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排序方式: 共有1675条查询结果,搜索用时 31 毫秒
101.
R W Lange B W Day R Lemus V A Tyurin V E Kagan M H Karol 《Chemical research in toxicology》1999,12(10):931-936
Diisocyanatotoluene (toluene diisocyanate, TDI), a 4:1 mixture of 2, 4- and 2,6-isomers used in the preparation of polyurethanes, causes occupational asthma by an as yet unknown mechanism. We previously showed that it forms adducts with the apical surface of the bronchoepithelium in vivo, and with ciliary microtubules in cultured human bronchoepithelial (HBE) cells. These results suggested that TDI may not enter HBE cells. In vitro studies, however, showed that TDI avidly forms bis adducts with glutathione (GSH) and that these adducts transfer monoisocyanato-monoglutathionyl-TDI to a sulfhydryl-containing peptide. This study sought to elucidate intracellular reactions of TDI. Using an electron paramagnetic resonance spectrometric (EPR) method, we established that the level of thiol-dependent quenching of phenoxyl radicals of etoposide was decreased >40% in pulmonary tissue of mice that received TDI intrabronchially. Similarly, HBE cells exposed to 100 ppb TDI vapor experienced a >30% reduction in thiol levels as determined with a thiol-specific fluorescent probe (ThioGlo 1). HPLC/UV analysis of lysates from HBE cells exposed to 200 and 500 ppb TDI vapor suggested a dose-related formation of S-glutathionyl adducts. Data from the 500 ppb TDI-treated HBE cells verified the identity of the 2-monoglutathionyl-4-monoisocyanato adduct. The results provide firm evidence that TDI enters pulmonary cells and reacts with GSH. This rapid reaction leading to formation of S-glutathionyl adducts of TDI suggests the importance of cellular thiols in TDI-induced pulmonary disease. 相似文献
102.
Spitz MR Strom SS Yamamura Y Troncoso P Babaian RJ Scardino PT Wheeler T Amos CI von Eschenbach A Kagan J 《International journal of cancer. Journal international du cancer》2000,89(3):259-264
While tumor volume and Gleason scores are the best available prognostic indicators for prostate cancer, contemporary predictive methods are unable to identify which men with Gleason scores of 7 have clinically insignificant tumors that will not progress and which men will develop highly aggressive prostate cancer. Our objective was to evaluate potential environmental determinants of significant prostate cancer. Subjects were patients identified from a university-based hospital and tertiary cancer center who had undergone radical prostatectomy for prostate cancer. Cases were 103 patients whose tumor volumes were =0.5 ml. The comparison group was comprised of 225 men with larger-volume disease or with histologic evidence of extracapsular extension but without lymph node involvement. The matching criteria were ethnicity, age at diagnosis (+/-5 years), and date of diagnosis (+/-1 year). Epidemiologic data, current weight, and height were obtained. The comparison group was significantly more likely than cases to be current smokers (7.6% vs. 3.9%) and to report more pack-years smoked (30.1 vs. 23.0 years, p = 0.06). Cases tended to weigh less (85.2 vs. 87.1 kg, p = 0.1) and have lower body mass indices (26.8 vs. 27.6, p = 0.07). A similar trend was evident for weight at age 40 (79 vs. 81 kg). Cases reported a mean weight gain of 4.9 kg compared with 6. 6 kg in the comparison subjects (p = 0.05) between the ages of 25 and 40. There was no significant difference in weight gain from age 40 to current age. Cases were more likely to report having prostate cancer screening (90% vs. 80%, p = 0.02). Cases with Gleason scores =7 (3 + 4, with 3 being the dominant grade) were younger at diagnosis than those with scores of 7 (4 + 3, with 4 being the dominant grade), were more likely (93%) to have had prostate screening, were less likely to be current smokers (4%), reported the fewest pack-years smoked (21.5 vs. 28.6 years for high-score cases and 30.1 for comparison subjects), and had the lowest average weight gain from ages 25 to 40 (4.62 vs. 6.31 kg for high-score cases). Weight gain in early adulthood and smoking thus appear to be important predictors of virulent prostate cancer. Our data also suggest that prior screening is associated with diagnosis of lower-volume and lower-score disease. 相似文献
103.
104.
Nano‐sized materials and nano‐scaled processes are widely used in many industries. They are being actively introduced as diagnostic and therapeutic in biomedicine and they are found in numerous consumer products. The small size of nanoparticles, comparable with molecular machinery of cells, may affect normal physiological functions of cells and cause cytotoxicity. Their toxic potential cannot be extrapolated from studies of larger particles due to unique physicochemical properties of nanomaterials. Therefore, the use of nanomaterials may pose unknown risks to human health and the environment. This review discusses several important issues relevant to pulmonary toxicity of nanoparticles, especially single‐walled carbon nanotubes (SWCNT), their direct cytotoxic effects, their ability to cause an inflammatory response, and induce oxidative stress upon pharyngeal aspiration or inhalation. Further, recognition and engulfment of nanotubes by macrophages as they relate to phagocytosis and bio‐distribution of nanotubes in tissues and circulation are discussed. The immunosuppressive effects of CNT and their significance in increased sensitivity of exposed individuals to microbial infections are summarized. Finally, data on biodegradation of SWCNT by oxidative enzymes of inflammatory cells are presented in lieu of their persistence and distribution in the body. 相似文献
105.
106.
Mass spectrometric analysis of tobacco-specific nitrosamine-DNA adducts in smokers and nonsmokers 总被引:4,自引:0,他引:4
P G Foiles S A Akerkar S G Carmella M Kagan G D Stoner J H Resau S S Hecht 《Chemical research in toxicology》1991,4(3):364-368
A gas chromatography, negative ion chemical ionization mass spectrometry (GC-NICI-MS) based assay for tobacco-specific nitrosamine adducts of DNA is described. The assay is based on the observation that acid hydrolysis of DNA from animals treated with tobacco-specific nitrosamines releases 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB). HPB and the internal standard [4,4-D2]HPB are derivatized with pentafluorobenzoyl chloride and the resulting HPB-pentafluorobenzoate is purified by high-performance liquid chromatography prior to GC-NICI-MS analysis. DNA from human peripheral lung and tracheobronchial tissue, collected at autopsy, was analyzed for acid-released HPB. The mean HPB level (fmol/mg of DNA) for peripheral lung DNA was 11 +/- 16 (SD, n = 9) for smokers and 0.9 +/- 2.3 (n = 8) for nonsmokers. Mean adduct levels in tracheobronchus were 16 +/- 18 (n = 4) for smokers and 0.9 +/- 1.7 (n = 4) for nonsmokers. These are the first measurements of tobacco-specific nitrosamine-DNA adducts in humans. Further studies comparing the levels of DNA and globin adducts will provide a better understanding of the metabolic activation of tobacco-specific nitrosamines in humans and may provide a more accurate indication of an individual's risk of developing tobacco-related cancer. 相似文献
107.
108.
S D Rockoff E Kagan A Schwartz D Kriebel W Hix P Rohatgi 《Journal of thoracic imaging》1987,2(4):58-66
We evaluated fissural (ie, visceral pleural) thickening on radiographs in two asbestos-exposed study populations and a control group. Asbestos workers had an incidence of fissural thickening of 54.5% compared with 16.0% in the unexposed control group, with a strong positive statistical effect due to asbestos exposure beyond that attributable to age. Fissural thickening occurred in 85% of workers with parietal plaques and in 36% without pleural plaques. Fissural thickening occurred in 45% without radiographic evidence of pulmonary fibrosis, but it was very common (85%) in those with pulmonary fibrosis. Data analysis showed that fissural thickening responds more strongly to asbestos exposure than does plaque formation, with 21 years of asbestos exposure needed for a 50% chance of developing fissural thickening, while 31 years of exposure were needed for a 50% chance of forming pleural plaques. From a second group of 57 asbestos workers evaluated clinically, 8 were diagnosed as having asbestosis with radiographically clear lungs and fissural thickening. We conclude that visceral pleural thickening is common in asbestos exposure, that it is related to the years since first asbestos exposure, and that its presence may indicate the presence of pulmonary asbestosis, even with radiographically normal lungs. 相似文献
109.
Kagan Tun Erkan Kaptanoglu Berker Cemil S. Tuna Karahan Ali Fırat Esmer Alaiddin Elhan 《European spine journal》2008,17(6):853-856
An anatomical study for evaluation of anterior C1–C2. To provide essential anatomic data for safer transoral odontoidectomy.
The surface dimensions of the atlas vertebra and the transoral approach for odontoidectomy have been described in detail.
Anterior arcus of C1 must be drilled out to reach odontoid process for transoral odontoidectomy. The thickness of anterior
ring of C1 has not been studied before. Sixty, dried adult atlas and 60 axis vertebrae and ten cadaveric craniocervical specimens
were measured for the following: (1) bony drilling depth (BDD), the distance from the anterior wall of anterior ring of C1
to anterior wall of odontoid; (2) minimum drilling diameter (MDD), distance of minimum C1 anterior ring removal for odontoid
resection on horizontal plane; (3) maximum bony drilling diameter (MBDD), distance of maximum C1 anterior ring removal for
odontoid resection on horizontal plane. Lateral border of this diameter is limited by medial borders of the lateral mass;
(4) the widest odontoid diameters (WOD) on coronal sections were measured. On 60 atlas and axis vertebrae, the BDD was 7.0 ± 1.2 mm
on dry bones, the distance between the medial borders of the lateral mass (MBDD) was 16.1 ± 1.5 mm, and the WOD on coronal
sections (WOD) was 9.8 ± 0.8 mm. On cadavers, the distance between the two edges of C1 anterior ring removal for odontoid
resection (MDD) was 10.8 ± 1.1 mm and the WOD on coronal sections (WOD) was 10.1 ± 1.4 mm. An odontoid surgery through transoral
approach is safe and feasible. A quantitative understanding of the anterior anatomy of C-1 and C-2 is necessary when considering
transoral odontoid resection. In this study the authors define safe zones for anterior atlas and axis. 相似文献
110.