No abstract

Previous studies from this laboratory have focused on the characterization of blood protein adducts formed in utero as a result of maternal smoking during pregnancy. These biological samples, obtained during the third trimester of pregnancy, at delivery, have clearly shown a correlation between maternal smoking histories and exposure of the fetus to tobacco smoke carcinogens, including 4-aminobiphenyl and benzo(a)pyrene. In the present study, we examined exposure of the fetus during the first trimester of pregnancy to various environmental carcinogens, particularly those found in tobacco smoke. Amniotic fluid samples were obtained from women undergoing routine amniocentesis between 16 and 20 weeks gestational age. Amniotic fluid, produced by the fetal lungs and kidneys, is an important part of pregnancy and fetal development and this fluid surrounds the fetus throughout pregnancy. In these studies, samples of amniotic fluid were obtained from nonsmokers as well as 0.5 pack per day smokers, 1.0 pack per day smokers, and greater than 2.0 pack per day smokers. Maternal smoking status was determined by questionnaire as well as assessment of amniotic fluid for 39 Downloaded by [University of Kent] at 15:01 07 December 2014 40 S. R. Myers et al. cotinine via immunoassay. Amniotic fluid samples were extracted and analyzed for the presence of polycyclic aromatic hydrocarbons (PAHs). A clear correlation was found between levels of maternal smoking and PAHs in the amniotic fluid.Amniotic fluid 1-hydroxypyrene levels ranged from 1.54 ± 0.12 µg/L in nonsmokers to 11.72 ± 0.67 µg/L in women smoking greater than 2 pks/da, indicating approximately a 10X increase over nonsmokers. Similar results were found 3-hydroxybenzo(a)pyrene, 6-hydroxybenzo(a)pyrene, and 3,6-dihydroxybenzo(a)pyrene, metabolites of the carcinogen benzo(a)pyrene as well as with the 9-hydroxy and 9,10-dihydroxy metabolites of anthracene. The 5-hydroxymethyl metabolite of 5-methylchrysene was found to range in concentrations from 1.65 ± 0.11 µg/L in nonsmokers to 12.67 ± 0.79 µg/L in greater than 2 packs per day smokers.These results demonstrate that amniotic fluid can serve as a biological marker of exposure to tobacco related polycyclic aromatic hydrocarbons. Identification of potentially harmful compounds detected at an early stage of pregnancy may prevent subsequent exposures to the fetus and as a result decrease the risk of potential genotoxic as well as teratogenic events.

Biological markers for assessment of exposure to a variety of environmental carcinogens has been widely applied in both basic as well as clinical research. Exposure to tobacco smoke presents an ideal environment with which to develop, characterize, and refine biological markers, especially of those carcinogens found in tobacco. In the present study, a sensitive gas chromatography/mass spectrometry (GC/MS) method was developed to measure nitrosamine- hemoglobin adducts (HPB-Hb (4-Hydroxy-3-pyridinyl-1-butanone) at trace levels in red blood cells of both African-American and Caucasian smoking and nonsmoking mothers and their infants. Gas chromatographic and mass spectrometric methods with chemical ionization (CI) of methane reagent gas in both positive and negative ion mode as well as electron ionization (EI) were studied to determine differences in sensitivity of detection among the various ionization methods. Detection limits using both positive and negative chemical ionization modes were found to be 30 femtomoles of HPB, whereas detection using electron impact modes yielded a detection limit of 80 femtomoles of HBP. Comparative derivatization of HPB was performed using O-bis(Trimethylsilyl)-trifluoroacetamide (BSTFA) and 2, 3, 4, 5, 6-Pentafluorobenzoylchloride (PFBC). Both Negative CI and Positive CI modes of analysis were compared to the more widely accepted EI modes of mass spectrometric analysis.

English as a language is an essential tool in the negotiation of power and relationship at the interpersonal, social and the global level as well. The importance of learning English has increased significantly as a useful communication tool in the age of globalization. In the existing scenario, English language learning and teaching in the rural areas of Bangladesh has become a prime concern. This study aims to present the current English language education policy, language learning and teaching obstacles pertaining to the poorly equipped classroom, lack of trained language teachers, and inadequate use of technology and non-availability of learning materials in Bangladesh. To analyze and to find the solution to the language teaching and learning obstacles, the researcher employed both qualitative and quantitative methods. The research was carried out in ten rural colleges far from the capital city Dhaka. The population of this study was higher secondary level students in the academic year 2019-2020. The number of populations was 25 students from intermediate class and 10 teachers from same school and colleges, and data were collected through a questionnaire. The findings show that though CLT based English language curriculum has been operating at the higher secondary level in Bangladesh, most of the teachers are not familiar with CLT guidelines and CLT related activities. Besides this, there are some crucial factors which demand great attention to change the current scenario. As a result, there are inconsistencies between the stated objectives of Teaching English and the actual teaching techniques.