Search PubMed⌕ Search

Biomedical subjects

L M Frazier

Publications and source records attributed to L M Frazier.

At least 37 records · Page 2Linked to original sources
PubMed1985

Characterization of aquatic bacteria and cloning of genes specifying partial degradation of 2,4-dichlorophenoxyacetic acid.

Water samples from rivers, streams, ponds, and activated sewage were tested for the presence of bacteria which utilize 2,4-dichlorophenoxyacetic acid (2,4-D) as a sole source of carbon. Seventy percent of the attempted enrichments yielded pure cultures of 2,4-D-metabolizing bacteria. All but 1 of the 30 isolates were gram-negative rods, all but 2 were motile, and all were nonfermentative and oxidase and catalase positive. Nine isolates had DNA guanine-plus-cytosine values of 61.1 to 65 mol%. One isolate had a 67 mol% guanine-plus-cytosine value. The results suggest that these 2,4-D-metabolizing bacteria belong to the genus Alcaligenes. Fourteen of 23 isolates contained one or more detectable plasmids of about 20, 60, or 100 megadaltons. HindIII restriction fragment patterns showed these plasmids to be different from each other with one exception. Very similar restriction fragment patterns were revealed with a plasmid isolated from an Alcaligenes eutrophus strain obtained from Australia (pJMP397) and in an Alcaligenes sp. isolated in Oregon (pEML159). These two plasmids were about 56 megadaltons, had the same guanine-plus-cytosine value, were transmissable, and coded for 2,4-D metabolism and resistance to HgCl2. Hybridization of these two plasmids was demonstrated by using nick-translated 32P-labeled pJMP397. The vector pBR325 was used to clone HindIII fragments from pEML159. One cloned fragment of 14.8 megaldaltons expressed in Escherichia coli the ability to release 14CO2 from 2,4-D labeled in the acetate portion.

2,4-Dichlorophenoxyacetic Acid↗
PubMedDate not supplied

The unit of analysis error in studies about physicians' patient care behavior.

OBJECTIVE: To estimate the frequency with which patients are incorrectly used as the unit of analysis among statistical calculations in published studies of physicians' patient care behavior. DESIGN: Retrospective review of studies published during 1980-1990. ARTICLES: 54 articles retrieved by a computerized search using medical subject headings for physicians and study characteristics. Article selection criteria included the requirement that the physician should have been the correct unit of analysis. INTERVENTION: Presence of the error was determined by consensus using published criteria. MAIN RESULTS: The error was present in 38 articles (70%). The number of study physicians was reported in 35 articles (65%). The error was found in 57% of articles that reported the number of study physicians and in 95% of those that did not. The error rate was not lower among articles published more recently nor among those published in journals with higher rates of article citations in the medical literature. CONCLUSION: The unit of analysis error occurs frequently and can generate artificially low p values. Failure to report the number of study physicians can be a clue that this type of error has been made.

Data Interpretation, Statistical↗
PubMedDate not supplied

Effect of over-the-counter cimetidine on phenytoin concentrations in patients with seizures.

OBJECTIVE: To determine the effects of the maximum recommended over-the-counter (OTC) cimetidine dosage on phenytoin concentrations in ambulatory seizure patients on long-term phenytoin therapy. METHODS: Adults with seizure disorders requiring phenytoin therapy were recruited. Trough total phenytoin concentrations were measured initially and once weekly for six weeks. All assays were performed using Biotrack patient-side cartridges. After a two-week baseline period, patients took cimetidine 200 mg twice daily for two weeks. Toxicity was monitored via weekly neurologic examinations and midweek telephone surveys. Patients were asked to return to clinic weekly during a two-week cimetidine washout period. RESULTS: Nine patients entered and completed the study. All but two patients took other anticonvulsants known to interact with phenytoin (carbamazepine, n = 5; phenobarbital, n = 2). No adverse effects or changes in seizure frequency were reported. Paired Student's t-tests revealed no significant difference between serum phenytoin concentrations before (12.3+/-3.2 mg/L [mean +/- SD]) and after (12.8+/-4.0 mg/L) two weeks on the OTC cimetidine regimen. No differences were noted in estimated pharmacokinetic parameters (maximum metabolic rate, Michaelis-Menten constant) for the same time periods (paired Student's t-test, p > 0.05). The Biotrack assay had an r2 = 0.7311 (p < 0.001, two-sided) when compared with TDx. CONCLUSIONS: It is possible that the lack of change in phenytoin concentrations was a result of the low daily dosage of cimetidine used or other factors related to the "real world" setting of the study. However, the potential for a serious drug interaction occurring in patients taking long-term oral phenytoin and OTC cimetidine appears to be small.

Adult↗