Showing papers by "Southern Illinois University Carbondale published in 2003"

The endocrine regulation of aging by insulin-like signals.

Abstract: Reduced signaling of insulin-like peptides increases the life-span of nematodes, flies, and rodents. In the nematode and the fly, secondary hormones downstream of insulin-like signaling appear to regulate aging. In mammals, the order in which the hormones act is unresolved because insulin, insulin-like growth factor-1, growth hormone, and thyroid hormones are interdependent. In all species examined to date, endocrine manipulations can slow aging without concurrent costs in reproduction, but with inevitable increases in stress resistance. Despite the similarities among mammals and invertebrates in insulin-like peptides and their signal cascade, more research is needed to determine whether these signals control aging in the same way in all the species by the same mechanism.

Agency costs, ownership structure and corporate governance mechanisms

Abstract: In this paper, we extend the work of Ang et al. [J. Finance 55 (1999) 81] to large firms. We find that managerial ownership is positively related to asset utilization but does not serve as a significant deterrent to excessive discretionary expenses. Outside block ownership may only have a limited effect on reducing agency costs. Furthermore, smaller boards serve the same role, but independent outsiders on a board do not appear to protect the firm from agency costs. Thus, this paper reports complementary evidence to Ang, Cole and Lin. In large publicly traded corporations, managerial ownership significantly alleviates principal–agent conflicts even in the presence of other agency deterrent mechanisms.

Social Networks and Political Participation: The Role of Social Interaction in Explaining Political Participation

Abstract: The argument advanced in this article is that interaction in social networks has a strong, though often over-looked, influence on the propensity to participate in politics. Specifically, I argue that social interaction creates opportunities for individuals to gather information about politics that allows them to live beyond personal resource constraints, thereby supporting the political activity of many people. Using relational data from the South Bend Election Study, this article provides evidence that the effect of social interaction on participation is contingent on the amount of political discussion that occurs in social networks. Additional analysis shows the substantive and theoretical importance of such interaction by explaining how it is distinct from the effect of social group memberships and how it enhances the effect of individual education on the probability of participation. This key contribution of this article is to show that models of political participation that do not account for informa...

Delay discounting by pathological gamblers.

Abstract: Discounting of delayed rewards by pathological gamblers was compared to discounting of delayed rewards by matched control nongambling participants All participants completed a hypothetical choice task in which they made repeated choices between dollars 1,000 available after a delay and an equal or lesser amount of money available immediately The delay to the large amount of money was varied from 1 week to 10 years across conditions Indifference points between immediate money and delayed money were identified at each delay condition by varying the amount of immediate money across choice trials For the majority of participants, indifference points decreased monotonically across delays Overall, gamblers discounted the delayed rewards more steeply than did control participants

The nature and identification of quantitative trait loci: a community's view.

Abstract: This white paper by eighty members of the Complex Trait Consortium presents a community's view on the approaches and statistical analyses that are needed for the identification of genetic loci that determine quantitative traits. Quantitative trait loci (QTLs) can be identified in several ways, but is there a definitive test of whether a candidate locus actually corresponds to a specific QTL?

Soy Isoflavones Exert Antidiabetic and Hypolipidemic Effects through the PPAR Pathways in Obese Zucker Rats and Murine RAW 264.7 Cells

Abstract: The hypocholesterolemic and anti-atherosclerotic mechanism by which soy may exert a beneficial effect remains unclear. Peroxisome-proliferator activated receptors (PPAR) are promiscuous nuclear receptors that regulate the transcription of genes involved in lipid and glucose homeostasis and lipid metabolism within the cell. We hypothesize that the isoflavones improve lipid and glucose metabolism by acting as an antidiabetic PPAR agonist. Male and female obese Zucker rats (OZR) were used as a model of Type 2 diabetes, and OZR fed a high isoflavone soy protein diet displayed improvements in lipid metabolism consistent with results in humans treated with antidiabetic PPAR agonists such as the fibrates or glitazones. Liver triglyceride and cholesterol concentrations were lower in all OZR fed high-isoflavone soy protein diets than in rats fed low-isoflavone and casein diets (P < 0.05). Concurrently, PPAR-directed gene expression was evaluated in a cell culture model. An isoflavone-containing soy extract doubled PPAR-directed gene expression (P < 0.05) in RAW 264.7 cells containing either a PPARalpha or PPARgamma expression plasmid. A similar induction was observed when the soy isoflavones genistein or daidzein were used to treat cells. Both isoflavones doubled PPARalpha-directed gene expression (P < 0.05), whereas they increased PPARgamma-directed gene expression 200-400% (P < 0.05). This study suggests that soy isoflavones improve lipid metabolism, produce an antidiabetic effect, and activate PPAR receptors.

Ecological traits predicting amphibian population declines in Central America

Abstract: Amphibian populations are declining on all continents on which they occur, but not all species have been affected equally. Populations of some species are extirpated, others have declined but survive, some have not obviously declined, and some are increasing. If amphibian populations at multiple sites were affected by the same factors, then surviving species should share traits that promote persistence, whereas declining species should share traits that promote susceptibility. Identifying these traits can help diagnose potential causes and thus help to direct conservation actions. Using logistic regression, we quantified the vulnerability of amphibian populations in four areas in Central America. We analyzed a species-specific database of taxonomic identity, geographic and elevational range, elevational distribution, adult and larval habitat, activity period, and maximum adult body size. We found that ( 1 ) all four sites exhibited the same pattern of decline ( there were no interactions between site and other variables ); ( 2 ) declining populations shared aquatic habitats, restricted elevational ranges, and large body sizes; and ( 3 ) there was an interaction between body size and elevational range. The most significant variable in the model was lifetime aquatic index, a factor unrelated to demographic vulnerability and one that therefore might indicate the potential causative agent( s ). Our results provide a predictive model with which to assess potential causes of population declines in other areas, and we generated a list of 52 species predicted to decline at a currently unaffected site in central Panama.

Multilocus sequence typing suggests the chytrid pathogen of amphibians is a recently emerged clone

Abstract: Chytridiomycosis is a recently identified fungal disease associated with global population declines of frogs. Although the fungus, Batrachochytrium dendrobatidis , is considered an emerging pathogen, little is known about its population genetics, including the origin of the current epidemic and how this relates to the dispersal ability of the fungus. In this study, we use multilocus sequence typing to examine genetic diversity and relationships among 35 fungal strains from North America, Africa and Australia. Only five variable nucleotide positions were detected among 10 loci (5918 bp). This low level of genetic variation is consistent with the description of B. dendrobatidis as a recently emerged disease agent. Fixed (i.e. 100%) or nearly fixed frequencies of heterozygous genotypes at two loci suggested that B. dendrobatidis is diploid and primarily reproduces clonally. In contrast to the lack of nucleotide polymorphism, electrophoretic karyotyping of multiple strains demonstrated a number of chromosome length polymorphisms.

Citizen Perceptions of Police Services: Race, Neighborhood Context, and Community Policing

Abstract: Studies considering perceptions of the police have traditionally focused on very broad outcome measures (e.g., global views of the police). In an era of community policing, it is imperative to consider how the public perceives the police and police services using measures reflecting this alternative paradigm of policing. In addition, recent research suggests that perceptions of the police are formed within the context of respondents’neighborhood cultures and contexts. This research examines factors predicting citizen perceptions of police services in a Midwestern community, incorporating variables reflecting respondents’ demographic traits, experiences, and neighborhood contexts. The analysis tests the predictive power of these factors using both traditional outcome measures and perceptions of police services based on community-policing criteria. The findings demonstrate the need for multidimensional constructs of citizen perceptions of police services and highlight important dimensions of public percepti...

Delayed Occurrence of Fatal Neoplastic Diseases in Ames Dwarf Mice: Correlation to Extended Longevity

Abstract: Ames dwarf mice have drawn much attention in aging research because of their marked life extension. Studies demonstrate that some of the physiological characteristics of Ames dwarf mice are similar to those of dietary restricted mice. Because dietary restriction has been shown to suppress and/or delay the occurrence of various age-related diseases, we investigated age-related pathological changes in Ames dwarf mice. We observed Ames dwarf mice to have a delayed occurrence of presumably fatal neoplastic disease compared with their normal siblings. In addition to the delayed occurrence, we found that the incidence of presumably fatal adenocarcinoma in lung was significantly lower in Ames dwarf mice than for their normal siblings. The delayed occurrence of total neoplastic lesions and reduced incidence of adenocarcinoma in lung possibly could be attributed to the retardation of tumor development by changes in the levels of growth hormone and insulin-like growth factor-1, and thereby be a major contributing factor to the extended life span observed in these mice.

The Impact of Content and Design Elements on Banner Advertising Click-through Rates

Abstract: This study investigates the impact of content and design elements on the click-through rates of banner advertisements using data from 8,725 real banner advertisements. It is one of the first empirical studies to examine banner advertising effectiveness (measured by click-through rates) and also one of the first to examine the differences between business-to-business (B2B) and business-to-consumer (B2C) banner advertisements. Content elements examined include the use of incentives and emotional appeals. Design elements examined include the use of interactivity, color, and animation. Results suggest that content and design elements do not work the same way for B2B and B2C banner advertisements.

Parasite establishment in host communities

Abstract: Many pathogens and parasites attack multiple host species, so their ability to invade a host community can depend on host community composition. We present a graphical isocline framework for studying disease establishment in systems with two host species, based on treating host species as resources. The isocline approach provides a natural generalization to multi-host systems of two related concepts in disease ecology – the basic reproductive rate of a parasite, and threshold host density. Qualitative isocline shape characterizes the threshold community configurations that permit parasite establishment. In general, isocline shape reflects the relative forces of inter- and intraspecific transmission of shared parasites. We discuss the qualitative implications of parasite isocline shape for issues of mounting concern in conservation ecology.

Functional activity of serotoninergic and melatoninergic systems expressed in the skin.

Abstract: We tested the expression of genes coding receptors of a cutaneous serotoninergic/melatoninergic system in whole human skin and in normal and pathologic cultured skin cells. Evaluation of serotonin (5HT), melatonin (MT), and melatonin-related receptors (MRR) showed expression of the isoforms 5HT2B, 5HT7, and MT1 genes in almost all the tested samples. Expression of other isoforms was less prevalent; 5HT2C, MRR, and MT2 were rarely detected. We also found novel isoforms for MT2, MRR, and 5HT2B and documented the process of RNA editing for 5HT2C. Testing for functional activity of these receptors with serotonin and melatonin (10(-14) to 10(-10) M) showed variable effects depending on cell type and culture conditions. Thus, serotonin stimulated proliferation of melanocytes in medium deprived of growth factors, while inhibiting cell growth in the presence of growth factors. Melatonin inhibited both apoptosis of HaCaT keratinocytes incubated in serum-free media, and proliferation of cells cultured in medium supplemented with serum. Melatonin also increased the numbers of viable fibroblasts incubated in serum free medium. N-acetylserotonin (NAS) and 5 methoxytryptamine (5MTT) were generally without effect on cell proliferation, with the exception of an inhibition of melanocyte proliferation at the higher 5MTT concentration of 10(-10) M. Thus, skin cells represent a true target for the products of the serotoninergic/melatoninergic cutaneous pathway with their actions modulating cell proliferation or viability.

Effects of resistance versus aerobic training on coronary artery disease risk factors.

Abstract: Individuals exhibiting "the metabolic syndrome" have multiple coronary artery disease risk factors, including insulin resistance, hyperlipidemia, hypertension, and android obesity. We performed a randomized trial to compare the effects of aerobic and resistance training regimens on coronary risk factors. Twenty-six volunteers who exhibited android obesity and at least one other risk factor for coronary artery disease were randomized to aerobic or resistance training groups. Body mass index, waist-to-hip ratio, glucose, insulin, body composition, 24-hr urinary albumin, fibrinogen, blood pressure, and lipid profile were measured at baseline and after 10 weeks of exercise training. Both groups showed a significant reduction in waist-to-hip ratio and the resistance training group also showed a reduction in total body fat. There was no significant change in mean arterial blood pressure in either group. Fasting plasma glucose, insulin, total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides were unchanged in both groups. High-density lipoprotein (HDL) cholesterol increased (13%) with aerobic training only. Plasma fibrinogen was increased (28% and 34%, P < 0.02) in both groups and both groups showed a significant decrease (34% and 28%, P < 0.03) in microalbuminuria after their respective training regimen. In conclusion, resistance training was effective in improving body composition of middle-aged obese sedentary males. Only aerobic training was effective in raising HDL cholesterol. More studies are warranted to assess the effects of exercise on plasma fibrinogen and microalbuminuria.

Human Papillomavirus Type 16 and Immune Status in Human Immunodeficiency Virus-Seropositive Women

Abstract: Background Human papillomavirus (HPV) type 16 is etiologically associated with approximately half of all cervical cancers. It is important, therefore, to determine the characteristics that distinguish HPV16 from other HPV types. A preliminary result based on cross-sectional baseline data in the Women's Interagency Human Immunodeficiency Virus (HIV) Study (WIHS) suggested that the prevalence of HPV16 might have a weaker association with immune status in HIV-seropositive women than that of other HPV types. To address this issue, we examined HPV test results from repeated study visits in the WIHS and from an independent study, the HIV Epidemiology Research Study (HERS). Methods HIV-seropositive women in the WIHS (n = 2058) and in the HERS (n = 871) were assessed semiannually. HPV DNA was detected in cervicovaginal lavage specimens by using polymerase chain reaction assays. Prevalence ratios were used to compare the prevalence of each HPV type in women with the lowest CD4+ T-cell counts ( or =500 T cells/mm3). A summary prevalence ratio for each HPV type (i.e., across visits and studies) was estimated using generalized estimating equations. The association of CD4+ T-cell stratum with type-specific HPV incidence was measured using multivariable Cox regression models. All statistical tests were two-sided. Results The prevalence ratio for HPV16 was low compared with that of other HPV types at every study visit in both cohorts. The generalized estimating equation summary prevalence ratio for HPV16 (1.25, 95% confidence interval [CI] = 0.97 to 1.62) was the smallest measured, and it was statistically significantly lower than that of all other HPV types combined (P =.01). The association of CD4+ T-cell stratum with HPV16 incidence was also among the smallest measured (hazard ratio = 1.69, 95% CI = 1.01 to 2.81). Conclusions The prevalent and incident detection of HPV16 is more weakly associated with immune status in HIV-seropositive women than that of other HPV types, suggesting that HPV16 may be better at avoiding the effects of immune surveillance, which could contribute to HPV16's strong association with cervical cancer.

The predictive power of implied volatility: Evidence from 35 futures markets

Abstract: Using data from 35 futures options markets from eight separate exchanges, we test how well the implied volatilities (IVs) embedded in option prices predict subsequently realized volatility (RV) in the underlying futures. We find that for this broad array of futures options, IV performs well in a relative sense. For a large majority of the commodities studied, the implieds outperform historical volatility (HV) as a predictor of the subsequently RV in the underlying futures prices over the remaining life of the option. Indeed, in most markets examined, regardless of whether it is modeled as a simple moving average or in a GARCH framework, HV contains no economically significant predictive information beyond what is already incorporated in IV. These findings add to previous research that has focused on currency and crude oil futures by extending the analysis into a very broad array of contracts and exchanges. Our results are consistent with the hypothesis that futures options markets in general, with their minimal trading frictions, are efficient.

A boost or bust for democracy? How the web influenced political attitudes and behaviors in the 1996 and 2000 presidential elections

Abstract: This study employed an online survey of 442 politically interested Web users during the 2000 presidential election to examine the extent to which relying on the Web for political information influe...

The interactive work of prosody in the IRF exchange: Teacher repetition in feedback moves

Abstract: This article examines the interactive import of prosody from a perspective of participants’ orientation to talk in interaction, taking advantage of data from institutional discourse to focus on the prosodic packaging of recurring turn sequences of the same discourse activity. The analysis focuses on the third slot of a ubiquitous three-part classroom discourse sequence, the IRF exchange (Sinclair & Coulthard 1975), a site in which teachers make repetitive feedback moves following student responses. Examination of more than 25 hours of classroom discourse and more than 300 third-turn teacher feedback types uncovered a systematic use of prosody for these teacher repetitions that coincides with a teacher’s positive assessment of the student response. Further analysis shows that more complex prosodic packaging is used by teachers in their repetitive feedback turns to index other interactive functions. (Prosody, repetition, classroom discourse.)*

Do Organizational Cultures Replicate National Cultures? Isomorphism, Rejection and Reciprocal Opposition in the Corporate Values of Three Countries

Abstract: Despite the intuitive relation between national and organizational culture, empirical research relating the two phenomena is sparse This article compares the national and organizational cultures of India, Brazil, and the USA, uncovering a significant but complex relationship Clusters are found in all three countries that both systematically replicate and reject national values Possible reasons for these `isomorphic' and `rejective' responses to national culture are explored and their theoretical implications developed

Surface Manipulation of the Electronic Energy of Subnanometer-Sized Gold Clusters: An Electrochemical and Spectroscopic Investigation

Abstract: Stable undecagold clusters were synthesized and protected with a monolayer of alkanethiolates. The particles were found to exhibit semiconductor electronic characteristics with a band gap of about 1.8 eV, as evaluated from voltammetric and spectroscopic measurements. Photoluminescence in the visible range was also observed from the peak position at 840 nm. The indirect band-gap characteristics indicate that there exist substantial surface trap states in the nanoparticle molecules. Prior to exchange reactions with alkanethiols, however, no luminescence was observed with the gold particles, Au11Cl3(PPh3)7. This was interpreted, at least in part, by the effect of ligand fields on the electronic (band-gap) energy splitting and the resulting electron distributions. These observations strongly suggest that surface chemistry plays a vital role in determining the electronic energy structure of these subnanometer-sized gold particles.

A combined analytic signal and Euler method (AN-EUL) for automatic interpretation of magnetic data

Abstract: We present a new automatic method of interpretation of magnetic data, called AN-EUL (pronounced “an oil”). The derivation is based on a combination of the analytic signal and the Euler deconvolution methods. With AN-EUL, both the location and the approximate geometry of a magnetic source can be deduced. The method is tested using theoretical simulations with different magnetic models placed at different depths with respect to the observation height. In all cases, the method estimated the locations and the approximate geometries of the sources. The method is tested further using ground magnetic data acquired above a shallow geological dike whose source parameters are known from drill logs, and also from airborne magnetic data measured over a known ferrometallic object. In both these cases, the method correctly estimated the locations and the nature of these sources.

Evidence-Based Practice: A Framework for Twenty-First-Century Scientist-Practitioner Training

Abstract: A consensus has long existed that the scientist-practitioner model has failed to reflect what was envisioned by the Boulder Conference participants and endorsed by counseling psychology at the Grey...

Diversity of Geobacteraceae species inhabiting metal-polluted freshwater lake sediments ascertained by 16S rDNA analyses.

Abstract: The abundance, distribution, and phylogenetic diversity of members of the Fe(III)-reducing family Geobacteraceae were studied along a gradient of metal contaminants in Lake Coeur d’Alene, Idaho. Partial 16S rRNA gene fragments were amplified by PCR using primers directed toward conserved regions of the gene within the family Geobacteraceae. Analysis of amplicons separated by denaturing gradient gel electrophoresis (DGGE) suggested within-site variation was as great as between-site variation. Amplicons were cloned and grouped by RFLP type and DGGE migration distance and representatives were sequenced. Grouping clones with 3% or less sequence dissimilarity, 15 distinct phylotypes were identified compared to 16 distinct DGGE bands. Only 1 phylotype was recovered from all sites. This clone, B14, is most closely related to Geobacter metallireducens and constituted a greater portion of the pristine community than of the contaminated communities. A second phylotype, Q2, predominated in the contaminated communities and was notably absent from the pristine libraries. Clone Q2 presents a high degree of sequence similarity to two Geobacter spp. previously isolated from this region of Lake Coeur d’Alene. Six phylotypes were unique to the contaminated sediments, whereas two were found only in the pristine sediments. Indices of diversity (Shannon and Simpson) were consistently higher when calculated with DGGE data than when clone library data were used. Most-probable-number PCR and real-time PCR suggested that the Geobacteraceae phylotypes were spread relatively evenly across all three sites along the gradient. Our data indicate that the Geobacteraceae are diverse and abundant in Lake Coeur d’Alene sediments, regardless of metals content. These results provide insight into the ability of dissimilatory Fe(III)-reducing bacteria to colonize habitats with elevated metal concentrations, and they have important implications for the management and remediation of metal-contaminated sites.