Penn McNair Research Journal: Volume 1, Issue 1

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Now showing 1 - 5 of 5
  • Publication
    Fast Rhythmic Bursting Cells: The Horizontal Fiber System in the Cat’s Primary Visual Cortex
    (2007-11-14) Lee, Jin
    One of the cellular mechanisms underlying the generation of gamma oscillations is a type of cortical pyramidal neuron named fast rhythmic bursting (FRB) cells. After 58 cells from 21 cats' primary visual cortices were filled with Neurobiotin, the brains were cut, and the cells were photographed. From all cells, 1 non-pyramidal and 4 pyramidal cell (3 regular spiking (RS) cells & 1 FRB cell) were confocaled, reconstructed with Neurolucida, and analyzed with NeuroExplorer. All 5 cells showed a linear correlation (>0.94) between length and number of intersections. Their polar histograms indicated that the FRB cell has triple dendritic length, twice the number of dendritic tree orders and mean length compared to the 4 other cells. We propose that FRB cells are key elements of the horizontal fiber system that links cell populations with similar feature selections throughout the primary visual cortex.
  • Publication
    Bilingual Education in California: Is It Working?
    (2007-11-16) Trujillo, Monica
    The topic of bilingual education has received heightened attention over the past few decades. How to educate children with limited English skills, or English learners (EL), is a highly controversial and debatable issue that deserves attention because of the vast numbers of English learners in the United States today. ELs are students for whom English is a second language and who come from homes in which a language other than English is spoken. Currently, there are about 5.5 million ELs in U.S. public schools (U.S. Department of Education, 2004). Their numbers have been growing dramatically over the past few decades, making them one of the fastest-growing student populations in the United States (Slavin & Cheung, 2004, p. 52). For example, from 1980 to 2000 the EL population doubled from 6 percent to 12 percent in the United States (Morse, 2002). Of this population, the majority of students are Spanish speakers (79%). This makes bilingual education largely a Latino issue.
  • Publication
    Linking Health and Economic Development: HIV/AIDS Prevalence as an Indicator of Economic Growth
    (2007-12-19) Chia, Luis
    Today we are witnessing what may amount to the biggest health and development challenge the world has ever faced. Having caused the deaths of 20 million people globally since its discovery in 1981, HIV/AIDS is unique in its devastating impact on the social, economic and demographic foundations of development. Today, the number of people infected with HIV in the world has already reached an estimated 39.4 million, with over 95% of them living in the developing world. Like clockwork, as every minute passes, 6 people die from AIDS, amounting to a daily loss of 8500 lives. Despite increased funding, political commitment, progress in expanding access to HIV treatment, and major developments in the fight against HIV and AIDS, including anti-retroviral medicines, rates of infection are still on the rise. Time and time again, the AIDS epidemic has outpaced the global response. Thus, if we are to turn the tide, effective intervention strategies are needed now.
  • Publication
    Searching for the Source: Determining NAD+ Concentrations in the Yeast Vacuole
    (2007-11-15) Hardiman, Camille
    The burgeoning field of bioremediation relies on the natural abilities of plants and fungi to accumulate certain toxic heavy metals. In heavy metal detoxification, plant and yeast vacuoles are responsible for the sequestration of toxins away from the cytoplasm. A yet-unpublished study done by the Rea group analyzed the protein profile of the vacuolar lumen in the budding yeast Saccharomyces cerevisiae. Several NAD+-dependent dehydrogenases were found within this compartment, a surprising finding in light of the yeast vacuole's predominantly lytic function. Five of these enzymes were found to increase in level in the vacuole during heavy metal stress. Moreover, when vacuolar lysates were assayed in vitro, they were found to contain dehydrogenase activity when exogenous NAD+ or NADH was provided. If these enzymes are also active in this compartment in vivo, the question is raised: from where do the cofactors required for the reactions that these enzymes catalyze come? If these enzymes had a vacuolar source of NAD+, they could also potentially be active in vivo. Thus, in the present project, we are seeking to determine the concentration of NAD+ inside the vacuole of S. cerevisiae. Toward this end, high-purity "proteomics-grade" intact vacuoles were isolated from S. cerevisiae by a combination of differential, density, and floatation centrifugation. NAD+ was then extracted by acid precipitation and solvent extraction to separate vacuolar proteins from cofactor. NAD+ was quantified using a two-step redox-coupled reaction system containing phenazine methosulfate (PMS) as mediator and thiazoyl blue tetrazolium bromide (MTT) as terminal electron acceptor. The spectrophotometric measurement of reduced MTT at 570 nm is an indirect measure of the initial NAD+ concentration. To provide a basis for comparison, the estimated NAD+ content of isolated vacuoles was compared to that of spheroplasts lysates extracted and assayed identically. The results indicate that the intravacuolar concentration of NAD+ is two orders of magnitude lower than that of the spheroplast (5.2 vs. 202 μM), which may have implications for this redox-active cofactor’s function in the vacuole. These findings may necessitate the reconsideration of the role played by vacuolar dehydrogenases in yeast cell metabolism (and possibly the metabolism of other vacuolate cells). Our findings suggest that the vacuolar pool of NAD+ may be sufficient for utilization in the vacuole.
  • Publication
    Home Language Use and Hispanic Academic Achievement: Evidence from Texas High Schools
    (2007-12-18) Hernandez, Carlos
    Hispanics, the nation’s largest ethnic minority, are largely characterized by their low levels of education and Spanish-speaking backgrounds. In 1989, 96% of Hispanic school-aged children lived in homes where Spanish is spoken at home. Because many Hispanics speak Spanish at home, this study seeks to explore the association between foreign language use at home and academic achievement. Using data from the Texas Higher Education Opportunity Project, preliminary cross-tabulations find that home language use does not sufficiently explain academic achievement patterns across race/ethnic groups. However, a strong correlation is shown between parental academic background and academic success. Bivariate analyses find that Hispanics who have at least one parent with a college education will perform significantly better and narrow achievement gaps between Hispanics and Whites and Asians.