Maryland Shared Open Access Repository

MD-SOAR is a shared digital repository platform for twelve colleges and universities in Maryland. It is currently funded by the University System of Maryland and Affiliated Institutions (USMAI) Library Consortium (usmai.org) and other participating partner institutions. MD-SOAR is jointly governed by all participating libraries, who have agreed to share policies and practices that are necessary and appropriate for the shared platform. Within this broad framework, each library provides customized repository services and collections that meet local institutional needs. Please follow the links below to learn more about each library's repository services and collections.

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Recent Submissions

COCAINE INDUCED CONDITIONED TASTE AVERSIONS AND SELF ADMINISTRATION IN THE SQUIRREL MONKEY (Saimiri sciureus)
(1990-05) Williams, Andrew Neil; Hood College Psychology; Human Sciences
Stimuli paired with drug injections can either maintain or suppress responding, depending upon the relationship between those stimuli and the delivery of the drug. In order to assess the role of prior history on this relationship, the effect of previous exposure to cocaine under a maintenance schedule of self-administration or a conditioned taste aversion schedule was examined. Four experimentally naive squirrel monkeys (Saimiri sciureus) initially responded under a FI30(FR30:S) schedule of food presentation. Each FR30 completed produced 2 sec illumination of green light and the first FR30 completed following the elapse of a 30 min interval produced 25 banana pellets in addition to the presence of 5 min of green light. Once responding was stable, the monkeys were placed into two groups matched for weight, rate of responding, and quarter-life. One group was exposed to an operant version of a conditioned taste aversion (CTA) paradigm first, and then later to a cocaine self-administration (SA) paradigm. The other group was exposed to the same conditions but in reverse order. In the operant CTA design the brief stimulus following each FR30 was 2 sec of red light. Twenty five sucrose pellets were delivered at the end of the first completed FR30 once the 30 min interval elapsed along with 5 min of red light and a 0.3mg/kg cocaine injection i.m. (thigh). The self-administration design was very similar to the CTA design, however the stimulus light was green, 25 banana pellets were presented along with a 0.3mg/kg cocaine injection i.m. (thigh) upon the completion of the schedule requirements. When drug naive subjects were exposed to the CTA procedure first their rate of responding dropped significantly from a baseline of 0.71 responses per sec to 0.35 responses per sec, t(8) = 6.62, p< 0.0001. When these same subjects were then exposed to the cocaine self-administration paradigm they responded at 43 percent of their pre-drug food maintenance rates. When drug naive subjects were exposed to the self-administration procedure first they responded at 66 percent of their food maintenance rate of responding. This group was then exposed to the CTA procedure resulting in no significant change in baseline responding t(8) = 1.51, N.S. This study shows that the same dose of cocaine can be used in a CTA design to decrease responding and a self-administration design to maintain responding, that prior exposure to CTA reduced the rate of responding under drug maintenance, and prior exposure to a self-administration design will decrease the effect of CTA.
CO-TRANSFECTION OF TWO HUMAN CELL LINES WITH pSV2-NE0 AND CLONED RESTRICTION FRAGMENTS OF EPSTEIN-BARR VIRUS B95-8 DNA.
(1989-05) Willette-Brown, Jami D.; Hood College Biology; Biomedical and Environmental Science
Introduction of Epstein-Barr virus DNA into mammalian cell lines by microinjection and transfection has been an effective method to study transient viral antigen expression and gene mapping (Boyd, et al., 1985; Glaser et al., 1983; Graessmann, et al., 1980; Stoerker et al., 1981; Takada et al., 1986b). Here I describe a method for the stable introduction of subgenomic fragments of EBV B95-8 DNA into two EBV negative human cell lines, the nasopharyngeal carcinoma line, CNE, and the fibroblast line AD/AH. CNE and AD/AH cells were co-transfected with pSV2-neoᴿ, which contains the bacterial Tn5 neo gene, and recombinant pBR322 plasmids containing individual EcoR12 restriction fragments of B95-8 DNA. Co-transfectants were selected for stable expression of Tn5 neo in G418 supplemented media. Fifty-two AD/AH-neoᴿ and 16 CNE-neoᴿ clones were isolated and screened for expression of viral antigens by indirect immunofluorescence using pre-characterized human sera and monoclonal antibodies specific for EBV antigens. Expression of the nuclear antigen EBNA-3 was detected in the CNE-neoᴿ K clone which had received the EcoR1 restriction fragment. CNE-neoᴿ clones co-transfected with the EcoR1 D, F, H, I, J, L, and M restriction fragments reacted with human sera against EBV early antigens. Two clones, CNE-neoᴿ Cl and CNE-neoᴿ C8, which received the EcoR1 C restriction fragment reacted with anti-VCA human sera. CNEneoᴿ clones were expanded and analyzed for stable maintenance of EBV DNA by Southern blot and stable expression of EBV antigens by Western blot and radio-immunoprecipitation. Two of the expanded CNE-neoᴿ cell lines were found to contain EBV DNA as demonstrated by hybridization of cDNA EBV radiolabeled probes to extracted cellular DNA (H. Ying, personal communication). Expansion of immuno-positive CNE-neoᴿ clones, however, resulted in the loss of EBV antigen expression. Further study is required to determine if loss of antigen expression is due to the lack of EBV DNA stability in neoᴿ co-transformants or due to repression of viral gene expression. The cell lines generated here provide the opportunity to further explore the possible restrictions involved with EBV gene expression.
INVESTIGATING THE EFFECTIVENESS OF POLYETHYLENE SHEETING ON RADON CONCENTRATION
(2008-12) Willard, Michael; Hood College Biology; Biomedical and Environmental Science
A continuous radon monitor encased in different thickness of polyethylene sheeting was used to track the variations in radon concentrations in a crawl space area for one month. Variations in relative humidity, barometric pressure, and temperature were recorded in the crawl space area along with the fluctuations in radon concentration. A multiple linear regression model depicting radon concentration was developed for the independent variables of thickness, relative humidity, and temperature. The study rejected the null hypothesis that there was no multiple linear regression model describing the mean radon concentration. The investigation found that the thickness of the polyethylene sheeting and temperature exhibited a negative correlation with radon concentration, whereas relative humidity showed a positive correlation. Although there was a slight negative correlation between radon concentration and thickness of polyethylene sheeting, it was not an effective remediation strategy in this home.
THE ROAD TO MARXISM: THE INTELLECTUAL JOURNEY OF CHEN DUXIU
(2009-05) Wieland, Natalie; Hood College Arts and Humanities; Humanities
New Real-Time RT-PCR Assay with Single Copy Sensitivity for HIV-1 RNA in Plasma
(2003-09) Wiegand, Ann; Hood College Biology; Biomedical and Environmental Science
Throughout the course of untreated HIV-1 infection, there is extensive virus replication with release of virions into the blood leading to high-level viremia and a genetically diverse virus population. The level of HIV-1 RNA in plasma is an extremely valuable marker of viral RNA level replication, number of productively infected cells, risk of disease progression, and efficacy of antiretroviral therapy. FDA-approved assays that are used routinely to measure plasma HIV-1 RNA have quantification limits of 50-75 copies/ml, and antiretroviral therapy is initially considered successful if viremia can be reduced to below such at these limits. However, reduction of HIV-1 RNA to below 50- 75 copies/m1 does not guarantee long-term success and rebound of drug-resistant virus can occur implying that HIV-1 replication and evolution may be continuing. To investigate this possibility, an assay was developed that accurately measures HIV-1 RNA levels below 50 copies/ml with 50-fold greater sensitivity than the FDA-approved assays. This assay uses larger plasma sample volumes (7m1), improved nucleic acid isolation and purification techniques, and real-time RT-PCR, to accurately quantify HIV-1 in plasma samples with a limit of detection of 1 copy in 3.8m1 of plasma. Since the assay has a detection limit of 1 RNA copy, it is referred to as the single copy assay. To monitor the recovery of HIV-1 from patient plasma, samples are spiked with an internal standard, consisting of the replication-competent avian sarcoma-leukosis retrovirus vector RCAS BP(A), derived from an unrelated retrovirus based on the Rous sarcoma virus. Five important steps were required for the development of this assay: (1) Primer and probe construction in a conserved region of HIV-1 subtype B, in addition to transcripts within the same region for a standard curve; (2) Development and optimization of an RT-PCR assay for real-time PCR (TaqMan); (3) Primer and probe construction in a conserved region of the Rous-Sarcoma Virus (RSV), for the internal virion standard and creation of the transcripts of this same region for a standard curve; (4) Development of a viral RNA extraction method incorporating the internal virion standard; (5) Evaluation of assay sensitivity and reproducibility from start to finish. Access to the Los Alamos database (http://hiv-web.lanl.gov) enabled selection of primers and probe in a highly conserved coding sequence of gag for HIV-1 Subtype B and the RCAS internal virion standard. RNA transcripts were generated and a standard curve of a known quantity was used to develop and optimize a two-step RT-PCR assay for both HIV-1 and RCAS. Patient plasma (7m1/sample) samples with viral RNA concentrations known to be above 50 copies by current commercial methods were spiked with internal standard and used to establish a concentration and extraction method. Extracted samples were assayed in triplicate and the quantity of HIV-1 RNA measured via fluorescent probe technology. Separate analysis of the internal virion standard provided confirmation of the virion recovery and HIV-1 RNA extraction. To compare the performance of the single copy assay with other commonly used HIV-1 RNA assays, a low copy number panel (200 to 0.781 RNA copies/nil) was measured. The single copy assay consistently detected HIV-1 RNA in all samples (200 to 0.781 copies/ml), and the mean values from the 4 assays indicate that HIV-1 RNA could be quantified to 1 copy per ml, although the standard deviation increased at 1.56 and 0.781 copies/ml. To ensure the single copy assay primers and probe accurately quantified HIV-1 RNA, 22 samples from untreated HIV-infected patients with HIV RNA levels >100 copies/ml, were analyzed by both the bDNA and the single copy assay. The single copy assay demonstrated excellent concordance (r²=0.894) with the bDNA assay and 20 out of the 22 patient samples had similar viral RNA levels with both assays. Testing of plasma samples from 15 patients on antiretroviral therapy with HIV-1 RNA <75 copies/ml revealed persistent viremia in all 15 patients with HIV-1 RNA levels ranging from 1 to 32 copies/ml (median of 13 copies/m1). Within 4 to 15 months after the initiation of antiretroviral treatment, four of the 15 patients showed stable, persistent HIV-1 RNA levels of 0.3-41 copies/ml which eventually reached a plateau. The sensitivity of the single copy assay allows for the quantification of persistent low-level viremia in patients whose viral loads are below the point of detection by commercial assays.