Science.gov

Sample records for microcirculation rarefaction precede

  1. Microvascular rarefaction

    PubMed Central

    2010-01-01

    The goals of this presentation are twofold: (1) to briefly sketch the field of vascular rarefaction as a key component of various fibrotic diseases and (2) to illustrate it with four vignettes depicting diverse mechanisms of microvascular rarefaction. Specifically, I shall describe migratory and angiogenic incompetence of endothelial cells under conditions of reduced bioavailability of nitric oxide, role of endothelial-to-mesenchymal cell and mesenchymal stem cell-to-endothelial reprogramming, and potential role of antiangiogenic peptides in the development of graft vascular disease as exemplified by chronic allograft nephropathy PMID:20592859

  2. Microcirculation in pregnancy.

    PubMed

    Abdo, I; George, R B; Farrag, M; Cerny, V; Lehmann, C

    2014-01-01

    The microcirculation, like all physiological systems undergoes modifications during the course of pregnancy. These changes aid the adaption to the new anatomical and physiological environment of pregnancy and ensure adequate oxygen supply to the fetus. Even though the microcirculation is believed to be involved in major pregnancy related pathologies, it remains poorly understood. The availability of safe and non-interventional technologies enabling scientists to study the intact microcirculation of the pregnant patient will hopefully expand our understanding. In this article we review the physiological changes occurring in the microcirculation during pregnancy and the role of the microcirculation in gestational related pathologies. We will also describe the available techniques for the measurement and evaluation of the microcirculation. Lastly we will highlight the possible fields in which these techniques could be utilized to help provide a clearer view of the microcirculation in the pregnant woman.

  3. Rarefaction shock in the near wake

    NASA Technical Reports Server (NTRS)

    Diebold, D.; Hershkowitz, N.; Eliezer, S.

    1987-01-01

    Laboratory experiments and fluid theory find a stationary rarefaction shock in the near wake of an electrically grounded obstacle placed in a steady state, supersonic plasma flow. The shock is only found when two electron temperatures, differing by at least an order of magnitude, are present. These shocks are analogous to rarefaction shocks in plasma free expansions.

  4. Rarefaction solitons initiated by sheath instability

    SciTech Connect

    Levko, Dmitry

    2015-09-15

    The instability of the cathode sheath initiated by the cold energetic electron beam is studied by the one-dimensional fluid model. Numerical simulations show the generation of travelling rarefaction solitons at the cathode. It is obtained that the parameters of these solitons strongly depend on the parameters of electron beam. The “stretched” variables are derived using the small-amplitude analysis. These variables are used in order to obtain the Korteweg-de Vries equation describing the propagation of the rarefaction solitons through the plasma with cold energetic electron beam.

  5. Life and death in the microcirculation: a role for angiotensin II

    NASA Technical Reports Server (NTRS)

    Greene, A. S.; Cowley, A. W. (Principal Investigator)

    1998-01-01

    OBJECTIVE: Angiotensin II (ANGII) plays a critical role in the maintenance of the microcirculation and in the anatomical loss of microvessels (rarefaction) that occurs in low renin forms of hypertension and in animals fed a high-salt diet. Elevations in sodium intake can trigger a series of hemodynamic and hormonal responses culminating in a substantial rarefaction of small arterioles and capillaries in both normal and reduced renal mass hypertensive rats. METHODS: Immunohistochemistry, Northern blot, and reverse transcription-polymerase chain reaction (RT-PCR) analysis of microdissected blood vessels were used to localize ANGII receptors in the microcirculation. Chronic infusion of ANGII and other physiologic and pharmacologic manipulations of the reninangiotensin system in rats was combined with morphologic and mathematical analysis of the network architecture. RESULTS: We have shown that rarefaction of the microcirculation can cause an increase in total peripheral resistance, reduced tissue perfusion, decreased oxygen delivery, and impaired organ function. Although the mechanisms by which this occurs are not well understood, a number of key observations point to a role for the renin-angiotensin system in this effect. First, ANGII infused systemically at subpressor levels, or locally into the skeletal muscle interstitium, can induce significant microvessel growth. Second, localization of ANGII receptor proteins by immunohistochemistry and Western blotting and RNA localization by RT-PCR confirm the presence of AT1 receptors, which are growth-stimulatory, and AT2 receptors, which are growth-inhibitory in the microcirculation. Third, maintenance of ANGII at normal levels during periods of hypertension or high-salt diet completely eliminates rarefaction. CONCLUSIONS: Taken together, these results support the hypothesis that ANGII acting through AT1- and AT2-receptor mechanisms modulate vessel density during high-salt diet and hypertension.

  6. Microcirculation and Hemorheology

    PubMed Central

    Popel, Aleksander S.; Johnson, Paul C.

    2010-01-01

    Major experimental and theoretical studies on microcirculation and hemorheology are reviewed with the focus on mechanics of blood flow and the vascular wall. Flow of the blood formed elements (red blood cells (RBCs), white blood cells or leukocytes (WBCs) and platelets) in individual arterioles, capillaries and venules, and in microvascular networks is discussed. Mechanical and rheological properties of the formed elements and their interactions with the vascular wall are reviewed. Short-term and long-term regulation of the microvasculature is discussed; the modes of regulation include metabolic, myogenic and shear-stress-dependent mechanisms as well as vascular adaptation such as angiogenesis and vascular remodeling. PMID:21151769

  7. Nanotechnology and tumor microcirculation.

    PubMed

    Kano, Mitsunobu R

    2014-07-01

    Though much progress has been made in the development of anti-tumor chemotherapeutic agents, refractoriness is still a major clinical difficulty because little is known about the non-autonomous mechanisms involved. Abnormal capillary structures in tumors, for example, are well documented, but a thorough characterization of microcirculation, including functional consequences with particular regard to drug delivery and intratumor accumulation, is still required for many kinds of tumor. In this review, we highlight how use of synthesized nanoparticles, themselves a product of emerging nanotechnology, are beginning to open up new perspectives in understanding the functional and therapeutic consequences of capillary structure within tumors. Furthermore, nanoparticles promise exciting new clinical applications. I also stress the urgent necessity of developing clinically relevant tumor models, both in vivo and in vitro.

  8. Rarefaction effects on Galileo probe aerodynamics

    NASA Technical Reports Server (NTRS)

    Moss, James N.; LeBeau, Gerald J.; Blanchard, Robert C.; Price, Joseph M.

    1996-01-01

    Solutions of aerodynamic characteristics are presented for the Galileo Probe entering Jupiter's hydrogen-helium atmosphere at a nominal relative velocity of 47.4 km/s. Focus is on predicting the aerodynamic drag coefficient during the transitional flow regime using the direct simulation Monte Carlo (DSMC) method. Accuracy of the probe's drag coefficient directly impacts the inferred atmospheric properties that are being extracted from the deceleration measurements made by onboard accelerometers as part of the Atmospheric Structure Experiment. The range of rarefaction considered in the present study extends from the free molecular limit to continuum conditions. Comparisons made with previous calculations and experimental measurements show the present results for drag to merge well with Navier-Stokes and experimental results for the least rarefied conditions considered.

  9. Rarefaction wave in relativistic steady magnetohydrodynamic flows

    SciTech Connect

    Sapountzis, Konstantinos Vlahakis, Nektarios

    2014-07-15

    We construct and analyze a model of the relativistic steady-state magnetohydrodynamic rarefaction that is induced when a planar symmetric flow (with one ignorable Cartesian coordinate) propagates under a steep drop of the external pressure profile. Using the method of self-similarity, we derive a system of ordinary differential equations that describe the flow dynamics. In the specific limit of an initially homogeneous flow, we also provide analytical results and accurate scaling laws. We consider that limit as a generalization of the previous Newtonian and hydrodynamic solutions already present in the literature. The model includes magnetic field and bulk flow speed having all components, whose role is explored with a parametric study.

  10. Physiopathology of the Cochlear Microcirculation

    PubMed Central

    Shi, Xiaorui

    2011-01-01

    Normal blood supply to the cochlea is critically important for establishing the endocochlear potential and sustaining production of endolymph. Abnormal cochlear microcirculation has long been considered an etiologic factor in noise-induced hearing loss, age-related hearing loss (presbycusis), sudden hearing loss or vestibular function, and Meniere's disease. Knowledge of the mechanisms underlying the pathophysiology of cochlear microcirculation is of fundamental clinical importance. A better understanding of cochlear blood flow (CoBF) will enable more effective management of hearing disorders resulting from aberrant blood flow. This review focuses on recent discoveries and findings related to the physiopathology of the cochlear microvasculature. PMID:21875658

  11. Physiopathology of the cochlear microcirculation.

    PubMed

    Shi, Xiaorui

    2011-12-01

    Normal blood supply to the cochlea is critically important for establishing the endocochlear potential and sustaining production of endolymph. Abnormal cochlear microcirculation has long been considered an etiologic factor in noise-induced hearing loss, age-related hearing loss (presbycusis), sudden hearing loss or vestibular function, and Meniere's disease. Knowledge of the mechanisms underlying the pathophysiology of cochlear microcirculation is of fundamental clinical importance. A better understanding of cochlear blood flow (CoBF) will enable more effective management of hearing disorders resulting from aberrant blood flow. This review focuses on recent discoveries and findings related to the physiopathology of the cochlear microvasculature.

  12. Blood microcirculation of ischemic pancreatitis

    NASA Astrophysics Data System (ADS)

    Dmitrieva, Irina V.; Arakelian, Sergei M.; Antonov, Olga V.

    1998-06-01

    Blood Microcirculation includes many of different components, which are joined by unique multiple system. Capillaries are one of the main link in this morpho-functional chain. Changes in any components of blood microcirculation are revealed by many of pathological processes in different organs and systems of the whole organism. We investigated 250 patients from 30 to 77 ages. Men included 149, women -- 101. The main diagnosis of all patients was the ischaemic pancreatitis. For verification of this diagnosis we used the whole spectrum of clinical, laboratorial and instrumental methods. These were the following: the definition of amylase of blood and urine, sonography and computer's tomography of pancreas, angiography of vessels of pancreas and Doppler's sonography of abdominal aorta and her branches: arteria mesenterica superior (AMS), truncus coeliacus (TC), arteria hepatica communis (AHC) and arteria lienalis (AL). We investigated the blood microcirculation of the mucous of the inferior lip, using Laser Dopplerography. The equipment for this research was LACC-01 with modified computer's program. The normal levels of blood microcirculation were from 120 to 180 Units. But patients with ischaemic pancreatitis had more lower level than in normal situation. This method are suggested as express diagnostic in the cases of abdominal ischaemic pathology. It can used as singel method or in combined with ultrasound Dopplerography.

  13. Magnetic instability in a dilute circular rarefaction wave

    SciTech Connect

    Dieckmann, M. E.; Sarri, G.; Borghesi, M.

    2012-12-15

    The growth of magnetic fields in the density gradient of a rarefaction wave has been observed in simulations and in laboratory experiments. The thermal anisotropy of the electrons, which gives rise to the magnetic instability, is maintained by the ambipolar electric field. This simple mechanism could be important for the magnetic field amplification in astrophysical jets or in the interstellar medium ahead of supernova remnant shocks. The acceleration of protons and the generation of a magnetic field by the rarefaction wave, which is fed by an expanding circular plasma cloud, is examined here in form of a 2D particle-in-cell simulation. The core of the plasma cloud is modeled by immobile charges, and the mobile protons form a small ring close to the cloud's surface. The number density of mobile protons is thus less than that of the electrons. The protons of the rarefaction wave are accelerated to 1/10 of the electron thermal speed, and the acceleration results in a thermal anisotropy of the electron distribution in the entire plasma cloud. The instability in the rarefaction wave is outrun by a TM wave, which grows in the dense core distribution, and its magnetic field expands into the rarefaction wave. This expansion drives a secondary TE wave.

  14. Integrative physiology of coronary microcirculation.

    PubMed

    Kajiya, F; Goto, M

    1999-06-01

    Coronary microvessels play a crucial role for mechanoenergetic interaction between blood flow and myocardial function, which is not uniform transmurally. Thus, highly organized vascular regulations are required for matching local blood flow with myocardial energy requirement. Recently, new technologies to investigate in vivo coronary microcirculation with new knowledge of the signaling molecules for vascular regulation have revolutionized our abilities to understand the integrative regulation of coronary microcirculation. In this review, the mechanical aspects of the interaction between coronary blood flow and myocardium, coronary arte-rial tree and its roles in myocardial blood flow regulation, hierarchical and dynamic control of coronary flow, capillary network and function, function of venous drainage system, and molecular and cellular aspects of integrative coronary blood flow regulation are discussed, focusing on their integrational roles in maintaining coronary microvascular function and cell signaling.

  15. [Methods of studying the microcirculation].

    PubMed

    Shagal, D I; Tsvik, A I; Razygrin, B A

    1980-01-01

    The article shows possibilities of thermography in the study of peripheral blood circulation. Data are presented on examining the patients with diverse pathology forms by means of conjunctival biomicroscopy and television capillaroscopy of the nail bed. Evaluation of these methods and analysis of the data obtained are presented. The authors believe in more extended possibilities of applying microcirculation study methods together with thermography for disclosure of some diseases. PMID:7402036

  16. Formation of rarefaction waves in origami-based metamaterials.

    PubMed

    Yasuda, H; Chong, C; Charalampidis, E G; Kevrekidis, P G; Yang, J

    2016-04-01

    We investigate the nonlinear wave dynamics of origami-based metamaterials composed of Tachi-Miura polyhedron (TMP) unit cells. These cells exhibit strain softening behavior under compression, which can be tuned by modifying their geometrical configurations or initial folded conditions. We assemble these TMP cells into a cluster of origami-based metamaterials, and we theoretically model and numerically analyze their wave transmission mechanism under external impact. Numerical simulations show that origami-based metamaterials can provide a prototypical platform for the formation of nonlinear coherent structures in the form of rarefaction waves, which feature a tensile wavefront upon the application of compression to the system. We also demonstrate the existence of numerically exact traveling rarefaction waves in an effective lumped-mass model. Origami-based metamaterials can be highly useful for mitigating shock waves, potentially enabling a wide variety of engineering applications.

  17. Characterization of rarefaction waves in van der Waals fluids.

    PubMed

    Yuen, Albert; Barnard, John J

    2015-12-01

    We calculate the isentropic evolution of an instantaneously heated foil, assuming a van der Waals equation of state with the Maxwell construction. The analysis by Yuen and Barnard [Phys. Rev. E 92, 033019 (2015)] is extended for the particular case of three degrees of freedom. We assume heating to temperatures in the vicinity of the critical point. The self-similar profiles of the rarefaction waves describing the evolution of the foil display plateaus in density and temperature due to a phase transition from the single-phase to the two-phase regime. The hydrodynamic equations are expressed in a dimensionless form and the solutions form a set of universal curves, depending on a single parameter: the dimensionless initial entropy. We characterize the rarefaction waves by calculating how the plateau length, density, pressure, temperature, velocity, internal energy, and sound speed vary with dimensionless initial entropy. PMID:26764692

  18. Formation of rarefaction waves in origami-based metamaterials

    DOE PAGESBeta

    Yasuda, H.; Chong, C.; Charalampidis, E. G.; Kevrekidis, P. G.; Yang, J.

    2016-04-15

    Here, we investigate the nonlinear wave dynamics of origami-based metamaterials composed of Tachi-Miura polyhedron (TMP) unit cells. These cells exhibit strain softening behavior under compression, which can be tuned by modifying their geometrical configurations or initial folded conditions. We assemble these TMP cells into a cluster of origami-based metamaterials, and we theoretically model and numerically analyze their wave transmission mechanism under external impact. Numerical simulations show that origami-based metamaterials can provide a prototypical platform for the formation of nonlinear coherent structures in the form of rarefaction waves, which feature a tensile wavefront upon the application of compression to the system.more » We also demonstrate the existence of numerically exact traveling rarefaction waves in an effective lumped-mass model. Origami-based metamaterials can be highly useful for mitigating shock waves, potentially enabling a wide variety of engineering applications.« less

  19. Formation of rarefaction waves in origami-based metamaterials.

    PubMed

    Yasuda, H; Chong, C; Charalampidis, E G; Kevrekidis, P G; Yang, J

    2016-04-01

    We investigate the nonlinear wave dynamics of origami-based metamaterials composed of Tachi-Miura polyhedron (TMP) unit cells. These cells exhibit strain softening behavior under compression, which can be tuned by modifying their geometrical configurations or initial folded conditions. We assemble these TMP cells into a cluster of origami-based metamaterials, and we theoretically model and numerically analyze their wave transmission mechanism under external impact. Numerical simulations show that origami-based metamaterials can provide a prototypical platform for the formation of nonlinear coherent structures in the form of rarefaction waves, which feature a tensile wavefront upon the application of compression to the system. We also demonstrate the existence of numerically exact traveling rarefaction waves in an effective lumped-mass model. Origami-based metamaterials can be highly useful for mitigating shock waves, potentially enabling a wide variety of engineering applications. PMID:27176382

  20. Characterization of rarefaction waves in van der Waals fluids

    NASA Astrophysics Data System (ADS)

    Yuen, Albert; Barnard, John J.

    2015-12-01

    We calculate the isentropic evolution of an instantaneously heated foil, assuming a van der Waals equation of state with the Maxwell construction. The analysis by Yuen and Barnard [Phys. Rev. E 92, 033019 (2015), 10.1103/PhysRevE.92.033019] is extended for the particular case of three degrees of freedom. We assume heating to temperatures in the vicinity of the critical point. The self-similar profiles of the rarefaction waves describing the evolution of the foil display plateaus in density and temperature due to a phase transition from the single-phase to the two-phase regime. The hydrodynamic equations are expressed in a dimensionless form and the solutions form a set of universal curves, depending on a single parameter: the dimensionless initial entropy. We characterize the rarefaction waves by calculating how the plateau length, density, pressure, temperature, velocity, internal energy, and sound speed vary with dimensionless initial entropy.

  1. Characterization of rarefaction waves in van der Waals fluids.

    PubMed

    Yuen, Albert; Barnard, John J

    2015-12-01

    We calculate the isentropic evolution of an instantaneously heated foil, assuming a van der Waals equation of state with the Maxwell construction. The analysis by Yuen and Barnard [Phys. Rev. E 92, 033019 (2015)] is extended for the particular case of three degrees of freedom. We assume heating to temperatures in the vicinity of the critical point. The self-similar profiles of the rarefaction waves describing the evolution of the foil display plateaus in density and temperature due to a phase transition from the single-phase to the two-phase regime. The hydrodynamic equations are expressed in a dimensionless form and the solutions form a set of universal curves, depending on a single parameter: the dimensionless initial entropy. We characterize the rarefaction waves by calculating how the plateau length, density, pressure, temperature, velocity, internal energy, and sound speed vary with dimensionless initial entropy.

  2. [Microcirculation of optic nerve head and glaucoma].

    PubMed

    Zhang, S H; Zhao, J L; Wu, C

    2016-06-11

    Glaucoma is a leading cause of irreversible blindness world widely. The pathogenesis of glaucoma is still not fully understood. It is proposed that the microcirculation of optic nerve head (ONH) may play an important role in glaucomatous optic neuropathy, but the hypothesis is still lack of direct evidence. In this review, we summarized the technical developments in ONH blood flow examination and findings on relationship between decreased ONH microcirculation and glaucoma. These evidences implicate that damaged ONH microcirculation involves in pathogenesis of glaucoma. (Chin J Ophthalmol, 2016, 52: 466-470). PMID:27373574

  3. EFFECT OF INTERACTING RAREFACTION WAVES ON RELATIVISTICALLY HOT JETS

    SciTech Connect

    Matsumoto, Jin; Shibata, Kazunari; Masada, Youhei

    2012-06-01

    The effect of rarefaction acceleration on the propagation dynamics and structure of relativistically hot jets is studied through relativistic hydrodynamic simulations. We emphasize the nonlinear interaction of rarefaction waves excited at the interface between a cylindrical jet and the surrounding medium. From simplified one-dimensional (1D) models with radial jet structure, we find that a decrease in the relativistic pressure due to the interacting rarefaction waves in the central zone of the jet transiently yields a more powerful boost of the bulk jet than that expected from single rarefaction acceleration. This leads to a cyclic in situ energy conversion between thermal and bulk kinetic energies, which induces radial oscillating motion of the jet. The oscillation timescale is characterized by the initial pressure ratio of the jet to the ambient medium and follows a simple scaling relation, {tau}{sub oscillation}{proportional_to}(P{sub jet,0}/P{sub amb,0}){sup 1/2}. Extended two-dimensional simulations confirm that this radial oscillating motion in the 1D system manifests as modulation of the structure of the jet in a more realistic situation where a relativistically hot jet propagates through an ambient medium. We find that when the ambient medium has a power-law pressure distribution, the size of the reconfinement region along the propagation direction of the jet in the modulation structure {lambda} evolves according to a self-similar relation {lambda}{proportional_to}t{sup {alpha}/2}, where {alpha} is the power-law index of the pressure distribution.

  4. A RECONNECTION-DRIVEN RAREFACTION WAVE MODEL FOR CORONAL OUTFLOWS

    SciTech Connect

    Bradshaw, S. J.; Aulanier, G.; Del Zanna, G.

    2011-12-10

    We conduct numerical experiments to determine whether interchange reconnection at high altitude coronal null points can explain the outflows observed as blueshifts in coronal emission lines at the boundaries between open and closed magnetic field regions. In this scenario, a strong, post-reconnection pressure gradient forms in the field-aligned direction when dense and hot, active region core loops reconnect with neighboring tenuous and cool, open field lines. We find that the pressure gradient drives a supersonic outflow and a rarefaction wave develops in both the open and closed post-reconnection magnetic field regions. We forward-model the spectral line profiles for a selection of coronal emission lines to predict the spectral signatures of the rarefaction wave. We find that the properties of the rarefaction wave are consistent with the observed velocity versus temperature structure of the corona in the outflow regions, where the velocity increases with the formation temperature of the emission lines. In particular, we find excellent agreement between the predicted and observed Fe XII 195.119 A spectral line profiles in terms of the blueshift (10 km s{sup -1}), full width at half-maximum (83 mA) and symmetry. Finally, we find that T{sub i} < T{sub e} in the open field region, which indicates that the interchange reconnection scenario may provide a viable mechanism and source region for the slow solar wind.

  5. [Endothelial function and the microcirculation in diabetes mellitus].

    PubMed

    Arosio, E; Minuz, P; Prior, M

    1999-01-01

    The role of endothelial dysfunction in the pathogenesis of diabetic microangiopathy is reviewed. Reversible alterations in microcirculation, consisting of increased capillary pressure, blood flow and endothelial permeability, can be detected at an early stage in diabetes mellitus. Irreversible structural modifications of the vascular wall, such as thickening of the basal membrane due to the extracellular accumulation of proteins, take place at later stages. Atherosclerosis further affects microcirculation in diabetes mellitus by decreasing autoregulatory capacity and blood flow reserve. Endothelial dysfunction has been observed to precede the onset of microvascular lesions, as demonstrated by reduction in the vasodilatory response to vasoactive agents and by alterations in the antithrombotic properties of the endothelium. Experimental data available so far suggest that endothelial dysfunction may be directly related to hyperglycemia. Abnormalities in lipoprotein metabolism, generation of glycation end products, and increased oxidative stress may also be responsible for the endothelial dysfunction in diabetes mellitus. Insulin resistance appears to be related to endothelial dysfunction in non-insulin-dependent diabetes mellitus through a reduction in the biological activity of endothelial-derived nitric oxide.

  6. Effect of hypokinesia on blood microcirculation

    NASA Technical Reports Server (NTRS)

    Chernukh, A. M.; Gazenko, O. G.; Fedorov, B. M.; Krupina, T. N.; Aleksandrov, P. N.; Shagal, D. I.; Ranferova, N. Y.; Proskurina, T. N.

    1980-01-01

    Blood microcirculation in the region of the scleral bulbar conjunctiva and the nail folds on the fingers and toes was studied in 18 practically healthy men during 182 day antiorthostatic hypokinesia and 30 day rehabilitation period. Marked changes in microcirculation in the sclera and feet and less evident changes on the hands was revealed. A complex of special prophylactic physical exercises had a distinctly favorable effect on circulation in the hands.

  7. [Cardiac function and the skin microcirculation in acromegaly].

    PubMed

    Bach, R; Leicht, E; Langer, H J; Hartenstein, R; Jung, F; Berg, G; Schätzer-Klotz, D; Bonaventura, K; Schieffer, H; Weinges, K F

    1992-03-27

    The microcirculation was measured by nail-fold capillary video microscopy in 21 patients (12 men, 9 women; mean age 54.7 [29-74] years) with acromegaly. Levels of growth hormone (12.0-71.7 microU/ml) and of somatomedin C (2.4-10.5 IU/ml) were elevated in 10 patients, despite preceding treatment. Eleven patients had an increase in myocardial thickness and nine had impairment of left ventricular function, although only slight in most. Left ventricular hypertrophy was demonstrable even in the absence of hypertension. No patient had evidence of coronary heart disease. Nail-fold capillary video microscopy (capillary density, torque index, reactive hyperaemia, epidermal blood flow) failed to distinguish between successfully treated patients and those with persistently elevated growth hormone concentrations or disease duration of over 5 years. There was no evidence of inadequate capillary blood flow as a cause of abnormal function in hypertrophied organs.

  8. Asymptotic stability of rarefaction waves for 2 ∗ 2 viscous hyperbolic conservation laws

    NASA Astrophysics Data System (ADS)

    Xin, Zhouping

    This paper concerns the asymptotic behavior toward rarefaction waves of the solution of a general 2 × 2 hyperbolic conservation laws with positive viscosity. We prove that if the initial data is close to a constant state and its values at ±∞ lie on the kth rarefaction curve for the corresponding hyperbolic conservation laws, then the solution tends as t → ∞ to the rarefaction wave determined by these states.

  9. PRECEDE for Wellness.

    ERIC Educational Resources Information Center

    Bonaguro, John A.

    1981-01-01

    The PRECEDE model was developed for health educators in an effort to improve programs and to influence health behaviors. The model consists of several diagnostic phases: (1) epidemiological; (2) social; (3) behavioral; (4) educational; (5) administrative; and (6) evaluation. (JN)

  10. Rarefaction shock waves in shock-compressed diamond <110> crystal

    NASA Astrophysics Data System (ADS)

    Perriot, Romain; Lin, You; Zhakhovsky, Vasily; White, Carter; Oleynik, Ivan

    2013-03-01

    Piston-driven shock compression of diamond <110> crystal was simulated by molecular dynamics using the REBO potential. At piston velocities between 2 and 5 km/s and corresponding pressures 117 GPA < P < 278 GPa, diamond sample undergoes a polymorphic phase transition, characterized by the coexistence of two elastically compressed phases, low-pressure phase A and high-pressure phase B. This phase transition results in the splitting of the shock wave into two elastic shock waves, composed of pure phase A and a mixture of phases A and B. Upon removal of the piston, a release wave is observed at the rear of the sample, turning into a rarefaction shock wave where the material undergoes the reverse phase transition from coexisting phases to the original low-pressure phase. For strong plastic waves induced by larger piston velocities the release wave propagates as a rarefaction wave without any phase transition corresponding to the adiabatic expansion along the plastic branch of the Hugoniot.

  11. Reshocks, rarefactions, and the generalized Layzer model for hydrodynamic instabilities

    SciTech Connect

    Mikaelian, K O

    2008-06-10

    We report numerical simulations and analytic modeling of shock tube experiments on Rayleigh-Taylor and Richtmyer-Meshkov instabilities. We examine single interfaces of the type A/B where the incident shock is initiated in A and the transmitted shock proceeds into B. Examples are He/air and air/He. In addition, we study finite-thickness or double-interface A/B/A configurations like air/SF{sub 6}/air gas-curtain experiments. We first consider conventional shock tubes that have a 'fixed' boundary: A solid endwall which reflects the transmitted shock and reshocks the interface(s). Then we focus on new experiments with a 'free' boundary--a membrane disrupted mechanically or by the transmitted shock, sending back a rarefaction towards the interface(s). Complex acceleration histories are achieved, relevant for Inertial Confinement Fusion implosions. We compare our simulation results with a generalized Layzer model for two fluids with time-dependent densities, and derive a new freeze-out condition whereby accelerating and compressive forces cancel each other out. Except for the recently reported failures of the Layzer model, the generalized Layzer model and hydrocode simulations for reshocks and rarefactions agree well with each other, and remain to be verified experimentally.

  12. Microcirculation Perfusion Monitor on the Back of the Health Volunteers

    PubMed Central

    Li, Yanqi; Li, Xiaomei; Zhou, Dan; Wang, Kang; Liu, Yangyang; Guo, Yi; Qiu, Shuang; Zhai, Tianchen; Liu, Shuang; Liu, Jingjing; Ming, Dong

    2013-01-01

    Objective. To observe the dermal microcirculation blood perfusion characterization of meridians channels (acupoints). Methods. 20 healthy human subjects were monitored using Pericam Perfusion Speckle Imager (PSI) for the changes in dermal microcirculation blood perfusion on governor meridian and other respective dermal regions as a control. Result. The microcirculation blood perfusion on Governor Meridian is higher than its control area. Conclusion. The dermal microcirculation blood perfusion on certain parts of Governor Meridian of healthy human subjects showed specifics. PMID:24371463

  13. Nitric Oxide Signaling in the Microcirculation

    PubMed Central

    Buerk, Donald G.; Barbee, Kenneth A.; Jaron, Dov

    2013-01-01

    Several apparent paradoxes are evident when one compares mathematical predictions from models of nitric oxide (NO) diffusion and convection in vasculature structures with experimental measurements of NO (or related metabolites) in animal and human studies. Values for NO predicted from mathematical models are generally much lower than in vivo NO values reported in the literature for experiments, specifically with NO microelectrodes positioned at perivascular locations next to different sizes of blood vessels in the microcirculation and NO electrodes inserted into a wide range of tissues supplied by the microcirculation of each specific organ system under investigation. There continues to be uncertainty about the roles of NO scavenging by hemoglobin versus a storage function that may conserve NO, and other signaling targets for NO need to be considered. This review describes model predictions and relevant experimental data with respect to several signaling pathways in the microcirculation that involve NO. PMID:22196161

  14. Cerebral Microcirculation during Experimental Normovolaemic Anemia

    PubMed Central

    Bellapart, Judith; Cuthbertson, Kylie; Dunster, Kimble; Diab, Sara; Platts, David G.; Raffel, O. Christopher; Gabrielian, Levon; Barnett, Adrian; Paratz, Jenifer; Boots, Rob; Fraser, John F.

    2016-01-01

    Anemia is accepted among critically ill patients as an alternative to elective blood transfusion. This practice has been extrapolated to head injury patients with only one study comparing the effects of mild anemia on neurological outcome. There are no studies quantifying microcirculation during anemia. Experimental studies suggest that anemia leads to cerebral hypoxia and increased rates of infarction, but the lack of clinical equipoise, when testing the cerebral effects of transfusion among critically injured patients, supports the need of experimental studies. The aim of this study was to quantify cerebral microcirculation and the potential presence of axonal damage in an experimental model exposed to normovolaemic anemia, with the intention of describing possible limitations within management practices in critically ill patients. Under non-recovered anesthesia, six Merino sheep were instrumented using an intracardiac transeptal catheter to inject coded microspheres into the left atrium to ensure systemic and non-chaotic distribution. Cytometric analyses quantified cerebral microcirculation at specific regions of the brain. Amyloid precursor protein staining was used as an indicator of axonal damage. Animals were exposed to normovolaemic anemia by blood extractions from the indwelling arterial catheter with simultaneous fluid replacement through a venous central catheter. Simultaneous data recording from cerebral tissue oxygenation, intracranial pressure, and cardiac output was monitored. A regression model was used to examine the effects of anemia on microcirculation with a mixed model to control for repeated measures. Homogeneous and normal cerebral microcirculation with no evidence of axonal damage was present in all cerebral regions, with no temporal variability, concluding that acute normovolaemic anemia does not result in short-term effects on cerebral microcirculation in the ovine brain. PMID:26869986

  15. Rarefaction and blood pressure in systemic and pulmonary arteries.

    PubMed

    Olufsen, Mette S; Hill, N A; Vaughan, Gareth D A; Sainsbury, Christopher; Johnson, Martin

    2012-08-01

    The effects of vascular rarefaction (the loss of small arteries) on the circulation of blood are studied using a multiscale mathematical model that can predict blood flow and pressure in the systemic and pulmonary arteries. We augmented a model originally developed for the systemic arteries (Olufsen et al. 1998, 1999, 2000, 2004) to (a) predict flow and pressure in the pulmonary arteries, and (b) predict pressure propagation along the small arteries in the vascular beds. The systemic and pulmonary arteries are modelled as separate, bifurcating trees of compliant and tapering vessels. Each tree is divided into two parts representing the `large' and `small' arteries. Blood flow and pressure in the large arteries are predicted using a nonlinear cross-sectional area-averaged model for a Newtonian fluid in an elastic tube with inflow obtained from magnetic resonance measurements. Each terminal vessel within the network of the large arteries is coupled to a vascular bed of small `resistance' arteries, which are modelled as asymmetric structured trees with specified area and asymmetry ratios between the parent and daughter arteries. For the systemic circulation, each structured tree represents a specific vascular bed corresponding to major organs and limbs. For the pulmonary circulation, there are four vascular beds supplied by the interlobar arteries. This manuscript presents the first theoretical calculations of the propagation of the pressure and flow waves along systemic and pulmonary large and small arteries. Results for all networks were in agreement with published observations. Two studies were done with this model. First, we showed how rarefaction can be modelled by pruning the tree of arteries in the microvascular system. This was done by modulating parameters used for designing the structured trees. Results showed that rarefaction leads to increased mean and decreased pulse pressure in the large arteries. Second, we investigated the impact of decreasing vessel

  16. Cardiovascular risk factors cause premature rarefaction of the collateral circulation and greater ischemic tissue injury

    PubMed Central

    Moore, Scott M.; Zhang, Hua; Maeda, Nobuyo; Doerschuk, Claire M.; Faber, James E.

    2015-01-01

    Rationale Collaterals lessen tissue injury in occlusive disease. However, aging causes progressive decline in their number and smaller diameters in those that remain (collateral rarefaction), beginning at 16 months-age in mice (ie, middle age), and worse ischemic injury—effects that are accelerated in even 3 months-old eNOS−/− mice. These findings have found indirect support in recent human studies. Objective We sought to determine if other cardiovascular risk factors (CVRFs) associated with endothelial dysfunction cause collateral rarefaction, investigate possible mechanisms, and test strategies for prevention. Methods and Results Mice with nine different models of CVRFs of 4–12 months-age were assessed for number and diameter of native collaterals in skeletal muscle and brain, and for collateral-dependent perfusion and ischemic injury after arterial occlusion. Hypertension caused collateral rarefaction whose severity increased with duration and level of hypertension, accompanied by greater hindlimb ischemia and cerebral infarct volume. Chronic treatment of wildtype mice with L-NG-nitro-arginine methylester caused similar rarefaction and worse ischemic injury that were not prevented by lowering arterial pressure with hydralazine. Metabolic syndrome, hypercholesterolemia, diabetes mellitus, and obesity also caused collateral rarefaction. Neither chronic statin treatment nor exercise training lessened hypertension-induced rarefaction. Conclusion Chronic CVRF presence caused collateral rarefaction and worse ischemic injury, even at relatively young ages. Rarefaction was associated with increased proliferation rate of collateral endothelial cells, effects that may promote accelerated endothelial cell senescence. PMID:25862671

  17. Asymptotic Stability of Planar Rarefaction Waves for the Relaxation Approximation of Conservation Laws in Several Dimensions

    NASA Astrophysics Data System (ADS)

    Luo, Tao

    1997-01-01

    This paper concerns the large time behavior toward planar rarefaction waves of solutions for the relaxation approximation of conservation laws in several dimensions. It is shown that a planar rarefaction wave is nonlinear stable in the sense that it is an asymptotic attractor for the relaxation approximation of conservation laws.

  18. Dis-ease or disease?: ontological rarefaction in the medical-industrial complex.

    PubMed

    Graham, S Scott

    2011-09-01

    Recent scholarship in medical humanities has expressed strong concern over the ability of pharmaceuticals companies to medicalize discomfort and subsequently invent diseases. In this article, I explore the clinical debates over the ontology of the sinus headache as a possible counter-case. Extending Foucault's concept of principles or rarefaction, this paper documents the efforts of clinicians to resist the pharmaceutically-provided understanding of the sinus headache. In so doing, it offers institutions of rarefaction and rarefactive assemblages as useful heuristics for the exploration of disease legitimization discourse. PMID:21484314

  19. Condensation of water vapor in rarefaction waves. I - Homogeneous nucleation

    NASA Technical Reports Server (NTRS)

    Sislian, J. P.; Glass, I. I.

    1976-01-01

    A detailed theoretical investigation has been made of the condensation of water vapor/carrier gas mixtures in the nonstationary rarefaction wave generated in a shock tube. It is assumed that condensation takes place by homogeneous nucleation. The equations of motion together with the nucleation rate and the droplet growth equations were solved numerically by the method of characteristics and Lax's method of implicit artificial viscosity. It is found that, for the case considered, the condensation wave formed by the collapse of the metastable nonequilibrium state is followed by a shock wave generated by the intersection of characteristics of the same family. The expansion is practically isentropic up to the onset of condensation. The condensation front accelerates in the x,t plane. The results of the computations for a chosen case of water vapor/nitrogen mixture are presented by plotting variations of pressure, nucleation rate, number density of critical clusters, and condensate mass-fraction along three particle paths. Some consideration is given to homogeneous condensation experiments conducted in a shock tube. Although a direct comparison of the present theoretical work and these experiments is not possible, several worthwhile interpretative features have resulted nevertheless.

  20. Propagation of rarefaction pulses in particulate materials with strain-softening behavior

    SciTech Connect

    Herbold, E B; Nesterenko, V F

    2011-07-29

    We investigate rarefaction waves in nonlinear periodic systems with a 'softening' power-law relationship between force and displacement to understand the dynamic behavior of this class of materials. A closed form expression describing the shape of the strongly nonlinear rarefaction wave is exact for n = 1/2 and agrees well with the shape and width of the pulses resulting from discrete simulations. A chain of particles under impact was shown to propagate a rarefaction pulse as the leading pulse in initially compressive impulsive loading in the absence of dissipation. Compression pulses generated by impact quickly disintegrated into a leading rarefaction solitary wave followed by an oscillatory train. Such behavior is favorable for metamaterials design of shock absorption layers as well as tunable information transmission lines for scrambling of acoustic information.

  1. Shock and Rarefaction Waves in a Heterogeneous Mantle

    NASA Astrophysics Data System (ADS)

    Jordan, J.; Hesse, M. A.

    2012-12-01

    has a zero eigenvalue, corresponding to a wave speed of zero, which preserves a residual imprint of the initial condition. Freezing fronts textemdash those that result in a negative change in porositytextemdash feature fast path waves that travel as shocks, whereas the fast path waves of melting fronts travel as spreading, rarefaction waves.

  2. Superficial microcirculation flow measurement using polarized light

    NASA Astrophysics Data System (ADS)

    Wu, Jiwei; Morgan, S. P.; Xiao, Yunshi

    2008-12-01

    Depth discrimination of polarized light is used in investigating laser Doppler measurement of the superficial microcirculation in tissue. Using polarization Monte Carlo simulation, temporal point spread function and power spectral distribution of backscattered polarization remaining light firstly are used to prove polarized light to be valid in measuring moving blood cell perfusion and mean flow velocity. Then simulation of layered medium model demonstrate that relationships between blood flow perfusion and mean frequency shift are linear to medium flowing velocity, and the Doppler shift information in polarization remaining light mainly comes from lower layer medium up to about 14 times of mean free path (MFP) of medium investigated and can be considered that Doppler effects come only from lower layer of the medium. Simulations in three-layer tissue model show that moving blood cell perfusion and mean blood cell moving velocity calculated from polarization remaining are much more sensitive to lower layer flow velocity variation, and more irrelevant to deeper layer flow rate fluctuations, that further confirms Doppler measurement from polarization remaining light to be effective for superficial microcirculation in tissue. Factors affecting Laser Doppler measurement like medium absorption, percentage of moving particles in blood detector size are discussed.

  3. Numerical Investigation into the Performance of a Rarefaction Shock Wave Cutter for Offshore Oil-Gas Platform Removal

    SciTech Connect

    Morris, J P; Glenn, L A; Antoun, T H; Lomov, I N

    2001-06-14

    The phase change in iron at 13 GPa results in the formation of rarefaction shock waves upon release. The interaction of multiple rarefaction shock waves induces high tensile stresses within a narrow zone, causing smooth spall. This effect can be exploited to sever cylindrical cross-section pipes, such as those supporting decommissioned offshore oil and gas platforms, using a minimal amount of explosive. Consequently, costs can be reduced and environmental impact minimized. They discuss the numerical techniques used to simulate rarefaction shock waves and the damage to steel resulting from the interaction of multiple rarefaction shock waves.

  4. Compressive and rarefactive solitary waves in nonthermal two-component plasmas

    SciTech Connect

    Verheest, Frank; Hellberg, Manfred A.

    2010-10-15

    Using a Sagdeev pseudopotential formalism where nonlinear structures are stationary in a comoving frame, large ion-acoustic solitary waves and double layers have been studied in plasmas with positive ions and nonthermal electrons. The velocity range of positive, compressive solitary waves is limited by the ion density reaching infinite compression, whereas negative, rarefactive solitary waves and double layers can exist when the electron nonthermality exceeds a certain minimum. There are even regions of coexistence, the limits of which can be elucidated by considering the properties of the special Sagdeev pseudopotential at the acoustic speed. In particular, when the compositional parameters and Mach numbers admit only compressive or rarefactive solitary structures, these have to be superacoustic, their amplitude vanishing at the acoustic speed. When both compressive and rarefactive modes can occur, one of them is Korteweg-de Vries (KdV)-like, the other having a non-KdV character, with a finite amplitude at the acoustic speed.

  5. Microcirculation and hemorheology in NIDDM patients.

    PubMed

    Catalano, M; Tomasini, M; Annoni, M; Gherardi, E; Scandale, G; Galimberti, P; Porro, T; Milanese, F; Libretti, A

    1990-12-01

    The authors studied 10 patients with non-insulin-dependent diabetes mellitus and 5 controls matched for age, sex, blood lipids, and smoking habit. The two groups were also comparable for hemorheologic characteristics as evaluated by viscosimetry on whole blood, plasma and serum, erythrocyte filtration and aggregation. The microcirculation was studied in the subjects of both groups by microalbuminuria determination, retinal fluorangiography, and capillaroscopic examination of the bulbar conjunctive and nail folds. None of the patients presented microalbuminuria values higher than the upper limit of normal (20mg/24h). Fluoroangiographic alterations were observed in 4 patients, and all 10 presented capillaroscopic alterations at the bulbar conjunctiva (microaneurysms, erythrocyte aggregates) and nail folds (more frequently of the fingers than toes). Similar alterations were detected in controls. Thus these abnormalities seem independent of hemorheologic values.

  6. Non-invasive imaging of microcirculation: a technology review

    PubMed Central

    Eriksson, Sam; Nilsson, Jan; Sturesson, Christian

    2014-01-01

    Microcirculation plays a crucial role in physiological processes of tissue oxygenation and nutritional exchange. Measurement of microcirculation can be applied on many organs in various pathologies. In this paper we aim to review the technique of non-invasive methods for imaging of the microcirculation. Methods covered are: videomicroscopy techniques, laser Doppler perfusion imaging, and laser speckle contrast imaging. Videomicroscopy techniques, such as orthogonal polarization spectral imaging and sidestream dark-field imaging, provide a plentitude of information and offer direct visualization of the microcirculation but have the major drawback that they may give pressure artifacts. Both laser Doppler perfusion imaging and laser speckle contrast imaging allow non-contact measurements but have the disadvantage of their sensitivity to motion artifacts and that they are confined to relative measurement comparisons. Ideal would be a non-contact videomicroscopy method with fully automatic analysis software. PMID:25525397

  7. Assessment of endothelial and neurovascular function in human skin microcirculation.

    PubMed

    Roustit, Matthieu; Cracowski, Jean-Luc

    2013-07-01

    Peripheral microvascular dysfunction has been described in many physiological and pathological conditions. Owing to its accessibility, the cutaneous microcirculation provides a unique index of microvascular function. Skin microvascular function has therefore been proposed as a prognostic marker or for evaluating the effect of drugs on the microcirculation. Various reactivity tests, coupled with techniques measuring skin blood flux, are used to non-invasively explore both endothelial and neurovascular microvascular functioning in humans. We review the advantages and limitations of the main reactivity tests, including post-occlusive reactive hyperemia, local thermal hyperemia, pressure-induced vasodilation, and iontophoresis of vasodilators, combined with measurement techniques such as laser Doppler and laser speckle contrast imaging. Recent advances in our comprehension of the physiological pathways underlying these reactivity tests, as well as technological developments in microcirculation imaging, have provided reliable and reproducible tools for studying the microcirculation.

  8. Asymptotic stability of rarefaction waves for 2 × 2 viscous hyperbolic conservation laws—The two-modes case

    NASA Astrophysics Data System (ADS)

    Xin, Zhouping

    In this paper, we continue our study on the asymptotic behavior toward rare-faction waves of a general 2 × 2 system of hyperbolic conservation laws with positive viscosity matrix. It is shown that when the initial data is a small perturbation of a weak rarefaction wave (a linear superposition of a 1-rarefaction wave and a 2-rarefaction wave) for the corresponding inviscid hyperbolic conservation laws, then the solution of the Cauchy problem for the viscous system globally exists and tends to the rarefaction wave. The result is proved by using an energy method, combining the technique in [Z. P. Xin, J. Differential Equations73 (1988), 45-77], and using the characteristic-energy method of T. P. Liu [ Mem. Amer. Math. Soc.328 (1975), 1-108].

  9. The application of rarefaction techniques to molecular inventories of microbial diversity.

    PubMed

    Hughes, Jennifer B; Hellmann, Jessica J

    2005-01-01

    With the growing capacity to inventory microbial community diversity, the need for statistical methods to compare community inventories is also growing. Several approaches have been proposed for comparing the diversity of microbial communities: some adapted from traditional ecology and others designed specifically for molecular inventories of microbes. Rarefaction is one statistical method that is commonly applied in microbial studies, and this chapter discusses the procedure and its advantages and disadvantages. Rarefaction compares observed taxon richness at a standardized sampling effort using confidence intervals. Special emphasis is placed here on the need for precise, rather than unbiased, estimation methods in microbial ecology, but precision can be judged only with a very large sample or with multiple samples drawn from a single community. With low sample sizes, rarefaction curves also have the potential to lead to incorrect rankings of relative species richness, but this chapter discusses a new method with the potential to address this problem. Finally, this chapter shows how rarefaction can be applied to the comparison of the taxonomic similarity of microbial communities.

  10. Experimental observation of cavitons and rarefaction waves in laser-produced plasma

    SciTech Connect

    Briand, J.; Tamer, M.E.; Adrian, V.; Gomes, A.; Quemener, Y.; Kieffer, J.C.; Dinguirard, J.P.

    1984-10-01

    A Wollaston's prism interferometer and a 632.9 nm probe beam having a 10 psec (FWHM) pulse are used to detect the electron density profile instabilities in a 1.06 ..mu..m laser-produced plasma. Experimental observations of cavitons and rarefaction waves are presented and discussed for a laser irradiance of 10/sup 15/ W/cm/sup 2/.

  11. Arterial stiffening precedes systolic hypertension in diet-induced obesity.

    PubMed

    Weisbrod, Robert M; Shiang, Tina; Al Sayah, Leona; Fry, Jessica L; Bajpai, Saumendra; Reinhart-King, Cynthia A; Lob, Heinrich E; Santhanam, Lakshmi; Mitchell, Gary; Cohen, Richard A; Seta, Francesca

    2013-12-01

    Stiffening of conduit arteries is a risk factor for cardiovascular morbidity. Aortic wall stiffening increases pulsatile hemodynamic forces that are detrimental to the microcirculation in highly perfused organs, such as the heart, brain, and kidney. Arterial stiffness is associated with hypertension but presumed to be due to an adaptive response to increased hemodynamic load. In contrast, a recent clinical study found that stiffness precedes and may contribute to the development of hypertension although the mechanisms underlying hypertension are unknown. Here, we report that in a diet-induced model of obesity, arterial stiffness, measured in vivo, develops within 1 month of the initiation of the diet and precedes the development of hypertension by 5 months. Diet-induced obese mice recapitulate the metabolic syndrome and are characterized by inflammation in visceral fat and aorta. Normalization of the metabolic state by weight loss resulted in return of arterial stiffness and blood pressure to normal. Our findings support the hypothesis that arterial stiffness is a cause rather than a consequence of hypertension.

  12. Foot microcirculation and blood rheology in diabetes.

    PubMed

    Zioupos, P; Barbenel, J C; Lowe, G D; MacRury, S

    1993-03-01

    Diabetes mellitus is associated with circulatory abnormalities. The blood flow in the skin of the dorsum of the foot and haemorheological variables were measured in 36 subjects. They were divided into three equal groups of diabetic patients: those with neuropathy, and both age and sex matched non-diabetic subjects; all were characterized by age, duration of diabetes and blood biochemistry. High and low shear rate blood viscosities were measured; aggregation was characterized using a Myrerene Aggregometer. The microcirculation in the skin of the dorsum of the foot was measured using a laser Doppler flowmeter. Measurements were made at room temperature with the subjects supine with the leg horizontal, and then with the lower leg vertical; the measurements were repeated at 42 degrees C. Both diabetic groups had significantly increased low shear whole blood viscosity compared with normal subjects. The aggregation index was significantly greater in diabetic neuropaths than normal subjects. There were significant differences in the depth of vasomotor activity between the three groups, with the diabetic neuropaths commonly showing no motor activity at room temperature. The only significant correlations were between equilibrium laser Doppler values with the limb horizontal and both the low and high shear whole blood viscosities.

  13. PIC simulation of compressive and rarefactive dust ion-acoustic solitary waves

    NASA Astrophysics Data System (ADS)

    Li, Zhong-Zheng; Zhang, Heng; Hong, Xue-Ren; Gao, Dong-Ning; Zhang, Jie; Duan, Wen-Shan; Yang, Lei

    2016-08-01

    The nonlinear propagations of dust ion-acoustic solitary waves in a collisionless four-component unmagnetized dusty plasma system containing nonextensive electrons, inertial negative ions, Maxwellian positive ions, and negatively charged static dust grains have been investigated by the particle-in-cell method. By comparing the simulation results with those obtained from the traditional reductive perturbation method, it is observed that the rarefactive KdV solitons propagate stably at a low amplitude, and when the amplitude is increased, the prime wave form evolves and then gradually breaks into several small amplitude solitary waves near the tail of soliton structure. The compressive KdV solitons propagate unstably and oscillation arises near the tail of soliton structure. The finite amplitude rarefactive and compressive Gardner solitons seem to propagate stably.

  14. Ion-acoustic compressive and rarefactive solitons in an electron-beam plasma system

    SciTech Connect

    Yadav, L.L.; Tiwari, R.S.; Sharma, S.R. )

    1994-03-01

    Using the general formulation of reductive perturbation method, the Korteweg--de Vries (KdV) equation is derived for an electron-beam plasma with hot isothermal beam and plasma electrons and warm ions. The soliton solution of the KdV equation is discussed in detail. It is found that above a critical velocity of electron-beam two additional ion-acoustic soliton branches appear. It is found that corresponding to two linear modes, the system supports the existence of compressive as well as rarefactive solitons depending upon the plasma parameters, while corresponding to other two wave modes, the system supports only rarefactive solitons. The effect of different parameters on the characteristics of solitons have been investigated in detail.

  15. Shock waves, rarefaction waves, and nonequilibrium steady states in quantum critical systems

    NASA Astrophysics Data System (ADS)

    Lucas, Andrew; Schalm, Koenraad; Doyon, Benjamin; Bhaseen, M. J.

    2016-07-01

    We reexamine the emergence of a universal nonequilibrium steady state following a local quench between quantum critical heat baths in spatial dimensions greater than one. We show that energy transport proceeds by the formation of an instantaneous shock wave and a broadening rarefaction wave on either side of the interface, and not by two shock waves as previously proposed. For small temperature differences the universal steady state energy currents of the two-shock and rarefaction-shock solutions coincide. Over a broad range of parameters, the difference in the energy flow across the interface between these two solutions is at the level of 2%. The properties of the energy flow remain fully universal and independent of the microscopic theory. We briefly discuss the width of the shock wave in a viscous fluid, the effects of momentum relaxation, and the generalization to charged fluids.

  16. Conspecific sperm precedence in Drosophila.

    PubMed

    Price, C S

    1997-08-14

    Traits that influence the interactions between males and females can evolve very rapidly through sexual selection or sexually antagonistic coevolution. Rapid change in the fertilization systems of independent populations can give rise to reproductive incompatibilities between populations, and may contribute to speciation. Here I provide evidence for cryptic reproductive divergence among three sibling species of Drosophila that leads to a form of postmating isolation. When a female mates with both a conspecific and a heterospecific male, the conspecific sperm fertilize the vast majority of the eggs, regardless of the order of the matings. Heterospecific sperm fertilize fewer eggs after these double matings than after single matings. Experiments using spermless males show that the seminal fluid of the conspecific male is largely responsible for this conspecific sperm precedence. Moreover, when two males of the same species mate sequentially with a female from a different species, a highly variable pattern of sperm precedence replaces the second-male sperm precedence that is consistently found within species. These results indicate that females mediate sperm competition, and that second-male sperm precedence is not an automatic consequence of the mechanics of sperm storage.

  17. Sublingual Microcirculation in Pulmonary Arterial Hypertension

    PubMed Central

    Dababneh, Luma; Cikach, Frank; Alkukhun, Laith; Dweik, Raed A.

    2014-01-01

    Rationale: Pulmonary arterial hypertension (PAH) is a pulmonary vasculopathy that leads to failure of the right ventricle and premature death. Objectives: To determine whether the sublingual microcirculation is affected in patients with PAH compared with healthy age- and sex-matched control subjects. Methods: Using the CapiScope Handheld Video Capillaroscope we measured the sublingual microvasculature density, flow index, tortuosity, and curvature. Videos were acquired immediately after right heart catheterization, and determinations were made off-line by investigators blinded to the group assignment or hemodynamics. Measurements and Main Results: In this cross-sectional pilot study, we included 26 patients with PAH (age, mean ± SD, 56.7 ± 10 yr; 77% women) and 14 healthy control subjects (age, 53.1 ± 12 yr; 71% women). Sublingual microvasculature flow index was lower (2 ± 0.66 vs. 2.7 ± 0.37, P < 0.001) with higher heterogeneity index (0.63 ± 0.63 vs. 0.25 ± 0.25, P = 0.04) in patients with PAH than control subjects. Microvasculature density was similar between the groups, but tortuosity was more pronounced in patients than control subjects (tort 0: 45 ± 19 vs. 23.6 ± 12, P = 0.001 and tort 1: 0.2 ± 0.16 vs. 0.06 ± 0.04, P < 0.001). Conclusions: Patients with PAH showed lower sublingual microvasculature flow index and higher tortuosity compared with healthy age- and sex-matched control subjects. Further investigations are needed to assess whether this methodology can provide information on disease prognosis and/or response to therapy in this condition. PMID:24601682

  18. Endothelial sirtuin 1 inactivation enhances capillary rarefaction and fibrosis following kidney injury through Notch activation.

    PubMed

    Kida, Yujiro; Zullo, Joseph A; Goligorsky, Michael S

    2016-09-23

    Peritubular capillary (PTC) rarefaction along with tissue fibrosis is a hallmark of chronic kidney disease (CKD). However, molecular mechanisms of PTC loss have been poorly understood. Previous studies have demonstrated that functional loss of endothelial sirtuin 1 (SIRT1) impairs angiogenesis during development and tissue damage. Here, we found that endothelial SIRT1 dysfunction causes activation of endothelial Notch1 signaling, which leads to PTC rarefaction and fibrosis following kidney injury. In mice lacking functional SIRT1 in the endothelium (Sirt1 mutant), kidney injury enhanced apoptosis and senescence of PTC endothelial cells with impaired endothelial proliferation and expanded myofibroblast population and collagen deposition. Compared to wild-type kidneys, Sirt1 mutant kidneys up-regulated expression of Delta-like 4 (DLL4, a potent Notch1 ligand), Hey1 and Hes1 (Notch target genes), and Notch intracellular domain-1 (NICD1, active form of Notch1) in microvascular endothelial cells (MVECs) post-injury. Sirt1 mutant primary kidney MVECs reduced motility and vascular assembly and enhanced senescence compared to wild-type kidney MVECs. This difference in the phenotype was negated with Notch inhibition. Concurrent stimulation of DLL4 and transforming growth factor (TGF)-β1 increased trans-differentiation of primary kidney pericytes into myofibroblast more than TGF-β1 treatment alone. Collectively, these results indicate that endothelial SIRT1 counteracts PTC rarefaction by repression of Notch1 signaling and antagonizes fibrosis via suppression of endothelial DLL4 expression.

  19. Rarefaction effects in dilute granular Poiseuille flow: Knudsen minimum and temperature bimodality

    NASA Astrophysics Data System (ADS)

    Mahajan, Achal; Alam, Meheboob

    2015-11-01

    The gravity-driven flow of smooth inelastic hard-disks through a channel, analog of granular Poiseuille flow, is analysed using event-driven simulations. We find that the variation of the mass-flow rate (Q) with Knudsen number (Kn) can be non-monotonic in the elastic limit (i.e. the restitution coefficient en --> 1) in channels with very smooth walls. The Knudsen minimum effect (i.e. the minimum flow rate occurring at Kn ~ O (1) for the Poiseuille flow of a molecular gas) is found to be absent in a granular gas with en <= 0 . 99 , irrespective of wall roughness. Another rarefaction phenomenon, the bimodality of the temperature profile, with a local minimum at the channel centerline and two symmetric maxima (Tmax) away from the centerline, is studied. We show that the inelastic dissipation is responsible for the onset of temperature bimodality [i.e. the excess temperature, ▵ T = (Tmax /Tmin - 1) ≠ 0 ] near the continuum limit (Kn ~ 0), but the rarefaction being its origin (as in molecular gas) holds beyond Kn ~ O (0 . 1) . The competition between dissipation and rarefaction seems to be responsible for the observed dependence of both mass-flow rate and temperature bimodality on Kn and en . [Alam etal. 2015, JFM (revised)].

  20. A case study of global stability of strong rarefaction waves for 2×2 hyperbolic conservation laws with artificial viscosity

    NASA Astrophysics Data System (ADS)

    Duan, Ran; Ma, Xuan; Zhao, Huijiang

    This paper is concerned with the global stability of strong rarefaction waves for a class of 2×2 hyperbolic conservation laws with artificial viscosity, i.e., the p-system with artificial viscosity {

  1. Two alternative models concerning the perialveolar microcirculation in mammalian lungs.

    PubMed

    Günther, Bruno; Morgado, Enrique; Cociña, Manuela

    2005-01-01

    Despite the fact that the concept of sheet-flow in the pulmonary microcirculation of mammals was introduced more than three decades ago, the capillary circulatory model still prevails in the physiological literature. Since cardiac output is identical in the systemic and in pulmonary circulations, it is noteworthy that in the former, the resulting arterial pressure is five times higher than that of the latter, which means that the corresponding microcirculations must be radically different. The present study addresses this problem from both morphological and physiological perspectives.

  2. [The introduction of thermodynamics in the theory of the microcirculation].

    PubMed

    Petrow, J M

    1991-12-01

    By application of thermodynamics on the theory of microcirculation in tissues one must implicate the fact that both phenomena convection and diffusion through semipermeable membranes take place in "non opened" compartments. Based on this precondition the present paper shows that the known calculations by Kedem and Katchalsky and others are insufficient in order to describe the above mentioned processes and that the reflection coefficient delta is not relevant to the real movement of molecules through capillary walls. Furthermore, the basic equation of the microcirculation is to be improved by a diffusion component in order to represent a better approximation of the exchange situation in tissues.

  3. Design of sensors for microcirculation investigation in pharyngeal mucosa

    NASA Astrophysics Data System (ADS)

    Mareew, Gleb O.; Mareew, Oleg V.; Fedosov, Ivan V.; Tuchin, Valery V.

    2004-08-01

    Sensors designed for research of blood microcirculation in pharyngeal mucosa by a laser Doppler flowmetry, are described and considered in view of anatomic and physiological features of objects of research. Two designs of sensors for laser Doppler flowmetry are described - non-contact and contact. The results of and clinical testing at norm and different pathologies of pharynx of on calibration of sensors, and also their comparative technical characteristics and materials of clinical researches of microcirculation are resulted at norm and at a various pathology.

  4. In vivo label-free quantification of liver microcirculation using dual-modality microscopy

    NASA Astrophysics Data System (ADS)

    Yan, Jie; Kang, Yuzhan; Xu, Shuoyu; Ong, Lee-Ling S.; Zhuo, Shuangmu; Bunte, Ralph M.; Chen, Nanguang; Asada, H. Harry; So, Peter T. C.; Wanless, Ian R.; Yu, Hanry

    2014-11-01

    Microcirculation lesion is a common symptom of chronic liver diseases in the form of vasculature deformation and circulation alteration. In acute to chronic liver diseases such as biliary atresia, microcirculation lesion can have an early onset. Detection of microcirculation lesion is meaningful for studying the progression of liver disease. We have combined wide-field fluorescence microscopy and a laser speckle contrast technique to characterize hepatic microcirculation in vivo without labeling in a bile-duct ligation rat fibrosis model of biliary atresia. Through quantitative image analysis of four microcirculation parameters, we observed significant microcirculation lesion in the early to middle stages of fibrosis. This bimodal imaging method is useful to assess hepatic microcirculation lesion for the study of liver diseases.

  5. Role of platelet-derived growth factor-CC in capillary rarefaction in renal fibrosis.

    PubMed

    Boor, Peter; Bábíčková, Janka; Steegh, Floor; Hautvast, Petra; Martin, Ina V; Djudjaj, Sonja; Nakagawa, Taizo; Ehling, Josef; Gremse, Felix; Bücher, Eva; Eriksson, Ulf; van Roeyen, Claudia R C; Eitner, Frank; Lammers, Twan; Floege, Jürgen; Peutz-Kootstra, Carine J; Ostendorf, Tammo

    2015-08-01

    We have identified platelet-derived growth factor (PDGF)-CC as a potent profibrotic mediator in kidney fibrosis and pro-angiogenic mediator in glomeruli. Because renal fibrosis is associated with progressive capillary rarefaction, we asked whether PDGF-CC neutralization in fibrosis might have detrimental anti-angiogenic effects leading to aggravated peritubular capillary loss. We analyzed capillary rarefaction in mice with and without PDGF-CC neutralization (using genetically deficient mice and neutralizing antibodies), in three different models of renal interstitial fibrosis, unilateral ureteral obstruction, unilateral ischemia-reperfusion, Col4a3-deficient (Alport) mice, and healthy animals. Independent of the effect of PDGF-CC neutralization on renal fibrosis, we found no difference in capillary rarefaction between PDGF-CC-neutralized mice and mice with intact PDGF-CC. We also found no differences in microvascular leakage (determined by extravasation of Evans Blue Dye) and in renal relative blood volume quantified using in vivo microcomputed tomography. PDGF-CC neutralization had no effects on renal microvasculature in healthy animals. Capillary endothelium did not express PDGF receptor-α, suggesting that potential PDGF-CC effects would have to be indirect. PDGF-CC neutralization or deficiency was not associated with preservation or accelerated loss of peritubular capillaries, suggesting no significant pro-angiogenic effects of PDGF-CC during renal fibrosis. From a clinical perspective, the profibrotic effects of PDGF-CC outweigh the pro-angiogenic effects and, thus, do not limit a potential therapeutic use of PDGF-CC inhibition in renal fibrosis.

  6. Effects of rarefaction on the shock wave/boundary layer interaction in hypersonic regime

    NASA Astrophysics Data System (ADS)

    Zuppardi, Gennaro; Boffa, Chiara

    2012-11-01

    Maneuverability of an aero-space-plane can be performed, besides by thrusters, also by aerodynamic surfaces on which a shock wave, generated on the front part of the vehicle, could impinge. This impingement produces on the surface local increases of heat flux and of aerodynamic load. The purpose of the present study is to evaluate the effects of rarefaction on the Shock Wave/Boundary Layer Interaction (SWBLI) in hypersonic regime. In rarefied regimes, in fact, the shock wave and the boundary layer are thicker than those in continuum, producing on the surface a more extended interaction zone. Furthermore, as the present analysis is carried out at Mach numbers typical of the reentry, a shock wave is much stronger than that usually met in supersonic, continuum flow. The study is carried on as a function of altitude in order to quantify the effects of both rarefaction and intensity of the shock wave on: extension of the interaction region, heat flux, aerodynamic load, slip velocity and slip temperature. The problem is studied computationally by the direct simulation Monte Carlo code DS2V. The flow field on a flat plate, on which a shock wave impinges, is simulated. The test conditions are those that should be met by the Flight Test Bed vehicle (FTB-X) along the re-entry path in the altitude interval 55-75 km. As expected, the extension of the interaction region increases with rarefaction. The maximum values of heat flux and aerodynamic load in the interaction region are about one order of magnitude higher than the same quantities without shock wave impingement and are comparable with those at the leading edge. The tests verified that the Neumann's analytical relation, linking the pressure rise to the heating rise in the interaction region, holds also in rarefied regime.

  7. Coexistence of Shocks and Rarefaction Fans: Complex Phase Diagram of a Simple Hyperbolic Particle System

    NASA Astrophysics Data System (ADS)

    Balázs, Márton; Nagy, Attila László; Tóth, Bálint; Tóth, István

    2016-10-01

    This paper investigates the non-equilibrium hydrodynamic behavior of a simple totally asymmetric interacting particle system of particles, antiparticles and holes on Z. Rigorous hydrodynamic results apply to our model with a hydrodynamic flux that is exactly calculated and shown to change convexity in some region of the model parameters. We then characterize the entropy solutions of the hydrodynamic equation with step initial condition in this scenario which include various mixtures of rarefaction fans and shock waves. We highlight how the phase diagram of the model changes by varying the model parameters.

  8. Compressive and rarefactive dressed solitons in plasma with nonthermal electrons and positrons

    NASA Astrophysics Data System (ADS)

    Abdelwahed, H. G.; El-Shewy, E. K.; Zahran, M. A.; Elwakil, S. A.

    2016-02-01

    The study of dressed solitary ion waves in a collisionless unmagnetized plasma composed warm fluid of ion, nonthermal distributed positrons and electrons are discussed. Concerning nonlinear ion acoustic waves, a reductive perturbation method is applied to obtain the KdV equation in terms of first order potential. Our results exemplify that, if soliton amplitude enlarged, the shape of the wave sidetrack from KdV equation. In order to improve the soliton shape, the perturbed KdV equation is suggest. In particular, the effects of nonthermal positrons and ionic temperature on the electrostatic dressed rarefactive and compressive soliton structures are discussed.

  9. 47 CFR 213.5 - Precedence designators.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Precedence designators. 213.5 Section 213.5 Telecommunication OFFICE OF SCIENCE AND TECHNOLOGY POLICY AND NATIONAL SECURITY COUNCIL GOVERNMENT AND PUBLIC CORRESPONDENCE TELECOMMUNICATIONS PRECEDENCE SYSTEM § 213.5 Precedence designators. (a) The following...

  10. Rarefaction windows in a high-power impulse magnetron sputtering plasma

    SciTech Connect

    Palmucci, Maria; Britun, Nikolay; Konstantinidis, Stephanos; Snyders, Rony

    2013-09-21

    The velocity distribution function of the sputtered particles in the direction parallel to the planar magnetron cathode is studied by spatially- and time-resolved laser-induced fluorescence spectroscopy in a short-duration (20 μs) high-power impulse magnetron sputtering discharge. The experimental evidence for the neutral and ionized sputtered particles to have a constant (saturated) velocity at the end of the plasma on-time is demonstrated. The velocity component parallel to the target surface reaches the values of about 5 km/s for Ti atoms and ions, which is higher that the values typically measured in the direct current sputtering discharges before. The results point out on the presence of a strong gas rarefaction significantly reducing the sputtered particles energy dissipation during a certain time interval at the end of the plasma pulse, referred to as “rarefaction window” in this work. The obtained results agree with and essentially clarify the dynamics of HiPIMS discharge studied during the plasma off-time previously in the work: N. Britun, Appl. Phys. Lett. 99, 131504 (2011)

  11. Influence of rarefaction on the flow dynamics of a stationary supersonic hot-gas expansion.

    PubMed

    Abbate, G; Kleijn, C R; Thijsse, B J; Engeln, R; van de Sanden, M C M; Schram, D C

    2008-03-01

    The gas dynamics of a stationary hot-gas jet supersonically expanding into a low pressure environment is studied through numerical simulations. A hybrid coupled continuum-molecular approach is used to model the flow field. Due to the low pressure and high thermodynamic gradients, continuum mechanics results are doubtful, while, because of its excessive time expenses, a full molecular method is not feasible. The results of the hybrid coupled continuum-molecular approach proposed have been successfully validated against experimental data by R. Engeln [Plasma Sources Sci. Technol. 10, 595 (2001)] obtained by means of laser induced fluorescence. Two main questions are addressed: the necessity of applying a molecular approach where rarefaction effects are present in order to correctly model the flow and the demonstration of an invasion of the supersonic part of the flow by background particles. A comparison between the hybrid method and full continuum simulations demonstrates the inadequacy of the latter, due to the influence of rarefaction effects on both velocity and temperature fields. An analysis of the particle velocity distribution in the expansion-shock region shows clear departure from thermodynamic equilibrium and confirms the invasion of the supersonic part of the flow by background particles. A study made through particles and collisions tracking in the supersonic region further proves the presence of background particles in this region and explains how they cause thermodynamic nonequilibrium by colliding and interacting with the local particles.

  12. Rarefaction of skin capillaries in normotensive offspring of individuals with essential hypertension

    PubMed Central

    Antonios, T F T; Rattray, F M; Singer, D R J; Markandu, N D; Mortimer, P S; MacGregor, G A

    2003-01-01

    Background: Rarefaction of skin capillaries in people with intermittent borderline essential hypertension suggests a primary or an early abnormality that may antedate the onset of sustained hypertension. Objective: To compare skin capillary density in subjects with and without a family history of essential hypertension. Subjects: 21 normotensive individuals, one or both of whose parents had essential hypertension (mean age 39.3 years; blood pressure 124/79 mm Hg); 21 normotensive controls with no family history of hypertension (age 46.3 years; blood pressure 124/78 mm Hg). Methods: The skin of the dorsum of the fingers was examined by intravital capillary microscopy before and after venous congestion at 60 mm Hg for two minutes. Results: By analysis of variance, both baseline and maximum skin capillary density were lower in subjects with a family history of essential hypertension than in those with no family history (baseline: 67 v 79 capillaries per field, p = 0.008; maximum: 74 v 93 capillaries per field, p < 0.0005). Conclusions: Capillary rarefaction in essential hypertension may occur before the increase in blood pressure and could, at least in part, reflect a primary rather than a secondary abnormality. PMID:12527671

  13. PIC simulation of a thermal anisotropy-driven Weibel instability in a circular rarefaction wave

    NASA Astrophysics Data System (ADS)

    Dieckmann, M. E.; Sarri, G.; Murphy, G. C.; Bret, A.; Romagnani, L.; Kourakis, I.; Borghesi, M.; Ynnerman, A.; O'C Drury, L.

    2012-02-01

    The expansion of an initially unmagnetized planar rarefaction wave has recently been shown to trigger a thermal anisotropy-driven Weibel instability (TAWI), which can generate magnetic fields from noise levels. It is examined here whether the TAWI can also grow in a curved rarefaction wave. The expansion of an initially unmagnetized circular plasma cloud, which consists of protons and hot electrons, into a vacuum is modelled for this purpose with a two-dimensional particle-in-cell (PIC) simulation. It is shown that the momentum transfer from the electrons to the radially accelerating protons can indeed trigger a TAWI. Radial current channels form and the aperiodic growth of a magnetowave is observed, which has a magnetic field that is oriented orthogonal to the simulation plane. The induced electric field implies that the electron density gradient is no longer parallel to the electric field. Evidence is presented here that this electric field modification triggers a second magnetic instability, which results in a rotational low-frequency magnetowave. The relevance of the TAWI is discussed for the growth of small-scale magnetic fields in astrophysical environments, which are needed to explain the electromagnetic emissions by astrophysical jets. It is outlined how this instability could be examined experimentally.

  14. Compressive and rarefactive DIA solitons beyond the KdV limit

    SciTech Connect

    Mamun, A. A.; Deeba, F.

    2012-04-15

    The modified Gardner equation (MGE), showing the existence of compressive and rarefactive dust-ion-acoustic (DIA) solitons in a nonplanar dusty plasma (containing inertial ions, Boltzmann electrons, and negatively charged stationary dust) beyond the KdV Korteweg-de Vries (KdV) limit, is derived and numerically solved. The basic features of the compressive and rarefactive cylindrical and spherical DIA solitons, which are found to exist beyond the KdV limit, i.e., exist for {mu} {approx} 2/3 (where {mu} = Z{sub n}n{sub d0}/n{sub i0}, z{sub d} is the number of electrons residing onto the dust grain surface, n{sub d0}(n{sub i0}) is the dust (ion) number density at equilibrium, and {mu} {approx} 2/3 means that {mu} is not equal to 2/3, but it is around 2/3) are identified. These solitons (which can be referred to as DIA Gardner solitons (DIA-GSs)) are completely different from the KdV solitons because {mu} = 2/3 corresponds to the vanishing of the nonlinear coefficient of the KdV equation, and {mu} {approx} 2/3 corresponds to extremely large amplitude KdV solitons for which the validity of the reductive perturbation method breaks down. It is also shown that the properties of the nonplanar (cylindrical and spherical) DIA-GSs are significantly different from those of the one dimensional planar ones.

  15. Precedence relationship representations of mechanical assembly sequences

    NASA Technical Reports Server (NTRS)

    Homendemello, L. S.; Sanderson, A. C.

    1989-01-01

    Two types of precedence relationship representations for mechanical assembly sequences are presented: precedence relationships between the establishment of one connection between two parts and the establishment of another connection, and precedence relationships between the establishment of one connection and states of the assembly process. Precedence relationship representations have the advantage of being very compact. The problem with these representations was how to guarantee their correctness and completeness. Two theorems are presented each of which leads to the generation of one type of precedence relationship representation guaranteeing its correctness and completeness for a class of assemblies.

  16. Nonlinear Stability of Strong Planar Rarefaction Waves for the Relaxation Approximation of Conservation Laws in Several Space Dimensions

    NASA Astrophysics Data System (ADS)

    Zhao, Huijiang

    2000-04-01

    In this paper, we show that a strong planar rarefaction wave is nonlinear stable, namely it is an attractor for the relaxation approximation of the scalar conservation laws in several space dimensions. Compared with former results obtained by T. P. Liu (1987, Comm. Math. Phys.108, 153-175) and T. Luo (1997, J. Differential Equations133, 255-279), our main novelty lies in the fact that the planar rarefaction waves do not need to be small, and in the one-dimensional case, the initial disturbance can also be chosen arbitrarily large.

  17. Mechanobiology and the microcirculation: cellular, nuclear and fluid mechanics

    PubMed Central

    Dahl, Kris Noel; Kalinowski, Agnieszka; Pekkan, Kerem

    2010-01-01

    Endothelial cells are stimulated by shear stress throughout the vasculature and respond with changes in gene expression and by morphological reorganization. Mechanical sensors of the cell are varied and include cell surface sensors that activate intracellular chemical signaling pathways. Here, possible mechanical sensors of the cell including reorganization of the cytoskeleton and the nucleus are discussed in relation to shear flow. A mutation in the nuclear structural protein lamin A, related to Hutchinson Gilford progeria syndrome, is reviewed specifically since the mutation results in altered nuclear structure and stiffer nuclei; animal models also suggest significantly altered vascular structure. Nuclear and cellular deformation of endothelial cells in response to shear stress provides partial understanding of possible mechanical regulation in the microcirculation. Increasing sophistication of fluid flow simulations inside the vessel is also an emerging area relevant to the microcirculation since visualization in situ is difficult. This integrated approach to study – including medicine, molecular and cell biology, biophysics and engineering – provides a unique understanding of multi-scale interactions in the microcirculation. PMID:20374482

  18. Frontiers in Microcirculation: Control Processes and Clinical Applications

    PubMed Central

    Segal, Steven S.

    2010-01-01

    This edition of Microcirculation presents five current and emerging perspectives of the microcirculation in development, health and disease. The onset of blood flow and pressure are central to cardiovascular development. These hemodynamic forces are explored in light of underlying molecular signaling pathways that affect vascular and cardiac cell shape and proliferation. Shear-induced strain exerted on the plasma membrane and cytoskeleton is transmitted to cell nuclei and thereby affects gene activation through mechanotransduction. Altered stiffness or disturbed surfaces of aberrant vascular cells may affect an array of vasculopathies through altered gene expression. The endothelium is both a site and source for inflammatory responses triggered by cardiovascular risk factors often mediated through reactive oxygen species and angiotensin II. Tumor microenvironments are disturbed with abnormal growth and remodeling of blood and lymphatic vessels. More effective targeting strategies for delivering anti-angiogenic and cytotoxic agents are being developed through advances in intravital imaging. Blood flow control requires both vasodilation and vasoconstriction to be coordinated along and among arterioles and feed arteries. Evolving insights into signaling pathways between smooth muscle cells and endothelial cells illuminate how such processes can be affected in vasculopathies. These timely reviews provide a novel reference for advancing research frontiers in microcirculation. PMID:20374480

  19. Mechanobiology and the microcirculation: cellular, nuclear and fluid mechanics.

    PubMed

    Dahl, Kris Noel; Kalinowski, Agnieszka; Pekkan, Kerem

    2010-04-01

    Endothelial cells are stimulated by shear stress throughout the vasculature and respond with changes in gene expression and by morphological reorganization. Mechanical sensors of the cell are varied and include cell surface sensors that activate intracellular chemical signaling pathways. Here, possible mechanical sensors of the cell including reorganization of the cytoskeleton and the nucleus are discussed in relation to shear flow. A mutation in the nuclear structural protein lamin A, related to Hutchinson-Gilford progeria syndrome, is reviewed specifically as the mutation results in altered nuclear structure and stiffer nuclei; animal models also suggest significantly altered vascular structure. Nuclear and cellular deformation of endothelial cells in response to shear stress provides partial understanding of possible mechanical regulation in the microcirculation. Increasing sophistication of fluid flow simulations inside the vessel is also an emerging area relevant to the microcirculation as visualization in situ is difficult. This integrated approach to study--including medicine, molecular and cell biology, biophysics and engineering--provides a unique understanding of multi-scale interactions in the microcirculation.

  20. Effect of copper IUD on microcirculation of blood flow in rabbit uterus

    SciTech Connect

    Zhang, M.; Wang, H.F.; Meng, Z.; Huang, H.Y.

    1987-12-01

    A survey of the rabbit's normal microcirculation of blood flow volume in the endometrium and myometrium with or without a copper intrauterine device (IUD) was made. It was found through statistical analyses that the IUD stimulated the endometrium so that microcirculation of blood flow volume in the endometrium increased significantly, but it did not change the microcirculation of blood flow volume in the myometrium and in the opposite uterus.

  1. [Microcirculation impairment in periodontal tissues in patients with chronic generalized periodontitis combined with metabolic syndrome].

    PubMed

    Krechina, E K; Zorina, O A; Molchanov, A M; Shilov, A M

    2016-01-01

    Using the method of laser Doppler flowmetry the study of microcirculation in periodontal tissues in patients with moderate chronic generalized periodontitis and metabolic syndrome was carried out. The analysis of microcirculation values proved not only the reduction of blood flow intensity but also the decreased vasoactivity of microvessels essential to maintain normal microcirculation in periodontal tissues, as it provides active modulation of tissue blood flow and its adaptation to local metabolic needs. PMID:26925562

  2. Slip and accommodation coefficients from rarefaction and roughness in rotating microscale disk flows

    NASA Astrophysics Data System (ADS)

    Blanchard, Danny; Ligrani, Phil

    2007-06-01

    Accommodation coefficients are determined from experimental results and analysis based on the Navier-Stokes equations for rotation-induced flows in C-shaped fluid chamber passages formed between a rotating disk and a stationary surface. A first-order boundary condition is used to model the slip flow. The fluid chamber passage height ranges from 6.85to29.2μm to give Knudsen numbers from 0.0025 to 0.031 for air and helium. In all cases, roughness size is large compared to molecular mean free path. The unique method presented for deducing tangential momentum accommodation coefficients gives values with less uncertainty compared to procedures that rely on flows in stationary tubes and channels. When channel height is defined at the tops of the roughness elements, slip velocity magnitudes and associated accommodation coefficients are a result of rarefaction at solid-gas interfaces and shear at the gas-gas interfaces. With this arrangement, tangential accommodation coefficients obtained with this approach decrease, and slip velocity magnitudes increase, at a particular value of Knudsen number, as the level of surface roughness increases. At values of the mean roughness height greater than 500nm, accommodation coefficients then appear to be lower in air flows than in helium flows, when compared for a particular roughness configuration. When channel height is defined midway between the crests and troughs of the roughness elements, nondimensional pressure rise data show little or no dependence on the level of disk surface roughness and working fluid. With this arrangement, slip is largely independent of surface roughness magnitude and mostly due to rarefaction, provided the appropriate channel height is chosen to define the roughness height.

  3. CEREBRAL CORTICAL MICROVASCULAR RAREFACTION IN METABOLIC SYNDROME IS DEPENDENT ON INSULIN RESISTANCE AND LOSS OF NITRIC OXIDE BIOAVAILABILITY

    PubMed Central

    Chantler, Paul D.; Shrader, Carl D.; Tabone, Lawrence E.; d’Audiffret, Alexandre C.; Huseynova, Khumara; Brooks, Steven D.; Branyan, Kayla W.; Grogg, Kristin A.; Frisbee, Jefferson C.

    2015-01-01

    Objective Chronic presentation of the metabolic syndrome (MS) is associated with an increased likelihood for stroke and poor stroke outcomes following occlusive cerebrovascular events. However, the physiological mechanisms contributing to compromised outcomes remain unclear, and the degree of cerebral cortical microvascular density (MVD) may represent a central determinant of stroke outcomes. Methods This study used the obese Zucker rat (OZR) model of MS and clinically-relevant, chronic interventions to determine the impact on cerebral cortical microvascular rarefaction via immunohistochemistry with a parallel determination of cerebrovascular function to identify putative mechanistic contributors. Results OZR exhibited a progressive rarefaction (to ~80% control MVD) of the cortical microvascular networks vs. lean Zucker rats. Chronic treatment with anti-hypertensive agents (captopril/hydralazine) had limited effectiveness in blunting rarefaction, although treatments improving glycemic control (metformin/rosiglitazone) were superior, maintaining ~94% control MVD. Chronic treatment with the antioxidant TEMPOL severely blunted rarefaction in OZR, although this ameliorative effect was prevented by concurrent NOS inhibition. Conclusions Further analyses revealed that the maintenance of glycemic control and vascular nitric oxide bioavailability were stronger predictors of cerebral cortical MVD in OZR than was prevention of hypertension, and this may have implications for chronic treatment of CVD risk under stroke-prone conditions. PMID:26014499

  4. CHANGES IN SUBLINGUAL MICROCIRCULATION IS CLOSELY RELATED WITH THAT OF BULBAR CONJUNCTIVAL MICROCIRCULATION IN A RAT MODEL OF CARDIAC ARREST.

    PubMed

    Yin, Lu; Yang, Zhengfei; Yu, Haifang; Qian, Jie; Zhao, Shen; Wang, Jiangang; Wu, Xiaobo; Cahoon, Jena; Tang, Wanchun

    2016-04-01

    Following successful resuscitation, a significantly impaired microcirculation has been identified. The severity of the impairment of microcirculation is closely related to that of vital organ dysfunction. Sublingual microcirculation is a traditional site for the measurement of tissue perfusion. In the present study, we investigated the bulbar conjunctival microcirculatory alterations following CPR and its relationship with the changes of sublingual microcirculation in a rat model of cardiac arrest.Male Sprague-Dawley rats (450-550 g) were utilized. Ventricular fibrillation was induced and untreated for 8 min followed by 8 min of CPR. Sublingual and bulbar conjunctival microcirculatory blood flow was visualized by a sidestream dark-field imaging device at baseline, 30 min, 1, 2, 4, and 8 h post-resuscitation. Both perfused vessel density (PVD) and microcirculatory flow index (MFI) were recorded.The post-resuscitation PVD and MFI were significantly decreased in both sublingual and bulbar conjunctival sites. Sublingual PVD decreased from baseline of 5.9 ± 0.3 to 3.1 ± 0.4 n/mm at 30 min post-resuscitation and MFI from 3.0 ± 0.0 to 1.5 ± 0.3 (both P < 0.05 vs. baseline). Bulbar conjunctival PVD was significantly reduced from baseline of 6.5 ± 0.6 to 3.9 ± 0.5 n/mm at 30 min post-resuscitation and MFI from 3.0 ± 0.0 to 1.2 ± 0.4 (both P < 0.05 vs. baseline). PVD, MFI, and cardiac function did not change significantly from the 30-min measurements in the surviving rats throughout the remainder of the study (both P > 0.05 vs. 30-min post-resuscitation). The decreases in sublingual microcirculatory blood flow were closely correlated with the reductions of bulbar conjunctival microcirculatory blood flow (PVD: r = 0.87, P < 0.05; MFI: r = 0.92, P < 0.05). Myocardial function was significantly impaired in all animals after resuscitation when compared with baseline values (P < 0.05). The impairments of both sublingual and bulbar conjunctival microcirculation were

  5. Influence of antiseptics on microcirculation after neuronal and receptor blockade.

    PubMed

    Goertz, Ole; Hirsch, Tobias; Ring, Andrej; Muehlberger, Thomas; Steinau, Hans U; Tilkorn, Daniel; Lehnhardt, Marcus; Homann, Heinz H

    2011-08-01

    The topical application of the antiseptics octenidine and polyhexanide on wounds seems to improve microcirculation. These two antiseptics were tested in combination with neuronal inhibition and sympathethic receptor blockade to verify these findings, explore the influence of β blockers on these microcirculative effects, and find out the principle of operation. Investigations were carried out on a standardised cremaster muscle model in rats (n = 66). The tested antiseptics, octenidine and polyhexanide were investigated alone (n = 12) and in combination with bupivacaine (n = 12), metoprolol (n = 12), phentolamine (n = 12) and surgical denervation (n = 12). Physiological saline was used for control (n = 6). The arteriolar diameter and functional capillary density (FCD) were investigated via trans-illumination microscopy before, as well as 60 and 120 minutes after application. Polyhexanide caused a significant increase in arteriolar diameter (86·5 ± 3·8 µm versus 100·0 ± 3·6 µm) and, like octenidine (7·2 ± 0·7 n/0·22 mm(2) versus 11·6 ± 0·6 n/0·22 mm(2) ), in FCD (9·2 ± 0·5 versus 12·6 ± 0·9) as well. When the antiseptics are used in combination with bupivacaine, metoprolol, phentolamine or surgical sympathectomy, these effects were eliminated or inverted. Assessing the results of the different blockades in combination with polyhexanide, we surmise that the antiseptic polyhexanide acts on the microcirculation mainly by blocking α receptors. This study shows that polyhexanide and octenidine improve muscular perfusion. Interestingly, the benefit of polyhexanide and octenidine on muscular perfusion is eliminated when the antiseptics are combined with other vasoactive agents, especially β blockers.

  6. Syndecan-1 in the Mouse Parietal Peritoneum Microcirculation in Inflammation

    PubMed Central

    Kowalewska, Paulina M.; Patrick, Amanda L.; Fox-Robichaud, Alison E.

    2014-01-01

    Background The heparan sulfate proteoglycan syndecan-1 (CD138) was shown to regulate inflammatory responses by binding chemokines and cytokines and interacting with adhesion molecules, thereby modulating leukocyte trafficking to tissues. The objectives of this study were to examine the expression of syndecan-1 and its role in leukocyte recruitment and chemokine presentation in the microcirculation underlying the parietal peritoneum. Methods Wild-type BALB/c and syndecan-1 null mice were stimulated with an intraperitoneal injection of Staphylococcus aureus LTA, Escherichia coli LPS or TNFα and the microcirculation of the parietal peritoneum was examined by intravital microscopy after 4 hours. Fluorescence confocal microscopy was used to examine syndecan-1 expression in the peritoneal microcirculation using fluorescent antibodies. Blocking antibodies to adhesion molecules were used to examine the role of these molecules in leukocyte-endothelial cell interactions in response to LTA. To determine whether syndecan-1 co-localizes with chemokines in vivo, fluorescent antibodies to syndecan-1 were co-injected intravenously with anti-MIP-2 (CXCL2), anti-KC (CXCL1) or anti-MCP-1 (CCL2). Results and Conclusion Syndecan-1 was localized to the subendothelial region of peritoneal venules and the mesothelial layer. Leukocyte rolling was significantly decreased with LPS treatment while LTA and TNFα significantly increased leukocyte adhesion compared with saline control. Leukocyte-endothelial cell interactions were not different in syndecan-1 null mice. Antibody blockade of β2 integrin (CD18), ICAM-1 (CD54) and VCAM-1 (CD106) did not decrease leukocyte adhesion in response to LTA challenge while blockade of P-selectin (CD62P) abrogated leukocyte rolling. Lastly, MIP-2 expression in the peritoneal venules was not dependent on syndecan-1 in vivo. Our data suggest that syndecan-1 is expressed in the parietal peritoneum microvasculature but does not regulate leukocyte recruitment

  7. Application of LASCA for study of blood microcirculation in brain: testing of new prophylactic preparations

    NASA Astrophysics Data System (ADS)

    Ulyanov, Sergey; Ganilova, Yulia; Ulianova, Onega; Li, Pengcheng; Zhu, Dan; Luo, Qingming

    2007-05-01

    LASCA has been combined with cross-correlation technique; as a result, quality of LASCA images has been rather enhanced. Cerebral blood microcirculation has been investigated using modified LASCA technique. Blood microvessels, lying on the deep layers of brain, have been studied. Changes of blood microcirculation in brain, caused by toxic influence of prototypes of new vaccines against extremely dangerous infections, have been analyzed.

  8. 8 CFR 103.10 - Precedent decisions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... General are governed by part 1003 of 8 CFR chapter V. (b) Decisions as precedents. Except as Board... provided in paragraph (c) of this section or 8 CFR 1003.1(h)(2). (d) Publication of Secretary's precedent...; BIOMETRIC REQUIREMENTS; AVAILABILITY OF RECORDS Applying for Benefits, Surety Bonds, Fees § 103.10...

  9. 8 CFR 103.10 - Precedent decisions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... General are governed by part 1003 of 8 CFR chapter V. (b) Decisions as precedents. Except as Board... provided in paragraph (c) of this section or 8 CFR 1003.1(h)(2). (d) Publication of Secretary's precedent...; BIOMETRIC REQUIREMENTS; AVAILABILITY OF RECORDS Applying for Benefits, Surety Bonds, Fees § 103.10...

  10. 8 CFR 103.10 - Precedent decisions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... General are governed by part 1003 of 8 CFR chapter V. (b) Decisions as precedents. Except as Board... provided in paragraph (c) of this section or 8 CFR 1003.1(h)(2). (d) Publication of Secretary's precedent...; BIOMETRIC REQUIREMENTS; AVAILABILITY OF RECORDS Applying for Benefits, Surety Bonds, Fees § 103.10...

  11. Effect of zero magnetic field on cardiovascular system and microcirculation

    NASA Astrophysics Data System (ADS)

    Gurfinkel, Yu. I.; At'kov, O. Yu.; Vasin, A. L.; Breus, T. K.; Sasonko, M. L.; Pishchalnikov, R. Yu.

    2016-02-01

    The effects of zero magnetic field conditions on cardiovascular system of healthy adults have been studied. In order to generate zero magnetic field, the facility for magnetic fields modeling "ARFA" has been used. Parameters of the capillary blood flow, blood pressure, and the electrocardiogram (ECG) monitoring were measured during the study. All subjects were tested twice: in zero magnetic field and, for comparison, in sham condition. The obtained results during 60 minutes of zero magnetic field exposure demonstrate a clear effect on cardiovascular system and microcirculation. The results of our experiments can be used in studies of long-term stay in hypo-magnetic conditions during interplanetary missions.

  12. Effect of zero magnetic field on cardiovascular system and microcirculation.

    PubMed

    Gurfinkel, Yu I; At'kov, O Yu; Vasin, A L; Breus, T K; Sasonko, M L; Pishchalnikov, R Yu

    2016-02-01

    The effects of zero magnetic field conditions on cardiovascular system of healthy adults have been studied. In order to generate zero magnetic field, the facility for magnetic fields modeling "ARFA" has been used. Parameters of the capillary blood flow, blood pressure, and the electrocardiogram (ECG) monitoring were measured during the study. All subjects were tested twice: in zero magnetic field and, for comparison, in sham condition. The obtained results during 60 minutes of zero magnetic field exposure demonstrate a clear effect on cardiovascular system and microcirculation. The results of our experiments can be used in studies of long-term stay in hypo-magnetic conditions during interplanetary missions. PMID:26948007

  13. Cerebral Microcirculation and Oxygen Tension in the Human Secondary Cortex

    PubMed Central

    Linninger, A. A.; Gould, I. G.; Marinnan, T.; Hsu, C.-Y.; Chojecki, M.; Alaraj, A.

    2013-01-01

    The three-dimensional spatial arrangement of the cortical microcirculatory system is critical for understanding oxygen exchange between blood vessels and brain cells. A three-dimensional computer model of a 3 × 3 × 3 mm3 subsection of the human secondary cortex was constructed to quantify oxygen advection in the microcirculation, tissue oxygen perfusion, and consumption in the human cortex. This computer model accounts for all arterial, capillary and venous blood vessels of the cerebral microvascular bed as well as brain tissue occupying the extravascular space. Microvessels were assembled with optimization algorithms emulating angiogenic growth; a realistic capillary bed was built with space filling procedures. The extravascular tissue was modeled as a porous medium supplied with oxygen by advection–diffusion to match normal metabolic oxygen demand. The resulting synthetic computer generated network matches prior measured morphometrics and fractal patterns of the cortical microvasculature. This morphologically accurate, physiologically consistent, multi-scale computer network of the cerebral microcirculation predicts the oxygen exchange of cortical blood vessels with the surrounding gray matter. Oxygen tension subject to blood pressure and flow conditions were computed and validated for the blood as well as brain tissue. Oxygen gradients along arterioles, capillaries and veins agreed with in vivo trends observed recently in imaging studies within experimental tolerances and uncertainty. PMID:23842693

  14. HB-EGF Improves Intestinal Microcirculation after Hemorrhagic Shock

    PubMed Central

    Zhang, Hong-yi; Radulescu, Andrei; Chen, Yan; Besner, Gail E.

    2010-01-01

    Background The goal of this study was to determine the role of heparin-binding epidermal growth factor-like growth factor (HB-EGF) as a mediator of gut microcirculation after hemorrhagic shock and resuscitation (HS/R) in mice. Materials and methods HS/R was induced in HB-EGF knockout (KO) and wild type (WT) mice. Ink-gelatin injection and vascular corrosion casting were performed to visualize the gut microvasculature. The degree of gut microcirculatory injury was graded using five patterns of injury (1–5) according to the severity of microvascular hypoperfusion. Statistical analyses were performed using linear mixed models with p<0.05 considered statistically significant. Results HB-EGF KO mice subjected to HS/R had significantly decreased perfusion of the gut microvasculature compared to WT mice subjected to HS/R (p=0.0001). HB-EGF KO mice subjected to HS/R and treated with exogenous HB-EGF had significantly increased gut microvascular perfusion compared to non-HB-EGF treated KO mice (p=0.01). Lastly, WT mice subjected to HS/R and treated with HB-EGF had significantly increased gut microvascular perfusion compared to non-HB-EGF-treated WT mice (p=0.04). Conclusions HB-EGF improves gut microcirculation after HS/R. These findings support the clinical use of HB-EGF in protection of the intestines from disease states associated with intestinal hypoperfusion injury. PMID:20421109

  15. Effects of low-dose extracorporeal shock waves on microcirculation

    NASA Astrophysics Data System (ADS)

    Khaled, Walaa; Goertz, Ole; Lauer, Henrik; Lehnhardt, Marcus; Hauser, Jörg

    2012-11-01

    The extended wounds of burn patients remain a challenge due to wound infection and following septicemia. The aim of this study was to analyze microcirculation, angiogenesis and leukocyte endothelium interaction after burn injury with and without extracorporeal shock wave application (ESWA). A novel shockwave system was developed based on a commercially available device for orthopedics (Dornier Aries®) that was equipped with a newly developed applicator. This system is based on the electromagnetic shock wave emitter (EMSE) technology and was introduced to accomplish a localized treatment for wound healing. The system includes a novel field of focus for new applications, with high precision and ease of use. In the animal study, full-thickness burns were inflicted on to the ears of hairless mice (n=51). Intravital fluorescent microscopy was used to assess microcirculatory parameters, angiogenesis and leukocyte behavior. ESWA was performed on day 1, 3 and 7. Values were obtained immediately after burn, as well as at days 1, 3, 7, and 12 post burn. All shockwave treated groups showed an accelerated angiogenesis with a less non-perfused area and an improved blood flow after burn injury compared to the placebo control group. After three treatments, the shock waves increased the number of rolling leukocytes significantly compared to the non-treated animals. Shock waves seem to have a positive effect on several parameters of wound healing after burn injury. However, further investigations are necessary to detect positive influence of shock waves on microcirculation after burn injuries.

  16. 2-D Model for Normal and Sickle Cell Blood Microcirculation

    NASA Astrophysics Data System (ADS)

    Tekleab, Yonatan; Harris, Wesley

    2011-11-01

    Sickle cell disease (SCD) is a genetic disorder that alters the red blood cell (RBC) structure and function such that hemoglobin (Hb) cannot effectively bind and release oxygen. Previous computational models have been designed to study the microcirculation for insight into blood disorders such as SCD. Our novel 2-D computational model represents a fast, time efficient method developed to analyze flow dynamics, O2 diffusion, and cell deformation in the microcirculation. The model uses a finite difference, Crank-Nicholson scheme to compute the flow and O2 concentration, and the level set computational method to advect the RBC membrane on a staggered grid. Several sets of initial and boundary conditions were tested. Simulation data indicate a few parameters to be significant in the perturbation of the blood flow and O2 concentration profiles. Specifically, the Hill coefficient, arterial O2 partial pressure, O2 partial pressure at 50% Hb saturation, and cell membrane stiffness are significant factors. Results were found to be consistent with those of Le Floch [2010] and Secomb [2006].

  17. Simulations of the Microcirculation in the Human Conjunctiva

    NASA Astrophysics Data System (ADS)

    Dow, William; Jacobitz, Frank; Chen, Peter

    2012-11-01

    The microcirculation in the conjunctiva of a healthy human subject is analyzed using a simulation approach. A comparison between healthy and diseased states may lead to early diagnosis for a variety of vascular related disorders. Previous work suggests that hypertension, arteriosclerosis, and diabetes mellitus have noticeable very early changes in the microvasculature (Davis and Landau, 1957; Ditzel, 1968; Kunitomo, 1974) and the vessels of the conjunctiva are specifically useful for this research because they can be studied non-invasively. The microcirculation in the conjunctiva has been documented over the course of disease treatments, providing both still images and video footage for information on vessel length, diameter, and connectivity as well as the direction of blood flow. The numerical method is based on a Hagen-Poiseuille balance in the microvessels and a sparse matrix solver is used to obtain the solution. The simulations use realistic vessel topology for the microvasculature, reconstructed from microscope images of tissue samples, and consider blood rheology as well as passive and active vessel properties.

  18. DSMC-LBM hybrid scheme for flows with variable rarefaction conditions

    NASA Astrophysics Data System (ADS)

    di Staso, Gianluca; Succi, Sauro; Toschi, Federico; Clercx, Herman

    2015-11-01

    The kinetic description of gases, based on the Boltzmann equation, allows to cover flow regimes ranging from the rarefied to the continuum limit. The two limits are traditionally studied by numerically approximating the Boltzmann equation via Direct Simulation Monte Carlo (DSMC) method or the Lattice Boltzmann Equation method (LBM). While DSMC is suitable for rarefied flows, its computational cost makes it unpractical to study hydrodynamic flows. The LBM has instead proved itself to be an efficient and accurate method in the hydrodynamic limit even though simulation of rarefied flows requires additional modeling. Here, results on the development of a hybrid scheme capable of coupling the LBM and the DSMC methods and able to efficiently simulate flows with variable rarefaction conditions are presented. The coupling scheme is based on Grad's moment method approach and the local single particle distribution function at a given order of truncation is built by using the Hermite polynomials expansion approach and Gauss-Hermite quadratures. The capabilities of the hybrid approach for simulating flows in the transition regime are illustrated in the case of planar Couette and Poiseuille flows.

  19. Muscle-specific vascular endothelial growth factor deletion induces muscle capillary rarefaction creating muscle insulin resistance.

    PubMed

    Bonner, Jeffrey S; Lantier, Louise; Hasenour, Clinton M; James, Freyja D; Bracy, Deanna P; Wasserman, David H

    2013-02-01

    Muscle insulin resistance is associated with a reduction in vascular endothelial growth factor (VEGF) action and muscle capillary density. We tested the hypothesis that muscle capillary rarefaction critically contributes to the etiology of muscle insulin resistance in chow-fed mice with skeletal and cardiac muscle VEGF deletion (mVEGF(-/-)) and wild-type littermates (mVEGF(+/+)) on a C57BL/6 background. The mVEGF(-/-) mice had an ~60% and ~50% decrease in capillaries in skeletal and cardiac muscle, respectively. The mVEGF(-/-) mice had augmented fasting glucose turnover. Insulin-stimulated whole-body glucose disappearance was blunted in mVEGF(-/-) mice. The reduced peripheral glucose utilization during insulin stimulation was due to diminished in vivo cardiac and skeletal muscle insulin action and signaling. The decreased insulin-stimulated muscle glucose uptake was independent of defects in insulin action at the myocyte, suggesting that the impairment in insulin-stimulated muscle glucose uptake was due to poor muscle perfusion. The deletion of VEGF in cardiac muscle did not affect cardiac output. These studies emphasize the importance for novel therapeutic approaches that target the vasculature in the treatment of insulin-resistant muscle. PMID:23002035

  20. Compressive and rarefactive ion acoustic solitons in a magnetized two-ion component plasma

    NASA Astrophysics Data System (ADS)

    Ur-Rehman, Hafeez; Mahmood, S.; Aman-ur-Rehman

    2014-10-01

    The formation of compressive (hump) and rarefactive (dip) ion acoustic solitons is studied in magnetized O+- H+- e and O+- H-- e plasmas. The hydrodynamics equations are described for cold heavy (oxygen) ions, warm light (hydrogen) ions and isothermal Boltzmann distributed electrons along with Poisson equations in the presence of a magnetic field. The reductive perturbation method is used to derive the nonlinear Zakharov-Kuznetsov (ZK) equation for an ion acoustic wave in magnetized two-ion component plasma. It is found that two modes of ion acoustic waves with fast and slow speeds can propagate in the linear limit in such a plasma. It is noticed that, in the case of positively charged light hydrogen ions O+- H+- e plasmas, the slow ion acoustic wave solitons formed both potential hump as well as dip structures, while fast ion acoustic wave solitons give only hump structures. However in the case of negatively charged light hydrogen ions O+- H-- e plasmas, the slow ion acoustic wave solitons formed potential hump structures while fast ion acoustic wave solitons produce dip structures. The variations in the amplitude and width of the nonlinear slow and fast ion acoustic wave structures with density, temperature of light ions and magnetic field intensity are obtained in magnetized two-ion component plasmas. The magnetic field has its effect only on the width of the nonlinear ion acoustic wave structures in two-ion component plasmas.

  1. Residual gas entering high density hydrogen plasma: rarefaction due to rapid heating

    NASA Astrophysics Data System (ADS)

    Den Harder, N.; Schram, D. C.; Goedheer, W. J.; De Blank, H. J.; Van de Sanden, M. C. M.; Van Rooij, G. J.

    2015-04-01

    The interaction of background molecular hydrogen with magnetized (0.4 T) high density (1-5 × 1020 m-3) low temperature (˜3 eV) hydrogen plasma was inferred from the Fulcher band emission in the linear plasma generator Pilot-PSI. In the plasma center, vibrational temperatures reached 1 eV. Rotational temperatures obtained from the Q(v = 1) branch were systematically ˜0.1 eV lower than the Q(v = 0) branch temperatures, which were in the range of 0.4-0.8 eV, typically 60% of the translational temperature (determined from the width of the same spectral lines). The latter is attributed to preferential excitation of translational degrees of freedom in collisions with ions on the timescale of their in-plasma residence time. Doppler shifts revealed co-rotation of the molecules with the plasma at an angular velocity an order of magnitude lower, confirming that the Fulcher emission connects to background molecules. A simple model estimated a factor of 90 rarefaction of the molecular density at the center of the plasma column compared to the residual gas density. Temperature and density information was combined to conclude that ion-conversion molecular assisted recombination dominates plasma recombination at a rate of 1 × 10-15 m3 s-1. The observations illustrate the general significance of rapid molecule heating in high density hydrogen plasma for estimating molecular processes and how this affects Fulcher spectroscopy.

  2. ADZE: a rarefaction approach for counting alleles private to combinations of populations

    PubMed Central

    Szpiech, Zachary A.; Jakobsson, Mattias; Rosenberg, Noah A.

    2008-01-01

    Motivation: Analysis of the distribution of alleles across populations is a useful tool for examining population diversity and relationships. However, sample sizes often differ across populations, sometimes making it difficult to assess allelic distributions across groups. Results: We introduce a generalized rarefaction approach for counting alleles private to combinations of populations. Our method evaluates the number of alleles found in each of a set of populations but absent in all remaining populations, considering equal-sized subsamples from each population. Applying this method to a worldwide human microsatellite dataset, we observe a high number of alleles private to the combination of African and Oceanian populations. This result supports the possibility of a migration out of Africa into Oceania separate from the migrations responsible for the majority of the ancestry of the modern populations of Asia, and it highlights the utility of our approach to sample size correction in evaluating hypotheses about population history. Availability: We have implemented our method in the computer pro-gram ADZE, which is available for download at http://rosenberglab.bioinformatics.med.umich.edu/adze.html. Contact: szpiechz@umich.edu PMID:18779233

  3. Morphologic study of microcirculation in acromegaly by capillaroscopy.

    PubMed

    Schiavon, F; Maffei, P; Martini, C; De Carlo, E; Fais, C; Todesco, S; Sicolo, N

    1999-09-01

    Although wide range investigations on the heart and great vessels have been reported in acromegaly, the field of microcirculation is still largely vacant. The nailfold is a window through which we can observe in vivo the vascular bed. This study investigates through nailfold capillaroscopy the morphology of cutaneous microcirculation in acromegaly in relationship with the usual hormonal parameters of disease activity. Twenty-five acromegalic patients and 26 normal subjects, age and sex matched, were studied. A subgroup of acromegalics (8 patients) was considered in stable remission, and the remaining 17 had active disease. Capillaroscopy was performed in each subject by in vivo computer aided stereomicroscopy (magnification, x400). The following morphological parameters were calculated: the number of tortuous loops, meandering capillaries, and capillaries per millimeter; avascular areas; visibility of subpapillary plexus; the capillary length; and intercapillary distance. We were unable to perform the exam in 4 of 25 patients because visibility was poor. The capillary number and length were significantly reduced in acromegalics compared to controls [8.9 +/- 1.5 vs. 10.3 +/- 1.2 no./mm (P = 0.0010) and 174 +/- 49 vs. 255 +/- 24 microm (P < 0.0001)]. Moreover, in acromegalics, the numbers of tortuous loops and meandering capillaries were significantly increased [19 +/- 8 vs. 13 +/- 5 (P = 0.0027) and 10 +/- 12 vs. 0.7 +/- 1.1 (P < 0.0001)]. The capillaroscopic alterations were still observed in a smaller group of 8 nondiabetic and nonhypertensive acromegalics. We found branch-like capillaries in 4 acromegalic patients, but not in the control group. Finally, we observed a meaningful different and ameliorated capillaroscopic morphology in acromegalic patients in stable remission compared to active disease patients as far as the total number (density) and meandering capillaries were concerned. In conclusion, our study shows that in acromegaly, morphological alterations

  4. Alpha adrenoceptors in the rabbit ear thermoregulatory microcirculation.

    PubMed

    Li, Z; Koman, L A; Smith, B P; Gordon, E S; Smith, T L

    1998-03-01

    The rabbit ear microcirculation was analyzed in a chronic unanesthetized model to evaluate alpha adrenergic microvascular control in a thermoregulatory end organ. This model allowed direct measurement of microcirculatory responses without the effects of anesthetics or inflammatory responses induced by acute surgical intervention. The ipsilateral facial artery was catheterized for drug injections into the experimental ear. Microvascular diameter changes following stimulation or blockade of adrenoceptor (AR) subtypes were observed directly through a chronic microvascular chamber implanted in the rabbit ear. Vascular alpha1- and alpha2-ARs appear to be distributed differently across the arterioles and AVAs of the rabbit ear. Both alpha1- and alpha2-ARs appear to contribute to vasoconstriction of AVAs in the conscious rabbit ear. In contrast, alpha1-AR's (vs alpha2-ARs) appear to predominate in adrenergically mediated sympathetic vasoconstriction of arterioles. PMID:9521886

  5. Influence of topically applied antimicrobial agents on muscular microcirculation.

    PubMed

    Goertz, Ole; Hirsch, Tobias; Ring, Andrej; Steinau, Hans U; Daigeler, Adrien; Lehnhardt, Marcus; Homann, Heinz H

    2011-10-01

    Bacterial infections cause major complications in wound healing. Local antiseptics are used for daily wound care; however, their potential toxic effects on the vasculature have not yet been thoroughly investigated. The aim of this study was to assess the effects of antiseptics on microcirculation. Investigations were performed on a standardized cremaster muscle model on rats (n = 60). The arteriolar diameter and functional capillary density (FCD) were investigated using transillumination microscopy before and 60 and 120 minutes after application of each of the following antimicrobial agents: alcohol, hydrogen peroxide, imipenem, octenidine dihydrochloride, polyhexanide, and ethacridine lactate. Although polyhexanide caused a significant arteriolar dilatation (106.25 ± 3.23 vs. 88.54 ± 6.74 μm [baseline value]) and increase of FCD compared with baseline value (12.65 ± 0.82 vs. 9.10 ± 0.50 n/0.22 mm), alcohol led to a significant decrease of both parameters (90.63 ± 10.80 vs. 52.09 ± 7.69 and 5.35 ± 0.54 vs. 1.68 ± 0.48) and was the only agent that caused arteriolar thrombosis. The FCD also increased significantly after treatment with hydrogen peroxide (10.55 ± 0.33 vs. 12.30 ± 0.48) and octenidine (6.82 ± 0.63 vs. 12.32 ± 0.63). However, no positive effect on arteriolar diameter could be found. Ethacridine lactate and imipenem did not impact either parameter. In addition to reducing bacteria, an antiseptic should be nontoxic, especially to the microcirculation. Polyhexanide seems to have a positive influence on vessel diameter and capillary density, whereas alcohol reduces both parameters. If the antimicrobial efficacy is comparable, the antiseptic with less toxic effects should be chosen, especially in critically perfused wounds.

  6. The microcirculation in hypoxia: The center of the battlefield for oxygen.

    PubMed

    Jung, Christian; Jung, Friedrich; Kelm, Malte

    2016-09-12

    In the past years the microcirculation has gained increasing attention not only by basic scientists, but also by clinicians and translational researchers. In the clinical scenario, it has been convincingly described that the microcirculation is a key predictor of outcome and of central pathophysiological relevance. A vast body of evidence demonstrates the central role of the smallest vessels in inflammation, hyperviscosity, cell-cell-interaction, endothelial function, tissue edema, hemodynamic and blood flow regulation and its important role in the interaction with soluble factors. A central feature of different diseases and a strong regulator of different changes is hypoxia, the lack of oxygen. Also the microcirculation is on one hand a central component responding with dynamic changes to hypoxia but also the central place where hypoxia mediates its unfavorable effects. These changes and associated interactions are the topic of this special thematic issue "Hypoxia" in Clinical Hemorheology and Microcirculation and it seems logical that important and relevant findings are presented. PMID:27567802

  7. Low Intensity Laser Therapy (LILT) Versus Transcutaneous Electrical Nerve Stimulation On Microcirculation In Diabetic Neuropathy

    NASA Astrophysics Data System (ADS)

    Battecha, Kadria H.; Atya, Azza M.

    2011-09-01

    Reduced microcirculation is a morbid element of neuropathy and one of the most common complications of uncontrolled diabetes. Many physical modalities have gained a considerable attention for enhancing cutaneous microcirculation in diabetic patients and prevent its serious complications. Accordingly, the present study was conducted to compare between the effect of low intensity laser therapy (LILT) and transcutaneous electrical nerve stimulation (TENS) on microcirculation in diabetic neuropathy. Thirty diabetic polyneuropathic patients ranged in age from 45-60 years participated in this study. They were randomly divided into two groups of equal number; patients in group (A) received LILT on plantar surface of foot with a dose of 3 J/cm2 and wavelength (904 nm), while those in group (B) received TENS on lower leg for 30 minutes with frequency (2 HZ). Treatment was conducted 3 times/week for 6 weeks. The cutaneous microcirculation was evaluated by Laser Doppler flowmetry at the baseline and at the end of treatment. Results revealed that group (A) showed statistically significant increase in the cutaneous microcirculation compared with group (B). So, it was concluded that LILT has to be more efficient than TENS in increasing cutaneous microcirculation in patients with diabetic neuropathy.

  8. More Than the Rules of Precedence

    ERIC Educational Resources Information Center

    Liang, Yawei

    2005-01-01

    In a fundamental computer-programming course, such as CSE101, questions about how to evaluate an arithmetic expression are frequently used to check if our students know the rules of precedence. The author uses two of our final examination questions to show that more knowledge of computer science is needed to answer them correctly. Furthermore,…

  9. PWORLD: A Precedent-Based Global Simulation.

    ERIC Educational Resources Information Center

    Schrodt, Philip A.

    A "world model" is constructed where precedent-searching is one of the primary driving mechanisms. The simulation assumes that nations in the system are utility maximizers but that they have relatively primitive decision mechanisms and that they are strongly influenced by their previous short-term successful behavior and the short-term success of…

  10. On the Rhetoric and Precedents of Racism.

    ERIC Educational Resources Information Center

    Villanueva, Victor

    1999-01-01

    Considers contribution of rhetorical training of the Aztecs prior to the European conquest as well as other early philosophers from the Americas. Encourages breaking precedent in order to battle racism by looking to rhetorical training developed in the Americas and Puerto Rico in addition to the European thinkers. (SC)

  11. Sleep Disturbance Preceding Completed Suicide in Adolescents

    ERIC Educational Resources Information Center

    Goldstein, Tina R.; Bridge, Jeffrey A.; Brent, David A.

    2008-01-01

    We examined sleep difficulties preceding death in a sample of adolescent suicide completers as compared with a matched sample of community control adolescents. Sleep disturbances were assessed in 140 adolescent suicide victims with a psychological autopsy protocol and in 131 controls with a similar semistructured psychiatric interview. Rates of…

  12. Thrombotic thrombocytopenic purpura preceding systemic lupus erythematosus.

    PubMed Central

    Simeon-Aznar, C P; Cuenca-Luque, R; Fonollosa-Pla, V; Bosch-Gil, J A

    1992-01-01

    The case of a patient admitted with thrombotic thrombocytopenic purpura nine years after developing systemic lupus erythematosus (SLE) is reported. Thrombotic thrombocytopenic purpura associated with SLE has been described on other occasions, but in most patients the diagnosis of SLE precedes that of thrombotic thrombocytopenic purpura. The unusual sequence and the chronological separation of the two diseases is emphasised. PMID:1575591

  13. Targeting of the tumor microcirculation with a new photosensitizer

    NASA Astrophysics Data System (ADS)

    Abels, Christoph; Dellian, Marc; Szeimies, Rolf-Markus; Steinbach, Pia; Richert, C.; Goetz, Alwin E.

    1996-01-01

    Tumors are characterized by an insufficient neoangiogenesis. Therefore targeting of the fragile tumor microcirculation by photodynamic therapy (PDT) may induce easily tumor ischemia leading to tumor necrosis. Nine-acetoxy-2,7,12,17-tetrakis-((beta) -methoxyethyl)- prophycene (ATMPn) is a chemically pure, lipophilic substance and revealed superior photodynamic characteristics in vitro as compared to PhotofrinR. In this study pharmacokinetics, photodynamic effects and localization of ATMPn incorporated in small unilamellar liposomes in tumor and surrounding normal tissue were evaluated. Amelanotic melanomas (A-Mel-3) were implanted in dorsal skin fold chambers fitted to Syrian Golden hamsters (70 - 80 g b.w.). Fluorescence kinetics of ATMPn administered intravenously (1.4 micrometers ol/kg b.w.; n equals 8) were monitored by intravital microscopy. Quantitative measurements of fluorescence intensity were carried out by digital image analysis. For tumor growth studies 1.4 micrometers ol/kg was injected 24 h (n equals 3), 3 h (n equals 3), 1 min (n equals 6) and 2.8 micrometers ol/kg 1 min (n equals 6) before PDT (630 nm, 100 mW/cm2, 100 J/cm2). Tumor growth was measured over 28 days. Solid tumors (n equals 3) were excised 1 min after injection of ATMPn (1.4 micrometers ol/kg) and cryostat sections (10 micrometers) were analyzed by confocal laser scanning microscopy (CSLM) to determine tissue localization of dye. Maximal fluorescence (mean plus or minus S.E.) arose in tumor (94 plus or minus 7%) and surrounding host tissue (67 plus or minus 5%) 30 s post injection followed by a rapid decrease. Hardly any fluorescence was detectable after 12 h. Only PDT 1 min after injection of ATMPn was effective yielding 1/6 complete remission (1.4 micrometers ol/kg) and 3/6 complete remissions (2.8 mmol/kg), respectively. At that time dye is primarily localized in vessels and vessel walls as shown by CSLM. ATMPn in liposomes reveals very rapid kinetics thus suitable for intraoperative

  14. Rarefactive and compressive soliton waves in unmagnetized dusty plasma with non-thermal electron and ion distribution

    SciTech Connect

    Eslami, Esmaeil Baraz, Rasoul

    2014-02-15

    Sagdeev's pseudo potential method is employed to study dust acoustic solitary waves in an unmagnetized plasma containing negatively charged dusts with non-thermal electron and ion. The range of parameters for the existence of solitary waves using the analytical expression of the Sagdeev potential has been found. It is observed that, depending on the values of the plasma parameters like ion to electron temperature ratio σ, non-thermal parameters β and γ, electron to ion density ratio μ, and the value of the Mach number M, both rarefactive and compressive solitary waves may exist.

  15. Comment on "Electrostatic compressive and rarefactive shocks and solitons in relativistic plasmas occurring in polar regions of pulsar"

    NASA Astrophysics Data System (ADS)

    Hafez, M. G.; Talukder, M. R.; Hossain Ali, M.

    2016-05-01

    The aim of this comment is to show the solution of the KdVB equation used by Shah et al. (Astrophys. Space Sci. 335:529-537, 2011, doi: 10.1007/s10509-011-0766-y) is not correct. So, the numerical results that are predicted in this manuscript should not be helpful for further investigations in a plasma laboratory. For this reason, we have employed the Bernoulli's equation method to obtain the correct form of analytical solution to this equation, which is appropriate for the study of electrostatic compressive and rarefactive shocks and solitons in relativistic plasmas occurring in polar regions of pulsar.

  16. INTERVALS OF RADIAL INTERPLANETARY MAGNETIC FIELDS AT 1 AU, THEIR ASSOCIATION WITH RAREFACTION REGIONS, AND THEIR APPARENT MAGNETIC FOOT POINTS AT THE SUN

    SciTech Connect

    Orlove, Steven T.; Smith, Charles W.; Vasquez, Bernard J.; Schwadron, Nathan A.; Skoug, Ruth M.; Zurbuchen, Thomas H.; Zhao Liang E-mail: Charles.Smith@unh.edu E-mail: N.Schwadron@unh.edu E-mail: thomasz@umich.edu

    2013-09-01

    We have examined 226 intervals of nearly radial interplanetary magnetic field orientations at 1 AU lasting in excess of 6 hr. They are found within rarefaction regions as are the previously reported high-latitude observations. We show that these rarefactions typically do not involve high-speed wind such as that seen by Ulysses at high latitudes during solar minimum. We have examined both the wind speeds and the thermal ion composition before, during and after the rarefaction in an effort to establish the source of the flow that leads to the formation of the rarefaction. We find that the bulk of the measurements, both fast- and slow-wind intervals, possess both wind speeds and thermal ion compositions that suggest they come from typical low-latitude sources that are nominally considered slow-wind sources. In other words, we find relatively little evidence of polar coronal hole sources even when we examine the faster wind ahead of the rarefaction regions. While this is in contrast to high-latitude observations, we argue that this is to be expected of low-latitude observations where polar coronal hole sources are less prevalent. As with the previous high-latitude observations, we contend that the best explanation for these periods of radial magnetic field is interchange reconnection between two sources of different wind speed.

  17. Numerical Simulation of Sickle Cell Blood Flow in the Microcirculation

    NASA Astrophysics Data System (ADS)

    Berger, Stanley A.; Carlson, Brian E.

    2001-11-01

    A numerical simulation of normal and sickle cell blood flow through the transverse arteriole-capillary microcirculation is carried out to model the dominant mechanisms involved in the onset of vascular stasis in sickle cell disease. The transverse arteriole-capillary network is described by Strahler's network branching method, and the oxygen and blood transport in the capillaries is modeled by a Krogh cylinder analysis utilizing Lighthill's lubrication theory, as developed by Berger and King. Poiseuille's law is used to represent blood flow in the arterioles. Applying this flow and transport model and utilizing volumetric flow continuity at each network bifurcation, a nonlinear system of equations is obtained, which is solved iteratively using a steepest descent algorithm coupled with a Newton solver. Ten different networks are generated and flow results are calculated for normal blood and sickle cell blood without and with precapillary oxygen loss. We find that total volumetric blood flow through the network is greater in the two sickle cell blood simulations than for normal blood owing to the anemia associated with sickle cell disease. The percentage of capillary blockage in the network increases dramatically with decreasing pressure drop across the network in the sickle cell cases while there is no blockage when normal blood flows through simulated networks. It is concluded that, in sickle cell disease, without any vasomotor dilation response to decreasing oxygen concentrations in the blood, capillary blockage will occur in the microvasculature even at average pressure drops across the transverse arteriole-capillary networks.

  18. Microvascular Transport and Tumor Cell Adhesion in the Microcirculation

    PubMed Central

    Fu, Bingmei M.; Liu, Yang

    2016-01-01

    One critical step in tumor metastasis is tumor cell adhesion to the endothelium forming the microvessel wall. Understanding this step may lead to new therapeutic concepts for tumor metastasis. Vascular endothelium forming the microvessel wall and the glycocalyx layer at its surface are the principal barriers to, and regulators of the material exchange between circulating blood and body tissues. The cleft between adjacent ECs (interendothelial cleft) is the principal pathway for water and solutes transport through the microvessel wall in health. It is also suggested to be the pathway for high molecular weight plasma proteins, leukocytes and tumor cells across microvessel walls in disease. Thus the first part of the review introduced the mathematical models for water and solutes transport through the interendothelial cleft. These models, combined with the experimental results from in vivo animal studies and electron microscopic observations, are used to evaluate the role of the endothelial surface glycocalyx, the junction strand geometry in the interendothelial cleft, and the surrounding extracellular matrix and tissue cells, as the determinants of microvascular transport. The second part of the review demonstrated how the microvascular permeability, hydrodynamic factors, microvascular geometry and cell adhesion molecules affect tumor cell adhesion in the microcirculation. PMID:22476895

  19. Age-related changes in skin topography and microcirculation.

    PubMed

    Li, Li; Mac-Mary, Sophie; Marsaut, David; Sainthillier, Jean Marie; Nouveau, Stéphanie; Gharbi, Tijani; de Lacharriere, Olivier; Humbert, Philippe

    2006-03-01

    Skin topography and microvasculature undergo characteristic changes with age. Although several non-invasive bioengineering methods are currently available to measure them quantitatively, few publications have referred to their relationship with age in different anatomical sites. This study was carried out to observe the age-related changes of the skin topography and skin microcirculation. The microrelief was assessed with special processing software from scanning by interference fringe profilometry of silicone replicas performed on two sites (volar forearm and back of hand) on 50 female volunteers (aged 20-74 years who consisted of ten probands in each decade). The superficial vascular network of both sites was assessed by videocapillaroscopy, and the subpapillary vascular plexus was studied with laser Doppler flowmetry. Skin color, which is affected by blood flow, was observed by colorimeter. The skin roughness and the mean height between peak and valley increased with age. There were statistically significant differences between the evaluated sites. This study also shows that the capillary loops in the dermal papillae decrease but the subpapillary plexus increase with age. The interference fringe profilometry associated with videocapillaroscopy may be useful and accurate to measure the efficacy of medical or cosmetic products to delay skin aging.

  20. Microcirculation and atherothrombotic parameters in prolactinoma patients: a pilot study.

    PubMed

    Reuwer, Anne Q; Sondermeijer, Brigitte M; Battjes, Suzanne; van Zijderveld, Rogier; Stuijver, Danka J F; Bisschop, Peter H; Twickler, Marcel Th B; Meijers, Joost C M; Schlingemann, Reinier O; Stroes, Erik S

    2012-12-01

    Atherothrombosis is a multifactorial process, governed by an interaction between the vessel wall, hemodynamic factors and systemic atherothrombotic risk factors. Recent in vitro, human ex vivo and animal studies have implicated the hormone prolactin as an atherothrombotic mediator. To address this issue, we evaluated the anatomy and function of various microvascular beds as well as plasma atherothrombosis markers in patients with elevated prolactin levels. In this pilot study, involving 10 prolactinoma patients and 10 control subjects, sidestream dark field (SDF) imaging revealed a marked perturbation of the sublingual microcirculation in prolactinoma patients compared to control subjects, as attested to by significant changes in microvascular flow index (2.74 ± 0.12 vs. 2.91 ± 0.05, respectively; P = 0.0006), in heterogeneity index (0.28 [IQR 0.18-0.31] vs. 0.09 [IQR 0.08-0.17], respectively; P = 0.002) and lower proportion of perfused vessels (90 ± 4.0% vs. 95 ± 3.0%, respectively; P = 0.016). In the retina, fluorescein angiography (FAG) confirmed these data, since prolactinoma patients more often have dilatated perifoveal capillaries. In plasma, prolactinoma patients displayed several pro-atherogenic disturbances, including a higher endogenous thrombin potential and prothrombin levels as well as decreased HDL-cholesterol levels. Prolactinoma patients are characterized by microvascular dysfunction as well as plasma markers indicating a pro-atherothrombotic state. Further studies are required to assess if prolactin is causally involved in atherothrombotic disease.

  1. Blood substitutes and redox responses in the microcirculation.

    PubMed

    Baldwin, Ann L

    2004-12-01

    Transfusion of hemoglobin-based blood substitutes, designed for their plasma expansion and oxygen transport capabilities, has resulted in some major problems, such as organ dysfunction, during clinical trials. Experimental evidence demonstrates that these hemoglobins damage tissue by producing highly reactive oxygen species. Although cell-free hemoglobin may present a low risk to people with normal redox status, patients who are sick and have a poor antioxidant status may be at risk. Oxidative damage is particularly dangerous in the microcirculation because excess leakage of plasma components into the interstitium will disturb the fluid balance between blood and tissue and alter the kinetics of delivery of intravascularly injected drugs, and endogenous enzymes and hormones, to various tissues. In this review, the redox chemistry of hemoglobin-based blood substitutes is briefly described, and their effects on cultured endothelial cells, and on the exchange properties of the microvasculature, are discussed. Taking into account the possible mechanisms by which oxidative damage can occur, various methods to reduce the deleterious effects of blood substitutes in vivo are evaluated. Finally, several possible cell signaling pathways that are triggered in endothelial cells, in response to modified hemoglobins, are considered in terms of protecting microvascular function.

  2. Patterns of seismic activity preceding large earthquakes

    NASA Technical Reports Server (NTRS)

    Shaw, Bruce E.; Carlson, J. M.; Langer, J. S.

    1992-01-01

    A mechanical model of seismic faults is employed to investigate the seismic activities that occur prior to major events. The block-and-spring model dynamically generates a statistical distribution of smaller slipping events that precede large events, and the results satisfy the Gutenberg-Richter law. The scaling behavior during a loading cycle suggests small but systematic variations in space and time with maximum activity acceleration near the future epicenter. Activity patterns inferred from data on seismicity in California demonstrate a regional aspect; increased activity in certain areas are found to precede major earthquake events. One example is given regarding the Loma Prieta earthquake of 1989 which is located near a fault section associated with increased activity levels.

  3. Threshold of the precedence effect in noise

    PubMed Central

    Freyman, Richard L.; Griffin, Amanda M.; Zurek, Patrick M.

    2014-01-01

    Three effects that show a temporal asymmetry in the influence of interaural cues were studied through the addition of masking noise: (1) The transient precedence effect—the perceptual dominance of a leading transient over a similar lagging transient; (2) the ongoing precedence effect—lead dominance with lead and lag components that extend in time; and (3) the onset capture effect—determination by an onset transient of the lateral position of an otherwise ambiguous extended trailing sound. These three effects were evoked with noise-burst stimuli and were compared in the presence of masking noise. Using a diotic noise masker, detection thresholds for stimuli with lead/lag interaural delays of 0/500 μs were compared to those with 500/0 μs delays. None of the three effects showed a masking difference between those conditions, suggesting that none of the effects is operative at masked threshold. A task requiring the discrimination between stimuli with 500/0 and 0/500 μs interaural delays was used to determine the threshold for each effect in noise. The results showed similar thresholds in noise (10–13 dB SL) for the transient and ongoing precedence effects, but a much higher threshold (33 dB SL) for onset capture of an ambiguous trailing sound. PMID:24815272

  4. Dysfunctional Microcirculation of the Lumbar Vertebral Marrow Prior to the Bone Loss and Intervertebral Discal Degeneration

    PubMed Central

    Lu, Guang-ming

    2015-01-01

    Study Design. Descriptive study, stratified sampling. Objective. Using dynamic computed tomographic perfusion (CTP) to explore the age-related distribution patterns of the microcirculation perfusion in the vertebral marrow, the vertebral bone mineral density (BMD), and the intervertebral discal degeneration (IDD) further to discuss the possible causation between them. Summary of Background Data. A latest viewpoint deemed that reduced blood supply of the vertebral marrow was correlated with an increased incidence of IDD and loss of BMD. However, the causative relationship between them needs more investigation. Methods. One hundred eighty-six general people were randomly enrolled by stratified sampling and grouped by age: 15 years or less, 16 to 25 years, 26 to 35 years, 36 to 45 years, 46 to 55 years, 56 to 65 years, 66 to 75 years, and 76 years or more. Both CTP and BMD of the third and fourth lumbar vertebral marrow were measured, and the IDD incidence of the third-fourth vertebrae was assessed. The temporal-spatial distribution patterns of the age-related changes of CTP, BMD, and IDD were described, and the correlations between them were calculated. Results. Microcirculatory perfusion of the vertebral marrow developed to maturate by 25 years, maintained stable at 35 years, and then declined by age after 35 years. BMD grew to a peak phase in 26 to 45 years and then dropped by years. However, IDD presented a sudden increase after 45 years of age. CTP (blood flow [r = 0.806], blood volume [r = 0.685], and permeability [r = 0.619]) showed strong positive correlations and CTP (time to peak [r = −0.211], mean transit time [r = −0.598]) showed negative correlations with BMD. Meanwhile, CTP (blood flow [r = −0.815], blood volume [r = −0.753], and permeability [r = −0.690]) had strong negative correlations and CTP (time to peak [r = 0.323] and mean transit time [r = 0.628]) had positive correlations with the incidence of IDD. Conclusion. Aging-related decrease

  5. The diagnosis of lymph microcirculation in experimental studies on rat mesentery in vivo

    NASA Astrophysics Data System (ADS)

    Galanzha, Ekateryna I.; Tuchin, Valery V.; Zharov, Vladimir P.; Solovieva, Anastasia V.; Stepanova, Tatyana V.; Brill, Gregory E.

    2003-07-01

    The many biological and medical problems associated with microlymphatic functioning and its disturbances at different diseases, include primary and secondary lymphedema, inflammation, lymphatic malformations, and so on. It is important both to establish an adequate animal model for study lymph microcirculation in vivo and to match it with corresponding diagnostic techniques. The rat mesentery has been successfully used in experiments focusing on the microcirculation, including small lymphatics. Among optical methods the transmittance microscopy is most widely employed to study microcirculation. We have undertaken following investigations: development and evaluation of capability of transmission microscopy for in vivo studies of microcirculation; obtaining of single cell images; estimation of lymph microcirculation parameters, including the relation of forward to backward flow in intact lymphatics; regulation of microlymphatic function by nitric oxide and study of microlymphatic disturbances at the experimental lymphedema. Although interesting data has been obtained, the transmission microscopy has the relatively low absorption sensitivity and prevents obtaining good absorption contrast. To obtain more comprehensive physiological data, the further development and improvement imaging of rat mesentery is discussed with focus on new combined optical imaging systems which integrate recent advances in video-transmission and photothermal (PT) microscopy, PT fluid velocimetry, and laser spectroscopy.

  6. In vivo assessment of the structure of skin microcirculation by reflectance confocal-laser-scanning microscopy

    NASA Astrophysics Data System (ADS)

    Sugata, Keiichi; Osanai, Osamu; Kawada, Hiromitsu

    2012-02-01

    One of the major roles of the skin microcirculation is to supply oxygen and nutrition to the surrounding tissue. Regardless of the close relationship between the microcirculation and the surrounding tissue, there are few non-invasive methods that can evaluate both the microcirculation and its surrounding tissue at the same site. We visualized microcapillary plexus structures in human skin using in vivo reflectance confocal-laser-scanning microscopy (CLSM), Vivascope 3000® (Lucid Inc., USA) and Image J software (National Institutes of Health, USA) for video image processing. CLSM is a non-invasive technique that can visualize the internal structure of the skin at the cellular level. In addition to internal morphological information such as the extracellular matrix, our method reveals capillary structures up to the depth of the subpapillary plexus at the same site without the need for additional optical systems. Video images at specific depths of the inner forearm skin were recorded. By creating frame-to-frame difference images from the video images using off-line video image processing, we obtained images that emphasize the brightness depending on changes of intensity coming from the movement of blood cells. Merging images from different depths of the skin elucidates the 3-dimensional fine line-structure of the microcirculation. Overall our results show the feasibility of a non-invasive, high-resolution imaging technique to characterize the skin microcirculation and the surrounding tissue.

  7. Characterization of nanoparticle delivery in microcirculation using a microfluidic device.

    PubMed

    Thomas, Antony; Tan, Jifu; Liu, Yaling

    2014-07-01

    This work focuses on the characterization of particle delivery in microcirculation through a microfluidic device. In microvasculature the vessel size is comparable to that of red blood cells (RBCs) and the existence of blood cells largely influences the dispersion and binding distribution of drug loaded particles. The geometry of the microvasculature leads to non-uniform particle distribution and affects the particle binding characteristics. We perform an in vitro study in a microfluidic chip with micro vessel mimicking channels having a rectangular cross section. Various factors that influence particle distribution and delivery such as the vessel geometry, shear rate, blood cells, particle size, particle antibody density are considered in this study. Around 10% higher particle binding density is observed at bifurcation regions of the mimetic microvasculature geometry compared to straight regions. Particle binding density is found to decrease with increased shear rates. RBCs enhance particle binding for both 210 nm and 2 μm particles for shear rates between 200-1600 s(-1) studied. The particle binding density increases about 2-3 times and 6-10 times when flowing in whole blood at 25% RBC concentration compared to the pure particle case, for 210 nm and 2 μm particles respectively. With RBCs, the binding enhancement is more significant for 2 μm particles than that for 210 nm particles, which indicates an enhanced size dependent exclusion of 2 μm particles from the channel centre to the cell free layer (CFL). Increased particle antibody coating density leads to higher particle binding density for both 210 nm and 2 μm particles. PMID:24788074

  8. Oral lichen planus preceding concomitant lichen planopilaris.

    PubMed

    Stoopler, Eric T; Alfaris, Sausan; Alomar, Dalal; Alawi, Faizan

    2016-09-01

    Lichen planus (LP) is an immune-mediated mucocutaneous disorder with a wide array of clinical presentations. Oral lichen planus (OLP) is characterized clinically by striae, desquamation, and/or ulceration. Lichen planopilaris (LPP), a variant of LP, affects the scalp, resulting in perifollicular erythema and scarring of cutaneous surfaces accompanied by hair loss. The association between OLP and LPP has been reported previously with scant information on concomitant or sequential disease presentation. We describe a patient with concomitant OLP and LPP, and to the best of our knowledge, this is the first report on OLP preceding the onset of LPP. PMID:27544399

  9. The NRF2 knockout rat: a new animal model to study endothelial dysfunction, oxidant stress, and microvascular rarefaction.

    PubMed

    Priestley, Jessica R C; Kautenburg, Katie E; Casati, Marc C; Endres, Bradley T; Geurts, Aron M; Lombard, Julian H

    2016-02-15

    Nuclear factor (erythroid-derived 2)-like-2 (NRF2) is a master antioxidant and cell protective transcription factor that upregulates antioxidant defenses. In this study we developed a strain of Nrf2 null mutant rats to evaluate the role of reduced NRF2-regulated antioxidant defenses in contributing to endothelial dysfunction and impaired angiogenic responses during salt-induced ANG II suppression. Nrf2(-/-) mutant rats were developed using transcription activator-like effector nuclease technology in the Sprague-Dawley genetic background, and exhibited a 41-bp deletion that included the start codon for Nrf2 and an absence of immunohistochemically detectable NRF2 protein. Expression of mRNA for the NRF2-regulated indicator enzymes heme oxygenase-1, catalase, superoxide dismutase 1, superoxide dismutase 2, and glutathione reductase was significantly lower in livers of Nrf2(-/-) mutant rats fed high salt (HS; 4% NaCl) for 2 wk compared with wild-type controls. Endothelium-dependent dilation to acetylcholine was similar in isolated middle cerebral arteries (MCA) of Nrf2(-/-) mutant rats and wild-type littermates fed low-salt (0.4% NaCl) diet, and was eliminated by short-term (3 days) HS diet in both strains. Low-dose ANG II infusion (100 ng/kg sc) reversed salt-induced endothelial dysfunction in MCA and prevented microvessel rarefaction in wild-type rats fed HS diet, but not in Nrf2(-/-) mutant rats. The results of this study indicate that suppression of NRF2 antioxidant defenses plays an essential role in the development of salt-induced oxidant stress, endothelial dysfunction, and microvessel rarefaction in normotensive rats and emphasize the potential therapeutic benefits of directly upregulating NRF2-mediated antioxidant defenses to ameliorate vascular oxidant stress in humans. PMID:26637559

  10. [Wide QRS tachycardia preceded by pacemaker spikes].

    PubMed

    Romero, M; Aranda, A; Gómez, F J; Jurado, A

    2014-04-01

    The differential diagnosis and therapeutic management of wide QRS tachycardia preceded by pacemaker spike is presented. The pacemaker-mediated tachycardia, tachycardia fibrillo-flutter in patients with pacemakers, and runaway pacemakers, have a similar surface electrocardiogram, but respond to different therapeutic measures. The tachycardia response to the application of a magnet over the pacemaker could help in the differential diagnosis, and in some cases will be therapeutic, as in the case of a tachycardia-mediated pacemaker. Although these conditions are diagnosed and treated in hospitals with catheterization laboratories using the application programmer over the pacemaker, patients presenting in primary care clinic and emergency forced us to make a diagnosis and treat the haemodynamically unstable patient prior to referral. PMID:23768570

  11. Precedence effects and the evolution of chorusing

    PubMed Central

    Greenfield, M. D.; Tourtellot, M. K.; Snedden, W. A.

    1997-01-01

    The structured choruses produced by rhythmically signalling males in many species of acoustic animals have long-captured the imagination of evolutionary biologists. Though various hypotheses have been forwarded to explain the adaptive significance of such chorusing, none have withstood empirical scrutiny. We suggest instead that alternating and synchronous choruses represent collective epiphenomena resulting from individual males competing to jam each other's signals. These competitions originate in psychoacoustic precedence effects wherein females only orient toward the first call of a sequence, thus selectively favouring males who produce leading calls. Given this perceptual bias, our modelling confirms that a resetting of signal rhythm by neighbours' signals, which generates either alternation or synchrony, is evolutionarily stable provided that resetting includes a relativity adjustment for the velocity of signal transmission and selective attention toward only a subset of signalling neighbours. Signalling strategies in chorusing insects and anurans are consistent with these predicted features.

  12. Cerebral Hypoperfusion Precedes Nausea During Centrifugation

    NASA Technical Reports Server (NTRS)

    Serrador, Jorge M.; Schlegel, Todd T.; Black, F. Owen; Wood, Scott J.

    2004-01-01

    Nausea and motion sickness are important operational concerns for aviators and astronauts. Understanding underlying mechanisms associated with motion sickness may lead to new treatments. The goal of this work was to determine if cerebral blood flow changes precede the development of nausea in motion sick susceptible subjects. Cerebral flow velocity in the middle cerebral artery (transcranial Doppler), blood pressure (Finapres) and end-tidal CO2 were measured while subjects were rotated on a centrifuge (250 degrees/sec). Following 5 min of rotation, subjects were translated 0.504 m off-center, creating a +lGx centripetal acceleration in the nasal-occipital plane. Ten subjects completed the protocol without symptoms while 5 developed nausea (4 while 6ff-center and 1 while rotating on-center). Prior to nausea, subjects had significant increases in blood pressure (+13plus or minus 3 mmHg, P less than 0.05) and cerebrovascular resistance (+46 plus or minus 17%, P less than 0.05) and decreases in cerebral flow velocity both in the second (-13 plus or minus 4%) and last minute (-22 plus or minus 5%) before symptoms (P less than 0.05). In comparison, controls demonstrated no change in blood pressure or cerebrovascular resistance in the last minute of off-center rotation and only a 7 plus or minus 2% decrease in cerebral flow velocity. All subjects had significant hypocapnia (-3.8 plus or minus 0.4 mmHg, P less than 0.05), however this hypocapnia could not fully explain the cerebral hypoperfusion associated with the development of nausea. These data indicate that reductions in cerebral blood flow precede the development of nausea. Further work is necessary to determine what role cerebral hypoperfusion plays in motion sickness and whether cerebral hypoperfusion can be used to predict the development of nausea in susceptible individuals.

  13. Localization of the ANG II type 2 receptor in the microcirculation of skeletal muscle

    NASA Technical Reports Server (NTRS)

    Nora, E. H.; Munzenmaier, D. H.; Hansen-Smith, F. M.; Lombard, J. H.; Greene, A. S.; Cowley, A. W. (Principal Investigator)

    1998-01-01

    Only functional studies have suggested the presence of the ANG II type 2 (AT2) receptor in the microcirculation. To determine the distribution of this receptor in the rat skeletal muscle microcirculation, a polyclonal rabbit anti-rat antiserum was developed and used for immunohistochemistry and Western blot analysis. The antiserum was prepared against a highly specific and antigenic AT2-receptor synthetic peptide and was validated by competition and sensitivity assays. Western blot analysis demonstrated a prominent, single band at approximately 40 kDa in cremaster and soleus muscle. Immunohistochemical analysis revealed a wide distribution of AT2 receptors throughout the skeletal muscle microcirculation in large and small microvessels. Microanatomic studies displayed an endothelial localization of the AT2 receptor, whereas dual labeling with smooth muscle alpha-actin also showed colocalization of the AT2 receptor with vascular smooth muscle cells. Other cells associated with the microvessels also stained positive for AT2 receptors. Briefly, this study confirms previous functional data and localizes the AT2 receptor to the microcirculation. These studies demonstrate that the AT2 receptor is present on a variety of vascular cell types and that it is situated in a fashion that would allow it to directly oppose ANG II type 1 receptor actions.

  14. Removing noises caused by motion artefacts in microcirculation maps of human skin in vivo.

    PubMed

    Chen, C; Shi, W; Gao, W

    2015-12-01

    This paper presents a zero-padding and cross-correlation technique-based correlation mapping optical coherence tomography (ZPCC-cmOCT) to reconstruct microcirculation maps of human skin in vivo, which can remove the background decorrelation noise caused by motion artefacts. In conventional correlation mapping optical coherence tomography method, the correlation degree of static tissue may be lowered by the motion artefacts due to cardiac and respiratory motion, resulting in background decorrelation noise in microcirculation maps. In zero-padding and cross-correlation technique-based correlation mapping optical coherence tomography method, structural images are first obtained by performing Fourier transform on zero-padded interference fringes, and then cross-correlation-based image registration is utilized to align local areas in two adjacent structural images. Finally, correlation mapping optical coherence tomography method is performed to generate microcirculation maps. Both phantom experiments and in vivo experiments were implemented and the results demonstrate that the proposed method is capable of providing microcirculation maps with the background decorrelation noise removed.

  15. Extension of the preceding birth technique.

    PubMed

    Aguirre, A

    1994-01-01

    The Brass-inspired Preceding Birth Technique (PBT), is an indirect estimation technique with low costs of administration. PBT involves asking women at a time close to delivery about the survival of the preceding births. The proportion dead is close to the probability of dying between the birth and the second birthday or an index of early childhood mortality (II or Q). Brass and Macrae have determined that II is an estimate of mortality between birth and an age lower than the birth interval or around 4/5 of the birth interval. Hospital and clinic data are likely to include a concentration of women with lower risks of disease because of higher educational levels and socioeconomic status. A simulation of PBT data from the World Fertility Survey for Mexico and Peru found that the proportions of previously dead children were 0.156 in Peru and 0.092 in Mexican home deliveries. Maternity clinic proportions were 0.088 in Peru and 0.066 in Mexico. Use of clinic and hospital data collection underestimated mortality by 32% in Peru and 15% in Mexico. Another alternative was proposed: interviewing women at some other time than delivery. If the interview was during a child/infant intervention after delivery, the subsample would still be subject to a bias, but this problem could be overcome by computing the weighted average of the actual probability of the older child being dead and the conditional probability of the younger child being dead or both younger and older children being dead. Correction factors could be applied using the general standard of the logit life table system of Brass. Calculation of a simple average of the ages of the younger children could provide enough information to help decide which tables to use. Five surveys were selected for testing the factors of dependence between probabilities of death of successive siblings: Bangladesh, Lesotho, Kenya, Ghana, and Guyana. Higher mortality was related to lower dependency factors between the probabilities of death

  16. White Dwarf Convection Preceding Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Zingale, Michael; Almgren, A. S.; Bell, J. B.; Malone, C. M.; Nonaka, A.; Woosley, S. E.

    2010-01-01

    In the single degenerate scenario for Type Ia supernovae, a Chandrasekhar mass white dwarf `simmers' for centuries preceding the ultimate explosion. During this period, reactions near the center drive convection throughout most of the interior of the white dwarf. The details of this convective flow determine how the first flames in the white dwarf ignite. Simulating this phase is difficult because the flows are highly subsonic. Using the low Mach number hydrodynamics code, MAESTRO, we present 3-d, full star models of the final hours of this convective phase, up to the point of ignition of a Type Ia supernova. We discuss the details of the convective velocity field and the locations of the initial hot spots. Finally, we show some preliminary results with rotation. Support for this work came from the DOE/Office of Nuclear Physics, grant No. DE-FG02-06ER41448 (Stony Brook), the SciDAC Program of the DOE Office of Mathematics, Information, and Computational Sciences under the DOE under contract No. DE-AC02-05CH11231 (LBNL), and the DOE SciDAC program, under grant No. DE-FC02-06ER41438 (UCSC). We made use of the jaguar machine via a DOE INCITE allocation at the Oak Ridge Leadership Computational Facility.

  17. Animal Detection Precedes Access to Scene Category

    PubMed Central

    Crouzet, Sébastien M.; Joubert, Olivier R.; Thorpe, Simon J.; Fabre-Thorpe, Michèle

    2012-01-01

    The processes underlying object recognition are fundamental for the understanding of visual perception. Humans can recognize many objects rapidly even in complex scenes, a task that still presents major challenges for computer vision systems. A common experimental demonstration of this ability is the rapid animal detection protocol, where human participants earliest responses to report the presence/absence of animals in natural scenes are observed at 250–270 ms latencies. One of the hypotheses to account for such speed is that people would not actually recognize an animal per se, but rather base their decision on global scene statistics. These global statistics (also referred to as spatial envelope or gist) have been shown to be computationally easy to process and could thus be used as a proxy for coarse object recognition. Here, using a saccadic choice task, which allows us to investigate a previously inaccessible temporal window of visual processing, we showed that animal – but not vehicle – detection clearly precedes scene categorization. This asynchrony is in addition validated by a late contextual modulation of animal detection, starting simultaneously with the availability of scene category. Interestingly, the advantage for animal over scene categorization is in opposition to the results of simulations using standard computational models. Taken together, these results challenge the idea that rapid animal detection might be based on early access of global scene statistics, and rather suggests a process based on the extraction of specific local complex features that might be hardwired in the visual system. PMID:23251545

  18. The evolution of conspecific sperm precedence in Drosophila.

    PubMed

    Dixon, Sheri M; Coyne, Jerry A; Noor, Mohamed A F

    2003-05-01

    Conspecific sperm precedence takes place when females inseminated by both conspecific and heterospecific sperm preferentially produce conspecific rather than hybrid offspring. Although many studies have documented conspecific sperm precedence, most have only identified it between taxa that are already considered to be good species. Here, we test for sperm precedence between two Drosophila pseudoobscura subspecies and between two Drosophila melanogaster races to evaluate how early in evolutionary divergence sperm precedence evolves. We found evidence of weak conspecific sperm precedence between the Drosophila subspecies but none between the Drosophila races. These pairs of taxa are already separated by mating discrimination and/or hybrid sterility, so our observation suggests that conspecific sperm precedence does not always evolve before other barriers to gene exchange.

  19. In situ testing of CO2 laser on dental pulp function: Effects on microcirculation

    SciTech Connect

    Friedman, S.; Liu, M.; Doerscher-Kim, J.K.; Kim, S. )

    1991-01-01

    The effect of CO2 laser irradiation on pulpal microcirculation was studied in cat canines. The enamel surfaces of 4 teeth were exposed with energy densities of 304-1440J/cm2, using either a handpiece or a microslad, with a focal spot of 0.21mm and 0.33mm respectively. Pulpal blood flow (PBF) before and following lasing was recorded through the intact tooth surface by a laser Doppler flowmeter. CO2 laser irradiation caused an increase in PBF, which was immediate and transient. The PBF increase was higher in a large pulp than in a small pulp, and it was inversely related to the focal spot size. These findings confirm that the dental pulp is thermally affected by CO2 lasing of the tooth surface, however, without extensive pulp coagulation. It is concluded that the effects of laser irradiation on the pulpal microcirculation may be studied in situ by means of the presented methodology.

  20. Laser speckle contrast imaging of cerebral autoregulation in rats at a macro- and microcirculation level

    NASA Astrophysics Data System (ADS)

    Semyachkina-Glushkovskaya, O. V.; Abdurashitov, A. S.; Sindeev, S. S.; Tuchin, V. V.

    2016-06-01

    Using the method of laser speckle imaging for the simultaneous study of macro- and microcirculation in cerebral vessels of healthy rats, we show that the mechanisms underlying cerebral autoregulation depend on the initial condition of the organism and the sex of individual animals. The pharmacological dose-dependent stimulation of the peripheral arterial pressure increase is not accompanied by the cerebral circulation responses of analogous intensity, but manifests itself as 'compensating' reactions, namely, the redistribution of the blood flow at the level of macro- (in females) and microcirculation (in females and males). The obtained results extend our understanding of the capabilities of laser speckle imaging technique in neurophysiological studies of reserve abilities of cerebral circulation autoregulation under the conditions of hypertensive status formation.

  1. Monitoring the microcirculation at the bedside using hand-held imaging microscopes: Automatic tracking of erythrocytes.

    PubMed

    Sorelli, M; Bocchi, L; Ince, C

    2015-01-01

    In recent years, the development of portable microscopy devices that enable the noninvasive bedside evaluation of the mucosal microcirculation in critically ill patients has expanded the research on this level of the cardiovascular system. Several semi-quantitative scores have been defined to assess the peripheral perfusion, based on videos of the microcirculation. However, they are cumbersome and time-consuming processes, highlighting the need for the development of automated software techniques, to reduce physicians workload and ensure prompt and objective patient evaluation. We developed a rapid, automatic method for the quantitative assessment of erythrocyte velocities in Incident Dark Field (IDF) illumination videos of capillary flow. The technique, based on Kalman filter object tracking, was tested in 35 IDF videos against space-time diagrams, showing high correlation (r = 0.96) and agreement (bias = 3.3 μm/s) with space-time diagrams (STD), below 200 μm/s.

  2. Laser speckle-imaging of blood microcirculation in the brain cortex of laboratory rats in stress

    SciTech Connect

    Vilensky, M A; Semyachkina-Glushkovskaya, Oxana V; Timoshina, P A; Kuznetsova, Jana V; Semyachkin-Glushkovskii, I A; Agafonov, Dmitry N; Tuchin, Valerii V

    2012-06-30

    The results of experimental approbation of the method of laser full-field speckle-imaging for monitoring the changes in blood microcirculation state of the brain cortex of laboratory rats under the conditions of developing stroke and administration of vasodilating and vasoconstrictive agents are presented. The studies aimed at the choice of the optimal conditions of speckle-image formation and recording were performed and the software implementing an adaptive algorithm for processing the data of measurements was created. The transfer of laser radiation to the probed region of the biotissue was implemented by means of a silica-polymer optical fibre. The problems and prospects of speckle-imaging of cerebral microcirculation of blood in laboratory and clinical conditions are discussed.

  3. Application of colour magnification technique for revealing skin microcirculation changes under regional anaesthetic input

    NASA Astrophysics Data System (ADS)

    Rubins, Uldis; Spigulis, Janis; Miscuks, Aleksejs

    2013-11-01

    In this work the colour magnification technique was applied for monitoring of palm skin microcirculation changes under peripheral (Plexus Brachialis with axiliary access) Regional Anaesthesia (RA). During the RA procedure 20 minute video of patient's forearm was taken at steady light conditions. Video content was processed offline by custom developed Matlab software with build-in colour magnification algorithm that performs temporal filtering of video sequence near-heartbeat frequency, spatial decomposition of video and amplification of pulsatile signal in every pixel of skin image. Using this method, we are able to visualize the subcutaneous microcirculation changes in high spatial resolution. The results showed different blood pulse amplitude dynamics over the skin regions of palm and forearm during the RA. The colour magnification technique could be used for real-time monitoring of RA effect.

  4. MR imaging of hand microcirculation as a potential tool for space glove testing and design

    NASA Technical Reports Server (NTRS)

    Peterson, Steven W.; Strauss, Alvin M.; Niemann, Trista A.; Lorenz, Christine H.

    1991-01-01

    The task of evaluating and designing space gloves requires accurate biomechanical characterization of the hand. The availability of magnetic resonance (MR) imaging has created new opportunities for in vivo analysis of physiological phenomena such as the relationship between circulation and fatigue. An MR imaging technique originally proposed to quantitatively evaluate cerebral perfusion has been modified to evaluate the capillary microcirculation in hand muscles. An experimental protocol was developed to acquire perfusion-weighted images in the hand before and after various levels of exercise. Preliminary results on the feasibility of applying the MR imaging technique to the study of microcirculation and fatigue in the hand are presented. The potential of this method for space glove testing and design is also discussed.

  5. Study of microcirculation of the ocular ciliary body in experimental kidney disease.

    PubMed

    Obrubov, S A; Ivanova, A O; Klyuchnikov, S O; Dreval, A A; Boginskaya, O A

    2014-08-01

    We studied disorders in ciliary body microcirculation in experimental chronic glomerulonephritis with tubulointerstitial nephritis and evaluated the hemodynamic effects of low-frequency pulsed electromagnetic field in this pathology. Laser Doppler flowmetry demonstrated vasospasm with reduced nutrient blood fl ow in the ciliary body of animals with experimental chronic glomerulonephritis with tubulointerstitial nephritis. The exposure to low-frequency pulsed electromagnetic field using developed technology will lead to significant reduction of the vascular tone and improve arterial blood supply to the microcirculatory bed.

  6. Impact of antibiotics on the microcirculation in local and systemic inflammation.

    PubMed

    Al-Banna, N A; Pavlovic, D; Gründling, M; Zhou, J; Kelly, M; Whynot, S; Hung, O; Johnston, B; Issekutz, T B; Kern, H; Cerny, V; Lehmann, Ch

    2013-01-01

    The main function of antibiotics is related to their capacity to eliminate a microorganism. In addition to the antimicrobial function of antibiotics, they are known to have anti-inflammatory and vasomodulatory effects on the microcirculation. The ability of non-antimicrobial derivatives of antibiotics to control inflammation illustrates the distinct anti-microbial and anti-inflammatory roles of antibiotics. In this review, we discuss the impact of antibiotics on leukocyte recruitment and the state of the microcirculation. Literature reporting the effect of antibiotics in non-infectious inflammatory conditions is reviewed as well as the studies demonstrating the anti-inflammatory effects of antibiotics in animal models of infection. In addition, the effect of the antibiotics on the immune system is summarized in this review, in order to postulate some mechanisms of action for the proand anti-inflammatory contribution of antibiotics. Literature reported the effect of antibiotics on the production of cytokines, chemotaxis and recruitment of leukocytes, production of reactive oxygen species, process of phagocytosis and autophagy, and apoptosis of leukocytes. Yet, all antibiotics may not necessarily exert an anti-inflammatory effect on the microcirculation. Thus, we suggest a model for spectrum of anti-inflammatory and vasomodulatory effects of antibiotics in the microcirculation of animals in local and systemic inflammation. Although the literature suggests the ability of antibiotics to modulate leukocyte recruitment and microperfusion, the process and the mechanism of action are not fully characterized. Studying this process will expand the knowledge base that is required for the selection of antibiotic treatment based on its anti-inflammatory functions, which might be particularly important for critically ill patients.

  7. Wavelet-based analysis of gastric microcirculation in rats with ulcer bleedings

    NASA Astrophysics Data System (ADS)

    Pavlov, A. N.; Rodionov, M. A.; Pavlova, O. N.; Semyachkina-Glushkovskaya, O. V.; Berdnikova, V. A.; Kuznetsova, Ya. V.; Semyachkin-Glushkovskij, I. A.

    2012-03-01

    Studying of nitric oxide (NO) dependent mechanisms of regulation of microcirculation in a stomach can provide important diagnostic markers of the development of stress-induced ulcer bleedings. In this work we use a multiscale analysis based on the discrete wavelet-transform to characterize a latent stage of illness formation in rats. A higher sensitivity of stomach vessels to the NO-level in ill rats is discussed.

  8. Influence of gravity on flow distribution of red blood cells in microcirculation.

    PubMed

    Tateishi, N; Suzuki, Y; Shirai, M; Maeda, N

    2000-07-01

    The influence of the gravity on flow distribution of erythrocytes in microcirculation was examined. We developed a new centrifuge system with a rotation disc. An observation system of blood flow in a micro-flow channel was arranged on the disc. Erythrocyte flow in the micro-flow tube was displaced under the gravity. This study suggests that the gravity affects the transfer of substances from blood vessels to tissues.

  9. Microcirculation-on-a-Chip: A Microfluidic Platform for Assaying Blood- and Lymphatic-Vessel Permeability

    PubMed Central

    Sato, Miwa; Sasaki, Naoki; Ato, Manabu; Hirakawa, Satoshi; Sato, Kiichi; Sato, Kae

    2015-01-01

    We developed a microfluidic model of microcirculation containing both blood and lymphatic vessels for examining vascular permeability. The designed microfluidic device harbors upper and lower channels that are partly aligned and are separated by a porous membrane, and on this membrane, blood vascular endothelial cells (BECs) and lymphatic endothelial cells (LECs) were cocultured back-to-back. At cell-cell junctions of both BECs and LECs, claudin-5 and VE-cadherin were detected. The permeability coefficient measured here was lower than the value reported for isolated mammalian venules. Moreover, our results showed that the flow culture established in the device promoted the formation of endothelial cell-cell junctions, and that treatment with histamine, an inflammation-promoting substance, induced changes in the localization of tight and adherens junction-associated proteins and an increase in vascular permeability in the microdevice. These findings indicated that both BECs and LECs appeared to retain their functions in the microfluidic coculture platform. Using this microcirculation device, the vascular damage induced by habu snake venom was successfully assayed, and the assay time was reduced from 24 h to 30 min. This is the first report of a microcirculation model in which BECs and LECs were cocultured. Because the micromodel includes lymphatic vessels in addition to blood vessels, the model can be used to evaluate both vascular permeability and lymphatic return rate. PMID:26332321

  10. Tissue ACE inhibition improves microcirculation in remote myocardium after coronary stenosis: MR imaging study in rats.

    PubMed

    Hiller, Karl-Heinz; Ruile, Philipp; Kraus, Günter; Bauer, Wolfgang R; Waller, Christiane

    2010-12-01

    ACE inhibition has been shown to improve left ventricular (LV) and myocardial blood flow. Previous data regarding changes in capillary density and angiogenesis during ACE inhibition are controversial. The aim of the following study was to determine myocardial microcirculation and heart function in the rat after coronary stenosis using non invasive MR imaging techniques. MR spin labeling and cine techniques have been performed in female Wistar rats 2weeks after coronary artery stenosis. In one group, animals were treated with quinapril in a dose of 6mg/kg/day. Perfusion, relative blood volume (RBV), LV mass and function were determined non-invasively 2weeks after treatment. Finally, fibrosis and capillary density were analyzed histologically. Additionally, hemodynamic measurements were realized in a further group in order to calculate systemic vascular resistance (SVR). Quinapril resulted in a significant increase in perfusion at rest in the remote and the poststenotic myocardium with improved systolic function and a decrease in SVR compared to the non treated control group. Additionally, maximum perfusion and RBV were slightly elevated whereas capillary density was unchanged among the groups. MRI allows for non-invasive quantification of functional microcirculation and heart function. In addition to the well known effect of ACE inhibition on systolic function, treatment with the tissue specific ACE inhibitor quinapril revealed an important microvascular improvement, especially at arteriolar level. These findings may support the use of tissue ACE inhibitors to improve cardiac microcirculation after ischemia.

  11. [Effect of LHRH agonists on testicular microcirculation with Doppler laser flowmetry].

    PubMed

    Gonzalvo, V; Navalón, P; Lloris, J M

    1996-10-01

    The purpose of this paper is to present the changes that take place in testicular microcirculation measured by DLF during systemic administration of LHRH agonists. The essay includes a comparison with the variations registered in the volume of testicular interstitial fluid, the anatomopathological changes and the associated leucocyte demyeloperoxidase levels. We also examine the relationship between testicular microcirculation changes and plasma testosterone levels. To do this, 50 male Wistar rats were randomly divided into 5 groups, using 10 as control group and the remaining 40 distributed in 4 groups. Measurements were done at 2, 4, 8 and 24 hours after administration of Tryptorelin 0.4 mg i.v. We found that acute administration of an LHRH agonist causes a series of significant changes on testicular microcirculation. Testicular rhythmic microcirculatory flow, i.e., vasomotion, disappears. In turn, accumulation of PMN leucocytes associated to increased venular permeability takes places. Such pre- and postcapillary vascular changes lead to increased vascular permeability which results in increased volume of testicular interstitial fluid. This increased capillary permeability is responsible for the extensive interstitial oedema that would explain the serious histological changes seen on the seminiferous tubule with these drugs.

  12. The effect of wound ointments on tissue microcirculation and leucocyte behaviour.

    PubMed

    Peter, F W; Li-Peuser, H; Vogt, P M; Muehlberger, T; Homann, H H; Steinau, H U

    2002-01-01

    An intact microcirculation is essential for normal healing to occur. Wound repair may be impaired by various endogenous and exogenous factors, such as reduced microvascular perfusion, infection and debris. In the nonhealing wound, radical surgical debridement is critical. To supplement healing, various ointments are used in clinical practice. Little is known about their effects on tissue perfusion. We have therefore selected two substances widely used, the antiseptic Betadine and the enzyme combination Elase and investigated their impact on the microcirculation and on leucocyte activity, using the cremaster muscle as a model. We found that functional capillary density and arteriolar diameters were significantly reduced by Betadine, whereas leucocyte activity was not affected. In the Elase group, capillary flow and arteriolar diameters were significantly increased, and again leucocyte activity was not changed. The mechanism by which Betadine reduces microvascular flow is believed to be the same as in reperfusion injury. The positive effect of Elase on the microcirculation might be attributed to plasmin, which has been shown to dilate blood vessels.

  13. Nicotine induces leukocyte rolling and adhesion in the cerebral microcirculation of the mouse.

    PubMed

    Yong, T; Zheng, M Q; Linthicum, D S

    1997-12-01

    Nicotine and several related metabolites were examined for their ability to induce leukocyte rolling and adhesion in the cerebral microcirculation of the mouse. A cranial window was surgically prepared for the visualization of the pial microcirculation using an intra-vital microscopy imaging system. Using this technique rhodamine-labeled leukocytes could be visualized and video-recorded as they traveled within the microvessels, and the quantitation of their rolling and adhesion along the pial venule walls was assessed during an off-line video playback analysis. Nicotine was found to produce significant dose-related increases in leukocyte rolling and adhesion. Cotinine, a major nicotine metabolite, did not induce the same degree of leukocyte rolling and adhesion. Mecamylamine, a nicotine antagonist, was found to inhibit the nicotine-induced leukocyte rolling and adhesion. Anti-P-selectin antibody blocked nicotine-induced leukocyte rolling, while anti-CD18 antibody effectively inhibited leukocyte adhesion, but not rolling in similar experiments. Nicotine-induced leukocyte rolling and adhesion were also inhibited by superoxide dismutase and catalase. These data suggest that nicotine, the principle pharmacological agent in cigarette smoke and related tobacco products, acts via a ganglionic-type nicotinic receptor to enhance leukocyte rolling via P-selectin and reactive oxygen radical-dependent mechanisms in cerebral microcirculation of the mouse. PMID:9413272

  14. Assesment of gingival microcirculation in anterior teeth using laser Doppler flowmetry

    NASA Astrophysics Data System (ADS)

    Canjau, Silvana; Miron, Mariana I.; Todea, Carmen D.

    2016-03-01

    Introduction: Evaluating the health status of the gingival tissue represents an important objective in the daily practice. Inflammation changes the microcirculatory and micromorphological dynamics of human gingiva. Aim: The purpose of this study was to evaluate the microcirculation in subjects with moderate gingivitis and healthy gingiva by using laser Doppler flowmetry (LDF). Material and Methods: Recordings of the gingival microcirculation (GM) were taken from 20 healthy gingival sites and from 20 sites with moderate gingivitis. The gingival blood flows in the gingivitis group before treatment was significantly different from those in the healthy gingiva group. Signals were recorded with the aid of a laser Doppler MoorLab instrument VMS-LDF2 probe VP3 10 mm S/N 2482. Three consecutive determinations of the GM were registered for each site, as follows: before the initial therapy, at 24 hours after the initial therapy and then, 7 days after the initial therapy. The data were processed using the statistical analysis software SPSS v16.0.1. Results: The results of this preliminary study showed statistically significant differences among the GM values recorded before and after the initial therapy. Conclusions: LDF could be a useful, noninvasive, sensitive, reproducible, and harmless method for measuring gingival blood flow (gingival microcirculation) in humans.

  15. Impact of methylene blue in addition to norepinephrine on the intestinal microcirculation in experimental septic shock.

    PubMed

    Nantais, Jordan; Dumbarton, Tristan C; Farah, Nizam; Maxan, Alexander; Zhou, Juan; Minor, Samuel; Lehmann, Christian

    2014-01-01

    Methylene blue (MB) has been used with some success as a treatment for the vasoplegia of vasopressor-refractory septic shock. The putative mechanism of action of MB is the inhibition of endothelial nitric oxide within the microvasculature and improved responsiveness to endogenous catecholamines (norepinephrine (NE)). However, to date, no study has demonstrated the microcirculatory effect of methylene blue in septic shock. The objective of this randomized, controlled, animal study was to show, in an experimentally-induced, septic shock model in rats, the effects of MB and NE on global hemodynamics and the microcirculation. Mean arterial pressure (MAP) was drastically reduced following bacterial endotoxin (lipopolysaccharide, LPS) administration in animals not receiving vasopressors. Only the combination of NE + MB restored MAP to control levels by the end of the three hour experiment. Intravital microscopy of the microcirculation was performed in the terminal ileum in order to examine functional capillary density in intestinal muscle layers and the mucosa, as well as leukocyte activation in venules (rolling, adhesion to the endothelium). Untreated LPS animals showed a significant increase in leukocyte adhesion and a decrease in capillary perfusion in the intestinal microcirculation. In groups receiving NE or NE+MB, we observed a significant decrease in leukocyte adhesion and improved functional capillary density, indicating that microvasculature function was improved. This study suggests that methylene blue may be able to improve hemodynamics while preserving microvascular function in septic shock.

  16. Evaluation of the microcirculation in a rabbit hemorrhagic shock model using laser Doppler imaging.

    PubMed

    Luo, Zhenchun; Wang, Pengfei; Zhang, An; Zuo, Guoqing; Zheng, Yuanyi; Huang, Yan

    2015-01-01

    The aim of this study is to evaluate the feasibility of Laser Doppler imaging (LDI) for noninvasive and dynamic assessment of hemorrhagic shock in a rabbit model. A rabbit model of hemorrhagic shock was generated and LDI of the microcirculation in the rabbit ears was performed before and at 0, 30, 60, and 90 min after hemorrhage. The CCD (Charge Coupled Device) image of the ears, the mean arterial pressure (MAP) and the heart rate (HR) were monitored. The mean LDI flux was calculated. The HR of rabbits was significantly (p < 0.05) elevated and the MAP was decreased after hemorrhage, compared to the pre-hemorrhage level. Within the initial 30 min after hemorrhage, the perfusion flux lineally dropped down. In contrast, the MAP values did not differ significantly between the time points of 0 and 30 after hemorrhage (p > 0.05). Both the flux numbers and the red-to-blue color changes on LDI imaging showed the reduction of the microcirculation. LDI imaging is a noninvasive and non-contact approach to evaluate the microcirculation and may offer benefits in the diagnosis and treatment of hemorrhage shock. Further studies are needed to confirm its effectiveness in clinical practice.

  17. Influences of high-voltage electrical burns on the pulmonary microcirculation in rabbits.

    PubMed

    Zhou, H M; Xu, S J; Wang, L; Shao, H B; Xie, B; Feng, J K; Wang, C J; Bai, Y Q; Zhang, Q F

    2016-01-01

    This study was performed to investigate the effects of high-voltage electrical burns (HEB) on the pulmonary microcirculation in rabbits. Total of 120 rabbits were randomly divided into control and HEB group using a random number table. HEB model was developed with a voltage regulator and experimental transformer. Laser Doppler perfusion imager was utilized to monitor and quantify the blood perfusion in pulmonary microcirculation. The microvascular morphologic changes of the lung were observed using light microscopy and transmission electron microscope (TEM). The lung wet/dry weight ratio and the PaO2 were determined. The values of blood perfusion in rabbit pulmonary microcirculation in the HEB group were decreased at 5 min, but increased at 1 h after burn (P <  0.01) and then decreased gradually. Light microscopy reveals microthrombus formation in pulmonary venules and bleeding in venous capillaries in HEB group. We found the number of microvilli in the capillary endothelial cells decreased, the rough endoplasmic reticulum expanded and severe degranulation occurred, the mitochondrial cristae fused or disappeared, and severe edema surrounded the capillary endothelial cells by TEM. The values of lung wet/dry weight ratio were higher and the PaO2 were lower than that of before burn group (P <  0.01). These results demonstrated that microcirculatory disorders play a major role in the development of progressive lung damage after high-voltage electrical burns.

  18. Comparison of cerebral microcirculation of alloxan diabetes and healthy mice using laser speckle contrast imaging

    NASA Astrophysics Data System (ADS)

    Timoshina, Polina A.; Shi, Rui; Zhang, Yang; Zhu, Dan; Semyachkina-Glushkovskaya, Oxana V.; Tuchin, Valery V.; Luo, Qingming

    2015-03-01

    The study of blood microcirculation is one of the most important problems of the medicine. This paper presents results of experimental study of cerebral blood flow microcirculation in mice with alloxan-induced diabetes using Temporal Laser Speckle Imaging (TLSI). Additionally, a direct effect of glucose water solution (concentration 20% and 45%) on blood flow microcirculation was studied. In the research, 20 white laboratory mice weighing 20-30 g were used. The TLSI method allows one to investigate time dependent scattering from the objects with complex dynamics, since it possesses greater temporal resolution. Results show that in brain of animal diabetic group diameter of sagittal vein is increased and the speed of blood flow reduced relative to the control group. Topical application of 20%- or 45%-glucose solutions also causes increase of diameter of blood vessels and slows down blood circulation. The results obtained show that diabetes development causes changes in the cerebral microcirculatory system and TLSI techniques can be effectively used to quantify these alterations.

  19. New potentialities for noninvasive optical investigation of microcirculation in extended space missions

    NASA Astrophysics Data System (ADS)

    Gurfinkel, Youri I.; Mikhailov, Valery M.

    2002-05-01

    Goals of the investigation were to analyze the spectrum of microcirculation parameters and collection of baseline data healthy subjects during extended isolation and relative hypokinesia as a model of mission to the International space station. There were investigated four healthy volunteers at the age of 37, 40, 41 and 48 during the baseline 240-d isolation period starting from July 3, 1999. With the regularity of 3 times a week each subject made records at the same time between 1 and 2 pm. Optical computerized capillaroscope for noninvasive measurement of the capillary diameters, blood flow velocity as well as the size of the perivascular zone and the number of the blood aggregates was used. About 1500 episodes were recorded on laser disks and analyzed. Parameters of microcirculation were compared with other physiological parameters monitored in the experiment. All subjects had wave-like variations in the microcirculation parameters within the minute, week, and month ranges. Mean blood flow velocity in the baseline period was lower than in the period of isolation. Results of the daily body mass measurement were found to correlate with the perivascular zone size, that could be explained as retention of body fluids in tissues. Computerized capillaroscopy is easy to perform, noninvasive, highly sensitive and informative. It enables analysis of the character of rhythmic processes, adaptability of organism to long-term experiments and, therefore, can be proposed for use in extended space missions.

  20. 10 CFR 205.11 - Order of precedence.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 3 2010-01-01 2010-01-01 false Order of precedence. 205.11 Section 205.11 Energy DEPARTMENT OF ENERGY OIL ADMINISTRATIVE PROCEDURES AND SANCTIONS General Provisions § 205.11 Order of precedence. (a) If there is any conflict or inconsistency between the provisions of this part and any...

  1. 26 CFR 1.665(e)-1 - Preceding taxable year.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 8 2012-04-01 2012-04-01 false Preceding taxable year. 1.665(e)-1 Section 1.665... (CONTINUED) INCOME TAXES (CONTINUED) Treatment of Excess Distributions of Trusts Applicable to Taxable Years Beginning Before January 1, 1969 § 1.665(e)-1 Preceding taxable year. (a) Definition. For purposes...

  2. 26 CFR 1.665(e)-1 - Preceding taxable year.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 8 2011-04-01 2011-04-01 false Preceding taxable year. 1.665(e)-1 Section 1.665... (CONTINUED) INCOME TAXES (CONTINUED) Treatment of Excess Distributions of Trusts Applicable to Taxable Years Beginning Before January 1, 1969 § 1.665(e)-1 Preceding taxable year. (a) Definition. For purposes...

  3. 26 CFR 1.665(e)-1 - Preceding taxable year.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 8 2014-04-01 2014-04-01 false Preceding taxable year. 1.665(e)-1 Section 1.665... (CONTINUED) INCOME TAXES (CONTINUED) Treatment of Excess Distributions of Trusts Applicable to Taxable Years Beginning Before January 1, 1969 § 1.665(e)-1 Preceding taxable year. (a) Definition. For purposes...

  4. A preparation for in vivo study of the diaphragmatic microcirculation in the rat.

    PubMed

    Boczkowski, J; Vicaut, E; Aubier, M

    1990-07-01

    A new preparation is described for the study of the microcirculation of the rat diaphragm by in vivo microscopy. After midline laparotomy, the abdominal site of the diaphragm muscle was exposed. The rat was mechanically ventilated and placed in the Trendelenburg position, thus allowing a microscope placed on a three-dimensional articulated system to be set up perpendicular to the diaphragm. The diaphragm was then transilluminated by inserting fiberoptic microprobes into the thorax cavity by thoracotomy in the fifth intercostal space. This preparation allowed us to describe the morphological characteristics of the arteriolar network in vivo. As regards the venular network, two parts were distinguished: one part collects the blood of the external half of the diaphragm, runs roughly parallel to the arterioles, and converges toward the internal mammary and intercostal veins; the other part collects the blood of the central half of the diaphragm and converges on the central venous arcade along its central tendon. Anastomotic channels between these two parts were observed, as well as spontaneous inversion of the direction of the blood flow, indicating the presence of unsteady pressure gradients in some branches of the venular network. Capillary density was also studied by measuring intercapillary distance, whose mean value was 21.43 +/- 0.67 microns. No differences in intercapillary distance were found between the external and central parts of the diaphragm. In conclusion, we describe a preparation which allowed us to study the diaphragmatic microcirculation for at least 2 hr under good hemodynamic conditions. The study of this specific microcirculation is important because the diaphragm's metabolism and functions are specific and because it is essential to life that its perfusion should be adapted to its specific metabolic requirements. PMID:2398828

  5. Is there a stimulation of blood microcirculation at low level laser irradiation

    NASA Astrophysics Data System (ADS)

    Rogatkin, Dmitry; Dunaev, Andrey

    2014-05-01

    In 1980-2000 besides the laser surgery an intensive evolution of Low Level Laser Therapy (LLLT) had started in medicine, especially in Russia as well as in several other East-European countries. At the same time the biophysical mechanisms of LLLT are still the subject of disputes. One of the most popular clinical effects at Low Level Laser Irradiation (LLLI) being mentioned in medical publications for justification of the LLLT healing outcome is a stimulation of blood microcirculation in irradiated area. It was declared a priori at a dawn of LLLT and is now a basis of medical interpretation of healing mechanisms of LLLT at least in Russia. But in past 20 years a lot of investigation was carried out on optical registration of microhaemodynamic parameters in vivo as well as a number of noninvasive diagnostic tools was created for that. So, today it is possible to experimentally check the blood microcirculation stimulation hypothesis. Our study was aimed on that during the past 10 years. The most precision and accurate experiments we have carried out recently using simultaneously three different noninvasive diagnostic techniques: Laser Doppler Flowmetry, Tissue Reflectance Oximetry and Infrared Thermography. All these methods didn't confirm the effect on the blood microcirculation stimulation in skin or mucosa at irradiation with the power density below 50 mW/cm2 and irradiation time up to 5-6 minutes. Above this threshold the heating on 0,8…1 °C of tissue in the field of irradiation and the corresponding synchronous increase of all parameters of microhemodynamics were observed.

  6. Intestinal and sublingual microcirculation are more severely compromised in hemodilution than in hemorrhage.

    PubMed

    Ferrara, Gonzalo; Kanoore Edul, Vanina Siham; Martins, Enrique; Canales, Héctor Saúl; Canullán, Carlos; Murias, Gastón; Pozo, Mario Omar; Estenssoro, Elisa; Ince, Can; Dubin, Arnaldo

    2016-05-15

    The alterations in O2 extraction in hemodilution have been linked to fast red blood cell (RBC) velocity, which might affect the complete release of O2 from Hb. Fast RBC velocity might also explain the normal mucosal-arterial Pco2 (ΔPco2). Yet sublingual and intestinal microcirculation have not been completely characterized in extreme hemodilution. Our hypothesis was that the unchanged ΔPco2 in hemodilution depends on the preservation of villi microcirculation. For this purpose, pentobarbital-anesthetized and mechanically ventilated sheep were submitted to stepwise hemodilution (n = 8), hemorrhage (n = 8), or no intervention (sham, n = 8). In both hypoxic groups, equivalent reductions in O2 consumption (V̇o2) were targeted. Microcirculation was assessed by videomicroscopy, intestinal ΔPco2 by air tonometry, and V̇o2 by expired gases analysis. Although cardiac output and superior mesenteric flow increased in hemodilution, from the very first step (Hb = 5.0 g/dl), villi functional vascular density and RBC velocity decreased (21.7 ± 0.9 vs. 15.9 ± 1.0 mm/mm(2) and 1,033 ± 75 vs. 850 ± 79 μm/s, P < 0.01). In the last stage (Hb = 1.2 g/dl), these variables were lower in hemodiution than in hemorrhage (11.1 ± 0.5 vs. 15.4 ± 0.9 mm/mm(2) and 544 ± 26 vs. 686 ± 70 μm/s, P < 0.01), and were associated with lower intestinal fractional O2 extraction (0.61 ± 0.04 vs. 0.79 ± 0.02, P < 0.01) but preserved ΔPco2 (5 ± 2 vs. 25 ± 4 mmHg, P < 0.01). Therefore, alterations in O2 extraction in hemodilution seemed related to microvascular shunting, not to fast RBC velocity. The severe microvascular abnormalities suggest that normal ΔPco2 was not dependent on CO2 washout by the villi microcirculation. Increased perfusion in deeper intestinal layers might be an alternative explanation. PMID:26989219

  7. Chronic Central Nervous System Expression of HIV-1 Tat Leads to Accelerated Rarefaction of Neocortical Capillaries and Loss of Red Blood Cell Velocity Heterogeneity

    PubMed Central

    Silva, Jharon N.; Polesskaya, Oksana; Wei, Helen S.; Rasheed, Izad-Yar D.; Chamberlain, Jeffrey M.; Nishimura, Christopher; Feng, Changyong; Dewhurst, Stephen

    2014-01-01

    Objectives HIV-1 infection of the central nervous system is associated with impairment of cerebral blood flow and neurocognitive function, and accelerated signs of aging. Since normal aging is associated with rarefaction of the cerebral vasculature, we set out to examine chronic viral effects on the cerebral vasculature. Methods Doxycycline-inducible HIV-1 Tat transgenic (Tat-tg) and wild-type (WT) control mice were used. Animals were treated with doxycycline for 3 weeks or 5–7 months. Cerebral vessel density and capillary segment length were determined from quantitative image analyses of sectioned cortical tissue. In addition, movement of red blood cells in individual capillaries was imaged in vivo using multiphoton microscopy, to determine red blood cell velocity and flux. Results Mean RBCV was not different between Tat-tg mice and age matched WT controls. However, cortical capillaries from Tat-tg mice showed a significant loss of RBCV heterogeneity and increased RBCF that was attributed to a marked decrease in total cortical capillary length (35–40%) compared to WT mice. Conclusions Cerebrovascular rarefaction is accelerated in HIV-1 Tat transgenic mice, and this is associated with alterations in red cell blood velocity. These changes may have relevance to the pathogenesis of HIV-associated neurocognitive disorders in an aging HIV positive population. PMID:24813724

  8. Characterization of nanoparticle binding dynamics in microcirculation using an adhesion probability function.

    PubMed

    Sohrabi, Salman; Yunus, Doruk Erdem; Xu, Jiang; Yang, Jie; Liu, Yaling

    2016-11-01

    Quantitative understanding of nanoparticles transport and adhesion dynamic in microcirculation is very challenging due to complexity of fluid dynamics and imaging setup. In-vitro experiments within microfluidic channels showed the significant influence of shear rate, carrier size, particle-substrate chemistry and vessel geometry on particle deposition rate. However, there are few theoretical models that can accurately predict experimental results. We have developed a numerical model to predict nanoparticle transport and binding dynamics and verified with our previous in-vitro tests results. A binding probability function is used to simplify the carrier attachment and detachment processes. Our results showed that due to the complex dynamics of particle transport and adhesion mechanism, the correlation between binding probability and actual deposition rate is not linear. Using experimental data, it is shown that the binding probability of small particles changes slightly with shear rate whereas the chance of binding for big particles decreases exponentially with shear. Our particulate model also captured some phenomena that cannot be achieved by continuum approach such as accumulation of drug particles in close vicinity of vessel wall. In addition, the effects of channel geometry and antibody density on particle binding are discussed extensively. The results from our particulate approach agrees well with experimental data suggesting that it can be used as a simple, yet efficient predictive tool for studying drug carrier binding in microcirculation. PMID:27423938

  9. Pilot Study of Laser Doppler Measurement of Flow Variability in the Microcirculation of the Palatal Mucosa.

    PubMed

    Le Bars, Pierre; Niagha, Gaston; Kouadio, Ayepa Alain; Demoersman, Julien; Roy, Elisabeth; Armengol, Valérie; Soueidan, Assem

    2016-01-01

    Background. Histopathological alterations can arise when the denture-supporting mucosa experiences microbial and mechanical stress through the denture base and diagnosis of these diseases usually follows microvascular changes. Microcirculation measurement could allow for detection of such dysfunction and aid in the early diagnosis of palatal mucosa pathologies. Materials and Methods. We tested the sensitivity of laser Doppler for measuring the microcirculation of the palatal mucosa, assessing the median raphe (MR), Schroeder area (SA), and retroincisive papilla (RP). A Doppler PeriFlux 5000 System, containing a laser diode, was used. 54 healthy participants were recruited. We compare the measurements of PU (perfusion unit) using ANOVA test. Results. The numerical values for palatal mucosa blood flow differed significantly among the anatomical areas (p = 0.0167). The mean value of Schroeder area was 92.6 (SD: 38.4) and was significantly higher than the retroincisive papilla (51.9) (SD: 20.2) (p < 0.05), which in turn was higher than that of median raphe (31.9) (SD: 24.2) (p < 0.0001). Conclusion. Schroeder area appeared to have the greatest sensitivity, and vascular flow variability among individuals was also greatest in this region. We suggest that analysis of blood stream modification with laser Doppler of the palatal mucosa can help to detect onset signs of pathological alterations.

  10. Cerebral microcirculation shear stress levels determine Neisseria meningitidis attachment sites along the blood–brain barrier

    PubMed Central

    Mairey, Emilie; Genovesio, Auguste; Donnadieu, Emmanuel; Bernard, Christine; Jaubert, Francis; Pinard, Elisabeth; Seylaz, Jacques; Olivo-Marin, Jean-Christophe; Nassif, Xavier; Duménil, Guillaume

    2006-01-01

    Neisseria meningitidis is a commensal bacterium of the human nasopharynx. Occasionally, this bacterium reaches the bloodstream and causes meningitis after crossing the blood–brain barrier by an unknown mechanism. An immunohistological study of a meningococcal sepsis case revealed that neisserial adhesion was restricted to capillaries located in low blood flow regions in the infected organs. This study led to the hypothesis that drag forces encountered by the meningococcus in the bloodstream determine its attachment site in vessels. We therefore investigated the ability of N. meningitidis to bind to endothelial cells in the presence of liquid flow mimicking the bloodstream with a laminar flow chamber. Strikingly, average blood flows reported for various organs strongly inhibited initial adhesion. As cerebral microcirculation is known to be highly heterogeneous, cerebral blood velocity was investigated at the level of individual vessels using intravital imaging of rat brain. In agreement with the histological study, shear stress levels compatible with meningococcal adhesion were only observed in capillaries, which exhibited transient reductions in flow. The flow chamber assay revealed that, after initial attachment, bacteria resisted high blood velocities and even multiplied, forming microcolonies resembling those observed in the septicemia case. These results argue that the combined mechanical properties of neisserial adhesion and blood microcirculation target meningococci to transiently underperfused cerebral capillaries and thus determine disease development. PMID:16864659

  11. Cilostazol improves hepatic blood perfusion, microcirculation, and liver regeneration after major hepatectomy in rats.

    PubMed

    von Heesen, Maximilian; Dold, Stefan; Müller, Simon; Scheuer, Claudia; Kollmar, Otto; Schilling, Martin K; Menger, Michael D; Moussavian, Mohammed R

    2015-06-01

    Major hepatectomy or small-for-size liver transplantation may result in postoperative liver failure. So far, no treatment is available to improve liver regeneration. Herein, we studied whether cilostazol, a selective phosphodiesterase III inhibitor, is capable of improving liver regeneration after major hepatectomy. Sprague-Dawley rats (n = 74) were treated with cilostazol (5 mg/kg daily) or a glucose solution and underwent either 70% liver resection or a sham operation. Before and after surgery, hepatic arterial and portal venous blood flow and hepatic microvascular perfusion were analyzed. Liver morphology, function, and regeneration were studied with histology, immunohistochemistry, western blotting, and bile excretion analysis. Cilostazol significantly increased hepatic blood flow and microcirculation before and after hepatectomy in comparison with sham-operated controls. This was associated with an elevation of hepatic vascular endothelial growth factor expression, an increase of hepatocellular proliferation, and an acceleration of liver regeneration. Furthermore, cilostazol protected the tissue of the remnant liver as indicated by an attenuation of hepatocellular disintegration. In conclusion, cilostazol increases hepatic blood perfusion, microcirculation, and liver regeneration after a major hepatectomy. Thus, cilostazol may represent a novel strategy to reduce the rate of liver failure after both extended hepatectomy and small-for-size liver transplantation.

  12. Effect of tetracaine-induced spinal anesthesia on pial microcirculation in pentobarbital anesthetized rats.

    PubMed

    Lin, Jun; Lu, Gabriel

    2009-07-01

    Local anesthetic is administrated intrathecally to produce spinal anesthesia. This study examines the effect of spinal anesthesia induced by intrathecal tetracaine on cerebral pial microcirculation in rats. We monitored changes in the mean arterial pressure, internal diameter (ID) of the pial arteriole, intracranial pressure, and red blood cell velocity. The regional cerebral blood flow was calculated from the product of cross sectional area and red blood cell velocity. To induce spinal anesthesia, tetracaine was administered via a polyethylene tube at the L4-5 intervertebral space after laminectomy. Arterial blood pressure was monitored via a catheter in the femoral artery. A left parietal craniotomy with an encapsulated cranial window was prepared for biomicroscopy. Change in the arteriolar ID was measured by image shearing. Red blood cell velocity was measured by the dual-slit photometric method and correlation technique. Three levels of spinal anesthesia were evaluated. Tetracaine at 0.1 and 0.2 mg/kg, which produced T10 and T6 sensory block, respectively, did not cause significant change of ID of the pial arteriole and red blood cell velocity. Tetracaine (0.3 mg/kg) produced total spinal block, resulting in a significant decrease of the calculated cerebral blood flow and caused brief pial arteriolar vasodilation followed by vasoconstriction. Our results show that total spinal anesthesia with tetracaine causes significant changes in rat cerebral microcirculation.

  13. Label-free in vivo optical imaging of functional microcirculations within meninges and cortex in mice.

    PubMed

    Jia, Yali; Wang, Ruikang K

    2010-12-15

    Abnormal microcirculation within meninges is common in many neurological diseases. There is a need for an imaging method that is capable of monitoring dynamic meningeal microcirculations, preferably decoupled from cortical blood flow. Optical microangiography (OMAG) is a recently developed label-free imaging method capable of producing 3D images of dynamic blood perfusion within micro-circulatory tissue beds at an imaging depth up to ∼2 mm, with an unprecedented imaging sensitivity to blood flow at ∼4 μm/s. In this paper, we demonstrate the utility of OMAG in imaging the detailed blood flow distributions, at a capillary level resolution, within the meninges and cortex in mice with the cranium left intact. Using a thrombotic mouse model, we show that the OMAG can yield longitudinal measurements of meningeal vascular responses to the insult and can decouple these responses from those in the cortex, giving valuable information regarding the localized hemodynamics along with the dynamic formation of thrombotic event. The results indicate that OMAG can be a useful tool to study therapeutic strategies in preclinical animal models in order to mitigate various pathologies that are mainly related to the meningeal circulations.

  14. A new contrast-assisted method in microcirculation volumetric flow assessment

    NASA Astrophysics Data System (ADS)

    Lu, Sheng-Yi; Chen, Yung-Sheng; Yeh, Chih-Kuang

    2007-03-01

    Microcirculation volumetric flow rate is a significant index in diseases diagnosis and treatment such as diabetes and cancer. In this study, we propose an integrated algorithm to assess microcirculation volumetric flow rate including estimation of blood perfused area and corresponding flow velocity maps based on high frequency destruction/contrast replenishment imaging technique. The perfused area indicates the blood flow regions including capillaries, arterioles and venules. Due to the echo variance changes between ultrasonic contrast agents (UCAs) pre- and post-destruction two images, the perfused area can be estimated by the correlation-based approach. The flow velocity distribution within the perfused area can be estimated by refilling time-intensity curves (TICs) after UCAs destruction. Most studies introduced the rising exponential model proposed by Wei (1998) to fit the TICs. Nevertheless, we found the TICs profile has a great resemblance to sigmoid function in simulations and in vitro experiments results. Good fitting correlation reveals that sigmoid model was more close to actual fact in describing destruction/contrast replenishment phenomenon. We derived that the saddle point of sigmoid model is proportional to blood flow velocity. A strong linear relationship (R = 0.97) between the actual flow velocities (0.4-2.1 mm/s) and the estimated saddle constants was found in M-mode and B-mode flow phantom experiments. Potential applications of this technique include high-resolution volumetric flow rate assessment in small animal tumor and the evaluation of superficial vasculature in clinical studies.

  15. In Vivo Monitoring of Microcirculation in Burn Healing Process with Optical Microangiography

    PubMed Central

    Qin, Wan; Li, Yuandong; Wang, Jingang; Qi, Xiaoli; Wang, Ruikang K.

    2016-01-01

    Objective: Optical microangiography (OMAG)-based optical coherence tomography is a noninvasive technique capable of imaging functional microvasculature innervating scanned tissue volume. In this study, we utilize OMAG to investigate dynamic changes of microcirculation during the healing process of a burn. Approach: A soft-contact superficial burn injury was induced on a mouse ear with 1 μL 70°C hot water. Microangiograms were generated by using OMAG before and after the burn. Results: Vessel recruitment and remodeling were observed in the healing process. Burn injury reached to the worst extent within the first 24 h and had no expansion thereafter. The interrupted microcirculation in the mouse ear was progressively recovered in the consequent postburn days and completely healed on postburn day 7. Innovation: OMAG provides a novel way for noninvasive visualization and quantification of vasculature changes over time after burn injuries. The high resolution achieved by the imaging system reveals microvascular details down to capillary level. Conclusion: Our results demonstrated that OMAG has great potential to improve the understanding of microcirculatory responses to burns and thus benefit the development of effective therapeutics. PMID:27602252

  16. High sensitive volumetric imaging of renal microcirculation in vivo using ultrahigh sensitive optical microangiography

    NASA Astrophysics Data System (ADS)

    Zhi, Zhongwei; Jung, Yeongri; Jia, Yali; An, Lin; Wang, Ruikang K.

    2011-03-01

    We present a non-invasive, label-free imaging technique called Ultrahigh Sensitive Optical Microangiography (UHSOMAG) for high sensitive volumetric imaging of renal microcirculation. The UHS-OMAG imaging system is based on spectral domain optical coherence tomography (SD-OCT), which uses a 47000 A-line scan rate CCD camera to perform an imaging speed of 150 frames per second that takes only ~7 seconds to acquire a 3D image. The technique, capable of measuring slow blood flow down to 4 um/s, is sensitive enough to image capillary networks, such as peritubular capillaries and glomerulus within renal cortex. We show superior performance of UHS-OMAG in providing depthresolved volumetric images of rich renal microcirculation. We monitored the dynamics of renal microvasculature during renal ischemia and reperfusion. Obvious reduction of renal microvascular density due to renal ischemia was visualized and quantitatively analyzed. This technique can be helpful for the assessment of chronic kidney disease (CKD) which relates to abnormal microvasculature.

  17. Insights Into Microcirculation Underlying Critical Limb Ischemia by Single-Photon Emission Computed Tomography

    PubMed Central

    Liu, Jung-Tung; Chang, Cheng-Siu; Su, Chen-Hsing; Li, Cho-Shun

    2015-01-01

    Abstract Perfusion difference is used as a parameter to evaluate microcirculation. This study aims to differentiate lower-limb perfusion insufficiency from neuropathy to prevent possible occurrence of failed back surgery syndrome (FBSS). Patients were retrospectively gathered from 134 FBSS cases diagnosed in the past 7 years. Up to 82 cases that were excluded from neuralgia by radiologic imaging, electrodiagnostic electromyography, and nerve conduction velocity were enrolled in this study. Perfusion difference was evaluated by single-photon emission computed tomography, and pain intensities were recorded via visual analog scale (VAS) score. Lower perfusion at the left leg comprises 51.2% (42 of 82) of the patients. The mean perfusion difference of the 82 patients was 0.86 ± 0.05 (range: 0.75–0.93). Patients with systemic vascular diseases exhibited significantly higher perfusion difference than that of patients without these related diseases (P < 0.05), except for renal insufficiency (P = 0.134). Significant correlation was observed between perfusion difference and VAS score (r = −0.78; P < 0.0001; n = 82). In this study, we presented perfusion difference as a parameter for evaluating microcirculation, which cannot be detected by ultrasonography or angiography. PMID:26166084

  18. Microscopic Local Measurement of Blood Flow and Oxygen Tension in Brain Microcirculation

    NASA Astrophysics Data System (ADS)

    Minamitani, Haruyuki; Takahashi, Ryota; Tsukada, Kousuke

    A multi-photonic imaging system was proposed for measuring blood flow velocity, vessel diameter and blood oxygen tension pO2 simultaneously with high spatio-temporal resolution in the parenchymatous organ microcirculation, such as pial tissue, by using a closed cranial window and two light sources. FITC-stained erythrocytes was used to visualize the microcirculation, and the fluorescent image was recorded by a high-speed video camera for measuring blood flow velocity. Oxygen tension pO2 was measured by oxygen-dependent quenching of phosphorescent molecules, Pd-TCPP, in the microvessels after irradiation of second harmonic light of Nd:YAG pulse laser (532nm). Animal experiments were performed for investigation of blood flow dynamics and oxygen diffusion phenomenon during acute cerebral ischemia using photochemical thrombus formation in the closed cranial window of male Wistar rats. Experimental results showed specific and significant blood flow and oxygen diffusion phenomena related to the abnormal organ tissues, from those the proposed technique would contribute to the trasnlational research for the clinical medicine, concerned in the ischemic dysfunction, angiogenisis, tumorgenisis and so on.

  19. Changes in microcirculation as early markers for infection in preterm infants--an observational prospective study.

    PubMed

    Weidlich, Kathrin; Kroth, Julia; Nussbaum, Claudia; Hiedl, Stephan; Bauer, Andreas; Christ, Frank; Genzel-Boroviczeny, Orsolya

    2009-10-01

    In adults with severe sepsis, the disturbances of the sublingual microcirculation can be quantified with orthogonal polarization spectral imaging. We investigated the cutaneous microcirculation of preterm infants with proven infection (PosInf) and with suspected but unproven infection (NegInf). In 25 infants, orthogonal polarization spectral images were obtained daily, videos of the images were blinded, and analyzed off-line. Functional small vessel density (FSVD) was prospectively calculated from day 3 to day 30 of life. There were 17 episodes of proven and nine episodes of suspected but unproven nosocomial late onset infection. Four infants remained healthy. The data were analyzed for the 5 d before the start of antibiotics (day -5 until day -1). FSVD varied widely, but in the PosInf-group, we found a 10% decline from day -5 to day -1 (p = 0.013). There was no significant change over time in the NegInf-group (p = 0.58). Thus, in infants with proven infection, FSVD decreases already 1 d before changes in laboratory parameters. However, these changes in FSVD during infection are not represented by absolute values, but must be identified by daily intraindividual observation. PMID:19581833

  20. Evaluation of three inverse problem models to quantify skin microcirculation using diffusion-weighted MRI

    NASA Astrophysics Data System (ADS)

    Cordier, G.; Choi, J.; Raguin, L. G.

    2008-11-01

    Skin microcirculation plays an important role in diseases such as chronic venous insufficiency and diabetes. Magnetic resonance imaging (MRI) can provide quantitative information with a better penetration depth than other noninvasive methods, such as laser Doppler flowmetry or optical coherence tomography. Moreover, successful MRI skin studies have recently been reported. In this article, we investigate three potential inverse models to quantify skin microcirculation using diffusion-weighted MRI (DWI), also known as q-space MRI. The model parameters are estimated based on nonlinear least-squares (NLS). For each of the three models, an optimal DWI sampling scheme is proposed based on D-optimality in order to minimize the size of the confidence region of the NLS estimates and thus the effect of the experimental noise inherent to DWI. The resulting covariance matrices of the NLS estimates are predicted by asymptotic normality and compared to the ones computed by Monte-Carlo simulations. Our numerical results demonstrate the effectiveness of the proposed models and corresponding DWI sampling schemes as compared to conventional approaches.

  1. Robust optimal design of diffusion-weighted magnetic resonance experiments for skin microcirculation

    NASA Astrophysics Data System (ADS)

    Choi, J.; Raguin, L. G.

    2010-10-01

    Skin microcirculation plays an important role in several diseases including chronic venous insufficiency and diabetes. Magnetic resonance (MR) has the potential to provide quantitative information and a better penetration depth compared with other non-invasive methods such as laser Doppler flowmetry or optical coherence tomography. The continuous progress in hardware resulting in higher sensitivity must be coupled with advances in data acquisition schemes. In this article, we first introduce a physical model for quantifying skin microcirculation using diffusion-weighted MR (DWMR) based on an effective dispersion model for skin leading to a q-space model of the DWMR complex signal, and then design the corresponding robust optimal experiments. The resulting robust optimal DWMR protocols improve the worst-case quality of parameter estimates using nonlinear least squares optimization by exploiting available a priori knowledge of model parameters. Hence, our approach optimizes the gradient strengths and directions used in DWMR experiments to robustly minimize the size of the parameter estimation error with respect to model parameter uncertainty. Numerical evaluations are presented to demonstrate the effectiveness of our approach as compared to conventional DWMR protocols.

  2. An experimental model for minimizing errors in laser speckle contrast imaging for microcirculation analysis

    NASA Astrophysics Data System (ADS)

    Sujatha, N.; Banerjee, Arnab

    2015-03-01

    Understanding the changes in microcirculatory flow and its measurements are very important for assessing the progress of various vascular malfunctions and their subsequent treatment effectiveness. Laser Speckle Contrast Imaging (LSCI) has been evolved as a whole-field, non-invasive and non-contact technique which has inherent advantages for microcirculation assessment in an in vivo environment compared to its noninvasive counterparts such as laser Doppler technique and video capillaroscopy. However, representation of flow velocity values in absolute units is still challenging and yet to be completely explored. In this paper, we propose an experimental model for estimating the flow velocity based for optimum camera exposure time. The LSCI experiments were conducted on a custom made phantom flow channel with induced flow in the microcirculation range using a syringe pump. The speckle image contrast was estimated temporally and is used to calculate velocity values. The relative error in the flow values is estimated to be a function of the calculated contrast. The estimated error has been incorporated as a correction factor in the obtained velocity term using LSCI and final velocity estimation was found to be within an acceptable error range independent of the flow velocity and scatterer concentration of the sample for optimum camera exposure duration.

  3. Improvement of Impaired Cerebral Microcirculation Using Rheological Modulation by Drag-Reducing Polymers.

    PubMed

    Bragin, D E; Peng, Z; Bragina, O A; Statom, G L; Kameneva, M V; Nemoto, E M

    2016-01-01

    Nanomolar intravascular concentrations of drag-reducing polymers (DRP) have been shown to improve hemodynamics and survival in animal models of ischemic myocardium and limb, but the effects of DRP on the cerebral microcirculation have not yet been studied. We recently demonstrated that DRP enhance microvascular flow in normal rat brain and hypothesized that it would restore impaired microvascular perfusion and improve outcomes after focal ischemia and traumatic brain injury (TBI). We studied the effects of DRP (high molecular weight polyethylene oxide, 4000 kDa, i.v. at 2 μg/mL of blood) on microcirculation of the rat brain: (1) after permanent middle cerebral artery occlusion (pMCAO); and (2) after TBI induced by fluid percussion. Using in vivo two-photon laser scanning microscopy (2PLSM) over the parietal cortex of anesthetized rats we showed that both pMCAO and TBI resulted in progressive decrease in microvascular circulation, leading to tissue hypoxia (NADH increase) and increased blood brain barrier (BBB) degradation. DRP, injected post insult, increased blood volume flow in arterioles and red blood cell (RBC) flow velocity in capillaries mitigating capillary stasis, tissue hypoxia and BBB degradation, which improved neuronal survival (Fluoro-Jade B, 24 h) and neurologic outcome (Rotarod, 1 week). Improved microvascular perfusion by DRP may be effective in the treatment of ischemic stroke and TBI. PMID:27526149

  4. Intravenous contrast medium aggravates the impairment of pancreatic microcirculation in necrotizing pancreatitis in the rat.

    PubMed Central

    Schmidt, J; Hotz, H G; Foitzik, T; Ryschich, E; Buhr, H J; Warshaw, A L; Herfarth, C; Klar, E

    1995-01-01

    BACKGROUND: Previous reports demonstrated that radiographic contrast medium, as used in contrast-enhanced computed tomography, increases acinar necrosis and mortality in experimental pancreatitis. The authors studied the possibility that these changes may be related to an additional impairment of pancreatic microcirculation. METHODS: Fifty Wistar rats had acute pancreatitis induced by intraductal glycodeoxycholic acid (10 mmol/L for 10 min) and intravenous cerulein (5 micrograms/kg/hr for 6 hrs). After rehydration (16 mL/kg), pancreatic capillary perfusion was quantified by means of intravital microscopy at baseline before intravenous infusion of contrast medium (n = 25) or saline (n = 25), and 30 and 60 minutes thereafter. In addition to total capillary flow, capillaries were categorized as high- or low-flow (> or < 1.6 nL/min). RESULTS: Pancreatic capillary flow did not change in either high- or low-flow capillaries after saline infusion. However, contrast medium infusion induced a significant decrease of total capillary flow (p < 0.001). Analysis according to the relative flow rate revealed that this was primarily because of a significant additional reduction of perfusion in low-flow capillaries (p < 0.0001). Furthermore, complete capillary stasis was observed in 15.9 +/- 3.4% after contrast medium as compared with 3.2 +/- 1.2% after saline infusion (p < 0.006). CONCLUSION: Radiographic contrast medium aggravates the impairment of pancreatic microcirculation in experimental necrotizing pancreatitis. PMID:7717779

  5. Imaging photoplethysmography for clinical assessment of cutaneous microcirculation at two different depths

    NASA Astrophysics Data System (ADS)

    Marcinkevics, Zbignevs; Rubins, Uldis; Zaharans, Janis; Miscuks, Aleksejs; Urtane, Evelina; Ozolina-Moll, Liga

    2016-03-01

    The feasibility of bispectral imaging photoplethysmography (iPPG) system for clinical assessment of cutaneous microcirculation at two different depths is proposed. The iPPG system has been developed and evaluated for in vivo conditions during various tests: (1) topical application of vasodilatory liniment on the skin, (2) skin local heating, (3) arterial occlusion, and (4) regional anesthesia. The device has been validated by the measurements of a laser Doppler imager (LDI) as a reference. The hardware comprises four bispectral light sources (530 and 810 nm) for uniform illumination of skin, video camera, and the control unit for triggering of the system. The PPG signals were calculated and the changes of perfusion index (PI) were obtained during the tests. The results showed convincing correlations for PI obtained by iPPG and LDI at (1) topical liniment (r=0.98) and (2) heating (r=0.98) tests. The topical liniment and local heating tests revealed good selectivity of the system for superficial microcirculation monitoring. It is confirmed that the iPPG system could be used for assessment of cutaneous perfusion at two different depths, morphologically and functionally different vascular networks, and thus utilized in clinics as a cost-effective alternative to the LDI.

  6. Semisynthetic hybrid biopolymers for non-pharmacological intervention of the microcirculation.

    PubMed

    Salazar Vázquez, Beatriz Y; Hightower, C Makena; Yalcin, Ozlem; Acharya, Seetharama A; Intaglietta, Marcos

    2013-06-01

    The microcirculation presents functional organic structures in the range of 1-100 micrometers, commensurate with the upper end of nanotechnology constructs. When devices are designed and deployed to deliver treatment via the circulation they ultimately contend with the smallest dimensions of both healthy and impaired microvessels, particularly the capillary system whose ability to sustain the tissue is assessed by measuring "functional capillary density" (FCD). FCD is directly determined by hydrostatic and osmotic pressures and indirectly by the effect of cardiovascular regulators, particularly the bioavailability of nitric oxide (NO) resulting from fluid mechanical effects and transport in the submicroscopic cell free plasma layer (CFL) located between blood and microvascular wall. Macromolecules using colloids as templates that are surface decorated with polyethylene glycol (PEG) become immuno-invisible and can be introduced into the circulation to manipulate the NO environment in blood and the endothelium. PEG-albumin is a class of molecules with novel plasma expansion properties that directly interacts with the microcirculation via CFL related effects. The principal application of this technology is in transfusion medicine and the plasma expanders used to treat blood losses and concomitant effects on microvascular function due to related acute inflammatory conditions and ischemia.

  7. Pilot Study of Laser Doppler Measurement of Flow Variability in the Microcirculation of the Palatal Mucosa

    PubMed Central

    Le Bars, Pierre; Niagha, Gaston; Kouadio, Ayepa Alain; Demoersman, Julien; Roy, Elisabeth; Armengol, Valérie; Soueidan, Assem

    2016-01-01

    Background. Histopathological alterations can arise when the denture-supporting mucosa experiences microbial and mechanical stress through the denture base and diagnosis of these diseases usually follows microvascular changes. Microcirculation measurement could allow for detection of such dysfunction and aid in the early diagnosis of palatal mucosa pathologies. Materials and Methods. We tested the sensitivity of laser Doppler for measuring the microcirculation of the palatal mucosa, assessing the median raphe (MR), Schroeder area (SA), and retroincisive papilla (RP). A Doppler PeriFlux 5000 System, containing a laser diode, was used. 54 healthy participants were recruited. We compare the measurements of PU (perfusion unit) using ANOVA test. Results. The numerical values for palatal mucosa blood flow differed significantly among the anatomical areas (p = 0.0167). The mean value of Schroeder area was 92.6 (SD: 38.4) and was significantly higher than the retroincisive papilla (51.9) (SD: 20.2) (p < 0.05), which in turn was higher than that of median raphe (31.9) (SD: 24.2) (p < 0.0001). Conclusion. Schroeder area appeared to have the greatest sensitivity, and vascular flow variability among individuals was also greatest in this region. We suggest that analysis of blood stream modification with laser Doppler of the palatal mucosa can help to detect onset signs of pathological alterations. PMID:27340663

  8. Improvement of Impaired Cerebral Microcirculation Using Rheological Modulation by Drag-Reducing Polymers.

    PubMed

    Bragin, D E; Peng, Z; Bragina, O A; Statom, G L; Kameneva, M V; Nemoto, E M

    2016-01-01

    Nanomolar intravascular concentrations of drag-reducing polymers (DRP) have been shown to improve hemodynamics and survival in animal models of ischemic myocardium and limb, but the effects of DRP on the cerebral microcirculation have not yet been studied. We recently demonstrated that DRP enhance microvascular flow in normal rat brain and hypothesized that it would restore impaired microvascular perfusion and improve outcomes after focal ischemia and traumatic brain injury (TBI). We studied the effects of DRP (high molecular weight polyethylene oxide, 4000 kDa, i.v. at 2 μg/mL of blood) on microcirculation of the rat brain: (1) after permanent middle cerebral artery occlusion (pMCAO); and (2) after TBI induced by fluid percussion. Using in vivo two-photon laser scanning microscopy (2PLSM) over the parietal cortex of anesthetized rats we showed that both pMCAO and TBI resulted in progressive decrease in microvascular circulation, leading to tissue hypoxia (NADH increase) and increased blood brain barrier (BBB) degradation. DRP, injected post insult, increased blood volume flow in arterioles and red blood cell (RBC) flow velocity in capillaries mitigating capillary stasis, tissue hypoxia and BBB degradation, which improved neuronal survival (Fluoro-Jade B, 24 h) and neurologic outcome (Rotarod, 1 week). Improved microvascular perfusion by DRP may be effective in the treatment of ischemic stroke and TBI.

  9. Blood volume redistribution from a passive elastic permeable microcirculation due to hypovolemia.

    PubMed

    LaForte, A J; Lee, L P; Rich, G F; Skalak, T C; Lee, J S

    1994-06-01

    We measured the variations in blood and plasma density for a cyclic hemorrhage protocol in conscious rabbits to calculate delta Vf [the volume of fluid restituted into the circulation from the time the blood volume was at its control to that after the hemorrhage of a blood volume (delta V)] and delta Vs (the volume shift from micro- to macrocirculation over the same time interval). We found that delta Vf is 7% of delta V and delta Vs 60% of delta V. They combine to reduce the effect of hemorrhage on macrovascular volume by 67% of delta V. Based on a two-resistor circulation model, the change in microcirculatory pressure (delta Pmic) from control to hemorrhage was estimated from the measured cardiac outputs and arterial and venous pressures. The computations indicate that delta Vs (or delta Vf) is linearly related to delta Pmic. With one relation fitting all data of rabbits that were conscious, infused with hexamethonium, and anesthetized with pentobarbital sodium, we concluded that the two short-term volume redistributions are not direct neural control or local regulation, but the response of a passive, permeable microcirculation to delta Pmic. From the linear relations, we obtained 0.88 ml.mmHg-1.kg-1 as the compliance of the rabbit microcirculation and 0.21 ml.min-1.mmHg-1.kg-1 as its filtration coefficient. PMID:7912898

  10. In Vivo Monitoring of Microcirculation in Burn Healing Process with Optical Microangiography

    PubMed Central

    Qin, Wan; Li, Yuandong; Wang, Jingang; Qi, Xiaoli; Wang, Ruikang K.

    2016-01-01

    Objective: Optical microangiography (OMAG)-based optical coherence tomography is a noninvasive technique capable of imaging functional microvasculature innervating scanned tissue volume. In this study, we utilize OMAG to investigate dynamic changes of microcirculation during the healing process of a burn. Approach: A soft-contact superficial burn injury was induced on a mouse ear with 1 μL 70°C hot water. Microangiograms were generated by using OMAG before and after the burn. Results: Vessel recruitment and remodeling were observed in the healing process. Burn injury reached to the worst extent within the first 24 h and had no expansion thereafter. The interrupted microcirculation in the mouse ear was progressively recovered in the consequent postburn days and completely healed on postburn day 7. Innovation: OMAG provides a novel way for noninvasive visualization and quantification of vasculature changes over time after burn injuries. The high resolution achieved by the imaging system reveals microvascular details down to capillary level. Conclusion: Our results demonstrated that OMAG has great potential to improve the understanding of microcirculatory responses to burns and thus benefit the development of effective therapeutics.

  11. Wavelet-analysis of gastric microcirculation in rats with ulcer bleedings

    NASA Astrophysics Data System (ADS)

    Pavlov, A. N.; Semyachkina-Glushkovskaya, O. V.; Pavlova, O. N.; Bibikova, O. A.; Kurths, J.

    2013-10-01

    Nitric oxide (NO) plays an important role in regulation of central and peripheral circulation in normal state and during hemorrhagic stress. Because the impaired gastric mucosal blood flow is the major cause of gastroduodenal lesions including ulcer bleeding (UB), we study in this work the NO-ergic mechanism responsible for regulation of this blood flow. Our study is performed in rats with a model of stress-induced UB using laser Doppler flowmetry (LDF) that characterizes the rate of blood flow by measuring a Doppler shift of the laser beam scattered by the moving red blood cells. Numerical analysis of LDF-data is based on the discrete wavelet-transform (DWT) using Daubechies wavelets aiming to quantify influences of NO on the gastric microcirculation. We show that the stress-induced UB is associated with an increased level of NO in the gastric tissue and a stronger vascular sensitivity to pharmacological modulation of NO-production by L-NAME. We demonstrate that wavelet-based analyses of NO-dependent regulation of gastric microcirculation can provide an effective endoscopic diagnostics of a risk of UB.

  12. Polysomnographic findings in nights preceding a migraine attack.

    PubMed

    Göder, R; Fritzer, G; Kapsokalyvas, A; Kropp, P; Niederberger, U; Strenge, H; Gerber, W D; Aldenhoff, J B

    2001-02-01

    Sleep recordings were performed in eight patients to analyse sleep alterations preceding migraine attacks. Polysomnographic recordings from nights before an attack were compared with nights without following migraine. We analysed standard sleep parameters and electroencephalogram (EEG) power spectra. The main findings preceding migraine attacks were a significant decrease in the number of arousals, a decrease in rapid eye movement (REM) density, a significant decrease of beta power in the slow wave sleep, and a decrease of alpha power during the first REM period. The results suggest a decrease in cortical activation during sleep preceding migraine attacks. According to the models of sleep regulation, alterations in the function of aminergic or cholinergic brainstem nuclei have to be discussed. PMID:11298661

  13. Preceding trauma in childhood hematogenous bone and joint infections.

    PubMed

    Pääkkönen, Markus; Kallio, Markku J T; Lankinen, Petteri; Peltola, Heikki; Kallio, Pentti E

    2014-03-01

    Preceding trauma may play a role in the etiology and pathogenesis of hematogenous bone and joint infections. Among 345 children with an acute hematogenous bone and/or joint infection, 20% reported trauma during a 2-week period leading to infection. Blunt impact, bruises, or excoriations were commonly reported. The rate was similar to that in the general pediatric population obtained from the literature. In the study group, patients with and without trauma were similar in age, serum C-reactive protein and erythrocyte sedimentation rate, length of hospitalization, and late sequelae. Preceding minor trauma did not prove to be significant as an etiological or as a prognostic factor.

  14. In vivo microcirculation imaging of the sub surface fingertip using correlation mapping optical coherence tomography (cmOCT)

    NASA Astrophysics Data System (ADS)

    Dsouza, Roshan I.; Zam, Azhar; Subhash, Hrebesh M.; Larin, Kirill V.; Leahy, Martin

    2013-02-01

    We describe a novel application of correlation mapping optical coherence tomography (cmOCT) for sub-surface fingerprint biometric identification. Fingerprint biometrics including automated fingerprint identification systems, are commonly used to recognise the fingerprint, since they constitute simple, effective and valuable physical evidence. Spoofing of biometric fingerprint devices can be easily done because of the limited information obtained from the surface topography. In order to overcome this limitation a potentially more secure source of information is required for biometric identification applications. In this study, we retrieve the microcirculation map of the subsurface fingertip by use of the cmOCT technique. To increase probing depth of the sub surface microcirculation, an optical clearing agent composed of 75% glycerol in aqueous solution was applied topically and kept in contact for 15 min. OCT intensity images were acquired from commercial research grade swept source OCT system (model OCT1300SS, Thorlabs Inc. USA). A 3D OCT scan of the fingertip was acquired over an area of 5x5 mm using 1024x1024 A-scans in approximately 70 s. The resulting volume was then processed using the cmOCT technique with a 7x7 kernel to provide a microcirculation map. We believe these results will demonstrate an enhanced security level over artificial fingertips. To the best of our knowledge, this is the first demonstration of imaging microcirculation map of the subsurface fingertip.

  15. Blood microcirculation monitoring by use of spatial filtering of time-integrated speckle patterns: potentialities to improve the depth resolution

    NASA Astrophysics Data System (ADS)

    Zimnyakov, Dmitry A.; Misnin, Alexander B.

    2001-06-01

    Statistical analysis of images of time-integrated dynamic speckle patterns is considered as the tool for diagnostics and imaging of in vivo tissue dynamics such as blood microcirculation in superficial layers of human tissues and organs. Basic approach for blood microcirculation monitoring using the contrast analysis of time-averaged speckle images is known as LASCA (Laser Speckle Contrast Analysis) technique. This paper presents the modified version of LASCA, which is based on application of the localized probe light source and the spatial filtration of analyzed speckle pattern in the object plane. Being compared with classical LASCA technique, this method has the certain disadvantage as the necessity of scanning procedure to provide the reconstruction of maps of blood microcirculation parameters, but it gives the additional possibilities for the analysis of depth distributions of these parameters. Theoretical background for the depth-resolved analysis of blood microcirculation parameters on the basis of the concept of effective optical path distributions for multiply scattered probe light is considered. The effect of non-zero residual contrast even in the case of large integration times is also discussed.

  16. Linear-array-based photoacoustic imaging of human microcirculation with a range of high frequency transducer probes

    NASA Astrophysics Data System (ADS)

    Zafar, Haroon; Breathnach, Aedán; Subhash, Hrebesh M.; Leahy, Martin J.

    2015-05-01

    Photoacoustic imaging (PAI) with a linear-array-based probe can provide a convenient means of imaging the human microcirculation within its native structural context and adds functional information. PAI using a multielement linear transducer array combined with multichannel collecting system was used for in vivo volumetric imaging of the blood microcirculation, the total concentration of hemoglobin (HbT), and the hemoglobin oxygen saturation (sO2) within human tissue. Three-dimensional (3-D) PA and ultrasound (US) volumetric scans were acquired from the forearm skin by linearly translating the transducer with a stepper motor over a region of interest, while capturing two-dimensional images using 15, 21, and 40 MHz frequency transducer probes. For the microvasculature imaging, PA images were acquired at 800- and 1064-nm wavelengths. For the HbT and sO2 estimates, PA images were collected at 750- and 850-nm wavelengths. 3-D microcirculation, HbT, and sO2 maps of the forearm skin were obtained from normal subjects. The linear-array-based PAI has been found promising in terms of resolution, imaging depth, and imaging speed for in vivo microcirculation imaging within human skin. We believe that a reflection type probe, similar to existing clinical US probes, is most likely to succeed in real clinical applications. Its advantages include ease of use, speed, and familiarity for radiographers and clinicians.

  17. The effect of a cryotherapy gel wrap on the microcirculation of skin affected by Chronic Venous Disorders

    PubMed Central

    Mueller, Martina; Zapka, Jane G.; King, Dana E.

    2011-01-01

    Aim This randomized clinical trial was conducted 2008 – 2009 to investigate a cryotherapy (cooling) gel wrap applied to lower leg skin affected by chronic venous disorders to determine whether therapeutic cooling improves skin microcirculation. Impaired skin microcirculation contributes to venous leg ulcer development, thus new prevention therapies should address the microcirculation to prevent venous leg ulcers. Data Sources Sixty participants (n = 30 per group) were randomized to receive one of two daily 30-minute interventions for four weeks. The treatment group applied the cryotherapy gel wrap around the affected lower leg skin, or compression and elevated the legs on a special pillow each evening at bedtime. The standard care group wore compression and elevated the legs only. Laboratory pre- and post-measures included microcirculation measures of skin temperature with a thermistor, blood flow with a laser Doppler flowmeter, and venous refill time with a photoplethysmograph. Review methods Data were analysed using descriptive statistics, paired t-tests or Wilcoxon signed ranks tests, logistic regression analyses, and mixed model analyses. Results Fifty-seven participants (treatment = 28; standard care = 29) completed the study. The mean age was 62 years, 70% female, 50% African American. In the final adjusted model, there was a statistically significant decrease in blood flow between the two groups (−6.2[−11.8; −0.6], P = 0.03). No statistically significant differences were noted in temperature or venous refill time. Conclusion Study findings suggest that cryotherapy improves blood flow by slowing movement within the microcirculation and thus might potentially provide a therapeutic benefit to prevent leg ulcers. PMID:21592186

  18. High-sensitivity detection and monitoring of microcirculation using cutaneous and catheter probes for Doppler optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Yang, Victor X.; Gordon, M. L.; Qi, B.; Yue, E. Seng; Tang, S.; Bisland, Stuart K.; Pekar, J.; Lo, S.; Marcon, Norman E.; Wilson, B.; Vitkin, Alex

    2003-07-01

    Background: Currently clinical Doppler ultrasound cannot detect microvascular blood flow and it is difficult to provide depth discrimination using laser Doppler flowmetry. Doppler optical coherence tomography (DOCT) is a novel technique for noninvasive subsurface imaging of microcirculation and tissue structure. Aims: To design handheld and catheter-based DOCT probes for clinical cutaneous and endoscopic imaging. To develop signal processing techniques for real-time detection and quantification of microvascular blood flow. Methods: A DOCT system, with interchangeable cutaneous and catheter probes, was developed. The axial spatial resolution was 10 μm, and the velocity resolution was 20 μm/s, using a 1300 nm broadband infrared light. The system achieved real-time imaging with frame rates up to 32 Hz at 512 x 256 pixels per frame. We used the system to detect microcirculation in human skin and rat esophagus, and to monitor microvascular responses to photodynamic therapy (PDT) in a rat tumor model. Results: We present experimental results from in vivo DOCT imaging of microcirculation in human skin arterio-venous malformations (AVM), normal rat esophagus, and a rat gliosarcoma PDT model. In the PDT model, we followed microvascular responses to PDT and observed differences in the microcirculation during and after therapy, which can have important implications for PDT dosimetry and treatment optimization. Conclusions: To our knowledge, this is the first demonstration of endoscopic catheter-based DOCT detection of microcirculation in vivo. In addition, AVM can be detected using handheld cutaneous DOCT probes under clinical settings. DOCT may serve as a real-time monitoring tool for PDT dosimetry, especially for vascular targeting photosensitizers.

  19. Effect of adrenergic stimulation on cutaneous microcirculation immediately after surgical adventitiectomy in a rat skin flap model.

    PubMed

    Lecoq, Jean-Pierre H; Joris, Jean L; Nelissen, Xavier P; Lamy, Maurice L; Heymans, Olivier Y

    2008-01-01

    Chronic sympathetic denervation leads to the development of supersentivity to adrenergic agents. Free flap surgery results in the disruption of the autonomic nerve fibers running along the anastomosed vessels. We therefore investigated the early effect of surgical sympathectomy on the reactivity of cutaneous microcirculation challenged to adrenergic agents. Two epigastric flaps were elevated and exposed in 15 rats. On the right flap (Side A), a circular adventitiectomy of the feeder vessels was realized to provide surgical sympathectomy. On the left flap (Side N), vessels were kept intact. The following drugs were then given intravenously successively: phenylephrine (10 and 15 microg kg(-1)), norepinephrine (10 microg kg(-1)), prazocin (1 mg kg(-1)) followed by norepinephrine (10 microg kg(-1)). Cutaneous microcirculation was assessed using Laser-Doppler Flowmeters simultaneously on the two flaps after each drug administration. Mean arterial pressure was also measured. On side N, phenylephrine and norepinephrine resulted in a transient increase in cutaneous microcirculation followed by a more prolonged reduction. On side A, only the initial increase was observed, which was greater and longer as compared with side N, and paralleled the increase in mean arterial pressure. After prazocin pre-treatment, norepinephrine produced a transient increase in cutaneous microcirculation similar on both sides, and parallel to the changes in arterial pressure. No decrease in cutaneous microcirculation was observed. Immediately after surgical adventitiectomy, the vasoconstriction produced by alpha-adrenergic agents is prevented. No denervation-induced hypersentivity is observed. Surgical sympathectomy might protect cutaneous flaps from vasoconstriction induced by endogenous catecholamines release. PMID:18623150

  20. The Role of Sexual Precedence in Verbal Sexual Coercion

    ERIC Educational Resources Information Center

    Livingston, Jennifer A.; Buddie, Amy M.; Testa, Maria; VanZile-Tamsen, Carol

    2004-01-01

    Experiences of verbal sexual coercion are common and have potential for negative consequences, yet are not well understood. This study used qualitative and descriptive statistics to examine verbal sexual coercion experiences among a community sample of 114 women and explored the role of sexual precedence in these experiences. Analyses revealed…

  1. Metrical expectations from preceding prosody influence perception of lexical stress.

    PubMed

    Brown, Meredith; Salverda, Anne Pier; Dilley, Laura C; Tanenhaus, Michael K

    2015-04-01

    Two visual-world experiments tested the hypothesis that expectations based on preceding prosody influence the perception of suprasegmental cues to lexical stress. The results demonstrate that listeners' consideration of competing alternatives with different stress patterns (e.g., 'jury/gi'raffe) can be influenced by the fundamental frequency and syllable timing patterns across material preceding a target word. When preceding stressed syllables distal to the target word shared pitch and timing characteristics with the first syllable of the target word, pictures of alternatives with primary lexical stress on the first syllable (e.g., jury) initially attracted more looks than alternatives with unstressed initial syllables (e.g., giraffe). This effect was modulated when preceding unstressed syllables had pitch and timing characteristics similar to the initial syllable of the target word, with more looks to alternatives with unstressed initial syllables (e.g., giraffe) than to those with stressed initial syllables (e.g., jury). These findings suggest that expectations about the acoustic realization of upcoming speech include information about metrical organization and lexical stress and that these expectations constrain the initial interpretation of suprasegmental stress cues. These distal prosody effects implicate online probabilistic inferences about the sources of acoustic-phonetic variation during spoken-word recognition.

  2. Impact of preceding crop on alfalfa competitiveness with weeds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Organic producers would like to include no-till practices in their farming systems. We are seeking to develop a continuous no-till system for organic farming, based on a complex rotation that includes a 3-year sequence of alfalfa. In this study, we evaluated impact of preceding crop on weed infest...

  3. 48 CFR 3452.215-33 - Order of precedence.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 7 2010-10-01 2010-10-01 false Order of precedence. 3452.215-33 Section 3452.215-33 Federal Acquisition Regulations System DEPARTMENT OF EDUCATION ACQUISITION REGULATION CLAUSES AND FORMS SOLICITATION PROVISIONS AND CONTRACT CLAUSES Texts of Provisions and...

  4. Henoch-Schönlein purpura with preceding abdominal pain.

    PubMed

    Toshihiko, Kakiuchi; Tomonobu, Aoki

    2015-06-01

    Diagnosing HSP can be difficult, especially when abdominal symptoms precede the onset of characteristic palpable purpura (Chen MJ et al. 2005, World Gastroenterol., 11, 2354). Therefore, it is necessary to consider the possibility of HSP in patients with prolonged strong abdominal pain, even in cases without purpura.

  5. Henoch–Schönlein purpura with preceding abdominal pain

    PubMed Central

    Toshihiko, Kakiuchi; Tomonobu, Aoki

    2015-01-01

    Key Clinical Message Diagnosing HSP can be difficult, especially when abdominal symptoms precede the onset of characteristic palpable purpura (Chen MJ et al. 2005, World Gastroenterol., 11, 2354). Therefore, it is necessary to consider the possibility of HSP in patients with prolonged strong abdominal pain, even in cases without purpura. PMID:26185663

  6. Metrical expectations from preceding prosody influence perception of lexical stress.

    PubMed

    Brown, Meredith; Salverda, Anne Pier; Dilley, Laura C; Tanenhaus, Michael K

    2015-04-01

    Two visual-world experiments tested the hypothesis that expectations based on preceding prosody influence the perception of suprasegmental cues to lexical stress. The results demonstrate that listeners' consideration of competing alternatives with different stress patterns (e.g., 'jury/gi'raffe) can be influenced by the fundamental frequency and syllable timing patterns across material preceding a target word. When preceding stressed syllables distal to the target word shared pitch and timing characteristics with the first syllable of the target word, pictures of alternatives with primary lexical stress on the first syllable (e.g., jury) initially attracted more looks than alternatives with unstressed initial syllables (e.g., giraffe). This effect was modulated when preceding unstressed syllables had pitch and timing characteristics similar to the initial syllable of the target word, with more looks to alternatives with unstressed initial syllables (e.g., giraffe) than to those with stressed initial syllables (e.g., jury). These findings suggest that expectations about the acoustic realization of upcoming speech include information about metrical organization and lexical stress and that these expectations constrain the initial interpretation of suprasegmental stress cues. These distal prosody effects implicate online probabilistic inferences about the sources of acoustic-phonetic variation during spoken-word recognition. PMID:25621583

  7. Counselor Interventions Preceding Client Laughter in Brief Therapy.

    ERIC Educational Resources Information Center

    Falk, Dana R.; Hill, Clara E.

    1992-01-01

    Examined whether 6 categories of counselor humor and 4 categories of risk interventions preceded client laughter in 236 events from 8 cases of brief psychotherapy. Found most client laughter was mild and moderate, with only eight instances of strong laughter. Humorous interventions led to more client laughter than did interventions that encouraged…

  8. Henoch-Schönlein purpura with preceding abdominal pain.

    PubMed

    Toshihiko, Kakiuchi; Tomonobu, Aoki

    2015-06-01

    Diagnosing HSP can be difficult, especially when abdominal symptoms precede the onset of characteristic palpable purpura (Chen MJ et al. 2005, World Gastroenterol., 11, 2354). Therefore, it is necessary to consider the possibility of HSP in patients with prolonged strong abdominal pain, even in cases without purpura. PMID:26185663

  9. Metrical expectations from preceding prosody influence perception of lexical stress

    PubMed Central

    Brown, Meredith; Salverda, Anne Pier; Dilley, Laura C.; Tanenhaus, Michael K.

    2015-01-01

    Two visual-world experiments tested the hypothesis that expectations based on preceding prosody influence the perception of suprasegmental cues to lexical stress. The results demonstrate that listeners’ consideration of competing alternatives with different stress patterns (e.g., ‘jury/gi’raffe) can be influenced by the fundamental frequency and syllable timing patterns across material preceding a target word. When preceding stressed syllables distal to the target word shared pitch and timing characteristics with the first syllable of the target word, pictures of alternatives with primary lexical stress on the first syllable (e.g., jury) initially attracted more looks than alternatives with unstressed initial syllables (e.g., giraffe). This effect was modulated when preceding unstressed syllables had pitch and timing characteristics similar to the initial syllable of the target word, with more looks to alternatives with unstressed initial syllables (e.g., giraffe) than to those with stressed initial syllables (e.g., jury). These findings suggest that expectations about the acoustic realization of upcoming speech include information about metrical organization and lexical stress, and that these expectations constrain the initial interpretation of suprasegmental stress cues. These distal prosody effects implicate on-line probabilistic inferences about the sources of acoustic-phonetic variation during spoken-word recognition. PMID:25621583

  10. Microcirculation and structural reorganization of the bladder mucosa in chronic cystitis under conditions of ozone therapy.

    PubMed

    Neimark, A I; Nepomnyashchikh, L M; Lushnikova, E L; Bakarev, M A; Abdullaev, N A; Sizov, K A

    2014-01-01

    Structural reorganization of the bladder mucosa in chronic cystitis and its correction by ozone therapy were studied. A relationship between the epithelial layer restructuring of different kinds (dystrophy, metaplasia, and degeneration), level of cell proliferation, and ultrastructural organization of urotheliocytes was detected. This complex of structural reactions was combined with dysregulation of tissue bloodflow in the bladder mucosa, shown by laser Doppler flowmetry. Positive structural changes were most marked in intravesical and less so in parenteral ozone therapy added to the therapeutic complex and manifested in reduction of inflammation and alteration in parallel with more intense reparative reactions. A special feature of parenteral ozone therapy was a significant improvement of microcirculation in the bladder mucosa.

  11. Live demonstration of microcirculation in the deep fascia and its implication.

    PubMed

    Bhattacharya, V; Watts, Rajesh Kumar; Reddy, G R

    2005-02-01

    The rich vascular network in the deep fascia has been emphasized by various scientists, but the actual demonstration of live circulation in the deep fascia has not previously been witnessed. Encouraged by the sight of live circulation in the web membrane of toad hind limb, a successful attempt was made to demonstrate the live circulation in the vascular network of the deep fascia. Fascial extensions of inferiorly based fasciocutaneous flaps were dissected in five patients with distal leg and heel defects. The fascial extension in continuity with a proximal retrograde fasciocutaneous flap was mounted on a glass slide and examined under a microscope. The authors witnessed the live microcirculation and the movement of individual red blood corpuscles in vascular channels of the deep fascia. The authors also noticed that the deep fascia has two layers with circulations that are independent of one other. A video recording was made to document these important features.

  12. Video-rate imaging of microcirculation with single-exposure oblique back-illumination microscopy.

    PubMed

    Ford, Tim N; Mertz, Jerome

    2013-06-01

    Oblique back-illumination microscopy (OBM) is a new technique for simultaneous, independent measurements of phase gradients and absorption in thick scattering tissues based on widefield imaging. To date, OBM has been used with sequential camera exposures, which reduces temporal resolution, and can produce motion artifacts in dynamic samples. Here, a variation of OBM that allows single-exposure operation with wavelength multiplexing and image splitting with a Wollaston prism is introduced. Asymmetric anamorphic distortion induced by the prism is characterized and corrected in real time using a graphics-processing unit. To demonstrate the capacity of single-exposure OBM to perform artifact-free imaging of blood flow, video-rate movies of microcirculation in ovo in the chorioallantoic membrane of the developing chick are presented. Imaging is performed with a high-resolution rigid Hopkins lens suitable for endoscopy. PMID:23733023

  13. Video-rate imaging of microcirculation with single-exposure oblique back-illumination microscopy

    NASA Astrophysics Data System (ADS)

    Ford, Tim N.; Mertz, Jerome

    2013-06-01

    Oblique back-illumination microscopy (OBM) is a new technique for simultaneous, independent measurements of phase gradients and absorption in thick scattering tissues based on widefield imaging. To date, OBM has been used with sequential camera exposures, which reduces temporal resolution, and can produce motion artifacts in dynamic samples. Here, a variation of OBM that allows single-exposure operation with wavelength multiplexing and image splitting with a Wollaston prism is introduced. Asymmetric anamorphic distortion induced by the prism is characterized and corrected in real time using a graphics-processing unit. To demonstrate the capacity of single-exposure OBM to perform artifact-free imaging of blood flow, video-rate movies of microcirculation in ovo in the chorioallantoic membrane of the developing chick are presented. Imaging is performed with a high-resolution rigid Hopkins lens suitable for endoscopy.

  14. Video-rate imaging of microcirculation with single-exposure oblique back-illumination microscopy.

    PubMed

    Ford, Tim N; Mertz, Jerome

    2013-06-01

    Oblique back-illumination microscopy (OBM) is a new technique for simultaneous, independent measurements of phase gradients and absorption in thick scattering tissues based on widefield imaging. To date, OBM has been used with sequential camera exposures, which reduces temporal resolution, and can produce motion artifacts in dynamic samples. Here, a variation of OBM that allows single-exposure operation with wavelength multiplexing and image splitting with a Wollaston prism is introduced. Asymmetric anamorphic distortion induced by the prism is characterized and corrected in real time using a graphics-processing unit. To demonstrate the capacity of single-exposure OBM to perform artifact-free imaging of blood flow, video-rate movies of microcirculation in ovo in the chorioallantoic membrane of the developing chick are presented. Imaging is performed with a high-resolution rigid Hopkins lens suitable for endoscopy.

  15. [Effect of lumbar (perirenal) procaine blockade on microcirculation and exchange proteoglycans with experimental gonarthrosis].

    PubMed

    Tarasko, A D; Ibatullin, I A; Aref'eva, A K

    2015-01-01

    Experimental studies on guinea pigs of both sexes (n = 30). Experimental animals are awicea into equal groups oJ 10 animals: 1--the control group (intact animals), 2--the comparison group (modelling of gonarthrosis by crossing his own patellar ligament has been made, exposure 6 months), 3--the main group (animals with gonarthrosis treatment was carried out by performing lumbar procaine blockade (LPB) with an interval of 3-5 days three times). We establish that after a course of LPB in gonarthrosis marked increase in the density of the injected channel in the articular and periarticular structures, which reflects a growth in the microcirculation, and more intense accumulation in the basic substance of epiphyseal cartilage PAS (+) indicates the material to increase the level of proteoglycan in articular cartilage. PMID:26259255

  16. ggstThe role of tendon microcirculation in Achilles and patellar tendinopathy

    PubMed Central

    Knobloch, Karsten

    2008-01-01

    Tendinopathy is of distinct interest as it describes a painful tendon disease with local tenderness, swelling and pain associated with sonographic features such as hypoechogenic texture and diameter enlargement. Recent research elucidated microcirculatory changes in tendinopathy using laser Doppler flowmetry and spectrophotometry such as at the Achilles tendon, the patellar tendon as well as at the elbow and the wrist level. Tendon capillary blood flow is increased at the point of pain. Tendon oxygen saturation as well as tendon postcapillary venous filling pressures, determined non-invasively using combined Laser Doppler flowmetry and spectrophotometry, can quantify, in real-time, how tendon microcirculation changes over with pathology or in response to a given therapy. Tendon oxygen saturation can be increased by repetitive, intermittent short-term ice applications in Achilles tendons; this corresponds to 'ischemic preconditioning', a method used to train tissue to sustain ischemic damage. On the other hand, decreasing tendon oxygenation may reflect local acidosis and deteriorating tendon metabolism. Painful eccentric training, a common therapy for Achilles, patellar, supraspinatus and wrist tendinopathy decreases abnormal capillary tendon flow without compromising local tendon oxygenation. Combining an Achilles pneumatic wrap with eccentric training changes tendon microcirculation in a different way than does eccentric training alone; both approaches reduce pain in Achilles tendinopathy. The microcirculatory effects of measures such as extracorporeal shock wave therapy as well as topical nitroglycerine application are to be studied in tendinopathy as well as the critical question of dosage and maintenance. Interestingly it seems that injection therapy using color Doppler for targeting the area of neovascularisation yields to good clinical results with polidocanol sclerosing therapy, but also with a combination of epinephrine and lidocaine. PMID:18447938

  17. Coronary microcirculation changes in non-ischemic dilated cardiomyopathy identified by novel perfusion CT

    PubMed Central

    Miller, Wayne L.; Behrenbeck, Thomas R.; McCollough, Cynthia H.; Williamson, Eric E.; Leng, Shuai; Kline, Timothy L.

    2015-01-01

    Intramyocardial microvessels demonstrate functional changes in cardiomyopathies. However, clinical computed tomography (CT) does not have adequate spatial resolution to assess the microvessels. Our hypothesis is that these functional changes manifest as altered heterogeneity of the spatial distribution of arteriolar perfusion territories. Our goal was to determine whether the spatial analysis of perfusion CT could clinically detect changes in the function and structure of the intramyocardial microcirculation in a non-ischemic dilated cardiomyopathy (DCM). Two groups were studied: (1) a Control group (12 male plus 12 female) with no risk factors nor evidence of coronary artery disease, and (2) a DCM group (12 male plus 12 female)with left ventricular ejection fraction ≤40 %and no evidence of coronary artery disease. Using the CT scan, the LV free wall thickness and its radius of curvature were measured. The DCM group was sub divided into those with LV free wall thickness <11.5 mm and those with thickness≥11.5 mm. In themyocardial opacification phase of the CT scan sequence, myocardial perfusion (F) and intramyocardial blood volume (Bv) for multiple intramyocardial regions were computed. No significant differences between the groups were demonstrable in overall myocardial F or Bv. However, the myocardial regional data showed significantly increased spatial heterogeneity in the DCM group when compared to the Control group. The findings demonstrate that altered function of the subresolution intramyocardial microcirculation can be quantified with myocardial perfusion CT and that significant changes in these parameters occur in the DCM subjects with LV wall thickness greater than 11.5 mm. PMID:25712168

  18. Geomagnetic field modulates artificial static magnetic field effect on arterial baroreflex and on microcirculation

    NASA Astrophysics Data System (ADS)

    Gmitrov, Juraj

    2007-03-01

    Spreading evidence suggests that geomagnetic field (GMF) modulates artificial magnetic fields biological effect and associated with increased cardiovascular morbidity. To explore the underlying physiological mechanism we studied 350 mT static magnetic field (SMF) effect on arterial baroreflex-mediated skin microcirculatory response in conjunction with actual geomagnetic activity, reflected by K and K p indices. Fourteen experiments were performed in rabbits sedated by pentobarbital infusion (5 mg/kg/h). Mean femoral artery blood pressure, heart rate, and the ear lobe skin microcirculatory blood flow, measured by microphotoelectric plethysmogram (MPPG), were simultaneously recorded before and after 40 min of NdFeB magnets local exposure to sinocarotid baroreceptors. Arterial baroreflex sensitivity (BRS) was estimated from heart rate/blood pressure response to intravenous bolus injections of nitroprusside and phenylephrine. We found a significant positive correlation between SMF-induced increase in BRS and increment in microvascular blood flow (ΔBRS with ΔMPPG, r=0.7, p<0.009) indicated the participation of the arterial baroreflex in the regulation of the microcirculation and its enhancement after SMF exposure. Geomagnetic disturbance, as opposed to SMF, decreased both microcirculation and BRS, and counteracted SMF-induced increment in microcirculatory blood flow ( K-index with ΔMPPG; r s=-0.55, p<0.041). GMF probably affected central baroreflex pathways, diminishing SMF direct stimulatory effect on sinocarotid baroreceptors and on baroreflex-mediated vasodilatatory response. The results herein may thus point to arterial baroreflex as a possible physiological mechanism for magnetic-field cardiovascular effect. It seems that geomagnetic disturbance modifies artificial magnetic fields biological effect and should be taken into consideration in the assessment of the final effect.

  19. Geomagnetic field modulates artificial static magnetic field effect on arterial baroreflex and on microcirculation.

    PubMed

    Gmitrov, Juraj

    2007-03-01

    Spreading evidence suggests that geomagnetic field (GMF) modulates artificial magnetic fields biological effect and associated with increased cardiovascular morbidity. To explore the underlying physiological mechanism we studied 350 mT static magnetic field (SMF) effect on arterial baroreflex-mediated skin microcirculatory response in conjunction with actual geomagnetic activity, reflected by K and K ( p ) indices. Fourteen experiments were performed in rabbits sedated by pentobarbital infusion (5 mg/kg/h). Mean femoral artery blood pressure, heart rate, and the ear lobe skin microcirculatory blood flow, measured by microphotoelectric plethysmogram (MPPG), were simultaneously recorded before and after 40 min of NdFeB magnets local exposure to sinocarotid baroreceptors. Arterial baroreflex sensitivity (BRS) was estimated from heart rate/blood pressure response to intravenous bolus injections of nitroprusside and phenylephrine. We found a significant positive correlation between SMF-induced increase in BRS and increment in microvascular blood flow (DeltaBRS with DeltaMPPG, r=0.7, p<0.009) indicated the participation of the arterial baroreflex in the regulation of the microcirculation and its enhancement after SMF exposure. Geomagnetic disturbance, as opposed to SMF, decreased both microcirculation and BRS, and counteracted SMF-induced increment in microcirculatory blood flow (K-index with DeltaMPPG; r (s)=-0.55, p<0.041). GMF probably affected central baroreflex pathways, diminishing SMF direct stimulatory effect on sinocarotid baroreceptors and on baroreflex-mediated vasodilatatory response. The results herein may thus point to arterial baroreflex as a possible physiological mechanism for magnetic-field cardiovascular effect. It seems that geomagnetic disturbance modifies artificial magnetic fields biological effect and should be taken into consideration in the assessment of the final effect. PMID:16983578

  20. Manipulation of magnetic nanoparticle retention and hemodynamic consequences in microcirculation: assessment by laser speckle imaging

    PubMed Central

    Ma, Yunn-Hwa; Chen, Si-Yi; Tu, Shu-Ju; Yang, Hung-Wei; Liu, Hao-Li

    2012-01-01

    Magnetic nanoparticles (MNPs) have been proposed for targeted or embolization therapeutics. How MNP retention occurs in circulation may critically determine local hemodynamics, tissue distribution of MNPs, and the therapeutic effects. We attempted to establish a microcirculation model to study the magnetic capture of MNPs in small vessels and to determine the factors affecting MNP retention. Two-dimensional hemodynamic changes in response to magnet-induced MNP retention in the microvessels of the cremaster muscle in vivo were observed in a real-time manner using a laser speckle imaging technique. Changes in tissue perfusion of the cremaster muscle appeared to be closely correlated with the location of the magnet placement underneath the muscle in response to intra-arterial administration of dextran-coated MNPs. Magnet-related retention was observed along the edge of the magnet, as corroborated by the results of histology analysis and microcomputed tomography. In these preparations, tissue iron content almost doubled, as revealed by inductively coupled plasma optical emission spectroscopy. In addition, MNP retention was associated with reduced downstream flow in a dose-dependent manner. Dissipation of MNPs (5 mg/kg) occurred shortly after removal of the magnet, which was associated with significant recovery of tissue flow. However, MNP dissipation did not easily occur after administration of a higher MNP dose (10 mg/kg) or prolonged exposure to the magnetic field. An ultrasound after removal of the magnet may induce the partial dispersion of MNPs and thus partially improve hemodynamics. In conclusion, our results revealed the important correlation of local MNP retention and hemodynamic changes in microcirculation, which can be crucial in the application of MNPs for effective targeted therapeutics. PMID:22745544

  1. Effects of low-power laser exposure on masseter muscle pain and microcirculation.

    PubMed

    Tullberg, Marie; Alstergren, Per J; Ernberg, Malin M

    2003-09-01

    One possible cause of the reported positive treatment effect by low-power laser exposure in muscle pain conditions could be that it increases the local microcirculation. The aim of this study was therefore to investigate the immediate effects on masseter muscle blood flow by low-power laser exposure in patients with chronic orofacial pain of muscular origin in comparison to healthy individuals. Twelve patients with myofascial pain of orofacial muscles and 12 age and gender matched healthy individuals participated in the study. Before laser exposure the subjects were examined clinically and the patients scored their current pain intensity from the most tender masseter muscle. Intramuscular laser-Doppler flowmetry was performed unilaterally in the most tender point (patients) or in a standardized point (healthy subjects) of the masseter muscle. The muscle was first exposed with a Gallium-Aluminum-Arsenide laser (active laser) or placebo laser for 2 min in a randomized and double-blind manner. After another 8 min the muscle was treated with the other laser for 2 min and the LDF recording continued for 8 min. Finally, the patients again assessed the pain intensity. Data were analyzed blindly by one of the authors not participating in data collection. The pain intensity was not affected by laser exposure. The blood flow did not change significantly in the patients, but increased after active laser exposure and decreased after placebo exposure in the healthy individuals. The difference between active laser and placebo was significant. In conclusion, the results of this study do not support an effect of low-power laser exposure on masseter muscle microcirculation in patients with chronic orofacial pain of muscular origin.

  2. Degradation of the endothelial glycocalyx is associated with chylomicron leakage in mouse cremaster muscle microcirculation.

    PubMed

    Constantinescu, A; Spaan, J A E; Arkenbout, E K; Vink, H; Vanteeffelen, J W G E

    2011-05-01

    A thick endothelial glycocalyx contributes to the barrier function of vascular endothelium in macro- and microcirculation. We hypothesised in the current study that diet-induced hyperlipidaemia perturbs the glycocalyx, resulting in decreased dimensions of this layer and increased transendothelial lipoprotein leakage in capillaries. Glycocalyx thickness was measured in mouse cremaster muscle capillaries by intravital microscopy from the distance between flowing red blood cells and the endothelial surface. In control C57BL/6 mice on standard chow, glycocalyx thickness measured 0.58 ± 0.01 (mean ± SEM) μm, and no lipoproteins were observed in the tissue. After three months administration of an either mild or severe high-fat / high-cholesterol diet (HFC) to C57BL/6 and ApoE3-Leiden mice, circulating large lipoproteins appeared into the subendothelial space in an increasing proportion of cremaster capillaries, and these capillaries displayed reduced glycocalyx dimensions of 0.40 ± 0.02 and 0.30 ± 0.01 μm (C57BL/6 mice), and 0.37 ± 0.01 and 0.28 ± 0.01 μm (ApoE3-Leiden mice), after the mild and severe HFC diet, respectively. The chylomicron nature of the accumulated lipoproteins was confirmed by observations of subendothelial deposition of DiI-labeled chylomicrons in capillaries after inducing acute glycocalyx degradation by heparitinase in normolipidaemic C57BL/6 mice. It is concluded that while under control conditions the endothelial glycocalyx contributes to the vascular barrier against transvascular lipoprotein leakage in the microcirculation, diet-induced hyperlipidaemia reduces the thickness of the glycocalyx, thereby facilitating leakage of chylomicrons across the capillary wall.

  3. Remote ischemic conditioning improves coronary microcirculation in healthy subjects and patients with heart failure

    PubMed Central

    Kono, Yasushi; Fukuda, Shota; Hanatani, Akihisa; Nakanishi, Koki; Otsuka, Kenichiro; Taguchi, Haruyuki; Shimada, Kenei

    2014-01-01

    Background Remote ischemic conditioning (RIC) is a treatment modality that suppresses inflammation and improves endothelial function, which are factors involved in the pathogenesis of heart failure (HF) with reduced left ventricular ejection fraction. Coronary flow reserve (CFR) is a physiological index of coronary microcirculation and is noninvasively measured by transthoracic Doppler echocardiography (TTDE). This study aimed to investigate the effects of RIC on CFR in healthy subjects and patients with HF, through the assessment by TTDE. Methods Ten patients with HF with left ventricular ejection fraction of less than 40%, and ten healthy volunteers were enrolled in this study. RIC treatment was performed twice a day for 1 week. Our custom-made RIC device was programmed to automatically conduct 4 cycles of 5 minutes inflation and 5 minutes deflation of a blood pressure cuff to create intermittent arm ischemia. CFR measurements and laboratory tests were examined before, and after 1 week of RIC treatment. Results One week of RIC treatment was well tolerated in both groups. RIC treatment increased CFR from 4.0±0.9 to 4.6±1.3 (mean ± standard deviation) in healthy subjects (P=0.02), and from 1.9±0.4 to 2.3±0.7 in patients with HF (P=0.03), respectively. Systolic blood pressure in healthy subjects, and heart rate in HF patients decreased after RIC treatment (both P<0.01). Conclusion This study demonstrated that a 1 week course of RIC treatment improved coronary microcirculation in healthy subjects and patients with HF associated with reduced left ventricular ejection fraction. PMID:25210440

  4. Improved instrumentation for blood flow velocity measurements in the microcirculation of small animals

    SciTech Connect

    Mesquita, Jayme Alves Jr. de; Bouskela, Eliete; Wajnberg, Eliane; Lopes de Melo, Pedro

    2007-02-15

    Microcirculation is the generic name of vessels with internal diameter less than 100 {mu}m of the circulatory system, whose main functions are tissue nutrition and oxygen supply. In microcirculatory studies, it is important to know the amount of oxyhemoglobin present in the blood and how fast it is moving. The present work describes improvements introduced in a classical hardware-based instrument that has usually been used to monitor blood flow velocity in the microcirculation of small animals. It consists of a virtual instrument that can be easily incorporated into existing hardware-based systems, contributing to reduce operator related biases and allowing digital processing and storage. The design and calibration of the modified instrument are described as well as in vitro and in vivo results obtained with electrical models and small animals, respectively. Results obtained in in vivo studies showed that this new system is able to detect a small reduction in blood flow velocity comparing arteries and arterioles (p<0.002) and a further reduction in capillaries (p<0.0001). A significant increase in velocity comparing capillaries and venules (p<0.001) and venules and veins (p<0.001) was also observed. These results are in close agreement with biophysical principles. Moreover, the improvements introduced in the device allowed us to clearly observe changes in blood flow introduced by a pharmacological intervention, suggesting that the system has enough temporal resolution to track these microcirculatory events. These results were also in close conformity to physiology, confirming the high scientific potential of the modified system and indicating that this instrument can also be useful for pharmacological evaluations.

  5. Extended precedence preservative crossover for job shop scheduling problems

    NASA Astrophysics Data System (ADS)

    Ong, Chung Sin; Moin, Noor Hasnah; Omar, Mohd

    2013-04-01

    Job shop scheduling problems (JSSP) is one of difficult combinatorial scheduling problems. A wide range of genetic algorithms based on the two parents crossover have been applied to solve the problem but multi parents (more than two parents) crossover in solving the JSSP is still lacking. This paper proposes the extended precedence preservative crossover (EPPX) which uses multi parents for recombination in the genetic algorithms. EPPX is a variation of the precedence preservative crossover (PPX) which is one of the crossovers that perform well to find the solutions for the JSSP. EPPX is based on a vector to determine the gene selected in recombination for the next generation. Legalization of children (offspring) can be eliminated due to the JSSP representation encoded by using permutation with repetition that guarantees the feasibility of chromosomes. The simulations are performed on a set of benchmarks from the literatures and the results are compared to ensure the sustainability of multi parents recombination in solving the JSSP.

  6. Planning school based sexuality programs utilizing the PRECEDE model.

    PubMed

    Rubinson, L; Baillie, L

    1981-04-01

    Both substantive and methodological issues in teenage sexuality were explored. Specific study purposes were the following: 1) to explore the effectiveness of a community needs assessment to reduce traditional negative parental input and facilitating the use of the schools as public health resources; 2) to identify substantive targets of intervention for curriculum development which would be accepted and supported by both parents and teenagers; and 3) to develop a methodology of assessment where the PRECEDE model would be tested for its utility in identifying educational targets in a complex and multidimensional area such as human sexuality and to quantify the model's categories to identify major differences in perceptions between parents and teenagers, and to explore underlying constructs in teenage sexuality. The PRECEDE model provides an assessment of social and epidemiological factors as well as an investigation of the behavioral causes of the outcomes as identified by the community. 50% of the population of 600 families living in a small midwestern community were surveyed: 204 parents and 210 teenagers responded to the survey. The following were among the major findings: 1) a community needs assessment using the PRECEDE model was effective in reducing negative political input and in facilitating the use of the schools as public health resources; 2) there were major needs, especially in the identification of important social problems; and 3) 24% of the teenagers reported they were sexually active while only 10% of the parents perceived their children as being sexually active.

  7. Hemodynamic management of septic shock: is it time for "individualized goal-directed hemodynamic therapy" and for specifically targeting the microcirculation?

    PubMed

    Saugel, Bernd; Trepte, Constantin J; Heckel, Kai; Wagner, Julia Y; Reuter, Daniel A

    2015-06-01

    Septic shock is a life-threatening condition in both critically ill medical patients and surgical patients during the perioperative phase. In septic shock, specific alterations in global cardiovascular dynamics (i.e., the macrocirculation) and in the microcirculatory blood flow (i.e., the microcirculation) have been described. However, the presence and degree of microcirculatory failure are in part independent from systemic macrohemodynamic variables. Macrocirculatory and microcirculatory failure can independently induce organ dysfunction. We review current diagnostic and therapeutic approaches for the assessment and optimization of both the macrocirculation and the microcirculation in septic shock. There are various technologies for the determination of macrocirculatory hemodynamic variables. We discuss the data on early goal-directed therapy for the resuscitation of the macrocirculation. In addition, we describe the concept of "individualized goal-directed hemodynamic therapy." Technologies to assess the local microcirculation are also available. However, adequate resuscitation goals for the optimization of the microcirculation still need to be defined. At present, we are not ready to specifically monitor and target the microcirculation in clinical routine outside studies. In the future, concepts for an integrative approach for individualized hemodynamic management of the macrocirculation and in parallel the microcirculation might constitute a huge opportunity to define additional resuscitation end points in septic shock.

  8. Inhibition of glycogen synthase kinase (GSK)-3-β improves liver microcirculation and hepatocellular function after hemorrhagic shock.

    PubMed

    Jellestad, Lena; Fink, Tobias; Pradarutti, Sascha; Kubulus, Darius; Wolf, Beate; Bauer, Inge; Thiemermann, Chris; Rensing, Hauke

    2014-02-01

    Ischemia and reperfusion may cause liver injury and are characterized by hepatic microperfusion failure and a decreased hepatocellular function. Inhibition of glycogen synthase kinase (GSK)-3β, a serine-threonine kinase that has recently emerged as a key regulator in the modulation of the inflammatory response after stress events, may be protective in conditions like sepsis, inflammation and shock. Therefore, aim of the study was to assess the role of GSK-3β in liver microcirculation and hepatocellular function after hemorrhagic shock and resuscitation (H/R). Anesthetized male Sprague-Dawley rats underwent pretreatment with Ringer´s solution, vehicle (DMSO) or TDZD-8 (1 mg/kg), a selective GSK-3β inhibitor, 30 min before induction of hemorrhagic shock (mean arterial pressure 35±5 mmHg for 90 min) and were resuscitated with shed blood and Ringer´s solution (2h). 5h after resuscitation hepatic microcirculation was assessed by intravital microscopy. Propidium iodide (PI) positive cells, liver enzymes and alpha-GST were measured as indicators of hepatic injury. Liver function was estimated by assessment of indocyanine green plasma disappearance rate. H/R led to a significant decrease in sinusoidal diameters and impairment of liver function compared to sham operation. Furthermore, the number of PI positive cells in the liver as well as serum activities of liver enzymes and alpha-GST increased significantly after H/R. Pretreatment with TDZD-8 prevented the changes in liver microcirculation, hepatocellular injury and liver function after H/R. A significant rise in the plasma level of IL-10 was observed. Thus, inhibition of GSK-3β before hemorrhagic shock modulates the inflammatory response and improves hepatic microcirculation and hepatocellular function.

  9. Ultra-high-sensitive optical micro-angiography provides depth resolved visualization of microcirculations within human skin under psoriatic conditions

    NASA Astrophysics Data System (ADS)

    Qin, Jia; An, Lin; Wang, Ruikang

    2011-03-01

    Adequate functioning of the peripheral micro vascular in human skin is necessary to maintain optimal tissue perfusion and preserve normal hemodynamic function. There is a growing body of evidence suggests that vascular abnormalities may directly related to several dermatologic diseases, such as psoriasis, port-wine stain, skin cancer, etc. New in vivo imaging modalities to aid volumetric microvascular blood perfusion imaging are there for highly desirable. To address this need, we demonstrate the capability of ultra-high sensitive optical micro angiography to allow blood flow visualization and quantification of vascular densities of lesional psoriasis area in human subject in vivo. The microcirculation networks of lesion and non-lesion skin were obtained after post processing the data sets captured by the system. With our image resolution (~20 μm), we could compare these two types of microcirculation networks both qualitatively and quantitatively. The B-scan (lateral or x direction) cross section images, en-face (x-y plane) images and the volumetric in vivo perfusion map of lesion and non-lesion skin areas were obtained using UHS-OMAG. Characteristic perfusion map features were identified between lesional and non-lesional skin area. A statistically significant difference between vascular densities of lesion and non-lesion skin area was also found using a histogram based analysis. UHS-OMAG has the potential to differentiate the normal skin microcirculation from abnormal human skin microcirculation non-invasively with high speed and sensitivity. The presented data demonstrates the great potential of UHS-OMAG for detecting and diagnosing skin disease such as psoriasis in human subjects.

  10. Persistent effects after trigeminal nerve proprioceptive stimulation by mandibular extension on rat blood pressure, heart rate and pial microcirculation.

    PubMed

    Lapi, D; Colantuoni, A; Del Seppia, C; Ghione, S; Tonlorenzi, D; Brunelli, M; Scuri, R

    2013-03-01

    The trigemino-cardiac reflex is a brainstem reflex known to lead to a decrement in heart rate and blood pressure, whereas few data have been collected about its effects on the cerebral hemodynamic. In this study we assess the in vivo effects of trigeminal nerve peripheral stimulation by mandibular extension on pial microcirculation and systemic arterial blood pressure in rats. Experiments were performed in male Wistar rats subjected to mandibular extension obtained inserting an ad hoc developed retractor between the dental arches. Mean arterial blood pressure and heart rate were recorded and the pial arterioles were visualized by fluorescence microscopy to measure the vessel diameters before (15 minutes) during (5-15 minutes) and after (80 minutes) mandibular extension. While in control rats (sham-operated rats) and in rats subjected to the dissection of the trigeminal peripheral branches mean arterial blood pressure, heart rate and pial microcirculation did not change during the whole observation period (110 minutes), in rats submitted to mandibular extension, mean arterial blood pressure, heart rate and arteriolar diameter significantly decreased during stimulation. Afterward mean arterial blood pressure remained reduced as well as heart rate, while arteriolar diameter significantly increased evidencing a vasodilatation persisting for the whole remaining observation time. Therefore, trigeminal nerve proprioceptive stimulation appears to trigger specific mechanisms regulating systemic arterial blood pressure and pial microcirculation.

  11. The Effects of Vaccinium myrtillus Extract on Hamster Pial Microcirculation during Hypoperfusion-Reperfusion Injury

    PubMed Central

    Mastantuono, Teresa; Starita, Noemy; Sapio, Daniela; D’Avanzo, Sabato Andrea; Di Maro, Martina; Muscariello, Espedita; Paterni, Marco; Colantuoni, Antonio; Lapi, Dominga

    2016-01-01

    Introduction The present study was aimed to assess the in vivo hamster pial microvessel alterations due to 30 min transient bilateral common carotid artery occlusion (BCCAO) and reperfusion (60 min); moreover, the neuroprotective effects of Vaccinium myrtillus extract, containing 34.7% of anthocyanins, were investigated. Materials and Methods Two groups of male hamsters were used: the first fed with control diet and the other with Vaccinium myrtillus supplemented diet. Hamster pial microcirculation was visualized by fluorescence microscopy through an open cranial window. Pial arterioles were classified according to Strahler’s method. Results In age-matched control diet-fed hamsters, BCCAO caused a decrease in diameter of all arterioles. At the end of reperfusion, the reduction of diameter in order 3 arterioles was by 8.4 ± 3.1%, 10.8 ± 2.3% and 12.1 ± 1.1% of baseline in the 2, 4 and 6 month control diet-fed hamsters, respectively. Microvascular permeability and leukocyte adhesion were markedly enhanced, while perfused capillary length (PCL) decreased. The response to acetylcholine and papaverine topical application was impaired; 2’-7’-dichlorofluoresceine-diacetate assay demonstrated a significant ROS production. At the end of BCCAO, in age-matched Vaccinium myrtillussupplemented diet-fed hamsters, the arteriolar diameter did not significantly change compared to baseline. After 60 min reperfusion, order 3 arterioles dilated by 9.3 ± 2.4%, 10.6 ± 3.1% and 11.8 ± 2.7% of baseline in the 2, 4 and 6 month Vaccinium myrtillus supplemented diet-fed hamsters, respectively. Microvascular leakage and leukocyte adhesion were significantly reduced in all groups according to the time-dependent treatment, when compared with the age-matched control diet-fed hamsters. Similarly, the reduction in PCL was progressively prevented. Finally, the response to acetylcholine and papaverine topical application was preserved and there was no significant increase in ROS

  12. APOE polymorphisms influence longitudinal lipid trends preceding intracerebral hemorrhage

    PubMed Central

    Phuah, Chia-Ling; Raffeld, Miriam R.; Ayres, Alison M.; Gurol, M. Edip; Viswanathan, Anand; Greenberg, Steven M.; Biffi, Alessandro; Rosand, Jonathan

    2016-01-01

    Objective: We sought to determine whether APOE genotype influences a previously observed decline in serum total cholesterol (TC) and low-density lipoprotein (LDL) levels preceding primary intracerebral hemorrhage (ICH), as a potential demonstration of nonamyloid mechanisms of APOE in ICH risk. Methods: We performed a single-center retrospective longitudinal analysis using patients with known APOE genotype drawn from an ongoing cohort study of ICH. Serum lipid measurements for TC, triglycerides (TGs), LDL, and high-density lipoprotein (HDL) collected within 2 years before and after index ICH were extracted from electronic medical records. Piecewise linear mixed-effects models were used to compare APOE allele–specific effects on temporal serum lipid trends in ICH. Demographics, medical history, medications, and health maintenance data were included as fixed effects. Inter- and intraindividual variations in lipid levels were modeled as random effects. Results: A total of 124 ICH cases were analyzed. APOE ε4 carriers had greater rates of decline in serum TC and LDL within 6 months preceding ICH (TC: −7.30 mg/dL/mo, p = 0.0035; LDL: −8.44 mg/dL/mo, p = 0.0001). Conversely, serum TC and LDL levels in APOE ε2 carriers were unchanged within the same time period. APOE genotype had no associations with serum HDL or TG trends. Conclusions: APOE allele status predicts serum TC and LDL changes preceding acute ICH. Our results have implications for ongoing efforts in dissecting the role of dyslipidemia in cerebrovascular disease risk. APOE genotype–specific influence on lipid trends provides a clue for one mechanism by which APOE may influence risk of ICH. Further characterization of the metabolic roles of APOE is needed to improve the understanding of APOE biology in cerebrovascular disease risk. PMID:27433544

  13. Low voltage electrical activity preceding right atrial depolarisation in man.

    PubMed Central

    Mackintosh, A F; English, M J; Vincent, R; Woollons, D J; Chamberlain, D A

    1979-01-01

    Electrical recordings were made in the high right atrium in 28 patients undergoing cardiac catheterisation and in 3 healthy volunteers. After filtering and amplification by 3 to 10 million times, the signals were passed through a signal averaging process in a digital computer. Of the 28 subjects who had technically satisfactory recordings, 23 showed low voltage electrical activity preceding the conventionally-recorded atrial depolarisation. The low voltage activity started 50 to 200 ms before the atrial deflection and was variable in shape. These early signals may be the result of activity in the region of the sinus node. PMID:486271

  14. Learning-induced modulations of the stimulus-preceding negativity.

    PubMed

    Morís, Joaquín; Luque, David; Rodríguez-Fornells, Antoni

    2013-09-01

    The neural basis of feedback expectation, which is crucial in learning theory, has only been minimally studied. Stimulus-preceding negativity (SPN), an ERP component that appears prior to the presentation of feedback, has been proposed as being related to feedback expectation. The present study showed, for the first time, amplitude modulations of the SPN component during learning acquisition in a trial-by-trial associative learning task. The results indicate that SPN could be a plausible electrophysiological index of the cognitive processes engaged while expecting the appearance of relevant feedback during reinforcement learning.

  15. Vitiligo disease triggers: psychological stressors preceding the onset of disease.

    PubMed

    Silverberg, Jonathan I; Silverberg, Nanette B

    2015-05-01

    Vitiligo is the loss of skin pigmentation caused by autoimmune destruction of melanocytes. Little is known about the impact of psychological stressors preceding vitiligo onset on symptoms associated with vitiligo and the extent of disease. We performed a questionnaire-based study of 1541 adults with vitiligo to evaluate the impact of psychological stressors in this patient population. Psychological stressors should be considered as potential disease triggers in vitiligo patients, and screening of vitiligo patients for psychological stressors and associated symptoms should be included in routine assessment.

  16. Precedence based speech segregation in bilateral cochlear implant users

    PubMed Central

    Hossain, Shaikat; Montazeri, Vahid; Assmann, Peter F.; Litovsky, Ruth Y.

    2015-01-01

    The precedence effect (PE) enables the perceptual dominance by a source (lead) over an echo (lag) in reverberant environments. In addition to facilitating sound localization, the PE can play an important role in spatial unmasking of speech. Listeners attending to binaural vocoder simulations with identical channel center frequencies and phase demonstrated PE-based benefits in a closed-set speech segregation task. When presented with the same stimuli, bilateral cochlear implant users did not derive such benefits. These findings suggest that envelope extraction in itself may not lead to a breakdown of the PE benefits, and that other factors may play a role. PMID:26723365

  17. Theoretical effects of UTB urea transporters in the renal medullary microcirculation.

    PubMed

    Zhang, Wensheng; Edwards, Aurélie

    2003-10-01

    A mathematical model of transport in the renal medullary microcirculation was used to investigate the role of the UTB urea transporter expressed in descending vasa recta (DVR) endothelia and red blood cell (RBC) membranes. Our simulations suggest that UTB raises RBC and plasma and interstitial urea concentrations by facilitating radial diffusion of the solute and therefore serves to increase the contribution of urea to the corticomedullary osmolality gradient, assuming no secondary effects on tubular transport. However, by lowering transmural urea concentration gradients, UTB reduces water efflux from DVR through aquaporin-1 (AQP1) water channels, thereby decreasing plasma sodium concentration. The net result of these competing effects on the osmolality gradient depends on the fraction of filtered urea that is reabsorbed by vasa recta. We also found that the contribution of UTB to water transport across DVR and RBCs is negligible, even in the absence of AQP1. Our model predicts that UTB plays a significant role, however, in reducing the shrinking and swelling of RBCs as blood flows along the medulla. PMID:12824077

  18. Obesity alters the peripheral circadian clock in the aorta and microcirculation

    PubMed Central

    Nernpermpisooth, Nitirut; Qiu, Shuiqing; Mintz, James D; Suvitayavat, Wisuda; Thirawarapan, Suwan; Rudic, Daniel R.; Fulton, David J.; Stepp, David W.

    2015-01-01

    Perturbation of daily rhythm increases cardiovascular risk. The aim of this study was to determine whether obesity alters circadian gene expression and microvascular function in lean mice and obese (db/db) mice. Mice were subjected to normal light-dark cycle or constant darkness (DD) to alter circadian rhythm. Metabolic parameters and microvascular vasoreactivity were evaluated. Array studies were conducted in the AM and PM cycles to assess the rhythmicity of the entire genomics. Rhythmic expression of specific clock genes (Bmal1, Clock, Npas2, Per1, Per2, and Cry1), clock output genes (dbp), and vascular relaxation-related genes (eNOS, GTPCH1) were assessed. Obesity was associated with metabolic dysfunction and impaired endothelial dilation in the microvasculature. Circadian rhythm of gene expression was suppressed 80% in both macro- and microcirculations of obese mice. Circadian disruption with DD increased fasting serum glucose and HbA1C in obese but not lean mice. Endothelium-dependent dilation was attenuated in obese mice and in lean mice subjected to DD. Rhythmic expression of per1 and dbp was depressed in obesity. Expression of eNOS expression was suppressed and GTPCH1 lost rhythmic expression both in obesity and by constant darkness. These results suggest that obesity reduces circadian gene expression in concert with impaired endothelial function. The causal relationship remains to be determined. PMID:25660131

  19. Leukotrienes as mediators in ischemia-reperfusion injury in a microcirculation model in the hamster.

    PubMed Central

    Lehr, H A; Guhlmann, A; Nolte, D; Keppler, D; Messmer, K

    1991-01-01

    Leukotriene (LT)B4 promotes leukocyte chemotaxis and adhesion to the endothelium of postcapillary venules. The cysteinyl leukotrienes, LTC4, LTD4, and LTE4, elicit macromolecular leakage from this vessel segment. Both leukocyte adhesion to the endothelium and macromolecular leakage from postcapillary venules hallmark the microcirculatory failure after ischemia-reperfusion, suggesting a role of leukotrienes as mediators of ischemia-reperfusion injury. Using the dorsal skinfold chamber model for intravital fluorescence microscopy of the microcirculation in striated muscle in awake hamsters and sequential RP-HPLC and RIA for leukotrienes, we demonstrate in this study that (a) the leukotrienes (LT)B4 and LTD4 elicit leukocyte/endothelium interaction and macromolecular leakage from postcapillary venules, respectively, that (b) leukotrienes accumulate in the tissue after ischemia and reperfusion, and that (c) selective inhibition of leukotriene biosynthesis (by MK-886) prevents both postischemic leukotriene accumulation and the microcirculatory changes after ischemia-reperfusion, while blocking of LTD4/E4 receptors (by MK-571) inhibits postischemic macromolecular leakage. These results demonstrate a key role of leukotrienes in ischemia-reperfusion injury in striated muscle in vivo. Images PMID:1645749

  20. Accessing the biocompatibility of layered double hydroxide by intramuscular implantation: histological and microcirculation evaluation

    PubMed Central

    Cunha, Vanessa Roberta Rodrigues; de Souza, Rodrigo Barbosa; da Fonseca Martins, Ana Maria Cristina Rebello Pinto; Koh, Ivan Hong Jun; Constantino, Vera Regina Leopoldo

    2016-01-01

    Biocompatibility of layered double hydroxides (LDHs), also known as hydrotalcite-like materials or double metal hydroxides, was investigated by in vivo assays via intramuscular tablets implantation in rat abdominal wall. The tablets were composed by chloride ions intercalated into LDH of magnesium/aluminum (Mg2Al-Cl) and zinc/aluminum (Zn2Al-Cl). The antigenicity and tissue integration capacity of LDHs were assessed histologically after 7 and 28 days post-implantation. No fibrous capsule nearby the LDH was noticed for both materials as well any sign of inflammatory reactions. Sidestream Dark Field imaging, used to monitor in real time the microcirculation in tissues, revealed overall integrity of the microcirculatory network neighboring the tablets, with no blood flow obstruction, bleeding and/or increasing of leukocyte endothelial adhesion. After 28 days Mg2Al-Cl promoted multiple collagen invaginations (mostly collagen type-I) among its fragments while Zn2Al-Cl induced predominantly collagen type–III. This work supports previous results in the literature about LDHs compatibility with living matter, endorsing them as functional materials for biomedical applications. PMID:27480483

  1. Impact of Stroma on the Growth, Microcirculation, and Metabolism of Experimental Prostate Tumors

    PubMed Central

    Zechmann, Christian M; Woenne, Eva C; Brix, Gunnar; Radzwill, Nicole; Ilg, Martin; Bachert, Peter; Peschke, Peter; Kirsch, Stefan; Kauczor, Hans-Ulrich; Delorme, Stefan; Semmler, Wolfhard; Kiessling, Fabian

    2007-01-01

    Abstract In prostate cancers (PCa), the formation of malignant stroma may substantially influence tumor phenotype and aggressiveness. Thus, the impact of the orthotopic and subcutaneous implantations of hormone-sensitive (H), hormone-insensitive (HI), and anaplastic (AT1) Dunning PCa in rats on growth, microcirculation, and metabolism was investigated. For this purpose, dynamic contrast-enhanced magnetic resonance imaging and 1H magnetic resonance spectroscopy ([1H]MRS) were applied in combination with histology. Consistent observations revealed that orthotopic H tumors grew significantly slower compared to subcutaneous ones, whereas the growth of HI and AT1 tumors was comparable at both locations. Histologic analysis indicated that glandular differentiation and a close interaction of tumor cells and smooth muscle cells (SMC) were associated with slow tumor growth. Furthermore, there was a significantly lower SMC density in subcutaneous H tumors than in orthotopic H tumors. Perfusion was observed to be significantly lower in orthotopic H tumors than in subcutaneous H tumors. Regional blood volume and permeability-surface area product showed no significant differences between tumor models and their implantation sites. Differences in growth between subcutaneous and orthotopic H tumors can be attributed to tumor-stroma interaction and perfusion. Here, SMC, may stabilize glandular structures and contribute to the maintenance of differentiated phenotype. PMID:17325744

  2. Accessing the biocompatibility of layered double hydroxide by intramuscular implantation: histological and microcirculation evaluation.

    PubMed

    Cunha, Vanessa Roberta Rodrigues; de Souza, Rodrigo Barbosa; da Fonseca Martins, Ana Maria Cristina Rebello Pinto; Koh, Ivan Hong Jun; Constantino, Vera Regina Leopoldo

    2016-01-01

    Biocompatibility of layered double hydroxides (LDHs), also known as hydrotalcite-like materials or double metal hydroxides, was investigated by in vivo assays via intramuscular tablets implantation in rat abdominal wall. The tablets were composed by chloride ions intercalated into LDH of magnesium/aluminum (Mg2Al-Cl) and zinc/aluminum (Zn2Al-Cl). The antigenicity and tissue integration capacity of LDHs were assessed histologically after 7 and 28 days post-implantation. No fibrous capsule nearby the LDH was noticed for both materials as well any sign of inflammatory reactions. Sidestream Dark Field imaging, used to monitor in real time the microcirculation in tissues, revealed overall integrity of the microcirculatory network neighboring the tablets, with no blood flow obstruction, bleeding and/or increasing of leukocyte endothelial adhesion. After 28 days Mg2Al-Cl promoted multiple collagen invaginations (mostly collagen type-I) among its fragments while Zn2Al-Cl induced predominantly collagen type-III. This work supports previous results in the literature about LDHs compatibility with living matter, endorsing them as functional materials for biomedical applications. PMID:27480483

  3. [Changes of the microcirculating blood volume in the reproductive axis during estrous cycle of the rats].

    PubMed

    Wu, S Y; Zhang, M; Zhu, B Q; Huang, H Y; Zhang, X G

    1990-10-01

    The microcirculating blood volume of the hypothalamic-pituitary-ovarian axis in the female rats was measured using radiobiomicrosphere method during the estrous cycle. The blood flow volume of the hypothalamus and the pituitary was not significantly different between each phase of the estrous cycle. The ovarian blood flow volume was the highest in metestrus and the lowest in estrus. The difference between them was significant (P less than 0.02). The uterine blood flow volume was the highest in metestrus and remained at higher level in diestrus and then changed to the lowest in estrus. The values in metestrus and diestrus were significantly higher than that in estrus (P less than 0.01, P less than 0.05, respectively). The blood flow volume of the oviduct in proestrus was significantly lower than that in estrus (P less than 0.05). The above results suggest that the cyclic changes of the blood volume of the ovary, uterus and oviduct are closely related to their functional state and the hormonal changes.

  4. Properties of the microcirculation in capillary bundles of rat spinotrapezius muscle fascia

    NASA Astrophysics Data System (ADS)

    Jacobitz, Frank; Engebrecht, Cheryn; Metzger, Ian; Porterfield, Colin

    2006-11-01

    Properties of the microcirculation in capillary bundles of rat spinotrapezius muscle fascia are investigated using microscope observations, empirical modeling, and numerical simulations. Capillary bundles consist of a network of feeding arterioles, draining venules, and capillary vessels. A dozen samples of muscle fascia tissue were prepared for microscope observation. The chosen method of preparation allows for the long-term preservation of the tissue samples for future studies. Capillary bundles are photographed under a microscope with 40x magnification. From the images, the microvasculature of the tissue samples is reconstructed. It was found, for example, that the distribution of vessel length in a capillary bundle follows a log-normal law. In addition to a statistical analysis of the vessel data, the network topology is used for numerical simulations of the flow in the capillary bundles. The numerical approach uses a sparse-matrix solver and it considers vessel elasticity and blood rheology. The numerical simulations show, for example, a strong pressure drop across the capillary vessels of the bundle.

  5. Comprehensive Spatial Display of the Microcirculation in a Capillary Bundle from Rat Spinotrapezius Muscle Fascia Tissue

    NASA Astrophysics Data System (ADS)

    Yamamura, Niki; Jacobitz, Frank; Schmid-Schönbein, Geert

    2012-11-01

    Previous investigations of the microcirculation in skeletal muscle have utilized a statistical display of fundamental hemodynamic variables without regard of actual microvascular details. The focus of this project is the development of a software tool to perform a spatial analysis of hemodynamic results. The vessel network considered in this study is a capillary bundle in rat spinotrapezius muscle fascia with transverse arterioles supplying blood, capillary vessels, and collecting venules removing blood. The software tool represents information about blood vessel location and connectivity in two matrices. The first matrix holds spatial locations of vessel intersections or nodes. This matrix is used to create a second matrix containing the locations of all microvessels. The second matrix is then used to produce result matrices holding the values of flow properties at the locations at which they are observed in the vessel network. The resulting images provide a full display, for example, of the pressure drop in the network. The highest velocities are obtained in the transverse arterioles and adjacent capillaries, while other vessels in the network show lower velocities. An area of elevated hematocrit is observed in the periphery of the network.

  6. Computational fluid dynamics in the microcirculation and microfluidics: what role can the lattice Boltzmann method play?

    PubMed

    O'Connor, Joseph; Day, Philip; Mandal, Parthasarathi; Revell, Alistair

    2016-05-16

    Patient-specific simulations, efficient parametric analyses, and the study of complex processes that are otherwise experimentally intractable are facilitated through the use of Computational Fluid Dynamics (CFD) to study biological flows. This review discusses various CFD methodologies that have been applied across different biological scales, from cell to organ level. Through this discussion the lattice Boltzmann method (LBM) is highlighted as an emerging technique capable of efficiently simulating fluid problems across the midrange of scales; providing a practical analytical tool compared to methods more attuned to the extremities of scale. Furthermore, the merits of the LBM are highlighted through examples of previous applications and suggestions for future research are made. The review focusses on applications in the midrange bracket, such as cell-cell interactions, the microcirculation, and microfluidic devices; wherein the inherent mesoscale nature of the LBM renders it well suited to the incorporation of fluid-structure interaction effects, molecular/particle interactions and interfacial dynamics. The review demonstrates that the LBM has the potential to become a valuable tool across a range of emerging areas in bio-CFD, such as understanding and predicting disease, designing lab-on-a-chip devices, and elucidating complex biological processes.

  7. Assessment of microcirculation dynamics during cutaneous wound healing phases in vivo using optical microangiography

    NASA Astrophysics Data System (ADS)

    Yousefi, Siavash; Qin, Jia; Dziennis, Suzan; Wang, Ruikang K.

    2014-07-01

    Cutaneous wound healing consists of multiple overlapping phases starting with blood coagulation following incision of blood vessels. We utilized label-free optical coherence tomography and optical microangiography (OMAG) to noninvasively monitor healing process and dynamics of microcirculation system in a mouse ear pinna wound model. Mouse ear pinna is composed of two layers of skin separated by a layer of cartilage and because its total thickness is around 500 μm, it can be utilized as an ideal model for optical imaging techniques. These skin layers are identical to human skin structure except for sweat ducts and glands. Microcirculatory system responds to the wound injury by recruiting collateral vessels to supply blood flow to hypoxic region. During the inflammatory phase, lymphatic vessels play an important role in the immune response of the tissue and clearing waste from interstitial fluid. In the final phase of wound healing, tissue maturation, and remodeling, the wound area is fully closed while blood vessels mature to support the tissue cells. We show that using OMAG technology allows noninvasive and label-free monitoring and imaging each phase of wound healing that can be used to replace invasive tissue sample histology and immunochemistry technologies.

  8. Assessment of microcirculation dynamics during cutaneous wound healing phases in vivo using optical microangiography

    PubMed Central

    Yousefi, Siavash; Qin, Jia; Dziennis, Suzan; Wang, Ruikang K.

    2014-01-01

    Abstract. Cutaneous wound healing consists of multiple overlapping phases starting with blood coagulation following incision of blood vessels. We utilized label-free optical coherence tomography and optical microangiography (OMAG) to noninvasively monitor healing process and dynamics of microcirculation system in a mouse ear pinna wound model. Mouse ear pinna is composed of two layers of skin separated by a layer of cartilage and because its total thickness is around 500 μm, it can be utilized as an ideal model for optical imaging techniques. These skin layers are identical to human skin structure except for sweat ducts and glands. Microcirculatory system responds to the wound injury by recruiting collateral vessels to supply blood flow to hypoxic region. During the inflammatory phase, lymphatic vessels play an important role in the immune response of the tissue and clearing waste from interstitial fluid. In the final phase of wound healing, tissue maturation, and remodeling, the wound area is fully closed while blood vessels mature to support the tissue cells. We show that using OMAG technology allows noninvasive and label-free monitoring and imaging each phase of wound healing that can be used to replace invasive tissue sample histology and immunochemistry technologies. PMID:25036212

  9. Examination of the microcirculation damage in smokers versus nonsmokers with vasospastic angina pectoris.

    PubMed

    Ashikaga, Takashi; Nishizaki, Mitsuhiro; Fujii, Hiroyuki; Niki, Saori; Maeda, Shingo; Yamawake, Noriyoshi; Kishi, Yukio; Isobe, Mitsuaki

    2007-09-15

    Endothelial dysfunction is considered one of the mechanisms underlying vasospastic angina pectoris (VSA). It is also known that smokers have abnormalities in endothelial dysfunction. Although smoking is a major risk factor for coronary artery disease, microvascular abnormalities have not been well shown. We investigated clinical characteristics and coronary reactivity with adenosine triphosphate in smokers with VSA. Twenty-two consecutive patients whose coronary spasm was documented in the left anterior descending (LAD) coronary artery with acetylcholine were enrolled. Coronary blood flow responses were also evaluated by intracoronary Doppler flow velocity recordings in the LAD coronary artery. Average peak velocities (APVs) were measured at baseline and intracoronary administration of adenosine triphosphate (50 microg) in 11 smokers (age 60+/-9 years; 8 men) and 11 nonsmokers (age 61+/-10 years, 5 men). Coronary flow reserve (CFR) was calculated by the ratio of baseline to hyperemic APV. Multivessel spasm was demonstrated in 6 smokers and only 2 nonsmokers (p<0.05). APV at rest in smokers (13.4+/-3.0 cm/s) was similar to that in nonsmokers (13.5+/-2.9 cm/s). However, CFR in smokers (2.6+/-0.7) was significantly lower than in nonsmokers (3.4+/-0.8; p<0.05). In conclusion, multivessel spasm was demonstrated in smokers in clinical settings, and microcirculation damage is prominent in smokers with VSA.

  10. Effects of dextran 70 versus crystalloids in the microcirculation of porcine hemorrhagic pancreatitis

    SciTech Connect

    Lehtola, A.; Kivilaakso, E.; Puolakkainen, P.; Karonen, S.L.; Lempinen, M.; Schroeder, T.

    1986-06-01

    The cause of hemodynamic changes occurring during acute pancreatitis remains obscure. Using a pig model of acute hemorrhagic pancreatitis and the reference sample method with 113Tin and 46 Scandium labelled microspheres, blood flow to organs was determined before and five hours after the induction of pancreatitis. Blood pressure, pulse rate and cardiac output were measured hourly. There were two treatment groups. The first group received dextran 70 (5.7 milliliters per kilogram per hour) and saline solution (7.5 milliliters per kilogram per hour) in sufficient amounts to maintain cardiac output at the initial (prepancreatic) level. The second group received saline solution (26 milliliters per kilogram per hour) only and during the experiment the cardiac output was allowed to decrease to approximately one-half of the initial level. In the dextran 70 group, blood flow in various organs stayed at the initial level or was slightly increased. However, in the saline solution group there was a marked and significant decrease in the blood flow in all organs except the antral mucosa, gallbladder and adrenal glands. The changes in the pancreatic fraction of the cardiac output during the experiment were similar to those of other organs in respective treatment groups. In conclusion, adequate infusion of dextran maintains cardiac output and organ microcirculation at the initial level during the early phase of acute hemorrhagic pancreatitis. It is suggested that the hemodynamic changes which develop during acute pancreatitis are mainly secondary to the ensuing hypovolemia and not direct consequences of the pancreatic inflammatory process.

  11. Expectations from preceding prosody influence segmentation in online sentence processing.

    PubMed

    Brown, Meredith; Salverda, Anne Pier; Dilley, Laura C; Tanenhaus, Michael K

    2011-12-01

    Previous work examining prosodic cues in online spoken-word recognition has focused primarily on local cues to word identity. However, recent studies have suggested that utterance-level prosodic patterns can also influence the interpretation of subsequent sequences of lexically ambiguous syllables (Dilley, Mattys, & Vinke, Journal of Memory and Language, 63:274-294, 2010; Dilley & McAuley, Journal of Memory and Language, 59:294-311, 2008). To test the hypothesis that these distal prosody effects are based on expectations about the organization of upcoming material, we conducted a visual-world experiment. We examined fixations to competing alternatives such as pan and panda upon hearing the target word panda in utterances in which the acoustic properties of the preceding sentence material had been manipulated. The proportions of fixations to the monosyllabic competitor were higher beginning 200 ms after target word onset when the preceding prosody supported a prosodic constituent boundary following pan-, rather than following panda. These findings support the hypothesis that expectations based on perceived prosodic patterns in the distal context influence lexical segmentation and word recognition.

  12. Does lumbar facet arthrosis precede disc degeneration? A postmortem study.

    PubMed

    Eubanks, Jason David; Lee, Michael J; Cassinelli, Ezequiel; Ahn, Nicholas U

    2007-11-01

    It is believed lumbar degeneration begins in the disc, where desiccation and collapse lead to instability and compensatory facet arthrosis. We explored the contrary contention that facet degeneration precedes disc degeneration by examining 647 skeletal lumbar spines. Using facet osteophytosis as a measure of facet degeneration and vertebral rim osteophytosis as a measure of disc degeneration, we assumed bone degeneration in both locations equally reflected the progression of those in the soft tissues. We graded arthrosis Grade 0 to 4 on a continuum from no arthritis to ankylosis. The data were analyzed for different age groups to examine patterns of degeneration with age. Specimens younger than 30 years of age had a higher prevalence of facet osteophytosis compared with vertebral rim osteophotosis at L1-L2 and L2-L3. Specimens aged 30 to 39 years showed more facet osteophytosis than vertebral rim osteophytosis at L4-L5. Specimens older than 40 years, however, showed more vertebral rim osteophytosis compared with facet osteophytosis at all levels except L4-L5 and L5-S1. This skeletal study suggests facet osteophytosis appears early in the degenerative process, preceding vertebral rim osteophytosis of degenerating intervertebral discs. However, once facets begin deteriorating with age, vertebral rim osteophytosis overtakes continued facet osteophytosis. These data challenge the belief that facet osteophytosis follows vertebral rim osteophytosis; rather, it appears vertebral rim osteophytosis progresses more rapidly in later years, but facet osteophotosis occurs early, predominating in younger individuals.

  13. Hydroclimatic conditions preceding the March 2014 Oso landslide

    USGS Publications Warehouse

    Henn, Brian; Cao, Qian; Lettenmaier, Dennis P.; Magirl, Christopher S.; Mass, Clifford; Bower, J. Brent; St. Laurent, Michael; Mao, Yixin; Perica, Sanja

    2015-01-01

    The 22 March 2014 Oso landslide was one of the deadliest in U.S. history, resulting in 43 fatalities and the destruction of more than 40 structures. We examine synoptic conditions, precipitation records and soil moisture reconstructions in the days, months, and years preceding the landslide. Atmospheric reanalysis shows a period of enhanced moisture transport to the Pacific Northwest beginning on 11 February 2014. The 21- to 42-day periods prior to the landslide had anomalously high precipitation; we estimate that 300-400 mm of precipitation fell at Oso in the 21 days prior to the landslide. Relative only to historical periods ending on 22 March, the return periods of these precipitation accumulations are large (25-88 years). However, relative to the largest accumulations from any time of the year (annual maxima), return periods are more modest (2-6 years). In addition to the 21-42 days prior to the landslide, there is a secondary maximum in the precipitation return periods for the 4 years preceding the landslide. Reconstructed soil moisture was anomalously high prior to the landslide, with a return period that exceeded 40 years about a week before the event.

  14. Continental warming preceding the Palaeocene-Eocene thermal maximum.

    PubMed

    Secord, Ross; Gingerich, Philip D; Lohmann, Kyger C; Macleod, Kenneth G

    2010-10-21

    Marine and continental records show an abrupt negative shift in carbon isotope values at ∼55.8 Myr ago. This carbon isotope excursion (CIE) is consistent with the release of a massive amount of isotopically light carbon into the atmosphere and was associated with a dramatic rise in global temperatures termed the Palaeocene-Eocene thermal maximum (PETM). Greenhouse gases released during the CIE, probably including methane, have often been considered the main cause of PETM warming. However, some evidence from the marine record suggests that warming directly preceded the CIE, raising the possibility that the CIE and PETM may have been linked to earlier warming with different origins. Yet pre-CIE warming is still uncertain. Disentangling the sequence of events before and during the CIE and PETM is important for understanding the causes of, and Earth system responses to, abrupt climate change. Here we show that continental warming of about 5 °C preceded the CIE in the Bighorn Basin, Wyoming. Our evidence, based on oxygen isotopes in mammal teeth (which reflect temperature-sensitive fractionation processes) and other proxies, reveals a marked temperature increase directly below the CIE, and again in the CIE. Pre-CIE warming is also supported by a negative amplification of δ(13)C values in soil carbonates below the CIE. Our results suggest that at least two sources of warming-the earlier of which is unlikely to have been methane-contributed to the PETM.

  15. Genome duplication and the evolution of conspecific pollen precedence

    PubMed Central

    Baldwin, Sarah J.; Husband, Brian C.

    2011-01-01

    Conspecific pollen precedence can be a strong reproductive barrier between polyploid and diploid species, but the role of genome multiplication in the evolution of this barrier has not been investigated. Here, we examine the direct effect of genome duplication on the evolution of pollen siring success in tetraploid Chamerion angustifolium. To separate the effects of genome duplication from selection after duplication, we compared pollen siring success of synthesized tetraploids (neotetraploids) with that of naturally occurring tetraploids by applying 2x, 4x (neo or established) or 2x + 4x pollen to diploid and tetraploid flowers. Seed set increased in diploids and decreased in both types of tetraploids as the proportion of pollen from diploid plants increased. Based on offspring ploidy from mixed-ploidy pollinations, pollen of the maternal ploidy always sired the majority of offspring but was strongest in established tetraploids and weakest in neotetraploids. Pollen from established tetraploids had significantly higher siring rates than neotetraploids when deposited on diploid (4xest = 47.2%, 4xneo = 27.1%) and on tetraploid recipients (4xest = 91.9%, 4xneo = 56.0%). Siring success of established tetraploids exceeded that of neotetraploids despite having similar pollen production per anther and pollen diameter. Our results suggest that, while pollen precedence can arise in association with the duplication event, the strength of polyploid siring success evolves after the duplication event. PMID:21123263

  16. Genome duplication and the evolution of conspecific pollen precedence.

    PubMed

    Baldwin, Sarah J; Husband, Brian C

    2011-07-01

    Conspecific pollen precedence can be a strong reproductive barrier between polyploid and diploid species, but the role of genome multiplication in the evolution of this barrier has not been investigated. Here, we examine the direct effect of genome duplication on the evolution of pollen siring success in tetraploid Chamerion angustifolium. To separate the effects of genome duplication from selection after duplication, we compared pollen siring success of synthesized tetraploids (neotetraploids) with that of naturally occurring tetraploids by applying 2x, 4x (neo or established) or 2x + 4x pollen to diploid and tetraploid flowers. Seed set increased in diploids and decreased in both types of tetraploids as the proportion of pollen from diploid plants increased. Based on offspring ploidy from mixed-ploidy pollinations, pollen of the maternal ploidy always sired the majority of offspring but was strongest in established tetraploids and weakest in neotetraploids. Pollen from established tetraploids had significantly higher siring rates than neotetraploids when deposited on diploid (4x(est) = 47.2%, 4x(neo) = 27.1%) and on tetraploid recipients (4x(est) = 91.9%, 4x(neo) = 56.0%). Siring success of established tetraploids exceeded that of neotetraploids despite having similar pollen production per anther and pollen diameter. Our results suggest that, while pollen precedence can arise in association with the duplication event, the strength of polyploid siring success evolves after the duplication event. PMID:21123263

  17. Expectations from preceding prosody influence segmentation in online sentence processing

    PubMed Central

    Brown, Meredith; Salverda, Anne Pier; Dilley, Laura C.; Tanenhaus, Michael K.

    2013-01-01

    Previous work examining prosodic cues in online spoken-word recognition has focused primarily on local cues to word identity. However, recent studies have suggested that utterance-level prosodic patterns can also influence the interpretation of subsequent sequences of lexically ambiguous syllables (Dilley, Mattys, & Vinke, Journal of Memory and Language, 63:274–294, 2010; Dilley & McAuley, Journal of Memory and Language, 59:294–311, 2008). To test the hypothesis that these distal prosody effects are based on expectations about the organization of upcoming material, we conducted a visual-world experiment. We examined fixations to competing alternatives such as pan and panda upon hearing the target word panda in utterances in which the acoustic properties of the preceding sentence material had been manipulated. The proportions of fixations to the monosyllabic competitor were higher beginning 200 ms after target word onset when the preceding prosody supported a prosodic constituent boundary following pan-, rather than following panda. These findings support the hypothesis that expectations based on perceived prosodic patterns in the distal context influence lexical segmentation and word recognition. PMID:21968925

  18. Selective attention in the honeybee optic lobes precedes behavioral choices.

    PubMed

    Paulk, Angelique C; Stacey, Jacqueline A; Pearson, Thomas W J; Taylor, Gavin J; Moore, Richard J D; Srinivasan, Mandyam V; van Swinderen, Bruno

    2014-04-01

    Attention allows animals to respond selectively to competing stimuli, enabling some stimuli to evoke a behavioral response while others are ignored. How the brain does this remains mysterious, although it is increasingly evident that even animals with the smallest brains display this capacity. For example, insects respond selectively to salient visual stimuli, but it is unknown where such selectivity occurs in the insect brain, or whether neural correlates of attention might predict the visual choices made by an insect. Here, we investigate neural correlates of visual attention in behaving honeybees (Apis mellifera). Using a closed-loop paradigm that allows tethered, walking bees to actively control visual objects in a virtual reality arena, we show that behavioral fixation increases neuronal responses to flickering, frequency-tagged stimuli. Attention-like effects were reduced in the optic lobes during replay of the same visual sequences, when bees were not able to control the visual displays. When bees were presented with competing frequency-tagged visual stimuli, selectivity in the medulla (an optic ganglion) preceded behavioral selection of a stimulus, suggesting that modulation of early visual processing centers precedes eventual behavioral choices made by these insects.

  19. Physiological and psychophysical modeling of the precedence effect.

    PubMed

    Xia, Jing; Brughera, Andrew; Colburn, H Steven; Shinn-Cunningham, Barbara

    2010-09-01

    Many past studies of sound localization explored the precedence effect (PE), in which a pair of brief, temporally close sounds from different directions is perceived as coming from a location near that of the first-arriving sound. Here, a computational model of low-frequency inferior colliculus (IC) neurons accounts for both physiological and psychophysical responses to PE click stimuli. In the model, IC neurons have physiologically plausible inputs, receiving excitation from the ipsilateral medial superior olive (MSO) and long-lasting inhibition from both ipsilateral and contralateral MSOs, relayed through the dorsal nucleus of the lateral lemniscus. In this model, physiological suppression of the lagging response depends on the inter-stimulus delay (ISD) between the lead and lag as well as their relative locations. Psychophysical predictions are generated from a population of model neurons. At all ISDs, predicted lead localization is good. At short ISDs, the estimated location of the lag is near that of the lead, consistent with subjects perceiving both lead and lag from the lead location. As ISD increases, the estimated lag location moves closer to the true lag location, consistent with listeners' perception of two sounds from separate locations. Together, these simulations suggest that location-dependent suppression in IC neurons can explain the behavioral phenomenon known as the precedence effect.

  20. Selective attention in the honeybee optic lobes precedes behavioral choices

    PubMed Central

    Paulk, Angelique C.; Stacey, Jacqueline A.; Pearson, Thomas W. J.; Taylor, Gavin J.; Moore, Richard J. D.; Srinivasan, Mandyam V.; van Swinderen, Bruno

    2014-01-01

    Attention allows animals to respond selectively to competing stimuli, enabling some stimuli to evoke a behavioral response while others are ignored. How the brain does this remains mysterious, although it is increasingly evident that even animals with the smallest brains display this capacity. For example, insects respond selectively to salient visual stimuli, but it is unknown where such selectivity occurs in the insect brain, or whether neural correlates of attention might predict the visual choices made by an insect. Here, we investigate neural correlates of visual attention in behaving honeybees (Apis mellifera). Using a closed-loop paradigm that allows tethered, walking bees to actively control visual objects in a virtual reality arena, we show that behavioral fixation increases neuronal responses to flickering, frequency-tagged stimuli. Attention-like effects were reduced in the optic lobes during replay of the same visual sequences, when bees were not able to control the visual displays. When bees were presented with competing frequency-tagged visual stimuli, selectivity in the medulla (an optic ganglion) preceded behavioral selection of a stimulus, suggesting that modulation of early visual processing centers precedes eventual behavioral choices made by these insects. PMID:24639490

  1. Changes in autonomic activity preceding onset of nonsustained ventricular tachycardia

    NASA Technical Reports Server (NTRS)

    Osaka, M.; Saitoh, H.; Sasabe, N.; Atarashi, H.; Katoh, T.; Hayakawa, H.; Cohen, R. J.

    1996-01-01

    Background: The triggering role of the autonomic nervous system in the initiation of ventricular tachycardia has not been established. To investigate the relationship between changes in autonomic activity and the occurrence of nonsustained ventricular tachycardia (NSVT) we examined heart rate variability (HRV) during the 2-hour period preceding spontaneous episodes of NSVT. Twenty-four subjects were identified retrospectively as having had one episode of NSVT during 24-hour Holter ECC recording. Methods: We measured the mean interval between normal heats (meanRR), the standard deviation of the intervals between beats (SD), the percentage of counts of sequential intervals between normal beats with a change of >50 ms (%RR50), the logarithms of low- and high-frequency spectral components (lnLF, lnHF) of HRV for sequential 10-minute segments preceding NSVT. The correlation dimension (CDim) of HRV was calculated similarly for sequential 20-minute segments. We assessed the significance of the time-course change of each marker over the 120-minute period prior to NSVT onset. Results: MeanRR (P < 0.05), lnLF (P < 0.0001), lnHF (P < 0.0001), the natural logarithm of the ratio of LF to HF (ln[LF/HF]; P < 0.05), and CDim (P < 0.05) showed significant time-course changes during that period, while SD and %RR50 did not. MeanRR, lnLF, lnHF, and CDim all decreased prior to the onset of NSVT, whereas ln(LF/HF) increased. We divided the subjects into two groups: one consisting of 12 patients with coronary artery disease; and the second group of 12 patients without known coronary artery disease. Both groups showed significant changes (P < 0.05) of CDim, lnLF, and lnHF preceding the episodes of NSVT. Conclusions: Changes in the pattern of HRV prior to the onset of episodes of NSVT suggest that changes in autonomic activity may commonly play a role in the triggering of spontaneous episodes of NSVT in susceptible patients. The measured changes suggest a reduction in parasympathetic

  2. 22 CFR 42.68 - Informal evaluation of family members if principal applicant precedes them.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... principal applicant precedes them. 42.68 Section 42.68 Foreign Relations DEPARTMENT OF STATE VISAS VISAS... Visas § 42.68 Informal evaluation of family members if principal applicant precedes them. (a) Preliminary determination of visa eligibility. If a principal applicant proposes to precede the family to...

  3. Revisiting Precede-Proceed: A Leading Model for Ecological and Ethical Health Promotion

    ERIC Educational Resources Information Center

    Porter, Christine M.

    2016-01-01

    Background: The Precede-Proceed model has provided moral and practical guidance for the fields of health education and health promotion since Lawrence Green first developed Precede in 1974 and Green and Kreuter added Proceed in 1991. Precede-Proceed today remains the most comprehensive and one of the most used approaches to promoting health.…

  4. Decision Preceding Negativity in the Iowa Gambling Task: An ERP study

    ERIC Educational Resources Information Center

    Bianchin, Marta; Angrilli, Alessandro

    2011-01-01

    The present study aimed to investigate the slow negative potential (termed Decision Preceding Negativity, DPN, from the family of the Readiness Potential) which precedes a willed risky decision. To this end, evoked potentials preceding and following an economic choice were measured in a sample of 16 male students during the Iowa Gambling Task…

  5. Electrical polarity in embryos of wild carrot precedes cotyledon differentiation.

    PubMed

    Brawley, S H; Wetherell, D F; Robinson, K R

    1984-10-01

    Endogenous electrical currents traverse embryos of a higher plant, the wild carrot Daucus carota L. Current enters the apical pole and leaves the region near the presumptive radicle in the radially symmetric globular embryo. Current also enters the exposed surfaces of incipient globular embryos. This electrical polarity precedes differentiation of vascular tissue and cotyledon development. Localized current is observed at both growing ends of the embryos in subsequent stages of embryogenesis. Inward current is found at the cotyledons; outward current is found at the radicle/root. Exogenous indole-3-acetic acid (3 muM) reversibly inhibits these currents. Little current traverses the surface of intermediate regions of the embryo. The ionic gradients generated by these currents may be important in accumulation of metabolites and in other developmental processes within the embryo.

  6. [The influences of laterality on global precedence: interference effects].

    PubMed

    Kimura, Jun

    2008-02-01

    This study aimed to clarify the influence of laterality on interference effects for global precedence, and to examine the mechanism of these effects. In most previous studies, the neutral condition was excluded from the consistency factor and the difference of latencies between the consistent and inconsistent conditions was regarded as the interference score, which may not be accurate. In this study, the difference of latencies between the neutral and the inconsistent condition was regarded as the interference score. The results of the analysis of variance (ANOVA) for latencies showed that interference effects influenced only right visual field-left hemisphere (RVF-LH), and facilitation effects influenced only left visual field-right hemisphere (LVF-RH) in the local condition. These findings indicate that it does not matter how optimal processing influenced interference effects on suboptimal processing in each hemisphere, for example how global processing influenced local processing in the right hemisphere, but rather how each hemisphere controlled optimal processing.

  7. Solar wind iron charge states preceding a driver plasma

    NASA Technical Reports Server (NTRS)

    Galvin, A. B.; Ipavich, F. M.; Gloeckler, G.; Hovestadt, D.; Tsurutani, B. T.

    1987-01-01

    Iron and silicon/sulfur charge state and velocity measurements and iron density measurements in the shocked solar wind which preceded the flare-related driver plasma observed on September 29, 1978 by ISEE 3 are reported. Given the assumption that the driver plasma is magnetically isolated from the ambient solar wind, the contact surface separating these two plasma regimes is expected to form an distinct boundary in the charge state composition. Instead, an apparent transition in the ionization state of the shocked solar wind from ambient solar wind values to those typical of the driver plasma is observed. This result may reflect X-ray ionization of the solar wind plasma near the flare site.

  8. The physics of charge separation preceding lightning strokes in thunderclouds

    NASA Technical Reports Server (NTRS)

    Kyrala, Ali

    1987-01-01

    The physics of charge separation preceding lightning strokes in thunderclouds is presented by three types of arguments: An explanation is given for the aggregation of electrical charges of like sign overcoming Coulomb repulsion by attraction due to exchange interaction. The latter is well known in quantum mechanics from the theories of the nuclear bond and the covalent bond. A classical electrostatic model of charge balls of segregated positive and negative charges in the thundercloud is presented. These charge balls can only be maintained in temporarily stable locations by a containing vortex. Because they will be of different sizes and masses, they will stabilize at different altitudes when drag forces are included with the given electrostatic force. The question of how the charges become concentrated again after lightning discharges is approached by means of the collisional Boltzmann transport equation to explain quasi-periodic recharging. It is shown that solutions cannot be separable in both position and time if they are to represent aggregation.

  9. Heart rate dynamics preceding hemorrhage in the intensive care unit.

    PubMed

    Moss, Travis J; Clark, Matthew T; Lake, Douglas E; Moorman, J Randall; Calland, J Forrest

    2015-01-01

    Occult hemorrhage in surgical/trauma intensive care unit (STICU) patients is common and may lead to circulatory collapse. Continuous electrocardiography (ECG) monitoring may allow for early identification and treatment, and could improve outcomes. We studied 4,259 consecutive admissions to the STICU at the University of Virginia Health System. We collected ECG waveform data captured by bedside monitors and calculated linear and non-linear measures of the RR interbeat intervals. We tested the hypothesis that a transfusion requirement of 3 or more PRBC transfusions in a 24 hour period is preceded by dynamical changes in these heart rate measures and performed logistic regression modeling. We identified 308 hemorrhage events. A multivariate model including heart rate, standard deviation of the RR intervals, detrended fluctuation analysis, and local dynamics density had a C-statistic of 0.62. Earlier detection of hemorrhage might improve outcomes by allowing earlier resuscitation in STICU patients.

  10. Evaluation of the effects of gender and estradiol treatment on the intestinal microcirculation during experimental sepsis.

    PubMed

    Sharawy, Nivin; Pavlovic, Dragan; Wendt, Michael; Cerny, Vladimir; Lehmann, Christian

    2011-11-01

    Intestinal barrier dysfunction plays an important role in sepsis. Females may tolerate sepsis better than males, which could be due to the relative resistance of the female intestine to gut injury and inflammation when subjected to sepsis. In this study the intestinal microcirculation was investigated in 50 female and 40 male rats divided in to 9 groups of 10 animals. Male and female rats were subjected to sham CASP (colon ascendens stent peritonitis). We induced experimental sepsis (CASP) in another two groups of male and female rats. The role of the estradiol treatment was evaluated both in male and ovariectomized female rats. Female rats were subjected to sham ovariectomy 3 weeks before sham CASP. Male and ovariectomized female rats were treated with estradiol (10mg/kg estradiol in rizinus oil immediately and 12h following CASP). Another two groups of male and ovariectomized female rats received placebo oil treatment. To evaluate the effects of gender and estradiol treatment on the microvascular perfusion during sepsis, intravital microscopy was performed twenty-four hours after sham CASP or CASP surgery, which permits the in vivo determination of leukocyte-endothelial cell interaction (rolling leukocytes and adherent leukocytes) and the measurement of functional capillary density (FCD), which served as the measure of quality of microvascular perfusion. We found that there was gender difference mainly in the leukocyte endothelial interaction rather than the functional capillary density (FCD), in which male showed significant increases (P<0.05) both in the leukocyte adhesion and rolling leukocytes in submucosal venules (V1 and V3) in comparison to female rats. (Leukocyte adhesion: V1 107.1 ± 49.2n/mm(2); V3 112.3 ± 68.1n/mm(2)) (Rolling leukocytes:V1 16.2 ± 10.3n/min; V3 8.4 ± 8.2n/min). In addition estradiol replacement in ovariectomized female and male rats induced significant decreases (P<0.05) in the leukocyte adhesion and rolling (V1 and V3) with a

  11. New paradigms in sepsis: from prevention to protection of failing microcirculation.

    PubMed

    Hawiger, J; Veach, R A; Zienkiewicz, J

    2015-10-01

    Sepsis, also known as septicemia, is one of the 10 leading causes of death worldwide. The rising tide of sepsis due to bacterial, fungal and viral infections cannot be stemmed by current antimicrobial therapies and supportive measures. New paradigms for the mechanism and resolution of sepsis and consequences for sepsis survivors are emerging. Consistent with Benjamin Franklin's dictum 'an ounce of prevention is worth a pound of cure', sepsis can be prevented by vaccinations against pneumococci and meningococci. Recently, the NIH NHLBI Panel redefined sepsis as 'severe endothelial dysfunction syndrome in response to intravascular and extravascular infections causing reversible or irreversible injury to the microcirculation responsible for multiple organ failure'. Microvascular endothelial injury underlies sepsis-associated hypotension, edema, disseminated intravascular coagulation, acute respiratory distress syndrome and acute kidney injury. Microbial genome products trigger 'genome wars' in sepsis that reprogram the human genome and culminate in a 'genomic storm' in blood and vascular cells. Sepsis can be averted experimentally by endothelial cytoprotection through targeting nuclear signaling that mediates inflammation and deranged metabolism. Endothelial 'rheostats' (e.g. inhibitors of NF-κB, A20 protein, CRADD/RAIDD protein and microRNAs) regulate endothelial signaling. Physiologic 'extinguishers' (e.g. suppressor of cytokine signaling 3) can be replenished through intracellular protein therapy. Lipid mediators (e.g. resolvin D1) hasten sepsis resolution. As sepsis cases rose from 387 330 in 1996 to 1.1 million in 2011, and are estimated to reach 2 million by 2020 in the US, mortality due to sepsis approaches that of heart attacks and exceeds deaths from stroke. More preventive vaccines and therapeutic measures are urgently needed. PMID:26190521

  12. Acute dairy milk ingestion does not improve nitric oxide-dependent vasodilation in the cutaneous microcirculation.

    PubMed

    Alba, Billie K; Stanhewicz, Anna E; Kenney, W Larry; Alexander, Lacy M

    2016-07-01

    In epidemiological studies, chronic dairy milk consumption is associated with improved vascular health and reduced age-related increases in blood pressure. Although milk protein supplementation augments conduit artery flow-mediated dilation, whether or not acute dairy milk intake may improve microvascular function remains unclear. We hypothesised that dairy milk would increase direct measurement of endothelial nitric oxide (NO)-dependent cutaneous vasodilation in response to local skin heating. Eleven men and women (61 (sem 2) years) ingested two or four servings (473 and 946 ml) of 1 % dairy milk or a rice beverage on each of 4 separate study days. In a subset of five subjects, an additional protocol was completed after 473 ml of water ingestion. Once a stable blood flow occurred, 15 mm-N G -nitro-l-arginine methyl ester was perfused (intradermal microdialysis) to quantify NO-dependent vasodilation. Red-blood-cell flux (RBF) was measured by laser-Doppler flowmetry, and cutaneous vascular conductance (CVC=RBF/mean arterial pressure) was calculated and normalised to maximum (%CVCmax; 28 mm-sodium nitroprusside). Full expression of cutaneous vasodilation was not different among dairy milk, rice beverage and water, and there was no effect of serving size on the total vasodilatory response. Contrary to our hypothesis, NO-dependent vasodilation was lower for dairy milk than rice beverage (D: 49 (sem 5), R: 55 (sem 5) %CVCmax; P<0·01). Acute dairy milk ingestion does not augment NO-dependent vasodilation in the cutaneous microcirculation compared with a rice beverage control.

  13. Effect of rhubarb pre-treatment on intestinal microcirculation in septic rats.

    PubMed

    Cui, Yun-Liang; Wang, Lv; Tian, Zhao-Tao; Lin, Zhao-Fen; Chen, De-Chang

    2014-01-01

    The intestine plays a vital role in the pathophysiology of sepsis development. The objective of the present study was to explore the effects of rhubarb on intestinal microcirculation in septic rats. We used moorFLPI laser speckle imaging to detect the blood flow of the intestinal mucosa and wall. Using an ELISA, we assayed the concentration of lactate (L) and pyruvic acid (P) in the intestinal tissue to calculate the ratio of lactate to pyruvic acid (L/P ratio). To observe the intestinal mucosal capillaries, gelatin and ink were perfused into the intestine and subsequently stained with hematoxylin and eosin (HE) to measure the ratio of the vessel area. We then used immunohistochemistry to measure CD31 expression. Using an MTT assay, the effect of the rhubarb extract on the proliferation of human umbilical vein endothelial cells (HUVECs) was analyzed. The blood flow in the intestinal wall and mucosa of the control, sham and rhubarb-treated groups was significantly higher, while the sepsis group had relatively low blood flow. The L/P ratio in the intestinal tissue was larger in the sepsis group than in the other three groups. The microvascular area (MVA) in the sepsis group was smaller than in the control group, sham group or rhubarb group. Positive expression for CD31 was observed in the cytoplasm of vascular endothelial cells. The intestinal mucosal capillaries were reduced in septic rats as compared to the other three groups. HUVEC proliferation was enhanced by the rhubarb extract monomers at 1 μmol/L, but suppressed at higher concentrations of 10 to 100 μmol/L. These results suggest that pre-treatment with rhubarb prior to sepsis induction promotes the expansion of the intestinal mucosal capillaries, protects intestinal mucosal capillary endothelial cells and increases the number of functional intestinal capillaries. PMID:25176604

  14. Non-invasive assessment of cerebral microcirculation with diffuse optics and coherent hemodynamics spectroscopy

    NASA Astrophysics Data System (ADS)

    Fantini, Sergio; Sassaroli, Angelo; Kainerstorfer, Jana M.; Tgavalekos, Kristen T.; Zang, Xuan

    2016-03-01

    We describe the general principles and initial results of coherent hemodynamics spectroscopy (CHS), which is a new technique for the quantitative assessment of cerebral hemodynamics on the basis of dynamic near-infrared spectroscopy (NIRS) measurements. The two components of CHS are (1) dynamic measurements of coherent cerebral hemodynamics in the form of oscillations at multiple frequencies (frequency domain) or temporal transients (time domain), and (2) their quantitative analysis with a dynamic mathematical model that relates the concentration and oxygen saturation of hemoglobin in tissue to cerebral blood volume (CBV), cerebral blood flow (CBF), and cerebral metabolic rate of oxygen (CMRO2). In particular, CHS can provide absolute measurements and dynamic monitoring of CBF, and quantitative measures of cerebral autoregulation. We report initial results of CBF measurements in hemodialysis patients, where we found a lower CBF (54 +/- 16 ml/(100 g-min)) compared to a group of healthy controls (95 +/- 11 ml/(100 g-min)). We also report CHS measurements of cerebral autoregulation, where a quantitative index of autoregulation (its cutoff frequency) was found to be significantly greater in healthy subjects during hyperventilation (0.034 +/- 0.005 Hz) than during normal breathing (0.017 +/- 0.002 Hz). We also present our approach to depth resolved CHS, based on multi-distance, frequency-domain NIRS data and a two-layer diffusion model, to enhance sensitivity to cerebral tissue. CHS offers a potentially powerful approach to the quantitative assessment and continuous monitoring of local brain perfusion at the microcirculation level, with prospective brain mapping capabilities of research and clinical significance.

  15. Intracardiac echocardiography guided transeptal catheter injection of microspheres for assessment of cerebral microcirculation in experimental models.

    PubMed

    Bellapart, Judith; Dunster, Kimble R; Diab, Sara; Platts, David G; Raffel, Christopher; Gabrielian, Levon; Maybauer, Marc O; Barnett, Adrian; Boots, Robert James; Fraser, John F

    2013-01-01

    The use of microspheres for the determination of regional microvascular blood flow (RMBF) has previously used different approaches. This study presents for the first time the intracardiac injection of microspheres using transeptal puncture under intracardiac echocardiography guidance. Five Merino sheep were instrumented and cardiovascularly supported according to local guidelines. Two catheter sheaths into the internal jugular vein facilitated the introduction of an intracardiac probe and transeptal catheter, respectively. Five million colour coded microspheres were injected into the left atrium via this catheter. After euthanasia the brain was used as proof of principle and the endpoint for determination of microcirculation at different time points. Homogeneous allocation of microspheres to different regions of the brain was found over time. Alternate slices from both hemispheres showed the following flow ranges: for slice 02; 0.57-1.02 mL/min/g, slice 04; 0.45-1.42 mL/min/g, slice 06; 0.35-1.87 mL/min/g, slice 08; 0.46-1.77 mL/min/g, slice 10; 0.34-1.28 mL/min/g. A mixed effect regression model demonstrated that the confidence interval did include zero suggesting that the apparent variability intra- and intersubject was not statistically significant, supporting the stability and reproducibility of the injection technique. This study demonstrates the feasibility of the transeptal injection of microspheres, showing a homogeneous distribution of blood flow through the brain unchanged over time and has established a new interventional model for the measurement of RMBF in ovine models.

  16. The role of sympathetic reflex control of cerebral blood flow and microcirculation during normoxia and hypoxia

    SciTech Connect

    Kissen, I.

    1989-01-01

    The purpose of this study was to investigate the hypothesis that there is sympathetic reflex regulation of the cerebral blood flow (CBF) and the utilization of microvessels during normoxia and hypoxia. Regional CBF was determined in conscious Long Evans rats with 4-iodo(N-methyl-{sup 14}C)antipyrine. The percentage of the microvessels perfused as determined by comparing perfused microvessels (FITC-dextran), with the total microvasculature (alkaline phosphatase stain). To test this hypothesis, arcs of the proposed reflex were eliminated. The first experiment examined the effect of bilateral superior cervical ganglionectomy on CBF and microcirulation during normoxia and hypoxia. CBF increased during hypoxia from 67 {plus minus} 2 to 115 {plus minus} 3 ml/min/100 g in control, and from 77 {plus minus} 2 to 155 {plus minus} 6 ml/min/100 g in ganglionectomized animals. In control, hypoxic flow to caudal areas was higher than to rostral areas and that difference was prevented by ganglionectomy. Utilization of arterioles during hypoxia increased from 51 {plus minus} 2% to 63 {plus minus} 2% in control, and from 52 {plus minus} 1% to 77 {plus minus} 2% in ganglionectomized group. The percent perfused capillaries during normoxia was 49 {plus minus} 2% in control, and 52 {plus minus} 1% in ganglionectomized group, and during hypoxia it was 73 {plus minus} 2% in both groups. In the second study, cerebral vascular responses to hypoxia were determined after administration of alpha-adrenoceptor antagonists N-methyl chlorpromazine (does not cross the blood-brain barrier), and phenoxybenzamine (crosses the blood-brain barrier). Neither phenoxybenzamine nor N-methyl chlorpromazine affected CBF and microcirculation during normoxia. During hypoxia, they similarly reversed the rostral to caudal gradient of flow, increased utilization of arterioles in rostral brain areas, and did not affect capillaries.

  17. Intracardiac echocardiography guided transeptal catheter injection of microspheres for assessment of cerebral microcirculation in experimental models.

    PubMed

    Bellapart, Judith; Dunster, Kimble R; Diab, Sara; Platts, David G; Raffel, Christopher; Gabrielian, Levon; Maybauer, Marc O; Barnett, Adrian; Boots, Robert James; Fraser, John F

    2013-01-01

    The use of microspheres for the determination of regional microvascular blood flow (RMBF) has previously used different approaches. This study presents for the first time the intracardiac injection of microspheres using transeptal puncture under intracardiac echocardiography guidance. Five Merino sheep were instrumented and cardiovascularly supported according to local guidelines. Two catheter sheaths into the internal jugular vein facilitated the introduction of an intracardiac probe and transeptal catheter, respectively. Five million colour coded microspheres were injected into the left atrium via this catheter. After euthanasia the brain was used as proof of principle and the endpoint for determination of microcirculation at different time points. Homogeneous allocation of microspheres to different regions of the brain was found over time. Alternate slices from both hemispheres showed the following flow ranges: for slice 02; 0.57-1.02 mL/min/g, slice 04; 0.45-1.42 mL/min/g, slice 06; 0.35-1.87 mL/min/g, slice 08; 0.46-1.77 mL/min/g, slice 10; 0.34-1.28 mL/min/g. A mixed effect regression model demonstrated that the confidence interval did include zero suggesting that the apparent variability intra- and intersubject was not statistically significant, supporting the stability and reproducibility of the injection technique. This study demonstrates the feasibility of the transeptal injection of microspheres, showing a homogeneous distribution of blood flow through the brain unchanged over time and has established a new interventional model for the measurement of RMBF in ovine models. PMID:24102032

  18. Method of assessing blood oxygenation in microcirculation vessels based on Doppler approach

    NASA Astrophysics Data System (ADS)

    Sokolov, Vladimir G.; Korsi, Larissa V.; Egorov, Sergei Y.

    2001-06-01

    Combination of laser Doppler flowmetry and pulse oximetry methods allows for the direct assessment of oxygen supply to tissues at the microcirculatory level, namely, in that part of the vascular network where the transcapillary exchange takes place that is responsible for saturating tissues with oxygen. The microcirculation system comprises arterial and venous microvascular parts that differ in blood flow velocities. Frequency separation of the photodetector signal components related to different velocity ranges makes possible to distinguish the hemodynamic processes in these two parts of the microvascular system. Moreover, numerous studies of collective oscillatory processes in hemodynamics reveal that cardio-oscillations are more pronounced in arterioles, whereas venous hemodynamics is mostly influenced by the breath rhythm. Taking account of the above phenomena allows developing a signal-filtration system for separate characterization of blood-oxygenation states in arterial and venous blood flows. Light absorbance in the skin depends on both light wavelength and blood-oxygenation level. Processing the signals obtained with a two-channel dual-wavelength (630 and 1115 nm) laser Doppler flowmeter provides information about blood oxygenation levels at the entrance and exit of the microvascular system and allows assessing the specific levels of oxygenation levels at the entrance and exit of the microvascular system and allows assessing the specific levels of oxygen consumption in tissues. In particular, this approach allows revealing pathogenic processes resulting from hyper- and hypo-oxygenation in tissues. For instance, rapidly growing malignant tumors are characterized by intensive metabolism, rapid formation of capillaries, and active transcapillary oxygen exchange that results in higher level of oxygen diffusion into tissue, while the level of oxygen is lowered in the microvascular veins.

  19. Increased peripheral vascular disease risk progressively constrains perfusion adaptability in the skeletal muscle microcirculation.

    PubMed

    Frisbee, Jefferson C; Butcher, Joshua T; Frisbee, Stephanie J; Olfert, I Mark; Chantler, Paul D; Tabone, Lawrence E; d'Audiffret, Alexandre C; Shrader, Carl D; Goodwill, Adam G; Stapleton, Phoebe A; Brooks, Steven D; Brock, Robert W; Lombard, Julian H

    2016-02-15

    To determine the impact of progressive elevations in peripheral vascular disease (PVD) risk on microvascular function, we utilized eight rat models spanning "healthy" to "high PVD risk" and used a multiscale approach to interrogate microvascular function and outcomes: healthy: Sprague-Dawley rats (SDR) and lean Zucker rats (LZR); mild risk: SDR on high-salt diet (HSD) and SDR on high-fructose diet (HFD); moderate risk: reduced renal mass-hypertensive rats (RRM) and spontaneously hypertensive rats (SHR); high risk: obese Zucker rats (OZR) and Dahl salt-sensitive rats (DSS). Vascular reactivity and biochemical analyses demonstrated that even mild elevations in PVD risk severely attenuated nitric oxide (NO) bioavailability and caused progressive shifts in arachidonic acid metabolism, increasing thromboxane A2 levels. With the introduction of hypertension, arteriolar myogenic activation and adrenergic constriction were increased. However, while functional hyperemia and fatigue resistance of in situ skeletal muscle were not impacted with mild or moderate PVD risk, blood oxygen handling suggested an increasingly heterogeneous perfusion within resting and contracting skeletal muscle. Analysis of in situ networks demonstrated an increasingly stable and heterogeneous distribution of perfusion at arteriolar bifurcations with elevated PVD risk, a phenomenon that was manifested first in the distal microcirculation and evolved proximally with increasing risk. The increased perfusion distribution heterogeneity and loss of flexibility throughout the microvascular network, the result of the combined effects on NO bioavailability, arachidonic acid metabolism, myogenic activation, and adrenergic constriction, may represent the most accurate predictor of the skeletal muscle microvasculopathy and poor health outcomes associated with chronic elevations in PVD risk. PMID:26702145

  20. Dissecting the Effects of Ischemia and Reperfusion on the Coronary Microcirculation in a Rat Model of Acute Myocardial Infarction

    PubMed Central

    Hollander, Maurits R.; de Waard, Guus A.; Konijnenberg, Lara S. F.; Meijer-van Putten, Rosalie M. E.; van den Brom, Charissa E.; Paauw, Nanne; de Vries, Helga E.; van de Ven, Peter M.; Aman, Jurjan; Van Nieuw-Amerongen, Geerten P.; Hordijk, Peter L.; Niessen, Hans W. M.; Horrevoets, Anton J. G.; Van Royen, Niels

    2016-01-01

    Background Microvascular injury (MVI) after coronary ischemia-reperfusion is associated with high morbidity and mortality. Both ischemia and reperfusion are involved in MVI, but to what degree these phases contribute is unknown. Understanding the etiology is essential for the development of new potential therapies. Methods and Findings Rats were divided into 3 groups receiving either 30 minutes ischemia, 90 minutes ischemia or 30 minutes ischemia followed by 60 minutes reperfusion. Subsequently hearts were ex-vivo perfused in a Langendorff-model. Fluorescence and electron microscopy was used for analysis of capillary density, vascular permeability and ultrastructure. Most MVI was observed after 30 minutes ischemia followed by 60 minutes reperfusion. In comparison to the 30’ and 90’ ischemia group, wall thickness decreased (207.0±74 vs 407.8±75 and 407.5±71, p = 0.02). Endothelial nuclei in the 30’-60’ group showed irreversible damage and decreased chromatin density variation (50.5±9.4, 35.4±7.1 and 23.7±3.8, p = 0.03). Cell junction density was lowest in the 30’-60’ group (0.15±0.02 vs 2.5±0.6 and 1.8±0.7, p<0.01). Microsphere extravasation was increased in both the 90’ ischemia and 30’-60’ group. Conclusions Ischemia alone for 90 minutes induces mild morphological changes to the coronary microcirculation, with increased vascular permeability. Ischemia for 30 minutes, followed by 60 minutes of reperfusion, induces massive MVI. This shows the direct consequences of reperfusion on the coronary microcirculation. These data imply that a therapeutic window exists to protect the microcirculation directly upon coronary revascularization. PMID:27391645

  1. Parameters of Microcirculation in the Broad Ligament of the Uterus in Wistar Rats after Injection of Autologous Biomedical Cell Product.

    PubMed

    Dergacheva, T I; Lykov, A P; Shurlygina, A V; Starkova, E V; Poveshchenko, O V; Bondarenko, N A; Kim, I I; Tenditnik, M V; Borodin, Yu I; Konenkov, V I

    2015-10-01

    We studied the effects of autologous biomedical cell product (bone marrow multipotent mesenchymal stromal cells and their conditioned media) on the parameters of the microcirculatory bed in the broad ligament of the uterus of normal Wistar rats were studied. The parameters of microcirculation and lymph drainage in the broad ligament changed in opposite directions in response to injection of autologous biomedical cell product via different routes. This fact should be taken into consideration when prescribing cell therapy for inflammatory degenerative processes in the pelvic organs.

  2. Cerebral potentials preceding unilateral and simultaneous bilateral finger movements.

    PubMed

    Kristeva, R; Keller, E; Deecke, L; Kornhuber, H H

    1979-08-01

    Cerebral potentials preceding voluntary bilateral simultaneous finger movements were investigated in 19 right-handed young adult subjects, and were compared with unilateral right-sided finger m n the same experiment. With bilateral movements, the Bereitschaftspotential (BP) was not symmetrical or larger over the dominant hemisphere, but surprisingly, it was larger over the minor hemisphere. The BP averaged -3.66 microV (S.D. 1.96) over the left precentral region and -4.82 microV (S.D. 3.73) over the right precentral region in this condition. The difference was significant at 2P less than 0.01. This difference was pronounced in precentral leads but very small and almost missing in parietal leads. The pre-motion positivity (PMP) was well developed and even larger with bilateral than with unilateral (right-sides) movements. At the vertex it averaged +1.33 microV (S.D.4.16) with bilateral movements and only +0.15 microV (S.D. 1.42) with right-sided unilateral movements (2P less than 0.05). With bilateral movements the PMP could be observed in any record, but with unilateral movements it was missing at the left precentral lead, in accordance with previous publications (Deecke et al. 1969, 1976). The motor potential (MP), measured in a bipolar record from left and right precentral leads, was larger with unilateral (-1.25 microV, S.D. 1.33) than with bilateral movements (-0.36 microV, S.D. 0.92). Onset time differences of the BP preceding unilateral and bilateral movements were very small. However, there was a tendency towards earlier onset with unilateral than with bilateral movements (1031 msec, S.D. 358, as compared with 951 msec, S.D. 305). The averaged EMG revealed differences in movement onset. Muscular contraction tended to be earlier in the right than in the left m. flexor indicis in our right-handed subjects, on the average by 16 msec (S.D. 15). With unilateral right-sided movements, the left m. flexor indicis was not silent but showed an abortive mirror activity

  3. Lithospheric Convergence Preceded Extension in the Pannonian-Carpathian System

    NASA Astrophysics Data System (ADS)

    Houseman, Gregory; Stuart, Graham; Dando, Ben; Hetenyi, Gyorgy; Lorinczi, Piroska; Hegedus, Endre; Brueckl, Ewald

    2010-05-01

    The continuing collision of the Adriatic block with European continental lithosphere has its clearest expression now in the Alpine collision zone. Recent tomographic images of the upper mantle beneath the eastern Alps and western Pannonian Basin support the interpretation that in the Early Miocene the collision zone extended further east: a steeply dipping seismically fast structure stretches downward beneath the Eastern Alps reaching to the base of the transition zone, consistent with the long history of convergence in this region. This high velocity structure also extends eastward beneath the extensional Pannonian Basin. The high velocity anomaly beneath the Basin is strongly developed in transition zone depths (410 to 660 km) but the anomaly weakens upward. High velocities beneath the center of the extensional basin are unexpected because there is substantive evidence that the onset of extension in the Pannonian domain at around 17 Ma produced rapid extension of the lithosphere and replacement of the lower part of the lithosphere by hot asthenosphere. These deeper structures, however, must be explained by the long history of convergence that preceded the extension of the basin. Further evidence of a history of sustained convergence in the present Pannonian region is found in the depression of the 660 km seismic discontinuity beneath the Alps (Lombardi et al., EPSL, 2009) and also beneath the Pannonian Basin (Hetenyi et al., GRL, 2009). The 660 km discontinuity in both places is depressed by as much as 40 km, whereas the 410 km discontinuity is at approximately nominal depths. Evidently in both regions relatively dense material derived from the mid-Miocene collision sits stagnant on top of the 660 km discontinuity, where further descent is obstructed by the negative Clapeyron slope of the spinel-to-perovskite phase transition and/or the high viscosity of the lower mantle. The rapid extension of the Intra-Carpathian Basins in the Mid-Miocene (between about 17 and

  4. Mancozeb-induced behavioral deficits precede structural neural degeneration.

    PubMed

    Harrison Brody, A; Chou, Eunice; Gray, Janet M; Pokyrwka, Nancy J; Raley-Susman, Kathleen M

    2013-01-01

    Manganese-containing fungicides like Mancozeb have been associated with neurodegenerative conditions like Parkinson's disease. We examined the behavioral damage and differential neuronal vulnerability resulting from Mancozeb exposure using Caenorhabditis elegans, an important mid-trophic level soil organism that is also a powerful model for studying mechanisms of environmental pollutant-induced neurodegenerative disease. The dopamine-mediated swim to crawl locomotory transition behavior is exquisitely vulnerable to Mancozeb, with functional impairment preceding markers of neuronal structural damage. The damage is partially rescued in mutants lacking the divalent metal transporter, SMF-1, demonstrating that some, but not all, of the damage is mediated by manganese. Increasing concentrations of Mancozeb recruit additional behavioral dysfunction, notably serotonin-mediated egg-laying behavior, but without evident serotonergic neuronal structural damage. Thus, measurements of behavioral dysfunction are a sensitive early marker of fungicide toxicity that could be exploited to examine further mechanisms of neuron damage and possible therapeutic interventions. These results also provide important insight into the consequences of fungicide use on the ecological behavior of nematodes. PMID:23103283

  5. Joint shape morphogenesis precedes cavitation of the developing hip joint

    PubMed Central

    Nowlan, Niamh C; Sharpe, James

    2014-01-01

    The biology and mechanobiology of joint cavitation have undergone extensive investigation, but we have almost no understanding of the development of joint shape. Joint morphogenesis, the development of shape, has been identified as the ‘least understood aspect of joint formation’ (2005, Birth Defects Res C Embryo Today 75, 237), despite the clinical relevance of shape morphogenesis to postnatal skeletal malformations such as developmental dysplasia of the hip. In this study, we characterise development of early hip joint shape in the embryonic chick using direct capture 3D imaging. Contrary to formerly held assumptions that cavitation precedes morphogenesis in joint development, we have found that the major anatomical features of the adult hip are present at Hamburger Hamilton (HH)32, a full day prior to cavitation of the joint at HH34. We also reveal that the pelvis undergoes significant changes in orientation with respect to the femur, despite the lack of a joint cavity between the rudiments. Furthermore, we have identified the appearance of the ischium and pubis several developmental stages earlier than was previously reported, illustrating the value and importance of direct capture 3D imaging. PMID:24266523

  6. High rates of evolution preceded the origin of birds.

    PubMed

    Puttick, Mark N; Thomas, Gavin H; Benton, Michael J

    2014-05-01

    The origin of birds (Aves) is one of the great evolutionary transitions. Fossils show that many unique morphological features of modern birds, such as feathers, reduction in body size, and the semilunate carpal, long preceded the origin of clade Aves, but some may be unique to Aves, such as relative elongation of the forelimb. We study the evolution of body size and forelimb length across the phylogeny of coelurosaurian theropods and Mesozoic Aves. Using recently developed phylogenetic comparative methods, we find an increase in rates of body size and body size dependent forelimb evolution leading to small body size relative to forelimb length in Paraves, the wider clade comprising Aves and Deinonychosauria. The high evolutionary rates arose primarily from a reduction in body size, as there were no increased rates of forelimb evolution. In line with a recent study, we find evidence that Aves appear to have a unique relationship between body size and forelimb dimensions. Traits associated with Aves evolved before their origin, at high rates, and support the notion that numerous lineages of paravians were experimenting with different modes of flight through the Late Jurassic and Early Cretaceous.

  7. PRECEDENTS FOR AUTHORIZATION OF CONTENTS USING DOSE RATE MEASUREMENTS

    SciTech Connect

    Abramczyk, G.; Bellamy, S.; Nathan, S.; Loftin, B.

    2012-06-05

    For the transportation of Radioactive Material (RAM) packages, the requirements for the maximum allowed dose rate at the package surface and in its vicinity are given in Title 10 of the Code of Federal Regulations, Section 71.47. The regulations are based on the acceptable dose rates to which the public, workers, and the environment may be exposed. As such, the regulations specify dose rates, rather than quantity of radioactive isotopes and require monitoring to confirm the requirements are met. 10CFR71.47 requires that each package of radioactive materials offered for transportation must be designed and prepared for shipment so that under conditions normally incident to transportation the radiation level does not exceed 2 mSv/h (200 mrem/h) at any point on the external Surface of the package, and the transport index does not exceed 10. Before shipment, the dose rate of the package is determined by measurement, ensuring that it conforms to the regulatory limits, regardless of any analyses. This is the requirement for all certified packagings. This paper discusses the requirements for establishing the dose rates when shipping RAM packages and the precedents for meeting these requirements by measurement.

  8. Activation of ras oncogenes preceding the onset of neoplasia

    SciTech Connect

    Kumar, R.; Barbacid, M. ); Sukumar, S. )

    1990-06-01

    The identification of ras oncogenes in human and animal cancers including precancerous lesions indicates that these genes participate in the early stages of neoplastic development. Yet, these observations do not define the timing of ras oncogene activation in the multistep process of carcinogenesis. To ascertain the timing of ras oncogene activation, an animal model system was devised that involves the induction of mammary carcinomas in rats exposed at birth to the carcinogen nitrosomethylurea. High-resolution restriction fragment length polymorphism analysis of polymerase chain reaction-amplified ras sequences revealed the presence of both H-ras and K-ras oncogenes in normal mammary glands 2 weeks after carcinogen treatment and at least 2 months before the onset of neoplasia. These ras oncogenes can remain latent within the mammary gland until exposure to estrogens, demonstrating that activation of ras oncogenes can precede the onset of neoplasia and suggesting that normal physiological proliferative processes such as estrogen-induced mammary gland development may lead to neoplasia if the targeted cells harbor latent ras oncogenes.

  9. Bell's palsy: symptoms preceding and accompanying the facial paresis.

    PubMed

    De Seta, Daniele; Mancini, Patrizia; Minni, Antonio; Prosperini, Luca; De Seta, Elio; Attanasio, Giuseppe; Covelli, Edoardo; De Carlo, Andrea; Filipo, Roberto

    2014-01-01

    This individual prospective cohort study aims to report and analyze the symptoms preceding and accompanying the facial paresis in Bell's palsy (BP). Two hundred sixty-nine patients affected by BP with a maximum delay of 48 hours from the onset were enrolled in the study. The evolution of the facial paresis expressed as House-Brackmann grade in the first 10 days and its correlation with symptoms were analyzed. At the onset, 136 patients presented postauricular pain, 114 were affected by dry eye, and 94 reported dysgeusia. Dry mouth was present in 54 patients (19.7%), facial pain, hyperlacrimation, aural fullness, and hyperacusis represented a smaller percentage of the reported symptoms. After 10 days, 39.9% of the group had a severe paresis while 10.2% reached a complete recovery. Dry mouth at the onset was correlated with severe grade of palsy and was prognostic for poor recovery in the early period. These outcomes lead to the deduction that the nervus intermedius plays an important role in the presentation of the BP and it might be responsible for most of the accompanying symptomatology of the paresis. Our findings could be of important interest to early address a BP patient to further examinations and subsequent therapy.

  10. Neurological Evidence Linguistic Processes Precede Perceptual Simulation in Conceptual Processing

    PubMed Central

    Louwerse, Max; Hutchinson, Sterling

    2012-01-01

    There is increasing evidence from response time experiments that language statistics and perceptual simulations both play a role in conceptual processing. In an EEG experiment we compared neural activity in cortical regions commonly associated with linguistic processing and visual perceptual processing to determine to what extent symbolic and embodied accounts of cognition applied. Participants were asked to determine the semantic relationship of word pairs (e.g., sky – ground) or to determine their iconic relationship (i.e., if the presentation of the pair matched their expected physical relationship). A linguistic bias was found toward the semantic judgment task and a perceptual bias was found toward the iconicity judgment task. More importantly, conceptual processing involved activation in brain regions associated with both linguistic and perceptual processes. When comparing the relative activation of linguistic cortical regions with perceptual cortical regions, the effect sizes for linguistic cortical regions were larger than those for the perceptual cortical regions early in a trial with the reverse being true later in a trial. These results map upon findings from other experimental literature and provide further evidence that processing of concept words relies both on language statistics and on perceptual simulations, whereby linguistic processes precede perceptual simulation processes. PMID:23133427

  11. Destruction of rat mammary tumor and normal tissue microcirculation by hematoporphyrin derivative photoradiation observed in vivo in sandwich observation chambers.

    PubMed

    Star, W M; Marijnissen, H P; van den Berg-Blok, A E; Versteeg, J A; Franken, K A; Reinhold, H S

    1986-05-01

    The effect of hematoporphyrin derivative photoradiation on tumor and normal tissue microcirculation was studied microscopically in vivo on rats with mammary carcinomas transplanted into subcutis in transparent observation chambers. One day after i.p. injection of hematoporphyrin derivative (15 mg/kg), chambers were exposed to red light (632 +/- 2 nm, eight light dose values, 0 to 270 J/cm2). After an initial blanching (ischemia) of the tumor accompanied by apparent vasoconstriction, reperfusion was observed with a slowing down of the tumor circulation, vasodilatation, and eventually a complete stasis, together with diffuse hemorrhages and subsequent necrosis. Besides, in large normal tissue vessels, platelet aggregates were observed, but no hemorrhage. Tumor regrowth occurred unless the tumor circulation and the adjacent normal tissue circulation were both destroyed. Tumor cell viability after treatment was assessed by transplanting the tumor from the chamber into the flank of the same animal. Even after a combined porphyrin and light dose 4 times the lethal dose for all tissues in the chamber, five of five transplanted tumors did regrow. This leads to the conclusion that, in our model system, tumor cell death after photoradiation occurs secondary to destruction of the microcirculation. In order to obtain additional information on normal tissue damage, rat ears were also irradiated. For the same light dose, the biological effect was only slightly larger than that of the normal tissue in the observation chambers, even though the measured ratio of porphyrin concentrations in ears and normal tissue in the chambers (subcutis) was about six.

  12. Electroacupuncture improves microcirculation and neuronal morphology in the spinal cord of a rat model of intervertebral disc extrusion.

    PubMed

    Jiang, Dai-Xun; Lu, Zhi-Song; Li, Ge-Bin; Sun, Sheng-Yong; Mu, Xiang; Lee, Peter; Chen, Wu

    2015-02-01

    Most studies on spinal cord neuronal injury have focused on spinal cord tissue histology and the expression of nerve cell damage and repair-related genes. The importance of the microcirculation is often ignored in spinal cord injury and repair research. Therefore, in this study, we established a rat model of intervertebral disc extrusion by inserting a silica gel pad into the left ventral surface of T13. Electroacupuncture was used to stimulate the bilateral Zusanli point (ST36) and Neiting point (ST44) for 14 days. Compared with control animals, blood flow in the first lumbar vertebra (L1) was noticeably increased in rats given electroacupuncture. Microvessel density in the T13 segment of the spinal cord was increased significantly as well. The number of normal neurons was higher in the ventral horn of the spinal cord. In addition, vacuolation in the white matter was lessened. No obvious glial cell proliferation was visible. Furthermore, hindlimb motor function was improved significantly. Collectively, our results suggest that electroacupuncture can improve neuronal morphology and microcirculation, and promote the recovery of neurological functions in a rat model of intervertebral disc extrusion. PMID:25883622

  13. Electroacupuncture improves microcirculation and neuronal morphology in the spinal cord of a rat model of intervertebral disc extrusion

    PubMed Central

    Jiang, Dai-xun; Lu, Zhi-song; Li, Ge-bin; Sun, Sheng-yong; Mu, Xiang; Lee, Peter; Chen, Wu

    2015-01-01

    Most studies on spinal cord neuronal injury have focused on spinal cord tissue histology and the expression of nerve cell damage and repair-related genes. The importance of the microcirculation is often ignored in spinal cord injury and repair research. Therefore, in this study, we established a rat model of intervertebral disc extrusion by inserting a silica gel pad into the left ventral surface of T13. Electroacupuncture was used to stimulate the bilateral Zusanli point (ST36) and Neiting point (ST44) for 14 days. Compared with control animals, blood flow in the first lumbar vertebra (L1) was noticeably increased in rats given electroacupuncture. Microvessel density in the T13 segment of the spinal cord was increased significantly as well. The number of normal neurons was higher in the ventral horn of the spinal cord. In addition, vacuolation in the white matter was lessened. No obvious glial cell proliferation was visible. Furthermore, hindlimb motor function was improved significantly. Collectively, our results suggest that electroacupuncture can improve neuronal morphology and microcirculation, and promote the recovery of neurological functions in a rat model of intervertebral disc extrusion. PMID:25883622

  14. The importance of liver microcirculation in promoting autoimmune hepatitis via maintaining an inflammatory cytokine milieu--a mathematical model study.

    PubMed

    Lettmann, Karsten Alexander; Hardtke-Wolenski, Matthias

    2014-05-01

    In autoimmune diseases, inflammatory cytokine concentrations are important for initiating and maintaining the status of autoimmunity. Autoimmune hepatitis (AIH) is an inflammatory liver disease characterized by a loss of immune tolerance against specific antigens located in hepatocytes. During the progression of the disease, antigen-presenting cells and different classes of T-helper cells secrete specific cytokines important for maintaining the disease. As these cytokines are secreted into the local liver environment, the blood flow in liver sinusoids might influence the local cytokine concentration. Considering the liver tissue as a porous medium, based on Darcy׳s law, the microcirculation within a liver lobule was modelled. Using realistic physiological pressure differences and tissue permeabilities, the blood velocity inside the sinusoids could be calculated and validated with blood velocity data obtained via Orthogonal Polarization Spectral Imaging (OPSI). Furthermore, oxygen consumption is modelled to obtain Rappaport׳s acinus model. Finally, steady state spatial distributions of secreted cytokines within the liver lobule could be estimated for specified realistic production rates of T-helper cells. It could be demonstrated that the characteristics of the liver microcirculation have an important impact on establishing inflammatory cytokine levels within the portal fields and the vascular septa promoting the occurrence of interface hepatitis.

  15. Noncontacting diffuse VIS-NIR spectroscopy of human skin for evaluation of skin type and time-dependent microcirculation

    NASA Astrophysics Data System (ADS)

    Schmidt, Wolf-Dieter; Fassler, Dieter; Zimmermann, Gabi; Liebold, Kristin; Wollina, Uwe

    2000-11-01

    Spectroscopic investigations of the VIS-NIR range allow the objective determination of pigmentation, blood microcirculation and water content of human skin. Non- contacting in vivo measurements of the human skin of 50 volunteers reflect the clinical skin type well. Our correlation analysis yields that the red/infrared spectral range can be used for a determination of skin type. The observed strong spectral variations within the same group of skin type are likely based on the high biological variability of human skin and subjective clinically observed skin type. Therefore it can be useful to measure the full spectral range and to calculate a non-observed skin score with multivariate spectral methods. By multivariate analysis a correct classification of remittance spectra can be obtained. Time- depending spectral variations of dermal microcirculation can be measured at defined locations of the body, for instance the dynamics of oxygenation or blood volume in the skin of the fingertip. The cardial, pulmonal and vasomotoric waves of the micro- and macrocirculation are clearly visible at different wavelengths. The spectroscopic informations are important as an objective measure for the skin type evaluation, the penetration behavior of pharmaca, laser surgery, and therapy.

  16. Effects of carbogen on decreases in endocochlear potential and cochlear microcirculation induced by ischemia of the cochlea.

    PubMed

    Hua, H B; Chang, J S; Rui, G

    1993-11-01

    Preventive effects of carbogen on decreases in endocochlear potential (EP) and cochlear microcirculation induced by ischemia of the cochlea were examined in guinea pigs with intravital microscopy. The experimental model giving a severe decline in cochlear blood flow (CBF) was established by occlusion of both common carotid arteries and one of the vertebral arteries and i.v. infusion of adenosine triphosphate (ATP). The results showed no significant difference in the magnitude and pattern of the decrease in the cochlear microcirculation induced by ATP infusion and arterial occlusion before and after carbogen inhalation. However, even with a dramatic decrease in CBF, carbogen could reduce the decline in EP. The results clearly indicate that although carbogen fails to ameliorate cochlear ischemia in the face of a large impairment of the blood supply caused by a drop of blood pressure and cardiac output, it does in fact enhance the oxygen delivery to the cochlea and thus provide a therapeutic means of treating certain inner ear diseases caused by insufficient blood supply to the cochlea. PMID:8291429

  17. Rarefaction Effects in Hypersonic Aerodynamics

    NASA Astrophysics Data System (ADS)

    Riabov, Vladimir V.

    2011-05-01

    The Direct Simulation Monte-Carlo (DSMC) technique is used for numerical analysis of rarefied-gas hypersonic flows near a blunt plate, wedge, two side-by-side plates, disk, torus, and rotating cylinder. The role of various similarity parameters (Knudsen and Mach numbers, geometrical and temperature factors, specific heat ratios, and others) in aerodynamics of the probes is studied. Important kinetic effects that are specific for the transition flow regime have been found: non-monotonic lift and drag of plates, strong repulsive force between side-by-side plates and cylinders, dependence of drag on torus radii ratio, and the reverse Magnus effect on the lift of a rotating cylinder. The numerical results are in a good agreement with experimental data, which were obtained in a vacuum chamber at low and moderate Knudsen numbers from 0.01 to 10.

  18. Integrated Vehicle Ground Vibration Testing of Manned Spacecraft: Historical Precedent

    NASA Technical Reports Server (NTRS)

    Lemke, Paul R.; Tuma, Margaret L.; Askins, Bruce R.

    2008-01-01

    For the first time in nearly 30 years, NASA is developing a new manned space flight launch system. The Ares I will carry crew and cargo to not only the International Space Station, but onward for the future exploration of the Moon and Mars. The Ares I control system and structural designs use complex computer models for their development. An Integrated Vehicle Ground Vibration Test (IVGVT) will validate the efficacy of these computer models. The IVGVT will reduce the technical risk of unexpected conditions that could place the vehicle or crew in jeopardy. The Ares Project Office's Flight and Integrated Test Office commissioned a study to determine how historical programs, such as Saturn and Space Shuttle, validated the structural dynamics of an integrated flight vehicle. The study methodology was to examine the historical record and seek out members of the engineering community who recall the development of historic manned launch vehicles. These records and interviews provided insight into the best practices and lessons learned from these historic development programs. The information that was gathered allowed the creation of timelines of the historic development programs. The timelines trace the programs from the development of test articles through test preparation, test operations, and test data reduction efforts. These timelines also demonstrate how the historical tests fit within their overall vehicle development programs. Finally, the study was able to quantify approximate staffing levels during historic development programs. Using this study, the Flight and Integrated Test Office was able to evaluate the Ares I Integrated Vehicle Ground Vibration Test schedule and workforce budgets in light of the historical precedents to determine if the test had schedule or cost risks associated with it.

  19. Increased cerebral oxygenation precedes generalized tonic clonic seizures.

    PubMed

    Moseley, Brian D; Britton, Jeffrey W; So, Elson

    2014-11-01

    Based on previous fMRI and SPECT studies, it has been suggested seizures may be preceded by increased cerebral blood flow. Recently, we demonstrated transcutaneous regional cerebral oxygen saturation (rSO2) sensors are feasible for use in patients undergoing video EEG monitoring. We reanalyzed our data to determine if seizures were consistently marked by increased cerebral oxygenation. Patients with histories of generalized tonic clonic seizures (GTCS) were recruited into our study. All subjects were evaluated with continuous 30-channel scalp EEG and 2 rSO2 sensors placed on each side of the forehead. We calculated the mean rSO2 value for the 1h epochs in the non-ictal (2h prior to seizure onset) and pre-ictal (1h prior to onset) periods. Seven primary/secondarily GTCS from 5 patients were captured. The mean rSO2 value in the non-ictal period was 75.6 ± 5.7%. This increased to 76.0 ± 6% in the pre-ictal period (p=0.032). Four of the 7GTCS (57.1%) were marked by ≥ 3 sequential rSO2 values in the pre-ictal period that were ≥ 3 SDs greater than the mean non-ictal rSO2 value. Three GTCS (42.9%) were marked by sustained cerebral hyperemia for ≥ 15 consecutive readings. Our results suggest increased cerebral blood flow could be non-invasively used to predict seizure occurrence. PMID:25277885

  20. Axonal Dysfunction Precedes Motor Neuronal Death in Amyotrophic Lateral Sclerosis.

    PubMed

    Iwai, Yuta; Shibuya, Kazumoto; Misawa, Sonoko; Sekiguchi, Yukari; Watanabe, Keisuke; Amino, Hiroshi; Kuwabara, Satoshi

    2016-01-01

    Wide-spread fasciculations are a characteristic feature in amyotrophic lateral sclerosis (ALS), suggesting motor axonal hyperexcitability. Previous excitability studies have shown increased nodal persistent sodium conductances and decreased potassium currents in motor axons of ALS patients, both of the changes inducing hyperexcitability. Altered axonal excitability potentially contributes to motor neuron death in ALS, but the relationship of the extent of motor neuronal death and abnormal excitability has not been fully elucidated. We performed multiple nerve excitability measurements in the median nerve at the wrist of 140 ALS patients and analyzed the relationship of compound muscle action potential (CMAP) amplitude (index of motor neuronal loss) and excitability indices, such as strength-duration time constant, threshold electrotonus, recovery cycle and current-threshold relationships. Compared to age-matched normal controls (n = 44), ALS patients (n = 140) had longer strength-duration time constant (SDTC: a measure of nodal persistent sodium current; p < 0.05), greater threshold changes in depolarizing threshold electrotonus (p < 0.05) and depolarizing current threshold relationship (i.e. less accommodation; (p < 0.05), greater superexcitability (a measure of fast potassium current; p < 0.05) and reduced late subexcitability (a measure of slow potassium current; p < 0.05), suggesting increased persistent sodium currents and decreased potassium currents. The reduced potassium currents were found even in the patient subgroups with normal CMAP (> 5mV). Regression analyses showed that SDTC (R = -0.22) and depolarizing threshold electrotonus (R = -0.22) increased with CMAP decline. These findings suggest that motor nerve hyperexcitability occurs in the early stage of the disease, and precedes motor neuronal loss in ALS. Modulation of altered ion channel function could be a treatment option for ALS. PMID:27383069

  1. Axonal Dysfunction Precedes Motor Neuronal Death in Amyotrophic Lateral Sclerosis

    PubMed Central

    Iwai, Yuta; Shibuya, Kazumoto; Misawa, Sonoko; Sekiguchi, Yukari; Watanabe, Keisuke; Amino, Hiroshi; Kuwabara, Satoshi

    2016-01-01

    Wide-spread fasciculations are a characteristic feature in amyotrophic lateral sclerosis (ALS), suggesting motor axonal hyperexcitability. Previous excitability studies have shown increased nodal persistent sodium conductances and decreased potassium currents in motor axons of ALS patients, both of the changes inducing hyperexcitability. Altered axonal excitability potentially contributes to motor neuron death in ALS, but the relationship of the extent of motor neuronal death and abnormal excitability has not been fully elucidated. We performed multiple nerve excitability measurements in the median nerve at the wrist of 140 ALS patients and analyzed the relationship of compound muscle action potential (CMAP) amplitude (index of motor neuronal loss) and excitability indices, such as strength-duration time constant, threshold electrotonus, recovery cycle and current-threshold relationships. Compared to age-matched normal controls (n = 44), ALS patients (n = 140) had longer strength-duration time constant (SDTC: a measure of nodal persistent sodium current; p < 0.05), greater threshold changes in depolarizing threshold electrotonus (p < 0.05) and depolarizing current threshold relationship (i.e. less accommodation; (p < 0.05), greater superexcitability (a measure of fast potassium current; p < 0.05) and reduced late subexcitability (a measure of slow potassium current; p < 0.05), suggesting increased persistent sodium currents and decreased potassium currents. The reduced potassium currents were found even in the patient subgroups with normal CMAP (> 5mV). Regression analyses showed that SDTC (R = -0.22) and depolarizing threshold electrotonus (R = -0.22) increased with CMAP decline. These findings suggest that motor nerve hyperexcitability occurs in the early stage of the disease, and precedes motor neuronal loss in ALS. Modulation of altered ion channel function could be a treatment option for ALS. PMID:27383069

  2. Rising catch variability preceded historical fisheries collapses in Alaska.

    PubMed

    Litzow, Michael A; Mueter, Franz J; Urban, J Daniel

    2013-09-01

    Statistical indicators such as rising variance and rising skewness in key system parameters may provide early warning of "regime shifts" in communities and populations. However, the utility of these indicators has rarely been tested in the large, complex ecosystems that are of most interest to managers. Crustacean fisheries in the Gulf of Alaska and Bering Sea experienced a series of collapses beginning in the 1970s, and we used spatially resolved catch data from these fisheries to test the predictions that increasing variability and skewness would precede stock collapse. Our data set consisted of catch data from 14 fisheries (12 collapsing and two non-collapsing), spanning 278 cumulative years. Our sampling unit for analysis was the Alaska Department of Fish and Game statistical reporting area (mean n for individual fisheries = 42 areas, range 7-81). We found that spatial variability in catches increased prior to stock collapse: a random-effects model estimating trend in variability across all 12 collapsing fisheries showed strong evidence of increasing variability prior to collapse. Individual trends in variability were statistically significant for only four of the 12 collapsing fisheries, suggesting that rising variability might be most effective as an indicator when information from multiple populations is available. Analyzing data across multiple fisheries allowed us to detect increasing variability 1-4 years prior to collapse, and trends in variability were significantly different for collapsing and non-collapsing fisheries. In spite of theoretical expectations, we found no evidence of pre-collapse increases in catch skewness. Further, while models generally predict that rising variability should be a transient phenomenon around collapse points, increased variability was a persistent feature of collapsed fisheries in our study. We conclude that this result is more consistent with fishing effects as the cause of increased catch variability, rather than the

  3. 26 CFR 1.665(e)-1A - Preceding taxable year.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 8 2014-04-01 2014-04-01 false Preceding taxable year. 1.665(e)-1A Section 1... (CONTINUED) INCOME TAXES (CONTINUED) Treatment of Excess Distributions of Trusts Applicable to Taxable Years Beginning on Or After January 1, 1969 § 1.665(e)-1A Preceding taxable year. (a) Definition—(1)...

  4. 26 CFR 1.665(e)-1A - Preceding taxable year.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 8 2012-04-01 2012-04-01 false Preceding taxable year. 1.665(e)-1A Section 1... (CONTINUED) INCOME TAXES (CONTINUED) Treatment of Excess Distributions of Trusts Applicable to Taxable Years Beginning on Or After January 1, 1969 § 1.665(e)-1A Preceding taxable year. (a) Definition—(1)...

  5. 26 CFR 1.665(e)-1A - Preceding taxable year.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 8 2011-04-01 2011-04-01 false Preceding taxable year. 1.665(e)-1A Section 1... (CONTINUED) INCOME TAXES (CONTINUED) Treatment of Excess Distributions of Trusts Applicable to Taxable Years Beginning on Or After January 1, 1969 § 1.665(e)-1A Preceding taxable year. (a) Definition—(1)...

  6. Numerical simulation of blood flow and interstitial fluid pressure in solid tumor microcirculation based on tumor-induced angiogenesis

    NASA Astrophysics Data System (ADS)

    Zhao, Gaiping; Wu, Jie; Xu, Shixiong; Collins, M. W.; Long, Quan; König, Carola S.; Jiang, Yuping; Wang, Jian; Padhani, A. R.

    2007-10-01

    A coupled intravascular transvascular interstitial fluid flow model is developed to study the distributions of blood flow and interstitial fluid pressure in solid tumor microcirculation based on a tumor-induced microvascular network. This is generated from a 2D nine-point discrete mathematical model of tumor angiogenesis and contains two parent vessels. Blood flow through the microvascular network and interstitial fluid flow in tumor tissues are performed by the extended Poiseuille’s law and Darcy’s law, respectively, transvascular flow is described by Starling’s law; effects of the vascular permeability and the interstitial hydraulic conductivity are also considered. The simulation results predict the heterogeneous blood supply, interstitial hypertension and low convection on the inside of the tumor, which are consistent with physiological observed facts. These results may provide beneficial information for anti-angiogenesis treatment of tumor and further clinical research.

  7. Effects of the Infusion of 4% or 20% Human Serum Albumin on the Skeletal Muscle Microcirculation in Endotoxemic Rats

    PubMed Central

    Damiani, Elisa; Ince, Can; Orlando, Fiorenza; Pierpaoli, Elisa; Cirioni, Oscar; Giacometti, Andrea; Mocchegiani, Federico; Pelaia, Paolo; Provinciali, Mauro; Donati, Abele

    2016-01-01

    Background Sepsis-induced microcirculatory alterations contribute to tissue hypoxia and organ dysfunction. In addition to its plasma volume expanding activity, human serum albumin (HSA) has anti-oxidant and anti-inflammatory properties and may have a protective role in the microcirculation during sepsis. The concentration of HSA infused may influence these effects. We compared the microcirculatory effects of the infusion of 4% and 20% HSA in an experimental model of sepsis. Methods Adult male Wistar rats were equipped with arterial and venous catheters and received an intravenous infusion of lipopolysaccharide (LPS, serotype O127:B8, 10 mg/kg over 30 minutes) or vehicle (SHAM, n = 6). Two hours later, endotoxemic animals were randomized to receive 10 mL/kg of either 4% HSA (LPS+4%HSA, n = 6), 20% HSA (LPS+20%HSA, n = 6) or 0.9% NaCl (LPS+0.9%NaCl, n = 6). No fluids were given to an additional 6 animals (LPS). Vessel density and perfusion were assessed in the skeletal muscle microcirculation with sidestream dark field videomicroscopy at baseline (t0), 2 hours after LPS injection (t1), after HSA infusion (t2) and 1 hour later (t3). The mean arterial pressure (MAP) and heart rate were recorded. Serum endothelin-1 was measured at t2. Results MAP was stable over time in all groups. The microcirculatory parameters were significantly altered in endotoxemic animals at t1. The infusion of both 4% and 20% HSA similarly increased the perfused vessel density and blood flow velocity and decreased the flow heterogeneity to control values. Microvascular perfusion was preserved in the LPS+20%HSA group at t3, whereas alterations reappeared in the LPS+4%HSA group. Conclusions In a rat model of normotensive endotoxemia, the infusion of 4% or 20% HSA produced a similar acute improvement in the microvascular perfusion in otherwise unresuscitated animals. PMID:26942605

  8. An intravital microscopic study of the hepatic microcirculation in cirrhotic mice models: relationship between fibrosis and angiogenesis.

    PubMed

    Vanheule, Eline; Geerts, Anja M; Van Huysse, Jacques; Schelfhout, Daphné; Praet, Marleen; Van Vlierberghe, Hans; De Vos, Martine; Colle, Isabelle

    2008-12-01

    This intravital fluorescence microscopy (IVFM) study validates cirrhotic mice models and describes the different intrahepatic alterations and the role of angiogenesis in the liver during genesis of cirrhosis. Cirrhosis was induced by subcutaneous injection of carbon tetrachloride (CCl(4)) and by common bile duct ligation (CBDL) in mice. Diameters of sinusoids, portal venules (PV), central venules (CV) and shunts were measured at different time points by IVFM. Thereafter, liver samples were taken for sirius red, CD31, Ki67, vascular endothelial growth factor (VEGF) and alpha-smooth muscle actin (alpha-SMA) evaluation by immunohistochemistry (IHC). In parallel with fibrogenesis, hepatic microcirculation was markedly disturbed in CCl(4) and CBDL mice with a significant decrease in sinusoidal diameter compared to control mice. In CCl(4) mice, CV were enlarged, with marked sinusoidal-free spaces around CV. In contrast, PV were enlarged in CBDL mice and bile lakes were observed. In both mice models, intrahepatic shunts developed gradually after induction. During genesis of cirrhosis using CD31 IHC we observed a progressive increase in the number of blood vessels within the fibrotic septa area and a progressively increase in staining by Ki67, VEGF and alpha-SMA of endothelial cells, hepatocytes and hepatic stellate cells respectively. In vivo study of the hepatic microcirculation demonstrated a totally disturbed intrahepatic architecture, with narrowing of sinusoids in both cirrhotic mice models. The diameters of CV and PV increased and large shunts, bypassing the sinusoids, were seen after both CCl(4) and CBDL induction. Thus present study shows that there is angiogenesis in the liver during cirrhogenesis, and this is probably due partially to an increased production of VEGF.

  9. Improvement of the microcirculation in the acute ischemic rat limb during intravenous infusion of drag-reducing polymers.

    PubMed

    Hu, Feng; Zha, Daogang; Du, Rongsheng; Chen, Xianghui; Zhou, Bingjie; Xiu, Jiancheng; Bin, Jianping; Liu, Yili

    2011-01-01

    Drag-reducing polymers (DRPs) are blood-soluble macromolecules that can increase blood flow and reduce vascular resistance. The purpose of the present study is to examine the effects of DRPs on microcirculation in rat hind limb during acute femoral artery occlusion. Two groups of 20 male Wistar rats were subjected to either hemodynamic measurement or contrast enhanced ultrasound (CEU) imaging during peripheral ischemia. Both groups were further subdivided into a DRP-treated group or a saline-treated group. Polyethylene oxide (PEO) was chosen as the test DRP, and rats were injected with either 10 ppm PEO solution or saline through the caudal vein at a constant rate of 5 ml/h for 20 min. Abdominal aortic flow, iliac artery pressure, iliac vein pressure, heart rate, carotid artery pressure and central venous pressure (CVP) were monitored, and vascular resistance was calculated by (iliac artery pressure-iliac vein pressure)/abdominal aortic blood flow. Flow perfusion and capillary volume of skeletal muscle were measured by CEU. During PEO infusion, abdominal aortic blood flow increased (p<0.001) and vascular resistance decreased (p<0.001) compared to rats that received saline during peripheral ischemia. There was no significant change in ischemic skeletal capillary volume (A) with DRP treatment (p>0.05), but red blood cell velocity (β) and capillary blood flow (A×β) increased significantly (p<0.05) during PEO infusion. In addition, A, β and A×β all increased (p<0.05) in the contralateral hind limb muscle. In contrast, PEO had no significant influence on heart rate, mean carotid artery blood pressure or CVP. Intravenous infusion of drag reducing polymers may offer a novel hydrodynamic approach for improving microcirculation during acute peripheral ischemia.

  10. Intracoronary Delivery of Human Mesenchymal/Stromal Stem Cells: Insights from Coronary Microcirculation Invasive Assessment in a Swine Model

    PubMed Central

    Fiarresga, António; Mata, Márcia F.; Cavaco-Gonçalves, Sandra; Selas, Mafalda; Simões, Irina N.; Oliveira, Eunice; Carrapiço, Belmira; Cardim, Nuno; Cabral, Joaquim M. S.; Ferreira, Rui Cruz; da Silva, Cláudia L.

    2015-01-01

    Background Mesenchymal stem/stromal cells have unique properties favorable to their use in clinical practice and have been studied for cardiac repair. However, these cells are larger than coronary microvessels and there is controversy about the risk of embolization and microinfarctions, which could jeopardize the safety and efficacy of intracoronary route for their delivery. The index of microcirculatory resistance (IMR) is an invasive method for quantitatively assessing the coronary microcirculation status. Objectives To examine heart microcirculation after intracoronary injection of mesenchymal stem/stromal cells with the index of microcirculatory resistance. Methods Healthy swine were randomized to receive by intracoronary route either 30x106 MSC or the same solution with no cells (1% human albumin/PBS) (placebo). Blinded operators took coronary pressure and flow measurements, prior to intracoronary infusion and at 5 and 30 minutes post-delivery. Coronary flow reserve (CFR) and the IMR were compared between groups. Results CFR and IMR were done with a variance within the 3 transit time measurements of 6% at rest and 11% at maximal hyperemia. After intracoronary infusion there were no significant differences in CFR. The IMR was significantly higher in MSC-injected animals (at 30 minutes, 14.2U vs. 8.8U, p = 0.02) and intragroup analysis showed a significant increase of 112% from baseline to 30 minutes after cell infusion, although no electrocardiographic changes or clinical deterioration were noted. Conclusion Overall, this study provides definitive evidence of microcirculatory disruption upon intracoronary administration of mesenchymal stem/stromal cells, in a large animal model closely resembling human cardiac physiology, function and anatomy. PMID:26479722

  11. In vivo reflectance-mode confocal microscopy assessments: impact of overweight on human skin microcirculation and histomorphology.

    PubMed

    Altintas, Ahmet A; Aust, Matthias C; Krämer, Robert; Vogt, Peter M; Altintas, Mehmet A

    2016-03-01

    Reflectance-mode confocal microscopy (RCM) enables in vivo assessment of the human skin. Impact of overweight on both human skin microcirculation and histomorphology has not been investigated in vivo. The purpose of this study is to evaluate both microcirculation and histomorphology in vivo in overweight. In 10 normotensive overweight nondiabetic individuals (OW-group, BMI 29.1 ± 2.7 kg/m(2)) and 10 age- and sex-matched healthy lean controls (CO-group, BMI 20.4 ± 1.9 kg/m(2)) the following parameters were evaluated using RCM: dermal blood cell flow (DBCF), density of dermal capillaries (DDC), epidermal thickness (ET), and epidermal cell size (ECS). DBCF was counted at 63.11 ± 4.14 cells/min in OW-group and at 51.06 ± 3.84 cells/min in CO-group (P < 0.05). DDC was reduced in OW-group (4.91 ± 0.39 capillaries/mm(2)) compared to the controls (6.02 ± 0.64 capillaries/mm(2), P < 0.05). Histometric evaluation of ET reveals thickening in OW-group compared to the CO-group (54.79 ± 4.25 μm versus 44.03 ± 3.11 μm, P < 0.05). ECS differed significantly (P < 0.05) in OW-group (821.3 ± 42.02 μm(2)) compared to the controls (772.6 ± 34.79 μm(2)). Inverse correlation of dermal capillary density and overweight point to reduced total tissue perfusion while positive related blood cell flow reveals vasodilatation. Increase of both ET and cell size indicates remodeling of cutaneous histomorphology, maybe as an early stage of adiposity-related skin condition. PMID:27020601

  12. In vivo reflectance-mode confocal microscopy assessments: impact of overweight on human skin microcirculation and histomorphology

    NASA Astrophysics Data System (ADS)

    Altintas, Ahmet A.; Aust, Matthias C.; Krämer, Robert; Vogt, Peter M.; Altintas, Mehmet A.

    2016-03-01

    Reflectance-mode confocal microscopy (RCM) enables in vivo assessment of the human skin. Impact of overweight on both human skin microcirculation and histomorphology has not been investigated in vivo. The purpose of this study is to evaluate both microcirculation and histomorphology in vivo in overweight. In 10 normotensive overweight nondiabetic individuals (OW-group, BMI 29.1±2.7 kg/m2) and 10 age- and sex-matched healthy lean controls (CO-group, BMI 20.4±1.9 kg/m2) the following parameters were evaluated using RCM: dermal blood cell flow (DBCF), density of dermal capillaries (DDC), epidermal thickness (ET), and epidermal cell size (ECS). DBCF was counted at 63.11±4.14 cells/min in OW-group and at 51.06±3.84 cells/min in CO-group (P<0.05). DDC was reduced in OW-group (4.91±0.39 capillaries/mm2) compared to the controls (6.02±0.64 capillaries/mm2, P<0.05). Histometric evaluation of ET reveals thickening in OW-group compared to the CO-group (54.79±4.25 μm versus 44.03±3.11 μm, P<0.05). ECS differed significantly (P<0.05) in OW-group (821.3±42.02 μm2) compared to the controls (772.6±34.79 μm2). Inverse correlation of dermal capillary density and overweight point to reduced total tissue perfusion while positive related blood cell flow reveals vasodilatation. Increase of both ET and cell size indicates remodeling of cutaneous histomorphology, maybe as an early stage of adiposity-related skin condition.

  13. The margination propensity of spherical particles for vascular targeting in the microcirculation.

    PubMed

    Gentile, Francesco; Curcio, Antonio; Indolfi, Ciro; Ferrari, Mauro; Decuzzi, Paolo

    2008-01-01

    The propensity of circulating particles to drift laterally towards the vessel walls (margination) in the microcirculation has been experimentally studied using a parallel plate flow chamber. Fluorescent polystyrene particles, with a relative density to water of just 50 g/cm3comparable with that of liposomal or polymeric nanoparticles used in drug delivery and bio-imaging, have been used with a diameter spanning over three order of magnitudes from 50 nm up to 10 mum. The number n approximately s MathType@MTEF@5@5@+=feaagaart1ev2aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacPC6xNi=xH8viVGI8Gi=hEeeu0xXdbba9frFj0xb9qqpG0dXdb9aspeI8k8fiI+fsY=rqGqVepae9pg0db9vqaiVgFr0xfr=xfr=xc9adbaqaaeGaciGaaiaabeqaaeqabiWaaaGcbaGafmOvayLbaGaadaWgaaWcbaGaem4Camhabeaaaaa@2EB4@ of particles marginating per unit surface have been measured through confocal fluorescent microscopy for a horizontal chamber, and the corresponding total volume V approximately s MathType@MTEF@5@5@+=feaagaart1ev2aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacPC6xNi=xH8viVGI8Gi=hEeeu0xXdbba9frFj0xb9qqpG0dXdb9aspeI8k8fiI+fsY=rqGqVepae9pg0db9vqaiVgFr0xfr=xfr=xc9adbaqaaeGaciGaaiaabeqaaeqabiWaaaGcbaGafmOvayLbaGaadaWgaaWcbaGaem4Camhabeaaaaa@2EB4@ of particles has been calculated. Scaling laws have been derived as a function of the particle diameter d. In horizontal capillaries, margination is mainly due to the gravitational force for particles with d > 200 nm and V approximately s MathType@MTEF@5@5@+=feaagaart1ev2aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacPC6xNi=xH8viVGI8Gi=hEeeu0xXdbba9frFj0xb9qqpG0dXdb9aspeI8k8fiI+fsY=rqGqVepae9pg0db9vqaiVgFr0xfr=xfr=xc9adbaqaaeGaciGaaiaabeqaaeqabiWaaaGcbaGafmOvayLbaGaadaWgaaWcbaGaem4Camhabeaaaaa@2EB4@ increases with d4; whereas for smaller particles V approximately s MathType@MTEF@5@5@+=feaagaart1ev2aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacPC6xNi=xH8viVGI8Gi=hEeeu0xXdbba9frFj0xb9qqpG0dXdb9aspe

  14. [The influence of intravenous laser therapy on prostaglandin E2 and F2-alpha dynamics and the state of microcirculation in the patients presenting with gastroesophageal reflux disease].

    PubMed

    Burduli, N M; Tadtaeva, D Ia

    2012-01-01

    The objective of the present work was to study the influence of low-frequency laser radiation on the levels of prostaglandins E2 and F2-alpha and characteristics of microcirculation in the patients suffering from gastroesophageal reflux disease (GERD). A total of 112 patients at the age from 19 to 79 years presenting with GERD were examined. 78 of them were given the complete 10-day course of intravenous laser therapy based on a Matriks-VLOK ("Matriks", Russia) therapeutic laser set emitting in the continuous mode at a wavelength of 0.405 mcm with the radiation power 1-11.5 mW at the output of the main lightguide. The characteristics of interest were determined before and after the treatment. It was shown that laser irradiation resulted in the elevation of pro-inflammatory prostaglandin levels and the improvement of parameters of microcirculation. PMID:23373291

  15. Precedency control and other semantic integrity issues in a workbench database

    NASA Technical Reports Server (NTRS)

    Dampney, C. N. G.

    1983-01-01

    Most database systems model the current state of a system of real world discrete and simple entities together with their relationships. By examining instead a database system that is a workbench and models more complicated entities, a fresh perspective is gained. Specifically, semantic integrity is analysed. Four aspects distinct from physical integrity are identified, namely - access, failure, concurrency and precedency. Access control is shown to be the consequence of semantic interdependency between data and its matching semantic routines. Failure, concurrency precedency controls are concerned with preventing processes interfering with each other. Precedency is a new concept in the database context. It expresses a constraint between processes that act on the database. As processes create, update and delete entities they in general obey a partial ordering imposed by the semantics of their actions. Precedency control ensures that data remains consistent with respect to this partial order.

  16. Historical Uses of Meteoritic Metals as Precedent for Modern In-Situ Asteroid Mining

    NASA Astrophysics Data System (ADS)

    Krispin, D.; Mardon, A. A.; Fawcett, B. G.

    2016-08-01

    The strain on earth's resources of metal and the metallic density of meteorites mean that in situ asteroid mining is advisable. This has precedent: Use of meteoritic metal dates back to ancient times.

  17. 17 CFR 240.11a1-1(T) - Transactions yielding priority, parity, and precedence.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... section 11(a)(1) of the Act or specified in 17 CFR 240.11a1-4(T) shall be deemed to be revenue derived..., parity, and precedence. 240.11a1-1(T) Section 240.11a1-1(T) Commodity and Securities Exchanges SECURITIES... (rule 11a-1) § 240.11a1-1(T) Transactions yielding priority, parity, and precedence. (a) A...

  18. 17 CFR 240.11a1-1(T) - Transactions yielding priority, parity, and precedence.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... section 11(a)(1) of the Act or specified in 17 CFR 240.11a1-4(T) shall be deemed to be revenue derived..., parity, and precedence. 240.11a1-1(T) Section 240.11a1-1(T) Commodity and Securities Exchanges SECURITIES... (rule 11a-1) § 240.11a1-1(T) Transactions yielding priority, parity, and precedence. (a) A...

  19. 17 CFR 240.11a1-1(T) - Transactions yielding priority, parity, and precedence.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... section 11(a)(1) of the Act or specified in 17 CFR 240.11a1-4(T) shall be deemed to be revenue derived..., parity, and precedence. 240.11a1-1(T) Section 240.11a1-1(T) Commodity and Securities Exchanges SECURITIES... (rule 11a-1) § 240.11a1-1(T) Transactions yielding priority, parity, and precedence. (a) A...

  20. 17 CFR 240.11a1-1(T) - Transactions yielding priority, parity, and precedence.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... section 11(a)(1) of the Act or specified in 17 CFR 240.11a1-4(T) shall be deemed to be revenue derived..., parity, and precedence. 240.11a1-1(T) Section 240.11a1-1(T) Commodity and Securities Exchanges SECURITIES... (rule 11a-1) § 240.11a1-1(T) Transactions yielding priority, parity, and precedence. (a) A...

  1. 17 CFR 240.11a1-1(T) - Transactions yielding priority, parity, and precedence.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... section 11(a)(1) of the Act or specified in 17 CFR 240.11a1-4(T) shall be deemed to be revenue derived..., parity, and precedence. 240.11a1-1(T) Section 240.11a1-1(T) Commodity and Securities Exchanges SECURITIES... (rule 11a-1) § 240.11a1-1(T) Transactions yielding priority, parity, and precedence. (a) A...

  2. Detectability of contrast agents for video-rate confocal reflectance microscopy of skin and microcirculation in vivo

    NASA Astrophysics Data System (ADS)

    Rajadhyaksha, Milind M.; Gonzalez, Salvador

    2003-06-01

    The lack of structure-specific contrast limits the usefulness of confocal reflectance microscopy to morphologic investigations at the cellular- and nuclear-level in human and animal skin in vivo. Morphologic and functional imaging at specific organelle- and ultrastructure-levels will require contrast agents that may be used and detected in vivo. High-resolution confocal reflectance imaging is based on the detection of singly back-scattered photons, where contrast is provided by variations in the refractive indices of microstructures. We carried out a quantitative Mie back-scatter analysis and imaging experiments to understand signal detectability of reflectance contrast agents for visualizing human skin and animal microcirculation. When imaging at video-rate with illumination of 10 milliwatts at 1064 nm, we detect 100-104 photons/pixel from the epidermis to dermis, relative to a background of 100 photons; this provides a signal-to-noise ratio of 3-40 and signal-to-background of 1-100. Organelles of size (d) 0.1-1.0 μm with refractive indices (n) of 1.34-1.45 (relative to n=1.34 for epidermis, n=1.38 for dermis) back-scatter 10-104 photons/pixel. Exogenous contrast agents such as liposomes (n=1.41, d=0.7 μm) and polystyrene microspheres (d=0.2-1.0 μm, n=1.57; 100-105 photons/pixel) are detectable and they strongly enhance the contrast of microcirculation in the dermis of Sprague-Dawley rats. Topically applied 5% acetic acid causes the intra-nuclear 30-100 nm-thin chromatin filaments to condense into 1-5 μm-thick strands, increasing back-scattered signal from 100 to 104 photons/pixels, making the nuclei appear bright and easily detectable in basal cell cancers. Such analyses provide a basis for optimizing confocal microscope design for detectability of contrast agents in vivo.

  3. Bicyclic monoterpene diols stimulate release of nitric oxide from skin cells, increase microcirculation, and elevate skin temperature.

    PubMed

    Brown, David A; Canning, Matthew T; Nay, Stephanie L; Pena, Arely V; Yarosh, Daniel B

    2006-08-01

    Bicyclic monoterpene diols (BMTd) stimulate nitric oxide synthesis in melanoma and neuronal cells, representing cell types arising from embryonic neural crest tissue. This study shows that an equimolar mixture of the BMTd's 2,3-cis/exo-pinanediol and 2,3-cis/exo-camphanediol stimulates nitric oxide synthesis in epithelial cells of the skin, specifically normal human epidermal keratinocytes (NHEK) and normal human microvascular endothelial cells (HMVEC). A 1 mM mixture increased nitric oxide 3-fold in HMVEC in the first 24 h after treatment, and a 2 mM mixture produced an equivalent increase in NHEK. We hypothesized that an increase in nitric oxide in skin would lead to an increase in microcirculation, thereby increasing skin temperature. We found that twice daily application of 1mM BMTd lotion significantly increased arm skin temperature by 0.5 degrees C in 14 days compared to placebo, while a 2 mM mixture significantly increased skin temperature by 0.3 degrees C in 7 days (P < or = 0.05; ANOVA). A single application of a 2 mM BMTd mixture applied 30 min before a 30 min cold challenge (6 degrees C), maintained facial skin temperature 1.4 degrees C above untreated control sites (P < or = 0.05; ANOVA). We also tested whether BMTd treatment would benefit people with dark circles under their eyes. Twenty-six panelists with dark undereye circles completed 2-week, twice daily application of a lotion containing the 1mM mixture to one eye while the other eye was untreated. Seven of 26 subjects showed a reduction of darkness of undereye circles (P < or = 0.05; paired t test). Application of 2 mM BMTd lotion to lips resulted in a significant increase in their redness, as measured by the erythema index (P < or = 0.05; ANOVA). These results show that a mixture of BMTd's increases nitric oxide, and application to skin increases microcirculation and skin temperature.

  4. The Natural History of Kidney Graft Cortical Microcirculation Determined by Real-Time Contrast-Enhanced Sonography (RT-CES)

    PubMed Central

    Jiménez, Carlos; López, María Ovidia; Ros, Amaia; Aguilar, Ana; Menendez, David; Rivas, Begoña; Santana, María José; Vaca, Marco Antonio; Escuin, Fernando; Madero, Rosario; Selgas, Rafael

    2016-01-01

    Background Kidney transplantation is the therapy of choice for end-stage kidney disease. Graft’s life span is shorter than expected due in part to the delayed diagnosis of various complications, specifically those related to silent progression. It is recognized that serum creatinine levels and proteinuria are poor markers of mild kidney lesions, which results in delayed clinical information. There are many investigation looking for early markers of graft damage. Decreasing kidney graft cortical microcirculation has been related to poor prognosis in kidney transplantation. Cortical capillary blood flow (CCBF) can be measured by real-time contrast-enhanced sonography (RT-CES). Our aim was to describe the natural history of CCBF over time under diverse conditions of kidney transplantation, to explore the influence of donor conditions and recipient events, and to determine the capacity of CCBF for predicting renal function in medium term. Patients and Methods RT-CES was performed in 79 consecutive kidney transplant recipients during the first year under regular clinical practice. Cortical capillary blood flow was measured. Clinical variables were analyzed. The influence of CCBF has been determined by univariate and multivariate analysis using mixed regression models based on sequential measurements for each patient over time. We used a first-order autoregression model as the structure of the covariation between measures. The post-hoc comparisons were considered using the Bonferroni correction. Results The CCBF values varied significantly over the study periods and were significantly lower at 48 h and day 7. Brain-death donor age and CCBF levels showed an inverse relationship (r: -0.62, p<0.001). Living donors showed higher mean CCBF levels than brain-death donors at each point in the study. These significant differences persisted at month 12 (54.5 ± 28.2 vs 33.7 ± 30 dB/sec, living vs brain-death donor, respectively, p = 0.004) despite similar serum creatinine

  5. Bioelectric and microcirculation cutaneous sensors for the study of vigilance and emotional response during tasks and tests.

    PubMed

    Rada, H; Dittmar, A; Delhomme, G; Collet, C; Roure, R; Vernet-Maury, E; Priez, A

    1995-01-01

    Bioelectronic phenomena related to the activity of the Autonomic Nervous System (ANS) activity mainly take place in the deep part of the brain where they are difficult to record. The hand skin, being richly innervated by sympathetic efferent fibres, offers an interface from which relevant ANS-related signals can be recorded. Two non-invasive bioelectronic measurements (skin resistance and potential) reflecting the activity of the ANS were performed at the skin surface. These measurements were complemented by thermovascular (skin microcirculation and skin temperature) and cardiorespiratory (instantaneous heart rate and instantaneous respiratory frequency) measurements. The bioelectric measurements were performed using noninvasive Ag/AgCl electrodes. Non-metallic NASICON (Na Super Ionic Conductor) electrodes were tested and compared with traditional electrodes for the optimization of bioelectric measurements. Signal analysis and data processing was accomplished by means of original indices on a specially designed PC-based software. The methodology was used to evaluate vigilance level, mental workload, and emotional response during tasks (sporting activity, mental calculation, olfactive stimuli) and in critical situations (car crash avoidance). PMID:7734122

  6. The Effects of Acupuncture on Cerebral and Muscular Microcirculation: A Systematic Review of Near-Infrared Spectroscopy Studies

    PubMed Central

    Lo, Ming-Yu; Ong, Ming Wei; Chen, Wei-Yu; Sun, Wei-Zen; Lin, Jaung-Geng

    2015-01-01

    Acupuncture produces physiological effects via stimulating acupoints, proximal or distal to the region of effect. Near-infrared spectroscopy (NIRS) noninvasively measures tissue-level hemodynamics in real time. We review the literature investigating the effect of acupuncture on muscular and/or cerebral microcirculation. As the basis, we queried PubMed in June 2014 for articles mentioning both acupuncture and NIRS in title/abstract. The reviewed papers investigated either cerebral (n = 11) or muscular hemodynamics (n = 5) and, based on STRICTA for reporting acupuncture methodology, were overall poor in quality. Acupuncture was found to influence regional oxygen saturation in cerebral and muscular tissue. The cortical response in healthy subjects varied across studies. For subjects with stroke or cerebrovascular dementia, findings suggest that acupuncture may modulate dysfunction in cerebral autoregulation. The muscular response to pressure techniques was more intense than that to needling or laser. Probe proximity could impact measurement sensitivity. No one study simultaneously investigated the direct and remote responses. Research utilizing NIRS to investigate the hemodynamics of acupuncture presently lacks in scope and quality. Improved designs, for example, placebo-controlled, randomized trials, and standardized intervention reporting will raise study quality. Exploiting NIRS in clinical settings, such as stroke, migraine, or other pain conditions, is worthwhile. PMID:26221180

  7. Effects of Local Pancreatic Renin-Angiotensin System on the Microcirculation of Rat with Severe Acute Pancreatitis.

    PubMed

    Pan, Zhijian; Feng, Ling; Long, Haocheng; Wang, Hui; Feng, Jiarui; Chen, Feixiang

    2015-07-01

    Severe acute pancreatitis (SAP) is normally related to multiorgan dysfunction and local complications. Studies have found that local pancreatic renin-angiotensin system (RAS) was significantly upregulated in drug-induced SAP. The present study aimed to investigate the effects of angiotensin II receptors inhibitor valsartan on dual role of RAS in SAP in a rat model and to elucidate the underlying mechanisms. 3.8% sodium taurocholate (1 ml/kg) was injected to the pancreatic capsule in order for pancreatitis induction. Rats in the sham group were injected with normal saline in identical locations. We also investigated the regulation of experimentally induced SAP on local RAS expression in the pancreas through determination of the activities of serum amylase, lipase and myeloperoxidase, histological and biochemical analysis, radioimmunoassay, fluorescence quantitative PCR and Western blot analysis. The results indicated that valsartan could effectively suppress the local RAS to protect against experimental acute pancreatitis through inhibition of microcirculation disturbances and inflammation. The results suggest that pancreatic RAS plays a critical role in the regulation of pancreatic functions and demonstrates application potential as AT1 receptor antagonists. Moreover, other RAS inhibitors could be a new therapeutic target in acute pancreatitis. PMID:26170733

  8. Synergistic effects of high blood cholesterol and hypertension on leukocyte and platelet recruitment in the cerebral microcirculation.

    PubMed

    Rodrigues, Stephen F; Almeida-Paula, Lidiana D; Granger, Daniel N

    2014-04-01

    Hypertension or hypercholesterolemia can induce a proinflammatory and prothrombogenic phenotype in the microcirculation of the brain; however, less is known about how the combination of these risk factors affects the vasculature. We recently reported that a moderate (60%) increase in plasma cholesterol blunts the recruitment of leukocytes and platelets in the cerebral microvessels elicited by hypertension. In this study, we examined whether larger increments in blood cholesterol (4-fold) exerts a similar modulating influence on the vasculature in the presence of hypertension. Apolipoprotein E-knockout mice with deoxycorticosterone acetate salt-induced hypertension were placed on a high-cholesterol diet and exhibited exaggerated leukocyte and platelet adhesion responses in cerebral microvessels. Intermittent feeding (every fourth day) with high-cholesterol diet yielded similar phenotypic changes in the vasculature. Once the mice were placed on high-cholesterol diet, 4 days on normal diet (ND) were needed to revert to a normal vascular phenotype. Angiotensin II type 1 receptors and reactive oxygen species seem to contribute to the vascular responses induced by hypercholesterolemia and hypertension. Our findings indicate that the combination of hypertension and large increases in plasma cholesterol concentration results in a severe, but reversible, inflammatory and thrombogenic phenotype in the cerebral microvasculature.

  9. Comparison of Two Algorithms for Analysis of Perfusion Computed Tomography Data for Evaluation of Cerebral Microcirculation in Chronic Subdural Hematoma.

    PubMed

    Trofimov, Alexey O; Kalentiev, George; Voennov, Oleg; Yuriev, Michail; Agarkova, Darya; Trofimova, Svetlana; Bragin, Denis E

    2016-01-01

    The aim of this work was comparison of two algorithms of perfusion computed tomography (PCT) data analysis for evaluation of cerebral microcirculation in the perifocal zone of chronic subdural hematoma (CSDH). Twenty patients with CSDH after polytrauma were included in the study. The same PCT data were assessed quantitatively in cortical brain region beneath the CSDH (zone 1), and in the corresponding contralateral brain hemisphere (zone 2) without and with the use of perfusion calculation mode excluding vascular pixel 'Remote Vessels' (RV); 1st and 2nd analysis method, respectively. Comparison with normal values for perfusion indices in the zone 1 in the 1st analysis method showed a significant (p < 0.01) increase in CBV and CBF, and no significant increase in MTT and TTP. Use of the RV mode (2nd analysis method) showed no statistically reliable change of perfusion parameters in the microcirculatory blood flow of the 2nd zone. Maintenance of microcirculatory blood flow perfusion reflects the preservation of cerebral blood flow autoregulation in patients with CSDH. PMID:27526170

  10. High quality optical microangiography of ocular microcirculation and measurement of total retinal blood flow in mouse eye

    NASA Astrophysics Data System (ADS)

    Zhi, Zhongwei; Yin, Xin; Dziennis, Suzan; Alpers, Charles E.; Wang, Ruikang K.

    2013-03-01

    Visualization and measurement of retinal blood flow (RBF) is important to the diagnosis and management of different eye diseases, including diabetic retinopathy. Optical microangiography (OMAG) is developed for generating 3D dynamic microcirculation image and later refined into ultra-high sensitive OMAG (UHS-OMAG) for true capillary vessels imaging. Here, we present the application of OMAG imaging technique for visualization of depth-resolved vascular network within retina and choroid as well as measurement of total retinal blood flow in mice. A fast speed spectral domain OCT imaging system at 820nm with a line scan rate of 140 kHz was developed to image mouse posterior eye. By applying UHS-OMAG scanning protocol and processing algorithm, we achieved true capillary level imaging of retina and choroid vasculature in mouse eye. The vascular pattern within different retinal layers and choroid was presented. An en face Doppler OCT approach [1] without knowing Doppler angle was adopted for the measurement of total retinal blood flow. The axial blood flow velocity is measured in an en face plane by raster scanning and the flow is calculated by integrating over the vessel area of the central retinal artery.

  11. Subtle exchange model of flow depended on the blood cell shape to enhance the micro-circulation in capillary

    NASA Astrophysics Data System (ADS)

    Chan, Iatneng

    2012-02-01

    In general the exchange of gases or other material in capillary system is conceptualized by the diffusion effect. But in this model, we investigate a micro-flow pattern by simulation and computation on a micro-exchange model in which the blood cell is a considered factor, especially on its shape. It shows that the cell benefits the circulation while it is moving in the capillary. In the study, the flow detail near the cell surface is mathematically analyzed, such that the Navier-Stokes equations are applied and the viscous factor is also briefly considered. For having a driven force to the motion of micro-circulation, a breathing mode is suggested to approximately compute on the flow rate in the blood capillary during the transfer of cell. The rate is also used to estimate the enhancement to the circulation in additional to the outcome of diffusion. Moreover in the research, the shape change of capillary wall under pressure influence is another element in the beginning calculation for the effect in the assistance to cell motion.

  12. The Effects of Acupuncture on Cerebral and Muscular Microcirculation: A Systematic Review of Near-Infrared Spectroscopy Studies.

    PubMed

    Lo, Ming-Yu; Ong, Ming Wei; Chen, Wei-Yu; Sun, Wei-Zen; Lin, Jaung-Geng

    2015-01-01

    Acupuncture produces physiological effects via stimulating acupoints, proximal or distal to the region of effect. Near-infrared spectroscopy (NIRS) noninvasively measures tissue-level hemodynamics in real time. We review the literature investigating the effect of acupuncture on muscular and/or cerebral microcirculation. As the basis, we queried PubMed in June 2014 for articles mentioning both acupuncture and NIRS in title/abstract. The reviewed papers investigated either cerebral (n = 11) or muscular hemodynamics (n = 5) and, based on STRICTA for reporting acupuncture methodology, were overall poor in quality. Acupuncture was found to influence regional oxygen saturation in cerebral and muscular tissue. The cortical response in healthy subjects varied across studies. For subjects with stroke or cerebrovascular dementia, findings suggest that acupuncture may modulate dysfunction in cerebral autoregulation. The muscular response to pressure techniques was more intense than that to needling or laser. Probe proximity could impact measurement sensitivity. No one study simultaneously investigated the direct and remote responses. Research utilizing NIRS to investigate the hemodynamics of acupuncture presently lacks in scope and quality. Improved designs, for example, placebo-controlled, randomized trials, and standardized intervention reporting will raise study quality. Exploiting NIRS in clinical settings, such as stroke, migraine, or other pain conditions, is worthwhile. PMID:26221180

  13. Kickoff to Conflict: A Sequence Analysis of Intra-State Conflict-Preceding Event Structures

    PubMed Central

    D'Orazio, Vito; Yonamine, James E.

    2015-01-01

    While many studies have suggested or assumed that the periods preceding the onset of intra-state conflict are similar across time and space, few have empirically tested this proposition. Using the Integrated Crisis Early Warning System's domestic event data in Asia from 1998–2010, we subject this proposition to empirical analysis. We code the similarity of government-rebel interactions in sequences preceding the onset of intra-state conflict to those preceding further periods of peace using three different metrics: Euclidean, Levenshtein, and mutual information. These scores are then used as predictors in a bivariate logistic regression to forecast whether we are likely to observe conflict in neither, one, or both of the states. We find that our model accurately classifies cases where both sequences precede peace, but struggles to distinguish between cases in which one sequence escalates to conflict and where both sequences escalate to conflict. These findings empirically suggest that generalizable patterns exist between event sequences that precede peace. PMID:25951105

  14. Outcome after autologous stem cell transplantation for multiple myeloma in patients with preceding plasma cell disorders.

    PubMed

    Kumar, Shaji K; Dingli, David; Lacy, Martha Q; Dispenzieri, Angela; Hayman, Suzanne R; Buadi, Francis K; Rajkumar, S Vincent; Litzow, Mark R; Gertz, Morie A

    2008-04-01

    A third of patients with multiple myeloma (MM) have a preceding diagnosis of plasma cell proliferative disorder (PCPD), mostly monoclonal gammopathy of undetermined significance (MGUS), smoldering MM (SMM) or plasmacytoma. While autologous stem cell transplantation (SCT) improves survival in MM, it is not clear if patients with preceding PCPD have a different outcome. We identified 151 patients with preceding PCPD from among 804 patients undergoing SCT, and their outcomes were compared. The response rates, including complete responses, were similar between the groups. Patients with a preceding diagnosis of MGUS had longer time to progression (TTP; 27.5 months vs. 17.2 months, P = 0.01), and longer overall survival (OS) from transplant (80.2 months vs. 48.3 months, P = 0.03) compared to those with de novo myeloma. However no differences were seen among those with a preceding diagnosis of SMM or plasmacytoma in terms of TTP or OS from transplant when compared to those with de novo myeloma. Multivariate analysis indicated that the presence of MGUS prior to myeloma was prognostic for post-transplant relapse independent of other known risk factors. Patients with pre-existing MGUS prior to myeloma diagnosis have a better outcome following HDT, reflecting more indolent disease and a favourable biology than those presenting with de novo myeloma. PMID:18318761

  15. A novel car following model considering average speed of preceding vehicles group

    NASA Astrophysics Data System (ADS)

    Sun, Dihua; Kang, Yirong; Yang, Shuhong

    2015-10-01

    In this paper, a new car following model is presented by considering the average speed effect of preceding vehicles group in cyber-physical systems (CPS) environment. The effect of this new consideration upon the stability of traffic flow is examined through linear stability analysis. A modified Korteweg-de Vries (mKdV) equation was derived via nonlinear analysis to describe the propagating behavior of traffic density wave near the critical point. Good agreement between the simulation and the analytical results shows that average speed of preceding vehicles group leads to the stabilization of traffic systems, and thus can efficiently suppress the emergence of traffic jamming.

  16. Progress through precedent: Going where no helicopter simulator has gone before

    NASA Technical Reports Server (NTRS)

    Adams, Richard J.

    1992-01-01

    Helicopter simulators have been approved by means of special exemption; there are no FAA standards for simulators used in training or airmen Certification checking. The fixed-wing industry provides a precedent which can be used for expediting implementation of helicopter simulators. The analysis in this paper is founded on the experience with that precedent and is driven by a clear definition of helicopter user needs for (1) improved training at lower cost, (2) more comprehensive emergency training at lower risk, (3) increased fidelity of transition and instrument training compared with low-cost aircraft alternatives, and (4) certification credit for improved simulator training.

  17. Relationship Type and Sexual Precedence: Their Associations With Characteristics of Sexual Assault Perpetrators and Incidents

    PubMed Central

    Wegner, Rhiana; Pierce, Jennifer; Abbey, Antonia

    2015-01-01

    Although most sexual assaults are committed by men who know their victims, few researchers have considered how characteristics of perpetrators and incidents differ depending on the victim–perpetrator relationship. This study addresses this gap with a community sample of 204 men who reported committing a sexually aggressive act in an audio computer-assisted self-interview. 2 (Relationship Type: Committed vs. Casual) × 2 (Sexual Precedence: Yes vs. No) ANOVAs revealed significant main effects of relationship type and sexual precedence associated with individual difference and incident characteristics. These findings demonstrate the importance of developing theories and prevention programs tailored for different relationship contexts. PMID:25288595

  18. The involvement of ATP-sensitive potassium channels in β2-adrenoceptor agonist-induced vasodilatation on rat diaphragmatic microcirculation

    PubMed Central

    Chang, Han-Yu

    1997-01-01

    The effects of glibenclamide (GLB), a blocker of ATP-sensitive potassium (KATP) channels, on diaphragmatic microcirculation in male Sprague-Dawley rats were assessed under basal conditions and after β2-adrenoceptor-agonist stimulation. In addition, forskolin was used to bypass β-adrenoceptors and GTP-binding proteins (G-protein) to explore the possible mechanism of GLB effects. For comparison, the relationships between KATP channel activity and cyclic GMP-mediated vasodilator responses to acetylcholine (ACh) and sodium nitroprusside (SNP) were also assessed. Male Sprague-Dawley rats were anaesthetized with urethane and mechanically ventilated. The left hemi-diaphragm of each rat was prepared and microvascular blood flow (QLDF) was recorded with laser-Doppler flowmetry during continuous superfusion with bicarbonate-buffered, prewarmed Ringer solution. The drugs were topically applied to the surface of the hemi-diaphragm. Salbutamol (0.32–32 μM), terbutaline (0.32 μM–0.32 μM) and forskolin (0.32–10 μM) each elicited a concentration-dependent increase in QLDF. Baseline microvascular blood flow was unaffected by a 30 min suffusion of 1 μM GLB (295±51 mV vs 325±62 mV, P=0.738). The vasodilator response elicited by salbutamol (0.32 μM, 1 μM and 3.2 μM), was significantly attenuated by a 30 min superfusion with 1 μM GLB; this salbutamol-induced vasodilatation was mediated via an interaction with β-adrenoceptor receptors, as in other experiments it was greatly inhibited by 30-min superfusion with propranolol (10 μM). Similarly, following 30-min superfusion with GLB (1 μM), the terbutaline (1 μM, 3.2 μM and 10 μM)-induced vasodilator response was almost abolished and the vasodilator responses induced by incremental concentrations of forskolin (0.32 μM, 1 μM and 3.2 μM) were also significantly attenuated. Cromakalim (1.5 μM, 3 μM and 3.2 μM) produced an increase of QLDF in a dose-dependent manner

  19. Pretreatment Evaluation of Microcirculation by Dynamic Contrast-Enhanced Magnetic Resonance Imaging Predicts Survival in Primary Rectal Cancer Patients

    SciTech Connect

    DeVries, Alexander Friedrich; Piringer, Gudrun; Kremser, Christian; Judmaier, Werner; Saely, Christoph Hubert; Lukas, Peter; Öfner, Dietmar

    2014-12-01

    Purpose: To investigate the prognostic value of the perfusion index (PI), a microcirculatory parameter estimated from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), which integrates information on both flow and permeability, to predict overall survival and disease-free survival in patients with primary rectal cancer. Methods and Materials: A total of 83 patients with stage cT3 rectal cancer requiring neoadjuvant chemoradiation were investigated with DCE-MRI before start of therapy. Contrast-enhanced dynamic T{sub 1} mapping was obtained, and a simple data analysis strategy based on the calculation of the maximum slope of the tissue concentration–time curve divided by the maximum of the arterial input function was used as a measure of tumor microcirculation (PI), which integrates information on both flow and permeability. Results: In 39 patients (47.0%), T downstaging (ypT0-2) was observed. During a mean (±SD) follow-up period of 71 ± 29 months, 58 patients (69.9%) survived, and disease-free survival was achieved in 45 patients (54.2%). The mean PI (PImean) averaged over the group of nonresponders was significantly higher than for responders. Additionally, higher PImean in age- and gender-adjusted analyses was strongly predictive of therapy nonresponse. Most importantly, PImean strongly and significantly predicted disease-free survival (unadjusted hazard ratio [HR], 1.85 [ 95% confidence interval, 1.35-2.54; P<.001)]; HR adjusted for age and sex, 1.81 [1.30-2.51]; P<.001) as well as overall survival (unadjusted HR 1.42 [1.02-1.99], P=.040; HR adjusted for age and sex, 1.43 [1.03-1.98]; P=.034). Conclusions: This analysis identifies PImean as a novel biomarker that is predictive for therapy response, disease-free survival, and overall survival in patients with primary locally advanced rectal cancer.

  20. [The state of microcirculation in the middle ear structures at different stages of the treatment of the patients presenting with chronic otitis media].

    PubMed

    Belokopytova, E Iu; Fedoseev, V I; Pleshkov, V A

    2014-01-01

    The present work was designed to study dynamics of blood circulation in the tympanic membrane and tympanic cavity mucosa of 92 patients (105 ears) presenting with otosclerosis, adhesive non-perforative otitis media, and different stages of chronic suppurative otitis media. Normal characteristics of tympanic microcirculation were determined in 22 otologically healthy volunteers (30 ears). Laser Doppler flowmetry with the use of a specially designed probe (the outer diameter: 1.9 mm) was applied. The results of Doppler flowmetry varied in ontologically healthy subjects. The same circulation parameters in the vessels of the microcirculatory bed of the postero-superior quadrant of the tympanic membrane in the patients presenting with chronic suppurative otitis media at the stage of remission, otosclerosis, and adhesive non-perforative otitis media did not significantly differ from those of otologically healthy subjects. The blood flow was shown to increase in the tympanic membrane of the majority of the patients during the postoperative period (within 2nd to 4th weeks after types I-III tympanoplasty); thereafter, it either decreased or returned to the baseline level by weeks 6-8. Four months after the improvement of perfusion parameters of tympanic cavity mucosa and the arrest of exacerbation of mesotympanitis, characteristics of microcirculation in tympanic cavity mucosa were not significantly different from those of the patients with adhesive perforative otitis media. It is concluded that laser Doppler flowmetry may be used as an objective non-invasive technique for the study of microcirculation in the tympanic membrane and tympanic cavity mucosa.

  1. Prognostic impact of coronary microcirculation abnormalities in systemic sclerosis: a prospective study to evaluate the role of non-invasive tests

    PubMed Central

    2013-01-01

    Introduction Microcirculation dysfunction is a typical feature of systemic sclerosis (SSc) and represents the earliest abnormality of primary myocardial involvement. We assessed coronary microcirculation status by combining two functional tests in SSc patients and estimating its impact on disease outcome. Methods Forty-one SSc patients, asymptomatic for coronary artery disease, were tested for coronary flow velocity reserve (CFR) by transthoracic-echo-Doppler with adenosine infusion (A-TTE) and for left ventricular wall motion abnormalities (WMA) by dobutamine stress echocardiography (DSE). Myocardial multi-detector computed tomography (MDCT) enabled the presence of epicardial stenosis, which could interfere with the accuracy of the tests, to be excluded. Patient survival rate was assessed over a 6.7- ± 3.5-year follow-up. Results Nineteen out of 41 (46%) SSc patients had a reduced CFR (≤2.5) and in 16/41 (39%) a WMA was observed during DSE. Furthermore, 13/41 (32%) patients showed pathological CFR and WMA. An inverse correlation between wall motion score index (WMSI) during DSE and CFR value (r = -0.57, P <0.0001) was observed; in addition, CFR was significantly reduced (2.21 ± 0.38) in patients with WMA as compared to those without (2.94 ± 0.60) (P <0.0001). In 12 patients with abnormal DSE, MDCT was used to exclude macrovasculopathy. During a 6.7- ± 3.5-year follow-up seven patients with abnormal coronary functional tests died of disease-related causes, compared to only one patient with normal tests. Conclusions A-TTE and DSE tests are useful tools to detect non-invasively pre-clinical microcirculation abnormalities in SSc patients; moreover, abnormal CFR and WMA might be related to a worse disease outcome suggesting a prognostic value of these tests, similar to other myocardial diseases. PMID:23302110

  2. Postwar Era Precedents and the Ambivalent Quest for International Students at the University of Florida

    ERIC Educational Resources Information Center

    Terzian, Sevan G.; Osborne, Leigh Ann

    2006-01-01

    The number of international students studying at U.S. institutions of higher education in the 2003-2004 academic year dropped for the first time in more than three decades. New visa restrictions and international tensions in the wake of September 11, 2001, have been cited as central factors. This article identifies historical precedents from the…

  3. Effect of Personnel Change on Supreme Court Use of Precedent in Freedom of Expression Cases.

    ERIC Educational Resources Information Center

    Schwartz, Thomas A.; Warrick, Kathleen

    To test the findings of a 1981 study, which concluded that the Supreme Court of Chief Justice Warren Burger has attempted to reverse the liberal policies of the court presided over by Earl Warren by adopting a policy of ignoring precedent, a second study duplicated the earlier study's general research design, except that it focused on freedom of…

  4. Building ensemble representations: How the shape of preceding distractor distributions affects visual search.

    PubMed

    Chetverikov, Andrey; Campana, Gianluca; Kristjánsson, Árni

    2016-08-01

    Perception allows us to extract information about regularities in the environment. Observers can quickly determine summary statistics of a group of objects and detect outliers. The existing body of research has, however, not revealed how such ensemble representations develop over time. Moreover, the correspondence between the physical distribution of features in the external world and their potential internal representation as a probability density function (PDF) by the visual system is still unknown. Here, for the first time we demonstrate that such internal PDFs are built during visual search and show how they can be assessed with repetition and role-reversal effects. Using singleton search for an oddly oriented target line among differently oriented distractors (a priming of pop-out paradigm), we test how different properties of previously observed distractor distributions (mean, variability, and shape) influence search times. Our results indicate that observers learn properties of distractor distributions over and above mean and variance; in fact, response times also depend on the shape of the preceding distractor distribution. Response times decrease as a function of target distance from the mean of preceding Gaussian distractor distributions, and the decrease is steeper when preceding distributions have small standard deviations. When preceding distributions are uniform, however, this decrease in response times can be described by a two-piece function corresponding to the uniform distribution PDF. Moreover, following skewed distributions response times function is skewed in accordance with the skew in distributions. Indeed, internal PDFs seem to be specifically tuned to the observed feature distribution. PMID:27232163

  5. Applying PRECEDE-PROCEED to Develop an Intuitive Eating Nondieting Approach to Weight Management Pilot Program

    ERIC Educational Resources Information Center

    Cole, Renee E.; Horacek, Tanya

    2009-01-01

    Objective: To describe the use of a consolidated version of the PRECEDE-PROCEED participatory program planning model to collaboratively design an intuitive eating program with Fort Drum military spouses tailored to their readiness to reject the dieting mentality and make healthful lifestyle modifications. Design: A consolidated version of…

  6. Building ensemble representations: How the shape of preceding distractor distributions affects visual search.

    PubMed

    Chetverikov, Andrey; Campana, Gianluca; Kristjánsson, Árni

    2016-08-01

    Perception allows us to extract information about regularities in the environment. Observers can quickly determine summary statistics of a group of objects and detect outliers. The existing body of research has, however, not revealed how such ensemble representations develop over time. Moreover, the correspondence between the physical distribution of features in the external world and their potential internal representation as a probability density function (PDF) by the visual system is still unknown. Here, for the first time we demonstrate that such internal PDFs are built during visual search and show how they can be assessed with repetition and role-reversal effects. Using singleton search for an oddly oriented target line among differently oriented distractors (a priming of pop-out paradigm), we test how different properties of previously observed distractor distributions (mean, variability, and shape) influence search times. Our results indicate that observers learn properties of distractor distributions over and above mean and variance; in fact, response times also depend on the shape of the preceding distractor distribution. Response times decrease as a function of target distance from the mean of preceding Gaussian distractor distributions, and the decrease is steeper when preceding distributions have small standard deviations. When preceding distributions are uniform, however, this decrease in response times can be described by a two-piece function corresponding to the uniform distribution PDF. Moreover, following skewed distributions response times function is skewed in accordance with the skew in distributions. Indeed, internal PDFs seem to be specifically tuned to the observed feature distribution.

  7. Effects of Age and Hearing Loss on Gap Detection and the Precedence Effect: Broadband Stimuli

    ERIC Educational Resources Information Center

    Roberts, Richard A.; Lister, Jennifer J.

    2004-01-01

    Older listeners with normal-hearing sensitivity and impaired-hearing sensitivity often demonstrate poorer-than-normal performance on tasks of speech understanding in noise and reverberation. Deficits in temporal resolution and in the precedence effect may underlie this difficulty. Temporal resolution is often studied by means of a gap-detection…

  8. 29 CFR 548.306 - Average earnings for year or quarter year preceding the current quarter.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Average earnings for year or quarter year preceding the... PAY Interpretations Authorized Basic Rates § 548.306 Average earnings for year or quarter year... hour for each workweek equal to the average hourly remuneration of the employee for employment...

  9. Female Genital Cutting: Applying the PRECEDE-PROCEED Model To Understand the Incentives for the Practice.

    ERIC Educational Resources Information Center

    Dabbagh, Leila

    2002-01-01

    Reviews the practice of female circumcision and the significance of considering social, cultural, economic, and educational opportunities available to females in developing countries when creating intervention programs to help end this practice. The PRECEDE-PROCEED model is a tool that can assess various elements present in a girls' life that…

  10. Metabolic and Signaling Alterations in Dystrophin-Deficient Hearts Precede Overt Cardiomyopathy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The cytoskeletal protein dystrophin has been implicated in hereditary and acquired forms of cardiomyopathy. However, much remains to be learned about the role of dystrophin in the heart. We hypothesized that the dystrophin-deficient heart displays early alterations in energy metabolism that precede ...

  11. Using the PRECEDE Model for Causal Analysis of Bulimic Tendencies among Elite Women Swimmers.

    ERIC Educational Resources Information Center

    Benson, RoseAnn; Taub, Diane E.

    1993-01-01

    Describes a study of weight control techniques and bulimic tendencies among elite female participants in an Olympic Swimming Selection Meet. Results showed concern with thinness, body dissatisfaction, and unhealthy eating, dieting, and weight loss patterns among participants. Discusses the explanatory power of the PRECEDE model. (SM)

  12. Ancient Uses of Meteoritic Metals as Precedent for Modern In-Situ Asteroid Mining

    NASA Astrophysics Data System (ADS)

    Mardon, Austin A.; Fawcett, Brett; Krispin, Daniel

    2016-05-01

    Given the strain on earth's supply of metal and the meteoritic content of meteorites, a prudent course would be to pursue in-situ asteroid mining of meteors for metal. There is a precedent for this going back to ancient Egypt; humans have always used the meteoritic content of meteorites to fashion everything from weapons to cosmetics.

  13. 5 CFR 870.801 - Order of precedence and payment of benefits.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... specific person or persons to receive life insurance benefits upon the death of an insured individual... the individual(s) entitled to receive Basic life insurance benefits under the statutory order of... SERVICE REGULATIONS (CONTINUED) FEDERAL EMPLOYEES' GROUP LIFE INSURANCE PROGRAM Order of Precedence...

  14. 29 CFR 548.306 - Average earnings for year or quarter year preceding the current quarter.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 3 2012-07-01 2012-07-01 false Average earnings for year or quarter year preceding the current quarter. 548.306 Section 548.306 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS AUTHORIZATION OF ESTABLISHED BASIC RATES FOR COMPUTING OVERTIME PAY Interpretations Authorized Basic Rates...

  15. Reduced Activation of Left Orbitofrontal Cortex Precedes Blocked Vocalization: A Magnetoencephalographic Study

    ERIC Educational Resources Information Center

    Sowman, Paul F.; Crain, Stephen; Harrison, Elisabeth; Johnson, Blake W.

    2012-01-01

    While stuttering is known to be characterized by anomalous brain activations during speech, very little data is available describing brain activations during stuttering. To our knowledge there are no reports describing brain activations that precede blocking. In this case report we present magnetoencephalographic data from a person who stutters…

  16. Strategy Precedes Operational Effectiveness: Aligning High Graduation Rankings with Competitive Graduation Grade Point Averages

    ERIC Educational Resources Information Center

    Apprey, Maurice; Bassett, Kimberley C.; Preston-Grimes, Patrice; Lewis, Dion W.; Wood, Beverly

    2014-01-01

    Two pivotal and interconnected claims are addressed in this article. First, strategy precedes program effectiveness. Second, graduation rates and rankings are insufficient in any account of academic progress for African American students. In this article, graduation is regarded as the floor and not the ceiling, as it were. The ideal situation in…

  17. 7 CFR 1980.454 - Conditions precedent to issuance of the Loan Note Guarantee.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 14 2012-01-01 2012-01-01 false Conditions precedent to issuance of the Loan Note Guarantee. 1980.454 Section 1980.454 Agriculture Regulations of the Department of Agriculture (Continued... AGENCY, DEPARTMENT OF AGRICULTURE (CONTINUED) PROGRAM REGULATIONS (CONTINUED) GENERAL Business...

  18. 7 CFR 1980.454 - Conditions precedent to issuance of the Loan Note Guarantee.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 14 2010-01-01 2009-01-01 true Conditions precedent to issuance of the Loan Note Guarantee. 1980.454 Section 1980.454 Agriculture Regulations of the Department of Agriculture (Continued... AGENCY, DEPARTMENT OF AGRICULTURE (CONTINUED) PROGRAM REGULATIONS (CONTINUED) GENERAL Business...

  19. 7 CFR 1980.454 - Conditions precedent to issuance of the Loan Note Guarantee.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 14 2013-01-01 2013-01-01 false Conditions precedent to issuance of the Loan Note Guarantee. 1980.454 Section 1980.454 Agriculture Regulations of the Department of Agriculture (Continued... AGENCY, DEPARTMENT OF AGRICULTURE (CONTINUED) PROGRAM REGULATIONS (CONTINUED) GENERAL Business...

  20. 7 CFR 1980.454 - Conditions precedent to issuance of the Loan Note Guarantee.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 14 2011-01-01 2011-01-01 false Conditions precedent to issuance of the Loan Note Guarantee. 1980.454 Section 1980.454 Agriculture Regulations of the Department of Agriculture (Continued... AGENCY, DEPARTMENT OF AGRICULTURE (CONTINUED) PROGRAM REGULATIONS (CONTINUED) GENERAL Business...

  1. 7 CFR 1980.454 - Conditions precedent to issuance of the Loan Note Guarantee.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 14 2014-01-01 2014-01-01 false Conditions precedent to issuance of the Loan Note Guarantee. 1980.454 Section 1980.454 Agriculture Regulations of the Department of Agriculture (Continued... AGENCY, DEPARTMENT OF AGRICULTURE (CONTINUED) PROGRAM REGULATIONS (CONTINUED) GENERAL Business...

  2. The Existentialist Reality of Educational Production Functions (Their Existence Has Preceded Their Essence).

    ERIC Educational Resources Information Center

    Michelson, Stephan

    This publication is a discussion of the concept of an educational production function, a mathematical formulation of the relationship between inputs and outputs in education. A description of how a production function can direct decision making toward economic efficiency precedes a theoretical discussion of the nature of actual estimation. Several…

  3. Parafoveal Processing of Word n + 2 during Reading: Do the Preceding Words Matter?

    ERIC Educational Resources Information Center

    Angele, Bernhard; Rayner, Keith

    2011-01-01

    We used the boundary paradigm (Rayner, 1975) to test two hypotheses that might explain why no conclusive evidence has been found for the existence of n + 2 preprocessing effects. In Experiment 1, we tested whether parafoveal processing of the second word to the right of fixation (n + 2) takes place only when the preceding word (n + 1) is very…

  4. Application of the PRECEDE Model to Understanding Mental Health Promoting Behaviors in Hong Kong

    ERIC Educational Resources Information Center

    Mo, Phoenix K. H.; Mak, Winnie W. S.

    2008-01-01

    The burdens related to mental illness have been increasingly recognized in many countries. Nevertheless, research in positive mental health behaviors remains scarce. This study utilizes the Predisposing, Reinforcing, and Enabling Causes in Education Diagnosis and Evaluation (PRECEDE) model to identify factors associated with mental health…

  5. Height changes in the epicentral region preceding the January 17, 1994 Northridge earthquake

    USGS Publications Warehouse

    Castle, Robert O.; Packard, Robert F.; Dinitz, Laura B.

    2000-01-01

    Analysis of the results of repeated levelings through the epicentral region of the Mw 6.7, 1994 Northridge earthquake has disclosed the occurrence of differential uplift in this area that preceded the earthquake. Although the distribution of the relevant vertical-control data is somewhat sparse, in both space and time, those data that we have recovered indicate that this uplift exceeded 0.10 m and peaked 20-25 km west of the 1994 epicenter. While our data also indicate that this deformational event must have occurred during the period 1978-1989, evidence based on the character and magnitude of misclosures developed from 1987 and 1989 surveys argue that the deformation occurred largely during the period 1987-1989. The preseismic vertical-displacement field that preceded the Northridge earthquake is similar in form and, less certainly, magnitude to that which preceded the Mw 6.7, 1971 San Fernando earthquake; other possible, but less significant southern California analogues include the deformational events that preceded the Mw 5.3, 1973 Point Mugu and Mw 5.9, 1987 Whittier Narrows earthquakes. The small but growing number of recognized aseismic deformational episodes that preceded small to moderate magnitude earthquakes in southern California suggests that the deployment of the dense array of continuously recording GPS receivers planned for southern California can be expected to detect and more accurately describe such events than was heretofore possible. Moreover, if the relation between the duration of these deformational anomalies and the magnitudes of any ensuing earthquakes can be much more clearly established, the near perfect temporal control on position afforded by GPS suggests that we may be on the threshold of a realistic earthquake warning system.

  6. Global precedence, spatial frequency channels, and the statistics of natural images.

    PubMed

    Hughes, H C; Nozawa, G; Kitterle, F

    1996-01-01

    A great deal of evidence suggests that early in processing, retinal images are filtered by parallel, spatial frequency selective channels. We attempt to incorporate this view of early vision with the principle of global precedence, which holds that Gestalt-like processes sensitive to global image configurations tend to dominate local feature processing in human pattern perception. Global precedence is inferred from the pattern of reaction times observed when visual patterns contain multiple cues at different levels of spatial scale. Specifically, it is frequently observed that global processing times are largely unaffected by conflicting local cues, but local processing times are substantially lengthened by conflicting global cues. The asymmetry of these effects suggests the dominant role of global configurations. Since global spatial information is effectively represented by low spatial frequencies, global precedence potentially implies a low frequency dominance. The thesis is that low spatial frequencies tend to be available before information carried by higher frequency bands, producing a coarse-to-fine temporal order in visual spatial perception. It is suggested that a variety of factors contribute to the "prior entry" of low frequency information, including the high contrast gain of the magnocellular pathway, the amplitude spectra typical of natural images, and inhibitory interactions between the parallel frequency-tuned channels. Evidence suggesting a close relationship between global precedence and spatial frequency channels is provided by observations that the essential features of the global precedence effect are obtained using patterns consisting of low and high frequency sinusoids. The hypothesis that these asymmetric interference effects are due to interactions between parallel spatial channels is supported by an analysis of reaction times (RTs), which shows that RTs to redundant low and high frequency cues produce less facilitation than predictions

  7. Development of a Comprehensive Model of the Apparent Viscosity of Blood for Simulations of the Microcirculation in Rat Spinotrapezius Muscle Fascia

    NASA Astrophysics Data System (ADS)

    Jacobitz, Frank; Porterfield, Colin; Engebrecht, Cheryn; Metzger, Ian

    2007-11-01

    A more comprehensive model for the apparent viscosity of blood is proposed and applied to simulations of the microcirculation in rat spinotrapezius muscle fascia. At the microcirculatory level, the apparent viscosity of blood depends on the local vessel diameter, hematocrit, and shear rate. Starting with the apparent viscosity model proposed by Pries, Secomb, Gaehtgens, and Gross (Circulation Research, 67, 826-834, 1990), describing the effect of vessel diameter and hematocrit on the apparent viscosity, and using experimental data presented by Lipowsky, Usami, and Chien (Microvascular Research, 19, 297-319, 1980), describing the shear rate dependence of apparent viscosity, a more comprehensive model is developed. This model is applied to simulations of the microcirculation in rat spinotrapezius muscle fascia. The simulations use realistic vessel topology for the microvasculature, reconstructed from microscope images of tissue samples, and consider passive and active vessel properties. The numerical method is based on a Hagen-Poiseuille balance in the microvessels and a sparse matrix solver is used to obtain the solution. It was found, for example, that the distribution of vessel length follows a log-normal law. The distribution of hematocrit, however, was found to be approximately normal.

  8. Impact of different antithrombotics on the microcirculation and viability of perforator-based ischaemic skin flaps in a small animal model

    PubMed Central

    Fichter, Andreas M.; Ritschl, Lucas M.; Robitzky, Luisa K.; Wagenpfeil, Stefan; Mitchell, David A.; Wolff, Klaus-Dietrich; Mücke, Thomas

    2016-01-01

    The effects of antithrombotic drugs on random and free flap survival have been investigated in the past, but the experimental and clinical results are not in agreement. A perforator-based critical ischaemia model was used to evaluate the effects of different perioperatively administered pharmaceutical agents on tissue ischaemia and to assess the potential additional haemorheological or vasodilative effects of antithrombotics on flap microcirculation. Combined laser Doppler flowmetry and remission spectroscopy revealed an increase in certain microcirculation parameters in most groups in comparison with saline controls, and these changes correlated with flap survival. Clopidogrel and hirudin significantly improved the amount of viable flap tissue in comparison with controls, while unfractioned heparin had a negative effect on flap survival. Low molecular weight heparin, aspirin, pentoxifylline, and hydroxyethyl starch had no impact on the amount of viable flap tissue. A higher complication rate was observed in all experimental groups, but only clopidogrel had a negative impact on the flap viability. Our results add to the body of evidence supporting the conclusion that perioperative antithrombotic treatment improves flap survival. Clopidogrel and hirudin are effective pharmacological agents that significantly increased the viability of perforator-based skin flaps in rats, but at a higher risk of postoperative bleeding. PMID:27767060

  9. A new in vivo model using a dorsal skinfold chamber to investigate microcirculation and angiogenesis in diabetic wounds

    PubMed Central

    Langer, Stefan; Beescho, Christian; Ring, Andrej; Dorfmann, Olivia; Steinau, Hans Ulrich; Spindler, Nick

    2016-01-01

    the skinfold chamber, it was possible to analyze and quantify microangiopathical changes which are essential for a better understanding of the pathophysiology of disturbed wound healing. Research in microcirculation is important to display perfusion in wounds versus healthy tissue. Using our model, we were able to compare wound healing in diabetic and healthy mice. We were also able to objectively analyze perfusion in wound edges and compare microcirculatory parameters. This model may be well suited to augment different therapeutic options. PMID:26955508

  10. Changes in Oxygenation Levels Precede Changes in Amplitude of the EEG in Premature Infants.

    PubMed

    Caicedo, Alexander; Thewissen, Liesbeth; Smits, Anne; Naulaers, Gunnar; Allegaert, Karel; Van Huffel, Sabine

    2016-01-01

    Brain function is supported by an appropriate balance between the metabolic demand and the supply of nutrients and oxygen. However, the physiological principles behind the regulation of brain metabolism and demand in premature infants are unknown. Some studies found that changes in hemodynamic variables in this population precede changes in EEG activity; however, these studies only used descriptive statistics. This paper describes the relationship between changes in cerebral oxygenation, assessed by means of near-infrared spectroscopy (NIRS), and changes in EEG, using mathematical methods taken from information dynamics. In a cohort of 35 neonates subjected to sedation by propofol, we quantified the direction of information transfer between brain oxygenation and EEG. The results obtained indicate that, as reported in other studies, changes in NIRS are likely to precede changes in EEG activity. PMID:27526136

  11. A Decrease in Temperature and Humidity Precedes Human Rhinovirus Infections in a Cold Climate.

    PubMed

    Ikäheimo, Tiina M; Jaakkola, Kari; Jokelainen, Jari; Saukkoriipi, Annika; Roivainen, Merja; Juvonen, Raija; Vainio, Olli; Jaakkola, Jouni J K

    2016-01-01

    Both temperature and humidity may independently or jointly contribute to the risk of human rhinovirus (HRV) infections, either through altered survival and spread of viruses in the environment or due to changes in host susceptibility. This study examined the relationship between short-term variations in temperature and humidity and the risk of HRV infections in a subarctic climate. We conducted a case-crossover study among conscripts (n = 892) seeking medical attention due to respiratory symptoms during their military training and identified 147 HRV cases by real-time PCR. An average temperature, a decline in daily ambient temperature and absolute humidity (AH) during the three preceding days of the onset (hazard period) and two reference periods (a week prior and after the onset) were obtained. The average daily temperature preceding HRV infections was -9.9 ± 4.9 °C and the average AH was 2.2 ± 0.9 g/m³. An average (odds ratios (OR) 1.07 (95% confidence interval (CI) 1.00-1.15)) and maximal (OR 1.08 (1.01-1.17)) change in temperature increased the risk of HRV infections by 8% per 1 °C decrease. An average (OR 1.20 (CI 1.03-1.40)) and maximal decrease (OR 1.13 (CI 0.96-1.34)) in AH increased the risk of HRV infection by 13% and 20% per 0.5 g/m³ decrease. A higher average temperature during the three preceding days was positively associated with HRV infections (OR 1.07 (CI 1.00-1.15)). A decrease rather than low temperature and humidity per se during the preceding few days increases the risk of HRV infections in a cold climate. The information is applicable to populations residing in cold climates for appropriate personal protection and prevention of adverse health effects. PMID:27598190

  12. A Decrease in Temperature and Humidity Precedes Human Rhinovirus Infections in a Cold Climate.

    PubMed

    Ikäheimo, Tiina M; Jaakkola, Kari; Jokelainen, Jari; Saukkoriipi, Annika; Roivainen, Merja; Juvonen, Raija; Vainio, Olli; Jaakkola, Jouni J K

    2016-01-01

    Both temperature and humidity may independently or jointly contribute to the risk of human rhinovirus (HRV) infections, either through altered survival and spread of viruses in the environment or due to changes in host susceptibility. This study examined the relationship between short-term variations in temperature and humidity and the risk of HRV infections in a subarctic climate. We conducted a case-crossover study among conscripts (n = 892) seeking medical attention due to respiratory symptoms during their military training and identified 147 HRV cases by real-time PCR. An average temperature, a decline in daily ambient temperature and absolute humidity (AH) during the three preceding days of the onset (hazard period) and two reference periods (a week prior and after the onset) were obtained. The average daily temperature preceding HRV infections was -9.9 ± 4.9 °C and the average AH was 2.2 ± 0.9 g/m³. An average (odds ratios (OR) 1.07 (95% confidence interval (CI) 1.00-1.15)) and maximal (OR 1.08 (1.01-1.17)) change in temperature increased the risk of HRV infections by 8% per 1 °C decrease. An average (OR 1.20 (CI 1.03-1.40)) and maximal decrease (OR 1.13 (CI 0.96-1.34)) in AH increased the risk of HRV infection by 13% and 20% per 0.5 g/m³ decrease. A higher average temperature during the three preceding days was positively associated with HRV infections (OR 1.07 (CI 1.00-1.15)). A decrease rather than low temperature and humidity per se during the preceding few days increases the risk of HRV infections in a cold climate. The information is applicable to populations residing in cold climates for appropriate personal protection and prevention of adverse health effects.

  13. Organizational precedents for ownership and management of decentralized renewable-energy systems

    SciTech Connect

    Meunier, R.; Silversmith, J.A.

    1981-03-01

    Three existing organizational types that meet the decentralization criteria of local consumer ownership and control - cooperatives, Rural Electric Cooperatives, and municipal utilities - are examined. These three organizational precedents are analyzed in terms of their histories, structures, legal powers, sources of capital, and social and political aspects. Examples of related experiments with renewable energy technologies are given, and inferences are drawn regarding the organizations' suitability as vehicles for future implementation of decentralized renewable energy systems.

  14. Legal precedents regarding use and defensibility of risk assessment in Federal transportation of SNF and HLW

    SciTech Connect

    Bentz, E.J. Jr.; Bentz, C.B.; O`Hora, T.D.; Chen, S.Y.

    1997-04-01

    Risk assessment has become an increasingly important and essential tool in support of Federal decision-making regarding the handling, storage, disposal, and transportation of spent nuclear fuel (SNF) and high-level radioactive waste (HLW). This paper analyzes the current statutory and regulatory framework and related legal precedents with regard to SNF and HLW transportation. The authors identify key scientific and technical issues regarding the use and defensibility of risk assessment in Federal decision-making regarding anticipated shipments.

  15. Chromatin structural changes precede replication in initiated replicons during inhibition of DNA elongation

    SciTech Connect

    D'Anna, J.A.; Grady, D.L.; Tobey, R.A.

    1988-01-01

    Partial inhibition of replicative DNA synthesis by hydroxyurea or other agents produces changes in the composition and structure of bulk chromatin. We have begun to investigate the structural changes in specific regions of the genome using synchronized cells and cloned genomic probes. Current results indicate changes in chromatin structure occur preferentially in initiated replicons and can precede the replication fork during inhibition of DNA elongation. 4 refs., 2 figs.

  16. Effects of Age and Hearing Loss on Gap Detection and the Precedence Effect: Narrow-Band Stimuli

    ERIC Educational Resources Information Center

    Lister, Jennifer J.; Roberts, Richard A.

    2005-01-01

    Deficits in temporal resolution and/or the precedence effect may underlie part of the speech understanding difficulties experienced by older listeners in degraded acoustic environments. In a previous investigation, R. Roberts and J. Lister (2004) identified a positive correlation between measures of temporal resolution and the precedence effect,…

  17. Quiet Periods in Edge Turbulence Preceding the L-H Transition in NSTX

    SciTech Connect

    Zweben, S; Hager, R; Hallatschek, K; Kaye, S M; Munsat, T; Poli, F M; Roquemore, A L; Sechrest, Y

    2010-04-26

    This paper describes the first observations in NSTX of ‘quiet periods’ in the edge turbulence preceding the L-H transition, as diagnosed by the GPI diagnostic near the outer midplane separatrix. During these quiet periods the GPI Dα light emission pattern was transiently similar to that seen during Hmode, i.e. with a relatively small fraction of the GPI light emission located outside the separatrix. These quiet periods had a frequency of ~3 kHz for at least 30 msec before the L-H transition, and were correlated with changes in the direction of the local poloidal velocity. The GPI turbulence images were also analyzed to obtain an estimate for the dimensionless poloidal shearing S =(dVp/dr)(Lr/Lp)τ. The values of S were strongly modulated by the quiet periods, but not otherwise varying for at least 30 msec preceding the L-H transition. Since neither the quiet periods nor the shear flow increased significantly immediately preceding the L-H transition, neither of these appears to be the trigger for this transition, at least for these cases in NSTX.

  18. The Response of Durum Wheat to the Preceding Crop in a Mediterranean Environment

    PubMed Central

    Ercoli, Laura; Masoni, Alessandro; Pampana, Silvia; Mariotti, Marco; Arduini, Iduna

    2014-01-01

    Crop sequence is an important management practice that may affect durum wheat (Triticum durum Desf.) production. Field research was conducted in 2007-2008 and 2008-2009 seasons in a rain-fed cold Mediterranean environment to examine the impact of the preceding crops alfalfa (Medicago sativa L.), maize (Zea mays L.), sunflower (Helianthus annuus L.), and bread wheat (Triticum aestivum L.) on yield and N uptake of four durum wheat varieties. The response of grain yield of durum wheat to the preceding crop was high in 2007-2008 and was absent in the 2008-2009 season, because of the heavy rainfall that negatively impacted establishment, vegetative growth, and grain yield of durum wheat due to waterlogging. In the first season, durum wheat grain yield was highest following alfalfa, and was 33% lower following wheat. The yield increase of durum wheat following alfalfa was mainly due to an increased number of spikes per unit area and number of kernels per spike, while the yield decrease following wheat was mainly due to a reduction of spike number per unit area. Variety growth habit and performance did not affect the response to preceding crop and varieties ranked in the order Levante > Saragolla = Svevo > Normanno. PMID:25401153

  19. Classifying EEG Signals Preceding Right Hand, Left Hand, Tongue, and Right Foot Movements and Motor Imageries

    PubMed Central

    Morash, Valerie; Bai, Ou; Furlani, Stephen; Lin, Peter; Hallett, Mark

    2008-01-01

    Objective To use the neural signals preceding movement and motor imagery to predict which of four movements/motor imageries is about to occur, and to access this utility for brain-computer interface (BCI) applications. Methods Eight naive subjects performed or kinesthetically imagined four movements while electroencephalogram (EEG) was recorded from 29 channels over sensorimotor areas. The task was instructed with a specific stimulus (S1) and performed at a second stimulus (S2). A classifier was trained and tested offline at differentiating the EEG signals from movement/imagery preparation (the 1.5 seconds preceding movement/imagery execution). Results Accuracy of movement/imagery preparation classification varied between subjects. The system preferentially selected event related (de)synchronization (ERD/ERS) signals for classification, and high accuracies were associated with classifications that relied heavily on the ERD/ERS to discriminate movement/imagery planning. Conclusions The ERD/ERS preceding movement and motor imagery can be used to predict which of four movements/imageries is about to occur. Prediction accuracy depends on this signal’s accessibility. Significance The ERD/ERS is the most specific pre-movement/imagery signal to the movement/imagery about to be performed. PMID:18845473

  20. Two sources of meaning in infant communication: preceding action contexts and act-accompanying characteristics.

    PubMed

    Liszkowski, Ulf

    2014-09-19

    How do infants communicate before they have acquired a language? This paper supports the hypothesis that infants possess social-cognitive skills that run deeper than language alone, enabling them to understand others and make themselves understood. I suggested that infants, like adults, use two sources of extralinguistic information to communicate meaningfully and react to and express communicative intentions appropriately. In support, a review of relevant experiments demonstrates, first, that infants use information from preceding shared activities to tailor their comprehension and production of communication. Second, a series of novel findings from our laboratory shows that in the absence of distinguishing information from preceding routines or activities, infants use accompanying characteristics (such as prosody and posture) that mark communicative intentions to extract and transmit meaning. Findings reveal that before infants begin to speak they communicate in meaningful ways by binding preceding and simultaneous multisensory information to a communicative act. These skills are not only a precursor to language, but also an outcome of social-cognitive development and social experience in the first year of life. PMID:25092662

  1. Measuring Algorithm for the Distance to a Preceding Vehicle on Curve Road Using On-Board Monocular Camera

    NASA Astrophysics Data System (ADS)

    Yu, Guizhen; Zhou, Bin; Wang, Yunpeng; Wun, Xinkai; Wang, Pengcheng

    2015-12-01

    Due to more severe challenges of traffic safety problems, the Advanced Driver Assistance Systems (ADAS) has received widespread attention. Measuring the distance to a preceding vehicle is important for ADAS. However, the existing algorithm focuses more on straight road sections than on curve measurements. In this paper, we present a novel measuring algorithm for the distance to a preceding vehicle on a curve road using on-board monocular camera. Firstly, the characteristics of driving on the curve road is analyzed and the recognition of the preceding vehicle road area is proposed. Then, the vehicle detection and distance measuring algorithms are investigated. We have verified these algorithms on real road driving. The experimental results show that this method proposed in the paper can detect the preceding vehicle on curve roads and accurately calculate the longitudinal distance and horizontal distance to the preceding vehicle.

  2. The microcirculation in shock

    PubMed Central

    Matheson, N. A.

    1969-01-01

    Some aspects of blood fluidity in hypoperfusion with particular reference to the important role of the red cell are discussed. Changes in different organ beds and the internal fluidity of the red cell, which is of obvious importance in capillary flow are not considered. It is not certain to what extent the phenomena discussed are critical factors in morbidity and mortality in shock because of paucity of objective data but there are good reasons for assuming them to be of importance and for directing treatment towards their correction. The properties of Dextran 40 applicable to the therapy of disordered blood fluidity are described. PMID:5343581

  3. Protective effect of heme oxygenase-1 on Wistar rats with heart failure through the inhibition of inflammation and amelioration of intestinal microcirculation

    PubMed Central

    Zhang, Li; Gan, Zhuo-Kun; Han, Li-Na; Wang, Hao; Bai, Jie; Tan, Guo-Juan; Li, Xiao-Xia; Xu, Ya-Ping; Zhou, Yu; Gong, Mei-Liang; Lin, Mo-Si; Han, Xiao-Yang

    2015-01-01

    Background Myocardial infarction (MI) has likely contributed to the increased prevalence of heart failure (HF). As a result of reduced cardiac function, splanchnic blood flow decreases, causing ischemia in villi and damage to the intestinal barrier. The induction of heme oxygenase-1 (HO-1) could prevent, or lessen the effects of stress and inflammation. Thus, the effect and mechanism thereof of HO-1 on the intestines of rats with HF was investigated. Methods Male Wistar rats with heart failure through ligation of the left coronary artery were identified with an left ventricular ejection fraction of < 45% through echocardiography and then divided into various experimental groups based on the type of peritoneal injection they received [MI: saline; MI + Cobalt protoporphyrin (CoPP): CoPP solution; and MI + Tin mesoporphyrin IX dichloride (SnMP): SnMP solution]. The control group was comprised of rats without coronary ligation. Echocardiography was performed before ligation for a baseline and eight weeks after ligation in order to evaluate the cardiac function of the rats. The bacterial translocation (BT) incidence, mesenteric microcirculation, amount of endotoxins in the vein serum, ileum levels of HO-1, carbon oxide (CO), nitric oxide (NO), interleukin (IL)-10, tumour necrosis factor-α (TNF-α), and the ileum morphology were determined eight weeks after the operation. Results The rats receiving MI + CoPP injections exhibited a recovery in cardiac function, an amelioration of mesenteric microcirculation and change in morphology, a lower BT incidence, a reduction in serum and ileac NO and TNF-α levels, and an elevation in ileac HO-1, CO, and interleukin-10 (IL-10) levels compared to the MI group (P < 0.05). The rats that received the MI + SnMP injections exhibited results inverse to the MI (P < 0.05) group. Conclusions HO-1 exerted a protective effect on the intestines of rats with HF by inhibiting the inflammation and amelioration of microcirculation through the CO

  4. Decline in NAD(P)H autofluorescence precedes apoptotic cell death from chemotherapy

    NASA Astrophysics Data System (ADS)

    Toms, Steven A.; Muhammad, Osman; Jackson, Heather; Lin, Wei-Chiang

    2005-11-01

    OBJECTIVE: Optical spectroscopic tools exist that allow open surgical and minimally invasive assays of intrinsic tissue optics. Optical detection of cellular and tissue viability may offer a minimally invasive way to assess tumor responsiveness to chemotherapies. We report on an optical spectroscopic change that precedes apoptotic cell death and appears related to NAD(P)H autofluorescence. METHODS: The cell lines SW 480 and U87-MG were grown in culture and treated with cisplatin 100 μg/ml and tamoxifen 10 μM, respectively. Fluorescence spectroscopy at 355 nm excitation and 460 nm emission were collected. MTS assays were used to determine cell viability. Cell lysates were analyzed for NAD(P)H concentrations by mass spectroscopy. RESULTS: Autoflourescence at 355 nm excitation and 460 nm emission declines markedly despite normalization for cell number and total protein concentration after treatment with tamoxifen or cisplatin. The autofluorescence drop precedes the loss of cell viability as measured by MTS assay. For example, the relative viability of the U87-MG cell treated with tamoxifen at hours 0, 8, 12 and 24 of treatment was 100 +/- 6, 85 +/- 6, 53 +/- 9 and 0 +/- 3. The relative fluorescence at the same time points were 100 +/- 2, 57 +/- 6, 47 +/- 3, and 0 +/- 1. TUNNEL assays confirm that cell death is via apoptosis. The key cellular fluorophore at these wavelengths is NAD(P)H. Mass spectroscopic analysis of cell lysates at these time points reveals a drop in NAD(P)H concentrations that is parallel to the loss of fluorescence signal. CONCLUSIONS: NAD(P)H autofluoresence decline precedes apoptotic cell death. This may allow the design of minimally invasive spectroscopic tools to monitor chemotherapeutic response.

  5. Behaviour of coconut mites preceding take-off to passive aerial dispersal.

    PubMed

    Melo, J W S; Lima, D B; Sabelis, M W; Pallini, A; Gondim, M G C

    2014-12-01

    For more than three decades the coconut mite Aceria guerreronis Keifer is one of the most important pests of coconut palms and has recently spread to many coconut production areas worldwide. Colonization of coconut palms is thought to arise from mites dispersing aerially after take-off from other plants within the same plantation or other plantations. The underlying dispersal behaviour of the mite at take-off, in the airborne state and after landing is largely unknown and this is essential to understand how they spread from tree to tree. In this article we studied whether take-off to aerial dispersal of coconut mites is preceded by characteristic behaviour, whether there is a correlation between the body position preceding aerial dispersal and the direction of the wind, and whether the substrate (outer surface of coconut bracts or epidermis) and the wind speed matter to the decision to take-off. We found that take-off can sometimes be preceded by a raised body stance, but more frequently take-off occurs while the mite is walking or resting on its substrate. Coconut mites that become airborne assumed a body stance that had no relation to the wind direction. Take-off was suppressed on a substrate providing food to coconut mites, but occurred significantly more frequently on the outer surface of coconut bracts than on the surface of the fruit. For both substrates, take-off frequency increased with wind speed. We conclude that coconut mites have at least some degree of control over take-off for aerial dispersal and that there is as yet no reason to infer that a raised body stance is necessary to become airborne.

  6. Gestalt perception and the decline of global precedence in older subjects.

    PubMed

    Staudinger, Markus R; Fink, Gereon R; Mackay, Clare E; Lux, Silke

    2011-01-01

    Our visual world is hierarchically organized. Hierarchical processing is frequently investigated using Navon figures (large letters made up of smaller ones). In young adults, many studies reported faster reaction times (RT) to target letters presented at the global level [i.e., global precedence (GP)]. Furthermore, an age-related decline of this GP has been reported. We tested whether deficits in perceptual grouping via Gestalt laws (Gestalt principles of Proximity and Continuity) might contribute to this decline. In a directed attention task with valid and invalid cues, 20 young (mean age 22) and 20 older (mean age 57) male subjects had to indicate whether a target letter appeared at the global or local level of a Navon figure. The number of local letters forming the global figure was modulated in 5 steps. As expected, during valid trials, young adults showed a GP that linearly increased with increasing numbers of local letters (i.e., GP enhancement). This suggests that GP is related to perceptual grouping via Gestalt laws. By contrast, the group of older subjects demonstrated no precedence effect in RT and a non-significant trend toward GP in error rates (ER). No GP enhancement with an increasing number of local elements was observed. Exploratory analysis revealed that individual insensitivity to the modulation of matrix density, as revealed by a lack of global RT acceleration, was restricted to subjects that showed an overall local precedence (LP). Because older subjects tended to more frequently display an insensitivity to matrix modulation and an LP, we conclude that deficient Gestalt detection as indicated by non-enhanced global RT might contribute to the RT-related decline of GP with age.

  7. [Dynamics of the functional characteristics of the microcirculation system in the women of late reproductive age presenting with chronic endometritis under effect of contrast massage].

    PubMed

    Gaĭdarova, A Kh; Kul'chitskaia, D B; Sycheva, A Iu; Alisultanova, L S; Kotenko, N V; Tarasova, T Iu

    2014-01-01

    The objective of the present work was to study the functional characteristics of the microcirculation system in the women of late reproductive age presenting with chronic endometritis before and after a course of contrast massage. Three types of functional changes in the microcirulation system were distinguished based on the results of laser-assisted Doppler flowmetry. All of them were characterized by high coefficients of correlation with the results of dopplerometry of uterine blood flow and underwent dynamic changes in the course of the treatment. The study has demonstrated the high therapeutic effectiveness of the contrast massage technique as a tool for inducing hemodynamic changes in the small pelvis basin in the women suffering from chronic endometritis. PMID:25314767

  8. Label-free and highly sensitive optical imaging of detailed microcirculation within meninges and cortex in mice with the cranium left intact

    NASA Astrophysics Data System (ADS)

    Jia, Yali; An, Lin; Wang, Ruikang K.

    2010-05-01

    We demonstrate for the first time that the detailed blood flow distribution within intracranial dura mater and cortex can be visualized by an ultrahigh sensitive optical microangiography (UHS-OMAG). The study uses an UHS-OMAG system operating at 1310 nm with an imaging speed at 150 frames per second that requires ~10 s to complete one 3-D scan of ~2.5×2.5 mm2. The system is sensitive to blood flow with a velocity ranging from ~4 μm/s to ~23 mm/s. We show superior performance of UHS-OMAG in providing functional images of capillary level microcirculation within meninges in mice with the cranium left intact, the results of which correlate well with the standard dural histopathology.

  9. Label-free and highly sensitive optical imaging of detailed microcirculation within meninges and cortex in mice with the cranium left intact.

    PubMed

    Jia, Yali; An, Lin; Wang, Ruikang K

    2010-01-01

    We demonstrate for the first time that the detailed blood flow distribution within intracranial dura mater and cortex can be visualized by an ultrahigh sensitive optical microangiography (UHS-OMAG). The study uses an UHS-OMAG system operating at 1310 nm with an imaging speed at 150 frames per second that requires approximately 10 s to complete one 3-D scan of approximately 2.5 x 2.5 mm(2). The system is sensitive to blood flow with a velocity ranging from approximately 4 microms to approximately 23 mms. We show superior performance of UHS-OMAG in providing functional images of capillary level microcirculation within meninges in mice with the cranium left intact, the results of which correlate well with the standard dural histopathology.

  10. Paraneoplastic (non-metastatic) adrenal insufficiency preceded the onset of primary lung cancer by 12 weeks.

    PubMed

    Shantha, Ghanshyam Palamaner Subash; Kumar, Anita A; Jeyachandran, Vijay; Rajamanickam, Deepan; Bhaskar, Emmanuel; Paniker, Vinod K; Abraham, Georgi

    2009-01-01

    Clinically evident adrenal insufficiency associated with lung cancer is a rare entity. Among reported cases, adrenal insufficiency has occurred with or succeeded the primary lung cancer. Adrenal insufficiency has also been secondary to metastasis to the adrenal gland. The present report concerns a 61-year-old man, a chronic smoker, who presented to us with symptomatic adrenal insufficiency. He had no evidence of lung cancer during this visit. The primary lung cancer was only identified 12 weeks later. Additionally, his adrenals showed no evidence of metastasis. Hence his adrenal insufficiency had been a paraneoplastic manifestation of the lung cancer, and it had also preceded the primary by 12 weeks.

  11. Paraneoplastic (non-metastatic) adrenal insufficiency preceded the onset of primary lung cancer by 12 weeks

    PubMed Central

    Shantha, Ghanshyam Palamaner Subash; Kumar, Anita A; Jeyachandran, Vijay; Rajamanickam, Deepan; Bhaskar, Emmanuel; Paniker, Vinod K; Abraham, Georgi

    2009-01-01

    Clinically evident adrenal insufficiency associated with lung cancer is a rare entity. Among reported cases, adrenal insufficiency has occurred with or succeeded the primary lung cancer. Adrenal insufficiency has also been secondary to metastasis to the adrenal gland. The present report concerns a 61-year-old man, a chronic smoker, who presented to us with symptomatic adrenal insufficiency. He had no evidence of lung cancer during this visit. The primary lung cancer was only identified 12 weeks later. Additionally, his adrenals showed no evidence of metastasis. Hence his adrenal insufficiency had been a paraneoplastic manifestation of the lung cancer, and it had also preceded the primary by 12 weeks. PMID:21686682

  12. [Hyperinsulinemia as a factor preceding body mass increase in liquidators of the Chernobyl nuclear accident].

    PubMed

    Kovalenko, A N; Zueva, N A; Gerasimenko, T I; Efimov, A S

    2001-01-01

    Basal hyperinsulinemia has been recordable over several years in liquidators of the effects of Chernobyl Accident (ChAEL). There was no dependence of hyperinsulinemia on age, body mass or lenght of service of those persons having worked within the 30-km zone. The findings secured suggest to us that increase in the body mass index (BMI) in ChAEL is preceded by a rise in the blood level of insulin; there is no relatedness of the basal level of insulin in the blood to BMI.

  13. A Decrease in Temperature and Humidity Precedes Human Rhinovirus Infections in a Cold Climate

    PubMed Central

    Ikäheimo, Tiina M.; Jaakkola, Kari; Jokelainen, Jari; Saukkoriipi, Annika; Roivainen, Merja; Juvonen, Raija; Vainio, Olli; Jaakkola, Jouni J.K.

    2016-01-01

    Both temperature and humidity may independently or jointly contribute to the risk of human rhinovirus (HRV) infections, either through altered survival and spread of viruses in the environment or due to changes in host susceptibility. This study examined the relationship between short-term variations in temperature and humidity and the risk of HRV infections in a subarctic climate. We conducted a case-crossover study among conscripts (n = 892) seeking medical attention due to respiratory symptoms during their military training and identified 147 HRV cases by real-time PCR. An average temperature, a decline in daily ambient temperature and absolute humidity (AH) during the three preceding days of the onset (hazard period) and two reference periods (a week prior and after the onset) were obtained. The average daily temperature preceding HRV infections was −9.9 ± 4.9 °C and the average AH was 2.2 ± 0.9 g/m3. An average (odds ratios (OR) 1.07 (95% confidence interval (CI) 1.00–1.15)) and maximal (OR 1.08 (1.01–1.17)) change in temperature increased the risk of HRV infections by 8% per 1 °C decrease. An average (OR 1.20 (CI 1.03–1.40)) and maximal decrease (OR 1.13 (CI 0.96–1.34)) in AH increased the risk of HRV infection by 13% and 20% per 0.5 g/m3 decrease. A higher average temperature during the three preceding days was positively associated with HRV infections (OR 1.07 (CI 1.00–1.15)). A decrease rather than low temperature and humidity per se during the preceding few days increases the risk of HRV infections in a cold climate. The information is applicable to populations residing in cold climates for appropriate personal protection and prevention of adverse health effects. PMID:27598190

  14. Comparative analysis of in situ versus ex situ perfusion on flow and microcirculation in kidney procurement: research on a porcine model

    PubMed Central

    2013-01-01

    Background The first crucial step in transplantation appears to be the effective rinsing of the graft during organ procurement. Even though there is strong suspicion that ex situ perfusion results in better rinsing of the graft, there is no proof for this hypothesis. The aim of this study was to analyse the differences of in situ and ex situ kidney perfusion in a porcine model. Methods Standardised multiorgan procurement was performed in 15 German landrace pigs. Perfusion was carried out using histidine–tryptophan–ketoglutarate solution (HTK) under the application of pressure. In one kidney, in situ perfusion via the aorta was carried out while the second kidney received ex situ perfusion via the renal artery (RA). Perfusate flow inside the aorta and the RA was recorded at different pressure steps. In order to visualise the effect on the microcirculation, different coloured microparticles (MPs; 10 μm) were administered via the aorta or RA. Subsequently, frozen sections of the explanted kidneys were analysed histologically and MPs were evaluated quantitatively. Results Ex situ kidney perfusion resulted in significantly improved flow rates (P<0.0001) compared with in situ perfusion. By applying ex situ perfusion it was even possible to attain physiological flow levels on the RA under the application of external pressure of 150 to 200 mmHg. The amount of MPs was able to highlight the positive impact of ex situ perfusion on microcirculation of the kidney graft (P<0.0001). Conclusions The use of MPs represents a valuable tool for quantitative investigation and illustration of kidney perfusion in experimental setups. Additional ex situ perfusion is able to improve the quality of kidney perfusion. PMID:23837545

  15. Microcirculation of gills and accessory respiratory organs from the air-breathing snakehead fish, Channa punctata, C. gachua, and C. marulius.

    PubMed

    Olson, K R; Roy, P K; Ghosh, T K; Munshi, J S

    1994-01-01

    Snakehead fish of the genus Channa have well-developed air-breathing organs (ABO) yet retain their gill arches for respiratory and non-respiratory functions. Alterations in the macrocirculation accompany inclusion of the ABO and appear to enhance gas exchange efficiency (Munshi et al., 1994. Anat. Rec. 238:77-91). In the present study, the microcirculatory anatomy of gill and ABO from two facultative air-breathing Channa, C. punctata and C. gachua, and one obligate air-breather, C. marulius, were examined in detail using scanning electron microscopy (SEM) of vascular corrosion replicas and fixed whole-sectioned tissue. The results show that the circulation in the filaments from the first, second, and third gill arches is similar to that found in water-breathing teleosts. Fourth gill arch microcirculation of C. punctata is not different from the other three, whereas in C. marulius, it has been greatly modified into a network of low-resistance vascular shunts, although remnants of an intralamellar filamental microcirculation remain. The vascular shunts are formed from extensions of afferent and efferent lamellar arterioles and the complete, or nearly complete, loss of a lamellar sinus. The vasculature of the ABO has been highly modified in all species into a coiled-spiral capillary network with a constricted aperture guarding a dilated capillary dome at the epithelial surface. Microvilli are found congregated on the aperture endothelium of C. punctata but they are virtually absent from C. marulius endothelium. Less than 15% of the ABO capillary surface appears to face the epithelium and thereby contributes directly to gas exchange. These findings suggest that the microvascular modifications observed in Channa entail more than a simple increase in the contact surface between ABO vessels and air and they may serve other unknown physiological functions.

  16. Nocturnal respiration of lichens in their natural habitat is not affected by preceding diurnal net photosynthesis.

    PubMed

    Lange, Otto L; Green, T G Allan

    2006-06-01

    Dark respiration (DR) of lichens is reported to be higher in species with a high photosynthetic potential (suggesting a metabolic maintenance cost effect) and also, often in laboratory studies, transiently after photosynthesis (suggesting a substrate-driven effect). We investigated the occurrence of the latter, the effect of diurnal net photosynthesis (NP) on subsequent nocturnal DR, under natural temperate climate conditions in the chlorolichens Lecanora muralis and Cladonia convoluta and the cyanolichen Collema cristatum. Data sets totalling 15 months, 106 and 113 days, respectively, were obtained from automatic cuvettes that continually measured CO2 exchange and ambient conditions at 30 min intervals. For each 24 h period (sunrise to following sunrise), several measures of NP and DR were extracted, including maximal and mean rates and daily sums. No statistically significant correlations between the various measures of DR and preceding NP were found for L. muralis, only one weak correlation for Co. cristatum (the means of DR and NP) and three for Cl. convoluta (sums and means of DR and NP). It is proposed that even these significant correlations are actually a result of embedded codependencies between NP, DR and thallus water content. Overall it is concluded that no substrate-driven dependency of DR on preceding NP under natural conditions could be recognised. The periods of desiccation that often occur between the NP and following DR as well as the wide range of combinations of conditions would certainly contribute to this lack of relationship.

  17. Peripheral and central neuronal ATF3 precedes CD4+ T-cell infiltration in EAE.

    PubMed

    Frezel, Noémie; Sohet, Fabien; Daneman, Richard; Basbaum, Allan I; Braz, Joao M

    2016-09-01

    Experimental allergic encephalomyelitis (EAE), an animal model of multiple sclerosis produced by immunization with myelin oligodendrocyte glycoprotein (MOG) and adjuvants, results from profound T-cell mediated CNS demyelination. EAE is characterized by progressive, ascending motor dysfunction and symptoms of ongoing pain and hypersensitivity, in some cases preceding or concomitant with the motor deficits. In this regard, the EAE model mimics major features of multiple sclerosis, where a central neuropathic pain state is common. Although the latter condition is presumed to arise from a CNS loss of inhibitory controls secondary to the demyelination, dysfunction of sensory neurons may also contribute. Based on our previous studies that demonstrated the utility of monitoring expression of activating transcription factor 3 (ATF3), a sensitive marker of injured sensory neurons, here we followed both ATF3 and CD4+ T cells invasion of sensory ganglia (as well as the CNS) at different stages of the EAE model. We found that ATF3 is induced in peripheral sensory ganglia and brainstem well before the appearance of motor deficits. Unexpectedly, the ATF3 induction always preceded T cell infiltration, typically in adjacent, but non-overlapping regions. Surprisingly, control administration of the pertussis toxin and/or Complete Freund's adjuvants, without MOG, induced ATF3 in sensory neurons. In contrast, T cell infiltration only occurred with MOG. Taken together, our results suggest that the clinical manifestations in the EAE result not only from central demyelination but also from neuronal stress and subsequent pathophysiology of sensory neurons. PMID:27343802

  18. Aseismic Slips Preceding Ruptures Assumed for Anomalous Seismicities and Crustal Deformations

    NASA Astrophysics Data System (ADS)

    Ogata, Y.

    2007-12-01

    If aseismic slips occurs on a fault or its deeper extension, both seismicity and geodetic records around the source should be affected. Such anomalies are revealed to have occurred during the last several years leading up to the October 2004 Chuetsu Earthquake of M6.8, the March 2007 Noto Peninsula Earthquake of M6.9, and the July 2007 Chuetsu-Oki Earthquake of M6.8, which occurred successively in the near-field, central Japan. Seismic zones of negative and positive increments of the Coulomb failure stress, assuming such slips, show seismic quiescence and activation, respectively, relative to the predicted rate by the ETAS model. These are further supported by transient crustal movement around the source preceding the rupture. Namely, time series of the baseline distance records between a numbers of the permanent GPS stations deviated from the predicted trend, with the trend of different slope that is basically consistent with the horizontal displacements of the stations due to the assumed slips. References Ogata, Y. (2007) Seismicity and geodetic anomalies in a wide area preceding the Niigata-Ken-Chuetsu Earthquake of October 23, 2004, central Japan, J. Geophys. Res. 112, in press.

  19. Investigations of the precedence effect in budgerigars: The perceived location of auditory images

    NASA Astrophysics Data System (ADS)

    Dent, Micheal L.; Dooling, Robert J.

    2003-04-01

    The perceived location of auditory images has been recently studied in budgerigars [Dent and Dooling, J. Acoust. Soc. Am. 113, 2146-2158 (2003)]. Those results suggested that budgerigars (Melopsittacus undulatus) perceive precedence effect stimuli in a manner similar to humans and other animals. Here we extend those experiments to include the effects of intensity on the perceived location of auditory images and the perceived location of paired stimuli from multiple locations in space. We measured the abilities of budgerigars to discriminate between paired stimuli separated in time, intensity, and/or location. Increasing the intensity of a lag stimulus disrupted localization dominance. Budgerigars also perceived simultaneously presented (away from the midline) stimuli as very similar to a single sound presented from the midline, much like the phantom image reported in humans. The perception of paired stimuli from one side of the head versus two sides of the head was also examined and showed that the spatial cues available in these stimuli are important and that echoes are not perceptually inaccessible during localization dominance conditions. The results from these experiments add further data showing the precedence effect in budgerigars is similar to that found in humans and other animals.

  20. Patterns of Life Events Preceding the Suicide in Rural Young Chinese: A Case Control Study1

    PubMed Central

    Zhang, Jie; Ma, Zhenyu

    2012-01-01

    Background Previous studies on the Chinese suicide found some life events prior to the suicide different from those in the West, but there is a lack of summary of the Chinese life event patterns to better understand the effects of the social structure on Chinese suicide. Aim We tried to identify the life events that precede the Chinese rural youth suicides and compare them with what found in the West, so as to find the patterns that are particularly true in the Chinese culture contexts. Methods Suicide cases were investigated with a psychological autopsy study in rural China, and local community living controls were also interviewed with the same protocol. Results We collapsed 64 negative life events into six categories: (1) Marriage/Love, (2) Family/Home, (3) Work/Business, (4) Health/Hospital, (5) Law/Legal, (6) Friend/Relationship. About 92.3% of the suicides studied had experienced at least one type of negative life events. The three most common negative life events categories in the past one year were Family/Home (60.7%), Health/Hospital (53.8%) and Marriage/Love (51.3%) in the rural young suicide victims. Conclusions Among the negative life events, those related to family relations, love affairs, and marital issues were most likely to precede a suicide of rural suicides in China, and it is especially true of rural young women. Family is an important social institution in rural China for suicide prevention efforts. PMID:22595373

  1. Male and female effects on sperm precedence in the giant sperm species Drosophila bifurca.

    PubMed

    Luck, Nathalie; Dejonghe, Béatrice; Fruchard, Stéphane; Huguenin, Sophie; Joly, Dominique

    2007-07-01

    Sperm competition is expected to be a driving force in sexual selection. In internally fertilized organisms, it occurs when ejaculates from more than one male are present simultaneously within the female's reproductive tract. It has been suggested that greater sperm size may improve the competitive ability of sperm, but studies provide contradictory results depending on the species. More recently, the role of females in the evolution of sperm morphology has been pointed out. We investigate here the male and female effects that influence sperm precedence in the giant sperm species, Drosophila bifurca Patterson & Wheeler. Females were mated with two successive males, and the paternity outcomes for both males were analyzed after determining sperm transfer and storage. We found very high values of last male sperm precedence, suggesting a strong interaction between rival sperm. However, the data also indicate high frequencies of removal of the sperm of the first male from the female reproductive tract prior to any interaction with the second male. This implies that successful paternity depends mainly on successful sperm storage. Knowing what happens to the sperm within females appears to be a prerequisite for disentangling post-copulatory sexual interactions between males and females.

  2. HIGH-RESOLUTION SIMULATIONS OF CONVECTION PRECEDING IGNITION IN TYPE Ia SUPERNOVAE USING ADAPTIVE MESH REFINEMENT

    SciTech Connect

    Nonaka, A.; Aspden, A. J.; Almgren, A. S.; Bell, J. B.; Zingale, M.; Woosley, S. E.

    2012-01-20

    We extend our previous three-dimensional, full-star simulations of the final hours of convection preceding ignition in Type Ia supernovae to higher resolution using the adaptive mesh refinement capability of our low Mach number code, MAESTRO. We report the statistics of the ignition of the first flame at an effective 4.34 km resolution and general flow field properties at an effective 2.17 km resolution. We find that off-center ignition is likely, with radius of 50 km most favored and a likely range of 40-75 km. This is consistent with our previous coarser (8.68 km resolution) simulations, implying that we have achieved sufficient resolution in our determination of likely ignition radii. The dynamics of the last few hot spots preceding ignition suggest that a multiple ignition scenario is not likely. With improved resolution, we can more clearly see the general flow pattern in the convective region, characterized by a strong outward plume with a lower speed recirculation. We show that the convective core is turbulent with a Kolmogorov spectrum and has a lower turbulent intensity and larger integral length scale than previously thought (on the order of 16 km s{sup -1} and 200 km, respectively), and we discuss the potential consequences for the first flames.

  3. The effect of an additional reflection in a precedence effect experiment

    PubMed Central

    Goupell, Matthew J.; Yu, Gongqiang; Litovsky, Ruth Y.

    2012-01-01

    Studies on the precedence effect typically utilize a two-source paradigm, which is not realistic relative to real world situations where multiple reflections exist. A step closer to multiple-reflection situations was studied using a three-source paradigm. Discrimination of interaural time differences (ITDs) was measured for one-, two-, and three-source stimuli, using clicks presented over headphones. The ITD was varied in either the first, second, or the third source. The inter-source intervals ranged from 0–130 ms. A perceptual weighting model was extendedto incorporate the three-source stimuli and used to interpret the data. The effect of adding a third source could mostly, but not entirely, be understood by the interaction of effects observed in the precedence effect with two sources. Specifically, for delays between 1 and 8 ms, the ITD information of prior sources was typically weighted more heavily than subsequent sources. For delays greater than 8 ms, subsequent sources were typically weighted slightly more heavily than prior sources. However, there were specific conditions that showed a more complex interaction between the sources. These findings suggest that the two-source paradigm provides a strong basis for understanding how the auditory system processes reflections in spatial hearing tasks. PMID:22501073

  4. The relationship between congenital cardiovascular malformations and spontaneous abortion in preceding pregnancy.

    PubMed

    Sheiner, E; Katz, M; Fraser, D; Gohar, J; Carmi, R

    1998-04-01

    Previous studies have shown an increased frequency of spontaneous abortions in the pregnancy preceding a fetus or a newborn with neural tube defect (NTD) compared with a normal newborn. One explanation of this observation is the trophoblastic cell rest hypothesis put forward by Knox and Clarke, suggesting a teratogenic interaction between the developing embryo and pathological remnants of a previous pregnancy. The other explanation is that the previously lost fetus was also affected with neural tube defect. The aim of this study was to verify whether this observation is also valid for congenital cardiovascular malformations (CCVM). Demographic and obstetric data of 99 mothers (58 Jewish and 41 Bedouin) of newborns who died in the neonatal period from isolated CCVM were compared with those of 103 mothers (48 Jewish and 55 Bedouin) of newborns who died of congenital defects other than NTD and CCVM. Spontaneous abortions in the preceding pregnancy were found in 32% of the cases with CCVM compared with 14% of cases with other defects (ODs) (P=0.0012; odds ratio=3.1, 95% confidence interval 1.5-6.4). This significant difference was independent of maternal age and number of pregnancies or deliveries. No difference was found between Jews and Bedouins. As there is no indication in the literature that fetuses with isolated CCVM tend to be spontaneously aborted, our findings are more supportive of the trophoblastic cell rest theory. PMID:9620563

  5. The Chicken or the Egg: Examining Temporal Precedence Among Attitudes, Injunctive Norms, and College Student Drinking

    PubMed Central

    Lewis, Melissa A.; Litt, Dana M.; Neighbors, Clayton

    2015-01-01

    Objective: The present study was designed to test for projection, conformity, or reciprocal associations among attitudes, injunctive norms, and drinking. Assuming that these constructs are not independent, we proposed three possible trajectories. A conformity model would suggest that injunctive norms should temporally precede drinking or attitudes. Alternatively, a projection model would suggest that attitudes or alcohol use would precede injunctive norms. Furthermore, by examining the processes over three time points, the current study would also examine whether both conformity and projection processes were at work, indicating reciprocal relationships. Method: participants included 249 college students (63.1% female), who participated as a control group in a larger intervention trial. Structural equation modeling was used to examine cross-sectional and prospective associations among injunctive norms, attitudes, and drinking across each of the three time points. Results: Findings demonstrated three significant cross-lagged associations. Injunctive norms at Time 1 was significantly associated with drinking at Time 2 (conformity), and both attitudes and drinking at Time 2 were significantly associated with injunctive norms at Time 3 (projection). The pattern of cross-lagged associations suggested one meaningful indirect pathway, from Time 1 injunctive norms to Time 2 drinking to Time 3 injunctive norms (reciprocal association). Conclusions: The present study suggests that both the conformity and the projection processes seem to be important and evident for college student drinking when considering injunctive norms and drinking over time. Interventions that focus on both conformity and projection may be particularly effective at reducing longer-term alcohol use. PMID:26098035

  6. Elevated prolactin levels immediately precede decisions to babysit by male meerkat helpers.

    PubMed

    Carlson, Anne A; Russell, Andrew F; Young, Andrew J; Jordan, Neil R; McNeilly, Alan S; Parlow, Al F; Clutton-Brock, Tim

    2006-06-01

    Recent studies suggest that decisions to care for the offspring of others in societies of cooperative vertebrates may have a hormonal basis. The crucial question of whether changes in hormone levels immediately precede or merely follow bouts of offspring care, however, remains largely unanswered. Here, we show that in wild groups of cooperatively breeding meerkats, male helpers that decided to babysit for the day had significantly higher levels of prolactin, coupled with lower levels of cortisol, before initiating a babysitting session compared with similarly aged individuals that decided to forage. In addition, these hormonal differences disappeared over the course of the day, suggesting that hormone levels changed in a fundamentally different way in meerkats that babysat versus those that foraged. In contrast, long-term contributions to babysitting were not significantly associated with plasma levels of prolactin, cortisol, or testosterone in individual male helpers. Our results show, for the first time, that elevated levels of prolactin may immediately precede bouts of helping behavior but differ from recent findings on the same study population in which plasma levels of cortisol, but not prolactin, were significantly and positively associated with rates of pup feeding by male helpers. Together, these results lend significant weight to the idea that decisions to help in cooperative vertebrates have a hormonal basis, although different hormones appear to be associated with different types of care.

  7. Application of Convergence Confinement Analysis to the study of preceding displacement of a squeezing rock tunnel

    NASA Astrophysics Data System (ADS)

    Kitagawa, T.; Kumeta, T.; Ichizyo, T.; Soga, S.; Sato, M.; Yasukawa, M.

    1991-01-01

    This paper deals with a study on the geomechanical behavior of the rock mass around the tunnel. The Convergence Confinement Analysis is one of the most appropriate way to estimate this behavior. Elasto-plastic models proposed by Hoek and Brown, Egger and Kastner were adopted in this study. Measurements of the preceding displacement were performed in a road tunnel in Japan, the geology of which is Neogene squeezing mudstone. The measured data was compared with the results of Convergence Confinement Analysis. The preceding displacement was about 40% against the upper bench face converged displacement and 17% against the final converged displacement. Meanwhile, it increased drastically in lower bench excavation step. Back analysis was also executed to calculate the extension of the plastic zone of the rock mass, which was half of that estimated by Convergence Confinement Analysis in upper bench excavation step. But, in lower bench excavation step, the results of the two analyses were very similar. The support pressure and support stiffness were also calculated.

  8. Effects of Prediction and Contextual Support on Lexical Processing: Prediction takes Precedence

    PubMed Central

    Brothers, Trevor; Swaab, Tamara Y.; Traxler, Matthew J.

    2014-01-01

    Readers may use contextual information to anticipate and pre-activate specific lexical items during reading. However, prior studies have not clearly dissociated the effects of accurate lexical prediction from other forms of contextual facilitation such as plausibility or semantic priming. In this study, we measured electrophysiological responses to predicted and unpredicted target words in passages providing varying levels of contextual support. This method was used to isolate the neural effects of prediction from other potential contextual influences on lexical processing. While both prediction and discourse context influenced ERP amplitudes within the time range of the N400, the effects of prediction occurred much more rapidly, preceding contextual facilitation by approximately 100ms. In addition, a frontal, post-N400 positivity (PNP) was modulated by both prediction accuracy and the overall plausibility of the preceding passage. These results suggest a unique temporal primacy for prediction in facilitating lexical access. They also suggest that the frontal PNP may index the costs of revising discourse representations following an incorrect lexical prediction. PMID:25497522

  9. Elevated prolactin levels immediately precede decisions to babysit by male meerkat helpers.

    PubMed

    Carlson, Anne A; Russell, Andrew F; Young, Andrew J; Jordan, Neil R; McNeilly, Alan S; Parlow, Al F; Clutton-Brock, Tim

    2006-06-01

    Recent studies suggest that decisions to care for the offspring of others in societies of cooperative vertebrates may have a hormonal basis. The crucial question of whether changes in hormone levels immediately precede or merely follow bouts of offspring care, however, remains largely unanswered. Here, we show that in wild groups of cooperatively breeding meerkats, male helpers that decided to babysit for the day had significantly higher levels of prolactin, coupled with lower levels of cortisol, before initiating a babysitting session compared with similarly aged individuals that decided to forage. In addition, these hormonal differences disappeared over the course of the day, suggesting that hormone levels changed in a fundamentally different way in meerkats that babysat versus those that foraged. In contrast, long-term contributions to babysitting were not significantly associated with plasma levels of prolactin, cortisol, or testosterone in individual male helpers. Our results show, for the first time, that elevated levels of prolactin may immediately precede bouts of helping behavior but differ from recent findings on the same study population in which plasma levels of cortisol, but not prolactin, were significantly and positively associated with rates of pup feeding by male helpers. Together, these results lend significant weight to the idea that decisions to help in cooperative vertebrates have a hormonal basis, although different hormones appear to be associated with different types of care. PMID:16527276

  10. [Submucosal Partial-turbinectomy (SPT) Preceding an Endoscopic Sinus Surgery (ESS) Procedure].

    PubMed

    Hirai, Tomohisa; Fukushima, Noriyuki; Miyahara, Nobuyuki; Miyoshi, Ayako; Ariki, Masahiko

    2015-07-01

    Preceding a endoscopic sinus surgery (ESS), we have proposed performing a submucosal partial-turbinectomy (SPT) which removes a part of the inferior nasal concha bone attached to maxillary sinus with an antrostomy. By this method, we could not only make a large antrostomy but also obtain good maneuverability by opening the middle nasal meatus in ESS. We performed SPT preceding ESS in 140 cases (261 sides) between January 2012 and June 2014. The stenosis rates of the middle nasal meatus were 14.2% (37 sides from 261 sides) in one month, 7.4% (18 sides from 243 sides) in three months and 3.7% (6 sides from 163 sides) in 6 months after surgery. The closing rates of the antrostomy were 1.5% (4 sides from 261 sides) in one month, 2.9% (7 sides from 243 sides) in three months and 6.7% (11 sides from 163 sides) in 6 months after surgery. We considered that the SPT method would contribute to secure sufficient ventilation routes for wound healing of sinusitis following surgery on the mucous membrane. In addition, the SPT method has merit from the point of deceasing risks of atrophic rhinitis and empty nose syndrome by preserving most of the inferior nasal concha.

  11. Preceding infection as an important risk factor for ischaemic brain infarction in young and middle aged patients

    PubMed Central

    Syrjänen, Jaana; Valtonen, Ville V; Iivanainen, Matti; Kaste, Markku; Huttunen, Jussi K

    1988-01-01

    The role of preceding infection as a risk factor for ischaemic stroke was investigated in a case-control study of 54 consecutive patients under 50 years of age with brain infarction and 54 randomly selected controls from the community matched for sex and age. Information about previous illnesses, smoking, consumption of alcohol, and use of drugs was taken. A blood sample was analysed for standard biochemical variables and serum cholesterol, high density lipoprotein cholesterol, triglyceride, and fasting blood glucose concentrations determined. Titres of antimicrobial antibodies against various bacteria, including Staphylococcus, Streptococcus, Yersinia, and Salmonella and several viruses were determined. Febrile infection was found in patients during the month before the brain infarction significantly more often than in controls one month before their examination (19 patients v three controls; estimated relative risk 9·0 (95% confidence interval 2·2 to 80·0)). The most common preceding febrile infection was respiratory infection (80%). Infections preceding brain infarction were mostly of bacterial origin based on cultural, serological, and clinical data. In conditional logistic regression analysis for matched pairs the effect of preceding febrile infection remained significant (estimated relative risk 14·5 (95% confidence interval 1·9 to 112·3)) when tested with triglyceride concentration, hypertension, smoking, and preceding intoxication with alcohol. Although causality cannot be inferred from these data and plausible underlying mechanisms remain undetermined, preceding febrile infection may play an important part in the development of brain infarction in young and middle aged patients. PMID:3132245

  12. Foreshock Patterns Preceding Great Earthquakes in the Subduction Zone of Chile

    NASA Astrophysics Data System (ADS)

    Papadopoulos, G. A.; Minadakis, G.

    2016-07-01

    Foreshock activity is considered as one of the most promising precursory changes for the main shock prediction in the short term. Averaging over several foreshock sequences has shown that foreshocks are characterized by distinct 3D patterns: their epicenters move towards the main shock epicenter, event count accelerates, and b-value drops. However, these space-time-size patterns were verified so far only in a very few individual cases mainly due to inadequate seismicity catalogue data. We have investigated 3D foreshock patterns before the M w 8.8 Maule in 27 February 2010, M w 8.1 Iquique in 1 April 2014, and M w 8.4 Illapel in 16 September 2015 great earthquakes in the Chile subduction zone. To avoid biased results, no a priori spatiotemporal definitions of foreshocks were inserted. The procedure was based on pattern recognition from statistically significant seismicity changes in the three domains. The pattern recognition in one domain was independent of the pattern recognition in another domain. We found and verified with two independent catalogue data sets (CSN, IPOC) that within a critical area of ca. 65 km from the main shock epicenter, the 2014 event was preceded by distinct foreshock 3D patterns. A nearly weak foreshock stage (20 January-14 March 2014) was followed by a main-strong stage (15 March-1 April 2014) highly significant in all domains, although foreshock activity slightly decreased in about the last 5 days. Seismic moment release also accelerated in the last stage due to the occurrence of a cluster of very strong foreshock events. Foreshock activity very likely occurred in the hanging-wall fault domain on the South American Plate overriding Nazca Plate. The 2014 foreshock activity was quite similar to the one preceding the 6 Apr. 2009 L' Aquila (Italy) M w 6.3 earthquake associated with normal faulting. Using the 2014 earthquake as a reference event, we observed that similar foreshock 3D patterns preceded the 2010 and 2015 earthquakes within

  13. Foreshock Patterns Preceding Great Earthquakes in the Subduction Zone of Chile

    NASA Astrophysics Data System (ADS)

    Papadopoulos, G. A.; Minadakis, G.

    2016-10-01

    Foreshock activity is considered as one of the most promising precursory changes for the main shock prediction in the short term. Averaging over several foreshock sequences has shown that foreshocks are characterized by distinct 3D patterns: their epicenters move towards the main shock epicenter, event count accelerates, and b-value drops. However, these space-time-size patterns were verified so far only in a very few individual cases mainly due to inadequate seismicity catalogue data. We have investigated 3D foreshock patterns before the M w 8.8 Maule in 27 February 2010, M w 8.1 Iquique in 1 April 2014, and M w 8.4 Illapel in 16 September 2015 great earthquakes in the Chile subduction zone. To avoid biased results, no a priori spatiotemporal definitions of foreshocks were inserted. The procedure was based on pattern recognition from statistically significant seismicity changes in the three domains. The pattern recognition in one domain was independent of the pattern recognition in another domain. We found and verified with two independent catalogue data sets (CSN, IPOC) that within a critical area of ca. 65 km from the main shock epicenter, the 2014 event was preceded by distinct foreshock 3D patterns. A nearly weak foreshock stage (20 January-14 March 2014) was followed by a main-strong stage (15 March-1 April 2014) highly significant in all domains, although foreshock activity slightly decreased in about the last 5 days. Seismic moment release also accelerated in the last stage due to the occurrence of a cluster of very strong foreshock events. Foreshock activity very likely occurred in the hanging-wall fault domain on the South American Plate overriding Nazca Plate. The 2014 foreshock activity was quite similar to the one preceding the 6 Apr. 2009 L' Aquila (Italy) M w 6.3 earthquake associated with normal faulting. Using the 2014 earthquake as a reference event, we observed that similar foreshock 3D patterns preceded the 2010 and 2015 earthquakes within

  14. Earth's magnetic field anomalies that precede the M6+ global seismic activity

    NASA Astrophysics Data System (ADS)

    Cataldi, Gabriele; Cataldi, Daniele; Straser, Valentino

    2014-05-01

    In this work has been analyzed the Earth's magnetic field variations and the M6+ global seismic activity to verify if M6+ earthquakes are preceded by a change of the Earth's magnetic field. The data of Earth's magnetic field used to conduct the study of correlation are provided by the induction magnetometer of Radio Emissions Project's station (Lat: 41°41'4.27"N, Long: 12°38'33,60"E, Albano Laziale, Rome, Italy), equipped with a ELF receiver prototype (with a vertically aligned coil antenna) capable to detect the variations of the intensity of the Earth's magnetic field on Z magnetic component. The M6+ global seismic activity data are provided in real-time by USGS, INGV and CSEM. The sample of data used to conduct the study refers to the period between 1 January 2012 and 31 December 2012. The Earth's magnetic field variations data set has been marked with the times (time markers) of M6+ earthquakes occurred on a global scale and has been verified the existence of disturbances of the Earth's geomagnetic field in the time interval that preceded the M6+ global seismic activity. The correlation study showed that all M6+ earthquakes recorded on 2012 were preceded by an increase of the Earth's magnetic field, detected in the Z magnetic component. The authors measured the time lag elapsed between the maximum increment of the Earth's magnetic field recorded before an earthquake M6+ and the date and time at which this occurred, and has been verified that the minimum time lag recorded between the Earth's magnetic field increase and the earthquake M6+ has been 1 minute (9 October 2012, Balleny Islands, M6,4); while, the maximum time lag recorded has been 3600 minutes (26 June 2012, China, M6,3). The average time lag has been 629.47 minutes. In addition, the average time lag is deflected in relation to the magnitude increase. Key words: Seismic Geomagnetic Precursor (SGP), Interplanetary Seismic Precursor (ISP), Earth's magnetic field variations, earthquakes, prevision.

  15. Horizontal Gene Transfer of Pectinases from Bacteria Preceded the Diversification of Stick and Leaf Insects

    PubMed Central

    Shelomi, Matan; Danchin, Etienne G. J.; Heckel, David; Wipfler, Benjamin; Bradler, Sven; Zhou, Xin; Pauchet, Yannick

    2016-01-01

    Genes acquired by horizontal transfer are increasingly being found in animal genomes. Understanding their origin and evolution requires knowledge about the phylogenetic relationships from both source and recipient organisms. We used RNASeq data and respective assembled transcript libraries to trace the evolutionary history of polygalacturonase (pectinase) genes in stick insects (Phasmatodea). By mapping the distribution of pectinase genes on a Polyneoptera phylogeny, we identified the transfer of pectinase genes from known phasmatodean gut microbes into the genome of an early euphasmatodean ancestor that took place between 60 and 100 million years ago. This transfer preceded the rapid diversification of the suborder, enabling symbiont-free pectinase production that would increase the insects’ digestive efficiency and reduce dependence on microbes. Bacteria-to-insect gene transfer was thought to be uncommon, however the increasing availability of large-scale genomic data may change this prevailing notion. PMID:27210832

  16. Bivalent separation into univalents precedes age-related meiosis I errors in oocytes

    PubMed Central

    Sakakibara, Yogo; Hashimoto, Shu; Nakaoka, Yoshiharu; Kouznetsova, Anna; Höög, Christer; Kitajima, Tomoya S.

    2015-01-01

    The frequency of chromosome segregation errors during meiosis I (MI) in oocytes increases with age. The two-hit model suggests that errors are caused by the combination of a first hit that creates susceptible crossover configurations and a second hit comprising an age-related reduction in chromosome cohesion. This model predicts an age-related increase in univalents, but direct evidence of this phenomenon as a major cause of segregation errors has been lacking. Here, we provide the first live analysis of single chromosomes undergoing segregation errors during MI in the oocytes of naturally aged mice. Chromosome tracking reveals that 80% of the errors are preceded by bivalent separation into univalents. The set of the univalents is biased towards balanced and unbalanced predivision of sister chromatids during MI. Moreover, we find univalents predisposed to predivision in human oocytes. This study defines premature bivalent separation into univalents as the primary defect responsible for age-related aneuploidy. PMID:26130582

  17. Foreshock patterns preceding large earthquakes in the subduction zone of Chile

    NASA Astrophysics Data System (ADS)

    Minadakis, George; Papadopoulos, Gerassimos A.

    2016-04-01

    Some of the largest earthquakes in the globe occur in the subduction zone of Chile. Therefore, it is of particular interest to investigate foreshock patterns preceding such earthquakes. Foreshocks in Chile were recognized as early as 1960. In fact, the giant (Mw9.5) earthquake of 22 May 1960, which was the largest ever instrumentally recorded, was preceded by 45 foreshocks in a time period of 33h before the mainshock, while 250 aftershocks were recorded in a 33h time period after the mainshock. Four foreshocks were bigger than magnitude 7.0, including a magnitude 7.9 on May 21 that caused severe damage in the Concepcion area. More recently, Brodsky and Lay (2014) and Bedford et al. (2015) reported on foreshock activity before the 1 April 2014 large earthquake (Mw8.2). However, 3-D foreshock patterns in space, time and size were not studied in depth so far. Since such studies require for good seismic catalogues to be available, we have investigated 3-D foreshock patterns only before the recent, very large mainshocks occurring on 27 February 2010 (Mw 8.8), 1 April 2014 (Mw8.2) and 16 September 2015 (Mw8.4). Although our analysis does not depend on a priori definition of short-term foreshocks, our interest focuses in the short-term time frame, that is in the last 5-6 months before the mainshock. The analysis of the 2014 event showed an excellent foreshock sequence consisting by an early-weak foreshock stage lasting for about 1.8 months and by a main-strong precursory foreshock stage that was evolved in the last 18 days before the mainshock. During the strong foreshock period the seismicity concentrated around the mainshock epicenter in a critical area of about 65 km mainly along the trench domain to the south of the mainshock epicenter. At the same time, the activity rate increased dramatically, the b-value dropped and the mean magnitude increased significantly, while the level of seismic energy released also increased. In view of these highly significant seismicity

  18. Apoptosis Mediated by HIV Protease is Preceded by Cleavage of Bcl-2

    NASA Astrophysics Data System (ADS)

    Strack, Peter R.; West Frey, Michelle; Rizzo, Christopher J.; Cordova, Beverly; George, Henry J.; Meade, Raymond; Ho, Siew Peng; Corman, Jeanne; Tritch, Radonna; Korant, Bruce D.

    1996-09-01

    Expression of the human immunodeficiency virus type 1 (HIV) protease in cultured cells leads to apoptosis, preceded by cleavage of bcl-2, a key negative regulator of cell death. In contrast, a high level of bcl-2 protects cells in vitro and in vivo from the viral protease and prevents cell death following HIV infection of human lymphocytes, while reducing the yields of viral structural proteins, infectivity, and tumor necrosis factor α . We present a model for HIV replication in which the viral protease depletes the infected cells of bcl-2, leading to oxidative stress-dependent activation of NFkappa B, a cellular factor required for HIV transcription, and ultimately to cell death. Purified bcl-2 is cleaved by HIV protease between phenylalanine 112 and alanine 113. The results suggest a new option for HIV gene therapy; bcl-2 muteins that have noncleavable alterations surrounding the HIV protease cleavage site.

  19. Intense foreshocks and a slow slip event preceded the 2014 Iquique Mw 8.1 earthquake.

    PubMed

    Ruiz, S; Metois, M; Fuenzalida, A; Ruiz, J; Leyton, F; Grandin, R; Vigny, C; Madariaga, R; Campos, J

    2014-09-01

    The subduction zone in northern Chile is a well-identified seismic gap that last ruptured in 1877. The moment magnitude (Mw) 8.1 Iquique earthquake of 1 April 2014 broke a highly coupled portion of this gap. To understand the seismicity preceding this event, we studied the location and mechanisms of the foreshocks and computed Global Positioning System (GPS) time series at stations located on shore. Seismicity off the coast of Iquique started to increase in January 2014. After 16 March, several Mw > 6 events occurred near the low-coupled zone. These events migrated northward for ~50 kilometers until the 1 April earthquake occurred. On 16 March, on-shore continuous GPS stations detected a westward motion that we model as a slow slip event situated in the same area where the mainshock occurred. PMID:25061132

  20. Nephrotic syndrome due to immunoglobulin M mesangial glomerulonephritis preceding juvenile idiopathic arthritis.

    PubMed

    Voyer, Luis E; Alvarado, Caupolican; Cuttica, Rubén J; Balestracci, Alejandro; Zardini, Marta; Lago, Néstor

    2013-05-21

    The association between nephrotic syndrome and juvenile idiopathic arthritis have rarely been described in pediatric patients. We report a child with steroid-responsive nephrotic syndrome, with frequent relapses, who presented with a new relapse of nephrotic syndrome associated with arthritis and uveitis at 21 months in remission after treatment with chlorambucil. Juvenile idiopathic arthritis was diagnosed and kidney biopsy examination showed mesangial glomerulonephritis with immunoglobulin M deposits. To our knowledge, only 2 cases of nephrotic syndrome preceding juvenile idiopathic arthritis have been reported, one without histopathology assessment and the other with minimal change disease. Although mesangial glomerulonephritis with nephrotic syndrome and juvenile idiopathic arthritis could have been coincidental, the immune pathogenic mechanism accepted for both diseases suggests they could be related.

  1. Cerebral complexity preceded enlarged brain size and reduced olfactory bulbs in Old World monkeys

    PubMed Central

    Gonzales, Lauren A.; Benefit, Brenda R.; McCrossin, Monte L.; Spoor, Fred

    2015-01-01

    Analysis of the only complete early cercopithecoid (Old World monkey) endocast currently known, that of 15-million-year (Myr)-old Victoriapithecus, reveals an unexpectedly small endocranial volume (ECV) relative to body size and a large olfactory bulb volume relative to ECV, similar to extant lemurs and Oligocene anthropoids. However, the Victoriapithecus brain has principal and arcuate sulci of the frontal lobe not seen in the stem catarrhine Aegyptopithecus, as well as a distinctive cercopithecoid pattern of gyrification, indicating that cerebral complexity preceded encephalization in cercopithecoids. Since larger ECVs, expanded frontal lobes, and reduced olfactory bulbs are already present in the 17- to 18-Myr-old ape Proconsul these features evolved independently in hominoids (apes) and cercopithecoids and much earlier in the former. Moreover, the order of encephalization and brain reorganization was apparently different in hominoids and cercopithecoids, showing that brain size and cerebral organization evolve independently. PMID:26138795

  2. Temporal Precedence Checking for Switched Models and its Application to a Parallel Landing Protocol

    NASA Technical Reports Server (NTRS)

    Duggirala, Parasara Sridhar; Wang, Le; Mitra, Sayan; Viswanathan, Mahesh; Munoz, Cesar A.

    2014-01-01

    This paper presents an algorithm for checking temporal precedence properties of nonlinear switched systems. This class of properties subsume bounded safety and capture requirements about visiting a sequence of predicates within given time intervals. The algorithm handles nonlinear predicates that arise from dynamics-based predictions used in alerting protocols for state-of-the-art transportation systems. It is sound and complete for nonlinear switch systems that robustly satisfy the given property. The algorithm is implemented in the Compare Execute Check Engine (C2E2) using validated simulations. As a case study, a simplified model of an alerting system for closely spaced parallel runways is considered. The proposed approach is applied to this model to check safety properties of the alerting logic for different operating conditions such as initial velocities, bank angles, aircraft longitudinal separation, and runway separation.

  3. Terrorist attacks escalate in frequency and fatalities preceding highly lethal attacks.

    PubMed

    Martens, Andy; Sainudiin, Raazesh; Sibley, Chris G; Schimel, Jeff; Webber, David

    2014-01-01

    Highly lethal terrorist attacks, which we define as those killing 21 or more people, account for 50% of the total number of people killed in all terrorist attacks combined, yet comprise only 3.5% of terrorist attacks. Given the disproportionate influence of these incidents, uncovering systematic patterns in attacks that precede and anticipate these highly lethal attacks may be of value for understanding attacks that exact a heavy toll on life. Here we examined whether the activity of terrorist groups escalates--both in the number of people killed per attack and in the frequency of attacks--leading up to highly lethal attacks. Analyses of terrorist attacks drawn from a state-of-the-art international terrorism database (The Global Terrorism Database) showed evidence for both types of escalation leading up to highly lethal attacks, though complexities to the patterns emerged as well. These patterns of escalation do not emerge among terrorist groups that never commit a highly lethal attack.

  4. Adaptive control for a class of nonlinear time-delay systems preceded by unknown hysteresis

    NASA Astrophysics Data System (ADS)

    Zhang, Xiuyu; Lin, Yan

    2013-08-01

    In this article, a robust adaptive neural dynamic surface control is proposed for a class of time-delay nonlinear systems preceded by saturated hystereses. Compared with the present schemes of dealing with time delay and hystereses input, the main advantages of the proposed scheme are that the prespecified transient and steady-state performance of tracking error can be guaranteed, the computational burden can be greatly reduced and the explosion of complexity problem inherent in backstepping control can be eliminated. Moreover, the utilisation of saturated-type Prandtl-Ishlinskii model makes our scheme more applicable. It is proved that the new scheme can guarantee all the closed-loop signals semiglobally uniformly ultimate bounded. Simulation results are presented to demonstrate the validity of the proposed scheme.

  5. Ionospheric anomalies observed over South Korea preceding the Great Tohoku earthquake of 2011

    NASA Astrophysics Data System (ADS)

    Choi, B. K.; Park, J. U.; Lee, S. J.

    2012-08-01

    We investigated the ionospheric anomalies observed before the Tohoku earthquake, which occurred near the northeast coast of Honshu, Japan on 11 March, 2011. Based on data from a ground-based Global Positioning System (GPS) network on the Korean Peninsula, ionospheric anomalies were detected in the total electron content (TEC) during the daytime a few days before earthquake. Ionospheric TEC anomalies appeared on 5, 8 and 11 March. In particular, the ionospheric disturbances on 8 March evidenced a remarkable increase in TEC. The GPS TEC variation associated with the Tohoku earthquake was an increase of approximately 20 total electron content units (TECU), observed simultaneously in local and global TEC measurements. To investigate these pre-earthquake ionospheric anomalies, space weather conditions such as the solar activity index (F10.7) and geomagnetic activity indices (the Kp and Dst indices) were examined. We also created two-dimensional TEC maps to visual the spatial variations in the ionospheric anomalies preceding the earthquake.

  6. Enhancement of visual attention precedes the emergence of novel metaphor interpretations

    PubMed Central

    Terai, Asuka; Nakagawa, Masanori; Kusumi, Takashi; Koike, Yasuharu; Jimura, Koji

    2015-01-01

    Emergence of creative ideas often involves sudden linking of unrelated ideas. Here we demonstrate that the production of insights about novel metaphor was preceded by prolonged visual inspection of metaphorical sentences. The participants made free spoken responses in a task requiring the generation of semantic interpretations about visually presented sentences, where gaze locations were continuously monitored. We found that creative interpretations were primarily generated from novel metaphorical expressions, rather than from conventional expressions. Moreover, presented words within novel metaphors were visually inspected for longer periods specifically before creative interpretations were produced. Interestingly, prolonged gazes occurred several seconds (∼8 s) prior to the generation of creative interpretations, particularly, in the case of the topic word within the metaphor. These results demonstrate latent cognitive process meditating the emergence of insights, and suggest that the prior visual inspection prompted the semantic representation of the metaphorical sentences, which eventually facilitates creative ideas. PMID:26167155

  7. Possible deep fault slip preceding the 2004 Parkfield earthquake, inferred from detailed observations of tectonic tremor

    USGS Publications Warehouse

    Shelly, D.R.

    2009-01-01

    Earthquake predictability depends, in part, on the degree to which sudden slip is preceded by slow aseismic slip. Recently, observations of deep tremor have enabled inferences of deep slow slip even when detection by other means is not possible, but these data are limited to certain areas and mostly the last decade. The region near Parkfield, California, provides a unique convergence of several years of high-quality tremor data bracketing a moderate earthquake, the 2004 magnitude 6.0 event. Here, I present detailed observations of tectonic tremor from mid-2001 through 2008 that indicate deep fault slip both before and after the Parkfield earthquake that cannot be detected with surface geodetic instruments. While there is no obvious short-term precursor, I find unidirectional tremor migration accompanied by elevated tremor rates in the 3 months prior to the earthquake, which suggests accelerated creep on the fault ???16 km beneath the eventual earthquake hypocenter. Copyright 2009 by the American Geophysical Union.

  8. The tailings dam failure of 5 November 2015 in SE Brazil and its preceding seismic sequence

    NASA Astrophysics Data System (ADS)

    Agurto-Detzel, H.; Bianchi, M.; Assumpção, M.; Schimmel, M.; Collaço, B.; Ciardelli, C.; Barbosa, J. R.; Calhau, J.

    2016-05-01

    The collapse of a mine tailings dam and subsequent flood in SE Brazil on 5 November 2015 was preceded by a small-magnitude seismic sequence. In this report, we explore the spatiotemporal associations between the seismic events and the accident and discuss their possible connection. We also analyze the signals generated by the turbulent mudflow, as recorded by the Brazilian Seismographic Network (RSBR). In light of our observations, we propose as possible contributing factor for the dam collapse either ground shaking and/or soil liquefaction triggered by the earthquakes. The possibility of such a small-magnitude earthquake contributing to the collapse of a tailings dam raises important concerns regarding safety and related legislation of dams in Brazil and the world.

  9. A case of multifocal lupus vulgaris that preceded pulmonary tuberculosis in an immune compromised patient.

    PubMed

    Hamada, Manabu; Urabe, Kazunori; Moroi, Yoichi; Koga, Tetsuya; Takeishi, Masaaki; Fujita, Masaki; Nakanishi, Yoichi; Furue, Masutaka

    2004-02-01

    We describe the rare case of a Japanese male with multifocal lupus vulgaris that preceded asymptomatic pulmonary tuberculosis and adult T-cell leukemia/lymphoma (ATL). He visited our hospital with multiple reddish plaques and erythema of 4-12 months duration. A skin biopsy revealed non-caseating epithelioid granulomas. Mycobacterium tuberculosis was detected by polymerase chain reaction (PCR)-hybridization from a skin biopsy specimen and was also isolated from a culture of the skin biopsy sample. The result of chest roentogenography was compatible with pulmonary tuberculosis. In addition, the diagnosis of ATL was based upon the presence of atypical lymphocytes with convoluted nuclei in his peripheral blood and a positive anti-ATL antibody reaction. Cases of cutaneous tuberculosis presenting with unusual clinical features may be on the increase, accompanying the spread of tuberculosis in immunosuppressed patients, including those with ATL and acquired immunodeficiency syndrome (AIDS).

  10. A healthy patient with bilateral frozen hips preceding bilateral frozen shoulders: a cautionary tale.

    PubMed

    Miller, Abigail R; Arnot, Dean; Wake, Melissa

    2015-01-01

    Adhesive capsulitis of the shoulder (frozen shoulder) is a common disease characterised by spontaneous onset of pain and restriction of movement, followed by 'thawing', with complete or near-complete resolution. Adhesive capsulitis of the hip has been reported in around a dozen patients. This report describes an otherwise-healthy middle-aged woman with apparent sequential resolving adhesive capsulitis of all four ball-and-socket joints over a 9-year period, initially affecting each hip and then each shoulder sequentially. The likely hip diagnosis became clear only retrospectively with development of the second frozen shoulder, 5 years after the first pain. All joints subsequently resolved within the expected timeframe and the patient remains healthy, other than having mild hypertension. This case illustrates that, when hip precedes shoulder involvement, there is the potential for the frozen hip to receive alternate diagnoses for which invasive open hip surgery could unnecessarily be recommended. PMID:26564111

  11. Noble metal nanoclusters and nanoparticles precede mineral formation in magmatic sulphide melts

    PubMed Central

    Helmy, Hassan M.; Ballhaus, Chris; Fonseca, Raúl O.C.; Wirth, Richard; Nagel, Thorsten; Tredoux, Marian

    2013-01-01

    In low temperature aqueous solutions, it has long been recognized by in situ experiments that many minerals are preceded by crystalline nanometre-sized particles and non-crystalline nanophases. For magmatic systems, nanometre-sized precursors have not yet been demonstrated to exist, although the suggestion has been around for some time. Here we demonstrate by high temperature quench experiments that platinum and arsenic self-organize to nanoparticles, well before the melt has reached a Pt–As concentration at which discrete Pt arsenide minerals become stable phases. If all highly siderophile elements associate to nanophases in undersaturated melts, the distribution of the noble metals between silicate, sulphide and metal melts will be controlled by the surface properties of nano-associations, more so than by the chemical properties of the elements. PMID:24008992

  12. Energy crisis precedes global metabolic failure in a novel Caenorhabditis elegans Alzheimer Disease model

    PubMed Central

    Fong, Sheng; Teo, Emelyne; Ng, Li Fang; Chen, Ce-Belle; Lakshmanan, Lakshmi Narayanan; Tsoi, Sau Yee; Moore, Philip Keith; Inoue, Takao; Halliwell, Barry; Gruber, Jan

    2016-01-01

    Alzheimer Disease (AD) is a progressive neurological disorder characterized by the deposition of amyloid beta (Aβ), predominantly the Aβ1–42 form, in the brain. Mitochondrial dysfunction and impaired energy metabolism are important components of AD pathogenesis. However, the causal and temporal relationships between them and AD pathology remain unclear. Using a novel C. elegans AD strain with constitutive neuronal Aβ1–42 expression that displays neuromuscular defects and age-dependent behavioural dysfunction reminiscent of AD, we have shown that mitochondrial bioenergetic deficit is an early event in AD pathogenesis, preceding dysfunction of mitochondrial electron transfer chain (ETC) complexes and the onset of global metabolic failure. These results are consistent with an emerging view that AD may be a metabolic neurodegenerative disease, and also confirm that Aβ-driven metabolic and mitochondrial effects can be reproduced in organisms separated by large evolutionary distances. PMID:27653553

  13. Horizontal Gene Transfer of Pectinases from Bacteria Preceded the Diversification of Stick and Leaf Insects.

    PubMed

    Shelomi, Matan; Danchin, Etienne G J; Heckel, David; Wipfler, Benjamin; Bradler, Sven; Zhou, Xin; Pauchet, Yannick

    2016-01-01

    Genes acquired by horizontal transfer are increasingly being found in animal genomes. Understanding their origin and evolution requires knowledge about the phylogenetic relationships from both source and recipient organisms. We used RNASeq data and respective assembled transcript libraries to trace the evolutionary history of polygalacturonase (pectinase) genes in stick insects (Phasmatodea). By mapping the distribution of pectinase genes on a Polyneoptera phylogeny, we identified the transfer of pectinase genes from known phasmatodean gut microbes into the genome of an early euphasmatodean ancestor that took place between 60 and 100 million years ago. This transfer preceded the rapid diversification of the suborder, enabling symbiont-free pectinase production that would increase the insects' digestive efficiency and reduce dependence on microbes. Bacteria-to-insect gene transfer was thought to be uncommon, however the increasing availability of large-scale genomic data may change this prevailing notion. PMID:27210832

  14. The chemistry that preceded life's origin: a study guide from meteorites.

    PubMed

    Pizzarello, Sandra

    2007-04-01

    Carbonaceous meteorites are rare fragments of asteroids that contain organic carbon of diverse composition, various complexity, and whose lineage can in several instances be traced back to pre-solar environments. Their analyses offer a unique glimpse into the chemistry of the solar system that preceded life and may have been available to its emergence on the early Earth. While the heterogeneity of the organic materials of meteorites is indicative of random synthetic processes for their formation, some of their components have identical counterparts in the biosphere, and a group of meteoritic amino acids were found to display chiral asymmetry, a property known since the time of Pasteur to be inextricably linked to life's processes. The ability of these amino acids to act as asymmetric catalysts, as well as indications that molecular asymmetry in meteorites may not be limited to these compounds, encourage the suggestion of possible involvement of meteoritic material in the induction of selective traits in molecular evolution. PMID:17443883

  15. Microglial activation precedes dopamine terminal pathology in methamphetamine-induced neurotoxicity.

    PubMed

    LaVoie, Matthew J; Card, J Patrick; Hastings, Teresa G

    2004-05-01

    Previous studies have demonstrated methamphetamine (METH)-induced toxicity to dopaminergic and serotonergic axons in rat striatum. Although several studies have identified the nature of reactive astrogliosis in this lesion model, the response of microglia has not been examined in detail. In this investigation, we characterized the temporal relationship of reactive microgliosis to neuropathological alterations of dopaminergic axons in striatum following exposure to methamphetamine. Adult male Sprague-Dawley rats were administered a neurotoxic regimen of methamphetamine and survived 12 h, or 1, 2, 4, and 6 days after treatment. Immunohistochemical methods were used to evaluate reactive changes in microglia throughout the brain of methamphetamine-treated rats, with a particular focus upon striatum. Pronounced morphological changes, indicative of reactive microgliosis, were evident in the brains of all methamphetamine-treated animals and were absent in saline-treated control animals. These included hyperplastic changes in cell morphology that substantially increased the size and staining intensity of reactive microglia. Quantitative analysis of reactive microglial changes in striatum demonstrated that these changes were most robust within the ventrolateral region and were maximal 2 days after methamphetamine administration. Analysis of tissue also revealed that microglial activation preceded the appearance of pathological changes in striatal dopamine fibers. Reactive microgliosis was also observed in extra-striatal regions (somatosensory and piriform cortices, and periaqueductal gray). These data demonstrate a consistent, robust, and selective activation of microglia in response to methamphetamine administration that, at least in striatum, precedes the appearance of morphological indicators of axon pathology. These observations raise the possibility that activated microglia may contribute to methamphetamine-induced neurotoxicity.

  16. Short-term seismic quiescence immediately preceding explosions during the 2011 eruption of Telica Volcano, Nicaragua

    NASA Astrophysics Data System (ADS)

    Rodgers, M.; Roman, D. C.; Geirsson, H.; La Femina, P. C.; Muñoz, A.; Tenorio, V.

    2013-12-01

    Telica Volcano, Nicaragua, experienced a VEI 2 eruptive episode from March-June 2011. The eruption consisted of numerous small to moderate ash explosions, many of which were observed visually and recorded by a local broadband seismic network (the TESAND network). Seismicity at Telica during both background and eruptive periods is characterized by generally high and variable rates of low-magnitude volcano-seismic events. Explosions at Telica are also detected seismically and distinguished from volcanic earthquakes by the length of the seismic signal, their emergent nature and 'cigar-shaped' envelope, and broadband spectral content. During the month of May 2011, we identified 16 explosion events on a seismometer located 0.5 km from the crater vent, some of which correlate with visually observed explosions. From May 1-12, ten explosions are apparent in continuous seismic data. During this period, the rate of volcano-seismic events is relatively low (0-20 events/hour with an average of 4 events per hour). Prior to eight of the 10 explosions, there were no detected seismic events within one hour of the explosion. From May 13-31, seven explosions were identified in the continuous seismic data. During this period, the rate of volcano-seismic events is relatively high (0-48 events per hour, with an average of 18 events per hour). In the hour preceding all seven explosions, there were no detected volcano-seismic events. Visual inspection of the continuous seismic data confirms that a strong decrease in the number of volcano-seismic events immediately preceded most of the 2011 explosions at Telica Volcano. We suggest that the apparent short-term decrease in seismicity before explosions at Telica is related to a cycle of pressure buildup and release in the shallow magmatic-hydrothermal system, with an increase in pressure prior to the explosions both resulting from and reflecting constriction of gas pathways.

  17. Effect of preceding resistance exercise on metabolism during subsequent aerobic session.

    PubMed

    Kang, Jie; Rashti, Stefanie L; Tranchina, Christopher P; Ratamess, Nicholas A; Faigenbaum, Avery D; Hoffman, Jay R

    2009-09-01

    The present study was undertaken to evaluate the acute effect of prior resistance training of varying intensities on energy expenditure and substrate utilization during subsequent aerobic exercise. Eleven males and 21 females completed three experimental trials consisting of (1) aerobic exercise only (C), (2) aerobic exercise preceded by a high-intensity resistance training (HI), and (3) aerobic exercise preceded by a low-intensity resistance training (LO). Resistance training produced an equal volume between HI and LO and consisted of six exercises with each performed for three sets of eight repetitions at 90% of 8-RM in HI and three sets of 12 repetitions at 60% of 8-RM in LO. Aerobic exercise was performed on a cycle ergometer at 50% VO(2)peak for 20 min in all trials. Oxygen uptake (VO2), and carbohydrate and fat oxidation were determined throughout each aerobic exercise session. Fat oxidation rate was higher (P < 0.05) in HI than either LO or C in both males and females. VO2 was also higher (P < 0.05) in HI than either LO or C in females. In males, although between-trial differences in VO2 did not reach statistical significance, they were consistent with the trend seen in females. No differences in carbohydrate oxidation rates were observed across the three trials in either gender group. It appears that in training that combines both aerobic and resistance exercises, performing a comparatively higher intensity resistance exercise first would augment fat utilization and energy expenditure during subsequent aerobic exercise.

  18. The Stress and Vascular Catastrophes in Newborn Rats: Mechanisms Preceding and Accompanying the Brain Hemorrhages.

    PubMed

    Semyachkina-Glushkovskaya, Oxana; Borisova, Ekaterina; Abakumov, Maxim; Gorin, Dmitry; Avramov, Latchezar; Fedosov, Ivan; Namykin, Anton; Abdurashitov, Arkady; Serov, Alexander; Pavlov, Alexey; Zinchenko, Ekaterina; Lychagov, Vlad; Navolokin, Nikita; Shirokov, Alexander; Maslyakova, Galina; Zhu, Dan; Luo, Qingming; Chekhonin, Vladimir; Tuchin, Valery; Kurths, Jürgen

    2016-01-01

    In this study, we analyzed the time-depended scenario of stress response cascade preceding and accompanying brain hemorrhages in newborn rats using an interdisciplinary approach based on: a morphological analysis of brain tissues, coherent-domain optical technologies for visualization of the cerebral blood flow, monitoring of the cerebral oxygenation and the deformability of red blood cells (RBCs). Using a model of stress-induced brain hemorrhages (sound stress, 120 dB, 370 Hz), we studied changes in neonatal brain 2, 4, 6, 8 h after stress (the pre-hemorrhage, latent period) and 24 h after stress (the post-hemorrhage period). We found that latent period of brain hemorrhages is accompanied by gradual pathological changes in systemic, metabolic, and cellular levels of stress. The incidence of brain hemorrhages is characterized by a progression of these changes and the irreversible cell death in the brain areas involved in higher mental functions. These processes are realized via a time-depended reduction of cerebral venous blood flow and oxygenation that was accompanied by an increase in RBCs deformability. The significant depletion of the molecular layer of the prefrontal cortex and the pyramidal neurons, which are crucial for associative learning and attention, is developed as a consequence of homeostasis imbalance. Thus, stress-induced processes preceding and accompanying brain hemorrhages in neonatal period contribute to serious injuries of the brain blood circulation, cerebral metabolic activity and structural elements of cognitive function. These results are an informative platform for further studies of mechanisms underlying stress-induced brain hemorrhages during the first days of life that will improve the future generation's health. PMID:27378933

  19. The Stress and Vascular Catastrophes in Newborn Rats: Mechanisms Preceding and Accompanying the Brain Hemorrhages

    PubMed Central

    Semyachkina-Glushkovskaya, Oxana; Borisova, Ekaterina; Abakumov, Maxim; Gorin, Dmitry; Avramov, Latchezar; Fedosov, Ivan; Namykin, Anton; Abdurashitov, Arkady; Serov, Alexander; Pavlov, Alexey; Zinchenko, Ekaterina; Lychagov, Vlad; Navolokin, Nikita; Shirokov, Alexander; Maslyakova, Galina; Zhu, Dan; Luo, Qingming; Chekhonin, Vladimir; Tuchin, Valery; Kurths, Jürgen

    2016-01-01

    In this study, we analyzed the time-depended scenario of stress response cascade preceding and accompanying brain hemorrhages in newborn rats using an interdisciplinary approach based on: a morphological analysis of brain tissues, coherent-domain optical technologies for visualization of the cerebral blood flow, monitoring of the cerebral oxygenation and the deformability of red blood cells (RBCs). Using a model of stress-induced brain hemorrhages (sound stress, 120 dB, 370 Hz), we studied changes in neonatal brain 2, 4, 6, 8 h after stress (the pre-hemorrhage, latent period) and 24 h after stress (the post-hemorrhage period). We found that latent period of brain hemorrhages is accompanied by gradual pathological changes in systemic, metabolic, and cellular levels of stress. The incidence of brain hemorrhages is characterized by a progression of these changes and the irreversible cell death in the brain areas involved in higher mental functions. These processes are realized via a time-depended reduction of cerebral venous blood flow and oxygenation that was accompanied by an increase in RBCs deformability. The significant depletion of the molecular layer of the prefrontal cortex and the pyramidal neurons, which are crucial for associative learning and attention, is developed as a consequence of homeostasis imbalance. Thus, stress-induced processes preceding and accompanying brain hemorrhages in neonatal period contribute to serious injuries of the brain blood circulation, cerebral metabolic activity and structural elements of cognitive function. These results are an informative platform for further studies of mechanisms underlying stress-induced brain hemorrhages during the first days of life that will improve the future generation's health. PMID:27378933

  20. Apoptosis induced in Jurkat cells by several agents is preceded by intracellular acidification.

    PubMed Central

    Gottlieb, R A; Nordberg, J; Skowronski, E; Babior, B M

    1996-01-01

    We have previously shown that in neutrophils deprived of granulocyte colony-stimulating factor, apoptosis is preceded by acidification and that the protection against apoptosis conferred on neutrophils by granulocyte colony-stimulating factor is dependent upon delay of this acidification. To test the hypothesis that acidification could be a general feature of apoptosis, we examined intracellular pH changes in another cell line. Jurkat cells, a T-lymphoblastoid line, were induced to undergo apoptosis with anti-Fas IgM, cycloheximide, or exposure to short-wavelength UV light. We found that acidification occurred in response to treatment with these agents and that acidification preceded DNA fragmentation. Jurkat cells were also found to possess an acid endonuclease that is active below pH 6.8, compatible with a possible role for this enzyme in chromatin digestion during apoptosis. Incubation of the cells with the bases imidazole or chloroquine during treatment with anti-Fas antibody or cycloheximide or after UV exposure decreased apoptosis as assessed by nuclear morphology and DNA content. The alkalinizing effect of imidazole and chloroquine was shown by the demonstration that the percentage of cells with an intracellular pH below 6.8 after treatment with anti-Fas antibody, cycloheximide, or UV was diminished in the presence of base as compared with similarly treated cells incubated in the absence of base. We conclude that acidification is an early event in programmed cell death and may be essential for genome destruction. Images Fig. 5 PMID:8570610

  1. Impaired fetal thymic growth precedes clinical preeclampsia: a case-control study.

    PubMed

    Eviston, David P; Quinton, Ann E; Benzie, Ron J; Peek, Michael J; Martin, Andrew; Nanan, Ralph K

    2012-06-01

    In preeclampsia the maternal adaptive immune system undergoes specific changes, which are different from the physiological processes associated with healthy pregnancy. Whether preeclampsia also affects the fetal immune system is difficult to investigate, due to limited access to the fetus. We hypothesized that if preeclampsia affects the fetal adaptive immune system this might be associated with early changes in thymic growth. In this case-control study, 53 preeclamptic and 120 healthy control pregnancies were matched for maternal age, gestational age and smoking. Fetal thymus diameter was measured as the greatest width perpendicular to a line connecting sternum and spine based on ultrasound images taken at 17-21 weeks gestation. Independent of fetal and maternal anthropometric measures, thymuses were found to be smaller in preeclamptic pregnancies than healthy controls (16.2 mm versus 18.3 mm, respectively, mean difference=2.1 mm, 95% CI: 0.8-3.3, p<0.001), and the odds of developing preeclampsia was estimated to be 0.72 (95% CI: 0.60-0.86, p<0.001) lower for each 1 mm increase in thymus diameter. There was no correlation between the onset of preeclampsia and fetal thymus size. This is the first study to suggest that fetal thymus growth is reduced before the clinical onset of preeclampsia and precedes any described fetal anomalies or maternal immunological changes associated with preeclampsia. We propose that the fetal adaptive immune system is either passively affected by maternal processes preceding clinical preeclampsia or is actively involved in initiating preeclampsia in later pregnancy.

  2. Intrinsic hyporesponsiveness of invariant natural killer T cells precedes the onset of lupus.

    PubMed

    Yang, J-Q; Kim, P J; Halder, R C; Singh, R R

    2013-07-01

    Patients with systemic lupus erythematosus (SLE) display reduced numbers and functions of invariant natural killer T (iNK T) cells, which are restored upon treatment with corticosteroids and rituximab. It is unclear whether the iNK T cell insufficiency is a consequence of disease or is a primary abnormality that precedes the onset of disease. To address this, we analysed iNK T cell function at different stages of disease development using the genetically lupus-susceptible NZB × NZW F1 (BWF(1)) model. We found that iNK T cell in-vivo cytokine responses to an iNK T cell ligand α-galactosylceramide (α-GalCer) were lower in BWF(1) mice than in non-autoimmune BALB/c and major histocompatibility complex (MHC)-matched NZB × N/B10.PL F1 mice, although iNK T cell numbers in the periphery were unchanged in BWF(1) mice compared to control mice. Such iNK T cell hyporesponsiveness in BWF(1) mice was detected at a young age long before the animals exhibited any sign of autoimmunity. In-vivo activation of iNK T cells is known to transactivate other immune cells. Such transactivated T and B cell activation markers and/or cytokine responses were also lower in BWF(1) mice than in BALB/c controls. Finally, we show that iNK T cell responses were markedly deficient in the NZB parent but not in NZW parent of BWF(1) mice, suggesting that BWF(1) might inherit the iNK T cell defect from NZB mice. Thus, iNK T cells are functionally insufficient in lupus-prone BWF(1) mice. Such iNK T cell insufficiency precedes the onset of disease and may play a pathogenic role during early stages of disease development in SLE.

  3. Diseases that precede disability among latter-stage elderly individuals in Japan.

    PubMed

    Naruse, Takashi; Sakai, Mahiro; Matsumoto, Hiroshige; Nagata, Satoko

    2015-08-01

    Understanding causes of disability among elderly individuals is an important public health issue, particularly because of the increasing rate of disabled elderly individuals and the social costs in a rapidly aging society. Accordingly, we aimed to describe the diseases that precede disability and investigate the types of diseases that are related to severe disability among Japanese elderly individuals aged over 75 years. Using claim data from the latter-stage elderly healthcare system and long-term care insurance system, we identified 76,265 elderly individuals over 75 years old who did not qualify as disabled on April 1, 2011. Among them, 3,715 elderly individuals who had been newly qualified as disabled between April 1, 2011 and March 31, 2012 were selected. Disease codes from the medical claim data in the 6 months prior to disability were collected. All descriptions were developed separately for six groups divided by gender and disability level (low, middle, and high). The results of the ordinal logistic analysis including sex and age revealed that men tended to have significantly higher levels of disability (β = 0.417, p < 0.001) than women. Cerebrovascular disorder (CVD) was the most common disease in almost all age and disability level groups. In low-level disability groups, cancer in men (12.8%) and arthropathy and fracture in women (11.9% and 13.5%, respectively) were as common as cerebrovascular disorder (12.2% and 9.7%, in men and women, respectively). Stroke was the most common disease for all genders and disability levels. The diseases preceding low-level disability differed by gender. This study demonstrated the need to consider arthropathy and fracture as well as CVD in order to prevent disability.

  4. Impaired nigrostriatal function precedes behavioral deficits in a genetic mitochondrial model of Parkinson's disease

    PubMed Central

    Good, Cameron H.; Hoffman, Alexander F.; Hoffer, Barry J.; Chefer, Vladimir I.; Shippenberg, Toni S.; Bäckman, Cristina M.; Larsson, Nils-Göran; Olson, Lars; Gellhaar, Sandra; Galter, Dagmar; Lupica, Carl R.

    2011-01-01

    Parkinson's disease (PD) involves progressive loss of nigrostriatal dopamine (DA) neurons over an extended period of time. Mitochondrial damage may lead to PD, and neurotoxins affecting mitochondria are widely used to produce degeneration of the nigrostriatal circuitry. Deletion of the mitochondrial transcription factor A gene (Tfam) in C57BL6 mouse DA neurons leads to a slowly progressing parkinsonian phenotype in which motor impairment is first observed at ∼12 wk of age. l-DOPA treatment improves motor dysfunction in these “MitoPark” mice, but this declines when DA neuron loss is more complete. To investigate early neurobiological events potentially contributing to PD, we compared the neurochemical and electrophysiological properties of the nigrostriatal circuit in behaviorally asymptomatic 6- to 8-wk-old MitoPark mice and age-matched control littermates. Release, but not uptake of DA, was impaired in MitoPark mouse striatal brain slices, and nigral DA neurons lacked characteristic pacemaker activity compared with control mice. Also, hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channel function was reduced in MitoPark DA neurons, although HCN messenger RNA was unchanged. This study demonstrates altered nigrostriatal function that precedes behavioral parkinsonian symptoms in this genetic PD model. A full understanding of these presymptomatic cellular properties may lead to more effective early treatments of PD.—Good, C. H., Hoffman, A. F., Hoffer, B. J., Chefer, V. I., Shippenberg, T. S., Bäckman, C. M., Larsson, N.-G., Olson, L., Gellhaar, S., Galter, D., Lupica, C. R. Impaired nigrostriatal function precedes behavioral deficits in a genetic mitochondrial model of Parkinson's disease. PMID:21233488

  5. [Comparative analysis of the results of patient prosthetic treatment by removable arch and elastic constructions in cases of end mandibular defects based on microcirculation study of prosthetic bed tissues].

    PubMed

    Churygin, S N

    2007-01-01

    Study was performed of the microcirculation in gingival tissues of prosthetic bed in patients with end mandibular defects treated by removable arch and elastic constructions in order to increase prosthetic treatment efficacy. It was established that most favourable stimulating effect upon trophics was achieved in patients who had received removable plate constructions made according to the technology of thermoinjection system produced by the company Valplast on nylon base. PMID:18163066

  6. Low-energy helium-neon laser therapy induces repigmentation and improves the abnormalities of cutaneous microcirculation in segmental-type vitiligo lesions.

    PubMed

    Wu, Chieh-Shan; Hu, Stephen Chu-Sung; Lan, Cheng-Che E; Chen, Gwo-Shing; Chuo, Wen-Ho; Yu, Hsin-Su

    2008-04-01

    Segmental vitiligo (SV) is a special form of vitiligo occurring in a dermatomal distribution, and an abnormality involving the sympathetic nerves supplying the affected dermatome is known to underlie this disorder. Previously, we have shown that SV is associated with an abnormal increase in cutaneous blood flow and adrenoceptor responses in the affected areas. Since SV is resistant to conventional forms of therapy, its management represents a challenge for dermatologists. Low energy helium-neon lasers (He-Ne laser, wavelength 632.8 nm) have been employed as a therapeutic instrument in many clinical situations, including vitiligo management and repair of nerve injury. The purpose of this study was to evaluate the effectiveness and safety of He-Ne lasers in treating SV, and determine their effects on the repair of sympathetic nerve dysfunction. Forty patients with stable-stage SV on the head and/or neck were enrolled in this study. He-Ne laser irradiation was administered locally at 3.0 J/cm2 with point stimulation once or twice weekly. Cutaneous microcirculatory assessments in six SV patients were performed using a laser Doppler flowmeter. The sympathetic adrenoceptor response of cutaneous microcirculation was determined by measuring cutaneous blood flow before, during and after iontophoresis with sympathomimetic drugs (phenylephrine, clonidine and propranolol). All measurements of microcirculation obtained at SV lesions were simultaneously compared with contralateral normal skin, both before and after He-Ne laser treatment. After an average of 17 treatment sessions, initial repigmentation was noticed in the majority of patients. Marked repigmentation (> 50%) was observed in 60% of patients with successive treatments. Cutaneous blood flow was significantly higher at SV lesions compared with contralateral skin, but this was normalized after He-Ne laser treatment. In addition, the abnormal decrease in cutaneous blood flow in response to clonidine was improved by He

  7. Behaviour patterns preceding a railway suicide: Explorative study of German Federal Police officers' experiences

    PubMed Central

    2011-01-01

    Background Constant high-level numbers of railway suicides indicate that prevention strategies against railway suicides are urgently needed. The main question of the present study was whether pre-crash railway suicide behaviour can be identified, using German Federal Police officers experience with suicidal events in railway related environments. Methods To collect information on pre-crash railway suicide behaviour, a questionnaire was used and made available on the German Federal Police intranet. A total of 202 subjects (mean age: 41 years, sex: 84.9% male) were included in the analysis. Multivariate logistic regression analyses were performed to predict the prevention of suicide (first model) or demand for counselling (second model) as outcomes. Sex, age, years of service, number of experienced suicides, suicides personally observed, information on suicides obtained from witnesses and finally either counselling/debriefing (first model) or whether officers had prevented a suicide (second model) were used as predictors. Results A considerable proportion of police officers reported behavioural patterns preceding a suicide. Half of them observed the dropping or leaving behind of personal belongings or the avoidance of eye contact, more than a third erratic gesture, mimic or movement. Erratic communication patterns and general confusion were each reported by about one quarter. One fifth indicated the influence of alcohol. Less frequently observed behaviour was aimlessly wandering (14.3%) and out of the ordinary clothing (4%). About one third of all railway suicide victims committed suicide in stations. Of those, 70% had chosen an eminent spot. The multivariate logistic regression model using prevented suicides as the outcome identified the number of suicides experienced, counselling/debriefing and having personally observed a suicide as variables with significant impact. The model using counselling/debriefing as the outcome identified age and having prevented a

  8. Modeling mechanisms that contribute to the precedence effect: From auditory periphery to midbrain

    NASA Astrophysics Data System (ADS)

    Xia, Jing

    The precedence effect (PE) describes a perceptual phenomenon whereby a pair of temporally close clicks from different directions is perceived as coming from a location near that of the first-arriving sound. The objective of this thesis is to build a physiologically plausible model that predicts perceptual aspects of the PE. The project explores different mechanisms that may contribute to the PE at different levels of the auditory system. The roles of peripheral processing and frequency dominance on the PE were explored by modeling the auditory nerve fiber and using a binaural, cross-correlation model whose outputs were weighted across frequency to predict perceived location. New behavioral results confirmed model predictions that (1) lateralization of narrowband clicks is strongly influenced by the stimulus center frequency and the inter-stimulus delay (ISD) between leading and lagging clicks, and (2) decrements in the leading click level influence lateralization of wideband clicks differently at different ISDs. The role of adaptation was explored by modeling neurons in the cochlear nucleus and the medial superior olive (MSO), both of which are important in computing the localization cues of the auditory stimuli. Simulation results indicated that low-threshold potassium currents (a form of fast adaptation) can prevent jittery, subthreshold inputs from accumulating, thus enhancing synchronization. Synaptic depression (a form of slow adaptation) can produce a sustained decline of the responses after accurately encoding the stimulus onset. The role of long-lasting inhibition was explored by modeling inferior colliculus neurons with inhibitory inputs from both ipsilateral and contralateral MSOs. Psychophysical predictions were generated from a population of model neurons. The model simulated how the physiological suppression of the lagging response depends on the ISD and relative lead and lag locations, as well as behavioral results showing that the perceived location

  9. A global method for identifying dependences between helio-geophysical and biological series by filtering the precedents (outliers)

    NASA Astrophysics Data System (ADS)

    Ozheredov, V. A.; Breus, T. K.; Gurfinkel, Yu. I.; Matveeva, T. A.

    2014-12-01

    A new approach to finding the dependence between heliophysical and meteorological factors and physiological parameters is considered that is based on the preliminary filtering of precedents (outliers). The sought-after dependence is masked by extraneous influences which cannot be taken into account. Therefore, the typically calculated correlation between the external-influence ( x) and physiology ( y) parameters is extremely low and does not allow their interdependence to be conclusively proved. A robust method for removing the precedents (outliers) from the database is proposed that is based on the intelligent sorting of the polynomial curves of possible dependences y( x), followed by filtering out the precedents which are far away from y( x) and optimizing the coefficient of nonlinear correlation between the regular, i.e., remaining, precedents. This optimization problem is shown to be a search for a maximum in the absence of the concept of gradient and requires the use of a genetic algorithm based on the Gray code. The relationships between the various medical and biological parameters and characteristics of the space and terrestrial weather are obtained and verified using the cross-validation method. It is proven that, by filtering out no more than 20% of precedents, it is possible to obtain a nonlinear correlation coefficient of no less than 0.5. A juxtaposition of the proposed method for filtering precedents (outliers) and the least-square method (LSM) for determining the optimal polynomial using multiple independent tests (Monte Carlo method) of models, which are as close as possible to real dependences, has shown that the LSM determination loses much in comparison to the proposed method.

  10. Effects of Multidirectional Vibrations Delivered in a Horizontal Position (Andullation®) on Blood Microcirculation in Laboratory Animals: A Preliminary Study

    PubMed Central

    Pastouret, Frederic; Cardozo, Lucia; Lamote, Jan; Buyl, Ronald; Lievens, Pierre

    2016-01-01

    Background A whole-body vibration technique delivered in a horizontal position through a massage mattress was introduced in 2007. The present study analyzed the effects of different exposure periods to these vibrations on microcirculation of mice. Material/Methods Different periods of vibrations (30Hz) were locally delivered in a horizontal position on the external abdominal skin in 3 randomized groups of mice (N=42). The 3 groups receiving vibrations were compared to an untreated control group (N=14). The 3 experimental groups received 3, 6, and 10 min of vibrations. The in vivo measurement of the arterial and venous diameters was done before and after each vibration period. Results Average venous diameters (μm) after 6 to 10 min of vibrations were significantly increased (7% and 12%, p values 0.026 and 0.013, respectively), but 3 min did not significantly change average venous diameters. Arterial diameters (μm) did not significantly vary after 3, 6, and 10 min. In the control group, variations of arterial and venous diameters during 10 min were not significant. Conclusions This study shows a vasodilatory effect of low-frequency vibrations. The hypothesis of local cutaneous blood flow increase is retained. A phenomenon of shear stress of the endothelium induced by skin massage generates this local venous vasodilation and blood flow increase. PMID:27739419

  11. Astragulus polysaccharide-loaded fibrous mats promote the restoration of microcirculation in/around skin wounds to accelerate wound healing in a diabetic rat model.

    PubMed

    Yang, Ye; Wang, Fei; Yin, Dengke; Fang, Zhaohui; Huang, Lu

    2015-12-01

    Tissue engineering scaffolds (TES) can carry numerous biomacromolecules and cells, and they have been widely used in diabetic skin wound healing with positive effects. However, the bioactive retention of biomacromolecules and cells during fabrication and storage is still a factor restricting their use. Moreover, impaired blood supply in/around poorly healing diabetic skin wounds has not been considered. In the present study, a bioactive natural substance of Astragalus polysaccharide (APS), which has stable and confirmed effects on endothelial protection, was embedded into fibrous TES by electrospinning. The administration of APS-loaded TES on the skin wound in a diabetic rat model led to a dose-dependent promotion in skin blood flow around wounds and an increase in endoglin expression and microvessel density in regenerated skin tissues. Furthermore, the higher loading of APS in TES led to faster collagen synthesis, appendage and epidermal differentiation, and wound closure. In summary, the combination of APS with TES is a potentially novel therapeutic strategy for diabetic skin wound healing, as it not only mimics the ultrastructure of extracellular matrixes but also restores skin microcirculation.

  12. Effects of Intermittent Pneumatic Compression on Reduction of Postoperative Lower Extremity Edema and Normalization of Foot Microcirculation Flow in Patients Undergoing Arterial Revascularization

    PubMed Central

    Pawlaczyk, Katarzyna; Gabriel, Marcin; Urbanek, Tomasz; Dzieciuchowicz, Łukasz; Krasiński, Zbigniew; Gabriel, Zofia; Olejniczak-Nowakowska, Małgorzata; Stanisić, Michał

    2015-01-01

    Background In patients with chronic leg ischemia, the beneficial effect of arterial revascularization can be significantly decreased due to postoperative leg swelling. The aim of this study was to assess the effects of intermittent pneumatic compression (IPC) on skin flow normalization in patients undergoing revascularization procedures due to chronic leg ischemia. Material/Methods We evaluated 116 patients with chronic leg ischemia. The patients were divided into groups according to the performed treatment (endovascular or surgical) and implementation of IPC postoperatively. The leg edema assessment and microcirculation flow assessment were performed pre- and postoperatively, using percutaneous O2 pressure (TcpO2), cutaneous blood perfusion (CBP) measurements, and skin flow motion assessment. Results In patients who did not receive IPC, a decrease in CBP value was observed in the 1st postoperative assessment. Among patients receiving IPC, the CBD value increased at the 1st and 2nd postoperative measurements, especially in the surgical group. The lowest TcpO2 values were observed in by-pass surgery group without IPC postoperatively. Conclusions The benefits of the by-pass procedure in patients with leg ischemia can be significantly reduced by postoperative edema. Among patients with postoperative leg edema, local tissue blood perfusion can be improved by the use of IPC, which can result in decreased local leg swelling, as well as improved skin blood perfusion and TcpO2. PMID:26690828

  13. Effects of hot and cold foods on signals of heart rate variability and nail fold microcirculation of healthy young humans: a pilot study.

    PubMed

    Chao, Dan-Ping; Chen, Jian-Jung; Huang, Sung-Yen; Tyan, Chu-Chang; Hsieh, Ching-Liang; Sheen, Lee-Yan

    2011-06-30

    In traditional Chinese medicine, hot- and cold-attribute of food ingredients are a major part of dietary therapy. The aim of this study was to establish a suitable scientific methodology to define the attributes of food ingredients by investigating the relationship between food attributes and the physiological signals produced in healthy young subjects with different constitutions. Thirty subjects were grouped into hot and cold constitutions by Chinese medical doctors. Every subject took water, aged ginger tea and coconut water, which are well recognized as having neutral-, hot- and cold-attribute, respectively, on different visits. The different physiological signals induced by the samples were observed using skin and axillary temperature sensors, a heart rate variability analyzer and a laser Doppler anemometer. We found that the capillary red blood cell (RBC) velocity in nail fold microcirculation (NFM) of the subjects with hot constitution accelerated significantly after taking the hot-attribute aged ginger tea, which might be the result of elevated vagal activity leading to arteriole dilation in these subjects. In contrast, in subjects with cold constitution, capillary RBC velocity decelerated significantly and skin temperature decreased markedly after taking the cold-attribute coconut water, which might have been induced by sympathetic nerve activation causing the arteriole to be constricted. Accordingly, the use of capillary RBC velocity of NFM measured by laser Doppler anemometer may be a promising way to classify attributes of food ingredients commonly used in Chinese medicine dietary therapy in accordance with different personal constitutions.

  14. Combined contrast-enhanced ultrasound and rt-PA treatment is safe and improves impaired microcirculation after reperfusion of middle cerebral artery occlusion

    PubMed Central

    Nedelmann, Max; Ritschel, Nouha; Doenges, Simone; Langheinrich, Alexander C; Acker, Till; Reuter, Peter; Yeniguen, Mesut; Pukropski, Jan; Kaps, Manfred; Mueller, Clemens; Bachmann, Georg; Gerriets, Tibo

    2010-01-01

    In monitoring of recanalization and in sonothrombolysis, contrast-enhanced ultrasound (CEUS) is applied in extended time protocols. As extended use may increase the probability of unwanted effects, careful safety evaluation is required. We investigated the safety profile and beneficial effects of CEUS in a reperfusion model. Wistar rats were subjected to filament occlusion of the right middle cerebral artery (MCA). Reperfusion was established after 90 minutes, followed by recombinant tissue-type plasminogen activator (rt-PA) treatment and randomization to additional CEUS (contrast agent: SonoVue; 60 minutes). Blinded outcome evaluation consisted of magnetic resonance imaging (MRI), neurologic assessment, and histology and, in separate experiments, quantitative 3D nano-computed tomography (CT) angiography (900 nm3 voxel size). Nano-CT revealed severely compromised microcirculation in untreated animals after MCA reperfusion. The rt-PA partially improved hemispheric perfusion. Impairment was completely reversed in animals receiving rt-PA and CEUS. This combination was more effective than treatment with either CEUS without rt-PA or rt-PA and ultrasound or ultrasound alone. In MRI experiments, CEUS and rt-PA treatment resulted in a significantly reduced ischemic lesion volume and edema formation. No unwanted effects were detected on MRI, histology, and intracranial temperature assessment. This study shows that CEUS and rt-PA is safe in the situation of reperfusion and displays beneficial effects on the level of the microvasculature. PMID:20531462

  15. The Worker Honeybee Fat Body Proteome Is Extensively Remodeled Preceding a Major Life-History Transition

    PubMed Central

    Chan, Queenie W. T.; Mutti, Navdeep S.; Foster, Leonard J.; Kocher, Sarah D.; Amdam, Gro V.; Wolschin, Florian

    2011-01-01

    Honeybee workers are essentially sterile female helpers that make up the majority of individuals in a colony. Workers display a marked change in physiology when they transition from in-nest tasks to foraging. Recent technological advances have made it possible to unravel the metabolic modifications associated with this transition. Previous studies have revealed extensive remodeling of brain, thorax, and hypopharyngeal gland biochemistry. However, data on changes in the abdomen is scarce. To narrow this gap we investigated the proteomic composition of abdominal tissue in the days typically preceding the onset of foraging in honeybee workers. In order to get a broader representation of possible protein dynamics, we used workers of two genotypes with differences in the age at which they initiate foraging. This approach was combined with RNA interference-mediated downregulation of an insulin/insulin-like signaling component that is central to foraging behavior, the insulin receptor substrate (irs), and with measurements of glucose and lipid levels. Our data provide new insight into the molecular underpinnings of phenotypic plasticity in the honeybee, invoke parallels with vertebrate metabolism, and support an integrated and irs-dependent association of carbohydrate and lipid metabolism with the transition from in-nest tasks to foraging. PMID:21969861

  16. Nondisjunctional segregations in Drosophila female meiosis I are preceded by homolog malorientation at metaphase arrest.

    PubMed

    Gillies, Shane C; Lane, Fiona M; Paik, Wonbeom; Pyrtel, Khateriaa; Wallace, Nneka T; Gilliland, William D

    2013-02-01

    The model of Drosophila female meiosis I was recently revised by the discovery that chromosome congression precedes metaphase I arrest. Use of the prior framework to interpret data from meiotic mutants led to the conclusion that chromosome segregation errors (nondisjunction, NDJ) occurred when nonexchange chromosomes moved out on the spindle in a maloriented configuration and became trapped there at metaphase arrest. The discovery that congression returns nonexchange chromosomes to the metaphase plate invalidates this interpretation and raises the question of what events actually do lead to NDJ. To address this, we have assayed an allelic series of ald (mps1) meiotic mutants that complete congression at wild-type rates, but have widely varying NDJ rates in an otherwise isogenic background, as well as a nod mutant background that primarily undergoes loss of chromosome 4. Using genetic assays to measure NDJ rates, and FISH assays to measure chromosome malorientation rates in metaphase-arrested oocytes, shows that these two rates are highly correlated across ald mutants, suggesting that malorientation during congression commits these chromosomes to eventually nondisjoin. Likewise, the rate of chromosome loss observed in nod is similar to the rate at which these chromosomes fail to associate with the main chromosome mass. Together these results provide a proximal mechanism for how these meiotic mutants cause NDJ and chromosome loss and improve our understanding of how prometaphase chromosome congression relates to anaphase chromosome segregation. PMID:23222652

  17. Nondisjunctional Segregations in Drosophila Female Meiosis I Are Preceded by Homolog Malorientation at Metaphase Arrest

    PubMed Central

    Gillies, Shane C.; Lane, Fiona M.; Paik, Wonbeom; Pyrtel, Khateriaa; Wallace, Nneka T.; Gilliland, William D.

    2013-01-01

    The model of Drosophila female meiosis I was recently revised by the discovery that chromosome congression precedes metaphase I arrest. Use of the prior framework to interpret data from meiotic mutants led to the conclusion that chromosome segregation errors (nondisjunction, NDJ) occurred when nonexchange chromosomes moved out on the spindle in a maloriented configuration and became trapped there at metaphase arrest. The discovery that congression returns nonexchange chromosomes to the metaphase plate invalidates this interpretation and raises the question of what events actually do lead to NDJ. To address this, we have assayed an allelic series of ald (mps1) meiotic mutants that complete congression at wild-type rates, but have widely varying NDJ rates in an otherwise isogenic background, as well as a nod mutant background that primarily undergoes loss of chromosome 4. Using genetic assays to measure NDJ rates, and FISH assays to measure chromosome malorientation rates in metaphase-arrested oocytes, shows that these two rates are highly correlated across ald mutants, suggesting that malorientation during congression commits these chromosomes to eventually nondisjoin. Likewise, the rate of chromosome loss observed in nod is similar to the rate at which these chromosomes fail to associate with the main chromosome mass. Together these results provide a proximal mechanism for how these meiotic mutants cause NDJ and chromosome loss and improve our understanding of how prometaphase chromosome congression relates to anaphase chromosome segregation. PMID:23222652

  18. Automated Discovery and Modeling of Sequential Patterns Preceding Events of Interest

    NASA Technical Reports Server (NTRS)

    Rohloff, Kurt

    2010-01-01

    The integration of emerging data manipulation technologies has enabled a paradigm shift in practitioners' abilities to understand and anticipate events of interest in complex systems. Example events of interest include outbreaks of socio-political violence in nation-states. Rather than relying on human-centric modeling efforts that are limited by the availability of SMEs, automated data processing technologies has enabled the development of innovative automated complex system modeling and predictive analysis technologies. We introduce one such emerging modeling technology - the sequential pattern methodology. We have applied the sequential pattern methodology to automatically identify patterns of observed behavior that precede outbreaks of socio-political violence such as riots, rebellions and coups in nation-states. The sequential pattern methodology is a groundbreaking approach to automated complex system model discovery because it generates easily interpretable patterns based on direct observations of sampled factor data for a deeper understanding of societal behaviors that is tolerant of observation noise and missing data. The discovered patterns are simple to interpret and mimic human's identifications of observed trends in temporal data. Discovered patterns also provide an automated forecasting ability: we discuss an example of using discovered patterns coupled with a rich data environment to forecast various types of socio-political violence in nation-states.

  19. In spontaneously hypertensive rats alterations in aortic wall properties precede development of hypertension.

    PubMed

    van Gorp, A W; Schenau, D S; Hoeks, A P; Boudier, H A; de Mey, J G; Reneman, R S

    2000-04-01

    In hypertension arterial wall properties do not necessarily depend on increased blood pressure alone. The present study investigates the relationship between the development of hypertension and thoracic aortic wall properties in 1.5-, 3-, and 6-mo-old spontaneously hypertensive rats (SHR); Wistar-Kyoto rats (WKY) served as controls. During ketamine-xylazine anesthesia, compliance and distensibility were assessed by means of a noninvasive ultrasound technique combined with invasive blood pressure measurements. Morphometric measurements provided in vivo media cross-sectional area and thickness, allowing the calculation of the incremental elastic modulus. Extracellular matrix protein contents were determined as well. Blood pressure was not significantly different in 1.5-mo-old SHR and WKY, but compliance and distensibility were significantly lower in SHR. Incremental elastic modulus was not significantly different between SHR and WKY at this age. Media thickness and media cross-sectional area were significantly larger in SHR than in WKY, but there was no consistent difference in collagen density and content between the strains. Blood pressure was significantly higher in 3- and 6-mo-old SHR than in WKY, and compliance was significantly lower in SHR. The findings in this study show that in SHR, in which hypertension develops over weeks, alterations in functional aortic wall properties precede the development of hypertension. The decrease in compliance and distensibility at a young age most likely results from media hypertrophy rather than a change in intrinsic elastic properties.

  20. What is a planning model? An introduction to PRECEDE-PROCEED.

    PubMed

    Crosby, Richard; Noar, Seth M

    2011-01-01

    Planning models exist at a macroscopic level; they serve as an organizing framework for an entire health promotion effort aimed at fostering reduction in a given disease. A particularly useful, widely applied, and easy-to-follow example of a planning model is the PRECEDE-PROCEED planning model (PPM). The PPM is very much an ecological approach to health promotion. The PPM is actually quite simple to understand once one realizes that it embodies two key aspects of intervention: a) planning, and (b) evaluation. The PPM guides the program planner to think logically about the desired end point and work "backwards" to achieve that goal. Through community participation, the planning process is broken down into objectives, step 3 sub-objectives, and step 4 sub-objectives. Conceptually, this approach to health promotion provides context to the use of theory, with theory being applied at the fourth step. This observation teaches a vital lesson, namely that program planning is larger and is a more comprehensive task compared to the subservient function of theory selection and application.

  1. [The first film presentation of REM sleep behavior disorder precedes its scientific debut by 35 years].

    PubMed

    Janković, Slavko M; Sokić, Dragoslav V; Vojvodić, Nikola M; Ristić, Aleksandar J

    2006-01-01

    The perplexing and tantalizing disease of rapid eye movement (REM) sleep behavior disorder (RBD) is characterized by peculiar, potentially dangerous behavior during REM sleep. It was described both in animals and humans. RBD in mammals was first described by Jouvet and Delorme in 1965, based on an experimental model induced by lesion in pontine region of cats. In 1972, Passouant et al. described sleep with eye movements and persistent tonic muscle activity induced by tricyclic antidepressant medication, and Tachibana et al., in 1975, the preservation of muscle tone during REM sleep in the acute psychosis induced by alcohol and meprobamate abuse. wever, the first formal description of RBD in humans as new parasomnia was made by Schenck et al in 1986. Subsequently, in 1990, the International Classification of Sleep Disorders definitely recognized RBD as new parasomnia. To our knowledge, arts and literature do not mention RBD. Except for the quotation, made by Schenck et al [n 2002, of Don Quixote de la Mancha whose behavior in sleep strongly suggested that Miguel de Servantes actually described RBD, no other artistic work has portrayed this disorder. Only recently we become aware of the cinematic presentation of RBD which by decades precedes the first scientific description. The first presentation of RBD on film was made prior to the era of advanced electroencephalography and polysomnography, and even before the discovery of REM sleep by Aserinsky and Kleitman in 1953. The artistic and intuitive presentation of RBD was produced in Technicolor in a famous film "Cinderella" created by Walt Disney in 1950, some 35 years prior to its original publication in the journal "Sleep". Since there is an earlier version of the film initially produced in 1920, presumably containing this similar scene, we can only speculate that the first cinematic presentation of RBD might precede its scientific debut by 65 years. In a scene in a barn, clumsy and goofy dog Bruno is, as dogs

  2. [The first film presentation of REM sleep behavior disorder precedes its scientific debut by 35 years].

    PubMed

    Janković, Slavko M; Sokić, Dragoslav V; Vojvodić, Nikola M; Ristić, Aleksandar J

    2006-01-01

    The perplexing and tantalizing disease of rapid eye movement (REM) sleep behavior disorder (RBD) is characterized by peculiar, potentially dangerous behavior during REM sleep. It was described both in animals and humans. RBD in mammals was first described by Jouvet and Delorme in 1965, based on an experimental model induced by lesion in pontine region of cats. In 1972, Passouant et al. described sleep with eye movements and persistent tonic muscle activity induced by tricyclic antidepressant medication, and Tachibana et al., in 1975, the preservation of muscle tone during REM sleep in the acute psychosis induced by alcohol and meprobamate abuse. wever, the first formal description of RBD in humans as new parasomnia was made by Schenck et al in 1986. Subsequently, in 1990, the International Classification of Sleep Disorders definitely recognized RBD as new parasomnia. To our knowledge, arts and literature do not mention RBD. Except for the quotation, made by Schenck et al [n 2002, of Don Quixote de la Mancha whose behavior in sleep strongly suggested that Miguel de Servantes actually described RBD, no other artistic work has portrayed this disorder. Only recently we become aware of the cinematic presentation of RBD which by decades precedes the first scientific description. The first presentation of RBD on film was made prior to the era of advanced electroencephalography and polysomnography, and even before the discovery of REM sleep by Aserinsky and Kleitman in 1953. The artistic and intuitive presentation of RBD was produced in Technicolor in a famous film "Cinderella" created by Walt Disney in 1950, some 35 years prior to its original publication in the journal "Sleep". Since there is an earlier version of the film initially produced in 1920, presumably containing this similar scene, we can only speculate that the first cinematic presentation of RBD might precede its scientific debut by 65 years. In a scene in a barn, clumsy and goofy dog Bruno is, as dogs

  3. The influence of preceding dive cycles on the foraging decisions of Antarctic fur seals

    PubMed Central

    Iwata, T.; Sakamoto, K. Q.; Edwards, E. W. J.; Staniland, I. J.; Trathan, P. N.; Goto, Y.; Sato, K.; Naito, Y.; Takahashi, A.

    2015-01-01

    The foraging strategy of many animals is thought to be determined by their past experiences. However, few empirical studies have investigated whether this is true in diving animals. We recorded three-dimensional movements and mouth-opening events from three Antarctic fur seals during their foraging trips to examine how they adapt their behaviour based on past experience—continuing to search for prey in the same area or moving to search in a different place. Each dive cycle was divided into a transit phase and a feeding phase. The linear horizontal distance travelled after feeding phases in each dive was affected by the mouth-opening rate during the previous 244 s, which typically covered two to three dive cycles. The linear distance travelled tended to be shorter when the mouth-opening rate in the previous 244 s was higher, i.e. seals tended to stay in the same areas with high prey-encounter rates. These results indicate that Antarctic fur seals follow decision-making strategies based on the past foraging experience over time periods longer than the immediately preceding dive. PMID:26156132

  4. Cost estimation for solid waste management in industrialising regions--precedents, problems and prospects.

    PubMed

    Parthan, Shantha R; Milke, Mark W; Wilson, David C; Cocks, John H

    2012-03-01

    The importance of cost planning for solid waste management (SWM) in industrialising regions (IR) is not well recognised. The approaches used to estimate costs of SWM can broadly be classified into three categories - the unit cost method, benchmarking techniques and developing cost models using sub-approaches such as cost and production function analysis. These methods have been developed into computer programmes with varying functionality and utility. IR mostly use the unit cost and benchmarking approach to estimate their SWM costs. The models for cost estimation, on the other hand, are used at times in industrialised countries, but not in IR. Taken together, these approaches could be viewed as precedents that can be modified appropriately to suit waste management systems in IR. The main challenges (or problems) one might face while attempting to do so are a lack of cost data, and a lack of quality for what data do exist. There are practical benefits to planners in IR where solid waste problems are critical and budgets are limited.

  5. DNA damage precedes apoptosis during the regression of the interdigital tissue in vertebrate embryos

    PubMed Central

    Montero, Juan A.; Sanchez-Fernandez, Cristina; Lorda-Diez, Carlos I.; Garcia-Porrero, Juan A.; Hurle, Juan M.

    2016-01-01

    DNA damage independent of caspase activation accompanies programmed cell death in different vertebrate embryonic organs. We analyzed the significance of DNA damage during the regression of the interdigital tissue, which sculpts the digits in the embryonic limb. Interdigit remodeling involves oxidative stress, massive apoptosis and cell senescence. Phosphorylation of H2AX mediated by ATM precedes caspase dependent apoptosis and cell senescence during interdigit regression. The association of γH2AX with other downstream DNA repair factors, including MDC1, Rad50 and 53BP1 suggests a defensive response of cells against DNA damage. The relative distribution of cells γH2AX-only positive, TUNEL-only positive, and cells double positive for both markers is consistent with a sequence of degenerative events starting by damage of the DNA. In support of this interpretation, the relative number of γH2AX-only cells increases after caspase inhibition while the relative number of TUNEL-only cells increases after inhibition of ATM. Furthermore, cultured interdigits survived and maintained intense chondrogenic potential, even at advanced stages of degeneration, discarding a previous commitment to die. Our findings support a new biological paradigm considering embryonic cell death secondary to genotoxic stimuli, challenging the idea that considers physiological cell death a cell suicide regulated by an internal death clock that pre-programmes degeneration. PMID:27752097

  6. Marking emergency exits and evacuation routes with sound beacons utilizing the precedence effect

    NASA Astrophysics Data System (ADS)

    van Wijngaarden, Sander J.; Bronkhorst, Adelbert W.; Boer, Louis C.

    2001-05-01

    Sound beacons can be extremely useful during emergency evacuations, especially when vision is obscured by smoke. When exits are marked with suitable sound sources, people can find these using only their capacity for directional hearing. Unfortunately, unless very explicit instructions were given, sound beacons currently commercially available (based on modulated noise) led to disappointing results during an evacuation experiment in a traffic tunnel. Only 19% out of 65 subjects were able to find an exit by ear. A signal designed to be more self-explanatory and less hostile-sounding (alternating chime signal and spoken message ``exit here'') increased the success rate to 86%. In a more complex environment-a mock-up of a ship's interior-routes to the exit were marked using multiple beacons. By applying carefully designed time delays between successive beacons, the direction of the route was marked, utilizing the precedence effect. Out of 34 subjects, 71% correctly followed the evacuation route by ear (compared to 24% for a noise signal as used in commercially available beacons). Even when subjects were forced to make a worst-case left-right decision at a T-junction, between two beacons differing only in arrival of the first wave front, 77% made the right decision.

  7. Multiple late Triassic carbon cycle perturbations preceding intensified volcanic activity in the Central Atlantic Magmatic Province

    NASA Astrophysics Data System (ADS)

    Ruhl, Micha; Kürschner, Wolfram M.

    2010-05-01

    The end-Triassic mass extinction (~201.5 Ma), marked by terrestrial ecosystem changes and a 50% loss in marine biodiversity, coincides with a major disruption of the global carbon cycle. These events closely coincide with the onset of Central Atlantic Magmatic Province emplacement (Deenen et al., 2010) and the subsequent release of isotopically depleted carbon as gaseous CO2 and from the methane hydrate reservoir. Here we show that the end-Triassic C-cycle perturbation is preceded by two successive 2-3‰ Rhaetian negative excursions in marine and continental δ13CTOC records from the western Tethys and north-west European sections. A coinciding, albeit slightly smaller, negative excursion in a δ13C leaf-record (Lepidopteris ottonis) further suggests successive 13C depletion of the late Triassic global atmosphere. Extensive dyke and sill systems that allowed major flood basalt emplacement in the Central Atlantic Magmatic Province, already intruded sedimentary basins over large parts of Pangea during the late Triassic. Subsurface thermal metamorphism of organic rich strata potentially led to oxidation of organic carbon and the transfer of isotopically depleted carbon to the exogenic carbon pool. In this way causing changes in the global C-cycle already before the onset of major volcanic activity.

  8. Strong and Anomalous Thermal Expansion Precedes the Thermosalient Effect in Dynamic Molecular Crystals.

    PubMed

    Panda, Manas K; Centore, Roberto; Causà, Mauro; Tuzi, Angela; Borbone, Fabio; Naumov, Panče

    2016-01-01

    The ability of thermosalient solids, organic analogues of inorganic martensites, to move by rapid mechanical reconfiguration or ballistic event remains visually appealing and potentially useful, yet mechanistically elusive phenomenon. Here, with a material that undergoes both thermosalient and non-thermosalient phase transitions, we demonstrate that the thermosalient effect is preceded by anomalous thermal expansion of the unit cell. The crystal explosion occurs as sudden release of the latent strain accumulated during the anisotropic, exceedingly strong expansion of the unit cell with αa = 225.9 × 10(-6) K(-1), αb = 238.8 × 10(-6) K(-1) and αc = -290.0 × 10(-6) K(-1), the latter being the largest negative thermal expansivity observed for an organic compound thus far. The results point out to the occurence of the thermosalient effect in phase transitions as means to identify new molecular materials with strong positive and/or negative thermal expansion which prior to this work could only be discovered serendipitously. PMID:27403616

  9. Nuclear Atrophy of Retinal Ganglion Cells Precedes the Bax-Dependent Stage of Apoptosis

    PubMed Central

    Janssen, Katherine T.; Mac Nair, Caitlin E.; Dietz, Joel A.; Schlamp, Cassandra L.; Nickells, Robert W.

    2013-01-01

    Purpose. Retinal ganglion cells atrophy during the execution of the intrinsic apoptotic program. This process, which has been termed the apoptotic volume decrease (AVD) in other cell types, has not been well-characterized in ganglion cells. Methods. Acute optic nerve crush was used to examine neuronal atrophy in the ganglion cell layer in wild-type and Bax-deficient mice. Nuclear size was measured from retinal wholemounts. Heterochromatin formation was assessed using transmission electron microscopy, whereas histone H4 acetylation was monitored using immunofluoresence. Ganglion cell and retinal transcript abundance was measured using quantitative PCR. Results. Nuclear and soma sizes linearly correlated in both control and damaged retinas. Cells in wild-type mice exhibited nuclear atrophy within 1 day after optic nerve damage. Three days after crush, nuclear atrophy was restricted to ganglion cells identified by retrograde labeling, while amacrine cells also exhibited some atrophy by 5 days. Similar kinetics of nuclear atrophy were observed in cells deficient for the essential proapoptotic gene Bax. Bax-deficient cells also exhibited other nuclear changes common in wild-type cells, including the deacetylation of histones, formation of heterochromatin, and the silencing of ganglion cell–specific gene expression. Conclusions. Retinal ganglion cell somas and nuclei undergo the AVD in response to optic nerve damage. Atrophy is rapid and precedes the Bax-dependent committed step of the intrinsic apoptotic pathway. PMID:23422829

  10. Understanding suicide among indigenous adolescents: a review using the PRECEDE model.

    PubMed Central

    Clarke, V. A.; Frankish, C. J.; Green, L. W.

    1997-01-01

    AIM: To use the available literature to identify the causes of suicide among indigenous adolescents. METHOD: The PRECEDE model provided a framework to organize the material and identify the areas where relatively little research had been reported. RESULTS: The epidemiological diagnosis showed that suicide was greater in indigenous than non-indigenous populations and particularly high among adolescent males. Environments of native persons are characterized by remoteness, poverty, cultural displacement, and family disintegration. The educational and organizational diagnosis identified predisposing factors reflecting the social environments previously identified, the enabling factors of televised suicides, and firearm and alcohol availability, in conjunction with an absence of positive expectations. Finally the administrative and policy diagnosis identified a piecemeal, short term perspective, often lacking cultural sensitivity. Although there was more literature from the United States than from Canada, Australia or New Zealand, the pictures emerging were consistent, with problems being identified across continents. Literature was more abundant in relation to the epidemiological, environmental, and educational/ organizational diagnoses than in relation to policy and administration. CONCLUSION: The increased suicide rates among indigenous adolescents were not a product of their native origins, but of the social milieu in which these people generally found themselves. PMID:9213160

  11. Medial temporal theta/alpha power enhancement precedes successful memory encoding: evidence based on intracranial EEG.

    PubMed

    Fell, Juergen; Ludowig, Eva; Staresina, Bernhard P; Wagner, Tobias; Kranz, Thorsten; Elger, Christian E; Axmacher, Nikolai

    2011-04-01

    Not only poststimulus, but also prestimulus neural activity has been shown to be predictive for later successful memory encoding. However, it is still not clear which medial temporal lobe processes precede effective memory formation. Here, our aim was to investigate whether such prestimulus markers for successful memory encoding can be specified based on intracranial recordings directly from the hippocampus and rhinal cortex. For this purpose, we analyzed subsequent memory effects during a continuous word recognition paradigm in 31 presurgical epilepsy patients. We found that rhinal and hippocampal theta and successive alpha power enhancement before word presentation predicted successful memory encoding. Previous studies suggest that stimulus-triggered hippocampal theta activity is particularly related to memory retrieval and activation of a mnemonic context, whereas the alpha rhythm reflects inhibitory top-down control of task processing and executive functioning. In line with these suggestions, we propose that the observed medial temporal theta and alpha power increases before stimulus presentation reflect activation of contextual information and inhibitory top-down control processes preparing for stimulus-triggered memory processing.

  12. The influence of preceding dive cycles on the foraging decisions of Antarctic fur seals.

    PubMed

    Iwata, T; Sakamoto, K Q; Edwards, E W J; Staniland, I J; Trathan, P N; Goto, Y; Sato, K; Naito, Y; Takahashi, A

    2015-07-01

    The foraging strategy of many animals is thought to be determined by their past experiences. However, few empirical studies have investigated whether this is true in diving animals. We recorded three-dimensional movements and mouth-opening events from three Antarctic fur seals during their foraging trips to examine how they adapt their behaviour based on past experience--continuing to search for prey in the same area or moving to search in a different place. Each dive cycle was divided into a transit phase and a feeding phase. The linear horizontal distance travelled after feeding phases in each dive was affected by the mouth-opening rate during the previous 244 s, which typically covered two to three dive cycles. The linear distance travelled tended to be shorter when the mouth-opening rate in the previous 244 s was higher, i.e. seals tended to stay in the same areas with high prey-encounter rates. These results indicate that Antarctic fur seals follow decision-making strategies based on the past foraging experience over time periods longer than the immediately preceding dive.

  13. Methylphenidate remediates error-preceding activation of the default mode brain regions in cocaine addicted individuals

    PubMed Central

    Matuskey, David; Luo, Xi; Zhang, Sheng; Morgan, Peter T.; Abdelghany, Osama; Malison, Robert T.; Li, Chiang-shan R.

    2013-01-01

    Many previous studies suggest the potential of psychostimulants in improving cognitive functioning. Our earlier pharmacological brain imaging study showed that intravenous methylphenidate (MPH) improves inhibitory control by altering cortico-striato-thalamic activations in cocaine dependent (CD) individuals. Here we provide additional evidence for the effects of MPH in restoring cerebral activations during cognitive performance. Ten CD individuals performed a stop signal task (SST) during functional magnetic resonance imaging (fMRI) in two sessions, in which either MPH (0.5 mg/Kg BW) or saline was administered intravenously. In the SST, a frequent go signal instructs participants to make a speeded response and a less frequent stop signal instructs them to withhold the response. Our previous work described increased activation of the precuneus/posterior cingulate cortex and ventromedial prefrontal cortex – regions of the default mode network (DMN) – before participants committed a stop error in healthy control but not CD individuals (Bednarski et al., 2011). The current results showed that, compared to saline, MPH restored error-preceding activations of DMN regions in CD individuals. The extent of the changes in precuneus activity was correlated with MPH-elicited increase in systolic blood pressure. These findings suggest that the influence of MPH on cerebral activations may extend beyond cognitive control and provide additional evidence warranting future studies to investigate the neural mechanisms and physiological markers of the efficacy of agonist therapy in cocaine dependence. PMID:23973363

  14. Motor neurone acetylcholinesterase release precedes neurotoxicity caused by systemic administration of excitatory amino acids and strychnine.

    PubMed

    Rodríguez-Ithurralde, D; Maruri, A; Rodríguez, X

    1998-10-01

    We have proposed that neuronal overactivation by either stimulation of excitatory receptors or hypofunction of inhibitory circuits is a cause of excessive acetylcholinesterase (AChE) release, which, in turn, can contribute to ALS/MND pathogenesis. We investigated histochemical and histopathological changes in cell populations of the mouse spinal ventral horn upon in vivo stimulation of glutamate receptors with L-aspartate (ASP, 10-50 mg/kg, intraperitoneal: i.p.), or blockade of glycine receptors with strychnine (STRY, 2 mg/kg, i.p.). ASP in P4-P13 (postnatal age in days) but not in older mice, and STRY irrespective of age, provoked rapid, striking depletions of motor neurone AChE, and appearance of AChE activity in astrocytes. This was followed by recovery of the enzyme in most motor neurones, astrocyte activation and statistically significant changes in: brain macrophage infiltration, loss of interneurones and motor neurones and neuronophagic images including rosettes of glial cells surrounding a central 'ghost-like' motor neurone. Although AChE release preceded the neuropathology found, it is not known if its uptake is a cause of glial activation. However, it has been shown that the enzyme potentiates non-N-metyl-D-aspartate receptors identical to those that mediate astrocyte activation. AChE activity produces protons and choline, possible microglial activators. These are putative routes towards long-lasting neuropathology.

  15. Cognitive Declines Precede and Predict Functional Declines in Aging and Alzheimer’s Disease

    PubMed Central

    Zahodne, Laura B.; Manly, Jennifer J.; MacKay-Brandt, Anna; Stern, Yaakov

    2013-01-01

    Objective To investigate the temporal ordering of cognitive and functional declines separately in older adults with or without Alzheimer’s disease (AD). Design and Setting A community-based longitudinal study of aging and dementia in Northern Manhattan (Washington Heights/Hamilton Heights Inwood Columbia Aging Project) and a multicenter, clinic-based longitudinal study of prevalent AD at Columbia University Medical Center, Johns Hopkins School of Medicine, Massachusetts General Hospital, and the Hôpital de la Salpêtrière in Paris, France (the Predictors Study). Participants 3,443 initially non-demented older adults (612 with eventual incident dementia) and 517 patients with AD. Main Outcome Measures Cognitive measures included the modified Mini-Mental State Exam and composite scores of memory and language derived from a standardized neuropsychological battery. Function was measured with the Blessed Dementia Rating Scale, completed by the participant (in the sample of non-demented older adults) or an informant (in the sample of prevalent AD patients). Data were analyzed with autoregressive cross-lagged panel analysis. Results Cognitive scores more consistently predicted subsequent functional abilities than vice versa in non-demented older adults, participants with eventual incident dementia, and patients with prevalent AD. Conclusions Cognitive declines appear to precede and cause functional declines prior to and following dementia diagnosis. Standardized neuropsychological tests are valid predictors of later functional changes in both non-demented and demented older adults. PMID:24023894

  16. Localization suppression and fusion measure of the precedence effect in young children

    NASA Astrophysics Data System (ADS)

    Litovsky, Ruth; Godar, Shelly; Yu, Gongqiang

    2001-05-01

    This study investigated aspects of the precedence effect (PE) known as fusion and localization dominance in children 4-5 years of age. Stimuli were three, 25-ms noise bursts (2-ms rise/fall times) with 250-ms ISI. On PE conditions the lead stimulus was presented from one of six locations in azimuth, and the lag was at 0 deg. Lead-lag delays varied from 5 to 100 ms. Localization was measured using an identification paradigm. Fusion was measured separately whereby subjects reported whether a single auditory event or two auditory events were perceived. Children reported two sounds on 75% of trials (fusion threshold) at delays ranging from 15 to 35 ms. Below fusion thresholds, the localization of the lead was similar to that of single-source stimuli. Above fusion thresholds lead localization was significantly degraded, persisting out to 100 ms. Localization of the lag was poor at all delays on which it was reported as being heard. According to these results localization dominance (difficulty localizing the lag) in children persists at greater delays than fusion, which is consistent with findings obtained in adult subjects. The range of delays over which these effects are robust in children is longer than the range observed in adults.

  17. Strong and Anomalous Thermal Expansion Precedes the Thermosalient Effect in Dynamic Molecular Crystals

    NASA Astrophysics Data System (ADS)

    Panda, Manas K.; Centore, Roberto; Causà, Mauro; Tuzi, Angela; Borbone, Fabio; Naumov, Panče

    2016-07-01

    The ability of thermosalient solids, organic analogues of inorganic martensites, to move by rapid mechanical reconfiguration or ballistic event remains visually appealing and potentially useful, yet mechanistically elusive phenomenon. Here, with a material that undergoes both thermosalient and non-thermosalient phase transitions, we demonstrate that the thermosalient effect is preceded by anomalous thermal expansion of the unit cell. The crystal explosion occurs as sudden release of the latent strain accumulated during the anisotropic, exceedingly strong expansion of the unit cell with αa = 225.9 × 10‑6 K‑1, αb = 238.8 × 10‑6 K‑1 and αc = ‑290.0 × 10‑6 K‑1, the latter being the largest negative thermal expansivity observed for an organic compound thus far. The results point out to the occurence of the thermosalient effect in phase transitions as means to identify new molecular materials with strong positive and/or negative thermal expansion which prior to this work could only be discovered serendipitously.

  18. Tobacco use in silent film: precedents of modern-day substance use portrayals.

    PubMed

    St Romain, Theresa; Hawley, Suzanne R; Ablah, Elizabeth; Kabler, Bethany S; Molgaard, Craig A

    2007-12-01

    Much research has been done into tobacco use portrayals in film since the mid-twentieth century, but the earlier years of Hollywood history have been overlooked. Yet the first decades of the twentieth century saw annual per capita cigarette consumption increase from under 100 in 1900 upto 1,500 in 1930. The current study looks at frequency and context (gender, age range, socioeconomic status, type of portrayal) of tobacco use in 20 top-grossing silent films spanning the silent feature era (1915-1928). The sample averaged 23.31 tobacco uses per hour. Tobacco use was most often associated with positive characterizations, working/middle class status, masculinity, and youth. Previous research has verified the influence of the film industry on tobacco consumption in modern years, and this potential connection should not be ignored for the silent film era. Top-grossing silent films set a precedent for positive media portrayals of substance use that have persisted to the present day.

  19. Terrorist Attacks Escalate in Frequency and Fatalities Preceding Highly Lethal Attacks

    PubMed Central

    Martens, Andy; Sainudiin, Raazesh; Sibley, Chris G.; Schimel, Jeff; Webber, David

    2014-01-01

    Highly lethal terrorist attacks, which we define as those killing 21 or more people, account for 50% of the total number of people killed in all terrorist attacks combined, yet comprise only 3.5% of terrorist attacks. Given the disproportionate influence of these incidents, uncovering systematic patterns in attacks that precede and anticipate these highly lethal attacks may be of value for understanding attacks that exact a heavy toll on life. Here we examined whether the activity of terrorist groups escalates–both in the number of people killed per attack and in the frequency of attacks–leading up to highly lethal attacks. Analyses of terrorist attacks drawn from a state-of-the-art international terrorism database (The Global Terrorism Database) showed evidence for both types of escalation leading up to highly lethal attacks, though complexities to the patterns emerged as well. These patterns of escalation do not emerge among terrorist groups that never commit a highly lethal attack. PMID:24755753

  20. Insulin-induced localized lipoatrophy preceded by shingles (herpes zoster): a case report

    PubMed Central

    2014-01-01

    Introduction Localized involutional lipoatrophy of subcutaneous adipose tissue may develop due to subcutaneous injection of pharmaceutical preparations. The pathogenesis of this adverse drug reaction is unknown. The progression of localized involutional lipoatrophy ceases and occasionally it resolves after withdrawing the inducing agent. In case of localized involutional lipoatrophy due to subcutaneous insulin therapy, low-dose systemic corticosteroids may be curative despite ongoing insulin administration. Case presentation We report a recurrence of insulin-induced localized involutional lipoatrophy at the abdominal wall in a 57-year-old Caucasian woman with type-1 diabetes on continuous subcutaneous insulin infusion. The first episode of insulin-induced localized involutional lipoatrophy two years previously had been cured by oral prednisone. The recurrence was treated immediately with 10mg prednisone once daily for five months, and was cured thereafter. The insulin analog preparation (Humalog™) and the insulin pump equipment (Accu-Chek Spirit™) applied were the same during both episodes. Both episodes were preceded by a temporary disturbance of the immune balance (the first episode by vaccination, the second episode through shingles). Conclusions This case confirms that insulin-induced localized involutional lipoatrophy in type-1 diabetes can occur again, and can be cured by systemic corticosteroids. We suggest that temporary disturbance of the immune balance may trigger this transitory idiosyncratic reaction in a susceptible individual. PMID:24961832

  1. Remodeling of Glucose Metabolism Precedes Pressure Overload -Induced Left Ventricular Hypertrophy: Review of a Hypothesis

    PubMed Central

    Kundu, Bijoy K.; Zhong, Min; Sen, Shiraj; Davogustto, Giovanni; Keller, Susanna R.; Taegtmeyer, Heinrich

    2015-01-01

    When subjected to pressure overload, the ventricular myocardium shifts from fatty acids to glucose as its main source for energy provision and frequently increases its mass. Here, we review the evidence in support of the concept that metabolic remodeling, measured as increased myocardial glucose uptake using dynamic positron emission tomography (PET) with the glucose analogue 2-deoxy-2-[18F]-fluoro-D-glucose (FDG), precedes the onset of left ventricular hypertrophy (LVH) and heart failure. Consistent with this, early intervention with propranolol, which attenuates glucose uptake, prevents the maladaptive metabolic response and preserves cardiac function in vivo. We also review ex vivo studies suggesting a link between dysregulated myocardial glucose metabolism, intracellular accumulation of glucose 6-phosphate (G6P) and contractile dysfunction of the heart. G6P levels correlate with activation of mTOR (mechanistic target of rapamycin) and endoplasmic reticulum stress. This sequence of events could be prevented by pre-treatment with rapamycin (mTOR inhibition) or metformin (enzyme 5′-AMP-activated protein kinase activation ). In conclusion, we propose that metabolic imaging with FDG PET may provide a novel approach to guide the treatment of patients with hypertension-induced LVH. PMID:25791172

  2. Robust Endoplasmic Reticulum-Associated Degradation of Rhodopsin Precedes Retinal Degeneration

    PubMed Central

    Chiang, Wei-Chieh; Kroeger, Heike; Sakami, Sanae; Messah, Carissa; Yasumura, Douglas; Matthes, Michael T.; Coppinger, Judith A.; Palczewski, Krzysztof; LaVail, Matthew M.; Lin, Jonathan H.

    2014-01-01

    Rhodopsin is a G protein-coupled receptor essential for vision and rod photoreceptor viability. Disease-associated rhodopsin mutations, such as P23H rhodopsin, cause rhodopsin protein misfolding and trigger endoplasmic reticulum (ER) stress, activating the Unfolded Protein Response (UPR). The pathophysiologic effects of ER stress and UPR activation on photoreceptors are unclear. Here, by examining a P23H rhodopsin knock-in mouse, we found that the UPR IRE1 signaling pathway is strongly activated in misfolded rhodopsin-expressing photoreceptors. IRE1 significantly upregulated ER-associated protein degradation (ERAD), triggering pronounced P23H rhodopsin degradation. Rhodopsin protein loss occurred as soon as photoreceptors developed, preceding photoreceptor cell death. By contrast, IRE1 activation did not affect JNK signaling or rhodopsin mRNA levels. Interestingly, pro-apoptotic signaling from the PERK UPR pathway was also not induced. Our findings reveal that an early and significant pathophysiologic effect of ER stress in photoreceptors is the highly efficient elimination of misfolded rhodopsin protein. We propose that early disruption of rhodopsin protein homeostasis in photoreceptors could contribute to retinal degeneration. PMID:25270370

  3. A precedence effect resolves phantom sound source illusions in the parasitoid fly Ormia ochracea

    PubMed Central

    Lee, Norman; Elias, Damian O.; Mason, Andrew C.

    2009-01-01

    Localizing individual sound sources under reverberant environmental conditions can be a challenge when the original source and its acoustic reflections arrive at the ears simultaneously from different paths that convey ambiguous directional information. The acoustic parasitoid fly Ormia ochracea (Diptera: Tachinidae) relies on a pair of ears exquisitely sensitive to sound direction to localize the 5-kHz tone pulsatile calling song of their host crickets. In nature, flies are expected to encounter a complex sound field with multiple sources and their reflections from acoustic clutter potentially masking temporal information relevant to source recognition and localization. In field experiments, O. ochracea were lured onto a test arena and subjected to small random acoustic asymmetries between 2 simultaneous sources. Most flies successfully localize a single source but some localize a ‘phantom’ source that is a summed effect of both source locations. Such misdirected phonotaxis can be elicited reliably in laboratory experiments that present symmetric acoustic stimulation. By varying onset delay between 2 sources, we test whether hyperacute directional hearing in O. ochracea can function to exploit small time differences to determine source location. Selective localization depends on both the relative timing and location of competing sources. Flies preferred phonotaxis to a forward source. With small onset disparities within a 10-ms temporal window of attention, flies selectively localize the leading source while the lagging source has minimal influence on orientation. These results demonstrate the precedence effect as a mechanism to overcome phantom source illusions that arise from acoustic reflections or competing sources. PMID:19332794

  4. Inflammation and Atrophy Precede Prostate Neoplasia in PhIP Induced Rat Model

    SciTech Connect

    Borowsky, A D; Dingley, K; Ubick, E; Turteltaub, K; Cardiff, R D; DeVere-White, R

    2006-06-01

    2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine (PhIP) has been implicated as a major mutagenic heterocyclic amine in the human diet and is carcinogenic in the rat prostate. In order to validate PhIP induced rat prostate neoplasia as a model of human prostate cancer progression, we sought to study the earliest histologic and morphologic changes in the prostate and to follow the progressive changes over time. We fed 67 male Fischer F344 5 week old rats with PhIP (400 PPM) or control diets for 20 weeks, and then sacrificed animals for histomorphologic examination at age 25 weeks, 45 weeks, and 65 weeks. Animals treated with PhIP showed significantly more inflammation (P=.002 (25wk), >.001(45wk), .016(65wk)) and atrophy (P=.003(25wk), >.001(45wk), .006 (65wk)) in their prostate glands relative to controls. Prostatic intraepithelial neoplasia (PIN) occurred only in PhIP treated rats. PIN lesions arose in areas of glandular atrophy, most often in the ventral prostate. Atypical cells in areas of atrophy show loss of glutathione S-transferase pi immunostaining preceding development of PIN. None of the animals in this study developed invasive carcinomas differing from previous reports. Overall, these findings suggest that the pathogenesis of prostatic neoplasia in the PhIP treated rat prostate proceeds from inflammation to post-inflammatory proliferative atrophy to PIN.

  5. Augmented force output in skeletal muscle fibres of Xenopus following a preceding bout of activity.

    PubMed Central

    Bruton, J D; Westerblad, H; Katz, A; Lännergren, J

    1996-01-01

    1. The effect of a brief period of activity on subsequent isometric tetanic force production was investigated in single muscle fibres of Xenopus laevis. 2. Following a train of ten tetani separated by 4 s intervals, tetanic force was significantly augmented by about 10%. The tetanic force augmentation persisted for at least 15 min and then slowly subsided. A similar potentiation was seen following trains of five and twenty tetani. 3. During the period of tetanic force potentiation, tetanic calcium was reduced by more than 30%, and intracellular pH was reduced from 7.15 +/- 0.07 to 7.03 +/- 0.11 (n = 4). 4. Fibre swelling was greatest at 1 min and then subsided over 15-20 min and possibly accounted for a small part of the observed force potentiation. 5. A reduction in the inorganic phosphate (P1) concentration of more than 40% was found in fibres frozen in liquid nitrogen at the peak of force potentiation compared with resting fibres. 6. It is concluded that the augmentation of tetanic force found after a brief preceding bout of activity is due to a reduction in inorganic phosphate. This mechanism may underlie the improved performance observed in athletes after warm-up. Images Figure 2 PMID:8735706

  6. Stromal cell migration precedes hemopoietic repopulation of the bone marrow after irradiation

    SciTech Connect

    Werts, E.D.; Gibson, D.P.; Knapp, S.A.; DeGowin, R.L.

    1980-01-01

    Circulation of hemopoietic stem cells into an irradiated site has been thoroughly documented, but migration of stromal cells to repair radiation damage has not. We determined the radiosensitivity of mouse bone marrow stroma and evaluated stromal and hemopoietic repopulation in x-irradiated marrow. The D/sub 0/ for growth of colonies of marrow stromal cells (MSC) was 215 to 230 rad. Total-body irradiation (TB) obliterated marrow stromal and hemopoietic cells within 3 days. In contrast, 1 day after 1000 rad leg irradiation (LI), MSC rose to 80% of normal, but fell to 34% by 3 days and recovered to 72% by 30 days. However, femoral nucleated cells diminished to 20% by 3 days and recovered to 74% of normal by 30 days. Likewise, differentiated marrow cells and hemopoietic stem cells were initially depleted. With 1000 rad LI followed 3 h later by 1000 rad to the body while shielding the leg, MSC and femoral nucleated cells recovered to values intermediate between 1000 rad TB and 1000 rad LI. We concluded that: (1) the D/sub 0/ for MSC was 215 to 230 rad, (2) stromal repopulation preceded hemopoietic recovery, and (3) immigration of stromal cells from an unirradiated sanctuary facilitated hemopoietic repopulation of a heavily irradiated site.

  7. Ice Thickness Distribution and Bottom Topography in Beaufort Sea in Winter Preceding 2007 Ice Minimum

    NASA Astrophysics Data System (ADS)

    Wadhams, P.; Rodrigues, J.; Toberg, N.

    2008-12-01

    The unprecedented sea ice retreat in the Arctic Ocean (especially Beaufort Sea) during the summer of 2007 was characterised by exceptional bottom melting. We were able to characterise the thickness distribution of the sea ice during the preceding winter in parts of the Beaufort Sea which subsequently became completely ice-free, as well as in regions of heavier multi-year ice, by means of a transect in March 2007 using a submarine equipped with upward-looking and multi-beam sonar. The transect involved extensive survey work under the APLIS 2007 ice camp from which the SEDNA project (led by University of Alaska) subsequently took place. The upward sonar generated statistical properties of the ice thickness distribution which showed that the ice cover was sensitised for subsequent break-up under enhanced bottom melt because of (a) the prevalence of first-year ice which was unusually thin, (b) the relative absence of deep ridges, (c) the relative prevalence of first-year ridges which melt quickly through water percolation around ice blocks. This is in contrast to the structure of the ice thickness distribution in earlier years. The multi-beam sonar (with additional information from high-resolution studies of individual ridges by small AUVs in 2007 and 2008) yields special insight into the role played by ridge melt in the overall break-up process.

  8. Representational changes of latent strategies in rat medial prefrontal cortex precede changes in behaviour

    PubMed Central

    Powell, Nathaniel James; Redish, A. David

    2016-01-01

    The ability to change behavioural strategies in the face of a changing world has been linked to the integrity of medial prefrontal cortex (mPFC) function in several species. While recording studies have found that mPFC representations reflect the strategy being used, lesion studies suggest that mPFC is necessary for changing strategy. Here we examine the relationship between representational changes in mPFC and behavioural strategy changes in the rat. We found that on tasks with a forced change in reward criterion, strategy-related representational transitions in mPFC occurred after animals learned that the reward contingency had changed, but before their behaviour changed. On tasks in which animals made their own strategic decisions, representational transitions in mPFC preceded changes in behaviour. These results suggest that mPFC does not merely reflect the action–selection policy of the animal, but rather that mPFC processes information related to a need for a change in strategy. PMID:27653278

  9. Chemotherapy for cancer causes apoptosis that precedes hypoplasia in crypts of the small intestine in humans

    PubMed Central

    Keefe, D; Brealey, J; Goland, G; Cummins, A

    2000-01-01

    BACKGROUND AND AIMS—The mechanism of gastrointestinal damage (mucositis) induced by cancer chemotherapy remains uncertain. The aims of this study were to define the time course and mechanism of small intestinal damage following chemotherapy in humans.
METHODS—Patients receiving chemotherapy underwent upper gastrointestinal endoscopy (a maximum of two per patient) with duodenal biopsy prior to chemotherapy and again at 1, 3, 5, and 16 days after chemotherapy. Tissue was taken for morphometry, disaccharidase assays, electron microscopy, and for assessment of apoptosis using the Tdt mediated dUTP-biotin nick end labelling (TUNEL) method. Villus area, crypt length, and mitotic index were measured by a microdissection technique.
RESULTS—Apoptosis increased sevenfold in intestinal crypts at one day, and villus area, crypt length, mitotic count per crypt, and enterocyte height decreased at three days after chemotherapy. Disaccharidase activities remained unchanged. Electron microscopy showed increased open tight junctions of enterocytes at day 3, consistent with more immature cells. All indices improved by 16 days.
CONCLUSION—Small intestinal mucositis is associated with apoptosis in crypts that precedes hypoplastic villous atrophy and loss of enterocyte height.


Keywords: chemotherapy; mucositis; small intestine PMID:11034578

  10. SINE extinction preceded LINE extinction in sigmodontine rodents: implications for retrotranspositional dynamics and mechanisms.

    PubMed

    Rinehart, T A; Grahn, R A; Wichman, H A

    2005-01-01

    Short Interspersed Nuclear Elements, or SINEs, retrotranspose despite lacking protein-coding capability. It has been proposed that SINEs utilize enzymes produced in trans by Long Interspersed Nuclear Elements, or LINEs. Strong support for this hypothesis is found in LINE and SINE pairs that share sequence homology; however, LINEs and SINEs in primates and rodents are only linked by an insertion site motif. We have now profiled L1 LINE and B1 SINE activity in 24 rodent species including candidate taxa for the first documented L1 extinction. As expected, there was no evidence for recent activity of B1s in species that also lack L1 activity. However, B1 silencing appears to have preceded L1 extinction, since B1 activity is also lacking in the genus most closely related to those lacking active L1s despite the presence of active L1s in this genus. A second genus with active L1s but inactive B1s was also identified.

  11. Temporal changes in stress preceding the 2004-2008 eruption of Mount St. Helens, Washington

    USGS Publications Warehouse

    Lehto, H.L.; Roman, D.C.; Moran, S.C.

    2010-01-01

    The 2004-2008 eruption of Mount St. Helens (MSH), Washington, was preceded by a swarm of shallow volcano-tectonic earthquakes (VTs) that began on September 23, 2004. We calculated locations and fault-plane solutions (FPS) for shallow VTs recorded during a background period (January 1999 to July 2004) and during the early vent-clearing phase (September 23 to 29, 2004) of the 2004-2008 eruption. FPS show normal and strike-slip faulting during the background period and on September 23; strike-slip and reverse faulting on September 24; and a mixture of strike-slip, reverse, and normal faulting on September 25-29. The orientation of ??1 beneath MSH, as estimated from stress tensor inversions, was found to be sub-horizontal for all periods and oriented NE-SW during the background period, NW-SE on September 24, and NE-SW on September 25-29. We suggest that the ephemeral ~90?? change in ??1 orientation was due to intrusion and inflation of a NE-SW-oriented dike in the shallow crust prior to the eruption onset. ?? 2010 Elsevier B.V.

  12. BK viremia precedes hemorrhagic cystitis in children undergoing allogeneic hematopoietic stem cell transplantation.

    PubMed

    Laskin, Benjamin L; Denburg, Michelle; Furth, Susan; Diorio, Donna; Goebel, Jens; Davies, Stella M; Jodele, Sonata

    2013-08-01

    BK virus is associated with hemorrhagic cystitis after hematopoietic stem cell transplantation (HSCT), although evidence supporting a causal relationship remains limited. Although BK viruria is common after HSCT, BK viremia may better predict clinically significant cystitis, similar to its predictive value for nephropathy after kidney transplantation. We hypothesized that BK viremia would precede hemorrhagic cystitis in a cohort of 88 consecutive children prospectively enrolled to originally study thrombotic microangiopathy in the first 100 days after allogeneic HSCT. Cox regression models with time-varying covariates assessed the association between different BK viremia cutoffs and the development of hemorrhagic cystitis, defined as at least macroscopic hematuria. Subjects with a peak plasma BK viral load 1 to 9999 copies/mL had an adjusted hazard ratio of 4.2 (95% confidence interval (CI), 1.3 to 13.7) for the development of hemorrhagic cystitis. Those with peak BK viremia >100,000 copies/mL had an adjusted hazard ratio of 116.8 (95% CI, 12 to 1136) for cystitis. Other independent risk factors for hemorrhagic cystitis included age >7 years and HHV-6 viremia. Neither graft-versus-host disease nor achieving engraftment increased the risk for cystitis. If therapeutic strategies are found to be effective, these observations may support screening for BK viremia after HSCT, as currently recommended for other DNA viruses.

  13. Strong and Anomalous Thermal Expansion Precedes the Thermosalient Effect in Dynamic Molecular Crystals

    PubMed Central

    Panda, Manas K.; Centore, Roberto; Causà, Mauro; Tuzi, Angela; Borbone, Fabio; Naumov, Panče

    2016-01-01

    The ability of thermosalient solids, organic analogues of inorganic martensites, to move by rapid mechanical reconfiguration or ballistic event remains visually appealing and potentially useful, yet mechanistically elusive phenomenon. Here, with a material that undergoes both thermosalient and non-thermosalient phase transitions, we demonstrate that the thermosalient effect is preceded by anomalous thermal expansion of the unit cell. The crystal explosion occurs as sudden release of the latent strain accumulated during the anisotropic, exceedingly strong expansion of the unit cell with αa = 225.9 × 10−6 K−1, αb = 238.8 × 10−6 K−1 and αc = −290.0 × 10−6 K−1, the latter being the largest negative thermal expansivity observed for an organic compound thus far. The results point out to the occurence of the thermosalient effect in phase transitions as means to identify new molecular materials with strong positive and/or negative thermal expansion which prior to this work could only be discovered serendipitously. PMID:27403616

  14. Retinal neurodegeneration may precede microvascular changes characteristic of diabetic retinopathy in diabetes mellitus.

    PubMed

    Sohn, Elliott H; van Dijk, Hille W; Jiao, Chunhua; Kok, Pauline H B; Jeong, Woojin; Demirkaya, Nazli; Garmager, Allison; Wit, Ferdinand; Kucukevcilioglu, Murat; van Velthoven, Mirjam E J; DeVries, J Hans; Mullins, Robert F; Kuehn, Markus H; Schlingemann, Reinier Otto; Sonka, Milan; Verbraak, Frank D; Abràmoff, Michael David

    2016-05-10

    Diabetic retinopathy (DR) has long been recognized as a microvasculopathy, but retinal diabetic neuropathy (RDN), characterized by inner retinal neurodegeneration, also occurs in people with diabetes mellitus (DM). We report that in 45 people with DM and no to minimal DR there was significant, progressive loss of the nerve fiber layer (NFL) (0.25 μm/y) and the ganglion cell (GC)/inner plexiform layer (0.29 μm/y) on optical coherence tomography analysis (OCT) over a 4-y period, independent of glycated hemoglobin, age, and sex. The NFL was significantly thinner (17.3 μm) in the eyes of six donors with DM than in the eyes of six similarly aged control donors (30.4 μm), although retinal capillary density did not differ in the two groups. We confirmed significant, progressive inner retinal thinning in streptozotocin-induced "type 1" and B6.BKS(D)-Lepr(db)/J "type 2" diabetic mouse models on OCT; immunohistochemistry in type 1 mice showed GC loss but no difference in pericyte density or acellular capillaries. The results suggest that RDN may precede the established clinical and morphometric vascular changes caused by DM and represent a paradigm shift in our understanding of ocular diabetic complications. PMID:27114552

  15. The effect of preceding sonar emission on temporal integration in the bat, Megaderma lyra.

    PubMed

    Weissenbacher, Petra; Wiegrebe, Lutz; Kössl, Manfred

    2002-03-01

    The present study investigated whether and to which extent temporal integration in bats is influenced by echolocation behavior. One way to quantify temporal integration is to measure the detection threshold for a pair of short tone pips as a function of the temporal separation between the pips. To asses the effect of preceding sonar emission on temporal integration in the bat, Megaderma lyra, the detection thresholds of identical subjects were measured in a passive as well as in an active paradigm. In the passive paradigm, the presentation of the pip pairs was independent of the bats' sonar emissions; in the active paradigm, the presentation was triggered by the bats' sonar emissions. In both cases, the bats showed a very short integration time in the range of 100-200 micros. Moreover, the comparison of the active and passive results within each bat revealed no systematic differences in the two measuring paradigms. These results indicate that temporal integration is not influenced by echolocation. Simulations with a computer model of cochlear filtering based on measurements of M. lyra cochlear tuning suggest that the perceptual temporal integration is dominated by the integration of the cochlear filters.

  16. Patterns of Theta Activity in Limbic Anxiety Circuit Preceding Exploratory Behavior in Approach-Avoidance Conflict

    PubMed Central

    Jacinto, Luis R.; Cerqueira, João J.; Sousa, Nuno

    2016-01-01

    Theta oscillations within the hippocampus-amygdala-medial prefrontal cortex (HPC-AMY-mPFC) circuit have been consistently implicated in the regulation of anxiety behaviors, including risk-assessment. To study if theta activity during risk-assessment was correlated with exploratory behavior in an approach/avoidance paradigm we recorded simultaneous local field potentials from this circuit in rats exploring the elevated-plus maze (EPM). Opposing patterns of power variations in the ventral hippocampus (vHPC), basolateral amygdala (BLA), and prelimbic (PrL) mPFC, but not in the dorsal hippocampus (dHPC), during exploratory risk-assessment of the open arms preceded further exploration of the open arms or retreat back to the safer closed arms. The same patterns of theta power variations in the HPC-BLA-mPFC(PrL) circuit were also displayed by animals submitted to chronic unpredictable stress protocol known to induce an anxious state. Diverging patterns of vHPC-mPFC(PrL) theta coherence were also significantly correlated with forthcoming approach or avoidance behavior in the conflict situation in both controls and stressed animals; interestingly, vHPC-BLA, and BLA-mPFC(PrL) theta coherence correlated with future behavior only in stressed animals, underlying the pivotal role of the amygdala on the stress response. PMID:27713693

  17. Preceding standard therapy is the likely cause of MDS after autotransplants for multiple myeloma.

    PubMed

    Govindarajan, R; Jagannath, S; Flick, J T; Vesole, D H; Sawyer, J; Barlogie, B; Tricot, G

    1996-11-01

    Myelodysplastic syndromes (MDS) and acute myeloid leukaemia (AML) have been reported after autologous transplantation (AT) for lymphoma. It is not clear whether myeloablative therapy used in conjunction with autologous transplantation contributes to the development of MDS/AML or whether the conventional chemotherapy preceding the transplant, and administered over a prolonged period, causes these secondary malignancies. To address this issue, we examined 188 patients with multiple myeloma (MM) who had received AT. 71 patients with no more than one cycle of standard chemotherapy were enrolled in our Total Therapy program, designed to avoid exposure to alkylating agents prior to peripheral blood stem cell mobilization (group 1). The median duration of pretransplant therapy in group 1 was 7.6 months and significantly shorter than the 24 months of 117 patients (group 2) with more prolonged conventional therapy (P = 0.0001). All seven patients developing MDS post-transplantation belonged to group 2 (P = 0.02); the median durations from initial therapy and first transplant were 66 months (range 38-86) and 24 months (range 9-39), respectively. Our findings provide evidence that prolonged standard-dose alkylating agent therapy prior to transplantation, rather than autotransplant-supported myeloablative treatment, is associated with development of MDS/AML. Stem cell damaging alkylator treatment should be avoided, not to compromise PBSC collection, but also to reduce the risk of treatment-related MDS/AML.

  18. Microarray Analyses and Comparisons of Upper or Lower Flanks of Rice Shoot Base Preceding Gravitropic Bending

    PubMed Central

    Zang, Aiping; Chen, Haiying; Dou, Xianying; Jin, Jing; Cai, Weiming

    2013-01-01

    Gravitropism is a complex process involving a series of physiological pathways. Despite ongoing research, gravitropism sensing and response mechanisms are not well understood. To identify the key transcripts and corresponding pathways in gravitropism, a whole-genome microarray approach was used to analyze transcript abundance in the shoot base of rice (Oryza sativa sp. japonica) at 0.5 h and 6 h after gravistimulation by horizontal reorientation. Between upper and lower flanks of the shoot base, 167 transcripts at 0.5 h and 1202 transcripts at 6 h were discovered to be significantly different in abundance by 2-fold. Among these transcripts, 48 were found to be changed both at 0.5 h and 6 h, while 119 transcripts were only changed at 0.5 h and 1154 transcripts were changed at 6 h in association with gravitropism. MapMan and PageMan analyses were used to identify transcripts significantly changed in abundance. The asymmetric regulation of transcripts related to phytohormones, signaling, RNA transcription, metabolism and cell wall-related categories between upper and lower flanks were demonstrated. Potential roles of the identified transcripts in gravitropism are discussed. Our results suggest that the induction of asymmetrical transcription, likely as a consequence of gravitropic reorientation, precedes gravitropic bending in the rice shoot base. PMID:24040303

  19. Cost estimation for solid waste management in industrialising regions - Precedents, problems and prospects

    SciTech Connect

    Parthan, Shantha R.; Milke, Mark W.; Wilson, David C.; Cocks, John H.

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer We review cost estimation approaches for solid waste management. Black-Right-Pointing-Pointer Unit cost method and benchmarking techniques used in industrialising regions (IR). Black-Right-Pointing-Pointer Variety in scope, quality and stakeholders makes cost estimation challenging in IR. Black-Right-Pointing-Pointer Integrate waste flow and cost models using cost functions to improve cost planning. - Abstract: The importance of cost planning for solid waste management (SWM) in industrialising regions (IR) is not well recognised. The approaches used to estimate costs of SWM can broadly be classified into three categories - the unit cost method, benchmarking techniques and developing cost models using sub-approaches such as cost and production function analysis. These methods have been developed into computer programmes with varying functionality and utility. IR mostly use the unit cost and benchmarking approach to estimate their SWM costs. The models for cost estimation, on the other hand, are used at times in industrialised countries, but not in IR. Taken together, these approaches could be viewed as precedents that can be modified appropriately to suit waste management systems in IR. The main challenges (or problems) one might face while attempting to do so are a lack of cost data, and a lack of quality for what data do exist. There are practical benefits to planners in IR where solid waste problems are critical and budgets are limited.

  20. Different Neural Patterns Are Associated with Trials Preceding Inhibitory Errors in Children with and without Attention-Deficit/Hyperactivity Disorder

    ERIC Educational Resources Information Center

    Spinelli, Simona; Joel, Suresh; Nelson, Tess E.; Vasa, Roma A.; Pekar, James J.; Mostofsky, Stewart H.

    2011-01-01

    Objective: Attention-deficit/hyperactivity disorder (ADHD) is associated with difficulty inhibiting impulsive, hyperactive, and off-task behavior. However, no studies have examined whether a distinct pattern of brain activity precedes inhibitory errors in typically developing (TD) children and children with ADHD. In healthy adults, increased…