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Biomedical subjects

M A Lewis

Publications and source records attributed to M A Lewis.

12 recordsLinked to original sources
PubMed1992

Determination of the rate-limiting step(s) in the biosynthetic pathways leading to penicillin and cephalosporin.

This paper is a review of strategies that have been used, or that could be used, to determine the rate-limiting step(s) in the biosynthetic pathways leading to penicillin or cephalosporin. Information is summarized from published material that involves studies with low-producing strains of Penicillium chrysogenum and Cephalosporium acremonium. We also summarize information derived from some high-producing production strains. Identification of the rate-limiting step(s) was of great interest to us as the first step in a rational program to further improve antibiotic titers of these highly developed strains. A number of approaches that could be used to elucidate the rate-limiting step(s) are described herein.

Acremonium↗
PubMed1992

Accuracy in perceptions of interpersonal interactions: effects of dysphoria, friendship, and similarity.

Conflicting views of depressives' interpersonal accuracy were addressed in an investigation of the accuracy of mild depressives (dysphorics) across differing social contexts. Women who were either friends or strangers and who were either similar or dissimilar in level of dysphoria conversed about 3 topics: a neutral topic, their own disclosure of a personal problem, and their partner's disclosure. Dysphorics were not more accurate in general than nondysphorics. After self-disclosure, all women more accurately detected sympathy from a similar stranger. After the partner's disclosure, women also better detected the mood of a similar partner. When interacting with nondysphoric strangers, however, dysphorics underestimated their partner's sympathy toward them. Implications for cognitive and interpersonal theories of depression and for depressives' relationships are discussed.

Depression↗
PubMed1979

Ornithine decarboxylase activity and DNA synthesis after treatment of cells in culture with 12-O-tetradecanoylphorbol-13-acetate.

The ability of the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) to induce the enzyme ornithine decarboxylase (ODC) and to stimulate DNA synthesis was studied in four different cell types in vitro. The effects of this agent on each cell type were different: (a) in hamster embryo cells, TPA induced ODC but had no effect on DNA synthesis; (b) TPA induced ODC and stimulated DNA synthesis in BALB/c 3T3 mouse cells; (c) it did not induce ODC in human fibroblasts but did stimulate DNA synthesis; and (d) it induced neither ODC nor DNA synthesis in rat embryo fibroblasts. In contrast to the effects of TPA, ODC was induced and DNA synthesis was stimulated in all cell types by fresh serum-containing medium. Treatment of the cells with a combination of fresh medium and TPA resulted in an approximate summation of the effects of treatment with each agent alone. These results emphasize the differences in the responses of various cells to TPA. They also show that in some cells, at least, the induction of ODC and stimulation of DNA synthesis following TPA treatment can be regulated independently.

Animals↗
PubMed1978

Informed consent by children and participation in an influenza vaccine trial.

Two hundred thirteen school children, ages six to nine, were presented the opportunity to participate in an experimental trial of swine influenza vaccine. In non-directive question and answer sessions, all groups of children except one composed only of six year olds elicited all relevant information on the details of the trial and the associated risks and benefits. Forty-six per cent of the subjects declined to participate. Letters requiring informed consent of the parents were sent to the homes of the others. Almost 15 per cent of these parents agreed to their children's participation. In this setting, children initiate their own visits to the school nurse practitioner. A significant association was found between volunteering for the study and higher use of services (but not for medical reasons). Younger children and boys, regardless of their patterns of use, were less inclined to volunteer for the experiment.

Age Factors↗
PubMed1978

Objective assessment of prior air traffic control-related experience through the use of an occupational knowledge test.

The Occupational Knowledge Test (OKT) 101-B was administered to 784 air traffic control trainees who entered the FAA Academy's 16-week training course in 1976. All trainees completed the nonradar laboratory portion of the training and, in addition, completed a preemployment questionnaire. Based on responses to the questionnaire, the trainees were assigned to one of three experience groups, corresponding to groups given credit for experience using Civil Service Commission (CSC) selection procedures. It was found that the OKT was highly correlated with experience (r = 0.64) and, in addition, had a higher correlation with successful completion of the nonradar lab than did experience (r = 0.25 vs. 0.12). It was determined that use of an OKT score of 75 or above to assign extra credit would result in a failure rate of 3.1% for those receiving credit, while use of the current experience scale would result in a failure rate of 7.6% for those receiving extra credit on the CSC selection battery. The results held up for a cross-validation sample of 432 trainees who entered the Academy during 1977. Based on the results, it is recommended that an OKT score of 75 or above be used to assign extra credit for experience in the selection of air traffic controllers.

Aviation↗
PubMed1977

The potential impact of sexual equality on health.

There are major differences between the sexes in morbidity and mortality rates. At all ages males have higher death rates and are more frequently afflicted with the chronic diseases associated with considerable reductions in longevity. Trend data indicate that males have become relatively more disadvantaged during a period characterized by major advances in medicine and increased access to care. In contrast, rates of disability and use of services are higher among females. There is some evidence that these differences are associated more with behavioral than with biologic factors. Certain shifts in age-specific mortality rates reflect sex-role-related changes in behavior--e.g., increased consumption of tobacco by women and a reversal in sex mortality ratio for cancer of the lung. Changes in sex roles may affect directly, or indirectly through family dynamics, the health status of both sexes.

Acute Disease↗
PubMed1976

Isolation and characterization of two new herpes-like viruses from capuchin monkeys.

Two herpes-like viruses were isolated from capuchin monkey (Cebus apella) brain and (Cebus albifrons) spleen cell cultures, respectively. Both isolates induced similar cytopathic effects consisting of rounded and ballooned cells in the original monkey cell cultures and in a wide range of permissive cell types. Neutralizing antibody to each virus was present in serum from the capuchin monkey from which it was isolated, but the two viruses did not cross-react by neutralization. Fluorescein isothiocyanate conjugates of hyperimmune rabbit serum to one of the isolates showed an antigenic cross relationship between the two isolates. By electron microscopy, herpes-like virus particles were observed in the nucleus and cytoplasm of infected human diploid fibroblast cell cultures. Virus-infected cell cultures stained with acridine orange revealed small deoxyribonucleic acid-containing intranuclear inclusion bodies. Both viruses were inhibited by 5-fluorodeoxyuridine and inactivated by chloroform or exposure to 56 degrees C for 30 min. Antisera prepared against 16 prototype herpesviruses and cytomegaloviruses did not neutralize approximately 100 50% tissue culture infective doses of either capuchin isolate. Neutralizing antibody to the capuchin isolates was detected in sera from 8 of 17 capuchin monkeys but not in sera from 16 humans, 15 chimpanzees, and 10 spider, 6 rhesus, and 5 squirrel monkeys.

Animals↗
PubMed1975

Kids vs. commercials.

A game show with fifth and sixth graders effectively demonstrated their ability to critically evaluate television commercials about health-related products. While the family physician is in a unique position to affect future drug utilization patterns of children by counseling parents, a more active role, such as this exercise in the evaluation of TV messages, may be even more effective.

Advertising↗