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Biomedical subjects

W R Johnson

Publications and source records attributed to W R Johnson.

At least 19 recordsLinked to original sources
PubMed2005

Relativistic electron correlation, quantum electrodynamics, and the lifetime of the 1s(2)2s(2)2p2p0(3/2) level in boronlike argon.

The lifetime of the Ar13+ 1s(2)2s(2)2p2p0(3/2) metastable level was determined at the Heidelberg Electron Beam Ion Trap to be 9.573(4)(5). The accuracy level of one per thousand makes this measurement sensitive to quantum electrodynamic effects like the electron anomalous magnetic moment (EAMM) and to relativistic electron-electron correlation effects like the frequency-dependent Breit interaction. Theoretical predictions, adjusted for the EAMM, cluster about a lifetime that is approximately shorter than our experimental result.

Journal Article↗
PubMed2004

Nondipole effects in the photoionization of xe 4d5/2 and 4d3/2: evidence for quadrupole satellites.

Measurements of nondipole parameters in spin-orbit-resolved Xe 4d photoionization demonstrate dynamical differences arising from relativistic effects. The experimental data do not agree with relativistic random-phase approximation calculations of single ionization dipole and quadrupole channels. It is suggested that the discrepancy is due to the omission of multiple-excitation quadrupole channels, i.e., quadrupole satellite transitions.

Journal Article↗
PubMed2003

Dramatic nondipole effects in low-energy photoionization: experimental and theoretical study of Xe 5s.

The Xe 5s nondipole photoelectron parameter gamma is obtained experimentally and theoretically from threshold to approximately 200 eV photon energy. Significant nondipole effects are seen even in the threshold region of this valence shell photoionization. In addition, contrary to previous understanding, clear evidence of interchannel coupling among quadrupole photoionization channels is found.

Journal Article↗
PubMed2001

Vacuum-polarization corrections to the parity-nonconserving 6s-7s transition amplitude in (133)Cs.

The dominant one-loop radiative corrections to atomic wave functions, those associated with vacuum polarization in the nuclear Coulomb field, are evaluated for the 6s-7s parity-nonconserving transition amplitude in (133)Cs. These corrections increase the size of this amplitude by 0.4% and, correspondingly, increase the difference between the experimental value of the weak charge Q(W)((133)Cs) and the value predicted by the standard model.

Journal Article↗
PubMed2000

Perceived overqualification and dimensions of job satisfaction: a longitudinal analysis.

The present study is an investigation of the effects of perceived overqualification on dimensions of job satisfaction. The data for this study came from a two-wave panel study of members of a midwestern American Postal Workers Union local. Job satisfaction was operationalized with 4 subscales from the Job Descriptive Index (P. Smith, L. Kendall, & C. Hulin, 1969). The following three hypotheses were tested: (a) Perceived overqualification will be negatively related to facets of job satisfaction; (b) there is stability in the test-retest correlations of facets of job satisfaction; and (c) the effects of perceived overqualification on facets of job satisfaction will not change from Time 1 to Time 2 because of adaptation. The cross-sectional results supported the hypotheses and suggested that perceived overqualification has a negative effect on job satisfaction. However, the relationships varied by dimension of perceived overqualification and dimension of job satisfaction. Future researchers of overqualification and dimensions of job satisfaction should consider relative deprivation as a source of work-related deprivations.

Adult↗
PubMed1999

Perceived overqualification and health: a longitudinal analysis.

The authors examined the effects of perceived overqualification on health and health decline by means of a 2-wave panel study of members of a midwestern American Postal Workers Union local. The 1st hypothesis was that overqualification was negatively related to health at Time 2 (T2); the second hypothesis was that overqualification was positively related to perceived health decline at T2. Neither was supported by the data. However, the relationships were in the expected direction for perceived mismatch but not for the perceived no grow dimension of overqualification. The results imply that perceived no grow may have immediate threats to health, whereas perceived mismatch may have longer term implications for health. The stability of perceived health between Time 1 (T1) and T2 could overshadow a longitudinal effect of overqualification on health and health decline at T2.

Adult↗
PubMed1997

Pre-operative histological diagnosis of breast cancer.

BACKGROUND: A concordant triple assessment (clinical, mammographic and cytological) diagnosis of breast malignancy allows for pre-operative planning of surgery and may also allow for one-stage surgery. However, while the accuracy of cytology is high, it is unable to distinguish invasive cancer from ductal carcinoma in situ (DCIS). A malignant mass may be due to pure in situ cancer and hence axillary dissection may be avoided if pre-operative histology is available. METHODS: A consecutive series of 300 cases of breast cancer treated over the last 5 years by the two authors was analysed to determine: the method of achieving pre-definitive operation histology; the number of stages of surgery required; and the number of cases of mass-forming DCIS which could be susceptible to over-treatment. RESULTS: Of 289 patients undergoing local definitive surgery for breast cancer, 12 (42%) had clinical masses predominantly due to DCIS and in most of these patients axillary dissection was avoided. Histology was obtained prior to definitive surgery in 272 (94.1%) patients, by intra-operative frozen section in 159 (55.0%), incisional biopsy in 37 (12.8%), needle localization biopsy in 62 (21.5%) and core biopsy in 14 (4.8%). A total of 189 patients (65.4%) underwent one-stage surgery only. Breast conservation was achieved in 210 (72.7%) patients. Those requiring mastectomy were significantly more likely to have required two stages of surgery as were those with lesions detected by screening. CONCLUSIONS: Mass-forming DCIS cannot be predicted pre-operatively by triple assessment alone; and therefore pre-operative histology is required to avoid axillary dissection. Pre-operative histology may be obtained by core biopsy or intra-operative frozen section to identify DCIS and distinguish it from invasive disease, but both allow a one-stage surgical procedure in the majority of cases.

Adult↗
PubMed1997

Cosmesis following complete local excision of breast cancer.

BACKGROUND: With the establishment of the safety of breast conservation in early breast cancer, cosmesis has become an increasingly important end-point of treatment. The aim of the present study was to establish a model to assess breast cosmesis after complete local excision and to assess cosmesis achieved in patients who had surgery using the seroma technique. METHODS: A total of 42 patients were retrospectively reviewed and assessed by independent clinical assessment by a surgeon, structured questionnaire and clinical photography. RESULTS: A total of 86% of patients were rated by surgeon and patient as having a good or excellent cosmetic outcome. There was a high degree of concordance between independent clinical assessment and clinical photographic analysis. CONCLUSIONS: A model has been established for the assessment of breast cosmesis; the technique of seroma formation without reconstruction of the defect results in good or excellent cosmesis in the majority of patients.

Activities of Daily Living↗
PubMed1996

Perceived overqualification and psychological well-being.

The relationship between perceived overqualification and psychological well-being was explored within the framework of stress-illness models, using multiple regression analysis. Data were collected from 179 male and 109 female members of a local midwestern chapter of the American Postal Workers Union. As expected, there was a significant, positive relationship between perceived overqualification and psychological well-being: The greater the perceived overqualification, the greater the psychological distress. The interaction between perceived overqualification and gender was not significant.

Adult↗
PubMed1996

Modification of growth of desmoid tumours in tissue culture by anti-oestrogenic substances: a preliminary report.

BACKGROUND: Tamoxifen and toremifene have been used in patients with advanced desmoid tumours with response rates of 51%. METHODS: We developed an experimental model of desmoid tumour cells in tissue culture to study their effect. Four cell lines were established in tissue culture. All native and corresponding cultured tumours were oestrogen receptor negative. Tumour 1 was from a 22 year old with familial adenomatous polyposis (FAP) and recurrent abdominal wall desmoid tumours. She remains disease free on tamoxifen 4 years following surgery. Both her mother and sister also have shown regression of their FAP-associated desmoid tumours at the menopause and on tamoxifen, respectively. We assessed the effect of tamoxifen on desmoid tumours in tissue culture at 780 ng/mL. The results were assessed by cell density counting. RESULTS: Tumours 1 and 2 have responded with an approximately. 50% reduction in growth to tamoxifen at 780 ng/mL. CONCLUSIONS: This apparent growth inhibitory effect of tamoxifen on two desmoid tumour cell lines appears to be independent of oestrogen and correlates with the in vivo effect of tamoxifen on three desmoid tumours in an FAP family.

Abdominal Neoplasms↗
PubMed1995

Evaluation of an automated urine chemistry reagent-strip analyzer.

We evaluated the Miles Inc., Clinitek Atlas Automated Urine Chemistry Analyzer for 11 tests: bilirubin, color, glucose, ketones, leukocyte esterase, nitrite, occult blood, pH, protein, specific gravity, and urobilinogen. The instrument uses a roll of reagent strips affixed to a clear plastic support; urine specimens are automatically pipetted onto these strips. The instrument measures the pads' color using reflectance colorimetry. Specific gravity is measured using a fiberoptic refractive index method. Four hospitals participated in the evaluation, and tests were performed only on fresh urine samples. We found the instrument easy to use; it has walk-away capability with up to 40-specimen loading capacity plus spaces for STATs, calibrators and controls. We found good comparability with chemical tests and other nonreagent strip procedures, as well as good agreement with the Miles Inc. Clinitek 200+ urine chemistry analyzer and visual reading of the Miles Inc. Multistix Reagent Strips. The Clinitek Atlas is rugged and reliable, and is suitable for a high-volume urinalysis laboratory.

Automation↗
PubMed1995

The effects of union membership on multiple work commitments among female public sector employees.

The effects of union membership on union, organizational, and dual commitment among 245 clerical employees at a midwestern state university represented by a Local of the American Federation of State, County, and Municipal Employees (AFSCME) were investigated. Based on the similarity hypothesis of the social identity theory, it was hypothesized that union membership would be positively related to union and dual commitment and negatively related to organizational commitment. The results of the regression analyses supported the similarity hypothesis, and union membership explained a significant amount of variance in union and dual commitment but not in organizational commitment. These findings are discussed in the context of applying social psychological approaches to understand attitudes toward unionization; industrial conflict; and union, organizational, and dual commitment.

Adult↗
PubMed1994

Traumatic diaphragmatic hernia presenting as an intercostal hernia: case report.

Intercostal hernias are rarely reported in the literature. We report a case of intercostal hernia secondary to a ruptured right hemidiaphragm and fractured costal margin caused by blunt trauma. The patient was ventilated at initial hospitalization because of rib fractures and advanced age, and the intercostal hernia was not evident. After physical rehabilitation treatment elsewhere, a painful chest wall bulge developed. A chest film and computed tomographic scan revealed the hernia. Surgery with a thoraco-abdominal incision in the line of the hernia allowed reduction of the hernial contents.

Aged↗
PubMed1993

Cancer risk in relatives of patients with common colorectal cancer.

OBJECTIVE: To quantify any risk for colorectal cancer in first-degree relatives of patients with common colorectal cancer and to define possible markers for increased risk. DESIGN: Case-control family study. PATIENTS: Relatives of colorectal cancer patients and of matched control patients from a one-surgeon practice. METHODS: Family medical histories were obtained for 7493 first-degree relatives and 1015 spouses of 523 case-control pairs. Reported diagnoses of colorectal cancer in relatives were verified in 79% of instances. RESULTS: By case-control analysis, the odds ratio was 1.8 (95% CI, 1.2 to 2.7) for one and 5.7 (CI, 1.7 to 19.3) for two affected relatives. By matched analysis of risk in relatives, the increased risk to parents and siblings was 2.1 times greater for case patients than for control patients (CI, 1.4 to 3.1); 3.7 times greater (CI, 1.5 to 9.1) with case patients diagnosed before 45; and 1.8 times greater (CI, 1.2 to 2.9) with case patients diagnosed at 45 years or older; and was independent of gender, type of relative, site of cancer, and type of cancer (single or multiple). The cumulative incidence among first-degree relatives was greater for case patients than for control patients (P < 0.001), and in case patients, greater for those diagnosed before 55 years of age (P < 0.001). The cumulative incidence (+/- S.E.) to age 80 was 11.1% +/- 1.3%, 7.3% +/- 0.8%, and 4.4% +/- 1.0% among relatives of case patients diagnosed before age 45 years, between 45 and 54 years, and at 55 years or older, respectively, and was 2.4% +/- 0.6% in relatives of control patients. CONCLUSIONS: First-degree relatives of patients with common colorectal cancer have an increased risk for colorectal cancer. This risk is greater if diagnosis was at an early and is greater when other first-degree relatives are affected. This increased risk should be considered when formulating screening strategies.

Adult↗
PubMed1993

Laparoscopic assisted right hemicolectomy with Valtrac BAR (Biofragmentable Anastomotic Ring) ileotransverse anastomosis.

Laparoscopic techniques have been employed in a group of medically compromised patients requiring right hemicolectomy, permitting a shorter and lower placed abdominal incision than may have been expected with a conventional surgical approach. In eight patients requiring right hemicolectomy, full mobilization of the right colon from the caecum to the proximal transverse colon was performed laparoscopically. Resection and anastomosis then proceeded through a small right-sided transverse abdominal incision. End to end ileotransverse anastomosis was performed in each instance employing the Valtrac BAR (Biofragmentable Anastomotic Ring) compressive anastomotic technique. The average operating time was 133 min. There was no mortality, but one patient developed pulmonary complications and three developed minor wound infections. An additional three patients developed urinary tract infections. There were no anastomotic complications. The average postoperative stay was 10 days. This study has indicated that laparoscopic techniques can be successfully applied to large bowel surgery, and may be of benefit to high risk patients.

Aged↗
PubMed1992

Subjective underemployment and psychosocial stress: the role of perceived social and supervisor support.

The purpose of this study was to examine the effects of subjective underemployment on psychosocial stress. The moderator effects of perceived social and supervisor support were also investigated. Data were collected during the summer of 1987 in a public utility governmental agency in the United States. The sample size was 212 with a 71% response rate. Multiple regression analysis was used to examine the relationship between subjective underemployment and psychosocial stress. As expected, the results revealed a significant positive relationship between subjective underemployment and five indexes of psychosocial stress. The interactions between subjective underemployment and social and supervisor support were not significant; however, the relationships were in the expected directions. Supervisor support was positive and significantly related to psychosocial stress, but social support was not.

Adaptation, Psychological↗
PubMed1991

Application of microcolumn liquid chromatography-continuous-flow fast atom bombardment mass spectrometry in environmental studies of sulfonylurea herbicides.

The use of 0.25-mm I.D. packed capillary liquid chromatography columns coupled with continuous-flow fast atom bombardment (FAB) mass spectrometry has proven to be a very valuable technique, especially for the identification of unknown sulfonylurea herbicide metabolites. Several new and unusual heterocycle ring-opened metabolites and hydrolysis products were identified, and metabolic pathways were proposed. Typical column flow-rates are 1-2 microliters/min, which allows direct coupling with no sample splitting. This is important in our metabolite identification work, since we are usually sample-limited. Techniques for increasing injection volume to allow analyses of dilute solutions and the use of polymeric packing for separation of polar metabolites are discussed. The FAB mass spectra usually provide unequivocal molecular weights and structurally useful fragments ions, which often allows structure assignments on exceedingly small quantities of isolated metabolites.

Animals↗