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Biomedical subjects

B J Stewart

Publications and source records attributed to B J Stewart.

At least 19 recordsLinked to original sources
PubMed1997

The lonS gene regulates swarmer cell differentiation of Vibrio parahaemolyticus.

Vibrio parahaemolyticus differentiates from a polarly flagellated, short, rod-shaped cell known as the swimmer to the elongated, hyperflagellated, and multinucleated swarmer cell type when it is grown on a surface. The swarmer is adapted to movement over and colonization of surfaces. To understand the signal transduction mechanism by which the bacterium recognizes surfaces and reprograms gene expression, we isolated a new class of mutants defective in surface sensing. These mutants were constitutive for swarmer cell gene expression, inappropriately expressing high levels of a swarmer cell gene fusion product when grown in liquid. They showed no defect in the swimming motility system, unlike all previously isolated constitutive mutants which have defects in the alternate, polar motility system. The lesions in the majority of the newly isolated mutants were found to be in a gene, lonS, which encodes a polypeptide exhibiting 81% sequence identity to the Escherichia coli Lon protein, an ATP-dependent protease. Upstream sequences preceding the lonS coding region resemble a heat shock promoter, and the homology extends to sequences flanking lonS. The gene order appears to be clpX lonS hupB, like the organization of the E. coli locus. V. parahaemolyticus lonS complemented E. coli lon mutants to restore UV resistance and capsular polysaccharide regulation to that of the wild type. Vibrio lonS mutants were UV sensitive. In addition, when grown in liquid and examined in a light microscope, lonS mutant cells were extremely long and thus resembled swarmer cells harvested from a surface.

ATP-Dependent Proteases↗
PubMed1996

Development of use and cost measures in a nursing intervention for family caregivers and frail elderly patients.

The purpose of this pilot study was to refine and evaluate methods of measuring costs of an innovative home-health nursing intervention designed to support frail, older persons and their family caregivers. We evaluated a multifaceted strategy to collect a detailed utilization profile from 22 caregiver/care receiver dyads for hospital, ambulatory, home health, nursing home, and community services. The strategy was feasible for most participants, maximized accuracy of cost data, and minimized research burden on study participants. Lower overall costs were found in the intervention group, but the difference was not significant. Approaches to the measurement of costs in this study can serve as models for evaluating other innovations in nursing, home care, and long-term care.

Aged↗
PubMed1996

Sense of coherence as a predictor of quality of life in persons with coronary heart disease surviving cardiac arrest.

The unique contribution of sense of coherence to explained variance in quality of life was studied in 149 persons with coronary heart disease who survived cardiac arrest. Using hierarchical multiple regression, 16 predictors, including 5 social status variables related to poor health vulnerability, perceived social support, self-esteem, and 9 variables reflecting instability and work of the chronic illness trajectory, accounted for 50% of variance in quality of life. The addition of sense of coherence resulted in a 15% increment to the explained variance (total R2 = .64). As a strong independent predictor of quality of life, sense of coherence has promise as a variable that might be strengthened by nursing interventions and merits continued study.

Adult↗
PubMed1996

Vibrio parahaemolyticus FlaJ, a homologue of FliS, is required for production of a flagellin.

The flaA locus of Vibrio parahaemolyticus encodes one of the four polar flagellin genes, the flagellum-capping protein HAP2, and three additional flagellar genes. Sequence analysis downstream of the gene encoding HAP2 revealed the region to be similar to the fliD (HAP2) locus of Pseudomonas aeruginosa. The deduced protein sequences for the newly identified genes suggest that one protein belongs to the family of transcriptional regulatory proteins known to interact with sigma (54), one may be a rod component of the flagellum, and one resembles the FliS protein. fliS is an essential flagellar gene in many bacteria; however its function is not clear. The V. parahaemolyticus polar flaC flagellin gene was poorly expressed in Escherichia coli Production of FlaC was stimulated by provision of the flaA locus in trans. Dissection of this locus revealed that the fliS-like gene, flaJ, was required for increased expression of flaC. Stimulation by FlaJ occurred in E.coli mutants defective in either the master flagellar-controlling operon or the gene encoding the flagellar sigma (28). Therefore the effect of FlaJ was not mediated through flagellar proteins. Nor was it mediated through sigma (54) for enhanced FlaC production was observed in mutants with defects in the gene encoding sigma (54).

Amino Acid Sequence↗
PubMed1995

The PREP system of nursing interventions: a pilot test with families caring for older members. Preparedness (PR), enrichment (E) and predictability (P).

The PREP system of nursing interventions, designed to increase preparedness (PR), enrichment (E), and predictability (P) in families providing care to older people, was pilot tested for acceptability and preliminary effectiveness. Eleven family units were assigned to the PREP group and 11 to a standard home health control group. The PREP group scored approximately one SD higher than the control group (p < .05) on the Care Effectiveness Scale, indicating greater preparedness, enrichment, and predictability. Further, on a rating of overall usefulness, the PREP group rated their assistance from PREP nurses (M = 9.75) as significantly higher (p < .01) than the control group rated assistance from the home health nurse or physical therapist (M = 6.57). Although not statistically significant, mean hospital costs for the PREP group ($2,775) were lower than for the control group ($6,929). Results provided support for a full intervention trial.

Aged↗
PubMed1995

Evaluating teaching effectiveness.

Major reform in nursing education is underway, with increased emphasis being placed on the importance of the teacher-student relationship. An instrument for evaluation of teaching effectiveness, developed at the Oregon Health Sciences University School of Nursing, attempts to capture the student's perception of the quality of the teacher-student relationship as well as other salient aspects of teaching practices. The evaluation tool contains 26 items evaluating teaching effectiveness and 14 items that evaluate the course. The teaching effectiveness items yield five scales including: knowledge and expertise, facilitative teaching methods, communication style, use of own experiences, and feedback. Psychometric testing has been completed and there is evidence of construct validity in relation to teaching effectiveness and internal consistency reliability for the five scales.

Analysis of Variance↗
PubMed1994

Development of a radioimmunoassay method for ethynylestradiol in plasma using a monoclonal antibody.

An ethynylestradiol (EE2) radioimmunoassay method (RIA) using a monoclonal antibody (MAB) reagent is described. 76 plasma and 67 buffer blanks spiked with known concentrations of EE2 were used as positive samples. The steroid was extracted using dichloromethane method with an extraction efficiency of 78 +/- 2.6%. The plasma extracts were not purified. Separation of the free from bound tritiated EE2 was by centrifugation with dextran-coated charcoal suspension in phosphate-gelatin buffer. Within 95% confidence limits, the sensitivity of the assay was 10 pg/ml in buffer samples, and 43 pg/ml in unpurified plasma samples. The accuracy and precision of the method were lower for the plasma samples than for the buffer solutions but within accepted limits (i.e., 80-120% for accuracy, and up to 20% for precision). The mean recovery accuracy (R) of the method for measuring 38 pg/ml EE2 in buffer was 101 +/- 0.9% (n = 67), while for 2.39 pg/ml to 18.0 pg/ml EE2 in plasma was 97 +/- 12% (n = 76). The buffer solutions and plasma samples containing 600 pg/ml EE2 had a mean R of 102% (n = 18) and 90% (n = 16), respectively. The average interassay variation (%CV) between buffer samples was 14 +/- 1.2%, and between plasma samples was 19 +/- 8%. Plasma samples with 18 pg/ml and 2.39 pg/ml EE2, together with the blank negative plasma samples showed high interassay variations (CV > 20%). Except for the above samples, however, the precision of the method in all sample groups was within accepted limits. The intra-assay variation of replicate assays of a single plasma sample containing 1.2 ng/ml EE2 and 4 ng/ml levonorgestrel was 13% (n = 7). In the presence of very high concentration of closely related levonorgestrel, the R of the method was 106%. The increase in average variability (%CV) between results for the plasma samples (CV 19 +/- 8%) over that of the spiked buffer solutions (CV 14 +/- 1.2%) suggest some possible interference by co-extracted materials from plasma, for example lipids, which interfered in the ligand-antibody reactions. Further investigation may prove that a pre-assay purification of the sample, e.g., HPLC, would eliminate this interference. Nevertheless, the immunoassay described above completely eliminates the problem of cross-reactivity caused by the natural estrogens in plasma with the conventional polyclonal antibodies. It possesses an acceptable intra- and interassay variation with very high specificity to EE2.(ABSTRACT TRUNCATED AT 400 WORDS)

Antibodies, Monoclonal↗
PubMed1994

Enrichment processes in family caregiving to frail elders.

Interview and observational data obtained from caregiver-care recipient dyads were analyzed in developing a theory of enrichment that explains how some families use pleasurable or meaningful experiences in their caregiving to frail elders. The personal history and frailty trajectory of both caregiver and care recipient, the quality of the dyadic relationship, and the caregiving situation are antecedents to enrichment processes. Core elements influencing the nature of enriching events include acquiring symbolic meaning, performing activity, and fine tuning. Categories of enrichment events are customary routines and innovative routine breakers. Consequences of enrichment are relationship and identity sustenance for both caregiver and care recipient, comfort for the care recipient, and rewards of meaning for the caregiver.

Adult↗
PubMed1994

Effect of contraceptive steroid and enalapril treatment of systolic blood pressure and plasma renin-angiotensin in the rat.

Previous work has demonstrated contraceptive steroid-induced hypertension in rats. Here, we examined the relationship between steroid-induced hypertension and components of the renin-angiotensin system. Female Sprague-Dawley rats were injected s.c. with 0.2 micrograms ethynyloestradiol, 2.0 micrograms levonorgestrel, a combination of both or vehicle, six days per week. A second group of rats received 2.0 micrograms enalapril maleate, enalapril plus ethynyloestradiol or levonorgestrel, or vehicle. Systolic blood pressure increased with both ethynyloestradiol. (6 weeks, +17 mmHg; 12 weeks, +32 mmHg) and levonorgestrel (6 weeks, +24 mmHg) treatment. This effect of levonorgestrel was attenuated by co-administration of enalapril, which also reversed the hypertension seen with ethynyloestradiol. Ethynyloestradiol, but not levonorgestrel treatment caused a significant increase in plasma renin concentration, plasma renin activity, and plasma angiotensin II at both 6 and 12 weeks. Plasma renin substrate was increased by ethynyloestradiol at 3, 6 and 12 weeks, prior to the observed increase in systolic blood pressure. Combined steroid treatment had less pronounced effects. Enalapril alone or in combination with ethynyloestradiol decreased plasma renin concentration, activity and angiotensin II, and in combination with levonorgestrel decreased plasma renin concentration, substrate and activity (6 weeks only) but not angiotensin II. The data indicate a positive relationship between hypertension and the renin-angiotensin system with ethynyloestradiol, but not levonorgestrel treatment in rats.

Angiotensin II↗
PubMed1994

Establishing partnerships with family caregivers. Local and cosmopolitan knowledge.

1. The concepts of local and cosmopolitan knowledge may be used by gerontological nurses in creating partnerships with family caregivers to frail older people. 2. Local knowledge is the understanding and skills that the family brings to the caregiving situation; cosmopolitan knowledge is the understanding and skills that the gerontological nurse brings to the situation. 3. Four nursing interventions are guided by the conceptualization of local and cosmopolitan knowledge: acknowledging and affirming local knowledge when it is adequate; developing or enhancing local knowledge when it is inadequate; assisting family caregivers to apply local knowledge to problem solving; and blending local and cosmopolitan knowledge.

Aged↗
PubMed1993

Nursing intervention studies require outcome measures that are sensitive to change: Part Two.

Ohis article is the second and concluding part of a discussion of the importance of sensitivity to change in selecting an outcome measure for a study evaluating a nursing intervention. In Part One of the discussion, (Stewart & Archbold, 1992) the relative lack of attention to measurement sensitivity in the nursing and measurement literature was described. Three factors to consider in selecting an outcome measure for an intervention study were reviewed: the conceptual link between the intervention and the outcome variable, the extent to which the outcome variable is amenable to change, and content validity. In Part Two, four additional factors are discussed: construct validity, distribution of scores on the outcome measure, reliability, and correlational stability over time.

Humans↗
PubMed1993

Enterotoxigenic bacteria in the sudden infant death syndrome.

Faecal samples from 123 infants who died with sudden infant death syndrome (SIDS) and from a comparative group of 52 age-matched babies were analysed for toxigenic bacteria and their toxins. Serum samples from the SIDS infants were also analysed for these toxins. A significantly higher proportion of toxigenic bacteria and their toxins were found in faecal samples of SIDS babies than in samples from the comparative group. These toxins were also found in serum from the SIDS babies. Clostridium perfringens was found in 54 (45.4%) of 119 SIDS cases compared with 10 (19.6%) of 51 healthy babies (chi 2 = 10.1, p < 0.01); C. difficile in 33 (27.7%) of 119 SIDS cases compared with 8 (14.8%) of 54 healthy babies (chi 2 = 3.43ns, p < 0.1); Staphylococcus aureus in 12 (27.3%; 66.7% enterotoxigenic) of 44 SIDS cases compared with 12 (85.7%; non-enterotoxigenic) of 14 healthy babies (chi 2 = 14.9, p < 0.001); C. botulinum in 6 (5.0%) of 120 SIDS cases compared with 0 of 53 healthy babies (chi 2 = 2.74, p < 0.1). Campylobacter jejuni, Yersinia enterocolitica, Vibrio parahaemolyticus, salmonellae and Bacillus cereus were not detected. Heat-labile toxin, lethal to mice (HLML) was found in 32 (27.1%) of 118 SIDS faecal samples compared with 5 (10.6%) of 47 healthy babies (chi 2 = 5.24, p < 0.05); cytotoxins in 38 (30.9%) of 123 SIDS faecal samples compared with 0 of 21 of healthy babies (chi 2 = 8.8, p < 0.01) and 24 (27.6%) of 87 SIDS serum samples. C. perfringens enterotoxin was detected in 33 (34.4%) of 96 SIDS faecal extracts compared with 0 of 23 of healthy babies (chi 2 = 10.94, p < 0.001), and in 27 (24.5%) of 110 SIDS serum samples. C. perfringens alpha-toxin (presumptive) was detected in 14 (17.5%) of 80 SIDS faecal extracts compared with 0 of 17 from healthy babies (chi 2 = 3.5ns, p congruent to 0.05) and in 2 (2.3%) of 87 SIDS serum samples. C. difficile toxin was detected in four SIDS faecal samples and two serum samples. C. botulinum toxin was detected in only one of 120 SIDS faecal samples compared with none of 49 from healthy babies. Staphylococcal enterotoxins were detected in 8 (19.5%) of 41 SIDS faecal samples compared with 0 of 19 from healthy babies (chi 2 = 4.278, p < 0.05), and in 4 (10.8%) of 37 SIDS serum samples.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Characterization of mutations in divIB of Bacillus subtilis and cellular localization of the DivIB protein.

Four temperature-sensitive mutations in the divIB gene of Bacillus subtilis have been localized to the region corresponding to the C-terminal half of the 263-residue DivIB protein. Antiserum was raised to the 80% C-terminal portion lying on one side of a putative transmembrane (hydrophobic) segment, and used to examine aspects of the nature and localization of the DivIB protein in the cell. A single DivIB species of a size equal to the full-length protein encoded by the divIB gene was detected in wild-type cells. Cell fractionation studies established that DivIB is associated preferentially with the cell envelope (membrane plus cell wall), with approximately 50% being released into solution upon treatment of cells with lysozyme under conditions that yield protoplasts. Of the remaining 50%, approximately half remained firmly associated with the membrane fraction. On the basis of the 'positive-inside rule' of von Heijne (1986) it is suggested that the topology of membrane-bound DivIB is such that the long C-terminal portion is directed to the outside and the smaller N-terminal portion to the inside of the cell. DivIB in protoplasts was rapidly degraded by proteinase K under conditions where there was no general proteolysis of the cytoplasmic proteins. This is consistent with its absence from the cytoplasm, and with the predicted membrane topology. Septum positioning in a divIB null mutant, which grows as filaments at temperatures of 30 degrees C and below, was found to be normal. It appears that DivIB is needed for achieving the appropriate rate of initiation of septum formation at normal division sites. It is proposed that the C-terminal portion of DivIB, localized on the exterior surface of the membrane and in juxtaposition to the peptidoglycan, normally interacts with another protein (or proteins) to initiate septum formation.

Amino Acid Sequence↗
PubMed1993

Reports of sensorineural deafness after measles, mumps, and rubella immunisation.

There have been nine reports of sensorineural hearing loss after measles, mumps, and rubella (MMR) immunisation. In three cases the deafness was unrelated to MMR immunisation. In six cases the cause was unknown and MMR remained a possible aetiology. Any risk associated with attenuated viruses must be weighed against the risks of the natural diseases.

Child↗
PubMed1992

Nursing intervention studies require outcome measures that are sensitive to change: Part One.

In selecting an outcome measure for a study evaluating a nursing intervention, the criterion of sensitivity to change should predominate. Researchers commonly justify their choice of outcome measures for experiments based on such psychometric criteria as high internal consistency reliability and patterns of correlations reflecting convergent and discriminant validity. Although such criteria are appropriate for measures to assess individual differences, they are insufficient when the measures will be used for intervention studies. Researchers may need to develop new measures that are tailored for experimental studies if existing measures are valid mainly for the assessment of individual differences. In this first portion of a two-part article, three of seven factors to consider in selecting an outcome measure for an intervention study are outlined and recommendations for application of principles of reliability and validity in the context of sensitivity to change are given.

Humans↗
PubMed1990

Mutuality and preparedness as predictors of caregiver role strain.

Data from 78 older persons and their family caregivers were obtained at 6 weeks and 9 months after hospital discharge. Hierarchical multiple regression was used to determine whether mutuality and preparedness for caregiving were related to lower levels of caregiver role strain. The results indicated that, after controlling for five other variables commonly found to be related to caregiver role strain, mutuality and preparedness ameliorated some but not all aspects of role strain.

Adult↗