1,731 research outputs found

    The Effect of Staphylococcus aureus on Stiffness of Cortical Bone

    Get PDF
    Osteomyelitis, a term for bone infection, is a common cause of hospitalization in the United States. Infection leading to osteomyelitis is almost always a product of bacterial origin. Although polymicrobial presence is seen at infection sites of osteomyelitis, Staphylococcus aureus is most commonly isolated and found to be the cause of more than 95% of bone infection in adults. This organism is a common commensal of humans that is carried by an estimated 60% of the US population. S. aureus is transferred by infected asymptomatic individuals, and its ability to proliferate under a variety of environmental conditions contributes to the organism’s role as a pathogen in hosts with compromised immunity. This study examines the effect that infection of Staphylococcus aureus has on cortical bone stiffness. The data collected may be relevant information for bone-graft banks storing donor tissues. A preliminary experiment showed the ability of S. aureus to infect cortical bone by traveling through its porous structure. Frozen, cortical bone samples were thawed, sterilized with alcohol, inoculated with nutrient broth containing S. aureus and then disinfected with chlorhexidine gluconate. Stiffness measurements of each sample were recorded before and after bacterial contamination to allow each sample to serve as its own control. One cube out of every testing batch was not inoculated in bacteria to serve as a control. The results demonstrate that S. aureus infection of bone does not significantly decrease bone stiffness in the axial orientation (p\u3e0.05). In the transverse orientation a significant decrease was observed in the experimental group (

    The tropospheric gas composition of Jupiter's north equatorial belt (NH3, PH3, CH3D, GeH4, H2O) and the Jovian D/H isotropic ratio

    Get PDF
    The gas composition of the troposphere of Jupiter in the clearest regions of the North Equatorial Belt (NEB) was derived from the Voyager 1 IRIS data. The infrared spectrum for this homogeneous cloud free region was modeled to infer altitude profiles for NH3, PH3, GeH4 and H2O. The Profiles for NH3 and PH3 were found to be depleted in the upper troposphere but otherwise in agreement with their solar values at the 1 bar level. The mole fraction for CH3D was determined to be 3.5(+1.0 or -1.3) x 10 to the minus 7th power. The GeH4 mole fraction of 7+ or -2 x 10 to the minus 10th power at the 2 to 3 bar level is a factor of 10 lower than the solar value. The H2O mole fraction is approximately 1 x 0.00001 at the 2.5 bar level and is increasing to approximately 3 x 0.00001 at 4 bars where it is a factor of 30 lower than solar. Using IRIS infrared values for the mole fractions of CH3D and CH4 a value of D/H = 3.6(+1.0 or -1.4)x 0.00001 is derived. Assuming this Jovian D/H ratio is representative of the protosolar nebula, and correcting for chemical galactic evolution, yields a value of 5.5 - 9.0 x 0.00001 for the primordial D/H ratio and an upper limit of 1.8 to 2.4 x 10 to the minus 31st power cu cm for the present day baryon density

    Synaptic MAGUK multimer formation is mediated by PDZ domains and promoted by ligand binding

    Get PDF
    To examine the scaffolding properties of PSD-95, we have taken advantage of established ligand/PDZ domain interactions and developed a cell-based assay for investigating protein complex formation. This assay enables quantitative analysis of PDZ domain-mediated protein clustering using bimolecular fluorescence complementation (BiFC). Two nonfluorescent halves of EYFP were fused to C-terminal PDZ ligand sequences to generate probes that sense for PDZ domain binding grooves of adjacent (interacting) molecules. When these probes are brought into proximity by the PDZ domains of a multiprotein scaffold, a functional fluorescent EYFP molecule can be detected. We have used this system to examine the properties of selected PSD-95 variants and thereby delineated regions of importance for PSD-95 complex formation. Further analysis led to the finding that PSD-95 multimerization is PDZ domain-mediated and promoted by ligand binding

    Sun bear predation on an oriental pied hornbill nest

    Get PDF
    Sun bears (Helarctos malayanus) are opportunistic omnivores that feed predominantly on fruits and invertebrates, but predatory behavior by sun bears is rarely recorded. Although commonly described as a forest-dependent species, the sun bear is a generalist and seems to have some potential to adapt to changing environments. Here we report the first record of a sun bear predating on oriental pied hornbills (Anthracoceros albirostris) in their nest in the Lower Kinabatangan Wildlife Sanctuary in Sabah, Malaysian Borneo, during spring of 2019. It is a human-disturbed landscape surrounded by oil palm (Elaeis guineensis) plantations, with the remaining degraded forest providing a wildlife corridor for Borneo's wildlife. The sun bears photographed by camera traps along the wildlife corridor, including the predatory bear, appeared to be in good condition, therefore evidently finding sufficient food resources. Their opportunistic feeding behavior, not necessarily food shortage, may allow them to take vulnerable prey, such as this low-nesting hornbill
    corecore