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ABSTRACT: Urinary benzene (UB) was investigated as a biomarker of exposure among benzene-exposed workers and unexposed subjects in Shanghai, China. Measurements were performed via headspace solid phase microextraction of 0.5 ml of urine specimens followed by gas chromatography-mass spectrometry. This assay is simple and more sensitive than other methods (detection limit 0.016 microg benzene/l urine). The median daily benzene exposure was 31 p.p.m. (range 1.65-329 p.p.m.). When subjects were divided into controls (n = 41), those exposed to < or =31 p.p.m. benzene (n = 22) and >31 p.p.m. benzene (n = 20), the median UB levels were 0.069, 4.95 and 46.1 microg/l, respectively (Spearman r = 0.879, P < 0.0001). A linear relationship was observed between the logarithm of UB and the logarithm of benzene exposure in exposed subjects according to the following equation: ln(UB, microg/l) = 0.196 + 0.709 ln (exposure, p.p.m.) (r = 0.717, P < 0.0001). Considering all subjects, linear relationships were also observed between the logarithm of UB and the corresponding logarithms of four urinary metabolites of benzene, namely t,t-muconic acid (r = 0.938, P < 0.0001), phenol (r = 0.826, P < 0.0001), catechol (r = 0.812, P < 0.0001) and hydroquinone (r = 0.898, P: < 0.0001). Ratios of individual metabolite levels to total metabolites versus UB provide evidence of competitive inhibition of CYP450 enzymes leading to increased production of phenol and catechol at the expense of hydroquinone and muconic acid. Among control subjects UB was readily detected with a mean level of 0.145 microg/l (range 0.027-2.06 microg/l), compared with 5.63 microg/l (range 0.837-26.38 microg/l) in workers exposed to benzene below 10 p.p.m. (P < 0.0001). This suggests that UB is a good biomarker for exposure to low levels of benzene.
Carcinogenesis 02/2001; 22(2):279-86. · 5.70 Impact Factor
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L Zhang,
N Rothman,
Y Wang,
R B Hayes, W Bechtold,
P Venkatesh,
S Yin,
M Dosemeci,
G Li,
W Lu,
M T Smith
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ABSTRACT: Fluorescence in situ hybridization (FISH) is a powerful new technique that allows numerical chromosome aberrations (aneuploidy) to be detected in interphase cells. In previous studies, FISH has been used to demonstrate that the benzene metabolites hydroquinone and 1,2,4-benzenetriol induce aneuploidy of chromosomes 7 and 9 in cultures of human cells. In the present study, we used an interphase FISH procedure to perform cytogenetic analyses on the blood cells of 43 workers exposed to benzene (median = 31 ppm, 8-hr time-weighted average) and 44 matched controls from Shanghai, China. High benzene exposure (> 31 ppm, n = 22) increased the hyperdiploid frequency of chromosome 9 (p < 0.01), but lower exposure (< or = 31 ppm, n = 21) did not. Trisomy 9 was the major form of benzene-induced hyperdiploidy. The level of hyperploidy in exposed workers correlated with their urinary phenol level (r = 0.58, p < 0.0001), a measure of internal benzene dose. A significant correlation was also found between hyperdiploidy and decreased absolute lymphocyte count, an indicator of benzene hematotoxicity, in the exposed group (r = -0.44, p = 0.003) but not in controls (r = -0.09, p = 0.58). These results show that high benzene exposure induces aneuploidy of chromosome 9 in nondiseased individuals, with trisomy being the most prevalent form. They further highlight the usefulness of interphase cytogenetics and FISH for the rapid and sensitive detection of aneuploidy in exposed human populations.
Environmental Health Perspectives 12/1996; 104 Suppl 6:1325-9. · 7.04 Impact Factor
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ABSTRACT: Recognition and treatment of craniofacial deformities require an understanding of complex skeletal structures in three planes of space. Traditional imaging techniques rely on biplanar radiographs which provide only two-dimensional data. The introduction of three-dimensional image display (3DIR) has provided a method of object analysis in three planes of space, obviating the need for mental reconstruction, and yielding more spatial information than was previously available. This study was undertaken to investigate the quantitative value of three-dimensional images compared with cephalometric techniques in assessing a craniofacial deformity. Metallic marker references were placed on a deformed skull. Measurements taken from cephalograms and three-dimensional images were compared with corresponding digitized and manual measurements taken from the skull. Three-dimensional image reformation provided a more accurate representation of the deformity than the cephalometric methods. Because all structural relationships are preserved in the CT data matrix, measurements are inherently accurate and reproducible. 3DIR offers dynamic advantages over cephalometric methods because data can be manipulated interactively. Further investigation is needed to study the importance of head position and to develop patient selection criteria, scan protocols, and surgical treatment planning algorithms.
Journal of Oral and Maxillofacial Surgery 11/1989; 47(10):1053-61. · 1.64 Impact Factor
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Journal of clinical orthodontics: JCO 08/1987; 21(7):470-3.
