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Biomedical subjects

N Swanson

Publications and source records attributed to N Swanson.

16 recordsLinked to original sources
PubMed2001

Impact of added rest breaks on the productivity and well being of workers.

The impact of frequent short rest breaks on the productivity and well being of a group of 30 workers in a meat-processing plant was studied. Two rest break schedules were tested, both of which provided 36 min of extra break time over the regular break schedule (30-min lunch and two 15-min breaks). In the first experimental rest break schedule, workers were given 12 3-min breaks evenly distributed over the workday (3-min break for every 27 min of work). In the second schedule, workers were given four 9-min breaks evenly distributed over the workday (9-min break every 51 min of work). Outcome measures included production rate and discomfort and stress ratings. Results showed that neither of the two experimental rest break schedules had a negative effect on production, and the 9-min break schedule improved discomfort ratings for the lower extremities. The workers in the study mostly preferred the 9-min rest break schedule, indicating that workers in general might not as readily accept fragmentation of break time into short, frequent breaks.

Adult↗
PubMed2001

Plasminogen activator and plasminogen activator inhibitor gene expression in human saphenous vein organ culture.

We describe the expression of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI-1) in saphenous vein culture. Smooth muscle cells (SMC) are quiescent in fresh tissue, whereas these cells acquire a proliferating phenotype when venous segments are cultured in the presence of serum. t-PA and PAI-1 were localized immunohistochemically and quantified using biochemical techniques. t-PA and PAI-1 mRNA was quantified by reverse transcription polymerase chain reaction (RT--PCR) assay. Immunostaining showed an increase in the positivity of proliferating cell nuclear antigen (PCNA) from 10-day tissue culture. Tissue sections from fresh vein showed minimal t-PA and maximal PAI-1 immunostaining. In contrast, 10-day cultures showed an increase in t-PA and a decline in PAI-1 staining. Biochemical analysis revealed a 118% increase in t-PA and a 50% decrease in PAI-1 antigen levels from 10-day tissue cultures. RT--PCR demonstrated that the mRNA encoding t-PA increased, while PAI-1 decreased after 10 days of culture. In conclusion, venous culture showed an up-regulation of t-PA and a repression of PAI-1 gene expression during SMC proliferation in the vessel wall. The PAI-1 repression observed in venous culture is in contrast to the situation observed in human atheroma. A shift in the t-PA/PAI-1 balance may have a role in vascular remodeling.

Blotting, Western↗
PubMed2001

Current perspectives on British use of adjunctive therapies during coronary interventions.

BACKGROUND: Interventional techniques are commonly performed with adjunctive therapy including clopidogrel, ticlopidine, abciximab and heparin. We wished to assess the current British use of antiplatelet and anticoagulant agents as adjunctive therapies in interventional cardiology in the light of the available evidence base regarding their usage. METHODS: A simple structured questionnaire was sent between August and October 1999 to all interventional cardiology consultants working in the UK regarding their usage of abciximab (ReoPro), heparin, clopidogrel (Plavix) and ticlopidine (Ticlid) peri-procedurally. RESULTS: 68% of consultants responded over the next 4 months, with many replying jointly for a centre rather than individually. Average abciximab use was 8.3% of interventional cases. Eighty-two percent of clinicians used clopidogrel in stented patients. Exact dosages varied considerably. Fifty-three percent of clinicians gave 10000 IU or more of heparin routinely. CONCLUSIONS: These figures are not in line with the published evidence and British interventionists appear to have adopted various strategies to target the use of these agents. In particular, abciximab appears to be being administered reactively, as and when problems arise in the catheterisation lab.

Abciximab↗
PubMed2000

The history of dermatologic surgical reconstruction.

Over the last 40-50 years, reconstructive surgery in dermatology has undergone expansive growth and development. As dermatologists began to provide a greater array of surgical services during this period, it became apparent that new skills and techniques in the area of reconstruction would be required. Initially many of the procedures and concepts were adopted from other specialties, however, in the years since, significant contributions have been made by dermatologists which in turn have benefited other specialties as well. This review attempts to summarize some of the significant historical events and innovations that have established and supported dermatologic surgical reconstruction.

Dermatologic Surgical Procedures↗
PubMed2000

Concepts of sliding and lifting tissue movement in flap reconstruction.

BACKGROUND: The optimal design of a skin flap requires an understanding of the concepts of tissue movement. OBJECTIVE: The purpose of this manuscript was to demonstrate concepts of sliding and lifting tissue movement for flap reconstruction. METHODS: Six similar defects located in the forehead-temple-eyebrow region were repaired using a different skin flap. RESULTS: The specific flap design for a given defect is based on the answer to three predictable events that result from tissue transfer: Where is the tension? Where are the final incision lines? Where is the redundant tissue? CONCLUSION: A mental exercise assessing all available reconstruction options should be performed for each individual patient and defect. Both patient and defect considerations need to be assessed. A thorough understanding of both anatomy and tissue movement is necessary for optimal skin flap reconstruction.

Adult↗
PubMed1998

Use of chest radiography in the initial evaluation of patients with localized melanoma.

OBJECTIVE: To evaluate the use of an initial staging chest x-ray film in asymptomatic patients who present with localized primary cutaneous melanoma. DESIGN: The staging workup of 1032 consecutive asymptomatic patients with localized melanoma was retrospectively reviewed via database chart review. SETTING: Regional melanoma referral center in an academic medical center. PATIENTS: The melanoma database identified 1032 asymptomatic patients with localized melanoma for retrospective review. Of the patients studied, 876 (85%) of 1032 had an initial staging chest x-ray film performed. A chest x-ray film was considered initial if performed within 6 months of melanoma diagnosis. MAIN OUTCOME MEASURE: The rate of positive, negative, and suspicious findings of initial chest x-ray films. RESULTS: One hundred thirty (15%) of 876 patients had suspicious findings necessitating additional workup. Based on follow-up radiologic findings, only 1 (0.1%) of 876 had a true-positive chest x-ray film demonstrating pulmonary metastasis. CONCLUSIONS: The yield of detection of unsuspected pulmonary metastasis by chest x-ray film in the initial evaluation of asymptomatic patients with localized melanoma was exceedingly low (0.1%). Our results support the concept that routine chest radiograph screening in asymptomatic patients presenting with stage I and intermediate-thickness (1.5- to 4.0-mm) stage II melanoma is unlikely to yield true-positive findings of silent pulmonary metastasis. No definitive conclusions were drawn for the subset of patients with stage II thick melanoma (> 4.0 mm) because of the small number of patients (n = 40) in our series. Prospective studies are necessary to ultimately define the yield of initial radiographs in asymptomatic patients with localized melanoma.

Adolescent↗
PubMed1997

Factors associated with client-reported HIV infection among clients entering methadone treatment.

To determine demographic and behavioral factors associated with client-reported HIV infection among new enrollees in methadone maintenance treatment programs (MMTPs) in Massachusetts and Connecticut, we examined ethnographic data and interview data from MMTP clients (N = 674). Clients responded to questions about behaviors in the 30 days before drug treatment. ETHNOGRAPH was used to analyze qualitative data, and logistic regression analysis was used to identify variables associated with client-reported HIV infection. Statistical significance was set at p < .05. The client-reported HIV infection rate was 20% (132/674). Odds ratios for factors associated with client-reported HIV infection were being white (0.53), increase in age (1.07), use of non-injected heroin (0.12), use of injected heroin (6.24), cocaine injection (1.78), sharing of "works" with strangers (2.15), and "safer sex" behavior (4.04). Additionally, 35% of those who did not use illicit drugs reported being seropositive. The qualitative data suggested HIV positive clients were concerned about protecting sex partners, and learning of HIV infection motivated some to stop using drugs. Although some clients engaged in low-risk behaviors, others did not, therefore the potential for HIV transmission among injection drug users (IDUs) in Connecticut and Massachusetts exists. HIV prevention and drug treatment program personnel should reinforce and build on the low-risk behaviors that are acceptable and adopted by some in this population.

Adult↗
PubMed1996

Increased monoamine oxidase A activity in the epidermis of patients with vitiligo.

Human keratinocytes under in vitro conditions synthesize norepinephrine and epinephrine, whereas melanocytes lack this capacity. Keratinocytes established from lesional and nonlesional skin of patients with vitiligo synthesized four and two times more norepinephrine, respectively, than controls. Epinephrine synthesis was similar in keratinocytes from uninvolved epidermis and controls, but cells from involved skin had 6.5-fold less epinephrine than controls, indicative of low phenylehtanolamine-N-methyl transferase (PNMT) activity. Similar results were obtained in five patients with vitiligo who showed low epinephrine levels in involved epidermis. Both human keratinocytes and melanocytes expressed significant levels of monoamine oxidase A (MAO-A) activities as shown using 14C-labelled 5-hydroxytryptamine as substrate and immunohistochemical staining with mouse monoclonal antibody. MAO-A activities in the total epidermis of patients with vitiligo were increased five- to ten-fold compared with skin of type-matched controls. Similar increases in MAO-A activities were also found in both keratinocytes and melanocytes established in vitro from vitiliginous epidermis. Based on these results, it can be concluded that defective catecholamine synthesis in the epidermis of patients with vitiligo leads to increased levels of norepinephrine with a concomitant increase in MAO-A activity.

Cells, Cultured↗
PubMed1996

Organizational network analysis as a tool for program evaluation.

Health program evaluation is generally focused on an examination of individual program characteristics and accomplishments, yet many programs are part of a broader service system. Evaluation of the role a program plays in that system is an important evaluation question to address. A network analysis of program referral patterns was used to evaluate Connecticut's Healthy Start program. Network analysis showed that Healthy Start played a "broker" role in 4 case study communities, sending and receiving referrals of pregnant women to a higher than average number of other programs. Further, in the urban area case study, competing market players providing services to pregnant women resulted in subsets of services with dense referral patterns within the subsets, but little referral between subsets. Healthy Start was found to be instrumental as an integrator of these otherwise disconnected service subsets.

Child Health Services↗
PubMed1995

Suicide and occupation: a review of the literature.

Suicide is the eighth leading cause of death in the United States. Suicide rates have been reported to be particularly high in professional, managerial, and executive groups. We reviewed English language epidemiological studies on suicide and occupation published since 1982. Some studies suggest that workers in a number of occupations, including chemistry, farming, and law enforcement, may have elevated suicide rates. The weight of current evidence supports the conclusion that both male and female physicians have elevated rates of suicide, with females at particularly high risk. Elevated rates of suicide in a particular occupational group may result from a complex interaction between job factors such as work stress and access to means and other risk factors such as age and presence of a mental disorder.

Female↗
PubMed1994

Identifying potential dropouts through school health records.

This study of the records of 255 ninth grade, inner-city Midwestern high school students shows that students who drop out of school are several times as likely to have incomplete health information in the school health record as students who stay in school. A cluster of five variables--vision screening, scoliosis screening, visits to the health office, age and attendance--were found to provide 85% or better accuracy in estimating actual drop-out rates. Missing or incomplete data in combination with attendance data thus become powerful predictors of potential dropouts.

Adolescent↗
PubMed1992

Serial studies of autologous antibody reactivity to squamous cell carcinoma of the head and neck.

In previous studies we evaluated the incidence and specificity of autologous antibody reactivity against squamous cell carcinoma of the head and neck (SCCHN). We were able to demonstrate that autologous antibody reactivity is present in native sera but was usually of too low a titer to allow further analysis. Dissociation of immune complexes by acidification and ultrafiltration of serum augmented autologous antibody reactivity in nine out of nine autologous systems tested. Native antibody and antibody derived from immune complexes produced by the host and reactive with autologous tumor cells may be directed against physiologically relevant antigens. Therefore, correlations of antibody titers with clinical course may provide insight into the nature of the host response to cancer. In the present analysis, serological studies of six patients with SCCHN were performed with serum samples obtained over many months. Results of serial serological assays were correlated to tumor progression and clinical course. Fluctuations in autologous antibody reactivity were noted over time. In four cases, rises in autologous antibody titers preceded the clinical diagnosis of recurrence by several months. Drops in autologous antibody reactivity were noted in two cases following surgery or radiation therapy. In two cases of long-term survivors, no correlation between antibody reactivity and clinical course was noted. Specificity analysis of the six autologous systems demonstrated reactivity against autologous and allogeneic SCCHN as well as melanoma cell lines. These sera did not react with glioma, neuroblastoma, renal cell, breast, bladder and colon carcinoma cell lines nor with fetal calf serum, pooled lymphocytes, red blood cells and platelets. Autologous serial serological studies may provide a means by which to evaluate the host/tumor relationship in patients with SCCHN.

Aged↗
PubMed1992

Transferrin index: an alternative method for calculating the iron saturation of transferrin.

We surveyed 140 clinical chemistry laboratories in Australia to establish which laboratory methods they used to determine serum iron status: 125 measured serum iron (Fe), 85 measured transferrin (TRF), 47 measured total iron-binding capacity (TIBC), and 14 measured both TRF and TIBC. Of the 55 laboratories routinely reporting TRF saturation (TS), 16 calculated TS directly as (Fe/TIBC) x 100, and 9 used [Fe/(TRF x 2)] x 100. Thirty laboratories measured TRF and converted it to an equivalent TIBC concentration; the derived TIBC was then used to calculate TS. We measured iron, TIBC, and TRF concentrations in 94 control subjects, 59 patients with alcoholic liver disease (ALD), and 20 with proven genetic hemochromatosis (GH). TS was compared with a transferrin index (TI = Fe/TRF) to determine whether both methods were sensitive for GH screening and which method gave the fewest false-positive results with discrimination limits of > 55% and > 1.0, respectively. All GH patients were detected by both TS and TI at these limits. One control subject had a TI > 1.0, whereas three control subjects had a TS > 55%. Nine patients with ALD had a TI > 1.0 and 11 ALD patients had a TS > 55%. Some iron-overload patients had lower than expected TS values compared with TI, possibly because of ferritin interference in the TIBC assay. Also, the precision of the TRF assay was better than that of the TIBC assay: CVs of 1.85-3.68% vs 6.17%. We therefore recommend that calculated TI replace TS in screening for iron overload.

Australia↗
PubMed1990

Variation in concentration of lipids, lipoprotein lipids, and apolipoproteins A-I and B in plasma from healthy women.

The components of total variation--biological, inter- and intra-individual, and analytical--of plasma lipids, lipoprotein lipids, and apolipoproteins A-I and B have been determined in a population of 44 healthy women, ages 18-35 years. Blood was sampled three separate times at three-month intervals, with no restrictions on diet or physical activity during these periods. The greatest inter-individual variances were observed for high-density lipoprotein (HDL)-cholesterol, HDL2-cholesterol, and total plasma cholesterol. Triglycerides had the highest intra-individual variance (CV 22%). The percentage of inter- and intra-individual variances of apolipoprotein A-I concentrations were more reflective of total HDL- and HDL2-cholesterol content than of HDL3-cholesterol. Concentrations of calculated low-density-lipoprotein cholesterol showed a greater inter-individual variation (18.6%) than did apolipoprotein B (10.7%). The laboratory CVs for these analytes were similar to other reported values. From these data, we computed the expected variation for subjects in our study for single and repeated measurements. Such considerations can influence decision-making in the clinical setting or in designing epidemiological studies.

Adolescent↗
PubMed1985

Antiacetylcholine receptor and antinuclear antibodies in myasthenia gravis. Correlation with HLA, sex and Gm.

Sera from 27 subjects with myasthenia gravis (MG) were examined by immunoassay for antibodies to double-stranded DNA (ds-DNA), RNA-nucleoprotein complexes (ENA) and acetylcholine receptor (ACHR). The prevalence of the genetic markers of sex, HLA and Gm were analyzed in relation to various parameters of these autoantibodies. The highest levels of ds-DNA antibodies were associated with HLA B8 as compared to other HLA antigens (p less than 0.05), females as compared with males (p less than 0.05), and females with HLA B8 (p less than 0.05) when both sex and HLA were analyzed concurrently. An association between low titers and HLA B7 (p less than 0.05), with a significant difference between the B8 females and B7 males (p less than 0.05) was also noted. By contrast, no Gm association was noted for antinuclear antibody parameters, but was observed in females between high ACHR antibody titers and the homozygous phenotype (3; 5, 13) (p less than 0.05). This study of MG implicated HLA and sex factors in the production of a broad spectrum of antinuclear antibodies, while the contrasting Gm association noted with ACHR antibody titers was indicative of distinctive immunogenetic influences over autoantibody production in MG.

Adult↗