Science.gov

Sample records for active stressed lap

  1. New design deforming controlling system of the active stressed lap

    NASA Astrophysics Data System (ADS)

    Ying, Li; Wang, Daxing

    2008-07-01

    A 450mm diameter active stressed lap has been developed in NIAOT by 2003. We design a new lap in 2007. This paper puts on emphases on introducing the new deforming control system of the lap. Aiming at the control characteristic of the lap, a new kind of digital deforming controller is designed. The controller consists of 3 parts: computer signal disposing, motor driving and force sensor signal disposing. Intelligent numeral PID method is applied in the controller instead of traditional PID. In the end, the result of new deformation are given.

  2. Experimental dynamic deformation analysis of active stressed lap.

    PubMed

    Zhao, Hongshen; Li, Xiaojin; Fan, Bin; Zeng, Zhige

    2016-02-20

    We introduce a method to measure the dynamic surface deformation of an active stressed lap for fabricating a 4  mf/1.5  mirror. Lap surface accuracy working in some typical deformation velocities is put forward. Experimental results indicate that dynamic lap surface accuracy is worse than that of a static surface, and dynamic surface accuracy gets worse if deformation velocity increases, while the difference of lap surface error RMS is less than 1 μm. An optimization of the processing strategy is feasible through changing the deformation velocity of the active stressed lap depending on the processing schedule. After optimizing the grinding and polishing strategy, efficiency is expected to have a significant increase. PMID:26906568

  3. Deformation verification and surface improvement of active stressed lap for 4  m-class primary mirror fabrication.

    PubMed

    Zhao, Hongshen; Li, Xiaojin; Fan, Bin; Zeng, Zhige

    2015-04-01

    The surface shape accuracy of the active stressed lap impacts the performance of grinding and polishing in the fabrication of large mirrors. We introduce a model of active stressed lap for the fabrication of a 4 m f/1.5 mirror based on finite element analysis (FEA), and the lap surface accuracy achieves RMS<1.8  μm in the FEA method. Using the lap surface measurement system, experimental verification is put forward, and the RMS of the measured lap surface is within 2 μm in practice. A general improvement in lap surface accuracy using the Zernike polynomial is shown. After compensating the calculation errors, the lap surface accuracy is improved by 8%-23%, and achieves RMS<1.5  μm, which is appropriate for practical grinding and polishing. PMID:25967173

  4. Cashier/Checker Learning Activity Packets (LAPs).

    ERIC Educational Resources Information Center

    Oklahoma State Dept. of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    Twenty-four learning activity packets (LAPs) are provided for six areas of instruction in a cashier/checker program. Section A, Orientation, contains an LAP on exploring the job of cashier-checker. Section B, Operations, has nine LAPs, including those on operating the cash register, issuing trading stamps, and completing the cash register balance…

  5. New mathematical model for error reduction of stressed lap

    NASA Astrophysics Data System (ADS)

    Zhao, Pu; Yang, Shuming; Sun, Lin; Shi, Xinyu; Liu, Tao; Jiang, Zhuangde

    2016-05-01

    Stressed lap, compared to traditional polishing methods, has high processing efficiency. However, this method has disadvantages in processing nonsymmetric surface errors. A basic-function method is proposed to calculate parameters for a stressed-lap polishing system. It aims to minimize residual errors and is based on a matrix and nonlinear optimization algorithm. The results show that residual root-mean-square could be >15% after one process for classical trefoil error. The surface period errors close to the lap diameter were removed efficiently, up to 50% material removal.

  6. Use of two-dimensional transmission photoelastic models to study stresses in double-lap bolted joints: Load transfer and stresses in the inner lap

    NASA Technical Reports Server (NTRS)

    Hyer, M. W.

    1980-01-01

    The determination of the stress distribution in the inner lap of double-lap, double-bolt joints using photoelastic models of the joint is discussed. The principal idea is to fabricate the inner lap of a photoelastic material and to use a photoelastically sensitive material for the two outer laps. With this setup, polarized light transmitted through the stressed model responds principally to the stressed inner lap. The model geometry, the procedures for making and testing the model, and test results are described.

  7. Learning Activity Package, Chemistry I, (LAP) Study 29.

    ERIC Educational Resources Information Center

    Jones, Naomi

    Presented is a Learning Activity Package (LAP) study concerned with carbon and its compounds. This LAP in chemistry includes a rationale for studying the chemical element of carbon, a list of student objectives (stated in behavioral terms), of activities (reading, laboratory experiments, model construction, etc.), a two-page worksheet, a…

  8. How lamina-associated polypeptide 1 (LAP1) activates Torsin

    PubMed Central

    Sosa, Brian A; Demircioglu, F Esra; Chen, James Z; Ingram, Jessica; Ploegh, Hidde L; Schwartz, Thomas U

    2014-01-01

    Lamina-associated polypeptide 1 (LAP1) resides at the nuclear envelope and interacts with Torsins, poorly understood endoplasmic reticulum (ER)-localized AAA+ ATPases, through a conserved, perinuclear domain. We determined the crystal structure of the perinuclear domain of human LAP1. LAP1 possesses an atypical AAA+ fold. While LAP1 lacks canonical nucleotide binding motifs, its strictly conserved arginine 563 is positioned exactly where the arginine finger of canonical AAA+ ATPases is found. Based on modeling and electron microscopic analysis, we propose that LAP1 targets Torsin to the nuclear envelope by forming an alternating, heterohexameric (LAP1-Torsin)3 ring, in which LAP1 acts as the Torsin activator. The experimental data show that mutation of arginine 563 in LAP1 reduces its ability to stimulate TorsinA ATPase hydrolysis. This knowledge may help scientists understand the etiology of DYT1 primary dystonia, a movement disorder caused by a single glutamate deletion in TorsinA. DOI: http://dx.doi.org/10.7554/eLife.03239.001 PMID:25149450

  9. Learning Activity Package, Physical Science 92, LAPs 1-9.

    ERIC Educational Resources Information Center

    Williams, G. J.

    This set of nine teacher-prepared Learning Activity Packages (LAPs) for individualized instruction in physical science covers the topics of scientific equipment and procedures; measure of time, length, area, and volume; water; oxygen and oxidation; atmospheric pressure; motion; machines; carbon; and light and sound. Each unit contains a rationale…

  10. Learning Activity Package, Algebra 124, LAPs 46-55.

    ERIC Educational Resources Information Center

    Holland, Bill

    A series of 10 teacher-prepared Learning Activity Packages (LAPs) in advanced algebra and trigonometry, these units cover absolute value, inequalities, exponents, radicals, and complex numbers; functions; higher degree equations and the derivative; the trigonometric functions; graphs and applications of the trigonometric functions; sequences and…

  11. Auto Mechanics I. Learning Activity Packets (LAPs). Section C--Engine.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This document contains five learning activity packets (LAPs) that outline the study activities for the "engine" instructional area for an Auto Mechanics I course. The five LAPs cover the following topics: basic engine principles, cooling system, engine lubrication system, exhaust system, and fuel system. Each LAP contains a cover sheet that…

  12. Auto Mechanics I. Learning Activity Packets (LAPs). Section A--Orientation and Safety.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This document contains seven learning activity packets (LAPs) that outline the study activities for the orientation and safety instructional area for an Auto Mechanics I course. The seven LAPs cover the following topics: orientation, safety, hand tools, arc welding, oxyacetylene cutting, oxyacetylene fusion welding, and oxyacetylene braze welding.…

  13. A neural-fuzzy model with confidence measure for controlled stressed-lap surface shape presentation

    NASA Astrophysics Data System (ADS)

    Chen, Minyou; Wan, Yongjian; Wu, Fan; Xie, Kaigui; Wang, Mingyu; Fan, Bin

    2009-05-01

    In computer controlled large aspheric mirror polishing process, it is crucially important to build an accurate stressed-lap surface model for shape control. It is desirable to provide a practical measure of prediction confidence to access the reliability of the resulting models. To build a reliable prediction model for representing the surface shape of stressed lap polishing process in large aperture and highly aspheric optical surface, this paper proposed a predictive model with its own confidence interval estimate based on a fuzzy neural network. The calculation of confidence interval accounts for the training data distribution and accuracy of the trained model with the given input-output data. Simulation results show that the proposed confidence interval estimation reflects the data distribution and extrapolation correctly, and works well in high-dimensional sparse data set of the detected stressed lap surface shape changes. The original data from the micro-displacement sensor matrix were used to train the neural network model. The experiment results showed that the proposed model can represent the surface shape of the stressed-lap accurately and facilitate the computer controlled optical polishing process.

  14. A two-dimensional stress analysis of single lap joints subjected to external bending moments

    SciTech Connect

    Sawa, Toshiyuki; Nakano, Katsuyuki; Toratani, Hiroshi

    1995-11-01

    The stress distribution of single lap adhesive joints subjected to external bending moments are analyzed as a three-body contact problem by using a two-dimensional theory of elasticity. In the analysis, two similar adherends and an adhesive are replaced by finite strips, respectively. In the numerical calculations, the effects of the ratio of Young;s modulus of adherends to that of adhesive and the adhesive thickness on the stress distribution at the interface are examined. As the results, it is seen that the stress singularity causes at the edges of the interfaces and the peel stress at the edges of the interface increases with a decrease of Young`s modulus of the adherends. In addition, photoelastic experiments are carried out. A fairly good agreement is seen between the analytical and the experimental results.

  15. Pseudomonas putida Fis Binds to the lapF Promoter In Vitro and Represses the Expression of LapF

    PubMed Central

    Lahesaare, Andrio; Moor, Hanna; Kivisaar, Maia; Teras, Riho

    2014-01-01

    The biofilm matrix of the rhizospheric bacterium Pseudomonas putida consists mainly of a proteinaceous component. The two largest P. putida proteins, adhesins LapA and LapF, are involved in biofilm development but prevail in different developmental stages of the biofilm matrix. LapA is abundant in the initial stage of biofilm formation whereas LapF is found in the mature biofilm. Although the transcriptional regulation of the adhesins is not exhaustively studied, some factors that can be involved in their regulation have been described. For example, RpoS, the major stress response sigma factor, activates, and Fis represses LapF expression. This study focused on the LapF expression control by Fis. Indeed, using DNase I footprint analysis a Fis binding site Fis-F2 was located 150 bp upstream of the lapF gene coding sequence. The mapped 5′ end of the lapF mRNA localized the promoter to the same region, overlapping with the Fis binding site Fis-F2. Monitoring the lapF promoter activity by a β-galactosidase assay revealed that Fis overexpression causes a 4-fold decrease in the transcriptional activity. Furthermore, mutations that diminished Fis binding to the Fis-F2 site abolished the repression of the lapF promoter. Thus, these data suggest that Fis is involved in the biofilm regulation via repression of LapF expression. PMID:25545773

  16. Lapping slurry

    DOEpatents

    Simandl, Ronald F.; Upchurch, Victor S.; Leitten, Michael E.

    1999-01-01

    Improved lapping slurries provide for easier and more thorough cleaning of alumina workpieces, as well as inhibit corrosion of the lapping table and provide for easier cleaning of the lapping equipment. The unthickened lapping slurry comprises abrasive grains such as diamond abrasive dispersed in a carrier comprising water, glycerine, and triethanolamine. The thickened lapping slurry comprises abrasive grains such as diamond abrasive dispersed in a carrier comprising water, glycerine, triethanolamine, a water soluble silicate, and acid.

  17. Lapping slurry

    DOEpatents

    Simandl, R.F.; Upchurch, V.S.; Leitten, M.E.

    1999-01-05

    Improved lapping slurries provide for easier and more thorough cleaning of alumina work pieces, as well as inhibit corrosion of the lapping table and provide for easier cleaning of the lapping equipment. The unthickened lapping slurry comprises abrasive grains such as diamond abrasive dispersed in a carrier comprising water, glycerine, and triethanolamine. The thickened lapping slurry comprises abrasive grains such as diamond abrasive dispersed in a carrier comprising water, glycerine, triethanolamine, a water soluble silicate, and acid. 1 fig.

  18. Learning Activity Package, Biology, LAPs 20, 30, 31, 32, and 33.

    ERIC Educational Resources Information Center

    Rhoden, Bruce

    Included is a set of five teacher-prepared Learning Activity Packages (LAPs) for individualized instruction in topics in biology. The units cover the topics of genetic continuity, methods of investigation, cell biology, genetics, and animal physiology. Each unit contains a rationale for the material; a list of behavioral objectives for the unit; a…

  19. Learning Activity Package, Algebra 93-94, LAPs 12-22.

    ERIC Educational Resources Information Center

    Evans, Diane

    A set of 11 teacher-prepared Learning Activity Packages (LAPs) in beginning algebra, these units cover sets, properties of operations, operations over real numbers, open expressions, solution sets of equations and inequalities, equations and inequalities with two variables, solution sets of equations with two variables, exponents, factoring and…

  20. Learning Activity Package, Physical Science. LAP Numbers 5, 6, and 7.

    ERIC Educational Resources Information Center

    Williams, G. J.

    These three units of the Learning Activity Packages (LAPs) for individualized instruction in physical science cover the physical and chemical properties of water, dehydration of crystals, solutions, acidity, strong and weak bases, neutral properties of salts, amorphous forms of carbon, hydrocarbons, and petroleum products. Each unit contains a…

  1. Learning Activity Package, Physical Science. LAP Numbers 8, 9, 10, and 11.

    ERIC Educational Resources Information Center

    Williams, G. J.

    These four units of the Learning Activity Packages (LAPs) for individualized instruction in physical science cover nuclear reactions, alpha and beta particles, atomic radiation, medical use of nuclear energy, fission, fusion, simple machines, Newton's laws of motion, electricity, currents, electromagnetism, Oersted's experiment, sound, light,…

  2. Learning Activity Package, Chemistry I. LAP Numbers 22, 23, 24, 25, 26, 27, and 28.

    ERIC Educational Resources Information Center

    Jones, Naomi

    As a set of seven Learning Activity Packages (LAPs) for individualized instruction in chemistry, the units cover the unit system, matter, energy, atomic structures, chemical formulas, physical states of matter, solutions and suspensions, ionization, acids, bases, and salts. Each unit contains a rationale for the material; a list of behavioral…

  3. Learning Activity Package, Physical Science. LAP Numbers 1, 2, 3, and 4.

    ERIC Educational Resources Information Center

    Williams, G. J.

    These four units of the Learning Activity Packages (LAPs) for individualized instruction in physical science cover measuring techniques, operations of instruments, metric system heat, matter, energy, elements, atomic numbers, isotopes, molecules, mixtures, compounds, physical and chemical properties, liquids, solids, and gases. Each unit contains…

  4. Stress analysis of the cracked lap shear specimens: An ASTM round robin

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.

    1986-01-01

    This ASTM Round Robin was conducted to evaluate the state of the art in stress analysis of adhesively bonded joint specimens. Specifically, the participants were asked to calculate the strain-energy-release rate for two different geometry cracked lap shear (CLS) specimens at four different debond lengths. The various analytical techniques consisted of 2- and 3-dimensional finite element analysis, beam theory, plate theory, and a combination of beam theory and finite element analysis. The results were examined in terms of the total strain-energy-release rate and the mode I to mode II ratio as a function of debond length for each specimen geometry. These results basically clustered into two groups: geometric linear or geometric nonlinear analysis. The geometric nonlinear analysis is required to properly analyze the CLS specimens. The 3-D finite element analysis gave indications of edge closure plus some mode III loading. Each participant described his analytical technique and results. Nine laboratories participated.

  5. Stress analysis of the cracked-lap-shear specimen - An ASTM round-robin

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.

    1987-01-01

    This ASTM Round Robin was conducted to evaluate the state of the art in stress analysis of adhesively bonded joint specimens. Specifically, the participants were asked to calculate the strain-energy-release rate for two different geometry cracked lap shear (CLS) specimens at four different debond lengths. The various analytical techniques consisted of 2- and 3-dimensional finite element analysis, beam theory, plate theory, and a combination of beam theory and finite element analysis. The results were examined in terms of the total strain-energy-release rate and the mode I to mode II ratio as a function of debond length for each specimen geometry. These results basically clustered into two groups: geometric linear or geometric nonlinear analysis. The geometric nonlinear analysis is required to properly analyze the CLS specimens. The 3-D finite element analysis gave indications of edge closure plus some mode III loading. Each participant described his analytical technique and results. Nine laboratories participated.

  6. Learning Activity Package, Social Studies 124, LAPs 29 Through 34.

    ERIC Educational Resources Information Center

    Franklin, Mary Ann

    A set of five teacher-prepared Learning Activity Packages for individualized instruction on western civilization at the twelfth grade level includes the following units: Establishment of Western Civilization; Middle Period of Western Civilization; Islam and the Saracenic Civilization; the Renaissance and Reformation; and Modern Western…

  7. Learning Activity Package, Social Studies 112, LAPs 17 Through 25.

    ERIC Educational Resources Information Center

    Burgdorf, Jane

    A set of nine teacher-prepared Learning Activity Packages for individualized instruction in United States history at the eleventh grade level includes the following topics: New World Settlement and Colonial Growth; American Revolution and the New Nation; Developing an Effective National Government; The Growth of Nationalism and Democracy…

  8. Residual Stresses and Tensile Properties of Friction Stir Welded AZ31B-H24 Magnesium Alloy in Lap Configuration

    NASA Astrophysics Data System (ADS)

    Naik, Bhukya Srinivasa; Cao, Xinjin; Wanjara, Priti; Friedman, Jacob; Chen, Daolun

    2015-08-01

    AZ31B-H24 Mg alloy sheets with a thickness of 2 mm were friction stir welded in lap configuration using two tool rotational rates of 1000 and 1500 rpm and two welding speeds of 10 and 20 mm/s. The residual stresses in the longitudinal and transverse directions of the weldments were determined using X-ray diffraction. The shear tensile behavior of the lap joints was evaluated at low [233 K (-40 °C)], room [298 K (25 °C)], and elevated [453 K (180 °C)] temperatures. The failure load was highest for the lower heat input condition that was obtained at a tool rotational rate of 1000 rpm and a welding speed of 20 mm/s for all the test temperatures, due to the smaller hooking height, larger effective sheet thickness, and lower tensile residual stresses, as compared to the other two welding conditions that were conducted at a higher tool rotational rate or lower welding speed. The lap joints usually fractured on the advancing side of the top sheet near the interface between the thermo-mechanically affected zone and the stir zone. Elevated temperature testing of the weld assembled at a tool rotational rate of 1000 rpm and a welding speed of 20 mm/s led to the failure along the sheet interface in shear fracture mode due to the high integrity of the joint that exhibited large plastic deformation and higher total energy absorption.

  9. Research on the design of surface acquisition system of active lap based on FPGA and FX2LP

    NASA Astrophysics Data System (ADS)

    Zhao, Hongshen; Li, Xiaojin; Fan, Bin; Zeng, Zhige

    2014-08-01

    In order to research the dynamic surface shape changes of active lap during the processing, this paper introduces a dynamic surface shape acquisition system of active lap using FPGA and USB communication. This system consists of high-precision micro-displacement sensor array, acquisition board, PC computer composition, and acquisition circuit board includes six sub-boards based on FPGA, a hub-board based on FPGA and USB communication. A sub-board is responsible for a number of independent channel sensors' data acquisition; hub-board is responsible for creating encoder simulation tools to active lap deformation control system with location information, sending synchronization information to latch the sensor data in all of the sub-boards for a time, while addressing the sub-boards to gather the sensor data in each sub-board one by one and transmitting all the sensor data together with location information via the USB chip FX2LP to the host computer. Experimental results show that the system is capable of fixing the location and speed of active lap, meanwhile the control of surface transforming and dynamic surface data acquisition at a certain location in the processing is implemented.

  10. Assembly of Lipopolysaccharide in Escherichia coli Requires the Essential LapB Heat Shock Protein*

    PubMed Central

    Klein, Gracjana; Kobylak, Natalia; Lindner, Buko; Stupak, Anna; Raina, Satish

    2014-01-01

    Here, we describe two new heat shock proteins involved in the assembly of LPS in Escherichia coli, LapA and LapB (lipopolysaccharide assembly protein A and B). lapB mutants were identified based on an increased envelope stress response. Envelope stress-responsive pathways control key steps in LPS biogenesis and respond to defects in the LPS assembly. Accordingly, the LPS content in ΔlapB or Δ(lapA lapB) mutants was elevated, with an enrichment of LPS derivatives with truncations in the core region, some of which were pentaacylated and exhibited carbon chain polymorphism. Further, the levels of LpxC, the enzyme that catalyzes the first committed step of lipid A synthesis, were highly elevated in the Δ(lapA lapB) mutant. Δ(lapA lapB) mutant accumulated extragenic suppressors that mapped either to lpxC, waaC, and gmhA, or to the waaQ operon (LPS biosynthesis) and lpp (Braun's lipoprotein). Increased synthesis of either FabZ (3-R-hydroxymyristoyl acyl carrier protein dehydratase), slrA (novel RpoE-regulated non-coding sRNA), lipoprotein YceK, toxin HicA, or MurA (UDP-N-acetylglucosamine 1-carboxyvinyltransferase) suppressed some of the Δ(lapA lapB) defects. LapB contains six tetratricopeptide repeats and, at the C-terminal end, a rubredoxin-like domain that was found to be essential for its activity. In pull-down experiments, LapA and LapB co-purified with LPS, Lpt proteins, FtsH (protease), DnaK, and DnaJ (chaperones). A specific interaction was also observed between WaaC and LapB. Our data suggest that LapB coordinates assembly of proteins involved in LPS synthesis at the plasma membrane and regulates turnover of LpxC, thereby ensuring balanced biosynthesis of LPS and phospholipids consistent with its essentiality. PMID:24722986

  11. Assembly of lipopolysaccharide in Escherichia coli requires the essential LapB heat shock protein.

    PubMed

    Klein, Gracjana; Kobylak, Natalia; Lindner, Buko; Stupak, Anna; Raina, Satish

    2014-05-23

    Here, we describe two new heat shock proteins involved in the assembly of LPS in Escherichia coli, LapA and LapB (lipopolysaccharide assembly protein A and B). lapB mutants were identified based on an increased envelope stress response. Envelope stress-responsive pathways control key steps in LPS biogenesis and respond to defects in the LPS assembly. Accordingly, the LPS content in ΔlapB or Δ(lapA lapB) mutants was elevated, with an enrichment of LPS derivatives with truncations in the core region, some of which were pentaacylated and exhibited carbon chain polymorphism. Further, the levels of LpxC, the enzyme that catalyzes the first committed step of lipid A synthesis, were highly elevated in the Δ(lapA lapB) mutant. Δ(lapA lapB) mutant accumulated extragenic suppressors that mapped either to lpxC, waaC, and gmhA, or to the waaQ operon (LPS biosynthesis) and lpp (Braun's lipoprotein). Increased synthesis of either FabZ (3-R-hydroxymyristoyl acyl carrier protein dehydratase), slrA (novel RpoE-regulated non-coding sRNA), lipoprotein YceK, toxin HicA, or MurA (UDP-N-acetylglucosamine 1-carboxyvinyltransferase) suppressed some of the Δ(lapA lapB) defects. LapB contains six tetratricopeptide repeats and, at the C-terminal end, a rubredoxin-like domain that was found to be essential for its activity. In pull-down experiments, LapA and LapB co-purified with LPS, Lpt proteins, FtsH (protease), DnaK, and DnaJ (chaperones). A specific interaction was also observed between WaaC and LapB. Our data suggest that LapB coordinates assembly of proteins involved in LPS synthesis at the plasma membrane and regulates turnover of LpxC, thereby ensuring balanced biosynthesis of LPS and phospholipids consistent with its essentiality.

  12. Lap seat belt injuries.

    PubMed

    Hingston, G R

    1996-08-01

    Over a 4 month period, three patients presented acutely to Whangarei Area Hospital after receiving severe abdominal injuries caused directly by lap seat belts. They were involved in road traffic crashes and were all seated in the middle rear seat of the car. The aim of this paper is to alert people to the injuries that can occur from two point lap belts. To this end, the patients and injuries sustained are described and a review of the literature is presented.

  13. Analysis of adhesively bonded composite lap joints

    SciTech Connect

    Tong, L.; Kuruppu, M.; Kelly, D.

    1994-12-31

    A new nonlinear formulation is developed for the governing equations for the shear and peel stresses in adhesively bonded composite double lap joints. The new formulation allows arbitrary nonlinear stress-strain characteristics in both shear and peel behavior. The equations are numerically integrated using a shooting technique and Newton-Raphson method behind a user friendly interface. The failure loads are predicted by utilizing the maximum stress criterion, interlaminar delamination and the energy density failure criteria. Numerical examples are presented to demonstrate the effect of the nonlinear adhesive behavior on the stress distribution and predict the failure load and the associated mode.

  14. Lap belt injuries in children.

    PubMed

    McGrath, N; Fitzpatrick, P; Okafor, I; Ryan, S; Hensey, O; Nicholson, A J

    2010-01-01

    The use of adult seat belts without booster seats in young children may lead to severe abdominal, lumbar or cervical spine and head and neck injuries. We describe four characteristic cases of lap belt injuries presenting to a tertiary children's hospital over the past year in addition to a review of the current literature. These four cases of spinal cord injury, resulting in significant long-term morbidity in the two survivors and death in one child, arose as a result of lap belt injury. These complex injuries are caused by rapid deceleration characteristic of high impact crashes, resulting in sudden flexion of the upper body around the fixed lap belt, and consequent compression of the abdominal viscera between the lap belt and spine. This report highlights the dangers of using lap belts only without shoulder straps. Age-appropriate child restraint in cars will prevent these injuries.

  15. Adhesive-bonded scarf and stepped-lap joints

    NASA Technical Reports Server (NTRS)

    Hart-Smith, L. J.

    1973-01-01

    Continuum mechanics solutions are derived for the static load-carrying capacity of scarf and stepped-lap adhesive-bonded joints. The analyses account for adhesive plasticity and adherend stiffness imbalance and thermal mismatch. The scarf joint solutions include a simple algebraic formula which serves as a close lower bound, within a small fraction of a per cent of the true answer for most practical geometries and materials. Digital computer programs were developed and, for the stepped-lap joints, the critical adherend and adhesive stresses are computed for each step. The scarf joint solutions exhibit grossly different behavior from that for double-lap joints for long overlaps inasmuch as that the potential bond shear strength continues to increase with indefinitely long overlaps on the scarf joints. The stepped-lap joint solutions exhibit some characteristics of both the scarf and double-lap joints. The stepped-lap computer program handles arbitrary (different) step lengths and thickness and the solutions obtained have clarified potentially weak design details and the remedies. The program has been used effectively to optimize the joint proportions.

  16. Electromechanical behaviour of REBCO tape lap splices under transverse compressive loading

    NASA Astrophysics Data System (ADS)

    Grether, A.; Scheuerlein, C.; Ballarino, A.; Bottura, L.

    2016-07-01

    We have studied the influence of transverse compressive stress on the resistance and critical current (I c ) of soldered REBCO tape lap splices. Internal contact resistances dominate the overall REBCO lap splice resistances. Application of transverse compressive stress up to 250 MPa during the resistance measurements does not alter the resistance and I c of the soldered REBCO splices that were studied. The resistance of unsoldered REBCO tape lap splices depends strongly on the contact pressure. At a transverse compressive stress of 100 MPa, to which Roebel cables are typically exposed in high field magnets, the crossover splice contact resistance is comparable to the internal tape resistances.

  17. C/EBPβ-LAP*/LAP Expression Is Mediated by RSK/eIF4B-Dependent Signalling and Boosted by Increased Protein Stability in Models of Monocytic Differentiation

    PubMed Central

    Christmann, Martin; Friesenhagen, Judith; Westphal, Andreas; Pietsch, Daniel; Brand, Korbinian

    2015-01-01

    The transcription factor C/EBPβ plays a key role in monocytic differentiation and inflammation. Its small isoform LIP is associated with proliferation at early premonocytic developmental stages and regulated via mTOR-dependent signalling. During later stages of (pre)monocytic differentiation there is a considerable increase in the large C/EBPβ isoforms LAP*/LAP which inhibit proliferation thus supporting terminal differentiation. Here, we showed in different models of monocytic differentiation that this dramatic increase in the LAP*/LAP protein and LAP/LIP ratio was accompanied by an only modest/retarded mRNA increase suggesting an important role for (post)translational mechanisms. We found that LAP*/LAP formation was induced via MEK/RSK-dependent cascades, whereas mTOR/S6K1 were not involved. Remarkably, LAP*/LAP expression was dependent on phosphorylated eIF4B, an acceleratory protein of RNA helicase eIF4A. PKR inhibition reduced the expression of eIF4B and C/EBPβ in an eIF2α-independent manner. Furthermore, under our conditions a marked stabilisation of LAP*/LAP protein occurred, accompanied by reduced chymotrypsin-like proteasome/calpain activities and increased calpastatin levels. Our study elucidates new signalling pathways inducing LAP*/LAP expression and indicates new alternative PKR functions in monocytes. The switch from mTOR- to RSK-mediated signalling to orchestrate eIF4B-dependent LAP*/LAP translation, accompanied by increased protein stability but only small mRNA changes, may be a prototypical example for the regulation of protein expression during selected processes of differentiation/proliferation. PMID:26646662

  18. Global-Local Finite Element Analysis of Bonded Single-Lap Joints

    NASA Technical Reports Server (NTRS)

    Kilic, Bahattin; Madenci, Erdogan; Ambur, Damodar R.

    2004-01-01

    Adhesively bonded lap joints involve dissimilar material junctions and sharp changes in geometry, possibly leading to premature failure. Although the finite element method is well suited to model the bonded lap joints, traditional finite elements are incapable of correctly resolving the stress state at junctions of dissimilar materials because of the unbounded nature of the stresses. In order to facilitate the use of bonded lap joints in future structures, this study presents a finite element technique utilizing a global (special) element coupled with traditional elements. The global element includes the singular behavior at the junction of dissimilar materials with or without traction-free surfaces.

  19. P-LAP/IRAP-induced cell proliferation and glucose uptake in endometrial carcinoma cells via insulin receptor signaling

    PubMed Central

    Shibata, Kiyosumi; Kajiyama, Hiroaki; Ino, Kazuhiko; Nawa, Akihiro; Nomura, Seiji; Mizutani, Shigehiko; Kikkawa, Fumitaka

    2007-01-01

    Background Hyperglycemia or hyperinsulinemia contributes to poorer endometrial cancer survival. It was shown that P-LAP/IRAP translocates to the plasma membrane in response to insulin stimulation. Recently, we demonstrated that P-LAP/IRAP is associated with a poor prognosis in endometrial adenocarcinoma patients. The aim of this study was to examine whether the malignant potential of endometrial cancer enhanced by P-LAP/IRAP is due to increased glucose uptake via the P-LAP/IRAP-mediated activation of insulin signaling. Methods We transfected P-LAP/IRAP cDNA into A-MEC cells (endometrial adenocarcinoma cell line), and A-MEC-LAP cells expressed a remarkably high level of GLUT4 proteins. Results 3H-2-deoxyglucose uptake which responds to insulin in A-MEC-LAP cells was significantly higher than that of A-MEC-pc cells. A-MEC-LAP cells exhibited a significant growth-stimulatory effect compared to A-MEC-pc cells. A-MEC-LAP cells expressed a remarkably high level of p85PI3K protein compared to A-MEC-pc cells, and showed a higher degree of AKT phosphorylation by insulin stimulation. Conclusion In summary, P-LAP/IRAP was involved in the increasing malignant potential of endometrial cancer mediated by insulin. P-LAP/IRAP was suggested to be a potential new target of molecular-targeted therapy for endometrial cancer. PMID:17233921

  20. Additive manufacturing of tools for lapping glass

    NASA Astrophysics Data System (ADS)

    Williams, Wesley B.

    2013-09-01

    Additive manufacturing technologies have the ability to directly produce parts with complex geometries without the need for secondary processes, tooling or fixtures. This ability was used to produce concave lapping tools with a VFlash 3D printer from 3D Systems. The lapping tools were first designed in Creo Parametric with a defined constant radius and radial groove pattern. The models were converted to stereolithography files which the VFlash used in building the parts, layer by layer, from a UV curable resin. The tools were rotated at 60 rpm and used with 120 grit and 220 grit silicon carbide lapping paste to lap 0.750" diameter fused silica workpieces. The samples developed a matte appearance on the lapped surface that started as a ring at the edge of the workpiece and expanded to the center. This indicated that as material was removed, the workpiece radius was beginning to match the tool radius. The workpieces were then cleaned and lapped on a second tool (with equivalent geometry) using a 3000 grit corundum aluminum oxide lapping paste, until a near specular surface was achieved. By using lapping tools that have been additively manufactured, fused silica workpieces can be lapped to approach a specified convex geometry. This approach may enable more rapid lapping of near net shape workpieces that minimize the material removal required by subsequent polishing. This research may also enable development of new lapping tool geometry and groove patterns for improved loose abrasive finishing.

  1. Fiber networks amplify active stress

    NASA Astrophysics Data System (ADS)

    Lenz, Martin; Ronceray, Pierre; Broedersz, Chase

    Large-scale force generation is essential for biological functions such as cell motility, embryonic development, and muscle contraction. In these processes, forces generated at the molecular level by motor proteins are transmitted by disordered fiber networks, resulting in large-scale active stresses. While fiber networks are well characterized macroscopically, this stress generation by microscopic active units is not well understood. I will present a comprehensive theoretical study of force transmission in these networks. I will show that the linear, small-force response of the networks is remarkably simple, as the macroscopic active stress depends only on the geometry of the force-exerting unit. In contrast, as non-linear buckling occurs around these units, local active forces are rectified towards isotropic contraction and strongly amplified. This stress amplification is reinforced by the networks' disordered nature, but saturates for high densities of active units. I will show that our predictions are quantitatively consistent with experiments on reconstituted tissues and actomyosin networks, and that they shed light on the role of the network microstructure in shaping active stresses in cells and tissue.

  2. Material characterization of structural adhesives in the lap shear mode

    NASA Technical Reports Server (NTRS)

    Sancaktar, E.; Schenck, S. C.

    1983-01-01

    A general method for characterizing structual adhesives in the bonded lap shear mode is proposed. Two approaches in the form of semiempirical and theoretical approaches are used. The semiempirical approach includes Ludwik's and Zhurkov's equations to describe respectively, the failure stresses in the constant strain rate and constant stress loading modes with the inclusion of the temperature effects. The theoretical approach is used to describe adhesive shear stress-strain behavior with the use of viscoelastic or nonlinear elastic constitutive equations. Two different model adhesives are used in the single lap shear mode with titanium adherends. These adhesives (one of which was developed at NASA Langley Research Center) are currently considered by NASA for possible aerospace applications. Use of different model adhesives helps in assessment of the generality of the method.

  3. Tubular lap joints for wind turbine applications

    SciTech Connect

    Reedy, E.D. Jr.; Guess, T.R.

    1990-01-01

    A combined analytical/experimental study of the strength of thick- walled, adhesively bonded PMMA-to-aluminum and E-glass/epoxy composite-to-aluminum tubular lap joints under axial load has been conducted. Test results include strength and failure mode data. Moreover, strain gages placed along the length of the outer tubular adherend characterize load transfer from one adherend to the other. The strain gage data indicate that load transfer is nonuniform and that the relatively compliant PMMA has the shorter load transfer length. Strains determined by a finite element analysis of the tested joints are in excellent agreement with those measured. Calculated bond stresses are highest in the region of observed failure, and extensive bond yielding is predicted in the E- glass/epoxy composite-to-aluminum joint prior to joint failure. 4 refs., 13 figs., 1 tab.

  4. Insights: A LAP on Moles: Teaching an Important Concept.

    ERIC Educational Resources Information Center

    Ihde, John

    1985-01-01

    Describes a learning activity packet (LAP) designed to help students understand the basic concept of the mole as a chemical unit; know relationships between the mole and atomic weights in the periodic table; and solve basic conversion problems involving moles, atoms, and molecules. (JN)

  5. Loose abrasive slurries for optical glass lapping

    SciTech Connect

    Neauport, Jerome; Destribats, Julie; Maunier, Cedric; Ambard, Chrystel; Cormont, Philippe; Pintault, B.; Rondeau, Olivier

    2010-10-20

    Loose abrasive lapping is widely used to prepare optical glass before its final polishing. We carried out a comparison of 20 different slurries from four different vendors. Slurry particle sizes and morphologies were measured. Fused silica samples were lapped with these different slurries on a single side polishing machine and characterized in terms of surface roughness and depth of subsurface damage (SSD). Effects of load, rotation speed, and slurry concentration during lapping on roughness, material removal rate, and SSD were investigated.

  6. Pediatric lap belt injuries: care and prevention.

    PubMed

    Shoemaker, B L; Ose, M

    1997-01-01

    Motor vehicle collisions are the leading cause of death from injury during childhood. As children outgrow their toddler car seats, they are often restrained by two-point lap belts, which are fashioned for adult body proportions. Those children restrained by two-point lap belts are at risk for intraabdominal and spinal injury during an auto collision. This article explores the mechanisms of injury and identification of "lap belt syndrome." Aspects of nursing care and prevention strategies will be discussed. A case study illustrates and summarizes the cogent aspects of lap belt related injury and child/family care.

  7. Quadruple Lap Shear Processing Evaluation

    NASA Technical Reports Server (NTRS)

    Thornton, Tony N.; McCool, A. (Technical Monitor)

    2000-01-01

    The Thiokol, Science and Engineering Huntsville Operations (SEHO) Laboratory has previously experienced significant levels of variation in testing Quadruple Lap Shear (QLS) specimens. The QLS test is used at Thiokol / Utah for the qualification of Reusable Solid Rocket Motor (RSRM) nozzle flex bearing materials. A test was conducted to verify that process changes instituted by SEHO personnel effectively reduced variability, even with normal processing variables introduced. A test matrix was designed to progress in a series of steps; the first establishing a baseline, then introducing additional solvents or other variables. Variables included normal test plan delay times, pre-bond solvent hand-wipes and contaminants. Each condition tested utilized standard QLS hardware bonded with natural rubber, two separate technicians and three replicates. This paper will report the results and conclusions of this investigation.

  8. Nonlinear Analysis of Bonded Composite Single-LAP Joints

    NASA Technical Reports Server (NTRS)

    Oterkus, E.; Barut, A.; Madenci, E.; Smeltzer, S. S.; Ambur, D. R.

    2004-01-01

    This study presents a semi-analytical solution method to analyze the geometrically nonlinear response of bonded composite single-lap joints with tapered adherend edges under uniaxial tension. The solution method provides the transverse shear and normal stresses in the adhesive and in-plane stress resultants and bending moments in the adherends. The method utilizes the principle of virtual work in conjunction with von Karman s nonlinear plate theory to model the adherends and the shear lag model to represent the kinematics of the thin adhesive layer between the adherends. Furthermore, the method accounts for the bilinear elastic material behavior of the adhesive while maintaining a linear stress-strain relationship in the adherends. In order to account for the stiffness changes due to thickness variation of the adherends along the tapered edges, their in-plane and bending stiffness matrices are varied as a function of thickness along the tapered region. The combination of these complexities results in a system of nonlinear governing equilibrium equations. This approach represents a computationally efficient alternative to finite element method. Comparisons are made with corresponding results obtained from finite-element analysis. The results confirm the validity of the solution method. The numerical results present the effects of taper angle, adherend overlap length, and the bilinear adhesive material on the stress fields in the adherends, as well as the adhesive, of a single-lap joint

  9. LAPS Grid generation and adaptation

    NASA Astrophysics Data System (ADS)

    Pagliantini, Cecilia; Delzanno, Gia Luca; Guo, Zehua; Srinivasan, Bhuvana; Tang, Xianzhu; Chacon, Luis

    2011-10-01

    LAPS uses a common-data framework in which a general purpose grid generation and adaptation package in toroidal and simply connected domains is implemented. The initial focus is on implementing the Winslow/Laplace-Beltrami method for generating non-overlapping block structured grids. This is to be followed by a grid adaptation scheme based on Monge-Kantorovich optimal transport method [Delzanno et al., J. Comput. Phys,227 (2008), 9841-9864], that equidistributes application-specified error. As an initial set of applications, we will lay out grids for an axisymmetric mirror, a field reversed configuration, and an entire poloidal cross section of a tokamak plasma reconstructed from a CMOD experimental shot. These grids will then be used for computing the plasma equilibrium and transport in accompanying presentations. A key issue for Monge-Kantorovich grid optimization is the choice of error or monitor function for equi-distribution. We will compare the Operator Recovery Error Source Detector (ORESD) [Lapenta, Int. J. Num. Meth. Eng,59 (2004) 2065-2087], the Tau method and a strategy based on the grid coarsening [Zhang et al., AIAA J,39 (2001) 1706-1715] to find an ``optimal'' grid. Work supported by DOE OFES.

  10. Selective expression of latency-associated peptide (LAP) and IL-1 receptor type I/II (CD121a/CD121b) on activated human FOXP3+ regulatory T cells allows for their purification from expansion cultures

    PubMed Central

    Andersson, John; Hardwick, Donna; Bebris, Lolita; Illei, Gabor G.

    2009-01-01

    Although adoptive transfer of regulatory T cells (Foxp3+ Tregs) has proven to be efficacious in the prevention and treatment of autoimmune diseases and graft-versus-host disease in rodents, a major obstacle for the use of Treg immunotherapy in humans is the difficulty of obtaining a highly purified preparation after ex vivo expansion. We have identified latency-associated peptide (LAP) and IL-1 receptor type I and II (CD121a/CD121b) as unique cell-surface markers that distinguish activated Tregs from activated FOXP3− and FOXP3+ non-Tregs. We show that it is feasible to sort expanded FOXP3+ Tregs from non-Tregs with the use of techniques for magnetic bead cell separation based on expression of these 3 markers. After separation, the final product contains greater than 90% fully functional FOXP3+ Tregs. This novel protocol should facilitate the purification of Tregs for both cell-based therapies as well as detailed studies of human Treg function in health and disease. PMID:19299332

  11. The Structure and Enzyme Characteristics of a Recombinant Leucine Aminopeptidase rLap1 from Aspergillus sojae and Its Application in Debittering.

    PubMed

    Huang, Wei-Qian; Zhong, Li-Fen; Meng, Zhi-Zhong; You, Zi-Juan; Li, Jia-Zhou; Luo, Xiao-Chun

    2015-09-01

    A leucine aminopeptidase Lap1 was cloned from Aspergillus sojae GIM3.30. The truncated Lap1 without a signal peptide was over-expressed in P. pastoris, and the enzymatic characteristics of recombinant Lap1 (rLap1) were tested. The rLap1 was about 36.7 kDa with an optimal pH 8.0 and optimal temperature 50 °C for substrate Leu-p-nitroanilide and it sustained 50 % activity after 1 h incubation at 50 °C. The activity of rLap1 was significantly inhibited by EDTA, whereas Co(2+), Mn(2+), and Ca(2+) ions, but not Zn(2+) ions, restored its activity. rLap1 showed the highest activity against Arg-pNA and then Leu-, Lys-, Met-, and Phe-pNA. The 3D structure of rLap1 showed it had a conserved functional charge/dipole complex and a hydrogen bond network of Zn2-D179-S228-Q177-D229-S158 around its active center. An acidic Asp residue was found at the bottom of the substrate binding pocket, which explains its preference for basic N-terminal amino acid substrates such as Arg and Lys. rLap1 improved the degree of hydrolysis of casein and soy protein hydrolysates and also decreased their bitterness, indicating its potential utility in food production.

  12. Fracture analysis of multi-site cracking in fuselage lap joints

    NASA Astrophysics Data System (ADS)

    Beuth, J. L.; Hutchinson, J. W.

    1994-09-01

    A two-dimensional plane stress elastic fracture mechanics analysis of a cracked lap joint fastened by rigid pins is presented and results are applied to the problem of multi-site damage (MSD) in riveted lap joints of aircraft fuselage skins. Two problems are addressed, the problem of equal length MSD cracks and the problem of alternating length MSD cracks. For the problem of equal length cracks, two models of rivet/skin interactions are studied and the role of residual stresses due to the riveting process is explored. Stress intensity factors are obtained as a function of normalized crack length. Also, the load distribution among rivet rows and the compliance change of the joint due to MSD cracking are obtained. For the problem of alternating length cracks, attention is focussed on how load is distributed between columns of rivets and how this load shedding can alter crack tip stress intensity factors. The equal and alternating length crack analyses reveal no clear-cut mechanism to explain the relative uniformity of fatigue cracks emerging from lap joint rivet holes in actual aircraft and in mechanical lap joint tests.

  13. 49 CFR 230.30 - Lap-joint seam boilers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Inspection and Repair § 230.30 Lap-joint seam boilers. Every boiler having lap-joint longitudinal seams... 49 Transportation 4 2013-10-01 2013-10-01 false Lap-joint seam boilers. 230.30 Section...

  14. 49 CFR 230.30 - Lap-joint seam boilers.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Inspection and Repair § 230.30 Lap-joint seam boilers. Every boiler having lap-joint longitudinal seams... 49 Transportation 4 2014-10-01 2014-10-01 false Lap-joint seam boilers. 230.30 Section...

  15. 49 CFR 230.30 - Lap-joint seam boilers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Inspection and Repair § 230.30 Lap-joint seam boilers. Every boiler having lap-joint longitudinal seams... 49 Transportation 4 2012-10-01 2012-10-01 false Lap-joint seam boilers. 230.30 Section...

  16. 49 CFR 230.30 - Lap-joint seam boilers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Inspection and Repair § 230.30 Lap-joint seam boilers. Every boiler having lap-joint longitudinal seams... 49 Transportation 4 2011-10-01 2011-10-01 false Lap-joint seam boilers. 230.30 Section...

  17. 49 CFR 230.30 - Lap-joint seam boilers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Inspection and Repair § 230.30 Lap-joint seam boilers. Every boiler having lap-joint longitudinal seams... 49 Transportation 4 2010-10-01 2010-10-01 false Lap-joint seam boilers. 230.30 Section...

  18. Thermal shock testing of lapped optical glass

    NASA Astrophysics Data System (ADS)

    Zhang, Yingrui; Wu, Yuansun; Liu, Han; Lambropoulos, John C.

    2007-09-01

    We have measured and modeled the thermal shock fracture of the commercially available BK-7 borosilicate crown optical glass as a function of surface finish prior to thermal shock testing. For surfaces lapped with alumina abrasives in the range 5 μm to 40 μm, the critical temperature drop for fracture in thin disk samples increases with diminishing abrasive size, and changes from 123.7+/-1.1 °C (for surfaces lapped with 40 μm abrasives) to 140.2+/-2.8 °C (for surfaces lapped with 5 μm abrasives.) We correlate the measured thermal shock (critical) temperature drop with the glass thermal and mechanical properties, including the fracture toughness, and the depth of surface cracks induced by the lapping process. We distinguish between "severe" and "mild" thermal shock conditions in terms of the applicable heat transfer coefficient and Biot number. We estimate that the depth of the strength controlling cracks on the edge of the disk samples was about 55-70 μm.

  19. Lap Shear Testing of Candidate Radiator Panel Adhesives

    NASA Technical Reports Server (NTRS)

    Ellis, David; Briggs, Maxwell; McGowan, Randy

    2013-01-01

    During testing of a subscale radiator section used to develop manufacturing techniques for a full-scale radiator panel, the adhesive bonds between the titanium heat pipes and the aluminum face sheets failed during installation and operation. Analysis revealed that the thermal expansion mismatch between the two metals resulted in relatively large shear stresses being developed even when operating the radiator at moderate temperatures. Lap shear testing of the adhesive used in the original joints demonstrated that the two-part epoxy adhesive fell far short of the strength required. A literature review resulted in several candidate adhesives being selected for lap shear joint testing at room temperature and 398 K, the nominal radiator operating temperature. The results showed that two-part epoxies cured at room and elevated temperatures generally did not perform well. Epoxy film adhesives cured at elevated temperatures, on the other hand, did very well with most being sufficiently strong to cause yielding in the titanium sheet used for the joints. The use of an epoxy primer generally improved the strength of the joint. Based upon these results, a new adhesive was selected for the second subscale radiator section.

  20. Oral Hygiene. Instructor's Packet. Learning Activity Package.

    ERIC Educational Resources Information Center

    Hime, Kirsten

    This instructor's packet accompanies the learning activity package (LAP) on oral hygiene. Contents included in the packet are a time sheet, suggested uses for the LAP, an instruction sheet, final LAP reviews, a final LAP review answer key, suggested activities, additional resources (student handouts), student performance checklists for both…

  1. Grooming. Instructor's Packet. Learning Activity Package.

    ERIC Educational Resources Information Center

    Stark, Pamela

    This instructor's packet accompanies the learning activity package (LAP) on grooming. Contents included in the packet are a time sheet, suggested uses for the LAP, an instruction sheet, final LAP reviews, a final LAP review answer key, suggested activities, an additional resources list, and student completion cards to issue to students as an…

  2. Cardiovascular reactivity, stress, and physical activity

    PubMed Central

    Huang, Chun-Jung; Webb, Heather E.; Zourdos, Michael C.; Acevedo, Edmund O.

    2013-01-01

    Psychological stress has been proposed as a major contributor to the progression of cardiovascular disease (CVD). Acute mental stress can activate the sympathetic-adrenal-medullary (SAM) axis, eliciting the release of catecholamines (NE and EPI) resulting in the elevation of heart rate (HR) and blood pressure (BP). Combined stress (psychological and physical) can exacerbate these cardiovascular responses, which may partially contribute to the elevated risk of CVD and increased proportionate mortality risks experienced by some occupations (e.g., firefighting and law enforcement). Studies have supported the benefits of physical activity on physiological and psychological health, including the cardiovascular response to acute stress. Aerobically trained individuals exhibit lower sympathetic nervous system (e.g., HR) reactivity and enhanced cardiovascular efficiency (e.g., lower vascular reactivity and decreased recovery time) in response to physical and/or psychological stress. In addition, resistance training has been demonstrated to attenuate cardiovascular responses and improve mental health. This review will examine stress-induced cardiovascular reactivity and plausible explanations for how exercise training and physical fitness (aerobic and resistance exercise) can attenuate cardiovascular responses to stress. This enhanced functionality may facilitate a reduction in the incidence of stroke and myocardial infarction. Finally, this review will also address the interaction of obesity and physical activity on cardiovascular reactivity and CVD. PMID:24223557

  3. Stress and Androgen Activity During Fetal Development.

    PubMed

    Barrett, Emily S; Swan, Shanna H

    2015-10-01

    Prenatal stress is known to alter hypothalamic-pituitary-adrenal axis activity, and more recent evidence suggests that it may also affect androgen activity. In animal models, prenatal stress disrupts the normal surge of testosterone in the developing male, whereas in females, associations differ by species. In humans, studies show that (1) associations between prenatal stress and child outcomes are often sex-dependent, (2) prenatal stress predicts several disorders with notable sex differences in prevalence, and (3) prenatal exposure to stressful life events may be associated with masculinized reproductive tract development and play behavior in girls. In this minireview, we examine the existing literature on prenatal stress and androgenic activity and present new, preliminary data indicating that prenatal stress may also modify associations between prenatal exposure to diethylhexyl phthalate, (a synthetic, antiandrogenic chemical) and reproductive development in infant boys. Taken together, these data support the hypothesis that prenatal exposure to both chemical and nonchemical stressors may alter sex steroid pathways in the maternal-placental-fetal unit and ultimately alter hormone-dependent developmental endpoints. PMID:26241065

  4. Stress and Androgen Activity During Fetal Development

    PubMed Central

    Swan, Shanna H.

    2015-01-01

    Prenatal stress is known to alter hypothalamic-pituitary-adrenal axis activity, and more recent evidence suggests that it may also affect androgen activity. In animal models, prenatal stress disrupts the normal surge of testosterone in the developing male, whereas in females, associations differ by species. In humans, studies show that (1) associations between prenatal stress and child outcomes are often sex-dependent, (2) prenatal stress predicts several disorders with notable sex differences in prevalence, and (3) prenatal exposure to stressful life events may be associated with masculinized reproductive tract development and play behavior in girls. In this minireview, we examine the existing literature on prenatal stress and androgenic activity and present new, preliminary data indicating that prenatal stress may also modify associations between prenatal exposure to diethylhexyl phthalate, (a synthetic, antiandrogenic chemical) and reproductive development in infant boys. Taken together, these data support the hypothesis that prenatal exposure to both chemical and nonchemical stressors may alter sex steroid pathways in the maternal-placental-fetal unit and ultimately alter hormone-dependent developmental endpoints. PMID:26241065

  5. Material characterization of structural adhesives in the lap shear mode. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Schenck, S. C.; Sancaktar, E.

    1983-01-01

    A general method for characterizing structural adhesives in the bonded lap shear mode is proposed. Two approaches in the form of semi-empirical and theoretical approaches are used. The semi-empirical approach includes Ludwik's and Zhurkov's equations to describe respectively, the failure stresses in the constant strain rate and constant stress loading modes with the inclusion of the temperature effects. The theoretical approach is used to describe adhesive shear stress-strain behavior with the use of viscoelastic or nonlinear elastic constitutive equations. Three different model adhesives are used in the simple lap shear mode with titanium adherends. These adhesives (one of which was developed at NASA Langley Research Center) are currently considered by NASA for possible aerospace applications. Use of different model adhesives helps in assessment of the generality of the method.

  6. Chronic variable stress activates hematopoietic stem cells

    PubMed Central

    Courties, Gabriel; Dutta, Partha; Iwamoto, Yoshiko; Zaltsman, Alex; von zur Muhlen, Constantin; Bode, Christoph; Fricchione, Gregory L.; Denninger, John; Lin, Charles P.; Vinegoni, Claudio; Libby, Peter; Swirski, Filip K.; Weissleder, Ralph; Nahrendorf, Matthias

    2014-01-01

    Exposure to psychosocial stress is a risk factor for many diseases, including atherosclerosis1,2. While incompletely understood, interaction between the psyche and the immune system provides one potential mechanism linking stress and disease inception and progression. Known crosstalk between the brain and immune system includes the hypothalamic–pituitary–adrenal axis, which centrally drives glucocorticoid production in the adrenal cortex, and the sympathetic–adrenal–medullary axis, which controls stress–induced catecholamine release in support of the fight–or–flight reflex3,4. It remains unknown however if chronic stress changes hematopoietic stem cell activity. Here we show that stress increases proliferation of these most primitive progenitors, giving rise to higher levels of disease–promoting inflammatory leukocytes. We found that chronic stress induced monocytosis and neutrophilia in humans. While investigating the source of leukocytosis in mice, we discovered that stress activates upstream hematopoietic stem cells. Sympathetic nerve fibers release surplus noradrenaline, which uses the β3 adrenergic receptor to signal bone marrow niche cells to decrease CXCL12 levels. Consequently, elevated hematopoietic stem cell proliferation increases output of neutrophils and inflammatory monocytes. When atherosclerosis–prone ApoE−/− mice encounter chronic stress, accelerated hematopoiesis promotes plaque features associated with vulnerable lesions that cause myocardial infarction and stroke in humans. PMID:24952646

  7. Large-scale Advanced Propfan (LAP) program

    NASA Technical Reports Server (NTRS)

    Sagerser, D. A.; Ludemann, S. G.

    1985-01-01

    The propfan is an advanced propeller concept which maintains the high efficiencies traditionally associated with conventional propellers at the higher aircraft cruise speeds associated with jet transports. The large-scale advanced propfan (LAP) program extends the research done on 2 ft diameter propfan models to a 9 ft diameter article. The program includes design, fabrication, and testing of both an eight bladed, 9 ft diameter propfan, designated SR-7L, and a 2 ft diameter aeroelastically scaled model, SR-7A. The LAP program is complemented by the propfan test assessment (PTA) program, which takes the large-scale propfan and mates it with a gas generator and gearbox to form a propfan propulsion system and then flight tests this system on the wing of a Gulfstream 2 testbed aircraft.

  8. Analysis of lap times in international swimming competitions.

    PubMed

    Robertson, Eileen; Pyne, David; Hopkins, Will; Anson, Judith

    2009-02-15

    Swimming performances were analysed for the top 16 finishers (semi-finalists, finalists) in nine international competitions over a 7-year period (1530 males, 1527 female). Total race time and intermediate lap times were log-transformed and analysed for effects of sex (male, female), stroke (freestyle, form strokes, individual medley), event (100, 200, and 400 m), and place (1-16). Between-athlete correlations characterized the relationship of each lap to final time, and within-athlete estimates quantified the effect of lap time on improvements in final time. Finalists exhibited very large correlations (r = 0.7-0.9) with final time in the second 50-m lap of 100-m events and the middle two 50-m and 100-m laps of 200-m and 400-m events respectively. For an individual swimmer, an achievable change in lap time was associated with an approximate 0.4-0.8% improvement in final time for finalists and an approximate 0.5-1.1% improvement in final time for semi-finalists, depending on sex, stroke, and event. The pattern of lap times was similar for the top 16 swimmers and between the best and worst swims for finalists. These findings indicate that substantial improvements can be made via the final lap in sprints and the middle two laps of 200- to 400-m events, but the overall pattern of lap times should not be changed. PMID:19214862

  9. Testing composite-to-metal tubular lap joints

    SciTech Connect

    Guess, T.R.; Reedy, E.D. Jr.; Slavin, A.M.

    1993-11-01

    Procedures were developed to fabricate, nondestructively evaluate, and mechanically test composite-to-metal tubular joints. The axially loaded tubular lap joint specimen consisted of two metal tubes bonded within each end of a fiberglass composite tube. Joint specimens with both tapered and untapered aluminum adherends and a plain weave E-glass/epoxy composite were tested in tension, compression, and flexure. Other specimens with tapered and untapered steel adherends and a triaxially reinforced E-glass/epoxy composite were tested in tension and compression. Test results include joint strength and failure mode data. A finite element analysis of the axially loaded joints explains the effect of adherend geometry and material properties on measured joint strength. The flexural specimen was also analyzed; calculated surface strains are in good agreement with measured values, and joint failure occurs in the region of calculated peak peel stress.

  10. Testing composite-to-metal tubular lap joints

    NASA Astrophysics Data System (ADS)

    Guess, T. R.; Reedy, E. D., Jr.; Slavin, A. M.

    Procedures were developed to fabricate, nondestructively evaluate, and mechanically test composite-to-metal tubular joints. The axially loaded tubular lap joint specimen consisted of two metal tubes bonded within each end of a fiberglass composite tube. Joint specimens with both tapered and untapered aluminum adherends and a plain weave E-glass/epoxy composite were tested in tension, compression, and flexure. Other specimens with tapered and untapered steel adherends and a triaxially reinforced E-glass/epoxy composite were tested in tension and compression. Test results include joint strength and failure mode data. A finite element analysis of the axially loaded joints explains the effect of adherend geometry and material properties on measured joint strength. The flexural specimen was also analyzed; calculated surface strains are in good agreement with measured values, and joint failure occurs in the region of calculated peak peel stress.

  11. Large-Scale Advanced Prop-Fan (LAP) blade design

    NASA Technical Reports Server (NTRS)

    Violette, John A.; Sullivan, William E.; Turnberg, Jay E.

    1984-01-01

    This report covers the design analysis of a very thin, highly swept, propeller blade to be used in the Large-Scale Advanced Prop-Fan (LAP) test program. The report includes: design requirements and goals, a description of the blade configuration which meets requirements, a description of the analytical methods utilized/developed to demonstrate compliance with the requirements, and the results of these analyses. The methods described include: finite element modeling, predicted aerodynamic loads and their application to the blade, steady state and vibratory response analyses, blade resonant frequencies and mode shapes, bird impact analysis, and predictions of stalled and unstalled flutter phenomena. Summarized results include deflections, retention loads, stress/strength comparisons, foreign object damage resistance, resonant frequencies and critical speed margins, resonant vibratory mode shapes, calculated boundaries of stalled and unstalled flutter, and aerodynamic and acoustic performance calculations.

  12. Dynamics of active cellular response under stress

    NASA Astrophysics Data System (ADS)

    de, Rumi; Zemel, Assaf; Safran, Samuel

    2008-03-01

    Forces exerted by and on adherent cells are important for many physiological processes such as wound healing and tissue formation. In addition, recent experiments have shown that stem cell differentiation is controlled, at least in part, by the elasticity of the surrounding matrix. Using a simple theoretical model that includes the forces due to both the mechanosensitive nature of cells and the elastic response of the matrix, we predict the dynamics of orientation of cells. The model predicts many features observed in measurements of cellular forces and orientation including the increase with time of the forces generated by cells in the absence of applied stress and the consequent decrease of the force in the presence of quasi-static stresses. We also explain the puzzling observation of parallel alignment of cells for static and quasi-static stresses and of nearly perpendicular alignment for dynamically varying stresses. In addition, we predict the response of the cellular orientation to a sinusoidally varying applied stress as a function of frequency. The dependence of the cell orientation angle on the Poisson ratio of the surrounding material can be used to distinguish systems in which cell activity is controlled by stress from those where cell activity is controlled by strain. Reference: Nature Physics, vol. 3, pp 655 (2007).

  13. Homologs of the LapD-LapG c-di-GMP Effector System Control Biofilm Formation by Bordetella bronchiseptica.

    PubMed

    Ambrosis, Nicolás; Boyd, Chelsea D; O Toole, George A; Fernández, Julieta; Sisti, Federico

    2016-01-01

    Biofilm formation is important for infection by many pathogens. Bordetella bronchiseptica causes respiratory tract infections in mammals and forms biofilm structures in nasal epithelium of infected mice. We previously demonstrated that cyclic di-GMP is involved in biofilm formation in B. bronchiseptica. In the present work, based on their previously reported function in Pseudomonas fluorescens, we identified three genes in the B. bronchiseptica genome likely involved in c-di-GMP-dependent biofilm formation: brtA, lapD and lapG. Genetic analysis confirmed a role for BrtA, LapD and LapG in biofilm formation using microtiter plate assays, as well as scanning electron and fluorescent microscopy to analyze the phenotypes of mutants lacking these proteins. In vitro and in vivo studies showed that the protease LapG of B. bronchiseptica cleaves the N-terminal domain of BrtA, as well as the LapA protein of P. fluorescens, indicating functional conservation between these species. Furthermore, while BrtA and LapG appear to have little or no impact on colonization in a mouse model of infection, a B. bronchiseptica strain lacking the LapG protease has a significantly higher rate of inducing a severe disease outcome compared to the wild type. These findings support a role for c-di-GMP acting through BrtA/LapD/LapG to modulate biofilm formation, as well as impact pathogenesis, by B. bronchiseptica. PMID:27380521

  14. Homologs of the LapD-LapG c-di-GMP Effector System Control Biofilm Formation by Bordetella bronchiseptica

    PubMed Central

    Ambrosis, Nicolás; Boyd, Chelsea D.; O´Toole, George A.; Fernández, Julieta; Sisti, Federico

    2016-01-01

    Biofilm formation is important for infection by many pathogens. Bordetella bronchiseptica causes respiratory tract infections in mammals and forms biofilm structures in nasal epithelium of infected mice. We previously demonstrated that cyclic di-GMP is involved in biofilm formation in B. bronchiseptica. In the present work, based on their previously reported function in Pseudomonas fluorescens, we identified three genes in the B. bronchiseptica genome likely involved in c-di-GMP-dependent biofilm formation: brtA, lapD and lapG. Genetic analysis confirmed a role for BrtA, LapD and LapG in biofilm formation using microtiter plate assays, as well as scanning electron and fluorescent microscopy to analyze the phenotypes of mutants lacking these proteins. In vitro and in vivo studies showed that the protease LapG of B. bronchiseptica cleaves the N-terminal domain of BrtA, as well as the LapA protein of P. fluorescens, indicating functional conservation between these species. Furthermore, while BrtA and LapG appear to have little or no impact on colonization in a mouse model of infection, a B. bronchiseptica strain lacking the LapG protease has a significantly higher rate of inducing a severe disease outcome compared to the wild type. These findings support a role for c-di-GMP acting through BrtA/LapD/LapG to modulate biofilm formation, as well as impact pathogenesis, by B. bronchiseptica PMID:27380521

  15. Homologs of the LapD-LapG c-di-GMP Effector System Control Biofilm Formation by Bordetella bronchiseptica.

    PubMed

    Ambrosis, Nicolás; Boyd, Chelsea D; O Toole, George A; Fernández, Julieta; Sisti, Federico

    2016-01-01

    Biofilm formation is important for infection by many pathogens. Bordetella bronchiseptica causes respiratory tract infections in mammals and forms biofilm structures in nasal epithelium of infected mice. We previously demonstrated that cyclic di-GMP is involved in biofilm formation in B. bronchiseptica. In the present work, based on their previously reported function in Pseudomonas fluorescens, we identified three genes in the B. bronchiseptica genome likely involved in c-di-GMP-dependent biofilm formation: brtA, lapD and lapG. Genetic analysis confirmed a role for BrtA, LapD and LapG in biofilm formation using microtiter plate assays, as well as scanning electron and fluorescent microscopy to analyze the phenotypes of mutants lacking these proteins. In vitro and in vivo studies showed that the protease LapG of B. bronchiseptica cleaves the N-terminal domain of BrtA, as well as the LapA protein of P. fluorescens, indicating functional conservation between these species. Furthermore, while BrtA and LapG appear to have little or no impact on colonization in a mouse model of infection, a B. bronchiseptica strain lacking the LapG protease has a significantly higher rate of inducing a severe disease outcome compared to the wild type. These findings support a role for c-di-GMP acting through BrtA/LapD/LapG to modulate biofilm formation, as well as impact pathogenesis, by B. bronchiseptica.

  16. Handwashing Technique. Instructor's Packet. Learning Activity Package.

    ERIC Educational Resources Information Center

    Stark, Pamela

    This instructor's packet accompanies the learning activity package (LAP) on handwashing. Contents included in the packet are a time sheet, suggested uses for the LAP, an instruction sheet, final LAP reviews, a final LAP review answer key, a student performance checklist, an additional resources list, and student completion cards to issue to…

  17. Fis overexpression enhances Pseudomonas putida biofilm formation by regulating the ratio of LapA and LapF.

    PubMed

    Moor, Hanna; Teppo, Annika; Lahesaare, Andrio; Kivisaar, Maia; Teras, Riho

    2014-12-01

    Bacteria form biofilm as a response to a number of environmental signals that are mediated by global transcription regulators and alarmones. Here we report the involvement of the global transcription regulator Fis in Pseudomonas putida biofilm formation through regulation of lapA and lapF genes. The major component of P. putida biofilm is proteinaceous and two large adhesive proteins, LapA and LapF, are known to play a key role in its formation. We have previously shown that Fis overexpression enhances P. putida biofilm formation. In this study, we used mini-Tn5 transposon mutagenesis to select potential Fis-regulated genes involved in biofilm formation. A total of 90 % of the studied transposon mutants carried insertions in the lap genes. Since our experiments showed that Fis-enhanced biofilm is mostly proteinaceous, the amounts of LapA and LapF from P. putida cells lysates were quantified using SDS-PAGE. Fis overexpression increases the quantity of LapA 1.6 times and decreases the amount of LapF at least 4 times compared to the wild-type cells. The increased LapA expression caused by Fis overexpression was confirmed by FACS analysis measuring the amount of LapA-GFP fusion protein. Our results suggest that the profusion of LapA in the Fis-overexpressed cells causes enhanced biofilm formation in mature stages of P. putida biofilm and LapF has a minor role in P. putida biofilm formation.

  18. Systematic Construction of Real Lapped Tight Frame Transforms

    PubMed Central

    Sandryhaila, Aliaksei; Chebira, Amina; Milo, Christina; Kovčcević, Jelena; Püschel, Markus

    2010-01-01

    We present a constructive algorithm for the design of real lapped equal-norm tight frame transforms. These transforms can be efficiently implemented through filter banks and have recently been proposed as a redundant counterpart to lapped orthogonal transforms, as well as an infinite-dimensional counterpart to harmonic tight frames. The proposed construction consists of two parts: First, we design a large class of new real lapped orthogonal transforms derived from submatrices of the discrete Fourier transform. Then, we seed these to obtain real lapped tight frame transforms corresponding to tight, equal-norm frames. We identify those frames that are maximally robust to erasures, and show that our construction leads to a large class of new lapped orthogonal transforms as well as new lapped tight frame transforms. PMID:20607116

  19. Dogs lap using acceleration-driven open pumping

    PubMed Central

    Gart, Sean; Socha, John J.; Vlachos, Pavlos P.; Jung, Sunghwan

    2015-01-01

    Dogs lap because they have incomplete cheeks and cannot suck. When lapping, a dog’s tongue pulls a liquid column from the bath, suggesting that the hydrodynamics of column formation are critical to understanding how dogs drink. We measured lapping in 19 dogs and used the results to generate a physical model of the tongue’s interaction with the air–fluid interface. These experiments help to explain how dogs exploit the fluid dynamics of the generated column. The results demonstrate that effects of acceleration govern lapping frequency, which suggests that dogs curl the tongue to create a larger liquid column. Comparing lapping in dogs and cats reveals that, despite similar morphology, these carnivores lap in different physical regimes: an unsteady inertial regime for dogs and steady inertial regime for cats. PMID:26668382

  20. Dogs lap using acceleration-driven open pumping.

    PubMed

    Gart, Sean; Socha, John J; Vlachos, Pavlos P; Jung, Sunghwan

    2015-12-29

    Dogs lap because they have incomplete cheeks and cannot suck. When lapping, a dog's tongue pulls a liquid column from the bath, suggesting that the hydrodynamics of column formation are critical to understanding how dogs drink. We measured lapping in 19 dogs and used the results to generate a physical model of the tongue's interaction with the air-fluid interface. These experiments help to explain how dogs exploit the fluid dynamics of the generated column. The results demonstrate that effects of acceleration govern lapping frequency, which suggests that dogs curl the tongue to create a larger liquid column. Comparing lapping in dogs and cats reveals that, despite similar morphology, these carnivores lap in different physical regimes: an unsteady inertial regime for dogs and steady inertial regime for cats.

  1. Swim Pressure: Stress Generation in Active Matter

    NASA Astrophysics Data System (ADS)

    Takatori, S. C.; Yan, W.; Brady, J. F.

    2014-07-01

    We discover a new contribution to the pressure (or stress) exerted by a suspension of self-propelled bodies. Through their self-motion, all active matter systems generate a unique swim pressure that is entirely athermal in origin. The origin of the swim pressure is based upon the notion that an active body would swim away in space unless confined by boundaries—this confinement pressure is precisely the swim pressure. Here we give the micromechanical basis for the swim stress and use this new perspective to study self-assembly and phase separation in active soft matter. The swim pressure gives rise to a nonequilibrium equation of state for active matter with pressure-volume phase diagrams that resemble a van der Waals loop from equilibrium gas-liquid coexistence. Theoretical predictions are corroborated by Brownian dynamics simulations. Our new swim stress perspective can help analyze and exploit a wide class of active soft matter, from swimming bacteria to catalytic nanobots to molecular motors that activate the cellular cytoskeleton.

  2. Swim pressure: stress generation in active matter.

    PubMed

    Takatori, S C; Yan, W; Brady, J F

    2014-07-11

    We discover a new contribution to the pressure (or stress) exerted by a suspension of self-propelled bodies. Through their self-motion, all active matter systems generate a unique swim pressure that is entirely athermal in origin. The origin of the swim pressure is based upon the notion that an active body would swim away in space unless confined by boundaries-this confinement pressure is precisely the swim pressure. Here we give the micromechanical basis for the swim stress and use this new perspective to study self-assembly and phase separation in active soft matter. The swim pressure gives rise to a nonequilibrium equation of state for active matter with pressure-volume phase diagrams that resemble a van der Waals loop from equilibrium gas-liquid coexistence. Theoretical predictions are corroborated by Brownian dynamics simulations. Our new swim stress perspective can help analyze and exploit a wide class of active soft matter, from swimming bacteria to catalytic nanobots to molecular motors that activate the cellular cytoskeleton.

  3. Bolted Double-Lap Composite Joints Under Mechanical and Thermal Loading

    NASA Technical Reports Server (NTRS)

    Kradinov, V.; Barut, A.; Madenci, E.; Walker, Sandra P. (Technical Monitor)

    2000-01-01

    This study concerns the determination of the contact stresses and contact region around bolt holes and the bolt load distribution in single- and double-lap joints of composite laminates with arbitrarily located bolts under general mechanical loading conditions and uniform temperature change. The unknown contact stress distribution and contact region between the bolt and laminates and the interaction among the bolts require the bolt load distribution, as well as the contact stresses, to be as part of the solution. The present method is based on the complex potential theory and the variational formulation in order to account for bolt stiffness, bolt-hole clearance, and finite geometry of the composite laminates.

  4. Diamond machine tool face lapping machine

    DOEpatents

    Yetter, H.H.

    1985-05-06

    An apparatus for shaping, sharpening and polishing diamond-tipped single-point machine tools. The isolation of a rotating grinding wheel from its driving apparatus using an air bearing and causing the tool to be shaped, polished or sharpened to be moved across the surface of the grinding wheel so that it does not remain at one radius for more than a single rotation of the grinding wheel has been found to readily result in machine tools of a quality which can only be obtained by the most tedious and costly processing procedures, and previously unattainable by simple lapping techniques.

  5. How dogs lap: open pumping driven by acceleration

    NASA Astrophysics Data System (ADS)

    Gart, Sean; Socha, John; Vlachos, Pavlos; Jung, Sunghwan

    2015-11-01

    Dogs drink by lapping because they have incomplete cheeks and cannot suck fluids into the mouth. When lapping, a dog's tongue pulls a liquid column from a bath, which is then swallowed, suggesting that the hydrodynamics of column formation are critical to understanding how dogs drink. We measured the kinematics of lapping from nineteen dogs and used the results to generate a physical model of the tongue's interaction with the air-fluid interface. These experiments with an accelerating rod help to explain how dogs exploit the fluid dynamics of the generated column. The results suggest that effects of acceleration govern lapping frequency, and that dogs curl the tongue ventrally (backwards) and time their bite on the column to increase fluid intake per lap. Comparing lapping in dogs and cats reveals that though they both lap with the same frequency scaling with respect to body mass and have similar morphology, these carnivores lap in different physical regimes: a high-acceleration regime for dogs and a low-acceleration regime for cats.

  6. A fracture mechanics analysis of adhesive failure in a single lap shear joint.

    NASA Technical Reports Server (NTRS)

    Devries, K. L.; Williams, M. L.; Chang, M. D.

    1972-01-01

    Discussion of adhesive fracture of single lap shear joints in terms of a maximum stress criterion and an energy balance. The Goland and Reissner (1944) analysis is used to determine the stress distribution in the adhesive assembly, and the results obtained are introduced into an energy balance to determine the initiation of adhesive fracture. In the stress analysis the loads at the edges of the joint are first determined. This is a problem in which the deformation of the joint sheets must be taken into account and is solved by using the finite-deflection theory of cylindrically bent plates. Then the stress in the joint due to applied loads is determined. This problem is formulated as one in plane strain consisting of two rectangular sheets of equal thickness and unit width. With the aid of this stress analysis and the stresses obtained from the conditions of equilibrium the contributions to the energy change with crack length are calculated. The analysis performed is then compared with a maximum stress criterion for a lap joint.

  7. A study of sandwich T-joints and composite lap joints

    NASA Astrophysics Data System (ADS)

    Turaga, Umamaheswar V. R. S.

    In this study, new efficient designs for adhesive sandwich T-joint and single-lap joint were proposed and investigated. In the proposed new sandwich T-joint, called U-channel joint, the load transfer path at the web-flange interface was modified to include a U-shaped aluminum channel which provides strong path for load transfer. Experimental results show that the new design has 62% more strength than the conventional circular fillet joint. The new U-channel joint was tested in tension, compression and bending to investigate its characteristics. It is found to have good performance in bending also, even though in compression it performs same as the circular fillet joint. An extensive parametric study was carried out to investigate the effect of parameters like flange skin stiffener, foam density, foam thickness in the web, and aluminum attachments. A fracture mechanics criterion based on the strain energy release rate was used to explain the failure modes, apart from the stress analysis explanation. The failure loads of the joints in compression were predicted using a maximum principal stress failure criterion based on the sandwich beam theory. A new single lap joint with attachments was proposed in the second phase of the research. The design was verified using both aluminum and composite materials. The new design was found to have 59% more strength than the single-lap joint. A parametric study was performed to find out the influence of the angle of attachment, thickness of attachment and the length of attachment. By careful consideration of design parameters, the joint can be optimized. Finally, the failure loads of the single lap joints with and without attachments were predicted using different failure criteria.

  8. Identification of a Novel Human LAP1 Isoform That Is Regulated by Protein Phosphorylation

    PubMed Central

    Santos, Mariana; Domingues, Sara C.; Costa, Patrícia; Muller, Thorsten; Galozzi, Sara; Marcus, Katrin; da Cruz e Silva, Edgar F.; da Cruz e Silva, Odete A.; Rebelo, Sandra

    2014-01-01

    Lamina associated polypeptide 1 (LAP1) is an integral protein of the inner nuclear membrane that is ubiquitously expressed. LAP1 binds to lamins and chromatin, probably contributing to the maintenance of the nuclear envelope architecture. Moreover, LAP1 also interacts with torsinA and emerin, proteins involved in DYT1 dystonia and X-linked Emery-Dreifuss muscular dystrophy disorder, respectively. Given its relevance to human pathological conditions, it is important to better understand the functional diversity of LAP1 proteins. In rat, the LAP1 gene (TOR1AIP1) undergoes alternative splicing to originate three LAP1 isoforms (LAP1A, B and C). However, it remains unclear if the same occurs with the human TOR1AIP1 gene, since only the LAP1B isoform had thus far been identified in human cells. In silico analysis suggested that, across different species, potential new LAP1 isoforms could be generated by alternative splicing. Using shRNA to induce LAP1 knockdown and HPLC-mass spectrometry analysis the presence of two isoforms in human cells was described and validated: LAP1B and LAP1C; the latter is putatively N-terminal truncated. LAP1B and LAP1C expression profiles appear to be dependent on the specific tissues analyzed and in cultured cells LAP1C was the major isoform detected. Moreover, LAP1B and LAP1C expression increased during neuronal maturation, suggesting that LAP1 is relevant in this process. Both isoforms were found to be post-translationally modified by phosphorylation and methionine oxidation and two LAP1B/LAP1C residues were shown to be dephosphorylated by PP1. This study permitted the identification of the novel human LAP1C isoform and partially unraveled the molecular basis of LAP1 regulation. PMID:25461922

  9. Cognitive activation theory of stress (CATS).

    PubMed

    Ursin, Holger; Eriksen, Hege R

    2010-05-01

    The cognitive activation theory of stress (CATS) is based on a long series of experiments on animals and on humans, in the laboratory, and in real life situations. From the common sense coping concept formulated by Seymour Levine; coping is when my "tommy" does not hurt, we have advanced to a systematic theory for what is behind the relaxed and happy coping rat (and cat). We also cover the translational leap to humans, starting with the now classic parachutist study. The bridge is based on formal and symbolic definitions, a theoretical short cut that Levine actually never really accepted. The essential pathophysiological concept is the potential pathological effects of sustained activation, which may occur in the absence of coping (positive response outcome expectancy). We review the current status of CATS in Behavioural Medicine by discussing its potential explanatory power in epidemiology, prevention and treatment of "subjective health complaints".

  10. Large-scale Advanced Prop-fan (LAP) static rotor test report

    NASA Technical Reports Server (NTRS)

    Degeorge, Charles L.; Turnberg, Jay E.; Wainauski, Harry S.

    1987-01-01

    Discussed is Static Rotor Testing of the SR-7L Large Scale Advanced Prop-Fan (LAP). The LAP is an advanced 9 foot diameter, 8 bladed propeller designed and built by Hamilton Standard under contract to the NASA Lewis Research Center. The Prop-Fan employs thin swept blades to provide efficient propulsion at flight speeds up to Mach .85. Static Testing was conducted on a 10,000 HP whirl rig at Wright Patterson Air Force Base. The test objectives were to investigate the Prop-Fan static aerodynamic and structural dynamic performance, determine the blade steady state stressers and deflections and to measure steady and unsteady pressures on the SR-7L blade surface. The measured performance of the LAP correlated well with analytical predictions at blade pitch angles below 30 deg. A stall buffet phenomenon was observed at blade pitch angles above 30 deg. This phenomenon manifested itself by elevated blade vibratory stress levels and lower than expected thrust produced and power absorbed by the Prop-Fan for a given speed and blade angle.

  11. Dissimilar effects of β-lapachone- and hydroxyurea-induced DNA replication stress in root meristem cells of Allium cepa.

    PubMed

    Zabka, Aneta; Trzaskoma, Paweł; Maszewski, Janusz

    2013-12-01

    Two anticancer drugs, β-lapachone (β-lap, a naphthoquinone) and hydroxyurea (HU, an inhibitor of ribonucleotide reductase), differently affect nuclear morphology and cell cycle control mechanisms in root meristem cells of Allium cepa. The 18 h treatment with 100 μM β-lap results in a lowered number of M-phase cells, increased occurrence of mitotic abnormalities, including over-condensation of chromosomes, their enhanced stickiness, formation of anaphase bridges, micronucleation and reduced mitotic spindles. Following prolonged incubations using high doses of β-lap, cell nuclei reveal dark-red fluorescence evenly distributed in chromatin surrounding the unstained regions of nucleoli. Both drugs generate H2O2 and induce DNA double strand breaks, which is correlated with γ-phoshorylation of H2AX histones. However, the extent of H2AX phosphorylation (including the frequency of γ-H2AX foci and the relative number cells creating phospho-H2AX domains) is considerably reduced in root meristem cells treated jointly with the β-lap/HU mixture. Furthermore, various effects of caffeine (an inhibitor of ATM/ATR cell cycle checkpoint kinases) on β-lap- and HU-induced γ-phoshorylation of H2AX histones and the protective activity of HU against β-lap suggest that their genotoxic activities are largely dissimilar. β-Lap treatment results in the induction of apoptosis-like programmed cell death, while HU treatment leads to cell adaptation to replication stress and promotion of abnormal nuclear divisions with biphasic interphase/mitotic states of chromatin condensation.

  12. Contributions of kinematics and viscoelastic lap deformation on the suface figure during full aperture polishing of fused silica

    SciTech Connect

    Suratwala, T I; Steele, R A; Feit, M D

    2007-10-09

    A typical optical fabrication process involves a series of basic process steps including: (1) shaping, (2) grinding, (3) polishing, and sometimes (4) sub-aperture tool finishing. With significant innovation and development over the years in both the front end (shaping using CNC machines) and the back end (sup-aperture tool polishing), these processes have become much more deterministic. However, the intermediate stages (full aperture grinding/polishing) in the process, which can be very time consuming, still have much reliance on the optician's insight to get to the desired surface figure. Such processes are not presently very deterministic (i.e. require multiple iterations to get desired figure). The ability to deterministically finish an optical surface using a full aperture grinding/polishing will aid optical glass fabricators to achieve desired figure in a more repeatable, less iterative, and more economical manner. Developing a scientific understanding of the material removal rate is a critical step in accomplishing this. In the present study, the surface figure and material removal rate of a fused silica workpiece is measured as a function of polishing time using Ceria based slurry on a polyurethane pad or pitch lap under a variety of kinematic conditions (motion of the workpiece and lap) and loading configurations. The measured results have been applied to expand the Preston model of material removal (utilizing chemical, mechanical and tribological effects). The results show that under uniform loading, the surface figure is dominated by kinematics which can be predicted by calculating the relative velocity (between the workpiece and the lap) with time and position on the workpiece. However, in the case where the kinematics predict a time-averaged removal function over the workpiece that is uniform, we find experimentally that the surface deviates significantly from uniform removal. We show that this non-uniform removal is caused by the non-uniform stress

  13. INTERIOR OF WEST SPAN LOOKING WEST (SHADOW OF VERTICAL LAPS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR OF WEST SPAN LOOKING WEST (SHADOW OF VERTICAL LAPS PLACED ON ZONE III; ASPHALT ZONE IX) - Honey Run Bridge, Spanning Butte Creek, bypassed section of Honey Run Road (originally Carr Hill Road), Paradise, Butte County, CA

  14. FRICTION STIR LAP WELDING OF ALUMINUM - POLYMER USING SCRIBE TECHNOLOGY

    SciTech Connect

    Upadhyay, Piyush; Hovanski, Yuri; Fifield, Leonard S.; Simmons, Kevin L.

    2015-02-16

    Friction Stir Scribe (FSS) technology is a relatively new variant of Friction Stir Welding (FSW) which enables lap joining of dissimilar material with very different melting points and different high temperature flow behaviors. The cutter scribe attached at the tip of FSW tool pin effectively cuts the high melting point material such that a mechanically interlocking feature is created between the dissimilar materials. The geometric shape of this interlocking feature determines the shear strength attained by the lap joint. This work presents first use of scribe technology in joining polymers to aluminum alloy. Details of the several runs of scribe welding performed in lap joining of ~3.175mm thick polymers including HDPE, filled and unfilled Nylon 66 to 2mm thick AA5182 are presented. The effect of scribe geometry and length on weld interlocking features is presented along with lap shear strength evaluations.

  15. Double-Lap Shear Test For Honeycomb Core

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.; Hodge, Andrew J.

    1992-01-01

    Double-lap test measures shear strength of panel made of honeycomb core with 8-ply carbon-fiber/epoxy face sheets. Developed to overcome three principal disadvantages of prior standard single-lap shear test: specimen had to be more than 17 in. long; metal face sheets had to be used; and test introduced torque, with consequent bending and peeling of face sheets and spurious tensile or compressive loading of honeycomb.

  16. Stress-induced asymmetric frontal brain activity and aggression risk.

    PubMed

    Verona, Edelyn; Sadeh, Naomi; Curtin, John J

    2009-02-01

    Impersonal stressors, not only interpersonal provocation, can instigate aggression through an associative network linking negative emotions to behavioral activation (L. Berkowitz, 1990). Research has not examined the brain mechanisms that are engaged by different types of stress and serve to promote hostility and aggression. The present study examined whether stress exposure elicits more left than right frontal brain activity implicated in behavioral approach motivation and whether this lateralized brain activity predicts stress-induced aggression and hostile/aggressive tendencies. Results showed that (a) participants in the impersonal (assigned to stress by a computer) and interpersonal (assigned to stress by a provoking confederate) stress conditions both showed more left than right frontal electroencephalogram activity after condition assignment and stress exposure and (b) the 2 stress groups exhibited subsequent increases in aggression relative to the no-stress group. Importantly, left frontal asymmetry in response to stress exposure predicted increases in subsequent aggressive behavior, a finding that did not emerge in the no-stress condition. Thus, both the interpersonal and impersonal stressors impacted state changes in brain activity related to behavioral approach, suggesting that stress reactivity involving approach activation represents risk for behavioral dysregulation.

  17. L-Cysteine and L-AP4 microinjections in the rat caudal ventrolateral medulla decrease arterial blood pressure.

    PubMed

    Takemoto, Yumi

    2014-12-01

    The thiol amino acid L-cysteine increases arterial blood pressure (ABP) when injected into the cerebrospinal fluid space in conscious rats, indicating a pressor response to centrally acting L-cysteine. A prior synaptic membrane binding assay suggests that L-cysteine has a strong affinity for the L-2-amino-4-phosphonobutyric acid (L-AP4) binding site. The central action of L-cysteine may be vial-AP4 sensitive receptors. The present study investigated cardiovascular responses to L-cysteine and L-ap4 microinjected into the autonomic area of the caudal ventrolateral medulla (CVLM) where inhibitory neurons regulate ABP via pre-sympathetic vasomotor neurons. Both the injection of L-cysteine and L-AP4 in the CVLM sites identified with L-glutamate produced the same depressor and bradycardic responses in urethane-anesthetized rats. Neither a prior antagonist microinjection of MK801 for the N-methyl-D-aspartate (NMDA) receptor nor CNQX for the non-NMDA receptor attenuated the responses to L-cysteine, but the combination of the two receptor blocking with an additional prior injection abolished the response. In contrast, either receptor blockade alone abolished the response to L-AP4, indicating distinct mechanisms between responses to L-cysteine and L-AP4 in the CVLM. The results indicate that the CVLM is a central active site for L-cysteine's cardiovascular response. Central L-cysteine's action could be independent of the L-AP4 sensitive receptors. Cardiovascular regulation may involve endogenous L-cysteine in the CVLM. Further multidisciplinary examinations are required to elaborate on L-cysteine's functional roles in the CVLM.

  18. FRACTURE MECHANICS APPROACH TO ESTIMATE FATIGUE LIVES OF WELDED LAP-SHEAR SPECIMENS

    SciTech Connect

    Lam, P.; Michigan, J.

    2014-04-25

    A full range of stress intensity factor solutions for a kinked crack is developed as a function of weld width and the sheet thickness. When used with the associated main crack solutions (global stress intensity factors) in terms of the applied load and specimen geometry, the fatigue lives can be estimated for the laser-welded lap-shear specimens. The estimations are in good agreement with the experimental data. A classical solution for an infinitesimal kink is also employed in the approach. However, the life predictions tend to overestimate the actual fatigue lives. The traditional life estimations with the structural stress along with the experimental stress-fatigue life data (S-N curve) are also provided. In this case, the estimations only agree with the experimental data under higher load conditions.

  19. Analysis of a double shear lap joint with interference fit pin

    SciTech Connect

    Sundarraj, N.; Dattaguru, B.; Ramamurthy, T.S.

    1995-04-01

    This paper presents the study of stress distribution in a double-shear lap joint with interference fit pin subjected to inplane plate loads using FELJNT, a finite element software developed for this special purpose. FELJNT accounts for the effects of clamping and flexure of the bolt without having to adopt a laborious three-dimensional analysis. It carries out stress analysis in an axisymmetric region around the pin under non-axisymmetric loading. It uses an iterative method of contact stress analysis and a dummy element concept with frontal solver for finite element solution. This paper discusses the load for initiation of separation, through-the-thickness stress distribution, and qualitatively the beneficial effects of interference on fatigue life of the joint. The paper concludes with comparison of FELJNT results with those of JACKAL, a three-dimensional finite element analysis software for joints. 13 refs.

  20. Aging causes decreased resistance to multiple stresses and a failure to activate specific stress response pathways

    PubMed Central

    Bergsma, Alexis L.; Senchuk, Megan M.; Van Raamsdonk, Jeremy M.

    2016-01-01

    In this work, we examine the relationship between stress resistance and aging. We find that resistance to multiple types of stress peaks during early adulthood and then declines with age. To dissect the underlying mechanisms, we use C. elegans transcriptional reporter strains that measure the activation of different stress responses including: the heat shock response, mitochondrial unfolded protein response, endoplasmic reticulum unfolded protein response, hypoxia response, SKN-1-mediated oxidative stress response, and the DAF-16-mediated stress response. We find that the decline in stress resistance with age is at least partially due to a decreased ability to activate protective mechanisms in response to stress. In contrast, we find that any baseline increase in stress caused by the advancing age is too mild to detectably upregulate any of the stress response pathways. Further exploration of how worms respond to stress with increasing age revealed that the ability to mount a hormetic response to heat stress is also lost with increasing age. Overall, this work demonstrates that resistance to all types of stress declines with age. Based on our data, we speculate that the decrease in stress resistance with advancing age results from a genetically-programmed inactivation of stress response pathways, not accumulation of damage. PMID:27053445

  1. Flaw Tolerance in Lap Shear Brazed Joints. Part 1

    NASA Technical Reports Server (NTRS)

    Flom, Yury; Wang, Li-Qin

    2003-01-01

    Furnace brazing is a joining process used in the aerospace and other industries to produce strong permanent and hermetic structural joints. As in any joining process, brazed joints have various imperfections and defects. At the present time, our understanding of the influence of the internal defects on the strength of the brazed joints is not adequate. The goal of this 3-part investigation is to better understand the properties and failure mechanisms of the brazed joints containing defects. This study focuses on the behavior of the brazed lap shear joints because of their importance in manufacturing aerospace structures. In Part 1, an average shear strength capability and failure modes of the single lap joints are explored. Stainless steel specimens brazed with pure silver are tested in accordance with the AWS C3.2 standard. Comparison of the failure loads and the ultimate shear strength with the Finite Element Analysis (FEA) of the same specimens as a function of the overlap widths shows excellent correlation between the experimental and calculated values for the defect-free lap joints. A damage zone criterion is shown to work quite well in understanding the failure of the braze joints. In Part 2, the findings of the Part 1 will be verified on the larger test specimens. Also, various flaws will be introduced in the test specimens to simulate lack of braze coverage in the lap joints. Mechanical testing and FEA will be performed on these joints to verify that behavior of the flawed ductile lap joints is similar to joints with a reduced braze area. Finally, in Part 3, the results obtained in Parts 1 and 2 will be applied to the actual brazed structure to evaluate the load-carrying capability of a structural lap joint containing discontinuities. In addition, a simplified engineering procedure will be offered for the laboratory testing of the lap shear specimens.

  2. High Voltage Breakdown, Partial Discharge and Aging in Lapped Tape Insulated Cold Dielectric Model Cables

    NASA Astrophysics Data System (ADS)

    Sauers, I.; James, D. R.; Pace, M. O.; Ellis, A. R.; Muller, A. C.

    2004-06-01

    High temperature superconducting (HTS) power cables generally follow either of two generic designs, cold dielectric and warm dielectric. In the cold dielectric design, lapped tape insulation and liquid nitrogen are used in combination to provide the electrical insulation between the conductor and the ground shield of an HTS cable. Lapped tape insulated model cables have been tested at high voltage, including AC breakdown, negative impulse breakdown, partial discharge, and long term aging under AC stress. Tapes tested include Cryoflex™ (a proprietary tape developed by Southwire) and PPLP® (a commercial semi synthetic tape). Two high voltage cryostats have been built for short and long term aging studies that permit testing of model cables under the combined conditions of high electric stress, cryogenic temperature and elevated pressures up to 15 bar. For the aging studies, a log-log plot of electric stress versus time-to-breakdown has yielded an estimate of cable lifetime. Since aging at cryogenic temperatures is not expected to have a thermal cause, dielectric wear in HTS cables reduces to partial discharge as the primary aging mechanism. Phase and amplitude resolved partial discharge data of model cables in liquid nitrogen will be presented.

  3. Dynamics of telomerase activity in response to acute psychological stress

    PubMed Central

    Epel, Elissa S.; Lin, Jue; Dhabhar, Firdaus S.; Wolkowitz, Owen M.; Puterman, E; Karan, Lori; Blackburn, Elizabeth H.

    2010-01-01

    Telomerase activity plays an essential role in cel0l survival, by lengthening telomeres and promoting cell growth and longevity. It is now possible to quantify the low levels of telomerase activity in human leukocytes. Low basal telomerase activity has been related to chronic stress in people and to chronic glucocorticoid exposure in vitro. Here we test whether leukocyte telomerase activity changes under acute psychological stress. We exposed 44 elderly women, including 22 high stress dementia caregivers and 22 matched low stress controls, to a brief laboratory psychological stressor, while examining changes in telomerase activity of peripheral blood mononuclear cells (PBMC). At baseline, caregivers had lower telomerase activity levels than controls, but during stress telomerase activity increased similarly in both groups. Across the entire sample, subsequent telomerase activity increased by 18% one hour after the end of the stressor (p<0.01). The increase in telomerase activity was independent of changes in numbers or percentages of monocytes, lymphocytes, and specific T cell types, although we cannot fully rule out some potential contribution from immune cell redistribution in the change in telomerase activity. Telomerase activity increases were associated with greater cortisol increases in response to the stressor. Lastly, psychological response to the tasks (greater threat perception) was also related to greater telomerase activity increases in controls. These findings uncover novel relationships of dynamic telomerase activity with exposure to an acute stressor, and with two classic aspects of the stress response -- perceived psychological stress and neuroendocrine (cortisol) responses to the stressor. PMID:20018236

  4. LAP5 and LAP6 Encode Anther-Specific Proteins with Similarity to Chalcone Synthase Essential for Pollen Exine Development in Arabidopsis1[W][OA

    PubMed Central

    Dobritsa, Anna A.; Lei, Zhentian; Nishikawa, Shuh-ichi; Urbanczyk-Wochniak, Ewa; Huhman, David V.; Preuss, Daphne; Sumner, Lloyd W.

    2010-01-01

    Pollen grains of land plants have evolved remarkably strong outer walls referred to as exine that protect pollen and interact with female stigma cells. Exine is composed of sporopollenin, and while the composition and synthesis of this biopolymer are not well understood, both fatty acids and phenolics are likely components. Here, we describe mutations in the Arabidopsis (Arabidopsis thaliana) LESS ADHESIVE POLLEN (LAP5) and LAP6 that affect exine development. Mutation of either gene results in abnormal exine patterning, whereas pollen of double mutants lacked exine deposition and subsequently collapsed, causing male sterility. LAP5 and LAP6 encode anther-specific proteins with homology to chalcone synthase, a key flavonoid biosynthesis enzyme. lap5 and lap6 mutations reduced the accumulation of flavonoid precursors and flavonoids in developing anthers, suggesting a role in the synthesis of phenolic constituents of sporopollenin. Our in vitro functional analysis of LAP5 and LAP6 using 4-coumaroyl-coenzyme A yielded bis-noryangonin (a commonly reported derailment product of chalcone synthase), while similar in vitro analyses using fatty acyl-coenzyme A as the substrate yielded medium-chain alkyl pyrones. Thus, in vitro assays indicate that LAP5 and LAP6 are multifunctional enzymes and may play a role in both the synthesis of pollen fatty acids and phenolics found in exine. Finally, the genetic interaction between LAP5 and an anther gene involved in fatty acid hydroxylation (CYP703A2) demonstrated that they act synergistically in exine production. PMID:20442277

  5. Mechanisms and Management of Stress Fractures in Physically Active Persons

    PubMed Central

    Romani, William A.; Gieck, Joe H.; Perrin, David H.; Saliba, Ethan N.; Kahler, David M.

    2002-01-01

    Objective: To describe the anatomy of bone and the physiology of bone remodeling as a basis for the proper management of stress fractures in physically active people. Data Sources: We searched PubMed for the years 1965 through 2000 using the key words stress fracture, bone remodeling, epidemiology, and rehabilitation. Data Synthesis: Bone undergoes a normal remodeling process in physically active persons. Increased stress leads to an acceleration of this remodeling process, a subsequent weakening of bone, and a higher susceptibility to stress fracture. When a stress fracture is suspected, appropriate management of the injury should begin immediately. Effective management includes a cyclic process of activity and rest that is based on the remodeling process of bone. Conclusions/Recommendations: Bone continuously remodels itself to withstand the stresses involved with physical activity. Stress fractures occur as the result of increased remodeling and a subsequent weakening of the outer surface ofthe bone. Once a stress fracture is suspected, a cyclic management program that incorporates the physiology of bone remodeling should be initiated. The cyclic program should allow the physically active person to remove the source of the stress to the bone, maintain fitness, promote a safe return to activity, and permit the bone to heal properly. PMID:16558676

  6. Dynamic neural activity during stress signals resilient coping.

    PubMed

    Sinha, Rajita; Lacadie, Cheryl M; Constable, R Todd; Seo, Dongju

    2016-08-01

    Active coping underlies a healthy stress response, but neural processes supporting such resilient coping are not well-known. Using a brief, sustained exposure paradigm contrasting highly stressful, threatening, and violent stimuli versus nonaversive neutral visual stimuli in a functional magnetic resonance imaging (fMRI) study, we show significant subjective, physiologic, and endocrine increases and temporally related dynamically distinct patterns of neural activation in brain circuits underlying the stress response. First, stress-specific sustained increases in the amygdala, striatum, hypothalamus, midbrain, right insula, and right dorsolateral prefrontal cortex (DLPFC) regions supported the stress processing and reactivity circuit. Second, dynamic neural activation during stress versus neutral runs, showing early increases followed by later reduced activation in the ventrolateral prefrontal cortex (VLPFC), dorsal anterior cingulate cortex (dACC), left DLPFC, hippocampus, and left insula, suggested a stress adaptation response network. Finally, dynamic stress-specific mobilization of the ventromedial prefrontal cortex (VmPFC), marked by initial hypoactivity followed by increased VmPFC activation, pointed to the VmPFC as a key locus of the emotional and behavioral control network. Consistent with this finding, greater neural flexibility signals in the VmPFC during stress correlated with active coping ratings whereas lower dynamic activity in the VmPFC also predicted a higher level of maladaptive coping behaviors in real life, including binge alcohol intake, emotional eating, and frequency of arguments and fights. These findings demonstrate acute functional neuroplasticity during stress, with distinct and separable brain networks that underlie critical components of the stress response, and a specific role for VmPFC neuroflexibility in stress-resilient coping. PMID:27432990

  7. Lap time optimisation of a racing go-kart

    NASA Astrophysics Data System (ADS)

    Lot, Roberto; Dal Bianco, Nicola

    2016-02-01

    The minimum lap time optimal control problem has been solved for a go-kart model. The symbolic algebra software Maple has been used to derive equations of motion and an indirect method has been adopted to solve the optimal control problem. Simulation has been successfully performed on a full track lap with a multibody model endowed with seven degrees of freedom. Geometrical and mechanical characteristics of a real kart have been measured by a lab test to feed the mathematical model. Telemetry recorded in an entire lap by a professional driver has been compared to simulation results in order to validate the model. After the reliability of the optimal control model was proved, the simulation has been used to study the peculiar dynamics of go-karts and focus to tyre slippage dynamics, which is highly affected by the lack of differential.

  8. Failure strength prediction for adhesively bonded single lap joints

    NASA Astrophysics Data System (ADS)

    Rahman, Niat Mahmud

    For adhesively bonded joint, failure strength depends on many factors such as material properties (both adhesive and adherend), specimen geometries, test environments, surface preparation procedures, etc. Failure occurs inside constitutive materials or along joint interfaces. Based on location, adhesively bonded failure mode can be classified as adhesive failure mode, cohesive failure mode and adherend failure mode. Failure mode directly affects the failure strength of joint. For last eight decades, researchers have developed analytical, empirical or semi-empirical methods capable of predicting failure strength for adhesively bonded joints generating either cohesive failure or adherend failure. Applicability of most of the methods is limited to particular cases. In this research, different failure modes for single lap joints (SLJs) were generated experimentally using epoxy based paste adhesive. Based on experimental data and analytical study, simplified failure prediction methods were developed for each failure mode. For adhesive failure mode, it is observed that peel stress distributions concur along interface near crack initiation points. All SLJs for this test endured consistent surface treatments. Geometric parameters of the joints were varied to study their effect on failure strength. Peel stress distributions were calculated using finite analysis (FEA). Based on peel stress distribution near crack initiation point, a failure model is proposed. Numerous analytical, empirical and semi-empirical models are available for predicting failure strengths of SLJs generating cohesive failures. However, most of the methods in the literature failed to capture failure behavior of SLJs having thickness of adhesive layer as variable. Cohesive failure mode was generated experimentally using aluminum as adherend and epoxy adhesive considering thickness of adhesive layers as variable within SLJs. Comparative study was performed among various methods. It was observed that

  9. Brain activation induced by psychological stress in patients with schizophrenia.

    PubMed

    Castro, M N; Villarreal, M F; Bolotinsky, N; Papávero, E; Goldschmidt, M G; Costanzo, E Y; Drucaroff, L; Wainsztein, A; de Achával, D; Pahissa, J; Bär, K-J; Nemeroff, C B; Guinjoan, S M

    2015-10-01

    Environmental influences are critical for the expression of genes putatively related to the behavioral and cognitive phenotypes of schizophrenia. Among such factors, psychosocial stress has been proposed to play a major role in the expression of symptoms. However, it is unsettled how stress interacts with pathophysiological pathways to produce the disease. We studied 21 patients with schizophrenia and 21 healthy controls aged 18 to 50years with 3T-fMRI, in which a period of 6min of resting state acquisition was followed by a block design, with three blocks of 1-min control-task, 1-min stress-task and 1-min rest after-task. Self-report of stress and PANSS were measured. Limbic structures were activated in schizophrenia patients by simple tasks and remained active during, and shortly after stress. In controls, stress-related brain activation was more time-focused, and restricted to the stressful task itself. Negative symptom severity was inversely related to activation of anterior cingulum and orbitofrontal cortex. Results might represent the neurobiological aspect of hyper-reactivity to normal stressful situations previously described in schizophrenia, thus providing evidence on the involvement of limbic areas in the response to stress in schizophrenia. Patients present a pattern of persistent limbic activation probably contributing to hypervigilance and subsequent psychotic thought distortions.

  10. Characterization studies on the additives mixed L-arginine phosphate monohydrate (LAP) crystals

    NASA Astrophysics Data System (ADS)

    Haja Hameed, A. S.; Karthikeyan, C.; Ravi, G.; Rohani, S.

    2011-04-01

    L-arginine phosphate monohydrate (LAP), potassium thiocyanate (KSCN) mixed LAP (LAP:KSCN) and sodium sulfite (Na 2SO 3) mixed LAP (LAP:Na 2SO 3) single crystals were grown by slow cooling technique. The effect of microbial contamination and coloration on the growth solutions was studied. The crystalline powders of the grown crystals were examined by X-ray diffraction and the lattice parameters of the crystals were estimated. From the FTIR spectroscopic analysis, various functional group frequencies associated with the crystals were assigned. Vickers microhardness studies were done on {1 0 0} faces for pure and additives mixed LAP crystals. From the preliminary surface second harmonic generation (SHG) results, it was found that the SHG intensity at (1 0 0) face of LAP:KSCN crystal was much stronger than that of pure LAP.

  11. RPC-LAP: The Rosetta Langmuir Probe Instrument

    NASA Astrophysics Data System (ADS)

    Eriksson, A. I.; Boström, R.; Gill, R.; Åhlén, L.; Jansson, S.-E.; Wahlund, J.-E.; André, M.; Mälkki, A.; Holtet, J. A.; Lybekk, B.; Pedersen, A.; Blomberg, L. G.

    2007-02-01

    The Rosetta dual Langmuir probe instrument, LAP, utilizes the multiple powers of a pair of spherical Langmuir probes for measurements of basic plasma parameters with the aim of providing detailed knowledge of the outgassing, ionization, and subsequent plasma processes around the Rosetta target comet. The fundamental plasma properties to be studied are the plasma density, the electron temperature, and the plasma flow velocity. However, study of electric fields up to 8 kHz, plasma density fluctuations, spacecraft potential, integrated UV flux, and dust impacts is also possible. LAP is fully integrated in the Rosetta Plasma Consortium (RPC), the instruments of which together provide a comprehensive characterization of the cometary plasma.

  12. High activity of the stress promoter contributes to susceptibility to stress in the tree shrew

    PubMed Central

    Fang, Hui; Sun, Yun-Jun; Lv, Yan-Hong; Ni, Rong-Jun; Shu, Yu-Mian; Feng, Xiu-Yu; Wang, Yu; Shan, Qing-Hong; Zu, Ya-Nan; Zhou, Jiang-Ning

    2016-01-01

    Stress is increasingly present in everyday life in our fast-paced society and involved in the pathogenesis of many psychiatric diseases. Corticotrophin-releasing-hormone (CRH) plays a pivotal role in regulating the stress responses. The tree shrews are highly vulnerable to stress which makes them the promising animal models for studying stress responses. However, the mechanisms underlying their high stress-susceptibility remained unknown. Here we confirmed that cortisol was the dominate corticosteroid in tree shrew and was significantly increased after acute stress. Our study showed that the function of tree shrew CRH - hypothalamic-pituitary-adrenal (HPA) axis was nearly identical to human that contributed little to their hyper-responsiveness to stress. Using CRH transcriptional regulation analysis we discovered a peculiar active glucocorticoid receptor response element (aGRE) site within the tree shrew CRH promoter, which continued to recruit co-activators including SRC-1 (steroid receptor co-activator-1) to promote CRH transcription under basal or forskolin/dexamethasone treatment conditions. Basal CRH mRNA increased when the aGRE was knocked into the CRH promoter in human HeLa cells using CAS9/CRISPR. The aGRE functioned critically to form the “Stress promoter” that contributed to the higher CRH expression and susceptibility to stress. These findings implicated novel molecular bases of the stress-related diseases in specific populations. PMID:27125313

  13. Stress causes tissue-specific changes in the sialyltransferase activity.

    PubMed

    Dabelic, Sanja; Flögel, Mirna; Maravić, Gordana; Lauc, Gordan

    2004-01-01

    Numerous pathological conditions are associated with specific changes in glycosylation. Recent studies clearly demonstrated a link between stress and the development and course of many diseases. Biochemical mechanisms that link stress and diseases are still not fully understood, but there are some indications that changes in glycosylation are involved in this process. Influence of acute and chronic psychological stress on protein sialylation as well as the activity of sialyltransferases, enzymes that synthesize sialoglycoproteins, has been studied on Fischer rats. Liver, spleen, kidney, skeletal muscle, heart, adrenal gland, serum, cerebellum, hippocampus, medulla oblongata and cortex have been analyzed. Statistically significant tissue- and type of stress-specific changes in total sialyltransferase (ST) activity were observed. Acute stress resulted in 39% increase of ST activity in liver and spleen, while at the same time there was 43% decrease in ST activity in cerebellum. In chronic stress, ST activity increased in spleen (93%) and decreased in liver (17%), cerebellum (38%) and hippocampus (64%). Western-blot analysis using Maackia amurensis and Sambucus nigra lectins did not reveal any difference in protein sialylation. The results of serum corticosterone analysis indicate that showed increase in acute stress and decrease in chronic stress are in good accordance with the hypothesis that corticosterone has a role in the regulation of liver ST activity. PMID:15241940

  14. Stress causes tissue-specific changes in the sialyltransferase activity.

    PubMed

    Dabelic, Sanja; Flögel, Mirna; Maravić, Gordana; Lauc, Gordan

    2004-01-01

    Numerous pathological conditions are associated with specific changes in glycosylation. Recent studies clearly demonstrated a link between stress and the development and course of many diseases. Biochemical mechanisms that link stress and diseases are still not fully understood, but there are some indications that changes in glycosylation are involved in this process. Influence of acute and chronic psychological stress on protein sialylation as well as the activity of sialyltransferases, enzymes that synthesize sialoglycoproteins, has been studied on Fischer rats. Liver, spleen, kidney, skeletal muscle, heart, adrenal gland, serum, cerebellum, hippocampus, medulla oblongata and cortex have been analyzed. Statistically significant tissue- and type of stress-specific changes in total sialyltransferase (ST) activity were observed. Acute stress resulted in 39% increase of ST activity in liver and spleen, while at the same time there was 43% decrease in ST activity in cerebellum. In chronic stress, ST activity increased in spleen (93%) and decreased in liver (17%), cerebellum (38%) and hippocampus (64%). Western-blot analysis using Maackia amurensis and Sambucus nigra lectins did not reveal any difference in protein sialylation. The results of serum corticosterone analysis indicate that showed increase in acute stress and decrease in chronic stress are in good accordance with the hypothesis that corticosterone has a role in the regulation of liver ST activity.

  15. Using quantum dots to tag subsurface damage in lapped and polished glass samples

    SciTech Connect

    Williams, Wesley B.; Mullany, Brigid A.; Parker, Wesley C.; Moyer, Patrick J.; Randles, Mark H.

    2009-09-20

    Grinding, lapping, and polishing are finishing processes used to achieve critical surface parameters in a variety of precision optical and electronic components. As these processes remove material from the surface through mechanical and chemical interactions, they may induce a damaged layer of cracks, voids, and stressed material below the surface. This subsurface damage (SSD) can degrade the performance of a final product by creating optical aberrations due to diffraction, premature failure in oscillating components, and a reduction in the laser induced damage threshold of high energy optics. As these defects lie beneath the surface, they are difficult to detect, and while many methods are available to detect SSD, they can have notable limitations regarding sample size and type, preparation time, or can be destructive in nature. The authors tested a nondestructive method for assessing SSD that consisted of tagging the abrasive slurries used in lapping and polishing with quantum dots (nano-sized fluorescent particles). Subsequent detection of fluorescence on the processed surface is hypothesized to indicate SSD. Quantum dots that were introduced to glass surfaces during the lapping process were retained through subsequent polishing and cleaning processes. The quantum dots were successfully imaged by both wide field and confocal fluorescence microscopy techniques. The detected fluorescence highlighted features that were not observable with optical or interferometric microscopy. Atomic force microscopy and additional confocal microscope analysis indicate that the dots are firmly embedded in the surface but do not appear to travel deep into fractures beneath the surface. Etching of the samples exhibiting fluorescence confirmed that SSD existed. SSD-free samples exposed to quantum dots did not retain the dots in their surfaces, even when polished in the presence of quantum dots.

  16. Chronic psychological stress activates BMP4-dependent extramedullary erythropoiesis.

    PubMed

    Vignjević, Sanja; Budeč, Mirela; Marković, Dragana; Dikić, Dragoslava; Mitrović, Olivera; Mojsilović, Slavko; Durić, Sanja Vranješ; Koko, Vesna; Cokić, Bojana Beleslin; Cokić, Vladan; Jovčić, Gordana

    2014-01-01

    Psychological stress affects different physiological processes including haematopoiesis. However, erythropoietic effects of chronic psychological stress remain largely unknown. The adult spleen contains a distinct microenvironment favourable for rapid expansion of erythroid progenitors in response to stressful stimuli, and emerging evidence suggests that inappropriate activation of stress erythropoiesis may predispose to leukaemic transformation. We used a mouse model to study the influence of chronic psychological stress on erythropoiesis in the spleen and to investigate potential mediators of observed effects. Adult mice were subjected to 2 hrs daily restraint stress for 7 or 14 consecutive days. Our results showed that chronic exposure to restraint stress decreased the concentration of haemoglobin in the blood, elevated circulating levels of erythropoietin and corticosterone, and resulted in markedly increased number of erythroid progenitors and precursors in the spleen. Western blot analysis revealed significantly decreased expression of both erythropoietin receptor and glucocorticoid receptor in the spleen of restrained mice. Furthermore, chronic stress enhanced the expression of stem cell factor receptor in the red pulp. Moreover, chronically stressed animals exhibited significantly increased expression of bone morphogenetic protein 4 (BMP4) in the red pulp as well as substantially enhanced mRNA expression levels of its receptors in the spleen. These findings demonstrate for the first time that chronic psychological stress activates BMP4-dependent extramedullary erythropoiesis and leads to the prolonged activation of stress erythropoiesis pathways. Prolonged activation of these pathways along with an excessive production of immature erythroid cells may predispose chronically stressed subjects to a higher risk of leukaemic transformation. PMID:24283209

  17. Silicon stress/strain activities at JPL

    NASA Technical Reports Server (NTRS)

    Chen, C. P.

    1986-01-01

    In-house Jet Propulsion Laboratory (JPL) work is described for silicon stress/strain, including the study of fracture mechanics, and on the high-temperature test program in which the low-strain response of silicon sheet materials above 1000 C is being measured and high temperature material property data are being determined.

  18. Activity-wheel stress and serotonergic hypersensitivity in rats.

    PubMed

    Mayeda, A R; Simon, J R; Hingtgen, J N; Hofstetter, J R; Aprison, M H

    1989-06-01

    Adult male Wistar rats were subjected to activity wheel stress: unlimited access to an activity wheel for up to twelve days and food for 30 to 60 min each day. Each treated rat was paired with a control, the latter being housed in home cages and given sufficient food to maintain a weight similar to the stressed partner. All rats were previously trained on a variable interval schedule for milk reinforcement. When the activity of the stressed rat increased rapidly then decreased suddenly, the pair was decapitated for biochemical analysis. Levels of the serotonin metabolite, 5-hydroxyindoleacetic acid, decreased by 50%, and the Bmax for ketanserin binding increased by 19% in frontal cortical homogenates from the stressed rats when compared to controls. These data support the concept that stress increases the sensitivity of central serotonin receptors. PMID:2479035

  19. Stress-Induced Out-of-Context Activation of Memory

    PubMed Central

    Ježek, Karel; Lee, Benjamin B.; Kelemen, Eduard; McCarthy, Katharine M.; McEwen, Bruce S.; Fenton, André A.

    2010-01-01

    Inappropriate recollections and responses in stressful conditions are hallmarks of post-traumatic stress disorder and other anxiety and mood disorders, but how stress contributes to the disorders is unclear. Here we show that stress itself reactivates memories even if the memory is unrelated to the stressful experience. Forced-swim stress one day after learning enhanced memory recall. One-day post-learning amnestic treatments were ineffective unless administered soon after the swim, indicating that a stressful experience itself can reactivate unrelated consolidated memories. The swim also triggered inter-hemispheric transfer of a lateralized memory, confirming stress reactivates stable memories. These novel effects of stress on memory required the hippocampus although the memories themselves did not, indicating hippocampus-dependent modulation of extrahippocampal memories. These findings that a stressful experience itself can activate memory suggest the novel hypothesis that traumatic stress reactivates pre-trauma memories, linking them to memory for the trauma and pathological facilitation of post-traumatic recall. PMID:21203585

  20. Dynamical theory of active cellular response to external stress

    NASA Astrophysics Data System (ADS)

    de, Rumi; Safran, Samuel A.

    2008-09-01

    We present a comprehensive, theoretical treatment of the orientational response to external stress of active, contractile cells embedded in a gel-like elastic medium. The theory includes both the forces that arise from the deformation of the matrix as well as forces due to the internal regulation of the stress fibers and focal adhesions of the cell. We calculate the time-dependent response of both the magnitude and the direction of the elastic dipole that characterizes the active forces exerted by the cell, for various situations. For static or quasistatic external stress, cells orient parallel to the stress while for high frequency dynamic external stress, cells orient nearly perpendicular. Both numerical and analytical calculations of these effects are presented. In addition we predict the relaxation time for the cellular response for both slowly and rapidly varying external stresses; several characteristic scaling regimes for the relaxation time as a function of applied frequency are predicted. We also treat the case of cells for which the regulation of the stress fibers and focal adhesions is controlled by strain (instead of stress) and show that the predicted dependence of the cellular orientation on the Poisson ratio of the matrix can differentiate strain vs stress regulation of cellular response.

  1. Dynamical theory of active cellular response to external stress.

    PubMed

    De, Rumi; Safran, Samuel A

    2008-09-01

    We present a comprehensive, theoretical treatment of the orientational response to external stress of active, contractile cells embedded in a gel-like elastic medium. The theory includes both the forces that arise from the deformation of the matrix as well as forces due to the internal regulation of the stress fibers and focal adhesions of the cell. We calculate the time-dependent response of both the magnitude and the direction of the elastic dipole that characterizes the active forces exerted by the cell, for various situations. For static or quasistatic external stress, cells orient parallel to the stress while for high frequency dynamic external stress, cells orient nearly perpendicular. Both numerical and analytical calculations of these effects are presented. In addition we predict the relaxation time for the cellular response for both slowly and rapidly varying external stresses; several characteristic scaling regimes for the relaxation time as a function of applied frequency are predicted. We also treat the case of cells for which the regulation of the stress fibers and focal adhesions is controlled by strain (instead of stress) and show that the predicted dependence of the cellular orientation on the Poisson ratio of the matrix can differentiate strain vs stress regulation of cellular response.

  2. Left brain cortical activity modulates stress effects on social behavior

    PubMed Central

    Lee, Eunee; Hong, Jiso; Park, Young-Gyun; Chae, Sujin; Kim, Yong; Kim, Daesoo

    2015-01-01

    When subjected to stress, some individuals develop maladaptive symptoms whereas others retain normal behavior. The medial prefrontal cortex (mPFC) is known to control these adaptive responses to stress. Here, we show that mPFC neurons in the left hemisphere control stress effects on social behavior. Mice made socially avoidant by the stress of chronic social defeats showed depressed neural activity in the left mPFC. Photoactivation of these neurons reversed social avoidance and restored social activity. Despite social defeats, resilient mice with normal sociability showed normal firing rates in the left mPFC; however, photoinhibition of these neurons induced social avoidance. The same photomodulation administered to the right mPFC caused no significant effects. These results explain how stressed individuals develop maladaptive behaviors through left cortical depression, as reported in mood and anxiety disorders. PMID:26302668

  3. Transition from stress-driven to thermally activated stress relaxation in metallic glasses

    NASA Astrophysics Data System (ADS)

    Qiao, J. C.; Wang, Yun-Jiang; Zhao, L. Z.; Dai, L. H.; Crespo, D.; Pelletier, J. M.; Keer, L. M.; Yao, Y.

    2016-09-01

    The short-range ordered but long-range disordered structure of metallic glasses yields strong structural and dynamic heterogeneities. Stress relaxation is a technique to trace the evolution of stress in response to a fixed strain, which reflects the dynamic features phenomenologically described by the Kohlrausch-Williams-Watts (KWW) equation. The KWW equation describes a broad distribution of relaxation times with a small number of empirical parameters, but it does not arise from a particular physically motivated mechanistic picture. Here we report an anomalous two-stage stress relaxation behavior in a Cu46Zr46Al8 metallic glass over a wide temperature range and generalize the findings in other compositions. Thermodynamic analysis identifies two categories of processes: a fast stress-driven event with large activation volume and a slow thermally activated event with small activation volume, which synthetically dominates the stress relaxation dynamics. Discrete analyses rationalize the transition mechanism induced by stress and explain the anomalous variation of the KWW characteristic time with temperature. Atomistic simulations reveal that the stress-driven event involves virtually instantaneous short-range atomic rearrangement, while the thermally activated event is the percolation of the fast event accommodated by the long-range atomic diffusion. The insights may clarify the underlying physical mechanisms behind the phenomenological description and shed light on correlating the hierarchical dynamics and structural heterogeneity of amorphous solids.

  4. Family History Predicts Stress Fracture in Active Female Adolescents

    PubMed Central

    Loud, Keith J.; Micheli, Lyle J.; Bristol, Stephanie; Austin, S. Bryn; Gordon, Catherine M.

    2011-01-01

    OBJECTIVE Increased physical activity and menstrual irregularity have been associated with increased risk for stress fracture among adult women active in athletics. The purposes of this study were to determine whether menstrual irregularity is also a risk factor for stress fracture in active female adolescents and to estimate the quantity of exercise associated with an increased risk for this injury. PATIENTS AND METHODS A case-control study was conducted of 13- to 22-year-old females diagnosed with their first stress fracture, each matched prospectively on age and self-reported ethnicity with 2 controls. Patients with chronic illnesses or use of medications known to affect bone mineral density were excluded, including use of hormonal preparations that could alter menstrual cycles. The primary outcome, stress fracture in any extremity or the spine, was confirmed radiographically. Girls with stress fracture had bone mineral density measured at the lumbar spine by dual-energy x-ray absorptiometry. RESULTS The mean ± SD age of the 168 participants was 15.9 ± 2.1 years; 91.7% were postmenarchal, with a mean age at menarche of 13.1 ± 1.1 years. The prevalence of menstrual irregularity was similar among cases and controls. There was no significant difference in the mean hours per week of total physical activity between girls in this sample with stress fracture (8.2 hours/week) and those without (7.4 hours/week). In multivariate models, case subjects had nearly 3 times the odds of having a family member with osteoporosis or osteopenia. In secondary analyses, participants with stress fracture had a low mean spinal bone mineral density for their age. CONCLUSIONS Among highly active female adolescents, only family history was independently associated with stress fracture. The magnitude of this association suggests that further investigations of inheritable skeletal factors are warranted in this population, along with evaluation of bone mineral density in girls with stress

  5. A multicopy sRNA of Listeria monocytogenes regulates expression of the virulence adhesin LapB

    PubMed Central

    Sievers, Susanne; Sternkopf Lillebæk, Eva Maria; Jacobsen, Kirstine; Lund, Anja; Mollerup, Maria Storm; Nielsen, Pia Kiil; Kallipolitis, Birgitte Haahr

    2014-01-01

    The multicopy sRNA LhrC of the intracellular pathogen Listeria monocytogenes has been shown to be induced under infection-relevant conditions, but its physiological role and mechanism of action is not understood. In an attempt to pinpoint the exact terms of LhrC expression, cell envelope stress could be defined as a specific inducer of LhrC. In this process, the two-component system LisRK was shown to be indispensable for expression of all five copies of LhrC. lapB mRNA, encoding a cell wall associated protein that was recently identified as an important virulence factor, was disclosed to be directly bound by LhrC leading to an impediment of its translation. Although LhrC binds to Hfq, it does not require the RNA chaperone for stability or lapB mRNA interaction. The mechanism of LhrC-lapB mRNA binding was shown to involve three redundant CU-rich sites and a structural rearrangement in the sRNA. This study represents an extensive depiction of a so far uncharacterized multicopy sRNA and reveals interesting new aspects concerning its regulation, virulence association and mechanism of target binding. PMID:25034691

  6. Hsp65-producing Lactococcus lactis prevents experimental autoimmune encephalomyelitis in mice by inducing CD4+LAP+ regulatory T cells.

    PubMed

    Rezende, Rafael M; Oliveira, Rafael P; Medeiros, Samara R; Gomes-Santos, Ana C; Alves, Andrea C; Loli, Flávia G; Guimarães, Mauro A F; Amaral, Sylvia S; da Cunha, André P; Weiner, Howard L; Azevedo, Vasco; Miyoshi, Anderson; Faria, Ana M C

    2013-02-01

    Heat shock proteins (Hsps) participate in the cellular response to stress and they are hiperexpressed in inflammatory conditions. They are also known to play a major role in immune modulation, controlling, for instance, autoimmune responses. In this study, we showed that oral administration of a recombinant Lactococcus lactis strain that produces and releases LPS-free Hsp65 prevented the development of experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice. This was confirmed by the reduced inflammatory cell infiltrate and absence of injury signs in the spinal cord. The effect was associated with reduced IL-17 and increased IL-10 production in mesenteric lymph node and spleen cell cultures. Hsp65-producing-L. lactis-fed mice had a remarkable increase in the number of natural and inducible CD4+Foxp3+ regulatory T (Treg) cells and CD4+LAP+ (Latency-associated peptide) Tregs - which express the membrane-bound TGF-β - in spleen, inguinal and mesenteric lymph nodes as well as in spinal cord. Moreover, many Tregs co-expressed Foxp3 and LAP. In vivo depletion of LAP+ cells abrogated the effect of Hsp65-producing L. lactis in EAE prevention and worsened disease in medium-fed mice. Thus, Hsp65-L.lactis seems to boost this critical regulatory circuit involved in controlling EAE development in mice. PMID:22939403

  7. Hsp65-producing Lactococcus lactis prevents experimental autoimmune encephalomyelitis in mice by inducing CD4+LAP+ regulatory T cells

    PubMed Central

    Rezende, Rafael M.; Oliveira, Rafael P.; Medeiros, Samara R.; Gomes-Santos, Ana C.; Alves, Andrea C.; Loli, Flávia G.; Guimarães, Mauro A.F.; Amaral, Sylvia S.; da Cunha, André P.; Weiner, Howard L.; Azevedo, Vasco; Miyoshi, Anderson; Faria, Ana M.C.

    2013-01-01

    Heat shock proteins (Hsps) participate in the cellular response to stress and they are hiperexpressed in inflammatory conditions. They are also known to play a major role in immune modulation, controlling, for instance, autoimmune responses. In this study, we showed that oral administration of a recombinant Lactococcus lactis strain that produces and releases LPS-free Hsp65 prevented the development of experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice. This was confirmed by the reduced inflammatory cell infiltrate and absence of injury signs in the spinal cord. The effect was associated with reduced IL-17 and increased IL-10 production in mesenteric lymph node and spleen cell cultures. Hsp65-producing-L. lactis-fed mice had a remarkable increase in the number of natural and inducible CD4+Foxp3+ regulatory T (Treg) cells and CD4+LAP+ (Latency-associated peptide) Tregs - which express the membrane-bound TGF-β - in spleen, inguinal and mesenteric lymph nodes as well as in spinal cord. Moreover, many Tregs co-expressed Foxp3 and LAP. In vivo depletion of LAP+ cells abrogated the effect of Hsp65-producing L. lactis in EAE prevention and worsened disease in medium-fed mice. Thus, Hsp65-L.lactis seems to boost this critical regulatory circuit involved in controlling EAE development in mice. PMID:22939403

  8. Hsp65-producing Lactococcus lactis prevents experimental autoimmune encephalomyelitis in mice by inducing CD4+LAP+ regulatory T cells.

    PubMed

    Rezende, Rafael M; Oliveira, Rafael P; Medeiros, Samara R; Gomes-Santos, Ana C; Alves, Andrea C; Loli, Flávia G; Guimarães, Mauro A F; Amaral, Sylvia S; da Cunha, André P; Weiner, Howard L; Azevedo, Vasco; Miyoshi, Anderson; Faria, Ana M C

    2013-02-01

    Heat shock proteins (Hsps) participate in the cellular response to stress and they are hiperexpressed in inflammatory conditions. They are also known to play a major role in immune modulation, controlling, for instance, autoimmune responses. In this study, we showed that oral administration of a recombinant Lactococcus lactis strain that produces and releases LPS-free Hsp65 prevented the development of experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice. This was confirmed by the reduced inflammatory cell infiltrate and absence of injury signs in the spinal cord. The effect was associated with reduced IL-17 and increased IL-10 production in mesenteric lymph node and spleen cell cultures. Hsp65-producing-L. lactis-fed mice had a remarkable increase in the number of natural and inducible CD4+Foxp3+ regulatory T (Treg) cells and CD4+LAP+ (Latency-associated peptide) Tregs - which express the membrane-bound TGF-β - in spleen, inguinal and mesenteric lymph nodes as well as in spinal cord. Moreover, many Tregs co-expressed Foxp3 and LAP. In vivo depletion of LAP+ cells abrogated the effect of Hsp65-producing L. lactis in EAE prevention and worsened disease in medium-fed mice. Thus, Hsp65-L.lactis seems to boost this critical regulatory circuit involved in controlling EAE development in mice.

  9. Structural Features of the Pseudomonas fluorescens Biofilm Adhesin LapA Required for LapG-Dependent Cleavage, Biofilm Formation, and Cell Surface Localization

    PubMed Central

    Boyd, Chelsea D.; Smith, T. Jarrod; El-Kirat-Chatel, Sofiane; Newell, Peter D.; Dufrêne, Yves F.

    2014-01-01

    The localization of the LapA protein to the cell surface is a key step required by Pseudomonas fluorescens Pf0-1 to irreversibly attach to a surface and form a biofilm. LapA is a member of a diverse family of predicted bacterial adhesins, and although lacking a high degree of sequence similarity, family members do share common predicted domains. Here, using mutational analysis, we determine the significance of each domain feature of LapA in relation to its export and localization to the cell surface and function in biofilm formation. Our previous work showed that the N terminus of LapA is required for cleavage by the periplasmic cysteine protease LapG and release of the adhesin from the cell surface under conditions unfavorable for biofilm formation. We define an additional critical region of the N terminus of LapA required for LapG proteolysis. Furthermore, our results suggest that the domains within the C terminus of LapA are not absolutely required for biofilm formation, export, or localization to the cell surface, with the exception of the type I secretion signal, which is required for LapA export and cell surface localization. In contrast, deletion of the central repetitive region of LapA, consisting of 37 repeats of 100 amino acids, results in an inability to form a biofilm. We also used single-molecule atomic force microscopy to further characterize the role of these domains in biofilm formation on hydrophobic and hydrophilic surfaces. These studies represent the first detailed analysis of the domains of the LapA family of biofilm adhesin proteins. PMID:24837291

  10. Design Concepts. Teacher Edition. Marketing Education LAPs.

    ERIC Educational Resources Information Center

    Hawley, Jana

    This learning activity packet is designed to help prepare students to acquire a competency: how to use design concepts in preparation for a career in the fashion industry. The unit consists of the competency, four objectives, suggested learning activities, transparency masters, and a pretest/posttest with answer keys. Activities include a…

  11. The Effects of Stress on Physical Activity and Exercise

    PubMed Central

    Stults-Kolehmainen, Matthew A.; Sinha, Rajita

    2013-01-01

    Background Psychological stress and physical activity (PA) are believed to be reciprocally related; however, most research examining the relationship between these constructs is devoted to the study of exercise and/or PA as an instrument to mitigate distress. Objective The aim of this paper was to review the literature investigating the influence of stress on indicators of PA and exercise. Methods A systematic search of Web of Science, Pub-Med, and SPORTDiscus was employed to find all relevant studies focusing on human participants. Search terms included “stress”, “exercise”, and “physical activity”. A rating scale (0–9) modified for this study was utilized to assess the quality of all studies with multiple time points. Results The literature search found 168 studies that examined the influence of stress on PA. Studies varied widely in their theoretical orientation and included perceived stress, distress, life events, job strain, role strain, and work–family conflict but not lifetime cumulative adversity. To more clearly address the question, prospective studies (n = 55) were considered for further review, the majority of which indicated that psychological stress predicts less PA (behavioral inhibition) and/or exercise or more sedentary behavior (76.4 %). Both objective (i.e., life events) and subjective (i.e., distress) measures of stress related to reduced PA. Prospective studies investigating the effects of objective markers of stress nearly all agreed (six of seven studies) that stress has a negative effect on PA. This was true for research examining (a) PA at periods of objectively varying levels of stress (i.e., final examinations vs. a control time point) and (b) chronically stressed populations (e.g., caregivers, parents of children with a cancer diagnosis) that were less likely to be active than controls over time. Studies examining older adults (>50 years), cohorts with both men and women, and larger sample sizes (n > 100) were more likely

  12. Intrinsic mechanisms of pain inhibition: activation by stress.

    PubMed

    Terman, G W; Shavit, Y; Lewis, J W; Cannon, J T; Liebeskind, J C

    1984-12-14

    Portions of the brain stem seem normally to inhibit pain. In man and laboratory animals these brain areas and pathways from them to spinal sensory circuits can be activated by focal stimulation. Endogenous opioids appear to be implicated although separate nonopioid mechanisms are also evident. Stress seems to be a natural stimulus triggering pain suppression. Properties of electric footshock have been shown to determine the opioid or nonopioid basis of stress-induced analgesia. Two different opioid systems can be activated by different footshock paradigms. This dissection of stress analgesia has begun to integrate divergent findings concerning pain inhibition and also to account for some of the variance that has obscured the reliable measurement of the effects of stress on tumor growth and immune function.

  13. Social Support Can Buffer against Stress and Shape Brain Activity

    PubMed Central

    Hostinar, Camelia E.; Gunnar, Megan R.

    2015-01-01

    Social support from close relationship partners is an important resource for coping with stress, particularly during childhood. We discuss ethical challenges associated with studying stress and its social buffering in the laboratory, as well as emerging evidence regarding two potential neural substrates for the social buffering of stress: hypothalamic oxytocin activity and activation of areas in the prefrontal cortex associated with effective self-regulation. We also address the role of early-life social experiences in shaping brain development, as well as recommendations for practice and policy that would advance the ethical treatment of children and reduce social inequalities in early-life experiences and opportunities–e.g., investing in programs that prevent child maltreatment and facilitating access to high-quality child care for economically disadvantaged families. We also debate the ethical implications of using oxytocin nasal sprays to simulate the stress-reducing properties of social support and advise waiting for more evidence before recommending their use. PMID:26478822

  14. FRICTION-STIR-LAP-WELDS OF AA6111 ALUMINUM ALLOY

    SciTech Connect

    Yadava, Manasij; Mishra, Rajiv S.; Chen, Y. L.; Gayden, X.; Grant, Glenn J.

    2007-01-09

    Lap joints of 1 mm thick AA6111 aluminum sheets were made by friction stir welding, using robotic and conventional machines. Welds were made for advancing as well as retreating side loading. Thinning in welds was quantified. Lap shear test of welds was conducted in as-welded and paint-baked conditions. Conventional machine welds showed less thinning and better strength than robotic machine welds. Process forces in conventional machine welding were higher. Paint bake treatment improved the weld strength; but the improvement varied with process parameters. Advancing side loaded welds achieved higher strength than the retreating side loaded welds. Fracture location was found to occur on the loaded side of the weld and along the thinning defect.

  15. The impact of lubricants on the precision lapping process.

    PubMed

    Jiang, Xionghua; Chen, Zhenxing; Wolfram, Joy; Wei, Zhongxian; Shen, Yuqiu; Yang, Zhizhou

    2014-12-01

    The impact of lubricants on pole-tip recession and surface morphology of hard disk drive heads in the precision lapping process was investigated with atomic force microscopy, scanning electron microscopy, and auger electron spectroscopy. In particular, the effects of deionized water, hydrocarbon oil, ethanediol, isopropanol, and ethanol lubricants were evaluated. The results reveal that proper selection of lubricant is critical for achieving optimal performance in the lapping process. A mixture of 68% hydrocarbon oil, 30% isopropanol, and 2% octadecenoic acid was found to yield the most favorable results, displaying a writer shield recession, first shield of reader recession, and surface roughness of 0.423, 0.581, and 0.242 nm, respectively. PMID:25387606

  16. Piano Playing Reduces Stress More than Other Creative Art Activities

    ERIC Educational Resources Information Center

    Toyoshima, Kumiko; Fukui, Hajime; Kuda, Kiyoto

    2011-01-01

    Few studies have been conducted on the physiological effects of creative art activities. In this study, the effects of creative art activities on human stress were investigated, and their effects were compared in 57 healthy college students (27 males and 30 females). Subjects were divided into four groups, each of which participated in 30-minute…

  17. Active stresses and hydrodynamics of microtubule/motor-protein assemblies

    NASA Astrophysics Data System (ADS)

    Shelley, Michael

    2014-03-01

    In biologically-inspired soft active materials, chemical energy (typically from ATP) is transduced to generate active stresses arising from reconiguration or forcing of the microstructure. This can lead to novel material organization, mechanical properties, and active flows. While much focus has been on active gels and motile suspensions, another important class are suspensions of microtubules (MTs) crosslinked by motile molecular motors. These are central actors in biological phenomena such as pronuclear transport and spindle formation. Here we develop a multi-scale theory for studying such systems. At the discrete level, we use Brownian dynamics of MTs with moving crosslinks to study microscopic organization and active stress development. We observe, surprisingly, that activity generated extensile stresses arise from both polarity sorting and crosslink relaxation. These simulations estimate polarity-dependent active stress coeffcients in a Doi-Onsager kinetic theory - similar to those developed previously for motile suspensions - that captures polarity sorting and induced hydrodynamic flows. In simulating recent experiments of active flows on immersed surfaces, the model exhibits turbulent-like dynamics, and the continous generation and annihilation of disclination defects associated with coherent flow structures. We can associate the system's coherent features with instabilities of aligned linear and nonlinear states.

  18. Ants cushion applied stress by active rearrangements

    NASA Astrophysics Data System (ADS)

    Liu, Zhongyang; Hyatt, John; Mlot, Nathan; Gerov, Michael; Fernandez-Nieves, Alberto; Hu, David

    2013-11-01

    Fire ants, Solenopsis invicta, link their bodies together to form waterproof rafts, which in turn drip, spread, and coagulate, demonstrating properties of an active material that can change state from a liquid to a solid. This soft-matter phase transition is important when the raft interacts with environmental forces such as raindrops and crashing waves. We study this active behavior through plate-on-plate rheology on the ants, extracting the active components by comparison with the rheological behavior of a collection of dead ants. In controlled shear tests, both and live and dead ants show properties of a non-Newtonian fluid, specifically, shear-thinning behavior. In oscillatory tests, live ants exhibit a rare behavior in which their storage modulus (G') and loss modulus (G'') have approximately the same value over three orders magnitudes of frequency and two orders of magnitude of strain, indicating the ants are neither fluid nor solid. In comparison, dead ants are more solid-like, with a storage modulus twice as large as their loss modulus. This striking active behavior arises from rearrangement of their bodies and storage and dissipation of energy with the ants' muscles.

  19. Textiles. Teacher Edition. Marketing Education LAPs.

    ERIC Educational Resources Information Center

    Hawley, Jana

    This learning activity packet is designed to help students to acquire a competency: how to use knowledge of textile design to gain expertise in preparation for a career in the fashion industry. The unit consists of the competency, four objectives, suggested learning activities, transparency masters, and a pretest/posttest with answer keys.…

  20. Investigation into Interface Lifting Within FSW Lap Welds

    SciTech Connect

    K. S. Miller; C. R. Tolle; D. E. Clark; C. I. Nichol; T. R. McJunkin; H. B. Smartt

    2008-06-01

    Friction stir welding (FSW) is rapidly penetrating the welding market in many materials and applications, particularly in aluminum alloys for transportation applications. As this expansion outside the research laboratory continues, fitness for service issues will arise, and process control and NDE methods will become important determinants of continued growth. The present paper describes research into FSW weld nugget flaw detection within aluminum alloy lap welds. We present results for two types of FSW tool designs: a smooth pin tool and a threaded pin tool. We show that under certain process parameters (as monitored during welding with a rotating dynamometer that measures x, y, z, and torque forces) and tooling designs, FSW lap welds allow significant nonbonded interface lifting of the lap joint, while forming a metallurgical bond only within the pin region of the weld nugget. These lifted joints are often held very tightly together even though unbonded, and might be expected to pass cursory NDE while representing a substantial compromise in joint mechanical properties. The phenomenon is investigated here via radiographic and ultrasonic NDE techniques, with a copper foil marking insert (as described elsewhere) and by the tensile testing of joints. As one would expect, these results show that tool design and process parameters significantly affect plactic flow and this lifted interface. NDE and mechanical strength ramifications of this defect are discussed.

  1. Residual Strength Analyses of Riveted Lap-Splice Joints

    NASA Technical Reports Server (NTRS)

    Seshadri, B. R.; Newman, J. C., Jr.

    2000-01-01

    The objective of this paper was to analyze the crack-linkup behavior in riveted-stiffened lap-splice joint panels with small multiple-site damage (MSD) cracks at several adjacent rivet holes. Analyses are based on the STAGS (STructural Analysis of General Shells) code with the critical crack-tip-opening angle (CTOA) fracture criterion. To account for high constraint around a crack front, the "plane strain core" option in STAGS was used. The importance of modeling rivet flexibility with fastener elements that accurately model load transfer across the joint is discussed. Fastener holes are not modeled but rivet connectivity is accounted for by attaching rivets to the sheet on one side of the cracks that simulated both the rivet diameter and MSD cracks. Residual strength analyses made on 2024-T3 alloy (1.6-mm thick) riveted-lap-splice joints with a lead crack and various size MSD cracks were compared with test data from Boeing Airplane Company. Analyses were conducted for both restrained and unrestrained buckling conditions. Comparison of results from these analyses and results from lap-splice-joint test panels, which were partially restrained against buckling indicate that the test results were bounded by the failure loads predicted by the analyses with restrained and unrestrained conditions.

  2. Strength analysis of laser welded lap joint for ultra high strength steel

    NASA Astrophysics Data System (ADS)

    Jeong, Young Cheol; Kim, Cheol Hee; Cho, Young Tae; Jung, Yoon Gyo

    2013-12-01

    Several industries including the automotive industry have recently applied the process of welding high strength steel. High strength steel is steel that is harder than normal high strength steel, making it much stronger and stiffer. HSS can be formed in pieces that can be up to 10 to 15 percent thinner than normal steel without sacrificing strength, which enables weight reduction and improved fuel economy. Furthermore, HSS can be formed into complex shapes that can be welded into structural areas. This study is based on previous experiments and is aimed at establishing the stress distribution for laser welded high strength steel. Research on the stress distribution for laser welded high strength steel is conducted by using Solid Works, a program that analyzes the stress of a virtual model. In conclusion, we found that the stress distribution is changed depending on the shape of welded lap joint. In addition, the Influence of the stress distribution on welded high strength steel can be used to standard for high energy welding of high strength steel, and we can also predict the region in welded high strength steel that may cracked.

  3. Adhesive-bonded double-lap joints. [analytical solutions for static load carrying capacity

    NASA Technical Reports Server (NTRS)

    Hart-Smith, L. J.

    1973-01-01

    Explicit analytical solutions are derived for the static load carrying capacity of double-lap adhesive-bonded joints. The analyses extend the elastic solution Volkersen and cover adhesive plasticity, adherend stiffness imbalance and thermal mismatch between the adherends. Both elastic-plastic and bi-elastic adhesive representations lead to the explicit result that the influence of the adhesive on the maximum potential bond strength is defined uniquely by the strain energy in shear per unit area of bond. Failures induced by peel stresses at the ends of the joint are examined. This failure mode is particularly important for composite adherends. The explicit solutions are sufficiently simple to be used for design purposes

  4. New concepts for strength enhancement of co-cured composite single lap joints

    NASA Astrophysics Data System (ADS)

    Coates, Cameron Wayne

    2001-10-01

    Often the benefits of utilizing composites are diminished by the poor performance of their joint designs. This research examines designs that seek to improve the performance of composite co-cured single lap joints under static and fatigue loading, with only minor alteration to the geometry or lay-up of a base design. The minor alteration criterion was chosen in order to reduce the cost of implementing these designs in replacing existing joints or altering existing manufacturing methods. The approach consisted of two phases, denoted Phase I and II. Phase I consisted of monotonic tests for all the proposed designs as well as Finite Element Analysis of the design showing the most improvement. The objective of Phase I was to determine whether the designs would improve monotonic strength at the joint interface and identify the most effective designs. The designs tested during Phase I may be categorized as Single Nested Overlap, Half Slice, Full Slice and Transverse Layer. The preliminary tests consisted of single lap joint composites with altered and unaltered interfaces tested under uniform extension. The configurations examined include a quasi-isotropic lay-up and a unidirectional lay-up, however the designs are applicable to any lay-up. A comparison of ultimate strengths indicated that these designs offered improvement in strength. During testing, acoustic emission equipment was used to monitor damage progression as well as detect damage initiation and accumulation. The most consistent and practical design improvements were determined to be the Single Nested Overlap and Transverse Layer configurations. A Finite Element Analysis (FEA) of the Reference joint and the Single Nested Overlap joint was performed. FE predictions of the effectiveness of the nested overlap design support the test data through a reduction in shear stress and a reversal of peel stresses.

  5. Activation of the hypothalamic-pituitary-adrenal stress axis induces cellular oxidative stress

    PubMed Central

    Spiers, Jereme G.; Chen, Hsiao-Jou Cortina; Sernia, Conrad; Lavidis, Nickolas A.

    2015-01-01

    Glucocorticoids released from the adrenal gland in response to stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis induce activity in the cellular reduction-oxidation (redox) system. The redox system is a ubiquitous chemical mechanism allowing the transfer of electrons between donor/acceptors and target molecules during oxidative phosphorylation while simultaneously maintaining the overall cellular environment in a reduced state. The objective of this review is to present an overview of the current literature discussing the link between HPA axis-derived glucocorticoids and increased oxidative stress, particularly focussing on the redox changes observed in the hippocampus following glucocorticoid exposure. PMID:25646076

  6. Apparatus and method for lapping an edge surface of an object

    NASA Technical Reports Server (NTRS)

    Rossi, Vito N. (Inventor)

    1989-01-01

    An apparatus for lapping an edge surface of an object comprises a block having a side adapted to engage a wide surface of an object, adjustable spacers disposed on the block and adapted to engage a lap plate, and a weighted spring disposed on the block for urging the spacers and the object edge surface towards the lap plate. A method for lapping comprises setting surfaces of adjustable spacers disposed on a block to be substantially the same distance from the block, affixing a wide surface of an object to the block, urging an edge surface of the object and the spacers towards a lap plate, lapping the edge of the object, inspecting the edge for parallelism to a reference line, resetting the spacers and relapping the edge surface.

  7. Optimal tubular adhesive-bonded lap joint of the carbon fiber epoxy composite shaft

    NASA Astrophysics Data System (ADS)

    Kim, Ki S.; Kim, Won T.; Lee, Dai G.; Jun, Eui J.

    The effects of the adhesive thickness and the adherend surface roughness on the fatigue strength of a tubular adhesive-bonded single lap joint were investigated using fatigue test specimens whose adherends were made of S45C carbon steel. Results of fatigue tests showed that the optimal arithmetic surface roughness of the adherends is about 2 microns and the optimal adhesive thickness is about 0.15 mm. Using these values, the prototype torsional adhesive joints were manufactured for power transmission shafts of an automotive vehicle or a small helicopter, and static tests under torque were performed on a single-lap joint, a single-lap joint with scarf, a double-lap joint, and a double-lap joint with scarf. It was found that the double-lap joint was superior among the joints, in terms of torque capacity and manufacturing cost.

  8. Learning Activity Packets for Milling Machines. Unit III--Vertical Milling Machines.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This learning activity packet (LAP) outlines the study activities and performance tasks covered in a related curriculum guide on milling machines. The course of study in this LAP is intended to help students learn to set up and operate a vertical mill. Tasks addressed in the LAP include mounting and removing cutters and cutter holders for vertical…

  9. Learning Activity Packets for Milling Machines. Unit II--Horizontal Milling Machines.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This learning activity packet (LAP) outlines the study activities and performance tasks covered in a related curriculum guide on milling machines. The course of study in this LAP is intended to help students learn to set up and operate a horizontal mill. Tasks addressed in the LAP include mounting style "A" or "B" arbors and adjusting arbor…

  10. Photo-induced bending in a light-activated polymer laminated composite.

    PubMed

    Mu, Xiaoming; Sowan, Nancy; Tumbic, Julia A; Bowman, Christopher N; Mather, Patrick T; Qi, H Jerry

    2015-04-01

    Light activated polymers (LAPs) have attracted increasing attention since these materials change their shape and/or behavior in response to light exposure, which serves as an instant, remote and precisely controllable stimulus that enables non-contact control of the material shape and behavior through simple variation in light intensity, wavelength and spatially controlled exposure. These features distinguish LAPs from other active polymers triggered by other stimuli such as heat, electrical field or humidity. Previous examples have resulted in demonstrations in applications such as surface patterning, photo-induced shape memory behavior, and photo-origami. However, in many of these applications, an undesirable limitation has been the requirement to apply and maintain an external load during light irradiation. In this paper, a laminated structure is introduced to provide a pre-programmed stress field, which is then used for photo-induced deformation. This laminated structure is fabricated by bonding a stretched elastomer (NOA65) sheet between two LAP layers. Releasing the elastomer causes contraction and introduces a compressive stress in the LAPs, which are relaxed optically to trigger the desired deformation. A theoretical model is developed to quantitatively examine the laminated composite system, allowing exploration of the design space and optimum design of the laminate. PMID:25690905

  11. Physical activity buffers fatigue only under low chronic stress.

    PubMed

    Strahler, Jana; Doerr, Johanna M; Ditzen, Beate; Linnemann, Alexandra; Skoluda, Nadine; Nater, Urs M

    2016-09-01

    Fatigue is one of the most commonly reported complaints in the general population. As physical activity (PA) has been shown to have beneficial effects, we hypothesized that everyday life PA improves fatigue. Thirty-three healthy students (21 women, 22.8 ± 3.3 years, 21.7 ± 2.3 kg/m(2)) completed two ambulatory assessment periods. During five days at the beginning of the semester (control condition) and five days during final examination preparation (examination condition), participants repeatedly reported on general fatigue (awakening, 10 am, 2 pm, 6 pm and 9 pm) by means of an electronic diary, collected saliva samples for the assessment of cortisol and α-amylase immediately after providing information on fatigue and wore a triaxial accelerometer to continuously record PA. Self-perceived chronic stress was assessed as a moderator. Using hierarchical linear modeling, including PA, condition (control vs. examination), sex and chronic stress as predictors, PA level during the 15 min prior to data entry did not predict momentary fatigue level. Furthermore, there was no effect of condition. However, a significant cross-level interaction of perceived chronic stress with PA was observed. In fact, the (negative) relationship between PA and fatigue was stronger in those participants with less chronic stress. Neither cortisol nor α-amylase was significantly related to physical activity or fatigue. Our study showed an immediate short-term buffering effect of everyday life PA on general fatigue, but only when experiencing lower chronic stress. There seems to be no short-term benefit of PA in the face of higher chronic stress. These findings highlight the importance of considering chronic stress when evaluating the effectiveness of PA interventions in different target populations, in particular among chronically stressed and fatigued subjects.

  12. Fluid Shear Stress Increases Neutrophil Activation via Platelet-Activating Factor

    PubMed Central

    Mitchell, Michael J.; Lin, Kimberly S.; King, Michael R.

    2014-01-01

    Leukocyte exposure to hemodynamic shear forces is critical for physiological functions including initial adhesion to the endothelium, the formation of pseudopods, and migration into tissues. G-protein coupled receptors on neutrophils, which bind to chemoattractants and play a role in neutrophil chemotaxis, have been implicated as fluid shear stress sensors that control neutrophil activation. Recently, exposure to physiological fluid shear stresses observed in the microvasculature was shown to reduce neutrophil activation in the presence of the chemoattractant formyl-methionyl-leucyl-phenylalanine. Here, however, human neutrophil preexposure to uniform shear stress (0.1–2.75 dyn/cm2) in a cone-and-plate viscometer for 1–120 min was shown to increase, rather than decrease, neutrophil activation in the presence of platelet activating factor (PAF). Fluid shear stress exposure increased PAF-induced neutrophil activation in terms of L-selectin shedding, αMβ2 integrin activation, and morphological changes. Neutrophil activation via PAF was found to correlate with fluid shear stress exposure, as neutrophil activation increased in a shear stress magnitude- and time-dependent manner. These results indicate that fluid shear stress exposure increases neutrophil activation by PAF, and, taken together with previous observations, differentially controls how neutrophils respond to chemoattractants. PMID:24853753

  13. Fractalkine Attenuates Microglial Cell Activation Induced by Prenatal Stress

    PubMed Central

    Ślusarczyk, Joanna; Trojan, Ewa; Głombik, Katarzyna; Chamera, Katarzyna; Roman, Adam; Budziszewska, Bogusława; Basta-Kaim, Agnieszka

    2016-01-01

    The potential contribution of inflammation to the development of neuropsychiatric diseases has recently received substantial attention. In the brain, the main immune cells are the microglia. As they are the main source of inflammatory factors, it is plausible that the regulation of their activation may be a potential therapeutic target. Fractalkine (CX3CL1) and its receptor CX3CR1 play a crucial role in the control of the biological activity of the microglia. In the present study, using microglial cultures we investigated whether fractalkine is able to reverse changes in microglia caused by a prenatal stress procedure. Our study found that the microglia do not express fractalkine. Prenatal stress decreases the expression of the fractalkine receptor, which in turn is enhanced by the administration of exogenous fractalkine. Moreover, treatment with fractalkine diminishes the prenatal stress-induced overproduction of proinflammatory factors such as IL-1β, IL-18, IL-6, TNF-α, CCL2, or NO in the microglial cells derived from prenatally stressed newborns. In conclusion, the present results revealed that the pathological activation of microglia in prenatally stressed newborns may be attenuated by fractalkine administration. Therefore, understanding of the role of the CX3CL1-CX3CR1 system may help to elucidate the mechanisms underlying the neuron-microglia interaction and its role in pathological conditions in the brain. PMID:27239349

  14. Activation of autophagy by unfolded proteins during endoplasmic reticulum stress.

    PubMed

    Yang, Xiaochen; Srivastava, Renu; Howell, Stephen H; Bassham, Diane C

    2016-01-01

    Endoplasmic reticulum stress is defined as the accumulation of unfolded proteins in the endoplasmic reticulum, and is caused by conditions such as heat or agents that cause endoplasmic reticulum stress, including tunicamycin and dithiothreitol. Autophagy, a major pathway for degradation of macromolecules in the vacuole, is activated by these stress agents in a manner dependent on inositol-requiring enzyme 1b (IRE1b), and delivers endoplasmic reticulum fragments to the vacuole for degradation. In this study, we examined the mechanism for activation of autophagy during endoplasmic reticulum stress in Arabidopsis thaliana. The chemical chaperones sodium 4-phenylbutyrate and tauroursodeoxycholic acid were found to reduce tunicamycin- or dithiothreitol-induced autophagy, but not autophagy caused by unrelated stresses. Similarly, over-expression of BINDING IMMUNOGLOBULIN PROTEIN (BIP), encoding a heat shock protein 70 (HSP70) molecular chaperone, reduced autophagy. Autophagy activated by heat stress was also found to be partially dependent on IRE1b and to be inhibited by sodium 4-phenylbutyrate, suggesting that heat-induced autophagy is due to accumulation of unfolded proteins in the endoplasmic reticulum. Expression in Arabidopsis of the misfolded protein mimics zeolin or a mutated form of carboxypeptidase Y (CPY*) also induced autophagy in an IRE1b-dependent manner. Moreover, zeolin and CPY* partially co-localized with the autophagic body marker GFP-ATG8e, indicating delivery to the vacuole by autophagy. We conclude that accumulation of unfolded proteins in the endoplasmic reticulum is a trigger for autophagy under conditions that cause endoplasmic reticulum stress. PMID:26616142

  15. Stress versus temperature dependent activation energies in creep

    NASA Technical Reports Server (NTRS)

    Freed, A. D.; Raj, S. V.; Walker, K. P.

    1990-01-01

    The activation energy for creep at low stresses and elevated temperatures is lattice diffusion, where the rate controlling mechanism for deformation is dislocation climb. At higher stresses and intermediate temperatures, the rate controlling mechanism changes from that of dislocation climb to one of obstacle-controlled dislocation glide. Along with this change, there occurs a change in the activation energy. It is shown that a temperature-dependent Gibbs free energy does a good job of correlating steady-state creep data, while a stress-dependent Gibbs free energy does a less desirable job of correlating the same data. Applications are made to copper and a LiF-22 mol. percent CaF2 hypereutectic salt.

  16. Stress versus temperature dependence of activation energies for creep

    NASA Technical Reports Server (NTRS)

    Freed, A. D.; Raj, S. V.; Walker, K. P.

    1992-01-01

    The activation energy for creep at low stresses and elevated temperatures is associated with lattice diffusion, where the rate controlling mechanism for deformation is dislocation climb. At higher stresses and intermediate temperatures, the rate controlling mechanism changes from dislocation climb to obstacle-controlled dislocation glide. Along with this change in deformation mechanism occurs a change in the activation energy. When the rate controlling mechanism for deformation is obstacle-controlled dislocation glide, it is shown that a temperature-dependent Gibbs free energy does better than a stress-dependent Gibbs free energy in correlating steady-state creep data for both copper and LiF-22mol percent CaF2 hypereutectic salt.

  17. Functional analysis of oxidative stress-activated mitogen-activated protein kinase cascade in plants

    PubMed Central

    Kovtun, Yelena; Chiu, Wan-Ling; Tena, Guillaume; Sheen, Jen

    2000-01-01

    Despite the recognition of H2O2 as a central signaling molecule in stress and wounding responses, pathogen defense, and regulation of cell cycle and cell death, little is known about how the H2O2 signal is perceived and transduced in plant cells. We report here that H2O2 is a potent activator of mitogen-activated protein kinases (MAPKs) in Arabidopsis leaf cells. Using epitope tagging and a protoplast transient expression assay, we show that H2O2 can activate a specific Arabidopsis mitogen-activated protein kinase kinase kinase, ANP1, which initiates a phosphorylation cascade involving two stress MAPKs, AtMPK3 and AtMPK6. Constitutively active ANP1 mimics the H2O2 effect and initiates the MAPK cascade that induces specific stress-responsive genes, but it blocks the action of auxin, a plant mitogen and growth hormone. The latter observation provides a molecular link between oxidative stress and auxin signal transduction. Finally, we show that transgenic tobacco plants that express a constitutively active tobacco ANP1 orthologue, NPK1, display enhanced tolerance to multiple environmental stress conditions without activating previously described drought, cold, and abscisic acid signaling pathways. Thus, manipulation of key regulators of an oxidative stress signaling pathway, such as ANP1/NPK1, provides a strategy for engineering multiple stress tolerance that may greatly benefit agriculture. PMID:10717008

  18. YoeB toxin is activated during thermal stress

    PubMed Central

    Janssen, Brian D; Garza-Sánchez, Fernando; Hayes, Christopher S

    2015-01-01

    Type II toxin-antitoxin (TA) modules are thought to mediate stress-responses by temporarily suppressing protein synthesis while cells redirect transcription to adapt to environmental change. Here, we show that YoeB, a ribosome-dependent mRNase toxin, is activated in Escherichia coli cells grown at elevated temperatures. YoeB activation is dependent on Lon protease, suggesting that thermal stress promotes increased degradation of the YefM antitoxin. Though YefM is efficiently degraded in response to Lon overproduction, we find that Lon antigen levels do not increase during heat shock, indicating that another mechanism accounts for temperature-induced YefM proteolysis. These observations suggest that YefM/YoeB functions in adaptation to temperature stress. However, this response is distinct from previously described models of TA function. First, YoeB mRNase activity is maintained over several hours of culture at 42°C, indicating that thermal activation is not transient. Moreover, heat-activated YoeB does not induce growth arrest nor does it suppress global protein synthesis. In fact, E. coli cells proliferate more rapidly at elevated temperatures and instantaneously accelerate their growth rate in response to acute heat shock. We propose that heat-activated YoeB may serve a quality control function, facilitating the recycling of stalled translation complexes through ribosome rescue pathways. PMID:26147890

  19. Androgenic influence on serotonergic activation of the HPA stress axis.

    PubMed

    Goel, Nirupa; Plyler, Kimberly S; Daniels, Derek; Bale, Tracy L

    2011-05-01

    The higher incidence of stress-mediated affective disorders in women may be a function of gonadal hormone influence on complex interactions between serotonin and neural circuits that mediate the hypothalamic-pituitary-adrenal (HPA) stress axis. The paraventricular nucleus of the hypothalamus (PVN) receives serotonergic innervation, and selective serotonin reuptake inhibitors such as citalopram activate the HPA axis independent of stress. We have previously demonstrated that the magnitude of this serotonergic activation was greater in females and was attenuated by testosterone administration; however, the potential central sites of action where androgens reduce these serotonergic effects have not been determined. Therefore, we examined a time course of corticosterone production and used central c-Fos protein levels to assay neuronal activation in stress-related brain regions in female, male, and gonadectomized male mice after an acute citalopram injection (15 mg/kg). In the hippocampus, c-Fos-immunoreactivity was greater in males than in females or gonadectomized males. This same pattern emerged in the lateral septum after vehicle and gonadectomy reversed the effect of citalopram. These regions are important for inhibitory influences on the PVN, and accordingly, hippocampal c-Fos levels were negatively correlated with corticosterone production. No sex differences in c-Fos were detected in the PVN, cingulate cortex, or paraventricular thalamus in response to vehicle or citalopram. These data support brain region-specific regulation of the HPA axis where sex differences may be mediated partly through androgen enhancement of signaling in inhibitory regions.

  20. Environmental stress on diving-induced platelet activation.

    PubMed

    Bosco, G; Yang, Z J; Savini, F; Nubile, G; Data, P G; Wang, J P; Camporesi, E M

    2001-01-01

    Platelet activation has been suggested to play an important role in the pathogenesis of prethrombotic states and thus may be responsible for decompression illness during compressed air (scuba) diving. To investigate the effect of physical, mental, and environmental stress on platelet activation during immersion in ice-cold water, we examined 10 male breath-hold divers (BHD), 10 elite BHD (eBHD), and 10 scuba divers during immersion in an ice-covered lake at moderate altitude. Platelet activation was examined by surface expression of activation-dependent glycoproteins CD62p, CD63, and CD42a with flow cytometry 10 min before and 1 min and again 24 h after diving. Plasma epinephrine level was also measured. In addition, the relationship between the activated platelets and the epinephrine level was evaluated. The percentage of platelet activation increased from 2.1 +/- 0.4 to 5.7 +/- 0.3, 1.8 +/- 0.3 to 12.9 +/- 0.8, and 3.7 +/- 0.9 to 31.2 +/- 0.8 in BHD, eBHD, and scuba divers, respectively. The percentage of platelet activation returned to pre-immersion levels in BHD and eBHD divers 24 h after diving, but was still higher in scuba divers. A positive relationship exists between the plasma epinephrine level and the percentage of the platelet activation. This study suggests that physical and mental stress enhance platelet activation during diving in ice-cold water.

  1. Obesity and lipid stress inhibit carnitine acetyltransferase activity[S

    PubMed Central

    Seiler, Sarah E.; Martin, Ola J.; Noland, Robert C.; Slentz, Dorothy H.; DeBalsi, Karen L.; Ilkayeva, Olga R.; An, Jie; Newgard, Christopher B.; Koves, Timothy R.; Muoio, Deborah M.

    2014-01-01

    Carnitine acetyltransferase (CrAT) is a mitochondrial matrix enzyme that catalyzes the interconversion of acetyl-CoA and acetylcarnitine. Emerging evidence suggests that this enzyme functions as a positive regulator of total body glucose tolerance and muscle activity of pyruvate dehydrogenase (PDH), a mitochondrial enzyme complex that promotes glucose oxidation and is feedback inhibited by acetyl-CoA. Here, we used tandem mass spectrometry-based metabolic profiling to identify a negative relationship between CrAT activity and muscle content of lipid intermediates. CrAT specific activity was diminished in muscles from obese and diabetic rodents despite increased protein abundance. This reduction in enzyme activity was accompanied by muscle accumulation of long-chain acylcarnitines (LCACs) and acyl-CoAs and a decline in the acetylcarnitine/acetyl-CoA ratio. In vitro assays demonstrated that palmitoyl-CoA acts as a direct mixed-model inhibitor of CrAT. Similarly, in primary human myocytes grown in culture, nutritional and genetic manipulations that promoted mitochondrial influx of fatty acids resulted in accumulation of LCACs but a pronounced decrease of CrAT-derived short-chain acylcarnitines. These results suggest that lipid-induced antagonism of CrAT might contribute to decreased PDH activity and glucose disposal in the context of obesity and diabetes. PMID:24395925

  2. Numerical solutions for heat flow in adhesive lap joints

    NASA Technical Reports Server (NTRS)

    Howell, P. A.; Winfree, William P.

    1992-01-01

    The present formulation for the modeling of heat transfer in thin, adhesively bonded lap joints precludes difficulties associated with large aspect ratio grids required by standard FEM formulations. This quasi-static formulation also reduces the problem dimensionality (by one), thereby minimizing computational requirements. The solutions obtained are found to be in good agreement with both analytical solutions and solutions from standard FEM programs. The approach is noted to yield a more accurate representation of heat-flux changes between layers due to a disbond.

  3. A Fluorescent Reporter of AMPK activity and Cellular Energy Stress

    PubMed Central

    Tsou, Peiling; Zheng, Bin; Hsu, Chia-Hsien; Sasaki, Atsuo T; Cantley, Lewis C.

    2011-01-01

    SUMMARY AMP-activated protein kinase (AMPK) is activated when the AMP/ATP ratio in cells is elevated due to energy stress. Here we describe a biosensor, AMPKAR, which exhibits enhanced fluorescence resonance energy transfer (FRET) in response to phosphorylation by AMPK, allowing spatio-temporal monitoring of AMPK activity in single cells. We show that this reporter responds to a variety of stimuli that are known to induce energy stress and that the response is dependent on AMPK α1 & α2 and on the upstream kinase, LKB1. Interestingly we found that AMPK activation is confined to the cytosol in response to energy stress but can be observed in both the cytosol and nucleus in response to calcium elevation. Finally, using this probe with U2OS cells in a microfluidics device, we observed a very high cell-to-cell variability in the amplitude and time course of AMPK activation and recovery in response to pulses of glucose deprivation. PMID:21459332

  4. Connecting Local Yield Stresses with Plastic Activity in Amorphous Solids

    NASA Astrophysics Data System (ADS)

    Patinet, Sylvain; Vandembroucq, Damien; Falk, Michael L.

    2016-07-01

    In model amorphous solids produced via differing quench protocols, a strong correlation is established between local yield stress measured by direct local probing of shear stress thresholds and the plastic rearrangements observed during remote loading in shear. This purely local measure shows a higher predictive power for identifying sites of plastic activity when compared with more conventional structural properties. Most importantly, the sites of low local yield stress, thus defined, are shown to be persistent, remaining predictive of deformation events even after fifty or more such plastic rearrangements. This direct and nonperturbative approach gives access to relevant transition pathways that control the stability of amorphous solids. Our results reinforce the relevance of modeling plasticity in amorphous solids based on a gradually evolving population of discrete and local zones preexisting in the structure.

  5. Connecting Local Yield Stresses with Plastic Activity in Amorphous Solids.

    PubMed

    Patinet, Sylvain; Vandembroucq, Damien; Falk, Michael L

    2016-07-22

    In model amorphous solids produced via differing quench protocols, a strong correlation is established between local yield stress measured by direct local probing of shear stress thresholds and the plastic rearrangements observed during remote loading in shear. This purely local measure shows a higher predictive power for identifying sites of plastic activity when compared with more conventional structural properties. Most importantly, the sites of low local yield stress, thus defined, are shown to be persistent, remaining predictive of deformation events even after fifty or more such plastic rearrangements. This direct and nonperturbative approach gives access to relevant transition pathways that control the stability of amorphous solids. Our results reinforce the relevance of modeling plasticity in amorphous solids based on a gradually evolving population of discrete and local zones preexisting in the structure. PMID:27494480

  6. Connecting Local Yield Stresses with Plastic Activity in Amorphous Solids.

    PubMed

    Patinet, Sylvain; Vandembroucq, Damien; Falk, Michael L

    2016-07-22

    In model amorphous solids produced via differing quench protocols, a strong correlation is established between local yield stress measured by direct local probing of shear stress thresholds and the plastic rearrangements observed during remote loading in shear. This purely local measure shows a higher predictive power for identifying sites of plastic activity when compared with more conventional structural properties. Most importantly, the sites of low local yield stress, thus defined, are shown to be persistent, remaining predictive of deformation events even after fifty or more such plastic rearrangements. This direct and nonperturbative approach gives access to relevant transition pathways that control the stability of amorphous solids. Our results reinforce the relevance of modeling plasticity in amorphous solids based on a gradually evolving population of discrete and local zones preexisting in the structure.

  7. Single-cycle and fatigue strengths of adhesively bonded lap joints

    SciTech Connect

    Metzinger, K.E.; Guess, T.R.

    1998-12-31

    This study considers a composite-to-steel tubular lap joint in which failure typically occurs when the adhesive debonds from the steel adherend. The same basic joint was subjected to compressive and tensile axial loads (single-cycle) as well as bending loads (fatigue). The purpose of these tests was to determine whether failure is more dependent on the plastic strain or the peel stress that develops in the adhesive. For the same joint, compressive and tensile loads of the same magnitude will produce similar plastic strains but peel stresses of opposite signs in the adhesive. In the axial tests, the tensile strengths were much greater than the compressive strengths - indicating that the peel stress is key to predicting the single-cycle strengths. To determine the key parameter(s) for predicting high-cycle fatigue strengths, a test technique capable of subjecting a specimen to several million cycles per day was developed. In these bending tests, the initial adhesive debonding always occurred on the compressive side. This result is consistent with the single-cycle tests, although not as conclusive due to the limited number of tests. Nevertheless, a fatigue test method has been established and future tests are planned.

  8. Stress, active coping, and problem behaviors among Chinese adolescents.

    PubMed

    Hsieh, Hsing-Fang; Zimmerman, Marc A; Xue, Yange; Bauermeister, Jose A; Caldwell, Cleopatra H; Wang, Zhenhong; Hou, Yubo

    2014-07-01

    Little is known about the stress and coping mechanisms on problem behaviors among Chinese adolescents, which might be quite different from their counterparts in Western cultures. We examined risk process of stress for internalizing outcomes (i.e., psychological distress, self-acceptance) and externalizing outcomes (i.e., substance use, delinquency, violent behavior) among Chinese adolescents. We also examined John Henryism Active Coping as a protective factor in a test of resilience from the negative effects of stress. A cross-sectional survey using self-reported questionnaires was conducted in 2 urban cities in China: Beijing and Xian. Participants included 1,356 students in Grades 7 to 12 (48% male, 52% female). Structural equation modeling analyses were conducted to test the conceptual model. The modifying (protective) effects of John Henryism were tested in multiple-group analysis. After controlling for demographics, we found that stress was associated with decreased self-acceptance and increased psychological distress among adolescents. Higher degree of psychological distress was then associated with increased delinquent behaviors and substance use. The results also indicated that individuals who scored higher in John Henryism reported more substance use as a result of psychological distress. Overall, our results support previous research with Western samples. Although John Henryism did not serve as a protective factor between stress and its negative outcomes, the findings underscore the relevance of addressing stress and possible coping strategies among Chinese adolescents. Further research that refines the active coping tailored for Chinese adolescents is necessary to more precisely test its protective effects. PMID:24999522

  9. Improvement of transformer core magnetic properties using the step-lap design

    NASA Astrophysics Data System (ADS)

    Valkovic, Z.; Rezic, A.

    1992-07-01

    Magnetic properties of the step-lap joints have been investigated experimentally on two three-phase three-leg transformer cores. Using the step-lap joint design, a reduction of the total core loss of 2 to 4.4% and of the exciting power of 31 to 37% has been obtained.

  10. Mechanistic Features of Nanodiamonds in the Lapping of Magnetic Heads

    PubMed Central

    Jiang, Xionghua; Chen, Zhenxing; Wolfram, Joy; Yang, Zhizhou

    2014-01-01

    Nanodiamonds, which are the main components of slurry in the precision lapping process of magnetic heads, play an important role in surface quality. This paper studies the mechanistic features of nanodiamond embedment into a Sn plate in the lapping process. This is the first study to develop mathematical models for nanodiamond embedment. Such models can predict the optimum parameters for particle embedment. From the modeling calculations, the embedded pressure satisfies p0 = (3/2)·(W/πa2) and the indentation depth satisfies δ=k1P/HV. Calculation results reveal that the largest embedded pressure is 731.48 GPa and the critical indentation depth δ is 7 nm. Atomic force microscopy (AFM), scanning electron microscopy (SEM), and Auger electron spectroscopy (AES) were used to carry out surface quality detection and analysis of the disk head. Both the formation of black spots on the surface and the removal rate have an important correlation with the size of nanodiamonds. The results demonstrate that an improved removal rate (21 nm·min−1) can be obtained with 100 nm diamonds embedded in the plate. PMID:25045730

  11. Large-Scale Advanced Prop-Fan (LAP)

    NASA Technical Reports Server (NTRS)

    Degeorge, C. L.

    1988-01-01

    In recent years, considerable attention has been directed toward improving aircraft fuel efficiency. Analytical studies and research with wind tunnel models have demonstrated that the high inherent efficiency of low speed turboprop propulsion systems may now be extended to the Mach .8 flight regime of today's commercial airliners. This can be accomplished with a propeller, employing a large number of thin highly swept blades. The term Prop-Fan has been coined to describe such a propulsion system. In 1983 the NASA-Lewis Research Center contracted with Hamilton Standard to design, build and test a near full scale Prop-Fan, designated the Large Scale Advanced Prop-Fan (LAP). This report provides a detailed description of the LAP program. The assumptions and analytical procedures used in the design of Prop-Fan system components are discussed in detail. The manufacturing techniques used in the fabrication of the Prop-Fan are presented. Each of the tests run during the course of the program are also discussed and the major conclusions derived from them stated.

  12. Ultrasonic guided wave inspection of Inconel 625 brazed lap joints

    NASA Astrophysics Data System (ADS)

    Comot, Pierre; Bocher, Philippe; Belanger, Pierre

    2016-04-01

    The aerospace industry has been investigating the use of brazing for structural joints, as a mean of reducing cost and weight. There therefore is a need for a rapid, robust, and cost-effective non-destructive testing method for evaluating the structural integrity of the joints. The mechanical strength of brazed joints depends mainly on the amount of brittle phases in their microstructure. Ultrasonic guided waves offer the possibility of detecting brittle phases in joints using spatio-temporal measurements. Moreover, they offer the opportunity to inspect complex shape joints. This study focused on the development of a technique based on ultrasonic guided waves for the inspection of Inconel 625 lap joints brazed with BNi-2 filler metal. A finite element model of a lap joint was used to optimize the inspection parameters and assess the feasibility of detecting the amount of brittle phases in the joint. A finite element parametric study simulating the input signal shape, the center frequency, and the excitation direction was performed. The simulations showed that the ultrasonic guided wave energy transmitted through, and reflected from, the joints was proportional to the amount of brittle phases in the joint.

  13. Stress monitoring versus microseismic ruptures in an active deep mine

    NASA Astrophysics Data System (ADS)

    Tonnellier, Alice; Bouffier, Christian; Bigarré, Pascal; Nyström, Anders; Österberg, Anders; Fjellström, Peter

    2015-04-01

    monitoring data coming from the mine in quasi-real time and facilitates information exchanges and decision making for experts and stakeholders. On the basis of these data acquisition and sharing, preliminary analysis has been started to highlight whether stress variations and seismic sources behaviour might be directly bound with mine working evolution and could improve the knowledge on the equilibrium states inside the mine. Knowing such parameters indeed will be a potential solution to understand better the response of deep mining activities to the exploitation solicitations and to develop, if possible, methods to prevent from major hazards such as rock bursts and other ground failure phenomena.

  14. Mechanical Behavior of Lithium-Ion Batteries and Fatigue Behavior of Ultrasonic Weld-Bonded Lap-Shear Specimens of Dissimilar Magnesium and Steel Sheets

    NASA Astrophysics Data System (ADS)

    Lai, Wei-Jen

    The mechanical behaviors of LiFePO4 battery cell and module specimens under in-plane constrained compression were investigated for simulations of battery cells, modules and packs under crush conditions. The experimental stress-strain curves were correlated to the deformation patterns of battery cell and module specimens. Analytical solutions were developed to estimate the buckling stresses and to provide a theoretical basis for future design of representative volume element cell and module specimens. A physical kinematics model for formation of kinks and shear bands in battery cells was developed to explain the deformation mechanism for layered battery cells under in-plane constrained compression. A small-scale module constrained punch indentation test was also conducted to benchmark the computational results. The computational results indicate that macro homogenized material models can be used to simulate battery modules under crush conditions. Fatigue behavior and failure modes of ultrasonic spot welds in lap-shear specimens of magnesium and steel sheets with and without adhesive were investigated. For ultrasonic spot welded lap-shear specimens, the failure mode changes from the partial nugget pullout mode under low-cycle loading conditions to the kinked crack failure mode under high-cycle loading conditions. For adhesive-bonded and weld-bonded lap-shear specimens, the test results show the near interface cohesive failure mode and the kinked crack failure mode under low-cycle and high-cycle loading conditions, respectively. Next, the analytical effective stress intensity factor solutions for main cracks in lap-shear specimens of three dissimilar sheets under plane strain conditions were developed and the solutions agreed well with the computational results. The analytical effective stress intensity factor solutions for kinked cracks were compared with the computational results at small kink lengths. The results indicate that the computational results approach to

  15. ER stress and ER stress-induced apoptosis are activated in gastric SMCs in diabetic rats

    PubMed Central

    Chen, Xia; Fu, Xiang-Sheng; Li, Chang-Ping; Zhao, Hong-Xian

    2014-01-01

    AIM: To investigate the gastric muscle injury caused by endoplasmic reticulum (ER) stress in rats with diabetic gastroparesis. METHODS: Forty rats were randomly divided into two groups: a control group and a diabetic group. Diabetes was induced by intraperitoneal injection of 60 mg/kg of streptozotocin. Gastric emptying was determined at the 4th and 12th week. The ultrastructural changes in gastric smooth muscle cells (SMCs) were investigated by transmission electron microscopy. TdT-mediated dUTP nick end labeling (TUNEL) assay was performed to assess apoptosis of SMCs. Expression of the ER stress marker, glucose-regulated protein 78 (GRP78), and the ER-specific apoptosis mediator, caspase-12 protein, was determined by immunohistochemistry. RESULTS: Gastric emptying was significantly lower in the diabetic rats than in the control rats at the 12th wk (40.71% ± 2.50%, control rats vs 54.65% ± 5.22%, diabetic rats; P < 0.05). Swollen and distended ER with an irregular shape was observed in gastric SMCs in diabetic rats. Apoptosis of gastric SMCs increased in the diabetic rats in addition to increased expression of GRP78 and caspase-12 proteins. CONCLUSION: ER stress and ER stress-mediated apoptosis are activated in gastric SMCs in diabetic rats with gastroparesis. PMID:25009401

  16. The Teacher's Lap--A Site of Emotional Well-Being for the Younger Children in Day-Care Groups

    ERIC Educational Resources Information Center

    Hännikäinen, Maritta

    2015-01-01

    This study focuses on a particular relationship between teachers and one- to three-year-old children: the child in the teacher's lap. When, in what situations, does this happen? Who are the children in the teacher's lap? Why are they there? How do children express emotional well-being when in the teacher's lap? Relational, sociocultural and…

  17. The activity-stress paradigm: possible mechanisms and applications.

    PubMed

    Lambert, K G

    1993-01-01

    The mechanisms and applications of the activity-stress (A-S) research paradigm are examined in this article. Past research has reflected the value of this paradigm in the investigation of ulcerogenesis. Evidence is offered to support a theory explaining the excessive running observed in the A-S animals, according to which, animals commence running to increase body temperature after failing to adapt to the restricted feeding regime. Further, excessive running levels are hypothesized to be sustained by reinforcement resulting from increased mesolimbic dopaminergic activity. Finally, parallels between the behavior observed in the A-S animals and some forms of maladaptive behavior observed in humans are discussed.

  18. Sympathetic activity during passive heat stress in healthy aged humans

    PubMed Central

    Gagnon, Daniel; Schlader, Zachary J; Crandall, Craig G

    2015-01-01

    Abstract Cardiovascular adjustments during heat stress are generally attenuated in healthy aged humans, which could be due to lower increases in sympathetic activity compared to the young. We compared muscle sympathetic nerve activity (MSNA) between 11 young (Y: 28 ± 4 years) and 10 aged (A: 70 ± 5 years) subjects prior to and during passive heating. Furthermore, MSNA responses were compared when a cold pressor test (CPT) and lower body negative pressure (LBNP) were superimposed upon heating. Baseline MSNA burst frequency (Y: 15 ± 4 vs. A: 31 ± 3 bursts min−1, P ≤ 0.01) and burst incidence (Y: 26 ± 8 vs. A: 50 ± 7 bursts (100 cardiac cycles (CC))−1, P ≤ 0.01) were greater in the aged. Heat stress increased core temperature to a similar extent in both groups (Y: +1.2 ± 0.1 vs. A: +1.2 ± 0.0°C, P = 0.99). Absolute levels of MSNA remained greater in the aged during heat stress (burst frequency: Y: 47 ± 6 vs. A: 63 ± 11 bursts min−1, P ≤ 0.01; burst incidence: Y: 48 ± 8 vs. A: 67 ± 9 bursts (100 CC)−1, P ≤ 0.01); however, the increase in both variables was similar between groups (both P ≥ 0.1). The CPT and LBNP further increased MSNA burst frequency and burst incidence, although the magnitude of increase was similar between groups (both P ≥ 0.07). These results suggest that increases in sympathetic activity during heat stress are not attenuated in healthy aged humans. Key points Cardiovascular adjustments to heat stress are attenuated in healthy aged individuals, which could contribute to their greater prevalence of heat-related illnesses and deaths during heat waves. The attenuated cardiovascular adjustments in the aged could be due to lower increases in sympathetic nerve activity during heat stress. We examined muscle sympathetic nerve activity (MSNA) and plasma catecholamine concentrations in healthy young and aged individuals during whole-body passive heat stress. The main finding

  19. Replication stress activates DNA repair synthesis in mitosis.

    PubMed

    Minocherhomji, Sheroy; Ying, Songmin; Bjerregaard, Victoria A; Bursomanno, Sara; Aleliunaite, Aiste; Wu, Wei; Mankouri, Hocine W; Shen, Huahao; Liu, Ying; Hickson, Ian D

    2015-12-10

    Oncogene-induced DNA replication stress has been implicated as a driver of tumorigenesis. Many chromosomal rearrangements characteristic of human cancers originate from specific regions of the genome called common fragile sites (CFSs). CFSs are difficult-to-replicate loci that manifest as gaps or breaks on metaphase chromosomes (termed CFS 'expression'), particularly when cells have been exposed to replicative stress. The MUS81-EME1 structure-specific endonuclease promotes the appearance of chromosome gaps or breaks at CFSs following replicative stress. Here we show that entry of cells into mitotic prophase triggers the recruitment of MUS81 to CFSs. The nuclease activity of MUS81 then promotes POLD3-dependent DNA synthesis at CFSs, which serves to minimize chromosome mis-segregation and non-disjunction. We propose that the attempted condensation of incompletely duplicated loci in early mitosis serves as the trigger for completion of DNA replication at CFS loci in human cells. Given that this POLD3-dependent mitotic DNA synthesis is enhanced in aneuploid cancer cells that exhibit intrinsically high levels of chromosomal instability (CIN(+)) and replicative stress, we suggest that targeting this pathway could represent a new therapeutic approach.

  20. Replication stress activates DNA repair synthesis in mitosis.

    PubMed

    Minocherhomji, Sheroy; Ying, Songmin; Bjerregaard, Victoria A; Bursomanno, Sara; Aleliunaite, Aiste; Wu, Wei; Mankouri, Hocine W; Shen, Huahao; Liu, Ying; Hickson, Ian D

    2015-12-10

    Oncogene-induced DNA replication stress has been implicated as a driver of tumorigenesis. Many chromosomal rearrangements characteristic of human cancers originate from specific regions of the genome called common fragile sites (CFSs). CFSs are difficult-to-replicate loci that manifest as gaps or breaks on metaphase chromosomes (termed CFS 'expression'), particularly when cells have been exposed to replicative stress. The MUS81-EME1 structure-specific endonuclease promotes the appearance of chromosome gaps or breaks at CFSs following replicative stress. Here we show that entry of cells into mitotic prophase triggers the recruitment of MUS81 to CFSs. The nuclease activity of MUS81 then promotes POLD3-dependent DNA synthesis at CFSs, which serves to minimize chromosome mis-segregation and non-disjunction. We propose that the attempted condensation of incompletely duplicated loci in early mitosis serves as the trigger for completion of DNA replication at CFS loci in human cells. Given that this POLD3-dependent mitotic DNA synthesis is enhanced in aneuploid cancer cells that exhibit intrinsically high levels of chromosomal instability (CIN(+)) and replicative stress, we suggest that targeting this pathway could represent a new therapeutic approach. PMID:26633632

  1. Prospectively Assessed Posttraumatic Stress Disorder and Associated Physical Activity

    PubMed Central

    LeardMann, Cynthia A.; Kelton, Molly L.; Smith, Besa; Littman, Alyson J.; Boyko, Edward J.; Wells, Timothy S.; Smith, Tyler C.

    2011-01-01

    Objectives We examined the association of physical activity with prospectively assessed posttraumatic stress disorder (PTSD) symptoms in a military cohort. Methods Using baseline and follow-up questionnaire data from a large prospective study of U.S. service members, we applied multivariable logistic regression to examine the adjusted odds of new-onset and persistent PTSD symptoms associated with light/moderate physical activity, vigorous physical activity, and strength training at follow-up. Results Of the 38,883 participants, 89.4% reported engaging in at least 30 minutes of physical activity per week. At follow-up, those who reported proportionately less physical activity were more likely to screen positive for PTSD. Vigorous physical activity had the most consistent relationship with PTSD. Those who reported at least 20 minutes of vigorous physical activity twice weekly had significantly decreased odds for new-onset (odds ratio [OR] = 0.58, 95% confidence interval [CI] 0.49, 0.70) and persistent (OR=0.59, 95% CI 0.42, 0.83) PTSD symptoms. Conclusions Engagement in physical activity, especially vigorous activity, is significantly associated with decreased odds of PTSD symptoms among U.S. service members. While further longitudinal research is necessary, a physical activity component may be valuable to PTSD treatment and prevention programs. PMID:21553666

  2. Emotional stability, anxiety, and natural killer activity under examination stress.

    PubMed

    Borella, P; Bargellini, A; Rovesti, S; Pinelli, M; Vivoli, R; Solfrini, V; Vivoli, G

    1999-08-01

    This study was performed to evaluate the relation between a stable personality trait, a mood state and immune response to an examination stress. A self-reported measure of emotional stability (BFQ-ES scale) was obtained in a sample (n = 39) randomly selected from 277 cadets; this personality trait was also investigated by completing a neuroticism scale (Eysenck personality inventory) and a trait-anxiety scale (STAI). Natural killer (NK) cell activity was measured at baseline, long before the examination time and the examination day. The state-anxiety scale evaluated the response to the stressful stimulus. Taking subjects all together, the academic task did not result in significant modification over baseline in NK cell activity. Subjects were then divided into three groups based on emotional stability and state-anxiety scores: high emotional stability/low anxiety, medium, and low emotional stability/high anxiety. Examination stress induced significant increases in NK cell activity in the high emotional stability/low anxiety group, no effect in the medium group, and significant decreases in the low emotional stability/high anxiety group. The repeated-measure ANOVA revealed a significant interaction of group x period (baseline vs. examination) for both lytic units and percent cytolysis. The results did not change after introducing coffee and smoking habits as covariates. Our findings suggest that the state-anxiety acts in concert with a stable personality trait to modulate NK response in healthy subjects exposed to a psychological naturalistic stress. The relation between anxiety and poor immune control has been already described, whereas the ability of emotional stability to associate with an immunoenhancement has not yet reported. The peculiarity of our population, a very homogeneous and healthy group for life style and habits, can have highlighted the role of emotional stability, and may account for the difference with other studies.

  3. Psychosocial versus physiological stress - Meta-analyses on deactivations and activations of the neural correlates of stress reactions.

    PubMed

    Kogler, Lydia; Müller, Veronika I; Chang, Amy; Eickhoff, Simon B; Fox, Peter T; Gur, Ruben C; Derntl, Birgit

    2015-10-01

    Stress is present in everyday life in various forms and situations. Two stressors frequently investigated are physiological and psychosocial stress. Besides similar subjective and hormonal responses, it has been suggested that they also share common neural substrates. The current study used activation-likelihood-estimation meta-analysis to test this assumption by integrating results of previous neuroimaging studies on stress processing. Reported results are cluster-level FWE corrected. The inferior frontal gyrus (IFG) and the anterior insula (AI) were the only regions that demonstrated overlapping activation for both stressors. Analysis of physiological stress showed consistent activation of cognitive and affective components of pain processing such as the insula, striatum, or the middle cingulate cortex. Contrarily, analysis across psychosocial stress revealed consistent activation of the right superior temporal gyrus and deactivation of the striatum. Notably, parts of the striatum appeared to be functionally specified: the dorsal striatum was activated in physiological stress, whereas the ventral striatum was deactivated in psychosocial stress. Additional functional connectivity and decoding analyses further characterized this functional heterogeneity and revealed higher associations of the dorsal striatum with motor regions and of the ventral striatum with reward processing. Based on our meta-analytic approach, activation of the IFG and the AI seems to indicate a global neural stress reaction. While physiological stress activates a motoric fight-or-flight reaction, during psychosocial stress attention is shifted towards emotion regulation and goal-directed behavior, and reward processing is reduced. Our results show the significance of differentiating physiological and psychosocial stress in neural engagement. Furthermore, the assessment of deactivations in addition to activations in stress research is highly recommended. PMID:26123376

  4. Psychosocial versus physiological stress - Meta-analyses on deactivations and activations of the neural correlates of stress reactions.

    PubMed

    Kogler, Lydia; Müller, Veronika I; Chang, Amy; Eickhoff, Simon B; Fox, Peter T; Gur, Ruben C; Derntl, Birgit

    2015-10-01

    Stress is present in everyday life in various forms and situations. Two stressors frequently investigated are physiological and psychosocial stress. Besides similar subjective and hormonal responses, it has been suggested that they also share common neural substrates. The current study used activation-likelihood-estimation meta-analysis to test this assumption by integrating results of previous neuroimaging studies on stress processing. Reported results are cluster-level FWE corrected. The inferior frontal gyrus (IFG) and the anterior insula (AI) were the only regions that demonstrated overlapping activation for both stressors. Analysis of physiological stress showed consistent activation of cognitive and affective components of pain processing such as the insula, striatum, or the middle cingulate cortex. Contrarily, analysis across psychosocial stress revealed consistent activation of the right superior temporal gyrus and deactivation of the striatum. Notably, parts of the striatum appeared to be functionally specified: the dorsal striatum was activated in physiological stress, whereas the ventral striatum was deactivated in psychosocial stress. Additional functional connectivity and decoding analyses further characterized this functional heterogeneity and revealed higher associations of the dorsal striatum with motor regions and of the ventral striatum with reward processing. Based on our meta-analytic approach, activation of the IFG and the AI seems to indicate a global neural stress reaction. While physiological stress activates a motoric fight-or-flight reaction, during psychosocial stress attention is shifted towards emotion regulation and goal-directed behavior, and reward processing is reduced. Our results show the significance of differentiating physiological and psychosocial stress in neural engagement. Furthermore, the assessment of deactivations in addition to activations in stress research is highly recommended.

  5. Psychosocial versus physiological stress – meta-analyses on deactivations and activations of the neural correlates of stress reactions

    PubMed Central

    Kogler, Lydia; Mueller, Veronika I.; Chang, Amy; Eickhoff, Simon B.; Fox, Peter T.; Gur, Ruben C.; Derntl, Birgit

    2015-01-01

    Stress is present in everyday life in various forms and situations. Two stressors frequently investigated are physiological and psychosocial stress. Besides similar subjective and hormonal responses, it has been suggested that they also share common neural substrates. The current study used activation-likelihood-estimation meta-analysis to test this assumption by integrating results of previous neuroimaging studies on stress processing. Reported results are cluster-level FWE corrected. The inferior frontal gyrus (IFG) and the anterior insula (AI) were the only regions that demonstrated overlapping activation for both stressors. Analysis of physiological stress showed consistent activation of cognitive and affective components of pain processing such as the insula, striatum, or the middle cingulate cortex. Contrarily, analysis across psychosocial stress revealed consistent activation of the right superior temporal gyrus and deactivation of the striatum. Notably, parts of the striatum appeared to be functionally specified: the dorsal striatum was activated in physiological stress, whereas the ventral striatum was deactivated in psychosocial stress. Additional functional connectivity and decoding analyses further characterized this functional heterogeneity and revealed higher associations of the dorsal striatum with motor regions and of the ventral striatum with reward processing. Based on our meta-analytic approach, activation of the IFG and the AI seems to indicate a global neural stress reaction. While physiological stress activates a motoric fight-or-flight reaction, during psychosocial stress attention is shifted towards emotion regulation and goal-directed behavior, and reward processing is reduced. Our results show the significance of differentiating physiological and psychosocial stress in neural engagement. Furthermore, the assessment of deactivations in addition to activations in stress research is highly recommended. PMID:26123376

  6. Owning and Operating a Small Business. A Guide for Industrial Cooperative Training Programs. Learning Activity Package No. 14.

    ERIC Educational Resources Information Center

    Braden, Robert P.; Remzi, Kerim

    This learning activity package (LAP) on starting a small business is designed for student self-study. It will help students learn about their aptitudes and abilities as well as about the basics of running a small business. Following a list of learning objectives, the LAP contains a pretest (answer key provided at the end of the LAP). Ten learning…

  7. Lower Electrodermal Activity to Acute Stress in Caregivers of People with Autism Spectrum Disorder: An Adaptive Habituation to Stress

    ERIC Educational Resources Information Center

    Ruiz-Robledillo, Nicolás; Moya-Albiol, Luis

    2015-01-01

    Caring for a relative with autism spectrum disorder (ASD) entails being under chronic stress that could alter body homeostasis. Electrodermal activity (EDA) is an index of the sympathetic activity of the autonomic nervous system related to emotionality and homeostasis. This study compares EDA in response to acute stress in the laboratory between…

  8. [Stress prevention programs--strategies, techniques, effectiveness. Part I. National and international activities to prevent stress at work].

    PubMed

    Waszkowska, Małgorzata; Merecz, Dorota; Drabek, Marcin

    2009-01-01

    Work stress is nowadays one of the major world-wide problems because of its negative impact on health and socio-economic consequences. Therefore, many organizations, established to protect occupational health and safety, include stress-related issues into their preventive activities. This article is the first part of a broader review of approaches to work stress prevention and existing practices in Europe. It presents anti-stress interventions elaborated and implemented at international and national levels, such as: legal and research initiatives, educational actions, supporting the development of knowledge of occupational stress, and promoting the idea of healthy work place.

  9. Lapped Block Image Analysis via the Method of Legendre Moments

    NASA Astrophysics Data System (ADS)

    El Fadili, Hakim; Zenkouar, Khalid; Qjidaa, Hassan

    2003-12-01

    Research investigating the use of Legendre moments for pattern recognition has been performed in recent years. This field of research remains quite open. This paper proposes a new technique based on block-based reconstruction method (BBRM) using Legendre moments compared with the global reconstruction method (GRM). For alleviating the blocking artifact involved in the processing, we propose a new approach using lapped block-based reconstruction method (LBBRM). For the problem of selecting the optimal number of moment used to represent a given image, we propose the maximum entropy principle (MEP) method. The main motivation of the proposed approaches is to allow fast and efficient reconstruction algorithm, with improvement of the reconstructed images quality. A binary handwritten musical character and multi-gray-level Lena image are used to demonstrate the performance of our algorithm.

  10. Shoulder-lap seat belts and thoracic transection.

    PubMed

    Byard, R W

    2002-06-01

    While seat belt usage significantly decreases mortality and morbidity from traffic accidents, specific injuries may also occur. Two cases are described in adults where the wearing of three point restraints (shoulder-lap belts) in a serious high-speed vehicle accident resulted in fatal injuries to both a driver and a passenger. 'Mirror image' fractures of the sternum, rib cage and clavicles, with separation of the two halves of the rib cages and underlying trauma to the hearts and thoracic aortae resulted in death in both victims. Profound life-threatening internal injuries may be caused by seat belts in the absence of significant cutaneous injury. The pattern of internal trauma can also be useful in determining whether a seat belt was worn at the time of the accident, and on which side of the vehicle the deceased was sitting.

  11. Lamina Associated Polypeptide 1 (LAP1) Interactome and Its Functional Features

    PubMed Central

    Serrano, Joana B.; da Cruz e Silva, Odete A. B.; Rebelo, Sandra

    2016-01-01

    Lamina-associated polypeptide 1 (LAP1) is a type II transmembrane protein of the inner nuclear membrane encoded by the human gene TOR1AIP1. LAP1 is involved in maintaining the nuclear envelope structure and appears be involved in the positioning of lamins and chromatin. To date, LAP1’s precise function has not been fully elucidated but analysis of its interacting proteins will permit unraveling putative associations to specific cellular pathways and cellular processes. By assessing public databases it was possible to identify the LAP1 interactome, and this was curated. In total, 41 interactions were identified. Several functionally relevant proteins, such as TRF2, TERF2IP, RIF1, ATM, MAD2L1 and MAD2L1BP were identified and these support the putative functions proposed for LAP1. Furthermore, by making use of the Ingenuity Pathways Analysis tool and submitting the LAP1 interactors, the top two canonical pathways were “Telomerase signalling” and “Telomere Extension by Telomerase” and the top functions “Cell Morphology”, “Cellular Assembly and Organization” and “DNA Replication, Recombination, and Repair”. Once again, putative LAP1 functions are reinforced but novel functions are emerging. PMID:26784240

  12. Fabrication of micro nickel/diamond abrasive pellet array lapping tools using a LIGA-like technology

    NASA Astrophysics Data System (ADS)

    Luo, Sheng-Yih; Yu, Tsung-Han; Hu, Yuh-Chung

    2007-06-01

    A manufacturing process of micro nickel/diamond abrasive pellet array lapping tools using a LIGA-like technology is reported here. The thickness of JSR THB-151N resist coated on an aluminum alloy substrate for micro lithography can reach up to 110 µm. During the lithography, different geometrical photomasks were used to create specific design patterns of the resist mold on the substrate. Micro roots, made by electrolytic machining on the substrate with guidance of the resist mold, can improve the adhesion of micro nickel abrasive pellets electroplated on the substrate. During the composite electroforming, the desired hardness of the nickel matrix inside the micro diamond abrasive pellets can be obtained by the addition of leveling and stress reducing agents. At moderate blade agitation and ultrasonic oscillation, higher concentration and more uniform dispersion of diamond powders deposited in the nickel matrix can be achieved. With these optimal experiment conditions of this fabrication process, the production of micro nickel/diamond abrasive pellet array lapping tools is demonstrated.

  13. Physical activity, life events stress, cortisol, and DHEA: preliminary findings that physical activity may buffer against the negative effects of stress.

    PubMed

    Heaney, Jennifer L J; Carroll, Douglas; Phillips, Anna C

    2014-10-01

    The present study examined the relationship between habitual physical activity, life events stress, the diurnal rhythms of cortisol and DHEA, and the cortisol:dehydroepiandrosterone (DHEA) ratio in older adults. Thirty-six participants aged ≥ 65 reported their habitual physical activity, and indicated if a particular event happened to them in the past year (stress incidence) and how stressful they perceived the event to be (stress severity). Older adults with higher stress severity demonstrated a significantly higher cortisol:DHEA ratio. Individuals with higher stress incidence scores and who did not participate in aerobic exercise had a significantly higher cortisol:DHEA ratio and flatter DHEA diurnal rhythm compared with those who regularly participated in aerobic exercise. In conclusion, life events stress may have a negative impact on the cortisol:DHEA ratio in older adults. Under conditions of high stress exposure, exercise may protect older adults from an increased cortisol:DHEA ratio and flatter DHEA diurnal rhythm.

  14. Vegetation stress and summer fire activity in Portugal

    NASA Astrophysics Data System (ADS)

    Carlos, DaCamara; Sílvia, Nunes

    2013-04-01

    Fire activity in Mediterranean Europe is closely related to the climatological background where the occurrence of rainy and mild winters, followed by warm and dry summers, may induce high levels of vegetation stress over the different regions making them prone to the occurrence of fire events. The aim of the present study is to investigate whether years of very high or very low levels of fire activity over forests in Portugal are linked to contrasting vegetation cycles associated to high and low degrees of vegetation stress during the summer season. The present study relies on time series of yearly amounts of burned areas provided by Instituto de Conservação da Natureza e das Florestas (ICNF), the national authority for forests as well as on monthly values of NDVI and of brightness temperature as obtained from the Mediterranean Extended Daily One Km AVHRR Data Set (MEDOKADS) product provided by the Free University of Berlin. Both datasets cover the 16-year period from 1990 to 2005. The area of forest is first identified by means of a k-means cluster analysis that is performed on climatological yearly means of NDVI and brightness temperature. Monthly means of NDVI and of brightness temperature are then evaluated over the area of forest and composites are made for severe and mild years of fire activity defined as those with yearly burned areas respectively above the third quartile and below the first quartile. The composite of severe years presents a brightness temperature cycle with values above average during spring and summer together with values of NDVI below average during summer, the behavior of both parameters providing an indication of vegetation stress. In contrast, the composite of mild years of fire activity presents an NDVI cycle with values well below average during spring, an indication of lack of biomass, and a brightness temperature cycle with values below average during spring and summer, an indication that vegetation is not under stress. Results

  15. Reviewing the active stress field in Central Asia by using a modified stress tensor approach

    NASA Astrophysics Data System (ADS)

    Karagianni, I.; Papazachos, C. B.; Scordilis, E. M.; Karakaisis, G. F.

    2015-04-01

    Central Asia and its surroundings constitute a geodynamically complicated region, where almost all types of tectonic patterns can be observed. A triple junction, collision, and subduction zones, as well as extended fault systems of all types prevail in different parts of this region and compose one of the most interesting and complex geotectonic environments on Earth. This complicated setting is also associated with intense deformation, resulting in a large number of high seismicity zones, where numerous strong earthquakes occur, also extending, in some cases, to intermediate depths. Several previous studies have focused on specific seismotectonic zones in order to assess the active tectonic setting and the associated stress regime. We attempt to provide a unified but detailed picture of the stress field variability for the entire central Asia region, using the well-known inversion method proposed by Gephart and Forsyth (1984), modified in the present work on the basis of Fisher statistics. For this application, we employ a large number of focal mechanisms, spatially separated in 138 data groups. Τhe proposed modified algorithm (FD-BSM) examines the Fisher distribution of all possible stress principal axes solutions and select the one that: (a) shows the smallest angle variation from the Fisher mean in all three principal distributions and (b) minimizes the difference between the theoretical and observed slip vectors of the employed fault plane solution data. Synthetic tests and comparison of the corresponding results with real data show that, in cases where the stress regime is not clearly uniform or the number of available data is rather small, the models selected by the modified approach (FD-BSM) are more robust and show better spatial coherence compared to the initial Gephart and Forsyth (1984) method or alternative techniques such as the method of Michael (1984, 1987) as adapted by Vavrycuk (2014).

  16. Lumbar Chance fracture associated with use of the lap belt restraint in an adolescent.

    PubMed

    Walsh, A; Sheehan, E; Walsh, M G

    2003-05-01

    The use of the 2-point seat belt or lap belt in motor vehicles, particularly to restrain young rear seat passengers, remains an issue of some concern. The occurrence of lumbar spinal flexion-distraction injuries in lap belt restrained children and adolescents during road traffic accidents is a well known phenomenon, but is still occurring. High velocity paediatric Chance fractures are frequently associated with significant intra-abdominal trauma. We present the case of a Chance fracture sustained by a 15 year old girl, involved in a motor vehicle collision, while wearing a lap belt. We emphasise the need to develop safer seat belt designs for juvenile car passengers.

  17. Seat belt induced transection of the trachea in a child on the lap of an adult.

    PubMed

    Uemura, K; Yoshida, K

    2001-05-01

    As a victim of his parents' suicide, a three-year-old boy was found dead on the lap of the passenger in the left front seat of a car that dove from the wharf and crashed into the sea. He died from the transection of trachea due to shoulder belt in the absence of the signs of drowning. The seat belt paradoxically injured the child on the passenger's lap in the traffic accident. The popular custom of Japanese parents of holding their children on their laps in cars is dangerous, while another custom of killing their children upon suicide of parents or couples should be socially and legally controlled.

  18. Machine imparting complex rotary motion for lapping a spherical inner diameter

    DOEpatents

    Carroll, T.A.; Yetter, H.H.

    1985-01-30

    An apparatus for imparting complex rotary motion is used to lap an inner spherical diameter surface of a workpiece. A lapping tool consists of a dome and rod mounted along the dome's vertical axis. The workpiece containing the lapping tool is held in a gimbal which uses power derived from a secondary takeoff means to impart rotary motion about a horizontal axis. The gimbal is rotated about a vertical axis by a take means while mounted at a radially outward position on a rotating arm.

  19. Machine imparting complex rotary motion for lapping a spherical inner diameter

    DOEpatents

    Carroll, Thomas A.; Yetter, Harold H.

    1986-01-01

    An apparatus for imparting complex rotary motion is used to lap an inner spherical diameter surface of a workpiece. A lapping tool consists of a dome and rod mounted along the dome's vertical axis. The workpiece containing the lapping tool is held in a gimbal which uses power derived from a secondary takeoff means to impart rotary motion about a horizontal axis. The gimbal is rotated about a vertical axis by a take means while mounted at a radially outward position on a rotating arm.

  20. The effect of diamond powder characteristics on lapping of sintered silicon carbide

    NASA Astrophysics Data System (ADS)

    Rosczyk, Benjamin; Burkam, Eric; Titov, Artem; Onyenemezu, Clement; Benea, Ion C.

    2015-10-01

    In Automotive applications, sintered Silicon Carbide has been used in applications such as seal pump faces. The surface of sintered SiC, when lapped or polished for sealing to another surface, must be free of blemishes and mechanical defects. Lapping and polishing processes therefore must be well defined and controlled assuring minimal variation and production scrap. In this study, we related the characteristics of different diamond powders (particle size distribution, particle shape and surface) to their performance in lapping of sintered silicon carbide material, expressed as removal rate and surface finish.

  1. Endoplasmic reticulum stress activation mediates Ginseng Rg3-induced anti-gallbladder cancer cell activity.

    PubMed

    Wu, Keren; Li, Ning; Sun, Huaqin; Xu, Tao; Jin, Fa; Nie, Jifeng

    2015-10-23

    In the current study, we examined the potential effect of Ginsenoside Rg3 against gallbladder cancer cells, the underlying signaling mechanisms were also studied. We demonstrated that Rg3 exerted potent cytotoxic and pro-apoptotic activity against established and primary human gallbladder cancer cells. Yet it was safe to non-cancerous gallbladder epithelial cells. At the molecular level, we showed that Rg3 induced endoplasmic reticulum (ER) stress activation, the latter was evidenced by C/EBP homologous protein (CHOP) upregulation, inositol-requiring enzyme 1 (IRE1)/PKR-like endoplasmic reticulum kinase (PERK) phosphorylations, and caspase-12 activation in gallbladder cancer cells. Reversely, the ER stress inhibitor salubrinal, the caspase-12 inhibitor z-ATAD-fmk as well as CHOP shRNA knockdown significantly attenuated Rg3-induced cytotoxicity against gallbladder cancer cells. In vivo, we showed that Rg3 oral administration significantly inhibited GBC-SD gallbladder cancer xenograft growth in nude mice, its activity was, however, compromised with co-administration of the ER stress inhibitor salubrinal. Thus, we suggest that ER stress activation mediates Ginseng Rg3-induced anti-gallbladder cancer cell activity in vitro and in vivo. PMID:26361144

  2. Daily activity level buffers stress-glycemia associations in older sedentary NIDDM patients.

    PubMed

    Aikens, K S; Aikens, J E; Wallander, J L; Hunt, S

    1997-08-01

    Examined glycemic associations with medical variables, activity, daily stress, and mood state in 72 older patients with non-insulin-dependent diabetes mellitus (NIDDM). On three occasions over a 2-week observation period, subjects provided measures of everyday life stress, negative mood state, and daily activities. At the end of this period, fructosamine was assayed to measure glycemic control throughout the assessment period. After controlling for medical variables (age, illness duration, body mass index, caloric intake, and activity) and the main effects of psychological factors (stress; anxious, angry, and depressed mood states), stress interacted with activity such that glycemic elevation was positively associated with stress for subjects below the activity median but not for those above the median. This was unattributable to any overall activity-related differences in fructosamine, stress, or mood. None of the mood states interacted with activity. The findings suggest that extremely low levels of activity may strengthen life stress-glycemia associations in NIDDM. PMID:9298436

  3. Vaccination alone or in combination with pyridostigmine promotes and prolongs activation of stress-activated kinases induced by stress in the mouse brain.

    PubMed

    Wang, Dechun; Perides, George; Liu, Ya Fang

    2005-05-01

    Gulf war illnesses (GWI) are currently affecting thousands of veterans. To date, the molecular mechanisms underlying the pathogenesis of these illnesses remain unknown. During Gulf war I, military personnel were exposed to multiple stressors, one or more vaccines, pyridostigmine (PY), and other chemicals. In our previous studies, we found that stress induces activation of mitogen activated protein-kinase kinase 4 (MKK4) and c-Jun-N-terminal kinase (JNK) in the mouse brain (Liu et al. 2004). Our working hypothesis is that stress, vaccination, and PY may synergistically induce activation of MKK4 and JNK in the brain, leading to over-activation of these kinases and neurological injuries. To test our hypothesis, we examined the effect of keyhole limpet hemocyanin (KLH) immunization alone or in combination with PY on activation of MKK4 and JNK induced by stress. We found that KLH immunization alone had a small effect on MKK4 or JNK activity but it significantly enhanced and prolonged activation of these kinases induced by stress, from a few hours to several days. Additionally, KLH immunization caused activation of p38MAPK. PY treatment further enhanced and prolonged activation of these kinases induced by stress in combination with KLH immunization and triggered activation of caspase-3. Our current studies suggest that stress, vaccination, and PY may synergistically act on multiple stress-activated kinases in the brain to cause neurological impairments in GWI.

  4. Decreased Prolidase Activity in Patients with Posttraumatic Stress Disorder

    PubMed Central

    Bulut, Mahmut; Atli, Abdullah; Kaplan, İbrahim; Kaya, Mehmet Cemal; Bez, Yasin; Özdemir, Pınar Güzel; Sır, Aytekin

    2016-01-01

    Objective Many neurochemical systems have been implicated in the development of Posttraumatic Stress Disorder (PTSD). The prolidase enzyme is a cytosolic exopeptidase that detaches proline or hydroxyproline from the carboxyl terminal position of dipeptides. Prolidase has important biological effects, and to date, its role in the etiology of PTSD has not been studied. In the present study, we aimed to evaluate prolidase activity in patients with PTSD. Methods The study group consisted of patients who were diagnosed with PTSD after the earthquake that occurred in the province of Van in Turkey in 2011 (n=25); the first control group consisted of patients who experienced the earthquake but did not show PTSD symptoms (n=26) and the second control group consisted of patients who have never been exposed to a traumatic event (n=25). Prolidase activities in the patients and the control groups were determined by the ELISA method using commercial kits. Results Prolidase activity in the patient group was significantly lower when compared to the control groups. Prolidase activity was also significantly lower in the traumatized healthy subjects compared to the other healthy group (p<0.01). Conclusion The findings of the present study suggest that the decrease in prolidase activity may have neuroprotective effects in patients with PTSD. PMID:27482243

  5. Finite element formulation and analysis for an arterial wall with residual and active stresses.

    PubMed

    Kida, Naoki; Adachi, Taiji

    2015-08-01

    In this study, for predicting arterial function and pathogenesis from a mechanical viewpoint, we develop a continuum mechanical model of an arterial wall that embodies residual and active stresses following a traditional anisotropic passive constitutive law. The residual and active stresses are incorporated into finite element methods based on a two-field variational principle described in the Lagrangian form. The linearisation of nonlinear weak-form equations derived from this variational principle is then described for developing an original finite element algorithm. Numerical simulations reveal the following: (i) residual stresses lead to a reduction in stress gradient regardless of the magnitude of external load; (ii) active stresses help homogenise stress distribution under physiological external load, but this homogeneity collapses under pathological external load; (iii) when residual and active stresses act together, the effect of the residual stresses is relatively obscured by that of the active stresses. We conclude that residual stresses have minor but persistent mechanical effects on the arterial wall under both physiological and pathological external loads; active stresses play an important role in the physiological functions and pathogenesis of arteries, and the mechanical effect of residual stresses is dependent on the presence/absence of active stresses.

  6. Large-scale Advanced Prop-fan (LAP) hub/blade retention design report

    NASA Technical Reports Server (NTRS)

    Soule, Matthew

    1986-01-01

    The Large-scale Advanced Prop-fan (LAP) hub assembly forms a semi-rigid link between the blades, which provide the thrust, and the engine shaft, which provides the torque. The hub and tailshaft is a one piece partially forged part which is carburized, heat treated and machined. A single row ball bearing restrains each of the eight blades in the hub, while the tailshaft secures the propeller to the engine shaft with two cone seats that are preloaded against each other by the Prop-fan retaining nut. The hub also forms the support for the pitch change actuator system, the control and the spinner. The retention transmits the loads from the blades to the hub while allowing the changes in blade pitch. The single row ball bearing retention provides ease of maintenance by allowing individual blade replacement without dissassembly of the hub. It has a through hardened inner race which seats against the aluminum blade shank and an outer race which is integral with the barrel. The outer race area is carburized to achieve the hardness necessary to support the ball loads. The balls are kept from contact with each other by a separator. The rotational speed of the propeller keeps the retention submerged in the oil which is contained in the hub by a seal. Stress and strain analysis, material hardness requirements, weight predictions, and stiffness characteristics are discussed.

  7. A characterization of the LAP Aquarius Phantom for external LAP laser alignment and magnetic resonance geometric distortion verification for stereotactic radiation surgery patient simulation

    NASA Astrophysics Data System (ADS)

    Vergara, Daniel

    The Thesis explores additional applications of LAP's Aquarius external laser alignment verification Phantom by examining geometric accuracy of magnetic resonance images commonly used for planning intracranial stereotactic radiation surgery (ICSRS) cases. The scans were performed with MRI protocols used for ICSRS, and head and neck diagnosis, and their images fused to computerized tomographic (CT) images. The geometric distortions (GDs) were measured against the CT in all axial, sagittal, and coronal directions at different levels. Using the Aquarius Phantom, one is able to detect GD in ICSRS planning MRI acquisitions, and align the external LAP patient alignment lasers, by following the LAP QA protocol. GDs up to about 2 mm are observed at the distal regions of the longitudinal axis in the SRS treatment planning MR images. Based on the results, one may recommend the use of the Aquarius Phantom to determine if margins should be included for SRS treatment planning.

  8. Alteration of Sulphides in the Rumuruti Chondrite La Paz Icefield (LAP) 031275

    NASA Astrophysics Data System (ADS)

    Steer, E. D.; Treiman, A. H.

    2014-09-01

    Pyrrhotite in LAP 03175 (R5) has altered to a fine-grained mineral mixture. New data (optical, chemical, and Raman) suggest the mixture includes violarite and tochilinite, but not (as suggested earlier) graphite, hematite, and/or jarosite.

  9. On the water lapping of felines and the water running of lizards: A unifying physical perspective.

    PubMed

    Aristoff, Jeffrey M; Stocker, Roman; Reis, Pedro M; Jung, Sunghwan

    2011-03-01

    We consider two biological phenomena taking place at the air-water interface: the water lapping of felines and the water running of lizards. Although seemingly disparate motions, we show that they are intimately linked by their underlying hydrodynamics and belong to a broader class of processes called Froude mechanisms. We describe how both felines and lizards exploit inertia to defeat gravity, and discuss water lapping and water running in the broader context of water exit and water entry, respectively.

  10. Early life stress affects limited regional brain activity in depression.

    PubMed

    Du, Lian; Wang, Jingjie; Meng, Ben; Yong, Na; Yang, Xiangying; Huang, Qingling; Zhang, Yan; Yang, Lingling; Qu, Yuan; Chen, Zhu; Li, Yongmei; Lv, Fajin; Hu, Hua

    2016-05-03

    Early life stress (ELS) can alter brain function and increases the risk of major depressive disorder (MDD) in later life. This study investigated whether ELS contributes to differences in regional brain activity between MDD patients and healthy controls (HC), as measured by amplitude of low-frequency fluctuation (ALFF)/fractional (f)ALFF. Eighteen first-episode, treatment-naïve MDD patients and HC were assessed with the Childhood Trauma Questionnaire and resting-state functional magnetic resonance imaging. We compared ALFF/fALFF between MDD patients and HC, with or without controlling for ELS, and determined whether ELS level was correlated with regional brain activity in each group. After regressing out ELS, we found that ALFF increased in bilateral amygdala and left orbital/cerebellum, while fALFF decreased in left inferior temporal and right middle frontal gyri in MDD patients relative to controls. ELS positively correlated with regional activity in the left cerebellum in MDD and in the right post-central/inferior temporal/superior frontal cingulate, inferior frontal gyrus and bilateral cerebellum in HC. Our findings indicate that there is only very limited region showing correlation between ELS and brain activity in MDD, while diverse areas in HC, suggesting ELS has few impacts on MDD patients.

  11. Early life stress affects limited regional brain activity in depression

    PubMed Central

    Du, Lian; Wang, Jingjie; Meng, Ben; Yong, Na; Yang, Xiangying; Huang, Qingling; Zhang, Yan; Yang, Lingling; Qu, Yuan; Chen, Zhu; Li, Yongmei; Lv, Fajin; Hu, Hua

    2016-01-01

    Early life stress (ELS) can alter brain function and increases the risk of major depressive disorder (MDD) in later life. This study investigated whether ELS contributes to differences in regional brain activity between MDD patients and healthy controls (HC), as measured by amplitude of low-frequency fluctuation (ALFF)/fractional (f)ALFF. Eighteen first-episode, treatment-naïve MDD patients and HC were assessed with the Childhood Trauma Questionnaire and resting-state functional magnetic resonance imaging. We compared ALFF/fALFF between MDD patients and HC, with or without controlling for ELS, and determined whether ELS level was correlated with regional brain activity in each group. After regressing out ELS, we found that ALFF increased in bilateral amygdala and left orbital/cerebellum, while fALFF decreased in left inferior temporal and right middle frontal gyri in MDD patients relative to controls. ELS positively correlated with regional activity in the left cerebellum in MDD and in the right post-central/inferior temporal/superior frontal cingulate, inferior frontal gyrus and bilateral cerebellum in HC. Our findings indicate that there is only very limited region showing correlation between ELS and brain activity in MDD, while diverse areas in HC, suggesting ELS has few impacts on MDD patients. PMID:27138376

  12. How does stress exert its effects--smoking, diet and obesity, physical activity?

    PubMed Central

    Kornitzer, M.; Kittel, F.

    1986-01-01

    Using a job stress questionnaire a negative correlation was found between job stress and physical fitness and a positive one with Type A behaviour. No correlation was found between job stress and obesity, nutritional patterns or physical activity. Subjects with angina had higher scores on the job stress questionnaire than normal controls. The job stress score was not predictive of future coronary heart disease. PMID:3748939

  13. Composition of matrix in the CR chondrite LAP 02342

    NASA Astrophysics Data System (ADS)

    Wasson, John T.; Rubin, Alan E.

    2009-03-01

    We report evidence of interchondrule matrix heterogeneity on a scale of ˜50 μm in the well-preserved CR2 chondrite LAP 02342. Despite minor effects resulting from asteroidal aqueous alteration, the matrix in this CR chondrite seems to preserve much of the compositional record of nebular fines. We carried out electron-microprobe studies using a 3-μm-diameter beam; we analyzed 10 elements in 36- or 49-point grids on 11 ca. 50 × 50-μm rectangular areas of matrix. Each grid area has a distinct composition, inconsistent with a simple model of matrix material having a uniform composition throughout the nebular formation region of the CR chondrites. On S-Fe, Mg-Si, K-Na and K-Al scatter diagrams, the grid areas (i.e., different matrix patches) are largely separated from each other; plots of means with 95% confidence limits demonstrate that the compositions are resolvable. Five matrix areas were analyzed again in duplicate runs; excellent agreement was observed between duplicate studies. LAP 02342 experienced two forms of mild aqueous alteration - as patchy enrichments in Ca (inferred to reflect CaCO 3) and as regions in which sulfide laths are embedded within phyllosilicates. Despite this evidence of aqueous transport, the effect on the composition of matrix is not resolvable. For example, matrix points that were adjacent to points with high CaCO 3 contents show elemental concentrations similar to those in regions having only one or two points with a Ca enrichment. It appears that secondary minerals are found in areas where there are suitable precursor phases and voids into which new phases could grow unimpeded. Calcium appears to be unique in forming a phase that greatly lowers the Ca ++ content of the aqueous medium, thus enhancing the rate of diffusion. Because chondrules vary widely in bulk composition, the formation of chondrules in small sets (100 or less) could generate "smoke" and mesostasis spray with compositions unique to each set. However, if these

  14. Transcriptional regulation of miR-146b by C/EBPβ LAP2 in esophageal cancer cells

    SciTech Connect

    Li, Junxia; Shan, Fabo; Xiong, Gang; Wang, Ju-Ming; Wang, Wen-Lin; Xu, Xueqing; Bai, Yun

    2014-03-28

    Highlights: • MiR-146b promotes esophageal cancer cell proliferation. • MiR-146b inhibits esophageal cancer cell apoptosis. • C/EBPβ directly binds to miR-146b promoter conserved region. • MiR-146b is up-regulated by C/EBPβ LAP2 transcriptional activation. - Abstract: Recent clinical study indicated that up-regulation of miR-146b was associated with poor overall survival of patients in esophageal squamous cell carcinoma. However, the underlying mechanism of miR-146b dysregulation remains to be explored. Here we report that miR-146b promotes cell proliferation and inhibits cell apoptosis in esophageal cancer cell lines. Mechanismly, two C/EBPβ binding motifs are located in the miR-146b promoter conserved region. Among the three isoforms of C/EBPβ, C/EBPβ LAP2 positively regulated miR-146b expression and increases miR-146b levels in a dose-dependent manner through transcription activation of miR-146b gene. Together, these results suggest a miR-146b regulatory mechanism involving C/EBPβ, which may contribute to the up-regulation of miR-146b in esophageal squamous cell carcinoma.

  15. Catalase activity as a biomarker for mild-stress-induced robustness in Bacillus weihenstephanensis.

    PubMed

    den Besten, Heidy M W; Effraimidou, Styliani; Abee, Tjakko

    2013-01-01

    Microorganisms are able to survive and grow in changing environments by activating stress adaptation mechanisms which may enhance bacterial robustness. Stress-induced enhanced robustness complicates the predictability of microbial inactivation. Using psychrotolerant Bacillus weihenstephanensis strain KBAB4 as a model, we investigated the impact of the culturing temperature on mild-oxidative-stress-induced (cross-)protection toward multiple stresses, including severe oxidative, heat, and acid stresses. Culturing at a refrigeration temperature (7°C) compared to the optimal growth temperature (30°C) affected both the robustness level of B. weihenstephanensis and the oxidative stress adaptive response. Scavengers of reactive oxygen species have a crucial role in adaptation to oxidative stresses, and this points to a possible predictive role in mild-oxidative-stress-induced robustness. Therefore, the catalase activity was determined upon mild oxidative stress treatment and was demonstrated to be significantly correlated with the robustness level of mild-stress-treated cells toward severe oxidative and heat stresses but not toward severe acid stress for cells grown at both refrigeration and optimal temperatures. The quantified correlations supported the predictive quality of catalase activity as a biomarker and also underlined that the predictive quality is stress specific. Biomarkers that are able to predict stress-induced enhanced robustness can be used to better understand stress adaptation mechanisms and might allow the design of effective combinations of hurdles to control microbial behavior.

  16. Effects of Active Mastication on Chronic Stress-Induced Bone Loss in Mice

    PubMed Central

    Azuma, Kagaku; Furuzawa, Manabu; Fujiwara, Shu; Yamada, Kumiko; Kubo, Kin-ya

    2015-01-01

    Chronic psychologic stress increases corticosterone levels, which decreases bone density. Active mastication or chewing attenuates stress-induced increases in corticosterone. We evaluated whether active mastication attenuates chronic stress-induced bone loss in mice. Male C57BL/6 (B6) mice were randomly divided into control, stress, and stress/chewing groups. Stress was induced by placing mice in a ventilated restraint tube (60 min, 2x/day, 4 weeks). The stress/chewing group was given a wooden stick to chew during the experimental period. Quantitative micro-computed tomography, histologic analysis, and biochemical markers were used to evaluate the bone response. The stress/chewing group exhibited significantly attenuated stress-induced increases in serum corticosterone levels, suppressed bone formation, enhanced bone resorption, and decreased trabecular bone mass in the vertebrae and distal femurs, compared with mice in the stress group. Active mastication during exposure to chronic stress alleviated chronic stress-induced bone density loss in B6 mice. Active mastication during chronic psychologic stress may thus be an effective strategy to prevent and/or treat chronic stress-related osteopenia. PMID:26664256

  17. Sex differences in how stress affects brain activity during face viewing.

    PubMed

    Mather, Mara; Lighthall, Nichole R; Nga, Lin; Gorlick, Marissa A

    2010-10-01

    Under stress, men tend to withdraw socially whereas women seek social support. This functional magnetic resonance imaging study indicates that stress also affects brain activity while viewing emotional faces differently for men and women. Fusiform face area response to faces was diminished by acute stress in men but increased by stress in women. Furthermore, among stressed men viewing angry faces, brain regions involved in interpreting and understanding others' emotions (the insula, temporal pole, and inferior frontal gyrus) showed reduced coordination with the fusiform face area and the amygdala, whereas the functional connectivity among these regions increased with stress for women. These findings suggest that stress influences emotional perception differently for men and women.

  18. Preliminary results on the fracture analysis of multi-site cracking of lap joints in aircraft skins

    NASA Astrophysics Data System (ADS)

    Beuth, J. L., Jr.; Hutchinson, John W.

    1992-07-01

    Results of a fracture mechanics analysis relevant to fatigue crack growth at rivets in lap joints of aircraft skins are presented. Multi-site damage (MSD) is receiving increased attention within the context of problems of aging aircraft. Fracture analyses previously carried out include small-scale modeling of rivet/skin interactions, larger-scale two-dimensional models of lap joints similar to that developed here, and full scale three-dimensional models of large portions of the aircraft fuselage. Fatigue testing efforts have included flat coupon specimens, two-dimensional lap joint tests, and full scale tests on specimens designed to closely duplicate aircraft sections. Most of this work is documented in the proceedings of previous symposia on the aging aircraft problem. The effect MSD has on the ability of skin stiffeners to arrest the growth of long skin cracks is a particularly important topic that remains to be addressed. One of the most striking features of MSD observed in joints of some test sections and in the joints of some of the older aircraft fuselages is the relative uniformity of the fatigue cracks from rivet to rivet along an extended row of rivets. This regularity suggests that nucleation of the cracks must not be overly difficult. Moreover, it indicates that there is some mechanism which keeps longer cracks from running away from shorter ones, or, equivalently, a mechanism for shorter cracks to catch-up with longer cracks. This basic mechanism has not been identified, and one of the objectives of the work is to see to what extent the mechanism is revealed by a fracture analysis of the MSD cracks. Another related aim is to present accurate stress intensity factor variations with crack length which can be used to estimate fatigue crack growth lifetimes once cracks have been initiated. Results are presented which illustrate the influence of load shedding from rivets with long cracks to neighboring rivets with shorter cracks. Results are also included

  19. Preliminary results on the fracture analysis of multi-site cracking of lap joints in aircraft skins

    NASA Technical Reports Server (NTRS)

    Beuth, J. L., Jr.; Hutchinson, John W.

    1992-01-01

    Results of a fracture mechanics analysis relevant to fatigue crack growth at rivets in lap joints of aircraft skins are presented. Multi-site damage (MSD) is receiving increased attention within the context of problems of aging aircraft. Fracture analyses previously carried out include small-scale modeling of rivet/skin interactions, larger-scale two-dimensional models of lap joints similar to that developed here, and full scale three-dimensional models of large portions of the aircraft fuselage. Fatigue testing efforts have included flat coupon specimens, two-dimensional lap joint tests, and full scale tests on specimens designed to closely duplicate aircraft sections. Most of this work is documented in the proceedings of previous symposia on the aging aircraft problem. The effect MSD has on the ability of skin stiffeners to arrest the growth of long skin cracks is a particularly important topic that remains to be addressed. One of the most striking features of MSD observed in joints of some test sections and in the joints of some of the older aircraft fuselages is the relative uniformity of the fatigue cracks from rivet to rivet along an extended row of rivets. This regularity suggests that nucleation of the cracks must not be overly difficult. Moreover, it indicates that there is some mechanism which keeps longer cracks from running away from shorter ones, or, equivalently, a mechanism for shorter cracks to catch-up with longer cracks. This basic mechanism has not been identified, and one of the objectives of the work is to see to what extent the mechanism is revealed by a fracture analysis of the MSD cracks. Another related aim is to present accurate stress intensity factor variations with crack length which can be used to estimate fatigue crack growth lifetimes once cracks have been initiated. Results are presented which illustrate the influence of load shedding from rivets with long cracks to neighboring rivets with shorter cracks. Results are also included

  20. Heat stress activates the yeast high-osmolarity glycerol mitogen-activated protein kinase pathway, and protein tyrosine phosphatases are essential under heat stress.

    PubMed

    Winkler, Astrid; Arkind, Christopher; Mattison, Christopher P; Burkholder, Anne; Knoche, Kathryn; Ota, Irene

    2002-04-01

    The yeast high-osmolarity glycerol (HOG) mitogen-activated protein kinase (MAPK) pathway has been characterized as being activated solely by osmotic stress. In this work, we show that the Hog1 MAPK is also activated by heat stress and that Sho1, previously identified as a membrane-bound osmosensor, is required for heat stress activation of Hog1. The two-component signaling protein, Sln1, the second osmosensor in the HOG pathway, was not involved in heat stress activation of Hog1, suggesting that the Sho1 and Sln1 sensors discriminate between stresses. The possible function of Hog1 activation during heat stress was examined, and it was found that the hog1 delta strain does not recover as rapidly from heat stress as well as the wild type. It was also found that protein tyrosine phosphatases (PTPs) Ptp2 and Ptp3, which inactivate Hog1, have two functions during heat stress. First, they are essential for survival at elevated temperatures, preventing lethality due to Hog1 hyperactivation. Second, they block inappropriate cross talk between the HOG and the cell wall integrity MAPK pathways, suggesting that PTPs are important for maintaining specificity in MAPK signaling pathways. PMID:12455951

  1. Heat Stress Activates the Yeast High-Osmolarity Glycerol Mitogen-Activated Protein Kinase Pathway, and Protein Tyrosine Phosphatases Are Essential under Heat Stress

    PubMed Central

    Winkler, Astrid; Arkind, Christopher; Mattison, Christopher P.; Burkholder, Anne; Knoche, Kathryn; Ota, Irene

    2002-01-01

    The yeast high-osmolarity glycerol (HOG) mitogen-activated protein kinase (MAPK) pathway has been characterized as being activated solely by osmotic stress. In this work, we show that the Hog1 MAPK is also activated by heat stress and that Sho1, previously identified as a membrane-bound osmosensor, is required for heat stress activation of Hog1. The two-component signaling protein, Sln1, the second osmosensor in the HOG pathway, was not involved in heat stress activation of Hog1, suggesting that the Sho1 and Sln1 sensors discriminate between stresses. The possible function of Hog1 activation during heat stress was examined, and it was found that the hog1Δ strain does not recover as rapidly from heat stress as well as the wild type. It was also found that protein tyrosine phosphatases (PTPs) Ptp2 and Ptp3, which inactivate Hog1, have two functions during heat stress. First, they are essential for survival at elevated temperatures, preventing lethality due to Hog1 hyperactivation. Second, they block inappropriate cross talk between the HOG and the cell wall integrity MAPK pathways, suggesting that PTPs are important for maintaining specificity in MAPK signaling pathways. PMID:12455951

  2. Oxidative Stress and Maxi Calcium-Activated Potassium (BK) Channels

    PubMed Central

    Hermann, Anton; Sitdikova, Guzel F.; Weiger, Thomas M.

    2015-01-01

    All cells contain ion channels in their outer (plasma) and inner (organelle) membranes. Ion channels, similar to other proteins, are targets of oxidative impact, which modulates ion fluxes across membranes. Subsequently, these ion currents affect electrical excitability, such as action potential discharge (in neurons, muscle, and receptor cells), alteration of the membrane resting potential, synaptic transmission, hormone secretion, muscle contraction or coordination of the cell cycle. In this chapter we summarize effects of oxidative stress and redox mechanisms on some ion channels, in particular on maxi calcium-activated potassium (BK) channels which play an outstanding role in a plethora of physiological and pathophysiological functions in almost all cells and tissues. We first elaborate on some general features of ion channel structure and function and then summarize effects of oxidative alterations of ion channels and their functional consequences. PMID:26287261

  3. Oxidative stress, activity behaviour and body mass in captive parrots.

    PubMed

    Larcombe, S D; Tregaskes, C A; Coffey, J; Stevenson, A E; Alexander, L G; Arnold, K E

    2015-01-01

    Many parrot species are kept in captivity for conservation, but often show poor reproduction, health and survival. These traits are known to be influenced by oxidative stress, the imbalance between the production of reactive oxygen species (ROS) and ability of antioxidant defences to ameliorate ROS damage. In humans, oxidative stress is linked with obesity, lack of exercise and poor nutrition, all of which are common in captive animals. Here, we tested whether small parrots (budgerigars, Melopsittacus undulatus) maintained in typical pet cages and on ad libitum food varied in oxidative profile, behaviour and body mass. Importantly, as with many birds held in captivity, they did not have enough space to engage in extensive free flight. Four types of oxidative damage, single-stranded DNA breaks (low-pH comet assay), alkali-labile sites in DNA (high-pH comet assay), sensitivity of DNA to ROS (H2O2-treated comet assay) and malondialdehyde (a byproduct of lipid peroxidation), were uncorrelated with each other and with plasma concentrations of dietary antioxidants. Without strenuous exercise over 28 days in a relatively small cage, more naturally 'active' individuals had more single-stranded DNA breaks than sedentary birds. High body mass at the start or end of the experiment, coupled with substantial mass gain, were all associated with raised sensitivity of DNA to ROS. Thus, high body mass in these captive birds was associated with oxidative damage. These birds were not lacking dietary antioxidants, because final body mass was positively related to plasma levels of retinol, zeaxanthin and α-tocopherol. Individuals varied widely in activity levels, feeding behaviour, mass gain and oxidative profile despite standardized living conditions. DNA damage is often associated with poor immunocompetence, low fertility and faster ageing. Thus, we have candidate mechanisms for the limited lifespan and fecundity common to many birds kept for conservation purposes.

  4. Oxidative stress, activity behaviour and body mass in captive parrots.

    PubMed

    Larcombe, S D; Tregaskes, C A; Coffey, J; Stevenson, A E; Alexander, L G; Arnold, K E

    2015-01-01

    Many parrot species are kept in captivity for conservation, but often show poor reproduction, health and survival. These traits are known to be influenced by oxidative stress, the imbalance between the production of reactive oxygen species (ROS) and ability of antioxidant defences to ameliorate ROS damage. In humans, oxidative stress is linked with obesity, lack of exercise and poor nutrition, all of which are common in captive animals. Here, we tested whether small parrots (budgerigars, Melopsittacus undulatus) maintained in typical pet cages and on ad libitum food varied in oxidative profile, behaviour and body mass. Importantly, as with many birds held in captivity, they did not have enough space to engage in extensive free flight. Four types of oxidative damage, single-stranded DNA breaks (low-pH comet assay), alkali-labile sites in DNA (high-pH comet assay), sensitivity of DNA to ROS (H2O2-treated comet assay) and malondialdehyde (a byproduct of lipid peroxidation), were uncorrelated with each other and with plasma concentrations of dietary antioxidants. Without strenuous exercise over 28 days in a relatively small cage, more naturally 'active' individuals had more single-stranded DNA breaks than sedentary birds. High body mass at the start or end of the experiment, coupled with substantial mass gain, were all associated with raised sensitivity of DNA to ROS. Thus, high body mass in these captive birds was associated with oxidative damage. These birds were not lacking dietary antioxidants, because final body mass was positively related to plasma levels of retinol, zeaxanthin and α-tocopherol. Individuals varied widely in activity levels, feeding behaviour, mass gain and oxidative profile despite standardized living conditions. DNA damage is often associated with poor immunocompetence, low fertility and faster ageing. Thus, we have candidate mechanisms for the limited lifespan and fecundity common to many birds kept for conservation purposes. PMID:27293729

  5. Fatigue strength of a single lap joint SPR-bonded

    SciTech Connect

    Di Franco, G.; Fratini, L.; Pasta, A.

    2011-05-04

    In the last years, hybrid joints, meaning with this the joints which consist in combining a traditional mechanical joint to a layer of adhesive, are gradually attracting the attention of various sectors of the construction of vehicles and transportation industries, for their better performance compared to just mechanical joints (self-piercing riveting SPR, riveting, and so on) or just to bonded joints.The paper investigates the fatigue behavior of a single lap joint self-piercing riveted (SPR) and bonded throughout fatigue tests. The considered geometric configuration allowed the use of two rivets placed longitudinally; an epoxy resin was used as adhesive. In the first part of the work static characterization of the joints was carried out through tensile tests. Then fatigue tests were made with the application of different levels of load. The fatigue curves were also obtained at the varying the distance between the two rivets in order to better assess the joint strength for a given length of overlap.

  6. Molten pool characterization of laser lap welded copper and aluminum

    NASA Astrophysics Data System (ADS)

    Xue, Zhiqing; Hu, Shengsun; Zuo, Di; Cai, Wayne; Lee, Dongkyun; Elijah, Kannatey-Asibu, Jr.

    2013-12-01

    A 3D finite volume simulation model for laser welding of a Cu-Al lap joint was developed using ANSYS FLUENT to predict the weld pool temperature distribution, velocity field, geometry, alloying element distribution and transition layer thickness—all key attributes and performance characteristics for a laser-welded joint. Melting and solidification of the weld pool was simulated with an enthalpy-porosity formulation. Laser welding experiments and metallographic examination by SEM and EDX were performed to investigate the weld pool features and validate the simulated results. A bowl-shaped temperature field and molten pool, and a unique maximum fusion zone width were observed near the Cu-Al interface. Both the numerical simulation and experimental results indicate an arch-shaped intermediate layer of Cu and Al, and a gradual transition of Cu concentration from the aluminum plate to the copper plate with high composition gradient. For the conditions used, welding with Cu on top was found to result in a better weld joint.

  7. Osseous manifestations of elbow stress associated with sports activities.

    PubMed

    Gore, R M; Rogers, L F; Bowerman, J; Suker, J; Compere, C L

    1980-05-01

    The radiographic manifestations of musculoskeletal stress at the elbow associated with racket and throwing sports are reported in 29 symptomatic amateur, juvenile, and professional athletes. Five major categories of stress are identified: diffuse, humeral shaft, medial tension, lateral compression, and extension stress. The osseous changes produced by these stresses include bony hypertrophy, loose bodies, traction spur formation, osteochondral and humeral shaft fractures in the adult, and epiphyseal and apophyseal hypermaturity or avulsion in the youngster.

  8. Improving Health by Reducing Stress: An Experiential Activity

    ERIC Educational Resources Information Center

    Largo-Wight, Erin; Moore, Michele J.; Barr, Elissa M.

    2011-01-01

    Stress is a leading health issue among college students. Managing stress involves enhancing resources necessary to cope with life's demands. Relaxation techniques are especially critical coping strategies when stress is chronic and coping resources are overused and fatigued. Methods: This article describes a research-based relaxation technique…

  9. Apoptosis in the lens anlage of the heritable lens aplastic mouse (lap mouse).

    PubMed

    Aso, S; Tashiro, M; Baba, R; Sawaki, M; Noda, S; Fujita, M

    1998-08-01

    Adult homozygous lap mice show various eye abnormalities, such as aphakia, retinal disorganization, and dysplasia of the cornea and anterior chamber. In the fetal eye of a homozygous lap mouse, the lens placode seems to develop normally. However, the lens vesicle progresses abnormally to form a mass of cells without a cavity, and the mass vanishes soon afterward. We examined cell death in the lens anlage of this mutant. The lens anlagen of homozygous lap and normal mice from days 10 to 12 of gestation were observed by light microscopy after DNA end-labeling by immunohistochemistry and by transmission electron microscopy. By light microscopy, a slight frequency of cell death was detected in the lens anlage encircling the surface ectoderm and in the anlage or in the anlage of both homozygous lap mice and normal mice at day 10 of gestation. Cell death was seen in the lens anlage encircling the surface ectoderm in the normal mouse and sporadically in the anlage of the homozygous lap mouse at day 10.5 of gestation. Cell death was visible at the area of the lens vesicle attached to the surface ectoderm and encircling the surrounding surface ectoderm in the normal mouse, and in the lens anlage encircling the surface ectoderm and the apex areas of the lens anlage in the homozygous lap mouse at day 11 of gestation. At day 12 of gestation, almost no cell death was observed in the lens anlage of the normal mouse. However, extensive areas of cell death were still seen in the lens anlage at its apex, at the inner region, and encircling the surface ectoderm in the homozygous lap mouse. Electron microscopic observation showed that the dead cells observed in the lens anlagen by light microscopy in normal and lap mice are the result of apoptosis. In lap mice, cells with cytoplasmic condensation were observed mainly at days 10 and 10.5 of gestation. Many apoptotic bodies which had been phagocytosed by adjacent cells were seen predominantly at day 11 of gestation. At day 12 of

  10. Initiation and growth of multiple-site damage in the riveted lap joint of a curved stiffened fuselage panel: An experimental and analytical study

    NASA Astrophysics Data System (ADS)

    Ahmed, Abubaker Ali

    As part of the structural integrity research of the National Aging Aircraft Research Program, a comprehensive study on multiple-site damage (MSD) initiation and growth in a pristine lap-joint fuselage panel has been conducted. The curved stiffened fuselage panel was tested at the Full-Scale Aircraft Structural Test Evaluation and Research (FASTER) facility located at the Federal Aviation Administration William J. Hughes Technical Center. A strain survey test was conducted to verify proper load application. The panel was then subjected to a fatigue test with constant-amplitude cyclic loading. The applied loading spectrum included underload marker cycles so that crack growth history could be reconstructed from post-test fractographic examinations. Crack formation and growth were monitored via nondestructive and high-magnification visual inspections. Strain gage measurements recorded during the strain survey tests indicated that the inner surface of the skin along the upper rivet row of the lap joint experienced high tensile stresses due to local bending. During the fatigue loading, cracks were detected by eddy-current inspections at multiple rivet holes along the upper rivet row. Through-thickness cracks were detected visually after about 80% of the fatigue life. Once MSD cracks from two adjacent rivet holes linked up, there was a quick deterioration in the structural integrity of the lap joint. The linkup resulted in a 2.87" (72.9-mm) lead fatigue crack that rapidly propagated across 12 rivet holes and crossed over into the next skin bay, at which stage the fatigue test was terminated. A post-fatigue residual strength test was then conducted by loading the panel quasi-statically up to final failure. The panel failed catastrophically when the crack extended instantaneously across three additional bays. Post-test fractographic examinations of the fracture surfaces in the lap joint of the fuselage panel were conducted to characterize subsurface crack initiation and

  11. Oxidative stress inhibition and oxidant activity by fibrous clays.

    PubMed

    Cervini-Silva, Javiera; Nieto-Camacho, Antonio; Gómez-Vidales, Virginia

    2015-09-01

    Fibrous clays (sepiolite, palygorskite) are produced at 1.2m tonnes per year and have a wide range of industrial applications needing to replace long-fibre length asbestos. However, information on the beneficial effects of fibrous clays on health remains scarce. This paper reports on the effect of sepiolite (Vallecas, Spain) and palygorskite (Torrejón El Rubio, Spain) on cell damage via oxidative stress (determined as the progress of lipid peroxidation, LP). The extent of LP was assessed using the Thiobarbituric Acid Reactive Substances assay. The oxidant activity by fibrous clays was quantified using Electron-Paramagnetic Resonance. Sepiolite and palygorskite inhibited LP, whereby corresponding IC50 values were 6557±1024 and 4250±289μgmL(-1). As evidenced by dose-response experiments LP inhibition by palygorskite was surface-controlled. Fibrous clay surfaces did not stabilize HO species, except for suspensions containing 5000μgmL(-1). A strong oxidant (or weak anti-oxidant) activity favours the inhibition of LP by fibrous clays.

  12. Oxidative stress inhibition and oxidant activity by fibrous clays.

    PubMed

    Cervini-Silva, Javiera; Nieto-Camacho, Antonio; Gómez-Vidales, Virginia

    2015-09-01

    Fibrous clays (sepiolite, palygorskite) are produced at 1.2m tonnes per year and have a wide range of industrial applications needing to replace long-fibre length asbestos. However, information on the beneficial effects of fibrous clays on health remains scarce. This paper reports on the effect of sepiolite (Vallecas, Spain) and palygorskite (Torrejón El Rubio, Spain) on cell damage via oxidative stress (determined as the progress of lipid peroxidation, LP). The extent of LP was assessed using the Thiobarbituric Acid Reactive Substances assay. The oxidant activity by fibrous clays was quantified using Electron-Paramagnetic Resonance. Sepiolite and palygorskite inhibited LP, whereby corresponding IC50 values were 6557±1024 and 4250±289μgmL(-1). As evidenced by dose-response experiments LP inhibition by palygorskite was surface-controlled. Fibrous clay surfaces did not stabilize HO species, except for suspensions containing 5000μgmL(-1). A strong oxidant (or weak anti-oxidant) activity favours the inhibition of LP by fibrous clays. PMID:26071933

  13. Oxidative stress, activity behaviour and body mass in captive parrots

    PubMed Central

    Larcombe, S. D.; Tregaskes, C. A.; Coffey, J.; Stevenson, A. E.; Alexander, L. G.; Arnold, K. E.

    2015-01-01

    Many parrot species are kept in captivity for conservation, but often show poor reproduction, health and survival. These traits are known to be influenced by oxidative stress, the imbalance between the production of reactive oxygen species (ROS) and ability of antioxidant defences to ameliorate ROS damage. In humans, oxidative stress is linked with obesity, lack of exercise and poor nutrition, all of which are common in captive animals. Here, we tested whether small parrots (budgerigars, Melopsittacus undulatus) maintained in typical pet cages and on ad libitum food varied in oxidative profile, behaviour and body mass. Importantly, as with many birds held in captivity, they did not have enough space to engage in extensive free flight. Four types of oxidative damage, single-stranded DNA breaks (low-pH comet assay), alkali-labile sites in DNA (high-pH comet assay), sensitivity of DNA to ROS (H2O2-treated comet assay) and malondialdehyde (a byproduct of lipid peroxidation), were uncorrelated with each other and with plasma concentrations of dietary antioxidants. Without strenuous exercise over 28 days in a relatively small cage, more naturally ‘active’ individuals had more single-stranded DNA breaks than sedentary birds. High body mass at the start or end of the experiment, coupled with substantial mass gain, were all associated with raised sensitivity of DNA to ROS. Thus, high body mass in these captive birds was associated with oxidative damage. These birds were not lacking dietary antioxidants, because final body mass was positively related to plasma levels of retinol, zeaxanthin and α-tocopherol. Individuals varied widely in activity levels, feeding behaviour, mass gain and oxidative profile despite standardized living conditions. DNA damage is often associated with poor immunocompetence, low fertility and faster ageing. Thus, we have candidate mechanisms for the limited lifespan and fecundity common to many birds kept for conservation purposes. PMID

  14. Helping Children Cope with Fears and Stress. Part I: Discussion and Activities. Part II: Facilitator's Guide.

    ERIC Educational Resources Information Center

    Robinson, Edward H.; And Others

    How fears, phobias, anxiety and stress develop in elementary school students and how these students can be assisted in coping with fears and stress are discussed in this book. Part 1, "Discussion and Activities," contains six sections. Section 1 presents an overview of fears, and stress in children. Section 2 presents 12 fear-specific activities…

  15. Mechanical stress activates neurites and somata of myenteric neurons

    PubMed Central

    Kugler, Eva M.; Michel, Klaus; Zeller, Florian; Demir, Ihsan E.; Ceyhan, Güralp O.; Schemann, Michael; Mazzuoli-Weber, Gemma

    2015-01-01

    The particular location of myenteric neurons, sandwiched between the 2 muscle layers of the gut, implies that their somata and neurites undergo mechanical stress during gastrointestinal motility. Existence of mechanosensitive enteric neurons (MEN) is undoubted but many of their basic features remain to be studied. In this study, we used ultra-fast neuroimaging to record activity of primary cultured myenteric neurons of guinea pig and human intestine after von Frey hair evoked deformation of neurites and somata. Independent component analysis was applied to reconstruct neuronal morphology and follow neuronal signals. Of the cultured neurons 45% (114 out of 256, 30 guinea pigs) responded to neurite probing with a burst spike frequency of 13.4 Hz. Action potentials generated at the stimulation site invaded the soma and other neurites. Mechanosensitive sites were expressed across large areas of neurites. Many mechanosensitive neurites appeared to have afferent and efferent functions as those that responded to deformation also conducted spikes coming from the soma. Mechanosensitive neurites were also activated by nicotine application. This supported the concept of multifunctional MEN. 14% of the neurons (13 out of 96, 18 guinea pigs) responded to soma deformation with burst spike discharge of 17.9 Hz. Firing of MEN adapted rapidly (RAMEN), slowly (SAMEN), or ultra-slowly (USAMEN). The majority of MEN showed SAMEN behavior although significantly more RAMEN occurred after neurite probing. Cultured myenteric neurons from human intestine had similar properties. Compared to MEN, dorsal root ganglion neurons were activated by neurite but not by soma deformation with slow adaptation of firing. We demonstrated that MEN exhibit specific features very likely reflecting adaptation to their specialized functions in the gut. PMID:26441520

  16. Monitoring eruption activity using temporal stress changes at Mount Ontake volcano

    PubMed Central

    Terakawa, Toshiko; Kato, Aitaro; Yamanaka, Yoshiko; Maeda, Yuta; Horikawa, Shinichiro; Matsuhiro, Kenjiro; Okuda, Takashi

    2016-01-01

    Volcanic activity is often accompanied by many small earthquakes. Earthquake focal mechanisms represent the fault orientation and slip direction, which are influenced by the stress field. Focal mechanisms of volcano-tectonic earthquakes provide information on the state of volcanoes via stresses. Here we demonstrate that quantitative evaluation of temporal stress changes beneath Mt. Ontake, Japan, using the misfit angles of focal mechanism solutions to the regional stress field, is effective for eruption monitoring. The moving average of misfit angles indicates that during the precursory period the local stress field beneath Mt. Ontake was deviated from the regional stress field, presumably by stress perturbations caused by the inflation of magmatic/hydrothermal fluids, which was removed immediately after the expulsion of volcanic ejecta. The deviation of the local stress field can be an indicator of increases in volcanic activity. The proposed method may contribute to the mitigation of volcanic hazards. PMID:26892716

  17. Monitoring eruption activity using temporal stress changes at Mount Ontake volcano

    NASA Astrophysics Data System (ADS)

    Terakawa, Toshiko; Kato, Aitaro; Yamanaka, Yoshiko; Maeda, Yuta; Horikawa, Shinichiro; Matsuhiro, Kenjiro; Okuda, Takashi

    2016-02-01

    Volcanic activity is often accompanied by many small earthquakes. Earthquake focal mechanisms represent the fault orientation and slip direction, which are influenced by the stress field. Focal mechanisms of volcano-tectonic earthquakes provide information on the state of volcanoes via stresses. Here we demonstrate that quantitative evaluation of temporal stress changes beneath Mt. Ontake, Japan, using the misfit angles of focal mechanism solutions to the regional stress field, is effective for eruption monitoring. The moving average of misfit angles indicates that during the precursory period the local stress field beneath Mt. Ontake was deviated from the regional stress field, presumably by stress perturbations caused by the inflation of magmatic/hydrothermal fluids, which was removed immediately after the expulsion of volcanic ejecta. The deviation of the local stress field can be an indicator of increases in volcanic activity. The proposed method may contribute to the mitigation of volcanic hazards.

  18. Monitoring eruption activity using temporal stress changes at Mount Ontake volcano.

    PubMed

    Terakawa, Toshiko; Kato, Aitaro; Yamanaka, Yoshiko; Maeda, Yuta; Horikawa, Shinichiro; Matsuhiro, Kenjiro; Okuda, Takashi

    2016-01-01

    Volcanic activity is often accompanied by many small earthquakes. Earthquake focal mechanisms represent the fault orientation and slip direction, which are influenced by the stress field. Focal mechanisms of volcano-tectonic earthquakes provide information on the state of volcanoes via stresses. Here we demonstrate that quantitative evaluation of temporal stress changes beneath Mt. Ontake, Japan, using the misfit angles of focal mechanism solutions to the regional stress field, is effective for eruption monitoring. The moving average of misfit angles indicates that during the precursory period the local stress field beneath Mt. Ontake was deviated from the regional stress field, presumably by stress perturbations caused by the inflation of magmatic/hydrothermal fluids, which was removed immediately after the expulsion of volcanic ejecta. The deviation of the local stress field can be an indicator of increases in volcanic activity. The proposed method may contribute to the mitigation of volcanic hazards.

  19. Monitoring eruption activity using temporal stress changes at Mount Ontake volcano.

    PubMed

    Terakawa, Toshiko; Kato, Aitaro; Yamanaka, Yoshiko; Maeda, Yuta; Horikawa, Shinichiro; Matsuhiro, Kenjiro; Okuda, Takashi

    2016-01-01

    Volcanic activity is often accompanied by many small earthquakes. Earthquake focal mechanisms represent the fault orientation and slip direction, which are influenced by the stress field. Focal mechanisms of volcano-tectonic earthquakes provide information on the state of volcanoes via stresses. Here we demonstrate that quantitative evaluation of temporal stress changes beneath Mt. Ontake, Japan, using the misfit angles of focal mechanism solutions to the regional stress field, is effective for eruption monitoring. The moving average of misfit angles indicates that during the precursory period the local stress field beneath Mt. Ontake was deviated from the regional stress field, presumably by stress perturbations caused by the inflation of magmatic/hydrothermal fluids, which was removed immediately after the expulsion of volcanic ejecta. The deviation of the local stress field can be an indicator of increases in volcanic activity. The proposed method may contribute to the mitigation of volcanic hazards. PMID:26892716

  20. Stress and CRF gate neural activation of BDNF in the mesolimbic reward pathway.

    PubMed

    Walsh, Jessica J; Friedman, Allyson K; Sun, Haosheng; Heller, Elizabeth A; Ku, Stacy M; Juarez, Barbara; Burnham, Veronica L; Mazei-Robison, Michelle S; Ferguson, Deveroux; Golden, Sam A; Koo, Ja Wook; Chaudhury, Dipesh; Christoffel, Daniel J; Pomeranz, Lisa; Friedman, Jeffrey M; Russo, Scott J; Nestler, Eric J; Han, Ming-Hu

    2014-01-01

    Mechanisms controlling release of brain-derived neurotrophic factor (BDNF) in the mesolimbic dopamine reward pathway remain unknown. We report that phasic optogenetic activation of this pathway increases BDNF amounts in the nucleus accumbens (NAc) of socially stressed mice but not of stress-naive mice. This stress gating of BDNF signaling is mediated by corticotrophin-releasing factor (CRF) acting in the NAc. These results unravel a stress context-detecting function of the brain's mesolimbic circuit.

  1. Ozone exposure activates oxidative stress responses in murine skin.

    PubMed

    Valacchi, Giuseppe; van der Vliet, Albert; Schock, Bettina C; Okamoto, Tatsuya; Obermuller-Jevic, Ute; Cross, Carroll E; Packer, Lester

    2002-09-30

    Ozone (O(3)) is among the most reactive environmental oxidant to which skin is exposed. O(3) exposure has previously been shown to induce antioxidant depletion as well as lipid and protein oxidation in the outermost skin layer, the stratum corneum (SC), but little is known regarding the potential effects of O(3) on the skin epidermis and dermis. To evaluate such skin responses to O(3), SKH-1 hairless mice were exposed for 2 h to 8.0 ppm O(3) or to ambient air. O(3) exposure caused a significant increase in skin carbonyls (28%) compared to the skin of air exposed control animals. An evident increase in 4-hydroxynonenal-protein adducts was detected after O(3) exposure. O(3) exposure caused a rapid up-regulation of HSP27 (20-fold), and more delayed induction of HSP70 (2.8-fold) and heme oxygenase-1 (5-fold). O(3) exposure also led to the induction of nitric oxide synthase (iNOS) 6-12 h following O(3) exposure. We conclude that skin exposure to high levels of O(3) not only affects antioxidant levels and oxidation markers in the SC, but also induces stress responses in the active layers of the skin, most likely by indirect mechanisms, since it is unlikely that O(3) itself penetrates the protective SC layers.

  2. Large-scale Advanced Prop-fan (LAP) high speed wind tunnel test report

    NASA Technical Reports Server (NTRS)

    Campbell, William A.; Wainauski, Harold S.; Arseneaux, Peter J.

    1988-01-01

    High Speed Wind Tunnel testing of the SR-7L Large Scale Advanced Prop-Fan (LAP) is reported. The LAP is a 2.74 meter (9.0 ft) diameter, 8-bladed tractor type rated for 4475 KW (6000 SHP) at 1698 rpm. It was designated and built by Hamilton Standard under contract to the NASA Lewis Research Center. The LAP employs thin swept blades to provide efficient propulsion at flight speeds up to Mach .85. Testing was conducted in the ONERA S1-MA Atmospheric Wind Tunnel in Modane, France. The test objectives were to confirm that the LAP is free from high speed classical flutter, determine the structural and aerodynamic response to angular inflow, measure blade surface pressures (static and dynamic) and evaluate the aerodynamic performance at various blade angles, rotational speeds and Mach numbers. The measured structural and aerodynamic performance of the LAP correlated well with analytical predictions thereby providing confidence in the computer prediction codes used for the design. There were no signs of classical flutter throughout all phases of the test up to and including the 0.84 maximum Mach number achieved. Steady and unsteady blade surface pressures were successfully measured for a wide range of Mach numbers, inflow angles, rotational speeds and blade angles. No barriers were discovered that would prevent proceeding with the PTA (Prop-Fan Test Assessment) Flight Test Program scheduled for early 1987.

  3. Evaluation of pediatric use patterns and performance of lap shoulder belt systems in the center rear.

    PubMed

    Arbogast, Kristy B; Durbin, Dennis R; Kallan, Michael J; Winston, Flaura K

    2004-01-01

    Lap and shoulder belts have been required in rear outboard positions since 1989. A recent congressional mandate encouraged the requirement of a lap and shoulder belt in the center rear seat position. This study utilized Data from the Partners for Child Passenger Safety study, a large-scale child-focused crash surveillance system, to quantify changes in seating patterns for children in vehicles that already have this feature compared to those which do not and measured the safety benefit associated with the provision of a shoulder belt in the center rear seat position. The data demonstrate that the presence of a shoulder belt in the center rear seating position influences seating practices only when there is a single child occupant in the vehicle. Belted children in the center rear of vehicles equipped with a lap shoulder belt are at an 81% reduction in risk of injury than those belted in the center rear equipped with a lap only belt. The data suggest that by requiring lap shoulder belts in the center rear, benefits would be realized to belted children, specifically the 4-8 year old group.

  4. Application of the lag-after-pulsed-separation (LAPS) flow meter to different protein solutions.

    PubMed

    Sengupta, Shramik; Mahmud, Goher; Chiou, Daniel J; Ziaie, Babak; Barocas, Victor H

    2005-02-01

    A lag after pulsed separation (LAPS) meter was previously developed to measure flow rates of protein solutions. The LAPS meter operates on the time-of-flight principle. An upstream event (electrophoretic concentration of the particles in one section of the device) is detected downstream (by change in ac resistance). The time lag between the event and its detection is inversely proportional to the fluid flow rate. We demonstrate the ability of the LAPS meter to measure the flow rate of solutions containing one or more charged biomacromolecules or particles. A prototype of the LAPS meter was used to measure flow rates of solutions of model proteins [bovine serum albumin (BSA), lysozyme and hemoglobin] and mixtures of BSA and lysozyme. Flow rates of 10-50 microl min(-1)(average velocities of 0.24-1.2 mm s(-1)) were measured. When a single ac measurement was used, the results were solution-dependent, which we attribute to the interface between the protein solution and the ac electrodes. A differential mode, in which the signal from a positive and a negative dc pulse were subtracted from each other, eliminated interfacial effects and led to a single universal (solution-independent) calibration curve. The LAPS meter can be used as a non-invasive, no-moving-parts flow sensor in any microfluidic system (such as drug delivery devices or micro-reactor arrays) where one needs to measure the flow rate of a solution or a suspension containing charged species such as proteins or cells.

  5. The importance of physical activity and sleep for affect on stressful days: Two intensive longitudinal studies.

    PubMed

    Flueckiger, Lavinia; Lieb, Roselind; Meyer, Andrea H; Witthauer, Cornelia; Mata, Jutta

    2016-06-01

    We investigated the potential stress-buffering effect of 3 health behaviors-physical activity, sleep quality, and snacking-on affect in the context of everyday life in young adults. In 2 intensive longitudinal studies with up to 65 assessment days over an entire academic year, students (Study 1, N = 292; Study 2, N = 304) reported stress intensity, sleep quality, physical activity, snacking, and positive and negative affect. Data were analyzed using multilevel regression analyses. Stress and positive affect were negatively associated; stress and negative affect were positively associated. The more physically active than usual a person was on a given day, the weaker the association between stress and positive affect (Study 1) and negative affect (Studies 1 and 2). The better than usual a person's sleep quality had been during the previous night, the weaker the association between stress and positive affect (Studies 1 and 2) and negative affect (Study 2). The association between daily stress and positive or negative affect did not differ as a function of daily snacking (Studies 1 and 2). On stressful days, increasing physical activity or ensuring high sleep quality may buffer adverse effects of stress on affect in young adults. These findings suggest potential targets for health-promotion and stress-prevention programs, which could help reduce the negative impact of stress in young adults. (PsycINFO Database Record

  6. Tibial stress fractures in an active duty population: long-term outcomes.

    PubMed

    Kilcoyne, Kelly G; Dickens, Jonathan F; Rue, John-Paul

    2013-01-01

    Tibial stress fractures are a common overuse injury among military recruits. The purpose of this study was to determine what, if any, long-term effects that tibial stress fractures have on military personnel with respect to physical activity level, completion of military training, recurrence of symptoms, and active duty service. Twenty-six military recruits included in a previous tibial stress fracture study were contacted 10 years after initial injury and asked a series of questions related to any long-term consequences of their tibial stress fracture. Of the 13 patients available for contact, no patients reported any necessary limited duty while on active duty, and no patient reported being separated or discharged from the military as a result of stress fracture. Tibial stress fractures in military recruits are most often an isolated injury and do not affect ability to complete military training or reflect a long-term need for decreased physical activity.

  7. The contribution of activated processes to Q. [stress corrosion cracking in seismic wave attenuation

    NASA Technical Reports Server (NTRS)

    Spetzler, H. A.; Getting, I. C.; Swanson, P. L.

    1980-01-01

    The possible role of activated processes in seismic attenuation is investigated. In this study, a solid is modeled by a parallel and series configuration of dashpots and springs. The contribution of stress and temperature activated processes to the long term dissipative behavior of this system is analyzed. Data from brittle rock deformation experiments suggest that one such process, stress corrosion cracking, may make a significant contribution to the attenuation factor, Q, especially for long period oscillations under significant tectonic stress.

  8. [Stress prevention programs--strategies, techniques, effectiveness. Part II. Organizational activities to prevent stress at work].

    PubMed

    Małgorzata, W; Merecz, Dorota; Drabek, Marcin

    2010-01-01

    This is the second part of the publication on approaches to occupational stress prevention and a state of the art in different European countries. In this part, stress prevention within an organization is described and discussed. Although there is no one way of tackling stress at work, some recommendations can be formulated to increase the effectiveness of such interventions. The effective stress reducing programs should be aimed both at changes in the organization itself and empowerment of employees' coping with stress resources. It is also important to take the advantage of wide spectrum of methods and techniques (e.g., work redesign, participation, team work, cognitive behavioral methods, relaxation, etc.) remembering that one size does not fit all. The intervention should be carefully planned and adopted to the various branches, an individual organization or department and should be preceded by the identification of stress risks and risk groups. To have the stress prevention program successfully introduced one should also consider factors which may influence (positively or negatively) the process of program implementation.

  9. [Unpredictable chronic mild stress effects on antidepressants activities in forced swim test].

    PubMed

    Kudryashov, N V; Kalinina, T S; Voronina, T A

    2015-02-01

    The experiments has been designed to study unpredictable chronic mild stress effect on anti-depressive activities of amitriptyline (10 mg/kg) and fluoxetine (20 mg/kg) in forced swim test in male outbred mice. It is shown that acute treatment with fluoxetine does not produce any antidepressant effects in mice following stress of 14 days while the sub-chronic injections of fluoxetine result in more deep depressive-like behavior. In 28 daily stressed mice, antidepressant effect of fluoxetine is observed independently of the injection rates. Amitriptyline demonstrates the antidepressant activity regardless of the duration of stress or administration scheduling, but at the same time the severity of anti-immobilization effect of amitriptyline in stressed mice is weaker in compare to non-stressed trails. Thus, the injection rates and duration of unpredictable mild chronic stress are the parameters that determine the efficiency of antidepressants in the mouse forced swimming test.

  10. Lap belt iliac wing fracture: a predictor of bowel injury in children.

    PubMed

    Emery, Kathleen H

    2002-12-01

    Lap belt restraints in motor vehicle collisions have been associated with a variety of injuries, mainly bowel and lumbar spine. Cephalad positioning of the belt over the intended position across the anterior superior iliac spines (which typically occurs in younger children) is thought to be responsible for the observed bowel injuries. We report two pediatric patients, both restrained by lap belts in high-speed collisions, who suffered iliac wing fractures in addition to bowel injuries. Unexplained free peritoneal fluid was the sole CT finding in one patient (a teenage girl) who had a delay in diagnosis of bowel perforation. These cases illustrate the high frequency of bowel injury in pediatric patients with iliac wing fractures associated with lap belt use.

  11. Measurements of fuselage skin strains and displacements near a longitudinal lap joint in a pressurized aircraft

    NASA Technical Reports Server (NTRS)

    Phillips, Edward P.; Britt, Vicki O.

    1991-01-01

    Strains and displacements in a small area near a longitudinal lap joint in the fuselage skin of a B737 aircraft were measured during a pressurization cycle to a differential pressure of 6.2 psi while the aircraft was on the ground. It was found that hoop strains were higher than longitudinal strains at each location; membrane strains in the unreinforced skin were higher than in the joint; membrane strains in the hoop direction, as well as radial displacements, tended to be highest at the mid-bay location between skin reinforcements; significant bending in the hoop direction occurred in the joint and in the skin near the joint, and the bending was unsymmetrically distributed about the stringer at the middle of the joint; and radial displacements were unsymmetrically distributed across the lap joint. The interpretation of the strain gage data for locations on the bonded and riveted lap joint assumed that the joint did not contain disbonded areas.

  12. Large-scale Advanced Prop-fan (LAP) technology assessment report

    NASA Technical Reports Server (NTRS)

    Degeorge, C. L.

    1988-01-01

    The technologically significant findings and accomplishments of the Large Scale Advanced Prop-Fan (LAP) program in the areas of aerodynamics, aeroelasticity, acoustics and materials and fabrication are described. The extent to which the program goals related to these disciplines were achieved is discussed, and recommendations for additional research are presented. The LAP program consisted of the design, manufacture and testing of a near full-scale Prop-Fan or advanced turboprop capable of operating efficiently at speeds to Mach .8. An aeroelastically scaled model of the LAP was also designed and fabricated. The goal of the program was to acquire data on Prop-Fan performance that would indicate the technology readiness of Prop-Fans for practical applications in commercial and military aviation.

  13. Grain decoration in aluminum oxynitride (ALON) from polishing on bound abrasive laps

    NASA Astrophysics Data System (ADS)

    Gregg, Leslie L.; Marino, Anne E.; Hayes, Jennifer C.; Jacobs, Stephen D.

    2004-01-01

    Aluminum oxynitride (ALON) is a polycrystalline material that has proven difficult to polish due to its grain structure. Bound abrasives are an effective means for polishing ALON, and work is being done with them to obtain good surfaces, with reasonable removal rates. Laps consisting of abrasives bound in epoxy matrices were created for polishing ALON. The effects of varying abrasive type, abrasive concentration, lap shape, coolant and load were studied. Metrology procedures were developed to monitor different aspects of the grain structure and numerically evaluate grain boundary decoration. Strategies were developed to polish ALON at acceptable rates with reasonably good surface quality. Work is directed toward finding optimal bound abrasive lap formulations that can be fabricated into ring and/or contour tools for testing on CNC machining platforms.

  14. Grain decoration in aluminum oxynitride (ALON) from polishing on bound abrasive laps

    NASA Astrophysics Data System (ADS)

    Marino, Anne E.; Hayes, Jennifer; Gregg, Leslie L.; Jacobs, Stephen D.

    2003-05-01

    Aluminum oxynitride (ALON) is a material with desirable qualities for a variety of applications that has proven difficult to polish because of its grain structure. Bound abrasives may prove to be an effective means of polishing it, and work is being done with them to obtain good surfaces on ALON, with reasonable removal rates. Laps consisting of abrasives bound in epoxy matrices have been created for polishing ALON. The effects of varying abrasive type, abrasive concentration, lap shape, coolant and load are being studied. Metrology procedures are being developed to monitor different aspects of the grain structure and numerically evaluate its decoration. Strategies have been developed to polish ALON at acceptable rates with reasonably good surface quality. Work is directed toward finding optimal bound abrasive lap formulations that can be fabricated into ring and/or contour tools for testing on CNC machining platforms.

  15. EFFECT OF TOOL FEATURE ON THE JOINT STRENGTH OF DISSIMILAR FRICTION STIR LAP WELDS

    SciTech Connect

    Jana, Saumyadeep; Hovanski, Yuri; Grant, Glenn J.; Mattlin, Karl F.

    2011-04-25

    Several variations of friction stir tools were used to investigate the effects on the joint strengths of dissimilar friction stir lap welds. In the present lap weld configuration the top sheet was a 2.32 mm thick Mg (AZ 31) alloy. The bottom sheet consisted of two different steels, a (i) 0.8 mm thick electro-galvanized (EG) mild steel, or a (ii) 1.5 mm thick hot dip galvanized (HDG) high strength low alloy (HSLA) steel. Initially the tool shape was modified to accommodate the material, at which point the tool geometry was fixed. With a fixed tool geometry an additional feature was added to the pin bottom on one of the tools by incorporating a short hard insert, which would act as a stronger bottom sheet cutter. The effects of such modification on the unguided lap shear strength, and associated microstructural changes are discussed in this study.

  16. Resveratrol-loaded Nanoparticles Induce Antioxidant Activity against Oxidative Stress

    PubMed Central

    Kim, Jae-Hwan; Park, Eun-Young; Ha, Ho-Kyung; Jo, Chan-Mi; Lee, Won-Jae; Lee, Sung Sill; Kim, Jin Wook

    2016-01-01

    Resveratrol acts as a free radical scavenger and a potent antioxidant in the inhibition of numerous reactive oxygen species (ROS). The function of resveratrol and resveratrol-loaded nanoparticles in protecting human lung cancer cells (A549) against hydrogen peroxide was investigated in this study. The 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) assay was performed to evaluate the antioxidant properties. Resveratrol had substantially high antioxidant capacity (trolox equivalent antioxidant capacity value) compared to trolox and vitamin E since the concentration of resveratrol was more than 50 μM. Nanoparticles prepared from β-lactoglobulin (β-lg) were successfully developed. The β-lg nanoparticle showed 60 to 146 nm diameter in size with negatively charged surface. Non-cytotoxicity was observed in Caco-2 cells treated with β-lg nanoparticles. Fluorescein isothiocynate-conjugated β-lg nanoparticles were identified into the cell membrane of Caco-2 cells, indicating that nanoparticles can be used as a delivery system. Hydrogen peroxide caused accumulation of ROS in a dose- and time-dependent manner. Resveratrol-loaded nanoparticles restored H2O2-induced ROS levels by induction of cellular uptake of resveratrol in A549 cells. Furthermore, resveratrol activated nuclear factor erythroid 2-related factor 2-Kelch ECH associating protein 1 (Nrf2-Keap1) signaling in A549 cells, thereby accumulation of Nrf2 abundance, as demonstrated by western blotting approach. Overall, these results may have implications for improvement of oxidative stress in treatment with nanoparticles as a biodegradable and non-toxic delivery carrier of bioactive compounds. PMID:26732454

  17. Antidepressant-like activity of gallic acid in mice subjected to unpredictable chronic mild stress.

    PubMed

    Chhillar, Ritu; Dhingra, Dinesh

    2013-08-01

    This study was designed to evaluate antidepressant-like activity of gallic acid in Swiss young male albino mice subjected to unpredictable chronic mild stress and to explore the possible underlying mechanisms for this activity. Gallic acid (5, 10, 20 mg/kg, i.p.) and fluoxetine (10 mg/kg, i.p.) per se were administered daily to unstressed mice and other groups of mice subjected to unpredictable mild stress, 30 min after the injection for 21 successive days. The antidepressant-like activity was evaluated using forced swim test (FST) and sucrose preference test. Stress significantly increased immobility period of mice in FST. Gallic acid (10 and 20 mg/kg, i.p.) and fluoxetine significantly decreased immobility period of unstressed and stressed mice in FST and prevented the stress-induced decrease in sucrose preference, indicating significant antidepressant-like activity. There was no significant effect on locomotor activity of the mice by the drugs. Gallic acid (10 and 20 mg/kg, i.p.) significantly decreased Monoamine oxidase-A (MAO-A) activity, malondialdehyde levels, and catalase activity in unstressed mice; and significantly prevented the stress-induced decrease in reduced glutathione and catalase activity; and also significantly prevented stress-induced increase in MAO-A activity, malondialdehyde levels, plasma nitrite, and corticosterone levels. Thus, gallic acid showed antidepressant-like activity in unstressed and stressed mice probably due to its antioxidant activity and through inhibition of MAO-A activity and decrease in plasma nitrite levels. In addition, gallic acid also showed antidepressant-like activity in stressed mice probably through decrease in plasma corticosterone levels.

  18. Chronic stress and moderate physical exercise prompt widespread common activation and limited differential activation in specific brain regions.

    PubMed

    Kim, Tae-Kyung; Han, Pyung-Lim

    2016-10-01

    Chronic stress in rodents produces depressive behaviors, whereas moderate physical exercise counteracts stress-induced depressive behaviors. Chronic stress and physical exercise appear to produce such opposing effects by changing the neural activity of specific brain regions. However, the detailed mechanisms through which the two different types of stimuli regulate brain function in opposite directions are not clearly understood. In the present study, we attempted to explore the neuroanatomical substrates mediating stress-induced behavioral changes and anti-depressant effects of exercise by examining stimulus-dependent c-Fos induction in the brains of mice that were exposed to repeated stress or exercise in a scheduled manner. Systematic and integrated analyses of c-Fos expression profiles indicated that various brain areas, including the prelimbic cortex, lateral septal area, and paraventricular nuclei of hypothalamus were commonly and strongly activated by both stress and exercise, while the lateral habenula and hippocampus were identified as being preferentially activated by stress and exercise, respectively. Exercise-dependent c-Fos expression in all regions examined in the brain occurred in both glutamatergic and GABAergic neurons. These results suggest that chronic stress and moderate exercise produce counteractive effects on mood behaviors, along with prompting widespread common activation and limited differential activation in specific brain regions. PMID:27539656

  19. Chronic stress and moderate physical exercise prompt widespread common activation and limited differential activation in specific brain regions.

    PubMed

    Kim, Tae-Kyung; Han, Pyung-Lim

    2016-10-01

    Chronic stress in rodents produces depressive behaviors, whereas moderate physical exercise counteracts stress-induced depressive behaviors. Chronic stress and physical exercise appear to produce such opposing effects by changing the neural activity of specific brain regions. However, the detailed mechanisms through which the two different types of stimuli regulate brain function in opposite directions are not clearly understood. In the present study, we attempted to explore the neuroanatomical substrates mediating stress-induced behavioral changes and anti-depressant effects of exercise by examining stimulus-dependent c-Fos induction in the brains of mice that were exposed to repeated stress or exercise in a scheduled manner. Systematic and integrated analyses of c-Fos expression profiles indicated that various brain areas, including the prelimbic cortex, lateral septal area, and paraventricular nuclei of hypothalamus were commonly and strongly activated by both stress and exercise, while the lateral habenula and hippocampus were identified as being preferentially activated by stress and exercise, respectively. Exercise-dependent c-Fos expression in all regions examined in the brain occurred in both glutamatergic and GABAergic neurons. These results suggest that chronic stress and moderate exercise produce counteractive effects on mood behaviors, along with prompting widespread common activation and limited differential activation in specific brain regions.

  20. HA95 and LAP2 beta mediate a novel chromatin-nuclear envelope interaction implicated in initiation of DNA replication.

    PubMed

    Martins, Sandra; Eikvar, Sissel; Furukawa, Kazuhiro; Collas, Philippe

    2003-01-20

    HA95 is a chromatin-associated protein that interfaces the nuclear envelope (NE) and chromatin. We report an interaction between HA95 and the inner nuclear membrane protein lamina-associated polypeptide (LAP) 2 beta, and a role of this association in initiation of DNA replication. Precipitation of GST-LAP2 beta fusion proteins and overlays of immobilized HA95 indicate that a first HA95-binding region lies within amino acids 137-242 of LAP2 beta. A second domain sufficient to bind HA95 colocalizes with the lamin B-binding domain of LAP2beta at residues 299-373. HA95-LAP2 beta interaction is not required for NE formation. However, disruption of the association of HA95 with the NH2-terminal HA95-binding domain of LAP2 beta abolishes the initiation, but not elongation, of DNA replication in purified G1 phase nuclei incubated in S-phase extract. Inhibition of replication initiation correlates with proteasome-mediated proteolysis of Cdc6, a component of the prereplication complex. Rescue of Cdc6 degradation with proteasome inhibitors restores replication. We propose that an interaction of LAP2beta, or LAP2 proteins, with HA95 is involved in the control of initiation of DNA replication. PMID:12538639

  1. CrossLaps and beta-glucuronidase in peri-implant and gingival crevicular fluid.

    PubMed

    Schubert, U; Kleber, B M; Strietzel, F P; Dörfling, P

    2001-01-01

    Collagen degradation products of the carboxyterminal region possibly reflect bone and attachment loss. In the present study, the Serum CrossLaps One-Step enzyme-linked immunosorbent assay was used to determine a specific part of the carboxyterminal region of type I collagen, the CrossLaps. Samples of peri-implant and gingival crevicular fluid of 111 implants and 53 teeth from 47 partially or completely edentulous patients were examined in reference to levels of CrossLaps and beta-glucuronidase (beta G), an established marker of periodontal disease. Clinical probing pocket depth (PPD), bleeding on probing (BOP), plaque accumulation, mobility, radiographic bone loss, and the occurrence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia were assessed. The mean values were: for PPD at implants 3.76 +/- 1.41 mm, at teeth 3.44 +/- 0.88 mm; for beta G at implants 0.364 +/- 0.392 pU/min, at teeth 0.314 +/- 0.209 pU/min; for CrossLaps at implants 0.069 +/- 0.059 pmol/min, at teeth 0.082 +/- 0.053 pmol/min. Bleeding on probing was significantly higher on implants than on teeth (McNemar test, P = .004). No significant difference of beta G levels was found between teeth and implants (Wilcoxon test). A negative correlation was found between beta G levels and CrossLaps levels at teeth (Pearson-rank correlation, P = .002). On implants, no significant correlation of these 2 parameters was seen, but significant correlations were found between sulcus fluid flow rate and PPD (P = .012), beta G levels and bone loss (P < 0.0005), and CrossLaps levels and PPD (P = .011). CrossLaps can be detected in both gingival and peri-implant crevicular fluid. While rising levels of beta G may indicate acute peri-implantitis, CrossLaps may not, but could play a role as a marker of ongoing attachment loss.

  2. Lap-belt injury with complete avulsion of the spinal cord and cauda equina.

    PubMed

    Tubbs, R Shane; Golden, Blake; Doyle, Scott; Grabb, Paul A; Oakes, W Jerry

    2006-10-01

    The authors report a child who was involved in an automobile accident. The patient was restrained by a rear seat lap belt. Radiological examination revealed an L4 Chance-type fracture and ligamentous disruption at the L4-L5 interval. During superficial dissection of the paraspinal muscles for a spinal fusion procedure, the cauda equina and the lower spinal cord (several centimeters) were visible, completely transected and herniated into the extraspinal space through a disrupted thoracolumbar fascia. The clinician should be aware of the potentially devastating results following a lap-belt injury in which a Chance fracture is produced.

  3. Non destructive evaluation of adhesively bonded carbon fiber reinforced composite lap joints with varied bond quality

    NASA Astrophysics Data System (ADS)

    Vijayakumar, R. L.; Bhat, M. R.; Murthy, C. R. L.

    2012-05-01

    Structural adhesive bonding is widely used to execute assemblies in automobile and aerospace structures. The quality and reliability of these bonded joints must be ensured during service. In this context non destructive evaluation of these bonded structures play an important role. Evaluation of adhesively bonded composite single lap shear joints has been attempted through experimental approach. Series of tests, non-destructive as well as destructive were performed on different sets of carbon fiber reinforced polymer (CFRP) composite lap joint specimens with varied bond quality. Details of the experimental investigations carried out and the outcome are presented in this paper.

  4. Role of C/EBPβ-LAP and C/EBPβ-LIP in early adipogenic differentiation of human white adipose-derived progenitors and at later stages in immature adipocytes.

    PubMed

    Lechner, Stefan; Mitterberger, Maria C; Mattesich, Monika; Zwerschke, Werner

    2013-01-01

    We investigated the role of the major isoforms of CCAAT enhancer binding protein β (C/EBPβ), C/EBPβ-LAP and C/EBPβ-LIP, in adipogenesis of human white adipose-derived stromal/progenitor cells (ASC). C/EBPβ gene expression was transiently induced early in adipogenesis. At later stages, in immature adipocytes, the C/EBPβ mRNA and protein levels declined. The C/EBPβ-LIP protein steady-state level decreased considerably stronger than the C/EBPβ-LAP level and the C/EBPβ-LIP half-life was significantly shorter than the C/EBPβ-LAP half-life. The turn-over of both C/EBPβ-isoforms was regulated by ubiquitin/proteasome-dependent degradation. These data suggest that the protein stability of the C/EBPβ-isoforms is differentially regulated in the course of adipogenesis and in immature adipocytes. Constitutive overexpression of C/EBPβ-LIP had antiadipogenic activity in human ASC. C/EBPβ-LAP, which promotes adipogenesis in mouse 3T3-L1 preadipocytes by directly activating expression of the adipogenic keyregulator PPARγ2, induced the expression of PPARγ2 and of the adipocyte differentiation gene product FABP4 in confluent ASC in the absence of adipogenic hormones. At later stages after hormone cocktail-induced adipogenesis, in immature adipocytes, constitutive overexpression of C/EBPβ-LAP led to reduced expression of PPARγ2 and FABP4, C/EBPα expression was downregulated and the expression of the adipocyte differentiation gene products adiponectin and leptin was impaired. These findings suggest that constitutive overexpression of C/EBPβ-LAP induces adipogenesis in human ASC and negatively regulates the expression of adipogenic regulators and certain adipocyte differentiation gene products in immature adipocytes. We conclude the regulation of both C/EBPβ gene expression and C/EBPβ-LIP and C/EBPβ-LAP protein turn-over plays an important role for the expression of adipogenic regulators and/or adipocyte differentiation genes in early adipogenic differentiation of

  5. Markers of oxidative stress and erythrocyte antioxidant enzyme activity in older men and women with differing physical activity.

    PubMed

    Rowiński, Rafał; Kozakiewicz, Mariusz; Kędziora-Kornatowska, Kornelia; Hübner-Woźniak, Elżbieta; Kędziora, Józef

    2013-11-01

    The aim of the present study was to examine the relationship between markers of oxidative stress and erythrocyte antioxidant enzyme activity and physical activity in older men and women. The present study included 481 participants (233 men and 248 women) in the age group 65-69 years (127 men and 125 women) and in the age group 90 years and over (106 men and 123 women). The classification of respondents by physical activity was based on answers to the question if, in the past 12 months, they engaged in any pastimes which require physical activity. The systemic oxidative stress status was assessed by measuring plasma iso-PGF2α and protein carbonyl concentration as well as erythrocyte antioxidant enzymes activity, i.e., superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR). The concentration of plasma iso-PGF2α and protein carbonyls (CP) was lower in groups of younger men and women compared to the respective older groups. In all examined groups, physical activity resulted in decrease of these oxidative stress markers and simultaneously caused adaptive increase in the erythrocyte SOD activity. Additionally, in active younger men CAT, GPx, and GR activities were higher than in sedentary ones. In conclusion, oxidative stress increase is age-related, but physical activity can reduce oxidative stress markers and induce adaptive increase in the erythrocyte antioxidant enzyme activity, especially SOD, even in old and very old men and women.

  6. Dynamics of locomotor activity and heat production in rats after acute stress.

    PubMed

    Pertsov, S S; Alekseeva, I V; Koplik, E V; Sharanova, N E; Kirbaeva, N V; Gapparov, M M G

    2014-05-01

    The dynamics of locomotor activity and heat production were studied in rats demonstrating passive and active behavior in the open field test at different time after exposure to acute emotional stress caused by 12-h immobilization during dark hours. The most pronounced changes in behavior and heat production followed by disturbances in circadian rhythms of these parameters were detected within the first 2 days after stress. In contrast to behaviorally active rats, the most significant decrease in locomotor activity and heat production of passive animals subjected to emotional stress was observed during dark hours. Circadian rhythms of behavior and heat production in rats tended to recover on day 3 after immobilization stress. These data illustrate the specificity of metabolic and behavioral changes reflecting the shift of endogenous biological rhythms in individuals with different prognostic resistance to stress at different terms after exposure to negative emotiogenic stimuli. PMID:24906959

  7. Parenting Stress After Deployment in Navy Active Duty Fathers.

    PubMed

    Yablonsky, Abigail M; Yan, Guofen; Bullock, Linda

    2016-08-01

    Military fathers are being deployed, and leaving their families, for greater lengths of time and more frequently than ever before. The purpose of this study was to examine the impact of recent deployment on parenting stress in U.S. Navy fathers with young children. Of the 111 participants who completed the one-time study questionnaire at a large military outpatient clinic on the Eastern seaboard, 67.6% had returned from a ship-based deployment. Regression analyses were performed, using the Parenting Stress Index as the outcome variable, deployment elements (such as time away from home in the past 5 years) as predictors, and adjusting for other factors such as post-traumatic stress disorder (PTSD) and depression. Higher perceived threat and greater warfare exposure were both associated with increased parenting stress (p < 0.05) in the unadjusted model. These associations were greatly attenuated and no longer significant after adjustment for depression. In addition, rates of positive screens for PTSD and depression (17.1%) in this sample were higher than in other recent studies. In summary, these data indicate that various deployment factors are associated with increased parenting stress in Navy fathers back from deployment within the past year; these relationships are largely explained by depressive symptoms. Clinical implications are discussed. PMID:27483524

  8. Nature of stress: differential effects on brain acetylcholinesterase activity and memory in rats.

    PubMed

    Das, Amitava; Rai, Deepak; Dikshit, Madhu; Palit, Gautam; Nath, Chandishwar

    2005-09-16

    Effect of acute, chronic-predictable and chronic-unpredictable stress on memory and acetylcholinesterase (AChE) was investigated in rats. The animals were subjected to 3 type of stressors--(1) acute immobilization stress, (2) chronic-predictable stress i.e., immobilization daily for 5 consecutive days and (3) chronic-unpredictable stress that included reversal of light/dark cycle, over-night fasting, forced-swimming, immobilization and forced exercise in random unpredictable manner daily for 5 consecutive days. Learning and memory function was studied by single trial Passive avoidance test. AChE activity was assayed spectrophotometrically in the detergent (DS) and salt (SS) soluble fractions in different brain regions. Learning was obtained in acute and chronic-predictable stress groups but not in chronic-unpredictable group. Acute, chronic-predictable and chronic-unpredictable stress caused significant decrease in AChE activity in the DS fraction of cortex, hippocampus and hypothalamus as compared to control. Results indicate that AChE in DS fraction is predominantly affected in stressed and stressed-trained group but cognition is affected only by chronic-unpredictable stress. In acute and chronic-predictable groups the decreased AChE activity in the hippocampal DS fraction during learning may be responsible to maintain cognitive function by enhancing the cholinergic activity.

  9. Composite-to-metal tubular lap joints: Strength and fatigue resistance

    NASA Astrophysics Data System (ADS)

    Reedy, E. D., Jr.; Guess, T. R.

    1993-10-01

    The axial strength and fatigue resistance of thick-walled, adhesively bonded E-glass composite-to-aluminum tubular lap joints have been measured for tensile and compressive loadings. The joint specimen bonds a 63 mm OD aluminum tube within each end of a 300 mm long, 6 mm thick E-glass/epoxy tube. Untapered, 12.5 mm thick aluminum adherends were used in all but four of the joint specimens. The aluminum adherends in the remaining four specimens were tapered to a thickness of 1 mm at the inner bond end (the bond end where the aluminum adherend terminates). For all loadings, joint failure initiates at the inner bond end as a crack grows in the adhesive adjacent to the interface. Test results for a tension-tension fatigue loading indicate that fatigue can severely degrade joint performance. Interestingly, measured tensile strength and fatigue resistance for joints with untapered adherends is substantially greater than compressive strength and fatigue resistance. The joint specimen has been analyzed in two different ways: one approach models the adhesive as an uncracked, elastic-perfectly plastic material, while the other approach uses a linear elastic fracture mechanics methodology. Results for the uncracked, elastic-plastic adhesive model indicate that observed bond failure occurs in the region of highest calculated stresses, extensive bond yielding occurs at load levels well below that required to fail the joint, and a tensile peel stress is generated by a compressive joint loading when the aluminum adherends are untapered. This latter result is consistent with the observed joint tensile-compressive strength differential. Results of the linear elastic fracture mechanics analysis of a joint with untapered aluminum adherends are also consistent with the observed differential strength effect since a mode 1 crack loading is predicted for a compressive joint loading. Calculations and a limited number of tests suggest that it may be possible to selectively control the

  10. Acute stress-induced cortisol elevations mediate reward system activity during subconscious processing of sexual stimuli.

    PubMed

    Oei, Nicole Y L; Both, Stephanie; van Heemst, Diana; van der Grond, Jeroen

    2014-01-01

    Stress is thought to alter motivational processes by increasing dopamine (DA) secretion in the brain's "reward system", and its key region, the nucleus accumbens (NAcc). However, stress studies using functional magnetic resonance imaging (fMRI), mainly found evidence for stress-induced decreases in NAcc responsiveness toward reward cues. Results from both animal and human PET studies indicate that the stress hormone cortisol may be crucial in the interaction between stress and dopaminergic actions. In the present study we therefore investigated whether cortisol mediated the effect of stress on DA-related responses to -subliminal-presentation of reward cues using the Trier Social Stress Test (TSST), which is known to reliably enhance cortisol levels. Young healthy males (n = 37) were randomly assigned to the TSST or control condition. After stress induction, brain activation was assessed using fMRI during a backward-masking paradigm in which potentially rewarding (sexual), emotionally negative and neutral stimuli were presented subliminally, masked by pictures of inanimate objects. A region of interest analysis showed that stress decreased activation in the NAcc in response to masked sexual cues (voxel-corrected, p<05). Furthermore, with mediation analysis it was found that high cortisol levels were related to stronger NAcc activation, showing that cortisol acted as a suppressor variable in the negative relation between stress and NAcc activation. The present findings indicate that cortisol is crucially involved in the relation between stress and the responsiveness of the reward system. Although generally stress decreases activation in the NAcc in response to rewarding stimuli, high stress-induced cortisol levels suppress this relation, and are associated with stronger NAcc activation. Individuals with a high cortisol response to stress might on one hand be protected against reductions in reward sensitivity, which has been linked to anhedonia and depression, but

  11. Acute stress-induced cortisol elevations mediate reward system activity during subconscious processing of sexual stimuli.

    PubMed

    Oei, Nicole Y L; Both, Stephanie; van Heemst, Diana; van der Grond, Jeroen

    2014-01-01

    Stress is thought to alter motivational processes by increasing dopamine (DA) secretion in the brain's "reward system", and its key region, the nucleus accumbens (NAcc). However, stress studies using functional magnetic resonance imaging (fMRI), mainly found evidence for stress-induced decreases in NAcc responsiveness toward reward cues. Results from both animal and human PET studies indicate that the stress hormone cortisol may be crucial in the interaction between stress and dopaminergic actions. In the present study we therefore investigated whether cortisol mediated the effect of stress on DA-related responses to -subliminal-presentation of reward cues using the Trier Social Stress Test (TSST), which is known to reliably enhance cortisol levels. Young healthy males (n = 37) were randomly assigned to the TSST or control condition. After stress induction, brain activation was assessed using fMRI during a backward-masking paradigm in which potentially rewarding (sexual), emotionally negative and neutral stimuli were presented subliminally, masked by pictures of inanimate objects. A region of interest analysis showed that stress decreased activation in the NAcc in response to masked sexual cues (voxel-corrected, p<05). Furthermore, with mediation analysis it was found that high cortisol levels were related to stronger NAcc activation, showing that cortisol acted as a suppressor variable in the negative relation between stress and NAcc activation. The present findings indicate that cortisol is crucially involved in the relation between stress and the responsiveness of the reward system. Although generally stress decreases activation in the NAcc in response to rewarding stimuli, high stress-induced cortisol levels suppress this relation, and are associated with stronger NAcc activation. Individuals with a high cortisol response to stress might on one hand be protected against reductions in reward sensitivity, which has been linked to anhedonia and depression, but

  12. Estradiol levels modulate brain activity and negative responses to psychosocial stress across the menstrual cycle.

    PubMed

    Albert, Kimberly; Pruessner, Jens; Newhouse, Paul

    2015-09-01

    Although ovarian hormones are thought to have a potential role in the well-known sex difference in mood and anxiety disorders, the mechanisms through which ovarian hormone changes contribute to stress regulation are not well understood. One mechanism by which ovarian hormones might impact mood regulation is by mediating the effect of psychosocial stress, which often precedes depressive episodes and may have mood consequences that are particularly relevant in women. In the current study, brain activity and mood response to psychosocial stress was examined in healthy, normally cycling women at either the high or low estradiol phase of the menstrual cycle. Twenty eight women were exposed to the Montreal Imaging Stress Task (MIST), with brain activity determined through functional magnetic resonance imaging, and behavioral response assessed with subjective mood and stress measures. Brain activity responses to psychosocial stress differed between women in the low versus high estrogen phase of the menstrual cycle: women with high estradiol levels showed significantly less deactivation in limbic regions during psychosocial stress compared to women with low estradiol levels. Additionally, women with higher estradiol levels also had less subjective distress in response to the MIST than women with lower estradiol levels. The results of this study suggest that, in normally cycling premenopausal women, high estradiol levels attenuate the brain activation changes and negative mood response to psychosocial stress. Normal ovarian hormone fluctuations may alter the impact of psychosocially stressful events by presenting periods of increased vulnerability to psychosocial stress during low estradiol phases of the menstrual cycle. This menstrual cycle-related fluctuation in stress vulnerability may be relevant to the greater risk for affective disorder or post-traumatic stress disorder in women.

  13. Diazepam blocks striatal lipid peroxidation and improves stereotyped activity in a rat model of acute stress.

    PubMed

    Méndez-Cuesta, Luis A; Márquez-Valadez, Berenice; Pérez-De La Cruz, Verónica; Escobar-Briones, Carolina; Galván-Arzate, Sonia; Alvarez-Ruiz, Yarummy; Maldonado, Perla D; Santana, Ricardo A; Santamaría, Abel; Carrillo-Mora, Paul

    2011-11-01

    In this work, the effect of a single dose of diazepam was tested on different markers of oxidative damage in the striatum of rats in an acute model of immobilization (restraint) stress. In addition, the locomotor activity was measured at the end of the restraint period. Immobilization was induced to animals for 24 hr, and then, lipid peroxidation, superoxide dismutase activity and content, and mitochondrial function were all estimated in striatal tissue samples. Corticosterone levels were measured in serum. Diazepam was given to rats as a pre-treatment (1 mg/kg, i.p.) 20 min. before the initiation of stress. Our results indicate that acute stress produced enhanced striatal levels of lipid peroxidation (73% above the control), decreased superoxide dismutase activity (54% below the control), reduced levels of mitochondrial function (35% below the control) and increased corticosterone serum levels (86% above the control). Pre-treatment of stressed rats with diazepam decreased the striatal lipid peroxidation levels (68% below the stress group) and improved mitochondrial function (18% above the stress group), but only mild preservation of superoxide dismutase activity was detected (17% above the stress group). In regard to the motor assessment, only the stereotyped activity was increased in the stress group with respect to control (46% above the control), and this effect was prevented by diazepam administration (30% below the stress group). The preventive actions of diazepam in this acute model of stress suggest that drugs exhibiting anxiolytic and antioxidant properties might be useful for the design of therapies against early acute phases of physic stress.

  14. Increased oxidative stress in pemphigus vulgaris is related to disease activity and HLA-association.

    PubMed

    Shah, Amit Aakash; Dey-Rao, Rama; Seiffert-Sinha, Kristina; Sinha, Animesh A

    2016-06-01

    Pemphigus vulgaris (PV) is a rare blistering skin disorder characterized by the disadhesion of keratinocytes due to autoantibody attack against epidermal targets including desmoglein (Dsg) 3, Dsg 1 and possibly other adhesion and non-adhesion molecules. The mechanisms leading to immune-mediated pathology in PV are multifactorial and not fully understood. Recently, oxidative stress (antioxidant/oxidant disequilibrium) has been proposed as a contributory mechanism of autoimmune skin diseases, including PV. In this study, we directly assessed oxidative stress via measurement of total antioxidant capacity (TAC) using ELISA in 47 PV patients, 25 healthy controls and 18 bullous pemphigoid (BP) patients. We also performed microarray gene expression analysis on a separate set of 21 PV patients and 10 healthy controls to evaluate transcriptional dysregulation in oxidative stress-related pathways. Our data indicate that there is a significant reduction in TAC levels in PV patients compared with healthy controls, as well as BP patients. Furthermore, PV patients with active disease have significantly lower TAC levels than PV patients in remission. We also find that HLA allele status has a significant influence on oxidative stress. These findings are corroborated by microarray analysis showing differentially expressed genes involved in oxidative stress between the aforementioned groups. Collectively, our findings provide support for a role of oxidative stress in PV. Whether increased oxidative stress leads to disease manifestation and/or activity, or if disease activity leads to increased oxidative stress remains unknown. Future longitudinal studies may help to further elucidate the relationship between PV and oxidative stress.

  15. Acute stress differentially affects aromatase activity in specific brain nuclei of adult male and female quail.

    PubMed

    Dickens, Molly J; Cornil, Charlotte A; Balthazart, Jacques

    2011-11-01

    The rapid and temporary suppression of reproductive behavior is often assumed to be an important feature of the adaptive acute stress response. However, how this suppression operates at the mechanistic level is poorly understood. The enzyme aromatase converts testosterone to estradiol in the brain to activate reproductive behavior in male Japanese quail (Coturnix japonica). The discovery of rapid and reversible modification of aromatase activity (AA) provides a potential mechanism for fast, stress-induced changes in behavior. We investigated the effects of acute stress on AA in both sexes by measuring enzyme activity in all aromatase-expressing brain nuclei before, during, and after 30 min of acute restraint stress. We show here that acute stress rapidly alters AA in the male and female brain and that these changes are specific to the brain nuclei and sex of the individual. Specifically, acute stress rapidly (5 min) increased AA in the male medial preoptic nucleus, a region controlling male reproductive behavior; in females, a similar increase was also observed, but it appeared delayed (15 min) and had smaller amplitude. In the ventromedial and tuberal hypothalamus, regions associated with female reproductive behavior, stress induced a quick and sustained decrease in AA in females, but in males, only a slight increase (ventromedial) or no change (tuberal) in AA was observed. Effects of acute stress on brain estrogen production, therefore, represent one potential way through which stress affects reproduction.

  16. Mechanisms of Discoordination of Contractile Activity in the Gastroduodenal Zone during Psychogenic Stress in Rabbits.

    PubMed

    Ovsyannikov, V I; Berezina, T P; Shemerovskii, K A

    2015-08-01

    Inhibition of the contractile activity of the stomach induced by psychogenic stress persisted after blockade of muscarinic and nicotinic cholinergic receptors and α2 and β1/β2-adrenergic receptors. Stress-induced increase in contractile activity in the proximal part of the duodenum persisted during blockade of muscarinic and nicotinic cholinergic receptors, β1/β2-adrenergic receptors. At the same time, blockade of the above cholinergic and adrenergic receptors eliminated the stress-induced increase in contractive activity in the distal part of the duodenum.

  17. Progerin reduces LAP2α-telomere association in Hutchinson-Gilford progeria

    PubMed Central

    Chojnowski, Alexandre; Ong, Peh Fern; Wong, Esther SM; Lim, John SY; Mutalif, Rafidah A; Navasankari, Raju; Dutta, Bamaprasad; Yang, Henry; Liow, Yi Y; Sze, Siu K; Boudier, Thomas; Wright, Graham D; Colman, Alan; Burke, Brian; Stewart, Colin L; Dreesen, Oliver

    2015-01-01

    Hutchinson-Gilford progeria (HGPS) is a premature ageing syndrome caused by a mutation in LMNA, resulting in a truncated form of lamin A called progerin. Progerin triggers loss of the heterochromatic marker H3K27me3, and premature senescence, which is prevented by telomerase. However, the mechanism how progerin causes disease remains unclear. Here, we describe an inducible cellular system to model HGPS and find that LAP2α (lamina-associated polypeptide-α) interacts with lamin A, while its interaction with progerin is significantly reduced. Super-resolution microscopy revealed that over 50% of telomeres localize to the lamina and that LAP2α association with telomeres is impaired in HGPS. This impaired interaction is central to HGPS since increasing LAP2α levels rescues progerin-induced proliferation defects and loss of H3K27me3, whereas lowering LAP2 levels exacerbates progerin-induced defects. These findings provide novel insights into the pathophysiology underlying HGPS, and how the nuclear lamina regulates proliferation and chromatin organization. DOI: http://dx.doi.org/10.7554/eLife.07759.001 PMID:26312502

  18. Progerin reduces LAP2α-telomere association in Hutchinson-Gilford progeria.

    PubMed

    Chojnowski, Alexandre; Ong, Peh Fern; Wong, Esther S M; Lim, John S Y; Mutalif, Rafidah A; Navasankari, Raju; Dutta, Bamaprasad; Yang, Henry; Liow, Yi Y; Sze, Siu K; Boudier, Thomas; Wright, Graham D; Colman, Alan; Burke, Brian; Stewart, Colin L; Dreesen, Oliver

    2015-08-27

    Hutchinson-Gilford progeria (HGPS) is a premature ageing syndrome caused by a mutation in LMNA, resulting in a truncated form of lamin A called progerin. Progerin triggers loss of the heterochromatic marker H3K27me3, and premature senescence, which is prevented by telomerase. However, the mechanism how progerin causes disease remains unclear. Here, we describe an inducible cellular system to model HGPS and find that LAP2α (lamina-associated polypeptide-α) interacts with lamin A, while its interaction with progerin is significantly reduced. Super-resolution microscopy revealed that over 50% of telomeres localize to the lamina and that LAP2α association with telomeres is impaired in HGPS. This impaired interaction is central to HGPS since increasing LAP2α levels rescues progerin-induced proliferation defects and loss of H3K27me3, whereas lowering LAP2 levels exacerbates progerin-induced defects. These findings provide novel insights into the pathophysiology underlying HGPS, and how the nuclear lamina regulates proliferation and chromatin organization.

  19. Design Considerations of Polishing Lap for Computer-Controlled Cylindrical Polishing Process

    NASA Technical Reports Server (NTRS)

    Khan, Gufran S.; Gubarev, Mikhail; Arnold, William; Ramsey, Brian D.

    2009-01-01

    This paper establishes a relationship between the polishing process parameters and the generation of mid spatial-frequency error. The consideration of the polishing lap design to optimize the process in order to keep residual errors to a minimum and optimization of the process (speeds, stroke, etc.) and to keep the residual mid spatial-frequency error to a minimum, is also presented.

  20. 77 FR 27746 - Notice of Submission for OMB Review; Federal Student Aid; Lender Application Process (LAP)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-11

    ... special allowance, as well as Federal Insured Student Loan claims payment, under the Federal Family Education Loan Program. DATES: Interested persons are invited to submit comments on or before June 11, 2012... Notice of Submission for OMB Review; Federal Student Aid; Lender Application Process (LAP) SUMMARY:...

  1. Correlates of Mood and RPE During Multi-Lap Off-Road Cycling.

    PubMed

    Viana, Bruno Ferreira; Pires, Flávio Oliveira; Inoue, Allan; Micklewright, Dominic; Santos, Tony Meireles

    2016-03-01

    This study examined the relationship between mood and rating of perceived exertion (RPE) during a simulated multiple-lap time trial (MLTT). Nineteen male cyclists performed a MLTT consisting of four 9.9 km laps, each lap with a gradient ranging from 0 to 10 %. Mood as measured by the Profile of Mood States Questionnaire (POMS) and perceived exertion as measured by the Borg CR100 scale (RPE) were obtained at the end of each lap. A categorical multiple regressive model, having median of POMS subscales as independent variables, was obtained to explain the variance in median RPE responses. Increases in POMS fatigue scores and decreases in POMS vigour scores were observed throughout the MLTT (P < 0.001). A linear increase in RPE during the MLTT was also observed (P < 0.001). POMS fatigue subscale scores accounted for 88 % of the variance in RPE during the MLTT (R(2) = 0.88, P = 0.002), and no other POMS subscale improved the final predictive model. With the exception of fatigue these results suggest that most aspects of mood do not have a discernable effect on RPE during a MLTT. The rate of increase in RPE can predict the MLTT endpoint.

  2. Determination of Arsenic Poisoning and Metabolism in Hair by Synchrotron Radiation: The Case of Phar Lap

    SciTech Connect

    Kempson, Ivan M.; Henry, Dermot A.

    2010-08-26

    Fresh physical evidence about the demise of the racehorse Phar Lap (see photograph) has been gathered from the study of mane hair samples by synchrotron radiation analysis with high resolution X-ray fluorescence (XRF) and X-ray absorption near edge structure (XANES) analyses. The results are indicative of arsenic ingestion and metabolism, and show that the racing champion died from arsenic poisoning.

  3. Improving Critical Thinking Skills Using Learning Model Logan Avenue Problem Solving (LAPS)-Heuristic

    ERIC Educational Resources Information Center

    Anggrianto, Desi; Churiyah, Madziatul; Arief, Mohammad

    2016-01-01

    This research was conducted in order to know the effect of Logan Avenue Problem Solving (LAPS)-Heuristic learning model towards critical thinking skills of students of class X Office Administration (APK) in SMK Negeri 1 Ngawi, East Java, Indonesia on material curve and equilibrium of demand and supply, subject Introduction to Economics and…

  4. The impact of layer thickness on the performance of additively manufactured lapping tools

    NASA Astrophysics Data System (ADS)

    Williams, Wesley B.

    2015-10-01

    Lower cost additive manufacturing (AM) machines which have emerged in recent years are capable of producing tools, jigs, and fixtures that are useful in optical fabrication. In particular, AM tooling has been shown to be useful in lapping glass workpieces. Various AM machines are distinguished by the processes, materials, build times, and build resolution they provide. This research investigates the impact of varied build resolution (specifically layer resolution) on the lapping performance of tools built using the stereolithographic assembly (SLA) process in 50 μm and 100 μm layer thicknesses with a methacrylate photopolymer resin on a high resolution desktop printer. As with previous work, the lapping tools were shown to remove workpiece material during the lapping process, but the tools themselves also experienced significant wear on the order of 2-3 times the mass loss of the glass workpieces. The tool wear rates for the 100 μm and 50 μm layer tools were comparable, but the 50 μm layer tool was 74% more effective at removing material from the glass workpiece, which is attributed to some abrasive particles being trapped in the coarser surface of the 100 um layer tooling and not being available to interact with the glass workpiece. Considering the tool wear, these additively manufactured tools are most appropriate for prototype tooling where the low cost (<$45) and quick turnaround make them attractive when compared to a machined tool.

  5. Voluntary locomotor activity mitigates oxidative damage associated with isolation stress in the prairie vole (Microtus ochrogaster)

    PubMed Central

    Fletcher, Kelsey L.; Whitley, Brittany N.; Treidel, Lisa A.; Thompson, David; Williams, Annie; Noguera, Jose C.; Stevenson, Jennie R.; Haussmann, Mark F.

    2015-01-01

    Organismal performance directly depends on an individual's ability to cope with a wide array of physiological challenges. For social animals, social isolation is a stressor that has been shown to increase oxidative stress. Another physiological challenge, routine locomotor activity, has been found to decrease oxidative stress levels. Because we currently do not have a good understanding of how diverse physiological systems like stress and locomotion interact to affect oxidative balance, we studied this interaction in the prairie vole (Microtus ochrogaster). Voles were either pair housed or isolated and within the isolation group, voles either had access to a moving wheel or a stationary wheel. We found that chronic periodic isolation caused increased levels of oxidative stress. However, within the vole group that was able to run voluntarily, longer durations of locomotor activity were associated with less oxidative stress. Our work suggests that individuals who demonstrate increased locomotor activity may be better able to cope with the social stressor of isolation. PMID:26179798

  6. Voluntary locomotor activity mitigates oxidative damage associated with isolation stress in the prairie vole (Microtus ochrogaster).

    PubMed

    Fletcher, Kelsey L; Whitley, Brittany N; Treidel, Lisa A; Thompson, David; Williams, Annie; Noguera, Jose C; Stevenson, Jennie R; Haussmann, Mark F

    2015-07-01

    Organismal performance directly depends on an individual's ability to cope with a wide array of physiological challenges. For social animals, social isolation is a stressor that has been shown to increase oxidative stress. Another physiological challenge, routine locomotor activity, has been found to decrease oxidative stress levels. Because we currently do not have a good understanding of how diverse physiological systems like stress and locomotion interact to affect oxidative balance, we studied this interaction in the prairie vole (Microtus ochrogaster). Voles were either pair housed or isolated and within the isolation group, voles either had access to a moving wheel or a stationary wheel. We found that chronic periodic isolation caused increased levels of oxidative stress. However, within the vole group that was able to run voluntarily, longer durations of locomotor activity were associated with less oxidative stress. Our work suggests that individuals who demonstrate increased locomotor activity may be better able to cope with the social stressor of isolation.

  7. Voluntary locomotor activity mitigates oxidative damage associated with isolation stress in the prairie vole (Microtus ochrogaster).

    PubMed

    Fletcher, Kelsey L; Whitley, Brittany N; Treidel, Lisa A; Thompson, David; Williams, Annie; Noguera, Jose C; Stevenson, Jennie R; Haussmann, Mark F

    2015-07-01

    Organismal performance directly depends on an individual's ability to cope with a wide array of physiological challenges. For social animals, social isolation is a stressor that has been shown to increase oxidative stress. Another physiological challenge, routine locomotor activity, has been found to decrease oxidative stress levels. Because we currently do not have a good understanding of how diverse physiological systems like stress and locomotion interact to affect oxidative balance, we studied this interaction in the prairie vole (Microtus ochrogaster). Voles were either pair housed or isolated and within the isolation group, voles either had access to a moving wheel or a stationary wheel. We found that chronic periodic isolation caused increased levels of oxidative stress. However, within the vole group that was able to run voluntarily, longer durations of locomotor activity were associated with less oxidative stress. Our work suggests that individuals who demonstrate increased locomotor activity may be better able to cope with the social stressor of isolation. PMID:26179798

  8. Hypoplastic basement membrane of the lens anlage in the inheritable lens aplastic mouse (lap mouse).

    PubMed

    Aso, S; Baba, R; Noda, S; Ikuno, S; Fujita, M

    2000-04-01

    Adult homozygous lap mice show various eye abnormalities such as aphakia, retinal disorganization, and dysplasia of the cornea and anterior chamber. In the fetal eye of a homozygous lap mouse, the lens placode appears to develop normally. However, the lens vesicle develops abnormally to form a mass of cells without a cavity, and the mass vanishes soon afterward. Apoptotic cell death is associated with the disappearance of the lens anlage. We examined the basement membranes of the lens anlage of this mutant by immunohistochemical methods under light microscopy using antibodies against basement membrane components of the lens anlage, type IV collagen, fibronectin, laminin, heparan sulfate proteoglycan, and entactin and by transmission electron microscopy. Immunohistochemistry showed the distribution and intensity of antibody binding to the lens anlage to be almost the same for each these antibodies regardless of the stage of gestation or whether the anlagen were from normal BALB/c or lap mice. Thus, positive continuous reactions were observed around the exterior region of the lens anlage from day 10 of gestation for type IV collagen, fibronectin, laminin, heparan sulfate proteoglycan antibodies, and at least from day 11of gestation for entactin antibody. The basement membrane lamina densa of both normal and lap mice was shown by electron microscopy to be discontinuous at days 10 and 10.5 of gestation. However, by day 11 the lamina densa was continuous in the lens anlagen of normal mice but still discontinuous in the lap mice. By day 12 of gestation, the lamina densa had thickened markedly in normal mice, whereas in lap mice it remained discontinuous and its thinness indicated hypoplasia. These results indicate that, while all basement components examined are produced and deposited in the normal region of the lens anlage in the lap mouse, the basement membrane is, for some reason, imperfectly formed. The time at which hypoplasia of the basement membrane was observed

  9. The mechanisms of up-regulation of dendritic cell activity by oxidative stress.

    PubMed

    Batal, Ibrahim; Azzi, Jamil; Mounayar, Marwan; Abdoli, Rozita; Moore, Robert; Lee, Jack Y; Rosetti, Florencia; Wang, Chang; Fiorina, Paolo; Sackstein, Robert; Ichimura, Takaharu; Abdi, Reza

    2014-08-01

    Whereas DC have increasingly been recognized for their role in activating the inflammatory cascades during IRIs, the mechanisms by which oxidative stress enhances DC activation remain to be explored. We examined the role of oxidative stress on two important features of DC: T cell activation and trafficking. Bone marrow-derived OS-DC were compared with untreated DC. DC exposed to oxidative stress augmented allogeneic T cell proliferation and showed increased migration in a chemotaxis chamber. These results were confirmed by using hypoxanthine and xanthine oxidase as another inducer of oxidative stress. We used OT-II and OT-I mice to assess the effect of oxidative stress on DC activation of OVA-specific CD4(+) and CD8(+) T cells, respectively. Oxidative stress increased DC capacity to promote OVA-specific CD4(+) T cell activity, demonstrated by an increase in their proliferation and production of IFN-γ, IL-6, and IL-2 proinflammatory cytokines. Whereas oxidative stress increased the DC ability to stimulate IFN-γ production by OVA-specific CD8(+) T cells, cellular proliferation and cytotoxicity were not affected. Compared with untreated DC, oxidative stress significantly reduced the capacity of DC to generate T(regs), which were restored by using anti-IL-6. With regard to DC trafficking, whereas oxidative stress increased DC expression of p-Akt and p-NF-κB, targeting PI3Kγ and NF-κB pathways abrogated the observed increase in DC migration. Our data propose novel insights on the activation of DC by oxidative stress and provide rationales for targeted therapies, which can potentially attenuate IRI.

  10. The mechanisms of up-regulation of dendritic cell activity by oxidative stress

    PubMed Central

    Batal, Ibrahim; Azzi, Jamil; Mounayar, Marwan; Abdoli, Rozita; Moore, Robert; Lee, Jack Y.; Rosetti, Florencia; Wang, Chang; Fiorina, Paolo; Sackstein, Robert; Ichimura, Takaharu; Abdi, Reza

    2014-01-01

    Whereas DC have increasingly been recognized for their role in activating the inflammatory cascades during IRIs, the mechanisms by which oxidative stress enhances DC activation remain to be explored. We examined the role of oxidative stress on two important features of DC: T cell activation and trafficking. Bone marrow-derived OS-DC were compared with untreated DC. DC exposed to oxidative stress augmented allogeneic T cell proliferation and showed increased migration in a chemotaxis chamber. These results were confirmed by using hypoxanthine and xanthine oxidase as another inducer of oxidative stress. We used OT-II and OT-I mice to assess the effect of oxidative stress on DC activation of OVA-specific CD4+ and CD8+ T cells, respectively. Oxidative stress increased DC capacity to promote OVA-specific CD4+ T cell activity, demonstrated by an increase in their proliferation and production of IFN-γ, IL-6, and IL-2 proinflammatory cytokines. Whereas oxidative stress increased the DC ability to stimulate IFN-γ production by OVA-specific CD8+ T cells, cellular proliferation and cytotoxicity were not affected. Compared with untreated DC, oxidative stress significantly reduced the capacity of DC to generate Tregs, which were restored by using anti-IL-6. With regard to DC trafficking, whereas oxidative stress increased DC expression of p-Akt and p-NF-κB, targeting PI3Kγ and NF-κB pathways abrogated the observed increase in DC migration. Our data propose novel insights on the activation of DC by oxidative stress and provide rationales for targeted therapies, which can potentially attenuate IRI. PMID:24676276

  11. Salidroside Suppresses HUVECs Cell Injury Induced by Oxidative Stress through Activating the Nrf2 Signaling Pathway.

    PubMed

    Zhu, Yao; Zhang, Ya-Jie; Liu, Wei-Wei; Shi, Ai-Wu; Gu, Ning

    2016-01-01

    Oxidative stress plays an important role in the pathogenesis of cardiovascular diseases. Salidroside (SAL), one of the main effective constituents of Rhodiola rosea, has been reported to suppress oxidative stress-induced cardiomyocyte injury and necrosis by promoting transcription of nuclear factor E2-related factor 2 (Nrf2)-regulated genes such as heme oxygenase-1 (HO-1) and NAD(P)H dehydrogenase (quinone1) (NQO1). However, it has not been indicated whether SAL might ameliorate endothelial injury induced by oxidative stress. Here, our study demonstrated that SAL might suppress HUVEC cell injury induced by oxidative stress through activating the Nrf2 signaling pathway. The results of our study indicated that SAL decreased the levels of intercellular reactive oxygen species (ROS) and malondialdehyde (MDA), and improved the activities of superoxide dismutase (SOD) and catalase (CAT), resulting in protective effects against oxidative stress-induced cell damage in HUVECs. It suppressed oxidative stress damage by inducing Nrf2 nuclear translocation and activating the expression of Nrf2-regulated antioxidant enzyme genes such as HO-1 and NQO1 in HUVECs. Knockdown of Nrf2 with siRNA abolished the cytoprotective effects against oxidative stress, decreased the expression of Nrf2, HO-1, and NQO1, and inhibited the nucleus translocation of Nrf2 in HUVECs. This study is the first to demonstrate that SAL suppresses HUVECs cell injury induced by oxidative stress through activating the Nrf2 signaling pathway. PMID:27517893

  12. Salidroside Suppresses HUVECs Cell Injury Induced by Oxidative Stress through Activating the Nrf2 Signaling Pathway.

    PubMed

    Zhu, Yao; Zhang, Ya-Jie; Liu, Wei-Wei; Shi, Ai-Wu; Gu, Ning

    2016-01-01

    Oxidative stress plays an important role in the pathogenesis of cardiovascular diseases. Salidroside (SAL), one of the main effective constituents of Rhodiola rosea, has been reported to suppress oxidative stress-induced cardiomyocyte injury and necrosis by promoting transcription of nuclear factor E2-related factor 2 (Nrf2)-regulated genes such as heme oxygenase-1 (HO-1) and NAD(P)H dehydrogenase (quinone1) (NQO1). However, it has not been indicated whether SAL might ameliorate endothelial injury induced by oxidative stress. Here, our study demonstrated that SAL might suppress HUVEC cell injury induced by oxidative stress through activating the Nrf2 signaling pathway. The results of our study indicated that SAL decreased the levels of intercellular reactive oxygen species (ROS) and malondialdehyde (MDA), and improved the activities of superoxide dismutase (SOD) and catalase (CAT), resulting in protective effects against oxidative stress-induced cell damage in HUVECs. It suppressed oxidative stress damage by inducing Nrf2 nuclear translocation and activating the expression of Nrf2-regulated antioxidant enzyme genes such as HO-1 and NQO1 in HUVECs. Knockdown of Nrf2 with siRNA abolished the cytoprotective effects against oxidative stress, decreased the expression of Nrf2, HO-1, and NQO1, and inhibited the nucleus translocation of Nrf2 in HUVECs. This study is the first to demonstrate that SAL suppresses HUVECs cell injury induced by oxidative stress through activating the Nrf2 signaling pathway.

  13. Differential effects of mental concentration and acute psychosocial stress on cervical muscle activity and posture.

    PubMed

    Shahidi, Bahar; Haight, Ashley; Maluf, Katrina

    2013-10-01

    Physical and psychosocial stressors in the workplace have been independently associated with the development of neck pain, yet interactions among these risk factors remain unclear. The purpose of this study was to compare the effects of mentally challenging computer work performed with and without exposure to a psychosocial stressor on cervical muscle activity and posture. Changes in cervical posture and electromyography of upper trapezius, cervical extensor, and sternocleidomastoid muscles were compared between a resting seated posture at baseline, a low stress condition with mental concentration, and a high stress condition with mental concentration and psychosocial stress in sixty healthy office workers. Forward head posture significantly increased with mental concentration compared to baseline, but did not change with further introduction of the stressor. Muscle activity significantly increased from the low stress to high stress condition for both the dominant and non-dominant upper trapezius, with no corresponding change in activity of the cervical extensors or flexors between stress conditions. These findings suggest that upper trapezius muscles are selectively activated by psychosocial stress independent of changes in concentration or posture, which may have implications for the prevention of stress-related trapezius myalgia in the workplace.

  14. Induced resistance in tomato by SAR activators during predisposing salinity stress

    PubMed Central

    Pye, Matthew F.; Hakuno, Fumiaki; MacDonald, James D.; Bostock, Richard M.

    2013-01-01

    Plant activators are chemicals that induce disease resistance. The phytohormone salicylic acid (SA) is a crucial signal for systemic acquired resistance (SAR), and SA-mediated resistance is a target of several commercial plant activators, including Actigard (1,2,3-benzothiadiazole-7-thiocarboxylic acid-S-methyl-ester, BTH) and Tiadinil [N-(3-chloro-4-methylphenyl)-4-methyl-1,2,3-thiadiazole-5-carboxamide, TDL]. BTH and TDL were examined for their impact on abscisic acid (ABA)-mediated, salt-induced disease predisposition in tomato seedlings. A brief episode of salt stress to roots significantly increased the severity of disease caused by Pseudomonas syringae pv. tomato (Pst) and Phytophthora capsici relative to non-stressed plants. Root treatment with TDL induced resistance to Pst in leaves and provided protection in both non-stressed and salt-stressed seedlings in wild-type and highly susceptible NahG plants. Non-stressed and salt-stressed ABA-deficient sitiens mutants were highly resistant to Pst. Neither TDL nor BTH induced resistance to root infection by Phytophthora capsici, nor did they moderate the salt-induced increment in disease severity. Root treatment with these plant activators increased the levels of ABA in roots and shoots similar to levels observed in salt-stressed plants. The results indicate that SAR activators can protect tomato plants from bacterial speck disease under predisposing salt stress, and suggest that some SA-mediated defense responses function sufficiently in plants with elevated levels of ABA. PMID:23653630

  15. LAPS Lidar Measurements at the ARM Alaska Northslope Site (Support to FIRE Project)

    NASA Technical Reports Server (NTRS)

    Philbrick, C. Russell; Lysak, Daniel B., Jr.; Petach, Tomas M.; Esposito, Steven T.; Mulik, Karoline R.

    1998-01-01

    This report consists of data summaries of the results obtained during the May 1998 measurement period at Barrow Alaska. This report does not contain any data interpretation or analysis of the results which will follow this activity. This report is forwarded with a data set on magnetic media which contains the reduced data from the LAPS lidar in 15 minute intervals. The data was obtained during the period 15-30 May 1998. The measurement period overlapped with several aircraft flights conducted by NASA as part of the FIRE project. The report contains a summary list of the data obtained plus figures that have been prepared to help visualize the measurement periods. The order of the presentation is as follows: Section 1. A copy of the Statement of Work for the planned activity of the second measurement period at the ARM Northslope site is provided. Section 2. A list of the data collection periods shows the number of one minute data records stored during each hour of operation and the corresponding size (Mbytes) of the one hour data folders. The folder and file names are composed from the year, month, day, hour and minute. The date/time information is given in UTC for easier comparison with other data sets. Section 3. A set of 4 comparisons between the LAPS lidar results and the sondes released by the ARM scientists from a location nearby the lidar. The lidar results show the +/- 1 sigma statistical error on each of the independent 75 m altitude bins of the data. This set of 4 comparisons was used to set and validate the calibration value which was then used for the complete data set. Section 4. A set of false color figures with up to 10 hours of specific humidity measurements are shown in each graph. Two days of measurements are shown on each page. These plots are crude representations of the data and permit a survey which indicates when the clouds were very low or where interesting events may occur in the results. These plots are prepared using the real time sequence

  16. The Characteristics of Fatigue Damage in the Fuselage Riveted Lap Splice Joint

    NASA Technical Reports Server (NTRS)

    Piascik, Robert S.; Willard, Scott A.

    1997-01-01

    An extensive data base has been developed to form the physical basis for new analytical methodology to predict the onset of widespread fatigue damage in the fuselage lap splice joint. The results of detailed destructive examinations have been cataloged to describe the physical nature of MSD in the lap splice joint. ne catalog includes a detailed description, e.g., crack initiation, growth rates, size, location, and fracture morphology, of fatigue damage in the fuselage lap splice joint structure. Detailed examinations were conducted on a lap splice joint panel removed from a full scale fuselage test article after completing a 60,000 cycle pressure test. The panel contained a four bay region that exhibited visible outer skin cracks and regions of crack link-up along the upper rivet row. Destructive examinations revealed undetected fatigue damage in the outer skin, inner skin, and tear strap regions. Outer skin fatigue cracks were found to initiate by fretting damage along the faying surface. The cracks grew along the faying surface to a length equivalent to two to three skin thicknesses before penetrating the outboard surface of the outer skin. Analysis of fracture surface marker bands produced during full scale testing revealed that all upper rivet row fatigue cracks contained in a dim bay region grow at similar rates; this important result suggests that fracture mechanics based methods can be used to predict the growth of outer skin fatigue cracks in lap splice structure. Results are presented showing the affects of MSD and out-of-plane pressure loads on outer skin crack link-up.

  17. Determination of the Corrosive Conditions Present within Aircraft Lap-Splice Joints

    NASA Technical Reports Server (NTRS)

    Lewis, Karen S.; Kelly, Robert G.; Piascik, Robert S.

    1999-01-01

    The complexity of airframe structure lends itself to damage resulting from crevice corrosion. Fuselage lap-splice joints are a particularly important structural detail in this regard because of the difficulty associated with detection and measurement of corrosion in these occluded regions. The objective of this work is to develop a laboratory corrosion test protocol to identify the chemistry to which lap joints are exposed and to develop a model of the corrosion within the joints. A protocol for collecting and identifying the chemistry of airframe crevice corrosion has been developed. Capillary electrophoresis (CE) is used to identify the ionic species contained in corrosion product samples removed from fuselage lap splice joints. CE analysis has been performed on over sixty corrosion product samples removed from both civilian and military aircraft. Over twenty different ions have been detected. Measurements of pH of wetted corroded surfaces indicated an alkaline occluded solution. After determining the species present and their relative concentrations, the resultant solution was reproduced in bulk and electrochemical tests were performed to determine the corrosion rate. Electrochemical analyses of the behavior of AA2024-T3 in these solutions gave corrosion rates of up to 250 microns per year (10 mpy). Additional tests have determined the relative importance of each of the detected ions in model solutions used for future predictive tests. The statistically significant ions have been used to create a second generation solution. Laboratory studies have also included exposure tests involving artificial lap joints exposed to various simulated bulk and crevice environments. The extent and morphology of the attack in artificial lap joints has been compared to studies of corroded samples from actual aircraft. Other effects, such as temperature and potential, as well as the impact of the environment on fatigue crack growth have also been studied.

  18. Stress

    MedlinePlus

    ... hurt or killed. Examples include a major accident, war, assault, or a natural disaster. This type of ... stress, so you can avoid more serious health effects. NIH: National Institute of Mental Health

  19. Understanding Insurance. A Guide for Industrial Cooperative Training Programs. Learning Activity Package No. 15.

    ERIC Educational Resources Information Center

    Duenk, Lester G.; Tuel, Charles

    This learning activity package (LAP) on the insurance industry and the methods used to give protection to the insured is designed for student self-study. Following a list of learning objectives, the LAP contains a pretest (answer key provided at the back). Six learning activities follow. The learning activities cover the following material: terms…

  20. Stress and happiness among adolescents with varying frequency of physical activity.

    PubMed

    Moljord, Inger Elise Opheim; Moksnes, Unni Karin; Eriksen, Lasse; Espnes, Geir Arild

    2011-10-01

    The aim of this cross-sectional study was to investigate associations between physical activity, stress, and happiness, as well as possible sex and age differences on these variables in a survey of 1,508 adolescent pupils (13 to 18 yr.) in middle Norway. Adolescents who reported they participated in physical activity 2 to 3 times per week or more scored significantly lower on stress and higher on happiness than those who participated in physical activity 1 day per week or less. There was no significant difference on stress and happiness between those being physically active 2 or 3 times a week and those being active almost every day. There was no sex difference in physical activity frequency. Girls had higher mean scores on stress, and boys scored higher on happiness. Adolescents 15 to 16 years old showed higher stress scores than those 17 to 18 years old, but there were no significant differences between the different age groups when looking at happiness and physical activity. A statistically significant two-way interaction of sex by age was found on both stress and happiness.

  1. Salivary alpha amylase activity in human beings of different age groups subjected to psychological stress.

    PubMed

    Sahu, Gopal K; Upadhyay, Seema; Panna, Shradha M

    2014-10-01

    Salivary alpha-amylase (sAA) has been proposed as a sensitive non-invasive biomarker for stress-induced changes in the body that reflect the activity of the sympathetic nervous system. Though several experiments have been conducted to determine the validity of this salivary component as a reliable stress marker in human subjects, the effect of stress induced changes on sAA level in different age groups is least studied. This article reports the activity of sAA in human subjects of different age groups subjected to psychological stress induced through stressful video clip. Differences in sAA level based on sex of different age groups under stress have also been studied. A total of 112 subjects consisting of both the male and female subjects, divided into two groups on basis of age were viewed a video clip of corneal transplant surgery as stressor. Activity of sAA from saliva samples of the stressed subjects were measured and compared with the activity of the samples collected from the subjects before viewing the clip. The age ranges of subjects were 18-25 and 40-60 years. The sAA level increased significantly in both the groups after viewing the stressful video. The increase was more pronounced in the younger subjects. The level of sAA was comparatively more in males than females in the respective groups. No significant change in sAA activity was observed after viewing the soothed video clip. Significant increase of sAA level in response to psychological stress suggests that it might act as a reliable sympathetic activity biochemical marker in different stages of human beings.

  2. Mitochondrial oxidant stress in locus coeruleus is regulated by activity and nitric oxide synthase

    PubMed Central

    Sanchez–Padilla, J.; Guzman, J.N.; Ilijic, E.; Kondapalli, J.; Galtieri, D.J.; Yang, B.; Schieber, S.; Oertel, W.; Wokosin, D.; Schumacker, P. T.; Surmeier, D. J.

    2014-01-01

    Summary Loss of noradrenergic locus coeruleus (LC) neurons is a prominent feature of aging–related neurodegenerative diseases, like Parkinson’s disease (PD). The basis of this vulnerability is not understood. To explore possible physiological determinants, LC neurons were studied using electrophysiological and optical approaches in ex vivo mouse brain slices. These studies revealed that autonomous activity in LC neurons was accompanied by oscillations in dendritic Ca2+ concentration attributable to opening of L–type Ca2+ channels. This oscillation elevated mitochondrial oxidant stress and was attenuated by inhibition of nitric oxide synthase. The relationship between activity and stress was malleable, as arousal and carbon dioxide, each increased the spike rate, but differentially affected mitochondrial oxidant stress. Oxidant stress also was increased in an animal model of PD. Thus, our results point to activity–dependent Ca2+ entry and a resulting mitochondrial oxidant stress as factors contributing to the vulnerability of LC neurons. PMID:24816140

  3. Protein aggregation activates erratic stress response in dietary restricted yeast cells

    PubMed Central

    Bhadra, Ankan Kumar; Das, Eshita; Roy, Ipsita

    2016-01-01

    Chronic stress and prolonged activation of defence pathways have deleterious consequences for the cell. Dietary restriction is believed to be beneficial as it induces the cellular stress response machinery. We report here that although the phenomenon is beneficial in a wild-type cell, dietary restriction leads to an inconsistent response in a cell that is already under proteotoxicity-induced stress. Using a yeast model of Huntington’s disease, we show that contrary to expectation, aggregation of mutant huntingtin is exacerbated and activation of the unfolded protein response pathway is dampened under dietary restriction. Global proteomic analysis shows that when exposed to a single stress, either protein aggregation or dietary restriction, the expression of foldases like peptidyl-prolyl isomerase, is strongly upregulated. However, under combinatorial stress, this lead is lost, which results in enhanced protein aggregation and reduced cell survival. Successful designing of aggregation-targeted therapeutics will need to take additional stressors into account. PMID:27633120

  4. Protein aggregation activates erratic stress response in dietary restricted yeast cells.

    PubMed

    Bhadra, Ankan Kumar; Das, Eshita; Roy, Ipsita

    2016-01-01

    Chronic stress and prolonged activation of defence pathways have deleterious consequences for the cell. Dietary restriction is believed to be beneficial as it induces the cellular stress response machinery. We report here that although the phenomenon is beneficial in a wild-type cell, dietary restriction leads to an inconsistent response in a cell that is already under proteotoxicity-induced stress. Using a yeast model of Huntington's disease, we show that contrary to expectation, aggregation of mutant huntingtin is exacerbated and activation of the unfolded protein response pathway is dampened under dietary restriction. Global proteomic analysis shows that when exposed to a single stress, either protein aggregation or dietary restriction, the expression of foldases like peptidyl-prolyl isomerase, is strongly upregulated. However, under combinatorial stress, this lead is lost, which results in enhanced protein aggregation and reduced cell survival. Successful designing of aggregation-targeted therapeutics will need to take additional stressors into account. PMID:27633120

  5. Are Kids Too Busy? Early Adolescents' Perceptions of Discretionary Activities, Overscheduling, and Stress

    ERIC Educational Resources Information Center

    Brown, Stephen L.; Nobiling, Brandye D.; Teufel, James; Birch, David A.

    2011-01-01

    Background: The activity patterns of children, especially after-school patterns, are receiving more professional attention. However, evidence regarding the value of various activities in children's lives is contradictory. The purpose of this study was to assess perceptions of discretionary activities, overscheduling, and levels of stress from…

  6. Petrography of Lunar Meteorite LAP 02205, a New Low-Ti Basalt Possibly Launch Paired with NWA 032

    NASA Technical Reports Server (NTRS)

    Jolliff, B. L.; Zeigler, R. A.; Korotev, R. L.

    2004-01-01

    Lunar meteorite LAP 02205 is a 1.23 kg basalt collected during the 2002 field season in the La- Paz ice field, Antarctica [1]. We present a petrographic description including mineral modes and compositions, and the major-element composition of the bulk meteorite. LAP 02205 is an Fe-rich, moderately low-Ti mare basalt that is similar in composition, mineralogy, and mineral chemistry to the NWA 032 basaltic lunar meteorite. LAP 02205 is yet another of the moderately low- Ti basaltic meteorites that are underrepresented among Apollo and Luna samples but that appear from remote sensing to be the most common basalt type on the Moon.

  7. Strengths of composite-to-metal double-lap bolted joints

    NASA Astrophysics Data System (ADS)

    Sun, Hsien-Tang

    1998-12-01

    A three-dimensional analysis was proposed to study the through-the-thickness clamping effect on the bearing failure of double-lap bolted laminated composite joints. Experiments were first performed to characterize the material response due to bearing failure in composite bolted joints with and without lateral clamp-up supports. Composite plates made of T800H/3900-2 graphite/epoxy were selected in the tests, and various washer sizes and clamping forces were used in the study. The clamping force in the bolt was found to vary with the applied load, and may increase significantly due to a sudden through-the-thickness expansion of the laminate under the washers where bearing failure occurred. Experiments showed that the joint strength and response can be significantly affected by the bolt clamp-up, and the bolt bearing failure is a 3-D phenomenon. In order to facilitate the use of the proposed model with the ABAQUS code, an interface module 3DBOLT was developed. In order to reinforce the incompressibility condition in calculations for bearing-damaged material predicted by the model, the condition was imposed through a penalty method in the frame work of finite element analyses. The module provides a user-friendly input deck, generates automatically a joint mesh, and produces outputs and graphics for displaying the stresses, strains, and deformations of the joints and for simulating the failure progression in joints during loading. Extensive comparisons were made between the test data and model predictions. Overall, the model predicts both the failure load and response of bolted composite joints very well for various clamping forces and washer sizes. The model also predicted very well for joints failed in net-tension and shear-out modes. The predicted bolt clamp-up load as a function of the applied load agreed also very well with the data, which validates that the proposed incompressibility assumption for bearing-damaged material. Based on the model, a parametric study

  8. Experiments and simulation for 6061-T6 aluminum alloy resistance spot welded lap joints

    NASA Astrophysics Data System (ADS)

    Florea, Radu Stefanel

    This comprehensive study is the first to quantify the fatigue performance, failure loads, and microstructure of resistance spot welding (RSW) in 6061-T6 aluminum (Al) alloy according to welding parameters and process sensitivity. The extensive experimental, theoretical and simulated analyses will provide a framework to optimize the welding of lightweight structures for more fuel-efficient automotive and military applications. The research was executed in four primary components. The first section involved using electron back scatter diffraction (EBSD) scanning, tensile testing, laser beam profilometry (LBP) measurements, and optical microscopy(OM) images to experimentally investigate failure loads and deformation of the Al-alloy resistance spot welded joints. Three welding conditions, as well as nugget and microstructure characteristics, were quantified according to predefined process parameters. Quasi-static tensile tests were used to characterize the failure loads in specimens based upon these same process parameters. Profilometer results showed that increasing the applied welding current deepened the weld imprints. The EBSD scans revealed the strong dependency between the grain sizes and orientation function on the process parameters. For the second section, the fatigue behavior of the RSW'ed joints was experimentally investigated. The process optimization included consideration of the forces, currents, and times for both the main weld and post-heating. Load control cyclic tests were conducted on single weld lap-shear joint coupons to characterize the fatigue behavior in spot welded specimens. Results demonstrate that welding parameters do indeed significantly affect the microstructure and fatigue performance for these welds. The third section comprised residual strains of resistance spot welded joints measured in three different directions, denoted as in-plane longitudinal, in-plane transversal, and normal, and captured on the fusion zone, heat affected zone

  9. Business Education: Learning Activities Packet for Office Education.

    ERIC Educational Resources Information Center

    Hawaii State Dept. of Education, Honolulu. Office of Instructional Services.

    These seventeen individualized learning activities packets (LAPs) are intended to relate essential competencies needed for entry or advancement in office occupations to the secondary level office education program and to assist students in achieving occupational proficiency in business careers. Each LAP contains some or all of the following…

  10. Effect of Drought Stress on Total Phenolic, Lipid Peroxidation, and Antioxidant Activity of Achillea Species.

    PubMed

    Gharibi, Shima; Tabatabaei, Badraldin Ebrahim Sayed; Saeidi, Ghodratollah; Goli, Sayed Amir Hossein

    2016-02-01

    The changes in total phenolic content (TPC), total flavonoid content (TFC), proline, malondialdehyde (MDA), H2O2, and antioxidant activity were assessed based on three model systems in three Achillea species (Achillea millefolium, A. nobilis, and A. filipendulina) growing under four irrigation regimes, including 100% FC (field capacity as normal irrigation) 75% FC (low stress), 50% FC (moderate stress), and 25% FC (severe stress) conditions. The highest TPC (47.13 mg tannic acid/g DW) and TFC (20.86 mg quercetin/g W) were obtained in A. filipendulina under moderate and severe stress conditions. In 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, the highest and the lowest antioxidant activity was obtained for A. millefolium (70.28%) and A. filipendulina (53.21%), respectively, while in the FTC model system A. nobilis revealed the highest antioxidant activity (1.934) in severe drought condition. In the linoleic model system, the highest antioxidant activity was observed under low drought stress condition in A. nobilis. MDA and H2O2 content were increased due to both low (75% FC) and moderate (50% FC) drought stress, but they were decreased under severe stress condition (25% FC). Furthermore, A. millefolium revealed the lowest H2O2 (4.96 nm/g FW) and MDA content (176.32 μmol/g). Investigation of the relationship among different metabolites showed a strong positive correlation with TPC and TFC. Finally, the moderate drought stress treatment (50% FC) was introduced as the optimum condition to obtain appreciable TPC and TFC,, while the highest antioxidant activity was obtained in severe stress condition (25%FC).

  11. [Activity of aldehyde scavenger enzymes in the heart of rats of different age during immobilized stress].

    PubMed

    Grabovetskaia, E R; Davydov, V V

    2009-01-01

    This study was made to determine the activity of aldehyde scavenger enzymes in the heart's postmitochondrial fraction of rats of different age during immobilization stress. Our study demonstrated, that immobilization of 1.5-, 2- and 12-month rats was accompanied by inhibiting activity of aldehyde dehydrogenase and aldehyde reductase. At the same time we observed an increase in glutathione transferase activity in immobilized 1.5-month-old rats and that in reductase activity in 24-month-old rats. The revealed changes can lead to a decrease in the rate of endogenous aldehyde utilization in the heart during stress at puberty.

  12. The Stress-Activated Signaling (SAS) Pathways of a Human Fungal Pathogen, Cryptococcus neoformans.

    PubMed

    Jung, Kwang-Woo; Bahn, Yong-Sun

    2009-09-01

    Cryptococcus neoformans is a basidiomycete human fungal pathogen that causes meningoencephalitis in both immunocompromised and immunocompetent individuals. The ability to sense and respond to diverse extracellular signals is essential for the pathogen to infect and cause disease in the host. Four major stress-activated signaling (SAS) pathways have been characterized in C. neoformans, including the HOG (high osmolarity glycerol response), PKC/Mpk1 MAPK (mitogen-activated protein kinase), calcium-dependent calcineurin, and RAS signaling pathways. The HOG pathway in C. neoformans not only controls responses to diverse environmental stresses, including osmotic shock, UV irradiation, oxidative stress, heavy metal stress, antifungal drugs, toxic metabolites, and high temperature, but also regulates ergosterol biosynthesis. The PKC (Protein kinase C)/Mpk1 pathway in C. neoformans is involved in a variety of stress responses, including osmotic, oxidative, and nitrosative stresses and breaches of cell wall integrity. The Ca(2+)/calmodulin- and Ras-signaling pathways also play critical roles in adaptation to certain environmental stresses, such as high temperature and sexual differentiation. Perturbation of the SAS pathways not only impairs the ability of C. neoformans to resist a variety of environmental stresses during host infection, but also affects production of virulence factors, such as capsule and melanin. A drug(s) capable of targeting signaling components of the SAS pathway will be effective for treatment of cryptococcosis.

  13. Guanfacine effects on stress, drug craving and prefrontal activation in cocaine dependent individuals: preliminary findings

    PubMed Central

    Fox, Helen C.; Seo, Dongju; Tuit, Keri; Hansen, Julie; Kimmerling, Anne; Morgan, Peter T.; Sinha, Rajita

    2013-01-01

    Cocaine dependence is associated with increased stress and drug cue-induced craving and physiological arousal but decreased prefrontal activity to emotional and cognitive challenge. As these changes are associated with relapse risk, we investigated the effects of α2 receptor agonist guanfacine on these processes. Twenty-nine early abstinent treatment-seeking cocaine dependent individuals were randomly assigned to either daily placebo or guanfacine (up to 3 mg) for four weeks. In a laboratory experiment, all patients were exposed to three 10-min guided imagery conditions (stress/stress, drug cue/drug cue, stress/drug cue), one per day, consecutively in a random, counterbalanced order. Subjective craving, anxiety and arousal as well as cardiovascular output were assessed repeatedly. Brain response to stress, drug cue and relaxing imagery was also assessed during a functional magnetic resonance (fMRI) imaging session. In the current study, guanfacine was found to be safe and well-tolerated. Lower basal heart rate and blood pressure was observed in the guanfacine versus placebo group. Guanfacine lowered stress and cue-induced nicotine craving and cue-induced cocaine craving, anxiety and arousal. The guanfacine group also showed increased medial and lateral prefrontal activity following stress and drug cue exposure compared with placebo. Data suggest further exploration of guanfacine is warranted in terms of its potential for reducing stress-induced and cue-induced drug craving and arousal. PMID:22234929

  14. Antioxidant enzymes expression and activity in liver of stressed wistar rat

    NASA Astrophysics Data System (ADS)

    Djordjević, J.; Nićiforović, A.; Radojčić, M. B.

    2009-09-01

    Altered activities of antioxidant defence system enzymes and the levels of free radicals scavengers have been found to correlate with various physiological or pathological conditions, including stress. The aim of this study was to determine the effects of chronic 21 day isolation stress on antioxidant enzymes (AOEs) expression and activity in Wistar rat liver tissue. The serum corticosterone (CORT) and glucose (GLU) levels were also measured, as one of the most important indicators of stress. Our data revealed that in chronic stress conditions, when both CORT and GLU were low, the AOEs expression was markedly induced. This increase in MnSOD, CuZnSOD, and catalase exhibited similar trend implying efficient detoxification of O_2^{ - .} and H2O2. However, this trend was not followed by the respective enzyme activity. While the total SOD activity was induced by the stress, catalase activity remained unaltered. This discrepancy led us to a conclusion that chronic isolation stress may cause oxidant-antioxidant imbalance in rat liver tissue, favoring H2O2 accumulation.

  15. A Drosophila Reporter for the Translational Activation of ATF4 Marks Stressed Cells during Development.

    PubMed

    Kang, Kwonyoon; Ryoo, Hyung Don; Park, Jung-Eun; Yoon, Jee-Hyun; Kang, Min-Ji

    2015-01-01

    Eukaryotic cells have evolved signaling pathways that help to restore cellular homeostasis in response to various physiological or pathological conditions. ATF4 is a transcription factor whose mRNA translation is stimulated in response to stress-activated eIF2alpha kinases. Established conditions that activate eIF2alpha phosphorylation and ATF4 translation include excessive stress in the endoplasmic reticulum (ER) and amino acid deprivation. ATF4 is activated through a unique translational activation mechanism that involves multiple upstream open reading frames (uORFs) in the 5'-untranslated region (UTR), which is conserved from yeast to mammals. Taking advantage of this, we developed a translational activation reporter of ATF4 in Drosophila, in which the dsRed reporter coding sequence was placed downstream of the Drosophila ATF4 5' UTR. This reporter remained inactive in most tissues under normal conditions, but showed dsRed expression when starved, or when challenged with conditions that imposed ER stress. In normally developing flies, a small number of cell types showed reporter expression even without exogenous stress, which included the salivary gland, gut, the male reproductive organ, and the photoreceptor cells, suggestive of inherent stress during the normal development of these cell types. These results establish a new tool to study ATF4-mediated stress response in Drosophila development and disease.

  16. Review of the use of physical restraints and lap belts with wheelchair users.

    PubMed

    Chaves, Eliana S; Cooper, Rory A; Collins, Diane M; Karmarkar, Amol; Cooper, Rosemarie

    2007-01-01

    Wheelchair-related physical restraints, lap belts, and other alternatives are intended to provide safe and adequate seating and mobility for individuals using wheelchairs. Physical restraints and lap belts are also helpful for positioning people in their wheelchairs to reduce the risk of injury during wheelchair tips and falls. However, when used improperly or in ways other than intended, injury or even death can result. Although widely prescribed, little evidence is available to direct professionals on the appropriate use of these restraints and lap belts and for whom these restraints are indicated. The purpose of this study was to conduct a review of available literature from 1966-2006 to identify the risks and benefits associated with lap belts while seated in wheelchairs. Twenty-five studies that met the inclusion criteria were reviewed. Nine studies reported the frequency of asphyxial deaths caused by physical restraints, nine studies reported the long-term complication and indirect adverse effects of physical restraints and lap-belt use, and seven studies reported the benefits of physical restraints and lap belts with individuals using wheelchairs. Despite the weak evidence, the results suggest a considerable number of deaths from asphyxia caused by the use of physical restraints occurred each year in the U.S. The majority of the deaths occurred in nursing homes, followed by hospitals, and then the home of the person. Most deaths occurred while persons were restrained in wheelchairs or beds. Based on that, caution needs to be exercised when using restraints or positioning belts. In addition, other seating and environment alternatives should be explored prior to using restraints or positioning belts, such as power wheelchair seating options. Positioning belts may reduce risk of falls from wheelchairs and should be given careful consideration, but caution should be exercised if the individual cannot open the latch independently. Also, the duration of use of the

  17. Transposable Elements Contribute to Activation of Maize Genes in Response to Abiotic Stress

    PubMed Central

    Makarevitch, Irina; Waters, Amanda J.; West, Patrick T.; Stitzer, Michelle; Hirsch, Candice N.; Ross-Ibarra, Jeffrey; Springer, Nathan M.

    2015-01-01

    Transposable elements (TEs) account for a large portion of the genome in many eukaryotic species. Despite their reputation as “junk” DNA or genomic parasites deleterious for the host, TEs have complex interactions with host genes and the potential to contribute to regulatory variation in gene expression. It has been hypothesized that TEs and genes they insert near may be transcriptionally activated in response to stress conditions. The maize genome, with many different types of TEs interspersed with genes, provides an ideal system to study the genome-wide influence of TEs on gene regulation. To analyze the magnitude of the TE effect on gene expression response to environmental changes, we profiled gene and TE transcript levels in maize seedlings exposed to a number of abiotic stresses. Many genes exhibit up- or down-regulation in response to these stress conditions. The analysis of TE families inserted within upstream regions of up-regulated genes revealed that between four and nine different TE families are associated with up-regulated gene expression in each of these stress conditions, affecting up to 20% of the genes up-regulated in response to abiotic stress, and as many as 33% of genes that are only expressed in response to stress. Expression of many of these same TE families also responds to the same stress conditions. The analysis of the stress-induced transcripts and proximity of the transposon to the gene suggests that these TEs may provide local enhancer activities that stimulate stress-responsive gene expression. Our data on allelic variation for insertions of several of these TEs show strong correlation between the presence of TE insertions and stress-responsive up-regulation of gene expression. Our findings suggest that TEs provide an important source of allelic regulatory variation in gene response to abiotic stress in maize. PMID:25569788

  18. Stress-induced alterations of left-right electrodermal activity coupling indexed by pointwise transinformation.

    PubMed

    Světlák, M; Bob, P; Roman, R; Ježek, S; Damborská, A; Chládek, J; Shaw, D J; Kukleta, M

    2013-01-01

    In this study, we tested the hypothesis that experimental stress induces a specific change of left-right electrodermal activity (EDA) coupling pattern, as indexed by pointwise transinformation (PTI). Further, we hypothesized that this change is associated with scores on psychometric measures of the chronic stress-related psychopathology. Ninety-nine university students underwent bilateral measurement of EDA during rest and stress-inducing Stroop test and completed a battery of self-report measures of chronic stress-related psychopathology. A significant decrease in the mean PTI value was the prevalent response to the stress conditions. No association between chronic stress and PTI was found. Raw scores of psychometric measures of stress-related psychopathology had no effect on either the resting levels of PTI or the amount of stress-induced PTI change. In summary, acute stress alters the level of coupling pattern of cortico-autonomic influences on the left and right sympathetic pathways to the palmar sweat glands. Different results obtained using the PTI, EDA laterality coefficient, and skin conductance level also show that the PTI algorithm represents a new analytical approach to EDA asymmetry description. PMID:24359433

  19. MSK2 negatively regulates p53 activity in the absence of stress

    PubMed Central

    Llanos, Susana; Cuadrado, Ana; Serrano, Manuel

    2013-01-01

    Mitogen- and stress-activated kinase 2 (MSK2) is an inhibitor of the transcription factor p53; here, we investigate the mechanisms underlying this inhibition. In the absence of stress stimuli, MSK2 selectively suppressed the expression of a subset of p53 target genes. This basal inhibition of p53 by MSK2 occurred independently of its catalytic kinase activity and of upstream mitogen-activated protein kinase (MAPK) signaling to MSK2. Furthermore, MSK2 interacted with and inhibited the p53 coactivator p300, and associated with the Noxa promoter. Apoptotic stimuli promoted the degradation of MSK2, thus relieving its inhibitory activity towards p53 and allowing efficient p53-dependent transactivation of Noxa, which contributed to apoptosis. Together, these findings constitute a new mechanism of p53 activation in response to stress. PMID:19797274

  20. The wheat MAP kinase phosphatase 1 alleviates salt stress and increases antioxidant activities in Arabidopsis.

    PubMed

    Zaidi, Ikram; Ebel, Chantal; Belgaroui, Nibras; Ghorbel, Mouna; Amara, Imène; Hanin, Moez

    2016-04-01

    Mitogen-activated protein kinase phosphatases (MKPs) are important negative regulators in the MAPK signaling pathways, which play crucial roles in plant growth, development and stress responses. We have previously shown that the heterologous expression of a durum wheat MKP, TMKP1, results in increased tolerance to salt stress in yeast but its particular contribution in salt stress tolerance in plants was not investigated. Here, TMKP1 was overexpressed in Arabidopsis thaliana and physiological changes were assessed in transgenic plants exposed to stress conditions. Under salt stress and especially LiCl, the TMKP1 overexpressors displayed higher germination rates in comparison to wild type plants. The enhancement of salt stress tolerance was accompanied by increased antioxidant enzyme activities, namely superoxide dismutase, catalase and peroxydases. Such increases in antioxidant activities were concomitant with lower malondialdehyde, superoxide anion O2(-) and hydrogen peroxide levels in the TMKP1 transgenic seedlings. Moreover, we provide evidence that, in contrast to the Arabidopsis ortholog AtMKP1, TMKP1 acts as a positive regulator of salt stress tolerance via its ectopic expression in the Arabidopsis mkp1 mutant. PMID:26927025

  1. 20th Century Fashions. Teacher Edition. Marketing Education LAPs.

    ERIC Educational Resources Information Center

    Hawley, Jana

    This learning activity packet is designed to help students to acquire a competency: how to use an understanding of fashion history in preparation for a career in the fashion industry. The unit consists of the competency, three objectives, suggested learning activity, transparency masters, and a pretest/posttest with answer keys. The activity is a…

  2. Careers in Fashion. Teacher Edition. Marketing Education LAPs.

    ERIC Educational Resources Information Center

    Hawley, Jana

    This learning activity packet is designed to help students to acquire a competency, namely: how to use knowledge of careers in the fashion industry to gain information about their career choices. The unit consists of the competency, three objectives, suggested learning activities, transparency masters, handout materials for activities, and a…

  3. Stress and Sucrose Intake Modulate Neuronal Activity in the Anterior Hypothalamic Area in Rats

    PubMed Central

    Mitra, Arojit; Guèvremont, Geneviève; Timofeeva, Elena

    2016-01-01

    The anterior hypothalamic area (AHA) is an important integrative relay structure for a variety of autonomic, endocrine, and behavioral responses including feeding behavior and response to stress. However, changes in the activity of the AHA neurons during stress and feeding in freely moving rats are not clear. The present study investigated the firing rate and burst activity of neurons in the central nucleus of the AHA (cAHA) during sucrose intake in non-stressful conditions and after acute stress in freely behaving rats. Rats were implanted with micro-electrodes into the cAHA, and extracellular multi-unit activity was recorded during 1-h access to 10% sucrose in non-stressful conditions or after acute foot shock stress. Acute stress significantly reduced sucrose intake, total sucrose lick number, and lick frequency in licking clusters, and increased inter-lick intervals. At the cluster start (CS) of sucrose licking, the cAHA neurons increased (CS-excited, 20% of the recorded neurons), decreased (CS-inhibited, 42% of the neurons) or did not change (CS-nonresponsive, 38% of the neurons) their firing rate. Stress resulted in a significant increase in the firing rate of the CS-inhibited neurons by decreasing inter-spike intervals within the burst firing of these neurons. This increase in the stress-induced firing rate of the CS-inhibited neurons was accompanied by a disruption of the correlation between the firing rate of CS-inhibited and CS-nonresponsive neurons that was observed in non-stressful conditions. Stress did not affect the firing rate of the CS-excited and CS-nonresponsive neurons. However, stress changed the pattern of burst firing of the CS-excited and CS-nonresponsive neurons by decreasing and increasing the burst number in the CS-excited and CS-nonresponsive neurons, respectively. These results suggest that the cAHA neurons integrate the signals related to stress and intake of palatable food and play a role in the stress- and eating-related circuitry

  4. Different peroxidase activities and expression of abiotic stress-related peroxidases in apical root segments of wheat genotypes with different drought stress tolerance under osmotic stress.

    PubMed

    Csiszár, Jolán; Gallé, Agnes; Horváth, Edit; Dancsó, Piroska; Gombos, Magdolna; Váry, Zsolt; Erdei, László; Györgyey, János; Tari, Irma

    2012-03-01

    One-week-old seedlings of Triticum aestivum L. cv. Plainsman V, a drought tolerant; and Cappelle Desprez, a drought sensitive wheat cultivar were subjected gradually to osmotic stress using polyethylene glycol (PEG 6000) reaching 400 mOsm on the 11th day. Compared to controls cv. Plainsman V maintained the root growth and relative water content of root tissues, while these parameters were decreased in the drought sensitive cv. Cappelle Desprez under PEG-mediated osmotic stress. Simultaneously, H(2)O(2) content in 1-cm-long apical segment of roots comprising the proliferation and elongation zone, showed a transient increase in cv. Plainsman V and a permanent raise in cv. Cappelle Desprez. Measurements of the transcript levels of selected class III peroxidase (TaPrx) coding sequences revealed significant differences between the two cultivars on the 9th day, two days after applying 100 mOsm PEG. The abundance of TaPrx04 transcript was enhanced transitionally in the root apex of cv. Plainsman V but decreased in cv. Cappelle Desprez under osmotic stress while the expression of TaPrx01, TaPrx03, TaPrx19, TaPrx68, TaPrx107 and TaPrx109-C decreased to different extents in both cultivars. After a transient decrease, activities of soluble peroxidase fractions of crude protein extracts rose in both cultivars on day 11, but the activities of cell wall-bound fractions increased only in cv. Cappelle Desprez under osmotic stress. Parallel with high H(2)O(2) content of the tissues, certain isoenzymes of covalently bound fraction in cv. Cappelle Desprez showed increased activity suggesting that they may limit the extension of root cell walls in this cultivar.

  5. Calcium Causes Multimerization of the Large Adhesin LapF and Modulates Biofilm Formation by Pseudomonas putida

    PubMed Central

    Martínez-Gil, Marta; Romero, Diego; Kolter, Roberto

    2012-01-01

    LapF is a large secreted protein involved in microcolony formation and biofilm maturation in Pseudomonas putida. Its C-terminal domain shows the characteristics of proteins secreted through a type I secretion system and includes a predicted calcium binding motif. We provide experimental evidence of specific binding of Ca2+ to the purified C-terminal domain of LapF (CLapF). Calcium promotes the formation of large aggregates, which disappear in the presence of the calcium chelator EGTA. Immunolocalization of LapF also shows the tendency of this protein to accumulate in vivo in certain extracellular regions. These findings, along with results showing that calcium influences biofilm formation, lead us to propose a model in which P. putida cells interact with each other via LapF in a calcium-dependent manner during the development of biofilms. PMID:23042991

  6. Learning Activity Packets for Auto Mechanics II. Section A--Engine Rebuilding.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    Eight learning activity packets (LAPs) are provided for the instructional area of engine rebuilding in the auto mechanics II program. They accompany an instructor's guide available separately. The LAPs outline the study activities and performance tasks for these eight units: (1) engine condition evaluation; (2) engine removal; (3) engine…

  7. Individualized Instruction in Science, Earth-Space Project, Self-Directed Activities.

    ERIC Educational Resources Information Center

    Kuczma, R. M.

    As a supplement to Learning Activity Packages (LAP) of the earth-space project, this manual presents self-directed activities especially designed for individualized instruction. Besides an introduction to LAP characteristics, sets of instructions are given in connection with the metric system, the earth's dimensions, indirect evidence for atomic…

  8. Individualized Instruction in Science, Time-Space-Matter, Self-Directed Activities.

    ERIC Educational Resources Information Center

    Kuczma, R. M.

    As a supplement to Learning Activity Packages (LAP) on the time-space-matter subject, details are presented for self-directed activities. Major descriptions are given on the background of LAP characteristics, metric system, profile graph construction, spectroscope operation, radiant energy measurement, sunspot effects, density determination,…

  9. Learning Activity Packets for Auto Mechanics II. Section C--Drive Train.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    Five learning activity packets (LAPs) are provided for the instructional area of drive train in the auto mechanics II program. They accompany an instructor's guide available separately. The LAPs outline the study activities and performance tasks for these five units: (1) clutch assembly, (2) standard transmission, (3) drive lines, (4) rear axle,…

  10. Learning Activity Packets for Milling Machines. Unit I--Introduction to Milling Machines.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This learning activity packet (LAP) outlines the study activities and performance tasks covered in a related curriculum guide on milling machines. The course of study in this LAP is intended to help students learn to identify parts and attachments of vertical and horizontal milling machines, identify work-holding devices, state safety rules, and…

  11. The transcendental meditation technique, adrenocortical activity, and implications for stress.

    PubMed

    Jevning, R; Wilson, A F; Smith, W R

    1978-05-15

    The practice of the transcendental meditation technique in subjects eliciting this state regularly for 3--5 years is correlated with acute decline of adrenocortical activity not associated with sleep during the practice.

  12. Differential Effects of Stress on Microglial Cell Activation in Male and Female Medial Prefrontal Cortex

    PubMed Central

    Bollinger, Justin L.; Bergeon Burns, Christine M.; Wellman, Cara L.

    2016-01-01

    Susceptibility to stress-linked psychological disorders, including post-traumatic stress disorder and depression, differs between men and women. Dysfunction of medial prefrontal cortex (mPFC) has been implicated in many of these disorders. Chronic stress affects mPFC in a sex-dependent manner, differentially remodeling dendritic morphology and disrupting prefrontally mediated behaviors in males and females. Chronic restraint stress induces microglial activation, reflected in altered microglial morphology and immune factor expression, in mPFC in male rats. Unstressed females exhibit increased microglial ramification in several brain regions compared to males, suggesting both heightened basal activation and a potential for sex-dependent effects of stress on microglial activation. Therefore, we assessed microglial density and ramification in the prelimbic region of mPFC, and immune-associated genes in dorsal mPFC in male and female rats following acute or chronic restraint stress. Control rats were left unstressed. On the final day of restraint, brains were collected for either qPCR or visualization of microglia using Iba-1 immunohistochemistry. Microglia in mPFC were classified as ramified, primed, reactive, or amoeboid, and counted stereologically. Expression of microglia-associated genes (MHCII, CD40, IL6, CX3CL1, and CX3CR1) was also assessed using qPCR. Unstressed females showed a greater proportion of primed to ramified microglia relative to males, alongside heightened CX3CL1-CX3CR1 expression. Acute and chronic restraint stress reduced the proportion of primed to ramified microglia and microglial CD40 expression in females, but did not significantly alter microglial activation in males. This sex difference in microglial activation could contribute to the differential effects of stress on mPFC structure and function in males versus females. PMID:26441134

  13. Nodule Activity and Allocation of Photosynthate of Soybean during Recovery from Water Stress 1

    PubMed Central

    Fellows, Robert J.; Patterson, Robert P.; Raper, C. David; Harris, Dorothy

    1987-01-01

    Nodulated soybean plants (Glycine max [L.] Merr. cv Ransom) in a growth-chamber study were subjected to a leaf water potential (Ψw) of −2.0 megapascal during vegetative growth. Changes in nonstructural carbohydrate contents of leaves, stems, roots, and nodules, allocation of dry matter among plant parts, in situ specific nodule activity, and in situ canopy apparent photosynthetic rate were measured in stressed and nonstressed plants during a 7-day period following rewatering. Leaf and nodule Ψw also were determined. At the time of maximum stress, concentration of nonstructural carbohydrates had declined in leaves of stressed, relative to nonstressed, plants, and the concentration of nonstructural carbohydrates had increased in stems, roots, and nodules. Sucrose concentrations in roots and nodules of stressed plants were 1.5 and 3 times greater, respectively, than those of nonstressed plants. Within 12 hours after rewatering, leaf and nodule Ψw of stressed plants had returned to values of nonstressed plants. Canopy apparent photosynthesis and specific nodule activity of stressed plants recovered to levels for nonstressed plants within 2 days after rewatering. The elevated sucrose concentrations in roots and nodules of stressed plants also declined rapidly upon rehydration. The increase in sucrose concentration in nodules, as well as the increase of carbohydrates in roots and stems, during water stress and the rapid disappearance upon rewatering indicates that inhibition of carbohydrate utilization within the nodule may be associated with loss of nodule activity. Availability of carbohydrates within the nodules and from photosynthetic activity following rehydration of nodules may mediate the rate of recovery of N2-fixation activity. PMID:11539766

  14. Central beta-adrenergic receptors mediate renal nerve activity during stress in conscious spontaneously hypertensive rats.

    PubMed

    Koepke, J P; DiBona, G F

    1985-01-01

    The effects of intracerebroventricular (i.c.v.) administration of beta-adrenergic receptor antagonists (d,l-propranolol or timolol, 30 micrograms in 2 microL of isotonic saline) on the increased renal sympathetic nerve activity and decreased urinary sodium excretion (UNaV) responses to stressful environmental stimulation (air jet to head) in conscious spontaneously hypertensive rats (SHR) were examined. Before i.c.v. d,l-propranolol or timolol, air stress increased renal activity (68% from 10.6 +/- 2.1 and 63% from 8.2 +/- 0.9 integrator resets/min respectively). In contrast, after i.c.v. d,l-propranolol or timolol in the same conscious SHR, air stress had no effect on renal sympathetic nerve activity (+7% from 8.1 +/- 1.7 and +7% from 5.5 +/- 1.0 integrator resets/min respectively). Air stress decreased UNaV in conscious SHR given i.c.v. saline vehicle (25% from 2.8 +/- 0.5 microEq/min/100 g body weight), but had no effect on effective renal plasma flow or glomerular filtration rate. In contrast, after i.c.v. d,l-propranolol or timolol, air stress had no effect on UNaV (0% from 2.8 +/- 0.5 and +9% from 3.3 +/- 0.3 microEq/min/100 g body weight respectively). Mean arterial pressure increased similarly during air stress with i.c.v. saline-vehicle or beta-adrenergic receptor antagonists. Intravenous administration of the same doses of d,l-propranolol or timolol did not prevent the increased renal sympathetic nerve activity or decreased UNaV responses resulting from air stress. These results suggest that central nervous system beta-adrenergic receptors mediate the increased renal sympathetic nerve activity and decreased UNaV responses resulting from stressful environmental stimulation in conscious SHR.

  15. Nodule activity and allocation of photosynthate of soybean during recovery from water stress

    NASA Technical Reports Server (NTRS)

    Fellows, R. J.; Patterson, R. P.; Raper, C. D. Jr; Harris, D.; Raper CD, J. r. (Principal Investigator)

    1987-01-01

    Nodulated soybean plants (Glycine max [L.] Merr. cv Ransom) in a growth-chamber study were subjected to a leaf water potential (psi w) of -2.0 megapascal during vegetative growth. Changes in nonstructural carbohydrate contents of leaves, stems, roots, and nodules, allocation of dry matter among plant parts, in situ specific nodule activity, and in situ canopy apparent photosynthetic rate were measured in stressed and nonstressed plants during a 7-day period following rewatering. Leaf and nodule psi w also were determined. At the time of maximum stress, concentration of nonstructural carbohydrates had declined in leaves of stressed, relative to nonstressed, plants, and the concentration of nonstructural carbohydrates had increased in stems, roots, and nodules. Sucrose concentrations in roots and nodules of stressed plants were 1.5 and 3 times greater, respectively, than those of nonstressed plants. Within 12 hours after rewatering, leaf and nodule psi w of stressed plants had returned to values of nonstressed plants. Canopy apparent photosynthesis and specific nodule activity of stressed plants recovered to levels for nonstressed plants within 2 days after rewatering. The elevated sucrose concentrations in roots and nodules of stressed plants also declined rapidly upon rehydration. The increase in sucrose concentration in nodules, as well as the increase of carbohydrates in roots and stems, during water stress and the rapid disappearance upon rewatering indicates that inhibition of carbohydrate utilization within the nodule may be associated with loss of nodule activity. Availability of carbohydrates within the nodules and from photosynthetic activity following rehydration of nodules may mediate the rate of recovery of N2-fixation activity.

  16. Nodule activity and allocation of photosynthate of soybean during recovery from water stress.

    PubMed

    Fellows, R J; Patterson, R P; Raper, C D; Harris, D

    1987-05-01

    Nodulated soybean plants (Glycine max [L.] Merr. cv Ransom) in a growth-chamber study were subjected to a leaf water potential (psi w) of -2.0 megapascal during vegetative growth. Changes in nonstructural carbohydrate contents of leaves, stems, roots, and nodules, allocation of dry matter among plant parts, in situ specific nodule activity, and in situ canopy apparent photosynthetic rate were measured in stressed and nonstressed plants during a 7-day period following rewatering. Leaf and nodule psi w also were determined. At the time of maximum stress, concentration of nonstructural carbohydrates had declined in leaves of stressed, relative to nonstressed, plants, and the concentration of nonstructural carbohydrates had increased in stems, roots, and nodules. Sucrose concentrations in roots and nodules of stressed plants were 1.5 and 3 times greater, respectively, than those of nonstressed plants. Within 12 hours after rewatering, leaf and nodule psi w of stressed plants had returned to values of nonstressed plants. Canopy apparent photosynthesis and specific nodule activity of stressed plants recovered to levels for nonstressed plants within 2 days after rewatering. The elevated sucrose concentrations in roots and nodules of stressed plants also declined rapidly upon rehydration. The increase in sucrose concentration in nodules, as well as the increase of carbohydrates in roots and stems, during water stress and the rapid disappearance upon rewatering indicates that inhibition of carbohydrate utilization within the nodule may be associated with loss of nodule activity. Availability of carbohydrates within the nodules and from photosynthetic activity following rehydration of nodules may mediate the rate of recovery of N2-fixation activity.

  17. Cognitive activation theory of stress (CATS): from fish brains to the Olympics.

    PubMed

    Eriksen, Hege R; Murison, Robert; Pensgaard, Anne Marte; Ursin, Holger

    2005-11-01

    The Cognitive Activation Theory of Stress (CATS) offers formal and systematic definitions of the terms and concepts used in stress research. The stress response depends on acquired expectancies to the outcome of the stimulus and the available responses. The stress response itself is an alarm, an increase in arousal necessary for performance and adequate reactions to challenges. The response is healthy and necessary for survival. Only when sustained over time may potential health risks occur. The basic rules for when stress occurs are the same across cultures and species, from fish to Olympic performance in humans. The important dimensions for health are positive expectancies of outcome (coping), control, and safety, for all individuals in all species. PMID:15964143

  18. ER stress does not cause upregulation and activation of caspase-2 to initiate apoptosis.

    PubMed

    Sandow, J J; Dorstyn, L; O'Reilly, L A; Tailler, M; Kumar, S; Strasser, A; Ekert, P G

    2014-03-01

    A recent report claimed that endoplasmic reticulum (ER) stress activates the ER trans-membrane receptor IRE1α, leading to increased caspase-2 levels via degradation of microRNAs, and consequently induction of apoptosis. This observation casts caspase-2 into a central role in the apoptosis triggered by ER stress. We have used multiple cell types from caspase-2-deficient mice to test this hypothesis but failed to find significant impact of loss of caspase-2 on ER-stress-induced apoptosis. Moreover, we did not observe increased expression of caspase-2 protein in response to ER stress. Our data strongly argue against a critical role for caspase-2 in ER-stress-induced apoptosis.

  19. Organizational and activational effects of testosterone on masculinization of female physiological and behavioral stress responses.

    PubMed

    Goel, Nirupa; Bale, Tracy L

    2008-12-01

    The prevalence of affective disorders is two times greater in women than in men. The onset of anxiety and depression occurs at different ages that may correspond to key developmental periods when the brain is more vulnerable to hormonal and exogenous influences. Because stressful life events can precipitate disease onset, the development of greater stress sensitivity in females may contribute to their increased vulnerability. Gonadal hormone exposure in males during early development and again from puberty onward plays a prominent role in sexually dimorphic brain formation, possibly contributing to sex differences in stress responsivity. Therefore, organizational effects of testosterone propionate (TP) administered postnatally and activational effects of TP administered beginning at puberty on adult female physiological and behavioral stress responses were examined in mice. Although the activational effects of TP in females ameliorated the sex difference in the hypothalamic-pituitary-adrenal axis stress response, there was no effect of postnatal TP. Similarly, higher immobile time in intact females in the tail suspension test was blunted by activational TP in the absence of postnatal TP. However, in the marble-burying test of anxiety-like behaviors, organizational and activational TP independently resulted in increased burying behaviors. These results show that TP administration has distinct effects on reducing physiological and behavioral stress responsivity in rodent models and suggest that sex differences in these responses may partially result from the absence of testosterone in females.

  20. Inhibitory effects of stress on postprandial gastric myoelectrical activity and vagal tone in healthy subjects.

    PubMed

    Yin, J; Levanon, D; Chen, J D Z

    2004-12-01

    The aim was to investigate gastric myoelectrical activity (GMA) and vagal activity in response to stress. The study was performed in 10 healthy subjects in three sessions (control, relaxation and stress). The control session was composed of 30-min recordings before and 30-min recordings after a test meal. The protocol of two other sessions was similar except that the fasting recording was extended to 60 min and the subjects were continuously watching a horror movie (stress) or guided meditation tape (relaxation) after the 30-min baseline. GMA was recorded using electrogastrography and heart rate variability (HRV) was derived from the electrocardiogram. Meal resulted in a postprandial increase in the dominant frequency (2.91 cpm vs 3.17 cpm, P < 0.007), dominant power (30.0 dB vs 32.5 dB, P < 0.05), and percentage of normal slow waves (79.8%vs 87.4%, P = 0.09). Similar responses were found in the relaxation session. Stress inhibited all these normal postprandial response and reduced the regularity of gastric slow waves (82.0%vs 66.0%, P < 0.01). In addition, spectral analysis of the HRV demonstrated an inhibition of postprandial vagal activity and an increase of postprandial sympathetic activity with stress. Stress has an inhibitory effect on postprandial GMA and this may involve both vagal and sympathetic pathway.

  1. Stress is critical for LPS-induced activation of microglia and damage in the rat hippocampus.

    PubMed

    Espinosa-Oliva, A M; de Pablos, R M; Villarán, R F; Argüelles, S; Venero, J L; Machado, A; Cano, J

    2011-01-01

    The hippocampus is insensitive to strong inflammatory stimulus under normal conditions and one of the most severely affected areas in Alzheimer's disease. We have analyzed the effect of chronic stress for 9 days in the hippocampus unilaterally injected with LPS. In non-stressed rats, LPS injection failed to activate microglia although a subset of degenerating cells in the CA1 area was evident. This effect was not accompanied by loss of Neu-N positive neurons in the CA1 area. In stressed rats, LPS injection had a dramatic effect in activating microglia along with astrogliosis and BDNF mRNA induction. NeuN immunostaining demonstrated a loss of about 50% of CA1 pyramidal neurons under these conditions. Fluoro jade B histochemistry demonstrated the presence of degenerating cells in most of CA1 area. Mechanistically, combination of chronic stress and LPS resulted in prominent activation of MAPKs including JNK, p38 and ERK clearly different from LPS injection in controls. Further, LPS+stress induced a dramatic decrease in phosphorylated levels of both Akt and CREB, which fully supports a consistent deleterious state in the hippocampal system under these conditions. Treatment with RU486, a potent inhibitor of glucocorticoid receptor activation, significantly protected animals against the deleterious effects observed in LPS-stressed animals.

  2. Effects of novelty stress on hippocampal gene expression, corticosterone and motor activity in mice.

    PubMed

    Kurumaji, Akeo; Umino, Masakazu; Nishikawa, Toru

    2011-10-01

    Exposure to novelty, a mild psychological stressor, induces neuronal activations in the hippocampus of rodents, which may play an important role in the adaptation to stress. We examined the changes in three parameters, i.e., gene expression in the hippocampus using a RT-PCR method, corticosterone and motor activity, in mice exposed to a new environment for 120min. A sharp and short-lasting increase in the gene expression of a set of stress-related genes previously reported, e.g., Fos and Nr4a1, was observed during the stress, with a similar pattern of changes in corticosterone. The motor activity gradually decreased during the novelty stress, indicating a process of adaptation to the new environment. In addition, in order to minimize the effects of elevated adrenal hormones by the stress, we carried out experiments on adrenalectomized (ADX) mice. However, the adrenalectomy produced minimal changes in the pattern and the magnitude of the gene response after the stress, while the motor activity showed a relatively slower pattern of adaptation in the ADX mice. Hence, the present study suggests that there was a coordinated adaptation process to the new environment in mice, and that the transcriptional response was mediated by neuronal networks rather than by adrenal hormones.

  3. Activation of the Low Molecular Weight Protein Tyrosine Phosphatase in Keratinocytes Exposed to Hyperosmotic Stress

    PubMed Central

    Cavalheiro, Renan P.; Machado, Daisy; Cruz, Bread L. G.; Paredes-Gamero, Edgar J.; Gomes-Marcondes, Maria C. C.; Zambuzzi, Willian F.; Vasques, Luciana; Nader, Helena B.; Souza, Ana Carolina S.; Justo, Giselle Z.

    2015-01-01

    Herein, we provide new contribution to the mechanisms involved in keratinocytes response to hyperosmotic shock showing, for the first time, the participation of Low Molecular Weight Protein Tyrosine Phosphatase (LMWPTP) activity in this event. We reported that sorbitol-induced osmotic stress mediates alterations in the phosphorylation of pivotal cytoskeletal proteins, particularly Src and cofilin. Furthermore, an increase in the expression of the phosphorylated form of LMWPTP, which was followed by an augment in its catalytic activity, was observed. Of particular importance, these responses occurred in an intracellular milieu characterized by elevated levels of reduced glutathione (GSH) and increased expression of the antioxidant enzymes glutathione peroxidase and glutathione reductase. Altogether, our results suggest that hyperosmostic stress provides a favorable cellular environment to the activation of LMWPTP, which is associated with increased expression of antioxidant enzymes, high levels of GSH and inhibition of Src kinase. Finally, the real contribution of LMWPTP in the hyperosmotic stress response of keratinocytes was demonstrated through analysis of the effects of ACP1 gene knockdown in stressed and non-stressed cells. LMWPTP knockdown attenuates the effects of sorbitol induced-stress in HaCaT cells, mainly in the status of Src kinase, Rac and STAT5 phosphorylation and activity. These results describe for the first time the participation of LMWPTP in the dynamics of cytoskeleton rearrangement during exposure of human keratinocytes to hyperosmotic shock, which may contribute to cell death. PMID:25781955

  4. Activation of the low molecular weight protein tyrosine phosphatase in keratinocytes exposed to hyperosmotic stress.

    PubMed

    Silva, Rodrigo A; Palladino, Marcelly V; Cavalheiro, Renan P; Machado, Daisy; Cruz, Bread L G; Paredes-Gamero, Edgar J; Gomes-Marcondes, Maria C C; Zambuzzi, Willian F; Vasques, Luciana; Nader, Helena B; Souza, Ana Carolina S; Justo, Giselle Z

    2015-01-01

    Herein, we provide new contribution to the mechanisms involved in keratinocytes response to hyperosmotic shock showing, for the first time, the participation of Low Molecular Weight Protein Tyrosine Phosphatase (LMWPTP) activity in this event. We reported that sorbitol-induced osmotic stress mediates alterations in the phosphorylation of pivotal cytoskeletal proteins, particularly Src and cofilin. Furthermore, an increase in the expression of the phosphorylated form of LMWPTP, which was followed by an augment in its catalytic activity, was observed. Of particular importance, these responses occurred in an intracellular milieu characterized by elevated levels of reduced glutathione (GSH) and increased expression of the antioxidant enzymes glutathione peroxidase and glutathione reductase. Altogether, our results suggest that hyperosmostic stress provides a favorable cellular environment to the activation of LMWPTP, which is associated with increased expression of antioxidant enzymes, high levels of GSH and inhibition of Src kinase. Finally, the real contribution of LMWPTP in the hyperosmotic stress response of keratinocytes was demonstrated through analysis of the effects of ACP1 gene knockdown in stressed and non-stressed cells. LMWPTP knockdown attenuates the effects of sorbitol induced-stress in HaCaT cells, mainly in the status of Src kinase, Rac and STAT5 phosphorylation and activity. These results describe for the first time the participation of LMWPTP in the dynamics of cytoskeleton rearrangement during exposure of human keratinocytes to hyperosmotic shock, which may contribute to cell death. PMID:25781955

  5. Asymmetric dimethylarginine (ADMA) treatment induces apoptosis in cultured rat mesangial cells via endoplasmic reticulum stress activation.

    PubMed

    Park, Min-Jung; Oh, Ki-Seok; Nho, Jong-Hyun; Kim, Gye-Yeop; Kim, Dong-Il

    2016-06-01

    Asymmetric dimethylarginine (ADMA), a high risk factor for endothelial dysfunction and cardiovascular disease (CVD), has been reported to promote cellular dysfunction via endoplasmic reticulum (ER) stress activation in various cells. Additionally, increased serum ADMA levels have been observed in incipient kidney diseases. Previously, we reported that activated ER stress is associated with mesangial cell apoptosis, observed mainly in overt nephropathy or chronic kidney disease (CKD). However, the effect of ADMA on mesangial cell apoptosis is unknown. Thus, we investigated the effects of ADMA on mesangial cell apoptosis and ER stress signaling. ADMA treatment increased caspase-3 activity and activated three branches of ER stress signaling (PERK, IRE1, and ATF6) that induce mesangial cell apoptosis. Pharmacological inhibitors of ER stress (inhibitors of PERK, IRE1, and S1P) attenuated ADMA-induced cleavage of caspase-3 and induced a decrease in the mitochondrial membrane potential. Furthermore, these inhibitors diminished the number of apoptotic cells induced by ADMA treatment. Taken together, our results indicated that ADMA treatment induces mesangial cell apoptosis via ER stress signaling. These results suggest that ADMA-induced mesangial cell apoptosis could contribute to the progression of overt nephropathy and CKD.

  6. Stress-Strain Relationship of Ca(OH)2-Activated Hwangtoh Concrete

    PubMed Central

    Mun, Ju-Hyun; Hwang, Hey-Zoo

    2014-01-01

    This study examined the stress-strain behavior of 10 calcium hydroxide (Ca(OH)2)-activated Hwangtoh concrete mixes. The volumetric ratio of the coarse aggregate (Vagg) and the water-to-binder (W/B) ratio were selected as the main test variables. Two W/B ratios (25% and 40%) were used and the value of Vagg varied between 0% and 40.0%, and 0% and 46.5% for W/B ratios of 25% and 40%, respectively. The test results demonstrated that the slope of the ascending branch of the stress-strain curve of Ca(OH)2-activated Hwangtoh concrete was smaller, and it displayed a steeper drop in stress in the descending branch, compared with those of ordinary Portland cement (OPC) concrete with the same compressive strength. This trend was more pronounced with the increase in the W/B ratio and decrease in Vagg. Based on the experimental observations, a simple and rational stress-strain model was established mathematically. Furthermore, the modulus of elasticity and strain at peak stress of the Ca(OH)2-activated Hwangtoh concrete were formulated as a function of its compressive strength and Vagg. The proposed stress-strain model predicted the actual behavior accurately, whereas the previous models formulated using OPC concrete data were limited in their applicability to Ca(OH)2-activated Hwangtoh concrete. PMID:25147869

  7. Anti-stress Activity of Ocimum sanctum: Possible Effects on Hypothalamic-Pituitary-Adrenal Axis.

    PubMed

    Jothie Richard, Edwin; Illuri, Ramanaiah; Bethapudi, Bharathi; Anandhakumar, Senthilkumar; Bhaskar, Anirban; Chinampudur Velusami, Chandrasekaran; Mundkinajeddu, Deepak; Agarwal, Amit

    2016-05-01

    The present study investigated anti-stress potential of Ocimum sanctum in chronic variable stress (CVS) paradigm. Further, the possible mechanism of anti-stress was explored in vitro using cell and cell-free assays. Rats were administered O. sanctum followed by CVS regimen for a period of 16 days. On days 4, 8, 12, and 16, body weight and immobility time in forced swim test were measured. In addition, the possible inhibitory effect of O. sanctum and ursolic acid on cortisol release and CRHR1 receptor activity were studied in cell-based assays, while inhibitory effects on 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) and catechol-O-methyltransferase (COMT) were studied in cell-free assays. CVS group demonstrated less body weight gain and higher immobility time than O. sanctum administered groups, while oral administration of O. sanctum significantly increased body weight gain and decreased the immobility time. Further, O. sanctum and its constituents inhibited cortisol release and exhibited a significant CRHR1 receptor antagonist activity. Also, they had specific inhibitory activity towards 11β-HSD1 and COMT activity. Thus, O. sanctum was found to be effective in the management of stress effects, and anti-stress activity could be due to inhibition of cortisol release, blocking CRHR1 receptor, and inhibiting 11β-HSD1 and COMT activities. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26899341

  8. Modification of plasma membrane NADPH oxidase activity in cucumber seedling roots in response to cadmium stress.

    PubMed

    Jakubowska, Dagmara; Janicka-Russak, Małgorzata; Kabała, Katarzyna; Migocka, Magdalena; Reda, Małgorzata

    2015-05-01

    The aim of this study was to investigate the effect of cadmium on plasma membrane (PM) NADPH oxidase activity in cucumber roots. Plants were treated with cadmium for 1, 3 or 6 days. Some of the plants after 3-day exposure to cadmium were transferred to a medium without the heavy metal for the next 3 days. Treatment of plants with cadmium for 6 days stimulated the activity of NADPH oxidase. The highest stimulation of O2(•-) production by NADPH oxidase was observed in post-stressed plants, which was correlated with the stimulation of activity of PM H(+)-ATPase in the same conditions. In order to examine the effects of cadmium stresses on the expression level of genes encoding NADPH oxidase, putative cucumber homologs encoding RBOH proteins were selected and a real-time PCR assay was performed. NADPH is a substrate for oxidase; thus alterations in the activity of glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, NADP-isocitrate dehydrogenase and NADP-malic enzyme under cadmium stress were studied. The activity of NADPH dehydrogenases was increased under cadmium stress. The results indicate that PM NADPH oxidase could be involved in plants' response to cadmium stress by affecting the activity of PM H(+)-ATPase, and NADPH-generating enzymes could play important roles in this process.

  9. Orbital fluid shear stress promotes osteoblast metabolism, proliferation and alkaline phosphates activity in vitro

    SciTech Connect

    Aisha, M.D.; Nor-Ashikin, M.N.K.; Sharaniza, A.B.R.; Nawawi, H.; Froemming, G.R.A.

    2015-09-10

    Prolonged disuse of the musculoskeletal system is associated with reduced mechanical loading and lack of anabolic stimulus. As a form of mechanical signal, the multidirectional orbital fluid shear stress transmits anabolic signal to bone forming cells in promoting cell differentiation, metabolism and proliferation. Signals are channeled through the cytoskeleton framework, directly modifying gene and protein expression. For that reason, we aimed to study the organization of Normal Human Osteoblast (NHOst) cytoskeleton with regards to orbital fluid shear (OFS) stress. Of special interest were the consequences of cytoskeletal reorganization on NHOst metabolism, proliferation, and osteogenic functional markers. Cells stimulated at 250 RPM in a shaking incubator resulted in the rearrangement of actin and tubulin fibers after 72 h. Orbital shear stress increased NHOst mitochondrial metabolism and proliferation, simultaneously preventing apoptosis. The ratio of RANKL/OPG was reduced, suggesting that orbital shear stress has the potential to inhibit osteoclastogenesis and osteoclast activity. Increase in ALP activity and OCN protein production suggests that stimulation retained osteoblast function. Shear stress possibly generated through actin seemed to hold an anabolic response as osteoblast metabolism and functional markers were enhanced. We hypothesize that by applying orbital shear stress with suitable magnitude and duration as a non-drug anabolic treatment can help improve bone regeneration in prolonged disuse cases. - Highlights: • OFS stress transmits anabolic signals to osteoblasts. • Actin and tubulin fibers are rearranged under OFS stress. • OFS stress increases mitochondrial metabolism and proliferation. • Reduced RANKL/OPG ratio in response to OFS inhibits osteoclastogenesis. • OFS stress prevents apoptosis and stimulates ALP and OCN.

  10. Lumbar compression fractures secondary to lap-belt use in children.

    PubMed

    Sturm, P F; Glass, R B; Sivit, C J; Eichelberger, M R

    1995-01-01

    The correlation between flexion-distraction injuries and lap-belt use has been well documented. Over a 10-year period, we identified seven children admitted to Children's National Medical Center, Washington, DC, with compression fractures of the lumbar spine secondary to lap-belt use. Four were rear seat passengers, and three were in the front seat. The average age was 7 years. Four of the seven (57%) suffered associated abdominal injuries. One died of an associated head injury. We hypothesize that the mechanism of injury in these cases was similar to that in flexion-distraction injuries. The increased elasticity in the posterior ligamentous complex in children may be responsible for the occurrence of these compression fractures rather than the expected flexion-distraction-type injuries.

  11. Ground based experiments on the growth and characterization of L-Arginine Phosphate (LAP) crystals

    NASA Technical Reports Server (NTRS)

    Rao, S. M.; Cao, C.; Batra, A. K.; Lal, R. B.; Mookherji, T. K.

    1991-01-01

    L-Arginine Phosphate (LAP) is a new nonlinear optical material with higher efficiency for harmonic generation compared to KDP. Crystals of LAP were grown in the laboratory from supersaturated solutions by temperature lowering technique. Investigations revealed the presence of large dislocation densities inside the crystals which are observed to produce refractive index changes causing damage at high laser powers. This is a result of the convection during crystal growth from supersaturated solutions. It is proposed to grow these crystals in a diffusion controlled growth condition under microgravity environment and compare the crystals grown in space with those grown on ground. Physical properties of the solutions needed for modelling of crystal growth are also presented.

  12. A Practical Engineering Approach to Predicting Fatigue Crack Growth in Riveted Lap Joints

    NASA Technical Reports Server (NTRS)

    Harris, C. E.; Piascik, R. S.; Newman, J. C., Jr.

    2000-01-01

    An extensive experimental database has been assembled from very detailed teardown examinations of fatigue cracks found in rivet holes of fuselage structural components. Based on this experimental database, a comprehensive analysis methodology was developed to predict the onset of widespread fatigue damage in lap joints of fuselage structure. Several computer codes were developed with specialized capabilities to conduct the various analyses that make up the comprehensive methodology. Over the past several years, the authors have interrogated various aspects of the analysis methods to determine the degree of computational rigor required to produce numerical predictions with acceptable engineering accuracy. This study led to the formulation of a practical engineering approach to predicting fatigue crack growth in riveted lap joints. This paper describes the practical engineering approach and compares predictions with the results from several experimental studies.

  13. Investigation of defect rate of lap laser welding of stainless steel railway vehicles car body

    NASA Astrophysics Data System (ADS)

    Wang, Hongxiao

    2015-02-01

    In order to resolve the disadvantages such as poor appearance quality, poor tightness, low efficiency of resistance spot welding of stainless steel rail vehicles, partial penetration lap laser welding process was investigated widely. But due to the limitation of processing technology, there will be local incomplete fusion in the lap laser welding seam. Defect rate is the ratio of the local incomplete fusion length to the weld seam length. The tensile shear strength under different defect rate and its effect on the car body static strength are not clear. It is necessary to find the biggest defect rate by numerical analysis of effects of different defect rates on the laser welding stainless steel rail vehicle body structure strength ,and tests of laser welding shear tensile strength.

  14. Polyamines and plant stress - Activation of putrescine biosynthesis by osmotic shock

    NASA Technical Reports Server (NTRS)

    Flores, H. E.; Galston, A. W.

    1982-01-01

    The putrescine content of oat leaf cells and protoplasts increases up to 60-fold within 6 hours of exposure to osmotic stress (0.4 to 0.6 molar sorbitol). Barley, corn, wheat, and wild oat leaves show a similar response. Increased arginine decarboxylase activity parallels the rise in putrescine, whereas ornithine decarboxylase remains unchanged. DL-alpha-Difluoromethylarginine, a specific irreversible inhibitor of arginine decarboxylase, prevents the stress-induced rise in increase in arginine decarboxylase activity and putrescine synthesis, indicating the preferential activation of this pathway.

  15. Tyrosine nitration provokes inhibition of sunflower carbonic anhydrase (β-CA) activity under high temperature stress.

    PubMed

    Chaki, Mounira; Carreras, Alfonso; López-Jaramillo, Javier; Begara-Morales, Juan C; Sánchez-Calvo, Beatriz; Valderrama, Raquel; Corpas, Francisco J; Barroso, Juan B

    2013-02-28

    Protein tyrosine nitration is a post-translational modification (PTM) mediated by reactive nitrogen species (RNS) and it is a new area of research in higher plants. Previously, it was demonstrated that the exposition of sunflower (Helianthus annuus L.) seedlings to high temperature (HT) caused both oxidative and nitrosative stress. The nitroproteome analysis under this stress condition showed the induction of 13 tyrosine-nitrated proteins being the carbonic anhydrase (CA) one of these proteins. The analysis of CA activity under high temperature showed that this stress inhibited the CA activity by a 43%. To evaluate the effect of nitration on the CA activity in sunflower it was used 3-morpholinosydnonimine (SIN-1) (peroxynitrite donor) as the nitrating agent. Thus the CA activity was inhibited by 41%. In silico analysis of the pea CA protein sequence suggests that Tyr(205) is the most likely potential target for nitration.

  16. A Stress-Activated Transposon in Arabidopsis Induces Transgenerational Abscisic Acid Insensitivity

    PubMed Central

    Ito, Hidetaka; Kim, Jong-Myong; Matsunaga, Wataru; Saze, Hidetoshi; Matsui, Akihiro; Endo, Takaho A.; Harukawa, Yoshiko; Takagi, Hiroki; Yaegashi, Hiroki; Masuta, Yukari; Masuda, Seiji; Ishida, Junko; Tanaka, Maho; Takahashi, Satoshi; Morosawa, Taeko; Toyoda, Tetsuro; Kakutani, Tetsuji; Kato, Atsushi; Seki, Motoaki

    2016-01-01

    Transposable elements (TEs), or transposons, play an important role in adaptation. TE insertion can affect host gene function and provides a mechanism for rapid increases in genetic diversity, particularly because many TEs respond to environmental stress. In the current study, we show that the transposition of a heat-activated retrotransposon, ONSEN, generated a mutation in an abscisic acid (ABA) responsive gene, resulting in an ABA-insensitive phenotype in Arabidopsis, suggesting stress tolerance. Our results provide direct evidence that a transposon activated by environmental stress could alter the genome in a potentially positive manner. Furthermore, the ABA-insensitive phenotype was inherited when the transcription was disrupted by an ONSEN insertion, whereas ABA sensitivity was recovered when the effects of ONSEN were masked by IBM2. These results suggest that epigenetic mechanisms in host plants typically buffered the effect of a new insertion, but could selectively “turn on” TEs when stressed. PMID:26976262

  17. Low frequency ultrasonic nondestructive inspection of aluminum/adhesive fuselage lap splices

    SciTech Connect

    Patton, T.

    1994-01-04

    This thesis is a collection of research efforts in ultrasonics, conducted at the Center for Aviation Systems Reliability located at Iowa State University, as part of the Federal Aviation Administration`s ``Aging Aircraft Program.`` The research was directed toward the development of an ultrasonic prototype to inspect the aluminum/adhesive fuselage lap splices found on 1970`s vintage Boeing passenger aircraft. The ultrasonic prototype consists of a normal incidence, low frequency inspection technique, and a scanning adapter that allows focused immersion transducers to be operated in a direct contact manner in any inspection orientation, including upside-down. The inspection technique uses a computer-controlled data acquisition system to produce a C-scan image of a radio frequency (RF) waveform created by a low frequency, broadband, focused beam transducer, driven with a spike voltage pulser. C-scans produced by this technique are color representations of the received signal`s peak-to-peak amplitude (voltage) taken over an (x, y) grid. Low frequency, in this context, refers to a wavelength that is greater than the lap splice`s layer thicknesses. With the low frequency technique, interface echoes of the lap splice are not resolved and gating of the signal is unnecessary; this in itself makes the technique simple to implement and saves considerable time in data acquisition. Along with the advantages in data acquisition, the low frequency technique is relatively insensitive to minor surface curvature and to ultrasonic interference effects caused by adhesive bondline thickness variations in the lap splice.

  18. Evaluation of the fuselage lap joint fatigue and terminating action repair

    NASA Technical Reports Server (NTRS)

    Samavedam, Gopal; Thomson, Douglas; Jeong, David Y.

    1994-01-01

    Terminating action is a remedial repair which entails the replacement of shear head countersunk rivets with universal head rivets which have a larger shank diameter. The procedure was developed to eliminate the risk of widespread fatigue damage (WFD) in the upper rivet row of a fuselage lap joint. A test and evaluation program has been conducted by Foster-Miller, Inc. (FMI) to evaluate the terminating action repair of the upper rivet row of a commercial aircraft fuselage lap splice. Two full scale fatigue tests were conducted on fuselage panels using the growth of fatigue cracks in the lap joint. The second test was performed to evaluate the effectiveness of the terminating action repair. In both tests, cyclic pressurization loading was applied to the panels while crack propagation was recorded at all rivet locations at regular intervals to generate detailed data on conditions of fatigue crack initiation, ligament link-up, and fuselage fracture. This program demonstrated that the terminating action repair substantially increases the fatigue life of a fuselage panel structure and effectively eliminates the occurrence of cracking in the upper rivet row of the lap joint. While high cycle crack growth was recorded in the middle rivet row during the second test, failure was not imminent when the test was terminated after cycling to well beyond the service life. The program also demonstrated that the initiation, propagation, and linkup of WFD in full-scale fuselage structures can be simulated and quantitatively studied in the laboratory. This paper presents an overview of the testing program and provides a detailed discussion of the data analysis and results. Crack distribution and propagation rates and directions as well as frequency of cracking are presented for both tests. The progression of damage to linkup of adjacent cracks and to eventual overall panel failure is discussed. In addition, an assessment of the effectiveness of the terminating action repair and the

  19. Lap time variation and executive function in older adults: the Baltimore Longitudinal Study of Aging

    PubMed Central

    Tian, Qu; Simonsick, Eleanor M.; Resnick, Susan M.; Shardell, Michelle D.; Ferrucci, Luigi; Studenski, Stephanie A.

    2015-01-01

    Background: poor cognitive and motor performance predicts neurological dysfunction. Variable performance may be a subclinical indicator of emerging neurological problems. Objective: examine the cross-sectional association between a clinically accessible measure of variable walking and executive function. Methods: older adults aged 60 or older from the Baltimore Longitudinal Study of Aging (n = 811) with data on the 400-m walk test and cognition. Based on ten 40-m laps, we calculated mean lap time (MLT) and variation in time across ten 40-m laps (lap time variation, LTV). Executive function tests assessed attention and short-term memory (digit span forward and backward), psychomotor speed [Trail Making Test (TMT) part A] and multicomponent tasks requiring cognitive flexibility [TMT part B, part B-A (Delta TMT) and digit symbol substitution test (DSST)]. Multivariate linear regression analysis examined the cross-sectional association between LTV and executive function, adjusted for MLT, age, sex and education, as well as the LTV × MLT interaction. Results: the LTV was univariately associated with all executive function tests except digit span (P < 0.001); after adjustment, the association with TMT part A remained (standardised β = 0.142, P = 0.002). There was an interaction between MLT and LTV; among fast walkers, greater LTV was associated with a greater Delta TMT (β for LTV × MLT = −1.121, P = 0.016) after adjustment. Conclusion: at any walking speed, greater LTV is associated with psychomotor slowing. Among persons with faster walking speed, variation is associated with worse performance on a complex measure of cognitive flexibility. A simple measure of variability in walking time is independently associated with psychomotor slowing. PMID:26082177

  20. A Single-Lap Joint Adhesive Bonding Optimization Method Using Gradient and Genetic Algorithms

    NASA Technical Reports Server (NTRS)

    Smeltzer, Stanley S., III; Finckenor, Jeffrey L.

    1999-01-01

    A natural process for any engineer, scientist, educator, etc. is to seek the most efficient method for accomplishing a given task. In the case of structural design, an area that has a significant impact on the structural efficiency is joint design. Unless the structure is machined from a solid block of material, the individual components which compose the overall structure must be joined together. The method for joining a structure varies depending on the applied loads, material, assembly and disassembly requirements, service life, environment, etc. Using both metallic and fiber reinforced plastic materials limits the user to two methods or a combination of these methods for joining the components into one structure. The first is mechanical fastening and the second is adhesive bonding. Mechanical fastening is by far the most popular joining technique; however, in terms of structural efficiency, adhesive bonding provides a superior joint since the load is distributed uniformly across the joint. The purpose of this paper is to develop a method for optimizing single-lap joint adhesive bonded structures using both gradient and genetic algorithms and comparing the solution process for each method. The goal of the single-lap joint optimization is to find the most efficient structure that meets the imposed requirements while still remaining as lightweight, economical, and reliable as possible. For the single-lap joint, an optimum joint is determined by minimizing the weight of the overall joint based on constraints from adhesive strengths as well as empirically derived rules. The analytical solution of the sin-le-lap joint is determined using the classical Goland-Reissner technique for case 2 type adhesive joints. Joint weight minimization is achieved using a commercially available routine, Design Optimization Tool (DOT), for the gradient solution while an author developed method is used for the genetic algorithm solution. Results illustrate the critical design variables

  1. Spatial distribution of low energy plasma at comet 67P from Rosetta RPC-LAP measurements

    NASA Astrophysics Data System (ADS)

    Edberg, Niklas J. T.; Eriksson, Anders I.; Odelstad, Elias; Vigren, Erik; Henri, Pierre; Lebreton, Jean-Pierre; Mandt, Kathleen; Nilsson, Hans; Carr, Chris; Cupido, Emanuele; Vallat, Claire; Altwegg, Kathrin

    2015-04-01

    We present in situ measurements of the low energy plasma environment around comet 67P from the two Langmuir probes (LAP) on the Rosetta spacecraft, which form part of the Rosetta plasma consortium (RPC). RPC-LAP has operated almost continuously as Rosetta has orbited the comet at close distance (10-30 km) at low velocity (about 1 m/s) since August 2014. Using the RPC-LAP measurements we have produced global maps of the low energy plasma in the vicinity of 67P. Initial estimates indicate that the plasma density has reached values of several 100 cm^-3 and that the electron temperature has typically been in the range 5-10 eV, when the comet was beyond 2.5 AU from the sun. Photoionisation is the dominating process for producing the plasma around the comet while charge-exchange and impact ionisation may also contribute. The plasma environment has been found to be strongly coupled to the local neutral gas density, which in turn is coupled to which area on the comet is facing the sun. The northern summer neck-area of the comet outgasses more than other areas and above this region are the highest densities observed. In the southern winter and above the two main lobes of the comet body, the plasma density is lower. The plasma density is hence not determined by the solar wind, but by the outgassing from the comet. The 12.4-hour rotation period of the comet together with the varying latitude of the slow-moving Rosetta provide strong modulation of the RPC-LAP measurements. Besides orbiting the comet, Rosetta will also perform flybys of the comet in early 2015 when Rosetta will move to distances of several hundred kilometres from the nucleus. These flybys provide a cut-through view of the near-comet plasma environment, which will possibly give some insight to the solar-wind interaction with the cometary coma.

  2. Early evolution of comet 67P studied with the RPC-LAP onboard Rosetta

    NASA Astrophysics Data System (ADS)

    Miloch, Wojciech; Edberg, Niklas J. T.; Eriksson, Anders I.; Yang, Lei; Paulsson, Joakim J. P.; Wedlund, Cyril Simon; Odelstad, Elias

    2016-07-01

    The Rosetta mission provides the in-situ measurements of a comet that are closest to a comet's aphelion ever made. The Rosetta Plasma Consortium (RPC) is a set of five instruments on board the spacecraft that specialise in the measurements of the plasma environment of comet 67P. One of the instruments is RPC-LAP, which consists of two Langmuir Probes and can measure the density, temperature, and flow speed of the plasma in the vicinity of the comet. At the early stage of the Rosetta mission, when the spacecraft is far from the nucleus of comet 67P, the ion part of the current-voltage characteristics of RPC-LAP1 is dominated by the photoemission current which surpasses the currents from the dilute solar wind plasma. As Rosetta starts orbiting around the nucleus in September 2014, LAP1 picks up signatures of local plasma density enhancements corresponding to variations of water-group ions observed in the vicinity of the comet. With the help of current-voltage characteristics and the spacecraft potential, we identify and characterise in space and time the entering of this coma-dominated plasma. In particular we determine the transition for entering the ion dominated region characterised by the 6-hour variations in the local plasma density due to the comet rotation. This transition manifests as a steep gradient in the density with respect to the distance to the comet nucleus. We discuss these RPC-LAP results together with the corresponding measurements by other instruments to provide a comprehensive picture of the transition.

  3. Activity of earthworm in Latosol under simulated acid rain stress.

    PubMed

    Zhang, Jia-En; Yu, Jiayu; Ouyang, Ying

    2015-01-01

    Acid rain is still an issue of environmental concerns. This study investigated the impacts of simulated acid rain (SAR) upon earthworm activity from the Latosol (acidic red soil). Laboratory experiment was performed by leaching the soil columns grown with earthworms (Eisenia fetida) at the SAR pH levels ranged from 2.0 to 6.5 over a 34-day period. Results showed that earthworms tended to escape from the soil and eventually died for the SAR at pH = 2.0 as a result of acid toxicity. The catalase activity in the earthworms decreased with the SAR pH levels, whereas the superoxide dismutases activity in the earthworms showed a fluctuate pattern: decreasing from pH 6.5 to 5.0 and increasing from pH 5.0 to 4.0. Results implied that the growth of earthworms was retarded at the SAR pH ≤ 3.0.

  4. PIM1 destabilization activates a p53-dependent response to ribosomal stress in cancer cells

    PubMed Central

    Sagar, Vinay; Caldarola, Sara; Aria, Valentina; Monteleone, Valentina; Fuoco, Claudia; Gargioli, Cesare; Cannata, Stefano; Loreni, Fabrizio

    2016-01-01

    Defects in ribosome biogenesis triggers a stress response (ribosomal stress) that can lead to growth arrest and apoptosis. Signaling pathways activated by ribosomal stress are specifically involved in the pathological mechanism of a group of disorders defined as ribosomopathies. However, more generally, the quality control of ribosome synthesis is part of the regulatory circuits that control cell metabolism. A number of studies identified tumor suppressor p53 as a central player in ribosomal stress. We have previously reported that the kinase PIM1 plays a role as a sensor for ribosome deficiency. In this report we address the relationship between PIM1 and p53 in cancer cell lines after depletion of a ribosomal protein. We identified a novel signaling pathway that includes the kinase AKT and the ubiquitin ligase MDM2. In fact, our results indicate that the lower level of PIM1, induced by ribosomal stress, causes inactivation of AKT, inhibition of MDM2 and a consequent p53 stabilization. Therefore, we propose that activation of p53 in response to ribosomal stress, is dependent on the pathway PIM1-AKT-MDM2. In addition, we report evidence that PIM1 level may be relevant to assess the sensitivity of cancer cells to chemotherapeutic drugs that induce ribosomal stress. PMID:26993775

  5. Stress-induced enhancement of leukocyte trafficking into sites of surgery or immune activation

    NASA Astrophysics Data System (ADS)

    Viswanathan, Kavitha; Dhabhar, Firdaus S.

    2005-04-01

    Effective immunoprotection requires rapid recruitment of leukocytes into sites of surgery, wounding, infection, or vaccination. In contrast to immunosuppressive chronic stressors, short-term acute stressors have immunoenhancing effects. Here, we quantify leukocyte infiltration within a surgical sponge to elucidate the kinetics, magnitude, subpopulation, and chemoattractant specificity of an acute stress-induced increase in leukocyte trafficking to a site of immune activation. Mice acutely stressed before sponge implantation showed 200-300% higher neutrophil, macrophage, natural killer cell, and T cell infiltration than did nonstressed animals. We also quantified the effects of acute stress on lymphotactin- (LTN; a predominantly lymphocyte-specific chemokine), and TNF-- (a proinflammatory cytokine) stimulated leukocyte infiltration. An additional stress-induced increase in infiltration was observed for neutrophils, in response to TNF-, macrophages, in response to TNF- and LTN, and natural killer cells and T cells in response to LTN. These results show that acute stress initially increases trafficking of all major leukocyte subpopulations to a site of immune activation. Tissue damage-, antigen-, or pathogen-driven chemoattractants subsequently determine which subpopulations are recruited more vigorously. Such stress-induced increases in leukocyte trafficking may enhance immunoprotection during surgery, vaccination, or infection, but may also exacerbate immunopathology during inflammatory (cardiovascular disease or gingivitis) or autoimmune (psoriasis, arthritis, or multiple sclerosis) diseases. chemokine | psychophysiological stress | surgical sponge | wound healing | lymphotactin

  6. PIM1 destabilization activates a p53-dependent response to ribosomal stress in cancer cells.

    PubMed

    Sagar, Vinay; Caldarola, Sara; Aria, Valentina; Monteleone, Valentina; Fuoco, Claudia; Gargioli, Cesare; Cannata, Stefano; Loreni, Fabrizio

    2016-04-26

    Defects in ribosome biogenesis triggers a stress response (ribosomal stress) that can lead to growth arrest and apoptosis. Signaling pathways activated by ribosomal stress are specifically involved in the pathological mechanism of a group of disorders defined as ribosomopathies. However, more generally, the quality control of ribosome synthesis is part of the regulatory circuits that control cell metabolism. A number of studies identified tumor suppressor p53 as a central player in ribosomal stress. We have previously reported that the kinase PIM1 plays a role as a sensor for ribosome deficiency. In this report we address the relationship between PIM1 and p53 in cancer cell lines after depletion of a ribosomal protein. We identified a novel signaling pathway that includes the kinase AKT and the ubiquitin ligase MDM2. In fact, our results indicate that the lower level of PIM1, induced by ribosomal stress, causes inactivation of AKT, inhibition of MDM2 and a consequent p53 stabilization. Therefore, we propose that activation of p53 in response to ribosomal stress, is dependent on the pathway PIM1-AKT-MDM2. In addition, we report evidence that PIM1 level may be relevant to assess the sensitivity of cancer cells to chemotherapeutic drugs that induce ribosomal stress. PMID:26993775

  7. Eomesodermin, HAND1, and CSH1 proteins are induced by cellular stress in a stress-activated protein kinase-dependent manner.

    PubMed

    Awonuga, A O; Zhong, W; Abdallah, M E; Slater, J A; Zhou, S C; Xie, Y F; Puscheck, E E; Rappolee, D A

    2011-07-01

    Eomesodermin (Eomes) is a transcription factor essential for trophoblast development. Stress stimuli activate stress-activated protein kinase (MAPK8/9) and modulate transcription factors in trophoblast stem cells (TSC). In this study, we test the hypothesis that stress-induced Eomes upregulation and downstream trophoblast development are MAPK8/9-dependent. Immunocytochemical and immunoblot assays suggest that Eomes is induced by hyperosmolar stress in a dose- and time-dependent manner. Two MAPK8/9 inhibitors that work by different mechanisms, LJNKl1 and SP600125, block induction of Eomes protein by stress. During normal TSC differentiation, the transcription factor heart and neural crest derivatives expressed 1 (HAND1) is dependent on Eomes, and chorionic somatomammotropin hormone 1 (CSH1) expression is dependent on HAND1. Similar to Eomes, HAND1 and CSH1 induction by stress are MAPK8/9-dependent, and CSH1 is induced in nearly all stressed TSC. CSH1 induction normally requires downregulation of the transcription factor inhibitor of differentiation 2 (ID2) as well as HAND1 upregulation. It was shown previously that hyperosmolar stress induces AMP-activated protein kinase (PRKAA1/2)-dependent ID2 loss in a MAPK8/9-independent manner. Inhibition of PRKAA1/2 with compound C and LJNKl1, more than MAPK8/9 inhibitors alone, inhibits the induction of CSH1 by stress. Taken together these data suggest that stress-induced MAPK8/9 and PRKAA1/2 regulate transcription factors Eomes/HAND1 and ID2, respectively. Together this network mediates induction of CSH1 by stress. Therefore, stress triggers a proportional increase in a normal early TSC differentiation event that could be adaptive in inducing CSH1. But the flexibility of TSC to undergo stress-induced differentiation could lead to pathophysiological consequences if stress endured and TSC differentiation became unbalanced.

  8. In Situ Measurement of Voltage-Induced Stress in Conducting Polymers with Redox-Active Dopants.

    PubMed

    Sen, Sujat; Kim, Sung Yeol; Palmore, Lia R; Jin, Shenghua; Jadhav, Nitin; Chason, Eric; Palmore, G Tayhas R

    2016-09-14

    Minimization of stress-induced mechanical rupture and delamination of conducting polymer (CP) films is desirable to prevent failure of devices based on these materials. Thus, precise in situ measurement of voltage-induced stress within these films should provide insight into the cause of these failure mechanisms. The evolution of stress in films of polypyrrole (pPy), doped with indigo carmine (IC), was measured in different electrochemical environments using the multibeam optical stress sensor (MOSS) technique. The stress in these films gradually increases to a constant value during voltage cycling, revealing an initial break-in period for CP films. The nature of the ions involved in charge compensation of pPy[IC] during voltage cycling was determined from electrochemical quartz crystal microbalance (EQCM) data. The magnitude of the voltage-induced stress within pPy[IC] at neutral pH correlated with the radius of the hydrated mobile ion in the order Li(+) > Na(+) > K(+). At acidic pH, the IC dopant in pPy[IC] undergoes reversible oxidation and reduction within the range of potentials investigated, providing a secondary contribution to the observed voltage-induced stress. We report on the novel stress response of these polymers due to the presence of pH-dependent redox-active dopants and how it can affect material performance.

  9. Shear stress reduces protease activated receptor-1 expression in human endothelial cells

    NASA Technical Reports Server (NTRS)

    Nguyen, K. T.; Eskin, S. G.; Patterson, C.; Runge, M. S.; McIntire, L. V.

    2001-01-01

    Shear stress has been shown to regulate several genes involved in the thrombotic and proliferative functions of endothelial cells. Thrombin receptor (protease-activated receptor-1: PAR-1) increases at sites of vascular injury, which suggests an important role for PAR-1 in vascular diseases. However, the effect of shear stress on PAR-1 expression has not been previously studied. This work investigates effects of shear stress on PAR-1 gene expression in both human umbilical vein endothelial cells (HUVECs) and microvascular endothelial cells (HMECs). Cells were exposed to different shear stresses using a parallel plate flow system. Northern blot and flow cytometry analysis showed that shear stress down-regulated PAR-1 messenger RNA (mRNA) and protein levels in both HUVECs and HMECs but with different thresholds. Furthermore, shear-reduced PAR-1 mRNA was due to a decrease of transcription rate, not increased mRNA degradation. Postshear stress release of endothelin-1 in response to thrombin was reduced in HUVECs and HMECs. Moreover, inhibitors of potential signaling pathways applied during shear stress indicated mediation of the shear-decreased PAR-1 expression by protein kinases. In conclusion, shear stress exposure reduces PAR-1 gene expression in HMECs and HUVECs through a mechanism dependent in part on protein kinases, leading to altered endothelial cell functional responses to thrombin.

  10. Acute Restraint Stress Enhances Hippocampal Endocannabinoid Function via Glucocorticoid Receptor Activation

    PubMed Central

    Wang, Meina; Hill, Matthew N.; Zhang, Longhua; Gorzalka, Boris B.; Hillard, Cecilia J.; Alger, Bradley E.

    2012-01-01

    Exposure to behavioral stress normally triggers a complex, multi-level response of the hypothalamic-pituitary-adrenal (HPA) axis that helps maintain homeostatic balance. Although the endocannabinoid (eCB) system (ECS) is sensitive to chronic stress, few studies have directly addressed its response to acute stress. Here we show that acute restraint stress enhances eCB-dependent modulation of GABA release measured by whole-cell voltage clamp of inhibitory post-synaptic currents (IPSCs) in rat hippocampal CA1 pyramidal cells in vitro. Both Ca2+-dependent, eCB-mediated depolarization-induced suppression of inhibition (DSI), and muscarinic cholinergic receptor (mAChR) mediated eCB mobilization are enhanced following acute stress exposure. DSI enhancement is dependent on the activation of glucocorticoid receptors (GRs) and is mimicked by both in vivo and in vitro corticosterone treatment. This effect does not appear to involve cyclooxygenase-2 (COX-2), an enzyme that can degrade eCBs; however, treatment of hippocampal slices with the L-type calcium (Ca2+) channel inhibitor, nifedipine, reverses while an agonist of these channels mimics the effect of in vivo stress. Finally, we find that acute stress produces a delayed (by 30 min) increase in the hippocampal content of 2-arachidonoylglycerol, the eCB responsible for DSI. These results support the hypothesis that the ECS is a biochemical effector of glucocorticoids in the brain, linking stress with changes in synaptic strength. PMID:21890595

  11. In Situ Measurement of Voltage-Induced Stress in Conducting Polymers with Redox-Active Dopants.

    PubMed

    Sen, Sujat; Kim, Sung Yeol; Palmore, Lia R; Jin, Shenghua; Jadhav, Nitin; Chason, Eric; Palmore, G Tayhas R

    2016-09-14

    Minimization of stress-induced mechanical rupture and delamination of conducting polymer (CP) films is desirable to prevent failure of devices based on these materials. Thus, precise in situ measurement of voltage-induced stress within these films should provide insight into the cause of these failure mechanisms. The evolution of stress in films of polypyrrole (pPy), doped with indigo carmine (IC), was measured in different electrochemical environments using the multibeam optical stress sensor (MOSS) technique. The stress in these films gradually increases to a constant value during voltage cycling, revealing an initial break-in period for CP films. The nature of the ions involved in charge compensation of pPy[IC] during voltage cycling was determined from electrochemical quartz crystal microbalance (EQCM) data. The magnitude of the voltage-induced stress within pPy[IC] at neutral pH correlated with the radius of the hydrated mobile ion in the order Li(+) > Na(+) > K(+). At acidic pH, the IC dopant in pPy[IC] undergoes reversible oxidation and reduction within the range of potentials investigated, providing a secondary contribution to the observed voltage-induced stress. We report on the novel stress response of these polymers due to the presence of pH-dependent redox-active dopants and how it can affect material performance. PMID:27579593

  12. Beller Lectureship Talk: Active response of biological cells to mechanical stress

    NASA Astrophysics Data System (ADS)

    Safran, Samuel

    2009-03-01

    Forces exerted by and on adherent cells are important for many physiological processes such as wound healing and tissue formation. In addition, recent experiments have shown that stem cell differentiation is controlled, at least in part, by the elasticity of the surrounding matrix. We present a simple and generic theoretical model for the active response of biological cells to mechanical stress. The theory includes cell activity and mechanical forces as well as random forces as factors that determine the polarizability that relates cell orientation to stress. This allows us to explain the puzzling observation of parallel (or sometimes random) alignment of cells for static and quasi-static stresses and of nearly perpendicular alignment for dynamically varying stresses. In addition, we predict the response of the cellular orientation to a sinusoidally varying applied stress as a function of frequency and compare the theory with recent experiments. The dependence of the cell orientation angle on the Poisson ratio of the surrounding material distinguishes cells whose activity is controlled by stress from those controlled by strain. We have extended the theory to generalize the treatment of elastic inclusions in solids to ''living'' inclusions (cells) whose active polarizability, analogous to the polarizability of non-living matter, results in the feedback of cellular forces that develop in response to matrix stresses. We use this to explain recent observations of the non-monotonic dependence of stress-fiber polarization in stem cells on matrix rigidity. These findings provide a mechanical correlate for the existence of an optimal substrate elasticity for cell differentiation and function. [3pt] *In collaboration with R. De (Brown University), Y. Biton (Weizmann Institute), and A. Zemel (Hebrew University) and the experimental groups: Max Planck Institute, Stuttgart: S. Jungbauer, R. Kemkemer, J. Spatz; University of Pennsylvania: A. Brown, D. Discher, F. Rehfeldt.

  13. 17β-estradiol differentially regulates stress circuitry activity in healthy and depressed women.

    PubMed

    Jacobs, Emily G; Holsen, Laura M; Lancaster, Katie; Makris, Nikos; Whitfield-Gabrieli, Sue; Remington, Anne; Weiss, Blair; Buka, Stephen; Klibanski, Anne; Goldstein, Jill M

    2015-02-01

    Many regions within stress neurocircuitry, including the anterior hypothalamus, amygdala, hippocampus, and medial prefrontal cortex, are densely populated with sex steroid receptors. Substantial evidence from animal studies indicates that the gonadal hormone 17β-estradiol (E₂) impacts the structure and function of these regions, but human studies are limited. Characterizing estradiol's role in stress circuitry in vivo in humans may have important clinical implications given the comorbidity between major depressive disorder (MDD), stress circuitry dysfunction and endocrine dysregulation. In this study, we determined estradiol's role in modulating activity within cortical and subcortical stress circuitry regions in healthy and MDD women. Subjects were part of a population-based birth cohort, the New England Family Study. Capitalizing on the endogenous fluctuation in E₂ during the menstrual cycle, we conducted a within-person repeated-measures functional neuroimaging study in which 15 women with recurrent MDD, in remission, and 15 healthy control women underwent hormonal evaluations, behavioral testing, and fMRI scanning on two occasions, under low and high E₂ conditions. Subjects completed an fMRI scan while undergoing a mild visual stress challenge that reliably activated stress neural circuitry. Results demonstrate that E₂ modulates activity across key stress circuitry regions, including bilateral amygdala, hippocampus, and hypothalamus. In healthy women, robust task-evoked BOLD signal changes observed under low E₂ conditions were attenuated under high E₂ conditions. This hormonal capacity to regulate activity in stress circuitry was not observed in MDD women, despite their remitted status, suggesting that dysregulation of gonadal hormone function may be a characteristic trait of the disease. These findings serve to deepen our understanding of estradiol's actions in the healthy brain and the neurobiological mechanisms that may underlie the pronounced

  14. Activity of the Hypothalamic-Pituitary-Adrenal System in Prenatally Stressed Male Rats on the Experimental Model of Post-Traumatic Stress Disorder.

    PubMed

    Pivina, S G; Rakitskaya, V V; Akulova, V K; Ordyan, N E

    2016-03-01

    Using the experimental model of post-traumatic stress disorder (stress-restress paradigm), we studied the dynamics of activity of the hypothalamic-pituitary-adrenal system (HPAS) in adult male rats, whose mothers were daily subjected to restraint stress on days 15-19 of pregnancy. Prenatally stressed males that were subjected to combined stress and subsequent restress exhibited not only increased sensitivity of HPAS to negative feedback signals (manifested under restress conditions), but also enhanced stress system reactivity. These changes persisted to the 30th day after restress. Under basal conditions, the number of cells in the hypothalamic paraventricular nucleus of these animals expressing corticotropin-releasing hormone and vasopressin was shown to decrease progressively on days 1-30. By contrast, combined stress and restress in control animals were followed by an increase in the count of CRH-immunopositive cells in the magnocellular and parvocellular parts of the paraventricular nucleus and number of vasopressin-immunopositive cells in the magnocellular part of the nucleus (to the 10th day after restress). Our results indicate a peculiar level of functional activity of HPAS in prenatally stressed males in the stress-restress paradigm: decreased activity under basal conditions and enhanced reactivity during stress.

  15. Probabilistic seismic performance assessment of lap-spliced RC columns retrofitted by steel wrapping jackets

    NASA Astrophysics Data System (ADS)

    Choi, Eunsoo; Youn, Heejung; Cho, Baik-Soon

    2016-06-01

    In this study, the seismic fragility curves of two reinforced concrete (RC) columns that were lap-spliced at the bottom and retrofitted with steel wrapping jackets were generated. Their seismic performance was probabilistically assessed in comparison to that of lap-spliced or continuous reinforcement RC columns. This study used two types of steel wrapping jackets, a full jacket and a split jacket. Analytical models of the four types of columns were developed based on the experimental results of the columns using OpenSEES, which is effective in conducting nonlinear time history analyses. A suite of ten artificial ground motions, modified from recorded ground motions, was used to perform nonlinear time history analyses of the analytical models with scaling of the peak ground acceleration from 0.1 g to 1.0 g in increments of 0.1 g. The steel wrapping jackets did not increase the medians for yield (slight damage state) of the lap-spiced column and did not exceed the corresponding median of the continuous reinforcement column. However, the two steel jackets increased the medians for failure by 1.872 and 2.017 times, respectively, and exceeded the corresponding median of the continuous reinforcement column by 11.8% and 20.5%, respectively.

  16. Enhancing pulsed eddy current for inspection of P-3 Orion lap-joint structures

    NASA Astrophysics Data System (ADS)

    Butt, D. M.; Underhill, P. R.; Krause, T. W.

    2016-02-01

    During flight, aircraft are subjected to cyclic loading. In the Lockheed P-3 Orion airframe, this cyclic loading can lead to development of fatigue cracks at steel fastener locations in the top and second layers of aluminum wing skin lap-joints. An inspection method that is capable of detecting these cracks, without fastener removal, is desirable as this can minimize aircraft downtime, while subsequently reducing the risk of collateral damage. The ability to detect second layer cracks has been demonstrated using a Pulsed Eddy Current (PEC) probe design that utilizes the ferrous fastener as a flux conduit. This allows for deeper penetration of flux into the lap-joint second layer and consequently, sensitivity to the presence of cracks. Differential pick-up coil pairs are used to sense the eddy current response due to the presence of a crack. The differential signal obtained from pick-up coils on opposing sides of the fastener is analyzed using a Modified Principal Components Analysis (MPCA). This is followed by a cluster analysis of the resulting MPCA scores to separate fastener locations with cracks from those without. Probe design features, data acquisition system parameters and signal post-processing can each have a strong impact on crack detection. Physical probe configurations and signal analysis processes, used to enhance the PEC system for detection of cracks in P-3 Orion lap-joint structures, are investigated and an enhanced probe design is identified.

  17. Stress-Activated Cap’n’collar Transcription Factors in Aging and Human Disease

    PubMed Central

    Sykiotis, Gerasimos P.; Bohmann, Dirk

    2010-01-01

    Cap’n’collar (Cnc) transcription factors are conserved in metazoans and have important developmental and homeostatic functions. The vertebrate Nrf1, Nrf2, and Nrf3, the Caenorhabditis elegans SKN-1, and the Drosophila CncC comprise a subgroup of Cnc factors that mediate adaptive responses to cellular stress. The most studied stress-activated Cnc factor is Nrf2, which orchestrates the transcriptional response of cells to oxidative stressors and electrophilic xenobiotics. In rodent models, signaling by Nrf2 defends against oxidative stress and aging-associated disorders, such as neurodegeneration, respiratory diseases, and cancer. In humans, polymorphisms that decrease Nrf2 abundance have been associated with various pathologies of the skin, respiratory system, and digestive tract. In addition to preventing disease in rodents and humans, Cnc factors have lifespan-extending and anti-aging functions in invertebrates. However, despite the pro-longevity and antioxidant roles of stress-activated Cnc factors, their activity paradoxically declines in aging model organisms and in humans suffering from progressing respiratory disease or neurodegeneration. We review the roles and regulation of stress-activated Cnc factors across species, present all reported instances in which their activity is paradoxically decreased in aging and disease, and discuss the possibility that the pharmacological restoration of Nrf2 signaling may be useful in the prevention and treatment of age-related diseases. PMID:20215646

  18. Evidence that endoplasmic reticulum (ER) stress and caspase-4 activation occur in human neutrophils.

    PubMed

    Binet, François; Chiasson, Sonia; Girard, Denis

    2010-01-01

    Apoptosis can result from activation of three major pathways: the extrinsic, the intrinsic, and the most recently identified endoplasmic reticulum (ER) stress-mediated pathway. While the two former pathways are known to be operational in human polymorphonuclear neutrophils (PMNs), the existence of the ER stress-mediated pathway, generally involving caspase-4, has never been reported in these cells. Recently, we have documented that arsenic trioxide (ATO) induced apoptosis in human PMNs by a mechanism that needs to be further investigated. In this study, using immunofluorescence and electron microscopy, we present evidence of ER alterations in PMNs activated by the ER stress inducer arsenic trioxide (ATO). Several key players of the unfolded protein response, including GRP78, GADD153, ATF6, XBP1 and eIF2alpha are expressed and activated in PMNs treated with ATO or other ER stress inducers. Although caspase-4 is expressed and activated in neutrophils, treatment with a caspase-4 inhibitor did not attenuate the pro-apoptotic effect of ATO at a concentration that reverses caspase-4 processing and activation. Our results demonstrate for the first time that the ER stress-mediated apoptotic pathway operates in human neutrophils.

  19. A tomato chloroplast-targeted DnaJ protein protects Rubisco activity under heat stress.

    PubMed

    Wang, Guodong; Kong, Fanying; Zhang, Song; Meng, Xia; Wang, Yong; Meng, Qingwei

    2015-06-01

    Photosynthesis is one of the biological processes most sensitive to heat stress in plants. Carbon assimilation, which depends on ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), is one of the major sites sensitive to heat stress in photosynthesis. In this study, the roles of a tomato (Solanum lycopersicum) chloroplast-targeted DnaJ protein (SlCDJ2) in resisting heat using sense and antisense transgenic tomatoes were examined. SlCDJ2 was found to be uniformly distributed in the thylakoids and stroma of the chloroplasts. Under heat stress, sense plants exhibited higher chlorophyll contents and fresh weights, and lower accumulation of reactive oxygen species (ROS) and membrane damage. Moreover, Rubisco activity, Rubisco large subunit (RbcL) content, and CO2 assimilation capacity were all higher in sense plants and lower in antisense plants compared with wild-type plants. Thus, SlCDJ2 contributes to maintenance of CO2 assimilation capacity mainly by protecting Rubisco activity under heat stress. SlCDJ2 probably achieves this by keeping the levels of proteolytic enzymes low, which prevents accelerated degradation of Rubisco under heat stress. Furthermore, a chloroplast heat-shock protein 70 was identified as a binding partner of SlCDJ2 in yeast two-hybrid assays. Taken together, these findings establish a role for SlCDJ2 in maintaining Rubisco activity in plants under heat stress. PMID:25801077

  20. The effect of baclofen on the locomotor activity of control and small-platform-stressed mice.

    PubMed

    Pokk, P; Vassiljev, V; Väli, M

    2000-09-01

    The effect of baclofen on the locomotor activity of control and small-platform-stressed mice was studied. In the small platform technique, mice are forced to stay on small platforms (d= 3.5 cm) surrounded by water for 24 h. Small platform stress increased the locomotor activity of mice in the actometer. Baclofen administered at doses of 0.25, 0.5 and 1.0 mg kg(-1)(i.p.) had no effect on the locomotor activity of control mice. In small-platform-stressed mice, the locomotor depressant effect of baclofen was pronounced, being statistically significant at a dose of 1.0 mg kg(-1). These data suggest that small platform stress induces hypersensitivity of mice to the motor depressant effect of baclofen. On the basis of these data it could be proposed that small platform stress induces changes in the function of GABA(B)receptors and that GABA(B)receptors participate in the behavioural changes caused by small platform stress.

  1. Ketogenic diet decreases oxidative stress and improves mitochondrial respiratory complex activity.

    PubMed

    Greco, Tiffany; Glenn, Thomas C; Hovda, David A; Prins, Mayumi L

    2016-09-01

    Cerebral metabolism of ketones after traumatic brain injury (TBI) improves neuropathology and behavior in an age-dependent manner. Neuroprotection is attributed to improved cellular energetics, although other properties contribute to the beneficial effects. Oxidative stress is responsible for mitochondrial dysfunction after TBI. Ketones decrease oxidative stress, increase antioxidants and scavenge free radicals. It is hypothesized that ketogenic diet (KD) will decrease post-TBI oxidative stress and improve mitochondria. Postnatal day 35 (PND35) male rats were given sham or controlled cortical impact (CCI) injury and placed on standard (STD) or KD. Ipsilateral cortex homogenates and mitochondria were assayed for markers of oxidative stress, antioxidant expression and mitochondrial function. Oxidative stress was significantly increased at 6 and 24 h post-injury and attenuated by KD while inducing protein expression of antioxidants, NAD(P)H dehydrogenase quinone 1 (NQO1) and superoxide dismutase (SOD1/2). Complex I activity was inhibited in STD and KD groups at 6 h and normalized by 24 h. KD significantly improved Complex II-III activity that was reduced in STD at 6 h. Activity remained reduced at 24 h in STD and unchanged in KD animals. These results strongly suggest that ketones improve post-TBI cerebral metabolism by providing alternative substrates and through antioxidant properties, preventing oxidative stress-mediated mitochondrial dysfunction.

  2. Lung cancer: what are the links with oxidative stress, physical activity and nutrition.

    PubMed

    Filaire, Edith; Dupuis, Carmen; Galvaing, Géraud; Aubreton, Sylvie; Laurent, Hélène; Richard, Ruddy; Filaire, Marc

    2013-12-01

    Oxidative stress appears to play an essential role as a secondary messenger in the normal regulation of a variety of physiological processes, such as apoptosis, survival, and proliferative signaling pathways. Oxidative stress also plays important roles in the pathogenesis of many diseases, including aging, degenerative disease, and cancer. Among cancers, lung cancer is the leading cause of cancer in the Western world. Lung cancer is the commonest fatal cancer whose risk is dependent on the number of cigarettes smoked per day as well as the number of years smoking, some components of cigarette smoke inducing oxidative stress by transmitting or generating oxidative stress. It can be subdivided into two broad categories, small cell lung cancer and non-small-cell lung cancer, the latter is the most common type. Distinct measures of primary and secondary prevention have been investigated to reduce the risk of morbidity and mortality caused by lung cancer. Among them, it seems that physical activity and nutrition have some beneficial effects. However, physical activity can have different influences on carcinogenesis, depending on energy supply, strength and frequency of exercise loads as well as the degree of exercise-mediated oxidative stress. Micronutrient supplementation seems to have a positive impact in lung surgery, particularly as an antioxidant, even if the role of micronutrients in lung cancer remains controversial. The purpose of this review is to examine lung cancer in relation to oxidative stress, physical activity, and nutrition.

  3. A tomato chloroplast-targeted DnaJ protein protects Rubisco activity under heat stress.

    PubMed

    Wang, Guodong; Kong, Fanying; Zhang, Song; Meng, Xia; Wang, Yong; Meng, Qingwei

    2015-06-01

    Photosynthesis is one of the biological processes most sensitive to heat stress in plants. Carbon assimilation, which depends on ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), is one of the major sites sensitive to heat stress in photosynthesis. In this study, the roles of a tomato (Solanum lycopersicum) chloroplast-targeted DnaJ protein (SlCDJ2) in resisting heat using sense and antisense transgenic tomatoes were examined. SlCDJ2 was found to be uniformly distributed in the thylakoids and stroma of the chloroplasts. Under heat stress, sense plants exhibited higher chlorophyll contents and fresh weights, and lower accumulation of reactive oxygen species (ROS) and membrane damage. Moreover, Rubisco activity, Rubisco large subunit (RbcL) content, and CO2 assimilation capacity were all higher in sense plants and lower in antisense plants compared with wild-type plants. Thus, SlCDJ2 contributes to maintenance of CO2 assimilation capacity mainly by protecting Rubisco activity under heat stress. SlCDJ2 probably achieves this by keeping the levels of proteolytic enzymes low, which prevents accelerated degradation of Rubisco under heat stress. Furthermore, a chloroplast heat-shock protein 70 was identified as a binding partner of SlCDJ2 in yeast two-hybrid assays. Taken together, these findings establish a role for SlCDJ2 in maintaining Rubisco activity in plants under heat stress.

  4. Loss of the oxidative stress sensor NPGPx compromises GRP78 chaperone activity and induces systemic disease

    PubMed Central

    Wei, Pei-Chi; Hsieh, Yi-Hsuan; Su, Mei-I; Jiang, X-J; Hsu, Pang-Hung; Lo, Wen-Ting; Jeng, Yung-Ming; Wang, Ju-Ming; Chen, Phang-lang; Chang, Yi-Cheng; Lee, Kuo-Fen; Tsai, Ming-Daw; Shew, Jin-Yuh; Lee, Wen-Hwa

    2013-01-01

    Summary NPGPx is a member of the glutathione peroxidase (GPx) family; however, it lacks GPx enzymatic activity due to the absence of a critical selenocysteine residue, rendering its function an enigma. We report that NPGPx is a novel stress sensor that transmits oxidative stress signals by transferring the disulfide bond between its Cys57 and Cys86 residues to downstream effectors. Oxidized NPGPx binds and oxidizes the chaperone glucose-regulated protein (GRP)78 in the endoplasmic reticulum through covalent bonding between Cys86 of NPGPx and Cys41/Cys420 of GRP78, and facilitates the refolding of misfolded proteins by GRP78 to alleviate stress. NPGPx-deficient cells display impaired GRP78 chaperone activity, accumulate misfolded proteins, and suffer oxidative stress. Complete loss of NPGPx in animals causes systemic oxidative stress, increases carcinogenesis, and shortens lifespan. These results, for the first time, suggest that NPGPx is essential for mediating the oxidative stress response by modulating GRP78 chaperone activity to maintain physiological homeostasis. PMID:23123197

  5. Lung cancer: what are the links with oxidative stress, physical activity and nutrition.

    PubMed

    Filaire, Edith; Dupuis, Carmen; Galvaing, Géraud; Aubreton, Sylvie; Laurent, Hélène; Richard, Ruddy; Filaire, Marc

    2013-12-01

    Oxidative stress appears to play an essential role as a secondary messenger in the normal regulation of a variety of physiological processes, such as apoptosis, survival, and proliferative signaling pathways. Oxidative stress also plays important roles in the pathogenesis of many diseases, including aging, degenerative disease, and cancer. Among cancers, lung cancer is the leading cause of cancer in the Western world. Lung cancer is the commonest fatal cancer whose risk is dependent on the number of cigarettes smoked per day as well as the number of years smoking, some components of cigarette smoke inducing oxidative stress by transmitting or generating oxidative stress. It can be subdivided into two broad categories, small cell lung cancer and non-small-cell lung cancer, the latter is the most common type. Distinct measures of primary and secondary prevention have been investigated to reduce the risk of morbidity and mortality caused by lung cancer. Among them, it seems that physical activity and nutrition have some beneficial effects. However, physical activity can have different influences on carcinogenesis, depending on energy supply, strength and frequency of exercise loads as well as the degree of exercise-mediated oxidative stress. Micronutrient supplementation seems to have a positive impact in lung surgery, particularly as an antioxidant, even if the role of micronutrients in lung cancer remains controversial. The purpose of this review is to examine lung cancer in relation to oxidative stress, physical activity, and nutrition. PMID:24161719

  6. Active Hexose Correlated Compound Activates Immune Function to Decrease Chlamydia trachomatis Shedding in a Murine Stress Model

    PubMed Central

    Belay, Tesfaye; Fu, Chih-lung; Woart, Anthony

    2016-01-01

    A cold-induced stress mouse model for investigating chlamydia genital infection and immune response analysis was established in our laboratory. Previous results showed that cold-induced stress results in suppression of the immune response and increased intensity of chlamydia genital infection in the mouse model. The purpose of the present study was to evaluate the potential therapeutic value of active hexose correlated compound (AHCC) against chlamydia genital infection in mice. AHCC is an extract of mushroom commonly used as a dietary supplement is known to boost the immune system. Mice were infected intravaginally with Chlamydia trachomatis after a 24-day cold-stress application. Oral administration of AHCC to stressed or non-stressed mice was carried out seven days before infection and during the course of infection along with cervicovaginal swabbing. Cytokine production by peritoneal and splenic T cells isolated from AHCC-fed stressed mice and non-stressed mice was measured ELISA. Splenic T cells from both animal groups were co-cultured with mouse monocyte J774.2 cell line or cultured by addition of supernatants of AHCC-treated J774.2 cell line for 24 hours. Infection studies showed that AHCC-feeding compared to phosphate buffered saline (PBS)-feeding to stressed mice resulted in reduced Chlamydia trachomatis shedding from the genital tract. Levels of tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6) were significantly increased in stressed mice receiving AHCC compared to stressed mice receiving PBS. Production of interferon gamma (IFN-γ) and interleukin 2 (IL-2) in the AHCC group was significantly high compared to production in PBS-fed group. Splenic T cells from stressed and non-stressed cultured with supernatants of AHCC-treated J774.2 cell line resulted in significantly increased TNF-α or IFN-γ production. Results obtained in this study show that AHCC improves the function of immune cells as indicated by the restoration of levels of cytokines

  7. Differential regulation of protease activated receptor-1 and tissue plasminogen activator expression by shear stress in vascular smooth muscle cells

    NASA Technical Reports Server (NTRS)

    Papadaki, M.; Ruef, J.; Nguyen, K. T.; Li, F.; Patterson, C.; Eskin, S. G.; McIntire, L. V.; Runge, M. S.

    1998-01-01

    Recent studies have demonstrated that vascular smooth muscle cells are responsive to changes in their local hemodynamic environment. The effects of shear stress on the expression of human protease activated receptor-1 (PAR-1) and tissue plasminogen activator (tPA) mRNA and protein were investigated in human aortic smooth muscle cells (HASMCs). Under conditions of low shear stress (5 dyn/cm2), PAR-1 mRNA expression was increased transiently at 2 hours compared with stationary control values, whereas at high shear stress (25 dyn/cm2), mRNA expression was decreased (to 29% of stationary control; P<0.05) at all examined time points (2 to 24 hours). mRNA half-life studies showed that this response was not due to increased mRNA instability. tPA mRNA expression was decreased (to 10% of stationary control; P<0.05) by low shear stress after 12 hours of exposure and was increased (to 250% of stationary control; P<0.05) after 24 hours at high shear stress. The same trends in PAR-1 mRNA levels were observed in rat smooth muscle cells, indicating that the effects of shear stress on human PAR-1 were not species-specific. Flow cytometry and ELISA techniques using rat smooth muscle cells and HASMCs, respectively, provided evidence that shear stress exerted similar effects on cell surface-associated PAR-1 and tPA protein released into the conditioned media. The decrease in PAR-1 mRNA and protein had functional consequences for HASMCs, such as inhibition of [Ca2+] mobilization in response to thrombin stimulation. These data indicate that human PAR-1 and tPA gene expression are regulated differentially by shear stress, in a pattern consistent with their putative roles in several arterial vascular pathologies.

  8. The influence of body posture, arm movement, and work stress on trapezius activity during computer work.

    PubMed

    Mork, Paul Jarle; Westgaard, Rolf H

    2007-11-01

    The study aimed to determine the influence of arm posture and movement on trapezius activity of computer workers, considering the full workday. A second aim was to investigate if work periods perceived as stressful were associated with elevated or more sustained muscle activity pattern. Twenty-six computer workers performing call-center (n=11), help desk (n=7), or secretarial (n=8) work tasks participated. Bilateral trapezius surface electromyographic (sEMG) activity and heart rate was recorded throughout the workday. Simultaneous inclinometer recordings from left thigh and upper arms identified periods with sitting, standing, and walking, as well as arm posture and movement. Perceived work stress and tension were recorded on visual analog scales (VAS) every hour. Trapezius sEMG activity was low in seated posture [group median 1.8 and 0.9% of activity at maximal voluntary contraction (%EMGmax) for dominant and non-dominant side] and was elevated in standing (3.0 and 2.5% EMGmax) and walking (3.9 and 3.4% EMGmax). In seated posture (mean duration 79% of workday) arm movement consistently influenced trapezius activity, accounting for approximately 20% of intra-individual variation in trapezius activity. Arm elevation was on average not associated with trapezius activity when seated; however, considerable individual variation was observed. There was no indication of increase in trapezius activity or more sustained activity pattern, nor in heart rate, in high-stress versus low-stress periods, comparing periods with seated posture for the subjects reporting contrasts of at least two VAS units in stress (n=16) or tension (n=14) score. PMID:17653757

  9. Nature and the Sign of Stress-Activated Electronic Charge Carriers in Rocks

    NASA Astrophysics Data System (ADS)

    Freund, F.

    2013-12-01

    When rocks are subjected to increasing uniaxial stress, highly mobile charge carriers become activated, which have the remarkable ability to flow out of the stressed rock volume, spreading into and through adjacent less stressed or unstressed rocks. Two basic questions arise: (i) What is the nature - and the sign - of these charge carriers and (ii) How do they exist in the rocks before being activated by stress? A large body of evidence is available that points to a positive sign, consistent with defect electrons, which (in semiconductor parlance) are called 'holes'. Holes that reside in the oxygen anion sublattice, associated with O 2sp-type energy states at the upper edge of the valence band, are called 'positive holes'. The positive holes exist in rocks in form of dormant, electrically inactive peroxy defects. Ever so slight deformation, leading to grain-grain sliding, can break the peroxy bonds and activate positive holes. Electrons that are co-activated by the same process cannot flow out of the stressed rock volume into the unstressed rocks. This leads to charge separation and, hence, to a potential difference similar to a battery voltage. In order to experimentally confirm the positive sign of the positive hole charge carriers flowing out of a given stressed rock volume, certain rules have to be obeyed. If not, unreliable results may be obtained, even negative outflow currents, seemingly inconsistent with the postulated positive sign of the positive hole charge carriers. Such errors can be avoided by taking into account that the charge outflow occurs in response to a 'battery potential', V, rapidly evolving between stressed and unstressed or less stressed parts of the rock. The current I given by Ohm's Law, I=V/R, is then limited by the internal resistance R. A second complicating factor arises from the fact that, as the positive holes are stress-activated and begin to flow out, they simultaneously recombine, returning to the dormant state. The ensuing

  10. Activation and shedding of platelet glycoprotein IIb/IIIa under non-physiological shear stress.

    PubMed

    Chen, Zengsheng; Mondal, Nandan K; Ding, Jun; Koenig, Steven C; Slaughter, Mark S; Griffith, Bartley P; Wu, Zhongjun J

    2015-11-01

    The purpose of this study was to investigate the influence of non-physiological high shear stress on activation and shedding of platelet GP IIb/IIIa receptors. The healthy donor blood was exposed to three levels of high shear stresses (25, 75, 125 Pa) from the physiological to non-physiological status with three short exposure time (0.05, 0.5, 1.5 s), created by a specific blood shearing system. The activation and shedding of the platelet GPIIb/IIIa were analyzed using flow cytometry and enzyme-linked immunosorbent assay. In addition, platelet P-selectin expression of sheared blood, which is a marker for activated platelets, was also analyzed. The results from the present study showed that the number of activated platelets, as indicated by the surface GPIIb/IIIa activation and P-selectin expression, increased with increasing the shear stress level and exposure time. However, the mean fluorescence of GPIIb/IIIa on the platelet surface, decreased with increasing the shear stress level and exposure time. The reduction of GPIIb/IIIa on the platelet surface was further proved by the reduction of further activated platelet GPIIb/IIIa surface expression induced by ADP and the increase in GPIIb/IIIa concentration in microparticle-free plasma with increasing the applied shear stress and exposure time. It is clear that non-physiological shear stress induce a paradoxical phenomenon, in which both activation and shedding of the GPIIb/IIIa on the platelet surface occur simultaneously. This study may offer a new perspective to explain the reason of both increased thrombosis and bleeding events in patients implanted with high shear blood-contacting medical devices. PMID:26160282

  11. Activity of earthworm in Latosol under simulated acid rain stress.

    PubMed

    Zhang, Jia-En; Yu, Jiayu; Ouyang, Ying

    2015-01-01

    Acid rain is still an issue of environmental concerns. This study investigated the impacts of simulated acid rain (SAR) upon earthworm activity from the Latosol (acidic red soil). Laboratory experiment was performed by leaching the soil columns grown with earthworms (Eisenia fetida) at the SAR pH levels ranged from 2.0 to 6.5 over a 34-day period. Results showed that earthworms tended to escape from the soil and eventually died for the SAR at pH = 2.0 as a result of acid toxicity. The catalase activity in the earthworms decreased with the SAR pH levels, whereas the superoxide dismutases activity in the earthworms showed a fluctuate pattern: decreasing from pH 6.5 to 5.0 and increasing from pH 5.0 to 4.0. Results implied that the growth of earthworms was retarded at the SAR pH ≤ 3.0. PMID:25351717

  12. Moderate Thermal Stress Causes Active and Immediate Expulsion of Photosynthetically Damaged Zooxanthellae (Symbiodinium) from Corals

    PubMed Central

    Fujise, Lisa; Yamashita, Hiroshi; Suzuki, Go; Sasaki, Kengo; Liao, Lawrence M.; Koike, Kazuhiko

    2014-01-01

    The foundation of coral reef biology is the symbiosis between corals and zooxanthellae (dinoflagellate genus Symbiodinium). Recently, coral bleaching, which often results in mass mortality of corals and the collapse of coral reef ecosystems, has become an important issue around the world as coral reefs decrease in number year after year. To understand the mechanisms underlying coral bleaching, we maintained two species of scleractinian corals (Acroporidae) in aquaria under non-thermal stress (27°C) and moderate thermal stress conditions (30°C), and we compared the numbers and conditions of the expelled Symbiodinium from these corals. Under non-thermal stress conditions corals actively expel a degraded form of Symbiodinium, which are thought to be digested by their host coral. This response was also observed at 30°C. However, while the expulsion rates of Symbiodinium cells remained constant, the proportion of degraded cells significantly increased at 30°C. This result indicates that corals more actively digest and expel damaged Symbiodinium under thermal stress conditions, likely as a mechanism for coping with environmental change. However, the increase in digested Symbiodinium expulsion under thermal stress may not fully keep up with accumulation of the damaged cells. There are more photosynthetically damaged Symbiodinium upon prolonged exposure to thermal stress, and corals release them without digestion to prevent their accumulation. This response may be an adaptive strategy to moderate stress to ensure survival, but the accumulation of damaged Symbiodinium, which causes subsequent coral deterioration, may occur when the response cannot cope with the magnitude or duration of environmental stress, and this might be a possible mechanism underlying coral bleaching during prolonged moderate thermal stress. PMID:25493938

  13. Significance of neuronal cytochrome P450 activity in opioid-mediated stress-induced analgesia.

    PubMed

    Hough, Lindsay B; Nalwalk, Julia W; Yang, Weizhu; Ding, Xinxin

    2014-08-26

    Stressful environmental changes can suppress nociceptive transmission, a phenomenon known as "stress-induced analgesia". Depending on the stressor and the subject, opioid or non-opioid mechanisms are activated. Brain μ opioid receptors mediate analgesia evoked either by exogenous agents (e.g. morphine), or by the release of endogenous opioids following stressful procedures. Recent work with morphine and neuronal cytochrome P450 (P450)-deficient mice proposed a signal transduction role for P450 enzymes in µ analgesia. Since µ opioid receptors also mediate some forms of stress-induced analgesia, the present studies assessed the significance of brain P450 activity in opioid-mediated stress-induced analgesia. Two widely-used models of opioid stress-induced analgesia (restraint and warm water swim) were studied in both sexes of wild-type control and P450-deficient (Null) mice. In control mice, both stressors evoked moderate analgesic responses which were blocked by pretreatment with the opioid antagonist naltrexone, confirming the opioid nature of these responses. Consistent with literature, sex differences (control female>control male) were seen in swim-induced, but not restraint-induced, analgesia. Null mice showed differential responses to the two stress paradigms. As compared with control subjects, Null mice showed highly attenuated restraint-induced analgesia, showing a critical role for neuronal P450s in this response. However, warm water swim-induced analgesia was unchanged in Null vs. control mice. Additional control experiments confirmed the absence of morphine analgesia in Null mice. These results are the first to show that some forms of opioid-mediated stress-induced analgesia require brain neuronal P450 activity.

  14. Context Specificity of Stress-activated Mitogen-activated Protein (MAP) Kinase Signaling: The Story as Told by Caenorhabditis elegans.

    PubMed

    Andrusiak, Matthew G; Jin, Yishi

    2016-04-01

    Stress-associated p38 and JNK mitogen-activated protein (MAP) kinase signaling cascades trigger specific cellular responses and are involved in multiple disease states. At the root of MAP kinase signaling complexity is the differential use of common components on a context-specific basis. The roundwormCaenorhabditis eleganswas developed as a system to study genes required for development and nervous system function. The powerful genetics ofC. elegansin combination with molecular and cellular dissections has led to a greater understanding of how p38 and JNK signaling affects many biological processes under normal and stress conditions. This review focuses on the studies revealing context specificity of different stress-activated MAPK components inC. elegans.

  15. Context Specificity of Stress-activated Mitogen-activated Protein (MAP) Kinase Signaling: The Story as Told by Caenorhabditis elegans.

    PubMed

    Andrusiak, Matthew G; Jin, Yishi

    2016-04-01

    Stress-associated p38 and JNK mitogen-activated protein (MAP) kinase signaling cascades trigger specific cellular responses and are involved in multiple disease states. At the root of MAP kinase signaling complexity is the differential use of common components on a context-specific basis. The roundwormCaenorhabditis eleganswas developed as a system to study genes required for development and nervous system function. The powerful genetics ofC. elegansin combination with molecular and cellular dissections has led to a greater understanding of how p38 and JNK signaling affects many biological processes under normal and stress conditions. This review focuses on the studies revealing context specificity of different stress-activated MAPK components inC. elegans. PMID:26907690

  16. Latent transforming growth factor beta1 activation in situ: quantitative and functional evidence after low-dose gamma-irradiation

    NASA Technical Reports Server (NTRS)

    Ehrhart, E. J.; Segarini, P.; Tsang, M. L.; Carroll, A. G.; Barcellos-Hoff, M. H.; Chatterjee, A. (Principal Investigator)

    1997-01-01

    The biological activity of transforming growth factor beta1 (TGF-beta) is controlled by its secretion as a latent complex in which it is noncovalently associated with latency-associated peptide (LAP). Activation is the extracellular process in which TGF-beta is released from LAP, and is considered to be a primary regulatory control. We recently reported rapid and persistent changes in TGF-beta immunoreactivity in conjunction with extracellular matrix remodeling in gamma-irradiated mouse mammary gland. Our hypothesis is that these specific changes in immunoreactivity are indicative of latent TGF-beta activation. In the present study, we determined the radiation dose response and tested whether a functional relationship exists between radiation-induced TGF-beta and collagen type III remodeling. After radiation exposures as low as 0.1 Gy, we detected increased TGF-beta immunoreactivity in the mammary epithelium concomitant with decreased LAP immunostaining, which are events consistent with activation. Quantitative image analysis demonstrated a significant (P=0.0005) response at 0.1 Gy without an apparent threshold and a linear dose response to 5 Gy. However, in the adipose stroma, loss of LAP demonstrated a qualitative threshold at 0.5 Gy. Loss of LAP paralleled induction of collagen III immunoreactivity in this tissue compartment. We tested whether TGF-beta mediates collagen III expression by treating animals with TGF-beta panspecific monoclonal antibody, 1D11.16, administered i.p. shortly before irradiation. Radiation-induced collagen III staining in the adipose stroma was blocked in an antibody dose-dependent manner, which persisted through 7 days postirradiation. RNase protection assay revealed that radiation-induced elevation of total gland collagen III mRNA was also blocked by neutralizing antibody treatment. These data provide functional confirmation of the hypothesis that radiation exposure leads to latent TGF-beta activation, support our interpretation of the

  17. Oxidative stress is decreased in physically active sickle cell SAD mice.

    PubMed

    Charrin, Emmanuelle; Aufradet, Emeline; Douillard, Aymeric; Romdhani, Aymen; Souza, Genevieve De; Bessaad, Amine; Faes, Camille; Chirico, Erica N; Pialoux, Vincent; Martin, Cyril

    2015-03-01

    Oxidative stress plays a crucial role in sickle cell disease (SCD) physiopathology. Given that chronic physical activity is known to decrease reactive oxygen species (ROS) and increase nitric oxide (NO) bioavailability in healthy subjects and in patients with cardiovascular or inflammatory pathologies, modulating these factors involved in the severity of the pathology could also be beneficial in SCD. This study aimed to determine if 8 weeks of increased physical activity (PA) by voluntary wheel running affects the hypoxia/reoxygenation (H/R) responses by reducing oxidative stress and increasing NO synthesis in sickle SAD mice. Nitrite/nitrate (NOx) concentrations, NOS3 mRNA expression and phosphorylated-endothelial nitric oxide synthase immunostaining were increased in the lungs of the PA groups after H/R stress. Moreover, lipid peroxidation in the heart was decreased in PA SAD mice. The improvement of antioxidant activity at rest and the decrease in haemolysis may explain this reduced oxidative stress. These results suggest that physical activity probably diminishes some deleterious effects of H/R stress in SAD mice and could be protective against vascular occlusions. PMID:25382268

  18. Extracurricular activities associated with stress and burnout in preclinical medical students.

    PubMed

    Fares, Jawad; Saadeddin, Zein; Al Tabosh, Hayat; Aridi, Hussam; El Mouhayyar, Christopher; Koleilat, Mohamad Karim; Chaaya, Monique; El Asmar, Khalil

    2016-09-01

    This study aims to assess the prevalence of stress and burnout among preclinical medical students in a private university in Beirut, Lebanon, and evaluate the association between extracurricular involvement and stress and burnout relief in preclinical medical students. A cross-sectional survey was conducted on a random sample of 165 preclinical medical students. Distress level was measured using the 12-item General Health Questionnaire (GHQ-12) while that of burnout was measured through the Maslach Burnout Inventory-Student Survey (MBI-SS). The MBI-SS assesses three interrelated dimensions: emotional exhaustion, cynicism, and academic efficacy. Extracurricular activities were divided into four categories: physical exercise, music, reading, and social activities. All selected participants responded. A substantial proportion of preclinical medical students suffered from stress (62%) and burnout (75%). Bivariate and multivariate regression analyses revealed that being a female or a 1st year medical student correlated with higher stress and burnout. Music-related activities were correlated with lower burnout. Social activities or living with parents were associated with lower academic efficacy. The high stress and burnout levels call for action. Addressing the studying conditions and attending to the psychological wellbeing of preclinical medical students are recommendations made in the study.

  19. Extracurricular activities associated with stress and burnout in preclinical medical students.

    PubMed

    Fares, Jawad; Saadeddin, Zein; Al Tabosh, Hayat; Aridi, Hussam; El Mouhayyar, Christopher; Koleilat, Mohamad Karim; Chaaya, Monique; El Asmar, Khalil

    2016-09-01

    This study aims to assess the prevalence of stress and burnout among preclinical medical students in a private university in Beirut, Lebanon, and evaluate the association between extracurricular involvement and stress and burnout relief in preclinical medical students. A cross-sectional survey was conducted on a random sample of 165 preclinical medical students. Distress level was measured using the 12-item General Health Questionnaire (GHQ-12) while that of burnout was measured through the Maslach Burnout Inventory-Student Survey (MBI-SS). The MBI-SS assesses three interrelated dimensions: emotional exhaustion, cynicism, and academic efficacy. Extracurricular activities were divided into four categories: physical exercise, music, reading, and social activities. All selected participants responded. A substantial proportion of preclinical medical students suffered from stress (62%) and burnout (75%). Bivariate and multivariate regression analyses revealed that being a female or a 1st year medical student correlated with higher stress and burnout. Music-related activities were correlated with lower burnout. Social activities or living with parents were associated with lower academic efficacy. The high stress and burnout levels call for action. Addressing the studying conditions and attending to the psychological wellbeing of preclinical medical students are recommendations made in the study. PMID:26644345

  20. Mechanosensitive channels are activated by stress in the actin stress fibres, and could be involved in gravity sensing in plants.

    PubMed

    Tatsumi, H; Furuichi, T; Nakano, M; Toyota, M; Hayakawa, K; Sokabe, M; Iida, H

    2014-01-01

    Mechanosensitive (MS) channels are expressed in a variety of cells. The molecular and biophysical mechanism involved in the regulation of MS channel activities is a central interest in basic biology. MS channels are thought to play crucial roles in gravity sensing in plant cells. To date, two mechanisms have been proposed for MS channel activation. One is that tension development in the lipid bilayer directly activates MS channels. The second mechanism proposes that the cytoskeleton is involved in the channel activation, because MS channel activities are modulated by pharmacological treatments that affect the cytoskeleton. We tested whether tension in the cytoskeleton activates MS channels. Mammalian endothelial cells were microinjected with phalloidin-conjugated beads, which bound to stress fibres, and a traction force to the actin cytoskeleton was applied by dragging the beads with optical tweezers. MS channels were activated when the force was applied, demonstrating that a sub-pN force to the actin filaments activates a single MS channel. Plants may use a similar molecular mechanism in gravity sensing, since the cytoplasmic Ca(2+) concentration increase induced by changes in the gravity vector was attenuated by potential MS channel inhibitors, and by actin-disrupting drugs. These results support the idea that the tension increase in actin filaments by gravity-dependent sedimentation of amyloplasts activates MS Ca(2+) -permeable channels, which can be the molecular mechanism of a Ca(2+) concentration increase through gravistimulation. We review recent progress in the study of tension sensing by actin filaments and MS channels using advanced biophysical methods, and discuss their possible roles in gravisensing.

  1. Cocaine induces astrocytosis through ER stress-mediated activation of autophagy.

    PubMed

    Periyasamy, Palsamy; Guo, Ming-Lei; Buch, Shilpa

    2016-08-01

    Cocaine is known to induce inflammation, thereby contributing in part, to the pathogenesis of neurodegeneration. A recent study from our lab has revealed a link between macroautophagy/autophagy and microglial activation. The current study was aimed at investigating whether cocaine could also mediate activation of astrocytes and, whether this process involved induction of autophagy. Our findings demonstrated that cocaine mediated the activation of astrocytes by altering the levels of autophagy markers, such as BECN1, ATG5, MAP1LC3B-II, and SQSTM1 in both human A172 astrocytoma cells and primary human astrocytes. Furthermore, cocaine treatment resulted in increased formation of endogenous MAP1LC3B puncta in human astrocytes. Additionally, astrocytes transfected with the GFP-MAP1LC3B plasmid also demonstrated cocaine-mediated upregulation of the green fluorescent MAP1LC3B puncta. Cocaine-mediated induction of autophagy involved upstream activation of ER stress proteins such as EIF2AK3, ERN1, ATF6 since blockage of autophagy using either pharmacological or gene-silencing approaches, had no effect on cocaine-mediated induction of ER stress. Using both pharmacological and gene-silencing approaches to block either ER stress or autophagy, our findings demonstrated that cocaine-induced activation of astrocytes (measured by increased levels of GFAP) involved sequential activation of ER stress and autophagy. Cocaine-mediated-increased upregulation of GFAP correlated with increased expression of proinflammatory mediators such as TNF, IL1B, and IL6. In conclusion, these findings reveal an association between ER stress-mediated autophagy and astrogliosis in cocaine-treated astrocytes. Intervention of ER stress and/or autophagy signaling would thus be promising therapeutic targets for abrogating cocaine-mediated neuroinflammation. PMID:27337297

  2. Cocaine induces astrocytosis through ER stress-mediated activation of autophagy.

    PubMed

    Periyasamy, Palsamy; Guo, Ming-Lei; Buch, Shilpa

    2016-08-01

    Cocaine is known to induce inflammation, thereby contributing in part, to the pathogenesis of neurodegeneration. A recent study from our lab has revealed a link between macroautophagy/autophagy and microglial activation. The current study was aimed at investigating whether cocaine could also mediate activation of astrocytes and, whether this process involved induction of autophagy. Our findings demonstrated that cocaine mediated the activation of astrocytes by altering the levels of autophagy markers, such as BECN1, ATG5, MAP1LC3B-II, and SQSTM1 in both human A172 astrocytoma cells and primary human astrocytes. Furthermore, cocaine treatment resulted in increased formation of endogenous MAP1LC3B puncta in human astrocytes. Additionally, astrocytes transfected with the GFP-MAP1LC3B plasmid also demonstrated cocaine-mediated upregulation of the green fluorescent MAP1LC3B puncta. Cocaine-mediated induction of autophagy involved upstream activation of ER stress proteins such as EIF2AK3, ERN1, ATF6 since blockage of autophagy using either pharmacological or gene-silencing approaches, had no effect on cocaine-mediated induction of ER stress. Using both pharmacological and gene-silencing approaches to block either ER stress or autophagy, our findings demonstrated that cocaine-induced activation of astrocytes (measured by increased levels of GFAP) involved sequential activation of ER stress and autophagy. Cocaine-mediated-increased upregulation of GFAP correlated with increased expression of proinflammatory mediators such as TNF, IL1B, and IL6. In conclusion, these findings reveal an association between ER stress-mediated autophagy and astrogliosis in cocaine-treated astrocytes. Intervention of ER stress and/or autophagy signaling would thus be promising therapeutic targets for abrogating cocaine-mediated neuroinflammation.

  3. Cumulative stress in childhood is associated with blunted reward-related brain activity in adulthood.

    PubMed

    Hanson, Jamie L; Albert, Dustin; Iselin, Anne-Marie R; Carré, Justin M; Dodge, Kenneth A; Hariri, Ahmad R

    2016-03-01

    Early life stress (ELS) is strongly associated with negative outcomes in adulthood, including reduced motivation and increased negative mood. The mechanisms mediating these relations, however, are poorly understood. We examined the relation between exposure to ELS and reward-related brain activity, which is known to predict motivation and mood, at age 26, in a sample followed since kindergarten with annual assessments. Using functional neuroimaging, we assayed individual differences in the activity of the ventral striatum (VS) during the processing of monetary rewards associated with a simple card-guessing task, in a sample of 72 male participants. We examined associations between a cumulative measure of ELS exposure and VS activity in adulthood. We found that greater levels of cumulative stress during childhood and adolescence predicted lower reward-related VS activity in adulthood. Extending this general developmental pattern, we found that exposure to stress early in development (between kindergarten and grade 3) was significantly associated with variability in adult VS activity. Our results provide an important demonstration that cumulative life stress, especially during this childhood period, is associated with blunted reward-related VS activity in adulthood. These differences suggest neurobiological pathways through which a history of ELS may contribute to reduced motivation and increased negative mood. PMID:26443679

  4. Cumulative stress in childhood is associated with blunted reward-related brain activity in adulthood.

    PubMed

    Hanson, Jamie L; Albert, Dustin; Iselin, Anne-Marie R; Carré, Justin M; Dodge, Kenneth A; Hariri, Ahmad R

    2016-03-01

    Early life stress (ELS) is strongly associated with negative outcomes in adulthood, including reduced motivation and increased negative mood. The mechanisms mediating these relations, however, are poorly understood. We examined the relation between exposure to ELS and reward-related brain activity, which is known to predict motivation and mood, at age 26, in a sample followed since kindergarten with annual assessments. Using functional neuroimaging, we assayed individual differences in the activity of the ventral striatum (VS) during the processing of monetary rewards associated with a simple card-guessing task, in a sample of 72 male participants. We examined associations between a cumulative measure of ELS exposure and VS activity in adulthood. We found that greater levels of cumulative stress during childhood and adolescence predicted lower reward-related VS activity in adulthood. Extending this general developmental pattern, we found that exposure to stress early in development (between kindergarten and grade 3) was significantly associated with variability in adult VS activity. Our results provide an important demonstration that cumulative life stress, especially during this childhood period, is associated with blunted reward-related VS activity in adulthood. These differences suggest neurobiological pathways through which a history of ELS may contribute to reduced motivation and increased negative mood.

  5. Streetscape greenery and health: stress, social cohesion and physical activity as mediators.

    PubMed

    de Vries, Sjerp; van Dillen, Sonja M E; Groenewegen, Peter P; Spreeuwenberg, Peter

    2013-10-01

    Several studies have shown a positive relationship between local greenspace availability and residents' health, which may offer opportunities for health improvement. This study focuses on three mechanisms through which greenery might exert its positive effect on health: stress reduction, stimulating physical activity and facilitating social cohesion. Knowledge on mechanisms helps to identify which type of greenspace is most effective in generating health benefits. In eighty neighbourhoods in four Dutch cities data on quantity and quality of streetscape greenery were collected by observations. Data on self-reported health and proposed mediators were obtained for adults by mail questionnaires (N = 1641). Multilevel regression analyses, controlling for socio-demographic characteristics, revealed that both quantity and quality of streetscape greenery were related to perceived general health, acute health-related complaints, and mental health. Relationships were generally stronger for quality than for quantity. Stress and social cohesion were the strongest mediators. Total physical activity was not a mediator. Physical activity that could be undertaken in the public space (green activity) was, but less so than stress and social cohesion. With all three mediators included in the analysis, complete mediation could statistically be proven in five out of six cases. In these analyses the contribution of green activity was often not significant. The possibility that the effect of green activity is mediated by stress and social cohesion, rather than that it has a direct health effect, is discussed. PMID:23931942

  6. The Adaptogens Rhodiola and Schizandra Modify the Response to Immobilization Stress in Rabbits by Suppressing the Increase of Phosphorylated Stress-activated Protein Kinase, Nitric Oxide and Cortisol

    PubMed Central

    Panossian, Alexander; Hambardzumyan, Marina; Hovhanissyan, Areg; Wikman, Georg

    2007-01-01

    Adaptogens possess anti-fatigue and anti-stress activities that can increase mental and physical working performance against a background of fatigue or stress. The aim of the present study was to ascertain which mediators of stress response are significantly involved in the mechanisms of action of adaptogens, and to determine their relevance as biochemical markers for evaluating anti-stress effects in rabbits subjected to restraint stress. Blood levels of stress-activated protein kinase (SAPK/JNK), the phosphorylated kinase p-SAPK/p-JNK, nitric oxide (NO), cortisol, testosterone, prostaglandin E2, leukotriene B4 and thromboxane B2 were determined in groups of animals prior to daily oral administration of placebo, rhodioloside or extracts of Eleutherococcus senticosus, Schizandra chinensis, Rhodiola rosea, Bryonia alba and Panax ginseng over a 7 day period. Ten minutes after the final treatment, animals were immobilized for 2 hours and blood levels of the markers re-determined. In the placebo group, only p-SAPK/p-JNK, NO and cortisol were increased significantly (by 200–300% cf basal levels) following restraint stress, whilst in animals that had received multiple doses of adaptogens/stress-protectors, the levels of NO and cortisol remained practically unchanged after acute stress. Rhodioloside and extracts of S. chinensis and R. rosea were the most active inhibitors of stress-induced p-SAPK/p-JNK. E. senticosus, B. alba and P. ginseng exerted little effect on p-SAPK/p-JNK levels. It is suggested that the inhibitory effects of R. rosea and S. chinensis on p-SAPK/p-JNK activation may be associated with their antidepressant activity as well as their positive effects on mental performance under stress. PMID:21901061

  7. The stressed female brain: neuronal activity in the prelimbic but not infralimbic region of the medial prefrontal cortex suppresses learning after acute stress.

    PubMed

    Maeng, Lisa Y; Shors, Tracey J

    2013-01-01

    Women are nearly twice as likely as men to suffer from anxiety and post-traumatic stress disorder (PTSD), indicating that many females are especially vulnerable to stressful life experience. A profound sex difference in the response to stress is also observed in laboratory animals. Acute exposure to an uncontrollable stressful event disrupts associative learning during classical eyeblink conditioning in female rats but enhances this same type of learning process in males. These sex differences in response to stress are dependent on neuronal activity in similar but also different brain regions. Neuronal activity in the basolateral nucleus of the amygdala (BLA) is necessary in both males and females. However, neuronal activity in the medial prefrontal cortex (mPFC) during the stressor is necessary to modify learning in females but not in males. The mPFC is often divided into its prelimbic (PL) and infralimbic (IL) subregions, which differ both in structure and function. Through its connections to the BLA, we hypothesized that neuronal activity within the PL, but not IL, during the stressor is necessary to suppress learning in females. To test this hypothesis, either the PL or IL of adult female rats was bilaterally inactivated with GABAA agonist muscimol during acute inescapable swim stress. About 24 h later, all subjects were trained with classical eyeblink conditioning. Though stressed, females without neuronal activity in the PL learned well. In contrast, females with IL inactivation during the stressor did not learn well, behaving similarly to stressed vehicle-treated females. These data suggest that exposure to a stressful event critically engages the PL, but not IL, to disrupt associative learning in females. Together with previous studies, these data indicate that the PL communicates with the BLA to suppress learning after a stressful experience in females. This circuit may be similarly engaged in women who become cognitively impaired after stressful life

  8. Chronic stress enhances microglia activation and exacerbates death of nigral dopaminergic neurons under conditions of inflammation

    PubMed Central

    2014-01-01

    Background Parkinson’s disease is an irreversible neurodegenerative disease linked to progressive movement disorders and is accompanied by an inflammatory reaction that is believed to contribute to its pathogenesis. Since sensitivity to inflammation is not the same in all brain structures, the aim of this work was to test whether physiological conditions as stress could enhance susceptibility to inflammation in the substantia nigra, where death of dopaminergic neurons takes place in Parkinson’s disease. Methods To achieve our aim, we induced an inflammatory process in nonstressed and stressed rats (subject to a chronic variate stress) by a single intranigral injection of lipopolysaccharide, a potent proinflammogen. The effect of this treatment was evaluated on inflammatory markers as well as on neuronal and glial populations. Results Data showed a synergistic effect between inflammation and stress, thus resulting in higher microglial activation and expression of proinflammatory markers. More important, the higher inflammatory response seen in stressed animals was associated with a higher rate of death of dopaminergic neurons in the substantia nigra, the most characteristic feature seen in Parkinson’s disease. This effect was dependent on glucocorticoids. Conclusions Our data demonstrate that stress sensitises midbrain microglia to further inflammatory stimulus. This suggests that stress may be an important risk factor in the degenerative processes and symptoms of Parkinson’s disease. PMID:24565378

  9. Targeting Activation of Specific NF-κB Subunits Prevents Stress-Dependent Atherothrombotic Gene Expression

    PubMed Central

    Djuric, Zdenka; Kashif, Muhammed; Fleming, Thomas; Muhammad, Sajjad; Piel, David; von Bauer, Rüdiger; Bea, Florian; Herzig, Stephan; Zeier, Martin; Pizzi, Marina; Isermann, Berend; Hecker, Markus; Schwaninger, Markus; Bierhaus, Angelika; Nawroth, Peter P

    2012-01-01

    Psychosocial stress has been shown to be a contributing factor in the development of atherosclerosis. Although the underlying mechanisms have not been elucidated entirely, it has been shown previously that the transcription factor nuclear factor-κB (NF-κB) is an important component of stress-activated signaling pathway. In this study, we aimed to decipher the mechanisms of stress-induced NF-κB-mediated gene expression, using an in vitro and in vivo model of psychosocial stress. Induction of stress led to NF-κB-dependent expression of proinflammatory (tissue factor, intracellular adhesive molecule 1 [ICAM-1]) and protective genes (manganese superoxide dismutase [MnSOD]) via p50, p65 or cRel. Selective inhibition of the different subunits and the respective kinases showed that inhibition of cRel leads to the reduction of atherosclerotic lesions in apolipoprotein−/− (ApoE−/−) mice via suppression of proinflammatory gene expression. This observation may therefore provide a possible explanation for ineffectiveness of antioxidant therapies and suggests that selective targeting of cRel activation may provide a novel approach for the treatment of stress-related inflammatory vascular disease. PMID:23114885

  10. Physical activity, mindfulness meditation, or heart rate variability biofeedback for stress reduction: a randomized controlled trial.

    PubMed

    van der Zwan, Judith Esi; de Vente, Wieke; Huizink, Anja C; Bögels, Susan M; de Bruin, Esther I

    2015-12-01

    In contemporary western societies stress is highly prevalent, therefore the need for stress-reducing methods is great. This randomized controlled trial compared the efficacy of self-help physical activity (PA), mindfulness meditation (MM), and heart rate variability biofeedback (HRV-BF) in reducing stress and its related symptoms. We randomly allocated 126 participants to PA, MM, or HRV-BF upon enrollment, of whom 76 agreed to participate. The interventions consisted of psycho-education and an introduction to the specific intervention techniques and 5 weeks of daily exercises at home. The PA exercises consisted of a vigorous-intensity activity of free choice. The MM exercises consisted of guided mindfulness meditation. The HRV-BF exercises consisted of slow breathing with a heart rate variability biofeedback device. Participants received daily reminders for their exercises and were contacted weekly to monitor their progress. They completed questionnaires prior to, directly after, and 6 weeks after the intervention. Results indicated an overall beneficial effect consisting of reduced stress, anxiety and depressive symptoms, and improved psychological well-being and sleep quality. No significant between-intervention effect was found, suggesting that PA, MM, and HRV-BF are equally effective in reducing stress and its related symptoms. These self-help interventions provide easily accessible help for people with stress complaints. PMID:26111942

  11. Physical activity, mindfulness meditation, or heart rate variability biofeedback for stress reduction: a randomized controlled trial.

    PubMed

    van der Zwan, Judith Esi; de Vente, Wieke; Huizink, Anja C; Bögels, Susan M; de Bruin, Esther I

    2015-12-01

    In contemporary western societies stress is highly prevalent, therefore the need for stress-reducing methods is great. This randomized controlled trial compared the efficacy of self-help physical activity (PA), mindfulness meditation (MM), and heart rate variability biofeedback (HRV-BF) in reducing stress and its related symptoms. We randomly allocated 126 participants to PA, MM, or HRV-BF upon enrollment, of whom 76 agreed to participate. The interventions consisted of psycho-education and an introduction to the specific intervention techniques and 5 weeks of daily exercises at home. The PA exercises consisted of a vigorous-intensity activity of free choice. The MM exercises consisted of guided mindfulness meditation. The HRV-BF exercises consisted of slow breathing with a heart rate variability biofeedback device. Participants received daily reminders for their exercises and were contacted weekly to monitor their progress. They completed questionnaires prior to, directly after, and 6 weeks after the intervention. Results indicated an overall beneficial effect consisting of reduced stress, anxiety and depressive symptoms, and improved psychological well-being and sleep quality. No significant between-intervention effect was found, suggesting that PA, MM, and HRV-BF are equally effective in reducing stress and its related symptoms. These self-help interventions provide easily accessible help for people with stress complaints.

  12. Delayed healing of a navicular stress fracture, following limited weight-bearing activity

    PubMed Central

    Robinson, Matthew; Fulcher, Mark

    2014-01-01

    This report describes a 21-year-old man, a semiprofessional football (soccer) player, with a navicular stress fracture. It highlights the difficulty in diagnosing the condition and the complications arising from inadequate management. The case discusses the optimal management of these stress fractures and the detrimental role of weight-bearing recovery. The diagnosis of navicular stress fractures is challenging, and a high index of suspicion is required. The available literature indicates that limited weightbearing is not an appropriate treatment for navicular stress injuries. Non-weight-bearing (NWB) cast immobilisation for 6–8 weeks appears to be the gold standard treatment; however, open reduction with internal fixation (ORIF) has similar success rates and an equal return-to-play time but should also be followed by a period of NWB. NWB cast immobilisation for 6 weeks remains a good second option at any time following failed limited weight-bearing activity. PMID:24618870

  13. Reduction of Free Edge Peeling Stress of Laminated Composites Using Active Piezoelectric Layers

    PubMed Central

    Huang, Bin; Kim, Heung Soo

    2014-01-01

    An analytical approach is proposed in the reduction of free edge peeling stresses of laminated composites using active piezoelectric layers. The approach is the extended Kantorovich method which is an iterative method. Multiterms of trial function are employed and governing equations are derived by taking the principle of complementary virtual work. The solutions are obtained by solving a generalized eigenvalue problem. By this approach, the stresses automatically satisfy not only the traction-free boundary conditions, but also the free edge boundary conditions. Through the iteration processes, the free edge stresses converge very quickly. It is found that the peeling stresses generated by mechanical loadings are significantly reduced by applying a proper electric field to the piezoelectric actuators. PMID:25025088

  14. Noradrenergic blockade stabilizes prefrontal activity and enables fear extinction under stress.

    PubMed

    Fitzgerald, Paul J; Giustino, Thomas F; Seemann, Jocelyn R; Maren, Stephen

    2015-07-14

    Stress-induced impairments in extinction learning are believed to sustain posttraumatic stress disorder (PTSD). Noradrenergic signaling may contribute to extinction impairments by modulating medial prefrontal cortex (mPFC) circuits involved in fear regulation. Here we demonstrate that aversive fear conditioning rapidly and persistently alters spontaneous single-unit activity in the prelimbic and infralimbic subdivisions of the mPFC in behaving rats. These conditioning-induced changes in mPFC firing were mitigated by systemic administration of propranolol (10 mg/kg, i.p.), a β-noradrenergic receptor antagonist. Moreover, propranolol administration dampened the stress-induced impairment in extinction observed when extinction training is delivered shortly after fear conditioning. These findings suggest that β-adrenoceptors mediate stress-induced changes in mPFC spike firing that contribute to extinction impairments. Propranolol may be a helpful adjunct to behavioral therapy for PTSD, particularly in patients who have recently experienced trauma.

  15. Relationship between physical activity and markers of oxidative stress in independent community-living elderly individuals.

    PubMed

    Fraile-Bermúdez, A B; Kortajarena, M; Zarrazquin, I; Maquibar, A; Yanguas, J J; Sánchez-Fernández, C E; Gil, J; Irazusta, A; Ruiz-Litago, F

    2015-10-01

    The aim of the present study was to examine the relationship between objective data of physical activity and markers of oxidative stress in older men and women. Participants were old adults, aged≥60years (61 women and 34 men) who were all capable of performing basic daily activities by themselves and lived on their own. To describe physical activity we used objective data measured by accelerometers which record active and sedentary periods during everyday life for five days. Determination of oxidative stress was conducted from three perspectives: determination plasma total antioxidant status (TAS), plasma antioxidant enzyme activities, i.e., glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD), and membrane lipid peroxidation (TBARS). In the group of women, those who met physical activity recommendations (WR) had lower level of TAS. In addition, the moderate to vigorous physical activity (MVPA) was negatively correlated with TAS. Simultaneously, MVPA was correlated with increase in the GPx antioxidant enzyme activity, and the counts per minute were positively correlated with CAT activity. In the group of men, the cpm and the MVPA were negatively correlated with lipid peroxidation while lifestyle physical activity was positively correlated with CAT activity. These findings suggest that MVPA in the elderly although it is related to a decrease in the TAS in women, induces adaptive increase in antioxidant enzyme activity and decreases lipid peroxidation in both women and men. These results suggest that at this time of life, it is not only the amount of physical activity performed that is important but also its intensity.

  16. Changes in hormone and stress-inducing activities of municipal wastewater in a conventional activated sludge wastewater treatment plant.

    PubMed

    Wojnarowicz, Pola; Yang, Wenbo; Zhou, Hongde; Parker, Wayne J; Helbing, Caren C

    2014-12-01

    Conventional municipal wastewater treatment plants do not efficiently remove contaminants of emerging concern, and so are primary sources for contaminant release into the aquatic environment. Although these contaminants are present in effluents at ng-μg/L concentrations (i.e. microcontaminants), many compounds can act as endocrine disrupting compounds or stress-inducing agents at these levels. Chemical fate analyses indicate that additional levels of wastewater treatment reduce but do not always completely remove all microcontaminants. The removal of microcontaminants from wastewater does not necessarily correspond to a reduction in biological activity, as contaminant metabolites or byproducts may still be biologically active. To evaluate the efficacy of conventional municipal wastewater treatment plants to remove biological activity, we examined the performance of a full scale conventional activated sludge municipal wastewater treatment plant located in Guelph, Ontario, Canada. We assessed reductions in levels of conventional wastewater parameters and thyroid hormone disrupting and stress-inducing activities in wastewater at three phases along the treatment train using a C-fin assay. Wastewater treatment was effective at reducing total suspended solids, chemical and biochemical oxygen demand, and stress-inducing bioactivity. However, only minimal reduction was observed in thyroid hormone disrupting activities. The present study underscores the importance of examining multiple chemical and biological endpoints in evaluating and monitoring the effectiveness of wastewater treatment for removal of microcontaminants.

  17. Reactive Oxygene Species and Thioredoxin Activity in Plants at Development of Hypergravity and Oxidative Stresses

    NASA Astrophysics Data System (ADS)

    Jadko, Sergiy

    Early increasing of reactive oxygen species (ROS) content, including H2O2, occurs in plant cells under various impacts and than these ROS can function as signaling molecules in starting of cell stress responses. At the same time thioredoxins (TR) are significant ROS and H2O2 sensors and transmitters to activation of various redox sensitive proteins, transcription factors and MAP kinases. This study was aimed to investigate early increasing of ROS and H2O2 contents and TR activity in the pea roots and in tissue culture under hypergravity and oxidative stresses. Pea roots of 3-5 days old seedlings and 12-14 days old tissue culture of Arabidopsis thaliana were studied. The pea seedlings were grown on wet filter paper and the tissue culture was grown on MS medium in dark conditions under 24oC. Hypergravity stress was induced by centrifugation at 10 and 15 g. Chemiluminescence (ChL) intensity for ROS concentration, H2O2 content and TR activity were determined. All experiments were repeated by 3-5 times. Early and reliable increasing of ChL intensity and H2O2 contents in the pea roots and in the tissue culture took place under hypergravity and oxidative stresses to 30, 60 and 90 min. At the same time TR activity increased on 11 and 19 percents only to 60 and 90 min. Thus under hypergravity and oxidative stresses in both investigated plants take place early increasing of ROS and H2O2 contents which as second messengers lead to increasing of TR activity with creating of ROS-TR stress signaling pathway.

  18. Embryo as an active granular fluid: stress-coordinated cellular constriction chains

    NASA Astrophysics Data System (ADS)

    Gao, Guo-Jie Jason; Holcomb, Michael C.; Thomas, Jeffrey H.; Blawzdziewicz, Jerzy

    2016-10-01

    Mechanical stress plays an intricate role in gene expression in individual cells and sculpting of developing tissues. However, systematic methods of studying how mechanical stress and feedback help to harmonize cellular activities within a tissue have yet to be developed. Motivated by our observation of the cellular constriction chains (CCCs) during the initial phase of ventral furrow formation in the Drosophila melanogaster embryo, we propose an active granular fluid (AGF) model that provides valuable insights into cellular coordination in the apical constriction process. In our model, cells are treated as circular particles connected by a predefined force network, and they undergo a random constriction process in which the particle constriction probability P is a function of the stress exerted on the particle by its neighbors. We find that when P favors tensile stress, constricted particles tend to form chain-like structures. In contrast, constricted particles tend to form compact clusters when P favors compression. A remarkable similarity of constricted-particle chains and CCCs observed in vivo provides indirect evidence that tensile-stress feedback coordinates the apical constriction activity. Our particle-based AGF model will be useful in analyzing mechanical feedback effects in a wide variety of morphogenesis and organogenesis phenomena.

  19. Active faults, stress field and plate motion along the Indo-Eurasian plate boundary

    NASA Astrophysics Data System (ADS)

    Nakata, Takashi; Otsuki, Kenshiro; Khan, S. H.

    1990-09-01

    The active faults of the Himalayas and neighboring areas are direct indicators of Recent and sub-Recent crustal movements due to continental collision between the Indian and Eurasian plates. The direction of the maximum horizontal shortening or horizontal compressive stress axes deduced from the strike and type of active faulting reveals a characteristic regional stress field along the colliding boundary. The trajectories of the stress axes along the transcurrent faults and the Eastern Himalayan Front, are approximately N-S, parallel to the relative motion of the two plates. However, along the southern margin of the Eurasian plate, they are NE-SW in the Western Himalayan Front and NW-SE to E-W in the Kirthar-Sulaiman Front, which is not consistent with the direction of relative plate motion. A simple model is proposed in order to explain the regional stress pattern. In this model, the tectonic sliver between the transcurrent faults and the plate margin, is dragged northward by the oblique convergence of the Indian plate. Thus, the direction of relative motion between the tectonic sliver and the Indian plate changes regionally, causing local compressive stress fields. Judging from the long-term slip rates along the active faults, the relative motion between the Indian and Eurasian plates absorbed in the colliding zone is about one fourth of its total amount; the rest may be consumed along the extensive strike-slip faults in Tibet and China.

  20. Evidence for ACD5 ceramide kinase activity involvement in Arabidopsis response to cold stress.

    PubMed

    Dutilleul, Christelle; Chavarria, Heidy; Rézé, Nathalie; Sotta, Bruno; Baudouin, Emmanuel; Guillas, Isabelle

    2015-12-01

    Although sphingolipids emerged as important signals for plant response to low temperature, investigations have been limited so far to the function of long-chain base intermediates. The formation and function of ceramide phosphates (Cer-Ps) in chilled Arabidopsis were explored. Cer-Ps were analysed by thin layer chromatography (TLC) following in vivo metabolic radiolabelling. Ceramide kinase activity, gene expression and growth phenotype were determined in unstressed and cold-stressed wild type (WT) and Arabidopsis ceramide kinase mutant acd5. A rapid and transient formation of Cer-P occurs in cold-stressed WT Arabidopsis plantlets and cultured cells, which is strongly impaired in acd5 mutant. Although concomitant, Cer-P formation is independent of long-chain base phosphate (LCB-P) formation. No variation of ceramide kinase activity was measured in vitro in WT plantlets upon cold stress but the activity in acd5 mutant was further reduced by cold stress. At the seedling stage, acd5 response to cold was similar to that of WT. Nevertheless, acd5 seed germination was hypersensitive to cold and abscisic acid (ABA), and ABA-dependent gene expression was modified in acd5 seeds when germinated at low temperature. Our data involve for the first time Cer-P and ACD5 in low temperature response and further underline the complexity of sphingolipid signalling operating during cold stress.

  1. Nucleolus-derived mediators in oncogenic stress response and activation of p53-dependent pathways.

    PubMed

    Stępiński, Dariusz

    2016-08-01

    Rapid growth and division of cells, including tumor ones, is correlated with intensive protein biosynthesis. The output of nucleoli, organelles where translational machineries are formed, depends on a rate of particular stages of ribosome production and on accessibility of elements crucial for their effective functioning, including substrates, enzymes as well as energy resources. Different factors that induce cellular stress also often lead to nucleolar dysfunction which results in ribosome biogenesis impairment. Such nucleolar disorders, called nucleolar or ribosomal stress, usually affect cellular functioning which in fact is a result of p53-dependent pathway activation, elicited as a response to stress. These pathways direct cells to new destinations such as cell cycle arrest, damage repair, differentiation, autophagy, programmed cell death or aging. In the case of impaired nucleolar functioning, nucleolar and ribosomal proteins mediate activation of the p53 pathways. They are also triggered as a response to oncogenic factor overexpression to protect tissues and organs against extensive proliferation of abnormal cells. Intentional impairment of any step of ribosome biosynthesis which would direct the cells to these destinations could be a strategy used in anticancer therapy. This review presents current knowledge on a nucleolus, mainly in relation to cancer biology, which is an important and extremely sensitive element of the mechanism participating in cellular stress reaction mediating activation of the p53 pathways in order to counteract stress effects, especially cancer development.

  2. Embryo as an active granular fluid: stress-coordinated cellular constriction chains.

    PubMed

    Jason Gao, Guo-Jie; Holcomb, Michael C; Thomas, Jeffrey H; Blawzdziewicz, Jerzy

    2016-10-19

    Mechanical stress plays an intricate role in gene expression in individual cells and sculpting of developing tissues. However, systematic methods of studying how mechanical stress and feedback help to harmonize cellular activities within a tissue have yet to be developed. Motivated by our observation of the cellular constriction chains (CCCs) during the initial phase of ventral furrow formation in the Drosophila melanogaster embryo, we propose an active granular fluid (AGF) model that provides valuable insights into cellular coordination in the apical constriction process. In our model, cells are treated as circular particles connected by a predefined force network, and they undergo a random constriction process in which the particle constriction probability P is a function of the stress exerted on the particle by its neighbors. We find that when P favors tensile stress, constricted particles tend to form chain-like structures. In contrast, constricted particles tend to form compact clusters when P favors compression. A remarkable similarity of constricted-particle chains and CCCs observed in vivo provides indirect evidence that tensile-stress feedback coordinates the apical constriction activity. Our particle-based AGF model will be useful in analyzing mechanical feedback effects in a wide variety of morphogenesis and organogenesis phenomena. PMID:27545101

  3. S-Nitrosylation Positively Regulates Ascorbate Peroxidase Activity during Plant Stress Responses1

    PubMed Central

    Yang, Huanjie; Mu, Jinye; Chen, Lichao; Feng, Jian; Hu, Jiliang; Li, Lei; Zhou, Jian-Min; Zuo, Jianru

    2015-01-01

    Nitric oxide (NO) and reactive oxygen species (ROS) are two classes of key signaling molecules involved in various developmental processes and stress responses in plants. The burst of NO and ROS triggered by various stimuli activates downstream signaling pathways to cope with abiotic and biotic stresses. Emerging evidence suggests that the interplay of NO and ROS plays a critical role in regulating stress responses. However, the underpinning molecular mechanism remains poorly understood. Here, we show that NO positively regulates the activity of the Arabidopsis (Arabidopsis thaliana) cytosolic ascorbate peroxidase1 (APX1). We found that S-nitrosylation of APX1 at cysteine (Cys)-32 enhances its enzymatic activity of scavenging hydrogen peroxide, leading to the increased resistance to oxidative stress, whereas a substitution mutation at Cys-32 causes the reduction of ascorbate peroxidase activity and abolishes its responsiveness to the NO-enhanced enzymatic activity. Moreover, S-nitrosylation of APX1 at Cys-32 also plays an important role in regulating immune responses. These findings illustrate a unique mechanism by which NO regulates hydrogen peroxide homeostasis in plants, thereby establishing a molecular link between NO and ROS signaling pathways. PMID:25667317

  4. Activation of HIPK2 Promotes ER Stress-Mediated Neurodegeneration in Amyotrophic Lateral Sclerosis.

    PubMed

    Lee, Sebum; Shang, Yulei; Redmond, Stephanie A; Urisman, Anatoly; Tang, Amy A; Li, Kathy H; Burlingame, Alma L; Pak, Ryan A; Jovičić, Ana; Gitler, Aaron D; Wang, Jinhua; Gray, Nathanael S; Seeley, William W; Siddique, Teepu; Bigio, Eileen H; Lee, Virginia M-Y; Trojanowski, John Q; Chan, Jonah R; Huang, Eric J

    2016-07-01

    Persistent accumulation of misfolded proteins causes endoplasmic reticulum (ER) stress, a prominent feature in many neurodegenerative diseases including amyotrophic lateral sclerosis (ALS). Here we report the identification of homeodomain interacting protein kinase 2 (HIPK2) as the essential link that promotes ER-stress-induced cell death via the IRE1α-ASK1-JNK pathway. ER stress, induced by tunicamycin or SOD1(G93A), activates HIPK2 by phosphorylating highly conserved serine and threonine residues (S359/T360) within the activation loop of the HIPK2 kinase domain. In SOD1(G93A) mice, loss of HIPK2 delays disease onset, reduces cell death in spinal motor neurons, mitigates glial pathology, and improves survival. Remarkably, HIPK2 activation positively correlates with TDP-43 proteinopathy in NEFH-tTA/tetO-hTDP-43ΔNLS mice, sporadic ALS and C9ORF72 ALS, and blocking HIPK2 kinase activity protects motor neurons from TDP-43 cytotoxicity. These results reveal a previously unrecognized role of HIPK2 activation in ER-stress-mediated neurodegeneration and its potential role as a biomarker and therapeutic target for ALS. VIDEO ABSTRACT.

  5. Potential role for snoRNAs in PKR activation during metabolic stress.

    PubMed

    Youssef, Osama A; Safran, Sarah A; Nakamura, Takahisa; Nix, David A; Hotamisligil, Gökhan S; Bass, Brenda L

    2015-04-21

    Protein kinase RNA-activated (PKR) has long been known to be activated by viral double-stranded RNA (dsRNA) as part of the mammalian immune response. However, in mice PKR is also activated by metabolic stress in the absence of viral infection, and this requires a functional kinase domain, as well as a functional dsRNA-binding domain. The endogenous cellular RNA that potentially leads to PKR activation during metabolic stress is unknown. We investigated this question using mouse embryonic fibroblast cells expressing wild-type PKR (PKRWT) or PKR with a point mutation in each dsRNA-binding motif (PKRRM). Using this system, we identified endogenous RNA that interacts with PKR after induction of metabolic stress by palmitic acid (PA) treatment. Specifically, RIP-Seq analyses showed that the majority of enriched RNAs that interacted with WT PKR (≥twofold, false discovery rate ≤ 5%) were small nucleolar RNAs (snoRNAs). Immunoprecipitation of PKR in extracts of UV-cross-linked cells, followed by RT-qPCR, confirmed that snoRNAs were enriched in PKRWT samples after PA treatment, but not in the PKRRM samples. We also demonstrated that a subset of identified snoRNAs bind and activate PKR in vitro; the presence of a 5'-triphosphate enhanced PKR activity compared with the activity with a 5'-monophosphate, for some, but not all, snoRNAs. Finally, we demonstrated PKR activation in cells upon snoRNA transfection, supporting our hypothesis that endogenous snoRNAs can activate PKR. Our results suggest an unprecedented and unexpected model whereby snoRNAs play a role in the activation of PKR under metabolic stress.

  6. Potential role for snoRNAs in PKR activation during metabolic stress

    PubMed Central

    Youssef, Osama A.; Safran, Sarah A.; Nix, David A.; Hotamisligil, Gökhan S.; Bass, Brenda L.

    2015-01-01

    Protein kinase RNA-activated (PKR) has long been known to be activated by viral double-stranded RNA (dsRNA) as part of the mammalian immune response. However, in mice PKR is also activated by metabolic stress in the absence of viral infection, and this requires a functional kinase domain, as well as a functional dsRNA-binding domain. The endogenous cellular RNA that potentially leads to PKR activation during metabolic stress is unknown. We investigated this question using mouse embryonic fibroblast cells expressing wild-type PKR (PKRWT) or PKR with a point mutation in each dsRNA-binding motif (PKRRM). Using this system, we identified endogenous RNA that interacts with PKR after induction of metabolic stress by palmitic acid (PA) treatment. Specifically, RIP-Seq analyses showed that the majority of enriched RNAs that interacted with WT PKR (≥twofold, false discovery rate ≤ 5%) were small nucleolar RNAs (snoRNAs). Immunoprecipitation of PKR in extracts of UV–cross-linked cells, followed by RT-qPCR, confirmed that snoRNAs were enriched in PKRWT samples after PA treatment, but not in the PKRRM samples. We also demonstrated that a subset of identified snoRNAs bind and activate PKR in vitro; the presence of a 5′-triphosphate enhanced PKR activity compared with the activity with a 5′-monophosphate, for some, but not all, snoRNAs. Finally, we demonstrated PKR activation in cells upon snoRNA transfection, supporting our hypothesis that endogenous snoRNAs can activate PKR. Our results suggest an unprecedented and unexpected model whereby snoRNAs play a role in the activation of PKR under metabolic stress. PMID:25848059

  7. Preparing a Resume: A Learning Activity for Ninth Grade Students in Introduction to Occupations.

    ERIC Educational Resources Information Center

    Hunter, Joan

    This study examines the analysis, design, development, implementation, and evaluation of an instructional development project addressing resume writing. The project produced a learning activity package (LAP) that guides ninth-grade students through the steps necessary to write a complete resume. The LAP was organized by the main sections placed in…

  8. Free convection in parallelogram-shaped enclosures with isothermal active walls: viscous shear stress in active systems

    NASA Astrophysics Data System (ADS)

    Baïri, A.; Zarco-Pernia, E.; García de María, J.-M.; Laraqi, N.

    2012-10-01

    Thermocouples are often used for thermoregulation of active thermal systems. When the junctions of these sensors are under a natural convection flow, it is necessary to take into account the viscous stress that can affect the measurement of temperature and therefore the regulation set points. The main objective of this work is to study the viscous shear stress taking place close to the active hot wall in closed air-filled cavities of parallelogrammic shape. The influence of shear stress is examined for different inclination angles of the cavity and large Rayleigh numbers which are usual in thermal applications. The local stress distributions are presented for the steady state for all the geometric configurations considered. The Nusselt number at the hot wall as well as the temperature and stream function distributions in the cavities are also included. The findings obtained from the numerical simulation using the finite volume method are validated by thermal measurements on an experimental cavity. This study confirms the need to properly choose the location of thermocouples in the reference cell used for controlling the active system.

  9. Earthquake cluster activity beneath the Tanzawa Mountains region, Japan: Migration of hypocenters and low stress drop

    NASA Astrophysics Data System (ADS)

    Yamada, T.; Yukutake, Y.

    2013-12-01

    An earthquake cluster activity was observed beneath the Tanzawa Mountains region, Japan with a depth of 20 km in the end of January, 2012. Japan Meteorological Agency (JMA) determined hypocenters of 76 earthquakes with M > 2 in the area within 50 hours. Five of them had magnitudes greater than 4 and the largest one was 5.4. Four out of the five earthquakes had the reverse-type focal mechanisms with the P axis in the NW-SE direction. First we relocated hypocenters of the activity following the method of Yukutake et al. (2012). We estimated relative arrival times of P and S waves by calculating the coefficients of the cross correlation and relocated hypocenters with the double-difference relocation method (Waldhauser and Ellsworth, 2000). We found that the cluster activity showed a migration from the first earthquake of the activity. The parabolic migration speed was consistent with the migration speed of the deep tremor sources (Ide et al., 2010) for which the fluid activity would play an important role. We then analyzed stress drops of 17 earthquakes with M > 3.5 that occurred from January, 2000 to June, 2012 in the area of the cluster activity. We calculated empirical Green's functions from waveforms of earthquakes with magnitudes of 3.0 to 3.2 and estimated stress drops of the earthquakes assuming that the source spectra can be expressed as the omega-squared model. We found that earthquakes of the cluster activity had smaller stress drops by an order of magnitude than the values of earthquakes that occurred in the same area before the cluster activity. These results suggest that the fluid played an important role for the earthquake cluster activity. That is, the fluid increased the pore pressure, decreased the effective normal stress and triggered the cluster activity. The difference of the rupture speed and the change of the rigidity might also be candidates that account for our results. They, however, can hardly explain the results quantitatively. Fig

  10. Interrelation Between Oxidative Stress and Complement Activation in Models of Age-Related Macular Degeneration.

    PubMed

    Pujol-Lereis, Luciana M; Schäfer, Nicole; Kuhn, Laura B; Rohrer, Bärbel; Pauly, Diana

    2016-01-01

    Millions of individuals older than 50-years suffer from age-related macular degeneration (AMD). Associated with this multifactorial disease are polymorphisms of complement factor genes and a main environmental risk factor-oxidative stress. Until now the linkage between these risk factors for AMD has not been fully understood. Recent studies, integrating results on oxidative stress, complement activation, epidemiology and ocular pathology suggested the following sequence in AMD-etiology: initially, chronic oxidative stress results in modification of proteins and lipids in the posterior of the eye; these tissue alterations trigger chronic inflammation, involving the complement system; and finally, invasive immune cells facilitate pathology in the retina. Here, we summarize the results for animal studies which aim to elucidate this molecular interplay of oxidative events and tissue-specific complement activation in the eye.

  11. Heat-shock stress activates a novel nuclear import pathway mediated by Hikeshi

    PubMed Central

    Imamoto, Naoko; Kose, Shingo

    2012-01-01

    Cellular stresses significantly affect nuclear transport systems. Nuclear transport pathways mediated by importin β-family members, which are active under normal conditions, are downregulated. During thermal stress, a nuclear import pathway mediated by a novel carrier, which we named Hikeshi, becomes active. Hikeshi is not a member of the importin β family and mediates the nuclear import of Hsp70s. Unlike importin β family-mediated nuclear transport, the Hikeshi-mediated nuclear import of Hsp70s is not coupled to the GTPase cycle of the small GTPase Ran but rather is coupled with the ATPase cycle of Hsp70s. Hikeshi-mediated nuclear import is essential for the attenuation and reversal of the thermal stress response in human cells. The mechanism and functions of this newly identified nuclear import pathway will be discussed. PMID:22895094

  12. Heating and ultraviolet light activate anti-stress gene functions in humans.

    PubMed

    Semenkov, Victor F; Michalski, Anatoli I; Sapozhnikov, Alexander M

    2015-01-01

    Different environmental factors (i.e., toxins, heavy metals, ultraviolet (UV) rays, and X-radiation) cause damage to DNA, cell membranes and other organelles and induce oxidative stress, which results in the excessive production of reactive oxygen species (ROS) by phagocytes. All types of cell stress are accompanied by the activation of anti-stress genes that can suppress ROS synthesis. We hypothesized that different environmental factors would affect organisms through the activation of anti-stress genes by autologous serum (AS) proteins, followed by the synthesis of molecules that increase cell resistance to oxidative stress. The goal of this work was to study the influence of AS on ROS production by peripheral blood neutrophils isolated from donors in different age groups. Neutrophils were isolated from 59 donors (38-94 years old). AS was heated at 100°C for 30 s. or irradiated by UV light at 200-280 nm and 8 W for 10 min. Neutrophils were exposed to heat shock at 42°C for 1 min. (short-term heating stress) or 43°C for 10 min., followed by the determination of the chemiluminescence reaction induced by zymosan. AS can increase or decrease ROS production by neutrophils depending on the structure of the proteins in the serum; these structures can be changed by heating or UV treatment and the temperature of their interaction (4 or 37°C). We propose that the effect of environmental factors on AS proteins can cause an adverse increase in oxidative stress levels due to the functional reduction of anti-stress genes. We found a negative correlation between the quantity of intracellular Hsp70 and levels of intracellular ROS production following 10 min of heat shock at 43°C. Short-term heating stress (1 min) at 42°C was followed by a prominent reduction in ROS production. This effect may be a result of the impact of the hormone adrenaline on the functions of anti-stress genes. Indeed, the same effect was observed after treatment of the neutrophils with adrenaline at

  13. Accumulation of plasmid-mediated fluoroquinolone resistance genes, qepA and qnrS1, in Enterobacter aerogenes co-producing RmtB and class A beta-lactamase LAP-1.

    PubMed

    Park, Yeon-Joon; Yu, Jin Kyung; Kim, Sang-Il; Lee, Kyungwon; Arakawa, Yoshichika

    2009-01-01

    A new plasmid-mediated fluoroquinolone efflux pump gene, qepA, is known to be associated with the rmtB gene, which confers high-level resistance to aminoglycosides. We investigated the qepA gene in 573 AmpC-producing Enterobacteriaceae including one Citrobacter freundii known to harbor rmtB. Of them, two clonally unrelated E. aerogenes harbored qepA. Both isolates co-harbored rmtB, qnrS1, qepA, and bla(LAP-1) on an IncFI type plasmid. The qepA was flanked by two copies of IS26 containing ISCR3C, tnpA, tnpR, bla(TEM), and rmtB. The qnrS1 and bla(LAP-1) were located upstream of qepA. All the resistance determinants (qepA, qnrS1, rmtB, and bla(LAP-1)) were co-transferred to E. coli J53 by filter mating from both isolates. Although the prevalence of qepA is currently low, considering the presence of ISCR3C and the possibility of co-selection and co-transferability of plasmids, more active surveillance for these multi-drug resistant bacteria and prudent use of antimicrobials are needed.

  14. Oxidative Stress Impairs the Stimulatory Effect of S100 Proteins on Protein Phosphatase 5 Activity.

    PubMed

    Yamaguchi, Fuminori; Tsuchiya, Mitsumasa; Shimamoto, Seiko; Fujimoto, Tomohito; Tokumitsu, Hiroshi; Tokuda, Masaaki; Kobayashi, Ryoji

    2016-01-01

    Oxidative stress is the consequence of an imbalance between the production of harmful reactive oxygen species and the cellular antioxidant system for neutralization, and it activates multiple intracellular signaling pathways, including apoptosis signal-regulating kinase 1 (ASK1). Protein phosphatase 5 (PP5) is a serine/threonine phosphatase involved in oxidative stress responses. Previously, we reported that S100 proteins activate PP5 in a calcium-dependent manner. S100 proteins belong to a family of small EF-hand calcium-binding proteins involved in many processes such as cell proliferation, differentiation, apoptosis, and inflammation. Therefore, we investigated the effects of oxidative stress on S100 proteins, their interaction with PP5, and PP5 enzyme activity. Recombinant S100A2 was easily air-oxidized or Cu-oxidized, and oxidized S100A2 formed cross-linked dimers and higher molecular-mass complexes. The binding of oxidized S100A2 to PP5 was reduced, resulting in decreased PP5 activation in vitro. Oxidation also impaired S100A1, S100A6, S100B, and S100P to activate PP5, although the low dose of oxidized S100 proteins still activated PP5. Hydrogen peroxide (H2O2) induced S100A2 oxidation in human keratinocytes (HaCaT) and human hepatocellular carcinoma (Huh-7) cells. Furthermore, H2O2 reduced the binding of S100A2 to PP5 and decreased PP5 activation in HaCaT and Huh-7 cells. Importantly, even the low dose of S100A2 achieved by knocking down increased dephosphorylation of ASK1 and reduced caspase 3/7 activity in Huh-7 cells treated with H2O2. These results indicate that oxidative stress impairs the ability of S100 proteins to bind and activate PP5, which in turn modulates the ASK1-mediated signaling cascades involved in apoptosis. PMID:27600583

  15. Influence of arbuscular mycorrhiza on the growth and antioxidative activity in cyclamen under heat stress.

    PubMed

    Maya, Moslama Aktar; Matsubara, Yoh-ichi

    2013-07-01

    The influence of the arbuscular mycorrhizal (AM) fungus, Glomus fasciculatum, on the growth, heat stress responses and the antioxidative activity in cyclamen (Cyclamen persicum Mill.) plants was studied. Cyclamen plants (inoculated or not with the AM fungus) were placed in a commercial potting media at 17-20 °C for 12 weeks in a greenhouse and subsequently subjected to two temperature conditions in a growth chamber. Initially, plants were grown at 20 °C for 4 weeks as a no heat stress (HS-) condition, followed by 30 °C for another 4 weeks as a heat stress (HS+) condition. Different morphological and physiological growth parameters were compared between G. fasciculatum-inoculated and noninoculated plants. The mycorrhizal symbiosis markedly enhanced biomass production and HS + responses in plants compared to that in the controls. A severe rate of leaf browning (80-100%) was observed in control plants, whereas the mycorrhizal plants showed a minimum rate of leaf browning under HS + conditions. The mycorrhizal plants showed an increase activity of antioxidative enzymes such as superoxide dismutase and ascorbate peroxidase, as well as an increase in ascorbic acid and polyphenol contents. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity also showed a greater response in mycorrhizal plants than in the control plants under each temperature condition. The results indicate that in cyclamen plants, AM fungal colonisation alleviated heat stress damage through an increased antioxidative activity and that the mycorrhizal symbiosis strongly enhanced temperature stress tolerance which promoted plant growth and increased the host biomass under heat stress.

  16. Does pulsed low intensity ultrasound allow early return to normal activities when treating stress fractures? A review of one tarsal navicular and eight tibial stress fractures.

    PubMed

    Brand, J C; Brindle, T; Nyland, J; Caborn, D N; Johnson, D L

    1999-01-01

    We sought to evaluate the efficacy of daily pulsed low intensity ultrasound (LIUS) with early return to activities for the treatment of lower extremity stress fractures. Eight patients (2 males, 6 females) with radiographic and bone scan confirmed tibial stress fractures participated in this study. Additionally, a case report of a tarsal navicular stress fracture is described. All patients except one were involved in athletics. Prior to the study, subjects completed a 5 question, 10 cm visual analog scale (VAS) regarding pain level (10 = extreme pain, 1 = no pain) and were assessed for functional performance. Subjects received 20-minute LIUS treatments 5 times a week for 4 weeks. Subjects maintained all functional activities during the treatment period. Seven patients with posterior-medial stress fractures participated without a brace. Subjects were re-tested after 4 weeks of treatment. Mann-Whitney U tests (VAS data) and paired t-tests (functional tests) assessed statistical significance (p<0.05). Although the intensity of practice was diminished in some instances, no time off from competitive sports was prescribed for the patients with the tibial stress fractures. The patient with the anterior tibial stress fracture underwent tibial intramedullary nailing at the conclusion of a season of play. In this uncontrolled experience, treatment of tibial stress fractures with daily pulsed LIUS was effective in pain relief and early return to vigorous activity without bracing for the patients with posterior-medial stress fractures.

  17. Determination of oxidative stress and activities of antioxidant enzymes in guinea pigs treated with haloperidol

    PubMed Central

    GUMULEC, JAROMIR; RAUDENSKA, MARTINA; HLAVNA, MARIAN; STRACINA, TIBOR; SZTALMACHOVA, MARKETA; TANHAUSEROVA, VERONIKA; PACAL, LUKAS; RUTTKAY-NEDECKY, BRANISLAV; SOCHOR, JIRI; ZITKA, ONDREJ; BABULA, PETR; ADAM, VOJTECH; KIZEK, RENE; NOVAKOVA, MARIE; MASARIK, MICHAL

    2013-01-01

    Guinea pigs (Cavia porcellus) were treated with haloperidol (HP), and free radical (FR) and ferric reducing antioxidant power (FRAP) assays were used to determine oxidative stress levels. Furthermore, the superoxide dismutase (SOD), glutathione reductase (GR) and glutathione-S-transferase (GST) activity levels were detected and glucose levels and the reduced and oxidized glutathione (GSH/GSSG) ratio were measured in HP-treated and untreated guinea pigs. The present study demonstrated that the administration of HP causes significant oxidative stress in guinea pigs (P=0.022). In animals treated with HP, the activity of GST was significantly increased compared with a placebo (P= 0.007). The elevation of SOD and GR activity levels and increase in the levels of glutathione (GSH) in HP-treated animals were not statistically significant. In the HP-untreated animals, a significant positive correlation was observed between oxidative stress detected by the FR method and GST (r=0.88, P=0.008) and SOD (r=0.86, P= 0.01) activity levels, respectively. A significant negative correlation between the levels of plasma glucose and oxidative stress detected by the FRAP method was observed (r=−0.78, P=0.04). Notably, no significant correlations were observed in the treated animals. In the HP-treated group, two subgroups of animals were identified according to their responses to oxidative stress. The group with higher levels of plasma HP had higher enzyme activity and reactive oxygen species production compared with the group with lower plasma levels of HP. The greatest difference in activity (U/μl) between the two groups of animals was for GR. PMID:23403848

  18. Localization of hydrogen peroxide accumulation and diamine oxidase activity in pea root nodules under aluminum stress.

    PubMed

    Sujkowska-Rybkowska, Marzena; Borucki, Wojciech

    2014-02-01

    Aluminum (Al) is one of the environmental stressors that induces formation of reactive oxygen species (ROS) in plants. Hydrogen peroxide (H2O2) and H2O2-generated apoplast diamine oxidase (DAO) activity were detected cytochemically via transmission electron microscopy (TEM), in pea (Pisum sativum L.) root nodules exposed to high (50 μM AlCl3, for 2 and 24h) Al stress. The nodules were shown to respond to Al stress by disturbances in infection thread (IT) growth, bacteria endocytosis, premature degeneration of bacteroidal tissue and generation of H2O2 in nodule apoplast. Large amounts of peroxide were found at the same sites as high DAO activity under Al stress, suggesting that DAO is a major source of Al-induced peroxide accumulation in the nodules. Peroxide distribution and DAO activity in the nodules of both control plants and Al-treated ones were typically found in the plant cell walls, intercellular spaces and infection threads. However, 2 h Al treatment increased DAO activity and peroxide accumulation in the nodule apoplast and bacteria within threads. A prolonged Al treatment (24 h) increased the H2O2 content and DAO activity in the nodule apoplast, especially in the thread walls, matrix and bacteria within infection threads. In addition to ITs, prematurely degenerated bacteroids, which occurred in response to Al, were associated with intense staining for H2O2 and DAO activity. These results suggest the involvement of DAO in the production of a large amount of H2O2 in the nodule apoplast under Al stress. The role of reactive oxygen species in pea-Rhizobium symbiosis under Al stress is discussed. PMID:24246127

  19. Responses of proteolytic enzymes in embryonic axes of germinating bean seeds under copper stress.

    PubMed

    Karmous, Inès; Jaouani, Khadija; El Ferjani, Ezzedine; Chaoui, Abdelilah

    2014-07-01

    The changes in protease activities in embryonic axes during the first days of bean (Phaseolus vulgaris L.) seed germination were investigated in response to copper stress. Synthetic substrates and specific protease inhibitors have been used to define qualitatively and quantitatively different catalytic classes, particularly endoproteases (EP), carboxypeptidases (CP) and aminopeptidases (AP), then identify which ones were affected in the presence of copper. In fact, a failure in storage proteins mobilization and a disorder of nitrogen supply at enzymatic level occurred in Cu. In fact, Cu inhibited azocaseinolytic activity (ACA) and cysteine-, aspartic-, serine-, and metallo-endopeptidases activities (Cys-EP, Asp-EP, Ser-Ep, and Met-EP, respectively). Besides, Cu affected leucine- and proline-aminopeptidases (LAP and PAP, respectively) and glycine-carboxypeptidases (Gly-CP). The proteolytic responses might also be associated with the decrease in defense capacity in the Cu-treated embryos.

  20. Mitogen-activated protein kinase activation by oxidative and bacterial stress in an amphibian cell culture model.

    PubMed

    Carter, Lisa A; Tabor, Maija B; Bonner, James C; Bonner, Lisa A

    2002-07-01

    The decline of many amphibian species could be caused by their susceptibility to environmental pollutants that cause cellular stress and cell death. A variety of intracellular signal transduction pathways are activated by environmental stress factors, which result in cell death. Mitogen-activated protein kinases are intracellular signaling molecules that include the extracellular signal-regulated kinases (ERK-1 and ERK-2). We used cultured (italic)Xenopus(/italic) tadpole cells (XTC-2 cells) to investigate the activation of ERK by oxidative or bacterial stress, two environmental factors that could contribute to pollution in aquatic systems. We exposed XTC-2 cell monolayers to hydrogen peroxide or bacterial lipopolysaccharide and measured ERK activation by Western blotting using antibodies raised against phosphorylated ERK-1 and ERK-2. Only ERK-2 was detected in XTC-2 cells. Both hydrogen peroxide and lipopolysaccharide caused ERK-2 phosphorylation in a time- and concentration-dependent manner. Hydrogen peroxide caused a 20- to 30-fold increase in ERK-2 activation that peaked 30 min after treatment, and lipopolysaccharide induced a 5- to 10-fold increase in ERK-2 activation that peaked 60 min after treatment. PD98059, an inhibitor of the ERK pathway, reduced the cytotoxic response of XTC-2 cells to hydrogen peroxide or lipopolysaccharide. These data suggest that ERK-2 is an intracellular target of oxidative and bacterial stress in amphibians that mediates, at least in part, the cytotoxic response to hydrogen peroxide or lipopolysaccharide. Moreover, the (italic)Xenopus(/italic) (XTC-2) cell culture system could serve as a useful model to identify agents that might threaten amphibian populations and human health.

  1. Stream mesocosm response sensitivities to simulated ion stress in produced waters from resource extraction activities

    EPA Science Inventory

    To increase the ecological relevance of laboratory exposures intent on determining species sensitivity to ion stress from resource extraction activities we have conducted several stream mesocosm dosing studies that pair single-species and community-level responses in-situ and all...

  2. Behavioral Activation in the Treatment of Comorbid Posttraumatic Stress Disorder and Major Depressive Disorder

    ERIC Educational Resources Information Center

    Mulick, Patrick S.; Naugle, Amy E.

    2009-01-01

    This study investigated the efficacy of 10-weeks of Behavioral Activation (BA) in the treatment of comorbid Post-traumatic Stress Disorder (PTSD) and Major Depressive Disorder (MDD) in four adults using a nonconcurrent multiple baseline across participants design. All participants met full "DSM-IV" criteria for both MDD and PTSD at the outset of…

  3. Two Dictyostelium tyrosine kinase–like kinases function in parallel, stress-induced STAT activation pathways

    PubMed Central

    Araki, Tsuyoshi; Vu, Linh Hai; Sasaki, Norimitsu; Kawata, Takefumi; Eichinger, Ludwig; Williams, Jeffrey G.

    2014-01-01

    When Dictyostelium cells are hyperosmotically stressed, STATc is activated by tyrosine phosphorylation. Unusually, activation is regulated by serine phosphorylation and consequent inhibition of a tyrosine phosphatase: PTP3. The identity of the cognate tyrosine kinase is unknown, and we show that two tyrosine kinase–like (TKL) enzymes, Pyk2 and Pyk3, share this function; thus, for stress-induced STATc activation, single null mutants are only marginally impaired, but the double mutant is nonactivatable. When cells are stressed, Pyk2 and Pyk3 undergo increased autocatalytic tyrosine phosphorylation. The site(s) that are generated bind the SH2 domain of STATc, and then STATc becomes the target of further kinase action. The signaling pathways that activate Pyk2 and Pyk3 are only partially overlapping, and there may be a structural basis for this difference because Pyk3 contains both a TKL domain and a pseudokinase domain. The latter functions, like the JH2 domain of metazoan JAKs, as a negative regulator of the kinase domain. The fact that two differently regulated kinases catalyze the same phosphorylation event may facilitate specific targeting because under stress, Pyk3 and Pyk2 accumulate in different parts of the cell; Pyk3 moves from the cytosol to the cortex, whereas Pyk2 accumulates in cytosolic granules that colocalize with PTP3. PMID:25143406

  4. Enhancing Maritime Education and Training: Measuring a Ship Navigator's Stress Based on Salivary Amylase Activity

    ERIC Educational Resources Information Center

    Murai, Koji; Wakida, Shin-Ichi; Miyado, Takashi; Fukushi, Keiichi; Hayashi, Yuji; Stone, Laurie C.

    2009-01-01

    Purpose: The purpose of this paper is to propose that the measurement of salivary amylase activity is an effective index to evaluate the stress of a ship navigator for safe navigation training and education. Design/methodology/approach: Evaluation comes from the simulator and actual on-board experiments. The subjects are real captains who have…

  5. The influence of motor activity on the development of cardiac arrhythmias during experimental emotional stress

    NASA Technical Reports Server (NTRS)

    Ulyaninskiy, L. S.; Urmancheyeva, T. G.; Stepanyan, Y. P.; Fufacheva, A. A.; Gritsak, A. V.; Kuznetsova, B. A.; Kvitka, A. A.

    1982-01-01

    Experimental emotional stress which can produce various disorders of cardiac rhythm: sinus tachycardia, atrial fibrillation, ventricular, extrasystoles and paroxysmal ventricular tachysystoles was studied. In these conditions the adrenalin content in the blood and myocardium is increased 3 to 4 times. It is found that moderate motor activity leads to a relative decrease of adrenalin in the myocardium and arrest of cardiac arrhythmias.

  6. Romantic and Sexual Activities, Parent-Adolescent Stress, and Depressive Symptoms among Early Adolescent Girls

    ERIC Educational Resources Information Center

    Davila, Joanne; Stroud, Catherine B.; Starr, Lisa R.; Miller, Melissa Ramsay; Yoneda, Athena; Hershenberg, Rachel

    2009-01-01

    Building on evidence that romantic experiences are associated with depressive symptoms in adolescence, we examined their bidirectional association, as well as the role of sexual activity and parent-adolescent stress in their association. Data were collected from 71 early adolescent girls (M age 13.45 years; SD = 0.68) and their primary caregiver…

  7. Microglia activation regulates GluR1 phosphorylation in chronic unpredictable stress-induced cognitive dysfunction.

    PubMed

    Liu, Mingchao; Li, Juan; Dai, Peng; Zhao, Fang; Zheng, Gang; Jing, Jinfei; Wang, Jiye; Luo, Wenjing; Chen, Jingyuan

    2015-01-01

    Chronic stress is considered to be a major risk factor in the development of psychopathological syndromes in humans. Cognitive impairments and long-term potentiation (LTP) impairments are increasingly recognized as major components of depression, anxiety disorders and other stress-related chronic psychological illnesses. It seems timely to systematically study the potentially underlying neurobiological mechanisms of altered cognitive and synaptic plasticity in the course of chronic stress. In the present study, a rat model of chronic unpredictable stress (CUS) induced a cognitive impairment in spatial memory in the Morris water maze (MWM) test and a hippocampal LTP impairment. CUS also induced hippocampal microglial activation and attenuated phosphorylation of glutamate receptor 1 (GluR1 or GluA1). Moreover, chronic treatment with the selective microglial activation blocker, minocycline (120 mg/kg per day), beginning 3 d before CUS treatment and continuing through the behavioral testing period, prevented the CUS-induced impairments of spatial memory and LTP induction. Additional studies showed that minocycline-induced inhibition of microglia activation was associated with increased phosphorylation of GluR1. These results suggest that hippocampal microglial activation modulates the level of GluR1 phosphorylation and might play a causal role in CUS-induced cognitive and LTP disturbances.

  8. TAp73 promotes cell survival upon genotoxic stress by inhibiting p53 activity

    PubMed Central

    Chen, Dongshi; Ming, Lihua; Zou, Fangdong; Peng, Ye; Houten, Bennett Van; Yu, Jian; Zhang, Lin

    2014-01-01

    p53 plays a key role in regulating DNA damage response by suppressing cell cycle progression or inducing apoptosis depending on extent of DNA damage. However, it is not clear why mild genotoxic stress favors growth arrest, whereas excessive lesions signal cells to die. Here we showed that TAp73, a p53 homologue thought to have a similar function as p53, restrains the transcriptional activity of p53 and prevents excessive activation of its downstream targets upon low levels of DNA damage, which results in cell cycle arrest. Extensive DNA damage triggers TAp73 depletion through ubiquitin/proteasome-mediated degradation of E2F1, leading to enhanced transcriptional activation by p53 and subsequent induction of apoptosis. These findings provide novel insights into the regulation of p53 function and suggest that TAp73 keeps p53 activity in check in regulating cell fate decisions upon genotoxic stress. PMID:25237903

  9. Social stress in mice induces urinary bladder overactivity and increases TRPV1 channel-dependent afferent nerve activity

    PubMed Central

    Heppner, Thomas J.; Tykocki, Nathan R.; Erickson, Cuixia Shi; Vizzard, Margaret A.; Nelson, Mark T.

    2015-01-01

    Social stress has been implicated as a cause of urinary bladder hypertrophy and dysfunction in humans. Using a murine model of social stress, we and others have shown that social stress leads to bladder overactivity. Here, we show that social stress leads to bladder overactivity, increased bladder compliance, and increased afferent nerve activity. In the social stress paradigm, 6-wk-old male C57BL/6 mice were exposed for a total of 2 wk, via barrier cage, to a C57BL/6 retired breeder aggressor mouse. We performed conscious cystometry with and without intravesical infusion of the TRPV1 inhibitor capsazepine, and measured pressure-volume relationships and afferent nerve activity during bladder filling using an ex vivo bladder model. Stress leads to a decrease in intermicturition interval and void volume in vivo, which was restored by capsazepine. Ex vivo studies demonstrated that at low pressures, bladder compliance and afferent activity were elevated in stressed bladders compared with unstressed bladders. Capsazepine did not significantly change afferent activity in unstressed mice, but significantly decreased afferent activity at all pressures in stressed bladders. Immunohistochemistry revealed that TRPV1 colocalizes with CGRP to stain nerve fibers in unstressed bladders. Colocalization significantly increased along the same nerve fibers in the stressed bladders. Our results support the concept that social stress induces TRPV1-dependent afferent nerve activity, ultimately leading to the development of overactive bladder symptoms. PMID:26224686

  10. Using Activity-Related Behavioural Features towards More Effective Automatic Stress Detection

    PubMed Central

    Giakoumis, Dimitris; Drosou, Anastasios; Cipresso, Pietro; Tzovaras, Dimitrios; Hassapis, George; Gaggioli, Andrea; Riva, Giuseppe

    2012-01-01

    This paper introduces activity-related behavioural features that can be automatically extracted from a computer system, with the aim to increase the effectiveness of automatic stress detection. The proposed features are based on processing of appropriate video and accelerometer recordings taken from the monitored subjects. For the purposes of the present study, an experiment was conducted that utilized a stress-induction protocol based on the stroop colour word test. Video, accelerometer and biosignal (Electrocardiogram and Galvanic Skin Response) recordings were collected from nineteen participants. Then, an explorative study was conducted by following a methodology mainly based on spatiotemporal descriptors (Motion History Images) that are extracted from video sequences. A large set of activity-related behavioural features, potentially useful for automatic stress detection, were proposed and examined. Experimental evaluation showed that several of these behavioural features significantly correlate to self-reported stress. Moreover, it was found that the use of the proposed features can significantly enhance the performance of typical automatic stress detection systems, commonly based on biosignal processing. PMID:23028461

  11. Airborne particulate matter selectively activates endoplasmic reticulum stress response in the lung and liver tissues

    PubMed Central

    Laing, Suzette; Wang, Guohui; Briazova, Tamara; Zhang, Chunbin; Wang, Aixia; Zheng, Ze; Gow, Alexander; Chen, Alex F.; Rajagopalan, Sanjay; Chen, Lung Chi; Sun, Qinghua

    2010-01-01

    Recent studies have suggested a link between inhaled particulate matter (PM) exposure and increased mortality and morbidity associated with pulmonary and cardiovascular diseases. However, a precise understanding of the biological mechanism underlying PM-associated toxicity and pathogenesis remains elusive. Here, we investigated the impact of PM exposure in intracellular stress signaling pathways with animal models and cultured cells. Inhalation exposure of the mice to environmentally relevant fine particulate matter (aerodynamic diameter < 2.5 μm, PM2.5) induces endoplasmic reticulum (ER) stress and activation of unfolded protein response (UPR) in the lung and liver tissues as well as in the mouse macrophage cell line RAW264.7. Ambient PM2.5 exposure activates double-strand RNA-activated protein kinase-like ER kinase (PERK), leading to phosphorylation of translation initiation factor eIF2α and induction of C/EBP homologous transcription factor CHOP/GADD153. Activation of PERK-mediated UPR pathway relies on the production of reactive oxygen species (ROS) and is critical for PM2.5-induced apoptosis. Furthermore, PM2.5 exposure can activate ER stress sensor IRE1α, but it decreases the activity of IRE1α in splicing the mRNA encoding the UPR trans-activator X-box binding protein 1 (XBP1). Together, our study suggests that PM2.5 exposure differentially activates the UPR branches, leading to ER stress-induced apoptosis through the PERK-eIF2α-CHOP UPR branch. This work provides novel insights into the cellular and molecular basis by which ambient PM2.5 exposure elicits its cytotoxic effects that may be related to air pollution-associated pathogenesis. PMID:20554909

  12. Prodigiosin activates endoplasmic reticulum stress cell death pathway in human breast carcinoma cell lines.

    PubMed

    Pan, Mu-Yun; Shen, Yuh-Chiang; Lu, Chien-Hsing; Yang, Shu-Yi; Ho, Tsing-Fen; Peng, Yu-Ta; Chang, Chia-Che

    2012-12-15

    Prodigiosin is a bacterial tripyrrole pigment with potent cytotoxicity against diverse human cancer cell lines. Endoplasmic reticulum (ER) stress is initiated by accumulation of unfolded or misfolded proteins in the ER lumen and may induce cell death when irremediable. In this study, the role of ER stress in prodigiosin-induced cytotoxicity was elucidated for the first time. Comparable to the ER stress inducer thapsigargin, prodigiosin up-regulated signature ER stress markers GRP78 and CHOP in addition to activating the IRE1, PERK and ATF6 branches of the unfolded protein response (UPR) in multiple human breast carcinoma cell lines, confirming prodigiosin as an ER stress inducer. Prodigiosin transcriptionally up-regulated CHOP, as evidenced by its promoting effect on the CHOP promoter activity. Of note, knockdown of CHOP effectively lowered prodigiosin's capacity to evoke PARP cleavage, reduce cell viability and suppress colony formation, highlighting an essential role of CHOP in prodigiosin-induced cytotoxic ER stress response. In addition, prodigiosin down-regulated BCL2 in a CHOP-dependent manner. Importantly, restoration of BCL2 expression blocked prodigiosin-induced PARP cleavage and greatly enhanced the survival of prodigiosin-treated cells, suggesting that CHOP-dependent BCL2 suppression mediates prodigiosin-elicited cell death. Moreover, pharmacological inhibition of JNK by SP600125 or dominant-negative blockade of PERK-mediated eIF2α phosphorylation impaired prodigiosin-induced CHOP up-regulation and PARP cleavage. Collectively, these results identified ER stress-mediated cell death as a mode-of-action of prodigiosin's tumoricidal effect. Mechanistically, prodigiosin engages the IRE1-JNK and PERK-eIF2α branches of the UPR signaling to up-regulate CHOP, which in turn mediates BCL2 suppression to induce cell death.

  13. Heat stress and antioxidant enzyme activity in bubaline ( Bubalus bubalis) oocytes during in vitro maturation

    NASA Astrophysics Data System (ADS)

    Waiz, Syma Ashraf; Raies-ul-Haq, Mohammad; Dhanda, Suman; Kumar, Anil; Goud, T. Sridhar; Chauhan, M. S.; Upadhyay, R. C.

    2016-09-01

    In vitro environments like heat stress usually increase the production of reactive oxygen species in bubaline oocytes which have been implicated as one of the major causes for reduced developmental competence. Oocytes during meiotic maturation are sensitive to oxidative stress, and heat stress accelerates cellular metabolism, resulting in the higher production of free radicals. Therefore, the aim of present work was to assess the impact of heat stress during meiotic maturation on bubaline cumulus-oocyte complexes (COC), denuded oocytes (DO), and cumulus cell mass in terms of their oxidative status. Accordingly, for control group, COC were matured at 38.5 °C for complete 24 h of meiotic maturation and heat stress of 40.5 and 41.5 °C was applied to COC during the first 12 h of maturation and then moved to 38.5 °C for rest of the 12 h. In another group, COC after maturation were denuded from the surrounding cumulus cells by manual pipetting. Results indicated that the production of reactive oxygen species (ROS), lipid peroxides, and nitric oxide (NO) was significantly ( P < 0.05) higher in the oocytes subjected to heat stress (40.5 and 41.5 °C) during meiotic maturation compared to the oocytes matured under standard in vitro culture conditions (38.5 °C). Also, the antioxidant enzymatic activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase were significantly ( P < 0.05) increased in all the treatment groups compared to the control group. Therefore, the present study clearly establishes that heat stress ensues oxidative stress in bubaline oocytes which triggers the induction of antioxidant enzymatic defense system for scavenging the ROS.

  14. Heat stress and antioxidant enzyme activity in bubaline (Bubalus bubalis) oocytes during in vitro maturation

    NASA Astrophysics Data System (ADS)

    Waiz, Syma Ashraf; Raies-ul-Haq, Mohammad; Dhanda, Suman; Kumar, Anil; Goud, T. Sridhar; Chauhan, M. S.; Upadhyay, R. C.

    2016-01-01

    In vitro environments like heat stress usually increase the production of reactive oxygen species in bubaline oocytes which have been implicated as one of the major causes for reduced developmental competence. Oocytes during meiotic maturation are sensitive to oxidative stress, and heat stress accelerates cellular metabolism, resulting in the higher production of free radicals. Therefore, the aim of present work was to assess the impact of heat stress during meiotic maturation on bubaline cumulus-oocyte complexes (COC), denuded oocytes (DO), and cumulus cell mass in terms of their oxidative status. Accordingly, for control group, COC were matured at 38.5 °C for complete 24 h of meiotic maturation and heat stress of 40.5 and 41.5 °C was applied to COC during the first 12 h of maturation and then moved to 38.5 °C for rest of the 12 h. In another group, COC after maturation were denuded from the surrounding cumulus cells by manual pipetting. Results indicated that the production of reactive oxygen species (ROS), lipid peroxides, and nitric oxide (NO) was significantly (P < 0.05) higher in the oocytes subjected to heat stress (40.5 and 41.5 °C) during meiotic maturation compared to the oocytes matured under standard in vitro culture conditions (38.5 °C). Also, the antioxidant enzymatic activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase were significantly (P < 0.05) increased in all the treatment groups compared to the control group. Therefore, the present study clearly establishes that heat stress ensues oxidative stress in bubaline oocytes which triggers the induction of antioxidant enzymatic defense system for scavenging the ROS.

  15. Safety knowledge of users and non-users of the lap belt on two-point motorized belt systems.

    PubMed

    Lehto, M R; James, D S

    1997-11-01

    A field study of 1146 drivers and passengers of vehicles equipped with motorized passive belts was conducted in shopping malls and other locations in the states of Arizona and Indiana. The Indiana data was collected the summer of 1994 and the Arizona data the summer of 1995. Shoulder belt use by drivers and passengers was 93.4% in Indiana and 87.8% in Arizona. Lap belt use was 65% in Indiana and 69.9% in Arizona. Over 99% of drivers in both states knew that a manually fastened lap belt was provided along with the motorized shoulder belt. Most drivers agreed that they are supposed to wear the lap belt (96.3% in Indiana and 94.3% in Arizona) and said that the vehicle they were driving provided a warning signal when the lap belt was not fastened (75.7% in Indiana and 79.4% in Arizona). Most drivers were also aware of warning labels telling them to use their lap belt (63.9% in Indiana and 68.2% in Arizona).

  16. Analysis of bonded joints. [shear stress and stress-strain diagrams

    NASA Technical Reports Server (NTRS)

    Srinivas, S.

    1975-01-01

    A refined elastic analysis of bonded joints which accounts for transverse shear deformation and transverse normal stress was developed to obtain the stresses and displacements in the adherends and in the bond. The displacements were expanded in terms of polynomials in the thicknesswise coordinate; the coefficients of these polynomials were functions of the axial coordinate. The stress distribution was obtained in terms of these coefficients by using strain-displacement and stress-strain relations. The governing differential equations were obtained by integrating the equations of equilibrium, and were solved. The boundary conditions (interface or support) were satisfied to complete the analysis. Single-lap, flush, and double-lap joints were analyzed, along with the effects of adhesive properties, plate thicknesses, material properties, and plate taper on maximum peel and shear stresses in the bond. The results obtained by using the thin-beam analysis available in the literature were compared with the results obtained by using the refined analysis. In general, thin-beam analysis yielded reasonably accurate results, but in certain cases the errors were high. Numerical investigations showed that the maximum peel and shear stresses in the bond can be reduced by (1) using a combination of flexible and stiff bonds, (2) using stiffer lap plates, and (3) tapering the plates.

  17. TRMM and GPM: Radar Observations and Simulations with the Local Analysis and Prediction System (LAPS)

    NASA Astrophysics Data System (ADS)

    Albers, S. C.; Holub, K.; Xie, Y.

    2015-12-01

    The Local Analysis and Prediction System (LAPS), developed at NOAAs Earth System Research Laboratory is used for data assimilation, nowcasting, and model initialization/post-processing.It is a portable system and typically runs with a high resolution and rapid updateBlends a wide variety of in-situ and remotely sensed data sets (e.g. METARs, mesonets, radar, satellite)‏Here we test the assimilation of PMM radar data, using reflectivity obtained from the TRMM satellite, as a preparation for GPM. A case study for July 26 2013 with a small region of convection occurring over Florida. The 3-D LAPS domain is on a 1km grid and is producing analyses and forecasts.TRMM radar data was remapped to mimic the appearance of reflectivity in a ground-based radar over Florida.Three assimilation experiments are being performed using non-radar observations plus: TRMM radar, ground-based radar, and neither source of radar. We are comparing both analyses (initial condition) and forecasts where the WRF modelis initialized with the LAPS analysis. When evaluating the results we consider some big picture aspects in thatthe GPM Core Observatory radar coverage is limited in space and time and potentially less operational model benefit.To address this 4DVAR can help increase impact (particularly in a global model), since it spreads observations in time and space.The spreading in time also helps compensate for latency of the real-time data stream.We can also use GPM (core satellite) radar paired with microwave imager data to calibrate microwave data from other GPM constellation satellites. We thus can leverage more frequent satellite microwave passes compared with radar to assess hydrometeor climatological covariance between various species, fill in ice phase information.These relationships, leveraged from related climate research, help to provide constraints for our planned variational analysis improvements.

  18. A comparative study of the hydroxy acids from the Murchison, GRA 95229 and LAP 02342 meteorites

    NASA Astrophysics Data System (ADS)

    Pizzarello, Sandra; Wang, Yi; Chaban, Galina M.

    2010-11-01

    The hydroxy acid suites extracted from the Murchison (MN), GRA 95229 (GRA) and LAP 02342 (LAP) meteorites have been investigated for their molecular, chiral and isotopic composition. Substantial amounts of the compounds have been detected in all three meteorites, with a total abundance that is lower than that of the amino acids in the same stones. Overall, their molecular distributions mirror closely that of the corresponding amino acids and most evidently so for the LAP meteorite. A surprising L-lactic acid enantiomeric excess was found present in all three stones, which cannot be easily accounted by terrestrial contamination; all other compounds of the three hydroxy acid suites were found racemic. The branched-chain five carbon and the diastereomer six-carbon hydroxy acids were also studied vis-a-vis the corresponding amino acids and calculated ab initio thermodynamic data, with the comparison allowing the suggestion that meteoritic hydroxyacid at these chain lengths formed under thermodynamic control and, possibly, at a later stage than the corresponding amino acids. 13C and D isotopic enrichments were detected for many of the meteoritic hydroxy acids and found to vary between molecular species with trends that also appear to correlate to those of amino acids; the highest δD value (+3450‰) was displayed by GRA 2-OH-2-methylbutyric acid. The data suggest that, while the amino- and hydroxy acids likely relate to common presolar precursor, their final distribution in meteorites was determined to large extent by the overall composition of the environments that saw their formation, with ammonia being the determining factor in their final abundance ratios.

  19. Endoplasmic Reticulum Stress-Sensing Mechanism Is Activated in Entamoeba histolytica upon Treatment with Nitric Oxide

    PubMed Central

    Santi-Rocca, Julien; Smith, Sherri; Weber, Christian; Pineda, Erika; Hon, Chung-Chau; Saavedra, Emma; Olivos-García, Alfonso; Rousseau, Sandrine; Dillies, Marie-Agnès; Coppée, Jean-Yves; Guillén, Nancy

    2012-01-01

    The Endoplasmic Reticulum stores calcium and is a site of protein synthesis and modification. Changes in ER homeostasis lead to stress responses with an activation of the unfolded protein response (UPR). The Entamoeba histolytica endomembrane system is simple compared to those of higher eukaryotes, as a canonical ER is not observed. During amoebiasis, an infection of the human intestine and liver by E. histolytica, nitric oxide (NO) triggers an apoptotic-like event preceded by an impairment of energy production and a loss of important parasite pathogenic features. We address the question of how this ancient eukaryote responds to stress induced by immune components (i.e. NO) and whether stress leads to ER changes and subsequently to an UPR. Gene expression analysis suggested that NO triggers stress responses marked by (i) dramatic up-regulation of hsp genes although a bona fide UPR is absent; (ii) induction of DNA repair and redox gene expression and iii) up-regulation of glycolysis-related gene expression. Enzymology approaches demonstrate that NO directly inhibits glycolysis and enhance cysteine synthase activity. Using live imaging and confocal microscopy we found that NO dramatically provokes extensive ER fragmentation. ER fission in E. histolytica appears as a protective response against stress, as it has been recently proposed for neuron self-defense during neurologic disorders. Chronic ER stress is also involved in metabolic diseases including diabetes, where NO production reduces ER calcium levels and activates cell death. Our data highlighted unique cellular responses of interest to understand the mechanisms of parasite death during amoebiasis. PMID:22384074

  20. Yeast Breads. Learning Activity Pack and Instructor's Guide 5.15a. Commercial Foods and Culinary Arts Competency-Based Series. Section 5: Basic Food Preparation.

    ERIC Educational Resources Information Center

    Florida State Univ., Tallahassee. Center for Studies in Vocational Education.

    This document consists of a learning activity packet (LAP) for the student and an instructor's guide for the teacher. The LAP is intended to acquaint occupational home economics students with yeast breads and their ingredients. Illustrated information sheets and learning activities are provided in these areas: yeast breads and their ingredients,…

  1. Beverages. Learning Activity Pack and Instructor's Guide 5.3. Commercial Foods and Culinary Arts Competency-Based Series. Section 5: Basic Food Preparation.

    ERIC Educational Resources Information Center

    Florida State Univ., Tallahassee. Center for Studies in Vocational Education.

    This document consists of a learning activity packet (LAP) for the student and an instructor's guide for the teacher. The LAP is intended to acquaint occupational home economics students with preparing and serving beverages and caring for the equipment used to make them. Illustrated information sheets and learning activities are provided in these…

  2. KCP Activities Supporting the W76LEP Stress Cushions and LK3626 RTV Replacement Material Development

    SciTech Connect

    J. W. Schneider

    2009-10-01

    The S-5370 RTV blown foam previously produced by Dow Corning is no longer commercially available. The S-5370 material has been used on all of Los Alamos National Laboratory (LANL) programs to manufacture Stress Cushions up through the W88. The Kansas City Plant (KCP) did not have a sufficient supply of S-5370 material to cover the schedule requirements for the Program. This report provides information on the numerous activities conducted at KCP involving the development of the Program Stress Cushion and replacement RTV material.

  3. Nicotine-induced locomotor activity is increased by preexposure of rats to prenatal stress.

    PubMed

    Koehl, M; Bjijou, Y; Le Moal, M; Cador, M

    2000-11-01

    Genetic factors are believed to play a predominant role in the individual differences observed in behavioral and pharmacological responses to drugs of abuse. An increasing literature indicates, however, that epigenetic factors can be involved as well. In this report we examined whether developmental changes induced by prenatal stress could alter the way animals respond to the psychostimulant effect of nicotine when adults. The results show that nicotine induces a dose-dependent increase of locomotor activity in both groups, and that prenatally-stressed animals exhibit a higher behavioral response at all doses. This study emphasizes the importance of early environment in the later development of drug-related behavior. PMID:11056199

  4. Stress-induced activation of brown adipose tissue prevents obesity in conditions of low adaptive thermogenesis

    PubMed Central

    Razzoli, Maria; Frontini, Andrea; Gurney, Allison; Mondini, Eleonora; Cubuk, Cankut; Katz, Liora S.; Cero, Cheryl; Bolan, Patrick J.; Dopazo, Joaquin; Vidal-Puig, Antonio; Cinti, Saverio; Bartolomucci, Alessandro

    2015-01-01

    Background Stress-associated conditions such as psychoemotional reactivity and depression have been paradoxically linked to either weight gain or weight loss. This bi-directional effect of stress is not understood at the functional level. Here we tested the hypothesis that pre-stress level of adaptive thermogenesis and brown adipose tissue (BAT) functions explain the vulnerability or resilience to stress-induced obesity. Methods We used wt and triple β1,β2,β3−Adrenergic Receptors knockout (β-less) mice exposed to a model of chronic subordination stress (CSS) at either room temperature (22 °C) or murine thermoneutrality (30 °C). A combined behavioral, physiological, molecular, and immunohistochemical analysis was conducted to determine stress-induced modulation of energy balance and BAT structure and function. Immortalized brown adipocytes were used for in vitro assays. Results Departing from our initial observation that βARs are dispensable for cold-induced BAT browning, we demonstrated that under physiological conditions promoting low adaptive thermogenesis and BAT activity (e.g. thermoneutrality or genetic deletion of the βARs), exposure to CSS acted as a stimulus for BAT activation and thermogenesis, resulting in resistance to diet-induced obesity despite the presence of hyperphagia. Conversely, in wt mice acclimatized to room temperature, and therefore characterized by sustained BAT function, exposure to CSS increased vulnerability to obesity. Exposure to CSS enhanced the sympathetic innervation of BAT in wt acclimatized to thermoneutrality and in β-less mice. Despite increased sympathetic innervation suggesting adrenergic-mediated browning, norepinephrine did not promote browning in βARs knockout brown adipocytes, which led us to identify an alternative sympathetic/brown adipocytes purinergic pathway in the BAT. This pathway is downregulated under conditions of low adaptive thermogenesis requirements, is induced by stress, and elicits activation

  5. On the determination of diffusion lengths by means of angle-lapped p-n junctions

    NASA Technical Reports Server (NTRS)

    Von Roos, O.

    1979-01-01

    A standard procedure for determining the minority carrier diffusion length by means of SEM consists of scanning an angle-lapped surface of a p-n junction and measuring the resulting short circuit current as a function of beam position. The present paper points out that the usual expression linking the short circuit current induced by the electron beam to the angle between the semiconductor surface and the junction plane is incorrect. The correct expression is discussed and it is noted that, for angles less than 10 deg, the new and the old expression are practically indistinguishable.

  6. Lap belt complex. Recognition & assessment of seatbelt injuries in pediatric trauma patients.

    PubMed

    Jordan, B

    2001-05-01

    That seatbelts save lives is irrefutable. Every health-care professional should advocate parents use proper restraint systems for their children. Resource guides are available from local, state and national organizations regarding proper restraint usage for the pediatric population. However, children restrained with lap belts are at risk of sustaining an occult injury. You must quickly stabilize the ABCs, immobilize the spine and get the patient en route to a trauma center while you perform a solid baseline assessment. The trauma team needs information on kinetics, type of restraints used, assessment findings and treatment rendered so they can accurately assess subtle changes in the patient's condition and initiate proper treatment.

  7. Traumatic disruption of the abdominal wall: lap-belt injuries in children.

    PubMed

    Moremen, Jacob R; Nakayama, Don K; Ashley, Dennis W; Astin, Matthew; Nolan, Tracy L

    2013-04-01

    Traumatic abdominal wall hernia (TAWH) from high speed mechanism is a unique finding in adult trauma, and exceedingly rare in pediatrics. The majority of reports are of low-speed "handlebar" hernias associated with direct injury by bicycle handlebars. We report a series of three pediatric patients in motor vehicle collisions (MVC) who experienced TAWH by lap-belt and associated intra-abdominal injuries necessitating immediate operative intervention. Different operative approaches were used in each case to manage the varying types of disruptions. This adds to the pediatric literature the largest series of its kind.

  8. Brassinolide alleviates salt stress and increases antioxidant activity of cowpea plants (Vigna sinensis).

    PubMed

    El-Mashad, Ali Abdel Aziz; Mohamed, Heba Ibrahim

    2012-07-01

    Soil salinity is one of the most severe factors limiting growth and physiological response in Vigna sinensis plants. Plant salt stress tolerance requires the activation of complex metabolic activities including antioxidative pathways, especially reactive oxygen species and scavenging systems within the cells which can contribute to continued growth under water stress. The present investigation was carried out to study the role of brassinolide in enhancing tolerance of cowpea plants to salt stress (NaCl). Treatment with 0.05 ppm brassinolide as foliar spray mitigated salt stress by inducing enzyme activities responsible for antioxidation, e.g., superoxide dismutase, peroxidase, polyphenol oxidase, and detoxification as well as by elevating contents of ascorbic acid, tocopherol, and glutathione. On the other hand, total soluble proteins decreased with increasing NaCl concentrations in comparison with control plants. However, lipid peroxidation increased with increasing concentrations of NaCl. In addition to, the high concentrations of NaCl (100 and 150 mM) decreased total phenol of cowpea plants as being compared with control plants. SDS-PAGE of protein revealed that NaCl treatments alone or in combination with 0.05 ppm brassinolide were associated with the disappearance of some bands or appearance of unique ones in cowpea plants. Electrophoretic studies of α-esterase, β-esterase, polyphenol oxidase, peroxidase, acid phosphatase, and superoxide dismutase isoenzymes showed wide variations in their intensities and densities among all treatments.

  9. Analysis of antioxidant enzyme activity during germination of alfalfa under salt and drought stresses.

    PubMed

    Wang, Wen-Bin; Kim, Yun-Hee; Lee, Haeng-Soon; Kim, Ki-Yong; Deng, Xi-Ping; Kwak, Sang-Soo

    2009-07-01

    To understand the adaptability of alfalfa (Medicago sativa L.) to environmental stresses, we analyzed the activity of several antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), and catalase (CAT), in alfalfa shoots and roots subjected to salt and drought stresses during germination. The germination rate of six alfalfa cultivars was comparatively studied under 200 mM NaCl or 35% PEG treatment. Alfalfa Xinmu No. 1 and Northstar varieties were selected as stress-tolerant and -sensitive cultivars, respectively, and were used for further characterization. After NaCl or PEG treatment, Xinmu No. 1 showed enhanced seedling growth, compared with Northstar. Xinmu No. 1 also exhibited low levels of hydrogen peroxide (H(2)O(2)) production and lipid peroxidation, compared with Northstar. In addition, Xinmu No. 1 showed higher enzymatic activity of SOD, APX, CAT, and POD in its shoots and roots than Northstar. These results seem to indicate that Xinmu No. 1 cultivar's tolerance to salt or drought stresses during germination is associated with enhanced activity of antioxidant enzymes. This study highlights the importance of antioxidant enzymes in the establishment of alfalfa seedlings under drought and salinity conditions typical of desertification.

  10. Effects of social stress on tumor development in dominant male mice with diverse behavioral activity profiles.

    PubMed

    Cacho Fernández, Raúl; Garmendia Rezola, Larraitz; Vegas Moreno, Oscar; Azpíroz Sánchez, Arantxa

    2008-11-01

    We examined the influence of individual psychological profile and social behavior on tumor development in dominant male mice. Male OF1 mice were subjected to an open field test (OFT) to observe their motor activity and latency. Subsequently, the animals were divided into three groups: Stress-Non-Inoculated (SNI), Stress-Inoculated (SI) and Control-Inoculated (CI). The SI and CI groups were inoculated with tumor cells and the SNI group with vehicle. SNI and SI were exposed to social stress with an anosmic intruder six (T1) and twenty one (T2) days after inoculation and their behavior was analyzed. After T2, subjects were put down and the pulmonary metastatic foci counted. SI developed greater pulmonary metastasis than CI, indicating an effect of stress despite the animal's dominant status. Active animals developed less pulmonary metastasis than their passive counterparts. No differences were found in social behavior at T1. Differences were found, however, in some behavioral categories at T2 between SI and SNI, and between active and passive animals. These differences indicate an effect of tumor development on social behavior that is more evident in passive subjects.

  11. Effect of stress and peripheral immune activation on astrocyte activation in transgenic bioluminescent Gfap-luc mice.

    PubMed

    Biesmans, Steven; Acton, Paul D; Cotto, Carlos; Langlois, Xavier; Ver Donck, Luc; Bouwknecht, Jan A; Aelvoet, Sarah-Ann; Hellings, Niels; Meert, Theo F; Nuydens, Rony

    2015-07-01

    Neuroinflammation and the accompanying activation of glial cells is an important feature of many neurodegenerative conditions. It is known that factors such as peripheral infections and stress can influence immune processes in the brain. However, the effect of these stressors on astrocyte activation in vivo remains elusive. In this study, transgenic Gfap-luc mice expressing the luciferase gene under the transcriptional control of the glial fibrillary acidic protein promoter were used to quantify the kinetics of in vivo astrocyte activation following immune challenges relevant to clinical inflammation. It was found that astrocytes respond rapidly to peripheral immune activation elicited by either bacterial lipopolysaccharide (LPS) or the viral mimetic polyinosinic:polycytidylic acid (poly(I:C)). By measuring bioluminescence and 18-kDa translocator protein radioligand binding in the same animal it was observed that LPS induces both astrocyte as well as microglial activation at 6 h post-administration. Furthermore, the astrocyte response decreased upon repeated systemic LPS injections, indicating development of tolerance to the LPS challenge. Finally, restraining Gfap-luc mice for 1 h daily on 5 consecutive days did not affect brain bioluminescence, thereby indicating that sub-chronic stress does not influence astrocyte activation under unchallenged conditions. However, stressed animals showed a reduced response to a subsequent systemic LPS injection, suggesting that the immune system is compromised in these animals. Here, we demonstrate that Gfap-luc mice can be used to study astrocyte activation in response to stimuli relevant for clinical inflammation and that this approach may provide a more complete characterization of existing and novel models of neuroinflammation

  12. Evolution of the ONSEN retrotransposon family activated upon heat stress in Brassicaceae.

    PubMed

    Ito, Hidetaka; Yoshida, Takanori; Tsukahara, Sayuri; Kawabe, Akira

    2013-04-15

    A Ty1/Copia-like retrotransposon, ONSEN, is activated by heat stress in Arabidopsis thaliana, and its de novo integrations that were observed preferentially within genes implies its regulation of neighboring genes. Here we show that ONSEN related copies were found in most species of Brassicaceae, forming a cluster with each species in phylogenetic tree. Most copies were localized close to genes in Arabidopsis lyrata and Brassica rapa, suggesting conserved integration specificity of ONSEN family into genic or open chromatin. In addition, we found heat-induced transcriptional activation of ONSEN family in several species of Brassicaceae. These results suggest that ONSEN has conserved transcriptional activation promoted by environmental heat stress in some Brassicaceae species.

  13. Posterior Midline Activation during Symptom Provocation in Acute Stress Disorder: An fMRI Study.

    PubMed

    Cwik, Jan C; Sartory, Gudrun; Schürholt, Benjamin; Knuppertz, Helge; Seitz, Rüdiger J

    2014-01-01

    Functional imaging studies of patients with post-traumatic stress disorder showed wide-spread activation of midline cortical areas during symptom provocation, i.e., exposure to trauma-related cues. The present study aimed at investigating neural activation during exposure to trauma-related pictures in patients with acute stress disorder (ASD) shortly after the traumatic event. Nineteen ASD patients and 19 healthy control participants were presented with individualized pictures of the traumatic event and emotionally neutral control pictures during the acquisition of whole-brain data with a 3-T fMRI scanner. Compared to the control group and to control pictures, ASD patients showed significant activation in midline cortical areas in response to trauma-related pictures including precuneus, cuneus, postcentral gyrus, and pre-supplementary motor area. The results suggest that the trauma-related pictures evoke emotionally salient self-referential processing in ASD patients.

  14. Posterior Midline Activation during Symptom Provocation in Acute Stress Disorder: An fMRI Study

    PubMed Central

    Cwik, Jan C.; Sartory, Gudrun; Schürholt, Benjamin; Knuppertz, Helge; Seitz, Rüdiger J.

    2014-01-01

    Functional imaging studies of patients with post-traumatic stress disorder showed wide-spread activation of midline cortical areas during symptom provocation, i.e., exposure to trauma-related cues. The present study aimed at investigating neural activation during exposure to trauma-related pictures in patients with acute stress disorder (ASD) shortly after the traumatic event. Nineteen ASD patients and 19 healthy control participants were presented with individualized pictures of the traumatic event and emotionally neutral control pictures during the acquisition of whole-brain data with a 3-T fMRI scanner. Compared to the control group and to control pictures, ASD patients showed significant activation in midline cortical areas in response to trauma-related pictures including precuneus, cuneus, postcentral gyrus, and pre-supplementary motor area. The results suggest that the trauma-related pictures evoke emotionally salient self-referential processing in ASD patients. PMID:24847285

  15. Objective evaluation of stress with the blind by the monitoring of autonomic nervous system activity.

    PubMed

    Massot, Bertrand; Baltenneck, Nicolas; Gehin, Claudine; Dittmar, Andre; McAdams, Eric

    2010-01-01

    Accessibility for the blind in an urban space must be studied under real conditions in their daily environment. A new approach for evaluating the impact of environmental conditions on blind pedestrians is the objective measure of stress by the monitoring of the autonomic nervous system (ANS) activity. Original techniques of data analysis and spatial representation are proposed for the detection of the ANS activity through the assessment of the electrodermal activity. Skin resistance was recorded with an EmoSense system on 10 blind subjects who followed a charted course independently. The course was 1065 meters long and consisted of various environmental conditions in an urban space. The spatial frequency of the non-specific skin resistance responses was used to provide a more relevant representation of geographic hotspots. Results of statistical analysis based on this new parameter are discussed to conclude on phenomena causing mental stress with the blind moving in an urban space.

  16. Heat stress activates AKT via focal adhesion kinase-mediated pathway in neonatal rat ventricular myocytes.

    PubMed

    Wei, Hongguang; Vander Heide, Richard S

    2008-08-01

    Heat stress (HS)-induced cardioprotection is associated with increased paxillin localization to the membrane fraction of neonatal rat ventricular myocytes (NRVM). The purpose of this study was 1) to examine the subcellular signaling pathways activated by HS; 2) to determine whether myocardial stress organizes and activates an integrated survival pathway; and 3) to investigate potential downstream cytoprotective proteins activated by HS. After HS, NRVM were subjected to chemical inhibitors (CI) designed to simulate ischemia by inhibiting both glycolysis and mitochondrial respiration. Protein kinase B (AKT) expression (wild type) was increased selectively with an adenoviral vector. Cell signaling was analyzed with Western blot analysis, while oncosis/apoptosis was assayed by measuring Trypan blue exclusion and/or terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) staining, respectively. HS increased phosphorylation of focal adhesion kinase (FAK) at tyrosine 397 but did not adversely affect the viability of NRVM before CI. HS increased association between FAK and phosphatidylinositol 3-kinase as well as causing a significant increase in AKT activity. Increased expression of wild-type AKT protected myocytes from both oncotic and apoptotic cell death. Increased expression of a FAK inhibitor, FRNK, reduced AKT phosphorylation in response to HS both at time 0 and after 10 min of CI compared with myocytes expressing empty virus. We conclude that myocardial stress activates cytoskeleton-based signaling pathways that are associated with protection from lethal cell injury.

  17. A Semi-Analytical Method for Determining the Energy Release Rate of Cracks in Adhesively-Bonded Single-Lap Composite Joints

    NASA Technical Reports Server (NTRS)

    Yang, Charles; Sun, Wenjun; Tomblin, John S.; Smeltzer, Stanley S., III

    2007-01-01

    A semi-analytical method for determining the strain energy release rate due to a prescribed interface crack in an adhesively-bonded, single-lap composite joint subjected to axial tension is presented. The field equations in terms of displacements within the joint are formulated by using first-order shear deformable, laminated plate theory together with kinematic relations and force equilibrium conditions. The stress distributions for the adherends and adhesive are determined after the appropriate boundary and loading conditions are applied and the equations for the field displacements are solved. Based on the adhesive stress distributions, the forces at the crack tip are obtained and the strain energy release rate of the crack is determined by using the virtual crack closure technique (VCCT). Additionally, the test specimen geometry from both the ASTM D3165 and D1002 test standards are utilized during the derivation of the field equations in order to correlate analytical models with future test results. The system of second-order differential field equations is solved to provide the adherend and adhesive stress response using the symbolic computation tool, Maple 9. Finite element analyses using J-integral as well as VCCT were performed to verify the developed analytical model. The finite element analyses were conducted using the commercial finite element analysis software ABAQUS. The results determined using the analytical method correlated well with the results from the finite element analyses.

  18. Stress-strain sensor for monitoring seismic precursors and fault activities in the sand

    NASA Astrophysics Data System (ADS)

    Du, Qiujiao; Sun, Wei; Zeng, Zuoxun

    2016-04-01

    In this paper, a sensor to monitor stress-strain signals in a granular medium is used to detect seismic precursory information. Compared with the widely used sensors of borehole stress in the rock, the sensor has more convenient operation, higher output sensitivity, compactness and farther propagation effect. The stress and strain changes before Pu'er Ms6.4 earthquake in China are recorded by Beijing and Xinmin stations, and its corresponding fault activities are analyzed. Study indicates anomalous amplitude of strain signal reaches 10 times higher than that of ordinary background, and compressive oscillation and extensional oscillation occurred constantly before the earthquake. The method and results presented in the paper provide a new way for investigating seismic precursors for shallow-source earthquakes.

  19. Active Ground Optical Remote Sensing for Improved Monitoring of Seedling Stress in Nurseries

    PubMed Central

    Eitel, Jan U. H.; Keefe, Robert F.; Long, Dan S.; Davis, Anthony S.; Vierling, Lee A.

    2010-01-01

    Active ground optical remote sensing (AGORS) devices mounted on overhead irrigation booms could help to improve seedling quality by autonomously monitoring seedling stress. In contrast to traditionally used passive optical sensors, AGORS devices operate independently of ambient light conditions and do not require spectral reference readings. Besides measuring red (590–670 nm) and near-infrared (>760 nm) reflectance AGORS devices have recently become available that also measure red-edge (730 nm) reflectance. We tested the hypothesis that the additional availability of red-edge reflectance information would improve AGORS of plant stress induced chlorophyll breakdown in Scots pine (Pinus sylvestris). Our results showed that the availability of red-edge reflectance information improved AGORS estimates of stress induced variation in chlorophyll concentration (r2 > 0.73, RMSE < 1.69) when compared to those without (r2 = 0.57, RMSE = 2.11). PMID:22319275

  20. Prodigiosin activates endoplasmic reticulum stress cell death pathway in human breast carcinoma cell lines

    SciTech Connect

    Pan, Mu-Yun; Shen, Yuh-Chiang; Lu, Chien-Hsing; Yang, Shu-Yi; Ho, Tsing-Fen; Peng, Yu-Ta; Chang, Chia-Che

    2012-12-15

    Prodigiosin is a bacterial tripyrrole pigment with potent cytotoxicity against diverse human cancer cell lines. Endoplasmic reticulum (ER) stress is initiated by accumulation of unfolded or misfolded proteins in the ER lumen and may induce cell death when irremediable. In this study, the role of ER stress in prodigiosin-induced cytotoxicity was elucidated for the first time. Comparable to the ER stress inducer thapsigargin, prodigiosin up-regulated signature ER stress markers GRP78 and CHOP in addition to activating the IRE1, PERK and ATF6 branches of the unfolded protein response (UPR) in multiple human breast carcinoma cell lines, confirming prodigiosin as an ER stress inducer. Prodigiosin transcriptionally up-regulated CHOP, as evidenced by its promoting effect on the CHOP promoter activity. Of note, knockdown of CHOP effectively lowered prodigiosin's capacity to evoke PARP cleavage, reduce cell viability and suppress colony formation, highlighting an essential role of CHOP in prodigiosin-induced cytotoxic ER stress response. In addition, prodigiosin down-regulated BCL2 in a CHOP-dependent manner. Importantly, restoration of BCL2 expression blocked prodigiosin-induced PARP cleavage and greatly enhanced the survival of prodigiosin-treated cells, suggesting that CHOP-dependent BCL2 suppression mediates prodigiosin-elicited cell death. Moreover, pharmacological inhibition of JNK by SP600125 or dominant-negative blockade of PERK-mediated eIF2α phosphorylation impaired prodigiosin-induced CHOP up-regulation and PARP cleavage. Collectively, these results identified ER stress-mediated cell death as a mode-of-action of prodigiosin's tumoricidal effect. Mechanistically, prodigiosin engages the IRE1–JNK and PERK–eIF2α branches of the UPR signaling to up-regulate CHOP, which in turn mediates BCL2 suppression to induce cell death. Highlights: ► Prodigiosin is a bacterial tripyrrole pigment with potent anticancer effect. ► Prodigiosin is herein identified as an

  1. Endovascular management of lap belt-related abdominal aortic injury in a 9-year-old child.

    PubMed

    Papazoglou, Konstantinos O; Karkos, Christos D; Kalogirou, Thomas E; Giagtzidis, Ioakeim T

    2015-02-01

    Blunt abdominal aortic trauma is a rare occurrence in children with only a few patients having been reported in the literature. Most such cases have been described in the context of lap belt injuries. We report a 9-year-old boy who suffered lap belt trauma to the abdomen during a high-speed road traffic accident resulting to the well-recognized pattern of blunt abdominal injury, that is, the triad of intestinal perforation, fractures of the lumbar spine, and abdominal aortic injury. The latter presented with lower limb ischemia due to dissection of the infrarenal aorta and right common iliac artery. Revascularization was achieved by endovascular means using 2 self-expanding stents in the infrarenal aorta and the right common iliac artery. This case is one of the few reports of lap belt-related acute traumatic abdominal aortic dissection in a young child and highlights the feasibility of endovascular management in the pediatric population. PMID:25463338

  2. Acute cervical spinal cord injury secondary to air bag deployment without proper use of lap or shoulder harnesses.

    PubMed

    Hart, R A; Mayberry, J C; Herzberg, A M

    2000-02-01

    The authors present a case report of a patient with cervical central spinal cord syndrome caused by a hyperextension injury after a motor vehicle collision in which the air bag deployed in the absence of shoulder or lap belt harnesses. The potential for cervical spine and spinal cord hyperextension injuries in passengers positioned in front of air bags without proper use of shoulder or lap belt harnesses is discussed. Cervical central spinal cord quadriplegia occurred with cervical spondylosis and kyphosis that was managed by early three-level cervical corpectomy in a 58-year-old patient. Early improvement in the patient's neurological status occurred but was incomplete at the time of this report. Cervical hyperextension injuries are possible in passengers positioned in the front seat of cars with air bags when shoulder or lap belt harnesses are not used properly. Previous biomechanical studies have documented the potential for these types of injuries.

  3. Endovascular management of lap belt-related abdominal aortic injury in a 9-year-old child.

    PubMed

    Papazoglou, Konstantinos O; Karkos, Christos D; Kalogirou, Thomas E; Giagtzidis, Ioakeim T

    2015-02-01

    Blunt abdominal aortic trauma is a rare occurrence in children with only a few patients having been reported in the literature. Most such cases have been described in the context of lap belt injuries. We report a 9-year-old boy who suffered lap belt trauma to the abdomen during a high-speed road traffic accident resulting to the well-recognized pattern of blunt abdominal injury, that is, the triad of intestinal perforation, fractures of the lumbar spine, and abdominal aortic injury. The latter presented with lower limb ischemia due to dissection of the infrarenal aorta and right common iliac artery. Revascularization was achieved by endovascular means using 2 self-expanding stents in the infrarenal aorta and the right common iliac artery. This case is one of the few reports of lap belt-related acute traumatic abdominal aortic dissection in a young child and highlights the feasibility of endovascular management in the pediatric population.

  4. Interfacial and Mechanical Behavior of AA5456 Filling Friction-Stir-Welded Lap Joints Using Similar and Dissimilar Pins

    NASA Astrophysics Data System (ADS)

    Behmand, Saleh Alaei; Mirsalehi, Seyyed Ehsan; Omidvar, Hamid; Safarkhanian, Mohammad Ali

    2016-10-01

    In this article, filling friction stir welding (FFSW) of the remaining exit holes of AA5456 alloy friction-stir-welded lap joints was studied. For this purpose, the influences of different rotating speeds, holding times, and pin materials, AA5456 and AA2024, on the metallurgical structure and joint strength were investigated. The observations showed that defect-free lap joints are successfully obtainable by this method using similar and dissimilar consumable pins. The results indicated that the higher rotating speed and holding time adversely affect the weld performance. The best result was achieved for 30 seconds holding time, 500 rpm rotating speed, and AA2024 consumable pin. In this condition, a lap shear strength of 10 pct higher than that of the nonfilled joint, equivalent to about 94 pct of the original defect-free FSW joint, was obtained, whereas the GTAW filled joint showed only approximately 87 pct of the continuous FSW joint strength.

  5. Interfacial and Mechanical Behavior of AA5456 Filling Friction-Stir-Welded Lap Joints Using Similar and Dissimilar Pins

    NASA Astrophysics Data System (ADS)

    Behmand, Saleh Alaei; Mirsalehi, Seyyed Ehsan; Omidvar, Hamid; Safarkhanian, Mohammad Ali

    2016-06-01

    In this article, filling friction stir welding (FFSW) of the remaining exit holes of AA5456 alloy friction-stir-welded lap joints was studied. For this purpose, the influences of different rotating speeds, holding times, and pin materials, AA5456 and AA2024, on the metallurgical structure and joint strength were investigated. The observations showed that defect-free lap joints are successfully obtainable by this method using similar and dissimilar consumable pins. The results indicated that the higher rotating speed and holding time adversely affect the weld performance. The best result was achieved for 30 seconds holding time, 500 rpm rotating speed, and AA2024 consumable pin. In this condition, a lap shear strength of 10 pct higher than that of the nonfilled joint, equivalent to about 94 pct of the original defect-free FSW joint, was obtained, whereas the GTAW filled joint showed only approximately 87 pct of the continuous FSW joint strength.

  6. The Impact of Perceived Stress, Social Support, and Home-Based Physical Activity on Mental Health among Older Adults

    ERIC Educational Resources Information Center

    Kwag, Kyung Hwa; Martin, Peter; Russell, Daniel; Franke, Warren; Kohut, Marian

    2011-01-01

    This study investigated how perceived stress, social support, and home-based physical activity affected older adults' fatigue, loneliness, and depression. We also explored whether social support and physical activity mediated the relationships between stress and mental health problems. The data of 163 older participants were analyzed in this…

  7. Homer1/mGluR5 Activity Moderates Vulnerability to Chronic Social Stress

    PubMed Central

    Wagner, Klaus V; Hartmann, Jakob; Labermaier, Christiana; Häusl, Alexander S; Zhao, Gengjing; Harbich, Daniela; Schmid, Bianca; Wang, Xiao-Dong; Santarelli, Sara; Kohl, Christine; Gassen, Nils C; Matosin, Natalie; Schieven, Marcel; Webhofer, Christian; Turck, Christoph W; Lindemann, Lothar; Jaschke, Georg; Wettstein, Joseph G; Rein, Theo; Müller, Marianne B; Schmidt, Mathias V

    2015-01-01

    Stress-induced psychiatric disorders, such as depression, have recently been linked to changes in glutamate transmission in the central nervous system. Glutamate signaling is mediated by a range of receptors, including metabotropic glutamate receptors (mGluRs). In particular, mGluR subtype 5 (mGluR5) is highly implicated in stress-induced psychopathology. The major scaffold protein Homer1 critically interacts with mGluR5 and has also been linked to several psychopathologies. Yet, the specific role of Homer1 in this context remains poorly understood. We used chronic social defeat stress as an established animal model of depression and investigated changes in transcription of Homer1a and Homer1b/c isoforms and functional coupling of Homer1 to mGluR5. Next, we investigated the consequences of Homer1 deletion, overexpression of Homer1a, and chronic administration of the mGluR5 inverse agonist CTEP (2-chloro-4-((2,5-dimethyl-1-(4-(trifluoromethoxy)phenyl)-1H-imidazol-4-yl)ethynyl)pyridine) on the effects of chronic stress. In mice exposed to chronic stress, Homer1b/c, but not Homer1a, mRNA was upregulated and, accordingly, Homer1/mGluR5 coupling was disrupted. We found a marked hyperactivity behavior as well as a dysregulated hypothalamic–pituitary–adrenal axis activity in chronically stressed Homer1 knockout (KO) mice. Chronic administration of the selective and orally bioavailable mGluR5 inverse agonist, CTEP, was able to recover behavioral alterations induced by chronic stress, whereas overexpression of Homer1a in the hippocampus led to an increased vulnerability to chronic stress, reflected in an increased physiological response to stress as well as enhanced depression-like behavior. Overall, our results implicate the glutamatergic system in the emergence of stress-induced psychiatric disorders, and support the Homer1/mGluR5 complex as a target for the development of novel antidepressant agents. PMID:25409593

  8. Arterial baroreflex control of muscle sympathetic nerve activity under orthostatic stress in humans.

    PubMed

    Ichinose, Masashi; Nishiyasu, Takeshi

    2012-01-01

    The mechanisms by which blood pressure is maintained against the orthostatic stress caused by gravity's effect on the fluid distribution within the body are important issues in physiology, especially in humans who usually adopt an upright posture. Peripheral vasoconstriction and increased heart rate (HR) are major cardiovascular adjustments to orthostatic stress and comprise part of the reflex response elicited via the carotid sinus and aortic baroreceptors (arterial baroreflex: ABR) and cardiopulmonary stretch receptors (cardiopulmonary baroreflex). In a series of studies, we have been characterizing the ABR-mediated regulation of cardiovascular hemodynamics and muscle sympathetic nerve activity (MSNA) while applying orthostatic stress in humans. We have found that under orthostatic stress, dynamic carotid baroreflex responses are modulated as exemplified by the increases in the MSNA, blood pressure, and HR responses elicited by carotid baroreflex unloading and the shorter period of MSNA suppression, comparable reduction and faster recovery of mean arterial blood pressure (MAP) and greater HR response to carotid baroreflex stimulation. Our results also show that ABR-mediated beat-to-beat control over burst incidence, burst strength and total MSNA is progressively modulated as orthostatic stress is increased until induction of syncope, and that the sensitivity of ABR control over the aforementioned MSNA variables is substantially reduced during the development of syncope. We suggest that in humans, the modulation of ABR function under orthostatic stress may be one of the mechanisms by which blood pressure is maintained and orthostatic hypotension limited, and impairment of ABR control over sympathetic vasomotor activity leads to the severe hypotension associated with orthostatic syncope.

  9. Using DNA devices to track anticancer drug activity.

    PubMed

    Kahanda, Dimithree; Chakrabarti, Gaurab; Mcwilliams, Marc A; Boothman, David A; Slinker, Jason D

    2016-06-15

    It is beneficial to develop systems that reproduce complex reactions of biological systems while maintaining control over specific factors involved in such processes. We demonstrated a DNA device for following the repair of DNA damage produced by a redox-cycling anticancer drug, beta-lapachone (β-lap). These chips supported ß-lap-induced biological redox cycle and tracked subsequent DNA damage repair activity with redox-modified DNA monolayers on gold. We observed drug-specific changes in square wave voltammetry from these chips at therapeutic ß-lap concentrations of high statistical significance over drug-free control. We also demonstrated a high correlation of this change with the specific ß-lap-induced redox cycle using rational controls. The concentration dependence of ß-lap revealed significant signal changes at levels of high clinical significance as well as sensitivity to sub-lethal levels of ß-lap. Catalase, an enzyme decomposing peroxide, was found to suppress DNA damage at a NQO1/catalase ratio found in healthy cells, but was clearly overcome at a higher NQO1/catalase ratio consistent with cancer cells. We found that it was necessary to reproduce key features of the cellular environment to observe this activity. Thus, this chip-based platform enabled tracking of ß-lap-induced DNA damage repair when biological criteria were met, providing a unique synthetic platform for uncovering activity normally confined to inside cells. PMID:26901461

  10. Effects of dietary yeast extract on turkey stress response and heterophil oxidative burst activity.

    PubMed

    Huff, G R; Dutta, V; Huff, W E; Rath, N C

    2011-08-01

    1. Effective nutritional approaches to counteract the negative effects of stress may provide food animal producers with useful alternatives to antibiotics. In this study, turkeys were fed on a standard diet, or the same diet supplemented with yeast extract (YE), to determine if YE would improve disease resistance in a stress model. 2. At 16 weeks of age, half of the birds were exposed to a bacterial challenge using a coarse spray of the pen environment. A subset of control and challenged birds was also treated with dexamethasone (Dex) prior to challenge (Dex/challenge). At 18 weeks, another subset was subjected to a 12?h transport stress protocol (Challenge/transport). All birds were bled and necropsied the morning after transport. The numbers and proportions of blood cells and the heterophil oxidative burst activity (OBA) were determined. Serum corticosterone (Cort) levels of male birds were measured using a commercial ELISA kit. Body weight and gain were increased by YE during week 1. 3. YE decreased mortality and bacterial isolation following Dex/challenge only in females. Cort levels in male turkeys were decreased by YE and Dex treatment. OBA was higher in males and in birds given YE and was reduced by challenge and transport. 4. These results suggest there may be gender differences in the turkey stress response and that dietary YE has potential for modulating the impact of stress on innate immunity of turkeys. PMID:21919572

  11. Prevention of atherosclerosis by bioactive palmitoleate through suppression of organelle stress and inflammasome activation.

    PubMed

    Çimen, Ismail; Kocatürk, Begüm; Koyuncu, Seda; Tufanlı, Özlem; Onat, Umut I; Yıldırım, Asli D; Apaydın, Onur; Demirsoy, Şeyma; Aykut, Zaliha G; Nguyen, Uyen T; Watkins, Steven M; Hotamışlıgil, Gökhan S; Erbay, Ebru

    2016-09-28

    De novo lipogenesis (DNL), the conversion of glucose and other substrates to lipids, is often associated with ectopic lipid accumulation, metabolic stress, and insulin resistance, especially in the liver. However, organ-specific DNL can also generate distinct lipids with beneficial metabolic bioactivity, prompting a great interest in their use for the treatment of metabolic diseases. Palmitoleate (PAO), one such bioactive lipid, regulates lipid metabolism in liver and improves glucose utilization in skeletal muscle when it is generated de novo from the obese adipose tissue. We show that PAO treatment evokes an overall lipidomic remodeling of the endoplasmic reticulum (ER) membranes in macrophages and mouse tissues, which is associated with resistance of the ER to hyperlipidemic stress. By preventing ER stress, PAO blocks lipid-induced inflammasome activation in mouse and human macrophages. Chronic PAO supplementation also lowers systemic interleukin-1β (IL-1β) and IL-18 concentrations in vivo in hyperlipidemic mice. Moreover, PAO prevents macrophage ER stress and IL-1β production in atherosclerotic plaques in vivo, resulting in a marked reduction in plaque macrophages and protection against atherosclerosis in mice. These findings demonstrate that oral supplementation with a product of DNL such as PAO can promote membrane remodeling associated with metabolic resilience of intracellular organelles to lipid stress and limit the progression of atherosclerosis. These findings support therapeutic PAO supplementation as a potential preventive approach against complex metabolic and inflammatory diseases such as atherosclerosis, which warrants further studies in humans. PMID:27683551

  12. Pathway connectivity and signaling coordination in the yeast stress-activated signaling network

    PubMed Central

    Chasman, Deborah; Ho, Yi-Hsuan; Berry, David B; Nemec, Corey M; MacGilvray, Matthew E; Hose, James; Merrill, Anna E; Lee, M Violet; Will, Jessica L; Coon, Joshua J; Ansari, Aseem Z; Craven, Mark; Gasch, Audrey P

    2014-01-01

    Stressed cells coordinate a multi-faceted response spanning many levels of physiology. Yet knowledge of the complete stress-activated regulatory network as well as design principles for signal integration remains incomplete. We developed an experimental and computational approach to integrate available protein interaction data with gene fitness contributions, mutant transcriptome profiles, and phospho-proteome changes in cells responding to salt stress, to infer the salt-responsive signaling network in yeast. The inferred subnetwork presented many novel predictions by implicating new regulators, uncovering unrecognized crosstalk between known pathways, and pointing to previously unknown ‘hubs’ of signal integration. We exploited these predictions to show that Cdc14 phosphatase is a central hub in the network and that modification of RNA polymerase II coordinates induction of stress-defense genes with reduction of growth-related transcripts. We find that the orthologous human network is enriched for cancer-causing genes, underscoring the importance of the subnetwork's predictions in understanding stress biology. PMID:25411400

  13. [Impacts of root-zone hypoxia stress on muskmelon growth, its root respiratory metabolism, and antioxidative enzyme activities].

    PubMed

    Liu, Yi-Ling; Li, Tian-Lai; Sun, Zhou-Ping; Chen, Ya-Dong

    2010-06-01

    By using aeroponics culture system, this paper studied the impacts of root-zone hypoxia (10% O2 and 5% O2) stress on the plant growth, root respiratory metabolism, and antioxidative enzyme activities of muskmelon at its fruit development stage. Root-zone hypoxia stress inhibited the plant growth of muskmelon, resulting in the decrease of plant height, root length, and fresh and dry biomass. Comparing with the control (21% O2), hypoxia stress reduced the root respiration rate and malate dehydrogenase (MDH) activity significantly, and the impact of 5% O2 stress was more serious than that of 10% O2 stress. Under hypoxic conditions, the lactate dehydrogenase (LDH), alcohol dehydrogenase (ADH), pyruvate decarboxylase (PDC), superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities and the malondialdehyde (MDA) content were significantly higher than the control. The increment of antioxidative enzyme activities under 10% O2 stress was significantly higher than that under 5% O2 stress, while the MDA content was higher under 5% O2 stress than under 10% O2 stress, suggesting that when the root-zone oxygen concentration was below 10%, the aerobic respiration of muskmelon at its fruit development stage was obviously inhibited while the anaerobic respiration was accelerated, and the root antioxidative enzymes induced defense reaction. With the increasing duration of hypoxic stress, the lipid peroxidation would be aggravated, resulting in the damages on muskmelon roots, inhibition of plant growth, and decrease of fruit yield and quality. PMID:20873618

  14. [Impacts of root-zone hypoxia stress on muskmelon growth, its root respiratory metabolism, and antioxidative enzyme activities].

    PubMed

    Liu, Yi-Ling; Li, Tian-Lai; Sun, Zhou-Ping; Chen, Ya-Dong

    2010-06-01

    By using aeroponics culture system, this paper studied the impacts of root-zone hypoxia (10% O2 and 5% O2) stress on the plant growth, root respiratory metabolism, and antioxidative enzyme activities of muskmelon at its fruit development stage. Root-zone hypoxia stress inhibited the plant growth of muskmelon, resulting in the decrease of plant height, root length, and fresh and dry biomass. Comparing with the control (21% O2), hypoxia stress reduced the root respiration rate and malate dehydrogenase (MDH) activity significantly, and the impact of 5% O2 stress was more serious than that of 10% O2 stress. Under hypoxic conditions, the lactate dehydrogenase (LDH), alcohol dehydrogenase (ADH), pyruvate decarboxylase (PDC), superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities and the malondialdehyde (MDA) content were significantly higher than the control. The increment of antioxidative enzyme activities under 10% O2 stress was significantly higher than that under 5% O2 stress, while the MDA content was higher under 5% O2 stress than under 10% O2 stress, suggesting that when the root-zone oxygen concentration was below 10%, the aerobic respiration of muskmelon at its fruit development stage was obviously inhibited while the anaerobic respiration was accelerated, and the root antioxidative enzymes induced defense reaction. With the increasing duration of hypoxic stress, the lipid peroxidation would be aggravated, resulting in the damages on muskmelon roots, inhibition of plant growth, and decrease of fruit yield and quality.

  15. Activation of Antioxidant Defenses in Whole Saliva by Psychosocial Stress Is More Manifested in Young Women than in Young Men

    PubMed Central

    Tsuber, Viktoriia; Kadamov, Yunus; Tarasenko, Lydia

    2014-01-01

    Psychosocial stress has been long known to have deleterious effects on health. Nevertheless, an exposure to moderate stressors enhances resilience and promotes health benefits. Male and female organisms differ in many aspects of health and disease. The aim of this study was to investigate antioxidant activity and oxidative damage in saliva in a psychosocial stress paradigm in men and women. Here, we show that an acute stressor of moderate strength augments antioxidant activity and decreases oxidative damage in whole saliva of young people. An examination stress caused a significant increase of catalase activity, accompanied by a decrease of levels of oxidized proteins. Levels of thiobarbituric acid-reacting substances did not increase at stress, indicating that lipid peroxidation was not activated. The stress-induced alterations were more manifested in young women compared to young men. Thus, antioxidant protective mechanisms are more activated by a moderate stressor in young women than in young men. PMID:25525800

  16. [Stress-induced changes in functional activity of the neuro-endocrine system: modulatory action of derinat].

    PubMed

    Fomicheva, E E; Filatenkova, T A; Shanin, S N; Rybakina, E G

    2009-03-01

    Changes in functional activity of HPA and HPG axes under stress influences of different intensity, and possible ways for their correction by native DNA preparation: derinat, possessing immune modulator effects, were studied. It was shown that the vector of changes in hormone's reactions of both axes did not depend on the intensity of stress influences: different models of stress increased corticosterone level and decreased testosterone level in rats' blood. Intraperitoneal injection of 10 and 50 mg/kg BW doses of Derinat to rats enhanced HPA and HPG axes activity, reversed stress-induced decrease of testosterone concentration in blood, that may indicate a stress-protective effect of derinat. Injection of derinat caused normalizing of stress-induced changes in immunomodulatory cytokines production within Lymphocyte Activating Factors, which regulate not only the immune system functions but also the functions of HPA and HPG axes.

  17. Maternal stress, nutrition and physical activity: Impact on immune function, CNS development and psychopathology.

    PubMed

    Marques, Andrea Horvath; Bjørke-Monsen, Anne-Lise; Teixeira, Antônio L; Silverman, Marni N

    2015-08-18

    Evidence suggests that maternal and fetal immune dysfunction may impact fetal brain development and could play a role in neurodevelopmental disorders, although the definitive pathophysiological mechanisms are still not completely understood. Stress, malnutrition and physical inactivity are three maternal behavioral lifestyle factors that can influence immune and central nervous system (CNS) functions in both the mother and fetus, and may therefore, increase risk for neurodevelopmental/psychiatric disorders. First, we will briefly review some aspects of maternal-fetal immune system interactions and development of immune tolerance. Second, we will discuss the bidirectional communication between the immune system and CNS and the pathways by which immune dysfunction could contribute to neurodevelopmental disorders. Third, we will discuss the effects of prenatal stress and malnutrition (over and undernutrition) on perinatal programming of the CNS and immune system, and how this might influence neurodevelopment. Finally, we will discuss the beneficial impact of physical fitness during pregnancy on the maternal-fetal unit and infant and how regular physical activity and exercise can be an effective buffer against stress- and inflammatory-related disorders. Although regular physical activity has been shown to promote neuroplasticity and an anti-inflammatory state in the adult, there is a paucity of studies evaluating its impact on CNS and immune function during pregnancy. Implementing stress reduction, proper nutrition and ample physical activity during pregnancy and the childbearing period may be an efficient strategy to counteract the impact of maternal stress and malnutrition/obesity on the developing fetus. Such behavioral interventions could have an impact on early development of the CNS and immune system and contribute to the prevention of neurodevelopmental and psychiatric disorders. Further research is needed to elucidate this relationship and the underlying

  18. Personality types, lifestyle, and sensitivity to mental stress in association with NK activity.

    PubMed

    Imai, K; Nakachi, K

    2001-10-01

    We conducted a cross-sectional study among 302 healthy Japanese male workers to make a mechanistic approach to the association between per