67 research outputs found

    HEATING IN VASCULAR TISSUE AND FLOW-THROUGH TISSUE PHANTOMS INDUCED BY FOCUSED ULTRASOUND

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    High intensity focused ultrasound (HIFU) can be used to control bleeding, both from individual blood vessels as well as from gross damage to the capillary bed. This process, called acoustic hemostasis, is being studied in the hope that such a method would ultimately provide a lifesaving treatment during the so-called "golden hour", a brief grace period after a severe trauma in which prompt therapy can save the life of an injured person. Thermal effects play a major role in occlusion of small vessels and also appear to contribute to the sealing of punctures in major blood vessels. However, aggressive ultrasound-induced tissue heating can also impact healthy tissue and can lead to deleterious mechanical bioeffects. Moreover, the presence of vascularity can limit one’s ability to elevate the temperature of blood vessel walls owing to convective heat transport. In an effort to better understand the heating process in tissues with vascular structure we have developed a numerical simulation that couples models for ultrasound propagation, acoustic streaming, ultrasound heating and blood cooling in Newtonian viscous media. The 3-D simulation allows for the study of complicated biological structures and insonation geometries. We have also undertaken a series of in vitro experiments, in non-uniform flow-through tissue phantoms, designed to provide a ground truth verification of the model predictions. The calculated and measured results were compared over a range of values for insonation pressure, insonation time, and flow rate; we show good agreement between predictions and measurements. We then conducted a series of simulations that address two limiting problems of interest: hemostasis in small and large vessels. We employed realistic human tissue properties and considered more complex geometries. Results show that the heating pattern in and around a blood vessel is different for different vessel sizes, flow rates and for varying beam orientations relative to the flow axis. Complete occlusion and wall- puncture sealing are both possible depending on the exposure conditions. These results concur with prior clinical observations and may prove useful for planning of a more effective procedure in HIFU treatments.Defense Advanced Research Projects Agency, the U. S. Army, and the Center for Subsurface Sensing and Imaging Systems

    Receptor-like cytoplasmic kinase ScRIPK in sugarcane regulates disease resistance and drought tolerance in Arabidopsis

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    IntroductionReceptor-like cytoplastic kinases (RLCKs) are known in many plants to be involved in various processes of plant growth and development and regulate plant immunity to pathogen infection. Environmental stimuli such as pathogen infection and drought restrict the crop yield and interfere with plant growth. However, the function of RLCKs in sugarcane remains unclear.Methods and resultsIn this study, a member of the RLCK VII subfamily, ScRIPK, was identified in sugarcane based on sequence similarity to the rice and Arabidopsis RLCKs. ScRIPK was localized to the plasma membrane, as predicted, and the expression of ScRIPK was responsive to polyethylene glycol treatment and Fusarium sacchari infection. Overexpression of ScRIPK in Arabidopsis enhanced drought tolerance and disease susceptibility of seedlings. Moreover, the crystal structure of the ScRIPK kinase domain (ScRIPK KD) and the mutant proteins (ScRIPK-KD K124R and ScRIPK-KD S253A|T254A) were characterized in order to determine the activation mechanism. We also identified ScRIN4 as the interacting protein of ScRIPK.DiscussionOur work identified a RLCK in sugarcane, providing a potential target for sugarcane responses to disease infection and drought, and a structural basis for kinase activation mechanisms

    Complete mitogenome of the Common Koel Eudynamys scolopaceus Linnaeus 1758 (Aves: Cuculidae)

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    The Common Koel Eudynamys scolopaceus Linnaeus 1758, belongs to the family Cuculidae and order Cuculiformes. This omnivorous bird exhibits obligate nest parasitism. Here, the complete mitogenome of E. scolopaceus was determined and phylogenetically compared with those of other Cuculidae species. The newly sequenced complete mitogenome was a circular DNA molecule with a size of 17,610 bp (OM115963). This mitogenome had a higher A + T content (57.58%) than G + C content (42.42%). Phylogenetic analysis revealed that E. scolopaceus was most closely related to Eudynamys taitensis and the genus Cuculus, providing useful molecular information for further research on the phylogeny of the family Cuculidae
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