196,510 research outputs found
Toxicity of smokeless tobacco in human oral epithelium with emphasis on carcinogen metabolism and regulation of programmed cell death
No full textThe oral mucosa is globally a common site for cancer development. Primary risk factors include tobacco smoking and alcohol consumption whereas the contribution from usage of smokeless tobacco remains debated. The susceptibility of the human oral epithelium to carcinogens in tobacco likely depends on the presence of biotransformation enzymes, capable of metabolically activating or detoxifying these agents as well opposing influences from oxidative stress. Induction of programmed cell death (PCD), including function of tumor suppressor p53, may also modulate smokeless tobacco toxicity. On this basis, the purpose of this study was to investigate the expression of biotransformation enzymes as well as the roles of PCD and p53 in smokeless tobacco toxicity in oral epithelium.Various qualitative and quantitative analyses of oral tissue specimens and normal, immortalized and malignant oral keratinocytes indicated presence of multiple biotransformation enzymes. Several cytochrome P450 (CYP) transcripts were demonstrated including ]AL 1A2, 2C, 2D6, 2E1, 3A4/7 and 3A5. 'typical CYP substrates, including ethoxyresorutin, methoxyresorufin and chlorzoxazone, were delectably oxidized in vitro and metabolism of the tobacco-specific N-nitrosamine 4-(methylnitrosamino)1- (3-pyridyl)-1-butanone (NNK) and aflatoxin B1 (AFB1) resulted in covalently bound adducts. Moreover, normal keratinocytes and SV40T antigen-immortalized keratinocytes (SVpgC2a) were shown to express enzymes catalyzing conjugation reactions and detoxification of reactive oxygen. Notably, SVpgC2a showed higher expression levels than normal keratinocytes of some enzymes, e.g. CYP1B1, By RT-PCR, the CYPs where generally shown to be expressed at levels 1000 molecules, using 106 molecules of beta-actin as reference. Microarray analysis confirmed expression of these enzymes at levels >300 molecules per 1 06 molecules of beta-actin. The results indicated presence of several biotransformation enzymes in oral buccal mucosa in vivo and in vitro, indicating the usefulness of oral keratinocyte cell lines for studies of both single agents and complex mixtures in human oral epithelium.Studies of smokeless tobacco toxicity involved cultured oral keratinocyte cell lines and oral tissue specimens obtained from healthy controls, snuff users (SDL) and patients diagnosed for lichen planus (OLP). Assessments of net growth rates. apoptosis, necrosis and terminal differentiation in vitro showed that aqueous smokeless tobacco extract prepared from "Ettans snus" (STE) primarily caused necrotic death without substantial involvement of PCD. Carcinoma cells (SqCC/Y1) were more resistant to necrosis from STE as compared to normal cells. Extract prepared from "Kentucky standard reference tobacco" caused similar toxicity as STE. The latter extract induced increases in p53 content that did not associate to increased apoptosis, whereas in contrast. the DNA damaging agent mitomycin C (MMC) increased both p53-content and apoptosis. STE and nicotine separately. significantly inhibited apoptosis induced by various regimens. Slight increases in bcl-2 transcripts in STE-exposed keratinocytes indicated the involvement of this gene. Analysis of Jurkat cells implied that reactive smokeless tobacco chemicals might also block apoptosis by inhibiting caspase activity. Oral tissue analysis agreed with the concept that smokeless tobacco may inhibit apoptosis, i.e. increased mitosis in SDL (relative to normal controls) was not associated with increased apoptosis, whereas OLP exhibited increases in both mitosis and apoptosis. Finally, expression of the p53 and Bcl-2 proteins was noted in SDL whereas OLP expressed p53 but not bcl-2.In summary, the analysis of the expression of biotransformation enzymes and smokeless tobacco toxicity generally demonstrated similar results in tissue and cultured cell lines implying the usefulness of cell culture technology in the investigation of mechanisms underlying carcinogenesis and other oral disease processes. Thus. keratinocytes actively expressing multiple biotransformation enzymes were susceptible to smokeless tobacco toxicity. The toxicity mechanism of smokeless tobacco likely involves metabolism of carcinogenic agents, including N-nitrosamines. and inhibition of p53-mediated apoptosis. Thus, this study suggests several mechanisms whereby smokeless tobacco usage may contribute to adverse health effects including those associated with cancer development in the oral epithelium.List of scientific papersI. Vondracek M, Xi Z, Larsson P, Baker V, Mace K, Pfeifer A, Tjalve H, Donato MT, Gomez-Lechon MJ, Grafstrom RC (2001). "Cytochrome P450 expression and related metabolism in human buccal mucosa. " Carcinogenesis 22(3): 481-8 https://pubmed.ncbi.nlm.nih.gov/11238190II. Crawford EL, Peters GJ, Noordhuis P, Rots MG, Vondracek M, Grafstrom RC, Lieuallen K, Lennon G, Zahorchak RJ, Georgeson MJ, Wali A, Lechner JF, Fan PS, Kahaleh MB, Khuder SA, Warner KA, Weaver DA, Willey JC (2001). "Reproducible gene expression measurement among multiple laboratories obtained in a blinded study using standardized RT (StaRT)-PCR. " Mol Diagn 6(4): 217-25 https://pubmed.ncbi.nlm.nih.gov/11774186III. Vondracek M, Weaver DA, Sarang Z, Hedberg JJ, Willey JC, Warngard L, Grafstrom RC (2002). "Transcript profiling of enzymes involved in detoxification of xenobiotics and reactive oxygen in human normal and simian virus 40 T antigen-immortalized oral keratinocytes. " Int J Cancer 99(6): 776-82 https://pubmed.ncbi.nlm.nih.gov/12115477IV. Vondracek M, Hansson A, Zheng X, Sand L, Noren U, Hirsch JM, Lindholm J, Grafstrom RC (2002). "Smokeless tobacco toxicity and influences on programmed cell death in human oral mucosa in vivo and in vitro." (Manuscript)V. Vondracek M, Zheng X, Noren U, Elfwing A, Grafstrom RC (2002). "Influences of smokeless tobacco extract on growth and apoptosis in cultured human normal and malignant buccal keratinocytes." (Manuscript)</p
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
Patterns of ancestry and genetic diversity in reintroduced populations of the slimy sculpin: implications for conservation
No full textReintroductions are a common approach for
preserving intraspecific biodiversity in fragmented landscapes.
However, they may exacerbate the reduction in
genetic diversity initially caused by population fragmentation
because the effective population size of reintroduced
populations is often smaller and reintroduced populations
also tend to be more geographically isolated than native
populations. Mixing genetically divergent sources for
reintroduction purposes is a practice intended to increase
genetic diversity. We documented the outcome of reintroductions
from three mixed sources on the ancestral composition
and genetic variation of a North American fish, the
slimy sculpin (Cottus cognatus). We used microsatellite
markers to evaluate allelic richness and heterozygosity in
the reintroduced populations relative to computer simulated
expectations. Sculpins in reintroduced populations
exhibited higher levels of heterozygosity and allelic richness
than any single source, but only slightly higher than
the single most genetically diverse source population.
Simulations intended to mimic an ideal scenario for maximizing
genetic variation in the reintroduced populations
also predicted increases, but they were only moderately
greater than the most variable source population. We found
that a single source contributed more than the other two
sources at most reintroduction sites. We urge caution when
choosing whether to mix source populations in reintroduction
programs. Genetic characteristics of candidate
source populations should be evaluated prior to reintroduction
if feasible. When combined with knowledge of the
degree of genetic distinction among sources, simulations
may allow the genetic diversity benefits of mixing populations
to be weighed against the risks of outbreeding
depression in reintroduced and nearby populations.Huff, David, D.; Miller, Loren, M.; Vondracek, Bruce. (2010). Patterns of ancestry and genetic diversity in reintroduced populations of the slimy sculpin: implications for conservation. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/183583
Electronic properties of GaAsBi(001) alloys at low Bi content
No full textWe present an in-depth investigation of structural and electronic properties of GaAsBi epilayers. High (001) crystalline order is achieved using careful molecular beam epitaxy and surface preparation procedures. High surface order allows us to use x-ray, ultraviolet, and angle-resolved photoemission spectroscopy at variable photon energies and to disentangle electronic effects of an atomically thin Bi-rich surface layer with (2 x 3) symmetry from those of Bi atoms incorporated in the GaAs bulk matrix. The influence of bulk-integrated Bi concentrations on the GaAs band structure becomes visible in angle-resolved photoemission after removing Bi-rich surface layers by a brief and mild ion bombardment and subsequent annealing treatment. Experimental observations are supported by density functional theory simulations of the valence band structure of bulk and surface-reconstructed GaAs with and without Bi. Bi-induced energy shifts in the dispersion of GaAs heavy and light hole bulk bands are evident both in experiment and theory, which are relevant for modulations in the optical band gap and thus optoelectronic applications
Simulation of thermal plant optimization and hydraulic aspects of thermal distribution loops for large campuses
No full textFollowing an introduction, the author describes Texas A&M University and its utilities system. After that, the author presents how to construct simulation models for chilled water and heating hot water distribution systems. The simulation model was used in a $2.3 million Ross Street chilled water pipe replacement project at Texas A&M University. A second project conducted at the University of Texas at San Antonio was used as an example to demonstrate how to identify and design an optimal distribution system by using a simulation model. The author found that the minor losses of these closed loop thermal distribution systems are significantly higher than potable water distribution systems. In the second part of the report, the author presents the latest development of software called the Plant Optimization Program, which can simulate cogeneration plant operation, estimate its operation cost and provide optimized operation suggestions. The author also developed detailed simulation models for a gas turbine and heat recovery steam generator and identified significant potential savings. Finally, the author also used a steam turbine as an example to present a multi-regression method on constructing simulation models by using basic statistics and optimization algorithms. This report presents a survey of the author??s working experience at the Energy Systems Laboratory (ESL) at Texas A&M University during the period of January 2002 through March 2004. The purpose of the above work was to allow the author to become familiar with the practice of engineering. The result is that the author knows how to complete a project from start to finish and understands how both technical and nontechnical aspects of a project need to be considered in order to ensure a quality deliverable and bring a project to successful completion. This report concludes that the objectives of the internship were successfully accomplished and that the requirements for the degree of Degree of Engineering have been satisfied
Calophyinae Vondracek 1957
No full textSubfamily * Calophyinae Vondráček, 1957 Microceropsyllini Bekker-Migdisova, 1973: 104. Strogylocephalidae Li, 2011: 1257. Comments The subfamily was diagnosed by Burckhardt & Ouvrard (2012). Included genera * Calophya Löw, 1879 (syn. Calophya (Neocalophya), Holotrioza, Microceropsylla, Paracalophya, Pelmatobrachia); Pseudoglycaspis Brown & Hodkinson, 1988; * Strogylocephala Crawford, 1917 (syn. Synaphalara).Published as part of Burckhardt, Daniel, Ouvrard, David & Percy, Diana M., 2021, An updated classification of the jumping plant-lice (Hemiptera: Psylloidea) integrating molecular and morphological evidence, pp. 137-182 in European Journal of Taxonomy 736 on page 147, DOI: 10.5852/ejt.2021.736.1257, http://zenodo.org/record/459433
1961 Jay-Cee-An BJC -- Page 66
No full textPhotographs of BJC sophomoresBruce Riedman Joe Vondracek Michael Michalenko Bill Kleven
B. RIEDMAN - Bismarck; Pre-Law; Pep Band 1; Bagpipe Band; LSA 1.2; Circle K 1.
2. 1. VONDRACEK - Bismarck; Liberal Arts; Pep Band 1.2. M. MICHALENKO -
Bismarck; Liberal Arts. B. KLEVEN - Bismarck; LSA 2; Liberal Arts; International
Relations Club 2. A. HOLMEN - Livingston, Montana; Pre-Nursing.
Arlene Holmen
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