Developmental Exposure of Rats to Chlorpyrifos Elicits Sex-Selective Hyperlipidemia and Hyperinsulinemia in Adulthood

Developmental exposure to chlorpyrifos alters cell signaling both in the brain and in peripheral tissues, affecting the responses to a variety of neurotransmitters and hormones. We administered 1 mg/kg/day chlorpyrifos to rats on postnatal days 1–4, a regimen below the threshold for systemic toxicity. When tested in adulthood, chlorpyrifos-exposed animals displayed elevations in plasma cholesterol and triglycerides, without underlying alterations in nonesterified free fatty acids and glycerol. This effect was restricted to males. Similarly, in the postprandial state, male rats showed hyperinsulinemia in the face of normal circulating glucose levels but demonstrated appropriate reduction of circulating insulin concentrations after fasting. These outcomes and sex selectivity resemble earlier findings at the cellular level, which identified hepatic hyperresponsiveness to gluconeogenic inputs from β-adrenoceptors or glucagon receptors. Our results thus indicate that apparently subtoxic neonatal chlorpyrifos exposure, devoid of effects on viability or growth but within the parameters of human fetal or neonatal exposures, produce a metabolic pattern for plasma lipids and insulin that resembles the major adult risk factors for atherosclerosis and type 2 diabetes mellitus

Direct Laser Fabrication of a Gas Turbine Engine Component - Microstructure and Properties - Part I

This paper presents the development of a new technique for the production of abrasive turbine blade tips by direct laser processing. This superalloy cermet component is an integral part of the low pressure turbine sealing system in a demonstrator engine. Direct laser fabrication of this component fiom a bed a loose powder results in significant cost savings and improved performance over the currently employed production technique. The technology has been demonstrated by fabricating a prototype lot of 100 blade tips, which will be subjected to an engine test. This is the first instance of a direct fabrication method applied to the production of functional engine hardware. This research was funded by the United States Air Force contract F33615-94- C-2424 titled "Affordable Turbine Blade Tips".Mechanical Engineerin

Dissecting interferon-induced transcriptional programs in human peripheral blood cells

Interferons are key modulators of the immune system, and are central to the control of many diseases. The response of immune cells to stimuli in complex populations is the product of direct and indirect effects, and of homotypic and heterotypic cell interactions. Dissecting the global transcriptional profiles of immune cell populations may provide insights into this regulatory interplay. The host transcriptional response may also be useful in discriminating between disease states, and in understanding pathophysiology. The transcriptional programs of cell populations in health therefore provide a paradigm for deconvoluting disease-associated gene expression profiles.We used human cDNA microarrays to (1) compare the gene expression programs in human peripheral blood mononuclear cells (PBMCs) elicited by 6 major mediators of the immune response: interferons alpha, beta, omega and gamma, IL12 and TNFalpha; and (2) characterize the transcriptional responses of purified immune cell populations (CD4+ and CD8+ T cells, B cells, NK cells and monocytes) to IFNgamma stimulation. We defined a highly stereotyped response to type I interferons, while responses to IFNgamma and IL12 were largely restricted to a subset of type I interferon-inducible genes. TNFalpha stimulation resulted in a distinct pattern of gene expression. Cell type-specific transcriptional programs were identified, highlighting the pronounced response of monocytes to IFNgamma, and emergent properties associated with IFN-mediated activation of mixed cell populations. This information provides a detailed view of cellular activation by immune mediators, and contributes an interpretive framework for the definition of host immune responses in a variety of disease settings

The effects of dyad reading and text difficulty on third-graders’ reading achievement

This study replicated, with modifications, previous research of dyad reading using texts at various levels of difficulty (Morgan, 1997). The current project measured the effects of using above–grade-level texts on reading achievement and sought to determine the influences of dyad reading on both lead and assisted readers. Results indicate that weaker readers, using texts at two, three, and four grade levels above their instructional levels with the assistance of lead readers, outscored both proficient and less proficient students in the control group across multiple measures of reading achievement. However, the gains made by assisted readers were not significantly different relative to the various text levels. When all assessments were considered, assisted readers reading texts two grade levels above their instructional levels showed the most robust gains in oral reading fluency and comprehension. Lead readers also benefited from dyad reading and continued their respective reading developmental trajectories across measures

Ethnic politics and sovereign credit risk

How does domestic politics affect sovereign credit risk? To date, scholars have largely focused on how economic interests along class-cleavages influence sovereign default risk and borrowing costs. Ethnic dynamics are another important political factor that explains governments’ creditworthiness, yet are understudied. We investigate how ethnic politics shape governments’ credit access and argue that the fiscal incentives generated by ethnic coalitions influence credit risk differently than those created by class cleavages. Because ethnic coalitions are usually smaller than class coalitions, left governments with ethnic support can commit to lower spending and receive more favorable risk assessments. Right governments that rely on ethnic support, however, will have greater spending demands because of their need to satisfy ethnic groups. We test our argument using a new indicator of government ethnic support and four indicators of sovereign credit risk. We find that, in emerging markets, the borrowing costs of right governments increase as they become more dependent on ethnic groups for political support. Our findings suggest that financial markets are attuned to multiple dimensions of domestic politics and demonstrate that ethnic divisions can have strong implications for governments’ access to credit

Lethal Mutagenesis of Picornaviruses with N-6-Modified Purine Nucleoside Analogues

RNA viruses exhibit extraordinarily high mutation rates during genome replication. Nonnatural ribonucleosides that can increase the mutation rate of RNA viruses by acting as ambiguous substrates during replication have been explored as antiviral agents acting through lethal mutagenesis. We have synthesized novel N-6-substituted purine analogues with ambiguous incorporation characteristics due to tautomerization of the nucleobase. The most potent of these analogues reduced the titer of poliovirus (PV) and coxsackievirus (CVB3) over 1,000-fold during a single passage in HeLa cell culture, with an increase in transition mutation frequency up to 65-fold. Kinetic analysis of incorporation by the PV polymerase indicated that these analogues were templated ambiguously with increased efficiency compared to the known mutagenic nucleoside ribavirin. Notably, these nucleosides were not efficient substrates for cellular ribonucleotide reductase in vitro, suggesting that conversion to the deoxyriboucleoside may be hindered, potentially limiting genetic damage to the host cell. Furthermore, a high-fidelity PV variant (G64S) displayed resistance to the antiviral effect and mutagenic potential of these analogues. These purine nucleoside analogues represent promising lead compounds in the development of clinically useful antiviral therapies based on the strategy of lethal mutagenesis

Cytolethal Distending Toxin-Induced Cell Cycle Arrest of Lymphocytes is Dependent Upon Recognition and Binding to Cholesterol

Induction of cell cycle arrest in lymphocytes after exposure to the Aggregatibacter actinomycetemcomitans cytolethal distending toxin (Cdt) is dependent upon the integrity of lipid membrane microdomains. In this study we further demonstrate that the association of Cdt with lymphocyte plasma membranes is dependent upon binding to cholesterol. Depletion of cholesterol resulted in reduced toxin binding, whereas repletion of cholesterol-depleted cells restored binding. We employed fluorescence resonance energy transfer and surface plasmon resonance to demonstrate that toxin association with model membranes is dependent upon the concentration of cholesterol; moreover, these interactions were cholesterol-specific as the toxin failed to interact with model membranes containing stigmasterol, ergosterol, or lanosterol. Further analysis of the toxin indicated that the CdtC subunit contains a cholesterol recognition/interaction amino acid consensus (CRAC) region. Mutation of the CRAC site resulted in decreased binding of the holotoxin to cholesterol-containing model membranes as well as to the surface of Jurkat cells. The mutant toxin also exhibited reduced capacity for intracellular transfer of the active toxin subunit, CdtB, as well as reduced toxicity. Collectively, these observations indicate that membrane cholesterol serves as an essential ligand for Cdt and that this association can be blocked by either depleting membranes of cholesterol or mutation of the CRAC site. © 2009 by The American Society for Biochemistry and Molecular Biology, Inc

Potential prognostic marker ubiquitin carboxyl-terminal hydrolase-L1 does not predict patient survival in non-small cell lung carcinoma

<p>Abstract</p> <p>Background</p> <p>Ubiquitin Carboxyl-Terminal Hydrolase-L1 (UCH-L1) is a deubiquitinating enzyme that is highly expressed throughout the central and peripheral nervous system and in cells of the diffuse neuroendocrine system. Aberrant function of UCH-L1 has been associated with neurological disorders such as Parkinson's disease and Alzheimer's disease. Moreover, UCH-L1 exhibits a variable expression pattern in cancer, acting either as a tumour suppressor or promoter, depending on the type of cancer. In non-small cell lung carcinoma primary tumour samples, UCH-L1 is highly expressed and is associated with an advanced tumour stage. This suggests UCH-L1 may be involved in oncogenic transformation and tumour invasion in NSCLC. However, the functional significance of UCH-L1 in the progression of NSCLC is unclear. The aim of this study was to investigate the role of UCH-L1 using NSCLC cell line models and to determine if it is clinically relevant as a prognostic marker for advanced stage disease.</p> <p>Methods</p> <p>UCH-L1 expression in NSCLC cell lines H838 and H157 was modulated by siRNA-knockdown, and the phenotypic changes were assessed by flow cytometry, haematoxylin & eosin (H&E) staining and poly (ADP-ribose) polymerase (PARP) cleavage. Metastatic potential was measured by the presence of phosphorylated myosin light chain (MLC2). Tumour microarrays were examined immunohistochemically for UCH-L1 expression. Kaplan-Meier curves were generated using UCH-L1 expression levels and patient survival data extracted from Gene Expression Omnibus data files.</p> <p>Results</p> <p>Expression of UCH-L1 was decreased by siRNA in both cell lines, resulting in increased cell death in H838 adenocarcinoma cells but not in the H157 squamous cell line. However, metastatic potential was reduced in H157 cells. Immunohistochemical staining of UCH-L1 in patient tumours confirmed it was preferentially expressed in squamous cell carcinoma rather than adenocarcinoma. However the Kaplan-Meier curves generated showed no correlation between UCH-L1 expression levels and patient outcome.</p> <p>Conclusions</p> <p>Although UCH-L1 appears to be involved in carcinogenic processes in NSCLC cell lines, the absence of correlation with patient survival indicates that caution is required in the use of UCH-L1 as a potential prognostic marker for advanced stage and metastasis in lung carcinoma.</p

Membrane Association and Destabilization by Aggregatibacter Actinomycetemcomitans Leukotoxin Requires Changes in Secondary Structures

Aggregatibacter actinomycetemcomitans is a common inhabitant of the upper aerodigestive tract of humans and non-human primates and is associated with disseminated infections, including lung and brain abscesses, pediatric infective endocarditis in children, and localized aggressive periodontitis. A. actinomycetemcomitans secretes a repeats-in-toxin protein, leukotoxin, which exclusively kills lymphocyte function-associated antigen-1-bearing cells. The toxin\u27s pathological mechanism is not fully understood; however, experimental evidence indicates that it involves the association with and subsequent destabilization of the target cell\u27s plasma membrane. We have long hypothesized that leukotoxin secondary structure is strongly correlated with membrane association and/or destabilization. In this study, we tested this hypothesis by analyzing lipid-induced changes in leukotoxin conformation. Upon incubation of leukotoxin with lipids that favor leukotoxin-membrane association, we observed an increase in leukotoxin α-helical content that was not observed with lipids that favor membrane destabilization. The change in leukotoxin conformation after incubation with these lipids suggests that membrane binding and membrane destabilization have distinct secondary structural requirements, suggesting that they are independent events. These studies thus provide insight into the mechanism of cell damage that leads to disease progression by A. actinomycetemcomitans