the animals receiving the vaccine were protected from the tissue damage ordinarily observed after experimental challenge with virulent dysentery bacilli. The virulent challenge strain appeared to be unable to penetrate into the intestinal mucosa of immunized animals.

Animals↗
PubMed1966

Protection of monkeys against experimental shigellosis with a living attenuated oral polyvalent dysentery vaccine.

Formal, Samuel B. (Walter Reed Army Institute of Research, Washington, D.C.), T. H. Kent, H. C. May, A. Palmer, and E. H. LaBrec. Protection of monkeys against experimental challenge with a living attenuated oral polyvalent dysentery vaccine. J. Bacteriol. 91:17-22. 1966.-Virulent strains of Shigella flexneri 1b, S. flexneri 3, and S. sonnei I were mated with an Hfr strain of Escherichia coli K-12, and hybrids were selected for the xylose marker. One hybrid strain of each of the serotypes was chosen for study of their biological characteristics. Their capacity to cause a fatal enteric infection in starved guinea pigs was reduced, they failed to cause dysentery when fed to monkeys, they caused keratoconjunctivitis in the guinea pig eye, and they penetrated HeLa cells. Two doses of a polyvalent oral vaccine composed of S. flexneri 1b, 2a, and 3, and S. sonnei I hybrid strains were fed to groups of monkeys at an interval of 4 to 7 days, and they, together with controls, were challenged 10 days after the last dose with one or another of the virulent parent dysentery strains. A significant degree of protection was afforded in all vaccinated groups with the exception of one group challenged with S. flexneri 6, a component not included in the vaccine. When animals were challenged with virulent S. flexneri 2a 1 month after oral vaccination, they were also protected. The vaccine produced a rise in serum antibody, but we were not able to detect coproantibody in saline extracts of feces from animals which received the vaccine.

Animals↗
PubMed1966

Lethal gram-negative bacterial superinfection in Guinea pigs given bacitracin.

Farrar, W. Edmund, Jr. (Walter Reed Army Institute of Research, Washington, D.C.), Thomas H. Kent, and Van B. Elliott. Lethal gram-negative bacterial superinfection in guinea pigs given bacitracin. J. Bacteriol. 92:496-501. 1966.-Oral administration of a single dose of bacitracin (either 2,000 or 10,000 units) was lethal to more than 80% of guinea pigs. Within the first 12 hr, there was a 2,000-fold fall in the number of gram-positive organisms in the cecum. An increase in the number of coliform bacteria in the cecum was demonstrable within 6 hr, and, by 48 hr, these organisms had increased from the normal level of less than 100 per gram to approximately 1 billion per gram. The changes in intestinal bacterial flora were associated with development of a severe cecitis, mild ileitis, and acute regional lymphadenitis. Bacteremia, primarily due to coliform bacteria, was demonstrated in approximately 40% of the animals killed between 72 and 96 hr after administration of bacitracin. Development of this disease syndrome was suppressed by the administration of neomycin and polymyxin B, nonabsorbable antibiotics effective against coliform bacteria. The lethal disease produced by bacitracin in the guinea pig is similar to that produced by penicillin.

Journal Article↗
PubMed1965

Mitochondrial fatty acid oxidation and susceptibility to endotoxin in acute liver injury.

Farrar, W. Edmund, Jr. (Walter Reed Army Institute of Research, Washington, D.C.), Laurence M. Corwin, and Thomas H. Kent. Mitochondrial fatty acid oxidation and susceptibility to endotoxin in acute liver injury. J. Bacteriol. 90:1365-1372. 1965.-Acute liver injury was produced in guinea pigs with three chemically unrelated hepatotoxins: CCl(4), allyl alcohol, and dl-ethionine. The effects of these agents on liver morphology, susceptibility of animals to Escherichia coli endotoxin, endotoxin-inactivating ability of tissue homogenates, and substrate oxidation by liver mitochondria were studied. CCl(4) markedly reduced oxidation of all substrates studied except succinate, impaired the ability of liver homogenates to detoxify endotoxin in vitro, and increased the susceptibility of animals to the lethal effect of endotoxin by 150-fold. Allyl alcohol produced a severe morphological lesion in the liver but did not impair fatty acid oxidation by mitochondria, diminish endotoxin detoxification by liver homogenates, or greatly enhance susceptibility of the animals to endotoxin. Ethionine showed an effect intermediate between the other two agents. These findings are consistent with the hypothesis that the liver performs an important function in the detoxification of endotoxin by the oxidation of fatty acid residues in the endotoxin molecule.

Alcohols↗
PubMedDate not supplied

Evaluation of resident-in-training examination in cytopathology.

A cytopathology examination for residents was developed to determine its usefulness and ability to measure learning in cytopathology. Seventy-five resident-training programs participated in this study, which involved 143 beginning, 158 intermediate and 71 advanced residents as well as 63 pathologists and 118 cytotechnologists who considered themselves experienced practitioners. Scores increased significantly with training and practice (mean = 51%, 61%, 65%, 72% and 72%, respectively), although there was much overlap among groups. Of the 100 multiple-choice questions, the 50 involving interpretation of photographs produced the highest scores and greatest differences between advanced residents and experienced practitioners. Visual recognition and grading of cancer cells and visual recognition of normal cellular elements were the areas of greatest resident weakness. Resident recognition of verbal criteria was worse than visual recognition. Different strengths were identified for pathologists and cytotechnologists.

Allied Health Personnel↗