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Biomedical subjects

D I Johnson

Publications and source records attributed to D I Johnson.

53 records · Page 3Linked to original sources
PubMed1984

New regulatory genes involved in the control of transcription initiation at the thr and ilv promoters of Escherichia coli K-12.

The gene ileR+, considered to encode a transacting protein involved in the regulation of the thr and ilv operons of Escherichia coli, has been cloned and localized to a 1.2 Kb BglII-SalI fragment of DNA. In strains harboring attenuation-defective fusions of lacZ to the promoter regions of the thr and ilv operons, ileR mutations lead to beta-galactosidase levels higher than those of the deattenuated parental strains. Reduced utilization of the thr and ilv promoters was observed in ileR cells harboring either ilvR+ plasmids or plasmids leading to the hyperproduction of Trp repressor. These results support the idea that ileR+ encodes a repressor protein that negatively affects the expression of the thr and ilv operons. Two additional trans-acting positive regulatory elements that act at the thr and ilv promoters have been identified by an analysis of deletion mutants. It thus appears that there exist positive as well as negative controlling elements that can act independently of attenuation to modulate the ilv and thr operons.

Cloning, Molecular↗
PubMed1983

Evidence that repression mechanisms can exert control over the thr, leu, and ilv operons of Escherichia coli K-12.

Mutants of Escherichia coli K-12 resistant to either the threonine analog DL-alpha-amino-beta-hydroxyvaleric acid or the leucine analog 5',5',5'-trifluoro-DL-leucine were isolated. One DL-alpha-amino-beta-hydroxyvaleric acid-resistant mutant strain, designated SP572, constitutively expressed the thr and ilv operons. The mutant allele, avr-16, was localized between trpR and the thr operon at min 0. The wildtype allele of avr-16, designated ileR, is trans dominant. One 5',5',5'-trifluoro-DL-leucine-resistant mutant strain, designated FLR9, expressed the leu and ilv operons constitutively. The mutant allele, flr-9, is linked to entA at min 13. The constitutive expression of the thr, leu, and ilv operons in mutants avr-16 and flr-9 was partly reversed in cells harboring a plasmid, which leads to elevated levels of the trpR gene product, the Trp aporepressor protein. Operator-like sequences situated upstream from the transcription startpoints of the thr, leu, and ilv operons are plausible candidates for targets of systems of repressor-operator control functioning in parallel with attenuation.

Chromosome Mapping↗
PubMed1981

Pre-issue assessment and counselling as a component of hearing-aid provision.

Historically hearing-aid uptake and use in the United Kingdom has been poor. One contributory factor is believed to have been lack of basic knowledge about hearing loss and the benefits and problems of amplification. The scheme operating in South Manchester is described, wherein potential hearing aid users receive counselling both before and after the provision of the aid. The pre-fitting interview is partly for assessment purposes--determining the communication problems of the individual and family in order that the most appropriate assistance can be provided--and partly for counselling purposes, including attitude modification (if appropriate) and development of realistic expectations. The post-fitting counselling utilizes selected and trained volunteers who visit hearing-aids users in their homes at carefully chosen intervals. Additionally the great majority (95%) of hearing-aid users are reviewed by the Hearing Therapist at the Clinic about 1 month after issue. Evidence from Studies carried out in Manchester suggest that such a service considerably increases both use of and satisfaction with hearing aids.

Attitude↗
PubMed1979

Inhibition of carboxypeptidase A catalyzed peptide hydrolysis by 3-phenylpropanoate at activating and nonactivating substrate concentrations.

The carboxypeptidase A catalyzed hydrolyses of five structurally related dipeptide substrates in the presence of the inhibitor 3-phenylpropanoate have been studied. At nonactivating substrate concentrations, 3-phenylpropanoate is a mixed inhibitor of carbobenzoxyglycyl-L-phenylalanine hydrolysis and a noncompetitive inhibitor of the hydrolyses of benzoylglycyl-L-phenylalanine, cinnamoylglycyl-L-phenylalanine, hydrocinnamoylglycyl-L-phenylalanine, and acetylglycyl-L-phenylalanine. When carbobenzoxyglycyl-L-phenylalanine and benzoylglycyl-L-phenylalanine exhibit substrate activation, inhibition by 3-phenylpropanoate is mixed but appears to be mostly competitive. Proposed here is a site for the binding of 3-phenylpropanoate along with a kinetic mechanism consistent with these data.

Carboxypeptidases↗
PubMedDate not supplied

Spreadsheet terminology.

Explore the source record for details and available documents.

Quality Assurance, Health Care↗
PubMedDate not supplied

Take word processing one step further.

As financial constraints are placed on departments of nursing, cost-saving solutions must be found. Even as budgets shrink, state and federal agencies create standards that often are more easily tracked with flowsheets and forms. In the past, typesetters were contacted for form production. Today, in-house desk-top publishing can help to reduce costs. The tools may already be available in the word processor currently used. With a little time spent learning advanced features of word processors, attractive desk-top forms, newsletters, brochures, and patient information sheets can be produced. In this article, some of the features available to produce desk-top documents are discussed, as are other desk-top publishing programs.

Nursing↗