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R Lemen

Publications and source records attributed to R Lemen.

15 recordsLinked to original sources
PubMed1997

Exposure-response analysis of risk of respiratory disease associated with occupational exposure to chrysotile asbestos.

OBJECTIVES: To evaluate alternative models and estimate risk of mortality from lung cancer and asbestosis after occupational exposure to chrysotile asbestos. METHODS: Data were used from a recent update of a cohort mortality study of workers in a South Carolina textile factory. Alternative exposure-response models were evaluated with Poisson regression. A model designed to evaluate evidence of a threshold response was also fitted. Lifetime risks of lung cancer and asbestosis were estimated with an actuarial approach that accounts for competing causes of death. RESULTS: A highly significant exposure-response relation was found for both lung cancer and asbestosis. The exposure-response relation for lung cancer seemed to be linear on a multiplicative scale, which is consistent with previous analyses of lung cancer and exposure to asbestos. In contrast, the exposure-response relation for asbestosis seemed to be nonlinear on a multiplicative scale in this analysis. There was no significant evidence for a threshold in models of either the lung cancer or asbestosis. The excess lifetime risk for white men exposed for 45 years at the recently revised OSHA standard of 0.1 fibre/ml was predicted to be about 5/1000 for lung cancer, and 2/1000 for asbestosis. CONCLUSIONS: This study confirms the findings from previous investigations of a strong exposure-response relation between exposure to chrysotile asbestos and mortality from lung cancer, and asbestosis. The risk estimates for lung cancer derived from this analysis are higher than those derived from other populations exposed to chrysotile asbestos. Possible reasons for this discrepancy are discussed.

Adult↗
PubMed1997

Ragweed sensitization alters pulmonary vascular responses to bronchoprovocation in beagle dogs.

In ragweed (RW)-sensitized beagle dogs, we tested the hypothesis that reactivity of the pulmonary vasculature was enhanced with aerosolized histamine (Hist) and RW. Seven dogs were neonatally sensitized with repeated intraperitoneal RW injections, and 12 dogs were controls (Con). The dogs were anesthetized with intravenous chloralose, mechanically ventilated, and instrumented with femoral arterial and pulmonary artery catheters. Specific lung compliance (CLsp), specific lung conductance (Gsp), systemic vascular resistance index, and pulmonary vascular resistance index (PVRI) were measured before and after bronchoprovocation with Hist and RW. After Hist inhalation (5 breaths of 30 mg/ml), both Con and RW dogs had significant (P < 0.05) decreases in CLsp (-51 +/- 4 and -53 +/- 5%, respectively) and Gsp (-65 +/- 5 and -69 +/- 3%, respectively), but only RW-sensitized dogs had a significant increase in PVRI (38 +/- 10%). After RW inhalation (60 breaths of 0.8 mg/ml), only RW-sensitized dogs had significant increases (62 +/- 20%) in PVRI and decreases in Gsp (-77 +/- 4%) and CLsp (-65 +/- 7%). We conclude that, compared with Con, RW-sensitized beagle dogs have increased pulmonary vasoconstrictive responses with Hist or RW inhalation.

Allergens↗
PubMed1993

Lung cancer.

Explore the source record for details and available documents.

Cadmium↗
PubMed1992

A dose-response analysis and quantitative assessment of lung cancer risk and occupational cadmium exposure.

We performed a quantitative assessment of the risk of lung cancer from exposure to cadmium based on a retrospective cohort mortality study of cadmium-exposed workers. The study population consisted of white male workers who were employed for at least 6 months at a cadmium smelter between January 1, 1940, and December 31, 1969, and who were first employed at the facility on or after January 1, 1926. The study findings were analyzed using a modified life-table analysis to estimate standardized mortality ratios (SMRs), and various functional forms (i.e., exponential, power, additive relative rate, and linear) of Poisson and Cox proportional hazards models to examine the dose-response relationship. Estimates of working lifetime risk (45 years) were developed using an approach that corrects for competing causes of death. An excess in mortality from lung cancer was observed for the entire cohort (SMR = 149, 95% confidence interval (CI) = 95, 222). Mortality from lung cancer was greatest among non-Hispanic workers (SMR = 211, 95% CI = 131, 323), among workers in the highest cadmium exposure group (SMR = 272, 95% CI = 123, 513), and among workers with 20 or more years since the first exposure (SMR = 161, 95% CI = 100, 248). A statistically significant dose-response relationship was evident in nearly all of the regression models evaluated. Based on our analyses, the lifetime excess lung cancer risk at the current Occupational Safety and Health Administration standard for cadmium fumes of 100 micrograms/m3 is approximately 50 to 111 lung cancer deaths per 1000 workers exposed to cadmium for 45 years.

Adult↗
PubMed1992

A quantitative assessment of lung cancer risk and occupational cadmium exposure.

We have performed a quantitative assessment of the risk of lung cancer from exposure to cadmium based on a retrospective cohort mortality study of cadmium-exposed workers. The findings were analysed using a life-table analysis to estimate standardized mortality ratios (SMRs), and various functional forms of Poisson and Cox proportionate hazards models to examine dose-response relationships. An excess mortality from lung cancer was observed for the entire cohort (SMR = 149,95% CI = 95-222). Lung cancer mortality was significantly elevated among non-hispanic workers, among those in the highest cadmium-exposure group, and among workers with 20 or more years since first exposure. A statistically significant dose-response relationship was evident in nearly all of the regression analyses. Based on our analyses, the lifetime excess lung cancer risk at the current OSHA standard for cadmium fumes of 100 micrograms/m3 is approximately 50-111 lung cancer deaths per 1000 workers exposed to cadmium for 45 years.

Adult↗
PubMed1983

Ferrokinetic and hematologic studies in cystic fibrosis patients.

We investigated 28 cystic fibrosis (CF) patients to determine why hypoxia from their obstructive pulmonary disease does not produce polycythemia. Oxygen saturation was lower and erythropoietin levels were higher in CF patients than in 25 age-comparable reference subjects (90.8% and 47 mimu vs. 94.7% and 29 mimu, p less than 0.01). Hematocrit and red blood cell (RBC) indices were not different between groups. Serum vitamin and iron levels, ferrokinetics, RBC volume, and RBC survival were studied in 10 of the 28 CF patients. Total iron-binding capacity and vitamin E levels were low, and serum iron, ferritin, vitamin B12, and folate levels were normal in these patients. Red blood cell survival was minimally decreased in six patients although there was no other evidence for hemolysis. Ferrokinetics (59Fe) indicated a reduction in total erythropoiesis in only two patients. Plasma volume was high-normal in five and above normal in four CF patients; RBC mass was increased appropriately for each patient's degree of hypoxia, when compared to healthy individuals living at different altitudes. These results suggest that CF patients are able to compensate for hypoxia by increasing RBC mass; however, an expanded plasma volume prevents a detectable rise in hematocrit.

2,3-Diphosphoglycerate↗
PubMed1983

Cystic fibrosis manifesting with acrodermatitis enteropathica-like eruption. Association with essential fatty acid and zinc deficiencies.

A refractory dermatitis resembling acrodermatitis enteropathica was the manifesting sign in a 5-month-old male infant with cystic fibrosis, preceding pulmonary and gastrointestinal tract symptoms by two months. The eruption was clearly nutritionally responsive. Biochemical evidence was shown for deficiencies of zinc, essential fatty acids, and protein. Altered prostaglandin metabolism was also demonstrated.

Acrodermatitis↗
PubMed1978

The influence of bronchial smooth muscle tone on critical narrowing of dependent airways.

Critical narrowing of the dependent airways was examined in anaesthetized dogs with closed chests. Two techniques were used, (a) "closing" volume (CV), measured from the expired nitrogen plateau and (b) tantalum bronchography, to measure the calibre of airways of 3-8 mm diameter in the upper (UZ), middle (MZ) and lower (LZ) zones. The point of airway "closure" at the junction of phases III and IV of the alveolar plateau coincided with an inflection in the diameter-lung volume curve of the airways in the most basal zone of the lung. This was accompanied by a sudden large increase in the calculated resistance of the airways in LZ compared with UZ. Following stimulation of the vagi CV increased and there was increased narrowing of airways, particularly in LZ. The addition of 0.5% halothane to the anaesthetic abolished the effect of vagal stimulation on CV and on airway resistance.

Airway Resistance↗
PubMed1978

Changes in airway calibre following pulmonary venous congestion.

"Closing volume" (CV) was measured in 18 anaesthetized dogs before, during and after pulmonary vascular congestion produced by inflation of a balloon placed in the left atrium. In group A 10 dogs were anaesthetized with pentobarbitone. CV increased from 30.0 +/- 1.2 to 42 +/- 5.6% of vital capacity (P less than 0.05) when pulmonary wedge pressure was increased from 0.21 +/- 0.27 to 1.54 +/- 0.44 kPa (1.6 +/- 2.0 to 11.6 +/- 3.3 mm Hg) (P less than 0.05). In seven of these 10 dogs gas exchange was impaired after an increase of left atrial pressure. These changes in lung function during pulmonary vascular congestion were not associated with an increase in lung water. In group B, eight dogs were studied after anaesthesia with chloralose and urethane. Vagotomy or vagal cooling to 0 degrees C returned CV to baseline values in six dogs with pulmonary vascular congestion. In two dogs in which bilateral vagotomy had been performed before pulmonary vascular congestion there was no change in CV after balloon inflation. Isoprenaline abolished the effect of pulmonary vascular congestion on closing volume. This suggests that the vagus mediates the changes in lung mechanics associated with pulmonary vascular congestion.

Airway Resistance↗
PubMed1975

"Closing volume" changes in alloxan-induced pulmonary edema in anesthetized dogs.

"Closing volume" (CV) was measured by the single-breath oxygen (SBO2) test in six dogs (alloxan group) before and after alloxan 100-200 mg/kg iv) was injected. CV increased significantly (P less than 0.05) from 32 +/- 3.2% (base line) to 45 +/- 3.5 % in period 1 (0-30 min after alloxan), but vital capacity (VC), respiratory system pressure volume (PV) curves, and alveolar plateau slopes did not change. No radiologic evidence of pulmonary edema was demonstrated in two dogs studied in period 1. CV decreased to 20 +/- 3.9% during period 2 (30-80 min after alloxan) and was associated with tracheal frothing, decreased VC, changes in the PV curve, and alveolar plateau slope, as well as histologic evidence of severe pulmonary edema. CV was 29 +/- 3.0%, and there were no changes in VC, PV curves, or alveolar plateau slopes in 6 other dogs studied for 2 h (control group). CV increased during period 1 before pulmonary edema could be demonstrated by changes in VC, PV curves, or radiography, but in period 2 lung function was so altered that CV by the SBO2 technique gave no useful information.

Alloxan↗
PubMedDate not supplied

A retrospective cohort mortality study of a phosphate fertilizer production facility.

A retrospective cohort mortality study of phosphate fertilizer production workers was undertaken to determine whether this group is at increased risk of dying from any cause, particularly from lung cancer. A total of 3,199 workers who had ever been employed at one facility were included in this investigation. These workers were followed for vital status ascertainment from their first date of employment up to December 1, 1977, or the date of death, whichever occurred first. Overall, no statistically significant elevations in cause-specific mortality were observed for the entire study population. However, when the analysis was stratified by duration of employment, and length of follow-up, a statistically significant (P less than .05) excess in lung cancer mortality was observed among workers with more than 10 yr of employment and follow-up (standardized mortality ratio = 411). Because of the small number of deaths involved, and because we had prior knowledge of a lung cancer cluster at this plant, we believe that these findings should be viewed as suggestive, and that other investigations in plants with similar exposures are needed to clarify whether an occupationally related lung cancer excess truly exists.

Adolescent↗