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Biomedical subjects

D Goldenberg

Publications and source records attributed to D Goldenberg.

At least 73 records · Page 4Linked to original sources
PubMed1994

Genetic and biochemical analysis of IHF/HU hybrid proteins.

Integration host factor (IHF) is a small heterodimeric DNA-binding protein of E coli composed of two subunits, alpha and beta, encoded by the himA and hip genes, respectively. IHF binds to DNA at a consensus sequence and bends DNA. HU protein, encoded by the hupA and hupB genes, is similar to IHF except that it does not bind to a specific DNA sequence. To investigate the protein determinants for IHF specificity we exchanged progressively longer segments from the C-terminus of Hip with those of HupA, and followed the activity in vivo and in vitro of four such IHF/HU hybrids. Replacement of 11 residues from the C-terminal alpha helix of Hip by the complementary eight residues of HupA (hybrid 1), had only minor effects on the DNA binding activity of the protein. As progressively longer segments of Hip were replaced by HupA, a precipitous decrease in IHF activity was observed. The hybrid with the longest substitution, hybrid 4, was totally inactive in vivo and could not be purified. None of the hybrid proteins could complement HU activity. Comparing the activities of hybrid 1, hybrid 2 and IHF point mutants, led us to conclude that the structural integrity of the C-terminal alpha helix and its spatial position, but not its amino acid sequence, are important for DNA binding specificity. We favor the hypothesis that alpha helices 3 of both IHF subunits interact with the body of IHF so as to anchor the arms. This interaction stabilizes the arms to permit DNA binding specificity. Thus the C-termini of IHF influence, in an indirect way, the recognition of specific sites on DNA.

Amino Acid Sequence↗
PubMed1993

Genetic and biochemical analysis of the integration host factor of Escherichia coli.

Integration host factor (IHF) is a small, heterodimeric DNA-binding protein of Escherichia coli composed of two subunits, alpha and beta, encoded by the himA and hip genes, respectively. IHF binds to the minor groove at a consensus sequence and bends DNA. We mutagenized the hip gene and studied the activity of the mutant IHF proteins in vivo and in vitro. Substitutions at the C-terminal alpha-helix (alpha-helix 3) reduced IHF activity and relaxed the specificity to DNA without abolishing the ability of IHF to bend DNA. These results indicate that the C-terminal region of Hip participates in determining IHF specificity. Alanine substitutions in beta-strands 2 and 3 generally had no effect on IHF activity in vivo suggesting that individually, many of these residues make only small contributions to the binding of IHF to DNA. Replacing the single amino acid of Hip that differs from HU in a highly conserved region of the arm did not affect IHF activity. This finding led us to conclude that this region of Hip does not contribute to specific DNA recognition by IHF. The binding of IHF to DNA is probably not restricted to one domain, but requires the co-operative participation of a number of regions of the protein.

Bacterial Proteins↗
PubMed1993

Attitudes of practicing nurses as predictors of intended care behavior with persons who are HIV positive: testing the Ajzen-Fishbein Theory of Reasoned Action.

The purpose of this descriptive correlational study was to examine practicing nurses' attitudes, subjective norms, and intentions to care for HIV positive patients, using the Theory of Reasoned Action. One hundred and forty-one subjects completed a questionnaire developed according to guidelines described by Ajzen and Fishbein (1980). Consistent with the theory, nurses' attitudes and subjective norms were found to be significant predictors of intentions to care for persons who are HIV positive (R2 = 0.27). Personal beliefs found to discriminate between intenders and nonintenders were those related to possible consequences for self, family, and friends, but not job-related consequences. Normative beliefs which discriminated between groups were also related to nonprofessional referents' expectations. In addition, qualitative data showed persistent concerns about occupational risk for contracting AIDS. Based on the results of this research, it is recommended that nurse educators in both clinical and academic settings, target specific educational/training interventions to include transmission, prevention, as well as exploration of feelings, attitudes, beliefs, and behavioral intentions about HIV-related topics. Further theory-based research and testing of interventions to change practicing nurses' attitudes and beliefs about HIV disease are advocated.

Adult↗
PubMed1993

Professional socialisation of nursing students as an outcome of a senior clinical preceptorship experience.

The study purpose was to examine the effects of a senior clinical preceptorship experience on the professional socialisation of nursing students. Corwin's (1961) conception of the professional nursing role and literature on professional socialisation provided the model for the study. A three-group, pre- and post-test design was used. The voluntary, non-randomised sample was drawn from 242 senior community college, baccalaureate and RN-BScN nursing students. Instruments were the Lawler-Corwin (1988) Nursing Role Conception Scale and the Lawler-Stone (1988) Health Care Professional Attitude Inventory. Demographic data were collected. One-way ANOVA was used to compare the mean scores among the three groups. For statistically significant (p < 0.05) F tests, Student-Newman-Keuls multiple comparison tests were used to determine which pairs of groups were different. Pre-post scores were compared using paired t-tests. Following the preceptorship, on the Lawler-Stone subscales, the groups became more professional and more similar in attitude. On Corwin's three role conceptions, the total group reported less role conflict, with the community college students having the least and the RN-BScN students the most amount of conflict. The mixed results emphasise that professional socialization requires further research, especially as an outcome of a preceptorship experience for RN-BScN students.

Adult↗
PubMed1993

Peer teaching among nursing students in the clinical area: effects on student learning.

Substantial use of clinical peer teaching among students has been reported, but there is limited description of outcomes and no reports of the use of a theoretical framework. The purpose of this study was to investigate the effects of peer teaching on baccalaureate nursing students' clinical performance. It was hypothesized that students who were taught by peers will: (a) achieve significantly higher improvement scores than students taught by teachers alone; and (b) rate their preference for peer teaching equal to or higher than instructor teaching. Bandura's (1971) social learning theory provided the framework for the study. The experimental design involved 50 volunteer subjects on two surgical units, one for peer teaching and one for instructor teaching. Data were collected from pre- and post-psychomotor and cognitive tests of a surgical dressing procedure and from a Clinical Teaching Preference Questionnaire (CTPQ). Experimental subjects achieved significantly higher cognitive improvement scores (t = 1.67; P < 0.05) and moderately higher psychomotor improvement scores in support of hypothesis 1. Responses on the CTPQ showed support for hypothesis 2.

Adult↗
PubMed1992

Career patterns and job satisfaction of Canadian nurse educators.

The purpose of this study was to describe the career patterns and job satisfaction of Ontario university and college nurse educators. A descriptive survey design was employed using mailed questionnaires. The sample comprised 60 nurse educators, 30 from three universities and 30 from three colleges. Forty-four returned the completed questionnaire, giving a response rate of 73%. The variables about the career patterns and goals of the nurse educators included their past and present job satisfaction. Career patterns were described as stable, double-track, interrupted and unstable. Similarities and differences were compared and described in relation to these factors. Significant differences in job satisfaction were found between university and college faculty on nine of the 36 job characteristics (for example, leadership style, independence, autonomy and salary). There were no significant differences in job satisfaction for each of the career patterns and the selected demographic variables of age, years in nursing education, educational level and salary between the university and college faculty.

Career Mobility↗
PubMed1991

Attitudes and normative beliefs of nursing students as predictors of intended care behaviors with AIDS patients: a test of the Ajzen-Fishbein theory of reasoned action.

Few investigators have studied nurses' or nursing students' responses to caring for AIDS patients. The purpose of this exploratory study was to test the Ajzen-Fishbein (1980) Theory of Reasoned Action in a student nurse population about AIDS patient care. This theory offers an approach to explaining individuals' intentions to engage in certain behaviors as determined by two components: attitudes toward the behavior and subjective norms. Forty-six second-year baccalaureate nursing students completed a questionnaire developed according to guidelines described by Ajzen and Fishbein (alpha reliability range was .69-.85) prior to and following an instructional unit on caring for AIDS patients. Consistent with the theory, students' attitudes and subjective norms were found to be significant predictors of intentions to care for AIDS patients in their clinical experience (R2 = .29, F[1, 43] = 6.63, p less than .003). In addition, qualitative data resembled those in previous reports of fear of contagion among health professionals. The effects of the instructional unit about caring for AIDS patients resulted in significant changes in both attitudes and subjective norms.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Development and testing of a patient selection instrument for nursing students' hospital experience.

The purposes of this three-phase study were to explicate criteria for patient selection for students' hospital experience, to develop a patient selection instrument and to test its criterion-related validity and inter-rater reliability. In the first phase, 54 experienced nurse educators rated the importance of 63 criteria that may be used in patient selection. The mean ratings of the criteria were used in developing the first draft of the Patient Selection Instrument (PSI) in the second phase of the study. A pilot test of the PSI resulted in revisions. Ninety-four other experienced nurse educators then participated in the third major phase, a methodological study of the PSI. Criterion-related validity (McNemar's x2 = 4.000; p less than 0.05; Kappa = 0.524, se = 0.102, t = 4.918, p = 0.000) and inter-rater reliability (McNemar's x2 = 2.00, p greater than 0.05; Kappa = 0.338, se = 0.180, t = 1.824, p greater than 0.05) were established. A modification resulted in the final version of the PSI. The PSI will be useful to novice nurse educators and as a teaching tool in programs preparing nurse educators.

Education, Nursing, Baccalaureate↗
PubMed1990

Nursing education leadership. Effect of situational and constraint variables on leadership style.

A descriptive study investigating the effect of situational and constraint variables on leadership style is reported. A sample of 35 administrators of college (diploma) nursing programmes and 106 of their senior faculty participated in the study. The Leadership Style Analysis Instrument was used to determine the administrators' leadership styles, as perceived by the administrators themselves and by their senior faculty. Demographic characteristics of the administrators and constraint variables were examined by chi-square analysis (0.05) regarding their relationship to leadership styles. It was found that despite variations in administrator characteristics and extent of constraints, the perceived leadership style was consistently relationship-oriented. The results have implications for educators and administrators in nursing.

Adaptation, Psychological↗
PubMed1990

Occupational stress and coping strategies among female baccalaureate nursing faculty.

Considerable stress is involved in nursing education. However, the sources and extent have not been fully investigated, nor have ways of coping. The main purpose of the study was to explore the sources and levels of perceived stress, coping strategies and effectiveness among female baccalaureate nursing faculty. The second purpose was to examine the relationship between stress, coping and academic responsibilities of the faculty member such as teaching, research and community service. A sample of 70 subjects from eight Ontario universities completed the demographic questionnaire, the researcher-developed 'Stress-Coping Anxiety Inventory', and the 'State-Trait Anxiety Inventory' Form Y (STAI) (Spielberger et al. 1983). Analysis of data using frequencies, cross tabulations, ANOVA and Pearson product-moment correlation were computed. Perceived stressors chosen most frequently as high in stress (greater than or equal to 4) (range = 1-5), in rank order, were 'heavy workload (combined clinical and classroom teaching)', 'retaining failing students', 'failing clinically unsatisfactory students', 'meeting research requirements' and 'providing individual clinical supervision'. Active coping strategies were selected more frequently as being effective (greater than or equal to 4) than passive coping strategies. Age of the respondent, number of years of full-time teaching and tenure status were most often significant factors (less than 0.05) relating to the level of stress. Implications for nursing education administrators and their faculty are discussed.

Adaptation, Psychological↗
PubMed1989

Circular pancreatic trypsin inhibitor. A novel substrate for studies on intracellular proteolysis.

Several recent studies indicate that substrates for ubiquitin-dependent proteolysis must possess unblocked alpha-amino termini. To examine further the importance of free amino groups for proteolytic susceptibility we selected pancreatic trypsin inhibitor (PTI) as a test substrate. PTI can be circularized to form cPTI, a molecule that lacks alpha-amino groups in the absence of an endoproteolytic cleavage. We compared the breakdown of radioiodinated PTI and cPTI in rabbit reticulocyte lysate and found that cPTI was not stabilized relative to PTI. In addition, proteolysis of PTI or cPTI was not inhibited upon conversion of their lysine residues to homoarginine. However, neither degradation of PTI nor cPTI required ATP, and ubiquitin conjugation to either molecule was minor relative to known substrates of the ubiquitin pathway. Thus, PTI and cPTI are cleaved by an ATP-independent endoprotease(s) that does not require the substrate to be ubiquitinated. Such an activity was identified in low salt fractions obtained upon DEAE chromatography of reticulocyte lysate. The ubiquitin/ATP-dependent protease and another large multisubunit protease, both of which elute from DEAE-Fractogel at higher salt concentrations, do not degrade PTI or cPTI. Although monomeric PTI was rapidly degraded in reticulocyte lysate, cross-linked PTI molecules were stable both in reticulocyte lysate and following introduction into cultured cells using red blood cell-mediated microinjection. Thus, increased rates of turnover do not necessarily correlate with greater molecular mass of the substrate.

Animals↗
PubMed1989

Stevens-Johnson syndrome, respiratory distress and acute renal failure due to synergic bleomycin-cisplatin toxicity.

A patient presenting with a cervix uteri epidermoid carcinoma had acute renal failure after treatment with cisplatin and bleomycin. She later developed fatal bleomycin-induced pneumonitis and Stevens-Johnson syndrome. This is a very rare association of adverse effects. The risk of causing a drug interaction thus increasing the severity of bleomycin undesired effects must be taken into account when a nephrotoxic drug is added to the former. The authors stress the importance of monitoring renal function under these conditions.

Acute Kidney Injury↗
PubMed1989

The chronic fatigue syndrome: definition, current studies and lessons for fibromyalgia research.

Chronic fatigue syndrome (CFS) is characterized by chronic, debilitating fatigue lasting greater than 6 months. Frequent chronic and recurrent findings include fever, pharyngitis, myalgias, adenopathy, arthralgias, difficulties in cognition and disorders of mood. In the majority of patients, the illness starts suddenly with an acute, "flu-like" illness. The following laboratory abnormalities are seen with some frequency, although none are seen in all patients: lymphocytosis, atypical lymphocytosis, monocytosis, elevation of hepatocellular enzymes, low levels of antinuclear antibodies, varying levels of antithyroid antibodies, partial hypergammaglobulinemia, elevated CD4:CD8 ratio, decreased cytolytic activity of natural killer cells, and low levels of immune complexes. Clinical and serologic studies suggest an association of CFS with all of the human herpesviruses, particularly Epstein-Barr virus (EBV) and the recently discovered human B lymphotropic virus (HBLV) or human herpesvirus 6; neither EBV nor HBLV has yet been shown to play a causal role in the illness. Preliminary evidence suggests that many of these features of CFS also are seen in patients with fibromyalgia.

Fatigue Syndrome, Chronic↗
PubMed1988

Criteria used for patient selection for nursing students' hospital clinical experience.

This study investigated the criteria used by nurse educators when selecting patients for students' hospital clinical experience. Criteria were defined as individual elements or characteristics considered when selecting patients. Factors were defined as broad categories of related criteria. The sample consisted of 54 nurse educators from college and university nursing programs. A researcher-developed questionnaire was used. The three most important criteria for patient selection were: students' individual learning needs, patients' nursing care needs, and matching patients' needs with students' learning needs. One-way ANOVA was performed on the factors by subjects' demographic variables. Teacher-student clinical ratio, program in which teaching, and age most influenced the factors considered (p less than .05).

Clinical Clerkship↗
PubMed1987

Gentamicin dosage regimen based on serum creatinine concentration.

In order to avoid gentamicin toxicity trough serum concentrations when drug monitoring is not available, a correction factor for serum creatinine was calculated and evaluated. In a first group of 35 patients under aminoglycoside treatment with variable serum creatinine (SCr) values, the regression plot of SCr concentrations versus half-life (T1/2) values was established: log T1/2 = log 2.28 + 1.45 log SCr, r = 0.90, p less than 0.01. A second group of 18 patients was treated with doses of 1.0 mg/kg of gentamicin. Dose intervals equivalent to 3 T1/2 were daily adjusted. The T1/2 was calculated from SCr according to the relationship established for the patients of the first group. All the patients studied maintained trough levels within the therapeutic range.

Adult↗
PubMed1982

Trimeric intermediate in the in vivo folding and subunit assembly of the tail spike endorhamnosidase of bacteriophage P22.

Newly synthesized tail spike polypeptide chains mature from trypsin- and NaDodSO4-sensitive unfolded chains to trypsin- and NaDodSO4-resistant native trimers with a t1/2 of 5 min at 30 degrees C. A metastable intermediate in subunit folding and assembly was trapped by chilling and isolated by electrophoresis through nondenaturing gels in the cold. A fraction of the intermediate could be matured into native trimers in vitro by incubating at physiological temperature. Mixing experiments with electrophoretically distinct mutant proteins showed that the precursor that matured in vitro represented three tail spike polypeptide chains already associated with each other but not fully folded. Identification of this intermediate reveals that the processes of polypeptide chain folding and subunit assembly are coupled in this large structural protein.

Electrophoresis, Polyacrylamide Gel↗
PubMed1982

Fluorogenic substrates for bacterial aminopeptidase P and its analogs detected in human serum and calf lung.

A sensitive fluorimetric assay was developed for bacterial aminopeptidase P, based on intramolecularly quenched fluorogenic substrates. Two substrates were synthesized. Phe(NO2)-Pro-HN-CH2-CH2-NH-ABz (substrate I) and Phe(NO2)-Pro-Pro-HN-CH2-CH2-NH-ABz (substrate II), in which the Phe(NO2) group (rho-nitro-L-phenylalanyl) quenches the fluorescence of the ABz group (omicron-aminobenzoyl). Both substrates were readily cleaved by aminopeptidase P from Escherichia coli, releasing rho-nitro-L-phenylalanine and causing a proportional increase in fluorescence. Complete hydrolysis of the two substrates resulted in a 7.5-fold and 3.4-fold fluorescence increase, respectively. Applying this fluorogenic assay, we were able to detect and measure quantitatively amino-peptidase P-like activity in the human serum and calf-lung extracts. Substrate II was shown to be specifically cleaved by aminopeptidase P in these preparations, while substrate I was apparently cleaved by other enzymes as well. In both preparations, the enzyme activity was independent of Co2+ ions, and Pro-HN-CH2-CH2-NH-ABz (Cbz) was inhibitory. The kinetic constant Km was determined as 0.35 mM and 0.28 mM for the human serum and the calf-lung enzymes respectively. The enzyme activity was only slightly dependent on pH in the range 7.0-8.4.

Aminopeptidases↗