Search PubMed⌕ Search

Biomedical subjects

R G Jones

Publications and source records attributed to R G Jones.

134 records · Page 8Linked to original sources
PubMed1967

The relationship of 4-hydroxybenzoic acid to lysine and methionine formation in Escherichia coli.

1. A multiple aromatic mutant, Escherichia coli 156:53D2, required 4-hydroxybenzoic acid for rapid aerobic growth on a number of carbon sources. 2. In the absence of 4-hydroxybenzoic acid aerobic growth was stimulated by a mixture of lysine and methionine and by succinate. The influence of the amino acids is attributed to a sparing of succinyl-CoA. 3. Low activities of both alpha-oxoglutarate dehydrogenase and fumarate reductase were found in organisms grown aerobically without 4-hydroxybenzoate and consequently both mechanisms known for the formation of succinate were impaired. 4. The low fumarate-reductase activity in these organisms was due to repression of enzyme synthesis by aeration and not to enzyme inactivation. In contrast lactate dehydrogenase and ethanol dehydrogenase were induced. This is interpreted as the appearance of alternative routes of NADH oxidation when electron transfer to oxygen is impaired. 5. The activities of the other tricarboxylic acid-cycle enzymes tested were little influenced by 4-hydroxybenzoate deficiency, although anaerobiosis resulted in a fall in activity.

Alcohol Oxidoreductases↗
PubMed1967

Ubiquinone deficiency in an auxotroph of Escherichia coli requiring 4-hydroxybenzoic acid.

1. Escherichia coli 156:53D2 synthesized ubiquinone only when the growth medium was supplemented with 4-hydroxybenzoate acid. 2. Little or no vitamin K(2) was formed by the mutant under the growth conditions employed, in contrast with wild-type strains. 3. In the mutant ubiquinone deficiency was correlated with low respiration and with low particulate NADH-oxidase and NADH-cytochrome b(1)-reductase activity. 4. Preincubation of ubiquinone-deficient particles with ubiquinone-30 largely restored the NADH-oxidase and NADH-cytochrome b(1)-reductase activities. 5. Various NADH-dye-linked reductases which may be associated with NADH dehydrogenase were not affected by the absence of ubiquinone. 6. The succinate-oxidase complex was less affected than the particulate NADH oxidase by ubiquinone deficiency. 7. A pathway for electrons in the NADH-oxidase complex of the auxotroph of E. coli is proposed and its relationship to the pathway in the wild-type strain is discussed.

Benzoates↗
PubMedDate not supplied

Systematic assessment of World Wide Web materials for medical education: online, cooperative peer review.

OBJECTIVE: : To develop a generic methodology for the online assessment of medical education materials available on the World Wide Web and to implement it for pilot subject areas. DESIGN: An online questionnaire was developed, based on an existing scheme for computer-based learning material. It was extended to involve five stages, covering general suitability, local suitability, the user interface, educational style, and a general review. It is available on the Web, so expert reviewers may be recruited from outside the home institution. The methodology was piloted in three subjects areas--clinical chemistry, radiology, and medical physics--concentrating initially on undergraduate teaching. MEASUREMENTS: The contents of completed questionnaires were stored in an offline database. Selected fields, likely to be of use to students and educators searching for material, were input into an online database. RESULTS: The online assessment was used successfully in clinical chemistry and medical physics but less well in radiology. Fewer resources were found to fit local needs than expected. CONCLUSION: The methodology was found to work well for topics where teaching is highly structured and formal and is potentially applicable in other such disciplines. The approach produces more structured and applicable lists of resources than can be obtained from search engines.

Computer Communication Networks↗