Novel insights into the function and regulation of group X secretory phospholipase A\u3csub\u3e2\u3c/sub\u3e

Group X secretory phospholipase A2 (GX sPLA2) hydrolyzes membrane phospholipids producing free fatty acids and lysophospholipids. Previous studies from our lab suggest that mice with targeted deletion of GX sPLA2 (GX KO) have increased age-related weight gain due to an increase in overall adiposity. Paradoxically, this increased adiposity is associated with improved age-related glucose intolerance. GX KO mice also demonstrate a reduced inflammatory response to lipopolysaccharide injection. In vitro studies indicate this phenotype may be attributable to blunted macrophage mediated inflammatory responses. Given the role of macrophages in promoting adipose tissue (AT) inflammation and metabolic dysfunction in response to diet-induced obesity, we hypothesized that GX KO mice would be protected from the obesity related metabolic derangements associated with overfeeding. Unexpectedly, GX KO mice were only partially protected from high fat (HFD) diet-induced glucose intolerance and showed no improvement in HFD-induced insulin resistance. Moreover, GX KO mice were not protected against HFD-induced AT inflammation. GX sPLA2 is produced as a proenzyme (pro-GX sPLA2), and propeptide cleavage is required for enzymatic activity. Furin-like proprotein convertases (PCs) have recently been implicated in the proteolytic activation of pro-GX sPLA2; however the identity of individual PCs involved is unclear. Previous findings from our lab have shown that GX sPLA2 is expressed in the adrenals where it regulates glucocorticoid production. GX KO mice have increased plasma corticosterone levels under both basal and ACTH-induced stress conditions. However, how GX sPLA2 is regulated in the adrenals is still uncertain. We hypothesized that PCs may be involved in the proteolytic activation of pro-GX sPLA2 in the adrenals. Here we report the novel findings that the PCs, furin and PCSK6, proteolytically activate pro-GX sPLA2 in Y1 adrenal cells. Furthermore, we demonstrate that PC dependent processing of pro-GX sPLA2 is necessary for GX sPLA2 dependent suppression of steroidogenesis. Finally, we provide evidence that pro-GX sPLA2 processing by PCs is enhanced in response to adrenocorticotropic hormone (ACTH), suggesting a novel mechanism for negatively regulating adrenal steroidogenesis. Cumulatively, these studies provide valuable insight into the function and regulation of GX sPLA2

Adaptations of frogs to survive freezing

Five species of frogs from North America survive extensive freezing of their body fluids to temperatures as low as -8C for periods lasting at least 2 weeks. These frogs hibernate in leaf litter where subzero temperatures commonly occur during the winter. The onset of freezing triggers liver glycogenolysis and the production of high concentrations of glucose or glycerol (to 100x normal) that functions as a cryoprotectant against freezing injury. Concomitantly the release of the latent heat of crystallization as body water freezes promotes the continued function of the cardiovascular system for many hours, and serves to distribute glucose throughout the body. The water content of major organs is reduced by 50% or more during the first 24 hours of freezing, with the water being relocated and frozen in other body spaces. Organ dehydration functions to concentrate cryoprotectant and the reduce mechanical damage by ice during freezing. As freezing progresses, breathing, heart beat, and most other vital functions cease, but reanimation occurs within a few hours after thawing. The evolution of freeze tolerance in these animals illustrates the highly flexible capacities of frogs to adapt to stressful environments

Development of an Advanced Recycle Filter Tank Assembly for the ISS Urine Processor Assembly

Recovering water from urine is a process that is critical to supporting larger crews for extended missions aboard the International Space Station. Urine is collected, preserved, and stored for processing into water and a concentrated brine solution that is highly toxic and must be contained to avoid exposure to the crew. The brine solution is collected in an accumulator tank, called a Recycle Filter Tank Assembly (RFTA) that must be replaced monthly and disposed in order to continue urine processing operations. In order to reduce resupply requirements, a new accumulator tank is being developed that can be emptied on orbit into existing ISS waste tanks. The new tank, called the Advanced Recycle Filter Tank Assembly (ARFTA) is a metal bellows tank that is designed to collect concentrated brine solution and empty by applying pressure to the bellows. This paper discusses the requirements and design of the ARFTA as well as integration into the urine processor assembly

The FM-007: An advanced jet commuter for HUB to spoke transportation

Due to the increasing need for new commuter aircraft, the FM-007 is proposed, a technologically advanced jet propelled short takeoff and landing (STOL) airplane. The proposed commuter is designed for hub to spoke air travel. In order to reduce drag, natural laminar flow technology is integrated into the design using the natural laminar flow airfoil section for the wing. A three lifting surface configuration provides for more efficient cruise flight. This unique design includes a small forward wing (canard), a rear mounted high aspect ratio main wing, and a small horizontal stabilizer high atop the vertical tail. These three surfaces act together to reduce drag by minimizing the downward force the horizontal stabilizer has to account for due to the nose down pitching moment. Commuter aircraft must also incorporate passenger comfort. This is achieved by providing a spacious pressurized cabin with a large galley and reduced cabin noise due to incorporation of noise reduction gear. A basic oval design is adopted, as opposed to a circular design in order to allow for the seating of five passengers abreast. To get STOL capability, an over the wing blown flap is used using a Rolls Royce Tay series engine

Generation of representative primary virus isolates from blood plasma after isolation of HIV-1 with CD44 MicroBeads

Infection of cell cultures with cell-free virus isolated from HIV-infected patients is notoriously difficult and results in a loss of viral variation. Here, we describe viral sequences from PBMC, U87.CD4.CCR5 and U87.CD4.CXCR4 cell cultures and compare them to those from blood plasma from 12 patients from whom virus particles were isolated using CD44 MicroBeads. In both PBMC and U87.CD4.CCR5 cultures, 66% of the plasma viral strains were retrieved after culturing. In addition, coreceptor use was predicted based on the env-V3 sequence and tested in U87.CD4 cells expressing either CCR5 or CXCR4. Recovery was lower for the CXCR4-using viruses. Only 50% of the virus clusters predicted to use CXCR4 could be retrieved from cell cultures, while 71% of CCR5-using strains were found in U87.CCR5 cultures. Therefore, isolation of primary viruses with CD44 MicroBeads results in a good representation in cell culture of the in vivo divergence

Protection in Macaques Immunized with HIV-1 Candidate Vaccines Can Be Predicted Using the Kinetics of Their Neutralizing Antibodies

A vaccine is needed to control the spread of human immunodeficiency virus type 1 (HIV-1). An in vitro assay that can predict the protection induced by a vaccine would facilitate the development of such a vaccine. A potential candidate would be an assay to quantify neutralization of HIV-1.We have used sera from rhesus macaques that have been immunized with HIV candidate vaccines and subsequently challenged with simian human immunodeficiency virus (SHIV). We compared neutralization assays with different formats. In experiments with the standardized and validated TZMbl assay, neutralizing antibody titers against homologous SHIV(SF162P4) pseudovirus gave a variable correlation with reductions in plasma viremia levels. The target cells used in the assays are not just passive indicators of virus infection but are actively involved in the neutralization process. When replicating virus was used with GHOST cell assays, events during the absorption phase, as well as the incubation phase, determine the level of neutralization. Sera that are associated with protection have properties that are closest to the traditional concept of neutralization: the concentration of antibody present during the absorption phase has no effect on the inactivation rate. In GHOST assays, events during the absorption phase may inactivate a fixed number, rather than a proportion, of virus so that while complete neutralization can be obtained, it can only be found at low doses particularly with isolates that are relatively resistant to neutralization.Two scenarios have the potential to predict protection by neutralizing antibodies at concentrations that can be induced by vaccination: antibodies that have properties close to the traditional concept of neutralization may protect against a range of challenge doses of neutralization sensitive HIV isolates; a window of opportunity also exists for protection against isolates that are more resistant to neutralization but only at low challenge doses

Impact of resilience enhancing programs on youth surviving the Beslan school siege

The objective of this study was to evaluate a resilience-enhancing program for youth (mean age = 13.32 years) from Beslan, North Ossetia, in the Russian Federation. The program, offered in the summer of 2006, combined recreation, sport, and psychosocial rehabilitation activities for 94 participants, 46 of who were taken hostage in the 2004 school tragedy and experienced those events first hand. Self-reported resilience, as measured by the CD-RISC, was compared within subjects at the study baseline and at two follow-up assessments: immediately after the program and 6 months later. We also compared changes in resilience levels across groups that differed in their traumatic experiences. The results indicate a significant intra-participant mean increase in resilience at both follow-up assessments, and greater self-reported improvements in resilience processes for participants who experienced more trauma events

CP-rays in simplicial cones

An interior point of a triangle is called CP-point if its orthogonal projection on the line containing each side lies in the relative interior of that side. In classical mathematics, interest in the concept of regularity of a triangle is mainly centered on the property of every interior point of the triangle being a CP-point. We generalize the concept of regularity using this property, and extend this work to simplicial cones in ℝ n , and derive necessary and sufficient conditions for this property to hold in them. These conditions highlight the geometric properties of Z-matrices. We show that these concepts have important ramifications in algorithmic studies of the linear complementarity problem. We relate our results to other well known properties of square matrices.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47921/1/10107_2005_Article_BF01582265.pd