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Biomedical subjects

B T Lee

Publications and source records attributed to B T Lee.

At least 19 recordsLinked to original sources
PubMed1992

Copper resistance determinants in bacteria.

Copper is an essential trace element that is utilized in a number of oxygenases and electron transport proteins, but it is also a highly toxic heavy metal, against which all organisms must protect themselves. Known bacterial determinants of copper resistance are plasmid-encoded. The mechanisms which confer resistance must be integrated with the normal metabolism of copper. Different bacteria have adopted diverse strategies for copper resistance, and this review outlines what is known about bacterial copper resistance mechanisms and their genetic regulation.

Amino Acid Sequence↗
PubMed1992

Production of an extracellular polyethylene-degrading enzyme(s) by Streptomyces species.

Extracellular culture concentrates were prepared from Streptomyces viridosporus T7A, Streptomyces badius 252, and Streptomyces setonii 75Vi2 shake flask cultures. Ten-day-heat-treated (70 degrees C) starch-polyethylene degradable plastic films were incubated with shaking with active or inactive enzyme for 3 weeks (37 degrees C). Active enzyme illustrated changes in the films' Fourier transform infrared spectra, mechanical properties, and polyethylene molecular weight distributions.

Fourier Analysis↗
PubMed1991

Bacterial resistances to mercury and copper.

Heavy metals are toxic to living organisms. Some have no known beneficial biological function, while others have essential roles in physiological reactions. Mechanisms which deal with heavy metal stress must protect against the deleterious effects of heavy metals, yet avoid depleting the cell of a heavy metal which is also an essential nutrient. We describe the mechanisms of resistance in Escherichia coli to two different heavy metals, mercury and copper. Resistance of E. coli to mercury is reasonably well understood and is known to occur by transport of mercuric ions into the cytoplasmic compartment of the bacterial cell and subsequent reductive detoxification of mercuric ions. Recent mutational analysis has started to uncover the mechanistic detail of the mercuric ion transport processes, and has shown the essential nature of cysteine residues in transport of Hg(II). Resistance to copper is much less well understood, but is known to involve the increased export of copper from the bacterial cell and modification of the copper; the details of the process are still being elucidated. Expression of both metal resistance determinants is regulated by the corresponding cation. In each case the response enables the maintenance of cellular homeostasis for the metal. The conclusions drawn allow us to make testable predictions about the regulation of expression of resistance to other heavy metals.

Amino Acid Sequence↗
PubMed1991

Squamous cell carcinoma of the umbilicus associated with acquired immune deficiency syndrome.

A variety of malignancies, including hematologic malignancies, Kaposi's sarcoma, as well as adenocarcinomas and squamous cell carcinoma have been reported in association with acquired immune deficiency syndrome. Tumors of the umbilical area are unusual and can represent lesions of urachal origin. These may require extensive resection and are associated with a poor prognosis. We describe here a case of a young woman with AIDS who developed a squamous cell carcinoma of the umbilicus which suggests more than a casual relationship between these two conditions.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Cloning and characterization of cutE, a gene involved in copper transport in Escherichia coli.

The copper-sensitive/temperature-sensitive phenotype of the Escherichia coli cutE mutant has been complemented by cloning wild-type genomic DNA into the plasmid vector pACYC184 and selecting transformants on medium containing 4 mM copper sulfate and chloramphenicol. One of these complementing clones, designated pCUT1, contained a 5.6-kb BamHI fragment. This recombinant plasmid transformed cutE, allowing wild-type growth of transformants on medium containing copper sulfate. Complementation of copper sensitivity was assessed by comparing both cell survival at increased copper levels and the results of 64Cu accumulation assays. An EcoRI subclone, 2.3 kb in size, was also shown to complement cutE when cloned in both medium- and high-copy-number vectors and was completely sequenced. This clone was mapped on the E. coli physical map at 705.70 to 707.80 kb. A series of subclones was constructed from pCUT1 and used to show that the large open reading frame of the translated sequence was essential for complementation. This open reading frame has a potential upstream promoter region, ribosome-binding site, and transcriptional terminator and encodes a putative protein of 512 amino acids that contains a region showing some homology to a putative copper-binding site.

Acetyltransferases↗
PubMed1990

Leadership: by the pros, for the novice.

Leadership, communication, motivation and conflict resolution strategies shared during Leadership Day gave new meaning to these theoretical concepts. Leadership Day proved to be an effective teaching strategy for socializing our nursing leadership students into the real world of today's nursing. This united effort between leaders in practice and leaders in education enhanced the success of this proactive approach. The presenters' personification of nursing leadership and management concepts, as well as the descriptions of specific "how to" strategies, provided a valuable ingredient for reinforcing the theoretical concepts. Leadership Day was so successful that we began making plans immediately to expand the event to include all senior nursing students the following year.

Education, Nursing, Baccalaureate↗
PubMed1990

Enhancing the success of NCLEX-RN retesters.

The widely recognized shortage of nurses, together with uncertain trends in nursing school enrollments, poses a dilemma for the health care industry. This dilemma is aggravated by the loss from the work force of graduate nurses who fail the registered nurse licensure examination. Employer institutions fail to reap the benefits of expensive recruiting and orientation, the graduate nurses face a personal and professional crisis, and a shadow is cast over their nursing school. Out of mutual concern, a tertiary care hospital and its affiliated university school of nursing collaborated to develop a model for a clinically based remedial program to increase the likelihood of passing a licensure retest. Developmental aspects and advantages of this model are described. Issues for consideration prior to implementation of such a program are discussed.

Education, Nursing, Continuing↗
PubMed1988

Leadership in action: students learn with resource persons.

The faculty maintain close contact with the resource persons and are aware of their interaction with students on a weekly basis. Faculty and resource persons exchange observations, assessments, suggestions and problems they have either anticipated or experienced. The resource persons report that as students gain from the experiences, so do they. In particular, resource persons state interactions with students have stimulated them to increase their own clinical inquiry. A head nurse, functioning as a resource person, recently told the members of the Nursing Curriculum Committee she wished she had had such a course seven years ago when she was a senior in the program (S. Collier, personal communication, October 1987). She further elaborated that the learning opportunities she sees students experiencing today would have been invaluable to her and her peers as they began their professional nursing careers. We, the authors, believe individual learning opportunities with nurse leaders as resource persons is a unique, invaluable experience for nursing leadership students. These interactions provide a variety of learning opportunities sufficient for undergraduate students to develop beginning leadership skills, while also narrowing the education-practice gap. These experiences enhance the students' orientation to "real-world" nursing leadership and management. Students recognize the uniqueness of this teaching-learning strategy and value the time spent with resource persons. They frequently report never dreaming "that such problems have to be dealt with." They agree that learning with resource persons provides an essential ingredient for reinforcing the theoretical concepts of nursing leadership and putting classroom lectures into action.

Curriculum↗
PubMed1985

Inducible plasmid-mediated copper resistance in Escherichia coli.

The copper resistance in Escherichia coli determined by plasmid pRJ1004 is inducible. The level of resistance is proportional to the inducing dose of copper. The level of copper resistance in induced and uninduced cells changes with the growth phase of the culture. Induced resistant cells accumulate less copper than uninduced cells, so that reduced accumulation may be the mechanism of resistance. We propose that the inducible plasmid-coded copper resistance interacts with the normal metabolism of the cell to protect against toxic levels of copper while allowing continued operation of copper-dependent functions.

Copper↗
PubMed1979

Effect of bacteriophage C5 on ultraviolet light survival in Pseudomonas aeruginosa.

Bacteriophage C5 of Pseudomonas aeruginosa is able to reactivate ultraviolet (u.v.)-irradiated phage E79 in coinfection experiments and decrease the u.v.-sensitivity of a host-cell reactivation deficient mutant. These properties suggest that phage C5 has a gene(s) which is involved in the repair of u.v.-damaged DNA. The isolation of two u.v.-sensitive mutants of C5 supports this hypothesis.

Bacteriophages↗
PubMed1979

Effect of repair deficiency and R plasmids on spontaneous and radiation-induced mutability in Pseudomonas aeruginosa.

The effect of R plasmids on spontaneous and radiation (ultraviolet and gamma)-induced mutability in Pseudomonas aeruginosa was studied in strains containing the radiation-sensitive markers polA3 or rec-2 and the revertable auxotrophic markers hisO27 and trpB1. In the absence of an R plasmid, the radiation-induced mutability was dependent on the recA+ genotype and independent of the polA+ genotype, whereas spontaneous mutability was similar in all genetic backgrounds. R plasmids pPL1, R2, and pMG15 increased the ultraviolet radiation survival and ultraviolet-induced mutability of wild-type and polA host cells but did not alter either effect in a recA mutant. These R plasmids also increased the gamma radiation survival and gamma-induced mutability of wild-type host cells bud pMG15 also enhanced the level of spontaneous mutagenesis in wild-type host cells but not in a polA or recA mutant. These data suggested that a common plasmid gene product(s) may participate in various recA-dependent, error-prone deoxyribonucleic acid repair pathways of P. aeruginosa. The properties of a mutant R plasmid, pPL2, originally selected because it lacked enhanced ultraviolet-induced mutability, supported this conclusion.

Alleles↗
PubMed1978

R plasmids which alter ultraviolet light-sensitivity and enhance ultraviolet light-induced mutability in Pseudomonas aeruginosa.

R plasmids pMG1, R2, R931 and pMG15 increased the survival of Pseudomonas aeruginosa exposed to ultraviolet radiation (u.v.) in the wild type, and uvr and polA mutants but did not alter the u.v.-response of a recA mutant. The R plasmid RPL11 reduced u.v.-survival in the wild type, and uvr and polA mutants but did not alter the u.v.-response of a recA host. All the plasmids enhanced the level of spontaneous and u.v.-induced back mutation (Trp+) in a trpB1 strain. The effect of sublethal concentration of sodium arsenite following u.v.-irradiation was examined. It was concluded that in strains trpB1(pMG1) and trpB1(R931), u.v.-protection is determined by a recA+-dependent, arsenite-sensitive repair pathway, whereas in strains trpB1(R2) and trpB1(pMG15), u.v.-protection is determined by a recA+-dependent, arsenite-insensitive step in DNA repair.

Arsenic↗