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G R Petersen

Publications and source records attributed to G R Petersen.

At least 19 recordsLinked to original sources
PubMed1992

Evaluating strategies for health surveillance. Health event ascertainment at a nuclear facility.

The US Department of Energy's Health Surveillance System is a pilot project to design, implement, and evaluate a system of routine morbidity surveillance based on routinely collected occupational medical data at participating Department of Energy facilities. At the Hanford Site, most health events have been ascertained using a 21-day threshold-of-absence criterion. This provisional threshold, established under the assumption that it would capture all important morbidity, has been criticized as potentially omitting morbidity of interest. A review of all health-event absences occurring over a 1-year period revealed that the efficacy of the 21-day threshold varies widely by diagnosis and that absence based eligibility criteria are not useful for all morbidity of interest. Future development will require supplementation of health-event ascertainment by other, diagnosis-based criteria to ensure completeness of ascertainment.

Absenteeism↗
PubMed1990

Methods for analyzing combined data from studies of workers exposed to low doses of radiation.

Epidemiologic studies of workers exposed occupationally to protracted low doses of radiation provide a direct assessment of health effects resulting from such exposure and thus supplement information provided by studies of populations exposed at high doses of radiation and high dose rates. Analyses based on combined data from several studies can be expected to provide a more thorough assessment of low dose occupational studies and more precise risk estimates than can be obtained from any single study. Statistical methods for conducting such combined analyses are discussed, and different approaches, such as basing analyses on various levels of aggregation of exposure data, are compared and evaluated. Emphasis is given to methods for obtaining risk estimates and confidence limits that can be appropriately compared with estimates that form the basis for current radiation protection standards; these estimates have been obtained through extrapolation from high dose data. Methods are illustrated using combined data on workers at three US Department of Energy facilities: the Hanford Site, Richland, Washington; the Oak Ridge National Laboratory, Oak Ridge, Tennessee; and the Rocky Flats Nuclear Weapons Plant, Denver, Colorado.

Colorado↗
PubMed1990

A case-cohort study of lung cancer, ionizing radiation, and tobacco smoking among males at the Hanford Site.

Results of several epidemiological studies of workers exposed occupationally to low levels of radiation have been reported but have not included data on smoking. The authors conducted a case-cohort study of male workers at the Hanford Site with an objective of investigating the association between lung-cancer risk and occupational radiation exposure with appropriate adjustment for tobacco use. Eighty-six lung-cancer deaths for the period 1965-1980 and a stratified random sample of 445 subcohort members were included in the study. Tobacco-use data were obtained from medical records collected over each subject's period of employment. Data from this study were analyzed using methods that took into account both the case-cohort design and changes over time in the quality of the tobacco-use data collected. Tobacco use was not strongly related to the level of radiation exposure, and adjustment for tobacco use did not greatly modify results of analyses assessing the association between lung-cancer risk and cumulative dose equivalent. With or without adjustment for tobacco use, the estimated risks per unit of cumulative dose equivalent were negative, but the 95% confidence intervals were wide and included values several times those estimated from populations with high levels of irradiation.

Cohort Studies↗
PubMed1989

Rheologically interesting polysaccharides from yeasts.

We have examined the relationships between primary, secondary, and tertiary structures of polysaccharides exhibiting the rheological property of friction (drag) reduction in turbulent flows. We found an example of an exopolysaccharide from the yeast Cryptococcus laurentii that possessed high molecular weight but exhibited lower than expected drag reducing activity. Earlier correlations by Hoyt showing that beta 1 --> 3, beta 2 --> 4, and alpha 1 --> 3 linkages in polysaccharides favored drag reduction were expanded to include correlations to secondary structure. The effect of sidechains in a series of gellan gums was shown to be related to sidechain length and position. Disruption of secondary structure in drag reducing polysaccharides reduced drag reducing activity for some but not all exopolysaccharides. The polymer from C. laurentii was shown to be more stable than xanthan gum and other exopolysaccharides under the most vigorous of denaturing conditions. We also showed a direct relationship between extensional viscosity measurements and the drag reducing coefficient for four exopolysaccharides.

Biopolymers↗
PubMed1989

Phase separated membrane bioreactor: results from model system studies.

The operation and evaluation of a bioreactor designed for high intensity oxygen transfer in a microgravity environment is described. The reactor itself consists of a zero headspace liquid phase separated from the air supply by a long length of silicone rubber tubing through which the oxygen diffuses in and the carbon dioxide diffuses out. Mass transfer studies show that the oxygen is film diffusion controlled both externally and internally to the tubing and not by diffusion across the tube walls. Methods of upgrading the design to eliminate these resistances are proposed. Cell growth was obtained in the fermenter using Saccharomyces cerevisiae showing that this concept is capable of sustaining cell growth in the terrestrial [correction of terrestial] simulation.

Carbon Dioxide↗
PubMed1989

Units and terminology of radiation measurement: a primer for the epidemiologist.

The utility and even the validity of radiation epidemiology studies rest upon the quality of the underlying radiologic data and the correctness of their interpretation. To ensure meaningful and comparable results, radioepidemiologic studies need to properly and consistently use radiologic quantities and units, and to evaluate and fully discuss the radiologic measurements and their interpretation, recognizing that experts in health physics may differ in their assessments. As succinctly stated by Polya Two persons presented with the same evidence and applying the same patterns of plausible inference may honestly disagree.

Epidemiology↗
PubMed1989

Mortality of workers at the Hanford site: 1945-1981.

Analyses of mortality of workers at the Hanford Site were updated to include an additional three years of data (1979-81). Deaths occurring in the state of Washington in the years 1982-85 were also evaluated. Hanford workers continued to exhibit a strong healthy worker effect with death rates substantially below those of the general U.S. population. Comparisons by level of radiation exposure within the Hanford worker population provided no evidence of a positive correlation of radiation exposure and mortality from all cancers combined or of mortality from leukemia. Estimates of cancer risk due to radiation were negative, but confidence intervals were wide, indicating that the data were consistent with no risk and with risks several times larger than estimates provided by major groups concerned with risk assessment. Of 18 categories of cancer analyzed, a correlation of borderline statistical significance was identified for female genital cancers (p = 0.05), but was interpreted as probably spurious. The previously identified correlation for multiple myeloma persisted (p = 0.002).

Environmental Exposure↗
PubMed1989

Use of return-to-work medical clearance data for health surveillance.

The US Department of Energy's Health Surveillance System pilot project attempts to monitor the occurrence of major morbidity among active workers through return-to-work medical clearance data. Anecdotal information has suggested that salaried and wage-earning employees differ in compliance with medical clearance policy. Personnel data regarding illness absences among one contractor's employees were used to identify 216 illness absences eligible for medical clearance and medical records were reviewed to determine whether return-to-work clearance had been obtained. Although compliance improved with increasing duration of absence among both salaried and wage-earning employees, overall it was significantly higher among wage-earning than salaried employees.

Absenteeism↗
PubMed1989

Analyses of combined mortality data on workers at the Hanford Site, Oak Ridge National Laboratory, and Rocky Flats Nuclear Weapons Plant.

An important objective of studies of workers exposed occupationally to chronic low doses of ionizing radiation is to provide a direct assessment of health risks resulting from this exposure. This objective is most effectively accomplished by conducting combined analyses that allow evaluation of the totality of evidence from all study populations. In this paper, combined analyses of mortality in workers at the Hanford Site, Oak Ridge National Laboratory, and Rocky Flats Nuclear Weapons Plant are presented. These combined analyses provide no evidence of a correlation between radiation exposure and mortality from all cancer or from leukemia. Of 11 other specific types of cancer analyzed, multiple myeloma was the only cancer found to exhibit a statistically significant correlation with radiation exposure. Estimates of the excess risk of all cancer and of leukemia, based on the combined data, were negative. Upper confidence limits based on the combined data were lower than for any single population, and were similar to estimates obtained from recent analyses of A-bomb survivor data. These results strengthen support for the conclusion that estimates obtained through extrapolation from high-dose data do not seriously underestimate risks of low-dose exposure, but leave open the possibility that extrapolation may overestimate risks.

Adult↗
PubMed1988

Reproducible analyses of microbial food for advanced life support systems.

The use of yeasts in Controlled Ecological Life Support Systems (CELSS) for microbial food regeneration in space required the accurate and reproducible analysis of intracellular carbohydrate and protein levels. The reproducible analysis of glycogen was a key element in estimating overall content of edibles in candidate yeast strains. Typical analytical methods for estimating glycogen in Saccharomyces were not found to be entirely applicable to other candidate strains. Rigorous cell lysis coupled with acid/base fractionation followed by specific enzymatic glycogen analyses were required to obtain accurate results in two strains of Candida. A profile of edible fractions of these strains was then determined. The suitability of yeasts as food sources in CELSS food production processes is discussed.

Candida↗
PubMed1985

Determining a carbohydrate profile for Hansenula polymorpha.

The determination of the levels of carbohydrates in the yeast Hansenula polymorpha required the development of new analytical procedures. Existing fractionation and analytical methods were adapted to deal with the problems involved with the lysis of whole cells. Using these new procedures, the complete carbohydrates profiles of H. polymorpha and selected mutant strains were determined and shown to correlate favourably with previously published results.

Carbohydrates↗
PubMed1984

The California Automated Mortality Linkage System (CAMLIS).

The California Automated Mortality Linkage System (CAMLIS), established in 1981 to facilitate the conduct of follow-up studies in the State of California, employs a combination of deterministic and probabilistic linkage decision criteria to perform the death clearance function. The system was evaluated against four traditional death clearance procedures and the performance of each procedure measured in terms of measures of sensitivity and specificity. Only one procedure was associated with a specificity lower than 0.99; for that one, the specificity was 0.93. There was much greater fluctuation in the observed sensitivity levels. In one of the procedures, CAMLIS demonstrated a sensitivity of 0.97 versus 0.79 for the Social Security Administration. A comparison against the National Death Index (NDI) produced sensitivities of 0.89 for CAMLIS and 0.94 for the NDI. An assessment of manual search procedures using a file of Japanese names produced a CAMLIS sensitivity measure of 0.92 compared with 0.93 for the manual search. Another manual search procedure using microfiche copies of the state death index produced a CAMLIS sensitivity of 0.97; in this evaluation, the sensitivity of the manual search was defined as 1.0. Another measure of performance of a death clearance procedure is its predictive value in identifying a person who has died; CAMLIS generated predictive values in these evaluations that ranged from 0.93 through 0.99, contrasted with the NDI value of 0.59.

California↗
PubMed1983

Biosynthesis and degradation of storage protein in spores of the fungus Botryodiplodia theobromae.

Muiridin, a spore-specific protein of the fungus Botryodiplodia theobromae, comprises about 25% of the mature pycnidiospore protein. It has an apparent molecular weight of 16,000 to 17,000 and is rich in glutamine, asparagine, and arginine. Muiridin is synthesized in developing spores via a precursor with an apparent molecular weight of 24,000. Two other polypeptides present in young developing spores with apparent molecular weights of 18,000 and 15,000 are immunologically related to muiridin. We propose a pathway for muiridin synthesis. Muiridin is actively degraded during the germination of spores from 30-day-old cultures. This degradation is independent of exogenous amino acids in the germination medium. In contrast, glutamine and, to a lesser extent, asparagine partially inhibit the degradation of muiridin during germination of spores from 7-day-old cultures.

Amino Acids↗
PubMed1979

The influence of age, year of birth, and date on mortality from malignant melanoma in the populations of England and Wales, Canada, and the white population of the United States.

The age-adjusted death rates from malignant melanoma of the skin have increased from 1951 to 1975 by about 3% per year in the populations of England and Wales, Canada, and the white population of the US. This is due to large increases in risk of successively later born cohorts. Any effects of earlier diagnosis of improved treatment within the period 1951--1975 have been sufficiently steady to fail to alter these trends. The slope of the log rates with log age is about 3.5. Projections of rates for at least the next decade can be made with some confidence, and provide a basis for evaluating control measures.

Adult↗
PubMed1978

Mortality of California agricultural workers.

The mortality of white male farm laborers and farm operators in California for the years 1959 to 1961 was examined. Cause-specific mortality rates were calculated in order to identify diseases which might be of occupational importance. The mortality rate from respiratory diseases in the farm laborer groups (employees) was triple the rate in the farm management group (employers or self-employed individuals). Accidental deaths were also increased in the farm laborer group. Hazards of the agricultural industry which could contribute to accidents and respiratory disease were reviewed.

Adult↗
PubMed1976

Enzymatic synthesis of duplex circular phiX174 DNA containing phosphoramidate bonds in the (-) strand.

Duplex circular phiX174 DNA (RF I) containing some phosphoramidate links in the backbone chain of the (-) strand was synthesized by reaction of 5'-amino-5'-deoxythymidine 5'-triphosphate, dCTP, dGTP, and 3H-dATP with DNA polymerase I and DNA ligase (T4) on a (+) strand phiX174 amber 3 DNA template. The yield of duplex DNA was higher when dTTP was included along with the amino analog in the initial reaction system or was added late in the synthesis. RF I DNA was observed as a rapidly sedimenting species in an alkaline sucrose gradient, and the presence of phosphoramidate linkages was demonstrated by the unusual lability of the duplex DNA in a weakly acidic solution.

Amides↗