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Biomedical subjects

A Sigurdson

Publications and source records attributed to A Sigurdson.

At least 19 recordsLinked to original sources
PubMed2005

Incidence of haematopoietic malignancies in US radiologic technologists.

BACKGROUND: There are limited data on risks of haematopoietic malignancies associated with protracted low-to-moderate dose radiation. AIMS: To contribute the first incidence risk estimates for haematopoietic malignancies in relation to work history, procedures, practices, and protective measures in a large population of mostly female medical radiation workers. METHODS: The investigators followed up 71,894 (77.9% female) US radiologic technologists, first certified during 1926-80, from completion of a baseline questionnaire (1983-89) to return of a second questionnaire (1994-98), diagnosis of a first cancer, death, or 31 August 1998 (731,306 person-years), whichever occurred first. Cox proportional hazards regression was used to compute risks. RESULTS: Relative risks (RR) for leukaemias other than chronic lymphocytic leukaemia (non-CLL, 41 cases) were increased among technologists working five or more years before 1950 (RR = 6.6, 95% CI 1.0 to 41.9, based on seven cases) or holding patients 50 or more times for x ray examination (RR = 2.6, 95% CI 1.3 to 5.4). Risks of non-CLL leukaemias were not significantly related to the number of years subjects worked in more recent periods, the year or age first worked, the total years worked, specific procedures or equipment used, or personal radiotherapy. Working as a radiologic technologist was not significantly linked with risk of multiple myeloma (28 cases), non-Hodgkin's lymphoma (118 cases), Hodgkin's lymphoma (31 cases), or chronic lymphocytic leukaemia (23 cases). CONCLUSION: Similar to results for single acute dose and fractionated high dose radiation exposures, there was increased risk for non-CLL leukaemias decades after initial protracted radiation exposure that likely cumulated to low-to-moderate doses.

Adult↗
PubMed2000

Gender difference in smoking effect on chromosome sensitivity to gamma radiation in a healthy population.

In the general population, there is variation in radiosensitivity associated with cancer risk. However, data on the role of epigenetic factors in the variation of radiosensitivity are scarce. Thus we investigated the effects of smoking and age on the radiosensitivity of human lymphocytes by measuring the frequency of chromosome aberrations after in vitro exposure to gamma rays in peripheral lymphocytes from 441 healthy subjects (18-95 years old). We analyzed the frequency of both spontaneous (baseline) and in vitro gamma-ray-induced (1.5 Gy) chromatid breaks in 50 well-spread metaphases per subject. The overall mean frequencies of spontaneous and induced breaks were 0.02 and 0.45 per cell, respectively. The mean frequency of induced breaks was significantly higher in men than in women (P = 0.03) but did not differ by age or ethnicity. Donors who had ever smoked showed a small but significantly increased frequency of induced breaks (mean = 0.47) compared to nonsmokers (mean = 0.41; P = 0.005). Further stratification and multivariate analyses revealed that the smoking effect was more pronounced in men than in women. These findings support a smoking effect on radiosensitivity in a healthy population, particularly in men. Therefore, when evaluating the association between radiosensitivity and susceptibility to smoking-related cancers, the effect of smoking should be taken into account.

Adult↗
PubMed1999

Three measures of mutagen sensitivity in a cancer-free population.

Different individuals appear to respond differently to the same carcinogen, and different mutagens act differently on cells. We conducted mutagen sensitivity assays by using three mutagens (bleomycin, a radiomimetic agent; 4-nitroquinoline-1-oxide [4-NQO], an ultraviolet light mimetic agent; and benzo[a]pyrene diol epoxide [BPDE], a tobacco mutagen) in parallel in healthy human subjects to determine the relationships among these assays. Our results showed that the mean breaks per cell values (b/c) (+/- SD) for bleomycin, 4-NQO, and BPDE sensitivity were 0.49 (+/- 0.26), 0.53 (+/- 0.30), and 0.66 (+/- 0.41), respectively. Age, sex, smoking status, and family history of cancer were not correlated with any of these mutagen sensitivities. Also, there was no correlation between bleomycin and 4-NQO or 4-NQO and BPDE sensitivity, but a weak correlation between bleomycin and BPDE was observed (correlation coefficient = 0.289; P = 0.001). When the 75th percentile of b/c was used as a cutoff point in each assay, only one individual (1.8%) was sensitive to all three mutagens. Ten individuals (17.9%) were sensitive to two mutagens, 20 (35.7%) to one mutagen, and 25 (44.6%) to none of three mutagens. Our study suggests that these three mutagens may involve different DNA damage and repair pathways. The lack of correlation between the assay results may indicate the necessity of using a battery of mutagen sensitivity tests to refine our ability to identify a subpopulation at high cancer risk.

4-Nitroquinoline-1-oxide↗
PubMed1998

Assessing the burden of cancer in Texas using vital statistics data.

BACKGROUND: Vital statistics data were used to describe the burden of cancer in Texas. METHODS: Average annual age-adjusted mortality data in Texas (1986 to 1990) for 17 cancer types were compared with the US data for whites and blacks and with California data for Hispanics. Trends were examined from 1980 to 1990 for the entire state and from 1976 to 1989 for 24 geographic regions within the state. RESULTS: Mortality excesses were detected for lung and liver cancer, and deficits for colorectal, breast, and prostate cancers. Rates were generally stable from 1980 to 1990 with several exceptions (lung, liver, colon). Six areas of Texas, including four areas along the Gulf Coast, had relatively more excesses of various cancers, without a discernible pattern by cancer type. CONCLUSIONS: Overall, Texas has fared favorably in cancer mortality when compared with the United States. Enhanced evaluation of the frequency of cancer, as well as the conduct of etiologic research, must await the availability of statewide long-term cancer incidence data.

Black or African American↗
PubMed1997

Cancer mortality among petroleum refinery and chemical manufacturing workers in Texas.

Epidemiologic historical cohort studies of petroleum refinery and chemical manufacturing workers in Texas were reviewed to examine their cancer mortality in comparison to the U.S. and to assess the possible impact of cancer mortality among these workers on the State of Texas as a whole. Summary standardized mortality ratios and 95% confidence intervals were calculated for 20 cancer types, taking into account the heterogeneity of individual studies. There were 4314 cancer deaths among the 92,318 workers employed in 10 independent plant populations. Overall, there was a significant deficit in cancer mortality among petrochemical workers compared with the general U.S. population (SMR = 88, 95% CI = 80 to 96). Only the summary SMRs for brain cancer (SMR = 113, 95% CI = 96 to 133) and leukemias (SMR = 112, 95% CI = 94 to 130) approached statistical significance. Lung and liver cancer mortality excesses, noted for Texas as a whole, were decreased in these workers. Additional follow-up of these cohorts, their expansion to include minority and female workers, and additional study of possible occupational contributions to leukemia and brain cancer are recommended.

Chemical Industry↗
PubMed1983

Hyperplastic lesions of the gingiva and alveolar mucosa. A study of 175 cases.

175 'epulides' were studied clinically and histologically. The lesions were histologically reclassified into three groups: granulomatous, fibromatous and giant cell lesions. The granulomatous group was four times and the giant cell group 1.5 times more frequent in females. It is suggested that the expression epulis should be abandoned as a microscopic designation for lesions in the oral mucosa, as it is only a non-specific topographico-clinical concept comprising histogenetically and histomorphologically differing lesions and therefore does not represent a uniform group. The suggested new terms for the three types of hyperplastic lesions are oral mucosal granulomatous hyperplasias (including such diagnostic terms as granulomatous gingivitis, gingivitis of pregnancy, granuloma gravidarium, pyogenic granuloma, epulis angiomatosa and epulis telangiectaticum), oral mucosal fibrous hyperplasias (including such diagnostic terms as fibrous epulis, epulis fissuratum, fibroepithelial lesions, denture injury tumor and peripheral odontogenic fibroma) and oral mucosal giant cell hyperplasia (including such diagnostic terms as peripheral giant cell granuloma and giant cell epulis).

Adolescent↗
PubMed1979

Collection of cytological specimens with a cell aspirator with reference to the wooden spatula method. II. Comparative quantitative and qualitative studies.

This article describes the results of comparative quantitative and qualitative examinations of specimens obtained by testing 65 individuals by means of a cell aspirator and a wooden spatula. The studies were performed on a clinically normal mucosa as well as on different mucosal lesions. A statistical analysis of the cells obtained showed that the cell aspirator quantitatively produced significantly better results both with regard to the total number of cells obtained and to the number of epithelial cells in the different stages of maturity. The number of cells obtained turned out to be dependent on surface structure and the size of the lesion, however. Qualitatively the cell aspirator collected epithelial cells which were better preserved morphologically, but also a larger number of compact cell clusters. The number of erythrocytes was low. The structure of these blood cells was well preserved, indicating bleeding arising in connection with the taking of the specimens. The number of leucocytes was larger in the aspirated material. The degrees of fixation and staining were similar. The authors make recommendations for using the cell aspirator in such a manner as to obtain the best qualitative results.

Cytodiagnosis↗