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Biomedical subjects

G C Walker

Publications and source records attributed to G C Walker.

211 records · Page 12Linked to original sources
PubMed1965

Effects of a combination of atropine, metaraminol and pyridine aldoxime methanesulfonate (AMP therapy) on normal human subjects.

Four hundred and seventeen medical students at the University of Toronto were used as both subjects and observers in a series of double-blind experiments to determine possible toxic effects following oral ingestion of various combinations of 2 mg. atropine, 10 mg. metaraminol and 1 g. pyridine aldoxime methanesulfonate (P(2)S). Heart rate, blood pressure, pupil diameter, and visual accommodation were measured before and at 20-minute intervals after drug administration for 100 minutes. A visual and memory perceptual test (Mackworth) was performed before and 100 minutes after drug ingestion.No toxic effects were observed following administration of the triple combination of atropine, metaraminol and P(2)S (AMP therapy). The AMP combination might be useful prophylactically for persons facing exposure to organophosphorus anticholinesterase compounds. It must not be considered an adequate substitute for treatment should poisoning occur.

Atropine↗
PubMedDate not supplied

Complementation of a pKM101 derivative that decreases resistance to UV killing but increases susceptibility to mutagenesis.

The drug resistance plasmid pKM101 makes Escherichia coli resistant to the lethal effects of ultraviolet (UV) irradiation and more susceptible to mutagenesis by a variety of agents. The plasmid operon responsible for increasing mutagenesis has been termed mucAB (Mutagenesis, UV and chemical). We have isolated a derivative of pKM101 called pGW1975 which makes cells more sensitive to killing by UV but which retains the ability of pKM101 to increase susceptibility to methyl methanesulfonate (MMS) mutagenesis. pGW1975 increases UV mutagenesis less than pKM101 in a uvrA+ strain but more than pKM101 in a uvrA- strain. muc- point and insertion mutants of pKM101 and pGW1975 complement to restore the plasmid-mediated: (i) ability to reactivate UV-irradiated phage, (ii) resistance to killing by UV, and (iii) level of susceptibility to UV mutagenesis. We have identified a 2.0 kb region of pKM101 which is responsible for the complementation and which maps counterclockwise of mucAB.

Bacterial Proteins↗
PubMedDate not supplied

New mutations in cloned Escherichia coli umuDC genes: novel phenotypes of strains carrying a umuC125 plasmid.

The umuDC locus of Escherichia coli is required for most mutagenesis by UV and many chemicals. Mutations in E. coli umuDC genes cloned on pBR322-derived plasmids were isolated by two methods. First, spontaneously-arising mutant umuDC plasmids that failed to confer cold-sensitive growth on a lexA51(Def) strain were isolated by selection. Second, mutant umuDC plasmids that affected apparent mutant yield after UV-irradiation in a strain carrying umuD+C+ in the chromosome were isolated by screening hydroxylamine-mutagenized umuD+C+ plasmids. pBR322-derived umuD+C+ plasmids inhibited the induction of the SOS response of lexA+ strains as measured by expression of din::Mu dl(lac Ap) fusions but most mutant plasmids did not. Mutant plasmids defective in complementation of chromosomal umuD44, umuC36, or both were found among those selected for failure to confer cold-sensitivity, whereas those identified by the screening procedure yielded mostly mutant plasmids with more complex phenotypes. We studied in greater detail a plasmid, pLM109, carrying the umuC125 mutation. This plasmid increased the sensitivity of lexA+ strains to killing by UV-irradiation but was able to complement the deficiencies of umuC mutants in UV mutagenesis. pLM109 failed to confer cold-sensitive growth on lexA(Def) strains but inhibited SOS induction in lexA+ strains. The effect of pLM109 on the UV sensitivity of lexA(Def) strains was similar to that of the parental umuD+C+ plasmid. The mutation responsible for the phenotypes of pLM109 was localized to a 615-bp fragment. DNA sequencing revealed that the umuC125 mutation was a G:C----A:T transition that changed codon 39 of umuC from GCC----GTC thus changing Ala39 to Val39. The implications of the umuC125 mutation for umuDC-dependent effects on UV-mutagenesis and cell survival after UV damage are discussed.

Alleles↗
PubMedDate not supplied

Genetic mapping of symbiotic loci on the Rhizobium meliloti chromosome.

To facilitate genetic analyses of Rhizobium meliloti genes that are involved in symbiosis, we determined the map positions of 11 symbiotic loci on the R. meliloti chromosome by using a combination of the Tn5-Mob conjugational transfer method described by Klein et al. (S. Klein, K. Lohmann, G. C. Walker, and E. R. Signer. J. Bacteriol. 174:324-326, 1992) and co-transduction of genetic markers by bacteriophage phi M12. Loci involved in effective nodule formation (fix-379, fix-382, fix-383, fix-385, and fix-388), polysaccharide synthesis (exoR, exoS, exoC, and ndvB), nodule invasion (exoD), and nitrogen regulation (ntrA) were ordered with respect to previously mapped markers and each other. The positions of two other loci, degP and pho-1, were also determined.

Chromosome Mapping↗
PubMedDate not supplied

Nursing faculty practice in the Houston Linkage Model: administrative and faculty perspectives.

The authors describe a model for the development and implementation of faculty practice, focusing on administrative and faculty parameters of concern in its establishment. Administrative parameters include mission and purpose, benefits to nursing education and nursing service, contractual arrangements, legal issues, use of revenues, and evaluation. The case example illustrates faculty concerns and mentorship, maintenance of clinical skills, patient care, facilitation of research for promotion/tenure, and benefits.

Contract Services↗
PubMedDate not supplied

The Houston Linkage Model 1992; an update.

The authors provide an update on the development of an innovative model to promote faculty practice. Since its inception, the model has become more sophisticated and has more than tripled its revenues to the school of nursing. Faculty practice is an integral part of the teaching programs and has been the impetus for increased research productivity among faculty members. The authors discuss model changes, including the management of revenues and decentralized control of funds.

Efficiency, Organizational↗
PubMedDate not supplied

Measurement of locus of control in cocaine abusers.

Although the course of recovery for cocaine abusers is particularly problematic, there has been little investigation of perceptions of control in this population. The purposes of this study were (1) to develop an instrument that would measure specific expectancies of control in cocaine abusers, and (2) to examine the relationship between specific and generalized expectancies of control in these subjects. Rotter's I-E scale and a modification of the Drinking-Related Locus of Control (DRIE) scale were administered to 40 cocaine abusers in their first week of treatment. The Modified DRIE scale demonstrated adequate internal consistency and satisfactory test-retest reliability in the sample. No significant correlation was found between the Modified DRIE scale and the I-E scale, probably because of the relatively small sample size. Further validation of the Modified DRIE scale is indicated.

Adolescent↗