Measurement of nicotine in hair by reversed-phase high-performance liquid chromatography with electrochemical detection

We have developed an assay for nicotine in hair based on reversed-phase HPLC with electrochemical detection. The method uses a low-metal, high-purity silica reversed-phase column. We have investigated the washing, digestion and extraction procedures and discuss the important points in the HPLC method development. The assay is presented as an application in a population of exposed and non-exposed children. Analytical parameters are satisfactory with linearity, recoveries, limit of quantitation and precision all suitable for epidemiological studies involving environmental tobacco smoke exposure assessment.     

Met-Independent Hepatocyte Growth Factor-mediated regulation of cell adhesion in human prostate cancer cells

Background  

Prostate cancer cells communicate reciprocally with the stromal cells surrounding them, inside the prostate, and after metastasis, within the bone. Each tissue secretes factors for interpretation by the other. One stromally-derived factor, Hepatocyte Growth Factor (HGF), was found twenty years ago to regulate invasion and growth of carcinoma cells. Working with the LNCaP prostate cancer progression model, we found that these cells could respond to HGF stimulation, even in the absence of Met, the only known HGF receptor. The new HGF binding partner we find on the cell surface may help to clarify conflicts in the past literature about Met expression and HGF response in cancer cells.     

Snoring as a risk factor for type II diabetes mellitus: a prospective study

To examine the association between snoring and risk of developing type II diabetes mellitus, the authors analyzed data from the Nurses' Health Study cohort. This analysis included 69,852 US female nurses aged 40-65 years without diagnosed diabetes, cardiovascular disease, or cancer at baseline in 1986. Snoring patterns were ascertained by questionnaire. During 10 years of follow-up, 1,957 women were diagnosed with type II diabetes. In analyses adjusted for age and body mass index, snoring was associated with risk of diabetes (for occasional snoring vs. nonsnoring, relative risk (RR) = 1.48 (95% confidence interval (CI): 1.29, 1.70); for regular snoring vs. nonsnoring, RR = 2.25 (95% CI: 1.91, 2.66); p for trend < 0.0001). Further adjustment for other diabetes risk factors and sleeping-related covariates only slightly attenuated the risk (for occasional snoring, RR = 1.41 (95% CI: 1.22, 1.63); for regular snoring, RR = 2.03 (95% CI: 1.71, 2.40); p for trend < 0.0001). Analyses stratified by body mass index, smoking history, or parental history of diabetes showed a consistent association between snoring and diabetes within the categories of these variables. These results suggest that snoring is independently associated with elevated risk of type II diabetes.     

Measurement of tobacco smoke exposure: comparison of toenail nicotine biomarkers and self-reports.

BACKGROUND: Accurate measurement tools of exposure for use in large epidemiologic studies are lacking. Biomarkers of tobacco exposure provide additional advantages to self-reports and there is a need to further develop and validate them. The objective is to compare toenail nicotine levels, a novel biomarker of tobacco exposure, with self-reports of tobacco exposure from a large cohort study. METHODS: In this cross-sectional analysis, toenail samples were collected from 2,485 women participating in the Nurses' Health Study in 1982. Detailed self-reports of smoking habits and reported exposure to secondhand smoke (SHS) were collected from these women near the time of toenail collection. The toenail samples were analyzed by a high-performance liquid chromatography method for measuring nicotine. RESULTS: The 5 to 95 percentile range of toenail nicotine was from 0.06 to 4.06 ng/mg toenail and the median level was 0.21 ng/mg. There was a significant difference in toenail nicotine levels according to reported smoking status (the median level for nonsmokers with no SHS was 0.10 ng/mg, the median level for nonsmokers with SHS was 0.14 ng/mg, and the median level for active smokers was 1.77 ng/mg). However there was considerable overlap in nicotine levels according to reported smoking status. Toenail nicotine level was strongly associated with reported smoking level (Spearman r = 0.63), but there was no complete concordance, suggesting that the two methods are measuring different aspects of the same exposure. CONCLUSION: Our findings show that toenail nicotine levels capture the overall burden of tobacco smoke exposure and provide additional information on exposure not captured by reported history.     

Sjögren's syndrome sufferers have increased oral yeast levels despite regular dental care

Aim:  To investigate the prevalence and quantity of oral yeasts and their association with oral candidiasis in Sjögren's syndrome (SS) patients receiving regular dental care.
Materials and methods:  Yeasts in oral rinse and full-mouth supra-gingival plaque samples from 25 primary SS, 27 secondary SS and 29 control subjects were selectively cultured. All yeasts except single-species isolates were genotyped using pulsed field gel electrophoresis (PFGE).
Results:  Ten (19%) SS sufferers had symptomless candidiasis. SS subjects had a higher prevalence (73% vs 7%) and quantity of yeasts than controls in both oral rinse and plaque samples ( P  < 0.05). The prevalence of yeasts in plaque was associated with candidiasis regardless of denture wearing ( P  ≤ 0.04). Candida albicans was the predominant yeast isolated. PFGE showed 20 (66% of total) C. albicans isolate pairs, i.e. C. albicans species isolated from plaque and oral rinse samples of the same individual, were of closely related genetic clonal types ( P  < 0.01).
Conclusions:  Despite effective oral hygiene, more SS subjects than controls had detectable levels of oral yeasts and their presence in supra-gingival plaque was associated with candidiasis. Candida albicans colonized supra-gingival biofilm even in well-maintained SS individuals, posing a challenge to the control of oral candidiasis.     

Toenail nicotine level as a novel biomarker for lung cancer risk

The objective of this US study was to assess the association of toenail nicotine level as a novel biomarker with lung cancer risk independent of reported smoking history. A nested case-control study of 210 male lung cancer cases and 630 matched controls aged 40-75 years participating in the Health Professionals Follow-up Study was conducted. Toenail samples collected in 1987 were analyzed for nicotine levels, and incident lung cancer cases were diagnosed between 1988 and 2000. Mean toenail nicotine level among cases was 0.95 ng/mg compared with 0.25 ng/mg among controls (P < 0.0001). In univariate analyses, the relative risk of lung cancer for the highest versus lowest quintiles of toenail nicotine level was 10.50 (95% confidence interval: 5.61, 19.64; P for trend < 0.0001). When the authors adjusted for pack-years from reported smoking history in multivariate analyses, the relative risk for toenail nicotine levels in the highest quintile was still significant in predicting lung cancer risk: 3.57 (95% confidence interval: 1.73, 7.37; P for trend < 0.0001). In conclusion, the toenail nicotine biomarker was found to be a strong predictor of lung cancer independent of smoking history, suggesting that the adverse effects of cigarette smoke may be underestimated in studies based on smoking history only.     

Intracellular signaling mechanisms regulating the activation of human?eosinophils by the novel Th2 cytokine IL-33: implications for allergic?inflammation

The novel interleukin (IL)-1 family cytokine IL-33 has been shown to activate T helper 2 (Th2) lymphocytes, mast cells and basophils to produce an array of proinflammatory cytokines, as well as to mediate blood eosinophilia, IgE secretion and hypertrophy of airway epithelium in mice. In the present study, we characterized the activation of human eosinophils by IL-33, and investigated the underlying intracellular signaling mechanisms. IL-33 markedly enhanced eosinophil survival and upregulated cell surface expression of the adhesion molecule intercellular adhesion molecule (ICAM)-1 on eosinophils, but it suppressed that of ICAM-3 and L-selectin. In addition, IL-33 mediates significant release of the proinflammatory cytokine IL-6 and the chemokines CXCL8 and CCL2. We found that IL-33-mediated enhancement of survival, induction of adhesion molecules, and release of cytokines and chemokines were differentially regulated by activation of the nuclear factor (NF)-κB, p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) pathways. Furthermore, we compared the above IL-33 activities with two structurally and functionally related cytokines, IL-1β and IL-18. IL-1β, but not IL-18, markedly upregulated cell surface expression of ICAM-1. IL-1β and IL-18 also significantly enhanced eosinophil survival, and induced the release of IL-6 and chemokines CXCL8 and CCL2 via the activation of the NF-κB, p38 MAPK and ERK pathways. Synergistic effects on the release of IL-6 were also observed in combined treatment with IL-1β, IL-18 and IL-33. Taken together, our findings provide insight into IL-33-mediated activation of eosinophils via differential intracellular signaling cascades in the immunopathogenesis of allergic inflammation.     

胶质瘤干细胞对替莫唑胺敏感性的研究

目的 探讨胶质瘤干细胞(GSC)对替莫唑胺(TMZ)的敏感性及耐药机制.方法 新鲜多形性胶质母细胞瘤(GBM)标本培养后获得GSC.免疫荧光技术榆测未分化GSC的CD133及分化生长GSC的GFAP的表达,MTS法检测对替莫唑胺的敏感性,流式细胞技术对CD133阳性细胞的比例进行定量,荧光标记的甲基化特异性PCR分析MGMT启动子区域的甲基化状态,Western blot检测抑癌基因PTEN的表达.结果 (1)5例GBM标本中成功获得GSC,符合肿瘤下细胞定义.(2)5个GSC细胞株多数对TMZ不敏感.其中,T509的半数抑制浓度(IC50)为22.3 μmol/L(敏感),T411的IC50为286.3 μmol/L(中度敏感),其余3个细胞株T402,T405及T509的IC50皆大于1000μmol/L(不敏感).(3)CD133阳性细胞比例大于10%的GSC细胞株对TMZ不敏感.(4)MGMT启动子区域呈去甲基化状态的GSC对TMZ不敏感或仅为中度敏感.(5)5个GSC细胞株中,PTEN表达水平差异大,与GSC对TMZ的敏感性无明显关联.结论 GSC对TMZ普遍耐药,与MGMT启动子区域甲基化状态及CD133阳性细胞有关,而与PTEN蛋白表达水平无明显关联.