Browsing by Subject "Toxicology"
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Item A Study of Pesticide Safety and Health Perceptions Among Tarrant County Pesticide Applicators(2001-05-01) Martinez, Robert A.; Terrance B. Gratton; Claudia S. Coggin; Sam AtkinsonPesticides have become an important part of our lives. We rely on them to help protect our crops from pest; they rid our homes of unwanted pests and help us make our lawns and public parks beautiful. Pesticides are also important to public health. They are a major source of vector control and help stop the spread of vector-borne disease. Even though we used them in our everyday lives, it is important to remember that pesticides are poisons, and that great care must be taken to ensure the safety of the public and safety of those who work with pesticides. This study looked at the safety knowledge and health perceptions among Tarrant County, Texas licensed applicators. Much research has been focused on the effects of pesticides on human health. Much of this research has been focus on the farmer applicator (Alavanja, 1999). This study focuses on applicators that work mostly in the urban areas of the County, as well as ranchers live in the County. These licensed urban applicators included those who work for city parks departments, golf courses, commercial applicators, lawn care service, pest control and some private ranchers. The Texas Pesticide Regulations require that a person may not use a restricted-use or state-limited use pesticides or herbicides unless licensed by the Texas Department of Agriculture (2000). Therefore the purpose of this study is to see if an association between health beliefs and pesticide safety knowledge exist. The reason it is important is because these people can have either a positive or negative impact on the safety of themselves and their crews. Acute pesticide poisoning is one of the biggest risks that applicators face. The state of Texas conducts an active surveillance of occupational-related pesticide poisonings. The Environmental Epidemiology and Toxicology Division at the Texas Department of Health (TDH) have had this system in place since 1985. TDH reported that 107 work related cases occurred during 1998, with 55 confirmed as occupational pesticide poisoning (1998). The most frequent symptoms reported were neuromuscular symptoms such as headaches, dizziness, confusion, irritability, and twitching muscles. Pyrethroids and pyrethins were the most commonly reported class of pesticides exposure (51%) followed by Organophosphates (25%), which are the most widely used form of insecticides, as well as herbicides and fungicides. Pesticide safety and the TDH surveillance system are two very important ways of informing pesticide applicators about the risk and what can be done to minimize that risk to themselves and their crew.Item Association Between Air Pollution and Daily Mortality in Two Texas Counties(2005-05-01) Espinosa, Isabel Y.; Terry Gratton; Sejong Bae; Antonio ReneEspinosa, Isabel Y., Association of Air Pollution and Daily Mortality in Two Texas Counties. Master of Public Health (Environmental Health), May 2005, 36 pp., 11 tables, 2 illustrations, references, 36 titles. The purpose of this study was to investigate the association between ozone and specific daily mortality in two United States counties, Bexar and Tarrant County, Texas. Daily specific mortality, one hour ozone levels, average temperatures, and Air Quality Index values were obtained for both counties. The results from this study suggest that no association is present between air pollution and specific daily mortality in Bexar County. Further statistical analysis is needed to determine if an association is present in Tarrant County as factors inherent in the collected data could be affecting the results. Investigating the association between ozone levels and hospitalization rates may provide a better description of the relationship and should be considered as a future study.Item Association of Leukemia and Other Selected Diseases with Occupational Exposure to Welding(2003-05-01) Mendoza, Hilda OraliaMENDOZA, HILDA ORALIA. ASSOCIATION OF LEUKEMIA AND OTHER SELECTED DISEASES WITH OCCUPATIONAL EXPOSURE TO WELDING. Master of Public Health (Epidemiology). May, 2003. Exposure to carcinogens is an established risk factor for cancer development. Welders are chronically exposed to cardinogens. In this study, the relationship between occupational exposure to welding and mortality from leukemia, lymphoma, Hodgkin’s disease, melanoma, lung cancer, or myocardial infarcation was examined. Files from ORISEWDS, Comprehensive Epidemiologic Data Resource, U.S. Department of Energy were utilized to develop a working file including 416,686 records from employees of one or more Oak Ridge, nuclear plant facilities. Neither welding exposure length, radiation exposure, nor smoking were included in this study. Results show higher adjusted ratios (OR) for leukemia, lymphoma, and Hodgkin’s disease for employees occupationally exposed to welding as compared to employees on-occupationally exposed to welding. OR’s for lung cancer and myocardial infarction were also higher for welders than non-welders.Item Cellular and Molecular Mechanisms that Distinguish the Effects of Progestorone and Medroxyprogesterone Acetate on Neuroprotection(2006-07-28) Kaur, Paramjit; Goldfarb, Ronald; Singh, Meharvan; Agarwal, NeerajKaur, Paramjit. Cellular and Molecular Mechanisms That Distinguish the Effects of Progesterone and Medroxyprogesterone Acetate on Neuroprotection., Doctor of Philosophy, (Pharmacology and Neuroscience), July, 2006, 203 pp., 5 illustrations, 20 figures and bibliography. Women have a higher prevalence for Alzheimer’s disease (AD) than men, suggesting that the precipitous decline in gonadal hormone levels following the menopause may contribute to the risk of developing AD. However, principal results from the Women’s Health Initiative concluded that women taking conjugated equine estrogens combined with medroxyprogesterone acetate (MPA, tradename: Prempro) incurred more harmful than beneficial outcomes versus the placebo group (Rossouw et al., 2002). This dissertation was aimed at determining if the discrepancy between basic science reports and these clinical studies could have been due to the synthetic progestin, MPA. I hypothesized that P4 and MPA differed in their ability to protect against the excitotoxic/oxidative insult, glutamate. Further, I proposed that this difference in neuroprotective potential would be reflected in the difference in the ability of these hormones to elicit key effectors of two neuroprotection-associated signaling pathways, the ERK/MAPK and P13-Kinase pathways. Finally, studies were initiated to evaluate the potential importance of BDNF (brain-derived neurotrophic factor) in mediating the protective effects of P4. I used organotypic explants of the cerebral cortex, and found that both P4 and MPA elicit the phosphorylation of ERK and Akt, two signaling pathways implicated in neuroprotection, with maximal phosphorylation occurring at a concentration of 100 nM. Interestingly, P4 protected against glutamate- induced toxicity however, while an equimolar concentration of MPA (100nM) did not. Further, P4 resulted in an increase in BDNF, while MPA did not. Our data bring into question the relevance of using MPA as a component of hormone therapies in postmenopausal women, and instead, argue that the relevant progestin for use in treating brain-related disorders is progesterone. Collectively, the data presented here suggest that P4 is protective via multiple, and potentially related mechanism, and importantly, its neurobiology is different from the clinically used progestin, MPA.Item Characterization of Protein Kinase C in Cisplatin Sensitive and Resistant Human Cervical Cancer HeLa Cells(2000-12-01) Mohanty, Sanghamitra; Basu, Alakananda; Simecka, Jerry; Dimitrijevich, DanMohanty, S., Characterization of protein kinase C in cisplatin sensitive and resistant human cervical cancer HeLa cells. Master of Science (Microbiology and Immunology), December, 2000. 37 pp., 11 illustrations, bibliography, 27 titles. Signal transduction plays a crucial role in carcinogenesis. A defect in signaling, by evading cell death or promoting cell proliferation, may result in neoplastic transformation or protection of cells from the cytotoxicity of anticancer drugs. Therefore, in order to understand the complex mechanism of drug resistance, it is relevant to probe into the important signal transduction pathways. Protein kinase C, a key signal transducer, influences cisplatin sensitivity in many cell lines. We examined whether or not the PKC signal transduction pathway is affected during development of resistance to cisplatin by tumor cells. PKC activators increased cisplatin sensitivity in both parental and cisplatin-resistant cells. Western blot analysis showed a slight decrease in cPKCα and nPKCε, an evaluation in nPKCδ and no change in the abundance of PKCϚ in HeLa/CP cells compared to HeLa cells. Though TPA-induced translocation of PKC isoforms was identical in both cell lines, down regulation of PKCδ was defective in resistant cells. Therefore, a deregulation in PKCδ was associated with cisplatin resistance.Item EGCG and Its Role in Prostate Cancer Angiogenesis(2005-05-01) Thomas, Rusha; Porunelloor Mathew; Ming-Chi Wu; Dan DimitrijevichThomas, Rusha, EGCG and its role in prostate cancer angiogenesis. Master of Science (Biochemistry and Molecular Biology), May 2005, 47 pages, 14 illustrations, reference list, 44 titles. Hypoxia inducible factor-1 (HIF-1)-mediated upregulation of vascular endothelial growth factor (VEGF) has been implicated in angiogenesis associated with malignancies. HIF-1 consists of a constitutively expressed HIF-1β subunit, and a hypoxia-inducible HIF-1α subunit. Hypoxic induction of HIF-1α correlates with increased transcriptional activation of its downstream target genes, including VEGF. Epidemiologic and laboratory studies indicate that green tea has cancer preventive activity which has been attributed to its polyphenol components, the major one being epigallocatechin gallate (EGCG). This study investigated the effect of EGCG on normoxic VEGF expression in PC-3ML human prostate cancer cells. In contrast to previous studies where EGCG inhibited VEGF expression in breast and colon cancer cell lines, our results demonstrated that EGCG has the ability to upregulate HIF-1α transcription factor via inhibition of prolyl hydroxylation and subsequent von Hippel-Lindau protein interaction. HIF-1α upregulation by EGCG led to increased VEGF promoter activity and protein expression.Item Evaluation of Reconstituted High-Density Lipoprotein as a Drug Delivery System in Drug-Sensitive and Drug-Resistant Ovarian Cancer Cell Lines(2004-05-01) Buttreddy, Sabitha; Borejdo, Julian; McConathy, Walter J.; Nair, Maya P.The purpose of this study was to perform uptake and efflux studies of ORB in drug-sensitive (OV1063) and drug-resistant (SK-OV-3 and OVCAR-3) cells. Experiments were carried out by delivering ORB to the cells with and without rHDL to compare the amount of ORB taken up and expelled by the respective cells. Because serum contains lipoproteins, the experiments were also done in the absence of serum to show the specific effect of the rHDL vehicle. Because the efflux pumps responsible for multi-drug resistance are overexpressed and amplified in resistant cells, the efflux of ORB should be higher in these cells compared to the drug-sensitive cell line, OV1063. But, since our rHDL system is designed to reduce drug resistance by releasing the drug directly inside the cell bypassing the efflux pumps, the efflux of ORB should be less when it is delivered with rHDL.Item Fecal Coliforms in the Rio Grande: A Risk to Human Health(2004-12-01) Tompkins, Erin L.; Thomas Vaughan; Claudia S. CogginTompkins, Erin L., Fecal Coliforms in the Rio Grande: A Risk to Human Health. Master of Public Health (Environmental Health), December 2004, 45 pages, bibliography, 33 titles. The Rio Grande around Laredo, Texas/Nuevo Laredo, Mexico was designated for primary contact reaction by the EPA. However, monthly sampling over a ten-year period in this section of the river may show otherwise. Fecal contamination of the Rio Grande in this area may be a source of illness to the population. Four sites in Laredo area were tested for fecal coliform density and rate of flow. Rainfall data from the USGS was used for comparisons. The rate of flow of the Rio Grande had an impact on fecal coliform density at one site measured. Rainfall in Laredo had an impact on fecal coliform density at two measured sites, and was a significant predictor of density at these sites as well. A review of the designation for this river segment is recommended. More research is needed to determine the exposed population, and effects of high coliform densities on downstream communities.Item Gender Differences in Hemoglobin Level at the Onset of Symptoms of Cancer-Related Anemia(2003-12-01) Levar, Joshua M.; Victoria RudickLevar, Joshua M., Gender Differences in Hemoglobin Level at the Onset of Symptoms of Cancer-Related Anemia. Masters (Clinical Research Management), December, 2004, 39 pp., 2 tables, 5 illustrations, bibliography, 47 titles. The purpose of this study was to assess whether the previously demonstrated relationship between quality of life and anemia in cancer patients was influenced by gender. Two hundred and fifty one patients of various diagnoses completed the Functional Assessment of Cancer Therapy – Anemia (FACT-An) subscale to measure quality of life. Regression analysis revealed a significant positive correlation between hemoglobin and FACT-An subscale score, as well as a negative correlation between Eastern Cooperative Oncology Group (ECOG) performance status and FACT-An subscale score. Mean comparison demonstrated a significant difference in FACT-An score between patients currently and not currently receiving chemotherapy. An analysis of covariance, controlling for current therapy and ECOG performance status as confounders, found that men score more poorly on the FACT-An within the hemoglobin range of 10.-13.0 g/dL. In conclusion, the normalization of hemoglobin levels improves quality of life; however, gender differences should be taken into account when determining optimal hemoglobin levels.Item Legal Medicine and Toxicology(D. Appleton-Century Company Incorporated, 1937-01-01) Vance, Morgan; Helpern, Milton; Martland, Harrison; Gonzales, ThomasItem Lung Cancer Risk Among Workers in Poultry Slaughtering and Processing Plants: A Pilot Study(2008-05-01) Preacely, Nykiconia D.; Ramphal-Naley, Lilly; Cardarelli, Kathryn; Qualls-Hampton, RaquelPreacely, Nykiconia D., Lung Cancer Risk Among Workers in Poultry Slaughtering and Processing Plants: A Pilot Study. Doctor of Public Health (Epidemiology), May 2008, 104 pp., 21 tables, 4 figures, bibliography, 50 titles. Poultry workers are at a great risk of exposure to potentially harmful transmissible agents which can cause cancer in poultry; yet there are few epidemiological studies that examine the association of occupation and illnesses experienced by these workers. Workers in poultry slaughtering and processing plants are well suited to investigate the effects of exposure to poultry oncogenic agents because they have one of the highest human exposure to carcinogenic chemicals formed during the packaging and preparation of poultry. The preparations of poultry via smoking, and frying are additional exposures that release carcinogens which may be involved in lung cancer risk among poultry workers. Union records from several unions belonging to the United Food & Commercial Workers International Union for the years 1949-1989 were used to identify a cohort of workers once employed in poultry slaughtering and processing plants. The current research investigated whether certain occupational exposures were associated with lung cancer mortality among these workers. The research employed a case cohort design that provided individual level occupational and lifestyle data for workers who died with lung cancer between 1990 and 2003 compared to a sub-cohort of individuals randomly sampled from the entire cohort. It is anticipated that by identifying potentially harmful exposures in this industry, future research may focus on developing methods to alleviate them among poultry workers. The results of this study will provide public health professionals and the poultry industry with new information on the occupational exposures not previously explored in relation to lung cancer mortality among poultry slaughtering/processing plant workers.Item Medical Jurisprudence: Forensic Medicine and Toxicology(1906-01-01) Becker, Tracy; Witthaus, R.Item Risk of Hematopoietic Cancer Associated Mortality among Workers in the Poultry Slaughtering and Processing Industries(2015-05-01) Bangara, Saritha; Felini, Martha J.Objectives: Previous occupational cohort studies among poultry workers have revealed an excess risk of cancer-related mortality, including deaths due to hematopoietic malignancies. However, specific occupational and non-occupational exposures contributing to this excess risk have yet to be identified. Poultry workers are particularly at high risk since an average of 175,000 chickens are killed daily in poultry plants in the United States. This brings poultry workers into intimate contact with their blood, organs, and secretions, which may harbor transmissible oncogenic viruses. Moreover, they are exposed to potentially carcinogenic chemicals that are emitted during packaging and preparation. Hence, our study was conducted to provide preliminary evidence of which specific poultry related and non-poultry related occupational tasks increase the risk of mortality from hematopoietic cancer among poultry workers. Methods: A pilot case-cohort study was conducted using a combined cohort of 30,411 highly exposed poultry workers and 16,408 control subjects. Exposures pertaining to poultry and non-poultry related tasks were self-reported through telephone interviews from controls and next-of-kin for cases. Hematopoietic cancer mortality risk was assessed using logistic regression odds ratios (OR) and proportional hazard ratios (HR). Results: To assess possible differential recall between responses obtained directly from live study subjects and those from the next-of kin of deceased study subjects, the questionnaire was administered to a small subset of seven pairs of live control study subjects and their next-of-kin. Of the 245 direct responses obtained for dichotomous questions, there was an agreement of 80 % to 100% between the pairs for nearly 75% of the responses, with less than 60% agreement for only 8% of the responses. The highest risks for hematopoietic cancer mortality were among poultry workers in stockyards (OR=4.50, 95%CI=0.34-59.88), work as a poultry farmer (OR=2.67, 95%CI=0.78-9.23), working in non-commercial poultry farms (OR=2.53, 95%CI=0.85-7.52), handling of raw eggs in grocery stores (OR= 2.24, 95%CI=0.05-9.78), working in commercial poultry farms (OR=2.41, 95%CI=0.79-7.33), and spreading of chicken wastes (OR=2.00, 95%CI=0.58-6.89). Direct contact with poultry blood (OR=1.40, 95%CI=0.66-2.95) and killing chickens at work or outside of work (OR=1.35, 95%CI=0.26-7.14 and 1.63 (95%CI=0.72-3.65, respectively) were exposures that were also associated with an increased risk. Among non-poultry associated occupational exposures, working in a chemical plant (OR=6.92, 95%CI=0.56-85.23) and spraying insecticides (OR=3.03, 95%CI=0.78-11.83) incurred an increased risk. Work-related exposure to coal tar, naphthalene, or paraffin was associated with a significantly increased risk (OR=5.63, 95%CI=1.72-18.43). An elevated risk was also observed among subjects that worked at a gasoline station (OR=1.89, 95%CI=0.52-6.96). These exposures are known to be associated with increased exposures to PAHs and benzene. There was a statistically significant increased risk among those who sold seafood at work (OR=4.31, 95%CI=1.08-17.16) and among participants who worked on a commercial mixed farm (OR=3.15, 95%CI=1.20-9.92). Conclusion: This study provides preliminary evidence that exposure to poultry may be associated with increased mortality from hematopoietic cancer. A plausible explanation is that stockyard workers are regularly exposed to the bodily fluids of poultry, including blood and fecal matter, which may harbor oncogenic viruses that are transmissible to humans. The elevated risk estimates among workers exposed to gasoline as well as chemicals such as coal tar corroborate findings from previous studies that have established benzene and PAHs as risk factors for hematopoietic malignancies, respectively. While our findings support evidence from previous studies linking pesticide use and working on farms with mortality due to hematopoietic cancer, selling seafood was a unique risk factor that was discovered in our study, worthy of further investigation. Case-control studies nested within occupational cohorts of highly exposed subjects of sufficient statistical power may provide an efficient and valid method of investigating and confirming these findings.Item The Characterization of T Cell Responses Along the Respiratory Tract(2004-05-01) Ivey Jr., James A.; Brown, Mary B.; Fling, John; Wu, Ming-ChiIvey, James A., The Characterization of T Cell Responses Along the Respiratory Tract. Masters (Immunology). May, 2004. 63 pages. 2 tables, 10 figures. 55 titles. This research converged on T cell responses to respiratory agents, tobacco smoke and allergens in humans, and T cell responses to an extracellular bacterium, M. bovis, in calves. In the first chapter, we will discuss the basic functions of the immune system. In the second chapter, we will discuss the basic functions of the immune system. In the second chapter, we characterized the impact of tobacco smoke on T cell responses in atopic smokers and atopic nonsmokers. The results were inconclusive and the study was postponed until the proper allergens were found. We also characterized the T cell responses of calves infected with Mycoplasma bovis in the third chapter. The results showed an increase in T lymphocytes in the upper respiratory tract of infected calves, which correlated with sites of infection.Item The Involvement of D1 and D2 Dopamine Receptors in Cocaine Self-Administration(1996-06-01) Peltier, Rachel; Michael Forster; Patricia A. Gwirtz; Thomas YorioPeltier, Rachel L., The Involvement of D1 and D2 Dopamine Receptors in Cocaine Self-Administration. Doctor of Philosophy (Biomedical Sciences), June 1996, 195 pp. introduction, 6 chapters, discussion, bibliography, 91 titles. D1 and D2 dopamine receptor subtypes have been implicated in producing the reinforcing properties of cocaine. Chronic exposure to cocaine produces tolerance to its reinforcing effects in rats trained to self-administer cocaine. The time between cocaine reinforcers (ISRT) is directly related to dose. A three-point dose-response curve (0.125, 0.25 and 0.5 mg/inj) for cocaine self-administration is obtained during a single test session, allowing determination of optimal tolerance effects of cocaine (20 mg/kg/8 hr/7 days; IP) as demonstrated by a shift of the curve to the right. To test if pharmacokinetic factors contribute to the development of tolerance to the reinforcing properties of cocaine (20 mg/kg/8hr/7days; IP), cocaine and benzoylecgonine (metabolite) were measured in the plasma and brains of rats given a challenge injection of cocaine (2.0 mg/kg; I.V.). Chronic cocaine did not reduce the concentration of cocaine must be due to pharmacodynamics changes. Acute pretreatment with either the direct dopamine agonists d-amphetamine (0.32-3.2 mg/kg) or methamphetamine (1.0 mg/kg) did not consistently change cocaine self-administration. Chronic high-dose treatment with d-amphetamine and methamphetamine produced cross-tolerance to the reinforcing effects of cocaine but apomorphine (0.32-3.2 mg/kg) did not. In contrast, acute pretreatment with dopamine antagonists; flupentixol (mixed D1 and D2, 0.032-1.0 mg/kg), SCH23390 (specific D1, 0.0032-0.32 mg/kg), or eticlopride (specific D2, 0.0032 -3.2 mg/kg); dose-dependently decreased the reinforcing effects of cocaine (ISRT). Chronic treatment with mixed of D1 antagonists (flupentixol, 3.2 mg/kg/12 hr/5 days; or SCH23390, 0.25 mg/kg/12 hr/7 days) produced sensitization to the reinforcing effects of cocaine, but the D2 antagonist eticlopride (0.25 mg/kg/12 hr/7 days) produced cross-tolerance to the reinforcing effects of cocaine. In summary, both the D1 and D2 receptor subtypes seem to be involved in the acute effects of cocaine; however, the development of tolerance to cocaine appears to involve only the D1 receptor subtype.