Transmission of prions from mule deer and elk with chronic wasting disease to transgenic mice expressing cervid PrP

We generated mice expressing cervid prion protein to produce a transgenic system simulating chronic wasting disease (CWD) in deer and elk. While normal mice were resistant to CWD, these transgenic mice uniformly developed signs of neurological dysfunction approximately 230 days following intracerebral inoculation with four CWD isolates. Inoculated transgenic mice homozygous for the transgene array developed disease after approximately 160 days. The brains of sick transgenic mice exhibited widespread spongiform degeneration and contained abnormal prion protein and abundant amyloid plaques, many of which were florid plaques. Transmission studies indicated that the same prion strain caused CWD in the analyzed mule deer and elk. These mice provide a new and reliable tool for detecting CWD prions.     

Toll-like receptor 4-mediated innate IL-10 activates antigen-specific regulatory T cells and confers resistance to Bordetella pertussis by inhibiting inflammatory pathology

Signaling through Toll-like receptors (TLR) activates dendritic cell (DC) maturation and IL-12 production, which directs the induction of Th1 cells. We found that the production of IL-10, in addition to inflammatory cytokines and chemokines, was significantly reduced in DCs from TLR4-defective C3H/HeJ mice in response to Bordetella pertussis. TLR4 was also required for B. pertussis LPS-induced maturation of DCs, but other B. pertussis components stimulated DC maturation independently of TLR4. The course of B. pertussis infection was more severe in C3H/HeJ than in C3H/HeN mice. Surprisingly, Ab- and Ag-specific IFN-gamma responses were enhanced at the peak of infection, whereas Ag-specific IL-10-producing T cells were significantly reduced in C3H/HeJ mice. This was associated with enhanced inflammatory cytokine production, cellular infiltration, and severe pathological changes in the lungs of TLR4-defective mice. Our findings suggest that TLR-4 signaling activates innate IL-10 production in response to B. pertussis, which both directly, and by promoting the induction of IL-10-secreting type 1 regulatory T cells, may inhibit Th1 responses and limit inflammatory pathology in the lungs during infection with B. pertussis.     

High avidity antigen-specific CTL identified by CD8-independent tetramer staining

Tetrameric MHC/peptide complexes are important tools for enumerating, phenotyping, and rapidly cloning Ag-specific T cells. It remains however unclear whether they can reliably distinguish between high and low avidity T cell clones. In this report, tetramers with mutated CD8 binding site selectively stain higher avidity human and murine CTL capable of recognizing physiological levels of Ag. Furthermore, we demonstrate that CD8 binding significantly enhances the avidity as well as the stability of interactions between CTL and cognate tetramers. The use of CD8-null tetramers to identify high avidity CTL provides a tool to compare vaccination strategies for their ability to enhance the frequency of high avidity CTL. Using this technique, we show that DNA priming and vaccinia boosting of HHD A2 transgenic mice fail to selectively expand large numbers of high avidity NY-ESO-1(157-165)-specific CTL, possibly due to the large amounts of antigenic peptide delivered by the vaccinia virus. Furthermore, development of a protocol for rapid identification of high avidity human and murine T cells using tetramers with impaired CD8 binding provides an opportunity not only to monitor expansion of high avidity T cell responses ex vivo, but also to sort high avidity CTL clones for adoptive T cell transfer therapy.     

Negative selection--clearing out the bad apples from the T-cell repertoire

Dead cells are a prominent feature of the thymic landscape as only 5% of developing thymocytes are exported as mature T cells. The remaining thymocytes die by one of two mechanisms; most thymocytes die because they are not positively selected and do not receive a survival signal, whereas a minority of thymocytes undergo T-cell receptor (TCR)-mediated apoptosis, a process known as negative selection. Negative selection is extremely important for establishing a functional immune system, as it provides an efficient mechanism for ridding the T-cell repertoire of self-reactive and potentially autoimmune lymphocytes. This review discusses several cellular and molecular aspects of negative selection.     

The effects of 8 weeks of creatine monohydrate and glutamine supplementation on body composition and performance measures

Twenty-nine (17 men, 12 women) collegiate track and field athletes were randomly divided into a creatine monohydrate (CM, n = 10) group, creatine monohydrate and glutamine (CG, n = 10) group, or placebo (P, n = 9) group. The CM group received 0.3 g creatine.kg body mass per day for 1 week, followed by 0.03 g creatine.kg body mass per day for 7 weeks. The CG group received the same creatine dosage scheme as the CM group plus 4 g glutamine.day(-1). All 3 treatment groups participated in an identical periodized strength and conditioning program during preseason training. Body composition, vertical jump, and cycle performances were tested before (T1) and after (T2) the 8-week supplementation period. Body mass and lean body mass (LBM) increased at a greater rate for the CM and CG groups, compared with the P treatment. Additionally, the CM and CG groups exhibited significantly greater improvement in initial rate of power production, compared with the placebo treatment. These results suggest CM and CG significantly increase body mass, LBM, and initial rate of power production during multiple cycle ergometer bouts.     

Whither biological database research?

We consider how the landscape of biological databases may evolve in the future, and what research is needed to realize this evolution. We suggest today's dispersal of diverse resources will only increase as the number and size of those resources, driving the need for semantic interoperability even more strongly. Because the complexity of the questions biologists want answered automatically continues to rapidly escalate, we will need to draw upon high-performance computing resources such as the GRID to process complex queries. Finally, we still need data, and our ways of acquiring and curating data must improve by orders of magnitude.     

High-resolution magnetic resonance imaging tracks changes in organ and tissue mass in obese and aging rats

Magnetic resonance imaging (MRI) has the ability to discriminate between various soft tissues in vivo. Whole body, specific organ, total adipose tissue (TAT), intra-abdominal adipose tissue (IAAT), and skeletal muscle (SM) weights determined by MRI were compared with weights determined by dissection and chemical analysis in two studies with male Sprague-Dawley rats. A 4.2-T MRI machine acquired high-resolution, in vivo, longitudinal whole body images of rats as they developed obesity or aged. Weights of the whole body and specific tissues were determined using computer image analysis software, including semiautomatic segmentation algorithms for volume calculations. High correlations were found for body weight (r = 0.98), TAT (r = 0.99), and IAAT (r = 0.98) between MRI and dissection and chemical analyses. MRI estimated the weight of the brain, kidneys, and spleen with high accuracy (r > 0.9), but overestimated IAAT, SM, and liver volumes. No differences were detected in organ weights using MRI and dissection measurements. Longitudinal MRI measurements made during the development of obesity and aging accurately represented changes in organ and tissue mass.     

Structure of the C-terminal FG-nucleoporin binding domain of Tap/NXF1

The vertebrate Tap protein is a member of the NXF family of shuttling transport receptors for nuclear export of mRNA. Tap has a modular structure, and its most C-terminal domain is important for binding to FG repeat-containing nuclear pore proteins (FG-nucleoporins) and is sufficient to mediate nuclear shuttling. We report the solution structure of this C-terminal domain, which is based on a distinctive arrangement of four alpha-helices and is joined to the next module by a flexible 12-residue Pro-rich linker. F617A Tap suppresses FG-nucleoporin binding by the most C-terminal domain that, together with the structure of the other modules from which Tap is constructed, provides a structural context for its nuclear shuttling function.