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Biomedical subjects

M R Petersen

Publications and source records attributed to M R Petersen.

At least 19 recordsLinked to original sources
PubMed2001

Lung cancer case-control study of beryllium workers.

BACKGROUND: Cohort mortality studies have found elevated lung cancer mortality among beryllium-exposed workers, but none evaluated the association between beryllium exposure level and lung cancer risk. A nested case-control study of lung cancer within a beryllium processing plant was conducted to investigate the relationship between level of beryllium exposure and lung cancer. METHODS: Lung cancer cases were identified by mortality follow-up through 1992 of a cohort of male workers at a beryllium alloy production plant. Each of 142 lung cancer cases was age-race-matched to five controls. Calendar-time-specific beryllium exposure estimates were made for every job in the plant and were used to estimate workers' cumulative, average, and maximum exposures. The potential confounding effects of smoking were also evaluated. RESULTS: Lung cancer cases had shorter tenures and lower lifetime cumulative beryllium exposures than controls, but higher average and maximum exposures. However, after applying a 10- and 20-year lag, exposure metrics were higher for cases. Odds ratios in analyses lagged 20 years were significantly elevated for those with higher exposure compared to the lowest exposure category. Significant positive trends were seen with the log of the exposure metrics. Smoking did not appear to confound exposure-response analyses. CONCLUSION: Increased lung cancer among workers with higher lagged beryllium exposures and lack of evidence for confounding by cigarette smoking, provide further evidence that beryllium is a human lung carcinogen. Published 2001 Wiley-Liss, Inc.

Air Pollutants, Occupational↗
PubMed2001

Estimating historical exposures of workers in a beryllium manufacturing plant.

BACKGROUND: Beryllium is known to be toxic to the lungs, causing beryllium lung disease and associated with increased lung cancer risk. Airborne beryllium exposures have been monitored since the 1940s. This study describes methods used to measure airborne beryllium concentrations and how historical measurements from a beryllium manufacturing plant were used to estimate workers' exposures in a lung cancer case-control study. METHODS: Airborne beryllium concentrations had been measured using all-glass impingers, high-volume air filters, and personal respirable and total dust samplers. To provide consistency in exposure estimates over time, measurements collected by the other monitoring methods were converted to approximate the most frequently used high-volume, time-weighted average measurements. Because industrial hygiene measurements were not collected in every year for all jobs throughout the duration of the case-control study, exposure estimates had to be extrapolated from the existing measurements over time and across jobs. RESULTS: Over 7,000 historical measurements were available to estimate beryllium exposures of workers over time. Average exposures between jobs varied considerably and exposures for all jobs decreased dramatically between the 1940s and 1970s due to major plant production changes. CONCLUSIONS: Although error in the exposure metrics for the cases and controls likely occurred due to limitations of the exposure assessment data, the exposure estimates for each job over time provided a reasonable, objective mechanism for categorizing workers by the relative exposures they were likely to have encountered during their tenure. Published 2001 Wiley-Liss, Inc.

Air Pollutants, Occupational↗
PubMed2001

Progressive outer retinal necrosis syndrome in a lymphoma patient with good visual outcome.

PURPOSE: To report an HIV-negative lymphoma patient who developed progressive outer retinal necrosis syndrome and who had a good visual outcome after treatment with two-drug antiviral therapy and intravenous immunoglobulin. METHODS: Case report. RESULTS: A 43-year-old man with small lymphocytic lymphoma was diagnosed with progressive outer retinal necrosis in his left eye. Treatment was initiated with intravenous foscarnet and ganciclovir as well as intravenous gammaglobulin at a dose of 0.5 gm/kg per day for 5 days. On the second hospital day he was started on decadron 4 mg orally four times daily. No further posterior retinitis progression was observed despite severe immunosuppression. Visual acuity remained stable at 20/30 with 10 months' follow-up. CONCLUSIONS: The benefit of using gammaglobulin in progressive outer retinal necrosis is unknown. Given the rapid improvement seen in this patient's retinitis, it may be reasonable to consider the use of gammaglobulin in other cases of infectious retinitis in immunocompromised patients.

Adult↗
PubMed2001

Indocyanine green-assisted peeling of the retinal internal limiting membrane during vitrectomy surgery for macular hole repair.

OBJECTIVE: To determine the efficacy and safety of indocyanine green (ICG)-assisted retinal internal limiting membrane (ILM) peeling during macular hole repair. DESIGN: Interventional, noncomparative, prospective case series. PARTICIPANTS: Twenty-four consecutive patients (24 eyes) with stage 3 or 4 macular holes. INTERVENTION: All eyes underwent a pars plana vitrectomy, including peeling of the posterior cortical hyaloid when necessary. Indocyanine green dye (0.5%) was instilled into the posterior vitreous cavity over the macula and left in place for 3 to 5 minutes. After removal of the ICG, the retinal ILM was peeled. Medium- to long-acting gas tamponade was used in all cases, and all patients were asked to position face down for 1 to 2 weeks. MAIN OUTCOME MEASURES: Intraoperative staining properties of ICG, technical ease of peeling of the retinal ILM, postoperative anatomic results, visual acuity, and complications were recorded. RESULTS: Indocyanine green stained the retinal ILM, but did not stain the underlying retina. Indocyanine green staining greatly facilitated the surgeons' ability to visualize and peel the ILM in each case. Peeled tissue was sent for both light and electron microscopic studies, which confirmed that the ICG-stained tissue was truly retinal ILM. Patients were observed after surgery for an average of 123 days (range, 23-195 days). Anatomic closure of the macular hole was achieved in 21 eyes (88%) with a single surgery. Visual acuity improved in 23 of 24 patients (96%) after surgery. There were no intra- or postoperative complications related to ICG use, and there was no clinical or fluorescein angiographic evidence of ICG toxicity. CONCLUSIONS: Indocyanine green stains the retinal ILM. This property facilitates ILM peeling by providing a stark contrast between the stained ILM and the unstained retina. Indocyanine green staining of the ILM appears to be a safe and useful adjunct in vitreous surgery for macular hole repair.

Adult↗
PubMed2001

Sex-biased gene flow in spectacled eiders (Anatidae): inferences from molecular markers with contrasting modes of inheritance.

Genetic markers that differ in mode of inheritance and rate of evolution (a sex-linked Z-specific microsatellite locus, five biparentally inherited microsatellite loci, and maternally inherited mitochondrial [mtDNA] sequences) were used to evaluate the degree of spatial genetic structuring at macro- and microgeographic scales, among breeding regions and local nesting populations within each region, respectively, for a migratory sea duck species, the spectacled eider (Somateria fisheri). Disjunct and declining breeding populations coupled with sex-specific differences in seasonal migratory patterns and life history provide a series of hypotheses regarding rates and directionality of gene flow among breeding populations from the Indigirka River Delta, Russia, and the North Slope and Yukon-Kuskokwim Delta, Alaska. The degree of differentiation in mtDNA haplotype frequency among breeding regions and populations within regions was high (phiCT = 0.189, P < 0.01; phiSC = 0.059, P < 0.01, respectively). Eleven of 17 mtDNA haplotypes were restricted to a single breeding region. Genetic differences among regions were considerably lower for nuclear DNA loci (sex-linked: phiST = 0.001, P > 0.05; biparentally inherited microsatellites: mean theta = 0.001, P > 0.05) than was observed for mtDNA. Using models explicitly designed for uniparental and biparentally inherited genes, estimates of spatial divergence based on nuclear and mtDNA data together with elements of the species' breeding ecology were used to estimate effective population size and degree of male and female gene flow. Differences in the magnitude and spatial patterns of gene correlations for maternally inherited and nuclear genes revealed that females exhibit greater natal philopatry than do males. Estimates of generational female and male rates of gene flow among breeding regions differed markedly (3.67 x 10(-4) and 1.28 x 10(-2), respectively). Effective population size for mtDNA was estimated to be at least three times lower than that for biparental genes (30,671 and 101,528, respectively). Large disparities in population sizes among breeding areas greatly reduces the proportion of total genetic variance captured by dispersal, which may accelerate rates of inbreeding (i.e., promote higher coancestries) within populations due to nonrandom pairing of males with females from the same breeding population.

Animals↗
PubMed2000

[Alcohol consumption among patients aged 65 and over in an emergency medical department. A comparison between medical records and interviews].

METHODS: Two hundred and seven randomly selected patients more than 65 years of age were interviewed about their alcohol habits in a max. 15 minutes interview. The consumption was classified as "borderline consumption" (BC): 14/21 drinks per week female/male, "heavy users" (HU): more than 14/21 drinks per week female/male and "control group" (CG): less than 14/21 drinks per week female/male. RESULTS: Twenty-five percent of the patients were BC or HU. Thirty-one percent of the HU had unspecified vertigo/falling tendency compared to 2% in the CG. Sixty-three percent of the HU and 77.7% of the BC were registered in their medical notes as having "no alcohol consumption" or a much lower (50%) consumption than that found by interview. DISCUSSION: It is concluded, that you get a better estimate of alcohol consumption by asking: "How/when do you use alcohol?" and thereafter calculating the intake.

Aged↗
PubMed2000

Characterization and variability of endotoxin and 3-hydroxy fatty acids in an office building during a particle intervention study.

Air and dust samples were collected on two floors of an office building during a double-blind particle intervention study to examine spatial and temporal variability of airborne endotoxin over a period of weeks, and to characterize endotoxin activity and lipopolysaccharide (LPS) content in carpet and chair dust. Air samples were collected on multiple days within and across weeks. Dust samples were collected from carpets and chairs one day per week for three weeks. Endotoxin was measured using a Limulus assay. Dust samples were analyzed for LPS by determination of 3-hydroxy fatty acids (3-OHFAs) using gas chromatography-mass spectrometry. The geometric mean (geometric standard deviation) for 96 indoor air samples was 0.24 (1.6) EU/m3. Significant within-floor spatial variation of airborne endotoxin was found (P < 0.0001, n = 80). Temporal variability of airborne endotoxin was not significant across weeks. Mean (+/- SD) endotoxin levels in carpet dust (59 +/- 9.3 EU/mg dust, n = 12) and in chair dust (38 +/- 7.7 EU/mg dust, n = 10) were significantly different (P < 0.001). Carbon chain length-dependent differences in 3-OHFA levels by dust source and floor were found. Enhanced air filtration did not significantly affect airborne endotoxin (P = 0.62); however, total dust mass and total endotoxin in carpet dust samples increased significantly after enhanced surface cleaning (P < 0.01). These findings suggest that spatial variability, dust source, and surface cleaning may influence building occupant exposures to endotoxin.

Air Pollution, Indoor↗
PubMed2000

Use of accelerometers as an ergonomic assessment method for arm acceleration-a large-scale field trial.

Ergonomists need easy-to-use, quantitative job evaluation methods to assess risk factors for upper extremity work-related musculoskeletal disorders in field-based epidemiology studies. One device that may provide an objective measure of exposure to arm acceleration is a wrist-worn accelerometer or activity monitor. A field trial was conducted to evaluate the performance of a single-axis accelerometer using an industrial population (n=158) known to have diverse upper limb motion characteristics. The second phase of the field trial involved an examination of the relationship between more traditional observation-based ergonomic exposure measures and the monitor output among a group of assembly-line production employees (n=48) performing work tasks with highly stereotypic upper limb motion patterns. As expected, the linear acceleration data obtained from the activity monitor showed statistically significant differences between three occupational groups known observationally to have different upper limb motion requirements. Among the assembly-line production employees who performed different short-cycle assembly work tasks, statistically significant differences were also observed. Several observation-based ergonomic exposure measures were found to explain differences in the acceleration measure among the production employees who performed different jobs: hand and arm motion speed, use of the hand as a hammer, and, negatively, resisting forearm rotation from the torque of a power tool. The activity monitors were found to be easy to use and non-intrusive, and to be able to distinguish arm acceleration among groups with diverse upper limb motion characteristics as well as between different assembly job tasks where arm monitors were performed repeatedly at a fixed rate.

Acceleration↗
PubMed2000

Natural rubber latex: glove use, sensitization, and airborne and latent dust concentrations at a Denver hospital.

Exposure to natural rubber latex may cause immediate hypersensitivity reactions. Published latex sensitization prevalence rates range from 2.9% to 22% among health care workers, and from 0.12% to about 20% of occupationally unexposed populations. In this study, self-administered questionnaires addressed job and personal characteristics, glove use, and symptoms in two groups of hospital workers: those who regularly used latex gloves and those who did not. Serum was tested for latex-specific immunoglobulin E. Air, surface, and air-filter dust samples for natural rubber latex were collected. The prevalence of latex sensitization was 6.3% in the non-users and 6.1% in the latex glove users (P = 0.9); 81.3% of sensitized workers were atopic compared with 59.5% of non-sensitized workers (P < 0.05). Reporting of work-related hand dermatitis was more common in the latex glove users (23.4%) than in the non-users (4.9%), as were rhino-conjunctivitis (16.3% and 7.9%, respectively, [P < 0.01]), and hand urticaria (9.9% and 2.1%, respectively, [P < 0.01]). There was no significant difference in work-related symptoms between the sensitized and non-sensitized workers. Environmental concentrations of latex were higher in the work areas of the non-sensitized workers, but higher in the clinical than in the non-clinical areas. Occupational latex glove use was not a risk factor for sensitization.

Adult↗
PubMed1999

Concerns of the dry-cleaning industry: a qualitative investigation of labor and management.

BACKGROUND: Occupational scientists agree there are hazards associated with dry-cleaning, but do dry-cleaning owners and workers concur? Knowledge of owners' and workers' perceptions can help guide intervention efforts to reduce worker exposure. To better understand these issues, a qualitative study was conducted using focus group methodology and constant comparative analysis. METHODS: Two owner and four worker focus groups were held. RESULTS: Findings suggest that overall, health and safety issues were not of great concern. Owners were primarily concerned with the economic impact of regulations. Workers did express some anxiety about solvent exposure and burns, but most felt that these hazards were "just part of the job." Also, other than the installation of air-conditioning in the shops and the provision of health benefits, workers could not think of ways health and safety on the job could be improved. CONCLUSIONS: These findings will be used to develop comprehensive safety and health interventions (e.g., engineering plus education and training) in dry-cleaning shops.

Air Conditioning↗
PubMed1999

Blood lead levels among children of lead-exposed workers: A meta-analysis.

BACKGROUND: To further assess the utility of targeted blood lead screening for children from households with members having occupational lead exposures, we conducted a meta-analysis of all available reports of take-home lead exposures. Our objective was to estimate the blood lead levels among U.S. children (ages 1-5) from households with lead-exposed workers. METHODS: Reports considered for inclusion were cited in Medline, Toxline, Excerpta Medica, and Bio-Med plus all unpublished reports available at the National Institute for Occupational Safety and Health through 1994. The a priori criteria for inclusion of U.S. reports required their having data on: (1) venous blood lead levels for children, (2) children's ages, (3) data for at least five children, (4) workers' occupations, (5) workers' blood lead levels, and (6) data collection methods. RESULTS: Based on a meta-analysis of 10 reports from 1987 through 1994, the children (n=139) of lead-exposed workers (n=222) had a geometric mean blood lead level of 9.3 microg/dL compared to a U.S. population geometric mean of 3.6 microg/dL (P=0.0006). Also in this group, 52% of the children had blood lead levels (BLLs) >/= 10 microg/dL compared to 8.9% in the U.S. (P=.0010), and 21% of the children had BLLs >/= 20 microg/dL compared to 1.1% in the U.S. (P=. 0258). CONCLUSIONS: We estimate, based on 1981-83 survey data, that there are about 48,000 families with children under six living with household members occupationally exposed to lead. If the findings from this meta-analysis (admittedly limited by small numbers) are generalizable, about half of the young children in these families may have BLLs >/= 10 microg/dL. Data were too sparse to determine if children of workers with elevated blood leads were at greater risk than children whose parents were only known to be lead exposed. Our findings support the position that children of lead-exposed workers should be targeted for blood lead screening. Am. J. Ind. Med. 36:475-481, 1999. Published 1999 Wiley-Liss, Inc.

Child, Preschool↗
PubMed1998

Prevalence proportion ratios: estimation and hypothesis testing.

BACKGROUND: Recent communications have argued that often it may not be appropriate to analyse cross-sectional studies of prevalent outcomes with logistic regression models. The purpose of this communication is to compare three methods that have been proposed for application to cross sectional studies: (1) a multiplicative generalized linear model, which we will call the log-binomial model, (2) a method based on logistic regression and robust estimation of standard errors, which we will call the GEE-logistic model, and (3) a Cox regression model. METHODS: Five sets of simulations representing fourteen separate simulation conditions were used to test the performance of the methods. RESULTS: All three models produced point estimates close to the true parameter, i.e. the estimators of the parameter associated with exposure had negligible bias. The Cox regression produced standard errors that were too large, especially when the prevalence of the disease was high, whereas the log-binomial model and the GEE-logistic model had the correct type I error probabilities. It was shown by example that the GEE-logistic model could produce prevalences greater than one, whereas it was proven that this could not happen with the log-binomial model. The log-binomial model should be preferred.

Cross-Sectional Studies↗
PubMed1997

Chest radiography in Portland cement workers.

To investigate the prevalence of pneumoconiosis in Portland cement workers, a controlled cross-sectional survey was conducted. Chest radiographs of approximately 2640 Portland cement workers showed prevalence rates of about 1% for rounded and for irregular small opacities and about 2% for pleural abnormalities. After age and smoking adjustment, the overall prevalences were still significantly elevated over controls, but when examined separately by smoking status, the significant increases were confined to smokers. Although statistically significant, the prevalences were only elevated about 1% in cement workers, compared with controls. A statistically significant relationship with exposure was found for pleural abnormalities but not for rounded or irregular small opacities. Thus a weak association exists between pulmonary radiographic abnormalities and employment in US Portland cement plants, and there appears to be a dose-response relationship between exposure and pleural abnormalities.

Adult↗
PubMed1995

Lead poisoning of spectacled eiders (Somateria fischeri) and of a common eider (Somateria mollissima) in Alaska.

Lead poisoning was diagnosed in four spectacled eiders (Somateria fischeri) and one common eider (Somateria mollissima) found dead or moribund at the Yukon Delta National Wildlife Refuge, Alaska (USA) in 1992, 1993, and 1994. Ingested lead shot was found in the lower esophagus of one spectacled eider and in the gizzard of the common eider. Lead concentrations in the livers of the spectacled eiders were 26 to 38 ppm wet weight, and 52 ppm wet weight in the liver of the common eider. A blood sample collected from one of the spectacled eiders before it was euthanized had a lead concentration of 8.5 ppm wet weight. This is the first known report of lead poisoning in the spectacled eider, recently listed as a threatened species by the U.S. Fish and Wildlife Service.

Alaska↗
PubMed1992

Dendritic field size and morphology of midget and parasol ganglion cells of the human retina.

The visual system of the macaque monkey has provided a useful model for understanding the neural basis of human vision, yet, there are few detailed comparisons of neural populations other than photoreceptors for the two species. Using intracellular staining in an in vitro preparation of the isolated and intact human retina, we have characterized the relationship of dendritic field size to retinal eccentricity for the two major ganglion cell classes, the midget and the parasol cells. We report three findings. (i) The difference in dendritic field diameter between the parasol and midget cells increases from a ratio of approximately 3:1 in the retinal periphery to approximately 10:1 at 3 degrees eccentricity, suggesting that human midget cells may outnumber parasol cells by as much as 30:1 in the central retina. (ii) The dendritic fields of human ON-center parasol and midget cells are 30-50% larger in diameter than their OFF-center counterparts, suggesting a distinct asymmetry in the human ON-OFF visual pathways. (iii) The dendritic fields of parasol cells, but not midget cells, are larger in humans than in macaques. The difference increases from approximately 20% in the retinal periphery to approximately 90% at 5 degrees eccentricity. This result predicts that the human parasol cells should show a lower resolving ability and an increased sensitivity to luminance contrast than their equivalents in the macaque.

Animals↗
PubMed1992

Differential sensitivity of Japanese macaques (Macaca fuscata) and humans (Homo sapiens) to peak position along a synthetic coo call continuum.

Difference limens (DLs) for changes in the temporal position of a pitch peak along a synthetic early-high to late-high coo continuum were measured in 2 Japanese macaques (Macaca fuscata) and 2 humans (Homo sapiens) in a low-uncertainty, repeating standard discrimination procedure. Lowest DLs (19-32 ms for monkeys; less than 10 ms for humans) occurred near the endpoints of the continuum. Highest DLs (59-73 ms for monkeys; 25-27 ms for humans) occurred near the center of the continuum. DLs for both monkeys and humans corresponded to previously reported measures of temporal resolution. Neither monkeys nor humans exhibited categorical perception of the coo continuum, with a central area of enhanced sensitivity, a result previously reported by May, Moody, and Stebbins (1989) for similar stimuli. We conclude that our subjects discriminated variation in coo peak position by using general psychoacoustic mechanisms related to temporal discrimination.

Adult↗
PubMed1990

Progression of diabetic retinopathy after pancreas transplantation. The University of Michigan Pancreas Transplant Evaluation Committee.

The progression of diabetic retinopathy after combined pancreatic and kidney transplantation was studied in eight patients for 12 to 49 months. Four patients who had rapid pancreatic graft failure constituted a control group for comparison with four patients who retained functioning grafts. Using Fisher's exact probability test, the authors found no posttransplantation difference between the two groups in visual acuity lost, severity of diabetic macular edema, extent of capillary closure, progression of preretinal gliosis, development of disc or preretinal neovascularization, or worsening of the severity of the retinopathy. Achievement of normoglycemia by pancreatic transplantation is not effective in halting the progression of diabetic retinopathy in patients who already have severe diabetic microangiopathy joined the current follow-up.

Adult↗