Sample records for abnormal mechanical stresses

  1. The association between acute mental stress and abnormal left atrial electrophysiology.

    PubMed

    O'Neal, Wesley T; Hammadah, Muhammad; Sandesara, Pratik B; Almuwaqqat, Zakaria; Samman-Tahhan, Ayman; Gafeer, Mohamad M; Abdelhadi, Naser; Wilmot, Kobina; Al Mheid, Ibhar; Bremner, Douglas J; Kutner, Michael; Soliman, Elsayed Z; Shah, Amit J; Quyyumi, Arshed A; Vaccarino, Viola

    2017-10-01

    Acute stress may trigger atrial fibrillation (AF), but the underlying mechanisms are unclear. We examined if acute mental stress results in abnormal left atrial electrophysiology as detected by more negative deflection of P-wave terminal force in lead V 1 (PTFV 1 ), a well-known marker of AF risk. We examined this hypothesis in 422 patients (mean age = 56 ± 10 years; 61% men; 44% white) with stable coronary heart disease who underwent mental (speech task) stress testing. PTFV 1 was defined as the duration (milliseconds) times the value of the depth (μV) of the downward deflection (terminal portion) of the P-wave in lead V 1 measured on digital electrocardiograms (ECG). Electrocardiographic left atrial abnormality was defined as PTFV 1 ≤ -4000 μV*ms. Mean PTFV 1 values during stress and recovery were compared with rest. The percentage of participants who developed left atrial abnormality during stress and recovery was compared with the percentage at rest. Compared with rest, PTFV 1 became more negative during mental stress (mean change =  -348, 95% CI = [-515, -182]; P < 0.001) and no change was observed at recovery (mean change = 12, 95%CI = [-148, 172]; P = 0.89). A larger percentage of participants showed left atrial abnormality on ECGs obtained at stress (n = 163, 39%) and recovery (n = 142, 34%) compared with rest (n = 127, 30%). Acute mental stress alters left atrial electrophysiology, suggesting that stressful situations promote adverse transient electrical changes to provide the necessary substrate for AF. © 2017 Wiley Periodicals, Inc.

  2. Abnormal stress echocardiography findings in cardiac amyloidosis.

    PubMed

    Ong, Kevin C; Askew, J Wells; Dispenzieri, Angela; Maleszewski, Joseph J; Klarich, Kyle W; Anavekar, Nandan S; Mulvagh, Sharon L; Grogan, Martha

    2016-06-01

    Cardiac involvement in immunoglobulin light chain (amyloid light chain, AL) amyloidosis is characterized by myocardial interstitial deposition but can also cause obstructive deposits in the coronary microvasculature. We retrospectively identified 20 patients who underwent stress echocardiography within 1 year prior to the histologic diagnosis of AL amyloidosis. Only patients with cardiac amyloidosis and no known obstructive coronary disease were included. Stress echocardiograms (13 exercise; 7 dobutamine) were performed for evaluation of dyspnea and/or chest pain. Stress-induced wall motion abnormalities (WMAs) occurred in 11 patients (55%), 4 of whom had normal left ventricular wall thickness. Coronary angiogram was performed in 9 of 11 patients and demonstrated no or mild epicardial coronary artery disease. Seven (54%) patients had an abnormal exercise blood pressure which occurred with similar likelihood between those with and without stress-induced WMAs. Stress-induced WMAs and abnormal exercise blood pressure may occur in patients with cardiac AL amyloidosis despite the absence of significant epicardial coronary artery disease. This finding should raise the possibility of cardiac amyloidosis even in the absence of significant myocardial thickening.

  3. Abnormal behavior with hump characteristics in current stressed a-InGaZnO thin film transistors

    NASA Astrophysics Data System (ADS)

    Kim, Woo-Sic; Cho, Yong-Jung; Lee, Yeol-Hyeong; Park, JeongKi; Kim, GeonTae; Kim, Ohyun

    2017-11-01

    We investigated the degradation mechanism of a-InGaZnO TFTs under simultaneous gate and drain bias stress. Gate and drain bias of 20 V were applied simultaneously to induce current stress, and abnormal turn-around behavior in transfer characteristics with a hump phenomenon were identified. Hump characteristics were interpreted in terms of parasitic current path, and the degradation itself was found to be caused dominantly by the electrical field and to be accelerated with current by Joule heating. The mechanism of asymmetrical degradation after current stress was also investigated. By decomposing the curves into two curves and measuring the relaxation behavior of the stressed TFTs, we also found that abnormal turn-around behavior in the transfer characteristics was related to acceptor-like states.

  4. Estimation of stress relaxation time for normal and abnormal breast phantoms using optical technique

    NASA Astrophysics Data System (ADS)

    Udayakumar, K.; Sujatha, N.

    2015-03-01

    Many of the early occurring micro-anomalies in breast may transform into a deadliest cancer tumor in future. Probability of curing early occurring abnormalities in breast is more if rightly identified. Even in mammogram, considered as a golden standard technique for breast imaging, it is hard to pick up early occurring changes in the breast tissue due to the difference in mechanical behavior of the normal and abnormal tissue when subjected to compression prior to x-ray or laser exposure. In this paper, an attempt has been made to estimate the stress relaxation time of normal and abnormal breast mimicking phantom using laser speckle image correlation. Phantoms mimicking normal breast is prepared and subjected to precise mechanical compression. The phantom is illuminated by a Helium Neon laser and by using a CCD camera, a sequence of strained phantom speckle images are captured and correlated by the image mean intensity value at specific time intervals. From the relation between mean intensity versus time, tissue stress relaxation time is quantified. Experiments were repeated for phantoms with increased stiffness mimicking abnormal tissue for similar ranges of applied loading. Results shows that phantom with more stiffness representing abnormal tissue shows uniform relaxation for varying load of the selected range, whereas phantom with less stiffness representing normal tissue shows irregular behavior for varying loadings in the given range.

  5. Glutamatergic system abnormalities in posttraumatic stress disorder.

    PubMed

    Nishi, Daisuke; Hashimoto, Kenji; Noguchi, Hiroko; Hamazaki, Kei; Hamazaki, Tomohito; Matsuoka, Yutaka

    2015-12-01

    Accumulating evidence suggests involvement of the glutamatergic system in the biological mechanisms of posttraumatic stress disorder (PTSD), but few studies have demonstrated an association between glutamatergic system abnormalities and PTSD diagnosis or severity. We aimed to examine whether abnormalities in serum glutamate and in the glutamine/glutamate ratio were associated with PTSD diagnosis and severity in severely injured patients at risk for PTSD and major depressive disorder (MDD). This is a nested case-control study in TPOP (Tachikawa project for prevention of posttraumatic stress disorder with polyunsaturated fatty acid) trial. Diagnosis and severity of PTSD were assessed 3 months after the accidents using the Clinician-Administered PTSD Scale. The associations of glutamate levels and the glutamine/glutamate ratio with diagnosis and severity of PTSD and MDD were investigated by univariate and multiple linear regression analyses. Ninety-seven of 110 participants (88 %) completed assessments at 3 months. Serum glutamate levels were significantly higher for participants with full or partial PTSD than for participants without PTSD (p = 0.049) and for participants with MDD than for participants without MDD (p = 0.048). Multiple linear regression analyses showed serum glutamate levels were significantly positively associated with PTSD severity (p = 0.02) and MDD severity (p = 0.03). The glutamine/glutamate ratio was also significantly inversely associated with PTSD severity (p = 0.03), but not with MDD severity (p = 0.07). These findings suggest that the glutamatergic system may play a major role in the pathogenesis of PTSD and the need for new treatments targeting the glutamatergic system to be developed for PTSD.

  6. Psychosocial stress predicts abnormal glucose metabolism: the Australian Diabetes, Obesity and Lifestyle (AusDiab) study.

    PubMed

    Williams, Emily D; Magliano, Dianna J; Tapp, Robyn J; Oldenburg, Brian F; Shaw, Jonathan E

    2013-08-01

    The evidence supporting a relationship between stress and diabetes has been inconsistent. This study examined the effects of stress on abnormal glucose metabolism, using a population-based sample of 3,759, with normoglycemia at baseline, from the Australian Diabetes, Obesity and Lifestyle study. Perceived stress and stressful life events were measured at baseline, with health behavior and anthropometric information also collected. Oral glucose tolerance tests were undertaken at baseline and 5-year follow-up. The primary outcome was the development of abnormal glucose metabolism (impaired fasting glucose, impaired glucose tolerance, and type 2 diabetes), according to WHO 1999 criteria. Perceived stress predicted incident abnormal glucose metabolism in women but not men, after multivariate adjustment. Life events showed an inconsistent relationship with abnormal glucose metabolism. Perceived stress predicted abnormal glucose metabolism in women. Healthcare professionals should consider psychosocial adversity when assessing risk factor profiles for the development of diabetes.

  7. NEW FRONTIER IN UNDERSTANDING THE MECHANISMS OF DEVELOPMENTAL ABNORMALITIES

    EPA Science Inventory

    Recent advancements in molecular developmental biology afford an opportunity to apply newly developed tools for understanding the mechanisms of both normal and abnormal development. lthough a number of agents have been identified as causing developmental abnormalities, knowledge ...

  8. Abnormal stress responsivity in a rodent developmental disruption model of schizophrenia.

    PubMed

    Zimmerman, Eric C; Bellaire, Mark; Ewing, Samuel G; Grace, Anthony A

    2013-10-01

    Although numerous studies have implicated stress in the pathophysiology of schizophrenia, less is known about how the effects of stress interact with genetic, developmental, and/or environmental determinants to promote disease progression. In particular, it has been proposed that in humans, stress exposure in adolescence could combine with a predisposition towards increased stress sensitivity, leading to prodromal symptoms and eventually psychosis. However, the neurobiological substrates for this interaction are not fully characterized. Previous work in our lab has demonstrated that rats born to dams administered with the DNA-methylating agent methylazoxymethanol acetate (MAM) at gestational day 17 exhibit as adults behavioral and anatomical abnormalities consistent with those observed in patients with schizophrenia. Here, we examined behavioral and neuroendocrine responses to stress in the MAM model of schizophrenia. MAM-treated male rats were exposed to acute and repeated footshock stress at prepubertal, peripubteral, and adult ages. Ultrasonic vocalizations (USVs), freezing, and corticosterone responses were quantified. We found that juvenile MAM-treated rats emitted significantly more calls, spent more time vocalizing, emitted calls at a higher rate, and showed more freezing in response to acute footshock stress when compared with their saline (SAL) treated counterparts, and that this difference is not present in older animals. In addition, adolescent MAM-treated animals displayed a blunted HPA axis corticosterone response to acute footshock that did not adapt after 10 days of stress exposure. These data demonstrate abnormal stress responsivity in the MAM model of schizophrenia and suggest that these animals are more sensitive to the effects of stress in youth.

  9. Lysyl Oxidase Induces Vascular Oxidative Stress and Contributes to Arterial Stiffness and Abnormal Elastin Structure in Hypertension: Role of p38MAPK.

    PubMed

    Martínez-Revelles, Sonia; García-Redondo, Ana B; Avendaño, María S; Varona, Saray; Palao, Teresa; Orriols, Mar; Roque, Fernanda R; Fortuño, Ana; Touyz, Rhian M; Martínez-González, Jose; Salaices, Mercedes; Rodríguez, Cristina; Briones, Ana M

    2017-09-01

    Vascular stiffness, structural elastin abnormalities, and increased oxidative stress are hallmarks of hypertension. Lysyl oxidase (LOX) is an elastin crosslinking enzyme that produces H 2 O 2 as a by-product. We addressed the interplay between LOX, oxidative stress, vessel stiffness, and elastin. Angiotensin II (Ang II)-infused hypertensive mice and spontaneously hypertensive rats (SHR) showed increased vascular LOX expression and stiffness and an abnormal elastin structure. Mice over-expressing LOX in vascular smooth muscle cells (TgLOX) exhibited similar mechanical and elastin alterations to those of hypertensive models. LOX inhibition with β-aminopropionitrile (BAPN) attenuated mechanical and elastin alterations in TgLOX mice, Ang II-infused mice, and SHR. Arteries from TgLOX mice, Ang II-infused mice, and/or SHR exhibited increased vascular H 2 O 2 and O 2 .- levels, NADPH oxidase activity, and/or mitochondrial dysfunction. BAPN prevented the higher oxidative stress in hypertensive models. Treatment of TgLOX and Ang II-infused mice and SHR with the mitochondrial-targeted superoxide dismutase mimetic mito-TEMPO, the antioxidant apocynin, or the H 2 O 2 scavenger polyethylene glycol-conjugated catalase (PEG-catalase) reduced oxidative stress, vascular stiffness, and elastin alterations. Vascular p38 mitogen-activated protein kinase (p38MAPK) activation was increased in Ang II-infused and TgLOX mice and this effect was prevented by BAPN, mito-TEMPO, or PEG-catalase. SB203580, the p38MAPK inhibitor, normalized vessel stiffness and elastin structure in TgLOX mice. We identify LOX as a novel source of vascular reactive oxygen species and a new pathway involved in vascular stiffness and elastin remodeling in hypertension. LOX up-regulation is associated with enhanced oxidative stress that promotes p38MAPK activation, elastin structural alterations, and vascular stiffness. This pathway contributes to vascular abnormalities in hypertension. Antioxid. Redox Signal. 27

  10. Abnormal tibiofemoral contact stress and its association with altered kinematics following center-center ACL reconstruction: an in vitro study

    PubMed Central

    Imhauser, Carl; Mauro, Craig; Choi, Daniel; Rosenberg, Eric; Mathew, Stephen; Nguyen, Joseph; Ma, Yan; Wickiewicz, Thomas

    2014-01-01

    Background Abnormal tibiofemoral contact stress and aberrant kinematics may influence the progression of osteoarthritis in the ACL-deficient and the ACL-reconstructed knee. However, relationships between contact stress and kinematics following ACL reconstruction are poorly understood. Therefore, we posed the following research questions: (1) How do ACL deficiency and reconstruction affect kinematics of and contact stress in the tibiofemoral joint? (2) What kinematic differences are associated with abnormal contact stress following ACL reconstruction? Hypothesis/Purpose Center-center ACL reconstruction will not restore knee kinematics and contact stress. Correlations will exist between abnormal contact stress and aberrant kinematics following ACL reconstruction will exist. Study Design Controlled laboratory study Methods Clinical tests of anterior and rotational stability were simulated on eleven cadaveric knees using an industrial robot. Tests were conducted with the ACL intact, sectioned, and after single bundle ACL reconstruction using a quadrupled hamstring autograft with tunnels drilled through the center of the native footprints. Kinematics were recorded during the tests. Contact stress was continuously recorded from a stress transducer fixed to the tibial plateau and mean contact stress was calculated regionally. Results ACL deficiency resulted in increased mean contact stress in the posterior sectors of the medial and lateral compartments under anterior and rotational loads, respectively. Reconstruction reduced stress in these locations; however contact stress abnormalities remained. On average, kinematics were overconstrained following ACL reconstruction (≤1.8mm and ≤2.6° in all directions). However, combinations of overconstrained and underconstrained motions in ab/adduction and medial-lateral translation in response to combined moments, and axial rotation, anterior-posterior and medial-lateral translation in response to an anterior load were

  11. Familial Risk for Insomnia Is Associated With Abnormal Cortisol Response to Stress.

    PubMed

    Drake, Christopher L; Cheng, Philip; Almeida, David M; Roth, Thomas

    2017-10-01

    Abnormalities in the stress system have been implicated in insomnia. However, studies examining physiological stress regulation in insomnia have not consistently detected differences in the hypothalamic-pituitary-adrenal (HPA)-axis response to stress. One explanation may be that deficits in the stress system are associated specifically with a biological vulnerability to insomnia rather than the phenotypic expression of insomnia. To examine stress response as a function of vulnerability to insomnia, this study tested response to the Trier Social Stress Test in a sample of healthy sleepers with varying familial risks for insomnia. Thirty-five healthy individuals with and without familial risk for insomnia were recruited to complete a laboratory stressor. Participants with one or both biological parents with insomnia were categorized as positive for familial risk, whereas those without biological parents with insomnia were categorized as negative for familial risk. Participants completed the Trier Social Stress Test in the laboratory, and psychological and physiological (autonomic and HPA-axis) responses were compared. Despite self-reported increases in anxiety, those positive for familial risk exhibited a blunted cortisol response relative to those without familial risk for insomnia. Individuals with blunted cortisol also reported heightened reactivity to personal life stressors, including increased sleep disturbances, elevated cognitive intrusions, and more behavioral avoidance. Findings from this study provide initial evidence that abnormal stress regulation may be a biological predisposing factor conferred via familial risk for insomnia. This deficit may also predict negative consequences over time, including insomnia and the associated psychiatric comorbidities. © Sleep Research Society 2017. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

  12. Mechanisms of developing post-traumatic stress disorder: new targets for drug development and other potential interventions.

    PubMed

    Wimalawansa, Sunil J

    2014-01-01

    The post-traumatic stress disorder (PTSD) is defined as a severe anxiety disorder that develops after exposure to an event with actual, threatened, or perceived death or serious injury, or a threat to the physical integrity of oneself or others that results in significant psychological trauma. Moreover, the ability of people to handle acute severe stress experiences varies among individuals. Depending on the underlying personality and resiliency, therefore, PTSD can occur in individuals exposed to exceedingly stressful incidences or those who have encountered seemingly less overwhelming stressors. In addition to severe stressful exposure, multiple other factors including genetic susceptibility; past experiences; cultural, spiritual, and personal beliefs; bullying and harassments; and lack of support at the workplace, social, and home environement may contribute to the development of PTSD. Author investigated multiple potential mechanisms for the development and sustenance of PTSD based on the recent literature and his own experiences and insight. Based on this search, author indicates that among other pathological and biochemical abnormalities, hormonal aberrations are most likely key mechanisms initiating and the maintenance of the PTSD. These pathophysiological neuro-hormonal changes instigate maladaptive learning processes caused by sustained high levels of anxiety and fear, through a hypo-responsive hypothalamic-pituitary axis and hyper-responsive catecholamine system (persistently elevated blood norepinephrine levels and lower than appropriate glucocorticoid levels). In addition to having inappropriately low serum cortisol levels and high epinephrine and norepinephrine levels, patients with PTSD also have mitochondrial dysfunctions and other hormonal abnormalities. Based on these data, author concluded that these pathological, biochemical and sustained neurohormonal abnormalities are likely to influence the structural brain changes, particularly in the

  13. Mechanism of abnormally slow crystal growth of CuZr alloy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yan, X. Q.; Lü, Y. J., E-mail: yongjunlv@bit.edu.cn; State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027

    2015-10-28

    Crystal growth of the glass-forming CuZr alloy is shown to be abnormally slow, which suggests a new method to identify the good glass-forming alloys. The crystal growth of elemental Cu, Pd and binary NiAl, CuZr alloys is systematically studied with the aid of molecular dynamics simulations. The temperature dependence of the growth velocity indicates the different growth mechanisms between the elemental and the alloy systems. The high-speed growth featuring the elemental metals is dominated by the non-activated collision between liquid-like atoms and interface, and the low-speed growth for NiAl and CuZr is determined by the diffusion across the interface. Wemore » find that, in contrast to Cu, Pd, and NiAl, a strong stress layering arisen from the density and the local order layering forms in front of the liquid-crystal interface of CuZr alloy, which causes a slow diffusion zone. The formation of the slow diffusion zone suppresses the interface moving, resulting in much small growth velocity of CuZr alloy. We provide a direct evidence of this explanation by applying the compressive stress normal to the interface. The compression is shown to boost the stress layering in CuZr significantly, correspondingly enhancing the slow diffusion zone, and eventually slowing down the crystal growth of CuZr alloy immediately. In contrast, the growth of Cu, Pd, and NiAl is increased by the compression because the low diffusion zones in them are never well developed.« less

  14. Abnormal tibiofemoral contact stress and its association with altered kinematics after center-center anterior cruciate ligament reconstruction: an in vitro study.

    PubMed

    Imhauser, Carl; Mauro, Craig; Choi, Daniel; Rosenberg, Eric; Mathew, Stephen; Nguyen, Joseph; Ma, Yan; Wickiewicz, Thomas

    2013-04-01

    Abnormal tibiofemoral contact stress and aberrant kinematics may influence the progression of osteoarthritis in the anterior cruciate ligament (ACL)-deficient and the ACL-reconstructed knee. However, relationships between contact stress and kinematics after ACL reconstruction are poorly understood. Therefore, we posed the following research questions: (1) How do ACL deficiency and reconstruction affect the kinematics of and contact stress in the tibiofemoral joint? (2) What kinematic differences are associated with abnormal contact stress after ACL reconstruction? Center-center ACL reconstruction will not restore knee kinematics and contact stress. Correlations will exist between abnormal contact stress and aberrant kinematics after ACL reconstruction. Controlled laboratory study. Clinical tests of anterior and rotational stability were simulated on 11 cadaveric knees using an industrial robot. Tests were conducted with the ACL intact, sectioned, and after single-bundle ACL reconstruction using a quadrupled hamstring autograft with tunnels drilled through the center of the native footprints. Kinematics were recorded during the tests. Contact stress was continuously recorded from a stress transducer fixed to the tibial plateau, and mean contact stress was calculated regionally. ACL deficiency resulted in increased mean contact stress in the posterior sectors of the medial and lateral compartments under anterior and rotational loads, respectively. Reconstruction reduced stress in these locations; however, contact stress abnormalities remained. On average, kinematics were overconstrained after ACL reconstruction (≤1.8 mm and ≤2.6° in all directions). However, combinations of overconstrained and underconstrained motions in abduction/adduction and medial-lateral translation in response to combined moments, and anterior-posterior translation, medial-lateral translation, and axial rotation in response to an anterior load were associated with abnormal mean contact

  15. Lysyl Oxidase Induces Vascular Oxidative Stress and Contributes to Arterial Stiffness and Abnormal Elastin Structure in Hypertension: Role of p38MAPK

    PubMed Central

    Martínez-Revelles, Sonia; García-Redondo, Ana B.; Avendaño, María S.; Varona, Saray; Palao, Teresa; Orriols, Mar; Roque, Fernanda R.; Fortuño, Ana; Touyz, Rhian M.; Martínez-González, Jose; Salaices, Mercedes

    2017-01-01

    Abstract Aims: Vascular stiffness, structural elastin abnormalities, and increased oxidative stress are hallmarks of hypertension. Lysyl oxidase (LOX) is an elastin crosslinking enzyme that produces H2O2 as a by-product. We addressed the interplay between LOX, oxidative stress, vessel stiffness, and elastin. Results: Angiotensin II (Ang II)-infused hypertensive mice and spontaneously hypertensive rats (SHR) showed increased vascular LOX expression and stiffness and an abnormal elastin structure. Mice over-expressing LOX in vascular smooth muscle cells (TgLOX) exhibited similar mechanical and elastin alterations to those of hypertensive models. LOX inhibition with β-aminopropionitrile (BAPN) attenuated mechanical and elastin alterations in TgLOX mice, Ang II-infused mice, and SHR. Arteries from TgLOX mice, Ang II-infused mice, and/or SHR exhibited increased vascular H2O2 and O2.− levels, NADPH oxidase activity, and/or mitochondrial dysfunction. BAPN prevented the higher oxidative stress in hypertensive models. Treatment of TgLOX and Ang II-infused mice and SHR with the mitochondrial-targeted superoxide dismutase mimetic mito-TEMPO, the antioxidant apocynin, or the H2O2 scavenger polyethylene glycol-conjugated catalase (PEG-catalase) reduced oxidative stress, vascular stiffness, and elastin alterations. Vascular p38 mitogen-activated protein kinase (p38MAPK) activation was increased in Ang II-infused and TgLOX mice and this effect was prevented by BAPN, mito-TEMPO, or PEG-catalase. SB203580, the p38MAPK inhibitor, normalized vessel stiffness and elastin structure in TgLOX mice. Innovation: We identify LOX as a novel source of vascular reactive oxygen species and a new pathway involved in vascular stiffness and elastin remodeling in hypertension. Conclusion: LOX up-regulation is associated with enhanced oxidative stress that promotes p38MAPK activation, elastin structural alterations, and vascular stiffness. This pathway contributes to vascular abnormalities in

  16. Fluid shear stress as a regulator of gene expression in vascular cells: possible correlations with diabetic abnormalities

    NASA Technical Reports Server (NTRS)

    Papadaki, M.; Eskin, S. G.; Ruef, J.; Runge, M. S.; McIntire, L. V.

    1999-01-01

    Diabetes mellitus is associated with increased frequency, severity and more rapid progression of cardiovascular diseases. Metabolic perturbations from hyperglycemia result in disturbed endothelium-dependent relaxation, activation of coagulation pathways, depressed fibrinolysis, and other abnormalities in vascular homeostasis. Atherosclerosis is localized mainly at areas of geometric irregularity at which blood vessels branch, curve and change diameter, and where blood is subjected to sudden changes in velocity and/or direction of flow. Shear stress resulting from blood flow is a well known modulator of vascular cell function. This paper presents what is currently known regarding the molecular mechanisms responsible for signal transduction and gene regulation in vascular cells exposed to shear stress. Considering the importance of the hemodynamic environment of vascular cells might be vital to increasing our understanding of diabetes.

  17. Psychological stress exposure to aged mice causes abnormal feeding patterns with changes in the bout number.

    PubMed

    Yamada, Chihiro; Mogami, Sachiko; Hattori, Tomohisa

    2017-11-09

    Stress responses are affected by aging. However, studies on stress-related changes in feeding patterns with aging subject are minimal. We investigated feeding patterns induced by two psychological stress models, revealing characteristics of stress-induced feeding patterns as "meal" and "bout" (defined as the minimum feeding behavior parameters) in aged mice. Feeding behaviors of C57BL/6J mice were monitored for 24 h by an automatic monitoring device. Novelty stress reduced the meal amount over the 24 h in both young and aged mice, but as a result of a time course study it was persistent in aged mice. In addition, the decreased bout number was more pronounced in aged mice than in young mice. The 24-h meal and bout parameters did not change in either the young or aged mice following water avoidance stress (WAS). However, the meal amount and bout number increased in aged mice for 0-6 h after WAS exposure but remained unchanged in young mice. Our findings suggest that changes in bout number may lead to abnormal stress-related feeding patterns and may be one tool for evaluating eating abnormality in aged mice.

  18. Mechanisms of Stress-Induced Visceral Pain: Implications in Irritable Bowel Syndrome.

    PubMed

    Greenwood-Van Meerveld, B; Moloney, R D; Johnson, A C; Vicario, M

    2016-08-01

    Visceral pain is a term describing pain originating from the internal organs of the body and is a common feature of many disorders, including irritable bowel syndrome (IBS). Stress is implicated in the development and exacerbation of many visceral pain disorders. Recent evidence suggests that stress and the gut microbiota can interact through complementary or opposing factors to influence visceral nociceptive behaviours. The Young Investigator Forum at the International Society of Psychoneuroendocrinology (ISPNE) annual meeting reported experimental evidence suggesting the gut microbiota can affect the stress response to affect visceral pain. Building upon human imaging data showing abnormalities in the central processing of visceral stimuli in patients with IBS and knowledge that the amygdala plays a pivotal role in facilitating the stress axis, the latest experimental evidence supporting amygdala-mediated mechanisms in stress-induced visceral pain was reviewed. The final part of the session at ISPNE reviewed experimental evidence suggesting that visceral pain in IBS may be a result, at least in part, of afferent nerve sensitisation following increases in epithelial permeability and mucosal immune activation. © 2016 British Society for Neuroendocrinology.

  19. The Roles of Mechanical Stresses in the Pathogenesis of Osteoarthritis

    PubMed Central

    Anderson, Donald D.; Brown, Thomas D.; Tochigi, Yuki; Martin, James A.

    2013-01-01

    Excessive joint surface loadings, either single (acute impact event) or repetitive (cumulative contact stress), can cause the clinical syndrome of osteoarthritis (OA). Despite advances in treatment of injured joints, the risk of OA following joint injuries has not decreased in the past 50 years. Cumulative excessive articular surface contact stress that leads to OA results from posttraumatic joint incongruity and instability, and joint dysplasia, but may also cause OA in patients without known joint abnormalities. In vitro investigations show that excessive articular cartilage loading triggers release of reactive oxygen species (ROS) from mitochondria, and that these ROS cause chondrocyte death and matrix degradation. Preventing release of ROS or inhibiting their effects preserves chondrocytes and their matrix. Fibronectin fragments released from articular cartilage subjected to excessive loads also stimulate matrix degradation; inhibition of molecular pathways initiated by these fragments prevents this effect. Additionally, injured chondrocytes release alarmins that activate chondroprogentior cells in vitro that propogate and migrate to regions of damaged cartilage. These cells also release chemokines and cytokines that may contribute to inflammation that causes progressive cartilage loss. Distraction and motion of osteoarthritic human ankles can promote joint remodeling, decrease pain, and improve joint function in patients with end-stage posttraumatic OA. These advances in understanding of how altering mechanical stresses can lead to remodeling of osteoarthritic joints and how excessive stress causes loss of articular cartilage, including identification of mechanically induced mediators of cartilage loss, provide the basis for new biologic and mechanical approaches to the prevention and treatment of OA. PMID:25067995

  20. Abnormal Fear Memory as a Model for Posttraumatic Stress Disorder.

    PubMed

    Desmedt, Aline; Marighetto, Aline; Piazza, Pier-Vincenzo

    2015-09-01

    For over a century, clinicians have consistently described the paradoxical co-existence in posttraumatic stress disorder (PTSD) of sensory intrusive hypermnesia and declarative amnesia for the same traumatic event. Although this amnesia is considered as a critical etiological factor of the development and/or persistence of PTSD, most current animal models in basic neuroscience have focused exclusively on the hypermnesia, i.e., the persistence of a strong fear memory, neglecting the qualitative alteration of fear memory. The latest is characterized by an underrepresentation of the trauma in the context-based declarative memory system in favor of its overrepresentation in a cue-based sensory/emotional memory system. Combining psychological and neurobiological data as well as theoretical hypotheses, this review supports the idea that contextual amnesia is at the core of PTSD and its persistence and that altered hippocampal-amygdalar interaction may contribute to such pathologic memory. In a first attempt to unveil the neurobiological alterations underlying PTSD-related hypermnesia/amnesia, we describe a recent animal model mimicking in mice some critical aspects of such abnormal fear memory. Finally, this line of argument emphasizes the pressing need for a systematic comparison between normal/adaptive versus abnormal/maladaptive fear memory to identify biomarkers of PTSD while distinguishing them from general stress-related, potentially adaptive, neurobiological alterations. Copyright © 2015 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  1. Stress--the battle for hearts and minds: links between depression, stress and ischemic heart disease.

    PubMed

    Korszun, Ania; Frenneaux, Michael P

    2006-09-01

    Depression and ischemic heart disease (IHD) are strongly related common disorders. Depression itself is an independent cardiac risk factor and is associated with a two- to threefold increase in IHD mortality. Attention has now shifted to identifying the common underlying mechanisms that could make individuals susceptible to both disorders. Abnormalities that have been implicated in this relationship include abnormal platelet activation, decreased baroreceptor sensitivity and endothelial dysfunction. Depression and IHD both have a high association with environmental stress, and depression is characterized by abnormalities of the stress-hormone axis. This review provides a brief overview of some recent developments in our understanding of the pathophysiological links between stress, depression and IHD.

  2. [Role of stress in depression insomnia and sleep characteristics of commonly used animal stress models].

    PubMed

    Li, Yi-Ying; Hu, Zhen-Zhen; Huang, Zhi-Li; Yang, Su-Rong

    2012-01-01

    Depression and insomnia are intimately related. Depressed patients usually manifest sleep discontinuity and early awakening, reduced or no slow wave sleep (SWS) and shortened latency of rapid eye movement (REM) sleep. These sleep abnormalities are very similar to those caused by over activated hypothalamic-pituitary-adrenal (HPA) axis with stress. Therefore, the animal models developed by post-traumatic stress disorder or chronic unpredictable mild stress could be used to evaluate drugs which have effects of both anti-depression and improvement of sleep quality, and to provide a more reliable platform for further studis on the mechanisms of depression and accompanied insomnia. This review mainly focuses on the typical features of sleep disturbance of depression, possible pathophysiological mechanisms, establishment of animal stress models and analysis of their abnormal sleep characteristics.

  3. Polε Instability Drives Replication Stress, Abnormal Development, and Tumorigenesis.

    PubMed

    Bellelli, Roberto; Borel, Valerie; Logan, Clare; Svendsen, Jennifer; Cox, Danielle E; Nye, Emma; Metcalfe, Kay; O'Connell, Susan M; Stamp, Gordon; Flynn, Helen R; Snijders, Ambrosius P; Lassailly, François; Jackson, Andrew; Boulton, Simon J

    2018-05-17

    DNA polymerase ε (POLE) is a four-subunit complex and the major leading strand polymerase in eukaryotes. Budding yeast orthologs of POLE3 and POLE4 promote Polε processivity in vitro but are dispensable for viability in vivo. Here, we report that POLE4 deficiency in mice destabilizes the entire Polε complex, leading to embryonic lethality in inbred strains and extensive developmental abnormalities, leukopenia, and tumor predisposition in outbred strains. Comparable phenotypes of growth retardation and immunodeficiency are also observed in human patients harboring destabilizing mutations in POLE1. In both Pole4 -/- mouse and POLE1 mutant human cells, Polε hypomorphy is associated with replication stress and p53 activation, which we attribute to inefficient replication origin firing. Strikingly, removing p53 is sufficient to rescue embryonic lethality and all developmental abnormalities in Pole4 null mice. However, Pole4 -/- p53 +/- mice exhibit accelerated tumorigenesis, revealing an important role for controlled CMG and origin activation in normal development and tumor prevention. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

  4. A mechanical model predicts morphological abnormalities in the developing human brain

    NASA Astrophysics Data System (ADS)

    Budday, Silvia; Raybaud, Charles; Kuhl, Ellen

    2014-07-01

    The developing human brain remains one of the few unsolved mysteries of science. Advancements in developmental biology, neuroscience, and medical imaging have brought us closer than ever to understand brain development in health and disease. However, the precise role of mechanics throughout this process remains underestimated and poorly understood. Here we show that mechanical stretch plays a crucial role in brain development. Using the nonlinear field theories of mechanics supplemented by the theory of finite growth, we model the human brain as a living system with a morphogenetically growing outer surface and a stretch-driven growing inner core. This approach seamlessly integrates the two popular but competing hypotheses for cortical folding: axonal tension and differential growth. We calibrate our model using magnetic resonance images from very preterm neonates. Our model predicts that deviations in cortical growth and thickness induce morphological abnormalities. Using the gyrification index, the ratio between the total and exposed surface area, we demonstrate that these abnormalities agree with the classical pathologies of lissencephaly and polymicrogyria. Understanding the mechanisms of cortical folding in the developing human brain has direct implications in the diagnostics and treatment of neurological disorders, including epilepsy, schizophrenia, and autism.

  5. Mechanisms of Normal and Abnormal Endometrial Bleeding

    PubMed Central

    Lockwood, Charles J.

    2011-01-01

    Expression of tissue factor (TF), the primary initiator of coagulation, is enhanced in decidualized human endometrial stromal cells (HESC) during the progesterone-dominated luteal phase. Progesterone also augments a second HESC hemostatic factor, plasminogen activator inhibitor-1 (PAI-1). In contrast, progestins inhibit HESC matrix metalloproteinase (MMP)-1, 3 and 9 expression to stabilize endometrial stromal and vascular extracellular matrix. Through these mechanisms decidualized endometrium is rendered both hemostatic and resistant to excess trophoblast invasion in the mid-luteal phase and throughout gestation to prevent hemorrhage and accreta. In non-fertile cycles, progesterone withdrawal results in decreased HESC TF and PAI-expression and increased MMP activity and inflammatory cytokine production promoting the controlled hemorrhage of menstruation and related tissue sloughing. In contrast to these well ordered biochemical processes, unpredictable endometrial bleeding associated with anovulation reflects absence of progestational effects on TF, PAI-1 and MMP activity as well as unrestrained angiogenesis rendering the endometrium non-hemostatic, proteolytic and highly vascular. Abnormal bleeding associated with long-term progestin-only contraceptives results not from impaired hemostasis but from unrestrained angiogenesis leading to large fragile endometrial vessels. This abnormal angiogenesis reflects progestational inhibition of endometrial blood flow promoting local hypoxia and generation of reactive oxygen species that increase production of angiogenic factors such as vascular endothelial growth factor (VEGF) in HESCs and Angiopoietin-2 (Ang-2) in endometrial endothelial cells while decreasing HESC expression of angiostatic, Ang-1. The resulting vessel fragility promotes bleeding. Aberrant angiogenesis also underlies abnormal bleeding associated with myomas and endometrial polyps however there are gaps in our understanding of this pathology. PMID:21499503

  6. The impact of static stress change, dynamic stress change, and the background stress on aftershock focal mechanisms

    USGS Publications Warehouse

    Hardebeck, Jeanne L.

    2014-01-01

    The focal mechanisms of earthquakes in Southern California before and after four M ≥ 6.7 main shocks provide insight into how fault systems respond to stress and changes in stress. The main shock static stress changes have two observed impacts on the seismicity: changing the focal mechanisms in a given location to favor those aligned with the static stress change and changing the spatial distribution of seismicity to favor locations where the static stress change aligns with the background stress. The aftershock focal mechanisms are significantly aligned with the static stress changes for absolute stress changes of ≥ 0.02 MPa, for up to ~20 years following the main shock. The dynamic stress changes have similar, although smaller, effects on the local focal mechanisms and the spatial seismicity distribution. Dynamic stress effects are best observed at long periods (30–60 s) and for metrics based on repeated stress cycling in the same direction. This implies that dynamic triggering operates, at least in part, through cyclic shear stress loading in the direction of fault slip. The background stress also strongly controls both the preshock and aftershock mechanisms. While most aftershock mechanisms are well oriented in the background stress field, 10% of aftershocks are identified as poorly oriented outliers, which may indicate limited heterogeneity in the postmain shock stress field. The fault plane orientations of the outliers are well oriented in the background stress, while their slip directions are not, implying that the background stress restricts the distribution of available fault planes.

  7. Redox imbalance and mitochondrial abnormalities in the diabetic lung.

    PubMed

    Wu, Jinzi; Jin, Zhen; Yan, Liang-Jun

    2017-04-01

    Although the lung is one of the least studied organs in diabetes, increasing evidence indicates that it is an inevitable target of diabetic complications. Nevertheless, the underlying biochemical mechanisms of lung injury in diabetes remain largely unexplored. Given that redox imbalance, oxidative stress, and mitochondrial dysfunction have been implicated in diabetic tissue injury, we set out to investigate mechanisms of lung injury in diabetes. The objective of this study was to evaluate NADH/NAD + redox status, oxidative stress, and mitochondrial abnormalities in the diabetic lung. Using STZ induced diabetes in rat as a model, we measured redox-imbalance related parameters including aldose reductase activity, level of poly ADP ribose polymerase (PAPR-1), NAD + content, NADPH content, reduced form of glutathione (GSH), and glucose 6-phophate dehydrogenase (G6PD) activity. For assessment of mitochondrial abnormalities in the diabetic lung, we measured the activities of mitochondrial electron transport chain complexes I to IV and complex V as well as dihydrolipoamide dehydrogenase (DLDH) content and activity. We also measured the protein content of NAD + dependent enzymes such as sirtuin3 (sirt3) and NAD(P)H: quinone oxidoreductase 1 (NQO1). Our results demonstrate that NADH/NAD + redox imbalance occurs in the diabetic lung. This redox imbalance upregulates the activities of complexes I to IV, but not complex V; and this upregulation is likely the source of increased mitochondrial ROS production, oxidative stress, and cell death in the diabetic lung. These results, together with the findings that the protein contents of DLDH, sirt3, and NQO1 all are decreased in the diabetic lung, demonstrate that redox imbalance, mitochondrial abnormality, and oxidative stress contribute to lung injury in diabetes. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  8. Stress and tension-type headache mechanisms.

    PubMed

    Cathcart, Stuart; Winefield, Anthony H; Lushington, Kurt; Rolan, Paul

    2010-10-01

    Stress is widely demonstrated as a contributing factor in tension-type headache (TTH). The mechanisms underlying this remain unclear at present. Recent research indicates the importance of central pain processes in tension-type headache (TTH) pathophysiology. Concurrently, research with animals and healthy humans has begun to elucidate the relationship between stress and pain processing in the central nervous system, including central pain processes putatively dysfunctional in TTH. Combined, these two fields of research present new insights and hypotheses into possible mechanisms by which stress may contribute to TTH. To date, however, there has been no comprehensive review of this literature. The present paper provides such a review, which may be valuable in facilitating a broader understanding of the central mechanisms by which stress may contribute to TTH.

  9. Examining the mediating roles of binge eating and emotional eating in the relationships between stress and metabolic abnormalities

    PubMed Central

    Grey, Margaret; Whittemore, Robin; Reuning-Scherer, Jonathan; Grilo, Carlos M.; Sinha, Rajita

    2017-01-01

    To test whether binge eating and emotional eating mediate the relationships between self-reported stress, morning cortisol and the homeostatic model of insulin resistance and waist circumference. We also explored the moderators of gender and age. Data were from 249 adults (mean BMI = 26.9 ± 5.1 kg/m2; mean age = 28.3 ± 8.3 years; 54.2 % male; 69.5 % white) recruited from the community who were enrolled in a cross-sectional study. Participants completed a comprehensive assessment panel of psychological and physiological assessments including a morning blood draw for plasma cortisol. We found negative relationships between stress and morning cortisol (r = −0.15 to −0.21; p < 0.05), and cortisol and the homeostatic model of insulin resistance and waist circumference (r = −0.16, −0.25, respectively; p < 0.05). There was not statistical support for binge eating or emotional eating as mediators and no support for moderated mediation for either gender or age; however, gender moderated several paths in the model. These include the paths between perceived stress and emotional eating (B = 0.009, p < 0.001), perceived stress and binge eating (B = 0.01, p = 0.003), and binge eating and increased HOMA-IR (B = 0.149, p = 0.018), which were higher among females. Among women, perceived stress may be an important target to decrease binge and emotional eating. It remains to be determined what physiological and psychological mechanisms underlie the relationships between stress and metabolic abnormalities. PMID:26686376

  10. Improving Abnormality Detection on Chest Radiography Using Game-Like Reinforcement Mechanics.

    PubMed

    Chen, Po-Hao; Roth, Howard; Galperin-Aizenberg, Maya; Ruutiainen, Alexander T; Gefter, Warren; Cook, Tessa S

    2017-11-01

    Despite their increasing prevalence, online textbooks, question banks, and digital references focus primarily on explicit knowledge. Implicit skills such as abnormality detection require repeated practice on clinical service and have few digital substitutes. Using mechanics traditionally deployed in video games such as clearly defined goals, rapid-fire levels, and narrow time constraints may be an effective way to teach implicit skills. We created a freely available, online module to evaluate the ability of individuals to differentiate between normal and abnormal chest radiographs by implementing mechanics, including instantaneous feedback, rapid-fire cases, and 15-second timers. Volunteer subjects completed the modules and were separated based on formal experience with chest radiography. Performance between training and testing sets were measured for each group, and a survey was administered after each session. The module contained 74 cases and took approximately 20 minutes to complete. Thirty-two cases were normal radiographs and 56 cases were abnormal. Of the 60 volunteers recruited, 25 were "never trained" and 35 were "previously trained." "Never trained" users scored 21.9 out of 37 during training and 24.0 out of 37 during testing (59.1% vs 64.9%, P value <.001). "Previously trained" users scored 28.0 out of 37 during training and 28.3 out of 37 during testing phases (75.6% vs 76.4%, P value = .56). Survey results showed that 87% of all subjects agreed the module is an efficient way of learning, and 83% agreed the rapid-fire module is valuable for medical students. A gamified online module may improve the abnormality detection rates of novice interpreters of chest radiography, although experienced interpreters are less likely to derive similar benefits. Users reviewed the educational module favorably. Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

  11. Stress during a Critical Postnatal Period Induces Region-Specific Structural Abnormalities and Dysfunction of the Prefrontal Cortex via CRF1

    PubMed Central

    Yang, Xiao-Dun; Liao, Xue-Mei; Uribe-Mariño, Andrés; Liu, Rui; Xie, Xiao-Meng; Jia, Jiao; Su, Yun-Ai; Li, Ji-Tao; Schmidt, Mathias V; Wang, Xiao-Dong; Si, Tian-Mei

    2015-01-01

    During the early postnatal period, environmental influences play a pivotal role in shaping the development of the neocortex, including the prefrontal cortex (PFC) that is crucial for working memory and goal-directed actions. Exposure to stressful experiences during this critical period may disrupt the development of PFC pyramidal neurons and impair the wiring and function of related neural circuits. However, the molecular mechanisms of the impact of early-life stress on PFC development and function are not well understood. In this study, we found that repeated stress exposure during the first postnatal week hampered dendritic development in layers II/III and V pyramidal neurons in the dorsal agranular cingulate cortex (ACd) and prelimbic cortex (PL) of neonatal mice. The deleterious effects of early postnatal stress on structural plasticity persisted to adulthood only in ACd layer V pyramidal neurons. Most importantly, concurrent blockade of corticotropin-releasing factor receptor 1 (CRF1) by systemic antalarmin administration (20 μg/g of body weight) during early-life stress exposure prevented stress-induced apical dendritic retraction and spine loss in ACd layer V neurons and impairments in PFC-dependent cognitive tasks. Moreover, the magnitude of dendritic regression, especially the shrinkage of apical branches, of ACd layer V neurons predicted the degree of cognitive deficits in stressed mice. Our data highlight the region-specific effects of early postnatal stress on the structural plasticity of prefrontal pyramidal neurons, and suggest a critical role of CRF1 in modulating early-life stress-induced prefrontal abnormalities. PMID:25403725

  12. Network Mechanisms Generating Abnormal and Normal Hippocampal High-Frequency Oscillations: A Computational Analysis1,2,3

    PubMed Central

    Catoni, Nicholas

    2015-01-01

    Abstract High-frequency oscillations (HFOs) are an intriguing potential biomarker for epilepsy, typically categorized according to peak frequency as either ripples (100–250 Hz) or fast ripples (>250 Hz). In the hippocampus, fast ripples were originally thought to be more specific to epileptic tissue, but it is still very difficult to distinguish which HFOs are caused by normal versus pathological brain activity. In this study, we use a computational model of hippocampus to investigate possible network mechanisms underpinning normal ripples, pathological ripples, and fast ripples. Our results unify several prior findings regarding HFO mechanisms, and also make several new predictions regarding abnormal HFOs. We show that HFOs are generic, emergent phenomena whose characteristics reflect a wide range of connectivity and network input. Although produced by different mechanisms, both normal and abnormal HFOs generate similar ripple frequencies, underscoring that peak frequency is unable to distinguish the two. Abnormal ripples are generic phenomena that arise when input to pyramidal cells overcomes network inhibition, resulting in high-frequency, uncoordinated firing. In addition, fast ripples transiently and sporadically arise from the precise conditions that produce abnormal ripples. Lastly, we show that such abnormal conditions do not require any specific network structure to produce coherent HFOs, as even completely asynchronous activity is capable of producing abnormal ripples and fast ripples in this manner. These results provide a generic, network-based explanation for the link between pathological ripples and fast ripples, and a unifying description for the entire spectrum from normal ripples to pathological fast ripples. PMID:26146658

  13. Resveratrol Treatment after Status Epilepticus Restrains Neurodegeneration and Abnormal Neurogenesis with Suppression of Oxidative Stress and Inflammation.

    PubMed

    Mishra, Vikas; Shuai, Bing; Kodali, Maheedhar; Shetty, Geetha A; Hattiangady, Bharathi; Rao, Xiaolan; Shetty, Ashok K

    2015-12-07

    Antiepileptic drug therapy, though beneficial for restraining seizures, cannot thwart status epilepticus (SE) induced neurodegeneration or down-stream detrimental changes. We investigated the efficacy of resveratrol (RESV) for preventing SE-induced neurodegeneration, abnormal neurogenesis, oxidative stress and inflammation in the hippocampus. We induced SE in young rats and treated with either vehicle or RESV, commencing an hour after SE induction and continuing every hour for three-hours on SE day and twice daily thereafter for 3 days. Seizures were terminated in both groups two-hours after SE with a diazepam injection. In contrast to the vehicle-treated group, the hippocampus of animals receiving RESV during and after SE presented no loss of glutamatergic neurons in hippocampal cell layers, diminished loss of inhibitory interneurons expressing parvalbumin, somatostatin and neuropeptide Y in the dentate gyrus, reduced aberrant neurogenesis with preservation of reelin + interneurons, lowered concentration of oxidative stress byproduct malondialdehyde and pro-inflammatory cytokine tumor necrosis factor-alpha, normalized expression of oxidative stress responsive genes and diminished numbers of activated microglia. Thus, 4 days of RESV treatment after SE is efficacious for thwarting glutamatergic neuron degeneration, alleviating interneuron loss and abnormal neurogenesis, and suppressing oxidative stress and inflammation. These results have implications for restraining SE-induced chronic temporal lobe epilepsy.

  14. Ultrastructural and cellular basis for the development of abnormal myocardial mechanics during the transition from hypertension to heart failure.

    PubMed

    Shah, Sanjiv J; Aistrup, Gary L; Gupta, Deepak K; O'Toole, Matthew J; Nahhas, Amanda F; Schuster, Daniel; Chirayil, Nimi; Bassi, Nikhil; Ramakrishna, Satvik; Beussink, Lauren; Misener, Sol; Kane, Bonnie; Wang, David; Randolph, Blake; Ito, Aiko; Wu, Megan; Akintilo, Lisa; Mongkolrattanothai, Thitipong; Reddy, Mahendra; Kumar, Manvinder; Arora, Rishi; Ng, Jason; Wasserstrom, J Andrew

    2014-01-01

    Although the development of abnormal myocardial mechanics represents a key step during the transition from hypertension to overt heart failure (HF), the underlying ultrastructural and cellular basis of abnormal myocardial mechanics remains unclear. We therefore investigated how changes in transverse (T)-tubule organization and the resulting altered intracellular Ca(2+) cycling in large cell populations underlie the development of abnormal myocardial mechanics in a model of chronic hypertension. Hearts from spontaneously hypertensive rats (SHRs; n = 72) were studied at different ages and stages of hypertensive heart disease and early HF and were compared with age-matched control (Wistar-Kyoto) rats (n = 34). Echocardiography, including tissue Doppler and speckle-tracking analysis, was performed just before euthanization, after which T-tubule organization and Ca(2+) transients were studied using confocal microscopy. In SHRs, abnormalities in myocardial mechanics occurred early in response to hypertension, before the development of overt systolic dysfunction and HF. Reduced longitudinal, circumferential, and radial strain as well as reduced tissue Doppler early diastolic tissue velocities occurred in concert with T-tubule disorganization and impaired Ca(2+) cycling, all of which preceded the development of cardiac fibrosis. The time to peak of intracellular Ca(2+) transients was slowed due to T-tubule disruption, providing a link between declining cell ultrastructure and abnormal myocardial mechanics. In conclusion, subclinical abnormalities in myocardial mechanics occur early in response to hypertension and coincide with the development of T-tubule disorganization and impaired intracellular Ca(2+) cycling. These changes occur before the development of significant cardiac fibrosis and precede the development of overt cardiac dysfunction and HF.

  15. A risk score for predicting coronary artery disease in women with angina pectoris and abnormal stress test finding.

    PubMed

    Lo, Monica Y; Bonthala, Nirupama; Holper, Elizabeth M; Banks, Kamakki; Murphy, Sabina A; McGuire, Darren K; de Lemos, James A; Khera, Amit

    2013-03-15

    Women with angina pectoris and abnormal stress test findings commonly have no epicardial coronary artery disease (CAD) at catheterization. The aim of the present study was to develop a risk score to predict obstructive CAD in such patients. Data were analyzed from 337 consecutive women with angina pectoris and abnormal stress test findings who underwent cardiac catheterization at our center from 2003 to 2007. Forward selection multivariate logistic regression analysis was used to identify the independent predictors of CAD, defined by ≥50% diameter stenosis in ≥1 epicardial coronary artery. The independent predictors included age ≥55 years (odds ratio 2.3, 95% confidence interval 1.3 to 4.0), body mass index <30 kg/m(2) (odds ratio 1.9, 95% confidence interval 1.1 to 3.1), smoking (odds ratio 2.6, 95% confidence interval 1.4 to 4.8), low high-density lipoprotein cholesterol (odds ratio 2.9, 95% confidence interval 1.5 to 5.5), family history of premature CAD (odds ratio 2.4, 95% confidence interval 1.0 to 5.7), lateral abnormality on stress imaging (odds ratio 2.8, 95% confidence interval 1.5 to 5.5), and exercise capacity <5 metabolic equivalents (odds ratio 2.4, 95% confidence interval 1.1 to 5.6). Assigning each variable 1 point summed to constitute a risk score, a graded association between the score and prevalent CAD (ptrend <0.001). The risk score demonstrated good discrimination with a cross-validated c-statistic of 0.745 (95% confidence interval 0.70 to 0.79), and an optimized cutpoint of a score of ≤2 included 62% of the subjects and had a negative predictive value of 80%. In conclusion, a simple clinical risk score of 7 characteristics can help differentiate those more or less likely to have CAD among women with angina pectoris and abnormal stress test findings. This tool, if validated, could help to guide testing strategies in women with angina pectoris. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Mechanical stress regulation of plant growth and development

    NASA Technical Reports Server (NTRS)

    Mitchell, C. A.; Myers, P. N.

    1995-01-01

    The authors introduce the chapter with a discussion of lessons from nature, agriculture, and landscapes; terms and definitions; and an historical perspective of mechanical stress regulation of plant growth and development. Topics include developmental responses to mechanical stress; mechanical stress-environment interactions; metabolic, productivity, and compositional changes; hormonal involvement; mechanoperception and early transduction mechanisms; applications in agriculture; and research implications. The discussion of hormonal involvement in mechanical stress physiology includes ethylene, auxin, gibberellins, and other phytohormones. The discussion of applications in agriculture examines windbreaks, nursery practices, height control and conditioning, and enhancement of growth and productivity. Implications for research are related to handling plant materials, space biology, and future research needs.

  17. Mechanical stress modified ferroelectric aging behavior

    NASA Astrophysics Data System (ADS)

    Xu, Tingting; Kan, Yi; Jin, Yaming; Sun, Hui; Du, Yingchao; Wu, Xiumei; Bo, Huifeng; Cai, Wei; Huang, Fengzhen; Lu, Xiaomei; Zhu, Jinsong

    2013-05-01

    Mechanical stress effect on aging behavior of Bi3.25La0.75Ti3O12 (BLT) and PbZr0.53Ti0.47O3 (PZT) films was investigated. It is found that the remnant polarization decreases with time while the coercive field increases in stress-free BLT films. For unconfined PZT films, both the remnant polarization and the coercive field decrease as time elapses. The applied tensile stress weakens the aging of remnant polarization of BLT films but strengthens the aging of coercive field, while the applied tensile stress possesses opposite effect. In contrary, the applied compressive stress simultaneously improves the aging behavior of both remnant polarization and coercive field of PZT films. Mechanical-stress-induced variation of domain wall mobility in different materials was suggested as the possible origin of these observations. This work indicates that the aging behavior modification using stress could be realized, and it is helpful for promoting the reliability of ferroelectric films for industrial applications.

  18. Abnormalities in neuroendocrine stress response in psychosis: the role of endocannabinoids.

    PubMed

    Appiah-Kusi, E; Leyden, E; Parmar, S; Mondelli, V; McGuire, P; Bhattacharyya, S

    2016-01-01

    The aim of this article is to summarize current evidence regarding alterations in the neuroendocrine stress response system and endocannabinoid system and their relationship in psychotic disorders such as schizophrenia. Exposure to stress is linked to the development of a number of psychiatric disorders including psychosis. However, the precise role of stress in the development of psychosis and the possible mechanisms that might underlie this are not well understood. Recently the cannabinoid hypothesis of schizophrenia has emerged as a potential line of enquiry. Endocannabinoid levels are increased in patients with psychosis compared with healthy volunteers; furthermore, they increase in response to stress, which suggests another potential mechanism for how stress might be a causal factor in the development of psychosis. However, research regarding the links between stress and the endocannabinoid system is in its infancy. Evidence summarized here points to an alteration in the baseline tone and reactivity of the hypothalamic-pituitary-adrenal (HPA) axis as well as in various components of the endocannabinoid system in patients with psychosis. Moreover, the precise nature of the inter-relationship between these two systems is unclear in man, especially their biological relevance in the context of psychosis. Future studies need to simultaneously investigate HPA axis and endocannabinoid alterations both at baseline and following experimental perturbation in healthy individuals and those with psychosis to understand how they interact with each other in health and disease and obtain mechanistic insight as to their relevance to the pathophysiology of schizophrenia.

  19. Focal adhesions, stress fibers and mechanical tension

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Burridge, Keith, E-mail: Keith_Burridge@med.unc.edu; Guilluy, Christophe, E-mail: christophe.guilluy@univ-nantes.fr

    Stress fibers and focal adhesions are complex protein arrays that produce, transmit and sense mechanical tension. Evidence accumulated over many years led to the conclusion that mechanical tension generated within stress fibers contributes to the assembly of both stress fibers themselves and their associated focal adhesions. However, several lines of evidence have recently been presented against this model. Here we discuss the evidence for and against the role of mechanical tension in driving the assembly of these structures. We also consider how their assembly is influenced by the rigidity of the substratum to which cells are adhering. Finally, we discussmore » the recently identified connections between stress fibers and the nucleus, and the roles that these may play, both in cell migration and regulating nuclear function. - Highlights: • The different types of stress fiber and focal adhesion are described. • We discuss the controversy about tension and assembly of these structures. • We describe the different models used to investigate assembly of these structures. • The influence of substratum rigidity is discussed. • Stress fiber connections to the nucleus are reviewed.« less

  20. Planktonic foraminiferal abnormalities in coastal and open marine eastern Mediterranean environments: A natural stress monitoring approach in recent and early Holocene marine systems

    NASA Astrophysics Data System (ADS)

    Antonarakou, A.; Kontakiotis, G.; Zarkogiannis, S.; Mortyn, P. G.; Drinia, H.; Koskeridou, E.; Anastasakis, G.

    2018-05-01

    Marine environmental status can be assessed through the study of bio-indicator species. Here, we monitor natural environmental stress by the occurrence of morphologically abnormal planktonic foraminiferal specimens from a suite of surface sediments in the eastern Mediterranean Sea. We also compare Scanning Electron Microscopy (SEM) abnormality observations from sapropel S1-derived sediments in the Aegean, Libyan and Levantine basins, since they provide a direct record of a natural stress experiment that took place over past time scales. At initial sapropel deposition levels, we observe increased growth asymmetry in Globigerinoides ruber twinned and twisted individuals, possibly associated with eutrophication and anoxia. In modern material, a range of malformations and aberrant morphologies from slight deformity with smaller or overdeveloped chambers to more severe deformity with abnormally protruding or misplaced chambers, distorted spirals, and double tests is also observed, as a result of the hypersaline, oligotrophic and oxygen-depleted nature of the Mediterranean Sea water column. Overall, we highlight the current use of the relative abundance of abnormal tests as a bio-indicator for monitoring natural stress, especially the occurrence of twin specimens as indicative of high-salinity stress conditions, and further illustrate the necessity to map both their spatial and temporal distribution for accurate paleoenvironmental reconstructions. Such an approach presents the advantage to rapidly provide information over wide spatial and temporal scales, extending our ability to monitor a wide variety of environments (from coastal to the open-sea). However, further investigations should extend this approach to test the robustness of our findings in a number of similar oceanic settings.

  1. Mechanisms and consequences of paternally transmitted chromosomal abnormalities

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Marchetti, F; Wyrobek, A J

    Paternally transmitted chromosomal damage has been associated with pregnancy loss, developmental and morphological defects, infant mortality, infertility, and genetic diseases in the offspring including cancer. There is epidemiological evidence linking paternal exposure to occupational or environmental agents with an increased risk of abnormal reproductive outcomes. There is also a large body of literature on germ cell mutagenesis in rodents showing that treatment of male germ cells with mutagens has dramatic consequences on reproduction producing effects such as those observed in human epidemiological studies. However, we know very little about the etiology, transmission and early embryonic consequences of paternally-derived chromosomal abnormalities.more » The available evidence suggests that: (1) there are distinct patterns of germ cell-stage differences in the sensitivity of induction of transmissible genetic damage with male postmeiotic cells being the most sensitive; (2) cytogenetic abnormalities at first metaphase after fertilization are critical intermediates between paternal exposure and abnormal reproductive outcomes; and, (3) there are maternally susceptibility factors that may have profound effects on the amount of sperm DNA damage that is converted into chromosomal aberrations in the zygote and directly affect the risk for abnormal reproductive outcomes.« less

  2. Dynamics of Mechanical Signal Transmission through Prestressed Stress Fibers

    PubMed Central

    Hwang, Yongyun; Barakat, Abdul I.

    2012-01-01

    Transmission of mechanical stimuli through the actin cytoskeleton has been proposed as a mechanism for rapid long-distance mechanotransduction in cells; however, a quantitative understanding of the dynamics of this transmission and the physical factors governing it remains lacking. Two key features of the actin cytoskeleton are its viscoelastic nature and the presence of prestress due to actomyosin motor activity. We develop a model of mechanical signal transmission through prestressed viscoelastic actin stress fibers that directly connect the cell surface to the nucleus. The analysis considers both temporally stationary and oscillatory mechanical signals and accounts for cytosolic drag on the stress fibers. To elucidate the physical parameters that govern mechanical signal transmission, we initially focus on the highly simplified case of a single stress fiber. The results demonstrate that the dynamics of mechanical signal transmission depend on whether the applied force leads to transverse or axial motion of the stress fiber. For transverse motion, mechanical signal transmission is dominated by prestress while fiber elasticity has a negligible effect. Conversely, signal transmission for axial motion is mediated uniquely by elasticity due to the absence of a prestress restoring force. Mechanical signal transmission is significantly delayed by stress fiber material viscosity, while cytosolic damping becomes important only for longer stress fibers. Only transverse motion yields the rapid and long-distance mechanical signal transmission dynamics observed experimentally. For simple networks of stress fibers, mechanical signals are transmitted rapidly to the nucleus when the fibers are oriented largely orthogonal to the applied force, whereas the presence of fibers parallel to the applied force slows down mechanical signal transmission significantly. The present results suggest that cytoskeletal prestress mediates rapid mechanical signal transmission and allows

  3. Fetal Stress and Programming of Hypoxic/Ischemic-Sensitive Phenotype in the Neonatal Brain: Mechanisms and Possible Interventions

    PubMed Central

    Li, Yong; Gonzalez, Pablo; Zhang, Lubo

    2012-01-01

    Growing evidence of epidemiological, clinical and experimental studies has clearly shown a close link between adverse in utero environment and the increased risk of neurological, psychological and psychiatric disorders in later life. Fetal stresses, such as hypoxia, malnutrition, and fetal exposure to nicotine, alcohol, cocaine and glucocorticoids may directly or indirectly act at cellular and molecular levels to alter the brain development and result in programming of heightened brain vulnerability to hypoxic-ischemic encephalopathy and the development of neurological diseases in the postnatal life. The underlying mechanisms are not well understood. However, glucocorticoids may play a crucial role in epigenetic programming of neurological disorders of fetal origins. This review summarizes the recent studies about the effects of fetal stress on the abnormal brain development, focusing on the cellular, molecular and epigenetic mechanisms and highlighting the central effects of glucocorticoids on programming of hypoxicischemic-sensitive phenotype in the neonatal brain, which may enhance the understanding of brain pathophysiology resulting from fetal stress and help explore potential targets of timely diagnosis, prevention and intervention in neonatal hypoxic-ischemic encephalopathy and other for brain disorders. PMID:22627492

  4. Psychological Stress Induces Temporary Masticatory Muscle Mechanical Sensitivity in Rats

    PubMed Central

    Huang, Fei; Zhang, Min; Chen, Yong-Jin; Li, Qiang; Wu, An-Zhen

    2011-01-01

    To explore the relationship between psychological stress and masticatory muscle pain, we created a communication stress animal model to determine whether psychological stress could induce increased mechanical sensitivity in masticatory muscles and to study the changes of mechanical nociceptive thresholds after stress removal. Forty-eight male Sprague-Dawley rats were divided into a control group (CON), a foot-shocked group (FS, including 3 subgroups recorded as FS-1, FS-2, and FS-3), a psychological stress group (PS), and a drug treatment group (DT). PS and DT rats were confined in a communication box for one hour a day to observe the psychological responses of neighboring FS rats.Measurements of the mechanical nociceptive thresholds of the bilateral temporal and masseter muscles showed a stimulus-response relationship between psychological stress and muscle mechanical sensitivity. The DT rats, who received a diazepam injection, showed almost the same mechanical sensitivity of the masticatory muscles to that of the control in response to psychological stress. Fourteen days after the psychological stressor was removed, the mechanical nociceptive thresholds returned to normal. These findings suggest that psychological stress is directly related to masticatory muscle pain. Removal of the stressor could be a useful method for relieving mechanical sensitivity increase induced by psychological stress. PMID:21331360

  5. Abnormal Hippocampal Morphology in Dissociative Identity Disorder and Posttraumatic Stress Disorder Correlates with Childhood Trauma and Dissociative Symptoms

    PubMed Central

    Chalavi, Sima; Vissia, Eline M.; Giesen, Mechteld E.; Nijenhuis, Ellert R.S.; Draijer, Nel; Cole, James H.; Dazzan, Paola; Pariante, Carmine M.; Madsen, Sarah K.; Rajagopalan, Priya; Thompson, Paul M.; Toga, Arthur W.; Veltman, Dick J.; Reinders, Antje A.T.S.

    2015-01-01

    Smaller hippocampal volume has been reported in individuals with posttraumatic stress disorder (PTSD) and dissociative identity disorder (DID), but the regional specificity of hippocampal volume reductions and the association with severity of dissociative symptoms and/or childhood traumatization are still unclear. Brain structural MRI scans were analyzed for 33 outpatients (17 with DID and 16 with PTSD only) and 28 healthy controls (HC), all matched for age, sex, and education. DID patients met criteria for PTSD (PTSD-DID). Hippocampal global and subfield volumes and shape measurements were extracted. We found that global hippocampal volume was significantly smaller in all 33 patients (left: 6.75%; right: 8.33%) compared to HC. PTSD-DID (left: 10.19%; right: 11.37%) and PTSD-only with a history of childhood traumatization (left: 7.11%; right: 7.31%) had significantly smaller global hippocampal volume relative to HC. PTSD-DID had abnormal shape and significantly smaller volume in the CA2-3, CA4-DG and (pre)subiculum compared to HC. In the patient groups, smaller global and subfield hippocampal volumes significantly correlated with higher severity of childhood traumatization and dissociative symptoms. These findings support a childhood trauma-related etiology for abnormal hippocampal morphology in both PTSD and DID and can further the understanding of neurobiological mechanisms involved in these disorders. PMID:25545784

  6. Mechanisms of pro-arrhythmic abnormalities in ventricular repolarisation and anti-arrhythmic therapies in human hypertrophic cardiomyopathy.

    PubMed

    Passini, Elisa; Mincholé, Ana; Coppini, Raffaele; Cerbai, Elisabetta; Rodriguez, Blanca; Severi, Stefano; Bueno-Orovio, Alfonso

    2016-07-01

    Hypertrophic cardiomyopathy (HCM) is a cause of sudden arrhythmic death, but the understanding of its pro-arrhythmic mechanisms and an effective pharmacological treatment are lacking. HCM electrophysiological remodelling includes both increased inward and reduced outward currents, but their role in promoting repolarisation abnormalities remains unknown. The goal of this study is to identify key ionic mechanisms driving repolarisation abnormalities in human HCM, and to evaluate anti-arrhythmic effects of single and multichannel inward current blocks. Experimental ionic current, action potential (AP) and Ca(2+)-transient (CaT) recordings were used to construct populations of human non-diseased and HCM AP models (n=9118), accounting for inter-subject variability. Simulations were conducted for several degrees of selective and combined inward current block. Simulated HCM cardiomyocytes exhibited prolonged AP and CaT, diastolic Ca(2+) overload and decreased CaT amplitude, in agreement with experiments. Repolarisation abnormalities in HCM models were consistently driven by L-type Ca(2+) current (ICaL) re-activation, and ICaL block was the most effective intervention to normalise repolarisation and diastolic Ca(2+), but compromised CaT amplitude. Late Na(+) current (INaL) block partially abolished repolarisation abnormalities, with small impact on CaT. Na(+)/Ca(2+) exchanger (INCX) block effectively restored repolarisation and CaT amplitude, but increased Ca(2+) overload. Multichannel block increased efficacy in normalising repolarisation, AP biomarkers and CaT amplitude compared to selective block. Experimentally-calibrated populations of human AP models identify ICaL re-activation as the key mechanism for repolarisation abnormalities in HCM, and combined INCX, INaL and ICaL block as effective anti-arrhythmic therapies also able to partially reverse the HCM electrophysiological phenotype. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  7. Mechanical Stress Promotes Cisplatin-Induced Hepatocellular Carcinoma Cell Death

    PubMed Central

    Riad, Sandra; Bougherara, Habiba

    2015-01-01

    Cisplatin (CisPt) is a commonly used platinum-based chemotherapeutic agent. Its efficacy is limited due to drug resistance and multiple side effects, thereby warranting a new approach to improving the pharmacological effect of CisPt. A newly developed mathematical hypothesis suggested that mechanical loading, when coupled with a chemotherapeutic drug such as CisPt and immune cells, would boost tumor cell death. The current study investigated the aforementioned mathematical hypothesis by exposing human hepatocellular liver carcinoma (HepG2) cells to CisPt, peripheral blood mononuclear cells, and mechanical stress individually and in combination. HepG2 cells were also treated with a mixture of CisPt and carnosine with and without mechanical stress to examine one possible mechanism employed by mechanical stress to enhance CisPt effects. Carnosine is a dipeptide that reportedly sequesters platinum-based drugs away from their pharmacological target-site. Mechanical stress was achieved using an orbital shaker that produced 300 rpm with a horizontal circular motion. Our results demonstrated that mechanical stress promoted CisPt-induced death of HepG2 cells (~35% more cell death). Moreover, results showed that CisPt-induced death was compromised when CisPt was left to mix with carnosine 24 hours preceding treatment. Mechanical stress, however, ameliorated cell death (20% more cell death). PMID:25685789

  8. Hypothalamic mitochondrial abnormalities occur downstream of inflammation in diet-induced obesity.

    PubMed

    Carraro, Rodrigo S; Souza, Gabriela F; Solon, Carina; Razolli, Daniela S; Chausse, Bruno; Barbizan, Roberta; Victorio, Sheila C; Velloso, Licio A

    2018-01-15

    Hypothalamic dysfunction is a common feature of experimental obesity. Studies have identified at least three mechanisms involved in the development of hypothalamic neuronal defects in diet-induced obesity: i, inflammation; ii, endoplasmic reticulum stress; and iii, mitochondrial abnormalities. However, which of these mechanisms is activated earliest in response to the consumption of large portions of dietary fats is currently unknown. Here, we used immunoblot, real-time PCR, mitochondrial respiration assays and transmission electron microscopy to evaluate markers of inflammation, endoplasmic reticulum stress and mitochondrial abnormalities in the hypothalamus of Swiss mice fed a high-fat diet for up to seven days. In the present study we show that the expression of the inflammatory chemokine fractalkine was the earliest event detected. Its hypothalamic expression increased as early as 3 h after the introduction of a high-fat diet and was followed by the increase of cytokines. GPR78, an endoplasmic reticulum chaperone, was increased 6 h after the introduction of a high-fat diet, however the actual triggering of endoplasmic reticulum stress was only detected three days later, when IRE-1α was increased. Mitofusin-2, a protein involved in mitochondrial fusion and tethering of mitochondria to the endoplasmic reticulum, underwent a transient reduction 24 h after the introduction of a high-fat diet and then increased after seven days. There were no changes in hypothalamic mitochondrial respiration during the experimental period, however there were reductions in mitochondria/endoplasmic reticulum contact sites, beginning three days after the introduction of a high-fat diet. The inhibition of TNF-α with infliximab resulted in the normalization of mitofusin-2 levels 24 h after the introduction of the diet. Thus, inflammation is the earliest mechanism activated in the hypothalamus after the introduction of a high-fat diet and may play a mechanistic role in the

  9. 46 CFR 54.30-10 - Method of performing mechanical stress relief.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... PRESSURE VESSELS Mechanical Stress Relief § 54.30-10 Method of performing mechanical stress relief. (a) The mechanical stress relief shall be carried out in accordance with the following stipulations using water as... 46 Shipping 2 2011-10-01 2011-10-01 false Method of performing mechanical stress relief. 54.30-10...

  10. 46 CFR 54.30-10 - Method of performing mechanical stress relief.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Method of performing mechanical stress relief. 54.30-10... PRESSURE VESSELS Mechanical Stress Relief § 54.30-10 Method of performing mechanical stress relief. (a) The mechanical stress relief shall be carried out in accordance with the following stipulations using water as...

  11. 46 CFR 54.30-10 - Method of performing mechanical stress relief.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Method of performing mechanical stress relief. 54.30-10... PRESSURE VESSELS Mechanical Stress Relief § 54.30-10 Method of performing mechanical stress relief. (a) The mechanical stress relief shall be carried out in accordance with the following stipulations using water as...

  12. 46 CFR 54.30-10 - Method of performing mechanical stress relief.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Method of performing mechanical stress relief. 54.30-10... PRESSURE VESSELS Mechanical Stress Relief § 54.30-10 Method of performing mechanical stress relief. (a) The mechanical stress relief shall be carried out in accordance with the following stipulations using water as...

  13. 46 CFR 54.30-10 - Method of performing mechanical stress relief.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Method of performing mechanical stress relief. 54.30-10... PRESSURE VESSELS Mechanical Stress Relief § 54.30-10 Method of performing mechanical stress relief. (a) The mechanical stress relief shall be carried out in accordance with the following stipulations using water as...

  14. Mechanical Stress Induces Biotic and Abiotic Stress Responses via a Novel cis-Element

    PubMed Central

    Walley, Justin W; Coughlan, Sean; Hudson, Matthew E; Covington, Michael F; Kaspi, Roy; Banu, Gopalan; Harmer, Stacey L; Dehesh, Katayoon

    2007-01-01

    Plants are continuously exposed to a myriad of abiotic and biotic stresses. However, the molecular mechanisms by which these stress signals are perceived and transduced are poorly understood. To begin to identify primary stress signal transduction components, we have focused on genes that respond rapidly (within 5 min) to stress signals. Because it has been hypothesized that detection of physical stress is a mechanism common to mounting a response against a broad range of environmental stresses, we have utilized mechanical wounding as the stress stimulus and performed whole genome microarray analysis of Arabidopsis thaliana leaf tissue. This led to the identification of a number of rapid wound responsive (RWR) genes. Comparison of RWR genes with published abiotic and biotic stress microarray datasets demonstrates a large overlap across a wide range of environmental stresses. Interestingly, RWR genes also exhibit a striking level and pattern of circadian regulation, with induced and repressed genes displaying antiphasic rhythms. Using bioinformatic analysis, we identified a novel motif overrepresented in the promoters of RWR genes, herein designated as the Rapid Stress Response Element (RSRE). We demonstrate in transgenic plants that multimerized RSREs are sufficient to confer a rapid response to both biotic and abiotic stresses in vivo, thereby establishing the functional involvement of this motif in primary transcriptional stress responses. Collectively, our data provide evidence for a novel cis-element that is distributed across the promoters of an array of diverse stress-responsive genes, poised to respond immediately and coordinately to stress signals. This structure suggests that plants may have a transcriptional network resembling the general stress signaling pathway in yeast and that the RSRE element may provide the key to this coordinate regulation. PMID:17953483

  15. Dislocation mechanisms in stressed crystals with surface effects

    NASA Astrophysics Data System (ADS)

    Wu, Chi-Chin; Crone, Joshua; Munday, Lynn; Discrete Dislocation Dynamics Team

    2014-03-01

    Understanding dislocation properties in stressed crystals is the key for important processes in materials science, including the strengthening of metals and the stress relaxation during the growth of hetero-epitaxial structures. Despite existing experimental approaches and theories, many dislocation mechanisms with surface effects still remain elusive in experiments. Even though discrete dislocation dynamics (DDD) simulations are commonly employed to study dislocations, few demonstrate sufficient computational capabilities for massive dislocations with the combined effects of surfaces and stresses. Utilizing the Army's newly developed FED3 code, a DDD computation code coupled with finite elements, this work presents several dislocation mechanisms near different types of surfaces in finite domains. Our simulation models include dislocations in a bended metallic cantilever beam, near voids in stressed metals, as well as threading and misfit dislocations in as-grown semiconductor epitaxial layers and their quantitative inter-correlations to stress relaxation and surface instability. Our studies provide not only detailed physics of individual dislocation mechanisms, but also important collective dislocation properties such as dislocation densities and strain-stress profiles and their interactions with surfaces.

  16. Metabolic consequences of stress during childhood and adolescence.

    PubMed

    Pervanidou, Panagiota; Chrousos, George P

    2012-05-01

    Stress, that is, the state of threatened or perceived as threatened homeostasis, is associated with activation of the stress system, mainly comprised by the hypothalamic-pituitary-adrenal axis and the arousal/sympathetic nervous systems. The stress system normally functions in a circadian manner and interacts with other systems to regulate a variety of behavioral, endocrine, metabolic, immune, and cardiovascular functions. However, the experience of acute intense physical or emotional stress, as well as of chronic stress, may lead to the development of or may exacerbate several psychologic and somatic conditions, including anxiety disorders, depression, obesity, and the metabolic syndrome. In chronically stressed individuals, both behavioral and neuroendocrine mechanisms promote obesity and metabolic abnormalities: unhealthy lifestyles in conjunction with dysregulation of the stress system and increased secretion of cortisol, catecholamines, and interleukin-6, with concurrently elevated insulin concentrations, lead to development of central obesity, insulin resistance, and the metabolic syndrome. Fetal life, childhood, and adolescence are particularly vulnerable periods of life to the effects of intense acute or chronic stress. Similarly, these life stages are crucial for the later development of behavioral, metabolic, and immune abnormalities. Developing brain structures and functions related to stress regulation, such as the amygdala, the hippocampus, and the mesocorticolimbic system, are more vulnerable to the effects of stress compared with mature structures in adults. Moreover, chronic alterations in cortisol secretion in children may affect the timing of puberty, final stature, and body composition, as well as cause early-onset obesity, metabolic syndrome, and type 2 diabetes mellitus. The understanding of stress mechanisms leading to metabolic abnormalities in early life may lead to more effective prevention and intervention strategies of obesity

  17. Abnormalities of Calcium Handling Proteins in Skeletal Muscle Mirror those of the Heart in Humans with Heart Failure: a Shared Mechanism?

    PubMed Central

    Middlekauff, Holly R.; Vigna, Chris; Verity, M. Anthony; Fonarow, Gregg C.; Horwich, Tamara B.; Hamilton, Michele A.; Shieh, Perry; Tupling, A. Russell

    2012-01-01

    Background In the failing human heart, abnormalities of Ca2+ cycling have been described, but there is scant knowledge about Ca2+ handling in the skeletal muscle of humans with HF. We tested the hypothesis that in humans with HF, Ca2+ cycling proteins in skeletal muscle are abnormal. Methods and Results Ten advanced HF patients (50.4±3.7 years), and 9 age matched controls underwent vastus lateralis biopsy. Western blot analysis showed that sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA)2a, which is responsible for Ca2+ sequestration into the sarcoplasmic reticulum(SR), was lower in HF vs controls (4.8±0.5vs7.5±0.8AU, p=0.01). Although phospholamban (PLN), which inhibits SERCA2a, was not different in HF vs controls, phosphorylation (SER16 site) of PLN, which relieves this inhibition, was reduced (0.8±0.1vs3.9±0.9AU, p=0.004). Dihydropyridine receptors were reduced in HF, (2.1±0.4vs3.6±0.5AU, p=0.04). We tested the hypothesis that these abnormalities of Ca2+ handling protein content and regulation were due to increased oxidative stress, but oxygen radical scavenger proteins were not elevated in the skeletal muscle of HF patients. Conclusion In chronic HF, marked abnormalities of Ca2+ handling proteins are present in skeletal muscle, which mirror those in failing heart tissue. This suggests a common mechanism, such as chronic augmentation of sympathetic activity and autophosphorylation of Ca2+-calmodulin-dependent-protein kinase II. PMID:22939042

  18. Cells Respond to Mechanical Stress by Rapid Disassembly of Caveolae

    PubMed Central

    Sinha, Bidisha; Köster, Darius; Ruez, Richard; Gonnord, Pauline; Bastiani, Michele; Abankwa, Daniel; Stan, Radu. V.; Butler-Browne, Gillian; Vedie, Benoit; Johannes, Ludger; Morone, Nobuhiro; Parton, Robert G.; Raposo, Graça; Sens, Pierre; Lamaze, Christophe; Nassoy, Pierre

    2011-01-01

    SUMMARY The precise role of caveolae, the characteristic plasma membrane invaginations present in many cells, still remains debated. The high density of caveolae in cells experiencing mechanical stress led us to investigate their role in membrane-mediated mechanical response. Acute mechanical stress induced by cell osmotic swelling or by uniaxial stretching results in the immediate disappearance of caveolae, which is associated with a reduced caveolin/Cavin1 interaction, and an increase of free caveolins at the plasma membrane. Tether pulling force measurements in live cells and in plasma membrane spheres demonstrate that caveola flattening and disassembly is the primary actin and ATP-independent cell response which buffers membrane tension surges during mechanical stress. Conversely, stress release leads to complete caveola reassembly in an actin and ATP-dependent process. The absence of a functional caveola reservoir in myotubes from muscular dystrophic patients enhanced membrane fragility under mechanical stress. Our findings support a new role for caveolae as a physiological membrane reservoir that allows cells to quickly accommodate sudden and acute mechanical stresses. PMID:21295700

  19. Abnormal hippocampal morphology in dissociative identity disorder and post-traumatic stress disorder correlates with childhood trauma and dissociative symptoms.

    PubMed

    Chalavi, Sima; Vissia, Eline M; Giesen, Mechteld E; Nijenhuis, Ellert R S; Draijer, Nel; Cole, James H; Dazzan, Paola; Pariante, Carmine M; Madsen, Sarah K; Rajagopalan, Priya; Thompson, Paul M; Toga, Arthur W; Veltman, Dick J; Reinders, Antje A T S

    2015-05-01

    Smaller hippocampal volume has been reported in individuals with post-traumatic stress disorder (PTSD) and dissociative identity disorder (DID), but the regional specificity of hippocampal volume reductions and the association with severity of dissociative symptoms and/or childhood traumatization are still unclear. Brain structural magnetic resonance imaging scans were analyzed for 33 outpatients (17 with DID and 16 with PTSD only) and 28 healthy controls (HC), all matched for age, sex, and education. DID patients met criteria for PTSD (PTSD-DID). Hippocampal global and subfield volumes and shape measurements were extracted. We found that global hippocampal volume was significantly smaller in all 33 patients (left: 6.75%; right: 8.33%) compared with HC. PTSD-DID (left: 10.19%; right: 11.37%) and PTSD-only with a history of childhood traumatization (left: 7.11%; right: 7.31%) had significantly smaller global hippocampal volume relative to HC. PTSD-DID had abnormal shape and significantly smaller volume in the CA2-3, CA4-DG and (pre)subiculum compared with HC. In the patient groups, smaller global and subfield hippocampal volumes significantly correlated with higher severity of childhood traumatization and dissociative symptoms. These findings support a childhood trauma-related etiology for abnormal hippocampal morphology in both PTSD and DID and can further the understanding of neurobiological mechanisms involved in these disorders. © 2014 Wiley Periodicals, Inc.

  20. Study of mechanism of stress-induced threshold voltage shift and recovery in top-gate amorphous-InGaZnO4 thin-film transistors with source- and drain-offsets

    NASA Astrophysics Data System (ADS)

    Mativenga, Mallory; Kang, Dong Han; Lee, Ung Gi; Jang, Jin

    2012-09-01

    Bias instability of top-gate amorphous-indium-gallium-zinc-oxide thin-film transistors with source- and drain-offsets is reported. Positive and negative gate bias-stress (VG_STRESS) respectively induce reversible negative threshold-voltage shift (ΔVTH) and reduction in on-current. Migration of positive charges towards the offsets lowers the local resistance of the offsets, resulting in the abnormal negative ΔVTH under positive VG_STRESS. The reduction in on-current under negative VG_STRESS is due to increase in resistance of the offsets when positive charges migrate away from the offsets. Appropriate drain and source bias-stresses applied simultaneously with VG_STRESS either suppress or enhance the instability, verifying lateral ion migration to be the instability mechanism.

  1. Effect of Mechanical Stresses on Characteristics of Chip Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander A.

    2007-01-01

    The effect of compressive mechanical stresses on chip solid tantalum capacitors is investigated by monitoring characteristics of different part types under axial and hydrostatic stresses. Depending on part types, an exponential increase of leakage currents was observed when stresses exceeded 10 MPa to 40 MPa. For the first time, reversible variations of leakage currents (up to two orders of magnitude) with stress have been demonstrated. Mechanical stresses did not cause significant changes of AC characteristics of the capacitors, whereas breakdown voltages measured during the surge current testing decreased substantially indicating an increased probability of failures of stressed capacitors in low impedance applications. Variations of leakage currents are explained by a combination of two mechanisms: stress-induced scintillations and stress-induced generation of electron traps in the tantalum pentoxide dielectric.

  2. Developmental Ethanol Exposure Leads to Dysregulation of Lipid Metabolism and Oxidative Stress in Drosophila

    PubMed Central

    Logan-Garbisch, Theresa; Bortolazzo, Anthony; Luu, Peter; Ford, Audrey; Do, David; Khodabakhshi, Payam; French, Rachael L.

    2014-01-01

    Ethanol exposure during development causes an array of developmental abnormalities, both physiological and behavioral. In mammals, these abnormalities are collectively known as fetal alcohol effects (FAE) or fetal alcohol spectrum disorder (FASD). We have established a Drosophila melanogaster model of FASD and have previously shown that developmental ethanol exposure in flies leads to reduced expression of insulin-like peptides (dILPs) and their receptor. In this work, we link that observation to dysregulation of fatty acid metabolism and lipid accumulation. Further, we show that developmental ethanol exposure in Drosophila causes oxidative stress, that this stress is a primary cause of the developmental lethality and delay associated with ethanol exposure, and, finally, that one of the mechanisms by which ethanol increases oxidative stress is through abnormal fatty acid metabolism. These data suggest a previously uncharacterized mechanism by which ethanol causes the symptoms associated with FASD. PMID:25387828

  3. Abnormal early cleavage events predict early embryo demise: sperm oxidative stress and early abnormal cleavage.

    PubMed

    Burruel, Victoria; Klooster, Katie; Barker, Christopher M; Pera, Renee Reijo; Meyers, Stuart

    2014-10-13

    Human embryos resulting from abnormal early cleavage can result in aneuploidy and failure to develop normally to the blastocyst stage. The nature of paternal influence on early embryo development has not been directly demonstrated although many studies have suggested effects from spermatozoal chromatin packaging, DNA damage, centriolar and mitotic spindle integrity, and plasma membrane integrity. The goal of this study was to determine whether early developmental events were affected by oxidative damage to the fertilizing sperm. Survival analysis was used to compare patterns of blastocyst formation based on P2 duration. Kaplan-Meier survival curves demonstrate that relatively few embryos with short (<1 hr) P2 times reached blastocysts, and the two curves diverged beginning on day 4, with nearly all of the embryos with longer P2 times reaching blastocysts by day 6 (p < .01). We determined that duration of the 2nd to 3rd mitoses were sensitive periods in the presence of spermatozoal oxidative stress. Embryos that displayed either too long or too short cytokineses demonstrated an increased failure to reach blastocyst stage and therefore survive for further development. Although paternal-derived gene expression occurs later in development, this study suggests a specific role in early mitosis that is highly influenced by paternal factors.

  4. Stress regimes in the northwest of Iran from stress inversion of earthquake focal mechanisms

    NASA Astrophysics Data System (ADS)

    Afra, Mahsa; Moradi, Ali; Pakzad, Mehrdad

    2017-11-01

    Northwestern Iran is one of the seismically active regions with a high seismic risk in the world. This area is a part of the complex tectonic system due to the interaction between Arabia, Anatolia and Eurasia. The purpose of this study is to deduce the stress regimes in the northwestern Iran and surrounding regions from stress inversion of earthquake focal mechanisms. We compile 92 focal mechanisms data from the Global CMT catalogue and other sources and also determine the focal mechanisms of 14 earthquakes applying the moment tensor inversion. We divide the studied region into 9 zones using similarity of the horizontal GPS velocities and existing focal mechanisms. We implement two stress inversion methods, Multiple Inverse Method and Iterative Joint Inversion Method, which provide comparable results in terms of orientations of maximum horizontal stress axes SHmax. The similar results of the two methods should make us more confident about the interpretations. We consider zones of exclusion surrounding all the earthquakes according to independent focal mechanisms hypothesis. The hypothesis says that the inversion should involve events that are far enough from each other in order that any previous event doesn't affect the stress field near the earthquake under consideration. Accordingly we deal with the matter by considering zones of exclusion around all the events. The result of exclusion is only significant for eastern Anatolia. The stress regime in this region changes from oblique to strike slip faulting because of the exclusion. In eastern Anatolia, the direction of maximum horizontal stress is nearly north-south. The direction alters to east-west in Talesh region. Errors of σ1 are lower in all zones comparing with errors of σ2 and σ3 and there is a trade-off between data resolution and covariance of the model. The results substantiate the strike-slip and thrust faulting stress regimes in the northwest of Iran.

  5. Down's Syndrome and Leukemia: Mechanism of Additional Chromosomal Abnormalities

    ERIC Educational Resources Information Center

    And Others; Goh, Kong-oo

    1978-01-01

    Chromosomal abnormalities, some appearing in a stepwise clonal evoluation, were found in five Down's syndrome patients (35 weeks to 12 years old), four with acute leukemia and one with abnormal regulation of leukopoiesis. (Author/SBH)

  6. The Relationship between Personality Dimensions and Resiliency to Environmental Stress in Orange-Winged Amazon Parrots (Amazona amazonica), as Indicated by the Development of Abnormal Behaviors.

    PubMed

    Cussen, Victoria A; Mench, Joy A

    2015-01-01

    Parrots are popular companion animals, but are frequently relinquished because of behavioral problems, including abnormal repetitive behaviors like feather damaging behavior and stereotypy. In addition to contributing to pet relinquishment, these behaviors are important as potential indicators of diminished psychological well-being. While abnormal behaviors are common in captive animals, their presence and/or severity varies between animals of the same species that are experiencing the same environmental conditions. Personality differences could contribute to this observed individual variation, as they are known risk factors for stress sensitivity and affective disorders in humans. The goal of this study was to assess the relationship between personality and the development and severity of abnormal behaviors in captive-bred orange-winged Amazon parrots (Amazona amazonica). We monitored between-individual behavioral differences in enrichment-reared parrots of known personality types before, during, and after enrichment deprivation. We predicted that parrots with higher scores for neurotic-like personality traits would be more susceptible to enrichment deprivation and develop more abnormal behaviors. Our results partially supported this hypothesis, but also showed that distinct personality dimensions were related to different forms of abnormal behavior. While neuroticism-like traits were linked to feather damaging behavior, extraversion-like traits were negatively related to stereotypic behavior. More extraverted birds showed resiliency to environmental stress, developing fewer stereotypies during enrichment deprivation and showing lower levels of these behaviors following re-enrichment. Our data, together with the results of the few studies conducted on other species, suggest that, as in humans, certain personality types render individual animals more susceptible or resilient to environmental stress. Further, this susceptibility/resiliency can have a long

  7. The Relationship between Personality Dimensions and Resiliency to Environmental Stress in Orange-Winged Amazon Parrots (Amazona amazonica), as Indicated by the Development of Abnormal Behaviors

    PubMed Central

    Cussen, Victoria A.; Mench, Joy A.

    2015-01-01

    Parrots are popular companion animals, but are frequently relinquished because of behavioral problems, including abnormal repetitive behaviors like feather damaging behavior and stereotypy. In addition to contributing to pet relinquishment, these behaviors are important as potential indicators of diminished psychological well-being. While abnormal behaviors are common in captive animals, their presence and/or severity varies between animals of the same species that are experiencing the same environmental conditions. Personality differences could contribute to this observed individual variation, as they are known risk factors for stress sensitivity and affective disorders in humans. The goal of this study was to assess the relationship between personality and the development and severity of abnormal behaviors in captive-bred orange-winged Amazon parrots (Amazona amazonica). We monitored between-individual behavioral differences in enrichment-reared parrots of known personality types before, during, and after enrichment deprivation. We predicted that parrots with higher scores for neurotic-like personality traits would be more susceptible to enrichment deprivation and develop more abnormal behaviors. Our results partially supported this hypothesis, but also showed that distinct personality dimensions were related to different forms of abnormal behavior. While neuroticism-like traits were linked to feather damaging behavior, extraversion-like traits were negatively related to stereotypic behavior. More extraverted birds showed resiliency to environmental stress, developing fewer stereotypies during enrichment deprivation and showing lower levels of these behaviors following re-enrichment. Our data, together with the results of the few studies conducted on other species, suggest that, as in humans, certain personality types render individual animals more susceptible or resilient to environmental stress. Further, this susceptibility/resiliency can have a long

  8. Zika Virus (ZIKV): a review of proposed mechanisms of transmission and associated congenital abnormalities

    PubMed Central

    Desai, Sruti K; Hartman, Steven D; Jayarajan, Shilpa; Liu, Stephanie; Gallicano, G Ian

    2017-01-01

    Zika virus (ZIKV) has been of major international public health concern following large outbreaks in the Americas occurring in 2015-2016. Most notably, ZIKV has been seen to pose dangers in pregnancy due to its association with congenital abnormalities such as microcephaly. Numerous experimental approaches have been taken to address how the virus can cross the placenta, alter normal fetal development, and disrupt specific cellular functions. Many areas concerning the mechanisms of transmission, especially from mother to fetus, are largely unknown but demand further research. Several promising new studies are presented that provide insight into possible mechanisms of transmission, different cell types affected, and immune responses towards the virus. By aiming to better understand the processes behind altered fetal neuronal development due to ZIKV infection, the hope is to find ways to increase protection of the fetus and prevent congenital abnormalities such as microcephaly. As ZIKV infection is spreading to increasingly more areas and bringing harmful outcomes and birth defects with it, it is imperative to identify the mechanisms of transmitting this infectious agent, consider different genetic backgrounds of hosts and strain types, and navigate methods to protect those affected from the detrimental effects of this newly emerging virus. PMID:28804687

  9. [Mechanism Causing Abnormal Laboratory Data--Significance of Electrophoresis and Information Transmission--Chairmen's Introductory Remarks].

    PubMed

    Maekawa, Masato; Fujita, Kiyotaka

    2014-11-01

    Abnormal laboratory data are observed due to some kinds of modification as well as pathological conditions of patients. Elucidation of the causal mechanism is very important for clinical laboratories. This symposium was planned to highlight the significance of electrophoresis. Electrophoresis is one of the most important tools to provide clinicians with information for medical diagnosis and care.

  10. Epigenetic mechanisms of alcoholism and stress-related disorders.

    PubMed

    Palmisano, Martina; Pandey, Subhash C

    2017-05-01

    Stress-related disorders, such as anxiety, early life stress, and posttraumatic stress disorder appear to be important factors in promoting alcoholism, as alcohol consumption can temporarily attenuate the negative affective symptoms of these disorders. Several molecules involved in signaling pathways may contribute to the neuroadaptation induced during alcohol dependence and stress disorders, and among these, brain-derived neurotrophic factor (BDNF), corticotropin releasing factor (CRF), neuropeptide Y (NPY) and opioid peptides (i.e., nociceptin and dynorphin) are involved in the interaction of stress and alcohol. In fact, alterations in the expression and function of these molecules have been associated with the pathophysiology of stress-related disorders and alcoholism. In recent years, various studies have focused on the epigenetic mechanisms that regulate chromatin architecture, thereby modifying gene expression. Interestingly, epigenetic modifications in specific brain regions have been shown to be associated with the neurobiology of psychiatric disorders, including alcoholism and stress. In particular, the enzymes responsible for chromatin remodeling (i.e., histone deacetylases and methyltransferases, DNA methyltransferases) have been identified as common molecular mechanisms for the interaction of stress and alcohol and have become promising therapeutic targets to treat or prevent alcoholism and associated emotional disorders. Published by Elsevier Inc.

  11. EPIGENETIC MECHANISMS OF ALCOHOLISM AND STRESS-RELATED DISORDERS

    PubMed Central

    Palmisano, Martina; Pandey, Subhash C.

    2017-01-01

    Stress-related disorders, such as anxiety, early life stress and posttraumatic stress disorder appear to be important factors in promoting alcoholism, as alcohol consumption can temporarily attenuate the negative affective symptoms of these disorders. Several molecules involved in signaling pathways may contribute to the neuroadaptation induced during alcohol dependence and stress disorders, and among these, brain-derived neurotrophic factor (BDNF), corticotropin releasing factor (CRF), neuropeptide Y (NPY) and opioid peptides (i.e. nociceptin and dynorphin) are involved in the interaction of stress and alcohol. In fact, alterations in the expression and function of these molecules have been associated with the pathophysiology of stress-related disorders and alcoholism. In recent years, various studies have focused on the epigenetic mechanisms that regulate chromatin architecture thereby modifying gene expression. Interestingly, epigenetic modifications in specific brain regions have been shown to be associated with the neurobiology of psychiatric disorders, including alcoholism and stress. In particular, the enzymes responsible for chromatin remodeling (i.e. histone deacetylases and methyltransferases, DNA methyltransferases) have been identified as common molecular mechanisms for the interaction of stress and alcohol and have become promising therapeutic targets to treat or prevent alcoholism and associated emotional disorders. PMID:28477725

  12. Spinal cord stress injury assessment (SCOSIA): clinical applications of mechanical modeling of the spinal cord and brainstem

    NASA Astrophysics Data System (ADS)

    Wong, Kenneth H.; Choi, Jae; Wilson, William; Berry, Joel; Henderson, Fraser C., Sr.

    2009-02-01

    Abnormal stretch and strain is a major cause of injury to the spinal cord and brainstem. Such forces can develop from age-related degeneration, congenital malformations, occupational exposure, or trauma such as sporting accidents, whiplash and blast injury. While current imaging technologies provide excellent morphology and anatomy of the spinal cord, there is no validated diagnostic tool to assess mechanical stresses exerted upon the spinal cord and brainstem. Furthermore, there is no current means to correlate these stress patterns with known spinal cord injuries and other clinical metrics such as neurological impairment. We have therefore developed the spinal cord stress injury assessment (SCOSIA) system, which uses imaging and finite element analysis to predict stretch injury. This system was tested on a small cohort of neurosurgery patients. Initial results show that the calculated stress values decreased following surgery, and that this decrease was accompanied by a significant decrease in neurological symptoms. Regression analysis identified modest correlations between stress values and clinical metrics. The strongest correlations were seen with the Brainstem Disability Index (BDI) and the Karnofsky Performance Score (KPS), whereas the weakest correlations were seen with the American Spinal Injury Association (ASIA) scale. SCOSIA therefore shows encouraging initial results and may have wide applicability to trauma and degenerative disease involving the spinal cord and brainstem.

  13. Mechanisms of orthostatic intolerance during heat stress

    PubMed Central

    Schlader, Zachary J.; Wilson, Thad E.; Crandall, Craig G.

    2017-01-01

    Heat stress profoundly and unanimously reduces orthostatic tolerance. This review aims to provide an overview of the numerous and multifactorial mechanisms by which this occurs in humans. Potential causal factors include changes in arterial and venous vascular resistance and blood distribution, and the modulation of cardiac output, all of which contribute to the inability to maintain cerebral perfusion during heat and orthostatic stress. A number of countermeasures have been established to improve orthostatic tolerance during heat stress, which alleviate heat stress induced central hypovolemia (e.g., volume expansion) and/or increase peripheral vascular resistance (e.g., skin cooling). Unfortunately, these countermeasures can often be cumbersome to use with populations prone to syncopal episodes. Identifying the mechanisms of inter-individual differences in orthostatic intolerance during heat stress has proven elusive, but could provide greater insights into the development of novel and personalized countermeasures for maintaining or improving orthostatic tolerance during heat stress. This development will be especially impactful in occuational settings and clinical situations that present with orthostatic intolerance and/or central hypovolemia. Such investigations should be considered of vital importance given the impending increased incidence of heat events, and associated cardiovascular challenges that are predicted to occur with the ensuing changes in climate. PMID:26723547

  14. Site-specificity of abnormal excision: the mechanism of formation of a specialized transducing bacteriophage lambda plac5.

    PubMed Central

    Shpakovski, G V; Berlin, Y A

    1984-01-01

    Molecular mechanism of the specialized transducing bacteriophage lambda plac5 formation has been studied. Phage-bacterial DNA junctions in lambda plac5 DNA are localized and primary structure of regions of the abnormal excisional recombination leading to the phage formation is elucidated; the crossover region proved to be comparable with the central part of attP and attB sites (the core and the adjacent tetranucleotide) in length and degree of homology. Bacterial insert in lambda plac5 DNA is shown to end immediately after Z-Y spacer, the DNA not containing lacY gene segments. The data obtained led to the conclusion of site-specific (homologous) character of abnormal excision upon formation of lambda transducing bacteriophages. Possible mechanisms of the excision are discussed. Images PMID:6091038

  15. A multispecies approach for understanding neuroimmune mechanisms of stress.

    PubMed

    Deak, Terrence; Kudinova, Anastacia; Lovelock, Dennis F; Gibb, Brandon E; Hennessy, Michael B

    2017-03-01

    The relationship between stress challenges and adverse health outcomes, particularly for the development of affective disorders, is now well established. The highly conserved neuroimmune mechanisms through which responses to stressors are transcribed into effects on males and females have recently garnered much attention from researchers and clinicians alike. The use of animal models, from mice to guinea pigs to primates, has greatly increased our understanding of these mechanisms on the molecular, cellular, and behavioral levels, and research in humans has identified particular brain regions and connections of interest, as well as associations between stress-induced inflammation and psychiatric disorders. This review brings together findings from multiple species in order to better understand how the mechanisms of the neuroimmune response to stress contribute to stress-related psychopathologies, such as major depressive disorder, schizophrenia, and bipolar disorder.

  16. Stress Cardiac MRI in Women With Myocardial Infarction and Nonobstructive Coronary Artery Disease.

    PubMed

    Mauricio, Rina; Srichai, Monvadi B; Axel, Leon; Hochman, Judith S; Reynolds, Harmony R

    2016-10-01

    In a prospective study, cardiac MRI (CMR) and intravascular ultrasound were performed in women with myocardial infarction (MI) and nonobstructive coronary artery disease (MINOCA). Forty participants underwent adenosine-stress CMR (sCMR). Abnormal perfusion may co-localize with ischemic late gadolinium enhancement (LGE) and T2-weighted signal hyperintensity (T2+), suggesting microvascular dysfunction contributed to MI. Qualitative perfusion analysis was performed by 2 independent readers. Abnormal myocardial perfusion reserve index (MPRI) was defined as global average ≤1.84. Abnormal rest perfusion was present in 10 patients (25%) and stress perfusion abnormalities in 25 (63%). Abnormal stress perfusion was not associated with LGE but tended to occur with T2+. Among patients with abnormal perfusion and LGE, the LGE pattern was ischemic in half. The locations of abnormal perfusion and LGE matched in 75%, T2+ in 100%. Abnormal stress perfusion was not associated with plaque disruption and matched in location in 63%. MPRI was abnormal in 10 patients (25%) and was not associated with LGE, T2+ or plaque disruption. Abnormal perfusion on sCMR is common among women with MINOCA. Abnormal perfusion usually co-localized with LGE and/or T2+ when present. Variability in LGE pattern leads to uncertainty about whether the finding of abnormal perfusion was cause or consequence of the tissue state leading to LGE. Low MPRI, possibly indicating diffuse microvascular disease, was observed with and without LGE and T2+. Multiple mechanisms may lead to abnormal perfusion on sCMR. Microvascular dysfunction may contribute to the pathogenesis of and coexist with other causes of MINOCA. © 2016 Wiley Periodicals, Inc.

  17. Evaluation of tributyltin toxicity in Chinese rare minnow larvae by abnormal behavior, energy metabolism and endoplasmic reticulum stress.

    PubMed

    Li, Zhi-Hua; Li, Ping

    2015-02-05

    Tributyltin (TBT) is a ubiquitous contaminant in aquatic environment, but the detailed mechanisms underlying the toxicity of TBT have not been fully understood. In this study, the effects of TBT on behavior, energy metabolism and endoplasmic reticulum (ER) stress were investigated by using Chinese rare minnow larvae. Fish larvae were exposed at sublethal concentrations of TBT (100, 400 and 800 ng/L) for 7 days. Compared with the control, energy metabolic parameters (RNA/DNA ratio, Na(+)-K(+)-ATPase) were significantly inhibited in fish exposed at highest concentration (800 ng/L), as well as abnormal behaviors observed. Moreover, we found that the PERK (PKR-like ER kinase)-eIF2α (eukaryotic translation initiation factor 2α) pathway, as the main branch was activated by TBT exposure in fish larvae. In short, TBT-induced physiological, biochemical and molecular responses in fish larvae were reflected in parameters measured in this study, which suggest that these biomarkers could be used as potential indicators for monitoring organotin compounds present in aquatic environment. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  18. Mechanisms of stress in the brain.

    PubMed

    McEwen, Bruce S; Bowles, Nicole P; Gray, Jason D; Hill, Matthew N; Hunter, Richard G; Karatsoreos, Ilia N; Nasca, Carla

    2015-10-01

    The brain is the central organ involved in perceiving and adapting to social and physical stressors via multiple interacting mediators, from the cell surface to the cytoskeleton to epigenetic regulation and nongenomic mechanisms. A key result of stress is structural remodeling of neural architecture, which may be a sign of successful adaptation, whereas persistence of these changes when stress ends indicates failed resilience. Excitatory amino acids and glucocorticoids have key roles in these processes, along with a growing list of extra- and intracellular mediators that includes endocannabinoids and brain-derived neurotrophic factor (BDNF). The result is a continually changing pattern of gene expression mediated by epigenetic mechanisms involving histone modifications and CpG methylation and hydroxymethylation as well as by the activity of retrotransposons that may alter genomic stability. Elucidation of the underlying mechanisms of plasticity and vulnerability of the brain provides a basis for understanding the efficacy of interventions for anxiety and depressive disorders as well as age-related cognitive decline.

  19. Hydrogen content and mechanical stress in glow discharge amorphous silicon

    NASA Astrophysics Data System (ADS)

    Paduschek, P.; Eichinger, P.; Kristen, G.; Mitlehner, H.

    1982-08-01

    The hydrogen content of plasma deposited amorphous silicon thin films on silicon has been determined as a function of annealing parameters (200-700°C, 12 h) using the proton-proton scattering method. It is shown that hydrogen is released with an activation energy of 1.3 eV. Different deposition temperatures are compared with respect to the hydrogen evolution. The mechanical stress of the layers on silicon substrates has been measured by interferometric techniques for each annealing step. As the hydrogen content decreases monotonically with rising annealing temperature the mechanical stress converts from compressive to tensile. While only a weak correlation exists between the total hydrogen content and the mechanical stress, the bound hydrogen as determined by IR absorption displays a linear relation with the measured mechanical stress.

  20. A multispecies approach for understanding neuroimmune mechanisms of stress

    PubMed Central

    Deak, Terrence; Kudinova, Anastacia; Lovelock, Dennis F.; Gibb, Brandon E.; Hennessy, Michael B.

    2017-01-01

    The relationship between stress challenges and adverse health outcomes, particularly for the development of affective disorders, is now well established. The highly conserved neuroimmune mechanisms through which responses to stressors are transcribed into effects on males and females have recently garnered much attention from researchers and clinicians alike. The use of animal models, from mice to guinea pigs to primates, has greatly increased our understanding of these mechanisms on the molecular, cellular, and behavioral levels, and research in humans has identified particular brain regions and connections of interest, as well as associations between stress-induced inflammation and psychiatric disorders. This review brings together findings from multiple species in order to better understand how the mechanisms of the neuroimmune response to stress contribute to stress-related psychopathologies, such as major depressive disorder, schizophrenia, and bipolar disorder. PMID:28566946

  1. Aging of XLPE cable insulation under combined electrical and mechanical stresses

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    David, E.; Parpal, J.L.; Crine, J.P.

    1996-12-31

    Extruded crosslinked polyethylene (XLPE) insulation is widely used in high-voltage cables since it presents such attractive features as excellent dielectric properties and good thermomechanical behavior. However, its performance is affected by long-term degradation when it is subjected to the various thermal, mechanical and environmental stresses occurring in service in combination with electrical stress. The synergetic effect of superposed electrical and other stresses remains to be fully clarified. In particular, a fairly high level of mechanical stresses can be present in the insulation volume, originating from residual internal stresses created during the cooling process in the fabrication, external forces when cablesmore » are bent sharply, or thermomechanical stresses caused by differential thermal expansion between the conductor and the insulating material. In order to investigate the influence of the superposition of mechanical and electrical stresses, various measurements were conducted on XLPE and LDPE specimens in tip-plane and plane-plane geometries. Experimental data of time-to-breakdown, breakdown field and tree length are presented as a function of the magnitude of the stresses. In all cases, superposition of the mechanical stress was found to reduce the dielectric strength of the material.« less

  2. Parental decision-making after ultrasound diagnosis of a serious foetal abnormality.

    PubMed

    Bijma, Hilmar H; Wildschut, Hajo I J; van der Heide, Agnes; Passchier, Jan; Wladimiroff, Juriy W; van der Maas, Paul J

    2005-01-01

    The purpose of this article is to provide clinicians who are involved in the field of foetal medicine with a comprehensive overview of theories that are relevant for the parental decision-making process after ultrasound diagnosis of a serious foetal abnormality. Since little data are available of parental decision-making after ultrasound diagnosis of foetal abnormality, we reviewed the literature on parental decision-making in genetic counselling of couples at increased genetic risk together with the literature on general decision-making theories. The findings were linked to the specific situation of parental decision-making after an ultrasound diagnosis of foetal abnormality. Based on genetic counselling studies, several cognitive mechanisms play a role in parental decision-making regarding future pregnancies. Parents often have a binary perception of risk. Probabilistic information is translated into two options: the child will or will not be affected. The graduality of chance seems to be of little importance in this process. Instead, the focus shifts to the possible consequences for future family life. General decision-making theories often focus on rationality and coherence of the decision-making process. However, studies of both the influence of framing and the influence of stress indicate that emotional mechanisms can have an important and beneficial function in the decision-making process. Cognitive mechanisms that are elicited by emotions and that are not necessarily rational can have an important and beneficial function in parental decision-making after ultrasound diagnosis of a foetal abnormality. Consequently, the process of parental decision-making should not solely be assessed on the basis of its rationality, but also on the basis of the parental emotional outcome. Copyright (c) 2005 S. Karger AG, Basel.

  3. Glutamatergic Response to Heat Pain Stress in Schizophrenia.

    PubMed

    Chiappelli, Joshua; Shi, Qiaoyun; Wijtenburg, Sarah Andrea; Quiton, Raimi; Wisner, Krista; Gaston, Frank; Kodi, Priyadurga; Gaudiot, Christopher; Kochunov, Peter; Rowland, Laura M; Hong, Liyi Elliot

    2018-06-06

    Regulation of stress response involves top-down mechanisms of the frontal-limbic glutamatergic system. As schizophrenia is associated with glutamatergic abnormalities, we hypothesized that schizophrenia patients may have abnormal glutamatergic reactivity within the dorsal anterior cingulate cortex (dACC), a key region involved in perception of and reaction to stress. To test this, we developed a somatic stress paradigm involving pseudorandom application of safe but painfully hot stimuli to the forearm of participants while they were undergoing serial proton magnetic resonance spectroscopy to measure changes in glutamate and glutamine levels in the dACC. This paradigm was tested in a sample of 21 healthy controls and 23 patients with schizophrenia. Across groups, glutamate levels significantly decreased following exposure to thermal pain, while ratio of glutamine to glutamate significantly increased. However, schizophrenia patients exhibited an initial increase in glutamate levels during challenge that was significantly different from controls, after controlling for heat pain tolerance. Furthermore, in patients, the acute glutamate response was positively correlated with childhood trauma (r = .41, P = .050) and inversely correlated with working memory (r = -.49, P = .023). These results provide preliminary evidence for abnormal glutamatergic response to stress in schizophrenia patients, which may point toward novel approaches to understanding how stress contributes to the illness.

  4. Calculation and Visualization of Atomistic Mechanical Stresses in Nanomaterials and Biomolecules

    PubMed Central

    Gilson, Michael K.

    2014-01-01

    Many biomolecules have machine-like functions, and accordingly are discussed in terms of mechanical properties like force and motion. However, the concept of stress, a mechanical property that is of fundamental importance in the study of macroscopic mechanics, is not commonly applied in the biomolecular context. We anticipate that microscopical stress analyses of biomolecules and nanomaterials will provide useful mechanistic insights and help guide molecular design. To enable such applications, we have developed Calculator of Atomistic Mechanical Stress (CAMS), an open-source software package for computing atomic resolution stresses from molecular dynamics (MD) simulations. The software also enables decomposition of stress into contributions from bonded, nonbonded and Generalized Born potential terms. CAMS reads GROMACS topology and trajectory files, which are easily generated from AMBER files as well; and time-varying stresses may be animated and visualized in the VMD viewer. Here, we review relevant theory and present illustrative applications. PMID:25503996

  5. Calculation and visualization of atomistic mechanical stresses in nanomaterials and biomolecules.

    PubMed

    Fenley, Andrew T; Muddana, Hari S; Gilson, Michael K

    2014-01-01

    Many biomolecules have machine-like functions, and accordingly are discussed in terms of mechanical properties like force and motion. However, the concept of stress, a mechanical property that is of fundamental importance in the study of macroscopic mechanics, is not commonly applied in the biomolecular context. We anticipate that microscopical stress analyses of biomolecules and nanomaterials will provide useful mechanistic insights and help guide molecular design. To enable such applications, we have developed Calculator of Atomistic Mechanical Stress (CAMS), an open-source software package for computing atomic resolution stresses from molecular dynamics (MD) simulations. The software also enables decomposition of stress into contributions from bonded, nonbonded and Generalized Born potential terms. CAMS reads GROMACS topology and trajectory files, which are easily generated from AMBER files as well; and time-varying stresses may be animated and visualized in the VMD viewer. Here, we review relevant theory and present illustrative applications.

  6. Mechanical and hypoxia stress can cause chondrocytes apoptosis through over-activation of endoplasmic reticulum stress.

    PubMed

    Huang, Ziwei; Zhou, Min; Wang, Qian; Zhu, Mengjiao; Chen, Sheng; Li, Huang

    2017-12-01

    To examine the role of mechanical force and hypoxia on chondrocytes apoptosis and osteoarthritis (OA)-liked pathological change on mandibular cartilage through over-activation of endoplasmic reticulum stress (ERS). We used two in vitro models to examine the effect of mechanical force and hypoxia on chondrocytes apoptosis separately. The mandibular condylar chondrocytes were obtained from three-week-old male Sprague-Dawley rats. Flexcell 5000T apparatus was used to produce mechanical forces (12%, 0.5Hz, 24h vs 20%, 0.5Hz, 24h) on chondrocytes. For hypoxia experiment, the concentration of O 2 was down regulated to 5% or 1%. Cell apoptosis rates were quantified by annexin V and propidium iodide (PI) double staining and FACS analysis. Quantitative real-time PCR and western blot were performed to evaluate the activation of ERS and cellular hypoxia. Then we used a mechanical stress loading rat model to verify the involvement of ERS in OA-liked mandibular cartilage pathological change. Histological changes in mandibular condylar cartilage were assessed via hematoxylin & eosin (HE) staining. Immunohistochemistry of GRP78, GRP94, HIF-1α, and HIF-2α were performed to evaluate activation of the ERS and existence of hypoxia. Apoptotic cells were detected by the TUNEL method. Tunicamycin, 20% mechanical forces and hypoxia (1% O 2 ) all significantly increased chondrocytes apoptosis rates and expression of ERS markers (GRP78, GRP94 and Caspase 12). However, 12% mechanical forces can only increase the apoptotic sensitivity of chondrocytes. Mechanical stress resulted in OA-liked pathological change on rat mandibular condylar cartilage which included thinning cartilage and bone erosion. The number of apoptotic cells increased. ERS and hypoxia markers expressions were also enhanced. Salubrinal, an ERS inhibitor, can reverse these effects in vitro and in vivo through the down-regulation of ERS markers and hypoxia markers. We confirmed that mechanical stress and local hypoxia both

  7. The imperative for controlled mechanical stresses in unraveling cellular mechanisms of mechanotransduction

    PubMed Central

    Anderson, Eric J; Falls, Thomas D; Sorkin, Adam M; Tate, Melissa L Knothe

    2006-01-01

    Background In vitro mechanotransduction studies are designed to elucidate cell behavior in response to a well-defined mechanical signal that is imparted to cultured cells, e.g. through fluid flow. Typically, flow rates are calculated based on a parallel plate flow assumption, to achieve a targeted cellular shear stress. This study evaluates the performance of specific flow/perfusion chambers in imparting the targeted stress at the cellular level. Methods To evaluate how well actual flow chambers meet their target stresses (set for 1 and 10 dyn/cm2 for this study) at a cellular level, computational models were developed to calculate flow velocity components and imparted shear stresses for a given pressure gradient. Computational predictions were validated with micro-particle image velocimetry (μPIV) experiments. Results Based on these computational and experimental studies, as few as 66% of cells seeded along the midplane of commonly implemented flow/perfusion chambers are subjected to stresses within ±10% of the target stress. In addition, flow velocities and shear stresses imparted through fluid drag vary as a function of location within each chamber. Hence, not only a limited number of cells are exposed to target stress levels within each chamber, but also neighboring cells may experience different flow regimes. Finally, flow regimes are highly dependent on flow chamber geometry, resulting in significant variation in magnitudes and spatial distributions of stress between chambers. Conclusion The results of this study challenge the basic premise of in vitro mechanotransduction studies, i.e. that a controlled flow regime is applied to impart a defined mechanical stimulus to cells. These results also underscore the fact that data from studies in which different chambers are utilized can not be compared, even if the target stress regimes are comparable. PMID:16672051

  8. The neurobiology of abnormal manifestations of aggression--a review of hypothalamic mechanisms in cats, rodents, and humans.

    PubMed

    Haller, Jozsef

    2013-04-01

    Aggression research was for long dominated by the assumption that aggression-related psychopathologies result from the excessive activation of aggression-promoting brain mechanisms. This assumption was recently challenged by findings with models of aggression that mimic etiological factors of aggression-related psychopathologies. Subjects submitted to such procedures show abnormal attack features (mismatch between provocation and response, disregard of species-specific rules, and insensitivity toward the social signals of opponents). We review here 12 such laboratory models and the available human findings on the neural background of abnormal aggression. We focus on the hypothalamus, a region tightly involved in the execution of attacks. Data show that the hypothalamic mechanisms controlling attacks (general activation levels, local serotonin, vasopressin, substance P, glutamate, GABA, and dopamine neurotransmission) undergo etiological factor-dependent changes. Findings suggest that the emotional component of attacks differentiates two basic types of hypothalamic mechanisms. Aggression associated with increased arousal (emotional/reactive aggression) is paralleled by increased mediobasal hypothalamic activation, increased hypothalamic vasopressinergic, but diminished hypothalamic serotonergic neurotransmission. In aggression models associated with low arousal (unemotional/proactive aggression), the lateral but not the mediobasal hypothalamus is over-activated. In addition, the anti-aggressive effect of serotonergic neurotransmission is lost and paradoxical changes were noticed in vasopressinergic neurotransmission. We conclude that there is no single 'neurobiological road' to abnormal aggression: the neural background shows qualitative, etiological factor-dependent differences. Findings obtained with different models should be viewed as alternative mechanisms rather than conflicting data. The relevance of these findings for understanding and treating of aggression

  9. Stress accumulated mechanisms on strike-slip faults

    NASA Technical Reports Server (NTRS)

    Turcotte, D. L.

    1980-01-01

    The tectonic framework causing seismicity on the San Andreas and North Anatolian faults can be understood in terms of plate tectonics. However, the mechanisms responsible for the distribution of seismicity in space and time on these faults are poorly understood. The upper part of the crust apparently behaves elastically in storing energy that is released during an earthquake. The relatively small distances from the fault in which stress is stored argue in favor of a plate with a thickness of 5-10 km. The interaction of this plate with a lower crust that is behaving as a fluid damps the seismic cycling in distances of the order of 10 km from the fault. Low measured heat flow also argues in favor of a thin plate with a low stress level on the fault. Future measurements of stress, strain, and heat flow should help to provide a better understanding of the basic mechanisms governing the behavior of strike-slip faults.

  10. Transformations of organic compounds under the action of mechanical stress

    NASA Astrophysics Data System (ADS)

    Dubinskaya, Aleksandra M.

    1999-08-01

    Transformations of organic compounds (monomeric and polymeric) under the action of mechanical stress are considered. Two types of processes occur under these conditions. The first type involves disordering and amorphisation of crystal structure and conformational transformations as a result of rupture of intermolecular bonds. The second type includes mechanochemical reactions activated by deformation of valence bonds and angles under mechanical stress, namely, the rupture of bonds, oxidation and hydrolysis. Data on the organic mechanochemical synthesis of new compounds or molecular complexes are systematised and generalised. It is demonstrated that mechanical treatment ensures mass transfer and the contact of reacting species in these reactions. Proteins are especially sensitive to mechanical stress and undergo denaturation; enzymes are inactivated. The bibliography includes 115 references.

  11. Neurogenetic Approaches to Stress and Fear in Humans as Pathophysiological Mechanisms for Posttraumatic Stress Disorder.

    PubMed

    Nees, Frauke; Witt, Stephanie H; Flor, Herta

    2018-05-15

    In this review article, genetic variation associated with brain responses related to acute and chronic stress reactivity and fear learning in humans is presented as an important mechanism underlying posttraumatic stress disorder. We report that genes related to the regulation of the hypothalamic-pituitary-adrenal axis, as well as genes that modulate serotonergic, dopaminergic, and neuropeptidergic functions or plasticity, play a role in this context. The strong overlap of the genetic targets involved in stress and fear learning suggests that a dimensional and mechanistic model of the development of posttraumatic stress disorder based on these constructs is promising. Genome-wide genetic analyses on fear and stress mechanisms are scarce. So far, reliable replication is still lacking for most of the molecular genetic findings, and the proportion of explained variance is rather small. Further analysis of neurogenetic stress and fear learning needs to integrate data from animal and human studies. Copyright © 2018 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  12. Acquisition of Dynamic Mechanical Analyzer and Stress-Controlled Rheometer for the Mechanical Characterization of Advanced Materials

    DTIC Science & Technology

    2017-06-27

    Distribution Unlimited UU UU UU UU 27-06-2017 1-May-2016 30-Apr-2017 Final Report: Acquisition of Dynamic Mechanical Analyzer and Stress -ControlledRheometer...and Stress -Controlled Rheometer for the Mechanical Characterization of Advanced Materials ARO Grant # W911NF-16-1-0205 K. Wagener (PI) Chemistry

  13. [Oxidative stress in patients on mechanical ventilation].

    PubMed

    Marjanović, Vesna; Dordević, Vidosava; Marjanović, Goran

    2009-01-01

    The appearance and intensity of oxidative stress were analyzed in the course of mechanical ventilation and parameters that could point toward potential lung damage. In three time intervals on day 1, 3 and 7 of mechanical ventilation, parameters such as: triglycerides, cholesterol, lactate, serum lactic dehydrogenase, acid-base balance and lipid peroxidation products--thiobarbituric acid reactive substances, were followed in 30 patients with head injuries. A decrease in the level of partial oxygen pressure (PaO2) (p < 0.01) and PaO2/FiO2 index (p < 0.05) in arterial blood was recorded on day 3 of mechanical ventilation. This was accompanied with an increase in alveolar-arterial difference (AaDO2) (p < 0.05), thiobarbituric acid reactive substances (p < 0.001) and lactic dehydrogenase (p < 0.001) comparing to day 1 of mechanical ventilation. The patients with initial PaO2 > 120 mmHg, had significant increase of thiobarbituric acid reactive substances and AaDO2 (p < 0.05) and fall of PaO2 (p < 0.001) on day 3 of mechanical ventilation. Oxidative stress and lipid peroxide production are increased during third day of mechanical ventilation leading to disruption of oxygen diffusion through alveolar-capillary membrane and reduction of parameters of oxygenation.

  14. Mechanical stress induces lung fibrosis by epithelial-mesenchymal transition.

    PubMed

    Cabrera-Benítez, Nuria E; Parotto, Matteo; Post, Martin; Han, Bing; Spieth, Peter M; Cheng, Wei-Erh; Valladares, Francisco; Villar, Jesús; Liu, Mingayo; Sato, Masaaki; Zhang, Haibo; Slutsky, Arthur S

    2012-02-01

    Many mechanically ventilated patients with acute respiratory distress syndrome develop pulmonary fibrosis. Stresses induced by mechanical ventilation may explain the development of fibrosis by a number of mechanisms (e.g., damage the alveolar epithelium, biotrauma). The objective of this study was t test the hypothesis that mechanical ventilation plays an important role in the pathogenesis of lung fibrosis. C57BL/6 mice were randomized into four groups: healthy controls; hydrochloric acid aspiration alone; vehicle control solution followed 24 hrs later by mechanical ventilation (peak inspiratory pressure 22 cm H(2)O and positive end-expiratory pressure 2 cm H(2)O for 2 hrs); and acid aspiration followed 24 hrs later by mechanical ventilation. The animals were monitored for up to 15 days after acid aspiration. To explore the direct effects of mechanical stress on lung fibrotic formation, human lung epithelial cells (BEAS-2B) were exposed to mechanical stretch for up to 48 hrs. Impaired lung mechanics after mechanical ventilation was associated with increased lung hydroxyproline content, and increased expression of transforming growth factor-β, β-catenin, and mesenchymal markers (α-smooth muscle actin and vimentin) at both the gene and protein levels. Expression of epithelial markers including cytokeratin-8, E-cadherin, and prosurfactant protein B decreased. Lung histology demonstrated fibrosis formation and potential epithelia-mesenchymal transition. In vitro direct mechanical stretch of BEAS-2B cells resulted in similar fibrotic and epithelia-mesenchymal transition formation. Mechanical stress induces lung fibrosis, and epithelia-mesenchymal transition may play an important role in mediating the ventilator-induced lung fibrosis.

  15. Cell wall pectic arabinans influence the mechanical properties of Arabidopsis thaliana inflorescence stems and their response to mechanical stress.

    PubMed

    Verhertbruggen, Yves; Marcus, Susan E; Chen, Jianshe; Knox, J Paul

    2013-08-01

    Little is known of the dynamics of plant cell wall matrix polysaccharides in response to the impact of mechanical stress on plant organs. The capacity of the imposition of a mechanical stress (periodic brushing) to reduce the height of the inflorescence stem of Arabidopsis thaliana seedlings has been used to study the role of pectic arabinans in the mechanical properties and stress responsiveness of a plant organ. The arabinan-deficient-1 (arad1) mutation that affects arabinan structures in epidermal cell walls of inflorescence stems is demonstrated to reduce the impact on inflorescence stem heights caused by mechanical stress. The arabinan-deficient-2 (arad2) mutation, that does not have detectable impact on arabinan structures, is also shown to reduce the impact on stem heights caused by mechanical stress. The LM13 linear arabinan epitope is specifically detected in epidermal cell walls of the younger, flexible regions of inflorescence stems and increases in abundance at the base of inflorescence stems in response to an imposed mechanical stress. The strain (percentage deformation) of stem epidermal cells in the double mutant arad1 × arad2 is lower in unbrushed plants than in wild-type plants, but rises to wild-type levels in response to brushing. The study demonstrates the complexity of arabinan structures within plant cell walls and also that their contribution to cell wall mechanical properties is a factor influencing responsiveness to mechanical stress.

  16. Mechanics of couple-stress fluid coatings

    NASA Technical Reports Server (NTRS)

    Waxman, A. M.

    1982-01-01

    The formal development of a theory of viscoelastic surface fluids with bending resistance - their kinematics, dynamics, and rheology are discussed. It is relevant to the mechanics of fluid drops and jets coated by a thin layer of immiscible fluid with rather general rheology. This approach unifies the hydrodynamics of two-dimensional fluids with the mechanics of an elastic shell in the spirit of a Cosserat continuum. There are three distinct facets to the formulation of surface continuum mechanics. Outlined are the important ideas and results associated with each: the kinematics of evolving surface geometries, the conservation laws governing the mechanics of surface continua, and the rheological equations of state governing the surface stress and moment tensors.

  17. Achieving reversibility of ultra-high mechanical stress by hydrogen loading of thin films

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hamm, M.; Burlaka, V.; Wagner, S.

    2015-06-15

    Nano-materials are commonly stabilized by supports to maintain their desired shape and size. When these nano-materials take up interstitial atoms, this attachment to the support induces mechanical stresses. These stresses can be high when the support is rigid. High stress in the nano-material is typically released by delamination from the support or by the generation of defects, e.g., dislocations. As high mechanical stress can be beneficial for tuning the nano-materials properties, it is of general interest to deduce how real high mechanical stress can be gained. Here, we show that below a threshold nano-material size, dislocation formation can be completelymore » suppressed and, when delamination is inhibited, even the ultrahigh stress values of the linear elastic limit can be reached. Specifically, for hydrogen solved in epitaxial niobium films on sapphire substrate supports a threshold film thickness of 6 nm was found and mechanical stress of up to (−10 ± 1) GPa was reached. This finding is of basic interest for hydrogen energy applications, as the hydride stability in metals itself is affected by mechanical stress. Thus, tuning of the mechanical stress-state in nano-materials may lead to improved storage properties of nano-sized materials.« less

  18. Achieving reversibility of ultra-high mechanical stress by hydrogen loading of thin films

    NASA Astrophysics Data System (ADS)

    Hamm, M.; Burlaka, V.; Wagner, S.; Pundt, A.

    2015-06-01

    Nano-materials are commonly stabilized by supports to maintain their desired shape and size. When these nano-materials take up interstitial atoms, this attachment to the support induces mechanical stresses. These stresses can be high when the support is rigid. High stress in the nano-material is typically released by delamination from the support or by the generation of defects, e.g., dislocations. As high mechanical stress can be beneficial for tuning the nano-materials properties, it is of general interest to deduce how real high mechanical stress can be gained. Here, we show that below a threshold nano-material size, dislocation formation can be completely suppressed and, when delamination is inhibited, even the ultrahigh stress values of the linear elastic limit can be reached. Specifically, for hydrogen solved in epitaxial niobium films on sapphire substrate supports a threshold film thickness of 6 nm was found and mechanical stress of up to (-10 ± 1) GPa was reached. This finding is of basic interest for hydrogen energy applications, as the hydride stability in metals itself is affected by mechanical stress. Thus, tuning of the mechanical stress-state in nano-materials may lead to improved storage properties of nano-sized materials.

  19. Mechanical stress-controlled tunable active frequency-selective surface

    NASA Astrophysics Data System (ADS)

    Huang, Bo-Cin; Hong, Jian-Wei; Lo, Cheng-Yao

    2017-01-01

    This study proposes a tunable active frequency-selective surface (AFSS) realized by mechanically expanding or contracting a split-ring resonator (SRR) array. The proposed AFSS transfers mechanical stress from its elastic substrate to the top of the SRR, thereby achieving electromagnetic (EM) modulation without the need for an additional external power supply, meeting the requirements for the target application: the invisibility cloak. The operating mechanism of the proposed AFSS differs from those of other AFSSs, supporting modulations in arbitrary frequencies in the target range. The proposed stress-controlled or strain-induced EM modulation proves the existence of an identical and linear relationship between the strain gradient and the frequency shift, implying its suitability for other EM modulation ranges and applications.

  20. Intraplate Stress Field in South America Derived from Earthquake Focal Mechanisms

    NASA Astrophysics Data System (ADS)

    Dias, F. L.; Assumpcao, M.

    2017-12-01

    We present an updated compilation of earthquake focal mechanisms in Brazil together with the sub-Andean region through more obtained solutions together with published results from the literature and catalogs of international agencies. Stress orientations from breakouts and in-situ measurements were also compiled. The focal mechanisms were classified according to WSM (World Stress Map) criteria.For Brazil, we have 82 earthquakes with the mechanism that has been determined since 1978, begin that three new from this study. Focal mechanisms in Brazil show reverse, strike-slip and normal faulting while all events in the sub-Andean region have reverse (majority) or strike-slip mechanisms. For sub-Andean region have reverse (majority) or strike-slip mechanisms. Normal mechanisms can be found only in high attitudes. The mechanisms were grouped by proximity to be inverted for the stress tensor. We use the bootstrap technique to analyze the stability of the tensor. In SE Brazil and the Chaco-Pantanal basins, S1 tends to be oriented roughly E-W with S2 approximately equal to S3. This stress pattern changes to purely compressional (both SHmax and Shmin larger than Sv) in the São Francisco craton. A rotation of SHmax from E-W to SE-NW is suggested towards the Amazon region. Along the Atlantic margin, the regional stresses are affected by coastal effects. This coastal effect tends to make SHmax parallel to the coastline and Shmin (usually S3) perpendicular to the coastline. Few breakout data and in-situ measurements are available in Brazil and are generally consistent with the pattern derived from the earthquake focal mechanisms. In the sub-Andean region, the intermediate principal stress (S2) is also compressional, a feature that is not always reproduced in numerical models published in the literature. In mid-plate South America stresses seem to vary in nature and orientation. Although numerical models of global lithospheric stresses tend to reproduce the main large

  1. Translocation of TRPV2 channel induced by focal administration of mechanical stress

    PubMed Central

    Nagasawa, Masahiro; Kojima, Itaru

    2015-01-01

    The effect of focal mechanical stress on the localization of TRPV2 was investigated in HT1080 cells, where only mRNA for TRPV2 was detected among members of the TRPV channel family. Mechanical stress was applied by adding negative pressure using a glass pipette. When focal mechanical stress was applied, subplasma membrane Ca2+ concentration ([Ca2+]s) was increased beneath the pipette, which propagated throughout the cell. The increase in [Ca2+]s was blocked by ruthenium red or by knocking down TRPV2. Elevation of [Ca2+]s was not observed by removal of extracellular Ca2+, by an addition of a phosphatidylinositol 3-kinase inhibitor LY29034, and by transfection of dominant-negative Rac. In cells expressing GFP-TRPV2 and RFP-Akt, administration of focal mechanical stress induced accumulation of GFP-TRPV2 beneath the pipette. RFP-Akt was also accumulated to the same site. Gadolinium blocked the elevation of [Ca2+]s induced by focal mechanical stress and also attenuated accumulation of TRPV2. When GFP-TRPV1, GFP-TRPV3, GFP-TRPV4, GFP-TRPV5, or GFP-TRPV6 was transfected ectopically in HT1080 cells, only GFP-TRPV4 was accumulated beneath the pipette in response to the focal mechanical stress. These results indicate that TRPV2 translocates to the site receiving a focal mechanical stress and increases [Ca2+]s. PMID:25677550

  2. TensorCalculator: exploring the evolution of mechanical stress in the CCMV capsid

    NASA Astrophysics Data System (ADS)

    Kononova, Olga; Maksudov, Farkhad; Marx, Kenneth A.; Barsegov, Valeri

    2018-01-01

    A new computational methodology for the accurate numerical calculation of the Cauchy stress tensor, stress invariants, principal stress components, von Mises and Tresca tensors is developed. The methodology is based on the atomic stress approach which permits the calculation of stress tensors, widely used in continuum mechanics modeling of materials properties, using the output from the MD simulations of discrete atomic and C_α -based coarse-grained structural models of biological particles. The methodology mapped into the software package TensorCalculator was successfully applied to the empty cowpea chlorotic mottle virus (CCMV) shell to explore the evolution of mechanical stress in this mechanically-tested specific example of a soft virus capsid. We found an inhomogeneous stress distribution in various portions of the CCMV structure and stress transfer from one portion of the virus structure to another, which also points to the importance of entropic effects, often ignored in finite element analysis and elastic network modeling. We formulate a criterion for elastic deformation using the first principal stress components. Furthermore, we show that von Mises and Tresca stress tensors can be used to predict the onset of a viral capsid’s mechanical failure, which leads to total structural collapse. TensorCalculator can be used to study stress evolution and dynamics of defects in viral capsids and other large-size protein assemblies.

  3. Alterations in myocardial free fatty acid clearance precede mechanical abnormalities in canine tachycardia-induced heart failure.

    PubMed

    Freeman, G L; Colston, J T; Miller, D D

    1994-01-01

    The purpose of this study was to evaluate whether abnormalities of free fatty acid metabolism are present before the onset of overt mechanical dysfunction in dogs with tachycardia-induced heart failure. We studied six dogs chronically instrumented to allow assessment of left ventricular function in the pressure-volume plane. Free fatty acid clearance was assessed according to the washout rate of a free fatty acid analog, iodophenylpentadecanoic acid ([123I]PPA or IPPA). IPPA clearance was measured within 1 hour of the hemodynamic assessment. The animals were studied under baseline conditions and 11.7 +/- 3.6 days after ventricular pacing at a rate of 240 beats/min. Hemodynamic studies after pacing showed a nonsignificant increase in left ventricular end-diastolic pressure (11.7 +/- 4.7 to 17.4 +/- 6.5 mm Hg) and a nonsignificant decrease in the maximum derivative of pressure with respect to time (1836 +/- 164 vs 1688 +/- 422 mm Hg/sec). There was also no change in the time constant of left ventricular relaxation, which was 34.8 +/- 7.67 msec before and 35.3 +/- 7.3 msec after pacing. However, a significant prolongation in the clearance half-time of [123I]PPA, from 86.1 +/- 23.9 to 146.5 +/- 22.6 minutes (p < 0.01) was found. Thus abnormal lipid clearance appears before the onset of significant mechanical dysfunction in tachycardia-induced heart failure. This suggests that abnormal substrate metabolism may play an important role in the pathogenesis of this condition.

  4. Airplane Stress Analysis

    NASA Technical Reports Server (NTRS)

    Zahm, A F; Crook, L H

    1918-01-01

    Report presents stress analysis of individual components of an airplane. Normal and abnormal loads, sudden loads, simple stresses, indirect simple stresses, resultant unit stress, repetitive and equivalent stress, maximum steady load and stress are considered.

  5. Effect of thermal stresses on the mechanism of tooth pain.

    PubMed

    Oskui, Iman Z; Ashtiani, Mohammed N; Hashemi, Ata; Jafarzadeh, Hamid

    2014-11-01

    Daily hot and cold thermal loadings on teeth may result in structural deformation, mechanical stress, and pain signaling. The aim of this study was to compare the adverse effects of hot and cold beverages on an intact tooth and, then, to provide physical evidence to support the hydrodynamic theory of tooth pain sensation mechanism. Three-dimensional finite element analysis was performed on a premolar model subjected to hot and cold thermal loadings. Elapsed times for heat diffusion and stress detection at the pulp-dentin junction were calculated as measures of the pain sensation. Extreme tensile stress within the enamel resulted in damage in cold loadings. Also, extreme values of stress at the pulpal wall occurred 21.6 seconds earlier than extreme temperatures in hot and cold loadings. The intact tooth was remarkably vulnerable to cold loading. Earlier changes in mechanical stress rather than temperature at the pulp-dentin junction indicate that the dental pain caused by hot or cold beverages may be based on the hydrodynamic theory. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  6. Neural mechanisms of oculomotor abnormalities in the infantile strabismus syndrome.

    PubMed

    Walton, Mark M G; Pallus, Adam; Fleuriet, Jérome; Mustari, Michael J; Tarczy-Hornoch, Kristina

    2017-07-01

    Infantile strabismus is characterized by numerous visual and oculomotor abnormalities. Recently nonhuman primate models of infantile strabismus have been established, with characteristics that closely match those observed in human patients. This has made it possible to study the neural basis for visual and oculomotor symptoms in infantile strabismus. In this review, we consider the available evidence for neural abnormalities in structures related to oculomotor pathways ranging from visual cortex to oculomotor nuclei. These studies provide compelling evidence that a disturbance of binocular vision during a sensitive period early in life, whatever the cause, results in a cascade of abnormalities through numerous brain areas involved in visual functions and eye movements. Copyright © 2017 the American Physiological Society.

  7. Mechanic stress generated by a time-varying electromagnetic field on bone surface.

    PubMed

    Ye, Hui

    2018-03-19

    Bone cells sense mechanical load, which is essential for bone growth and remodeling. In a fracture, this mechanism is compromised. Electromagnetic stimulation has been widely used to assist in bone healing, but the underlying mechanisms are largely unknown. A recent hypothesis suggests that electromagnetic stimulation could influence tissue biomechanics; however, a detailed quantitative understanding of EM-induced biomechanical changes in the bone is unavailable. This paper used a muscle/bone model to study the biomechanics of the bone under EM exposure. Due to the dielectric properties of the muscle/bone interface, a time-varying magnetic field can generate both compressing and shear stresses on the bone surface, where many mechanical sensing cells are available for cellular mechanotransduction. I calculated these stresses and found that the shear stress is significantly greater than the compressing stress. Detailed parametric analysis suggests that both the compressing and shear stresses are dependent on the geometrical and electrical properties of the muscle and the bone. These stresses are also functions of the orientation of the coil and the frequency of the magnetic field. It is speculated that the EM field could apply biomechanical influence to fractured bone, through the fine-tuning of the controllable field parameters. Graphical abstract Mechanic stress on bone surface in a time-varying magnetic field.

  8. Abnormal cation transport in uremia. Mechanisms in adipocytes and skeletal muscle from uremic rats.

    PubMed

    Druml, W; Kelly, R A; May, R C; Mitch, W E

    1988-04-01

    The cause of the abnormal active cation transport in erythrocytes of some uremic patients is unknown. In isolated adipocytes and skeletal muscle from chronically uremic chronic renal failure rats, basal sodium pump activity was decreased by 36 and 30%, and intracellular sodium was increased by 90 and 50%, respectively, compared with pair-fed control rats; insulin-stimulated sodium pump activity was preserved in both tissues. Lower basal NaK-ATPase activity in adipocytes was due to a proportionate decline in [3H]ouabain binding, while in muscle, [3H]ouabain binding was not changed, indicating that the NaK-ATPase turnover rate was decreased. Normal muscle, but not normal adipocytes, acquired defective Na pump activity when incubated in uremic sera. Thus, the mechanism for defective active cation transport in CRF is multifactorial and tissue specific. Sodium-dependent amino acid transport in adipocytes closely paralleled diminished Na pump activity (r = 0.91), indicating the importance of this defect to abnormal cellular metabolism in uremia.

  9. Abnormal cation transport in uremia. Mechanisms in adipocytes and skeletal muscle from uremic rats.

    PubMed Central

    Druml, W; Kelly, R A; May, R C; Mitch, W E

    1988-01-01

    The cause of the abnormal active cation transport in erythrocytes of some uremic patients is unknown. In isolated adipocytes and skeletal muscle from chronically uremic chronic renal failure rats, basal sodium pump activity was decreased by 36 and 30%, and intracellular sodium was increased by 90 and 50%, respectively, compared with pair-fed control rats; insulin-stimulated sodium pump activity was preserved in both tissues. Lower basal NaK-ATPase activity in adipocytes was due to a proportionate decline in [3H]ouabain binding, while in muscle, [3H]ouabain binding was not changed, indicating that the NaK-ATPase turnover rate was decreased. Normal muscle, but not normal adipocytes, acquired defective Na pump activity when incubated in uremic sera. Thus, the mechanism for defective active cation transport in CRF is multifactorial and tissue specific. Sodium-dependent amino acid transport in adipocytes closely paralleled diminished Na pump activity (r = 0.91), indicating the importance of this defect to abnormal cellular metabolism in uremia. PMID:2832446

  10. Translocation of TRPV2 channel induced by focal administration of mechanical stress.

    PubMed

    Nagasawa, Masahiro; Kojima, Itaru

    2015-02-01

    The effect of focal mechanical stress on the localization of TRPV2 was investigated in HT1080 cells, where only mRNA for TRPV2 was detected among members of the TRPV channel family. Mechanical stress was applied by adding negative pressure using a glass pipette. When focal mechanical stress was applied, subplasma membrane Ca(2+) concentration ([Ca(2+)]s) was increased beneath the pipette, which propagated throughout the cell. The increase in [Ca(2+)]s was blocked by ruthenium red or by knocking down TRPV2. Elevation of [Ca(2+)]s was not observed by removal of extracellular Ca(2+), by an addition of a phosphatidylinositol 3-kinase inhibitor LY29034, and by transfection of dominant-negative Rac. In cells expressing GFP-TRPV2 and RFP-Akt, administration of focal mechanical stress induced accumulation of GFP-TRPV2 beneath the pipette. RFP-Akt was also accumulated to the same site. Gadolinium blocked the elevation of [Ca(2+)]s induced by focal mechanical stress and also attenuated accumulation of TRPV2. When GFP-TRPV1, GFP-TRPV3, GFP-TRPV4, GFP-TRPV5, or GFP-TRPV6 was transfected ectopically in HT1080 cells, only GFP-TRPV4 was accumulated beneath the pipette in response to the focal mechanical stress. These results indicate that TRPV2 translocates to the site receiving a focal mechanical stress and increases [Ca(2+)]s. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

  11. Oxidative stress and successful antioxidant treatment in models of RYR1-related myopathy

    PubMed Central

    Arbogast, Sandrine; Hur, Junguk; Nelson, Darcee D.; McEvoy, Anna; Waugh, Trent; Marty, Isabelle; Lunardi, Joel; Brooks, Susan V.; Kuwada, John Y.; Ferreiro, Ana

    2012-01-01

    The skeletal muscle ryanodine receptor is an essential component of the excitation–contraction coupling apparatus. Mutations in RYR1 are associated with several congenital myopathies (termed RYR1-related myopathies) that are the most common non-dystrophic muscle diseases of childhood. Currently, no treatments exist for these disorders. Although the primary pathogenic abnormality involves defective excitation–contraction coupling, other abnormalities likely play a role in disease pathogenesis. In an effort to discover novel pathogenic mechanisms, we analysed two complementary models of RYR1-related myopathies, the relatively relaxed zebrafish and cultured myotubes from patients with RYR1-related myopathies. Expression array analysis in the zebrafish disclosed significant abnormalities in pathways associated with cellular stress. Subsequent studies focused on oxidative stress in relatively relaxed zebrafish and RYR1-related myopathy myotubes and demonstrated increased oxidant activity, the presence of oxidative stress markers, excessive production of oxidants by mitochondria and diminished survival under oxidant conditions. Exposure to the antioxidant N-acetylcysteine reduced oxidative stress and improved survival in the RYR1-related myopathies human myotubes ex vivo and led to significant restoration of aspects of muscle function in the relatively relaxed zebrafish, thereby confirming its efficacy in vivo. We conclude that oxidative stress is an important pathophysiological mechanism in RYR1-related myopathies and that N-acetylcysteine is a successful treatment modality ex vivo and in a vertebrate disease model. We propose that N-acetylcysteine represents the first potential therapeutic strategy for these debilitating muscle diseases. PMID:22418739

  12. Mechanical Stress Measurement During Thin-Film Fabrication

    NASA Technical Reports Server (NTRS)

    Broadway, David M. (Inventor)

    2017-01-01

    A method and system are provided for determining mechanical stress experienced by a film during fabrication thereof on a substrate positioned in a vacuum deposition chamber. The substrate's first surface is disposed to have the film deposited thereon and the substrate's opposing second surface is a specular reflective surface. A portion of the substrate is supported. An optical displacement sensor is positioned in the vacuum deposition chamber in a spaced-apart relationship with respect to a portion of the substrate's second surface. During film deposition on the substrate's first surface, displacement of the portion of the substrate's second surface is measured using the optical displacement sensor. The measured displacement is indicative of a radius of curvature of the substrate, and the radius of curvature is indicative of mechanical stress being experienced by the film.

  13. Mechanical stresses and amorphization of ion-implanted diamond

    NASA Astrophysics Data System (ADS)

    Khmelnitsky, R. A.; Dravin, V. A.; Tal, A. A.; Latushko, M. I.; Khomich, A. A.; Khomich, A. V.; Trushin, A. S.; Alekseev, A. A.; Terentiev, S. A.

    2013-06-01

    Scanning white light interferometry and Raman spectroscopy were used to investigate the mechanical stresses and structural changes in ion-implanted natural diamonds with different impurity content. The uniform distribution of radiation defects in implanted area was obtained by the regime of multiple-energy implantation of keV He+ ions. A modification of Bosia's et al. (Nucl. Instrum. Meth. B 268 (2010) 2991) method for determining the internal stresses and the density variation in an ion-implanted diamond layer was proposed that suggests measuring, in addition to the surface swelling of a diamond plate, the radius of curvature of the plate. It is shown that, under multiple-energy implantation of He+, mechanical stresses in the implanted layer may be as high as 12 GPa. It is shown that radiation damage reaches saturation for the implantation fluence characteristic of amorphization of diamond but is appreciably lower than the graphitization threshold.

  14. Mechanical and electromagnetic induction of protection against oxidative stress.

    PubMed

    Di Carlo, A L; White, N C; Litovitz, T A

    2001-01-01

    Cells and tissues can be protected against a potentially lethal stress by first exposing them to a brief dose of the same or different stress. This "pre-conditioning" phenomenon has been documented in many models of protection against oxidative stress, including ischemia/reperfusion and ultraviolet (UV) light exposure. Stimuli which induce this protective response include heat, chemicals, brief ischemia, and electromagnetic (EM) field exposures. We report here that constant mechanical vibration pre-conditions chick embryos, protecting them during subsequent stress from hypoxia or UV light exposure. Continuously mechanically vibrated embryos (60 Hz, 1 g (32 ft/s2), 20 min) exhibited nearly double the survival (67.5%, P < 0.001) after subsequent hypoxia as compared to non-vibrated controls (37.6%). As a second set of experiments, embryos were vibrated and then exposed to UV light stress. Those embryos that were vibrated prior to UV had nearly double the survival 3 h after UV exposure (66%, P < 0.001) as compared to controls (35%). The degree of protection, however, was dependent on the constancy of the vibration amplitude. When vibration was turned on and off at 1-s intervals throughout exposure, no increase in hypoxia protection was noted. For 50 s on/off vibration intervals, however, hypoxia protection comparable to continuous vibration was obtained. In contrast, random, inconstant mechanical vibration did not induce protection against subsequent UV exposure. These data suggest that to be an effective pre-conditioning agent, mechanical vibration must have a degree of temporally constancy (on/off intervals of greater than 1 s). Further experiments in both models (hypoxia and UV) indicated an interaction between vibration and EM field-induced protection. Vibration-induced hypoxia protection was inhibited by superposition of a random EM noise field (previously shown to inhibit EM field-induced protection). In addition, EM field-induced UV protection was inhibited by

  15. Critical review on the mechanisms of maturation stress generation in trees.

    PubMed

    Alméras, Tancrède; Clair, Bruno

    2016-09-01

    Trees control their posture by generating asymmetric mechanical stress around the periphery of the trunk or branches. This stress is produced in wood during the maturation of the cell wall. When the need for reaction is high, it is accompanied by strong changes in cell organization and composition called reaction wood, namely compression wood in gymnosperms and tension wood in angiosperms. The process by which stress is generated in the cell wall during its formation is not yet known, and various hypothetical mechanisms have been proposed in the literature. Here we aim at discriminating between these models. First, we summarize current knowledge about reaction wood structure, state and behaviour relevant to the understanding of maturation stress generation. Then, the mechanisms proposed in the literature are listed and discussed in order to identify which can be rejected based on their inconsistency with current knowledge at the frontier between plant science and mechanical engineering. © 2016 The Author(s).

  16. Critical review on the mechanisms of maturation stress generation in trees

    PubMed Central

    Clair, Bruno

    2016-01-01

    Trees control their posture by generating asymmetric mechanical stress around the periphery of the trunk or branches. This stress is produced in wood during the maturation of the cell wall. When the need for reaction is high, it is accompanied by strong changes in cell organization and composition called reaction wood, namely compression wood in gymnosperms and tension wood in angiosperms. The process by which stress is generated in the cell wall during its formation is not yet known, and various hypothetical mechanisms have been proposed in the literature. Here we aim at discriminating between these models. First, we summarize current knowledge about reaction wood structure, state and behaviour relevant to the understanding of maturation stress generation. Then, the mechanisms proposed in the literature are listed and discussed in order to identify which can be rejected based on their inconsistency with current knowledge at the frontier between plant science and mechanical engineering. PMID:27605169

  17. Work related stress and coping mechanisms among bankers in Lagos, Nigeria.

    PubMed

    Olatona, F A; Ezeobika, E N; Okafor, I P; Owoeye, O B A

    2014-03-01

    This study assessed knowledge, prevalence, associated factors and mechanisms of coping with stress among bankers in Lagos State. It was a descriptive cross sectional study. A two stage sampling technique was used to select two hundred and twenty seven (227) respondents. Data was collected using a structured self administered questionnaire. The analysis was done using Epi-info version 2002 software and Chi Square was used to determine association between variables at p value 0.05. Fischer's Exact test was used where Chi-square was not valid. The age range of respondents was between 20 and 49 years while the mean age was 31.3 +/- 5.0 years. Only 3.6% had good level of knowledge about stress, 42.2% had fair level while more than half of the respondents had poor level of knowledge about stress (54.3%). Majority (67.0%) of the respondents were moderately stressed while one quarter (24.7%) were highly stressed. Majority (92.4%) of the respondents used good coping mechanisms though 69.5% of the respondents also used bad coping mechanisms. A greater proportion of those who had poor knowledge about stress were stressed or highly stressed (p = 0.002). A statistically significant association was also found between the departments in the bank and level of stress of the respondents (p = 0.002). The prevalence of stress was high among the bank workers studied. It is recommended that effective stress management programmes are implemented to address the problem of stress among bank workers.

  18. β1 subunit stabilises sodium channel Nav1.7 against mechanical stress.

    PubMed

    Körner, Jannis; Meents, Jannis; Machtens, Jan-Philipp; Lampert, Angelika

    2018-06-01

    The voltage-gated sodium channel Nav1.7 is a key player in neuronal excitability and pain signalling. In addition to voltage sensing, the channel is also modulated by mechanical stress. Using whole-cell patch-clamp experiments, we discovered that the sodium channel subunit β1 is able to prevent the impact of mechanical stress on Nav1.7. An intramolecular disulfide bond of β1 was identified to be essential for stabilisation of inactivation, but not activation, against mechanical stress using molecular dynamics simulations, homology modelling and site-directed mutagenesis. Our results highlight the role of segment 6 of domain IV in fast inactivation. We present a candidate mechanism for sodium channel stabilisation against mechanical stress, ensuring reliable channel functionality in living systems. Voltage-gated sodium channels are key players in neuronal excitability and pain signalling. Precise gating of these channels is crucial as even small functional alterations can lead to pathological phenotypes such as pain or heart failure. Mechanical stress has been shown to affect sodium channel activation and inactivation. This suggests that stabilising components are necessary to ensure precise channel gating in living organisms. Here, we show that mechanical shear stress affects voltage dependence of activation and fast inactivation of the Nav1.7 channel. Co-expression of the β1 subunit, however, protects both gating modes of Nav1.7 against mechanical shear stress. Using molecular dynamics simulation, homology modelling and site-directed mutagenesis, we identify an intramolecular disulfide bond of β1 (Cys21-Cys43) which is partially involved in this process: the β1-C43A mutant prevents mechanical modulation of voltage dependence of activation, but not of fast inactivation. Our data emphasise the unique role of segment 6 of domain IV for sodium channel fast inactivation and confirm previous reports that the intracellular process of fast inactivation can be

  19. Neuroimmune mechanisms of stress: sex differences, developmental plasticity, and implications for pharmacotherapy of stress-related disease

    PubMed Central

    Deak, Terrence; Quinn, Matt; Cidlowski, John A.; Victoria, Nicole C.; Murphy, Anne Z.; Sheridan, John F.

    2016-01-01

    The last decade has witnessed profound growth in studies examining the role of fundamental neuroimmune processes as key mechanisms that might form a natural bridge between normal physiology and pathological outcomes. Rooted in core concepts from psychoneuroimmunology, this review utilizes a succinct, exemplar-driven approach of several model systems that contribute significantly to our knowledge of the mechanisms by which neuroimmune processes interact with stress physiology. Specifically, we review recent evidence showing that (i) stress challenges produce time-dependent and stressor-specific patterns of cytokine/chemokine expression in the CNS; (ii) inflammation-related genes exhibit unique expression profiles in males and females depending upon individual, cooperative, or antagonistic interactions between steroid hormone receptors (Estrogen and Glucocorticoid receptors); (iii) adverse social experiences incurred through repeated social defeat engage a dynamic process of immune cell migration from the bone marrow to brain and prime neuroimmune function; and (iv) early developmental exposure to an inflammatory stimulus (carageenin injection into the hindpaw) has a lasting influence on stress reactivity across the lifespan. As such, the present review provides a theoretical framework for understanding the role that neuroimmune mechanisms might play in stress plasticity and pathological outcomes, while at the same time pointing toward features of the individual (sex, developmental experience, stress history) that might ultimately be used for the development of personalized strategies for therapeutic intervention in stress-related pathologies. PMID:26176590

  20. Neuroimmune mechanisms of stress: sex differences, developmental plasticity, and implications for pharmacotherapy of stress-related disease.

    PubMed

    Deak, Terrence; Quinn, Matt; Cidlowski, John A; Victoria, Nicole C; Murphy, Anne Z; Sheridan, John F

    2015-01-01

    The last decade has witnessed profound growth in studies examining the role of fundamental neuroimmune processes as key mechanisms that might form a natural bridge between normal physiology and pathological outcomes. Rooted in core concepts from psychoneuroimmunology, this review utilizes a succinct, exemplar-driven approach of several model systems that contribute significantly to our knowledge of the mechanisms by which neuroimmune processes interact with stress physiology. Specifically, we review recent evidence showing that (i) stress challenges produce time-dependent and stressor-specific patterns of cytokine/chemokine expression in the CNS; (ii) inflammation-related genes exhibit unique expression profiles in males and females depending upon individual, cooperative or antagonistic interactions between steroid hormone receptors (estrogen and glucocorticoid receptors); (iii) adverse social experiences incurred through repeated social defeat engage a dynamic process of immune cell migration from the bone marrow to brain and prime neuroimmune function and (iv) early developmental exposure to an inflammatory stimulus (carageenin injection into the hindpaw) has a lasting influence on stress reactivity across the lifespan. As such, the present review provides a theoretical framework for understanding the role that neuroimmune mechanisms might play in stress plasticity and pathological outcomes, while at the same time pointing toward features of the individual (sex, developmental experience, stress history) that might ultimately be used for the development of personalized strategies for therapeutic intervention in stress-related pathologies.

  1. Epigenetic and chromatin-based mechanisms in environmental stress adaptation and stress memory in plants.

    PubMed

    Lämke, Jörn; Bäurle, Isabel

    2017-06-27

    Plants frequently have to weather both biotic and abiotic stressors, and have evolved sophisticated adaptation and defense mechanisms. In recent years, chromatin modifications, nucleosome positioning, and DNA methylation have been recognized as important components in these adaptations. Given their potential epigenetic nature, such modifications may provide a mechanistic basis for a stress memory, enabling plants to respond more efficiently to recurring stress or even to prepare their offspring for potential future assaults. In this review, we discuss both the involvement of chromatin in stress responses and the current evidence on somatic, intergenerational, and transgenerational stress memory.

  2. Prenatal ethanol exposure-induced adrenal developmental abnormality of male offspring rats and its possible intrauterine programming mechanisms

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Huang, Hegui; He, Zheng; Zhu, Chunyan

    Fetal adrenal developmental status is the major determinant of fetal tissue maturation and offspring growth. We have previously proposed that prenatal ethanol exposure (PEE) suppresses fetal adrenal corticosterone (CORT) synthesis. Here, we focused on PEE-induced adrenal developmental abnormalities of male offspring rats before and after birth, and aimed to explore its intrauterine programming mechanisms. A rat model of intrauterine growth retardation (IUGR) was established by PEE (4 g/kg·d). In PEE fetus, increased serum CORT concentration and decreased insulin-like growth factor 1 (IGF1) concentration, with lower bodyweight and structural abnormalities as well as a decreased Ki67 expression (proliferative marker), were observedmore » in the male fetal adrenal cortex. Adrenal glucocorticoid (GC)-metabolic activation system was enhanced while gene expression of IGF1 signaling pathway with steroidogenic acute regulatory protein (StAR), 3β-hydroxysteroid dehydrogenase (3β-HSD) was decreased. Furthermore, in the male adult offspring of PEE, serum CORT level was decreased but IGF1 was increased with partial catch-up growth, and Ki67 expression demonstrated no obvious change. Adrenal GC-metabolic activation system was inhibited, while IGF1 signaling pathway and 3β-HSD was enhanced with the steroidogenic factor 1 (SF1), and StAR was down-regulated in the adult adrenal. Based on these findings, we propose a “two-programming” mechanism for PEE-induced adrenal developmental toxicity: “the first programming” is a lower functional programming of adrenal steroidogenesis, and “the second programming” is GC-metabolic activation system-related GC-IGF1 axis programming. - Highlights: • Prenatal ethanol exposure induces adrenal developmental abnormality in offspring rats. • Prenatal ethanol exposure induces intrauterine programming of adrenal steroidogenesis. • Intrauterine GC-IGF1 axis programming might mediate adrenal developmental abnormality.« less

  3. A neural hypothesis for stress-induced headache.

    PubMed

    Cathcart, Stuart

    2009-12-01

    The mechanisms by which stress contributes to CTH are not clearly understood. The commonly accepted notion of muscle hyper-reactivity to stress in CTH sufferers is not supported in the research data. We propose a neural model whereby stress acts supra-spinally to aggravate already increased pain sensitivity in CTH sufferers. Indirect support for the model comes from emerging research elucidating complex supra-spinal networks through which psychological stress may contribute to and even cause pain. Similarly, emerging research demonstrates supra-spinal pain processing abnormalities in CTH sufferers. While research with CTH sufferers offering direct support for the model is lacking at present, initial work by our group is consistent with the models predictions, particularly, that stress aggravates already increased pain sensitivity in CTH sufferers.

  4. Mechanism for amorphization of boron carbide under complex stress conditions

    NASA Astrophysics Data System (ADS)

    Li, Jun; Xu, Shuang; Liu, Lisheng; Wang, Zhen; Zhang, Jinyong; Liu, Qiwen

    2018-05-01

    As an excellent material, the application of boron carbide (B4C) is limited by pressure-induced amorphization. To understand the mechanism for amorphization in B4C, first-principles methods based on density functional theory were employed to investigate the mechanical behaviors and the deformation process in B4C under complex stress conditions with six different biaxial perpendicular compression directions. The angle (θ) between one of the loading directions and the [0 0 0 1] c-axis ranged from 0° to 75° with every 15° interval. We found that the maximum stress at θ = 30° is 124.5 GPa, which is the lowest among six biaxial compressions. Simulation results show that the mechanism for amorphization in B4C under complex stress conditions is complicated. We take the θ = 30° biaxial compression as an example to explain the complicated deformation process. In the elastic deformation region, sudden bending of three-atom chains occurs and results in a stress fluctuation. Then the formation of new B–B bonds between the three-atom chains and the icosahedra leads to the first stress drop. After that, the B–C bonds in the chains are broken, resulting in the second stress drop. In this process, the icosahedra are partially destroyed. The stress increases continuously and then drops at the critical failure strain. Finally, the fully destruction of icosahedra leads to amorphization in B4C. However, under other five biaxial compressions, the B–C bonds in three-atom chains are not fractured before structural failure. Understanding the deformation mechanism for amorphization of B4C in real applications is prime important for proposing how to resist amorphization and enhance the toughness of B4C.

  5. Investigating Resulting Residual Stresses during Mechanical Forming Process

    NASA Astrophysics Data System (ADS)

    Akinlabi, Stephen A.; Fatoba, Olawale S.; Mashinini, Peter M.; Akinlabi, Esther T.

    2018-03-01

    Most manufacturing processes such as machining, welding, heat treatment, laser forming, laser cladding and, laser metal deposition, etc. are subjected to a form of heat or energy to change the geometrical shape thus changing the inherent engineering and structural properties of the material. These changes often cause the development of locked up stresses referred to as residual stresses as a result of these activities. This study reports on the residual stresses developed due to the mechanical forming process to maintain a suitable structural integrity for the formed components. The result of the analysis through the X-ray diffraction confirmed that residual stresses were induced in the manufactured parts and further revealed that residual stresses were compressive in nature as found in the parent material but with values less than the parent material.

  6. Accuracy of pulmonary auscultation to detect abnormal respiratory mechanics: a cross-sectional diagnostic study.

    PubMed

    Xavier, Glaciele Nascimento; Duarte, Antonio Carlos Magalhães; Melo-Silva, César Augusto; dos Santos, Carlos Eduardo Ventura Gaio; Amado, Veronica Moreira

    2014-12-01

    Pulmonary auscultation is a method used in clinical practice for the evaluation and detection of abnormalities relating to the respiratory system. This method has limitations, as it depends on the experience and hearing acuity of the examiner to determine adventitious sounds. In this context, it's important to analyze whether there is a correlation between auscultation of lung sounds and the behavior of the respiratory mechanical properties of the respiratory system in patients with immediate postoperative cardiac surgery. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Heat stress protects against mechanical ventilation-induced diaphragmatic atrophy.

    PubMed

    Ichinoseki-Sekine, Noriko; Yoshihara, Toshinori; Kakigi, Ryo; Sugiura, Takao; Powers, Scott K; Naito, Hisashi

    2014-09-01

    Mechanical ventilation (MV) is a life-saving intervention in patients who are incapable of maintaining adequate pulmonary gas exchange due to respiratory failure or other disorders. However, prolonged MV is associated with the development of respiratory muscle weakness. We hypothesized that a single exposure to whole body heat stress would increase diaphragm expression of heat shock protein 72 (HSP72) and that this treatment would protect against MV-induced diaphragmatic atrophy. Adult male Wistar rats (n = 38) were randomly assigned to one of four groups: an acutely anesthetized control group (CON) with no MV; 12-h controlled MV group (CMV); 1-h whole body heat stress (HS); or 1-h whole body heat stress 24 h prior to 12-h controlled MV (HSMV). Compared with CON animals, diaphragmatic HSP72 expression increased significantly in the HS and HSMV groups (P < 0.05). Prolonged MV resulted in significant atrophy of type I, type IIa, and type IIx fibers in the costal diaphragm (P < 0.05). Whole body heat stress attenuated this effect. In contrast, heat stress did not protect against MV-induced diaphragm contractile dysfunction. The mechanisms responsible for this heat stress-induced protection remain unclear but may be linked to increased expression of HSP72 in the diaphragm. Copyright © 2014 the American Physiological Society.

  8. Transient abnormal Q waves during exercise electrocardiography

    PubMed Central

    Alameddine, F F; Zafari, A M

    2004-01-01

    Myocardial ischaemia during exercise electrocardiography is usually manifested by ST segment depression or elevation. Transient abnormal Q waves are rare, as Q waves indicate an old myocardial infarction. The case of a patient with exercise induced transient abnormal Q waves is reported. The potential mechanisms involved in the development of such an abnormality and its clinical implications are discussed. PMID:14676264

  9. Sex-specific mechanisms for responding to stress.

    PubMed

    Bangasser, Debra A; Wicks, Brittany

    2017-01-02

    Posttraumatic stress disorder and major depression share stress as an etiological contributor and are more common in women than in men. Traditionally, preclinical studies investigating the neurobiological underpinnings of stress vulnerability have used only male rodents; however, recent studies that include females are finding sex-specific mechanisms for responding to stress. This Mini-Review examines recent literature using a framework developed by McCarthy and colleagues (2012; J Neurosci 32:2241-2247) that highlights different types of sex differences. First, we detail how learned fear responses in rats are sexually dimorphic. Then, we contrast this finding with fear extinction, which is similar in males and females at the behavioral level but at the circuitry level is associated with sex-specific cellular changes and, thus, exemplifies a sex convergence. Next, sex differences in stress hormones are detailed. Finally, the effects of stress on learning, attention, and arousal are used to highlight the concept of a sex divergence in which the behavior of males and females is similar at baseline but diverges following stressor exposure. We argue that appreciating and investigating the diversity of sex differences in stress response systems will improve our understanding of vulnerability and resilience to stress-related psychiatric disorders and likely lead to the development of novel therapeutics for better treatment of these disorders in both men and women. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  10. The relationship of abnormal foot pronation to hallux abducto valgus--a pilot study.

    PubMed

    Ross, F D

    1986-08-01

    Abnormal foot mechanics is the most common cause of hallux abducto valgus. To date no quantitative data regarding the relationship between abnormal foot mechanics and the degree of hallux abducto valgus has been presented. An outline of the abnormal foot mechanics responsible for hallux abducto valgus is described along with a technique for measuring the extent of abnormal function. A common intrinsic abnormality responsible for hallux abducto valgus is described along with its diagnosis and orthotic treatment.

  11. Stress tensor and focal mechanisms in the Dead Sea basin

    NASA Astrophysics Data System (ADS)

    Hofstetter, A.; Dorbath, C.; Dorbath, L.; Braeuer, B.; Weber, M. H.

    2015-12-01

    We use the recorded seismicity, confined to the Dead Sea basin and its boundaries, by the Dead Sea Integrated Research (DESIRE) portable seismic network and the Israel and Jordan permanent seismic networks for studying the mechanisms of earthquakes that occurred in the Dead Sea basin. The observed seismicity in the Dead Sea basin was divided into 9 regions according to the spatial distribution of the earthquakes and the known tectonic features. The large number of recording stations and the good station distribution allowed the reliable determinations of 494 earthquake focal mechanisms. For each region, based on the inversion of the observed polarities of the earthquakes, we determine the focal mechanisms and the associated stress tensor. For 159 earthquakes out of the 494 mechanisms we could determine compatible fault planes. On the eastern side, the focal mechanisms are mainly strike-slip mechanism with nodal planes in the N-S and E-W directions. The azimuths of the stress axes are well constrained presenting minimal variability in the inversion of the data, which is in good agreement with the Arava fault on the eastern side of the Dead Sea basin and what we had expected from the regional geodynamics. However, larger variabilities of the azimuthal and dip angles are observed on the western side of the basin. Due to the wider range of azimuths of the fault planes, we observe the switching of sigma1 and sigma2 or the switching of sigma2 and sigma3as major horizontal stress directions. This observed switching of stress axes allows having dip-slip and normal mechanisms in a region that is dominated by strike-slip motion.

  12. EFL Foreign Teacher Stress in Korea: Causes and Coping Mechanisms

    ERIC Educational Resources Information Center

    Brundage, Gregory C.

    2007-01-01

    Survey study of 53 foreign EFL teachers in Jeonju City, South Korea looks at causes of teacher stress and coping mechanisms between the years of 2004 and 2006. Results show foreign EFL teachers report moderate levels of stress and attribute stresses in roughly equal measures to student misbehavior and school director/administrative sources. Survey…

  13. Investigation of stress relaxation mechanisms for ductility improvement in SS316L

    NASA Astrophysics Data System (ADS)

    Varma, Anand; Gokhale, Aditya; Jain, Jayant; Hariharan, Krishnaswamy; Cizek, Pavel; Barnett, Matthew

    2018-01-01

    Stress relaxation during plastic deformation has been reported to improve ductility and alter the mechanical properties of metallic materials. The aim of the present study is to investigate the role of various mechanisms responsible for this in stainless steel SS 316L. The fractography of the tested samples is analysed using an image analyser and the void fraction at failure is correlated with the corresponding mechanisms. The parametric studies on stress relaxation at different pre-strain and relaxation time correlate well with the fractography results supporting the proposed mechanisms. TEM investigation of dislocation structures and void characterisation further confirm the role of dislocation annihilation. Moreover, a novel indentation technique combining micro- and nano-indentation techniques is used to verify the role of stress homogenisation mechanism.

  14. Environmentally toxicant exposures induced intragenerational transmission of liver abnormalities in mice

    PubMed Central

    Al-Griw, Mohamed A.; Treesh, Soad A.; Alghazeer, Rabia O.; Regeai, Sassia O.

    2017-01-01

    Environmental toxicants such as chemicals, heavy metals, and pesticides have been shown to promote transgenerational inheritance of abnormal phenotypes and/or diseases to multiple subsequent generations following parental and/or ancestral exposures. This study was designed to examine the potential transgenerational action of the environmental toxicant trichloroethane (TCE) on transmission of liver abnormality, and to elucidate the molecular etiology of hepatocyte cell damage. A total of thirty two healthy immature female albino mice were randomly divided into three equal groups as follows: a sham group, which did not receive any treatment; a vehicle group, which received corn oil alone, and TCE treated group (3 weeks, 100 μg/kg i.p., every 4th day). The F0 and F1 generation control and TCE populations were sacrificed at the age of four months, and various abnormalities histpathologically investigated. Cell death and oxidative stress indices were also measured. The present study provides experimental evidence for the inheritance of environmentally induced liver abnormalities in mice. The results of this study show that exposure to the TCE promoted adult onset liver abnormalities in F0 female mice as well as unexposed F1 generation offspring. It is the first study to report a transgenerational liver abnormalities in the F1 generation mice through maternal line prior to gestation. This finding was based on careful evaluation of liver histopathological abnormalities, apoptosis of hepatocytes, and measurements of oxidative stress biomarkers (lipid peroxidation, protein carbonylation, and nitric oxide) in control and TCE populations. There was an increase in liver histopathological abnormalities, cell death, and oxidative lipid damage in F0 and F1 hepatic tissues of TCE treated group. In conclusion, this study showed that the biological and health impacts of environmental toxicant TCE do not end in maternal adults, but are passed on to offspring generations. Hence

  15. Analysis of Mechanical Stresses/Strains in Superconducting Wire

    NASA Astrophysics Data System (ADS)

    Barry, Matthew; Chen, Jingping; Zhai, Yuhu

    2016-10-01

    The optimization of superconducting magnet performance and development of high-field superconducting magnets will greatly impact the next generation of fusion devices. A successful magnet development, however, relies deeply on the understanding of superconducting materials. Among the numerous factors that impact a superconductor's performance, mechanical stress is the most important because of the extreme operation temperature and large electromagnetic forces. In this study, mechanical theory is used to calculate the stresses/strains in typical superconducting strands, which consist of a stabilizer, a barrier, a matrix and superconducting filaments. Both thermal loads and mechanical loads are included in the analysis to simulate operation conditions. Because this model simulates the typical architecture of major superconducting materials, such as Nb3Sn, MgB2, Bi-2212 etc., it provides a good overall picture for us to understand the behavior of these superconductors in terms of thermal and mechanical loads. This work was supported in part by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Science Undergraduate Laboratory Internship (SULI) program.

  16. Exacerbated immune stress response during experimental magnesium deficiency results from abnormal cell calcium homeostasis.

    PubMed

    Malpuech-Brugère, C; Rock, E; Astier, C; Nowacki, W; Mazur, A; Rayssiguier, Y

    1998-01-01

    The aim of this study was to assess the potential mechanism underlying the enhanced inflammatory processes during magnesium deficit. In this study, exacerbated response to live bacteria and platelet activating factors was shown in rats fed a magnesium-deficient diet. Peritoneal cells from these animals also showed enhanced superoxide anion production and calcium mobilising potency following in vitro stimulation. The latter effect occurred very early in the course of magnesium deficiency. These studies first showed that an abnormal calcium handling induced by extracellular magnesium depression in vivo may be at the origin of exacerbated inflammatory response.

  17. Coping Mechanisms Utah Agriculture Teachers Use to Manage Teaching Related Stress

    ERIC Educational Resources Information Center

    Lawver, Rebecca G.; Smith, Kasee L.

    2014-01-01

    The purpose of this study was to examine the level of occupational stress among Utah agriculture teachers, and to determine the coping mechanisms utilized to manage teaching related stressful events. Teachers were asked to rank their level of occupational stress according to the scale used by the American Psychological Association Stress in…

  18. Induction of IAPP amyloid deposition and associated diabetic abnormalities by a prion-like mechanism

    PubMed Central

    Morales-Scheihing, Diego; Salvadores, Natalia; Moreno-Gonzalez, Ines; Gonzalez, Cesar; Shahnawaz, Mohammad

    2017-01-01

    Although a large proportion of patients with type 2 diabetes (T2D) accumulate misfolded aggregates composed of the islet amyloid polypeptide (IAPP), its role in the disease is unknown. Here, we show that pancreatic IAPP aggregates can promote the misfolding and aggregation of endogenous IAPP in islet cultures obtained from transgenic mouse or healthy human pancreas. Islet homogenates immunodepleted with anti-IAPP–specific antibodies were not able to induce IAPP aggregation. Importantly, intraperitoneal inoculation of pancreatic homogenates containing IAPP aggregates into transgenic mice expressing human IAPP dramatically accelerates IAPP amyloid deposition, which was accompanied by clinical abnormalities typical of T2D, including hyperglycemia, impaired glucose tolerance, and a substantial reduction on β cell number and mass. Finally, induction of IAPP deposition and diabetic abnormalities were also induced in vivo by administration of IAPP aggregates prepared in vitro using pure, synthetic IAPP. Our findings suggest that some of the pathologic and clinical alterations of T2D might be transmissible through a similar mechanism by which prions propagate in prion diseases. PMID:28765400

  19. Mechanical Stress Induces Remodeling of Vascular Networks in Growing Leaves

    PubMed Central

    Bar-Sinai, Yohai; Julien, Jean-Daniel; Sharon, Eran; Armon, Shahaf; Nakayama, Naomi; Adda-Bedia, Mokhtar; Boudaoud, Arezki

    2016-01-01

    Differentiation into well-defined patterns and tissue growth are recognized as key processes in organismal development. However, it is unclear whether patterns are passively, homogeneously dilated by growth or whether they remodel during tissue expansion. Leaf vascular networks are well-fitted to investigate this issue, since leaves are approximately two-dimensional and grow manyfold in size. Here we study experimentally and computationally how vein patterns affect growth. We first model the growing vasculature as a network of viscoelastic rods and consider its response to external mechanical stress. We use the so-called texture tensor to quantify the local network geometry and reveal that growth is heterogeneous, resembling non-affine deformations in composite materials. We then apply mechanical forces to growing leaves after veins have differentiated, which respond by anisotropic growth and reorientation of the network in the direction of external stress. External mechanical stress appears to make growth more homogeneous, in contrast with the model with viscoelastic rods. However, we reconcile the model with experimental data by incorporating randomness in rod thickness and a threshold in the rod growth law, making the rods viscoelastoplastic. Altogether, we show that the higher stiffness of veins leads to their reorientation along external forces, along with a reduction in growth heterogeneity. This process may lead to the reinforcement of leaves against mechanical stress. More generally, our work contributes to a framework whereby growth and patterns are coordinated through the differences in mechanical properties between cell types. PMID:27074136

  20. Stress-strain state of mechanical rebar couplings

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Klimenov, Vasilij, E-mail: nauka@tsuab.ru; Tomsk State University of Architecture and Buildings, 2 Solyanaya Sq., Tomsk, 634003; Ovchinnikov, Artem

    Mechanical rebar couplers are preferable in the advanced building construction and structural design of anti-seismic elements. The paper presents destructive inspection techniques used to investigate stress fields (tensile and compressive) and deformation curves for mechanical rebar splicing. The properties of mechanical rebar splicing are investigated by the non-destructive testing digital radiography. The behavior of real connections (column-to-column, beam-to-column) is studied under static and dynamic loads. Investigation results allow the elaboration of recommendations on their application in the universal prefabricated anti-seismic structural system developed at Tomsk State University of Architecture and Building, Tomsk, Russia.

  1. Off-axis mirror fabrication from spherical surfaces under mechanical stress

    NASA Astrophysics Data System (ADS)

    Izazaga-Pérez, R.; Aguirre-Aguirre, D.; Percino-Zacarías, M. E.; Granados-Agustín, Fermin-Salomon

    2013-09-01

    The preliminary results in the fabrication of off-axis optical surfaces are presented. The propose using the conventional polishing method and with the surface under mechanical stress at its edges. It starts fabricating a spherical surface using ZERODUR® optical glass with the conventional polishing method, the surface is deformed by applying tension and/or compression at the surface edges using a specially designed mechanical mount. To know the necessary deformation, the interferogram of the deformed surface is analyzed in real time with a ZYGO® Mark II Fizeau type interferometer, the mechanical stress is applied until obtain the inverse interferogram associated to the off-axis surface that we need to fabricate. Polishing process is carried out again until obtain a spherical surface, then mechanical stress in the edges are removed and compares the actual interferogram with the theoretical associated to the off-axis surface. To analyze the resulting interferograms of the surface we used the phase shifting analysis method by using a piezoelectric phase-shifter and Durango® interferometry software from Diffraction International™.

  2. Complex patterns of abnormal heartbeats

    NASA Technical Reports Server (NTRS)

    Schulte-Frohlinde, Verena; Ashkenazy, Yosef; Goldberger, Ary L.; Ivanov, Plamen Ch; Costa, Madalena; Morley-Davies, Adrian; Stanley, H. Eugene; Glass, Leon

    2002-01-01

    Individuals having frequent abnormal heartbeats interspersed with normal heartbeats may be at an increased risk of sudden cardiac death. However, mechanistic understanding of such cardiac arrhythmias is limited. We present a visual and qualitative method to display statistical properties of abnormal heartbeats. We introduce dynamical "heartprints" which reveal characteristic patterns in long clinical records encompassing approximately 10(5) heartbeats and may provide information about underlying mechanisms. We test if these dynamics can be reproduced by model simulations in which abnormal heartbeats are generated (i) randomly, (ii) at a fixed time interval following a preceding normal heartbeat, or (iii) by an independent oscillator that may or may not interact with the normal heartbeat. We compare the results of these three models and test their limitations to comprehensively simulate the statistical features of selected clinical records. This work introduces methods that can be used to test mathematical models of arrhythmogenesis and to develop a new understanding of underlying electrophysiologic mechanisms of cardiac arrhythmia.

  3. Enhanced exosome secretion in Down syndrome brain - a protective mechanism to alleviate neuronal endosomal abnormalities.

    PubMed

    Gauthier, Sébastien A; Pérez-González, Rocío; Sharma, Ajay; Huang, Fang-Ke; Alldred, Melissa J; Pawlik, Monika; Kaur, Gurjinder; Ginsberg, Stephen D; Neubert, Thomas A; Levy, Efrat

    2017-08-29

    A dysfunctional endosomal pathway and abnormally enlarged early endosomes in neurons are an early characteristic of Down syndrome (DS) and Alzheimer's disease (AD). We have hypothesized that endosomal material can be released by endosomal multivesicular bodies (MVBs) into the extracellular space via exosomes to relieve neurons of accumulated endosomal contents when endosomal pathway function is compromised. Supporting this, we found that exosome secretion is enhanced in the brains of DS patients and a mouse model of the disease, and by DS fibroblasts. Furthermore, increased levels of the tetraspanin CD63, a regulator of exosome biogenesis, were observed in DS brains. Importantly, CD63 knockdown diminished exosome release and worsened endosomal pathology in DS fibroblasts. Taken together, these data suggest that increased CD63 expression enhances exosome release as an endogenous mechanism mitigating endosomal abnormalities in DS. Thus, the upregulation of exosome release represents a potential therapeutic goal for neurodegenerative disorders with endosomal pathology.

  4. Spine abnormalities depicted by magnetic resonance imaging in adolescent rowers.

    PubMed

    Maurer, Marvin; Soder, Ricardo Bernardi; Baldisserotto, Matteo

    2011-02-01

    Most lesions of the spine of athletes, which often are detected incidentally, do not cause important symptoms or make the athletes discontinue their physical activities. To better understand the significance of these lesions, new imaging studies have been conducted with asymptomatic athletes in several sports, aiming to detect potentially deleterious and disabling abnormalities. To compare the magnetic resonance imaging (MRI) lumbar spine findings in a group of asymptomatic adolescent rowers and in a control group of adolescents matched according to age and sex who do not practice any regular physical activity. Cohort study (prevalence); Level of evidence, 3. Our study evaluated 44 asymptomatic adolescent boys distributed in 2 groups of 22 rowers and 22 control subjects. All the examinations were performed using a 0.35-T open-field MRI unit and evaluated by 2 experienced radiologists blinded to the study groups. Each MRI scan was analyzed for the presence of disc degeneration/desiccation, herniated or bulging disc, pars interarticularis stress reaction, and spondylolysis. The Student t test and the Fisher exact test were used for statistical analyses. Nine rowers (40.9%) had at least 1 abnormality detected by MRI in the lumbar spine, whereas only 2 participants (9.1%) in the control group had at least 1 MRI abnormality (P = .03). Seven disc changes (31.8%) and 6 pars abnormalities (27.3%) were found in the group of elite rowers. In the control group, 3 disc changes (13.6%) and no pars abnormalities were found in the MR scans. The comparison between groups showed statistically significant differences in stress reaction of the pars articularis. Disc disease and pars interarticularis stress reaction are prevalent abnormalities of the lumbar spine of high-performance rowers.

  5. Biochemical mechanisms of signaling: perspectives in plants under arsenic stress.

    PubMed

    Islam, Ejazul; Khan, Muhammad Tahir; Irem, Samra

    2015-04-01

    Plants are the ultimate food source for humans, either directly or indirectly. Being sessile in nature, they are exposed to various biotic and abiotic stresses because of changing climate that adversely effects their growth and development. Contamination of heavy metals is one of the major abiotic stresses because of anthropogenic as well as natural factors which lead to increased toxicity and accumulation in plants. Arsenic is a naturally occurring metalloid toxin present in the earth crust. Due to its presence in terrestrial and aquatic environments, it effects the growth of plants. Plants can tolerate arsenic using several mechanisms like phytochelation, vacuole sequestration and activation of antioxidant defense systems. Several signaling mechanisms have evolved in plants that involve the use of proteins, calcium ions, hormones, reactive oxygen species and nitric oxide as signaling molecules to cope with arsenic toxicity. These mechanisms facilitate plants to survive under metal stress by activating their defense systems. The pathways by which these stress signals are perceived and responded is an unexplored area of research and there are lots of gaps still to be filled. A good understanding of these signaling pathways can help in raising the plants which can perform better in arsenic contaminated soil and water. In order to increase the survival of plants in contaminated areas there is a strong need to identify suitable gene targets that can be modified according to needs of the stakeholders using various biotechnological techniques. This review focuses on the signaling mechanisms of plants grown under arsenic stress and will give an insight of the different sensory systems in plants. Furthermore, it provides the knowledge about several pathways that can be exploited to develop plant cultivars which are resistant to arsenic stress or can reduce its uptake to minimize the risk of arsenic toxicity through food chain thus ensuring food security. Copyright © 2015

  6. Unique construction makes interferometer insensitive to mechanical stresses

    NASA Technical Reports Server (NTRS)

    Beer, R.

    1965-01-01

    Michelson-type interferometer with a cat-eye reflector operates effectively even in the presence of random mechanical stresses. A cubical beamsplitter with dichroic surfaces permits operation in infrared or visible light.

  7. Mechanical stress regulates insulin sensitivity through integrin-dependent control of insulin receptor localization.

    PubMed

    Kim, Jung; Bilder, David; Neufeld, Thomas P

    2018-01-15

    Insulin resistance, the failure to activate insulin signaling in the presence of ligand, leads to metabolic diseases, including type 2 diabetes. Physical activity and mechanical stress have been shown to protect against insulin resistance, but the molecular mechanisms remain unclear. Here, we address this relationship in the Drosophila larval fat body, an insulin-sensitive organ analogous to vertebrate adipose tissue and livers. We found that insulin signaling in Drosophila fat body cells is abolished in the absence of physical activity and mechanical stress even when excess insulin is present. Physical movement is required for insulin sensitivity in both intact larvae and fat bodies cultured ex vivo. Interestingly, the insulin receptor and other downstream components are recruited to the plasma membrane in response to mechanical stress, and this membrane localization is rapidly lost upon disruption of larval or tissue movement. Sensing of mechanical stimuli is mediated in part by integrins, whose activation is necessary and sufficient for mechanical stress-dependent insulin signaling. Insulin resistance develops naturally during the transition from the active larval stage to the immotile pupal stage, suggesting that regulation of insulin sensitivity by mechanical stress may help coordinate developmental programming with metabolism. © 2018 Kim et al.; Published by Cold Spring Harbor Laboratory Press.

  8. Mechanical stress as a regulator of cell motility

    NASA Astrophysics Data System (ADS)

    Putelat, T.; Recho, P.; Truskinovsky, L.

    2018-01-01

    The motility of a cell can be triggered or inhibited not only by an applied force but also by a mechanically neutral force couple. This type of loading, represented by an applied stress and commonly interpreted as either squeezing or stretching, can originate from extrinsic interaction of a cell with its neighbors. To quantify the effect of applied stresses on cell motility we use an analytically transparent one-dimensional model accounting for active myosin contraction and induced actin turnover. We show that stretching can polarize static cells and initiate cell motility while squeezing can symmetrize and arrest moving cells. We show further that sufficiently strong squeezing can lead to the loss of cell integrity. The overall behavior of the system depends on the two dimensionless parameters characterizing internal driving (chemical activity) and external loading (applied stress). We construct a phase diagram in this parameter space distinguishing between static, motile, and collapsed states. The obtained results are relevant for the mechanical understanding of contact inhibition and the epithelial-to-mesenchymal transition.

  9. Mechanism of valvular regurgitation.

    PubMed

    Khoo, Nee S; Smallhorn, Jeffery F

    2011-10-01

    Despite improvements in surgical techniques, valvular regurgitation results in major morbidity in children with heart disease. Functional anatomy, mechanisms of valve closure and adaptation to changing hemodynamic stress in normal mitral and tricuspid valves are complex and only partially understood. As well, pathology of atrioventricular valve regurgitation is further complicated by congenital valve abnormalities involving leaflet tissue, supporting chordal apparatus and displaced papillary muscles. This review provides a current understanding of the mechanisms that result in atrioventricular valve failure. Mitral valve leaflets have contractile elements, in addition to atrial muscle modulation of leaflet tension. When placed under mechanical tethering stress, the mitral valve adapts by leaflet expansion, which increases coaptation surface reserve and chordal thickening. Both pediatric and adult studies are increasingly reporting on the importance of subvalvar apparatus function in maintaining valve competency. The maintenance of efficient valve function is accomplished by a complex series of events involving atrial and annular contraction, annular deformation, active leaflet tension, chordal transmission of papillary muscle contractions and ventricular contraction.

  10. Mechanism of gastrointestinal abnormal motor activity induced by cisplatin in conscious dogs.

    PubMed

    Ando, Hiroyuki; Mochiki, Erito; Ohno, Tetsuro; Yanai, Mitsuhiro; Toyomasu, Yoshitaka; Ogata, Kyoichi; Tabe, Yuichi; Aihara, Ryuusuke; Nakabayashi, Toshihiro; Asao, Takayuki; Kuwano, Hiroyuki

    2014-11-14

    To investigate whether 5-hydroxytryptamine (serotonin; 5-HT) is involved in mediating abnormal motor activity in dogs after cisplatin administration. After the dogs had been given a 2-wk recovery period, all of them were administered cisplatin, and the motor activity was recorded using strain gauge force transducers. Blood and intestinal fluid samples were collected to measure 5-HT for 24 h. To determine whether 5-HT in plasma or that in intestinal fluids is more closely related to abnormal motor activity we injected 5-HT into the bloodstream and the intestinal tract of the dogs. Cisplatin given intravenously produced abnormal motor activity that lasted up to 5 h. From 3 to 4 h after cisplatin administration, normal intact dogs exhibited retropropagation of motor activity accompanied by emesis. The concentration of 5-HT in plasma reached the peak at 4 h, and that in intestinal fluids reached the peak at 3 h. In normal intact dogs with resection of the vagus nerve that were administered kytril, cisplatin given intravenously did not produce abnormal motor activity. Intestinal serotonin administration did not produce abnormal motor activity, but intravenous serotonin administration did. After the intravenous administration of cisplatin, abnormal motor activity was produced in the involved vagus nerve and in the involved serotonergic neurons via another pathway. This study was the first to determine the relationship between 5-HT and emesis-induced motor activity.

  11. An Abnormal Nitric Oxide Metabolism Contributes to Brain Oxidative Stress in the Mouse Model for the Fragile X Syndrome, a Possible Role in Intellectual Disability

    PubMed Central

    Lima-Cabello, Elena; Garcia-Guirado, Francisco; Calvo-Medina, Rocio; el Bekay, Rajaa; Perez-Costillas, Lucia; Quintero-Navarro, Carolina; Sanchez-Salido, Lourdes

    2016-01-01

    Background. Fragile X syndrome is the most common genetic cause of mental disability. Although many research has been performed, the mechanism underlying the pathogenesis is unclear and needs further investigation. Oxidative stress played major roles in the syndrome. The aim was to investigate the nitric oxide metabolism, protein nitration level, the expression of NOS isoforms, and furthermore the activation of the nuclear factor NF-κB-p65 subunit in different brain areas on the fragile X mouse model. Methods. This study involved adult male Fmr1-knockout and wild-type mice as controls. We detected nitric oxide metabolism and the activation of the nuclear factor NF-κBp65 subunit, comparing the mRNA expression and protein content of the three NOS isoforms in different brain areas. Results. Fmr1-KO mice showed an abnormal nitric oxide metabolism and increased levels of protein tyrosine nitrosylation. Besides that, nuclear factor NF-κB-p65 and inducible nitric oxide synthase appeared significantly increased in the Fmr1-knockout mice. mRNA and protein levels of the neuronal nitric oxide synthase appeared significantly decreased in the knockout mice. However, the epithelial nitric oxide synthase isoform displayed no significant changes. Conclusions. These data suggest the potential involvement of an abnormal nitric oxide metabolism in the pathogenesis of the fragile X syndrome. PMID:26788253

  12. Salicylic acid-induced abiotic stress tolerance and underlying mechanisms in plants

    PubMed Central

    Khan, M. Iqbal R.; Fatma, Mehar; Per, Tasir S.; Anjum, Naser A.; Khan, Nafees A.

    2015-01-01

    Abiotic stresses (such as metals/metalloids, salinity, ozone, UV-B radiation, extreme temperatures, and drought) are among the most challenging threats to agricultural system and economic yield of crop plants. These stresses (in isolation and/or combination) induce numerous adverse effects in plants, impair biochemical/physiological and molecular processes, and eventually cause severe reductions in plant growth, development and overall productivity. Phytohormones have been recognized as a strong tool for sustainably alleviating adverse effects of abiotic stresses in crop plants. In particular, the significance of salicylic acid (SA) has been increasingly recognized in improved plant abiotic stress-tolerance via SA-mediated control of major plant-metabolic processes. However, the basic biochemical/physiological and molecular mechanisms that potentially underpin SA-induced plant-tolerance to major abiotic stresses remain least discussed. Based on recent reports, this paper: (a) overviews historical background and biosynthesis of SA under both optimal and stressful environments in plants; (b) critically appraises the role of SA in plants exposed to major abiotic stresses; (c) cross-talks potential mechanisms potentially governing SA-induced plant abiotic stress-tolerance; and finally (d) briefly highlights major aspects so far unexplored in the current context. PMID:26175738

  13. Mechanisms of yeast stress tolerance and its manipulation for efficient fuel ethanol production.

    PubMed

    Zhao, X Q; Bai, F W

    2009-10-12

    Yeast strains of Saccharomyces cerevisiae have been extensively studied in recent years for fuel ethanol production, in which yeast cells are exposed to various stresses such as high temperature, ethanol inhibition, and osmotic pressure from product and substrate sugars as well as the inhibitory substances released from the pretreatment of lignocellulosic biomass. An in-depth understanding of the mechanism of yeast stress tolerance contributes to breeding more robust strains for ethanol production, especially under very high gravity conditions. Taking advantage of the "omics" technology, the stress response and defense mechanism of yeast cells during ethanol fermentation were further explored, and the newly emerged tools such as genome shuffling and global transcription machinery engineering have been applied to breed stress resistant yeast strains for ethanol production. In this review, the latest development of stress tolerance mechanisms was focused, and improvement of yeast stress tolerance by both random and rational tools was presented.

  14. Neuroendocrine and oxidoreductive mechanisms of stress-induced cardiovascular diseases.

    PubMed

    Pajović, S B; Radojcić, M B; Kanazir, D T

    2008-01-01

    The review concerns a number of basic molecular pathways that play a crucial role in perception, transmission, and modulation of the stress signals, and mediate the adaptation of the vital processes in the cardiovascular system (CVS). These highly complex systems for intracellular transfer of information include stress hormones and their receptors, stress-activated phosphoprotein kinases, stress-activated heat shock proteins, and antioxidant enzymes maintaining oxidoreductive homeostasis of the CVS. Failure to compensate for the deleterious effects of stress may result in the development of different pathophysiological states of the CVS, such as ischemia, hypertension, atherosclerosis and infarction. Stress-induced dysbalance in each of the CVS molecular signaling systems and their contribution to the CVS malfunctioning is reviewed. The general picture of the molecular mechanisms of the stress-induced pathophysiology in the CVS pointed out the importance of stress duration and intensity as etiological factors, and suggested that future studies should be complemented by the careful insights into the individual factors of susceptibility to stress, prophylactic effects of 'healthy' life styles and beneficial action of antioxidant-rich nutrition.

  15. Roles of the tyrosine isomers meta-tyrosine and ortho-tyrosine in oxidative stress.

    PubMed

    Ipson, Brett R; Fisher, Alfred L

    2016-05-01

    The damage to cellular components by reactive oxygen species, termed oxidative stress, both increases with age and likely contributes to age-related diseases including Alzheimer's disease, atherosclerosis, diabetes, and cataract formation. In the setting of oxidative stress, hydroxyl radicals can oxidize the benzyl ring of the amino acid phenylalanine, which then produces the abnormal tyrosine isomers meta-tyrosine or ortho-tyrosine. While elevations in m-tyrosine and o-tyrosine concentrations have been used as a biological marker of oxidative stress, there is emerging evidence from bacterial, plant, and mammalian studies demonstrating that these isomers, particularly m-tyrosine, directly produce adverse effects to cells and tissues. These new findings suggest that the abnormal tyrosine isomers could in fact represent mediators of the effects of oxidative stress. Consequently the accumulation of m- and o-tyrosine may disrupt cellular homeostasis and contribute to disease pathogenesis, and as result, effective defenses against oxidative stress can encompass not only the elimination of reactive oxygen species but also the metabolism and ultimately the removal of the abnormal tyrosine isomers from the cellular amino acid pool. Future research in this area is needed to clarify the biologic mechanisms by which the tyrosine isomers damage cells and disrupt the function of tissues and organs and to identify the metabolic pathways involved in removing the accumulated isomers after exposure to oxidative stress. Published by Elsevier B.V.

  16. Roles of the tyrosine isomers meta-tyrosine and ortho-tyrosine in oxidative stress

    PubMed Central

    Ipson, Brett R.; Fisher, Alfred L.

    2016-01-01

    The damage to cellular components by reactive oxygen species, termed oxidative stress, both increases with age and likely contributes to age-related diseases including Alzheimer’s disease, atherosclerosis, diabetes, and cataract formation. In the setting of oxidative stress, hydroxyl radicals can oxidize the benzyl ring of the amino acid phenylalanine, which then produces the abnormal tyrosine isomers meta-tyrosine or ortho-tyrosine. While elevations in m-tyrosine and o-tyrosine concentrations have been used as a biological marker of oxidative stress, there is emerging evidence from bacterial, plant, and mammalian studies demonstrating that these isomers, particularly m-tyrosine, directly produce adverse effects to cells and tissues. These new findings suggest that the abnormal tyrosine isomers could in fact represent mediators of the effects of oxidative stress. Consequently the accumulation of m- and o-tyrosine may disrupt cellular homeostasis and contribute to disease pathogenesis, and as result, effective defenses against oxidative stress can encompass not only the elimination of reactive oxygen species but also the metabolism and ultimately the removal of the abnormal tyrosine isomers from the cellular amino acid pool. Future research in this area is needed to clarify the biologic mechanisms by which the tyrosine isomers damage cells and disrupt the function of tissues and organs, and to identify the metabolic pathways involved in removing the accumulated isomers after exposure to oxidative stress. PMID:27039887

  17. On equally and completely stressed hinged mechanisms

    NASA Astrophysics Data System (ADS)

    Kovalev, M. D.

    2018-05-01

    The following new question is investigated: is there any bar and joint planar linkage with every bar having the same nonzero stress in each position of the linkage, and with each angle between adjacent bars varying, when the linkage moves? The absence of such mechanisms under appropriate condition is prooved.

  18. Mechanism of gastrointestinal abnormal motor activity induced by cisplatin in conscious dogs

    PubMed Central

    Ando, Hiroyuki; Mochiki, Erito; Ohno, Tetsuro; Yanai, Mitsuhiro; Toyomasu, Yoshitaka; Ogata, Kyoichi; Tabe, Yuichi; Aihara, Ryuusuke; Nakabayashi, Toshihiro; Asao, Takayuki; Kuwano, Hiroyuki

    2014-01-01

    AIM: To investigate whether 5-hydroxytryptamine (serotonin; 5-HT) is involved in mediating abnormal motor activity in dogs after cisplatin administration. METHODS: After the dogs had been given a 2-wk recovery period, all of them were administered cisplatin, and the motor activity was recorded using strain gauge force transducers. Blood and intestinal fluid samples were collected to measure 5-HT for 24 h. To determine whether 5-HT in plasma or that in intestinal fluids is more closely related to abnormal motor activity we injected 5-HT into the bloodstream and the intestinal tract of the dogs. RESULTS: Cisplatin given intravenously produced abnormal motor activity that lasted up to 5 h. From 3 to 4 h after cisplatin administration, normal intact dogs exhibited retropropagation of motor activity accompanied by emesis. The concentration of 5-HT in plasma reached the peak at 4 h, and that in intestinal fluids reached the peak at 3 h. In normal intact dogs with resection of the vagus nerve that were administered kytril, cisplatin given intravenously did not produce abnormal motor activity. Intestinal serotonin administration did not produce abnormal motor activity, but intravenous serotonin administration did. CONCLUSION: After the intravenous administration of cisplatin, abnormal motor activity was produced in the involved vagus nerve and in the involved serotonergic neurons via another pathway. This study was the first to determine the relationship between 5-HT and emesis-induced motor activity. PMID:25400453

  19. An analytical model of the mechanical properties of bulk coal under confined stress

    USGS Publications Warehouse

    Wang, G.X.; Wang, Z.T.; Rudolph, V.; Massarotto, P.; Finley, R.J.

    2007-01-01

    This paper presents the development of an analytical model which can be used to relate the structural parameters of coal to its mechanical properties such as elastic modulus and Poisson's ratio under a confined stress condition. This model is developed primarily to support process modeling of coalbed methane (CBM) or CO2-enhanced CBM (ECBM) recovery from coal seam. It applied an innovative approach by which stresses acting on and strains occurring in coal are successively combined in rectangular coordinates, leading to the aggregated mechanical constants. These mechanical properties represent important information for improving CBM/ECBM simulations and incorporating within these considerations of directional permeability. The model, consisting of constitutive equations which implement a mechanically consistent stress-strains correlation, can be used as a generalized tool to study the mechanical and fluid behaviors of coal composites. An example using the model to predict the stress-strain correlation of coal under triaxial confined stress by accounting for the elastic and brittle (non-elastic) deformations is discussed. The result shows a good agreement between the prediction and the experimental measurement. ?? 2007 Elsevier Ltd. All rights reserved.

  20. Mechanisms of adaptation to nitrosative stress in Bacillus subtilis.

    PubMed

    Rogstam, Annika; Larsson, Jonas T; Kjelgaard, Peter; von Wachenfeldt, Claes

    2007-04-01

    Bacteria use a number of mechanisms for coping with the toxic effects exerted by nitric oxide (NO) and its derivatives. Here we show that the flavohemoglobin encoded by the hmp gene has a vital role in an adaptive response to protect the soil bacterium Bacillus subtilis from nitrosative stress. We further show that nitrosative stress induced by the nitrosonium cation donor sodium nitroprusside (SNP) leads to deactivation of the transcriptional repressor NsrR, resulting in derepression of hmp. Nitrosative stress induces the sigma B-controlled general stress regulon. However, a sigB null mutant did not show increased sensitivity to SNP, suggesting that the sigma B-dependent stress proteins are involved in a nonspecific protection against stress whereas the Hmp flavohemoglobin plays a central role in detoxification. Mutations in the yjbIH operon, which encodes a truncated hemoglobin (YjbI) and a predicted 34-kDa cytosolic protein of unknown function (YjbH), rendered B. subtilis hypersensitive to SNP, suggesting roles in nitrosative stress management.

  1. Relationship between structural abnormalities in the cerebellum and dementia, posttraumatic stress disorder and bipolar disorder.

    PubMed

    Baldaçara, Leonardo; Borgio, João Guilherme Fiorani; Araújo, Célia; Nery-Fernandes, Fabiana; Lacerda, Acioly Luiz Taveres; Moraes, Walter André Dos Santos; Montaño, Maria Beatriz Marcondes Macedo; Rocha, Marlos; Quarantini, Lucas C; Schoedl, Aline; Pupo, Mariana; Mello, Marcelo F; Andreoli, Sergio B; Miranda-Scippa, Angela; Ramos, Luiz Roberto; Mari, Jair J; Bressan, Rodrigo Affonseca; Jackowski, Andrea Parolin

    2012-01-01

    New evidence suggests that the cerebellum has structural and functional abnormalities in psychiatric disorders. In this research, the goal was to measure the volume of the cerebellum and its subregions in individuals with psychiatric disorders and to relate these findings to their symptoms. Patients with different degrees of cognitive impairment (Epidemiology of the Elderly - UNIFESP) and patients with post-traumatic stress disorder (PTSD) from population studies were analyzed. Also, patients with bipolar disorder from an outpatient clinic (Center for the Study of Mood and Anxiety Disorders, Universidade Federal da Bahia) were recruited for this study. All subjects underwent a 1.5T structural magnetic resonance scan. Volumetric measures and symptom measurements, by psychometric scales, were performed and compared between patients and controls. The cerebellum volume was reduced in patients with cognitive impairment without dementia and with dementia, in patients with PTSD, and in patients with bipolar disorder compared to controls. In dementia and PTSD, the left cerebellar hemisphere and vermis volume were reduced. In bipolar disorder, volumes of both hemispheres and the vermis were reduced. In the first two studies, these cerebellar volumetric reductions correlated with symptoms of the disease. The exact nature of cerebellar involvement in mental processes is still not fully understood. However, abnormalities in cerebellar structure and its functions have been reported in some of these diseases. Future studies with larger samples are needed to clarify these findings and investigate whether they are important for treatment and prognosis.

  2. Subcellular and supracellular mechanical stress prescribes cytoskeleton behavior in Arabidopsis cotyledon pavement cells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sampathkumar, Arun; Krupinski, Pawel; Wightman, Raymond

    Although it is a central question in biology, how cell shape controls intracellular dynamics largely remains an open question. Here, we show that the shape of Arabidopsis pavement cells creates a stress pattern that controls microtubule orientation, which then guides cell wall reinforcement. Live-imaging, combined with modeling of cell mechanics, shows that microtubules align along the maximal tensile stress direction within the cells, and atomic force microscopy demonstrates that this leads to reinforcement of the cell wall parallel to the microtubules. This feedback loop is regulated: cell-shape derived stresses could be overridden by imposed tissue level stresses, showing how competitionmore » between subcellular and supracellular cues control microtubule behavior. Furthermore, at the microtubule level, we identified an amplification mechanism in which mechanical stress promotes the microtubule response to stress by increasing severing activity. These multiscale feedbacks likely contribute to the robustness of microtubule behavior in plant epidermis.« less

  3. Subcellular and supracellular mechanical stress prescribes cytoskeleton behavior in Arabidopsis cotyledon pavement cells

    PubMed Central

    Sampathkumar, Arun; Krupinski, Pawel; Wightman, Raymond; Milani, Pascale; Berquand, Alexandre; Boudaoud, Arezki; Hamant, Olivier; Jönsson, Henrik; Meyerowitz, Elliot M

    2014-01-01

    Although it is a central question in biology, how cell shape controls intracellular dynamics largely remains an open question. Here, we show that the shape of Arabidopsis pavement cells creates a stress pattern that controls microtubule orientation, which then guides cell wall reinforcement. Live-imaging, combined with modeling of cell mechanics, shows that microtubules align along the maximal tensile stress direction within the cells, and atomic force microscopy demonstrates that this leads to reinforcement of the cell wall parallel to the microtubules. This feedback loop is regulated: cell-shape derived stresses could be overridden by imposed tissue level stresses, showing how competition between subcellular and supracellular cues control microtubule behavior. Furthermore, at the microtubule level, we identified an amplification mechanism in which mechanical stress promotes the microtubule response to stress by increasing severing activity. These multiscale feedbacks likely contribute to the robustness of microtubule behavior in plant epidermis. DOI: http://dx.doi.org/10.7554/eLife.01967.001 PMID:24740969

  4. Subcellular and supracellular mechanical stress prescribes cytoskeleton behavior in Arabidopsis cotyledon pavement cells

    DOE PAGES

    Sampathkumar, Arun; Krupinski, Pawel; Wightman, Raymond; ...

    2014-04-16

    Although it is a central question in biology, how cell shape controls intracellular dynamics largely remains an open question. Here, we show that the shape of Arabidopsis pavement cells creates a stress pattern that controls microtubule orientation, which then guides cell wall reinforcement. Live-imaging, combined with modeling of cell mechanics, shows that microtubules align along the maximal tensile stress direction within the cells, and atomic force microscopy demonstrates that this leads to reinforcement of the cell wall parallel to the microtubules. This feedback loop is regulated: cell-shape derived stresses could be overridden by imposed tissue level stresses, showing how competitionmore » between subcellular and supracellular cues control microtubule behavior. Furthermore, at the microtubule level, we identified an amplification mechanism in which mechanical stress promotes the microtubule response to stress by increasing severing activity. These multiscale feedbacks likely contribute to the robustness of microtubule behavior in plant epidermis.« less

  5. Fibromyalgia: a stress disorder? Piecing the biopsychosocial puzzle together.

    PubMed

    Van Houdenhove, Boudewijn; Egle, Ulrich T

    2004-01-01

    Fibromyalgia (FM) is a controversial syndrome, characterised by persistent widespread pain, abnormal pain sensitivity and additional symptoms such as fatigue and sleep disturbance. The syndrome largely overlaps with other functional somatic disorders, particularly chronic fatigue syndrome (CFS). Although the exact aetiology and pathogenesis of FM are still unknown, it has been suggested that stress may play a key role in the syndrome. This article first reviews the function of the stress response system, placing special emphasis on the relationships between adverse life experiences, stress regulation and pain-processing mechanisms, and summarising the evidence for a possible aetiopathogenetic role of stress in FM. Finally, an integrative biopsychosocial model that conceptualizes FM as a stress disorder is proposed, and the clinical and research implications of the model are discussed.

  6. Controlling stress corrosion cracking in mechanism components of ground support equipment

    NASA Technical Reports Server (NTRS)

    Majid, W. A.

    1988-01-01

    The selection of materials for mechanism components used in ground support equipment so that failures resulting from stress corrosion cracking will be prevented is described. A general criteria to be used in designing for resistance to stress corrosion cracking is also provided. Stress corrosion can be defined as combined action of sustained tensile stress and corrosion to cause premature failure of materials. Various aluminum, steels, nickel, titanium and copper alloys, and tempers and corrosive environment are evaluated for stress corrosion cracking.

  7. Cytological, molecular mechanisms and temperature stress regulating production of diploid male gametes in Dianthus caryophyllus L.

    PubMed

    Zhou, Xuhong; Mo, Xijun; Gui, Min; Wu, Xuewei; Jiang, Yalian; Ma, Lulin; Shi, Ziming; Luo, Ying; Tang, Wenru

    2015-12-01

    In plant evolution, because of its key role in sexual polyploidization or whole genome duplication events, diploid gamete formation is considered as an important component in diversification and speciation. Environmental stress often triggers unreduced gamete production. However, the molecular, cellular mechanisms and adverse temperature regulating diplogamete production in carnation remain poorly understood. Here, we investigate the cytological basis for 2n male gamete formation and describe the isolation and characterization of the first gene, DcPS1 (Dianthus Caryophyllus Parallel Spindle 1). In addition, we analyze influence of temperature stress on diploid gamete formation and transcript levels of DcPS1. Cytological evidence indicated that 2n male gamete formation is attributable to abnormal spindle orientation at male meiosis II. DcPS1 protein is conserved throughout the plant kingdom and carries domains suggestive of a regulatory function. DcPS1 expression analysis show DcPS1 gene probably have a role in 2n pollen formation. Unreduced pollen formation in various cultivation was sensitive to high or low temperature which was probably regulated by the level of DcPS1 transcripts. In a broader perspective, these findings can have potential applications in fundamental polyploidization research and plant breeding programs. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  8. Periodic Mechanical Stress INDUCES Chondrocyte Proliferation and Matrix Synthesis via CaMKII-Mediated Pyk2 Signaling.

    PubMed

    Liang, Wenwei; Li, Zeng; Wang, Zhen; Zhou, Jinchun; Song, Huanghe; Xu, Shun; Cui, Weiding; Wang, Qing; Chen, Zhefeng; Liu, Feng; Fan, Weimin

    2017-01-01

    Periodic mechanical stress can promote chondrocyte proliferation and matrix synthesis to improve the quality of tissue-engineered cartilage. Although the integrin β1-ERK1/2 signal cascade has been implicated in periodic mechanical stress-induced mitogenic effects in chondrocytes, the precise mechanisms have not been fully established. The current study was designed to probe the roles of CaMKII and Pyk2 signaling in periodic mechanical stress-mediated chondrocyte proliferation and matrix synthesis. Chondrocytes were subjected to periodic mechanical stress, proliferation was assessed by direct cell counting and CCK-8 assay; gene expressions were analyzed using quantitative real-time PCR, protein abundance by Western blotting. Mechanical stress, markedly enhanced the phosphorylation levels of Pyk2 at Tyr402 and CaMKII at Thr286. Both suppression of Pyk2 with Pyk2 inhibitor PF431396 or Pyk2 shRNA and suppression of CaMKII with CaMKII inhibitor KN-93 or CaMKII shRNA blocked periodic mechanical stress-induced chondrocyte proliferation and matrix synthesis. Additionally, either pretreatment with KN-93 or shRNA targeted to CaMKII prevented the activation of ERK1/2 and Pyk2 under conditions of periodic mechanical stress. Interestingly, in relation to periodic mechanical stress, in the context of Pyk2 inhibition with PF431396 or its targeted shRNA, only the phosphorylation levels of ERK1/2 were abrogated, while CaMKII signal activation was not affected. Moreover, the phosphorylation levels of CaMKII- Thr286 and Pyk2- Tyr402 were abolished after pretreatment with blocking antibody against integrinβ1 exposed to periodic mechanical stress. Our results collectively indicate that periodic mechanical stress promotes chondrocyte proliferation and matrix synthesis through the integrinβ1-CaMKII-Pyk2-ERK1/2 signaling cascade. © 2017 The Author(s). Published by S. Karger AG, Basel.

  9. Mechanical Characterization of Thermomechanical Matrix Residual Stresses Incurred During MMC Processing

    NASA Technical Reports Server (NTRS)

    Castelli, Michael G.

    1998-01-01

    In recent years, much effort has been spent examining the residual stress-strain states of advanced composites. Such examinations are motivated by a number of significant concerns that affect composite development, processing, and analysis. The room-temperature residual stress states incurred in many advanced composite systems are often quite large and can introduce damage even prior to the first external mechanical loading of the material. These stresses, which are induced during the cooldown following high-temperature consolidation, result from the coefficient of thermal expansion mismatch between the fiber and matrix. Experimental techniques commonly used to evaluate composite internal residual stress states are non-mechanical in nature and generally include forms of x-ray and neutron diffraction. Such approaches are usually complex, involving a number of assumptions and limitations associated with a wide range of issues, including the depth of penetration, the volume of material being assessed, and erroneous effects associated with oriented grains. Furthermore, and more important to the present research, these techniques can assess only "single time" stress in the composite. That is, little, if any, information is obtained that addresses the time-dependent point at which internal stresses begin to accumulate, the manner in which the accumulation occurs, and the presiding relationships between thermoelastic, thermoplastic, and thermoviscous behaviors. To address these critical issues, researchers at the NASA Lewis Research Center developed and implemented an innovative mechanical test technique to examine in real time, the time-dependent thermomechanical stress behavior of a matrix alloy as it went through a consolidation cycle.

  10. Shared and unique responses of plants to multiple individual stresses and stress combinations: physiological and molecular mechanisms

    PubMed Central

    Pandey, Prachi; Ramegowda, Venkategowda; Senthil-Kumar, Muthappa

    2015-01-01

    In field conditions, plants are often simultaneously exposed to multiple biotic and abiotic stresses resulting in substantial yield loss. Plants have evolved various physiological and molecular adaptations to protect themselves under stress combinations. Emerging evidences suggest that plant responses to a combination of stresses are unique from individual stress responses. In addition, plants exhibit shared responses which are common to individual stresses and stress combination. In this review, we provide an update on the current understanding of both unique and shared responses. Specific focus of this review is on heat–drought stress as a major abiotic stress combination and, drought–pathogen and heat–pathogen as examples of abiotic–biotic stress combinations. We also comprehend the current understanding of molecular mechanisms of cross talk in relation to shared and unique molecular responses for plant survival under stress combinations. Thus, the knowledge of shared responses of plants from individual stress studies and stress combinations can be utilized to develop varieties with broad spectrum stress tolerance. PMID:26442037

  11. Mental Stress-Induced-Myocardial Ischemia in Young Patients With Recent Myocardial Infarction: Sex Differences and Mechanisms.

    PubMed

    Vaccarino, Viola; Sullivan, Samaah; Hammadah, Muhammad; Wilmot, Kobina; Al Mheid, Ibhar; Ramadan, Ronnie; Elon, Lisa; Pimple, Pratik M; Garcia, Ernest V; Nye, Jonathon; Shah, Amit J; Alkhoder, Ayman; Levantsevych, Oleksiy; Gay, Hawkins; Obideen, Malik; Huang, Minxuan; Lewis, Tené T; Bremner, J Douglas; Quyyumi, Arshed A; Raggi, Paolo

    2018-02-20

    Mental stress-induced myocardial ischemia (MSIMI) is frequent in patients with coronary artery disease and is associated with worse prognosis. Young women with a previous myocardial infarction (MI), a group with unexplained higher mortality than men of comparable age, have shown elevated rates of MSIMI, but the mechanisms are unknown. We studied 306 patients (150 women and 156 men) ≤61 years of age who were hospitalized for MI in the previous 8 months and 112 community controls (58 women and 54 men) frequency matched for sex and age to the patients with MI. Endothelium-dependent flow-mediated dilation and microvascular reactivity (reactive hyperemia index) were measured at rest and 30 minutes after mental stress. The digital vasomotor response to mental stress was assessed using peripheral arterial tonometry. Patients received 99m Tc-sestamibi myocardial perfusion imaging at rest, with mental (speech task) and conventional (exercise/pharmacological) stress. The mean age of the sample was 50 years (range, 22-61). In the MI group but not among controls, women had a more adverse socioeconomic and psychosocial profile than men. There were no sex differences in cardiovascular risk factors, and among patients with MI, clinical severity tended to be lower in women. Women in both groups showed a higher peripheral arterial tonometry ratio during mental stress but a lower reactive hyperemia index after mental stress, indicating enhanced microvascular dysfunction after stress. There were no sex differences in flow-mediated dilation changes with mental stress. The rate of MSIMI was twice as high in women as in men (22% versus 11%, P =0.009), and ischemia with conventional stress was similarly elevated (31% versus 16%, P =0.002). Psychosocial and clinical risk factors did not explain sex differences in inducible ischemia. Although vascular responses to mental stress (peripheral arterial tonometry ratio and reactive hyperemia index) also did not explain sex differences in

  12. Dysregulated stress signal sensitivity and inflammatory disinhibition as a pathophysiological mechanism of stress-related chronic fatigue.

    PubMed

    Strahler, Jana; Skoluda, Nadine; Rohleder, Nicolas; Nater, Urs M

    2016-09-01

    Chronic stress and its subsequent effects on biological stress systems have long been recognized as predisposing and perpetuating factors in chronic fatigue, although the exact mechanisms are far from being completely understood. In this review, we propose that sensitivity of immune cells to glucocorticoids (GCs) and catecholamines (CATs) may be the missing link in elucidating how stress turns into chronic fatigue. We searched for in vitro studies investigating the impact of GCs or CATs on mitogen-stimulated immune cells in chronically stressed or fatigued populations, with 34 original studies fulfilling our inclusion criteria. Besides mixed cross-sectional findings for stress- and fatigue-related changes of GC sensitivity under basal conditions or acute stress, longitudinal studies indicate a decrease with ongoing stress. Research on CATs is still scarce, but initial findings point towards a reduction of CAT sensitivity under chronic stress. In the long run, resistance of immune cells to stress signals under conditions of chronic stress might translate into self-maintaining inflammation and inflammatory disinhibition under acute stress, which in turn lead to fatigue. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Maternal mind-mindedness as a linking mechanism between childbirth-related posttraumatic stress symptoms and parenting stress.

    PubMed

    Camisasca, Elena; Procaccia, Rossella; Miragoli, Sarah; Valtolina, Giovanni Giulio; Di Blasio, Paola

    2017-06-01

    The researchers of this study have two aims. The first aim is to verify whether posttraumatic stress (PTS) symptoms, evaluated at 87 hours and at 3 months postpartum, are associated with maternal mind-mindedness (MM) and parenting stress, measured at 17 months postpartum. The second aim is to investigate, at 17 months, the predictive effects of PTS symptoms on the dimensions of parenting stress and to explore whether MM mediates these associations. Forty-one mother-infant dyads participated in the study. The results show that at 17 months, hyper-arousal symptoms predicted both MM and parenting stress. MM was a linking mechanism between maternal PTS symptoms and parenting stress.

  14. Mechanical stress and network structure drive protein dynamics during cytokinesis.

    PubMed

    Srivastava, Vasudha; Robinson, Douglas N

    2015-03-02

    Cell-shape changes associated with processes like cytokinesis and motility proceed on several-second timescales but are derived from molecular events, including protein-protein interactions, filament assembly, and force generation by molecular motors, all of which occur much faster [1-4]. Therefore, defining the dynamics of such molecular machinery is critical for understanding cell-shape regulation. In addition to signaling pathways, mechanical stresses also direct cytoskeletal protein accumulation [5-7]. A myosin-II-based mechanosensory system controls cellular contractility and shape during cytokinesis and under applied stress [6, 8]. In Dictyostelium, this system tunes myosin II accumulation by feedback through the actin network, particularly through the crosslinker cortexillin I. Cortexillin-binding IQGAPs are major regulators of this system. Here, we defined the short timescale dynamics of key cytoskeletal proteins during cytokinesis and under mechanical stress, using fluorescence recovery after photobleaching and fluorescence correlation spectroscopy, to examine the dynamic interplay between these proteins. Equatorially enriched proteins including cortexillin I, IQGAP2, and myosin II recovered much more slowly than actin and polar crosslinkers. The mobility of equatorial proteins was greatly reduced at the furrow compared to the interphase cortex, suggesting their stabilization during cytokinesis. This mobility shift did not arise from a single biochemical event, but rather from a global inhibition of protein dynamics by mechanical-stress-associated changes in the cytoskeletal structure. Mechanical tuning of contractile protein dynamics provides robustness to the cytoskeletal framework responsible for regulating cell shape and contributes to cytokinesis fidelity. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Understanding abiotic stress tolerance mechanisms in soybean: a comparative evaluation of soybean response to drought and flooding stress.

    PubMed

    Mutava, Raymond N; Prince, Silvas Jebakumar K; Syed, Naeem Hasan; Song, Li; Valliyodan, Babu; Chen, Wei; Nguyen, Henry T

    2015-01-01

    Many sources of drought and flooding tolerance have been identified in soybean, however underlying molecular and physiological mechanisms are poorly understood. Therefore, it is important to illuminate different plant responses to these abiotic stresses and understand the mechanisms that confer tolerance. Towards this goal we used four contrasting soybean (Glycine max) genotypes (PI 567690--drought tolerant, Pana--drought susceptible, PI 408105A--flooding tolerant, S99-2281--flooding susceptible) grown under greenhouse conditions and compared genotypic responses to drought and flooding at the physiological, biochemical, and cellular level. We also quantified these variations and tried to infer their role in drought and flooding tolerance in soybean. Our results revealed that different mechanisms contribute to reduction in net photosynthesis under drought and flooding stress. Under drought stress, ABA and stomatal conductance are responsible for reduced photosynthetic rate; while under flooding stress, accumulation of starch granules played a major role. Drought tolerant genotypes PI 567690 and PI 408105A had higher plastoglobule numbers than the susceptible Pana and S99-2281. Drought stress increased the number and size of plastoglobules in most of the genotypes pointing to a possible role in stress tolerance. Interestingly, there were seven fibrillin proteins localized within the plastoglobules that were up-regulated in the drought and flooding tolerant genotypes PI 567690 and PI 408105A, respectively, but down-regulated in the drought susceptible genotype Pana. These results suggest a potential role of Fibrillin proteins, FBN1a, 1b and 7a in soybean response to drought and flooding stress. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  16. Mapping of Mechanical Strains and Stresses around Quiescent Engineered Three-Dimensional Epithelial Tissues

    PubMed Central

    Gjorevski, Nikolce; Nelson, Celeste M.

    2012-01-01

    Understanding how physical signals guide biological processes requires qualitative and quantitative knowledge of the mechanical forces generated and sensed by cells in a physiologically realistic three-dimensional (3D) context. Here, we used computational modeling and engineered epithelial tissues of precise geometry to define the experimental parameters that are required to measure directly the mechanical stress profile of 3D tissues embedded within native type I collagen. We found that to calculate the stresses accurately in these settings, we had to account for mechanical heterogeneities within the matrix, which we visualized and quantified using confocal reflectance and atomic force microscopy. Using this technique, we were able to obtain traction forces at the epithelium-matrix interface, and to resolve and quantify patterns of mechanical stress throughout the surrounding matrix. We discovered that whereas single cells generate tension by contracting and pulling on the matrix, the contraction of multicellular tissues can also push against the matrix, causing emergent compression. Furthermore, tissue geometry defines the spatial distribution of mechanical stress across the epithelium, which communicates mechanically over distances spanning hundreds of micrometers. Spatially resolved mechanical maps can provide insight into the types and magnitudes of physical parameters that are sensed and interpreted by multicellular tissues during normal and pathological processes. PMID:22828342

  17. Altered mechanisms underlying the abnormal glutamate release in amyotrophic lateral sclerosis at a pre-symptomatic stage of the disease.

    PubMed

    Bonifacino, Tiziana; Musazzi, Laura; Milanese, Marco; Seguini, Mara; Marte, Antonella; Gallia, Elena; Cattaneo, Luca; Onofri, Franco; Popoli, Maurizio; Bonanno, Giambattista

    2016-11-01

    Abnormal Glu release occurs in the spinal cord of SOD1(G93A) mice, a transgenic animal model for human ALS. Here we studied the mechanisms underlying Glu release in spinal cord nerve terminals of SOD1(G93A) mice at a pre-symptomatic disease stage (30days) and found that the basal release of Glu was more elevated in SOD1(G93A) with respect to SOD1 mice, and that the surplus of release relies on synaptic vesicle exocytosis. Exposure to high KCl or ionomycin provoked Ca(2+)-dependent Glu release that was likewise augmented in SOD1(G93A) mice. Equally, the Ca(2+)-independent hypertonic sucrose-induced Glu release was abnormally elevated in SOD1(G93A) mice. Also in this case, the surplus of Glu release was exocytotic in nature. We could determine elevated cytosolic Ca(2+) levels, increased phosphorylation of Synapsin-I, which was causally related to the abnormal Glu release measured in spinal cord synaptosomes of pre-symptomatic SOD1(G93A) mice, and increased phosphorylation of glycogen synthase kinase-3 at the inhibitory sites, an event that favours SNARE protein assembly. Western blot experiments revealed an increased number of SNARE protein complexes at the nerve terminal membrane, with no changes of the three SNARE proteins and increased expression of synaptotagmin-1 and β-Actin, but not of an array of other release-related presynaptic proteins. These results indicate that the abnormal exocytotic Glu release in spinal cord of pre-symptomatic SOD1(G93A) mice is mainly based on the increased size of the readily releasable pool of vesicles and release facilitation, supported by plastic changes of specific presynaptic mechanisms. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Evaluation of Genotoxicity in Automobile Mechanics Occupationally Exposed to Polycyclic Aromatic Hydrocarbons Using Micronuclei and Other Nuclear Abnormalities

    PubMed Central

    Khan, Mohammed Rafiq; Sudha, Sellappa

    2012-01-01

    Background Occupational and environmental exposures mostly represent mixtures of genotoxic agents, whereas the specificity of biomarker measurements varies widely. Exploration of correlations among biomarkers contributes to the further progress of molecular cancer epidemiology and to the selection of the optimal biomarkers for the investigation of human exposure to carcinogens. The aim of this study was to assess the potential cytogenetic damage associated with occupational exposure to Polycyclic Aromatic Hydrocarbons (PAHs) among automobile mechanics by using Micronuclei (MN) and other Nuclear Abnormalities (NA) as a biomarker. Methods The study population composed of 110 occupationally exposed automobile mechanics and 100 unexposed controls. All the study participants were males. Both the exposed and control individuals were selected from automobile garages located in the urban area of Coimbatore City, South India. Exfoliated buccal cells were collected from 110 automobile mechanics and 100 age and sex matched controls. Further, cells were examined for MN frequency and Nuclear Abnormalities (NA) other than micronuclei, such as binucleates, broken eggs and karyolysis. Results Results showed a statistically significant difference between occupationally exposed automobile mechanics and control groups. MN and NA frequencies in automobile mechanics were significantly higher than those in control groups (p < 0.05) and also significantly related to smoking habit (p < 0.05). In addition, a higher degree of NA was observed among the exposed subjects with smoking, drinking, tobacco chewing, which is an indicative of cytogenetic damage in these individuals. Conclusion MN and other NA reflect genetic changes, events associated with carcinogenesis. Therefore, the results of this study indicate that automobile mechanics exposed to PAHs are under risk of significant cytogenetic damage. Therefore, it is important to provide and offer better awareness of occupational hazards

  19. Mechanism of laser-induced stress relaxation in cartilage

    NASA Astrophysics Data System (ADS)

    Sobol, Emil N.; Sviridov, Alexander P.; Omelchenko, Alexander I.; Bagratashvili, Victor N.; Bagratashvili, Nodar V.; Popov, Vladimir K.

    1997-06-01

    The paper presents theoretical and experimental results allowing to discuss and understand the mechanism of stress relaxation and reshaping of cartilage under laser radiation. A carbon dioxide and a Holmium laser was used for treatment of rabbits and human cartilage. We measured temperature, stress, amplitude of oscillation by free and forced vibration, internal friction, and light scattering in the course of laser irradiation. Using experimental data and theoretical modeling of heat and mass transfer in cartilaginous tissue we estimated the values of transformation heat, diffusion coefficients and energy activation for water movement.

  20. The effect of abnormal hemoglobins on the membrane regulation of cell hydration.

    PubMed

    Clark, M R; Shohet, S B

    Several hemoglobinopathies are associated with abnormalities in the permeability of the red cell membrane, in some cases leading to permanent alterations of the intracellular milieu. Homozygous sickle cell disease is the most thoroughly studied example. Deoxygenation of sickle cells causes a transient increase in the permeability to monovalent cations and Ca; prolonged deoxygenation can lead to a permanent accumulation of Ca and loss of total cations and water. Although the mechanisms for the permeability changes are not yet defined, mechanical stress on the membrane, with subsequent damages by excess Ca or membrane-associated hemoglobin have been suggested to play a role. Loss of cell water and increase in mean cell hemoglobin concentration causes massive reduction of cell deformability in the oxygenated state and makes the hemoglobin more likely to undergo sickling because of the strong concentration dependence of the sickling process. Limited evidence suggests the occurrence of permeability defects in other hemoglobinopathies and the thalassemias. The suggested alterations range from a slight increase in K permeability of incubated thalassemia cells to substantial dehydration of cells from patients with homozygous hemoglobin C disease. Oxidative damage to the membrane, involving an abnormal hemoglobin-membrane association, may underly the permeability changes in these cells.

  1. 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.

  2. In Vivo Talocrural Joint Contact Mechanics With Functional Ankle Instability.

    PubMed

    Kobayashi, Takumi; Suzuki, Eiichi; Yamazaki, Naohito; Suzukawa, Makoto; Akaike, Atsushi; Shimizu, Kuniaki; Gamada, Kazuyoshi

    2015-12-01

    Functional ankle instability (FAI) may involve abnormal kinematics and contact mechanics during ankle internal rotation. Understanding of these abnormalities is important to prevent secondary problems in patients with FAI. However, there are no in vivo studies that have investigated talocrural joint contact mechanics during weightbearing ankle internal rotation. The objective of this study to determine talocrural contact mechanics during weightbearing ankle internal rotation in patients with FAI. Twelve male subjects with unilateral FAI (age range, 18-26 years) were enrolled. Computed tomography and fluoroscopic imaging of both lower extremities were obtained during weightbearing passive ankle joint complex rotation. Three-dimensional bone models created from the computed tomographic images were matched to the fluoroscopic images to compute 6 degrees of freedom for talocrural joint kinematics. The closest contact area in the talocrural joint in ankle neutral rotation and maximum internal rotation during either dorsiflexion or plantar flexion was determined using geometric bone models and talocrural joint kinematics data. The closest contact area in the talus shifted anteromedially during ankle dorsiflexion-internal rotation, whereas it shifted posteromedially during ankle plantar flexion-internal rotation. The closest contact area in FAI joints was significantly more medial than that in healthy joints during maximum ankle internal rotation and was associated with excessive talocrural internal rotation or inversion. This study demonstrated abnormal talocrural kinematics and contact mechanics in FAI subjects. Such abnormal kinematics may contribute to abnormal contact mechanics and may increase cartilage stress in FAI joints. Therapeutic, Level IV: cross-sectional case-control study. © 2015 The Author(s).

  3. Elevated Shear Stress in Arteriovenous Fistulae: Is There Mechanical Homeostasis?

    NASA Astrophysics Data System (ADS)

    McGah, Patrick; Leotta, Daniel; Beach, Kirk; Aliseda, Alberto

    2011-11-01

    Arteriovenous fistulae are created surgically to provide access for dialysis in patients with renal failure. The current hypothesis is that the rapid remodeling occurring after the fistula creation is in part a process to restore the mechanical stresses to some preferred level (i.e. mechanical homeostasis). Given that nearly 50% of fistulae require an intervention after one year, understanding the altered hemodynamic stress is important in improving clinical outcomes. We perform numerical simulations of four patient-specific models of functioning fistulae reconstructed from 3D Doppler ultrasound scans. Our results show that the vessels are subjected to `normal' shear stresses away from the anastomosis; about 1 Pa in the veins and about 2.5 Pa in the arteries. However, simulations show that part of the anastomoses are consistently subjected to very high shear stress (>10Pa) over the cardiac cycle. These elevated values shear stresses are caused by the transitional flows at the anastomoses including flow separation and quasiperiodic vortex shedding. This suggests that the remodeling process lowers shear stress in the fistula but that it is limited as evidenced by the elevated shear at the anastomoses. This constant insult on the arterialized venous wall may explain the process of late fistula failure in which the dialysis access become occluded after years of use. Supported by an R21 Grant from NIDDK (DK081823).

  4. Adult Literacy Education Program Administrators' Perceptions of Occupational Stress and Coping Mechanisms

    ERIC Educational Resources Information Center

    Engelmann, Stephanie

    2014-01-01

    Job performance may be adversely affected by stress. Job stress is a primary contributor to serious physical and emotional health consequences. This quantitative study examined adult literacy program administrator perceptions of occupational stress and coping mechanisms related to job satisfaction, job efficacy, career longevity, and overall…

  5. A whole-heart motion-correction algorithm: Effects on CT image quality and diagnostic accuracy of mechanical valve prosthesis abnormalities.

    PubMed

    Suh, Young Joo; Kim, Young Jin; Kim, Jin Young; Chang, Suyon; Im, Dong Jin; Hong, Yoo Jin; Choi, Byoung Wook

    2017-11-01

    We aimed to determine the effect of a whole-heart motion-correction algorithm (new-generation snapshot freeze, NG SSF) on the image quality of cardiac computed tomography (CT) images in patients with mechanical valve prostheses compared to standard images without motion correction and to compare the diagnostic accuracy of NG SSF and standard CT image sets for the detection of prosthetic valve abnormalities. A total of 20 patients with 32 mechanical valves who underwent wide-coverage detector cardiac CT with single-heartbeat acquisition were included. The CT image quality for subvalvular (below the prosthesis) and valvular regions (valve leaflets) of mechanical valves was assessed by two observers on a four-point scale (1 = poor, 2 = fair, 3 = good, and 4 = excellent). Paired t-tests or Wilcoxon signed rank tests were used to compare image quality scores and the number of diagnostic phases (image quality score≥3) between the standard image sets and NG SSF image sets. Diagnostic performance for detection of prosthetic valve abnormalities was compared between two image sets with the final diagnosis set by re-operation or clinical findings as the standard reference. NG SSF image sets had better image quality scores than standard image sets for both valvular and subvalvular regions (P < 0.05 for both). The number of phases that were of diagnostic image quality per patient was significantly greater in the NG SSF image set than standard image set for both valvular and subvalvular regions (P < 0.0001). Diagnostic performance of NG SSF image sets for the detection of prosthetic abnormalities (20 pannus and two paravalvular leaks) was greater than that of standard image sets (P < 0.05). Application of NG SSF can improve CT image quality and diagnostic accuracy in patients with mechanical valves compared to standard images. Copyright © 2017 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

  6. Mechanical Twinning and Microstructures in Experimentally Stressed Quartzite

    NASA Astrophysics Data System (ADS)

    Minor, A.; Sintubin, M.; Wenk, H. R.; Rybacki, E.

    2015-12-01

    Since Dauphiné twins in quartz have been identified as a stress-related intracrystalline microstructure, several electron backscatter diffraction (EBSD) studies revealed that Dauphiné twins are present in naturally deformed quartz-bearing rocks in a wide range of tectono-metamorphic conditions. EBSD studies on experimentally stressed quartzite showed that crystals with particular crystallographic orientations contain many Dauphiné twin boundaries, while neighboring crystals with different orientations are largely free of twin boundaries. To understand the relationship between stress direction and orientation of Dauphiné twinned quartz crystals, a detailed EBSD study was performed on experimentally stressed quartzite samples and compared with an undeformed reference sample. We stressed 4 cylindrical samples in triaxial compression in a Paterson type gas deformation apparatus at GFZ Potsdam. Experimental conditions were 300MPa confining pressure, 500°C temperature and axial stresses of 145MPa, 250MPa and 460MPa for about 30 hours, resulting in a minor strain <0.04%. EBSD scans were obtained with a Zeiss Evo scanning electron microscope and TSL software at UC Berkeley. The EBSD maps show that Dauphiné twinning is present in the starting material as well as in experimentally stressed samples. Pole figures of the bulk orientation of the reference sample compared with stressed samples show a significant difference regarding the distribution for the r and z directions. The reference sample shows an indistinct maximum for r and z, whereas the stressed samples show a maximum for r poles and a minimum for z poles in the axial stress direction. EBSD scans of the reference and stressed samples were further analyzed manually to identify the orientations of single grains, which are free of twin boundaries and those, which contain twin boundaries. This analysis aims to quantify the relationship of crystal orientation and stress magnitude to initiate mechanical twinning.

  7. Integrated Stress Response Mediates Epithelial Injury in Mechanical Ventilation.

    PubMed

    Dolinay, Tamas; Himes, Blanca E; Shumyatcher, Maya; Lawrence, Gladys Gray; Margulies, Susan S

    2017-08-01

    Ventilator-induced lung injury (VILI) is a severe complication of mechanical ventilation that can lead to acute respiratory distress syndrome. VILI is characterized by damage to the epithelial barrier with subsequent pulmonary edema and profound hypoxia. Available lung-protective ventilator strategies offer only a modest benefit in preventing VILI because they cannot impede alveolar overdistension and concomitant epithelial barrier dysfunction in the inflamed lung regions. There are currently no effective biochemical therapies to mitigate injury to the alveolar epithelium. We hypothesize that alveolar stretch activates the integrated stress response (ISR) pathway and that the chemical inhibition of this pathway mitigates alveolar barrier disruption during stretch and mechanical ventilation. Using our established rat primary type I-like alveolar epithelial cell monolayer stretch model and in vivo rat mechanical ventilation that mimics the alveolar overdistension seen in acute respiratory distress syndrome, we studied epithelial responses to mechanical stress. Our studies revealed that the ISR signaling pathway is a key modulator of epithelial permeability. We show that prolonged epithelial stretch and injurious mechanical ventilation activate the ISR, leading to increased alveolar permeability, cell death, and proinflammatory signaling. Chemical inhibition of protein kinase RNA-like endoplasmic reticulum kinase, an upstream regulator of the pathway, resulted in decreased injury signaling and improved barrier function after prolonged cyclic stretch and injurious mechanical ventilation. Our results provide new evidence that therapeutic targeting of the ISR can mitigate VILI.

  8. Indirect Measurement of Energy Density of Soft PZT Ceramic Utilizing Mechanical Stress

    NASA Astrophysics Data System (ADS)

    Unruan, Muangjai; Unruan, Sujitra; Inkong, Yutthapong; Yimnirun, Rattikorn

    2017-11-01

    This paper reports on an indirect measurement of energy density of soft PZT ceramic utilizing mechanical stress. The method works analogous to the Olsen cycle and allows for a large amount of electro-mechanical energy conversion. A maximum energy density of 350 kJ/m3/cycle was found under 0-312 MPa and 1-20 kV/cm of applied mechanical stress and electric field, respectively. The obtained result is substantially higher than the results reported in previous studies of PZT materials utilizing a direct piezoelectric effect.

  9. Stress biology and aging mechanisms: toward understanding the deep connection between adaptation to stress and longevity.

    PubMed

    Epel, Elissa S; Lithgow, Gordon J

    2014-06-01

    The rate of biological aging is modulated in part by genes interacting with stressor exposures. Basic research has shown that exposure to short-term stress can strengthen cellular responses to stress ("hormetic stress"). Hormetic stress promotes longevity in part through enhanced activity of molecular chaperones and other defense mechanisms. In contrast, prolonged exposure to stress can overwhelm compensatory responses ("toxic stress") and shorten lifespan. One key question is whether the stressors that are well understood in basic models of aging can help us understand psychological stressors and human health. The psychological stress response promotes regulatory changes important in aging (e.g., increases in stress hormones, inflammation, oxidative stress, insulin). The negative effects of severe stress are well documented in humans. Potential positive effects of acute stress (stress resistance) are less studied, especially at the cellular level. Can stress resistance slow the rate of aging in humans, as it does in model organisms? If so, how can we promote stress resistance in humans? We urge a new research agenda embracing the continuum from cellular stress to psychological stress, using basic and human research in tandem. This will require interdisciplinary novel approaches that hold much promise for understanding and intervening in human chronic disease. © The Author 2014. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. A review of research trends in physiological abnormalities in autism spectrum disorders: immune dysregulation, inflammation, oxidative stress, mitochondrial dysfunction and environmental toxicant exposures

    PubMed Central

    Rossignol, D A; Frye, R E

    2012-01-01

    Recent studies have implicated physiological and metabolic abnormalities in autism spectrum disorders (ASD) and other psychiatric disorders, particularly immune dysregulation or inflammation, oxidative stress, mitochondrial dysfunction and environmental toxicant exposures (‘four major areas'). The aim of this study was to determine trends in the literature on these topics with respect to ASD. A comprehensive literature search from 1971 to 2010 was performed in these four major areas in ASD with three objectives. First, publications were divided by several criteria, including whether or not they implicated an association between the physiological abnormality and ASD. A large percentage of publications implicated an association between ASD and immune dysregulation/inflammation (416 out of 437 publications, 95%), oxidative stress (all 115), mitochondrial dysfunction (145 of 153, 95%) and toxicant exposures (170 of 190, 89%). Second, the strength of evidence for publications in each area was computed using a validated scale. The strongest evidence was for immune dysregulation/inflammation and oxidative stress, followed by toxicant exposures and mitochondrial dysfunction. In all areas, at least 45% of the publications were rated as providing strong evidence for an association between the physiological abnormalities and ASD. Third, the time trends in the four major areas were compared with trends in neuroimaging, neuropathology, theory of mind and genetics (‘four comparison areas'). The number of publications per 5-year block in all eight areas was calculated in order to identify significant changes in trends. Prior to 1986, only 12 publications were identified in the four major areas and 51 in the four comparison areas (42 for genetics). For each 5-year period, the total number of publications in the eight combined areas increased progressively. Most publications (552 of 895, 62%) in the four major areas were published in the last 5 years (2006–2010). Evaluation

  11. Musculo-Skeletal Abnormalities in Patients with Marfan Syndrome

    PubMed Central

    Al Kaissi, Ali; Zwettler, Elisabeth; Ganger, Rudolf; Schreiner, Simone; Klaushofer, Klaus; Grill, Franz

    2013-01-01

    Background A leptosomic body type is tall and thin with long hands. Marfanoid features may be familial in nature or pathological, as occurs in congenital contractual arachnodactyly (Beal’s syndrome) and Shprintzen-Goldberg syndrome mimicking some of the changes of Marfan syndrome, although not accompanied by luxation of lens and dissecting aneurysm of aorta. Methods In this article we collected eight patients who were consistent with the diagnosis of Marfan syndrome via phenotypic and genotypic characterization. Results Our patients manifested a constellation of variable presentations of musculo-skeletal abnormalities ranging from developmental dysplasia of the hip, protrusio acetabuli, leg length inequality, patellar instability, scoliosis, to early onset osteoarthritis. Each abnormality has been treated accordingly. Conclusion This is the first paper which includes the diagnosis and the management of the associated musculo-skeletal abnormalities in patients with Marfan syndrome, stressing that patients with Marfan syndrome are exhibiting great variability in the natural history and the severity of musculo-skeletal abnormalities. PMID:23399831

  12. Microtubules self-repair in response to mechanical stress

    PubMed Central

    Schaedel, Laura; John, Karin; Gaillard, Jérémie; Nachury, Maxence V.; Blanchoin, Laurent; Théry, Manuel

    2015-01-01

    Microtubules - which define the shape of axons, cilia and flagella, and provide tracks for intracellular transport - can be highly bent by intracellular forces, and microtubule structure and stiffness are thought to be affected by physical constraints. Yet how microtubules tolerate the vast forces exerted on them remains unknown. Here, by using a microfluidic device, we show that microtubule stiffness decreases incrementally with each cycle of bending and release. Similar to other cases of material fatigue, the concentration of mechanical stresses on pre-existing defects in the microtubule lattice is responsible for the generation of larger damages, which further decrease microtubule stiffness. Strikingly, damaged microtubules were able to incorporate new tubulin dimers into their lattice and recover their initial stiffness. Our findings demonstrate that microtubules are ductile materials with self-healing properties, that their dynamics does not exclusively occur at their ends, and that their lattice plasticity enables the microtubules' adaptation to mechanical stresses. PMID:26343914

  13. Microtubules self-repair in response to mechanical stress

    NASA Astrophysics Data System (ADS)

    Schaedel, Laura; John, Karin; Gaillard, Jérémie; Nachury, Maxence V.; Blanchoin, Laurent; Théry, Manuel

    2015-11-01

    Microtubules--which define the shape of axons, cilia and flagella, and provide tracks for intracellular transport--can be highly bent by intracellular forces, and microtubule structure and stiffness are thought to be affected by physical constraints. Yet how microtubules tolerate the vast forces exerted on them remains unknown. Here, by using a microfluidic device, we show that microtubule stiffness decreases incrementally with each cycle of bending and release. Similar to other cases of material fatigue, the concentration of mechanical stresses on pre-existing defects in the microtubule lattice is responsible for the generation of more extensive damage, which further decreases microtubule stiffness. Strikingly, damaged microtubules were able to incorporate new tubulin dimers into their lattice and recover their initial stiffness. Our findings demonstrate that microtubules are ductile materials with self-healing properties, that their dynamics does not exclusively occur at their ends, and that their lattice plasticity enables the microtubules' adaptation to mechanical stresses.

  14. Microtubules self-repair in response to mechanical stress.

    PubMed

    Schaedel, Laura; John, Karin; Gaillard, Jérémie; Nachury, Maxence V; Blanchoin, Laurent; Théry, Manuel

    2015-11-01

    Microtubules--which define the shape of axons, cilia and flagella, and provide tracks for intracellular transport--can be highly bent by intracellular forces, and microtubule structure and stiffness are thought to be affected by physical constraints. Yet how microtubules tolerate the vast forces exerted on them remains unknown. Here, by using a microfluidic device, we show that microtubule stiffness decreases incrementally with each cycle of bending and release. Similar to other cases of material fatigue, the concentration of mechanical stresses on pre-existing defects in the microtubule lattice is responsible for the generation of more extensive damage, which further decreases microtubule stiffness. Strikingly, damaged microtubules were able to incorporate new tubulin dimers into their lattice and recover their initial stiffness. Our findings demonstrate that microtubules are ductile materials with self-healing properties, that their dynamics does not exclusively occur at their ends, and that their lattice plasticity enables the microtubules' adaptation to mechanical stresses.

  15. Modeling of abnormal mechanical properties of nickel-based single crystal superalloy by three-dimensional discrete dislocation dynamics

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Li, Zhenhuan; Huang, Minsheng

    2014-12-01

    Unlike common single crystals, the nickel-based single crystal superalloy shows surprisingly anomalous flow strength (i.e. with the increase of temperature, the yield strength first increases to a peak value and then decreases) and tension-compression (TC) asymmetry. A comprehensive three-dimensional discrete dislocation dynamics (3D-DDD) procedure was developed to model these abnormal mechanical properties. For this purpose, a series of complicated dynamic evolution details of Kear-Wilsdorf (KW) locks, which are closely related to the flow strength anomaly and TC asymmetry, were incorporated into this 3D-DDD framework. Moreover, the activation of the cubic slip system, which is the origin of the decrease in yield strength with increasing temperature at relatively high temperatures, was especially taken into account by introducing a competition criterion between the unlocking of the KW locks and the activation of the cubic slip system. To test our framework, a series of 3D-DDD simulations were performed on a representative volume cell model with a cuboidal Ni3Al precipitate phase embedded in a nickel matrix. Results show that the present 3D-DDD procedure can successfully capture the dynamic evolution of KW locks, the flow strength anomaly and TC asymmetry. Then, the underlying dislocation mechanisms leading to these abnormal mechanical responses were investigated and discussed in detail. Finally, a cyclic deformation of the nickel-based single crystal superalloy was modeled by using the present DDD model, with a special focus on the influence of KW locks on the Bauschinger effect and cyclic softening.

  16. Prolonged secretion of cortisol as a possible mechanism underlying stress and depressive behaviour

    PubMed Central

    Qin, Dong-dong; Rizak, Joshua; Feng, Xiao-li; Yang, Shang-chuan; Lü, Long-bao; Pan, Lei; Yin, Yong; Hu, Xin-tian

    2016-01-01

    Stress is associated with the onset of depressive episodes, and cortisol hypersecretion is considered a biological risk factor of depression. However, the possible mechanisms underlying stress, cortisol and depressive behaviours are inconsistent in the literature. This study examined the interrelationships among stress, cortisol and observed depressive behaviours in female rhesus macaques for the first time and explored the possible mechanism underlying stress and depressive behaviour. Female monkeys were video-recorded, and the frequencies of life events and the duration of huddling were analysed to measure stress and depressive behaviour. Hair samples were used to measure chronic cortisol levels, and the interactions between stress and cortisol in the development of depressive behaviour were further evaluated. Significant correlations were found between stress and depressive behaviour measures and between cortisol levels and depressive behaviour. Stress was positively correlated with cortisol levels, and these two factors interacted with each other to predict the monkeys’ depressive behaviours. This finding extends the current understanding of stress/cortisol interactions in depression, especially pertaining to females. PMID:27443987

  17. Stress- and glucocorticoid-induced priming of neuroinflammatory responses: potential mechanisms of stress-induced vulnerability to drugs of abuse.

    PubMed

    Frank, Matthew G; Watkins, Linda R; Maier, Steven F

    2011-06-01

    Stress and stress-induced glucocorticoids (GCs) sensitize drug abuse behavior as well as the neuroinflammatory response to a subsequent pro-inflammatory challenge. Stress also predisposes or sensitizes individuals to develop substance abuse. There is an emerging evidence that glia and glia-derived neuroinflammatory mediators play key roles in the development of drug abuse. Drugs of abuse such as opioids, psychostimulants, and alcohol induce neuroinflammatory mediators such as pro-inflammatory cytokines (e.g. interleukin (IL)-1β), which modulate drug reward, dependence, and tolerance as well as analgesic properties. Drugs of abuse may directly activate microglial and astroglial cells via ligation of Toll-like receptors (TLRs), which mediate the innate immune response to pathogens as well as xenobiotic agents (e.g. drugs of abuse). The present review focuses on understanding the immunologic mechanism(s) whereby stress primes or sensitizes the neuroinflammatory response to drugs of abuse and explores whether stress- and GC-induced sensitization of neuroimmune processes predisposes individuals to drug abuse liability and the role of neuroinflammatory mediators in the development of drug addiction. Copyright © 2011 Elsevier Inc. All rights reserved.

  18. Default mode network abnormalities in posttraumatic stress disorder: A novel network-restricted topology approach.

    PubMed

    Akiki, Teddy J; Averill, Christopher L; Wrocklage, Kristen M; Scott, J Cobb; Averill, Lynnette A; Schweinsburg, Brian; Alexander-Bloch, Aaron; Martini, Brenda; Southwick, Steven M; Krystal, John H; Abdallah, Chadi G

    2018-08-01

    Disruption in the default mode network (DMN) has been implicated in numerous neuropsychiatric disorders, including posttraumatic stress disorder (PTSD). However, studies have largely been limited to seed-based methods and involved inconsistent definitions of the DMN. Recent advances in neuroimaging and graph theory now permit the systematic exploration of intrinsic brain networks. In this study, we used resting-state functional magnetic resonance imaging (fMRI), diffusion MRI, and graph theoretical analyses to systematically examine the DMN connectivity and its relationship with PTSD symptom severity in a cohort of 65 combat-exposed US Veterans. We employed metrics that index overall connectivity strength, network integration (global efficiency), and network segregation (clustering coefficient). Then, we conducted a modularity and network-based statistical analysis to identify DMN regions of particular importance in PTSD. Finally, structural connectivity analyses were used to probe whether white matter abnormalities are associated with the identified functional DMN changes. We found decreased DMN functional connectivity strength to be associated with increased PTSD symptom severity. Further topological characterization suggests decreased functional integration and increased segregation in subjects with severe PTSD. Modularity analyses suggest a spared connectivity in the posterior DMN community (posterior cingulate, precuneus, angular gyrus) despite overall DMN weakened connections with increasing PTSD severity. Edge-wise network-based statistical analyses revealed a prefrontal dysconnectivity. Analysis of the diffusion networks revealed no alterations in overall strength or prefrontal structural connectivity. DMN abnormalities in patients with severe PTSD symptoms are characterized by decreased overall interconnections. On a finer scale, we found a pattern of prefrontal dysconnectivity, but increased cohesiveness in the posterior DMN community and relative sparing

  19. Spatially varying stress state in the central U.S. from joint inversion of focal mechanism and maximum horizontal stress data

    NASA Astrophysics Data System (ADS)

    Carlson, G.; Johnson, K. M.; Rupp, J. A.

    2017-12-01

    The Midcontinental United States continues to experience anomalously high rates of seismicity and generate large earthquakes despite its location in the cratonic interior, far from any plate boundary. There is renewed interest in Midcontinent seismicity with the concern that fluid injection within the Illinois basin could induce seismicity. In order to better understand the seismic hazard and inform studies of risk mitigation, we present an assessment of the contemporary crustal stress state in the Illinois basin and surrounding region, looking specifically at how the orientation of maximum horizontal compressive stress varies throughout the region. This information will help identify which faults are critically stressed and therefore most likely to fail under increased pore pressures. We conduct a Bayesian stress inversion of focal mechanism solutions and maximum horizontal stress orientations from borehole breakout, core fracture, overcoring, hydraulic fracture, and strain gauge measurements for maximum horizontal compressive stress orientations across the Midcontinent region and produce a map of expected faulting styles. Because distinguishing the slipping fault plane from the auxiliary nodal plane is ambiguous for focal mechanisms, the choice of the fault plane and associated slip vector to use in the inversion is important in the estimation of the stress tensor. The stress inversion provides an objective means to estimate nonlinear parameters including the spatial smoothing parameter, unknown data uncertainties, as well as the selection of focal mechanism nodal planes. We find a systematic rotation of the maximum horizontal stress orientation (SHmax) across a 1000 km width of the Midcontinent. We find that SHmax rotates from N60E to E/W orientation across the southern Illinois basin and returns to N60E in the western Appalachian basin. The stress regime is largely consistent with strike-slip faulting with pockets of a reverse-faulting stress regime near the

  20. Association of comorbidity burden with abnormal cardiac mechanics: findings from the HyperGEN study.

    PubMed

    Selvaraj, Senthil; Aguilar, Frank G; Martinez, Eva E; Beussink, Lauren; Kim, Kwang-Youn A; Peng, Jie; Rasmussen-Torvik, Laura; Sha, Jin; Irvin, Marguerite R; Gu, C Charles; Lewis, Cora E; Hunt, Steven C; Arnett, Donna K; Shah, Sanjiv J

    2014-04-29

    Comorbidities are common in heart failure (HF), and the number of comorbidities has been associated with poor outcomes in HF patients. However, little is known about the effect of multiple comorbidities on cardiac mechanics, which could impact the pathogenesis of HF. We sought to determine the relationship between comorbidity burden and adverse cardiac mechanics. We performed speckle-tracking analysis on echocardiograms from the HyperGEN study (n=2150). Global longitudinal, circumferential, and radial strain, and early diastolic (e') tissue velocities were measured. We evaluated the association between comorbidity number and cardiac mechanics using linear mixed effects models to account for relatedness among subjects. The mean age was 51 ± 14 years, 58% were female, and 47% were African American. Dyslipidemia and hypertension were the most common comorbidities (61% and 58%, respectively). After adjusting for left ventricular (LV) mass index, ejection fraction, and several potential confounders, the number of comorbidities remained associated with all indices of cardiac mechanics except global circumferential strain (eg, β=-0.32 [95% CI -0.44, -0.20] per 1-unit increase in number of comorbidities for global longitudinal strain; β=-0.16 [95% CI -0.20, -0.11] for e' velocity; P ≤ 0.0001 for both comparisons). Results were similar after excluding participants with abnormal LV geometry (P<0.05 for all comparisons). Higher comorbidity burden is associated with worse cardiac mechanics, even in the presence of normal LV geometry. The deleterious effect of multiple comorbidities on cardiac mechanics may explain both the high comorbidity burden and adverse outcomes in patients who ultimately develop HF.

  1. Aroma Effects on Physiologic and Cognitive Function Following Acute Stress: A Mechanism Investigation

    PubMed Central

    Oken, Barry S.

    2016-01-01

    Abstract Objective: Aromas may improve physiologic and cognitive function after stress, but associated mechanisms remain unknown. This study evaluated the effects of lavender aroma, which is commonly used for stress reduction, on physiologic and cognitive functions. The contribution of pharmacologic, hedonic, and expectancy-related mechanisms of the aromatherapy effects was evaluated. Methods: Ninety-two healthy adults (mean age, 58.0 years; 79.3% women) were randomly assigned to three aroma groups (lavender, perceptible placebo [coconut], and nonperceptible placebo [water] and to two prime subgroups (primed, with a suggestion of inhaling a powerful stress-reducing aroma, or no prime). Participants' performance on a battery of cognitive tests, physiologic responses, and subjective stress were evaluated at baseline and after exposure to a stress battery during which aromatherapy was present. Participants also rated the intensity and pleasantness of their assigned aroma. Results: Pharmacologic effects of lavender but not placebo aromas significantly benefited post-stress performance on the working memory task (F(2, 86) = 5.41; p = 0.006). Increased expectancy due to positive prime, regardless of aroma type, facilitated post-stress performance on the processing speed task (F(1, 87) = 8.31; p = 0.005). Aroma hedonics (pleasantness and intensity) played a role in the beneficial lavender effect on working memory and physiologic function. Conclusions: The observable aroma effects were produced by a combination of mechanisms involving aroma-specific pharmacologic properties, aroma hedonic properties, and participant expectations. In the future, each of these mechanisms could be manipulated to produce optimal functioning. PMID:27355279

  2. Mechanisms of Adaptation to Nitrosative Stress in Bacillus subtilis▿ †

    PubMed Central

    Rogstam, Annika; Larsson, Jonas T.; Kjelgaard, Peter; von Wachenfeldt, Claes

    2007-01-01

    Bacteria use a number of mechanisms for coping with the toxic effects exerted by nitric oxide (NO) and its derivatives. Here we show that the flavohemoglobin encoded by the hmp gene has a vital role in an adaptive response to protect the soil bacterium Bacillus subtilis from nitrosative stress. We further show that nitrosative stress induced by the nitrosonium cation donor sodium nitroprusside (SNP) leads to deactivation of the transcriptional repressor NsrR, resulting in derepression of hmp. Nitrosative stress induces the sigma B-controlled general stress regulon. However, a sigB null mutant did not show increased sensitivity to SNP, suggesting that the sigma B-dependent stress proteins are involved in a nonspecific protection against stress whereas the Hmp flavohemoglobin plays a central role in detoxification. Mutations in the yjbIH operon, which encodes a truncated hemoglobin (YjbI) and a predicted 34-kDa cytosolic protein of unknown function (YjbH), rendered B. subtilis hypersensitive to SNP, suggesting roles in nitrosative stress management. PMID:17293416

  3. Stress transfer mechanisms at the submicron level for graphene/polymer systems.

    PubMed

    Anagnostopoulos, George; Androulidakis, Charalampos; Koukaras, Emmanuel N; Tsoukleri, Georgia; Polyzos, Ioannis; Parthenios, John; Papagelis, Konstantinos; Galiotis, Costas

    2015-02-25

    The stress transfer mechanism from a polymer substrate to a nanoinclusion, such as a graphene flake, is of extreme interest for the production of effective nanocomposites. Previous work conducted mainly at the micron scale has shown that the intrinsic mechanism of stress transfer is shear at the interface. However, since the interfacial shear takes its maximum value at the very edge of the nanoinclusion it is of extreme interest to assess the effect of edge integrity upon axial stress transfer at the submicron scale. Here, we conduct a detailed Raman line mapping near the edges of a monolayer graphene flake that is simply supported onto an epoxy-based photoresist (SU8)/poly(methyl methacrylate) matrix at steps as small as 100 nm. We show for the first time that the distribution of axial strain (stress) along the flake deviates somewhat from the classical shear-lag prediction for a region of ∼ 2 μm from the edge. This behavior is mainly attributed to the presence of residual stresses, unintentional doping, and/or edge effects (deviation from the equilibrium values of bond lengths and angles, as well as different edge chiralities). By considering a simple balance of shear-to-normal stresses at the interface we are able to directly convert the strain (stress) gradient to values of interfacial shear stress for all the applied tensile levels without assuming classical shear-lag behavior. For large flakes a maximum value of interfacial shear stress of 0.4 MPa is obtained prior to flake slipping.

  4. Stress Transfer Mechanisms at the Submicron Level for Graphene/Polymer Systems

    PubMed Central

    2015-01-01

    The stress transfer mechanism from a polymer substrate to a nanoinclusion, such as a graphene flake, is of extreme interest for the production of effective nanocomposites. Previous work conducted mainly at the micron scale has shown that the intrinsic mechanism of stress transfer is shear at the interface. However, since the interfacial shear takes its maximum value at the very edge of the nanoinclusion it is of extreme interest to assess the effect of edge integrity upon axial stress transfer at the submicron scale. Here, we conduct a detailed Raman line mapping near the edges of a monolayer graphene flake that is simply supported onto an epoxy-based photoresist (SU8)/poly(methyl methacrylate) matrix at steps as small as 100 nm. We show for the first time that the distribution of axial strain (stress) along the flake deviates somewhat from the classical shear-lag prediction for a region of ∼2 μm from the edge. This behavior is mainly attributed to the presence of residual stresses, unintentional doping, and/or edge effects (deviation from the equilibrium values of bond lengths and angles, as well as different edge chiralities). By considering a simple balance of shear-to-normal stresses at the interface we are able to directly convert the strain (stress) gradient to values of interfacial shear stress for all the applied tensile levels without assuming classical shear-lag behavior. For large flakes a maximum value of interfacial shear stress of 0.4 MPa is obtained prior to flake slipping. PMID:25644121

  5. Antagonistic interplay between hypocretin and leptin in the lateral hypothalamus regulates stress responses.

    PubMed

    Bonnavion, Patricia; Jackson, Alexander C; Carter, Matthew E; de Lecea, Luis

    2015-02-19

    The hypothalamic-pituitary-adrenal (HPA) axis functions to coordinate behavioural and physiological responses to stress in a manner that depends on the behavioural state of the organism. However, the mechanisms through which arousal and metabolic states influence the HPA axis are poorly understood. Here using optogenetic approaches in mice, we show that neurons that produce hypocretin (Hcrt)/orexin in the lateral hypothalamic area (LHA) regulate corticosterone release and a variety of behaviours and physiological hallmarks of the stress response. Interestingly, we found that Hcrt neuronal activity and Hcrt-mediated stress responses were inhibited by the satiety hormone leptin, which acts, in part, through a network of leptin-sensitive neurons in the LHA. These data demonstrate how peripheral metabolic signals interact with hypothalamic neurons to coordinate stress and arousal and suggest one mechanism through which hyperarousal or altered metabolic states may be linked with abnormal stress responses.

  6. Physiological, Biochemical, and Molecular Mechanisms of Heat Stress Tolerance in Plants

    PubMed Central

    Hasanuzzaman, Mirza; Nahar, Kamrun; Alam, Md. Mahabub; Roychowdhury, Rajib; Fujita, Masayuki

    2013-01-01

    High temperature (HT) stress is a major environmental stress that limits plant growth, metabolism, and productivity worldwide. Plant growth and development involve numerous biochemical reactions that are sensitive to temperature. Plant responses to HT vary with the degree and duration of HT and the plant type. HT is now a major concern for crop production and approaches for sustaining high yields of crop plants under HT stress are important agricultural goals. Plants possess a number of adaptive, avoidance, or acclimation mechanisms to cope with HT situations. In addition, major tolerance mechanisms that employ ion transporters, proteins, osmoprotectants, antioxidants, and other factors involved in signaling cascades and transcriptional control are activated to offset stress-induced biochemical and physiological alterations. Plant survival under HT stress depends on the ability to perceive the HT stimulus, generate and transmit the signal, and initiate appropriate physiological and biochemical changes. HT-induced gene expression and metabolite synthesis also substantially improve tolerance. The physiological and biochemical responses to heat stress are active research areas, and the molecular approaches are being adopted for developing HT tolerance in plants. This article reviews the recent findings on responses, adaptation, and tolerance to HT at the cellular, organellar, and whole plant levels and describes various approaches being taken to enhance thermotolerance in plants. PMID:23644891

  7. Effects and mechanisms of caffeine to improve immunological and metabolic abnormalities in diet-induced obese rats.

    PubMed

    Liu, Chih-Wei; Tsai, Hung-Cheng; Huang, Chia-Chang; Tsai, Chang-Youh; Su, Yen-Bo; Lin, Ming-Wei; Lee, Kuei-Chuan; Hsieh, Yun-Cheng; Li, Tzu-Hao; Huang, Shiang-Fen; Yang, Ying-Ying; Hou, Ming-Chih; Lin, Han-Chieh; Lee, Fa-Yauh; Lee, Shou-Dong

    2018-05-01

    In obesity, there are no effective therapies for parallel immune and metabolic abnormalities, including systemic/tissue insulin-resistance/inflammation, adiposity and hepatic steatosis. Caffeine has anti-inflammation, antihepatic steatosis, and anti-insulin resistance effects. In this study, we evaluated the effects and molecular mechanisms of 6 wk of caffeine treatment (HFD-caf) on immunological and metabolic abnormalities of high-fat diet (HFD)-induced obese rats. Compared with HFD vehicle (HFD-V) rats, in HFD-caf rats the suppressed circulating immune cell inflammatory [TNFα, MCP-1, IL-6, intercellular adhesion molecule 1 (ICAM-1), and nitrite] profiles were accompanied by decreased liver, white adipose tissue (WAT), and muscle macrophages and their intracellular cytokine levels. Metabolically, the increase in metabolic rates reduced lipid accumulation in various tissues, resulting in reduced adiposity, lower fat mass, decreased body weight, amelioration of hepatic steatosis, and improved systemic/muscle insulin resistance. Further mechanistic approaches revealed an upregulation of tissue lipogenic [(SREBP1c, fatty acid synthase, acetyl-CoA carboxylase)/insulin-sensitizing (GLUT4 and p-IRS1)] markers in HFD-caf rats. Significantly, ex vivo experiments revealed that the cytokine release by the cocultured peripheral blood mononuclear cell (monocyte) and WAT (adipocyte), which are known to stimulate macrophage migration and hepatocyte lipogenesis, were lower in HFD-V groups than HFD-caf groups. Caffeine treatment simultaneously ameliorates immune and metabolic pathogenic signals present in tissue to normalize immunolgical and metabolic abnormalities found in HFD-induced obese rats.

  8. Mechanisms of food processing and storage-related stress tolerance in Clostridium botulinum.

    PubMed

    Dahlsten, Elias; Lindström, Miia; Korkeala, Hannu

    2015-05-01

    Vegetative cultures of Clostridium botulinum produce the extremely potent botulinum neurotoxin, and may jeopardize the safety of foods unless sufficient measures to prevent growth are applied. Minimal food processing relies on combinations of mild treatments, primarily to avoid deterioration of the sensory qualities of the food. Tolerance of C. botulinum to minimal food processing is well characterized. However, data on effects of successive treatments on robustness towards further processing is lacking. Developments in genetic manipulation tools and the availability of annotated genomes have allowed identification of genetic mechanisms involved in stress tolerance of C. botulinum. Most studies focused on low temperature, and the importance of various regulatory mechanisms in cold tolerance of C. botulinum has been demonstrated. Furthermore, novel roles in cold tolerance were shown for metabolic pathways under the control of these regulators. A role for secondary oxidative stress in tolerance to extreme temperatures has been proposed. Additionally, genetic mechanisms related to tolerance to heat, low pH, and high salinity have been characterized. Data on genetic stress-related mechanisms of psychrotrophic Group II C. botulinum strains are scarce; these mechanisms are of interest for food safety research and should thus be investigated. This minireview encompasses the importance of C. botulinum as a food safety hazard and its central physiological characteristics related to food-processing and storage-related stress. Special attention is given to recent findings considering genetic mechanisms C. botulinum utilizes in detecting and countering these adverse conditions. Copyright © 2014 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  9. Mechanical stress induces neuroendocrine and immune responses of sea cucumber ( Apostichopus japonicus)

    NASA Astrophysics Data System (ADS)

    Tan, Jie; Li, Fenghui; Sun, Huiling; Gao, Fei; Yan, Jingping; Gai, Chunlei; Chen, Aihua; Wang, Qingyin

    2015-04-01

    Grading procedure in routine sea cucumber hatchery production is thought to affect juvenile sea cucumber immunological response. The present study investigated the impact of a 3-min mechanical perturbation mimicking the grading procedure on neuroendocrine and immune parameters of the sea cucumber Apostichopus japonicus. During the application of stress, concentrations of noradrenaline and dopamine in coelomic fluid increased significantly, indicating that the mechanical perturbation resulted in a transient state of stress in sea cucumbers. Coelomocytes concentration in coelomic fluid increased transiently after the beginning of stressing, and reached the maximum in 1 h. Whereas, coelomocytes phagocytosis at 3 min, superoxide anion production from 3 min to 0.5 h, acid phosphatase activity at 0.5 h, and phenoloxidase activity from 3 min to 0.5 h were all significantly down-regulated. All of the immune parameters recovered to baseline levels after the experiment was conducted for 8 h, and an immunostimulation occurred after the stress considering the phagocytosis and acid phosphatase activity. The results suggested that, as in other marine invertebrates, neuroendocrine/immune connections exist in sea cucumber A. japonicus. Mechanical stress can elicit a profound influence on sea cucumber neuroendocrine system. Neuroendocrine messengers act in turn to modulate the immunity functions. Therefore, these effects should be considered for developing better husbandry procedures.

  10. Thermo-mechanical stress analysis of cryopreservation in cryobags and the potential benefit of nanowarming.

    PubMed

    Solanki, Prem K; Bischof, John C; Rabin, Yoed

    2017-06-01

    Cryopreservation by vitrification is the only promising solution for long-term organ preservation which can save tens of thousands of lives across the world every year. One of the challenges in cryopreservation of large-size tissues and organs is to prevent fracture formation due to the tendency of the material to contract with temperature. The current study focuses on a pillow-like shape of a cryobag, while exploring various strategies to reduce thermo-mechanical stress during the rewarming phase of the cryopreservation protocol, where maximum stresses are typically found. It is demonstrated in this study that while the level of stress may generally increase with the increasing amount of CPA filled in the cryobag, the ratio between width and length of the cryobag play a significant role. Counterintuitively, the overall maximum stress is not found when the bag is filled to its maximum capacity (when the filled cryobag resembles a sphere). Parametric investigation suggests that reducing the initial rewarming rate between the storage temperature and the glass transition temperature may dramatically decrease the thermo-mechanical stress. Adding a temperature hold during rewarming at the glass transition temperature may reduce the thermo-mechanical stress in some cases, but may have an adverse effect in other cases. Finally, it is demonstrated that careful incorporation of volumetric heating by means on nanoparticles in an alternating magnetic field, or nanowarming, can dramatically reduce the resulting thermo-mechanical stress. These observations display the potential benefit of a thermo-mechanical design of the cryopreservation protocols in order to prevent structural damage. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. The nature of neuroendocrine abnormalities in depression: a controversial issue in contemporary psychiatry.

    PubMed

    von Zerssen, D; Berger, M; Dose, M; Doerr, P; Krieg, C; Bossert, S; Riemann, D; Pirke, K M; Dolhofer, R; Müller, O A

    1986-01-01

    Neuroendocrine abnormalities in depression have been regarded, by many authors, as relatively specific markers of nosological subtypes of the disorder, e.g. primary vs. secondary, endogenous vs. non-endogenous or unipolar vs. bipolar depression. They should reflect the same changes in central neurotransmitters (e.g. noradrenergic insufficiency and/or cholinergic hyperactivity) that were hypothesized as the cause of clinical symptoms. This view is challenged on the basis of our own neuroendocrine investigations in 317 psychiatric patients and 103 normal controls. According to these studies the abnormalities are nosologically rather unspecific. They are induced by a large variety of factors, e.g. emotional stress associated with the clinical symptomatology, weight loss due to malnutrition as a consequence of reduced appetite, medication and drug withdrawal. Stress-induced hypercortisolism appears to be the most common abnormality that may trigger other neuroendocrine dysfunctions, such as a blunted TSH response to TRH. Differences in neuroendocrine abnormalities of depressives are probably due to variations in the manifold factors influencing the hormonal axes involved, to temporal changes in hormonal patterns (e.g. one abnormality triggering another) and to individual differences in the basic activity and the responsiveness of the various axes.

  12. Ageing under mechanical stress: first experiments for a silver based multilayer mirror

    NASA Astrophysics Data System (ADS)

    Lalo, Arnaud; Ravel, Guillaume; Ignat, Michel; Cousin, Bernard; Swain, Michael V.

    2017-11-01

    Improving materials and devices reliability is a major concern to the spatial industry. Results are reported for satellite mirrors-like specimens consisting in oxide-protected metal systems. Optical coatings were deposited by electron beam evaporation. Mechanical stress fields in multi-layered materials play an important role. The stress state can have far-reaching implications both in kinetics and thermodynamics. Therefore an integrated apparatus with four-point bending equipment was designed. The technique allowed us to exert stress into a film or a system of films on a substrate concurrently with thermal treatment. In order to achieve the first tests performed with the help of the apparatus, various preliminary characterizations were required. The article reports the preliminary micro-mechanical testing of the materials (ultra micro-indentation to evaluate the elastic modulus of the samples materials and wafer curvature technique to determine the specimen residual stress) and the first ageing experiment. Experimental evidence of accelerated ageing under stress is successfully reported.

  13. Cadherin-11 modulates cell morphology and collagen synthesis in periodontal ligament cells under mechanical stress.

    PubMed

    Feng, Lishu; Zhang, Yimei; Kou, Xiaoxing; Yang, Ruili; Liu, Dawei; Wang, Xuedong; Song, Yang; Cao, Haifeng; He, Danqing; Gan, Yehua; Zhou, Yanheng

    2017-03-01

    To examine the role of cadherin-11, an integral membrane adhesion molecule, in periodontal ligament cells (PDLCs) under mechanical stimulation. Human PDLCs were cultured and subjected to mechanical stress. Cadherin-11 expression and cell morphology of PDLCs were investigated via immunofluorescence staining. The mRNA and protein expressions of cadherin-11 and type I collagen (Col-I) of PDLCs were evaluated by quantitative real-time polymerase chain reaction and Western blot, respectively. Small interfering RNA was used to knock down cadherin-11 expression in PDLCs. The collagen matrix of PDLCs was examined using toluidine blue staining. Cadherin-11 was expressed in PDLCs. Mechanical stress suppressed cadherin-11 expression in PDLCs with prolonged force treatment time and increased force intensity, accompanied by suppressed β-catenin expression. Simultaneously, mechanical stress altered cell morphology and repressed Col-I expression in a time- and dose-dependent manner in PDLCs. Moreover, knockdown of cadherin-11 with suppressed β-catenin expression resulted in altered PDLC morphology and repressed collagen expression, which were consistent with the changes observed under mechanical stress. Results of this study suggest that cadherin-11 is expressed in PDLCs and modulates PDLC morphology and collagen synthesis in response to mechanical stress, which may play an important role in the homeostasis and remodeling of the PDL under mechanical stimulation.

  14. Mapping Nondominant Voices into Understanding Stress-Coping Mechanisms

    ERIC Educational Resources Information Center

    Iwasaki, Yoshitaka; Bartlett, Judith; MacKay, Kelly; Mactavish, Jennifer; Ristock, Janice

    2008-01-01

    This study reports key findings from a research project, which examined the stress and coping mechanisms of several nondominant groups of individuals. The groups were based in Winnipeg, Manitoba, Canada and included (a) Aboriginal individuals with diabetes, (b) individuals with disabilities, and (c) gays and lesbians. Our analyses of personal…

  15. Pathogenic Cx31 is un/misfolded to cause skin abnormality via a Fos/JunB-mediated mechanism.

    PubMed

    Tang, Chengyuan; Chen, Xiang; Chi, Jingwei; Yang, Dawei; Liu, Shu; Liu, Mujun; Pan, Qian; Fan, Jianbing; Wang, Danling; Zhang, Zhuohua

    2015-11-01

    Mutations in connexin-31 (Cx31) are associated with multiple human diseases, including familial erythrokeratodermia variabilis (EKV). The pathogenic mechanism of EKV-associated Cx31 mutants remains largely elusive. Here, we show that EKV-pathogenic Cx31 mutants are un/misfolded and temperature sensitive. In Drosophila, expression of pathogenic Cx31, but not wild-type Cx31, causes depigmentation and degeneration of ommatidia that are rescued by expression of either dBip or dHsp70. Ectopic expression of Cx31 in mouse skin results in skin abnormalities resembling human EKV. The affected tissues show remarkable disrupted gap junction formation and significant upregulation of chaperones Bip and Hsp70 as well as AP-1 proteins c-Fos and JunB, in addition to molecular signatures of skin diseases. Consistently, c-Fos, JunB, Bip and Hsp70 are strikingly higher in keratinocytes of EKV patients than their matched control individuals. Furthermore, a druggable AP-1 inhibitory small molecule suppresses skin phenotype and pathological abnormalities of transgenic Cx31 mice. The study suggests that Cx31 mutant proteins are un/misfolded to cause EKV likely via an AP-1-mediated mechanism and identifies a small molecule with therapeutic potential of the disease. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  16. Illustrating the Molecular Origin of Mechanical Stress in Ductile Deformation of Polymer Glasses.

    PubMed

    Li, Xiaoxiao; Liu, Jianning; Liu, Zhuonan; Tsige, Mesfin; Wang, Shi-Qing

    2018-02-16

    New experiments show that tensile stress vanishes shortly after preyield deformation of polymer glasses while tensile stress after postyield deformation stays high and relaxes on much longer time scales, thus hinting at a specific molecular origin of stress in ductile cold drawing: chain tension rather than intersegmental interactions. Molecular dynamics simulation based on a coarse-grained model for polystyrene confirms the conclusion that the chain network plays an essential role, causing the glassy state to yield and to respond with a high level of intrachain retractive stress. This identification sheds light on the future development regarding an improved theoretical account for molecular mechanics of polymer glasses and the molecular design of stronger polymeric materials to enhance their mechanical performance.

  17. Illustrating the Molecular Origin of Mechanical Stress in Ductile Deformation of Polymer Glasses

    NASA Astrophysics Data System (ADS)

    Li, Xiaoxiao; Liu, Jianning; Liu, Zhuonan; Tsige, Mesfin; Wang, Shi-Qing

    2018-02-01

    New experiments show that tensile stress vanishes shortly after preyield deformation of polymer glasses while tensile stress after postyield deformation stays high and relaxes on much longer time scales, thus hinting at a specific molecular origin of stress in ductile cold drawing: chain tension rather than intersegmental interactions. Molecular dynamics simulation based on a coarse-grained model for polystyrene confirms the conclusion that the chain network plays an essential role, causing the glassy state to yield and to respond with a high level of intrachain retractive stress. This identification sheds light on the future development regarding an improved theoretical account for molecular mechanics of polymer glasses and the molecular design of stronger polymeric materials to enhance their mechanical performance.

  18. Phospholipase C as a potential target for cardioprotection during oxidative stress.

    PubMed

    Tappia, Paramjit S; Asemu, Girma; Rodriguez-Leyva, Delfin

    2010-03-01

    Cardiac dysfunction due to ischemia-reperfusion (I/R) is associated with marked changes in membrane function and subsequent Ca2+-handling abnormalities in cardiomyocytes. The membrane abnormalities in hearts subjected to I/R arise primarily from oxidative stress as a consequence of increased formation of reactive oxygen species and other oxidants, as well as reduced antioxidant defenses. Little is known, however, about the nature and mechanisms of the sarcolemmal membrane changes with respect to phospholipase C (PLC)-related signaling events. In addition, the mechanisms involved in protection of the postischemic myocardium and in ischemic preconditioning with respect to PLC function need to be established. Accordingly, this article reviews the historical and current information on PLC-mediated signal transduction mechanisms in I/R, as well as outlining future directions that should be addressed. Such information will extend our knowledge of ischemic heart disease and help improve its therapy.

  19. Numerical Study on the Thermal Stress and its Formation Mechanism of a Thermoelectric Device

    NASA Astrophysics Data System (ADS)

    Pan, Tao; Gong, Tingrui; Yang, Wei; Wu, Yongjia

    2018-06-01

    The strong thermo-mechanical stress is one of the most critical failure mechanisms that affect the durability of thermoelectric devices. In this study, numerical simulations on the formation mechanism of the maximum thermal stress inside the thermoelectric device have been performed by using finite element method. The influences of the material properties and the thermal radiation on the thermal stress have been examined. The results indicate that the maximum thermal stress was located at the contact position between the two materials and occurred due to differential thermal expansions and displacement constraints of the materials. The difference in the calculated thermal stress value between the constant and the variable material properties was between 3% and 4%. At a heat flux of 1 W·cm-2 and an emissivity of 0.5, the influence of the radiation heat transfer on the thermal stress was only about 5%; however, when the heat flux was 20 W·cm-2 and the emissivity was 0.7, the influence of the radiation heat transfer was more than 30%.

  20. Neonatal handling (resilience) attenuates water-avoidance stress induced enhancement of chronic mechanical hyperalgesia in the rat

    PubMed Central

    Alvarez, Pedro; Levine, Jon D.; Green, Paul G.

    2015-01-01

    Chronic stress is well known to exacerbate pain. We tested the hypothesis that neonatal handling, which induces resilience to the negative impact of stress by increasing the quality and quantity of maternal care, attenuates the mechanical hyperalgesia produced by water-avoidance stress in the adult rat. Neonatal male rats underwent the handling protocol on postnatal days 2–9, weaned at 21 days and tested for muscle mechanical nociceptive threshold at postnatal days 50–75. Decrease in mechanical nociceptive threshold in skeletal muscle in adult rats, produced by exposure to water-avoidance stress, was significantly attenuated by neonatal handling. Neonatal handling also attenuated the mechanical hyperalgesia produced by intramuscular administration of the pronociceptive inflammatory mediator, prostaglandin E2 in rats exposed as adults to water-avoidance stress. Neonatal handling, which induces a smaller corticosterone response in adult rats exposed to a stressor as well as changes in central nervous system neurotransmitter systems, attenuates mechanical hyperalgesia produced by water-avoidance stress and enhanced prostaglandin hyperalgesia in adult animals. PMID:25637700

  1. Role of connexin43 hemichannels in mechanical stress-induced ATP release in human periodontal ligament cells.

    PubMed

    Luckprom, P; Kanjanamekanant, K; Pavasant, P

    2011-10-01

    Our previous studies showed that mechanical stress could induce ATP release in human periodontal ligament (HPDL) cells. By signaling through P2 purinergic receptors, ATP increased the expression and the synthesis of osteopontin and RANKL. In this study, the mechanism of stress-induced ATP release was investigated. Continuous compressive forces were applied on cultured HPDL cells. The ATP released was measured using luciferin-luciferase bioluminescence. The expression of gap-junction proteins was examined using RT-PCR and western blot analysis. The opening of hemichannels was demonstrated by cellular uptake of a fluorescent dye, 5(6)-carboxyfluorescein, which is known to penetrate hemichannels. Intracellular signal transduction was investigated using inhibitors and antagonists. Mechanical stress induced the release of ATP into the culture medium, which was attenuated by carbenoxolone, a nonspecific gap-junction inhibitor. Addition of meclofenamic acid sodium salt, a connexin43 inhibitor, inhibited ATP release by mechanical stress. Knockdown of connexin43 expression by small interfering RNA reduced the amount of ATP released by mechanical stress, suggesting the role of connexin43 hemichannels. In addition, intracellular Ca(2+) blockers could also inhibit mechanical stress-induced ATP release and the opening of the gap junction. Our study demonstrated the involvement of gap-junction hemichannels, especially connexin43, in the stress-induced ATP-release mechanism. Furthermore, this mechanism may be regulated by the intracellular Ca(2+) signaling pathway. These results suggest an important role of gap-junction hemichannels in the function and behavior of HPDL cells. © 2011 John Wiley & Sons A/S.

  2. Thermal stress characterization using the electro-mechanical impedance method

    NASA Astrophysics Data System (ADS)

    Zhu, Xuan; Lanza di Scalea, Francesco; Fateh, Mahmood

    2017-04-01

    This study examines the potential of the Electro-Mechanical Impedance (EMI) method to provide an estimation of the developed thermal stress in constrained bar-like structures. This non-invasive method features the easiness of implementation and interpretation, while it is notoriously known for being vulnerable to environmental variability. A comprehensive analytical model is proposed to relate the measured electric admittance signatures of the PZT element to temperature and uniaxial stress applied to the underlying structure. The model results compare favorably to the experimental ones, where the sensitivities of features extracted from the admittance signatures to the varying stress levels and temperatures are determined. Two temperature compensation frameworks are proposed to characterize the thermal stress states: (a) a regression model is established based on temperature-only tests, and the residuals from the thermal stress tests are then used to isolate the stress measurand; (b) the temperature-only tests are decomposed by Principle Components Analysis (PCA) and the feature vectors of the thermal stress tests are reconstructed after removal of the temperaturesensitive components. For both methods, the features were selected based on their performance in Receiver Operating Characteristic (ROC) curves. Experimental results on the Continuous Welded Rails (CWR) are shown to demonstrate the effectiveness of these temperature compensation methods.

  3. Understanding brassinosteroid-regulated mechanisms to improve stress tolerance in plants: a critical review.

    PubMed

    Nawaz, Fahim; Naeem, Muhammad; Zulfiqar, Bilal; Akram, Asim; Ashraf, Muhammad Yasin; Raheel, Muhammad; Shabbir, Rana Nauman; Hussain, Rai Altaf; Anwar, Irfan; Aurangzaib, Muhammad

    2017-07-01

    Brassinosteroids (BRs) are steroidal plant hormones involved in regulation of physiological and molecular processes to ameliorate various biotic and abiotic stresses. Exogenous application of BRs to improve stress tolerance in plants has recently become a high research priority. Several studies have revealed the involvement of these steroidal hormones in upregulation of stress-related defense genes and their cross talk with other metabolic pathways. This is likely to stimulate research on many unanswered questions regarding their role in enhancing the ability of plants to tolerate adverse environmental conditions. Thus, this review appraises new insights on mechanisms mediating BR-regulated changes in plants, focused mainly on their involvement in regulation of physiological and molecular mechanisms under stress conditions. Herein, examples of BR-stimulated modulation of antioxidant defense system and upregulation of transcription factors in plants exposed to various biotic (bacterial, viral, and fungal attack) and abiotic stresses (drought, salinity, heat, low temperature, and heavy metal stress) are discussed. Based on these insights, future research in the current direction can be helpful to increase our understanding of BR-mediated complex and interrelated processes under stress conditions.

  4. Stress Response Mechanisms: From Single Cells to Multinational Organizations

    PubMed Central

    Pech, Richard J.

    2006-01-01

    Can a literal comparison be made between biological phenomena in organisms and phenomena in human organizations? The evidence provided by simplified but useful examples appears to suggest that a phenomenon simulating hormesis can and does occur in organizational contexts. Similarities between stress response behaviors of organisms and stress response behaviors in organizations are discussed. Cellular stress response mechanisms stimulate and repair, as well as defend the organism against further attacks. Organizational hormesis describes actions that stimulate the organization by increasing its focus and protecting it against future attacks. The common aim for the organism as well as the organization is to increase the probability of survival. The following describes examples of organizational survival that demonstrate a number of hormetic parallels between organisms and organisations. PMID:18648597

  5. Mechanical tensile stress effects on the expression of bone sialoprotein in bovine cementoblasts.

    PubMed

    Yu, Hongyou; Ren, Yijin; Sandham, Andrew; Ren, Aishu; Huang, Lan; Bai, Ding

    2009-03-01

    To develop a new cementoblast culture method and to detect bone sialoprotein (BSP) expression in response to high and low mechanical tensile stress in cementoblast in vitro. Cementoblasts were collected from the roots of newborn bovine teeth and were identified with cementum-derived attachment protein (CAP) antibody 3G9. Cell proliferation was evaluated by MTT [3-(4,5-dimethylthazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay, and mineralization was confirmed by von Kossa staining. Mechanical tensile stress was applied in vitro to the cementoblast with the use of a uniaxial four-point bending system with 2000 or 4000 microstrains, at a frequency of 0.5 Hz for 3, 6, 12, 24, or 36 hours. BSP mRNA level was quantified by real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). A large amount of cementoblast was observed to be expressing CAP. Cementoblasts had a proliferation tendency similar to that of osteoblasts but different from that of periodontal ligament (PDL) cells. Cementoblasts had the ability to become mineralized between osteoblasts and PDL cells. The mechanical tensile stress significantly up-regulated BSP mRNA expression, which reached a peak at 24 hours in both 2000 and 4000 microstrain groups (P < .01) and was tenfold and sixfold higher than that of controls, respectively. BSP expression dropped toward baseline levels at 36 hours in both groups. Mechanical tensile stress up-regulated the expression of BSP. Low mechanical tensile stress induced earlier and more intensive up-regulation of BSP mRNA; this might represent the optimal stimuli for cementoblast activity.

  6. Force control of endothelium permeability in mechanically stressed pulmonary micro-vascular endothelial cells.

    PubMed

    Wang, Bin; Caluch, Adam; Fodil, Redouane; Féréol, Sophie; Zadigue, Patricia; Pelle, Gabriel; Louis, Bruno; Isabey, Daniel

    2012-01-01

    Mechanical factors play a key role in the pathogenesis of Acute Respiratory Distress Syndrome (ARDS) and Ventilator-Induced Lung Injury (VILI) as contributing to alveolo-capillary barrier dysfunction. This study aims at elucidating the role of the cytoskeleton (CSK) and cell-matrix adhesion system in the stressed endothelium and more precisely in the loss of integrity of the endothelial barrier. We purposely develop a cellular model made of a monolayer of confluent Human Pulmonary Microvascular Endothelial Cells (HPMVECs) whose cytoskeleton (CSK) is directly exposed to sustained cyclic mechanical stress for 1 and 2 h. We used RGD-coated ferromagnetic beads and measured permeability before and after stress application. We find that endothelial permeability increases in the stressed endothelium, hence reflecting a loss of integrity. Structural and mechanical results suggest that this endothelial barrier alteration would be due to physically-founded discrepancies in latero-basal reinforcement of adhesion sites in response to the global increase in CSK stiffness or centripetal intracellular forces. Basal reinforcement of adhesion is presently evidenced by the marked redistribution of αvβ3 integrin with cluster formation in the stressed endothelium.

  7. Endoplasmic reticulum stress related molecular mechanisms in nonalcoholic fatty liver disease (NAFLD).

    PubMed

    Wang, Lifeng; Chen, J; Ning, C; Lei, D; Ren, Jun

    2018-05-16

    Non-alcoholic fatty liver disease (NAFLD) has emerged as a common public health problem and a common cause of chronic liver diseases. However, the underlying mechanisms leading to the development and progression of NAFLD remain elusive. Accumulating evidence has depicted an essential role for endoplasmic reticulum (ER) stress in the development of steatosis and later progression into nonalcoholic steatohepatitis and hepatocarcinoma. With the accumulation of unfolded and misfolded proteins in the ER lumen, ER stress is provoked to turn on the unfolded protein response (UPR). ER stress triggers a cascade reaction of transcriptional and translational events that restore ER homeostasis, promoting cell survival and adaptation. However, prolonged ER stress may be transit physiological mechanisms to pathological consequences, including insulin resistance, fat accumulation, inflammation, apoptosis, and autophagy, all of which with important roles in the development of NAFLD. Therefore, understanding the role of ER stress in the onset and pathogenesis of NAFLD is pertinent to the management of this devastating metabolic disease. Here we will summarize available information on recent findings linking ER stress to the pathogenesis of NAFLD. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  8. Comment on “Models of stochastic, spatially varying stress in the crust compatible with focal‐mechanism data, and how stress inversions can be biased toward the stress rate” by Deborah Elaine Smith and Thomas H. Heaton

    USGS Publications Warehouse

    Hardebeck, Jeanne L.

    2015-01-01

    This model makes specific predictions about the orientations and heterogeneity of earthquake focal mechanisms. Smith and Heaton (2011) attempt to validate this heterogeneous stress model using observations of earthquake focal‐mechanism variability from Hardebeck (2006). They then demonstrate that the model predicts a bias in the orientations of earthquake focal mechanisms, which are biased away from the background stress and toward the stressing rate. They suggest the focal‐mechanism bias in this model invalidates the large body of work over the last several decades, that has inferred stress orientations from the inversion of earthquake focal mechanisms. The question of whether or not the Smith and Heaton (2011) model is applicable to the real Earth is therefore important not only for understanding spatial stress variability but also for evaluating the numerous studies that have inferred crustal stress orientations from earthquake focal mechanisms (e.g., as compiled by Heidbach et al., 2008).

  9. The relationship between water loss, mechanical stress, and molecular structure of human stratum corneum ex vivo.

    PubMed

    Vyumvuhore, Raoul; Tfayli, Ali; Biniek, Krysta; Duplan, Hélène; Delalleau, Alexandre; Manfait, Michel; Dauskardt, Reinhold; Baillet-Guffroy, Arlette

    2015-03-01

    Proper hydration of the stratum corneum (SC) is important for maintaining skin's vital functions. Water loss causes development of drying stresses, which can be perceived as 'tightness', and plays an important role in dry skin damage processes. However, molecular structure modifications arising from water loss and the subsequent development of stress has not been established. We investigated the drying stress mechanism by studying, ex vivo, the behaviors of the SC components during water desorption from initially fully hydrated samples using Raman spectroscopy. Simultaneously, we measure the SC mechanical stress with a substrate curvature instrument. Very good correlations of water loss to the mechanical stress of the stratum corneum were obtained, and the latter was found to depend mainly on the unbound water fraction. In addition to that, the water loss is accompanied with an increase of lipids matrix compactness characterized by lower chain freedom, while protein structure showed an increase in amount of α-helices, a decline in α-sheets, and an increase in folding in the tertiary structure of keratin. The drying process of SC involves a complex interplay of water binding, molecular modifications, and mechanical stress. This article provides a better understanding of the molecular mechanism associated to SC mechanics. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Reproduction in shark-attacked sea turtles is supported by stress-reduction mechanisms.

    PubMed Central

    Jessop, Tim; Sumner, Joanna; Lance, Val; Limpus, Col

    2004-01-01

    Vertebrates exhibit varied behavioural and physiological tactics to promote reproductive success. We examined mechanisms that could enable female loggerhead turtles to undertake nesting activities and maintain seasonal reproduction despite recent shark injuries of varying severity. We proposed that endocrinal mechanisms that regulate both a turtle's stress response and reproductive ability are modified to promote successful and continued reproduction. Irrespective of the degree of injury, females did not exhibit increased levels of the stress hormone corticosterone, nor decreased levels of the reproductive steroid testosterone; hormone responses consistent with stress. When exposed to a capture stressor, females with shark injury did not exhibit any greater corticosterone response than controls. In addition, breeding females showed a reduced corticosterone stress response compared to non-breeding females. Reduced endocrinal responses following shark injury, and during breeding in general may, in part, enable females to maintain behavioural and physiological commitment to reproduction. PMID:15101429

  11. Mechanical stress activates NMDA receptors in the absence of agonists.

    PubMed

    Maneshi, Mohammad Mehdi; Maki, Bruce; Gnanasambandam, Radhakrishnan; Belin, Sophie; Popescu, Gabriela K; Sachs, Frederick; Hua, Susan Z

    2017-01-03

    While studying the physiological response of primary rat astrocytes to fluid shear stress in a model of traumatic brain injury (TBI), we found that shear stress induced Ca 2+ entry. The influx was inhibited by MK-801, a specific pore blocker of N-Methyl-D-aspartic acid receptor (NMDAR) channels, and this occurred in the absence of agonists. Other NMDA open channel blockers ketamine and memantine showed a similar effect. The competitive glutamate antagonists AP5 and GluN2B-selective inhibitor ifenprodil reduced NMDA-activated currents, but had no effect on the mechanically induced Ca 2+ influx. Extracellular Mg 2+ at 2 mM did not significantly affect the shear induced Ca 2+ influx, but at 10 mM it produced significant inhibition. Patch clamp experiments showed mechanical activation of NMDAR and inhibition by MK-801. The mechanical sensitivity of NMDARs may play a role in the normal physiology of fluid flow in the glymphatic system and it has obvious relevance to TBI.

  12. Stress Field in Brazil with Focal Mechanism: Regional and Local Patterns

    NASA Astrophysics Data System (ADS)

    Dias, F.; Assumpcao, M.

    2013-05-01

    The knowledge of stress field is fundamental not only to understand driving forces and plate deformation but also in the study of intraplate seismicity. The stress field in Brazil has been determined mainly using focal mechanisms and a few breakout data and in-situ measurements. However the stress field still is poorly known in Brazil. The focal mechanisms of recent earthquakes (magnitude lower than 5 mb) were studied using waveform modeling. We stacked the record of several teleseismic stations ( delta > 30°) stacked groups of stations separated according to distance and azimuth. Every record was visually inspected and those with a good signal/noise ratio (SNR) were grouped in windows of ten degrees distance and stacked. The teleseismic P-wave of the stacked signals was modeled using the hudson96 program of Herrmann seismology package (Herrmann, 2002) and the consistency of focal mechanism with the first-motion was checked. Some events in central Brazil were recorded by closer stations (~ 1000 km) and the moment tensor was determined with the ISOLA code (Sokos & Zahradnik, 2008). With the focal mechanisms available in literature and those obtained in this work, we were able to identify some patterns: the central region shows a purely compressional pattern (E-W SHmax), which is predicted by regional theoretical models (Richardson & Coblentz, 1996 and the TD0 model of Lithgow & Bertelloni, 2004). Meanwhile in the Amazon we find an indication of SHmax oriented in the SE-NW direction, probably caused by the Caribbean plate interaction (Meijer, 1995). In northern coastal region, the compression rotates following the coastline, which indicates an important local component related to spreading effects at the continental/oceanic transition (Assumpção, 1998) and flexural stresses caused by sedimentary load in Amazon Fan. We determine the focal mechanism of several events in Brazil using different techniques according to the available data. The major difficulty is to

  13. Stress-related disorders, pituitary adenylate cyclase-activating peptide (PACAP)ergic system, and sex differences.

    PubMed

    Ramikie, Teniel S; Ressler, Kerry J

    2016-12-01

    Trauma-related disorders, such as posttraumatic stress disorder (PTSD) are remarkably common and debilitating, and are often characterized by dysregulated threat responses. Across numerous epidemiological studies, females have been found to have an approximately twofold increased risk for PTSD and other stress-related disorders. Understanding the biological mechanisms of this differential risk is of critical importance. Recent data suggest that the pituitary adenylate cyclase-activating polypeptide (PACAP) pathway is a critical regulator of the stress response across species. Moreover, increasing evidence suggests that this pathway is regulated by both stress and estrogen modulation and may provide an important window into understanding mechanisms of sex differences in the stress response. We have recently shown that PACAP and its receptor (PAC1R) are critical mediators of abnormal processes after psychological trauma. Notably, in heavily traumatized human subjects, there appears to be a robust sex-specific association of PACAP blood levels and PAC1R gene variants with fear physiology, PTSD diagnosis, and symptoms, specifically in females. The sex-specific association occurs within a single-nucleotide polymorphism (rs2267735) that resides in a putative estrogen response element involved in PAC1R gene regulation. Complementing these human data, the PAC1R messenger RNA is induced with fear conditioning or estrogen replacement in rodent models. These data suggest that perturbations in the PACAP-PAC1R pathway are regulated by estrogen and are involved in abnormal fear responses underlying PTSD.

  14. Emotion Dysregulation as a Mechanism Linking Stress Exposure to Adolescent Aggressive Behavior

    ERIC Educational Resources Information Center

    Herts, Kate L.; McLaughlin, Katie A.; Hatzenbuehler, Mark L.

    2012-01-01

    Exposure to stress is associated with a wide range of internalizing and externalizing problems in adolescents, including aggressive behavior. Extant research examining mechanisms underlying the associations between stress and youth aggression has consistently identified social information processing pathways that are disrupted by exposure to…

  15. Analysis of electrolyte abnormalities and the mechanisms leading to arrhythmias in heart failure. A literature review.

    PubMed

    Urso, C; Canino, B; Brucculeri, S; Firenze, A; Caimi, G

    2016-01-01

    About 50% of deaths from heart failure (HF) are sudden, presumably referable to arrhythmias. Electrolyte and acid-base abnormalities are a frequent and potentially dangerous complication in HF patients. Their incidence is almost always correlated with the severity of cardiac dysfunction; furthermore leading to arrhythmias, these imbalances are associated with a poor prognosis. The frequency of ventricular ectopic beats and sudden cardiac death correlate with both plasma and whole body levels of potassium, especially in alkalemia. The early recognition of these alterations and the knowledge of the pathophysiological mechanisms are useful for the management of these HF patients.

  16. The mechanical properties of infrainguinal vascular bypass grafts: their role in influencing patency.

    PubMed

    Sarkar, S; Salacinski, H J; Hamilton, G; Seifalian, A M

    2006-06-01

    When autologous vein is unavailable, prosthetic graft materials, particularly expanded polytetrafluoroethylene are used for peripheral arterial revascularisation. Poor long term patency of prosthetic materials is due to distal anastomotic intimal hyperplasia. Intimal hyperplasia is directly linked to shear stress abnormalities at the vessel wall. Compliance and calibre mismatch between native vessel and graft, as well as anastomotic line stress concentration contribute towards unnatural wall shear stress. High porosity reduces graft compliance by causing fibrovascular infiltration, whereas low porosity discourages the development of an endothelial lining and hence effective antithrombogenicity. Therefore, consideration of mechanical properties is necessary in graft development. Current research into synthetic vascular grafts concentrates on simulating the mechanical properties of native arteries and tissue engineering aims to construct a new biological arterial conduit.

  17. Stress and Asthma: Novel Insights on Genetic, Epigenetic and Immunologic Mechanisms

    PubMed Central

    Rosenberg, Stacy L.; Miller, Gregory E.; Brehm, John M.; Celedón, Juan C.

    2014-01-01

    In the United States, the economically disadvantaged and some ethnic minorities are often exposed to chronic psychosocial stressors and disproportionately affected by asthma. Current evidence suggests a causal association between chronic psychosocial stress and asthma or asthma morbidity. Recent findings suggest potential mechanisms underlying this association, including changes in the methylation and expression of genes that regulate behavioral, autonomic, neuroendocrine, and immunologic responses to stress. There is also evidence suggesting the existence of susceptibility genes that predispose chronically stressed youth to both post-traumatic stress disorder and asthma. In this review, we critically examine published evidence and suggest future directions for research in this field. PMID:25129683

  18. Monitoring the effect of mechanical stress on mesenchymal stem cell collagen production by multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Chen, Wei-Liang; Chang, Chia-Cheng; Chiou, Ling-Ling; Li, Tsung-Hsien; Liu, Yuan; Lee, Hsuan-Shu; Dong, Chen-Yuan

    2008-02-01

    Tissue engineering is emerging as a promising method for repairing damaged tissues. Due to cartilage's common wear and injury, in vitro production of cartilage replacements have been an active area of research. Finding the optimal condition for the generation of the collagen matrix is crucial in reproducing cartilages that closely match those found in human. Using multiphoton autofluorescence and second-harmonic generation (SHG) microscopy we monitored the effect of mechanical stress on mesenchymal stem cell collagen production. Bone marrow mesenchymal stem cells in the form of pellets were cultured and periodically placed under different mechanical stress by centrifugation over a period of four weeks. The differently stressed samples were imaged several times during the four week period, and the collagen production under different mechanical stress is characterized.

  19. Crack-jump mechanism of microvein formation and its implications for stress cyclicity during extension fracturing

    NASA Astrophysics Data System (ADS)

    Caputo, Riccardo; Hancock, Paul L.

    1998-11-01

    It is well accepted and documented that faulting is produced by the cyclic behaviour of a stress field. Some extension fractures, such as veins characterised by the crack-seal mechanism, have also been presumed to result from repeated stress cycles. In the present note, some commonly observed field phenomena and relationships such as hackle marks and vein and joint spacing, are employed to argue that a stress field can also display cyclic behaviour during extensional fracturing. Indeed, the requirement of critical stress conditions for the occurrence of extensional failure events does not accord with the presence of contemporaneously open nearby parallel fractures. Therefore, because after each fracture event there is stress release within the surrounding volume of rock, high density sets of parallel extensional fractures also strongly support the idea that rocks undergo stress cyclicity during jointing and veining. A comparison with seismological data from earthquakes with dipole mechanical solutions, confirms that this process presently occurs at depth in the Earth crust. Furthermore, in order to explain dense sets of hair-like closely spaced microveins, a crack-jump mechanism is introduced here as an alternative to the crack-seal mechanism. We also propose that as a consequence of medium-scale stress cyclicity during brittle deformation, the re-fracturing of a rock mass occurs in either one or the other of these two possible ways depending on the ratio between the elastic parameters of the sealing material and those of the host rock. The crack-jump mechanism occurs when the former is stronger.

  20. The sex differences in nature of vascular endothelial stress: nitrergic mechanisms

    NASA Astrophysics Data System (ADS)

    Sindeev, Sergey; Gekaluyk, Artem; Ulanova, Maria; Agranovich, Ilana; Sharref, Ali Esmat; Semyachkina-Glushkovskaya, Oxana

    2016-04-01

    Here we studied the role of nitric oxide in cardiovascular regulation in male and female hypertensive rats under normal and stress conditions. We found that the severity of hypertension in females was lower than in males. Hypertensive females demonstrated more favorable pattern of cardiovascular responses to stress. Nitric oxide blockade by NG-nitro-L-arginine methyl ester (L-NAME) increased the mean arterial pressure and decreased the heart rate more effectively in females than in males. During stress, L-NAME modified the stress-induced cardiovascular responses more significantly in female compared with male groups. Our data show that hypertensive females demonstrated the more effective nitric oxide control of cardiovascular activity under normal and especially stress conditions than male groups. This sex differences may be important mechanism underlying greater in females vs. males stress-resistance of cardiovascular system and hypertension formation.

  1. Developmental abnormalities of the posterior pituitary gland.

    PubMed

    di Iorgi, Natascia; Secco, Andrea; Napoli, Flavia; Calandra, Erika; Rossi, Andrea; Maghnie, Mohamad

    2009-01-01

    While the molecular mechanisms of anterior pituitary development are now better understood than in the past, both in animals and in humans, little is known about the mechanisms regulating posterior pituitary development. The posterior pituitary gland is formed by the evagination of neural tissue from the floor of the third ventricle. It consists of the distal axons of the hypothalamic magnocellular neurones that shape the neurohypophysis. After its downward migration, it is encapsulated together with the ascending ectodermal cells of Rathke's pouch which form the anterior pituitary. By the end of the first trimester, this development is completed and vasopressin and oxytocin can be detected in neurohypophyseal tissue. Abnormal posterior pituitary migration such as the ectopic posterior pituitary lobe appearing at the level of median eminence or along the pituitary stalk have been reported in idiopathic GH deficiency or in subjects with HESX1, LHX4 and SOX3 gene mutations. Another intriguing feature of abnormal posterior pituitary development involves genetic forms of posterior pituitary neurodegeneration that have been reported in autosomal-dominant central diabetes insipidus and Wolfram disease. Defining the phenotype of the posterior pituitary gland can have significant clinical implications for management and counseling, as well as providing considerable insight into normal and abnormal mechanisms of posterior pituitary development in humans.

  2. Increased global transcription activity as a mechanism of replication stress in cancer

    PubMed Central

    Kotsantis, Panagiotis; Silva, Lara Marques; Irmscher, Sarah; Jones, Rebecca M.; Folkes, Lisa; Gromak, Natalia; Petermann, Eva

    2016-01-01

    Cancer is a disease associated with genomic instability that often results from oncogene activation. This in turn leads to hyperproliferation and replication stress. However, the molecular mechanisms that underlie oncogene-induced replication stress are still poorly understood. Oncogenes such as HRASV12 promote proliferation by upregulating general transcription factors to stimulate RNA synthesis. Here we investigate whether this increase in transcription underlies oncogene-induced replication stress. We show that in cells overexpressing HRASV12, elevated expression of the general transcription factor TATA-box binding protein (TBP) leads to increased RNA synthesis, which together with R-loop accumulation results in replication fork slowing and DNA damage. Furthermore, overexpression of TBP alone causes the hallmarks of oncogene-induced replication stress, including replication fork slowing, DNA damage and senescence. Consequently, we reveal that increased transcription can be a mechanism of oncogene-induced DNA damage, providing a molecular link between upregulation of the transcription machinery and genomic instability in cancer. PMID:27725641

  3. Increased global transcription activity as a mechanism of replication stress in cancer.

    PubMed

    Kotsantis, Panagiotis; Silva, Lara Marques; Irmscher, Sarah; Jones, Rebecca M; Folkes, Lisa; Gromak, Natalia; Petermann, Eva

    2016-10-11

    Cancer is a disease associated with genomic instability that often results from oncogene activation. This in turn leads to hyperproliferation and replication stress. However, the molecular mechanisms that underlie oncogene-induced replication stress are still poorly understood. Oncogenes such as HRAS V12 promote proliferation by upregulating general transcription factors to stimulate RNA synthesis. Here we investigate whether this increase in transcription underlies oncogene-induced replication stress. We show that in cells overexpressing HRAS V12 , elevated expression of the general transcription factor TATA-box binding protein (TBP) leads to increased RNA synthesis, which together with R-loop accumulation results in replication fork slowing and DNA damage. Furthermore, overexpression of TBP alone causes the hallmarks of oncogene-induced replication stress, including replication fork slowing, DNA damage and senescence. Consequently, we reveal that increased transcription can be a mechanism of oncogene-induced DNA damage, providing a molecular link between upregulation of the transcription machinery and genomic instability in cancer.

  4. Exercise offers anxiolytic potential: A role for stress and brain noradrenergic-galaninergic mechanisms

    PubMed Central

    Sciolino, Natale R.; Holmes, Philip V.

    2016-01-01

    Although physical activity reduces anxiety in humans, the neural basis for this response is unclear. Rodent models are essential to understand the mechanisms that underlie the benefits of exercise. However, it is controversial whether exercise exerts anxiolytic-like potential in rodents. Evidence is reviewed to evaluate the effects of wheel running, an experimental mode of exercise in rodents, on behavior in tests of anxiety and on norepinephrine and galanin systems in neural circuits that regulate stress. Stress is proposed to account for mixed behavioral findings in this literature. Indeed, running promotes an adaptive response to stress and alters anxiety-like behaviors in a manner dependent on stress. Running amplifies galanin expression in noradrenergic locus coeruleus (LC) and suppresses stress-induced activity of the LC and norepinephrine output in LC-target regions. Thus, enhanced galanin-mediated suppression of brain norepinephrine in runners is supported by current literature as a mechanism that may contribute to the stress-protective effects of exercise. These data support the use of rodents to study the emotional and neurobiological consequences of exercise. PMID:22771334

  5. Sirt1 Protects against Oxidative Stress-Induced Apoptosis in Fibroblasts from Psoriatic Patients: A New Insight into the Pathogenetic Mechanisms of Psoriasis.

    PubMed

    Becatti, Matteo; Barygina, Victoria; Mannucci, Amanda; Emmi, Giacomo; Prisco, Domenico; Lotti, Torello; Fiorillo, Claudia; Taddei, Niccolò

    2018-05-25

    Psoriasis, a multisystem chronic disease characterized by abnormal keratinocyte proliferation, has an unclear pathogenesis where systemic inflammation and oxidative stress play mutual roles. Dermal fibroblasts, which are known to provide a crucial microenvironment for epidermal keratinocyte function, represented the selected experimental model in our study which aimed to clarify the potential role of SIRT1 in the pathogenetic mechanisms of the disease. We firstly detected the presence of oxidative stress (lipid peroxidation and total antioxidant capacity), significantly reduced SIRT1 expression level and activity, mitochondrial damage and apoptosis (caspase-3, -8 and -9 activities) in psoriatic fibroblasts. Upon SIRT1 activation, redox balance was re-established, mitochondrial function was restored and apoptosis was no longer evident. Furthermore, we examined p38, ERK and JNK activation, which was strongly altered in psoriatic fibroblasts, in response to SIRT1 activation and we measured caspase-3 activity in the presence of specific MAPK inhibitors demonstrating the key role of the SIRT1 pathway against apoptotic cell death via MAPK modulation. Our results clearly demonstrate the involvement of SIRT1 in the protective mechanisms related to fibroblast injury in psoriasis. SIRT1 activation exerts an active role in restoring both mitochondrial function and redox balance via modulation of MAPK signaling. Hence, SIRT1 can be proposed as a specific tool for the treatment of psoriasis.

  6. Mechanisms of Local Stress Sensing in Multifunctional Polymer Films Using Fluorescent Tetrapod Nanocrystals

    DOE PAGES

    Raja, Shilpa N.; Zherebetskyy, Danylo; Wu, Siva; ...

    2016-07-13

    Nanoscale stress-sensing can be used across fields ranging from detection of incipient cracks in structural mechanics to monitoring forces in biological tissues. We demonstrate how tetrapod quantum dots (tQDs) embedded in block copolymers act as sensors of tensile/compressive stress. Remarkably, tQDs can detect their own composite dispersion and mechanical properties with a switch in optomechanical response when tQDs are in direct contact. Using experimental characterizations, atomistic simulations and finite-element analyses, we show that under tensile stress, densely packed tQDs exhibit a photoluminescence peak shifted to higher energies ("blue-shift") due to volumetric compressive stress in their core; loosely packed tQDs exhibitmore » a peak shifted to lower energies ("red-shift") from tensile stress in the core. The stress shifts result from the tQD's unique branched morphology in which the CdS arms act as antennas that amplify the stress in the CdSe core. Our nanocomposites exhibit excellent cyclability and scalability with no degraded properties of the host polymer. Colloidal tQDs allow sensing in many materials to potentially enable autoresponsive, smart structural nanocomposites that self-predict upcoming fracture.« less

  7. Stress and strain analysis from dynamic loads of mechanical hand using finite element method

    NASA Astrophysics Data System (ADS)

    Hasanuddin, Iskandar; Husaini; Syahril Anwar, M.; Yudha, B. Z. Sandy; Akhyar, Hasan

    2018-05-01

    This research discusses the distribution of stress and strain due to the dynamic loads of mechanical hand. The stress and strain that occur on mechanical hand are the main concern for comparing the value of finite element analysis (FEA) and calculating for its material properties. The stress and strain analysis are done with a loading condition. The given loading condition is dynamic. The loading input condition in the simulation of using hydraulic hand dynamometer is from the grip strength measurement of ten samples. The form of the given loading to the mechanical hand is the increment value with a maximum of 708 N/m2 within 1 minute. The amount of maximum stress (von Mises) simulation is 1.731 x 105 Pa, and the amount of maximum strain is 7.441 x 10-7. The amount of maximum reaction force is 5.864 x 10-2 N, while the amount of maximum displacement that occurs on the distal part is 1.223 x 10 m. Based on the analysis, the maximum stress and strain were found both to occur at the extension part. The result of this study has shown that the stress and strain still occur far below from the yield strength and the shear strength from the material AISI 1010. It can be concluded that the mechanical hand is durable for the given loading and can hold an object with a minimum diameter of 45 mm.

  8. Emotion Dysregulation as a Mechanism Linking Stress Exposure to Adolescent Aggressive Behavior

    PubMed Central

    McLaughlin, Katie A.; Hatzenbuehler, Mark L.

    2012-01-01

    Exposure to stress is associated with a wide range of internalizing and externalizing problems in adolescents, including aggressive behavior. Extant research examining mechanisms underlying the associations between stress and youth aggression has consistently identified social information processing pathways that are disrupted by exposure to violence and increase risk of aggressive behavior. In the current study, we use longitudinal data to examine emotion dysregulation as a potential mechanism linking a broader range of stressful experiences to aggressive behavior in a diverse sample of early adolescents (N=1065). Specifically, we examined the longitudinal associations of peer victimization and stressful life events with emotion dysregulation and aggressive behavior. Structural equation modeling was used to create latent constructs of emotion dysregulation and aggression. Both stressful life events and peer victimization predicted subsequent increases in emotion dysregulation over a 4-month period. These increases in emotion dysregulation, in turn, were associated with increases in aggression over the subsequent 3 months. Longitudinal mediation models showed that emotion dysregulation mediated the relationship of both peer victimization (z=2.35, p=0.019) and stressful life events (z=2.32, p=0.020) with aggressive behavior. Increasing the use of adaptive emotion regulation strategies is an important target for interventions aimed at preventing the onset of adolescent aggressive behavior. PMID:22466516

  9. Environmental stress and epigenetic transgenerational inheritance.

    PubMed

    Skinner, Michael K

    2014-09-05

    Previous studies have shown a wide variety of environmental toxicants and abnormal nutrition can promote the epigenetic transgenerational inheritance of disease. More recently a number of studies have indicated environmental stress can also promote epigenetic alterations that are transmitted to subsequent generations to induce pathologies. A recent study by Yao and colleagues demonstrated gestational exposure to restraint stress and forced swimming promoted preterm birth risk and adverse newborn outcomes generationally. This ancestral stress promoted the epigenetic transgenerational inheritance of abnormalities in the great-grand offspring of the exposed gestating female. Several studies now support the role of environmental stress in promoting the epigenetic transgenerational inheritance of disease. Observations suggest ancestral environmental stress may be a component of disease etiology in the current population.

  10. Retinal abnormalities in β-thalassemia major

    PubMed Central

    Bhoiwala, Devang L.; Dunaief, Joshua L.

    2015-01-01

    Patients with beta (β)-thalassemia (β-TM: thalassemia major, β-TI: thalassemia intermedia) have a variety of complications that may affect all organs, including the eye. Ocular abnormalities include retinal pigment epithelium degeneration, angioid streaks, venous tortuosity, night blindness, visual field defects, decreased visual acuity, color vision abnormalities, and acute visual loss. Patients with β-TM are transfusion dependent and require iron chelation therapy (ICT) in order to survive. Retinal degeneration may result from either retinal iron accumulation from transfusion-induced iron overload or retinal toxicity induced by ICT. Some who were never treated with ICT exhibited retinopathy, and others receiving ICT had chelator-induced retinopathy. We will focus on retinal abnormalities present in individuals with β-TM viewed in light of new findings on the mechanisms and manifestations of retinal iron toxicity. PMID:26325202

  11. Diverticular Disease of the Colon: Neuromuscular Function Abnormalities.

    PubMed

    Bassotti, Gabrio; Villanacci, Vincenzo; Bernardini, Nunzia; Dore, Maria P

    2016-10-01

    Colonic diverticular disease is a frequent finding in daily clinical practice. However, its pathophysiological mechanisms are largely unknown. This condition is likely the result of several concomitant factors occurring together to cause anatomic and functional abnormalities, leading as a result to the outpouching of the colonic mucosa. A pivotal role seems to be played by an abnormal colonic neuromuscular function, as shown repeatedly in these patients, and by an altered visceral perception. There is recent evidence that these abnormalities might be related to the derangement of the enteric innervation, to an abnormal distribution of mucosal neuropeptides, and to low-grade mucosal inflammation. The latter might be responsible for the development of visceral hypersensitivity, often causing abdominal pain in a subset of these patients.

  12. Overuse injuries: tendinopathies, stress fractures, compartment syndrome, and shin splints.

    PubMed

    Wilder, Robert P; Sethi, Shikha

    2004-01-01

    Approximately 50% of all sports injuries are secondary to overuse and result from repetitive microtrauma that causes local tissue damage. Injuries are most likely with changes in mode, intensity, or duration of training and can accumulate before symptoms appear. Intrinsic factors contributing to injuries are individual bio-mechanical abnormalities such as malalignments, muscle imbalance, inflexibility, weakness, and instability. Contributing extrinsic (avoidable) factors include poor technique, improper equipment, and improper changes in duration or frequency of activity. Injuries are often related to biomechanical abnormalities removed from the specific injury site, requiring evaluation of the entire kinetic chain. This article discusses common overuse injuries of the lower leg, ankle, and foot: tendinopathies, stress fractures, chronic exertional compartment syndrome, and shin splints.

  13. Mechanical stress activates NMDA receptors in the absence of agonists

    PubMed Central

    Maneshi, Mohammad Mehdi; Maki, Bruce; Gnanasambandam, Radhakrishnan; Belin, Sophie; Popescu, Gabriela K.; Sachs, Frederick; Hua, Susan Z.

    2017-01-01

    While studying the physiological response of primary rat astrocytes to fluid shear stress in a model of traumatic brain injury (TBI), we found that shear stress induced Ca2+ entry. The influx was inhibited by MK-801, a specific pore blocker of N-Methyl-D-aspartic acid receptor (NMDAR) channels, and this occurred in the absence of agonists. Other NMDA open channel blockers ketamine and memantine showed a similar effect. The competitive glutamate antagonists AP5 and GluN2B-selective inhibitor ifenprodil reduced NMDA-activated currents, but had no effect on the mechanically induced Ca2+ influx. Extracellular Mg2+ at 2 mM did not significantly affect the shear induced Ca2+ influx, but at 10 mM it produced significant inhibition. Patch clamp experiments showed mechanical activation of NMDAR and inhibition by MK-801. The mechanical sensitivity of NMDARs may play a role in the normal physiology of fluid flow in the glymphatic system and it has obvious relevance to TBI. PMID:28045032

  14. Impact of mechanical stress induced in silica vacuum windows on laser-induced damage.

    PubMed

    Gingreau, Clémence; Lanternier, Thomas; Lamaignère, Laurent; Donval, Thierry; Courchinoux, Roger; Leymarie, Christophe; Néauport, Jérôme

    2018-04-15

    At the interface between vacuum and air, optical windows must keep their optical properties, despite being subjected to mechanical stress. In this Letter, we investigate the impact of such stress on the laser-induced damage of fused silica windows at the wavelength of 351 nm in the nanosecond regime. Different stress values, from 1 to 30 MPa, both tensile and compressive, were applied. No effect of the stress on the laser-induced damage was evidenced.

  15. Neuroimaging in Posttraumatic Stress Disorder and Other Stress-related Disorders

    PubMed Central

    Bremner, J. Douglas

    2009-01-01

    Synopsis Traumatic stress has a broad range of effects on the brain. Brain areas implicated in the stress response include the amygdala, hippocampus, and prefrontal cortex. Studies in patients with posttraumatic stress disorder (PTSD) and other psychiatric disorders related to stress have replicated findings in animal studies by finding alterations in these brain areas. Brain regions implicated in PTSD also play an important role in memory function, highlighting the important interplay between memory and the traumatic stress response. Abnormalities in these brain areas are hypothesized to underlie symptoms of PTSD and other stress-related psychiatric disorders. PMID:17983968

  16. Stress tensor analysis in the Taiwan area from focal mechanisms of earthquakes

    NASA Astrophysics Data System (ADS)

    Yih-Hsiung, Yeh; Eric, Barrier; Cheng-Horng Lin; Jacques, Angelier

    1991-12-01

    We produce a map of the stress pattern in and around Taiwan based on 200 earthquake focal mechanism solutions. These solutions were determined by using data from Taiwan Telemetered Seismographic Network, microearthquake surveys and WWSSN. The stresses are derived through a minimization of angles between the slip vector and the shear stress on each nodal plane considered as a fault, employing appropriate weighting factors. The whole set of focal mechanisms is divided into several groups, mainly according to apparent clustering of the event locations. The results show that the direction of maximum principal stress in Taiwan area is nearly horizontal and SE-NW on average. This is in good agreement with the direction of relative motion between the Philippine Sea plate and the Eurasian plate. In western Taiwan, the fan-shaped distribution of the maximum principal stress is consistent with the direction of Philippine Sea-Eurasian plate convergence through a simple model of viscous material indented by a rigid wedge. In the northeastern part of Taiwan, a nearly horizontal minimum principal stress oriented N-S is found for shallow depths; it occurs in a region of low seismic velocities, probably related to the back-arc activity of the Okinawa Trough. Down-dip compressional and down-dip extensional stresses have been identified in different depth ranges within the subducting slab of the Philippine Sea plate in the northern Taiwan; this may reflect the slab characteristics in this area. A complex stress pattern prevails in the Hualien area, at the junction between the Ryukyu subduction system and the Taiwan collision zone.

  17. Effects, tolerance mechanisms and management of salt stress in grain legumes.

    PubMed

    Farooq, Muhammad; Gogoi, Nirmali; Hussain, Mubshar; Barthakur, Sharmistha; Paul, Sreyashi; Bharadwaj, Nandita; Migdadi, Hussein M; Alghamdi, Salem S; Siddique, Kadambot H M

    2017-09-01

    Salt stress is an ever-present threat to crop yields, especially in countries with irrigated agriculture. Efforts to improve salt tolerance in crop plants are vital for sustainable crop production on marginal lands to ensure future food supplies. Grain legumes are a fascinating group of plants due to their high grain protein contents and ability to fix biological nitrogen. However, the accumulation of excessive salts in soil and the use of saline groundwater are threatening legume production worldwide. Salt stress disturbs photosynthesis and hormonal regulation and causes nutritional imbalance, specific ion toxicity and osmotic effects in legumes to reduce grain yield and quality. Understanding the responses of grain legumes to salt stress and the associated tolerance mechanisms, as well as assessing management options, may help in the development of strategies to improve the performance of grain legumes under salt stress. In this manuscript, we discuss the effects, tolerance mechanisms and management of salt stress in grain legumes. The principal inferences of the review are: (i) salt stress reduces seed germination (by up to more than 50%) either by inhibiting water uptake and/or the toxic effect of ions in the embryo, (ii) salt stress reduces growth (by more than 70%), mineral uptake, and yield (by 12-100%) due to ion toxicity and reduced photosynthesis, (iii) apoplastic acidification is a good indicator of salt stress tolerance, (iv) tolerance to salt stress in grain legumes may develop through excretion and/or compartmentalization of toxic ions, increased antioxidant capacity, accumulation of compatible osmolytes, and/or hormonal regulation, (v) seed priming and nutrient management may improve salt tolerance in grain legumes, (vi) plant growth promoting rhizobacteria and arbuscular mycorrhizal fungi may help to improve salt tolerance due to better plant nutrient availability, and (vii) the integration of screening, innovative breeding, and the development of

  18. Protein kinase C and calcineurin cooperatively mediate cell survival under compressive mechanical stress.

    PubMed

    Mishra, Ranjan; van Drogen, Frank; Dechant, Reinhard; Oh, Soojung; Jeon, Noo Li; Lee, Sung Sik; Peter, Matthias

    2017-12-19

    Cells experience compressive stress while growing in limited space or migrating through narrow constrictions. To survive such stress, cells reprogram their intracellular organization to acquire appropriate mechanical properties. However, the mechanosensors and downstream signaling networks mediating these changes remain largely unknown. Here, we have established a microfluidic platform to specifically trigger compressive stress, and to quantitatively monitor single-cell responses of budding yeast in situ. We found that yeast senses compressive stress via the cell surface protein Mid2 and the calcium channel proteins Mid1 and Cch1, which then activate the Pkc1/Mpk1 MAP kinase pathway and calcium signaling, respectively. Genetic analysis revealed that these pathways work in parallel to mediate cell survival. Mid2 contains a short intracellular tail and a serine-threonine-rich extracellular domain with spring-like properties, and both domains are required for mechanosignaling. Mid2-dependent spatial activation of the Pkc1/Mpk1 pathway depolarizes the actin cytoskeleton in budding or shmooing cells, thereby antagonizing polarized growth to protect cells under compressive stress conditions. Together, these results identify a conserved signaling network responding to compressive mechanical stress, which, in higher eukaryotes, may ensure cell survival in confined environments.

  19. Molecular analysis of Hsp70 mechanisms in plants and their function in response to stress.

    PubMed

    Usman, Magaji G; Rafii, Mohd Y; Martini, Mohammad Y; Yusuff, Oladosu A; Ismail, Mohd R; Miah, Gous

    2017-04-01

    Studying the strategies of improving abiotic stress tolerance is quite imperative and research under this field will increase our understanding of response mechanisms to abiotic stress such as heat. The Hsp70 is an essential regulator of protein having the tendency to maintain internal cell stability like proper folding protein and breakdown of unfolded proteins. Hsp70 holds together protein substrates to help in movement, regulation, and prevent aggregation under physical and or chemical pressure. However, this review reports the molecular mechanism of heat shock protein 70 kDa (Hsp70) action and its structural and functional analysis, research progress on the interaction of Hsp70 with other proteins and their interaction mechanisms as well as the involvement of Hsp70 in abiotic stress responses as an adaptive defense mechanism.

  20. Stress and Anxious-Depressed Symptoms among Adolescents: Searching for Mechanisms of Risk.

    ERIC Educational Resources Information Center

    Grant, Kathryn E., Compas, Bruce E.

    1995-01-01

    Examined the possible mechanisms of risk among adolescents (n=55) exposed to the stress associated with the diagnosis of cancer in a parent. Girls whose mothers had cancer reported significantly more anxious-depressed symptoms than girls whose fathers were ill or boys whose mothers or fathers had cancer. Examines possible causes of stress in the…

  1. Residual Stress Induced Mechanical Property Enhancement in Steel Encapsulated Light Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Fudger, Sean James

    Macro hybridized systems consisting of steel encapsulated light metal matrix composites (MMCs) were produced with the goal of creating a low cost/light weight composite system with enhanced mechanical properties. MMCs are frequently incorporated into advanced material systems due to their tailorable material properties. However, they often have insufficient ductility for many structural applications. The macro hybridized systems take advantage of the high strength, modulus, and damage tolerance of steels and high specific stiffness and low density of MMCs while mitigating the high density of steels and the poor ductility of MMCs. Furthermore, a coefficient of thermal expansion (CTE) mismatch induced residual compressive stress method is utilized as a means of improving the ductility of the MMCs and overall efficiency of the macro hybridized systems. Systems consisting of an A36, 304 stainless steel, or NitronicRTM 50 stainless steel shell filled with an Al-SiC, Al-Al2O3, or Mg-B4C MMC are evaluated in this work. Upon cooling from processing temperatures, residual strains are generated due to a CTE mismatch between each of the phases. The resulting systems offer higher specific properties and a more structurally efficient system can be attained. Mechanical testing was performed and improvements in yield stress, ultimate tensile stress, and ductility were observed. However, the combination of these dissimilar materials often results in the formation of intermetallic compounds. In certain loading situations, these typically brittle intermetallic layers can result in degraded performance. X-ray Diffraction (XRD), X-ray Energy Dispersive Spectroscopy (EDS), and Electron Backscatter Diffraction (EBSD) are utilized to characterize the intermetallic layer formation at the interface between the steel and MMC. As the residual stress condition in each phase has a large impact on the mechanical property improvement, accurate quantification of these strains/stresses is

  2. Vessel abnormalization: another hallmark of cancer? Molecular mechanisms and therapeutic implications.

    PubMed

    De Bock, Katrien; Cauwenberghs, Sandra; Carmeliet, Peter

    2011-02-01

    As a result of excessive production of angiogenic molecules, tumor vessels become abnormal in structure and function. By impairing oxygen delivery, abnormal vessels fuel a vicious cycle of non-productive angiogenesis, which creates a hostile microenvironment from where tumor cells escape through leaky vessels and which renders tumors less responsive to chemoradiation. While anti-angiogenic strategies focused on inhibiting new vessel growth and destroying pre-existing vessels, clinical studies showed modest anti-tumor effects. For many solid tumors, anti-VEGF treatment offers greater clinical benefit when combined with chemotherapy. This is partly due to a normalization of the tumor vasculature, which improves cytotoxic drug delivery and efficacy and offers unprecedented opportunities for anti-cancer treatment. Here, we overview key novel molecular players that induce vessel normalization. Copyright © 2010 Elsevier Ltd. All rights reserved.

  3. Torsional bridge setup for the characterization of integrated circuits and microsensors under mechanical shear stress.

    PubMed

    Herrmann, M; Gieschke, P; Ruther, P; Paul, O

    2011-12-01

    We present a torsional bridge setup for the electro-mechanical characterization of devices integrated in the surface of silicon beams under mechanical in-plane shear stress. It is based on the application of a torsional moment to the longitudinal axis of the silicon beams, which results in a homogeneous in-plane shear stress in the beam surface. The safely applicable shear stresses span the range of ±50 MPa. Thanks to a specially designed clamping mechanism, the unintended normal stress typically stays below 2.5% of the applied shear stress. An analytical model is presented to compute the induced shear stress. Numerical computations verify the analytical results and show that the homogeneity of the shear stress is very high on the beam surface in the region of interest. Measurements with piezoresistive microsensors fabricated using a complementary metal-oxide-semiconductor process show an excellent agreement with both the computational results and comparative measurements performed on a four-point bending bridge. The electrical connection to the silicon beam is performed with standard bond wires. This ensures that minimal forces are applied to the beam by the electrical interconnection to the external instrumentation and that devices with arbitrary bond pad layout can be inserted into the setup.

  4. Neuroendocrine mechanisms for immune system regulation during stress in fish.

    PubMed

    Nardocci, Gino; Navarro, Cristina; Cortés, Paula P; Imarai, Mónica; Montoya, Margarita; Valenzuela, Beatriz; Jara, Pablo; Acuña-Castillo, Claudio; Fernández, Ricardo

    2014-10-01

    In the last years, the aquaculture crops have experienced an explosive and intensive growth, because of the high demand for protein. This growth has increased fish susceptibility to diseases and subsequent death. The constant biotic and abiotic changes experienced by fish species in culture are challenges that induce physiological, endocrine and immunological responses. These changes mitigate stress effects at the cellular level to maintain homeostasis. The effects of stress on the immune system have been studied for many years. While acute stress can have beneficial effects, chronic stress inhibits the immune response in mammals and teleost fish. In response to stress, a signaling cascade is triggered by the activation of neural circuits in the central nervous system because the hypothalamus is the central modulator of stress. This leads to the production of catecholamines, corticosteroid-releasing hormone, adrenocorticotropic hormone and glucocorticoids, which are the essential neuroendocrine mediators for this activation. Because stress situations are energetically demanding, the neuroendocrine signals are involved in metabolic support and will suppress the "less important" immune function. Understanding the cellular mechanisms of the neuroendocrine regulation of immunity in fish will allow the development of new pharmaceutical strategies and therapeutics for the prevention and treatment of diseases triggered by stress at all stages of fish cultures for commercial production. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Prenatal ethanol exposure-induced adrenal developmental abnormality of male offspring rats and its possible intrauterine programming mechanisms.

    PubMed

    Huang, Hegui; He, Zheng; Zhu, Chunyan; Liu, Lian; Kou, Hao; Shen, Lang; Wang, Hui

    2015-10-01

    Fetal adrenal developmental status is the major determinant of fetal tissue maturation and offspring growth. We have previously proposed that prenatal ethanol exposure (PEE) suppresses fetal adrenal corticosterone (CORT) synthesis. Here, we focused on PEE-induced adrenal developmental abnormalities of male offspring rats before and after birth, and aimed to explore its intrauterine programming mechanisms. A rat model of intrauterine growth retardation (IUGR) was established by PEE (4g/kg·d). In PEE fetus, increased serum CORT concentration and decreased insulin-like growth factor 1 (IGF1) concentration, with lower bodyweight and structural abnormalities as well as a decreased Ki67 expression (proliferative marker), were observed in the male fetal adrenal cortex. Adrenal glucocorticoid (GC)-metabolic activation system was enhanced while gene expression of IGF1 signaling pathway with steroidogenic acute regulatory protein (StAR), 3β-hydroxysteroid dehydrogenase (3β-HSD) was decreased. Furthermore, in the male adult offspring of PEE, serum CORT level was decreased but IGF1 was increased with partial catch-up growth, and Ki67 expression demonstrated no obvious change. Adrenal GC-metabolic activation system was inhibited, while IGF1 signaling pathway and 3β-HSD was enhanced with the steroidogenic factor 1 (SF1), and StAR was down-regulated in the adult adrenal. Based on these findings, we propose a "two-programming" mechanism for PEE-induced adrenal developmental toxicity: "the first programming" is a lower functional programming of adrenal steroidogenesis, and "the second programming" is GC-metabolic activation system-related GC-IGF1 axis programming. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Calcium-Mediated Oxidative Stress: a Common Mechanism in Tight Junction Disruption by Different Types of Cellular Stress

    PubMed Central

    Gangwar, Ruchika; Meena, Avtar S.; Shukla, Pradeep K.; Nagaraja, Archana S.; Dorniak, Piotr L.; Pallikuth, Sandeep; Waters, Christopher M.; Sood, Anil; Rao, RadhaKrishna

    2017-01-01

    The role of reactive oxygen species (ROS) in osmotic stress, dextran sulfate sodium (DSS) and cyclic stretch-induced tight junction disruption was investigated in Caco-2 cell monolayers in vitro, and restraint stress-induced barrier dysfunction in mouse colon in vivo. Live cell imaging showed that osmotic stress, cyclic stretch and DSS triggered rapid production of ROS in Caco-2 cell monolayers, which was blocked by depletion of intracellular Ca2+ by BAPTA. Knockdown of CaV1.3 or TRPV6 channels blocked osmotic stress and DSS-induced ROS production and attenuated tight junction disruption and barrier dysfunction. N-acetyl L-cysteine (NAC) and L-nitroarginine methyl ester (L-NAME) blocked stress-induced tight junction disruption and barrier dysfunction. NAC and L-NAME also blocked stress-induced activation of JNK and c-Src. ROS was co-localized with the mitochondrial marker in stressed cells. Cyclosporin A blocked osmotic stress and DSS-induced ROS production, barrier dysfunction, tight junction disruption and JNK activation. Mitochondria-targeted Mito-TEMPO blocked osmotic stress and DSS-induced barrier dysfunction and tight junction disruption. Chronic restraint stress in mice resulted in the elevation of intracellular Ca2+, activation of JNK and c-Src, and disruption of tight junction in the colonic epithelium. Furthermore, corticosterone administration induced JNK and c-Src activation, tight junction disruption and protein thiol oxidation in colonic mucosa. This study demonstrates that oxidative stress is a common signal in the mechanism of tight junction disruption in the intestinal epithelium by different types of cellular stress in vitro and bio behavioral stress in vivo. PMID:28057718

  7. Stress and asthma: novel insights on genetic, epigenetic, and immunologic mechanisms.

    PubMed

    Rosenberg, Stacy L; Miller, Gregory E; Brehm, John M; Celedón, Juan C

    2014-11-01

    In the United States the economically disadvantaged and some ethnic minorities are often exposed to chronic psychosocial stressors and disproportionately affected by asthma. Current evidence suggests a causal association between chronic psychosocial stress and asthma or asthma morbidity. Recent findings suggest potential mechanisms underlying this association, including changes in the methylation and expression of genes that regulate behavioral, autonomic, neuroendocrine, and immunologic responses to stress. There is also evidence suggesting the existence of susceptibility genes that predispose chronically stressed youth to both post-traumatic stress disorder and asthma. In this review we critically examine published evidence and suggest future directions for research in this field. Copyright © 2014 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

  8. Distinct hip and rearfoot kinematics in female runners with a history of tibial stress fracture.

    PubMed

    Milner, Clare E; Hamill, Joseph; Davis, Irene S

    2010-02-01

    Cross-sectional controlled laboratory study. To investigate the kinematics of the hip, knee, and rearfoot in the frontal and transverse planes in female distance runners with a history of tibial stress fracture. Tibial stress fractures are a common overuse injury in runners, accounting for up to half of all stress fractures. Abnormal kinematics of the lower extremity may contribute to abnormal musculoskeletal load distributions, leading to an increased risk of stress fractures. Thirty female runners with a history of tibial stress fracture were compared to 30 age-matched and weekly-running-distance-matched control subjects with no previous lower extremity bony injuries. Kinematic and kinetic data were collected using a motion capture system and a force platform, respectively, as subjects ran in the laboratory. Selected variables of interest were compared between the groups using a multivariate analysis of variance (MANOVA). Peak hip adduction and peak rearfoot eversion angles were greater in the stress fracture group compared to the control group. Peak knee adduction and knee internal rotation angles and all joint angles at impact peak were similar between the groups. Runners with a previous tibial stress fracture exhibited greater peak hip adduction and rearfoot eversion angles during the stance phase of running compared to healthy controls. A consequence of these mechanics may be altered load distribution within the lower extremity, predisposing individuals to stress fracture.

  9. Stress and PTSD Mechanisms as Targets for Pharmacotherapy of Alcohol Abuse, Addiction, and Relapse

    DTIC Science & Technology

    2015-10-01

    AWARD NUMBER: W81XWH-13-1-0126 TITLE: Stress and PTSD Mechanisms as Targets for Pharmacotherapy of Alcohol Abuse, Addiction, and Relapse...DATES COVERED 30 Sep 2014 - 29 Sep 2015 4. TITLE AND SUBTITLE Stress and PTSD Mechanisms as Targets for Pharmacotherapy of Alcohol Abuse, Addiction...demonstrated that alcohol -na"ive rats exhibiting high acoustic startle response (which is associated with increased anxiety-like behavior) develop

  10. Investigation of defect-induced abnormal body current in fin field-effect-transistors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Kuan-Ju; Tsai, Jyun-Yu; Lu, Ying-Hsin

    2015-08-24

    This letter investigates the mechanism of abnormal body current at the linear region in n-channel high-k/metal gate stack fin field effect transistors. Unlike body current, which is generated by impact ionization at high drain voltages, abnormal body current was found to increase with decreasing drain voltages. Notably, the unusual body leakage only occurs in three-dimensional structure devices. Based on measurements under different operation conditions, the abnormal body current can be attributed to fin surface defect-induced leakage current, and the mechanism is electron tunneling to the fin via the defects, resulting in holes left at the body terminal.

  11. Advances in understanding paternally transmitted Chromosomal Abnormalities

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Marchetti, F; Sloter, E; Wyrobek, A J

    2001-03-01

    Multicolor FISH has been adapted for detecting the major types of chromosomal abnormalities in human sperm including aneuploidies for clinically-relevant chromosomes, chromosomal aberrations including breaks and rearrangements, and other numerical abnormalities. The various sperm FISH assays have been used to evaluate healthy men, men of advanced age, and men who have received mutagenic cancer therapy. The mouse has also been used as a model to investigate the mechanism of paternally transmitted genetic damage. Sperm FISH for the mouse has been used to detect chromosomally abnormal mouse sperm, while the PAINT/DAPI analysis of mouse zygotes has been used to evaluate themore » types of chromosomal defects that can be paternally transmitted to the embryo and their effects on embryonic development.« less

  12. Stress, deformation, conservation, and rheology: a survey of key concepts in continuum mechanics

    USGS Publications Warehouse

    Major, J.J.

    2013-01-01

    This chapter provides a brief survey of key concepts in continuum mechanics. It focuses on the fundamental physical concepts that underlie derivations of the mathematical formulations of stress, strain, hydraulic head, pore-fluid pressure, and conservation equations. It then shows how stresses are linked to strain and rates of distortion through some special cases of idealized material behaviors. The goal is to equip the reader with a physical understanding of key mathematical formulations that anchor continuum mechanics in order to better understand theoretical studies published in geomorphology.

  13. Lithospheric buckling and intra-arc stresses: A mechanism for arc segmentation

    NASA Technical Reports Server (NTRS)

    Nelson, Kerri L.

    1989-01-01

    Comparison of segment development of a number of arcs has shown that consistent relationships between segmentation, volcanism and variable stresses exists. Researchers successfully modeled these relationships using the conceptual model of lithospheric buckling of Yamaoka et al. (1986; 1987). Lithosphere buckling (deformation) provides the needed mechanism to explain segmentation phenomenon; offsets in volcanic fronts, distribution of calderas within segments, variable segment stresses and the chemical diversity seen between segment boundary and segment interior magmas.

  14. Stress-induced mutation via DNA breaks in Escherichia coli: A molecular mechanism with implications for evolution and medicine

    PubMed Central

    Rosenberg, Susan M; Shee, Chandan; Frisch, Ryan L; Hastings, P J

    2012-01-01

    Abstract Evolutionary theory assumed that mutations occur constantly, gradually, and randomly over time. This formulation from the “modern synthesis” of the 1930s was embraced decades before molecular understanding of genes or mutations. Since then, our labs and others have elucidated mutation mechanisms activated by stress responses. Stress-induced mutation mechanisms produce mutations, potentially accelerating evolution, specifically when cells are maladapted to their environment, that is, when they are stressed. The mechanisms of stress-induced mutation that are being revealed experimentally in laboratory settings provide compelling models for mutagenesis that propels pathogen–host adaptation, antibiotic resistance, cancer progression and resistance, and perhaps much of evolution generally. We discuss double-strand-break-dependent stress-induced mutation in Escherichia coli. Recent results illustrate how a stress response activates mutagenesis and demonstrate this mechanism's generality and importance to spontaneous mutation. New data also suggest a possible harmony between previous, apparently opposed, models for the molecular mechanism. They additionally strengthen the case for anti-evolvability therapeutics for infectious disease and cancer. PMID:22911060

  15. Stress-induced mutation via DNA breaks in Escherichia coli: a molecular mechanism with implications for evolution and medicine.

    PubMed

    Rosenberg, Susan M; Shee, Chandan; Frisch, Ryan L; Hastings, P J

    2012-10-01

    Evolutionary theory assumed that mutations occur constantly, gradually, and randomly over time. This formulation from the "modern synthesis" of the 1930s was embraced decades before molecular understanding of genes or mutations. Since then, our labs and others have elucidated mutation mechanisms activated by stress responses. Stress-induced mutation mechanisms produce mutations, potentially accelerating evolution, specifically when cells are maladapted to their environment, that is, when they are stressed. The mechanisms of stress-induced mutation that are being revealed experimentally in laboratory settings provide compelling models for mutagenesis that propels pathogen-host adaptation, antibiotic resistance, cancer progression and resistance, and perhaps much of evolution generally. We discuss double-strand-break-dependent stress-induced mutation in Escherichia coli. Recent results illustrate how a stress response activates mutagenesis and demonstrate this mechanism's generality and importance to spontaneous mutation. New data also suggest a possible harmony between previous, apparently opposed, models for the molecular mechanism. They additionally strengthen the case for anti-evolvability therapeutics for infectious disease and cancer. Copyright © 2012 WILEY Periodicals, Inc.

  16. Coral bleaching under thermal stress: putative involvement of host/symbiont recognition mechanisms

    PubMed Central

    Vidal-Dupiol, Jeremie; Adjeroud, Mehdi; Roger, Emmanuel; Foure, Laurent; Duval, David; Mone, Yves; Ferrier-Pages, Christine; Tambutte, Eric; Tambutte, Sylvie; Zoccola, Didier; Allemand, Denis; Mitta, Guillaume

    2009-01-01

    Background Coral bleaching can be defined as the loss of symbiotic zooxanthellae and/or their photosynthetic pigments from their cnidarian host. This major disturbance of reef ecosystems is principally induced by increases in water temperature. Since the beginning of the 1980s and the onset of global climate change, this phenomenon has been occurring at increasing rates and scales, and with increasing severity. Several studies have been undertaken in the last few years to better understand the cellular and molecular mechanisms of coral bleaching but the jigsaw puzzle is far from being complete, especially concerning the early events leading to symbiosis breakdown. The aim of the present study was to find molecular actors involved early in the mechanism leading to symbiosis collapse. Results In our experimental procedure, one set of Pocillopora damicornis nubbins was subjected to a gradual increase of water temperature from 28°C to 32°C over 15 days. A second control set kept at constant temperature (28°C). The differentially expressed mRNA between the stressed states (sampled just before the onset of bleaching) and the non stressed states (control) were isolated by Suppression Subtractive Hybridization. Transcription rates of the most interesting genes (considering their putative function) were quantified by Q-RT-PCR, which revealed a significant decrease in transcription of two candidates six days before bleaching. RACE-PCR experiments showed that one of them (PdC-Lectin) contained a C-Type-Lectin domain specific for mannose. Immunolocalisation demonstrated that this host gene mediates molecular interactions between the host and the symbionts suggesting a putative role in zooxanthellae acquisition and/or sequestration. The second gene corresponds to a gene putatively involved in calcification processes (Pdcyst-rich). Its down-regulation could reflect a trade-off mechanism leading to the arrest of the mineralization process under stress. Conclusion Under thermal

  17. Coral bleaching under thermal stress: putative involvement of host/symbiont recognition mechanisms.

    PubMed

    Vidal-Dupiol, Jeremie; Adjeroud, Mehdi; Roger, Emmanuel; Foure, Laurent; Duval, David; Mone, Yves; Ferrier-Pages, Christine; Tambutte, Eric; Tambutte, Sylvie; Zoccola, Didier; Allemand, Denis; Mitta, Guillaume

    2009-08-04

    Coral bleaching can be defined as the loss of symbiotic zooxanthellae and/or their photosynthetic pigments from their cnidarian host. This major disturbance of reef ecosystems is principally induced by increases in water temperature. Since the beginning of the 1980s and the onset of global climate change, this phenomenon has been occurring at increasing rates and scales, and with increasing severity. Several studies have been undertaken in the last few years to better understand the cellular and molecular mechanisms of coral bleaching but the jigsaw puzzle is far from being complete, especially concerning the early events leading to symbiosis breakdown. The aim of the present study was to find molecular actors involved early in the mechanism leading to symbiosis collapse. In our experimental procedure, one set of Pocillopora damicornis nubbins was subjected to a gradual increase of water temperature from 28 degrees C to 32 degrees C over 15 days. A second control set kept at constant temperature (28 degrees C). The differentially expressed mRNA between the stressed states (sampled just before the onset of bleaching) and the non stressed states (control) were isolated by Suppression Subtractive Hybridization. Transcription rates of the most interesting genes (considering their putative function) were quantified by Q-RT-PCR, which revealed a significant decrease in transcription of two candidates six days before bleaching. RACE-PCR experiments showed that one of them (PdC-Lectin) contained a C-Type-Lectin domain specific for mannose. Immunolocalisation demonstrated that this host gene mediates molecular interactions between the host and the symbionts suggesting a putative role in zooxanthellae acquisition and/or sequestration. The second gene corresponds to a gene putatively involved in calcification processes (Pdcyst-rich). Its down-regulation could reflect a trade-off mechanism leading to the arrest of the mineralization process under stress. Under thermal stress

  18. Molecular Abnormalities Underlying Bone Fragility in Chronic Kidney Disease

    PubMed Central

    Iwasaki, Yoshiko; Kazama, Junichiro James

    2017-01-01

    Prevention of bone fractures is one goal of therapy for patients with chronic kidney disease-mineral and bone disorder (CKD-MBD), as indicated by the Kidney Disease: Improving Global Outcomes guidelines. CKD patients, including those on hemodialysis, are at higher risk for fractures and fracture-related death compared to people with normal kidney function. However, few clinicians focus on this issue as it is very difficult to estimate bone fragility. Additionally, uremia-related bone fragility has a more complicated pathological process compared to osteoporosis. There are many uremia-associated factors that contribute to bone fragility, including severe secondary hyperparathyroidism, skeletal resistance to parathyroid hormone, and bone mineralization disorders. Uremia also aggravates bone volume loss, disarranges microarchitecture, and increases the deterioration of material properties of bone through abnormal bone cells or excess oxidative stress. In this review, we outline the prevalence of fractures, the interaction of CKD-MBD with osteoporosis in CKD patients, and discuss possible factors that exacerbate the mechanical properties of bone. PMID:28421193

  19. Stress and glucocorticoid receptor-dependent mechanisms in long-term memory: from adaptive responses to psychopathologies

    PubMed Central

    Finsterwald, Charles; Alberini, Cristina M.

    2013-01-01

    A proper response against stressors is critical for survival. In mammals, the stress response is primarily mediated by secretion of glucocorticoids via the hypothalamic-pituitaryadrenocortical (HPA) axis and release of catecholamines through adrenergic neurotransmission. Activation of these pathways results in a quick physical response to the stress and, in adaptive conditions, mediates long-term changes in the brain that lead to the formation of long-term memories of the experience. These long-term memories are an essential adaptive mechanism that allows an animal to effectively face similar demands again. Indeed, a moderate stress level has a strong positive effect on memory and cognition, as a single arousing or moderately stressful event can be remembered for up to a lifetime. Conversely, exposure to extreme, traumatic, or chronic stress can have the opposite effect and cause memory loss, cognitive impairments, and stress-related psychopathologies such as anxiety disorders, depression and post-traumatic stress disorder (PTSD). While more effort has been devoted to the understanding of the effects of the negative effects of chronic stress, much less has been done thus far on the identification of the mechanisms engaged in the brain when stress promotes long-term memory formation. Understanding these mechanisms will provide critical information for use in ameliorating memory processes in both normal and pathological conditions. Here, we will review the role of glucocorticoids and glucocorticoid receptors (GRs) in memory formation and modulation. Furthermore, we will discuss recent findings on the molecular cascade of events underlying the effect of GR activation in adaptive levels of stress that leads to strong, long-lasting memories. Our recent data indicate that the positive effects of GR activation on memory consolidation critically engage the brain-derived neurotrophic factor (BDNF) pathway. We propose and will discuss the hypothesis that stress promotes the

  20. Targeting Histone Abnormality in Triple Negative Breast Cancer

    DTIC Science & Technology

    2015-08-01

    Casero RA, Davidson NE. Molecular mechanisms of polyamine analogues in cancer cells. Anti - Cancer Drugs, 16(3): 229-241, 2005. PMID: 15711175 18 3...1 AWARD NUMBER: W81XWH-14-1-0237 TITLE: Targeting Histone Abnormality in Triple-Negative Breast Cancer PRINCIPAL INVESTIGATOR: Yi...TITLE AND SUBTITLE 5a. CONTRACT NUMBER Targeting Histone Abnormality in Triple-Negative Breast Cancer 5b. GRANT NUMBER W81XWH-14-1-0237 5c

  1. Early-Life Stress, HPA Axis Adaptation, and Mechanisms Contributing to Later Health Outcomes

    PubMed Central

    Maniam, Jayanthi; Antoniadis, Christopher; Morris, Margaret J.

    2014-01-01

    Stress activates the hypothalamic–pituitary–adrenal (HPA) axis, which then modulates the degree of adaptation and response to a later stressor. It is known that early-life stress can impact on later health but less is known about how early-life stress impairs HPA axis activity, contributing to maladaptation of the stress–response system. Early-life stress exposure (either prenatally or in the early postnatal period) can impact developmental pathways resulting in lasting structural and regulatory changes that predispose to adulthood disease. Epidemiological, clinical, and experimental studies have demonstrated that early-life stress produces long term hyper-responsiveness to stress with exaggerated circulating glucocorticoids, and enhanced anxiety and depression-like behaviors. Recently, evidence has emerged on early-life stress-induced metabolic derangements, for example hyperinsulinemia and altered insulin sensitivity on exposure to a high energy diet later in life. This draws our attention to the contribution of later environment to disease vulnerability. Early-life stress can alter the expression of genes in peripheral tissues, such as the glucocorticoid receptor and 11-beta hydroxysteroid dehydrogenase (11β-HSD1). We propose that interactions between altered HPA axis activity and liver 11β-HSD1 modulates both tissue and circulating glucocorticoid availability, with adverse metabolic consequences. This review discusses the potential mechanisms underlying early-life stress-induced maladaptation of the HPA axis, and its subsequent effects on energy utilization and expenditure. The effects of positive later environments as a means of ameliorating early-life stress-induced health deficits, and proposed mechanisms underpinning the interaction between early-life stress and subsequent detrimental environmental exposures on metabolic risk will be outlined. Limitations in current methodology linking early-life stress and later health outcomes will also be

  2. Maize water status and physiological traits as affected by root endophytic fungus Piriformospora indica under combined drought and mechanical stresses.

    PubMed

    Hosseini, Fatemeh; Mosaddeghi, Mohammad Reza; Dexter, Anthony Roger; Sepehri, Mozhgan

    2018-05-01

    Under combined drought and mechanical stresses, mechanical stress primarily controlled physiological responses of maize. Piriformospora indica mitigated the adverse effects of stresses, and inoculated maize experienced less oxidative damage and had better adaptation to stressful conditions. The objective of this study was to investigate the effect of maize root colonization by an endophytic fungus P. indica on plant water status, physiological traits and root morphology under combined drought and mechanical stresses. Seedlings of inoculated and non-inoculated maize (Zea mays L., cv. single cross 704) were cultivated in growth chambers filled with moistened siliceous sand at a matric suction of 20 hPa. Drought stress was induced using PEG 6000 solution with osmotic potentials of 0, - 0.3 and - 0.5 MPa. Mechanical stress (i.e., penetration resistances of 1.05, 4.23 and 6.34 MPa) was exerted by placing weights on the surface of the sand medium. After 30 days, leaf water potential (LWP) and relative water content (RWC), root and shoot fresh weights, root volume (RV) and diameter (RD), leaf proline content, leaf area (LA) and catalase (CAT) and ascorbate peroxidase (APX) activities were measured. The results show that exposure to individual drought and mechanical stresses led to higher RD and proline content and lower plant biomass, RV and LA. Moreover, increasing drought and mechanical stress severity increased APX activity by about 1.9- and 3.1-fold compared with the control. When plants were exposed to combined stresses, mechanical stress played the dominant role in controlling plant responses. P. indica-inoculated plants are better adapted to individual and combined stresses. The inoculated plants had greater RV, LA, RWC, LWP and proline content under stressful conditions. In comparison with non-inoculated plants, inoculated plants showed lower CAT and APX activities which means that they experienced less oxidative stress induced by stressful conditions.

  3. Piezoelectric Pre-Stressed Bending Mechanism for Impact-Driven Energy Harvester

    NASA Astrophysics Data System (ADS)

    Abdal, A. M.; Leong, K. S.

    2017-06-01

    This paper experimentally demonstrates and evaluates a piezoelectric power generator bending mechanism based on pre-stressed condition whereby the piezoelectric transducer being bended and remained in the stressed condition before applying a force on the piezoelectric bending structure, which increase the stress on the piezoelectric surface and hence increase the generated electrical charges. An impact force is being exerted onto bending the piezoelectric beam and hence generating electrical power across an external resistive load. The proposed bending mechanism prototype has been manufactured by employing 3D printer technology in order to conduct the evaluation. A free fall test has been conducted as the evaluation method with varying force using a series of different masses and different fall heights. A rectangular piezoelectric harvester beam with the size of 32mm in width, 70mm in length, and 0.55mm in thickness is used to demonstrate the experiment. It can be seen from the experiment that the instantaneous peak to peak AC volt output measured at open-circuit is increasing and saturated at about of 70V when an impact force of about 80N is being applied. It is also found that a maximum power of about 53mW is generated at an impact force of 50N when it is connected to an external resistive load of 0.7KΩ. The reported mechanism is a promising candidate in the application of energy harvesting for powering various wireless sensor nodes (WSN) which is the core of Internet of Things (IoT).

  4. Endoplasmic reticulum stress as a novel mechanism in amiodarone-induced destructive thyroiditis.

    PubMed

    Lombardi, Angela; Inabnet, William Barlow; Owen, Randall; Farenholtz, Kaitlyn Ellen; Tomer, Yaron

    2015-01-01

    Amiodarone (AMIO) is one of the most effective antiarrhythmic drugs available; however, its use is limited by a serious side effect profile, including thyroiditis. The mechanisms underlying AMIO thyroid toxicity have been elusive; thus, identification of novel approaches in order to prevent thyroiditis is essential in patients treated with AMIO. Our aim was to evaluate whether AMIO treatment could induce endoplasmic reticulum (ER) stress in human thyroid cells and the possible implications of this effect in AMIO-induced destructive thyroiditis. Here we report that AMIO, but not iodine, significantly induced the expression of ER stress markers including Ig heavy chain-binding protein (BiP), phosphoeukaryotic translation initiation factor 2α (eIF2α), CCAAT/enhancer-binding protein homologous protein (CHOP) and spliced X-box binding protein-1 (XBP-1) in human thyroid ML-1 cells and human primary thyrocytes. In both experimental systems AMIO down-regulated thyroglobulin (Tg) protein but had little effect on Tg mRNA levels, suggesting a mechanism involving Tg protein degradation. Indeed, pretreatment with the specific proteasome inhibitor MG132 reversed AMIO-induced down-regulation of Tg protein levels, confirming a proteasome-dependent degradation of Tg protein. Corroborating our findings, pretreatment of ML-1 cells and human primary thyrocytes with the chemical chaperone 4-phenylbutyric acid completely prevented the effect of AMIO on both ER stress induction and Tg down-regulation. We identified ER stress as a novel mechanism contributing to AMIO-induced destructive thyroiditis. Our data establish that AMIO-induced ER stress impairs Tg expression via proteasome activation, providing a valuable therapeutic avenue for the treatment of AMIO-induced destructive thyroiditis.

  5. Chronic stress and brain plasticity: mechanisms underlying adaptive and maladaptive changes and implications for stress-related CNS disorders

    PubMed Central

    Radley, Jason; Morilak, David; Viau, Victor; Campeau, Serge

    2015-01-01

    Stress responses entail neuroendocrine, autonomic, and behavioral changes to promote effective coping with real or perceived threats to one’s safety. While these responses are critical for the survival of the individual, adverse effects of repeated exposure to stress are widely known to have deleterious effects on health. Thus, a considerable effort in the search for treatments to stress-related CNS disorders necessitates unraveling the brain mechanisms responsible for adaptation under acute conditions and their perturbations following chronic stress exposure. This paper is based upon a symposium from the 2014 International Behavioral Neuroscience Meeting, summarizing some recent advances in understanding the effects of stress on adaptive and maladaptive responses subserved by limbic forebrain networks. An important theme highlighted in this review is that the same networks mediating neuroendocrine, autonomic, and behavioral processes during adaptive coping also comprise targets of the effects of repeated stress exposure in the development of maladaptive states. Where possible, reference is made to the similarity of neurobiological substrates and effects observed following repeated exposure to stress in laboratory animals and the clinical features of stress-related disorders in humans. PMID:26116544

  6. Sound stress-induced long-term enhancement of mechanical hyperalgesia in rats is maintained by sympathoadrenal catecholamines.

    PubMed

    Khasar, Sachia G; Dina, Olayinka A; Green, Paul G; Levine, Jon D

    2009-10-01

    Although stress plays an important role in chronic widespread pain syndromes, such as fibromyalgia, the underlying mechanism has remained elusive. We have recently demonstrated, in a model of chronic widespread pain, that prolonged enhancement of immune mediator hyperalgesia, induced by unpredictable sound stress, requires a contribution of both the sympathoadrenal (epinephrine) and the hypothalamic-pituitary adrenal (corticosterone) neuroendocrine stress axes. Because this stress protocol produced sustained elevation of plasma epinephrine, in the current study we tested the hypothesis that the sympathoadrenal axis also plays a role in maintenance of symptoms in this model of chronic widespread pain. After establishment, adrenal medullectomy abolished the enhancement of epinephrine-induced cutaneous and muscle hyperalgesia. Administration of stress levels of epinephrine to adrenal medullectomized rats reconstituted the pain phenotype. These observations suggest that the sympathoadrenal stress axis plays a major role in the induction as well as maintenance of stress-induced enhancement of mechanical hyperalgesia, mediated by prolonged elevation of circulating epinephrine. We present data showing mechanical hyperalgesia persisting for up to 28 days after exposure to sound stress, with evidence that the sympathoadrenal axis mediator epinephrine plays a major role. These findings could have clinical implications with regard to novel potential treatments for chronic widespread pain syndromes, such as fibromyalgia.

  7. Oxidative Stress and β-Thalassemic Erythroid Cells behind the Molecular Defect

    PubMed Central

    Bertoldi, Mariarita; Matte, Alessandro; Santos Franco, Sara; Pantaleo, Antonella; Ferru, Emanuela; Turrini, Franco

    2013-01-01

    β-thalassemia is a worldwide distributed monogenic red cell disorder, characterized by the absence or reduced β-globin chain synthesis. Despite the extensive knowledge of the molecular defects causing β-thalassemia, less is known about the mechanisms responsible for the associated ineffective erythropoiesis and reduced red cell survival, which sustain anemia of β-thalassemia. The unbalance of alpha-gamma chain and the presence of pathological free iron promote a severe red cell membrane oxidative stress, which results in abnormal β-thalassemic red cell features. These cells are precociously removed by the macrophage system through two mechanisms: the removal of phosphatidylserine positive cells and through the natural occurring antibody produced against the abnormally clustered membrane protein band 3. In the present review we will discuss the changes in β-thalassemic red cell homeostasis related to the oxidative stress and its connection with production of microparticles and with malaria infection. The reactive oxygen species (ROS) are also involved in ineffective erythropoiesis of β-thalassemia through still partially known pathways. Novel cytoprotective systems such as ASHP, eIF2α, and peroxiredoxin-2 have been suggested to be important against ROS in β-thalassemic erythropoiesis. Finally, we will discuss the results of the major in vitro and in vivo studies with antioxidants in β-thalassemia. PMID:24205432

  8. Immune and Neuroendocrine Mechanisms of Stress Vulnerability and Resilience

    PubMed Central

    Ménard, Caroline; Pfau, Madeline L; Hodes, Georgia E; Russo, Scott J

    2017-01-01

    Diagnostic criteria for mood disorders including major depressive disorder (MDD) largely ignore biological factors in favor of behavioral symptoms. Compounding this paucity of psychiatric biomarkers is a need for therapeutics to adequately treat the 30–50% of MDD patients who are unresponsive to traditional antidepressant medications. Interestingly, MDD is highly prevalent in patients suffering from chronic inflammatory conditions, and MDD patients exhibit higher levels of circulating pro-inflammatory cytokines. Together, these clinical findings suggest a role for the immune system in vulnerability to stress-related psychiatric illness. A growing body of literature also implicates the immune system in stress resilience and coping. In this review, we discuss the mechanisms by which peripheral and central immune cells act on the brain to affect stress-related neurobiological and neuroendocrine responses. We specifically focus on the roles of pro-inflammatory cytokine signaling, peripheral monocyte infiltration, microglial activation, and hypothalamic-pituitary-adrenal axis hyperactivity in stress vulnerability. We also highlight recent evidence suggesting that adaptive immune responses and treatment with immune modulators (exogenous glucocorticoids, humanized antibodies against cytokines) may decrease depressive symptoms and thus represent an attractive alternative to the current antidepressant treatments. PMID:27291462

  9. Retinal abnormalities in β-thalassemia major.

    PubMed

    Bhoiwala, Devang L; Dunaief, Joshua L

    2016-01-01

    Patients with beta (β)-thalassemia (β-TM: β-thalassemia major, β-TI: β-thalassemia intermedia) have a variety of complications that may affect all organs, including the eye. Ocular abnormalities include retinal pigment epithelial degeneration, angioid streaks, venous tortuosity, night blindness, visual field defects, decreased visual acuity, color vision abnormalities, and acute visual loss. Patients with β-thalassemia major are transfusion dependent and require iron chelation therapy to survive. Retinal degeneration may result from either retinal iron accumulation from transfusion-induced iron overload or retinal toxicity induced by iron chelation therapy. Some who were never treated with iron chelation therapy exhibited retinopathy, and others receiving iron chelation therapy had chelator-induced retinopathy. We will focus on retinal abnormalities present in individuals with β-thalassemia major viewed in light of new findings on the mechanisms and manifestations of retinal iron toxicity. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Leaf Proteome Analysis Reveals Prospective Drought and Heat Stress Response Mechanisms in Soybean.

    PubMed

    Das, Aayudh; Eldakak, Moustafa; Paudel, Bimal; Kim, Dea-Wook; Hemmati, Homa; Basu, Chhandak; Rohila, Jai S

    2016-01-01

    Drought and heat are among the major abiotic stresses that affect soybean crops worldwide. During the current investigation, the effect of drought, heat, and drought plus heat stresses was compared in the leaves of two soybean varieties, Surge and Davison, combining 2D-DIGE proteomic data with physiology and biochemical analyses. We demonstrated how 25 differentially expressed photosynthesis-related proteins affect RuBisCO regulation, electron transport, Calvin cycle, and carbon fixation during drought and heat stress. We also observed higher abundance of heat stress-induced EF-Tu protein in Surge. It is possible that EF-Tu might have activated heat tolerance mechanisms in the soybean. Higher level expressions of heat shock-related protein seem to be regulating the heat tolerance mechanisms. This study identifies the differential expression of various abiotic stress-responsive proteins that regulate various molecular processes and signaling cascades. One inevitable outcome from the biochemical and proteomics assays of this study is that increase of ROS levels during drought stress does not show significant changes at the phenotypic level in Davison and this seems to be due to a higher amount of carbonic anhydrase accumulation in the cell which aids the cell to become more resistant to cytotoxic concentrations of H2O2.

  11. Leaf Proteome Analysis Reveals Prospective Drought and Heat Stress Response Mechanisms in Soybean

    PubMed Central

    Das, Aayudh; Eldakak, Moustafa; Paudel, Bimal; Kim, Dea-Wook; Hemmati, Homa; Basu, Chhandak

    2016-01-01

    Drought and heat are among the major abiotic stresses that affect soybean crops worldwide. During the current investigation, the effect of drought, heat, and drought plus heat stresses was compared in the leaves of two soybean varieties, Surge and Davison, combining 2D-DIGE proteomic data with physiology and biochemical analyses. We demonstrated how 25 differentially expressed photosynthesis-related proteins affect RuBisCO regulation, electron transport, Calvin cycle, and carbon fixation during drought and heat stress. We also observed higher abundance of heat stress-induced EF-Tu protein in Surge. It is possible that EF-Tu might have activated heat tolerance mechanisms in the soybean. Higher level expressions of heat shock-related protein seem to be regulating the heat tolerance mechanisms. This study identifies the differential expression of various abiotic stress-responsive proteins that regulate various molecular processes and signaling cascades. One inevitable outcome from the biochemical and proteomics assays of this study is that increase of ROS levels during drought stress does not show significant changes at the phenotypic level in Davison and this seems to be due to a higher amount of carbonic anhydrase accumulation in the cell which aids the cell to become more resistant to cytotoxic concentrations of H2O2. PMID:27034942

  12. Potential Mechanisms of Exercise in Gestational Diabetes

    PubMed Central

    Golbidi, Saeid; Laher, Ismail

    2013-01-01

    Gestational diabetes mellitus (GDM) is defined as glucose intolerance first diagnosed during pregnancy. This condition shares same array of underlying abnormalities as occurs in diabetes outside of pregnancy, for example, genetic and environmental causes. However, the role of a sedentary lifestyle and/or excess energy intake is more prominent in GDM. Physically active women are less likely to develop GDM and other pregnancy-related diseases. Weight gain in pregnancy causes increased release of adipokines from adipose tissue; many adipokines increase oxidative stress and insulin resistance. Increased intramyocellular lipids also increase cellular oxidative stress with subsequent generation of reactive oxygen species. A well-planned program of exercise is an important component of a healthy lifestyle and, in spite of old myths, is also recommended during pregnancy. This paper briefly reviews the role of adipokines in gestational diabetes and attempts to shed some light on the mechanisms by which exercise can be beneficial as an adjuvant therapy in GDM. In this regard, we discuss the mechanisms by which exercise increases insulin sensitivity, changes adipokine profile levels, and boosts antioxidant mechanisms. PMID:23691290

  13. Cellular packing, mechanical stress and the evolution of multicellularity

    NASA Astrophysics Data System (ADS)

    Jacobeen, Shane; Pentz, Jennifer T.; Graba, Elyes C.; Brandys, Colin G.; Ratcliff, William C.; Yunker, Peter J.

    2018-03-01

    The evolution of multicellularity set the stage for sustained increases in organismal complexity1-5. However, a fundamental aspect of this transition remains largely unknown: how do simple clusters of cells evolve increased size when confronted by forces capable of breaking intracellular bonds? Here we show that multicellular snowflake yeast clusters6-8 fracture due to crowding-induced mechanical stress. Over seven weeks ( 291 generations) of daily selection for large size, snowflake clusters evolve to increase their radius 1.7-fold by reducing the accumulation of internal stress. During this period, cells within the clusters evolve to be more elongated, concomitant with a decrease in the cellular volume fraction of the clusters. The associated increase in free space reduces the internal stress caused by cellular growth, thus delaying fracture and increasing cluster size. This work demonstrates how readily natural selection finds simple, physical solutions to spatial constraints that limit the evolution of group size—a fundamental step in the evolution of multicellularity.

  14. Preferential Osmolyte Accumulation: a Mechanism of Osmotic Stress Adaptation in Diazotrophic Bacteria

    PubMed Central

    Madkour, Magdy A.; Smith, Linda Tombras; Smith, Gary M.

    1990-01-01

    A common cellular mechanism of osmotic-stress adaptation is the intracellular accumulation of organic solutes (osmolytes). We investigated the mechanism of osmotic adaptation in the diazotrophic bacteria Azotobacter chroococcum, Azospirillum brasilense, and Klebsiella pneumoniae, which are adversely affected by high osmotic strength (i.e., soil salinity and/or drought). We used natural-abundance 13C nuclear magnetic resonance spectroscopy to identify all the osmolytes accumulating in these strains during osmotic stress generated by 0.5 M NaCl. Evidence is presented for the accumulation of trehalose and glutamate in Azotobacter chroococcum ZSM4, proline and glutamate in Azospirillum brasilense SHS6, and trehalose and proline in K. pneumoniae. Glycine betaine was accumulated in all strains grown in culture media containing yeast extract as the sole nitrogen source. Alternative nitrogen sources (e.g., NH4Cl or casamino acids) in the culture medium did not result in measurable glycine betaine accumulation. We suggest that the mechanism of osmotic adaptation in these organisms entails the accumulation of osmolytes in hyperosmotically stressed cells resulting from either enhanced uptake from the medium (of glycine betaine, proline, and glutamate) or increased net biosynthesis (of trehalose, proline, and glutamate) or both. The preferred osmolyte in Azotobacter chroococcum ZSM4 shifted from glutamate to trehalose as a consequence of a prolonged osmotic stress. Also, the dominant osmolyte in Azospirillum brasilense SHS6 shifted from glutamate to proline accumulation as the osmotic strength of the medium increased. PMID:16348295

  15. Growth reponses of eggplant and soybean seedlings to mechanical stress in greenhouse and outdoor environments

    NASA Technical Reports Server (NTRS)

    Latimer, J. G.; Pappas, T.; Mitchell, C. A.

    1986-01-01

    Eggplant (Solanum melongena L. var. esculentum 'Burpee's Black Beauty') and soybean [Glycine max (L.) Merr. 'Wells II'] seedlings were assigned to a greenhouse or a windless or windy outdoor environment. Plants within each environment received either periodic seismic (shaking) or thigmic (flexing or rubbing) treatment, or were left undisturbed. Productivity (dry weight) and dimensional (leaf area and stem length) growth parameters generally were reduced more by mechanical stress in the greenhouse (soybean) or outdoor-windless environment (eggplant) than in the outdoor windy environment. Outdoor exposure enhanced both stem and leaf specific weights, whereas mechanical stress enhanced only leaf specific weight. Although both forms of controlled mechanical stress tended to reduce node and internode diameters of soybean, outdoor exposure increased stem diameter.

  16. Control of Mechanical Stresses of High Pressure Container Walls by Magnetoelastic Method

    NASA Astrophysics Data System (ADS)

    Kulak, S. M.; Novikov, V. F.; Baranov, A. V.

    2016-10-01

    Deformations of the walls of pressure vessels arising in the process of testing and operation, as well as reduce their thickness due to corrosion, to create the prerequisites for the growth of mechanical stresses which accelerating the processes of strain aging, embrittlement of the material and reducing its fatigue properties. This article is devoted to researches of the magnetoelastic demagnetization in the wall of steel vessel of loading by internal pressure. It is established that the increasing pressure on the vessel wall is accompanied by a monotonic decrease in the intensity of the magnetic stray field of local magnetization of steel. It is shown that a magnetic stray field of local magnetization of the wall of steel vessel is non-uniform due to differences in structure and stresses. It is proposed to use the obtained results to control the stress state of vessels, experiencing multi-axial loads generated by internal pressure (pipelines, oil tanks, etc.) The method of magnetoelastic of the demagnetization of the steel has a high sensitivity to mechanical stress, the simplicity of implementation and expressiveness compared to the strain gauge and method of coercive force.

  17. Responses to combined abiotic and biotic stress in tomato are governed by stress intensity and resistance mechanism

    PubMed Central

    Kissoudis, Christos; Sunarti, Sri; van de Wiel, Clemens; Visser, Richard G.F.; van der Linden, C. Gerard; Bai, Yuling

    2016-01-01

    Stress conditions in agricultural ecosystems can occur at variable intensities. Different resistance mechanisms against abiotic stress and pathogens are deployed by plants. Thus, it is important to examine plant responses to stress combinations under different scenarios. Here, we evaluated the effect of different levels of salt stress ranging from mild to severe (50, 100, and 150mM NaCl) on powdery mildew resistance and overall performance of tomato introgression lines with contrasting levels of partial resistance, as well as near-isogenic lines (NILs) carrying the resistance gene Ol-1 (associated with a slow hypersensitivity response; HR), ol-2 (an mlo mutant associated with papilla formation), and Ol-4 (an R gene associated with a fast HR). Powdery mildew resistance was affected by salt stress in a genotype- and stress intensity-dependent manner. In susceptible and partial resistant lines, increased susceptibility was observed under mild salt stress (50mM) which was accompanied by accelerated cell death-like senescence. In contrast, severe salt stress (150mM) reduced disease symptoms. Na+ and Cl− accumulation in the leaves was linearly related to the decreased pathogen symptoms under severe stress. In contrast, complete resistance mediated by ol-2 and Ol-4 was unaffected under all treatment combinations, and was associated with a decreased growth penalty. Increased susceptibility and senescence under combined stress in NIL-Ol-1 was associated with the induction of ethylene and jasmonic acid pathway genes and the cell wall invertase gene LIN6. These results highlight the significance of stress severity and resistance type on the plant’s performance under the combination of abiotic and biotic stress. PMID:27436279

  18. Composite Overwrap Pressure Vessels: Mechanics and Stress Rupture Lifting Philosophy

    NASA Technical Reports Server (NTRS)

    Thesken, John C.; Murthy, Pappu L. N.; Phoenix, S. L.

    2009-01-01

    The NASA Engineering and Safety Center (NESC) has been conducting an independent technical assessment to address safety concerns related to the known stress rupture failure mode of filament wound pressure vessels in use on Shuttle and the International Space Station. The Shuttle s Kevlar-49 (DuPont) fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar-49 filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However due to the presence of load sharing liners and the complex manufacturing procedures, the state of actual fiber stress in flight hardware and test articles is not clearly known. Indeed nonconservative life predictions have been made where stress rupture data and lifing procedures have ignored the contribution of the liner in favor of applied pressure as the controlling load parameter. With the aid of analytical and finite element results, this paper examines the fundamental mechanical response of composite overwrapped pressure vessels including the influence of elastic plastic liners and degraded/creeping overwrap properties. Graphical methods are presented describing the non-linear relationship of applied pressure to Kevlar-49 fiber stress/strain during manufacturing, operations and burst loadings. These are applied to experimental measurements made on a variety of vessel systems to demonstrate the correct calibration of fiber stress as a function of pressure. Applying this analysis to the actual qualification burst data for Shuttle flight hardware revealed that the nominal fiber stress at burst was in some cases 23 percent lower than what had previously been used to predict stress rupture life. These results motivate a detailed discussion of the appropriate stress rupture lifing philosophy for COPVs including the correct transference of stress rupture life data between dissimilar vessels and test articles.

  19. Composite Overwrap Pressure Vessels: Mechanics and Stress Rupture Lifing Philosophy

    NASA Technical Reports Server (NTRS)

    Thesken, John C.; Murthy, Pappu L. N.; Phoenix, Leigh

    2007-01-01

    The NASA Engineering and Safety Center (NESC) has been conducting an independent technical assessment to address safety concerns related to the known stress rupture failure mode of filament wound pressure vessels in use on Shuttle and the International Space Station. The Shuttle's Kevlar-49 fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar-49 filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However due to the presence of load sharing liners and the complex manufacturing procedures, the state of actual fiber stress in flight hardware and test articles is not clearly known. Indeed non-conservative life predictions have been made where stress rupture data and lifing procedures have ignored the contribution of the liner in favor of applied pressure as the controlling load parameter. With the aid of analytical and finite element results, this paper examines the fundamental mechanical response of composite overwrapped pressure vessels including the influence of elastic-plastic liners and degraded/creeping overwrap properties. Graphical methods are presented describing the non-linear relationship of applied pressure to Kevlar-49 fiber stress/strain during manufacturing, operations and burst loadings. These are applied to experimental measurements made on a variety of vessel systems to demonstrate the correct calibration of fiber stress as a function of pressure. Applying this analysis to the actual qualification burst data for Shuttle flight hardware revealed that the nominal fiber stress at burst was in some cases 23% lower than what had previously been used to predict stress rupture life. These results motivate a detailed discussion of the appropriate stress rupture lifing philosophy for COPVs including the correct transference of stress rupture life data between dissimilar vessels and test articles.

  20. Closed-form analysis of fiber-matrix interface stresses under thermo-mechanical loadings

    NASA Technical Reports Server (NTRS)

    Naik, Rajiv A.; Crews, John H., Jr.

    1992-01-01

    Closed form techniques for calculating fiber matrix (FM) interface stresses, using repeating square and diamond regular arrays, were presented for a unidirectional composite under thermo-mechanical loadings. An Airy's stress function micromechanics approach from the literature, developed for calculating overall composite moduli, was extended in the present study to compute FM interface stresses for a unidirectional graphite/epoxy (AS4/3501-6) composite under thermal, longitudinal, transverse, transverse shear, and longitudinal shear loadings. Comparison with finite element results indicate excellent agreement of the FM interface stresses for the square array. Under thermal and longitudinal loading, the square array has the same FM peak stresses as the diamond array. The square array predicted higher stress concentrations under transverse normal and longitudinal shear loadings than the diamond array. Under transverse shear loading, the square array had a higher stress concentration while the diamond array had a higher radial stress concentration. Stress concentration factors under transverse shear and longitudinal shear loadings were very sensitive to fiber volume fraction. The present analysis provides a simple way to calculate accurate FM interface stresses for both the square and diamond array configurations.

  1. Topiramate for Abnormal Eating Behaviour in Frontotemporal Dementia

    PubMed Central

    Singam, Colin; Walterfang, Mark; Mocellin, Ramon; Evans, Andrew; Velakoulis, Dennis

    2013-01-01

    Topiramate is a sulfamate-substituted monosaccharide anticonvulsant that is associated with anorexia and weight loss and has been used to treat binge eating disorder and bulimia nervosa. This report describes a man with frontotemporal dementia, behavioural variant, associated with abnormal eating behaviour which appeared to respond to topiramate. We review the physiological basis of abnormal eating behaviour in frontotemporal dementia and explore possible mechanisms of action by which topiramate may modify eating behaviour in this condition. PMID:23548883

  2. Hemorheological abnormalities in human arterial hypertension

    NASA Astrophysics Data System (ADS)

    Lo Presti, Rosalia; Hopps, Eugenia; Caimi, Gregorio

    2014-05-01

    Blood rheology is impaired in hypertensive patients. The alteration involves blood and plasma viscosity, and the erythrocyte behaviour is often abnormal. The hemorheological pattern appears to be related to some pathophysiological mechanisms of hypertension and to organ damage, in particular left ventricular hypertrophy and myocardial ischemia. Abnormalities have been observed in erythrocyte membrane fluidity, explored by fluorescence spectroscopy and electron spin resonance. This may be relevant for red cell flow in microvessels and oxygen delivery to tissues. Although blood viscosity is not a direct target of antihypertensive therapy, the rheological properties of blood play a role in the pathophysiology of arterial hypertension and its vascular complications.

  3. In vivo immunoprotective role of Indigofera tinctoria and Scoparia dulcis aqueous extracts against chronic noise stress induced immune abnormalities in Wistar albino rats.

    PubMed

    Madakkannu, Boothapandi; Ravichandran, Ramanibai

    2017-01-01

    Indigofera tinctoria and Scoparia dulcis are being widely used in Indian folk medicine for the treatment of various disorders. Environmental noise pollution is thought to be an important factor for many health problems and it causes immune abnormalities. In the present study immune-regulating potential of I. tinctoria and S. dulcis aqueous extracts on innate and adaptive immune system of wistar albino rats was evaluated during normal and chronic noise induced stress conditions. The results demonstrated that both I. tinctoria and S. dulcis aqueous extracts (200 mg/kg b.w) showed immunostimulant effect on both innate and adaptive immune response of wistar albino rat compared to control group under normal condition. The noise stress (100 dB for 1 h, 20 days) induced animals showed suppressive effects on immune response by decreasing macrophage phagocytosis, antibody secretion by spleen cells, humoral immune response, proliferation of lymphocytes, cytotoxicity, TNF α expression, granzyme B and perforin expression in splenic NK cells. Similarly, noise stress also caused DNA damage in tissues. However, the suppressed effects induced by noise stress on rat immune system were significantly prevented by oral administration of both I. tinctoria and S. dulcis aqueous extracts. Considering all these results it is suggested that the selected medicinal plant's aqueous extracts have the potential to prevent the effects of noise stress induced rat immune system and explore a strong immunostimulant potential applicable to clinical practices.

  4. Focal mechanism and stress analyses for main tectonic zones in Albania

    NASA Astrophysics Data System (ADS)

    Dushi, Edmond; Koçi, Rexhep; Begu, Enkela; Bozo, Rrezart

    2017-04-01

    In this study, a number of 33 moderate earthquakes for the period 2013-2015, ranging in magnitude within 2.2 ≤ MW ≤ 4.9 and located within the Albanian territory, have been analyzed. As an earthquake prone country, situated at the frontal collision boundary between Adria microplate and Eurasian tectonic plate, Albania is characterized frequently by micro earthquakes, many moderate and seldom by strong ones. It is evidenced that the whole territory is divided in two different tectonic domains, correspondingly the outer and the inner domain, showing different stress regime as clearly evidenced based on earthquake focal mechanism and geodetic studies. Although strong earthquakes are clearly related to faults in tectonically active areas, moderate events are more frequent revealing valuable information on this purpose. All the studied events are selected to be well-recorded by a maximum possible number of the local broadband (BB) seismological stations of Albanian Seismological Network (ASN), although regional stations have been used as well to constrain the solution. Earthquakes are grouped according to their location, within three well-defined tectonic zones, namely: Adriatic-Ionian (AI), Lushnja-Elbasani-Dibra (LED) and Ohrid-Korça (OK). For each event, the seismic moment M0is determined, through spectral analyses. Moment values vary ranging 1012 - 1015 Nm, for the Adriatic-Ionian (AI) outer zone; 1013 - 1016 Nm, for the Lushnja-Elbasani-Dibra (LED) transversal zone, which cuts through both the outer and the inner domains and 1012 - 1014 Nm, for the Ohrid-Korça (OK), north-south trending inner zone. Focal mechanism solutions (FMS) have been determined for each earthquake, based on the robust first motion polarities method, as applied in the FOCMEC (Seisan 10.1) routine. Using the Michael's linear bootstrap invertion on FMS, a stress analysis is applied. Results show the minimum compressional stress directions variation: σ1 370/270, σ23030/80 and σ31980

  5. PRENATAL STRESS AND RISK FOR AUTISM

    PubMed Central

    Kinney, Dennis K.; Munir, Kerim M.; Crowley, David J.; Miller, Andrea M.

    2008-01-01

    This paper reviews several converging lines of research that suggest that prenatal exposure to environmental stress may increase risk for Autistic Disorder (AD). We first discuss studies finding that prenatal exposure to stressful life events is associated with significantly increased risk of AD, as well as other disorders, such as schizophrenia and depression. We then review evidence from animal and human studies that prenatal stress can produce both (a) abnormal postnatal behaviors that resemble the defining symptoms of AD, and (b) other abnormalities that have elevated rates in AD, such as learning deficits, seizure disorders, perinatal complications, immunologic and neuroinflammatory anomalies, and low postnatal tolerance for stress. We explain why an etiologic role for prenatal stress is compatible with genetic factors in AD, and describe how stress can disrupt fetal brain development. Finally, we discuss implications for understanding underlying processes in AD, including potential gene-environment interactions, and developing new therapies and early prevention programs. PMID:18598714

  6. Calcium-mediated oxidative stress: a common mechanism in tight junction disruption by different types of cellular stress.

    PubMed

    Gangwar, Ruchika; Meena, Avtar S; Shukla, Pradeep K; Nagaraja, Archana S; Dorniak, Piotr L; Pallikuth, Sandeep; Waters, Christopher M; Sood, Anil; Rao, RadhaKrishna

    2017-02-20

    The role of reactive oxygen species (ROS) in osmotic stress, dextran sulfate sodium (DSS) and cyclic stretch-induced tight junction (TJ) disruption was investigated in Caco-2 cell monolayers in vitro and restraint stress-induced barrier dysfunction in mouse colon in vivo Live cell imaging showed that osmotic stress, cyclic stretch and DSS triggered rapid production of ROS in Caco-2 cell monolayers, which was blocked by depletion of intracellular Ca 2+ by 1,2-bis-( o -aminophenoxy)ethane- N , N , N ', N '-tetraacetic acid. Knockdown of Ca V 1.3 or TRPV6 channels blocked osmotic stress and DSS-induced ROS production and attenuated TJ disruption and barrier dysfunction. N -Acetyl l-cysteine (NAC) and l- N G -Nitroarginine methyl ester (l-NAME) blocked stress-induced TJ disruption and barrier dysfunction. NAC and l-NAME also blocked stress-induced activation of c-Jun N -terminal kinase (JNK) and c-Src. ROS was colocalized with the mitochondrial marker in stressed cells. Cyclosporin A blocked osmotic stress and DSS-induced ROS production, barrier dysfunction, TJ disruption and JNK activation. Mitochondria-targeted Mito-TEMPO blocked osmotic stress and DSS-induced barrier dysfunction and TJ disruption. Chronic restraint stress in mice resulted in the elevation of intracellular Ca 2+ , activation of JNK and c-Src, and disruption of TJ in the colonic epithelium. Furthermore, corticosterone administration induced JNK and c-Src activation, TJ disruption and protein thiol oxidation in colonic mucosa. The present study demonstrates that oxidative stress is a common signal in the mechanism of TJ disruption in the intestinal epithelium by different types of cellular stress in vitro and bio behavioral stress in vivo . © 2017 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.

  7. Oxidative Stress in Schizophrenia: An Integrated Approach

    PubMed Central

    Bitanihirwe, Byron K.Y.; Woo, Tsung-Ung W.

    2010-01-01

    Oxidative stress has been suggested to contribute to the pathophysiology of schizophrenia. In particular, oxidative damage to lipids, proteins, and DNA as observed in schizophrenia is known to impair cell viability and function, which may subsequently account for the deteriorating course of the illness. Currently available evidence points towards an alteration in the activities of enzymatic and nonenzymatic antioxidant systems in schizophrenia. In fact, experimental models have demonstrated that oxidative stress induces behavioural and molecular anomalies strikingly similar to those observed in schizophrenia. These findings suggest that oxidative stress is intimately linked to a variety of pathophysiological processes, such as inflammation, oligodendrocyte abnormalities, mitochondrial dysfunction, hypoactive N-methyl-D-aspartate receptors and the impairment of fast-spiking gamma-aminobutyric acid interneurons.[bkyb1] Such self-sustaining mechanisms may progressively worsen producing the functional and structural consequences associated with schizophrenia. Recent clinical studies have shown antioxidant treatment to be effective in ameliorating schizophrenic symptoms. Hence, identifying viable therapeutic strategies to tackle oxidative stress and the resulting physiological disturbances provide an exciting opportunity for the treatment and ultimately prevention of schizophrenia. PMID:20974172

  8. Chemical chaperones reduce ER stress and adipose tissue inflammation in high fat diet-induced mouse model of obesity.

    PubMed

    Chen, Yaqin; Wu, Zhihong; Zhao, Shuiping; Xiang, Rong

    2016-06-08

    Obesity, which is characteristic by chronic inflammation, is defined as abnormal or excessive fat accumulation in adipose tissues. Endoplasmic reticulum (ER) stress is increased in adipose tissue of obese state and is known to be strongly associated with chronic inflammation. The aim of this study was to investigate the effect of ER stress on adipokine secretion in obese mice and explore the potential mechanisms. In this study, we found high-fat diet induced-obesity contributed to strengthened ER stress and triggered chronic inflammation in adipose tissue. Chemical chaperones, 4-PBA and TUDCA, modified metabolic disorders and decreased the levels of inflammatory cytokines in obese mice fed a high-fat diet. The alleviation of ER stress is in accordance with the decrease of free cholesterol in adipose tissue. Furthermore chemical chaperones suppress NF-κB activity in adipose tissue of obese mice in vivo. In vitro studies showed IKK/NF-κB may be involved in the signal transduction of adipokine secretion dysfunction induced by ER stress. The present study revealed the possibility that inhibition of ER stress may be a novel drug target for metabolic abnormalities associated with obesity. Further studies are now needed to characterize the initial incentive of sustained ER stress in obese.

  9. Endogenous reward mechanisms and their importance in stress reduction, exercise and the brain.

    PubMed

    Esch, Tobias; Stefano, George B

    2010-06-30

    Stress can facilitate disease processes and causes strain on the health care budgets. It is responsible or involved in many human ailments of our time, such as cardiovascular illnesses, particularly related to the psychosocial stressors of daily life, including work. Besides pharmacological or clinical medical treatment options, behavioral stress reduction is much-needed. These latter approaches rely on an endogenous healing potential via life-style modification. Hence, research has suggested different ways and approaches to self-treat stress or buffer against stressors and their impacts. These self-care-centred approaches are sometimes referred to as mind-body medicine or multi-factorial stress management strategies. They consist of various cognitive behavioral techniques, as well as relaxation exercises and nutritional counselling. However, a critical and consistent element of modern effective stress reduction strategies are exercise practices. With regard to underlying neurobiological mechanisms of stress relief, reward and motivation circuitries that are imbedded in the limbic regions of the brain are responsible for the autoregulatory and endogenous processing of stress. Exercise techniques clearly have an impact upon these systems. Thereby, physical activities have a potential to increase mood, i.e., decrease psychological distress by pleasure induction. For doing so, neurobiological signalling molecules such as endogenous morphine and coupled nitric oxide pathways get activated and finely tuned. Evolutionarily, the various activities and autoregulatory pathways are linked together, which can also be demonstrated by the fact that dopamine is endogenously converted into morphine which itself leads to enhanced nitric oxide release by activation of constitutive nitric oxide synthase enzymes. These molecules and mechanisms are clearly stress-reducing.

  10. Optimization of the Mechanical Properties and Residual Stresses in 2024 Aluminum Alloy Through Heat Treatment

    NASA Astrophysics Data System (ADS)

    Araghchi, M.; Mansouri, H.; Vafaei, R.; Guo, Y.

    2018-05-01

    Residual stresses induced during quenching of aluminum alloys cause dimensional instability and distortion. In this study, the effects of different concentrations of polyalkylene glycol (PAG) quenchants on residual stresses and mechanical properties of 2024 aluminum alloy were investigated. Surface residual stresses were measured by using hole-drilling strain-gauge method. Also, mechanical properties and microstructure of the heat-treated samples were analyzed using hardness measurements, tensile tests, and transmission electron microscopy. Results showed that quenching into a 15% polymeric solution and aging at 190 °C for 12 h cause 50% reduction in residual stress as compared with quenching in water at 20 °C and naturally aging. Moreover, tensile strength decreased by 104 MPa ( 20%) in compared with the T6 sample.

  11. Magnetic resonance imaging in stress fractures and shin splints.

    PubMed

    Aoki, Yoshimitsu; Yasuda, Kazunori; Tohyama, Harukazu; Ito, Hirokazu; Minami, Akio

    2004-04-01

    The purpose of the current study was to determine whether stress fractures and shin splints could be discriminated with MRI in the early phase. Twenty-two athletes, who had pain in the middle or distal part of their leg during or after sports activity, were evaluated with radiographs and MRI scans. Stress fractures were diagnosed when consecutive radiographs showed local periosteal reaction or a fracture line, and shin splints were diagnosed in all the other cases. In all eight patients with stress fractures, an abnormally wide high signal in the localized bone marrow was the most detectable in the coronal fat-suppressed MRI scan. In 11 patients with shin splints, the coronal fat-suppressed MRI scans showed a linear abnormally high signal along the medial posterior surface of the tibia, and in seven patients with shin splints, the MRI scans showed a linear abnormally high signal along the medial bone marrow. No MRI scans of shin splints showed an abnormally wide high signal in the bone marrow as observed on MRI scans of stress fractures. This study showed that fat-suppressed MRI is useful for discrimination between stress fracture and shin splints before radiographs show a detectable periosteal reaction in the tibia.

  12. Effects on DNA Damage and/or Repair Processes as Biological Mechanisms Linking Psychological Stress to Cancer Risk

    PubMed Central

    Jenkins, Frank J.; Van Houten, Bennett; Bovbjerg, Dana H.

    2014-01-01

    Considerable research effort in the past several decades has focused on the impact of psychological stress, and stress hormones, on cancer progression. Numerous studies have reported that stress hormone treatment or in vivo stress exposure can enhance the growth of tumor cell lines in vitro, as well as tumors in animal models, and have begun to explore molecular mechanisms. Comparatively little research has focused on the impact of psychological stress and stress hormones on cancer initiation, in part due to inherent methodological challenges, but also because potential underlying biological mechanisms have remained obscure. In this review, we present a testable theoretical model of pathways by which stress may result in cellular transformation and tumorigenesis. This model supports our overarching hypothesis that psychological stress, acting through increased levels of catecholamines and/or cortisol, can increase DNA damage and/or reduce repair mechanisms, resulting in increased risk of DNA mutations leading to carcinogenesis. A better understanding of molecular pathways by which psychological stress can increase the risk of cancer initiation would open new avenues of translational research, bringing together psychologists, neuroscientists, and molecular biologists, potentially resulting in the development of novel approaches for cancer risk reduction at the population level. PMID:24891812

  13. High-resolution axial MR imaging of tibial stress injuries

    PubMed Central

    2012-01-01

    Purpose To evaluate the relative involvement of tibial stress injuries using high-resolution axial MR imaging and the correlation with MR and radiographic images. Methods A total of 33 patients with exercise-induced tibial pain were evaluated. All patients underwent radiograph and high-resolution axial MR imaging. Radiographs were taken at initial presentation and 4 weeks later. High-resolution MR axial images were obtained using a microscopy surface coil with 60 × 60 mm field of view on a 1.5T MR unit. All images were evaluated for abnormal signals of the periosteum, cortex and bone marrow. Results Nineteen patients showed no periosteal reaction at initial and follow-up radiographs. MR imaging showed abnormal signals in the periosteal tissue and partially abnormal signals in the bone marrow. In 7 patients, periosteal reaction was not seen at initial radiograph, but was detected at follow-up radiograph. MR imaging showed abnormal signals in the periosteal tissue and entire bone marrow. Abnormal signals in the cortex were found in 6 patients. The remaining 7 showed periosteal reactions at initial radiograph. MR imaging showed abnormal signals in the periosteal tissue in 6 patients. Abnormal signals were seen in the partial and entire bone marrow in 4 and 3 patients, respectively. Conclusions Bone marrow abnormalities in high-resolution axial MR imaging were related to periosteal reactions at follow-up radiograph. Bone marrow abnormalities might predict later periosteal reactions, suggesting shin splints or stress fractures. High-resolution axial MR imaging is useful in early discrimination of tibial stress injuries. PMID:22574840

  14. Neural circuits in anxiety and stress disorders: a focused review

    PubMed Central

    Duval, Elizabeth R; Javanbakht, Arash; Liberzon, Israel

    2015-01-01

    Anxiety and stress disorders are among the most prevalent neuropsychiatric disorders. In recent years, multiple studies have examined brain regions and networks involved in anxiety symptomatology in an effort to better understand the mechanisms involved and to develop more effective treatments. However, much remains unknown regarding the specific abnormalities and interactions between networks of regions underlying anxiety disorder presentations. We examined recent neuroimaging literature that aims to identify neural mechanisms underlying anxiety, searching for patterns of neural dysfunction that might be specific to different anxiety disorder categories. Across different anxiety and stress disorders, patterns of hyperactivation in emotion-generating regions and hypoactivation in prefrontal/regulatory regions are common in the literature. Interestingly, evidence of differential patterns is also emerging, such that within a spectrum of disorders ranging from more fear-based to more anxiety-based, greater involvement of emotion-generating regions is reported in panic disorder and specific phobia, and greater involvement of prefrontal regions is reported in generalized anxiety disorder and posttraumatic stress disorder. We summarize the pertinent literature and suggest areas for continued investigation. PMID:25670901

  15. Stress urinary incontinence: where are we now, where should we go?

    PubMed

    DeLancey, J O

    1996-08-01

    Stress urinary incontinence results from specific damage to the muscles, fascial structures, and nerves of the pelvic floor. Scientific data are accumulating about the nature of each of these injuries. As we begin to define the damage occurring in each element of the continence mechanism, we should be able to precisely select treatment plans on the basis of the abnormality found in individual patients. For example, a woman who has lost all neural control of her pelvic muscles could be saved the useless frustration of attempting pelvic muscle strengthening, whereas a woman with intact but weak muscles can be made continent with exercise. Before these advances can be realized, we must change our current empiric approach that assigns women to treatment because they have stress urinary incontinence to one that asks about the status of each part of the continence mechanism.

  16. Interactive Effects of Nutrient and Mechanical Stresses on Plant Morphology

    PubMed Central

    Puijalon, Sara; Lena, Jean-Paul; Bornette, Gudrun

    2007-01-01

    Background and Aims Plant species frequently encounter multiple stresses under natural conditions, and the way they cope with these stresses is a major determinant of their ecological breadth. The way mechanical (e.g. wind, current) and resource stresses act simultaneously on plant morphological traits has been poorly addressed, even if both stresses often interact. This paper aims to assess whether hydraulic stress affects plant morphology in the same way at different nutrient levels. Methods An examination was made of morphological variations of an aquatic plant species growing under four hydraulic stress (flow velocity) gradients located in four habitats distributed along a nutrient gradient. Morphological traits covering plant size, dry mass allocation, organ water content and foliage architecture were measured. Key Results Significant interactive effects of flow velocity and nutrient level were observed for all morphological traits. In particular, increased flow velocity resulted in size reductions under low nutrient conditions, suggesting an adaptive response to flow stress (escape strategy). On the other hand, moderate increases in flow velocity resulted in increased size under high nutrient conditions, possibly related to an inevitable growth response to a higher nutrient supply induced by water renewal at the plant surface. For some traits (e.g. dry mass allocation), a consistent sense of variation as a result of increasing flow velocity was observed, but the amount of variation was either reduced or amplified under nutrient-rich compared with nutrient-poor conditions, depending on the traits considered. Conclusions These results suggest that, for a given species, a stress factor may result, in contrasting patterns and hence strategies, depending on a second stress factor. Such results emphasize the relevance of studies on plant responses to multiple stresses for understanding the actual ecological breadth of species. PMID:17913725

  17. Periodic mechanical stress activates EGFR-dependent Rac1 mitogenic signals in rat nucleus pulpous cells via ERK1/2

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gao, Gongming; Shen, Nan; Jiang, Xuefeng

    2016-01-15

    The mitogenic effects of periodic mechanical stress on nucleus pulpous cells have been studied extensively but the mechanisms whereby nucleus pulpous cells sense and respond to mechanical stimulation remain a matter of debate. We explored this question by performing cell culture experiments in our self-developed periodic stress field and perfusion culture system. Under periodic mechanical stress, rat nucleus pulpous cell proliferation was significantly increased (p < 0.05 for each) and was associated with increases in the phosphorylation and activation of EGFR, Rac1, and ERK1/2 (p < 0.05 for each). Pretreatment with the ERK1/2 selective inhibitor PD98059 reduced periodic mechanical stress-induced nucleus pulpous cell proliferationmore » (p < 0.05 for each), while the activation levels of EGFR and Rac1 were not inhibited. Proliferation and phosphorylation of ERK1/2 were inhibited after pretreatment with the Rac1 inhibitor NSC23766 in nucleus pulpous cells in response to periodic mechanical stress (p < 0.05 for each), while the phosphorylation site of EGFR was not affected. Inhibition of EGFR activity with AG1478 abrogated nucleus pulpous cell proliferation (p < 0.05 for each) and attenuated Rac1 and ERK1/2 activation in nucleus pulpous cells subjected to periodic mechanical stress (p < 0.05 for each). These findings suggest that periodic mechanical stress promotes nucleus pulpous cell proliferation in part through the EGFR-Rac1-ERK1/2 signaling pathway, which links these three important signaling molecules into a mitogenic cascade. - Highlights: • The mechanism involved in nucleus pulpous cells to respond to mechanical stimuli. • Periodic mechanical stress can stimulate the phosphorylation of EGFR. • EGFR activates Rac1 and leads to rat nucleus pulpous cell proliferation. • EGFR and Rac1 activate ERK1/2 mitogenic signals in nucleus pulpous cells. • EGFR-Rac1-ERK1/2 is constitutes at least one critical signal transduction pathway.« less

  18. Oxidative stress-induced telomeric erosion as a mechanism underlying airborne particulate matter-related cardiovascular disease

    PubMed Central

    2012-01-01

    Particulate matter (PM) pollution is responsible for hundreds of thousands of deaths worldwide, the majority due to cardiovascular disease (CVD). While many potential pathophysiological mechanisms have been proposed, there is not yet a consensus as to which are most important in causing pollution-related morbidity/mortality. Nor is there consensus regarding which specific types of PM are most likely to affect public health in this regard. One toxicological mechanism linking exposure to airborne PM with CVD outcomes is oxidative stress, a contributor to the development of CVD risk factors including atherosclerosis. Recent work suggests that accelerated shortening of telomeres and, thus, early senescence of cells may be an important pathway by which oxidative stress may accelerate biological aging and the resultant development of age-related morbidity. This pathway may explain a significant proportion of PM-related adverse health outcomes, since shortened telomeres accelerate the progression of many diseases. There is limited but consistent evidence that vehicular emissions produce oxidative stress in humans. Given that oxidative stress is associated with accelerated erosion of telomeres, and that shortened telomeres are linked with acceleration of biological ageing and greater incidence of various age-related pathology, including CVD, it is hypothesized that associations noted between certain pollution types and sources and oxidative stress may reflect a mechanism by which these pollutants result in CVD-related morbidity and mortality, namely accelerated aging via enhanced erosion of telomeres. This paper reviews the literature providing links among oxidative stress, accelerated erosion of telomeres, CVD, and specific sources and types of air pollutants. If certain PM species/sources might be responsible for adverse health outcomes via the proposed mechanism, perhaps the pathway to reducing mortality/morbidity from PM would become clearer. Not only would pollution

  19. Early-Life Stress: From Neuroendocrine Mechanisms to Stress-Related Disorders.

    PubMed

    Pervanidou, Panagiota; Chrousos, George P

    2018-06-08

    Stress exposure is highly prevalent in the general population; however, the experience of stress during vulnerable periods of development has substantial and permanent effects on brain structure and function and physical health in adulthood. Stress, the state of threatened homeostasis, is generally associated with a time-limited activation of the stress system, i.e., the hypothalamic-pituitary-adrenal axis and the arousal/sympathetic nervous system, tailored to the stressful stimulus also known as the stressor. On the other hand, chronic stress may be associated with lingering hyper- or hyposecretion of mediators of the stress system. This chronic condition is called dyshomeostasis, allostasis, or cacostasis and is associated with increased mental and physical morbidity in the long term. Stressful or traumatic experiences during fetal life, early childhood, and adolescence have been related to persistent neuroendocrine and epigenetic changes. Further, brain structures involved in the stress response, such as those of the stress system, the hippocampus, and the amygdala, may be programmed early on for a life of adversity. © 2018 S. Karger AG, Basel.

  20. Preventive Effects of Poloxamer 188 on Muscle Cell Damage Mechanics Under Oxidative Stress.

    PubMed

    Wong, Sing Wan; Yao, Yifei; Hong, Ye; Ma, Zhiyao; Kok, Stanton H L; Sun, Shan; Cho, Michael; Lee, Kenneth K H; Mak, Arthur F T

    2017-04-01

    High oxidative stress can occur during ischemic reperfusion and chronic inflammation. It has been hypothesized that such oxidative challenges could contribute to clinical risks such as deep tissue pressure ulcers. Skeletal muscles can be challenged by inflammation-induced or reperfusion-induced oxidative stress. Oxidative stress reportedly can lower the compressive damage threshold of skeletal muscles cells, causing actin filament depolymerization, and reduce membrane sealing ability. Skeletal muscles thus become easier to be damaged by mechanical loading under prolonged oxidative exposure. In this study, we investigated the preventive effect of poloxamer 188 (P188) on skeletal muscle cells against extrinsic oxidative challenges (H 2 O 2 ). It was found that with 1 mM P188 pre-treatment for 1 h, skeletal muscle cells could maintain their compressive damage threshold. The actin polymerization dynamics largely remained stable in term of the expression of cofilin, thymosin beta 4 and profilin. Laser photoporation demonstrated that membrane sealing ability was preserved even as the cells were challenged by H 2 O 2 . These findings suggest that P188 pre-treatment can help skeletal muscle cells retain their normal mechanical integrity in oxidative environments, adding a potential clinical use of P188 against the combined challenge of mechanical-oxidative stresses. Such effect may help to prevent deep tissue ulcer development.

  1. An Impact of Mechanical Stress in Coal Briquettes on Sorption of Carbon Dioxide

    NASA Astrophysics Data System (ADS)

    Wierzbicki, Mirosław

    2017-09-01

    The presence of gases (methane or carbon dioxide) in hard coal is connected with numerous threats for miners employed in underground mining facilities. When analyzing the coal-methane system, it is necessary to determine the relationship between pressure and gas sorption. Such a relationship should be determined under conditions similar to the natural ones - when it comes to both temperature and pressure. The present paper discusses the results of research conducted with the use of coal briquettes under the state of mechanical stress. Carbon dioxide sorption isotherms were determined for different values of stress affecting the coal material. For five coal samples collected in different mines of the Upper Silesian Coal Basin, Langmuir's sorption isotherms were determined. The results point to significant impact that mechanical stress has upon the sorption process. It is about 1 percent of the value obtained for coal not subjected to stress per 1 MPa. The research results can also prove useful when analyzing hard coal seams from the perspective of their carbon dioxide sequestration abilities.

  2. Depression and stressful environments: identifying gaps in conceptualization and measurement.

    PubMed

    Hammen, Constance

    2016-07-01

    Stress is well known as a trigger of depressive reactions, fear, anxiety, and behavioral disorders. However, there are many gaps in the conceptualization and measurement of environmental stress. Exciting developments in the neuroscience of stress have increasingly expanded our knowledge of mechanisms by which stress may affect emotional and behavioral adjustment. Ironically, environmental stress has often been a silent player in human studies of stress processes. There is a significant need for increased efforts to include environmental stress variables in models of internalizing and other disorders. Measurement and conceptualization issues are prominent, and this article makes the case for improved methods of measuring acute, chronic, and early life stress, and for additional conceptualization of the dynamically changing and bidirectional effects of stress on disorder over time. There is a critical need for greater focus on and better measurement of the environment and its impact on emotional and other disorders, with emphasis on developmentally informed hypotheses. Empirical findings and new perspectives may contribute enormously to our understanding of normal and abnormal outcomes, and also to the challenge of effective interventions to promote mental health and optimal functioning.

  3. Oxytocin and Stress-related Disorders: Neurobiological Mechanisms and Treatment Opportunities

    PubMed Central

    Sippel, Lauren M.; Allington, Casey E.; Pietrzak, Robert H.; Harpaz-Rotem, Ilan; Mayes, Linda C.; Olff, Miranda

    2017-01-01

    Novel pharmacotherapies that improve outcomes for individuals with stress-related psychiatric disorders are needed. The neurohormone oxytocin (OT) is a promising candidate given its influence on the social–emotional brain. In this review, we present an overview of evidence supporting OT’s utility for treating major depressive disorder and posttraumatic stress disorder. We first discuss endogenous OT, which research suggests is not yet a reliable biomarker of stress-related disorders. Second, we review effects of intranasal (IN) OT on processes relevant to stress-related disorders in healthy populations (anhedonia, reward processing, psychosocial stress reactivity, fear/anxiety, and social behavior) and their neurobiological mechanisms (e.g., the salience network and hypothalamic–pituitary–adrenal axis). Third, we present the sparse but promising findings from clinical populations, followed by discussion of critical moderating variables to consider in the service of maximizing the therapeutic potential of OT (e.g., patient sex and child maltreatment). We also identify heterogeneous findings and limitations of existing research, including reliance on single-dose studies in psychiatrically healthy samples and unanswered questions regarding the effectiveness of IN drug delivery and dosing schedules. Well-controlled multidose studies including women and measures of potentially moderating variables are sorely needed and would inform our understanding of the utility of OT for preventing and treating stress-related psychiatric disorders. PMID:28649672

  4. Posttraumatic Stress Disorder Disturbs Coronary Tone and Its Regulatory Mechanisms.

    PubMed

    Lazuko, Svetlana S; Kuzhel, Olga P; Belyaeva, Lyudmila E; Manukhina, Eugenia B; Fred Downey, H; Tseilikman, Olga B; Komelkova, Maria V; Tseilikman, Vadim E

    2018-01-01

    Posttraumatic stress disorder (PTSD) is associated with myocardial injury, but changes in coronary regulatory mechanisms in PTSD have not been investigated. This study evaluated the effect of PTSD-inducing stress on coronary tone and its regulation by nitric oxide (NO) and voltage-gated K + channels. PTSD was induced by exposing rats to predator stress, 15 min daily for 10 days, followed by 14 stress-free days. Presence of PTSD was confirmed by the elevated plus-maze test. Coronary tone was evaluated from changes in coronary perfusion pressure of Langendorff isolated hearts. Predator stress induced significant decreases in coronary tone of isolated hearts and in blood pressure of intact rats. L-NAME, a non-selective NO synthase (NOS) inhibitor, but not S-MT, a selective iNOS inhibitor, and increased coronary tone of control rats. In PTSD rats, both L-NAME and S-MT increased coronary tone. Therefore, the stress-induced coronary vasodilation resulted from NO overproduction by both iNOS and eNOS. NOS induction was apparently due to systemic inflammation as evidenced by increased serum interleukin-1β and C-reactive protein in PTSD rats. Decreased corticosterone in PTSD rats may have contributed to inflammation and its effect on coronary tone. PTSD was also associated with voltage-gated K + channel dysfunction, which would have also reduced coronary tone.

  5. Neural Mechanisms Underlying 5-HTTLPR Related Sensitivity to Acute Stress

    PubMed Central

    Drabant, Emily M; Ramel, Wiveka; Edge, Michael D; Hyde, Luke W; Kuo, Janice R; Goldin, Philippe R; Hariri, Ahmad R; Gross, James J

    2013-01-01

    Objective Many studies have shown that 5-HTTLPR genotype interacts with exposure to stress in conferring risk for psychopathology. However, the specific neural mechanisms through which this gene-by-environment interaction confers risk remain largely unknown, and no study to date has directly examined the modulatory effects of the 5-HTTLPR on corticolimbic circuit responses during exposure to acute stress. Methods An acute laboratory stressor was administered to 51 healthy women during BOLD fMRI scanning. In this task, electric shocks of uncertain intensity were threatened and unpredictably delivered to the wrist after a long anticipatory cue period of unpredictable duration. Results Relative to those carrying the L allele, SS homozygotes showed enhanced activation during threat anticipation in a network of regions including amygdala, hippocampus, anterior insula, thalamus, pulvinar, caudate, precuneus, anterior cingulate cortex, and medial prefrontal cortex. SS homozygotes also displayed enhanced positive coupling between medial prefrontal cortex activation and anxiety experience, whereas individuals carrying the L allele displayed enhanced negative coupling between insula activation and perceived success at regulating anxiety. Conclusions The present findings suggest that, when exposed to stress, SS homozygotes may preferentially engage neural systems which enhance fear and arousal, modulate attention toward threat, and perseverate on emotional salience of the threat. This may be one mechanism underlying risk for psychopathology conferred by the S allele upon exposure to life stressors. PMID:22362395

  6. Esophageal motility abnormalities in gastroesophageal reflux disease

    PubMed Central

    Martinucci, Irene; de Bortoli, Nicola; Giacchino, Maria; Bodini, Giorgia; Marabotto, Elisa; Marchi, Santino; Savarino, Vincenzo; Savarino, Edoardo

    2014-01-01

    Esophageal motility abnormalities are among the main factors implicated in the pathogenesis of gastroesophageal reflux disease. The recent introduction in clinical and research practice of novel esophageal testing has markedly improved our understanding of the mechanisms contributing to the development of gastroesophageal reflux disease, allowing a better management of patients with this disorder. In this context, the present article intends to provide an overview of the current literature about esophageal motility dysfunctions in patients with gastroesophageal reflux disease. Esophageal manometry, by recording intraluminal pressure, represents the gold standard to diagnose esophageal motility abnormalities. In particular, using novel techniques, such as high resolution manometry with or without concurrent intraluminal impedance monitoring, transient lower esophageal sphincter (LES) relaxations, hypotensive LES, ineffective esophageal peristalsis and bolus transit abnormalities have been better defined and strongly implicated in gastroesophageal reflux disease development. Overall, recent findings suggest that esophageal motility abnormalities are increasingly prevalent with increasing severity of reflux disease, from non-erosive reflux disease to erosive reflux disease and Barrett’s esophagus. Characterizing esophageal dysmotility among different subgroups of patients with reflux disease may represent a fundamental approach to properly diagnose these patients and, thus, to set up the best therapeutic management. Currently, surgery represents the only reliable way to restore the esophagogastric junction integrity and to reduce transient LES relaxations that are considered to be the predominant mechanism by which gastric contents can enter the esophagus. On that ground, more in depth future studies assessing the pathogenetic role of dysmotility in patients with reflux disease are warranted. PMID:24868489

  7. Esophageal motility abnormalities in gastroesophageal reflux disease.

    PubMed

    Martinucci, Irene; de Bortoli, Nicola; Giacchino, Maria; Bodini, Giorgia; Marabotto, Elisa; Marchi, Santino; Savarino, Vincenzo; Savarino, Edoardo

    2014-05-06

    Esophageal motility abnormalities are among the main factors implicated in the pathogenesis of gastroesophageal reflux disease. The recent introduction in clinical and research practice of novel esophageal testing has markedly improved our understanding of the mechanisms contributing to the development of gastroesophageal reflux disease, allowing a better management of patients with this disorder. In this context, the present article intends to provide an overview of the current literature about esophageal motility dysfunctions in patients with gastroesophageal reflux disease. Esophageal manometry, by recording intraluminal pressure, represents the gold standard to diagnose esophageal motility abnormalities. In particular, using novel techniques, such as high resolution manometry with or without concurrent intraluminal impedance monitoring, transient lower esophageal sphincter (LES) relaxations, hypotensive LES, ineffective esophageal peristalsis and bolus transit abnormalities have been better defined and strongly implicated in gastroesophageal reflux disease development. Overall, recent findings suggest that esophageal motility abnormalities are increasingly prevalent with increasing severity of reflux disease, from non-erosive reflux disease to erosive reflux disease and Barrett's esophagus. Characterizing esophageal dysmotility among different subgroups of patients with reflux disease may represent a fundamental approach to properly diagnose these patients and, thus, to set up the best therapeutic management. Currently, surgery represents the only reliable way to restore the esophagogastric junction integrity and to reduce transient LES relaxations that are considered to be the predominant mechanism by which gastric contents can enter the esophagus. On that ground, more in depth future studies assessing the pathogenetic role of dysmotility in patients with reflux disease are warranted.

  8. Cells exposed to nanosecond electrical pulses exhibit biomarkers of mechanical stress

    NASA Astrophysics Data System (ADS)

    Roth, Caleb C.; Barnes, Ronald A.; Ibey, Bennett L.; Beier, Hope T.; Moen, Erick K.; Glickman, Randolph D.

    2015-03-01

    Exposure of cells to very short (<1 μs) electric pulses in the megavolt/meter range have been shown to cause disruption of the plasma membrane. This disruption is often characterized by the formation of numerous small pores (<2 nm in diameter) in the plasma membrane that last for several minutes, allowing the flow of ions into the cell. These small pores are called nanopores and the resulting damage to the plasma membrane is referred to as nanoporation. Nanosecond electrical pulse (nsEP) exposure can impart many different stressors on a cell, including electrical, electro-chemical, and mechanical stress. Thus, nsEP exposure is not a "clean" insult, making determination of the mechanism of nanoporation quite difficult. We hypothesize that nsEP exposure creates acoustic shock waves capable of causing nanoporation. Microarray analysis of primary adult human dermal fibroblasts (HDFa) exposed to nsEP, indicated several genes associated with mechanical stress were selectively upregulated 4 h post exposure. The idea that nanoporation is caused by external mechanical force from acoustic shock waves has, to our knowledge, not been investigated. This work will critically challenge the existing paradigm that nanoporation is caused solely by an electric-field driven event and could provide the basis for a plausible explanation for electroporation.

  9. Focal mechanisms and the stress regime in NE and SW Tanzania, East Africa

    NASA Astrophysics Data System (ADS)

    Brazier, Richard A.; Nyblade, Andrew A.; Florentin, Juliette

    2005-07-01

    We report 12 new focal mechanisms from earthquakes in NE and SW Tanzania where the stress regime within the East African rift system is not well constrained. Focal mechanisms for events at the intersection of the Lake Tanganyika and Rukwa rifts in SW Tanzania indicate a complicated stress pattern with possible dextral strike-slip motion on some faults but oblique motion on others (either sinistral on NW striking faults or dextral on NE striking faults). Within the Rukwa rift, focal mechanisms indicate normal dip-slip motion with NE-SW opening. In NE Tanzania where the Eastern rift impinges on the margin of the Tanzania Craton, fault motions are consistent with a zone of distributed block faults and sub E-W extension. All twelve earthquakes likely nucleated within the crust.

  10. Fetal Alcohol Spectrum Disorders and Abnormal Neuronal Plasticity

    PubMed Central

    Medina, Alexandre E.

    2012-01-01

    The ingestion of alcohol during pregnancy can result in a group of neurobehavioral abnormalities collectively known as fetal alcohol spectrum disorders (FASD). During the past decade, studies using animal models indicated that early alcohol exposure can dramatically affect neuronal plasticity, an essential property of the central nervous system responsible for the normal wiring of the brain and involved in processes such as learning and memory. The abnormalities in neuronal plasticity caused by alcohol can explain many of the neurobehavioral deficits observed in FASD. Conversely, improving neuronal plasticity may have important therapeutic benefits. In this review, the author discuss the mechanisms that lead to these abnormalities and comment on recent pharmacological approaches that have been showing promising results in improving neuronal plasticity in FASD. PMID:21383101

  11. Role of insular cortex in visceral hypersensitivity model in rats subjected to chronic stress.

    PubMed

    Yi, LiSha; Sun, HuiHui; Ge, Chao; Chen, Ying; Peng, HaiXia; Jiang, YuanXi; Wu, Ping; Tang, YinHan; Meng, QingWei; Xu, ShuChang

    2014-12-30

    Abnormal processing of visceral sensation at the level of the central nervous system has been proven to be important in the pathophysiologic mechanisms of stress related functional gastrointestinal disorders. However, the specific mechanism is still not clear. The insular cortex (IC) was considered as one important visceral sensory area. Moreover, the IC has been shown to be involved in various neuropsychiatric diseases such as panic disorders and post-traumatic stress disorder. However, whether the IC is important in psychological stress related visceral hypersensitivity has not been studied yet. In our study, through destruction of the bilateral IC, we explored whether the IC played a critical role in the formation of visceral hypersensitivity induced by chronic stress on rats. Chronic partial restraint stress was used to establish viscerally hypersensitive rat model. Bilateral IC lesions were generated by N-methyl-D-day (door) aspartate. After a recovery period of 7 days, 14-day consecutive restraint stress was performed. The visceromotor response to colorectal distension was monitored by recording electromyogram to measure rats׳ visceral sensitivity. We found that bilateral insular cortex lesion could markedly inhibit the formation of visceral hypersensitivity induced by chronic stress. The insular cortex plays a critical role in the pathophysiology of stress-related visceral hypersensitivity.

  12. A mechanical model of metatarsal stress fracture during distance running.

    PubMed

    Gross, T S; Bunch, R P

    1989-01-01

    A model of metatarsal mechanics has been proposed as a link between the high incidence of second and third metatarsal stress fractures and the large stresses measured beneath the second and third metatarsal heads during distance running. Eight discrete piezoelectric vertical stress transducers were used to record the forefoot stresses of 21 male distance runners. Based upon load bearing area estimates derived from footprints, plantar forces were estimated. Highest force was estimated beneath the second and first metatarsal head (341.1 N and 279.1 N, respectively). Considering the toe as a hinged cantilever and the metatarsal as a proximally attached rigid cantilever allowed estimation of metatarsal midshaft bending strain, shear, and axial forces. Bending strain was estimated to be greatest in the second metatarsal (6662 mu epsilon), a value 6.9 times greater than estimated first metatarsal strain. Predicted third, fourth, and fifth metatarsal strains ranged between 4832 and 5241 mu epsilon. Shear force estimates were also greatest in the second metatarsal (203.0 N). Axial forces were highest in the first metatarsal (593.2 N) due to large hallux forces in relationship to the remaining toes. Although a first order model, these data highlight the structural demands placed upon the second metatarsal, a location of high metatarsal stress fracture incidence during distance running.

  13. ER-stress and apoptosis: molecular mechanisms and potential relevance in infection.

    PubMed

    Häcker, Georg

    2014-10-01

    During ER-stress, one of the responses a cell can choose is apoptosis. Apoptosis generally is a cell's preferred response when other control mechanisms are overwhelmed. We now have a reasonably clear molecular picture what is happening once the apoptotic apparatus has been started. Unclear however are the majority of the upstream pathways that connect other signalling to apoptosis. During ER-stress, confirmed apoptosis-regulating targets are pro- and anti-apoptotic proteins of the Bcl-2-family, whose concerted action induces apoptosis. I will here discuss how mitochondrial apoptosis is triggered, how this is linked to the ER-stress response and in what way this may be relevant during microbial infections. Copyright © 2014 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  14. Losing the sugar coating: potential impact of perineuronal net abnormalities on interneurons in schizophrenia.

    PubMed

    Berretta, Sabina; Pantazopoulos, Harry; Markota, Matej; Brown, Christopher; Batzianouli, Eleni T

    2015-09-01

    Perineuronal nets (PNNs) were shown to be markedly altered in subjects with schizophrenia. In particular, decreases of PNNs have been detected in the amygdala, entorhinal cortex and prefrontal cortex. The formation of these specialized extracellular matrix (ECM) aggregates during postnatal development, their functions, and association with distinct populations of GABAergic interneurons, bear great relevance to the pathophysiology of schizophrenia. PNNs gradually mature in an experience-dependent manner during late stages of postnatal development, overlapping with the prodromal period/age of onset of schizophrenia. Throughout adulthood, PNNs regulate neuronal properties, including synaptic remodeling, cell membrane compartmentalization and subsequent regulation of glutamate receptors and calcium channels, and susceptibility to oxidative stress. With the present paper, we discuss evidence for PNN abnormalities in schizophrenia, the potential functional impact of such abnormalities on inhibitory circuits and, in turn, cognitive and emotion processing. We integrate these considerations with results from recent genetic studies showing genetic susceptibility for schizophrenia associated with genes encoding for PNN components, matrix-regulating molecules and immune system factors. Notably, the composition of PNNs is regulated dynamically in response to factors such as fear, reward, stress, and immune response. This regulation occurs through families of matrix metalloproteinases that cleave ECM components, altering their functions and affecting plasticity. Several metalloproteinases have been proposed as vulnerability factors for schizophrenia. We speculate that the physiological process of PNN remodeling may be disrupted in schizophrenia as a result of interactions between matrix remodeling processes and immune system dysregulation. In turn, these mechanisms may contribute to the dysfunction of GABAergic neurons. Copyright © 2015. Published by Elsevier B.V.

  15. Non-Contact Technique for Determining the Mechanical Stress in thin Films on Wafers by Profiler

    NASA Astrophysics Data System (ADS)

    Djuzhev, N. A.; Dedkova, A. A.; E Gusev, E.; Makhiboroda, M. A.; Glagolev, P. Y.

    2017-04-01

    This paper presents an algorithm for analysis of relief for the purpose of calculating mechanical stresses in a selected direction on the plate in the form of software package Matlab. The method allows for the measurement sample in the local area. It provides a visual representation of the data and allows to get stress distribution on wafer surface. Automated analysis process reduces the likelihood of errors researcher. Achieved time saving during processing results. In carrying out several measurements possible drawing card plate to predict yield crystals. According to this technique done in measurement of mechanical stresses of thermal silicon oxide film on a silicon substrate. Analysis of the results showed objectivity and reliability calculations. This method can be used for selecting the optimal parameters of the material deposition conditions. In software of device-technological simulation TCAD defined process time, temperature and oxidation of the operation of the sample environment for receiving the set value of the dielectric film thickness. Calculated thermal stresses are in the system silicon-silicon oxide. There is a good correlation between numerical simulations and analytical calculation. It is shown that the nature of occurrence of mechanical stress is not limited to the difference of thermal expansion coefficients of materials.

  16. Stress, burnout and depression: A systematic review on DNA methylation mechanisms.

    PubMed

    Bakusic, Jelena; Schaufeli, Wilmar; Claes, Stephan; Godderis, Lode

    2017-01-01

    Despite that burnout presents a serious burden for modern society, there are no diagnostic criteria. Additional difficulty is the differential diagnosis with depression. Consequently, there is a need to dispose of a burnout biomarker. Epigenetic studies suggest that DNA methylation is a possible mediator linking individual response to stress and psychopathology and could be considered as a potential biomarker of stress-related mental disorders. Thus, the aim of this review is to provide an overview of DNA methylation mechanisms in stress, burnout and depression. In addition to state-of-the-art overview, the goal of this review is to provide a scientific base for burnout biomarker research. We performed a systematic literature search and identified 25 pertinent articles. Among these, 15 focused on depression, 7 on chronic stress and only 3 on work stress/burnout. Three epigenome-wide studies were identified and the majority of studies used the candidate-gene approach, assessing 12 different genes. The glucocorticoid receptor gene (NR3C1) displayed different methylation patterns in chronic stress and depression. The serotonin transporter gene (SLC6A4) methylation was similarly affected in stress, depression and burnout. Work-related stress and depressive symptoms were associated with different methylation patterns of the brain derived neurotrophic factor gene (BDNF) in the same human sample. The tyrosine hydroxylase (TH) methylation was correlated with work stress in a single study. Additional, thoroughly designed longitudinal studies are necessary for revealing the cause-effect relationship of work stress, epigenetics and burnout, including its overlap with depression. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Influence of engineered interfaces on residual stresses and mechanical response in metal matrix composites

    NASA Technical Reports Server (NTRS)

    Arnold, Steven M.; Wilt, Thomas E.

    1992-01-01

    Because of the inherent coefficient of thermal expansion (CTE) mismatch between fiber and matrix within metal and intermetallic matrix composite systems, high residual stresses can develop under various thermal loading conditions. These conditions include cooling from processing temperature to room temperature as well as subsequent thermal cycling. As a result of these stresses, within certain composite systems, radial, circumferential, and/or longitudinal cracks have been observed to form at the fiber matrix interface region. A number of potential solutions for reducing this thermally induced residual stress field have been proposed recently. Examples of some potential solutions are high CTE fibers, fiber preheating, thermal anneal treatments, and an engineered interface. Here the focus is on designing an interface (by using a compensating/compliant layer concept) to reduce or eliminate the thermal residual stress field and, therefore, the initiation and propagation of cracks developed during thermal loading. Furthermore, the impact of the engineered interface on the composite's mechanical response when subjected to isothermal mechanical load histories is examined.

  18. Stress-driven lithium dendrite growth mechanism and dendrite mitigation by electroplating on soft substrates

    NASA Astrophysics Data System (ADS)

    Wang, Xu; Zeng, Wei; Hong, Liang; Xu, Wenwen; Yang, Haokai; Wang, Fan; Duan, Huigao; Tang, Ming; Jiang, Hanqing

    2018-03-01

    Problems related to dendrite growth on lithium-metal anodes such as capacity loss and short circuit present major barriers to next-generation high-energy-density batteries. The development of successful lithium dendrite mitigation strategies is impeded by an incomplete understanding of the Li dendrite growth mechanisms, and in particular, Li-plating-induced internal stress in Li metal and its effect on Li growth morphology are not well addressed. Here, we reveal the enabling role of plating residual stress in dendrite formation through depositing Li on soft substrates and a stress-driven dendrite growth model. We show that dendrite growth is mitigated on such soft substrates through surface-wrinkling-induced stress relaxation in the deposited Li film. We demonstrate that this dendrite mitigation mechanism can be utilized synergistically with other existing approaches in the form of three-dimensional soft scaffolds for Li plating, which achieves higher coulombic efficiency and better capacity retention than that for conventional copper substrates.

  19. A mechanical property and stress corrosion evaluation of Custom 455 stainless steel alloy

    NASA Technical Reports Server (NTRS)

    Montano, J. W.

    1972-01-01

    The mechanical and stress corrosion properties are presented of vacuum melted Custom 455 stainless steel alloy bar (1.0-inch diameter) and sheet (0.083-inch thick) material aged at 950 F, 1000 F, and 1050 F. Low temperature mechanical properties were determined at temperatures of 80 F, 0 F, -100 F, and -200 F. For all three aging treatments, the ultimate tensile and 0.2 percent offset yield strengths increased with decreasing test temperatures while the elongation held fairly constant down to -100 F and decreased at -200 F. Reduction in Area decreased moderately with decreasing temperature for the longitudinal round (0.250-inch diameter) specimens. Notched tensile strength and charpy V-notched impact strength decreased with decreasing test temperature. For all three aging treatments, no failures were observed in the unstressed specimens or the specimens stressed to 50, 75, and 100 percent of their yield strengths for 180 days of alternate immersion testing in a 3.5 percent NaCl solution. As indicated by the results of tensile tests performed after alternate immersion testing, the mechanical properties of Custom 455 alloy were not affected by stress or exposure under the conditions of the evaluation.

  20. Physiological Mechanism of Enhancing Salt Stress Tolerance of Perennial Ryegrass by 24-Epibrassinolide

    PubMed Central

    Wu, Wenli; Zhang, Qiang; Ervin, Erik. H.; Yang, Zhiping; Zhang, Xunzhong

    2017-01-01

    Brassinosteroids (BR) regulate plant tolerance to salt stress but the mechanisms underlying are not fully understood. This study was to investigate physiological mechanisms of 24-epibrassinolide (EBR)'s impact on salt stress tolerance in perennial ryegrass (Lolium perenne L.) The grass seedlings were treated with EBR at 0, 10, and 100 nM, and subjected to salt stress (250 mM NaCl). The grass irrigated with regular water without EBR served as the control. Salt stress increased leaf electrolyte leakage (EL), malondialdehyde (MDA), and reduced photosynthetic rate (Pn). Exogenous EBR reduced EL and MDA, increased Pn, chlorophyll content, and stomatal conductance (gs). The EBR applications also alleviated decline of superoxide dismutase (SOD) and catalase (CAT) and ascorbate peroxidase (APX) activity when compared to salt treatment alone. Salt stress increased leaf abscisic acid (ABA) and gibberellin A4 (GA4) content but reduced indole-3-acetic acid (IAA), zeatin riboside (ZR), isopentenyl adenosine (iPA), and salicylic acid (SA). Exogenous EBR at 10 nm and 100 nM increased ABA, and iPA content under salt stress. The EBR treatment at 100 nM also increased leaf IAA, ZR, JA, and SA. In addition, EBR treatments increased leaf proline and ions (K+, Mg2+, and Ca2+) content, and reduced Na+/K+ in leaf tissues. The results of this study suggest that EBR treatment may improve salt stress tolerance by increasing the level of selected hormones and antioxidant enzyme (SOD and CAT) activity, promoting accumulation of proline and ions (K+, Ca2+, and Mg2+) in perennial ryegrass. PMID:28674542

  1. Focal Mechanisms and Stress Environment of the 12 May 2008 Wenchuan, China, Earthquake Sequence

    NASA Astrophysics Data System (ADS)

    Zhao, L.; Luo, Y.; Ni, S.

    2012-12-01

    The 12 May 2008 Wenchuan earthquake (Mw=7.9) was the largest earthquake in China ever recorded by modern seismic instruments. It generated numerous moderate sized aftershocks that were well recorded by both permanent stations as well as portable instruments deployed after the mainshock. These waveform records yield high-quality data for the determination of focal mechanisms of aftershocks, which in turn provide important information for the investigation of regional stress field and the seismogenic environment in the Wenchuan earthquake source region. In this study, we determine the focal mechanisms, depths and moment magnitudes of moderate-sized (Mw ≥ 4.0) Wenchuan aftershocks using broadband waveform records. The focal mechanism results are then used to obtain the orientation and ratio of the principle stresses by the damped linear stress inversion method of Hardebeck & Michael (2006). Our results show that the majority of the moderate aftershocks occur at a depth range of 10-20 km and outside of the major rupture zones of the mainshock. The Wenchuan source region remains under a nearly horizontal compression with mostly thrust and occasional strike-slip faulting, especially towards the two ends of the rupture of the main shock. There is also clearly local variations in the orientation of the principle stresses.

  2. Oxidative and inflammatory signals in obesity-associated vascular abnormalities.

    PubMed

    Reho, John J; Rahmouni, Kamal

    2017-07-15

    Obesity is associated with increased cardiovascular morbidity and mortality in part due to vascular abnormalities such as endothelial dysfunction and arterial stiffening. The hypertension and other health complications that arise from these vascular defects increase the risk of heart diseases and stroke. Prooxidant and proinflammatory signaling pathways as well as adipocyte-derived factors have emerged as critical mediators of obesity-associated vascular abnormalities. Designing treatments aimed specifically at improving the vascular dysfunction caused by obesity may provide an effective therapeutic approach to prevent the cardiovascular sequelae associated with excessive adiposity. In this review, we discuss the recent evidence supporting the role of oxidative stress and cytokines and inflammatory signals within the vasculature as well as the impact of the surrounding perivascular adipose tissue (PVAT) on the regulation of vascular function and arterial stiffening in obesity. In particular, we focus on the highly plastic nature of the vasculature in response to altered oxidant and inflammatory signaling and highlight how weight management can be an effective therapeutic approach to reduce the oxidative stress and inflammatory signaling and improve vascular function. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  3. Calcium ion involvement in growth inhibition of mechanically stressed soybean (Glycine max) seedlings

    NASA Technical Reports Server (NTRS)

    Jones, R. S.; Mitchell, C. A.

    1989-01-01

    A 40-50% reduction in soybean [Glycine max (L.) Merr. cv. Century 84] hypocotyl elongation occurred 24 h after application of mechanical stress. Exogenous Ca2+ at 10 mM inhibited growth by 28% if applied with the Ca2+ ionophore A23187 to the zone of maximum hypocotyl elongation. La3+ was even more inhibitory than Ca2+, especially above 5 mM. Treatment with ethyleneglycol-bis-(beta-aminoethylether)-N, N, N', N'-tetraacetic acid (EGTA) alone had no effect on growth of non-stressed seedlings at the concentrations used but negated stress-induced growth reduction by 36% at 4 mM when compared to non-treated, stressed controls. Treatment with EDTA was ineffective in negating stress-induced growth inhibition. Calmodulin antagonists calmidazolium, chlorpromazine, and 48/80 also negated stress-induced growth reduction by 23, 50, and 35%, respectively.

  4. Reversion of left ventricular systolic dysfunction and abnormal stress test: by catheter ablation, in a patient with Wolff-Parkinson-White syndrome from Para-Hisian Kent bundle.

    PubMed

    Tu, Chung-Ming; Chu, Kai-Ming; Cheng, Cheng-Chung; Cheng, Shu-Mung; Lin, Wei-Shiang

    2010-01-01

    The diagnosis of Wolff-Parkinson-White syndrome is typically reserved for patients who experience ventricular pre-excitation and symptoms that are related to paroxysmal supraventricular tachycardia, such as chest pain, dyspnea, dizziness, palpitations, or syncope. Herein, we report the case of a 38-year-old woman who presented at our outpatient department because of exercise intolerance. Cardiac auscultation revealed a grade 2/6 pansystolic murmur over the left lower sternal border. Twelve-lead electrocardiography showed sinus rhythm at a rate of 76 beats/min, with a significant delta wave. Transthoracic echocardiography revealed abnormal left ventricular systolic function. The results of a thallium stress test were also abnormal. Coronary artery disease was suspected; however, coronary angiography yielded normal results. Electrophysiologic study revealed a para-Hisian Kent bundle and a dual atrioventricular nodal pathway. After radiofrequency catheter ablation was performed, the patient's left ventricular function improved and her symptoms disappeared. In Wolff-Parkinson-White syndrome, left ventricular systolic dyssynchrony can yield abnormal findings on echocardiography and thallium scanning--even in persons who have no cardiovascular risk factors. Physicians who are armed with this knowledge can avoid performing coronary angiography unnecessarily. Catheter ablation can reverse the dyssynchrony of the ventricle and improve the patient's symptoms.

  5. A Comparison between Deep and Shallow Stress Fields in Korea Using Earthquake Focal Mechanism Inversions and Hydraulic Fracturing Stress Measurements

    NASA Astrophysics Data System (ADS)

    Lee, Rayeon; Chang, Chandong; Hong, Tae-kyung; Lee, Junhyung; Bae, Seong-Ho; Park, Eui-Seob; Park, Chan

    2016-04-01

    We are characterizing stress fields in Korea using two types of stress data: earthquake focal mechanism inversions (FMF) and hydraulic fracturing stress measurements (HF). The earthquake focal mechanism inversion data represent stress conditions at 2-20 km depths, whereas the hydraulic fracturing stress measurements, mostly conducted for geotechnical purposes, have been carried out at depths shallower than 1 km. We classified individual stress data based on the World Stress Map quality ranking scheme. A total of 20 FMF data were classified into A-B quality, possibly representing tectonic stress fields. A total of 83 HF data out of compiled 226 data were classified into B-C quality, which we use for shallow stress field characterization. The tectonic stress, revealed from the FMF data, is characterized by a remarkable consistency in its maximum stress (σ1) directions in and around Korea (N79±2° E), indicating a quite uniform deep stress field throughout. On the other hand, the shallow stress field, represented by HF data, exhibits local variations in σ1 directions, possibly due to effects of topography and geologic structures such as faults. Nonetheless, there is a general similarity in σ1 directions between deep and shallow stress fields. To investigate the shallow stress field statistically, we follow 'the mean orientation and wavelength analysis' suggested by Reiter et al. (2014). After the stress pattern analysis, the resulting stress points distribute sporadically over the country, not covering the entire region evenly. In the western part of Korea, the shallow σ1directions are generally uniform with their search radius reaching 100 km, where the average stress direction agrees well with those of the deep tectonic stress. We note two noticeable differences between shallow and deep stresses in the eastern part of Korea. First, the shallow σ1 orientations are markedly non-uniform in the southeastern part of Korea with their search radius less than 25 km

  6. Oxidative stress and mechanisms of ochronosis in alkaptonuria.

    PubMed

    Braconi, Daniela; Millucci, Lia; Bernardini, Giulia; Santucci, Annalisa

    2015-11-01

    Alkaptonuria (AKU) is a rare metabolic disease due to a deficient activity of the enzyme homogentisate 1,2-dioxygenase (HGD), involved in Phe and Tyr catabolism. Due to such a deficiency, AKU patients undergo accumulation of the metabolite homogentisic acid (HGA), which is prone to oxidation/polymerization reactions causing the production of a melanin-like pigment. Once the pigment is deposited onto connective tissues (mainly in joints, spine, and cardiac valves), a classical bluish-brown discoloration is imparted, leading to a phenomenon known as "ochronosis", the hallmark of AKU. A clarification of the molecular mechanisms for the production and deposition of the ochronotic pigment in AKU started only recently with a range of in vitro and ex vivo human models used for the study of HGA-induced effects. Thanks to redox-proteomic analyses, it was found that HGA could induce significant oxidation of a number of serum and chondrocyte proteins. Further investigations allowed highlighting how HGA-induced proteome alteration, lipid peroxidation, thiol depletion, and amyloid production could contribute to oxidative stress generation and protein oxidation in AKU. This review briefly summarizes the most recent findings on HGA-induced oxidative stress in AKU, helping in the clarification of the molecular mechanisms of ochronosis and potentially providing the basis for its pharmacological treatment. Future work should be undertaken in order to validate in vivo the results so far obtained in in vitro AKU models. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. [Application of mechanical measurement in assessment of neck pain and manual therapy].

    PubMed

    Wang, Kuan; Deng, Zhen; Wang, Hui-Hao; Niu, Wen-Xin; Zhan, Hong-Sheng

    2016-07-25

    Manual therapy is one of the effective methods in treating neck pain. It has certain advantages in the short term to ease the symptoms of neck pain. In recent years, using different mechanical sensors and imaging equipment with computer software, the researchers found the difference of cervical activity between health adult and patients with neck pain. They also analyzed the kinematics, magnitude of force, stress and strain of the related structure and other mechanical parameters during cervical manipulation. These biomechanical researches revealed the functional anomaly caused by neck pain, reflect the safety of cervical manipulation, explain the abnormal stress of neck pain and the adjusting role of manipulation. Relatively speaking, these studies are too basic, and their analysis also are limited for the stress and strain about internal tissue. Study to aim directly at above problems will have important significance in understanding neck pain and standardizing manipulation therapy. Copyright© 2016 by the China Journal of Orthopaedics and Traumatology Press.

  8. Plasma fibronectin stabilizes Borrelia burgdorferi–endothelial interactions under vascular shear stress by a catch-bond mechanism

    PubMed Central

    Niddam, Alexandra F.; Ebady, Rhodaba; Bansal, Anil; Koehler, Anne; Hinz, Boris

    2017-01-01

    Bacterial dissemination via the cardiovascular system is the most common cause of infection mortality. A key step in dissemination is bacterial interaction with endothelia lining blood vessels, which is physically challenging because of the shear stress generated by blood flow. Association of host cells such as leukocytes and platelets with endothelia under vascular shear stress requires mechanically specialized interaction mechanisms, including force-strengthened catch bonds. However, the biomechanical mechanisms supporting vascular interactions of most bacterial pathogens are undefined. Fibronectin (Fn), a ubiquitous host molecule targeted by many pathogens, promotes vascular interactions of the Lyme disease spirochete Borrelia burgdorferi. Here, we investigated how B. burgdorferi exploits Fn to interact with endothelia under physiological shear stress, using recently developed live cell imaging and particle-tracking methods for studying bacterial–endothelial interaction biomechanics. We found that B. burgdorferi does not primarily target insoluble matrix Fn deposited on endothelial surfaces but, instead, recruits and induces polymerization of soluble plasma Fn (pFn), an abundant protein in blood plasma that is normally soluble and nonadhesive. Under physiological shear stress, caps of polymerized pFn at bacterial poles formed part of mechanically loaded adhesion complexes, and pFn strengthened and stabilized interactions by a catch-bond mechanism. These results show that B. burgdorferi can transform a ubiquitous but normally nonadhesive blood constituent to increase the efficiency, strength, and stability of bacterial interactions with vascular surfaces. Similar mechanisms may promote dissemination of other Fn-binding pathogens. PMID:28396443

  9. Effects of mechanical stress or abscisic acid on growth, water status and leaf abscisic acid content of eggplant seedlings

    NASA Technical Reports Server (NTRS)

    Latimer, J. G.; Mitchell, C. A.

    1988-01-01

    Container-grown eggplant (Solanum melongena L. var esculentum Nees. 'Burpee's Black Beauty') seedlings were conditioned with brief, periodic mechanical stress or abscisic acid (ABA) in a greenhouse prior to outdoor exposure. Mechanical stress consisted of seismic (shaking) or thigmic (stem flexing) treatment. Exogenous ABA (10(-3) or 10(-4)M) was applied as a soil drench 3 days prior to outdoor transfer. During conditioning, only thigmic stress reduced stem elongation and only 10(-3) M ABA reduced relative growth rate (RGR). Both conditioning treatments increased leaf specific chlorophyll content, but mechanical stress did not affect leaf ABA content. Outdoor exposure of unconditioned eggplant seedlings decreased RGR and leaf-specific chlorophyll content, but tended to increase leaf ABA content relative to that of plants maintained in the greenhouse. Conditioning did not affect RGR of plants subsequently transferred outdoors, but did reduce stem growth. Seismic stress applied in the greenhouse reduced dry weight gain by plants subsequently transferred outdoors. Mechanical stress treatments increased leaf water potential by 18-25% relative to that of untreated plants.

  10. Cell cycle control, checkpoint mechanisms, and genotoxic stress.

    PubMed Central

    Shackelford, R E; Kaufmann, W K; Paules, R S

    1999-01-01

    The ability of cells to maintain genomic integrity is vital for cell survival and proliferation. Lack of fidelity in DNA replication and maintenance can result in deleterious mutations leading to cell death or, in multicellular organisms, cancer. The purpose of this review is to discuss the known signal transduction pathways that regulate cell cycle progression and the mechanisms cells employ to insure DNA stability in the face of genotoxic stress. In particular, we focus on mammalian cell cycle checkpoint functions, their role in maintaining DNA stability during the cell cycle following exposure to genotoxic agents, and the gene products that act in checkpoint function signal transduction cascades. Key transitions in the cell cycle are regulated by the activities of various protein kinase complexes composed of cyclin and cyclin-dependent kinase (Cdk) molecules. Surveillance control mechanisms that check to ensure proper completion of early events and cellular integrity before initiation of subsequent events in cell cycle progression are referred to as cell cycle checkpoints and can generate a transient delay that provides the cell more time to repair damage before progressing to the next phase of the cycle. A variety of cellular responses are elicited that function in checkpoint signaling to inhibit cyclin/Cdk activities. These responses include the p53-dependent and p53-independent induction of Cdk inhibitors and the p53-independent inhibitory phosphorylation of Cdk molecules themselves. Eliciting proper G1, S, and G2 checkpoint responses to double-strand DNA breaks requires the function of the Ataxia telangiectasia mutated gene product. Several human heritable cancer-prone syndromes known to alter DNA stability have been found to have defects in checkpoint surveillance pathways. Exposures to several common sources of genotoxic stress, including oxidative stress, ionizing radiation, UV radiation, and the genotoxic compound benzo[a]pyrene, elicit cell cycle

  11. Mechanisms by which stress can lead to coronary heart disease.

    PubMed Central

    Henry, J. P.

    1986-01-01

    Much stress is of psychological origin and due to emotional arousal. The mechanisms by which anger, helplessness, or a sense of control and serenity exert their various neuroendocrine effects are discussed. Primacy is given to three systems; to the catecholamines, to testosterone and to cortisol. Evidence that they interact to accelerate the arteriosclerotic process is cited. The protective aspects of intimacy are discussed together with evidence that certain personality types promote it in the marital situation while others do not. It is suggested that the post-traumatic stress syndrome may relate to the coronary-prone personality for it involves an alexithymic disturbance of the emotional competence required for successful intimacy. PMID:3748938

  12. Environmental stress induces trinucleotide repeat mutagenesis in human cells.

    PubMed

    Chatterjee, Nimrat; Lin, Yunfu; Santillan, Beatriz A; Yotnda, Patricia; Wilson, John H

    2015-03-24

    The dynamic mutability of microsatellite repeats is implicated in the modification of gene function and disease phenotype. Studies of the enhanced instability of long trinucleotide repeats (TNRs)-the cause of multiple human diseases-have revealed a remarkable complexity of mutagenic mechanisms. Here, we show that cold, heat, hypoxic, and oxidative stresses induce mutagenesis of a long CAG repeat tract in human cells. We show that stress-response factors mediate the stress-induced mutagenesis (SIM) of CAG repeats. We show further that SIM of CAG repeats does not involve mismatch repair, nucleotide excision repair, or transcription, processes that are known to promote TNR mutagenesis in other pathways of instability. Instead, we find that these stresses stimulate DNA rereplication, increasing the proportion of cells with >4 C-value (C) DNA content. Knockdown of the replication origin-licensing factor CDT1 eliminates both stress-induced rereplication and CAG repeat mutagenesis. In addition, direct induction of rereplication in the absence of stress also increases the proportion of cells with >4C DNA content and promotes repeat mutagenesis. Thus, environmental stress triggers a unique pathway for TNR mutagenesis that likely is mediated by DNA rereplication. This pathway may impact normal cells as they encounter stresses in their environment or during development or abnormal cells as they evolve metastatic potential.

  13. Psychological stress and fibromyalgia: a review of the evidence suggesting a neuroendocrine link

    PubMed Central

    Gupta, Anindya; Silman, Alan J

    2004-01-01

    The present review attempts to reconcile the dichotomy that exists in the literature in relation to fibromyalgia, in that it is considered either a somatic response to psychological stress or a distinct organically based syndrome. Specifically, the hypothesis explored is that the link between chronic stress and the subsequent development of fibromyalgia can be explained by one or more abnormalities in neuroendocrine function. There are several such abnormalities recognised that both occur as a result of chronic stress and are observed in fibromyalgia. Whether such abnormalities have an aetiologic role remains uncertain but should be testable by well-designed prospective studies. PMID:15142258

  14. Abnormalities in amphibian populations inhabiting agroecosystems in Northeastern Buenos Aires Province, Argentina.

    PubMed

    Agostini, M G; Kacoliris, F; Demetrio, P; Natale, G S; Bonetto, C; Ronco, A E

    2013-05-27

    The occurrence of abnormalities in amphibians has been reported in many populations, and its increase could be related to environmental pollution and habitat degradation. We evaluated the type and prevalence of abnormalities in 5 amphibian populations from agroecosystems with different degrees of agricultural disturbance (cultivated and reference areas). We detected 9 types of abnormalities, of which the most frequent were those occurring in limbs. The observed prevalence of abnormality in assessed populations from cultivated and reference areas was as follows: Rhinella fernandezae (37.1 and 10.2%, respectively), Leptodactylus latrans adults (28.1 and 9.2%) and juveniles (32.9 and 15.3%), and Hypsiboas pulchellus (11.6 and 2.8%). Scinax granulatus populations did not show abnormalities. Pseudis minuta, which was only detected in the reference area, exhibited a prevalence of 13.3%. For R. fernandezae, L. latrans, and H. pulchellus, generalized linear mixed models showed that prevalence of abnormalities was significantly higher (p < 0.05) in cultivated than in reference areas. L. latrans juveniles were more vulnerable to abnormalities than adults (p < 0.05). The presence of abnormalities in some species inhabiting different agroecosystems suggests that environmental stress factors might be responsible for their occurrence. While we detected pesticides (endosulfan, cypermethrin, and chlorpyrifos) and lower dissolved oxygen levels in ponds of the cultivated area, no data are currently available on how other factors, such as injuries from predators and parasite infections, vary by land use. Further research will be necessary to evaluate possible causes of abnormalities detected in the present study mainly in the context of factor interactions.

  15. Feeling Abnormal: Simulation of Deviancy in Abnormal and Exceptionality Courses.

    ERIC Educational Resources Information Center

    Fernald, Charles D.

    1980-01-01

    Describes activity in which student in abnormal psychology and psychology of exceptional children classes personally experience being judged abnormal. The experience allows the students to remember relevant research, become sensitized to the feelings of individuals classified as deviant, and use caution in classifying individuals as abnormal.…

  16. [Investigation of Wnt/β-catenin signaling pathway on regulation of Runx2 in cementoblasts under mechanical stress in vitro].

    PubMed

    Shuqin, Li; Shan, Yang; Aishu, Ren; Hongwei, Dai

    2015-02-01

    Periodontal tissue remodeling includes remodeling of alveolar bone, periodontal ligament, and cementum. Cementoblast plays a main role in repairing root resorption. Canonical Wnt/β-catenin signaling can promote the odontogenic differentiation in osteoblast. However, the mechanism on how the orthodontic force influences the function of cementoblast and the relationship between the canonical Wnt/β-catenin signaling and Runx2 of cementoblast are not yet known. The aim of this study is focus on this relationship. OCCM30 cementoblasts were subjected to mechanical strain by four-point bending system with tension stress for 0, 3, 6, and 12 h. They were pretreated with different concentrations of Dikkopf-1 (DKK1) for 48 h. Western blot analysis was performed to detect the β-catenin levels in the nucleus. Runx2 mRNA was observed by real-time quantitative polymerase chain reaction (RT-PCR). OCCM30 cementoblasts were then pretreated with 150 ng · mL(-1) DKK1 for 48 h and subjected to mechanical strain by FX4000T system with tension stress for 12 h. Western blot analysis was conducted to detect the β-catenin levels in the nucleus, and Runx2 mRNA was observed by RT-PCR. OCCM30 cementoblasts had significantly higher Runx2 mRNA and β-catenin levels after being loaded with mechanical stress. The amount of Runx2 mRNA in OCCM30 cementoblasts was significantly decreased by DKK1. When OCCM30 cemento-blasts were pretreated with DKK1 without stress, their β-catenin level was significantly decreased by DKK1 and Wnt signaling was blocked. When they were not pretreated with stress, the β-catenin level with DKK1 was lower than that without DKK1. Without DKK1, the β-catenin level in OCCM30 cemento- blasts increased afterbeing loaded with mechanical stress. With DKK1, the β-catenin level in OCCM30 cementoblasts, which were loaded with mechanical stress, was higher than that without mechanical stress. Cementoblasts had higher Runx2 mRNA expression under mechanical stress because of

  17. Abnormal Uterine Bleeding

    MedlinePlus

    ... abnormal uterine bleeding? Abnormal uterine bleeding is any heavy or unusual bleeding from the uterus (through your ... one symptom of abnormal uterine bleeding. Having extremely heavy bleeding during your period can also be considered ...

  18. PECVD silicon-rich nitride and low stress nitride films mechanical characterization using membrane point load deflection

    NASA Astrophysics Data System (ADS)

    Bagolini, Alvise; Picciotto, Antonino; Crivellari, Michele; Conci, Paolo; Bellutti, Pierluigi

    2016-02-01

    An analysis of the mechanical properties of plasma enhanced chemical vapor (PECVD) silicon nitrides is presented, using micro fabricated silicon nitride membranes under point load deflection. The membranes are made of PECVD silicon-rich nitride and low stress nitride films. The mechanical performance of the bended membranes is examined both with analytical models and finite element simulation in order to extract the elastic modulus and residual stress values. The elastic modulus of low stress silicon nitride is calculated using stress free analytical models, while for silicon-rich silicon nitride and annealed low stress silicon nitride it is estimated with a pre-stressed model of point-load deflection. The effect of annealing both in nitrogen and hydrogen atmosphere is evaluated in terms of residual stress, refractive index and thickness variation. It is demonstrated that a hydrogen rich annealing atmosphere induces very little change in low stress silicon nitride. Nitrogen annealing effects are measured and shown to be much higher in silicon-rich nitride than in low stress silicon nitride. An estimate of PECVD silicon-rich nitride elastic modulus is obtained in the range between 240-320 GPa for deposited samples and 390 GPa for samples annealed in nitrogen atmosphere. PECVD low stress silicon nitride elastic modulus is estimated to be 88 GPa as deposited and 320 GPa after nitrogen annealing.

  19. Relating cell shape and mechanical stress in a spatially disordered epithelium using a vertex-based model

    PubMed Central

    Nestor-Bergmann, Alexander; Goddard, Georgina; Woolner, Sarah; Jensen, Oliver E

    2018-01-01

    Abstract Using a popular vertex-based model to describe a spatially disordered planar epithelial monolayer, we examine the relationship between cell shape and mechanical stress at the cell and tissue level. Deriving expressions for stress tensors starting from an energetic formulation of the model, we show that the principal axes of stress for an individual cell align with the principal axes of shape, and we determine the bulk effective tissue pressure when the monolayer is isotropic at the tissue level. Using simulations for a monolayer that is not under peripheral stress, we fit parameters of the model to experimental data for Xenopus embryonic tissue. The model predicts that mechanical interactions can generate mesoscopic patterns within the monolayer that exhibit long-range correlations in cell shape. The model also suggests that the orientation of mechanical and geometric cues for processes such as cell division are likely to be strongly correlated in real epithelia. Some limitations of the model in capturing geometric features of Xenopus epithelial cells are highlighted. PMID:28992197

  20. Prenatal Stress, Prematurity, and Asthma.

    PubMed

    Medsker, Brock; Forno, Erick; Simhan, Hyagriv; Celedón, Juan C

    2015-12-01

    Asthma is the most common chronic disease of childhood, affecting millions of children in the United States and worldwide. Prematurity is a risk factor for asthma, and certain ethnic or racial minorities such as Puerto Ricans and non-Hispanic blacks are disproportionately affected by both prematurity and asthma. In this review, we examine current evidence to support maternal psychosocial stress as a putative link between prematurity and asthma, while also focusing on disruption of the hypothalamic-pituitary-adrenal (HPA) axis and immune responses as potential underlying mechanisms for stress-induced "premature asthma." Prenatal stress may cause not only abnormalities in the HPA axis but also epigenetic changes in the fetal glucocorticoid receptor gene (NR3C1), leading to impaired glucocorticoid metabolism. Moreover, maternal stress can alter fetal cytokine balance, favoring TH2 (allergic) immune responses characteristic of atopic asthma: interleukin 6 (IL-6), which has been associated with premature labor, can promote TH2 responses by stimulating production of IL-4 and IL-13. Given a link among stress, prematurity, and asthma, future research should include birth cohorts aimed at confirming and better characterizing "premature asthma." If confirmed, clinical trials of prenatal maternal stress reduction would be warranted to reduce the burden of these common comorbidities. While awaiting the results of such studies, sound policies to prevent domestic and community violence (eg, from firearms) are justified, not only by public safety but also by growing evidence of detrimental effects of violence-induced stress on psychiatric and somatic health.

  1. Prenatal stress, prematurity and asthma

    PubMed Central

    Medsker, Brock; Forno, Erick; Simhan, Hyagriv; Celedón, Juan C.

    2016-01-01

    Asthma is the most common chronic disease of childhood, affecting millions of children in the U.S. and worldwide. Prematurity is a risk factor for asthma, and certain ethnic or racial minorities such as Puerto Ricans and non-Hispanic Blacks are disproportionately affected by both prematurity and asthma. In this review, we examine current evidence to support maternal psychosocial stress as a putative link between prematurity and asthma, while also focusing on disruption of the hypothalamic-pituitary-adrenal (HPA) axis and immune responses as potential underlying mechanisms for stress-induced “premature asthma”. Prenatal stress may not only cause abnormalities in the HPA axis but also epigenetic changes in the fetal glucocorticoid receptor gene (NR3C1), leading to impaired glucocorticoid metabolism. Moreover, maternal stress can alter fetal cytokine balance, favoring Th2 (allergic) immune responses characteristic of atopic asthma: IL-6, which has been associated with premature labor, can promote Th2 responses by stimulating production of IL-4 and IL-13. Given a link among stress, prematurity, and asthma, future research should include birth cohorts aimed at confirming and better characterizing “premature asthma”. If confirmed, clinical trials of prenatal maternal stress reduction would be warranted to reduce the burden of these common co-morbidities. While awaiting the results of such studies, sound policies to prevent domestic and community violence (e.g. from firearms) are justified, not only by public safety but also by growing evidence of detrimental effects of violence-induced stress on psychiatric and somatic health. PMID:26676148

  2. Activation of peroxisome proliferator-activated receptor (PPAR)delta promotes reversal of multiple metabolic abnormalities, reduces oxidative stress, and increases fatty acid oxidation in moderately obese men.

    PubMed

    Risérus, Ulf; Sprecher, Dennis; Johnson, Tony; Olson, Eric; Hirschberg, Sandra; Liu, Aixue; Fang, Zeke; Hegde, Priti; Richards, Duncan; Sarov-Blat, Leli; Strum, Jay C; Basu, Samar; Cheeseman, Jane; Fielding, Barbara A; Humphreys, Sandy M; Danoff, Theodore; Moore, Niall R; Murgatroyd, Peter; O'Rahilly, Stephen; Sutton, Pauline; Willson, Tim; Hassall, David; Frayn, Keith N; Karpe, Fredrik

    2008-02-01

    Pharmacological use of peroxisome proliferator-activated receptor (PPAR)delta agonists and transgenic overexpression of PPARdelta in mice suggest amelioration of features of the metabolic syndrome through enhanced fat oxidation in skeletal muscle. We hypothesize a similar mechanism operates in humans. The PPARdelta agonist (10 mg o.d. GW501516), a comparator PPARalpha agonist (20 mug o.d. GW590735), and placebo were given in a double-blind, randomized, three-parallel group, 2-week study to six healthy moderately overweight subjects in each group. Metabolic evaluation was made before and after treatment including liver fat quantification, fasting blood samples, a 6-h meal tolerance test with stable isotope fatty acids, skeletal muscle biopsy for gene expression, and urinary isoprostanes for global oxidative stress. Treatment with GW501516 showed statistically significant reductions in fasting plasma triglycerides (-30%), apolipoprotein B (-26%), LDL cholesterol (-23%), and insulin (-11%), whereas HDL cholesterol was unchanged. A 20% reduction in liver fat content (P < 0.05) and 30% reduction in urinary isoprostanes (P = 0.01) were also observed. Except for a lowering of triglycerides (-30%, P < 0.05), none of these changes were observed in response to GW590735. The relative proportion of exhaled CO(2) directly originating from the fat content of the meal was increased (P < 0.05) in response to GW501516, and skeletal muscle expression of carnitine palmitoyl-transferase 1b (CPT1b) was also significantly increased. The PPARdelta agonist GW501516 reverses multiple abnormalities associated with the metabolic syndrome without increasing oxidative stress. The effect is probably caused by increased fat oxidation in skeletal muscle.

  3. Interrelations between hydraulic and mechanical stress adaptations in woody plants

    PubMed Central

    Ennos, A Roland; Fournier, Meriem

    2008-01-01

    The fields of plant water relations and plant biomechanics have traditionally been studied separately even though often the same tissues are responsible for water transport and mechanical support. There is now increasing evidence that hydraulic and mechanical adaptations may influence one another. We studied the changes in the hydraulic and mechanical properties of the wood along lateral roots of two species of buttressed trees. In these roots, the mechanical contstraints quantified by strain measurements are known to decrease distally. Further, we investigated the effect of mechanical loading on the vessel anatomy in these and four other species of tropical trees. We found that as the strain decreased, the wood became progressively less stiff and strong but the conductivity increased exponentially. This was reflected in that adaptations towards re-enforcing mechanically loaded areas resulted in xylem with fewer and smaller vessels. In addition a controlled growth experiment on three tree species showed that drought adaptation may results in plants with stronger and stiffer tissue. Our results indicate that hydraulic and mechanical stress adaptations may be interrelated, and so support recent studied suggesting that physiological responses are complex balances rather than pure optimisations. PMID:19704486

  4. The effects of mechanical stress and spectral shading on the growth and allocation of ten genotypes of a stoloniferous plant.

    PubMed

    Liu, Yun; Schieving, Feike; Stuefer, Josef F; Anten, Niels P R

    2007-01-01

    Because plants protect each other from wind, stand density affects both the light climate and the amount of mechanical stress experienced by plants. But the potential interactive effects of mechanical stress and canopy shading on plant growth have rarely been investigated and never in stoloniferous plants which, due to their creeping growth form, can be expected to respond differently to these factors than erect plants. Plants of ten genotypes of the stoloniferous species Potentilla reptans were subjected to two levels of mechanical stress (0 or 40 daily flexures) and two levels of spectral shading (15 % of daylight with a red:far red ratio of 0.3 vs. 50 % daylight and a red:far red ratio of 1.2). Mechanically stressed plants produced more leaves with shorter more flexible petioles, more roots, and more but less massive stolons. Responses to spectral shading were mostly in the opposite direction to thigmomorphogenesis, including the production of thinner, taller petioles made of more rigid tissue. The degree of thigmomorphogenesis was either independent of light climate or stimulated by spectral shading. At the genotypic level there were no clear correlations between responses to shade and mechanical stress. These results suggest that in stoloniferous plants mechanical stress results in clones with a more compact, shorter shoot structure and more roots. This response does not appear to be suppressed by canopy shading, which suggests that wind shielding (reduced mechanical stress) by neighbours in dense vegetation serves as a cue that induces shade avoidance responses such as increased petiole elongation.

  5. Thermo-hydro-mechanical stresses during repeat glacial cycles as preparatory factors for paraglacial rock slope instabilities

    NASA Astrophysics Data System (ADS)

    Grämiger, Lorenz; Moore, Jeffrey R.; Gischig, Valentin; Loew, Simon

    2015-04-01

    Glaciation and deglaciation contribute to stress redistribution in alpine valley rock slopes, generating rock mass damage. However, the physical processes contributing to slope instability during glacial cycles are not well understood, and the mechanical reasoning remains vague. In addition to glacier loading and unloading, thermal strains affect newly exposed bedrock while changes in hillslope hydrology modify effective stresses. Together these can generate damage and reduce rock slope stability over time. Here we explore the role of coupled thermo-hydro-mechanical (THM) stress changes in driving long-term progressive damage and conditioning paraglacial rock slope failure in the Aletsch glacier region of Switzerland. We develop a 2D numerical model using the distinct element code UDEC, creating a fractured rock slope containing rock mass elements of intact rock, discontinuities, and fault zones. Topography, rock properties and glacier history are all loosely based on real conditions in the Aletsch valley. In-situ stresses representing pre-LGM conditions with inherent rock mass damage are initialized. We model stress changes through multiple glacier cycles during the Lateglacial and Holocene; stress redistribution is not only induced by glacier loading, but also by changes in bedrock temperatures and transient hillslope hydrology. Each THM response mechanism is tied to the changing ice extents, therefore stress changes and resulting rock mass damage can be explored in both space and time. We analyze cyclic THM stresses and resulting damage during repeat glacial cycles, and compare spatiotemporal outputs with the mapped landslide distribution in the Aletsch region. Our results extend the concept of glacial debuttressing, lead to improved understanding of the rock mass response to glacial cycles, and clarify coupled interactions driving paraglacial rock mass damage.

  6. Research on Formation Mechanism of Dynamic Response and Residual Stress of Sheet Metal Induced by Laser Shock Wave

    NASA Astrophysics Data System (ADS)

    Feng, Aixin; Cao, Yupeng; Wang, Heng; Zhang, Zhengang

    2018-01-01

    In order to reveal the quantitative control of the residual stress on the surface of metal materials, the relevant theoretical and experimental studies were carried out to investigate the dynamic response of metal thin plates and the formation mechanism of residual stress induced by laser shock wave. In this paper, the latest research trends on the surface residual stress of laser shock processing technology were elaborated. The main progress of laser shock wave propagation mechanism and dynamic response, laser shock, and surface residual stress were discussed. It is pointed out that the multi-scale characterization of laser and material, surface residual stress and microstructure change is a new hotspot in laser shock strengthening technology.

  7. The action of chemical and mechanical stresses on single and dual species biofilm removal of drinking water bacteria.

    PubMed

    Gomes, I B; Lemos, M; Mathieu, L; Simões, M; Simões, L C

    2018-08-01

    The presence of biofilms in drinking water distribution systems (DWDS) is a global public health concern as they can harbor pathogenic microorganisms. Sodium hypochlorite (NaOCl) is the most commonly used disinfectant for microbial growth control in DWDS. However, its effect on biofilm removal is still unclear. This work aims to evaluate the effects of the combination of chemical (NaOCl) and mechanical stresses on the removal of single and dual species biofilms of two bacteria isolated from DWDS and considered opportunistic, Acinectobacter calcoaceticus and Stenotrophomonas maltophilia. A rotating cylinder reactor was successfully used for the first time in drinking water biofilm studies with polyvinyl chloride as substratum. The single and dual species biofilms presented different characteristics in terms of metabolic activity, mass, density, thickness and content of proteins and polysaccharides. Their complete removal was not achieved even when a high NaOCl concentrations and an increasing series of shear stresses (from 2 to 23Pa) were applied. In general, NaOCl pre-treatment did not improve the impact of mechanical stress on biofilm removal. Dual species biofilms were colonized mostly by S. maltophilia and were more susceptible to chemical and mechanical stresses than these single species. The most efficient treatment (93% biofilm removal) was the combination of NaOCl at 175mg·l -1 with mechanical stress against dual species biofilms. Of concern was the high tolerance of S. maltophilia to chemical and mechanical stresses in both single and dual species biofilms. The overall results demonstrate the inefficacy of NaOCl on biofilm removal even when combined with high shear stresses. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Analysis of the mechanical stresses on a squirrel cage induction motor by the finite element method

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jun, C.H.; Nicolas, A.

    1999-05-01

    The mechanical deformations and stresses have been analyzed by the Finite Element Method (FEM) in 3 dimensions on the rotor bars of a small squirrel cage induction motor. The authors considered the magnetic forces and the centrifugal forces as sources which provoked the deformations and stresses on the rotor bars. The mechanical calculations have been performed after doing the electromagnetic Finite Element modeling on the motor in steady states with various slip conditions.

  9. Acid Stress Response Mechanisms of Group B Streptococci

    PubMed Central

    Shabayek, Sarah; Spellerberg, Barbara

    2017-01-01

    Group B streptococcus (GBS) is a leading cause of neonatal mortality and morbidity in the United States and Europe. It is part of the vaginal microbiota in up to 30% of pregnant women and can be passed on to the newborn through perinatal transmission. GBS has the ability to survive in multiple different host niches. The pathophysiology of this bacterium reveals an outstanding ability to withstand varying pH fluctuations of the surrounding environments inside the human host. GBS host pathogen interations include colonization of the acidic vaginal mucosa, invasion of the neutral human blood or amniotic fluid, breaching of the blood brain barrier as well as survival within the acidic phagolysosomal compartment of macrophages. However, investigations on GBS responses to acid stress are limited. Technologies, such as whole genome sequencing, genome-wide transcription and proteome mapping facilitate large scale identification of genes and proteins. Mechanisms enabling GBS to cope with acid stress have mainly been studied through these techniques and are summarized in the current review PMID:28936424

  10. Modeling of Mechanical Stress Exerted by Cholesterol Crystallization on Atherosclerotic Plaques.

    PubMed

    Luo, Yuemei; Cui, Dongyao; Yu, Xiaojun; Chen, Si; Liu, Xinyu; Tang, Hongying; Wang, Xianghong; Liu, Linbo

    2016-01-01

    Plaque rupture is the critical cause of cardiovascular thrombosis, but the detailed mechanisms are not fully understood. Recent studies have found abundant cholesterol crystals in ruptured plaques, and it has been proposed that the rapid expansion of cholesterol crystals in a limited space during crystallization may contribute to plaque rupture. To evaluate the effect of cholesterol crystal growth on atherosclerotic plaques, we modeled the expansion of cholesterol crystals during the crystallization process in the necrotic core and estimated the stress on the thin cap with different arrangements of cholesterol crystals. We developed a two-dimensional finite element method model of atherosclerotic plaques containing expanding cholesterol crystals and investigated the effect of the magnitude and distribution of crystallization on the peak circumferential stress born by the cap. Using micro-optical coherence tomography (μOCT), we extracted the cross-sectional geometric information of cholesterol crystals in human atherosclerotic aorta tissue ex vivo and applied the information to the model. The results demonstrate that (1) the peak circumference stress is proportionally dependent on the cholesterol crystal growth; (2) cholesterol crystals at the cap shoulder impose the highest peak circumference stress; and (3) spatial distributions of cholesterol crystals have a significant impact on the peak circumference stress: evenly distributed cholesterol crystals exert less peak circumferential stress on the cap than concentrated crystals.

  11. ADDITIONAL STRESS AND FRACTURE MECHANICS ANALYSES OF PRESSURIZED WATER REACTOR PRESSURE VESSEL NOZZLES

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Walter, Matthew; Yin, Shengjun; Stevens, Gary

    2012-01-01

    In past years, the authors have undertaken various studies of nozzles in both boiling water reactors (BWRs) and pressurized water reactors (PWRs) located in the reactor pressure vessel (RPV) adjacent to the core beltline region. Those studies described stress and fracture mechanics analyses performed to assess various RPV nozzle geometries, which were selected based on their proximity to the core beltline region, i.e., those nozzle configurations that are located close enough to the core region such that they may receive sufficient fluence prior to end-of-life (EOL) to require evaluation of embrittlement as part of the RPV analyses associated with pressure-temperaturemore » (P-T) limits. In this paper, additional stress and fracture analyses are summarized that were performed for additional PWR nozzles with the following objectives: To expand the population of PWR nozzle configurations evaluated, which was limited in the previous work to just two nozzles (one inlet and one outlet nozzle). To model and understand differences in stress results obtained for an internal pressure load case using a two-dimensional (2-D) axi-symmetric finite element model (FEM) vs. a three-dimensional (3-D) FEM for these PWR nozzles. In particular, the ovalization (stress concentration) effect of two intersecting cylinders, which is typical of RPV nozzle configurations, was investigated. To investigate the applicability of previously recommended linear elastic fracture mechanics (LEFM) hand solutions for calculating the Mode I stress intensity factor for a postulated nozzle corner crack for pressure loading for these PWR nozzles. These analyses were performed to further expand earlier work completed to support potential revision and refinement of Title 10 to the U.S. Code of Federal Regulations (CFR), Part 50, Appendix G, Fracture Toughness Requirements, and are intended to supplement similar evaluation of nozzles presented at the 2008, 2009, and 2011 Pressure Vessels and Piping (PVP

  12. Stress Orientations in the Fort Worth Basin, Texas, Determined from Earthquake Focal Mechanisms

    NASA Astrophysics Data System (ADS)

    Quinones, L. A.; DeShon, H. R.

    2017-12-01

    Since October 2008 the Fort Worth Basin (FWB), an active shale gas production field in northeastern Texas, has experienced over 30 M3.0+ earthquakes, including one M4.0. These events have primarily occurred on faults in the Precambrian basement and within the overlying Ellenburger Limestone formation, which acts as the primary wastewater disposal unit in the FWB. We generate focal mechanism catalogs for the 2013-2015 Azle-Reno, 2014-present Irving-Dallas, and 2015 Venus earthquake sequences using P-wave first motion and S-to-P wave amplitude ratio data collected from the local seismic networks operating in the region. The mechanisms show little variability when compared to natural intraplate sequences, and are most consistent with failure on NE-SW striking normal faults. Stress inversions indicate maximum regional horizontal stress in the basement strikes 20-30° N of E, consistent with shallower borehole breakout data for the basin, and within this stress regime that all seismogenic faults in the FWB are optimally oriented for failure. We show via Mohr circle diagrams that small stress perturbations on these preexisting basement faults, of magnitudes similar to those observed or modeled to be associated with wastewater disposal, are capable of inducing the earthquakes that occurred in the Azle-Reno, Irving-Dallas, and Venus earthquake sequences.

  13. Reactive transport under stress: Permeability evolution by chemo-mechanical deformation

    NASA Astrophysics Data System (ADS)

    Roded, R.; Holtzman, R.

    2017-12-01

    The transport of reactive fluids in porous media is important in many natural and engineering processes. Reaction with the solid matrix—e.g. dissolution—changes the transport properties, which in turn affect the rate of reagent transport and hence the reaction. The importance of this highly nonlinear problem has motivated intensive research. Specifically, there have been numerous studies concerning the permeability evolution, especially the process of "wormholing", where preferential dissolution of the most conductive regions leads to a runaway permeability increase. Much less attention, however, has been given to the effect of geomechanics; that is, how the fact that the medium is under stress changes the permeability evolution. Here, we present a novel, mechanistic pore-scale model, simulating the interplay between pore opening by matrix dissolution and pore closure by mechanical compaction, facilitated by weakening caused by the very same process of dissolution. We combine a pore network model of reactive transport with a block-spring model that captures the effect of geomechanics through the update of the network properties. Our simulations show that permeability enhancement is inhibited by stress concentration downstream, in the less dissolved (hence stiffer) regions. Higher stresses lead to stronger inhibition, in agreement with experiments. The effect of stress also depends on the Damkohler number (Da)—the ratio between the flow and the reaction rate. At rapid injection (small Da), where dissolution is relatively uniform, stress has a significant effect on permeability. At slower flow rates (high Da, wormholing regime), stress affects the permeability evolution mostly in early stages, with a much smaller effect on the injected volume required for a significant permeability increase (breakthrough) than at low Da. Interestingly, at higher Da, stress concentration downstream induced by the more heterogeneous dissolution leads to a more homogeneous reagent

  14. Decreased SGK1 Expression and Function Contributes to Behavioral Deficits Induced by Traumatic Stress

    PubMed Central

    Licznerski, Pawel; Duric, Vanja; Banasr, Mounira; Alavian, Kambiz N.; Ota, Kristie T.; Kang, Hyo Jung; Jonas, Elizabeth A.; Ursano, Robert; Krystal, John H.; Duman, Ronald S.

    2015-01-01

    Exposure to extreme stress can trigger the development of major depressive disorder (MDD) as well as post-traumatic stress disorder (PTSD). The molecular mechanisms underlying the structural and functional alterations within corticolimbic brain regions, including the prefrontal cortex (PFC) and amygdala of individuals subjected to traumatic stress, remain unknown. In this study, we show that serum and glucocorticoid regulated kinase 1 (SGK1) expression is down-regulated in the postmortem PFC of PTSD subjects. Furthermore, we demonstrate that inhibition of SGK1 in the rat medial PFC results in helplessness- and anhedonic-like behaviors in rodent models. These behavioral changes are accompanied by abnormal dendritic spine morphology and synaptic dysfunction. Together, the results are consistent with the possibility that altered SGK1 signaling contributes to the behavioral and morphological phenotypes associated with traumatic stress pathophysiology. PMID:26506154

  15. Psychosocial stress in pregnancy and preterm birth: associations and mechanisms

    PubMed Central

    Shapiro, Gabriel D.; Fraser, William D.; Frasch, Martin G.; Séguin, Jean R.

    2016-01-01

    Aims Psychosocial stress during pregnancy (PSP) is a risk factor of growing interest in the etiology of preterm birth (PTB). This literature review assesses the published evidence concerning the association between PSP and PTB, highlighting established and hypothesized physiological pathways mediating this association. Method The PubMed and Web of Science databases were searched using the keywords “psychosocial stress”, “pregnancy”, “pregnancy stress”, “preterm”, “preterm birth”, “gestational age”, “anxiety”, and “social support”. After applying the exclusion criteria, the search produced 107 articles. Results The association of PSP with PTB varied according to the dimensions and timing of PSP. Stronger associations were generally found in early pregnancy, and most studies demonstrating positive results found moderate effect sizes, with risk ratios between 1.2 and 2.1. Subjective perception of stress and pregnancy-related anxiety appeared to be the stress measures most closely associated with PTB. Potential physiological pathways identified included behavioral, infectious, neuroinflammatory, and neuroendocrine mechanisms. Conclusions Future research should examine the biological pathways of these different psychosocial stress dimensions and at multiple time points across pregnancy. Culture-independent characterization of the vaginal microbiome and noninvasive monitoring of cholinergic activity represent two exciting frontiers in this research. PMID:24216160

  16. Gamma-band abnormalities as markers of autism spectrum disorders

    PubMed Central

    Rojas, Donald C.; Wilson, Lisa B.

    2014-01-01

    Summary Autism is a behaviorally diagnosed neurodevelopmental disorder with no current biomarkers with high specificity and sensitivity. Gamma-band abnormalities have been reported in many studies of autism spectrum disorders. Gamma-band activity is associated with perceptual and cognitive functions that are compromised in autism. Some gamma-band deficits have also been seen in unaffected first-degree relatives, suggesting heritability of these findings. This review covers the published literature on gamma abnormalities in autism, the proposed mechanisms underlying the deficits, and the potential for translation into new treatments. Although the utility of gamma-band metrics as diagnostic biomarkers is currently limited, such changes in autism are also useful as endophenotypes, for evaluating potential neural mechanisms, and for use as surrogate markers of treatment response to interventions. PMID:24712425

  17. Félix Voisin and the genesis of abnormals.

    PubMed

    Doron, Claude-Olivier

    2015-12-01

    This article traces the genealogy of the category of 'abnormals' in psychiatry. It focuses on the French alienist Felix Voisin (1794-1872) who played a decisive role in the creation of alienist knowledge and institutions for problem children, criminals, idiots and lunatics. After a presentation of the category of 'abnormals' as understood at the end of the nineteenth century, I identify in the works of Voisin a key moment in the concept's evolution. I show how, based on concepts borrowed from phrenology and applied first to idiocy, Voisin allows alienism to establish links between the medico-legal (including penitentiary) and medical-educational fields (including difficult childhood). I stress the extent to which this enterprise is related to Voisin's humanism, which claimed to remodel pedagogy and the right to punish on the anthropological particularities of individuals, in order to improve them. © The Author(s) 2015.

  18. The effects of magnetic and mechanical microstructures on the twinning stress in Ni-Mn-Ga

    NASA Astrophysics Data System (ADS)

    Faran, Eilon; Benichou, Itamar; Givli, Sefi; Shilo, Doron

    2015-12-01

    The ferromagnetic 10M Ni-Mn-Ga alloy exhibits complex magnetic and mechanical microstructures, which are expected to form barriers for motion of macro twin boundaries. Here, the contributions of both microstructures to the magnitude of the twinning stress property are investigated experimentally. A series of uniaxial loading-unloading curves are taken under different orientation angles of a constant magnetic field. The different 180 ° magnetic domains microstructures that are formed across the twin boundary in each case are visualised using a magneto optical film. Analysis of the different loading curves and the corresponding magnetic microstructures show that the latter does not contribute to the barriers for twin boundary motion. In accordance, the internal resisting stress for twin boundary motion under any magnetic field can be taken as the twinning stress measured in the absence of an external field. In addition, a statistical analysis of the fine features in the loading profiles reveals that the barrier for twinning is associated with a μ m sized characteristic length scale. This length scale corresponds to the typical thickness of micro-twinning laminates that constitute a mechanical microstructure. These findings indicate that the magnitude of the twinning stress in 10M Ni-Mn-Ga is determined by the characteristic fine twinned mechanical microstructure of this alloy.

  19. The mechanics of delamination in fiber-reinforced composite materials. I - Stress singularities and solution structure

    NASA Technical Reports Server (NTRS)

    Wang, S. S.; Choi, I.

    1983-01-01

    The fundamental mechanics of delamination in fiber composite laminates is studied. Mathematical formulation of the problem is based on laminate anisotropic elasticity theory and interlaminar fracture mechanics concepts. Stress singularities and complete solution structures associated with general composite delaminations are determined. For a fully open delamination with traction-free surfaces, oscillatory stress singularities always appear, leading to physically inadmissible field solutions. A refined model is introduced by considering a partially closed delamination with crack surfaces in finite-length contact. Stress singularities associated with a partially closed delamination having frictional crack-surface contact are determined, and are found to be different from the inverse square-root one of the frictionless-contact case. In the case of a delamination with very small area of crack closure, a simplified model having a square-root stress singularity is employed by taking the limit of the partially closed delamination. The possible presence of logarithmic-type stress singularity is examined; no logarithmic singularity of any kind is found in the composite delamination problem. Numerical examples of dominant stress singularities are shown for delaminations having crack-tip closure with different frictional coefficients between general (1) and (2) graphite-epoxy composites. Previously announced in STAR as N84-13221

  20. Sugarcane Water Stress Tolerance Mechanisms and Its Implications on Developing Biotechnology Solutions

    PubMed Central

    Ferreira, Thais H. S.; Tsunada, Max S.; Bassi, Denis; Araújo, Pedro; Mattiello, Lucia; Guidelli, Giovanna V.; Righetto, Germanna L.; Gonçalves, Vanessa R.; Lakshmanan, Prakash; Menossi, Marcelo

    2017-01-01

    Sugarcane is a unique crop with the ability to accumulate high levels of sugar and is a commercially viable source of biomass for bioelectricity and second-generation bioethanol. Water deficit is the single largest abiotic stress affecting sugarcane productivity and the development of water use efficient and drought tolerant cultivars is an imperative for all major sugarcane producing countries. This review summarizes the physiological and molecular studies on water deficit stress in sugarcane, with the aim to help formulate more effective research strategies for advancing our knowledge on genes and mechanisms underpinning plant response to water stress. We also overview transgenic studies in sugarcane, with an emphasis on the potential strategies to develop superior sugarcane varieties that improve crop productivity in drought-prone environments. PMID:28690620

  1. A mechanical model of the San Andreas fault and SAFOD Pilot Hole stress measurements

    USGS Publications Warehouse

    Chery, J.; Zoback, M.D.; Hickman, S.

    2004-01-01

    Stress measurements made in the SAFOD pilot hole provide an opportunity to study the relation between crustal stress outside the fault zone and the stress state within it using an integrated mechanical model of a transform fault loaded in transpression. The results of this modeling indicate that only a fault model in which the effective friction is very low (<0.1) through the seismogenic thickness of the crust is capable of matching stress measurements made in both the far field and in the SAFOD pilot hole. The stress rotation measured with depth in the SAFOD pilot hole (???28??) appears to be a typical feature of a weak fault embedded in a strong crust and a weak upper mantle with laterally variable heat flow, although our best model predicts less rotation (15??) than observed. Stress magnitudes predicted by our model within the fault zone indicate low shear stress on planes parallel to the fault but a very anomalous mean stress, approximately twice the lithostatic stress. Copyright 2004 by the American Geophysical Union.

  2. Abnormal positive bias stress instability of In–Ga–Zn–O thin-film transistors with low-temperature Al{sub 2}O{sub 3} gate dielectric

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chang, Yu-Hong; Yu, Ming-Jiue; Lin, Ruei-Ping

    2016-01-18

    Low-temperature atomic layer deposition (ALD) was employed to deposit Al{sub 2}O{sub 3} as a gate dielectric in amorphous In–Ga–Zn–O thin-film transistors fabricated at temperatures below 120 °C. The devices exhibited a negligible threshold voltage shift (ΔV{sub T}) during negative bias stress, but a more pronounced ΔV{sub T} under positive bias stress with a characteristic turnaround behavior from a positive ΔV{sub T} to a negative ΔV{sub T}. This abnormal positive bias instability is explained using a two-process model, including both electron trapping and hydrogen release and migration. Electron trapping induces the initial positive ΔV{sub T}, which can be fitted using the stretchedmore » exponential function. The breakage of residual AlO-H bonds in low-temperature ALD Al{sub 2}O{sub 3} is triggered by the energetic channel electrons. The hydrogen atoms then diffuse toward the In–Ga–Zn–O channel and induce the negative ΔV{sub T} through electron doping with power-law time dependence. A rapid partial recovery of the negative ΔV{sub T} after stress is also observed during relaxation.« less

  3. Epigenetic mechanisms in fear conditioning: Implications for treating post-traumatic stress disorder

    PubMed Central

    Kwapis, Janine L.; Wood, Marcelo A.

    2014-01-01

    Post-traumatic stress disorder (PTSD) and other anxiety disorders stemming from dysregulated fear memory are problematic and costly. Understanding the molecular mechanisms that contribute to the formation and maintenance of these persistent fear associations is critical to developing treatments for PTSD. Epigenetic mechanisms, which control gene expression to produce long-lasting changes in cellular function, may support the formation of fear memory underlying PTSD. Here, we address the role of epigenetic mechanisms in the formation, storage, updating, and extinction of fear memories and discuss methods of targeting these epigenetic mechanisms to reduce the initial formation of fear memory or to enhance its extinction. Epigenetic mechanisms may provide a novel target for pharmaceutical and other treatments to reduce aversive memory contributing to PTSD. PMID:25220045

  4. Influence of interfaces density and thermal processes on mechanical stress of PECVD silicon nitride

    NASA Astrophysics Data System (ADS)

    Picciotto, A.; Bagolini, A.; Bellutti, P.; Boscardin, M.

    2009-10-01

    The paper focuses on a particular silicon nitride thin film (SiN x) produced by plasma enahanced chemical vapor deposition (PECVD) technique with high deposition rate (26 nm/min) and low values of mechanical stress (<100 MPa). This was perfomed with mixed frequency procedure varying the modulation of high frequency at 13.56 MHz and low frequency at 308 kHz of RF power supply during the deposition, without changing the ratio of reaction gases. Low stress silicon nitride is commonly obtained by tailoring the thickness ratio of high frequency vs. low frequency silicon nitride layers. The attention of this work was directed to the influence of the number of interfaces per thickness unit on the stress characteristics of the deposited material. Two sets of wafer samples were deposited with low stress silicon nitride, with a thickness of 260 nm and 2 μm, respectively. Thermal annealing processes at 380 and 520 °C in a inert enviroment were also performed on the wafers. The Stoney-Hoffman model was used to estimate the stress values by wafer curvature measurement with a mechanical surface profilometer: the stress was calculated for the as-deposited layer, and after each annealing process. The thickness and the refractive index of the SiN x were also measured and charaterized by variable angle spectra elliposometry (VASE) techinique. The experimental measurements were performed at the MT-LAB, IRST (Istituto per la Ricerca Scientifica e Tecnologica) of Bruno Kessler Foundation for Research in Trento.

  5. Carotid artery mechanical properties and stresses quantified using in vivo data from normotensive and hypertensive humans.

    PubMed

    Masson, Ingrid; Beaussier, Hélène; Boutouyrie, Pierre; Laurent, Stéphane; Humphrey, Jay D; Zidi, Mustapha

    2011-12-01

    The goal of this study was to model the in vivo non-linear mechanical behavior of human common carotid arteries (CCAs) and then to compare wall stresses and associated contributions of micro-constituents in normotensive (NT) and treated hypertensive (HT) subjects. We used an established theoretical model of 3D arterial mechanics that assumes a hyperelastic, anisotropic, active-passive, and residually stressed wall. In vivo data were obtained non-invasively from CCAs in 16 NT (21-64 years old) and 25 treated HT (44-69 years old) subjects. The associated quasi-static boundary value problem was solved semi-analytically over a cardiac cycle while accounting for surrounding perivascular tissue. Best-fit values of model parameters, including those describing contributions by intramural elastin, fibrillar collagen, and vascular smooth muscle, were estimated by a non-linear least-squares method. The model (1) captured temporal changes in intraluminal pressure, (2) estimated wall stress fields that appeared to reflect the presence or absence of age and disease, and (3) suggested changes in mechanical characteristics of wall micro-constituents despite medical treatment of hypertension. For example, age was positively correlated with residual stresses and altered fibrillar collagen in NT subjects, which indirectly validated the modeling, and HT subjects had higher levels of stresses, increased smooth muscle tone, and a stiffer elastin-dominated matrix despite treatment. These results are consistent with prior reports on effects of age and hypertension, but provide increased insight into evolving contributions of cell and matrix mechanics to arterial behavior in vivo.

  6. Effect of the unfolded protein response on ER protein export: a potential new mechanism to relieve ER stress.

    PubMed

    Shaheen, Alaa

    2018-05-05

    The unfolded protein response (UPR) is an adaptive cellular response that aims to relieve endoplasmic reticulum (ER) stress via several mechanisms, including inhibition of protein synthesis and enhancement of protein folding and degradation. There is a controversy over the effect of the UPR on ER protein export. While some investigators suggested that ER export is inhibited during ER stress, others suggested the opposite. In this article, their conflicting studies are analyzed and compared in attempt to solve this controversy. The UPR appears indeed to enhance ER export, possibly via multiple mechanisms. However, another factor, which is the integrity of the folding machinery/environment inside ER, determines whether ER export will appear increased or decreased during experimentation. Also, different methods of stress induction appear to have different effects on ER export. Thus, improvement of ER export may represent a new mechanism by which the UPR alleviates ER stress. This may help researchers to understand how the UPR works inside cells and how to manipulate it to alter cell fate during stress, either to promote cell survival or death. This may open up new approaches for the treatment of ER stress-related diseases.

  7. Mitochondrial Abnormality Facilitates Cyst Formation in Autosomal Dominant Polycystic Kidney Disease

    PubMed Central

    Ishimoto, Yu; Yoshihara, Daisuke; Kugita, Masanori; Nagao, Shizuko; Shimizu, Akira; Takeda, Norihiko; Wake, Masaki; Honda, Kenjiro; Zhou, Jing

    2017-01-01

    ABSTRACT Autosomal dominant polycystic kidney disease (ADPKD) constitutes the most inherited kidney disease. Mutations in the PKD1 and PKD2 genes, encoding the polycystin 1 and polycystin 2 Ca2+ ion channels, respectively, result in tubular epithelial cell-derived renal cysts. Recent clinical studies demonstrate oxidative stress to be present early in ADPKD. Mitochondria comprise the primary reactive oxygen species source and also their main effector target; however, the pathophysiological role of mitochondria in ADPKD remains uncharacterized. To clarify this function, we examined the mitochondria of cyst-lining cells in ADPKD model mice (Ksp-Cre PKD1flox/flox) and rats (Han:SPRD Cy/+), demonstrating obvious tubular cell morphological abnormalities. Notably, the mitochondrial DNA copy number and peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) expression were decreased in ADPKD model animal kidneys, with PGC-1α expression inversely correlated with oxidative stress levels. Consistent with these findings, human ADPKD cyst-derived cells with heterozygous and homozygous PKD1 mutation exhibited morphological and functional abnormalities, including increased mitochondrial superoxide. Furthermore, PGC-1α expression was suppressed by decreased intracellular Ca2+ levels via calcineurin, p38 mitogen-activated protein kinase (MAPK), and nitric oxide synthase deactivation. Moreover, the mitochondrion-specific antioxidant MitoQuinone (MitoQ) reduced intracellular superoxide and inhibited cyst epithelial cell proliferation through extracellular signal-related kinase/MAPK inactivation. Collectively, these results indicate that mitochondrial abnormalities facilitate cyst formation in ADPKD. PMID:28993480

  8. Lexical stress contrast marking in fluent and non-fluent aphasia in Spanish: The relationship between acoustic cues and compensatory strategies.

    PubMed

    Baqué, Lorraine

    2017-01-01

    This study sought to investigate stress production in Spanish by patients with Broca's (BA) and conduction aphasia (CA) as compared to controls. Our objectives were to assess whether: a) there were many abnormal acoustic correlates of stress as produced by patients, b) these abnormalities had a phonetic component and c) ability for articulatory compensation for stress marking was preserved. The results showed abnormal acoustic values in both BA and CA's productions, affecting not only duration but also F0 and intensity cues, and an interaction effect of stress pattern and duration on intensity cubes in BA, but not in CA or controls. The results are interpreted as deriving from two different underlying phenomena: in BA, a compensatory use of intensity as a stress cue in order to avoid 'equal stress'; in CA, related to either a 'subtle phonetic deficit' involving abnormal stress acoustic cue-processing or to 'clear-speech' effects.

  9. Mechanical-magnetic-electric coupled behaviors for stress-driven Terfenol-D energy harvester

    NASA Astrophysics Data System (ADS)

    Cao, Shuying; Zheng, Jiaju; Wang, Bowen; Pan, Ruzheng; Zhao, Ran; Weng, Ling; Sun, Ying; Liu, Chengcheng

    2017-05-01

    The stress-driven Terfernol-D energy harvester exhibits the nonlinear mechanical-magnetic-electric coupled (MMEC) behaviors and the eddy current effects. To analyze and design the device, it is necessary to establish an accurate model of the device. Based on the effective magnetic field expression, the constitutive equations with eddy currents and variable coefficients, and the dynamic equations, a nonlinear dynamic MMEC model for the device is founded. Comparisons between the measured and calculated results show that the model can describe the nonlinear coupled curves of magnetization versus stress and strain versus stress under different bias fields, and can provide the reasonable data trends of piezomagnetic coefficients, Young's modulus and relative permeability for Terfenol-D. Moreover, the calculated power results show that the model can determine the optimal bias conditions, optimal resistance, suitable proof mass, suitable slices for the maximum energy extraction of the device under broad stress amplitude and broad frequency.

  10. Mechanisms of MDMA (Ecstasy)-Induced Oxidative Stress, Mitochondrial Dysfunction, and Organ Damage

    PubMed Central

    Song, Byoung-Joon; Moon, Kwan-Hoon; Upreti, Vijay V.; Eddington, Natalie D.; Lee, Insong J.

    2010-01-01

    Despite numerous reports about the acute and sub-chronic toxicities caused by MDMA (3,4-methylenedioxymethamphetamine, ecstasy), the underlying mechanism of organ damage is poorly understood. The aim of this review is to present an update of the mechanistic studies on MDMA-mediated organ damage partly caused by increased oxidative/nitrosative stress. Because of the extensive reviews on MDMA-mediated oxidative stress and tissue damage, we specifically focus on the mechanisms and consequences of oxidative-modifications of mitochondrial proteins, leading to mitochondrial dysfunction. We briefly describe a method to systematically identify oxidatively-modified mitochondrial proteins in control and MDMA-exposed rats by using biotin-N-maleimide (biotin-NM) as a sensitive probe for oxidized proteins. We also describe various applications and advantages of this Cys-targeted proteomics method and alternative approaches to overcome potential limitations of this method in studying oxidized proteins from MDMA-exposed tissues. Finally we discuss the mechanism of synergistic drug-interaction between MDMA and other abused substances including alcohol (ethanol) as well as application of this redox-based proteomics method in translational studies for developing effective preventive and therapeutic agents against MDMA-induced organ damage. PMID:20420575

  11. Analysis of differentially expressed genes and adaptive mechanisms of Prunus triloba Lindl. under alkaline stress.

    PubMed

    Liu, Jia; Wang, Yongqing; Li, Qingtian

    2017-01-01

    Prunus triloba Lindl. is a naturally salt-alkaline-tolerant plant with several unique characteristics, and it can be used as the rootstock of Chinese plum ( Prunus salicina Lindl.) in saline-alkaline soils. To comprehensively investigate the alkaline acclimation mechanisms in P. triloba , a series of analyses were conducted under alkaline stress, including analyses of the kinetics of molecular and physiological changes, and leaf microstructure. To understand the kinetics of molecular changes under short-term alkaline stress, we used Illumina HiSeq 2500 platform to identify alkaline stress-related differentially expressed genes (DEGs) in P. triloba . Approximately 53.0 million high-quality clean reads were generated from 59.6 million raw reads, and a total of 124,786 unigenes were obtained after de novo assembly of P. triloba transcriptome data. After alkaline stress treatment, a total of 8948 unigenes were identified as DEGs. Based on these DEGs, a Gene Ontology (GO) enrichment analysis was conducted, suggesting that 28 genes may play an important role in the early alkaline stress response. In addition, analysis of DEGs with the Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed that pathways were significant at different treatment time points. A significant positive correlation was found between the quantitative real-time PCR (qRT-PCR) results and the RNA-Seq data for seven alkaline-related genes, confirming the reliability of the RNA-Seq results. Based on physiological analysis of P. triloba in response to long-term alkaline stress, we found that the internal microstructures of the leaves of P. triloba changed to adapt to long-term alkaline stress. Various physiological indexes indicated that the degree of membrane injury increased with increasing duration of alkaline stress, affecting photosynthesis in P. triloba seedlings. This represents the first investigation into the physiology and transcriptome of P. triloba in response to alkaline stress. The results

  12. Neuroendocrine abnormalities in patients with traumatic brain injury

    NASA Technical Reports Server (NTRS)

    Yuan, X. Q.; Wade, C. E.

    1991-01-01

    . Increased intracranial pressure, which releases vasopressin by altering normal hypothalamic anatomy, may represent a unique type of stress to neuroendocrine systems and may contribute to adrenal secretion by a mechanism that requires intact brainstem function. Endocrine function should be monitored in brain-injured patients with basilar skull fractures and protracted posttraumatic amnesia, and patients with SIADH or DI should be closely monitored for other endocrine abnormalities.

  13. The mechanics of delamination in fiber-reinforced composite materials. Part 1: Stress singularities and solution structure

    NASA Technical Reports Server (NTRS)

    Wang, S. S.; Choi, I.

    1983-01-01

    The fundamental mechanics of delamination in fiber composite laminates is studied. Mathematical formulation of the problem is based on laminate anisotropic elasticity theory and interlaminar fracture mechanics concepts. Stress singularities and complete solution structures associated with general composite delaminations are determined. For a fully open delamination with traction-free surfaces, oscillatory stress singularities always appear, leading to physically inadmissible field solutions. A refined model is introduced by considering a partially closed delamination with crack surfaces in finite-length contact. Stress singularities associated with a partially closed delamination having frictional crack-surface contact are determined, and are found to be diferent from the inverse square-root one of the frictionless-contact case. In the case of a delamination with very small area of crack closure, a simplified model having a square-root stress singularity is employed by taking the limit of the partially closed delamination. The possible presence of logarithmic-type stress singularity is examined; no logarithmic singularity of any kind is found in the composite delamination problem. Numerical examples of dominant stress singularities are shown for delaminations having crack-tip closure with different frictional coefficients between general (1) and (2) graphite-epoxy composites.

  14. Simulation of Weld Mechanical Behavior to Include Welding-Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes

    DTIC Science & Technology

    2015-11-01

    Memorandum Simulation of Weld Mechanical Behavior to Include Welding -Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes... Weld Mechanical Behavior to Include Welding -Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes by Charles R. Fisher...TYPE Technical Report 3. DATES COVERED (From - To) Dec 2013 – July 2015 4. TITLE AND SUBTITLE Simulation of Weld Mechanical Behavior to Include

  15. Simulation of Weld Mechanical Behavior to Include Welding Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes

    DTIC Science & Technology

    2015-11-01

    Memorandum Simulation of Weld Mechanical Behavior to Include Welding -Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes... Weld Mechanical Behavior to Include Welding -Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes by Charles R. Fisher...TYPE Technical Report 3. DATES COVERED (From - To) Dec 2013 – July 2015 4. TITLE AND SUBTITLE Simulation of Weld Mechanical Behavior to Include

  16. Time resolved impedance spectroscopy analysis of lithium phosphorous oxynitride - LiPON layers under mechanical stress

    NASA Astrophysics Data System (ADS)

    Glenneberg, Jens; Bardenhagen, Ingo; Langer, Frederieke; Busse, Matthias; Kun, Robert

    2017-08-01

    In this paper we present investigations on the morphological and electrochemical changes of lithium phosphorous oxynitride (LiPON) under mechanically bent conditions. Therefore, two types of electrochemical cells with LiPON thin films were prepared by physical vapor deposition. First, symmetrical cells with two blocking electrodes (Cu/LiPON/Cu) were fabricated. Second, to simulate a more application-related scenario cells with one blocking and one non-blocking electrode (Cu/LiPON/Li/Cu) were analyzed. In order to investigate mechanical distortion induced transport property changes in LiPON layers the cells were deposited on a flexible polyimide substrate. Morphology of the as-prepared samples and deviations from the initial state after applying external stress by bending the cells over different radii were investigated by Focused Ion Beam- Scanning Electron Microscopy (FIB-SEM) cross-section and surface images. Mechanical stress induced changes in the impedance were evaluated by time-resolved electrochemical impedance spectroscopy (EIS). Due to the formation of a stable, ion-conducting solid electrolyte interphase (SEI), cells with lithium show decreased impedance values. Furthermore, applying mechanical stress to the cells results in a further reduction of the electrolyte resistance. These results are supported by finite element analysis (FEA) simulations.

  17. Mind the gap: glucocorticoids modulate hippocampal glutamate tone underlying individual differences in stress susceptibility.

    PubMed

    Nasca, C; Bigio, B; Zelli, D; Nicoletti, F; McEwen, B S

    2015-06-01

    Why do some individuals succumb to stress and develop debilitating psychiatric disorders, whereas others adapt well in the face of adversity? There is a gap in understanding the neural bases of individual differences in the responses to environmental factors on brain development and functions. Here, using a novel approach for screening an inbred population of laboratory animals, we identified two subpopulations of mice: susceptible mice that show mood-related abnormalities compared with resilient mice, which cope better with stress. This approach combined with molecular and behavioral analyses, led us to recognize, in hippocampus, presynaptic mGlu2 receptors, which inhibit glutamate release, as a stress-sensitive marker of individual differences to stress-induced mood disorders. Indeed, genetic mGlu2 deletion in mice results in a more severe susceptibility to stress, mimicking the susceptible mouse sub-population. Furthermore, we describe an underlying mechanism by which glucocorticoids, acting via mineralocorticoid receptors (MRs), decrease resilience to stress via downregulation of mGlu2 receptors. We also provide a mechanistic link between MRs and an epigenetic control of the glutamatergic synapse that underlies susceptibility to stressful experiences. The approach and the epigenetic allostasis concept introduced here serve as a model for identifying individual differences based upon biomarkers and underlying mechanisms and also provide molecular features that may be useful in translation to human behavior and psychopathology.

  18. Abnormal Transmethylation/Transsulfuration Metabolism and DNA Hypomethylation among Parents of Children with Autism

    ERIC Educational Resources Information Center

    James, S. Jill; Melnyk, Stepan; Jernigan, Stefanie; Hubanks, Amanda; Rose, Shannon; Gaylor, David W.

    2008-01-01

    An integrated metabolic profile reflects the combined influence of genetic, epigenetic, and environmental factors that affect the candidate pathway of interest. Recent evidence suggests that some autistic children may have reduced detoxification capacity and may be under chronic oxidative stress. Based on reports of abnormal methionine and…

  19. Meiotic abnormalities

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    NONE

    1993-12-31

    Chapter 19, describes meiotic abnormalities. These include nondisjunction of autosomes and sex chromosomes, genetic and environmental causes of nondisjunction, misdivision of the centromere, chromosomally abnormal human sperm, male infertility, parental age, and origin of diploid gametes. 57 refs., 2 figs., 1 tab.

  20. Environmental stress induces trinucleotide repeat mutagenesis in human cells

    PubMed Central

    Chatterjee, Nimrat; Lin, Yunfu; Santillan, Beatriz A.; Yotnda, Patricia; Wilson, John H.

    2015-01-01

    The dynamic mutability of microsatellite repeats is implicated in the modification of gene function and disease phenotype. Studies of the enhanced instability of long trinucleotide repeats (TNRs)—the cause of multiple human diseases—have revealed a remarkable complexity of mutagenic mechanisms. Here, we show that cold, heat, hypoxic, and oxidative stresses induce mutagenesis of a long CAG repeat tract in human cells. We show that stress-response factors mediate the stress-induced mutagenesis (SIM) of CAG repeats. We show further that SIM of CAG repeats does not involve mismatch repair, nucleotide excision repair, or transcription, processes that are known to promote TNR mutagenesis in other pathways of instability. Instead, we find that these stresses stimulate DNA rereplication, increasing the proportion of cells with >4 C-value (C) DNA content. Knockdown of the replication origin-licensing factor CDT1 eliminates both stress-induced rereplication and CAG repeat mutagenesis. In addition, direct induction of rereplication in the absence of stress also increases the proportion of cells with >4C DNA content and promotes repeat mutagenesis. Thus, environmental stress triggers a unique pathway for TNR mutagenesis that likely is mediated by DNA rereplication. This pathway may impact normal cells as they encounter stresses in their environment or during development or abnormal cells as they evolve metastatic potential. PMID:25775519

  1. Understanding the mechanisms of lipid extraction from microalga Chlamydomonas reinhardtii after electrical field solicitations and mechanical stress within a microfluidic device.

    PubMed

    Bensalem, Sakina; Lopes, Filipa; Bodénès, Pierre; Pareau, Dominique; Français, Olivier; Le Pioufle, Bruno

    2018-06-01

    One way envisioned to overcome part of the issues biodiesel production encounters today is to develop a simple, economically viable and eco-friendly process for the extraction of lipids from microalgae. This study investigates the lipid extraction efficiency from the microalga Chlamydomonas reinhardtii as well as the underlying mechanisms. We propose a new methodology combining a pulsed electric field (PEF) application and mechanical stresses as a pretreatment to improve lipid extraction with solvents. Cells enriched in lipids are therefore submitted to electric field pulses creating pores on the cell membrane and then subjected to a mechanical stress by applying cyclic pressures on the cell wall (using a microfluidic device). Results showed an increase in lipid extraction when cells were pretreated by the combination of both methods. Microscopic observations showed that both pretreatments affect the cell structure. Finally, the dependency of solvent lipid extraction efficiency with the cell wall structure is discussed. Copyright © 2018 Elsevier Ltd. All rights reserved.

  2. Heat stress responses in spermatozoa: Mechanisms and consequences for cattle fertility.

    PubMed

    Rahman, Mohammad Bozlur; Schellander, Karl; Luceño, Núria Llamas; Van Soom, Ann

    2018-06-01

    Currently, the world is facing the negative impact of global warming on all living beings. Adverse effects of global warming are also becoming obvious in dairy cattle breeding. In dairy bulls, low fertility has frequently been reported during summer season especially in tropical or subtropical conditions. Typically, spermatozoa at post-meiotic stages of development are more susceptible to heat stress. During this period extensive incorporation of histone modifications and hyperacetylation turns the chromatin into an unstable conformation. These unstable forms of chromatin are thought to be more vulnerable to heat stress, which may have an effect on chromatin condensation of spermatozoa. Spermatozoa with altered chromatin condensation perturb the dynamics of DNA methylation reprogramming in the paternal pronucleus resulting in disordered active DNA demethylation followed by de novo methylation patterns. In addition, there was a tendency of decreased size in both paternal and maternal pronuclei after fertilization of oocytes with heat-stressed spermatozoa, leading to lower fertilization rates. In this review, we will focus on the mechanisms of heat stress-induced sperm defects and provide more detailed insights into sperm-borne epigenetic regulations. Copyright © 2018 Elsevier Inc. All rights reserved.

  3. Mechanisms of Sex Differences in Fear and Posttraumatic Stress Disorder.

    PubMed

    Ramikie, Teniel Sonya; Ressler, Kerry J

    2018-05-15

    Following sexual maturity, females disproportionately have higher rates of posttraumatic stress disorder (PTSD) and experience greater symptom severity and chronicity as compared with males. This observation has led many to examine sex differences in PTSD risk factors. Though relatively few, these studies reveal that the root causes of PTSD sex differences are complex, and partly represent interactions between sex-specific nonbiological and biological risk factors, which differentially shape PTSD vulnerability. Moreover, these studies suggest that sex-specific PTSD vulnerability is partly regulated by sex differences in fear systems. Fear, which represents a highly conserved adaptive response to threatening environmental stimuli, becomes pathological in trauma- and stress-based psychiatric syndromes, such as PTSD. Over the last 30 years, considerable progress has been made in understanding normal and pathological molecular and behavioral fear processes in humans and animal models. Thus, fear mechanisms represent a tractable PTSD biomarker in the study of sex differences in fear. In this review, we discuss studies that examine nonbiological and biological sex differences that contribute to normal and pathological fear behaviors in humans and animal models. This, we hope, will shed greater light on the potential mechanisms that contribute to increased PTSD vulnerability in females. Copyright © 2017 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  4. The Challenge of Aviation Emergency and Abnormal Situations

    NASA Technical Reports Server (NTRS)

    Burian, Barbara K.; Barshi, Immanuel; Dismukes, Key

    2005-01-01

    Emergency and abnormal situations occur on flights everyday around the world. They range from minor situations readily managed to extremely serious and highly time-critical situations that deeply challenge the skills of even the most effective crews. How well crews respond to these situations is a function of several interacting sets of issues: (1) the design of non-normal procedures and checklists, (2) design of aircraft systems and automation, (3) specific aspects of the non-normal situation, such as time criticality and complexity of the situation, (4) human performance capabilities and cognitive limitations under high workload and stress, (5) design of training for non-normal situations, (6) philosophies, policies and practices within the industry, and (7) economic and regulatory constraints. Researchers and pilots working on NASA's Emergency and Abnormal Situations project are addressing these issues in a long-range study. In this paper we discuss these issues and illustrate them with examples from recent incidents and accidents.

  5. Central neuropeptide Y plays an important role in mediating the adaptation mechanism against chronic stress in male rats.

    PubMed

    Yang, Yu; Babygirija, Reji; Zheng, Jun; Shi, Bei; Sun, Weinan; Zheng, Xiaojiao; Zhang, Fan; Cao, Yu

    2018-02-07

    Exposure to continuous life stress often causes gastrointestinal (GI) symptoms. Studies have shown that neuropeptide Y (NPY) counteracts the biological actions of corticotrophin-releasing factor (CRF), and is involved in the termination of the stress response. However, in chronic repeated restraint stress (CRS) conditions, the actions of NPY on GI motility remain controversial. To evaluate the role of NPY in mediation of the adaptation mechanism and GI motility in CRS conditions, a CRS rat model was set up. Central CRF and NPY expression levels were analyzed, serum corticosterone and NPY concentrations were measured, and GI motor function was evaluated. The NPY Y1 receptor antagonist BIBP-3226 was centrally administered before stress loading, and on days, 1-5, of repeated stress, the central CRF and the serum corticosterone concentrations were measured. In addition, gastric and colonic motor functions were evaluated. The elevated central CRF expression and corticosterone concentration caused by acute stress began to fall after 3 days of stress loading, while central NPY expression and serum NPY began to increase. GI dysmotility also returned to a normal level. Pretreatment with BIBP-3226 abolished the adaptation mechanism, and significantly increased CRF expression and the corticosterone concentration, which resulted in delayed gastric emptying and accelerated fecal pellet output. Inhibited gastric motility and enhanced distal colonic motility were also recorded. CRS-produced adaptation, over-expressed central CRF, and GI dysmotility observed in acute restraint stress were restored to normal levels. Central NPY via the Y1 receptor plays an important role in mediating the adaptation mechanism against chronic stress. Copyright © 2018 Endocrine Society.

  6. Acoustic and Electrical Signal Emission recordings when marble specimens are subjected to compressional mechanical stress

    NASA Astrophysics Data System (ADS)

    Triantis, Dimos; Stavrakas, Ilias; Hloupis, George; Ninos, Konstantinos; Vallianatos, Filippos

    2013-04-01

    The detection of Acoustic Emissions (AE) and Electrical Signals (ES) has been proved as a valuable experimental method to characterize the mechanical status of marble specimens when subjected to mechanical stress. In this work, marble specimens with dimensions 10cm x 4cm x 4cm where subjected to sequential loading cycles. The maximum stress of each loading was near the vicinity of fracture and was maintained for a relatively long time (th=200s). Concurrently to the mechanical tests, AE and ES were recorded. Specifically, two AE sensors and five ES sensors were installed on the surface of the specimens and the detected emissions were stored on a PC. The recordings show that AE and ES provide information regarding the damage spreading and location in the bulk of the specimen. Specifically, when the mechanical stress was maintained constant at the high stress value during each loading cycle the cumulative number of the AE hits become gradually less reaching a minimum after the first three loading cycles, indicating the existence of the Kaiser effect. During the eighth loading cycle the AE hits show a significant increase that became maximum at the ninth cycle before where failure occured. A similar behavior was observed for the cumulative energy. A b-value analysis was conducted following both Aki's and Gutenberg-Richter relations on the amplitudes of the AE hits. The b-values were found to increase during the three first loading cycles while consequently they were practically constant until reaching the two final loading cycles where they became gradually lower. The ES significantly increases during the stress increase of each cycle and gradually restores at a background level when the applied stress is maintained constant near the vicinity of fracture. It was observed that the background restoration level becomes gradually higher during the first four loading cycles. Consequently, during the next three loading cycles the background level is maintained practically

  7. Changes in permeability caused by transient stresses: field observations, experiments, and mechanisms

    USGS Publications Warehouse

    Manga, Michael; Beresnev, Igor; Brodsky, Emily E.; Elkhoury, Jean E.; Elsworth, Derek; Ingebritsen, Steve E.; Mays, David C.; Wang, Chi-Yuen

    2012-01-01

    Oscillations in stress, such as those created by earthquakes, can increase permeability and fluid mobility in geologic media. In natural systems, strain amplitudes as small as 10–6 can increase discharge in streams and springs, change the water level in wells, and enhance production from petroleum reservoirs. Enhanced permeability typically recovers to prestimulated values over a period of months to years. Mechanisms that can change permeability at such small stresses include unblocking pores, either by breaking up permeability-limiting colloidal deposits or by mobilizing droplets and bubbles trapped in pores by capillary forces. The recovery time over which permeability returns to the prestimulated value is governed by the time to reblock pores, or for geochemical processes to seal pores. Monitoring permeability in geothermal systems where there is abundant seismicity, and the response of flow to local and regional earthquakes, would help test some of the proposed mechanisms and identify controls on permeability and its evolution.

  8. On the effects of thermal history on the development and relaxation of thermo-mechanical stress in cryopreservation

    NASA Astrophysics Data System (ADS)

    Eisenberg, David P.; Steif, Paul S.; Rabin, Yoed

    2014-11-01

    This study investigates the effects of the thermal protocol on the development and relaxation of thermo-mechanical stress in cryopreservation by means of glass formation, also known as vitrification. The cryopreserved medium is modeled as a homogeneous viscoelastic domain, constrained within either a stiff cylindrical container or a highly compliant bag. Annealing effects during the cooling phase of the cryopreservation protocol are analyzed. Results demonstrate that an intermediate temperature-hold period can significantly reduce the maximum tensile stress, thereby decreasing the potential for structural damage. It is also demonstrated that annealing at temperatures close to glass transition significantly weakens the dependency of thermo-mechanical stress on the cooling rate. Furthermore, a slower initial rewarming rate after cryogenic storage may drastically reduce the maximum tensile stress in the material, which supports previous experimental observations on the likelihood of fracture at this stage. This study discusses the dependency of the various stress components on the storage temperature. Finally, it is demonstrated that the stiffness of the container wall can affect the location of maximum stress, with implications on the development of cryopreservation protocols.

  9. Abnormal branching and regression of the notochord and its relationship to foregut abnormalities.

    PubMed

    Vleesch Dubois, V N; Quan Qi, B; Beasley, S W; Williams, A

    2002-04-01

    An abnormally positioned notochord has been reported in embryos that develop foregut abnormalities, vertebral defects and other abnormalities of the VATER association. This study examines the patterns of regression of the abnormal notochord in the rat model of the VATER association and investigates the relationship between developmental abnormalities of the notochord and those of the vertebra and foregut. Timed-pregnant Sprague-Dawley rats were given daily intraperitoneal injections of 1.75 mg/kg adriamycin on gestational days 6 - 9 inclusive. Rats were sacrificed between days 14 and 20 and their embryos harvested, histologically sectioned and stained and examined serially. The location and appearance of the degenerating notochord and its relationship to regional structural defects were analysed. All 26 embryos exposed to adriamycin developed foregut abnormalities and had an abnormal notochord. The notochord disappeared by a process of apoptotic degeneration that lagged behind that of the normal embryo: the notochord persisted in the abnormal embryo beyond day 17, whereas in the normal rat it had already disappeared. Similarly, formation of the nucleus pulposus was delayed. Vertebral abnormalities occurred when the notochord was ventrally-positioned. The notochord disappears during day 16 in the normal embryo whereas abnormal branches of the notochord persist until day 19 in the adriamycin-treated embryo. Degeneration of the notochord is dominated by apoptosis. An excessively ventrally-placed notochord is closely associated with abnormalities of the vertebral column, especially hemivertebrae.

  10. Mechanical Properties of Gels; Stress from Confined Fluids

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    George W. Scherer

    2009-12-01

    Abstract for Grant DE-FG02-97ER45642 Period: 1997-2002 Mechanical Properties of Gels 2002-2008 Stress from Confined Fluids Principal investigator: Prof. George W. Scherer Dept. Civil & Env. Eng./PRISM Eng. Quad. E-319 Princeton, NJ 08544 USA Recipient organization: Trustees of Princeton University 4 New South Princeton, NJ 08544 USA Abstract: The initial stage of this project, entitled Mechanical Properties of Gels, was dedicated to characterizing and explaining the properties of inorganic gels. Such materials, made by sol-gel processing, are of interest for fabrication of films, fibers, optical devices, advanced insulation and other uses. However, their poor mechanical properties are an impediment in somemore » applications, so understanding the origin of these properties could lead to enhanced performance. Novel experimental methods were developed and applied to measure the stiffness and permeability of gels and aerogels. Numerical simulations were developed to reproduce the growth process of the gels, resulting in structures whose mechanical properties matched the measurements. The models showed that the gels are formed by the growth of relatively robust clusters of molecules that are joined by tenuous links whose compliance compromises the stiffness of the structure. Therefore, synthetic methods that enhance the links could significantly increase the rigidity of such gels. The next stage of the project focused on Stress from Confined Fluids. The first problem of interest was the enhanced thermal expansion coefficient of water that we measured in the nanometric pores of cement paste. This could have a deleterious effect on the resistance of concrete to rapid heating in fires, because the excessive thermal expansion of water in the pores of the concrete could lead to spalling and collapse. A series of experiments demonstrated that the expansion of water increases as the pore size decreases. To explain this behavior, we undertook a collaboration with Prof

  11. Molecular Mechanisms of External Genitalia Development

    PubMed Central

    Blaschko, Sarah D.; Cunha, Gerald R.; Baskin, Laurence S.

    2012-01-01

    External genitalia development occurs through a combination of hormone independent, hormone dependent, and endocrine pathways. Perturbation of these pathways can lead to abnormal external genitalia development. We review human and animal mechanisms of normal and abnormal external genitalia development, and we evaluate abnormal mechanisms that lead to hypospadias. We also discuss recent laboratory findings that further our understanding of animal models of hypospadias. PMID:22790208

  12. Local stresses in metal matrix composites subjected to thermal and mechanical loading

    NASA Technical Reports Server (NTRS)

    Highsmith, Alton L.; Shin, Donghee; Naik, Rajiv A.

    1990-01-01

    An elasticity solution has been used to analyze matrix stresses near the fiber/matrix interface in continuous fiber-reinforced metal-matrix composites, modeling the micromechanics in question in terms of a cylindrical fiber and cylindrical matrix sheath which is embedded in an orthotropic medium representing the composite. The model's predictions for lamina thermal and mechanical properties are applied to a laminate analysis determining ply-level stresses due to thermomechanical loading. A comparison is made between these results, which assume cylindrical symmetry, and the predictions yielded by a FEM model in which the fibers are arranged in a square array.

  13. The short-term stress response - Mother nature's mechanism for enhancing protection and performance under conditions of threat, challenge, and opportunity.

    PubMed

    Dhabhar, Firdaus S

    2018-03-26

    Our group has proposed that in contrast to chronic stress that can have harmful effects, the short-term (fight-or-flight) stress response (lasting for minutes to hours) is nature's fundamental survival mechanism that enhances protection and performance under conditions involving threat/challenge/opportunity. Short-term stress enhances innate/primary, adaptive/secondary, vaccine-induced, and anti-tumor immune responses, and post-surgical recovery. Mechanisms and mediators include stress hormones, dendritic cell, neutrophil, macrophage, and lymphocyte trafficking/function and local/systemic chemokine and cytokine production. Short-term stress may also enhance mental/cognitive and physical performance through effects on brain, musculo-skeletal, and cardiovascular function, reappraisal of threat/anxiety, and training-induced stress-optimization. Therefore, short-term stress psychology/physiology could be harnessed to enhance immuno-protection, as well as mental and physical performance. This review aims to provide a conceptual framework and targets for further investigation of mechanisms and conditions under which the protective/adaptive aspects of short-term stress/exercise can be optimized/harnessed, and for developing pharmacological/biobehavioral interventions to enhance health/healing, and mental/cognitive/physical performance. Copyright © 2018 Elsevier Inc. All rights reserved.

  14. Fractured rock stress-permeability relationships from in situ data and effects of temperature and chemical-mechanical couplings

    DOE PAGES

    Rutqvist, J.

    2014-09-19

    The purpose of this paper is to (i) review field data on stress-induced permeability changes in fractured rock; (ii) describe estimation of fractured rock stress-permeability relationships through model calibration against such field data; and (iii) discuss observations of temperature and chemically mediated fracture closure and its effect on fractured rock permeability. The field data that are reviewed include in situ block experiments, excavation-induced changes in permeability around tunnels, borehole injection experiments, depth (and stress) dependent permeability, and permeability changes associated with a large-scale rock-mass heating experiment. Data show how the stress-permeability relationship of fractured rock very much depends on localmore » in situ conditions, such as fracture shear offset and fracture infilling by mineral precipitation. Field and laboratory experiments involving temperature have shown significant temperature-driven fracture closure even under constant stress. Such temperature-driven fracture closure has been described as thermal overclosure and relates to better fitting of opposing fracture surfaces at high temperatures, or is attributed to chemically mediated fracture closure related to pressure solution (and compaction) of stressed fracture surface asperities. Back-calculated stress-permeability relationships from field data may implicitly account for such effects, but the relative contribution of purely thermal-mechanical and chemically mediated changes is difficult to isolate. Therefore, it is concluded that further laboratory and in situ experiments are needed to increase the knowledge of the true mechanisms behind thermally driven fracture closure, and to further assess the importance of chemical-mechanical coupling for the long-term evolution of fractured rock permeability.« less

  15. Fractured rock stress-permeability relationships from in situ data and effects of temperature and chemical-mechanical couplings

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rutqvist, J.

    The purpose of this paper is to (i) review field data on stress-induced permeability changes in fractured rock; (ii) describe estimation of fractured rock stress-permeability relationships through model calibration against such field data; and (iii) discuss observations of temperature and chemically mediated fracture closure and its effect on fractured rock permeability. The field data that are reviewed include in situ block experiments, excavation-induced changes in permeability around tunnels, borehole injection experiments, depth (and stress) dependent permeability, and permeability changes associated with a large-scale rock-mass heating experiment. Data show how the stress-permeability relationship of fractured rock very much depends on localmore » in situ conditions, such as fracture shear offset and fracture infilling by mineral precipitation. Field and laboratory experiments involving temperature have shown significant temperature-driven fracture closure even under constant stress. Such temperature-driven fracture closure has been described as thermal overclosure and relates to better fitting of opposing fracture surfaces at high temperatures, or is attributed to chemically mediated fracture closure related to pressure solution (and compaction) of stressed fracture surface asperities. Back-calculated stress-permeability relationships from field data may implicitly account for such effects, but the relative contribution of purely thermal-mechanical and chemically mediated changes is difficult to isolate. Therefore, it is concluded that further laboratory and in situ experiments are needed to increase the knowledge of the true mechanisms behind thermally driven fracture closure, and to further assess the importance of chemical-mechanical coupling for the long-term evolution of fractured rock permeability.« less

  16. Chromosomal abnormalities, meiotic behavior and fertility in domestic animals.

    PubMed

    Villagómez, D A F; Pinton, A

    2008-01-01

    Since the advent of the surface microspreading technique for synaptonemal complex analysis, increasing interest in describing the synapsis patterns of chromosome abnormalities associated with fertility of domestic animals has been noticed during the past three decades. In spite of the number of scientific reports describing the occurrence of structural chromosome abnormalities, their meiotic behavior and gametic products, little is known in domestic animal species about the functional effects of such chromosome aberrations in the germ cell line of carriers. However, some interesting facts gained from recent and previous studies on the meiotic behavior of chromosome abnormalities of domestic animals permit us to discuss, in the frame of recent knowledge emerging from mouse and human investigations, the possible mechanism implicated in the well known association between meiotic disruption and chromosome pairing failure. New cytogenetic techniques, based on molecular and immunofluorescent analyses, are allowing a better description of meiotic processes, including gamete production. The present communication reviews the knowledge of the meiotic consequences of chromosome abnormalities in domestic animals. Copyright 2008 S. Karger AG, Basel.

  17. DNA Damage and Repair: Relevance to Mechanisms of Neurodegeneration

    PubMed Central

    Martin, Lee J.

    2008-01-01

    DNA damage is a form of cell stress and injury that has been implicated in the pathogenesis of many neurologic disorders, including amyotrophic lateral sclerosis, Alzheimer disease, Down syndrome, Parkinson disease, cerebral ischemia, and head trauma. However, most data reveal only associations, and the role for DNA damage in direct mechanisms of neurodegeneration is vague with respect to being a definitive upstream cause of neuron cell death, rather than a consequence of the degeneration. Although neurons seem inclined to develop DNA damage during oxidative stress, most of the existing work on DNA damage and repair mechanisms has been done in the context of cancer biology using cycling non-neuronal cells but not nondividing (i.e. postmitotic) neurons. Nevertheless, the identification of mutations in genes that encode proteins that function in DNA repair and DNA damage response in human hereditary DNA repair deficiency syndromes and ataxic disorders is establishing a mechanistic precedent that clearly links DNA damage and DNA repair abnormalities with progressive neurodegeneration. This review summarizes DNA damage and repair mechanisms and their potential relevance to the evolution of degeneration in postmitotic neurons. PMID:18431258

  18. [Effect of occupational stress on cardiovascular function of different vocational population].

    PubMed

    Yao, San-qiao; Fan, Xue-yun; Jin, Yu-lan; Bai, Yu-ping; Qu, Yin-e; Zhou, Yuan

    2003-02-01

    To study the effect of occupational stress on cardiovascular function of different vocational population. The occupational stressors, risk factors of cardiovascular diseases were investigated by questionnaire in 839 people with 4 kinds of jobs. Blood pressure, sugar, and lipid were detected at the same time. Blood pressure were higher in the groups of old age, long standing and teachers, and the abnormal rate of blood pressure was 21.69%. There was no difference in abnormal ECG among ages, standing and occupation, and the abnormal rate of ECG was 19.07%. Job control, job demands, job responsibility, role in a job and shift work were the main stress factors affecting systolic and diastolic blood pressure. More conflict in job, less chance of participation, severe job loads were the risk factors of primary hypertension. Accident due to job responsibility, job responsibility, role in a job were the main risk factors of abnormal electrocardiograph. Self-respect and activity beyond work were the good modifiers of heart function. Occupational stress has certain effect on cardiovascular function.

  19. Redox stress in geobacilli from geothermal springs: Phenomenon and membrane-associated response mechanisms.

    PubMed

    Ghazaryan, Astghik; Blbulyan, Syuzanna; Poladyan, Anna; Trchounian, Armen

    2015-10-01

    Geobacillus toebii ArzA-8, from Armenian geothermal springs, grew well in nutrient broth. During its growth, changes in pH in opposite directions were observed depending on glucose supplementation. Accordingly, the decrease in the redox potential was determined using titanium-silicate (Eh) and platinum (Eh') electrodes: Eh decreased to -150 ± 3 mV and Eh' to -350 ± 2 mV without glucose; the decrease in these potentials was smaller with glucose. Redox stress due to an oxidizer, K3[Fe(CN)6], or a reducer, dl-dithiothreitol (DTT), inhibited bacterial growth. However, a stimulatory effect of K3[Fe(CN)6] or DTT was observed with or without glucose, respectively. With glucose, the H(+) efflux was sensitive to N,N'-dicyclohexylcarbodiimide (DCCD), an inhibitor of FoF1FOF1-ATPase and other H(+) translocation mechanisms, but the addition of an oxidizer or reducer suppressed the H(+) efflux. The ATPase activity of membrane vesicles was ~1.3-fold higher in cells grown with glucose compared with cells grown without glucose. DCCD and DTT suppressed ATPase activity in cells grown without glucose, whereas DTT stimulated FOF1-ATPase activity in cells grown with glucose. Thus, G. toebii senses redox stress; this thermophile likely presents specific membrane-associated response mechanisms involving FOF1-ATPase to overcome redox stress and survive; these mechanisms are important for adaptation to extreme environments. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Fracture mechanics correlation of boron/aluminum coupons containing stress risers

    NASA Technical Reports Server (NTRS)

    Adsit, N. R.; Waszczak, J. P.

    1975-01-01

    The mechanical behavior of boron/aluminum near stress risers has been studied and reported. This effort was directed toward defining the tensile behavior of both unidirectional and (0/ plus or minus 45) boron/aluminum using linear elastic fracture mechanics (LEFM). The material used was 5.6-mil boron in 6061 aluminum, consolidated using conventional diffusion bonding techniques. Mechanical properties are reported for both unidirectional and (0/ plus or minus 45) boron/aluminum, which serve as control data for the fracture mechanics predictions. Three different flawed specimen types were studied. In each case the series of specimens remained geometrically similar to eliminate variations in finite size correction factors. The fracture data from these tests were reduced using two techniques. They both used conventional LEFM methods, but the existence of a characteristic flaw was assumed in one case and not the other. Both the data and the physical behavior of the specimens support the characteristic flaw hypothesis. Cracks were observed growing slowly in the (0/ plus or minus 45) laminates, until a critical crack length was reached at which time catastrophic failure occurred.

  1. Interpreting plant responses to clinostating. I - Mechanical stresses and ethylene

    NASA Technical Reports Server (NTRS)

    Salisbury, Frank B.; Wheeler, Raymond M.

    1981-01-01

    The possibility that the clinostat mechanical stresses (leaf flopping) induces ethylene production and, thus, the development of epinasty was tested by stressing vertical plants by constant gentle horizontal or vertical shaking or by a quick back-and-forth rotation (twisting). Clinostat leaf flopping was closely approximated by turning plants so that their stems were horizontal, rotating them quickly about the stem axis, and returning them to the vertical, with the treatment repeated every four minutes. It was found that horizontal and vertical shaking, twisting, intermittent horizontal rotating, and gentle hand shaking failed to induce epinasties that approached those observed on the slow clinostat. Minor epinasties were generated by vigorous hand-shaking (120 sec/day) and by daily application of Ag(+). Reducing leaf displacements by inverting plants did not significantly reduce the minor epinasty generated by vigorous hand-shaking.

  2. Hypoxia/oxidative stress alters the pharmacokinetics of CPU86017-RS through mitochondrial dysfunction and NADPH oxidase activation.

    PubMed

    Gao, Jie; Ding, Xuan-sheng; Zhang, Yu-mao; Dai, De-zai; Liu, Mei; Zhang, Can; Dai, Yin

    2013-12-01

    Hypoxia/oxidative stress can alter the pharmacokinetics (PK) of CPU86017-RS, a novel antiarrhythmic agent. The aim of this study was to investigate the mechanisms underlying the alteration of PK of CPU86017-RS by hypoxia/oxidative stress. Male SD rats exposed to normal or intermittent hypoxia (10% O2) were administered CPU86017-RS (20, 40 or 80 mg/kg, ig) for 8 consecutive days. The PK parameters of CPU86017-RS were examined on d 8. In a separate set of experiments, female SD rats were injected with isoproterenol (ISO) for 5 consecutive days to induce a stress-related status, then CPU86017-RS (80 mg/kg, ig) was administered, and the tissue distributions were examined. The levels of Mn-SOD (manganese containing superoxide dismutase), endoplasmic reticulum (ER) stress sensor proteins (ATF-6, activating transcription factor 6 and PERK, PRK-like ER kinase) and activation of NADPH oxidase (NOX) were detected with Western blotting. Rat liver microsomes were incubated under N2 for in vitro study. The Cmax, t1/2, MRT (mean residence time) and AUC (area under the curve) of CPU86017-RS were significantly increased in the hypoxic rats receiving the 3 different doses of CPU86017-RS. The hypoxia-induced alteration of PK was associated with significantly reduced Mn-SOD level, and increased ATF-6, PERK and NOX levels. In ISO-treated rats, the distributions of CPU86017-RS in plasma, heart, kidney, and liver were markedly increased, and NOX levels in heart, kidney, and liver were significantly upregulated. Co-administration of the NOX blocker apocynin eliminated the abnormalities in the PK and tissue distributions of CPU86017-RS induced by hypoxia/oxidative stress. The metabolism of CPU86017-RS in the N2-treated liver microsomes was significantly reduced, addition of N-acetylcysteine (NAC), but not vitamin C, effectively reversed this change. The altered PK and metabolism of CPU86017-RS induced by hypoxia/oxidative stress are produced by mitochondrial abnormalities, NOX activation

  3. Sensorimotor integration and psychopathology: motor control abnormalities related to psychiatric disorders.

    PubMed

    Velasques, Bruna; Machado, Sergio; Paes, Flávia; Cunha, Marlo; Sanfim, Antonio; Budde, Henning; Cagy, Mauricio; Anghinah, Renato; Basile, Luis F; Piedade, Roberto; Ribeiro, Pedro

    2011-12-01

    Recent evidence is reviewed to examine relationships among sensorimotor and cognitive aspects in some important psychiatry disorders. This study reviews the theoretical models in the context of sensorimotor integration and the abnormalities reported in the most common psychiatric disorders, such as Alzheimer's disease, autism spectrum disorder and squizophrenia. The bibliographical search used Pubmed/Medline, ISI Web of Knowledge, Cochrane data base and Scielo databases. The terms chosen for the search were: Alzheimer's disease, AD, autism spectrum disorder, and Squizophrenia in combination with sensorimotor integration. Fifty articles published in English and were selected conducted from 1989 up to 2010. We found that the sensorimotor integration process plays a relevant role in elementary mechanisms involved in occurrence of abnormalities in most common psychiatric disorders, participating in the acquisition of abilities that have as critical factor the coupling of different sensory data which will constitute the basis of elaboration of consciously goal-directed motor outputs. Whether these disorders are associated with an abnormal peripheral sensory input or defective central processing is still unclear, but some studies support a central mechanism. Sensorimotor integration seems to play a significant role in the disturbances of motor control, like deficits in the feedforward mechanism, typically seen in AD, autistic and squizophrenic patients.

  4. CHBPR: ENDOPLASMIC RETICULUM STRESS CONTRIBUTES TO AORTIC STIFFENING VIA PRO-APOPTOTIC AND FIBROTIC SIGNALING MECHANISMS

    PubMed Central

    Spitler, Kathryn M.; Webb, R. Clinton

    2014-01-01

    Vascular smooth muscle cell (VSMC) apoptosis and collagen synthesis contributes to aortic stiffening. A cellular signaling mechanism contributing to apoptotic and fibrotic events is endoplasmic reticulum (ER) stress. In this study we tested the hypothesis that induction of ER stress in a normotensive rat would cause pro-fibrotic and apoptotic signaling contributing to aortic stiffening. Furthermore, we hypothesized that inhibition of ER stress in an angiotensin II (Ang II) model of hypertension would improve aortic stiffening. Induction of ER stress with tunicamycin (TM) in normotensive Sprague Dawley rats (SD, 10 µg/kg/day, osmotic pump, 28 days) caused an increase in systolic blood pressure (mmHg; 160 ± 5) compared to vehicle-treated (127 ± 3) or TM-treated rats that were co-treated with ER stress inhibitor 4-phenylbutyic acid (PBA, 100 mg/kg/day, 28 days, (124 ± 6)). There was an increase in aortic apoptosis (fold; 3.0±0.3), collagen content (1.4±0.1) and fibrosis (2.0±0.1) in the TM-treated rats compared to vehicle-treated rats. Inhibition of ER stress in male SD rats given Ang II (60 ng/min, osmotic pump, 28 days) and treated with either tauroursodeoxycholic acid (TUDCA) or PBA (100 mg/kg/day, i.p., 28 days) led to a 20 mmHg decrease in blood pressure with either inhibitor, compared to Ang II treatment alone. Aortic apoptosis, increased collagen content and fibrosis in Ang II-treated rats were attenuated with ER stress inhibition. We conclude that ER stress is a new signaling mechanism contributing to aortic stiffening via promoting apoptosis and fibrosis. PMID:24379182

  5. Mechanical stress contributes to the expression of the STM homeobox gene in Arabidopsis shoot meristems

    PubMed Central

    Landrein, Benoît; Kiss, Annamaria; Sassi, Massimiliano; Chauvet, Aurélie; Das, Pradeep; Cortizo, Millan; Laufs, Patrick; Takeda, Seiji; Aida, Mitsuhiro; Traas, Jan; Vernoux, Teva; Boudaoud, Arezki; Hamant, Olivier

    2015-01-01

    The role of mechanical signals in cell identity determination remains poorly explored in tissues. Furthermore, because mechanical stress is widespread, mechanical signals are difficult to uncouple from biochemical-based transduction pathways. Here we focus on the homeobox gene SHOOT MERISTEMLESS (STM), a master regulator and marker of meristematic identity in Arabidopsis. We found that STM expression is quantitatively correlated to curvature in the saddle-shaped boundary domain of the shoot apical meristem. As tissue folding reflects the presence of mechanical stress, we test and demonstrate that STM expression is induced after micromechanical perturbations. We also show that STM expression in the boundary domain is required for organ separation. While STM expression correlates with auxin depletion in this domain, auxin distribution and STM expression can also be uncoupled. STM expression and boundary identity are thus strengthened through a synergy between auxin depletion and an auxin-independent mechanotransduction pathway at the shoot apical meristem. DOI: http://dx.doi.org/10.7554/eLife.07811.001 PMID:26623515

  6. Bone stress: a radionuclide imaging perspective. [/sup 99m/Tc-pyrophosphate

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Roub, L.W.; Gumerman, L.W.; Hanley, E.N. Jr.

    Thirty-five college athletes with lower leg pain underwent radiography and radionuclide studies to rule out a stress fracture. Their asymptomatic extremities and 13 pain-free athletes served as controls. Four main patterns were observed: (a) sharply marginated scintigraphic abnormalities and positive radiographs; (b) sharply marginated scintigraphic abnormalities and negatives radiographs; (c) ill-defined scintigraphic abnormalities and negative radiographs; and (d) negative radionuclide images and negative radiographs. Since the patients with the first two patterns were otherwise identical medically, the authors feel that this scintigraphic appearance is characterisic of bone stress in the appropriate clinical setting, regardless of the radiographic findings. A schemamore » is proposed to explain the occurrence of positive radionuclide images and negative radiographs in the same patient, using a broad conceptual approach to the problem of bone stress.« less

  7. Ulcerative Dermatitis in C57BL/6 Mice Exhibits an Oxidative Stress Response Consistent with Normal Wound Healing

    PubMed Central

    Williams, Lisa K; Csaki, Lauren S; Cantor, Rita M; Reue, Karen; Lawson, Greg W

    2012-01-01

    Ulcerative dermatitis (UD) is a common syndrome of unknown etiology that results in profound morbidity in C57BL/6 mice and lines on a C57BL/6 background. The lesions are due to severe pruritus-induced self-trauma, progressing from superficial excoriations to deep ulcerations. UD may be behavioral in origin, with ulcerative lesions resulting from self-mutilating behavior in response to unresolved inflammation or compulsion. Alternatively, abnormal oxidative damage may be a mechanism underlying UD. To evaluate whether UD behaves similarly to normal wounds, consistent with a secondary self-inflicted lesion, or is a distinct disorder with abnormal wound response, we evaluated expression levels of genes representing various arms of the oxidative stress response pathway UD-affected and unwounded C57BL/6J mice. No evidence indicated that UD wounds have a defect in the oxidative stress response. Our findings are consistent with an understanding of C57BL/6 UD lesions as typical rather than atypical wounds. PMID:22776048

  8. Impaired Functional Connectivity in the Prefrontal Cortex: A Mechanism for Chronic Stress-Induced Neuropsychiatric Disorders

    PubMed Central

    Negrón-Oyarzo, Ignacio; Aboitiz, Francisco; Fuentealba, Pablo

    2016-01-01

    Chronic stress-related psychiatric diseases, such as major depression, posttraumatic stress disorder, and schizophrenia, are characterized by a maladaptive organization of behavioral responses that strongly affect the well-being of patients. Current evidence suggests that a functional impairment of the prefrontal cortex (PFC) is implicated in the pathophysiology of these diseases. Therefore, chronic stress may impair PFC functions required for the adaptive orchestration of behavioral responses. In the present review, we integrate evidence obtained from cognitive neuroscience with neurophysiological research with animal models, to put forward a hypothesis that addresses stress-induced behavioral dysfunctions observed in stress-related neuropsychiatric disorders. We propose that chronic stress impairs mechanisms involved in neuronal functional connectivity in the PFC that are required for the formation of adaptive representations for the execution of adaptive behavioral responses. These considerations could be particularly relevant for understanding the pathophysiology of chronic stress-related neuropsychiatric disorders. PMID:26904302

  9. The Expression of Fn14 via Mechanical Stress-activated JNK Contributes to Apoptosis Induction in Osteoblasts*

    PubMed Central

    Matsui, Hiroyuki; Fukuno, Naoto; Kanda, Yoshiaki; Kantoh, Yusuke; Chida, Toko; Nagaura, Yuko; Suzuki, Osamu; Nishitoh, Hideki; Takeda, Kohsuke; Ichijo, Hidenori; Sawada, Yasuhiro; Sasaki, Keiichi; Kobayashi, Takayasu; Tamura, Shinri

    2014-01-01

    Bone mass is maintained by the balance between the activities of bone-forming osteoblasts and bone-resorbing osteoclasts. It is well known that adequate mechanical stress is essential for the maintenance of bone mass, whereas excess mechanical stress induces bone resorption. However, it has not been clarified how osteoblasts respond to different magnitudes of mechanical stress. Here we report that large-magnitude (12%) cyclic stretch induced Ca2+ influx, which activated reactive oxygen species generation in MC3T3-E1 osteoblasts. Reactive oxygen species then activated the ASK1-JNK/p38 pathways. The activated JNK led to transiently enhanced expression of FGF-inducible 14 (Fn14, a member of the TNF receptor superfamily) gene. Cells with enhanced expression of Fn14 subsequently acquired sensitivity to the ligand of Fn14, TNF-related weak inducer of apoptosis, and underwent apoptosis. On the other hand, the ASK1-p38 pathway induced expression of the monocyte chemoattractant protein 3 (MCP-3) gene, which promoted chemotaxis of preosteoclasts. In contrast, the ERK pathway was activated by small-magnitude stretching (1%) and induced expression of two osteogenic genes, collagen Ia (Col1a) and osteopontin (OPN). Moreover, activated JNK suppressed Col1a and OPN induction in large-magnitude mechanical stretch-loaded cells. The enhanced expression of Fn14 and MCP-3 by 12% stretch and the enhanced expression of Col1a and OPN by 1% stretch were also observed in mouse primary osteoblasts. These results suggest that differences in the response of osteoblasts to varying magnitudes of mechanical stress play a key role in switching the mode of bone metabolism between formation and resorption. PMID:24446436

  10. A mechanical property and stress corrosion evaluation of 431 stainless steel alloy

    NASA Technical Reports Server (NTRS)

    Montano, J. W.

    1973-01-01

    The mechanical properties of type 431 stainless steel in two conditions: annealed bar and hardened and tempered bar are presented. Test specimens, manufactured from approximately 1.0 inch (2.54 cm) diameter bar stock, were tested at temperatures of 80 F (+26.7 C), 0 F (-17.8 C), -100 F (-73 C), and -200 F (-129 C). The test data indicated excellent tensile strength, notched/unnotched tensile ratio, ductility, shear, and impact properties at all testing temperatures. Results of the alternate immersion stress corrosion tests on stressed and unstressed longitudinal tensile specimens 0.1250 inch (0.3175 cm) diameter and transverse C-ring specimens, machined from 1.0 inch (2.54 cm) diameter bar stock, indicated that the material is not susceptible to stress corrosion cracking when tested in a 3.5 percent NaCl solution for 180 days.

  11. Influence of fault geometry and tectonic driving stress orientation on the mechanics of multifault earthquakes

    NASA Astrophysics Data System (ADS)

    Madden, E. H.; Maerten, F.; Pollard, D. D.

    2012-12-01

    The M 7.3 28 June 1992 Landers, California earthquake was a well-documented event that highlighted the complex relationship between the earthquake and the multiple faults on which it occurred. Not only was fault slip data mapped in the field in detail, due to good exposure in the arid conditions of the Mojave Desert, but also it was one of the first earthquakes for which the surface displacement field was captured by satellite technology. In addition, precise aftershock relocations and fault plane solutions provide information about stress and fault behavior at depth. Study of fault interactions leading to the linkage of five right-lateral, strike-slip faults at Landers is aided by this abundance of available surface and subsurface data. While mapped near-field surface data often are restricted to the realm of the geologist, and subsurface data, such as aftershocks, often are restricted to the realm of the geophysicist, we find that integrating these data in mechanical forward models provides good constraint on the three-dimensional structures of the faults involved. Mechanical models also reveal that fault geometry and the orientation of the tectonic driving stress greatly influence whether or not slip is promoted across the extensional step between two of the faults along the southern-central rupture and elucidate the role of a crossing fault located within the step. Unfortunately, the orientation of the principal stresses are not well constrained near Landers or in many regions around the world. Previous determinations of the tectonic driving stress at Landers range from 7 degrees to 45 degrees, measured clockwise from North. We introduce a new stress inversion method that honors mechanical relationships among the remote stress state that is being inverted for, mainshock fault slip, the resulting total stress field following fault slip, and aftershocks. Use of the principal of superposition in this new algorithm obviates the need for the prohibitive computation

  12. Toward an understanding of mechanism of aging-induced oxidative stress in human mesenchymal stem cells.

    PubMed

    Benameur, Laila; Charif, Naceur; Li, Yueying; Stoltz, Jean-François; de Isla, Natalia

    2015-01-01

    Under physiological conditions, there is a production of limited range of free radicals. However, when the cellular antioxidant defence systems, overwhelm and fail to reverse back the free radicals to their normal basal levels, there is a creation of a condition of redox disequilibrium termed "oxidative stress", which is implicated in a very wide spectrum of genetic, metabolic, and cellular responses. The excess of free radicals can, cause unfavourable molecular alterations to biomolecules through oxidation of lipids, proteins, RNA and DNA, that can in turn lead to mutagenesis, carcinogenesis, and aging. Mesenchymal stem cells (MSCs) have been proven to be a promising source of cells for regenerative medicine, and to be useful in the treatment of pathologies in which tissue damage is linked to oxidative stress. Moreover, MSCs appeared to efficiently manage oxidative stress and to be more resistant to oxidative insult than normal somatic cells, making them an interesting and testable model for the role of oxidative stress in the aging process. In addition, aging is accompanied by a progressive decline in stem cell function, resulting in less effective tissue homeostasis and repair. Also, there is an obvious link between intracellular reactive oxygen species levels and cellular senescence. To date, few studies have investigated the promotion of aging by oxidative stress on human MSCs, and the mechanism by which oxidative stress induce stem cell aging is poorly understood. In this context, the aim of this review is to gain insight the current knowledge about the molecular mechanisms of aging-induced oxidative stress in human MSCs.

  13. Stress-intensity factors of r-cracks in fiber-reinforced composites under thermal and mechanical loading

    NASA Astrophysics Data System (ADS)

    Mueller, W. H.; Schmauder, S.

    1993-02-01

    The plane stress/plane strain problem of radial matrix cracking in fiber-reinforced composites, due to thermal mismatch and externally applied stress is solved numerically in the framework of linear elasticity, using Erdogan's integral equation technique. It is shown that, in order to obtain the results of the combined loading case, the solutions of purely thermal and purely mechanical loading can simply be superimposed. Stress-intensity factors are calculated for various lengths and distances of the crack from the interface for each of these loading conditions.

  14. Myocardial imaging with 99mTc-Tetrofosmin: Influence of post-stress acquisition time, regional radiotracer uptake, and wall motion abnormalities on the clinical result.

    PubMed

    Giorgetti, Assuero; Kusch, Annette; Casagranda, Mirta; Tagliavia, Irene D'Aragona; Marzullo, Paolo

    2010-04-01

    We previously demonstrated that early (15', T1) post-stress myocardial imaging with Tetrofosmin could be more accurate than standard acquisitions (45', T2) in identifying coronary artery disease. To clarify this phenomenon, 120 subjects (age 61 +/- 10 years) with both T1 and T2 scans were divided into Group 1 (53/120 pts) with more ischemia at T1 vs T2 imaging (T1-T2SDS > or = 3); Group 2 (67/120 pts) with similar results (T1-T2SDS < or = 2). Myocardial areas were categorized as control nonischemic, ischemic, and scarred on the basis of perfusion/contraction properties and coronary anatomy. In each area, regional myocardial count statistic and semiquantitative wall motion/thickening values were obtained. Analysis of T1 and T2 post-stress myocardial counts demonstrated a significant Tetrofosmin wash-out rate that was higher in Group 1 control nonischemic regions (15 +/- 8% vs 13.6 +/- 9.6%, P < .02), significantly lower in Group 1 ischemic regions (7 +/- 10% vs 12.2 +/- 9.5%, P < .0001), and comparable between scarred areas of the two groups (P = NS). Delta post-stress wall thickening (T1-T2) was lower in Group 1 ischemic regions (-4.5 +/- 9.15% vs -1.90 +/- 7.0%, P < .001) and comparable in both control nonischemic and scarred areas of the two groups (P = NS). The clinical result of Tetrofosmin gated-SPECT can be influenced by the post-stress acquisition time because of ischemic-induced regional wall thickening abnormalities and the existence of a differential radiotracer myocardial wash-out.

  15. Quantifying the Mechanical Properties of Materials and the Process of Elastic-Plastic Deformation under External Stress on Material

    PubMed Central

    Valíček, Jan; Harničárová, Marta; Öchsner, Andreas; Hutyrová, Zuzana; Kušnerová, Milena; Tozan, Hakan; Michenka, Vít; Šepelák, Vladimír; Mitaľ, Dušan; Zajac, Jozef

    2015-01-01

    The paper solves the problem of the nonexistence of a new method for calculation of dynamics of stress-deformation states of deformation tool-material systems including the construction of stress-strain diagrams. The presented solution focuses on explaining the mechanical behavior of materials after cutting by abrasive waterjet technology (AWJ), especially from the point of view of generated surface topography. AWJ is a flexible tool accurately responding to the mechanical resistance of the material according to the accurately determined shape and roughness of machined surfaces. From the surface topography, it is possible to resolve the transition from ideally elastic to quasi-elastic and plastic stress-strain states. For detecting the surface structure, an optical profilometer was used. Based on the analysis of experimental measurements and the results of analytical studies, a mathematical-physical model was created and an exact method of acquiring the equivalents of mechanical parameters from the topography of surfaces generated by abrasive waterjet cutting and external stress in general was determined. The results of the new approach to the construction of stress-strain diagrams are presented. The calculated values agreed very well with those obtained by a certified laboratory VÚHŽ. PMID:28793645

  16. Quantifying the Mechanical Properties of Materials and the Process of Elastic-Plastic Deformation under External Stress on Material.

    PubMed

    Valíček, Jan; Harničárová, Marta; Öchsner, Andreas; Hutyrová, Zuzana; Kušnerová, Milena; Tozan, Hakan; Michenka, Vít; Šepelák, Vladimír; Mitaľ, Dušan; Zajac, Jozef

    2015-11-03

    The paper solves the problem of the nonexistence of a new method for calculation of dynamics of stress-deformation states of deformation tool-material systems including the construction of stress-strain diagrams. The presented solution focuses on explaining the mechanical behavior of materials after cutting by abrasive waterjet technology (AWJ), especially from the point of view of generated surface topography. AWJ is a flexible tool accurately responding to the mechanical resistance of the material according to the accurately determined shape and roughness of machined surfaces. From the surface topography, it is possible to resolve the transition from ideally elastic to quasi-elastic and plastic stress-strain states. For detecting the surface structure, an optical profilometer was used. Based on the analysis of experimental measurements and the results of analytical studies, a mathematical-physical model was created and an exact method of acquiring the equivalents of mechanical parameters from the topography of surfaces generated by abrasive waterjet cutting and external stress in general was determined. The results of the new approach to the construction of stress-strain diagrams are presented. The calculated values agreed very well with those obtained by a certified laboratory VÚHŽ.

  17. Creep and stress rupture of oxide dispersion strengthened mechanically alloyed Inconel alloy MA 754

    NASA Technical Reports Server (NTRS)

    Howson, T. E.; Tien, J. K.; Stulga, J. E.

    1980-01-01

    The creep and stress rupture behavior of the mechanically alloyed oxide dispersion strengthened nickel-base alloy MA 754 was studied at 760, 982 and 1093 C. Tensile specimens with a fine, highly elongated grain structure, oriented parallel and perpendicular to the longitudinal grain direction were tested at various stresses in air under constant load. It was found that the apparent stress dependence was large, with power law exponents ranging from 19 to 33 over the temperature range studied. The creep activation energy, after correction for the temperature dependence of the elastic modulus, was close to but slightly larger than the activation energy for self diffusion. Rupture was intergranular and the rupture ductility as measured by percentage elongation was generally low, with values ranging from 0.5 to 16 pct. The creep properties are rationalized by describing the creep rates in terms of an effective stress which is the applied stress minus a resisting stress consistent with the alloy microstructure. Values of the resisting stress obtained through a curve fitting procedure are found to be close to the values of the particle by-pass stress for this oxide dispersion strengthened alloy, as calculated from the measured oxide particle distribution.

  18. A coupled mechanical-chemical model for reflecting the influence of stress on oxidation reactions in thermal barrier coating

    NASA Astrophysics Data System (ADS)

    Chen, Lin; Yueming, Li

    2018-06-01

    In this paper, a coupled mechanical-chemical model is established based on the thermodynamic framework, in which the contribution of chemical expansion to free energy is introduced. The stress-dependent chemical potential equilibrium at the gas-solid interface and the stress gradient-dependent diffusion equation as well as a so-called generalized force which is conjugate to the oxidation rate are derived from the proposed model, which could reflect the influence of stresses on the oxidation reaction. Based on the proposed coupled mechanical-chemical model, a user element subroutine is developed in ABAQUS. The numerical simulation of the high temperature oxidation in the thermal barrier coating is carried out to verify the accuracy of the proposed model, and then the influence of stresses on the oxidation reaction is investigated. In thermally grown oxide, the considerable stresses would be induced by permanent volumetric swelling during the oxidation. The stresses play an important role in the chemical potential equilibrium at the gas-solid interface and strongly affect the oxidation reaction. The gradient of the stresses, however, only occurs in the extremely thin oxidation front layer, which plays a very limited role in the oxidation reaction. The generalized force could be divided into the stress-dependent and the stress-independent parts. Comparing with the stress-independent part, the stress-dependent part is smaller, which has little influence on oxidation reaction.

  19. A novel perspective on neuron study: damaging and promoting effects in different neurons induced by mechanical stress.

    PubMed

    Wang, Yazhou; Wang, Wei; Li, Zong; Hao, Shilei; Wang, Bochu

    2016-10-01

    A growing volume of experimental evidence demonstrates that mechanical stress plays a significant role in growth, proliferation, apoptosis, gene expression, electrophysiological properties and many other aspects of neurons. In this review, first, the mechanical microenvironment and properties of neurons under in vivo conditions are introduced and analyzed. Second, research works in recent decades on the effects of different mechanical forces, especially compression and tension, on various neurons, including dorsal root ganglion neurons, retinal ganglion cells, cerebral cortex neurons, hippocampus neurons, neural stem cells, and other neurons, are summarized. Previous research results demonstrate that mechanical stress can not only injure neurons by damaging their morphology, impacting their electrophysiological characteristics and gene expression, but also promote neuron self-repair. Finally, some future perspectives in neuron research are discussed.

  20. Martensite phase stress and the strengthening mechanism in TRIP steel by neutron diffraction.

    PubMed

    Harjo, Stefanus; Tsuchida, Noriyuki; Abe, Jun; Gong, Wu

    2017-11-09

    Two TRIP-aided multiphase steels with different carbon contents (0.2 and 0.4 mass%) were analyzed in situ during tensile deformation by time-of-flight neutron diffraction to clarify the deformation induced martensitic transformation behavior and its role on the strengthening mechanism. The difference in the carbon content affected mainly the difference in the phase fractions before deformation, where the higher carbon content increased the phase fraction of retained austenite (γ). However, the changes in the relative fraction of martensitic transformation with respect to the applied strain were found to be similar in both steels since the carbon concentrations in γ were similar regardless of different carbon contents. The phase stress of martensite was found much larger than that of γ or bainitic ferrite since the martensite was generated at the beginning of plastic deformation. Stress contributions to the flow stress were evaluated by multiplying the phase stresses and their phase fractions. The stress contribution from martensite was observed increasing during plastic deformation while that from bainitic ferrite hardly changing and that from γ decreasing.

  1. [Traffic accidents associated with emotional stress after divorce].

    PubMed

    Cui, Li-Juan; Yi, Xu-Fu; Chen, Xiao-Gang

    2009-04-01

    In recent years, the traffic accidents increased gradually, especially those caused by the drivers daily emotional abnormality and in which the drivers were liable. This article reviewed the traffic accidents caused by divorced driver's emotional abnormality, illustrated the features of those accidents from the gender, age, occupation and mileage of drivers. It was considered that the major cause of those accidents was excessive drinking due to drivers' emotional stress. Suggestions about preventing the traffic accidents caused by emotional abnormality were put forward so as to make the corresponding rules and finally decrease the emotional abnormality traffic accidents.

  2. Heat or cold priming-induced cross-tolerance to abiotic stresses in plants: key regulators and possible mechanisms.

    PubMed

    Hossain, Mohammad Anwar; Li, Zhong-Guang; Hoque, Tahsina Sharmin; Burritt, David J; Fujita, Masayuki; Munné-Bosch, Sergi

    2018-01-01

    Plants growing under field conditions are constantly exposed, either simultaneously or sequentially, to more than one abiotic stress factor. Plants have evolved sophisticated sensory systems to perceive a number of stress signals that allow them to activate the most adequate response to grow and survive in a given environment. Recently, cross-stress tolerance (i.e. tolerance to a second, strong stress after a different type of mild primary stress) has gained attention as a potential means of producing stress-resistant crops to aid with global food security. Heat or cold priming-induced cross-tolerance is very common in plants and often results from the synergistic co-activation of multiple stress signalling pathways, which involve reactive nitrogen species (RNS), reactive oxygen species (ROS), reactive carbonyl species (RCS), plant hormones and transcription factors. Recent studies have shown that the signalling functions of ROS, RNS and RCS, most particularly hydrogen peroxide, nitric oxide (NO) and methylglyoxal (MG), provide resistance to abiotic stresses and underpin cross-stress tolerance in plants by modulating the expression of genes as well as the post-translational modification of proteins. The current review highlights the key regulators and mechanisms underlying heat or cold priming-induced cross-stress tolerance in plants, with a focus on ROS, MG and NO signalling, as well as on the role of antioxidant and glyoxalase systems, osmolytes, heat-shock proteins (HSPs) and hormones. Our aim is also to provide a comprehensive idea on the topic for researchers using heat or cold priming-induced cross-tolerance as a mechanism to improve crop yields under multiple abiotic stresses.

  3. Chronic Stress Alters Striosome-Circuit Dynamics, Leading to Aberrant Decision-Making.

    PubMed

    Friedman, Alexander; Homma, Daigo; Bloem, Bernard; Gibb, Leif G; Amemori, Ken-Ichi; Hu, Dan; Delcasso, Sebastien; Truong, Timothy F; Yang, Joyce; Hood, Adam S; Mikofalvy, Katrina A; Beck, Dirk W; Nguyen, Norah; Nelson, Erik D; Toro Arana, Sebastian E; Vorder Bruegge, Ruth H; Goosens, Ki A; Graybiel, Ann M

    2017-11-16

    Effective evaluation of costs and benefits is a core survival capacity that in humans is considered as optimal, "rational" decision-making. This capacity is vulnerable in neuropsychiatric disorders and in the aftermath of chronic stress, in which aberrant choices and high-risk behaviors occur. We report that chronic stress exposure in rodents produces abnormal evaluation of costs and benefits resembling non-optimal decision-making in which choices of high-cost/high-reward options are sharply increased. Concomitantly, alterations in the task-related spike activity of medial prefrontal neurons correspond with increased activity of their striosome-predominant striatal projection neuron targets and with decreased and delayed striatal fast-firing interneuron activity. These effects of chronic stress on prefronto-striatal circuit dynamics could be blocked or be mimicked by selective optogenetic manipulation of these circuits. We suggest that altered excitation-inhibition dynamics of striosome-based circuit function could be an underlying mechanism by which chronic stress contributes to disorders characterized by aberrant decision-making under conflict. VIDEO ABSTRACT. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Olfaction in eating disorders and abnormal eating behavior: a systematic review

    PubMed Central

    Islam, Mohammed A.; Fagundo, Ana B.; Arcelus, Jon; Agüera, Zaida; Jiménez-Murcia, Susana; Fernández-Real, José M.; Tinahones, Francisco J.; de la Torre, Rafael; Botella, Cristina; Frühbeck, Gema; Casanueva, Felipe F.; Menchón, José M.; Fernandez-Aranda, Fernando

    2015-01-01

    The study provides a systematic review that explores the current literature on olfactory capacity in abnormal eating behavior. The objective is to present a basis for discussion on whether research in olfaction in eating disorders may offer additional insight with regard to the complex etiopathology of eating disorders (ED) and abnormal eating behaviors. Electronic databases (Medline, PsycINFO, PubMed, Science Direct, and Web of Science) were searched using the components in relation to olfaction and combining them with the components related to abnormal eating behavior. Out of 1352 articles, titles were first excluded by title (n = 64) and then by abstract and fulltext resulting in a final selection of 14 articles (820 patients and 385 control participants) for this review. The highest number of existing literature on olfaction in ED were carried out with AN patients (78.6%) followed by BN patients (35.7%) and obese individuals (14.3%). Most studies were only conducted on females. The general findings support that olfaction is altered in AN and in obesity and indicates toward there being little to no difference in olfactory capacity between BN patients and the general population. Due to the limited number of studies and heterogeneity this review stresses on the importance of more research on olfaction and abnormal eating behavior. PMID:26483708

  5. Olfaction in eating disorders and abnormal eating behavior: a systematic review.

    PubMed

    Islam, Mohammed A; Fagundo, Ana B; Arcelus, Jon; Agüera, Zaida; Jiménez-Murcia, Susana; Fernández-Real, José M; Tinahones, Francisco J; de la Torre, Rafael; Botella, Cristina; Frühbeck, Gema; Casanueva, Felipe F; Menchón, José M; Fernandez-Aranda, Fernando

    2015-01-01

    The study provides a systematic review that explores the current literature on olfactory capacity in abnormal eating behavior. The objective is to present a basis for discussion on whether research in olfaction in eating disorders may offer additional insight with regard to the complex etiopathology of eating disorders (ED) and abnormal eating behaviors. Electronic databases (Medline, PsycINFO, PubMed, Science Direct, and Web of Science) were searched using the components in relation to olfaction and combining them with the components related to abnormal eating behavior. Out of 1352 articles, titles were first excluded by title (n = 64) and then by abstract and fulltext resulting in a final selection of 14 articles (820 patients and 385 control participants) for this review. The highest number of existing literature on olfaction in ED were carried out with AN patients (78.6%) followed by BN patients (35.7%) and obese individuals (14.3%). Most studies were only conducted on females. The general findings support that olfaction is altered in AN and in obesity and indicates toward there being little to no difference in olfactory capacity between BN patients and the general population. Due to the limited number of studies and heterogeneity this review stresses on the importance of more research on olfaction and abnormal eating behavior.

  6. Mitochondrial functions modulate neuroendocrine, metabolic, inflammatory, and transcriptional responses to acute psychological stress

    PubMed Central

    Picard, Martin; McManus, Meagan J.; Gray, Jason D.; Nasca, Carla; Moffat, Cynthia; Kopinski, Piotr K.; Seifert, Erin L.; McEwen, Bruce S.; Wallace, Douglas C.

    2015-01-01

    The experience of psychological stress triggers neuroendocrine, inflammatory, metabolic, and transcriptional perturbations that ultimately predispose to disease. However, the subcellular determinants of this integrated, multisystemic stress response have not been defined. Central to stress adaptation is cellular energetics, involving mitochondrial energy production and oxidative stress. We therefore hypothesized that abnormal mitochondrial functions would differentially modulate the organism’s multisystemic response to psychological stress. By mutating or deleting mitochondrial genes encoded in the mtDNA [NADH dehydrogenase 6 (ND6) and cytochrome c oxidase subunit I (COI)] or nuclear DNA [adenine nucleotide translocator 1 (ANT1) and nicotinamide nucleotide transhydrogenase (NNT)], we selectively impaired mitochondrial respiratory chain function, energy exchange, and mitochondrial redox balance in mice. The resulting impact on physiological reactivity and recovery from restraint stress were then characterized. We show that mitochondrial dysfunctions altered the hypothalamic–pituitary–adrenal axis, sympathetic adrenal–medullary activation and catecholamine levels, the inflammatory cytokine IL-6, circulating metabolites, and hippocampal gene expression responses to stress. Each mitochondrial defect generated a distinct whole-body stress-response signature. These results demonstrate the role of mitochondrial energetics and redox balance as modulators of key pathophysiological perturbations previously linked to disease. This work establishes mitochondria as stress-response modulators, with implications for understanding the mechanisms of stress pathophysiology and mitochondrial diseases. PMID:26627253

  7. Stress fractures: pathophysiology, clinical presentation, imaging features, and treatment options.

    PubMed

    Matcuk, George R; Mahanty, Scott R; Skalski, Matthew R; Patel, Dakshesh B; White, Eric A; Gottsegen, Christopher J

    2016-08-01

    Stress fracture, in its most inclusive description, includes both fatigue and insufficiency fracture. Fatigue fractures, sometimes equated with the term "stress fractures," are most common in runners and other athletes and typically occur in the lower extremities. These fractures are the result of abnormal, cyclical loading on normal bone leading to local cortical resorption and fracture. Insufficiency fractures are common in elderly populations, secondary to osteoporosis, and are typically located in and around the pelvis. They are a result of normal or traumatic loading on abnormal bone. Subchondral insufficiency fractures of the hip or knee may cause acute pain that may present in the emergency setting. Medial tibial stress syndrome is a type of stress injury of the tibia related to activity and is a clinical syndrome encompassing a range of injuries from stress edema to frank-displaced fracture. Atypical subtrochanteric femoral fracture associated with long-term bisphosphonate therapy is also a recently discovered entity that needs early recognition to prevent progression to a complete fracture. Imaging recommendations for evaluation of stress fractures include initial plain radiographs followed, if necessary, by magnetic resonance imaging (MRI), which is preferred over computed tomography (CT) and bone scintigraphy. Radiographs are the first-line modality and may reveal linear sclerosis and periosteal reaction prior to the development of a frank fracture. MRI is highly sensitive with findings ranging from periosteal edema to bone marrow and intracortical signal abnormality. Additionally, a brief description of relevant clinical management of stress fractures is included.

  8. Central mechanisms of stress-induced headache.

    PubMed

    Cathcart, S; Petkov, J; Winefield, A H; Lushington, K; Rolan, P

    2010-03-01

    Stress is the most commonly reported trigger of an episode of chronic tension-type headache (CTTH); however, the causal significance has not been experimentally demonstrated to date. Stress may trigger CTTH through hyperalgesic effects on already sensitized pain pathways in CTTH sufferers. This hypothesis could be partially tested by examining pain sensitivity in an experimental model of stress-induced headache in CTTH sufferers. Such examinations have not been reported to date. We measured pericranial muscle tenderness and pain thresholds at the finger, head and shoulder in 23 CTTH sufferers (CTH-S) and 25 healthy control subjects (CNT) exposed to an hour-long stressful mental task, and in 23 CTTH sufferers exposed to an hour-long neutral condition (CTH-N). Headache developed in 91% of CTH-S, 4% of CNT, and 17% of CTH-N subjects. Headache sufferers had increased muscle tenderness and reduced pain thresholds compared with healthy controls. During the task, muscle tenderness increased and pain thresholds decreased in the CTH-S group compared with CTH-N and CNT groups. Pre-task muscle tenderness and reduction in pain threshold during task were predictive of the development and intensity of headache following task. The main findings are that stress induced a headache in CTTH sufferers, and this was associated with pre-task muscle tenderness and stress-induced reduction in pain thresholds. The results support the hypothesis that stress triggers CTTH through hyperalgesic effects on already increased pain sensitivity in CTTH sufferers, reducing the threshold to noxious input from pericranial structures.

  9. A Modified Mechanical Threshold Stress Constitutive Model for Austenitic Stainless Steels

    NASA Astrophysics Data System (ADS)

    Prasad, K. Sajun; Gupta, Amit Kumar; Singh, Yashjeet; Singh, Swadesh Kumar

    2016-12-01

    This paper presents a modified mechanical threshold stress (m-MTS) constitutive model. The m-MTS model incorporates variable athermal and dynamic strain aging (DSA) Components to accurately predict the flow stress behavior of austenitic stainless steels (ASS)-316 and 304. Under strain rate variations between 0.01-0.0001 s-1, uniaxial tensile tests were conducted at temperatures ranging from 50-650 °C to evaluate the material constants of constitutive models. The test results revealed the high dependence of flow stress on strain, strain rate and temperature. In addition, it was observed that DSA occurred at elevated temperatures and very low strain rates, causing an increase in flow stress. While the original MTS model is capable of predicting the flow stress behavior for ASS, statistical parameters point out the inefficiency of the model when compared to other models such as Johnson Cook model, modified Zerilli-Armstrong (m-ZA) model, and modified Arrhenius-type equations (m-Arr). Therefore, in order to accurately model both the DSA and non-DSA regimes, the original MTS model was modified by incorporating variable athermal and DSA components. The suitability of the m-MTS model was assessed by comparing the statistical parameters. It was observed that the m-MTS model was highly accurate for the DSA regime when compared to the existing models. However, models like m-ZA and m-Arr showed better results for the non-DSA regime.

  10. Proanthocyanidins against Oxidative Stress: From Molecular Mechanisms to Clinical Applications

    PubMed Central

    Xiong, Xia; Lai, Rui

    2018-01-01

    Proanthocyanidins (PCs) are naturally occurring polyphenolic compounds abundant in many vegetables, plant skins (rind/bark), seeds, flowers, fruits, and nuts. Numerous in vitro and in vivo studies have demonstrated myriad effects potentially beneficial to human health, such as antioxidation, anti-inflammation, immunomodulation, DNA repair, and antitumor activity. Accumulation of prooxidants such as reactive oxygen species (ROS) exceeding cellular antioxidant capacity results in oxidative stress (OS), which can damage macromolecules (DNA, lipids, and proteins), organelles (membranes and mitochondria), and whole tissues. OS is implicated in the pathogenesis and exacerbation of many cardiovascular, neurodegenerative, dermatological, and metabolic diseases, both through direct molecular damage and secondary activation of stress-associated signaling pathways. PCs are promising natural agents to safely prevent acute damage and control chronic diseases at relatively low cost. In this review, we summarize the molecules and signaling pathways involved in OS and the corresponding therapeutic mechanisms of PCs. PMID:29750172

  11. Redox balance signalling in occupational stress: modification by nutraceutical intervention.

    PubMed

    Marotta, F; Naito, Y; Padrini, F; Xuewei, X; Jain, S; Soresi, V; Zhou, L; Catanzaro, R; Zhong, K; Polimeni, A; Chui, D H

    2011-01-01

    There is increasing evidence that psychosocial stress can be viewed as a system-wide derangement of cellular homeostasis, with heightened oxidative stress and triggered proinflammatory mechanisms. The aim of this study is twofold: a) to replicate findings that psychological stress increases oxidative damage and b) to determine whether a fermented papaya preparation known to exert significant protective antioxidant properties could buffer such increases in nuclear DNA damage while also inducing epigenetic protective mechanisms. Twenty-eight sedentary men and women (age range: 28-52), who reported living a stressful lifestyle but with an overall positive attitude, were recruited for this study. Chronic diseases as well as severe burnout and use of drugs for anxiety constituted exclusion criteria. Subjects were supplemented for 1 month with 9 g/day (4.5 g twice a day) of a certified fermented papaya preparation. All subjects were given a stress and sleep quality questionnaire together with a diet and life style assessment. Blood was collected at 2 and 4 week, erythrocyte and leukocyte were separated to assess redox balance and heme oxygenase-1 (HO-1) gene expression while bilirubin oxidized metabolites (BOMs) were tested in the urine. Stressed individuals showed a significant abnormality of redox status with increased MDA of erythrocyte and increased level of 8-0HdG in leukocyte and BOMs excretion (p<0.05). Nutraceutical supplementation brought about a normalization of such values already at the 2 week observation (p<0.05) together with a significant upregulation of HO-1 (p<0.01). Taken together, the results of this study confirm that stressful occupational life per se, without any overt psychiatric illness, may be associated to increased oxidative stress. Supplementation with functional food affecting redox regulation may be part of the therapeutic armamentarium to be considered in this clinical setting.

  12. Abnormal Uterine Bleeding FAQ

    MedlinePlus

    ... Abnormal Uterine Bleeding • What is a normal menstrual cycle? • When is bleeding abnormal? • At what ages is ... abnormal bleeding? •Glossary What is a normal menstrual cycle? The normal length of the menstrual cycle is ...

  13. Dual mechanisms regulating glutamate decarboxylases and accumulation of gamma-aminobutyric acid in tea (Camellia sinensis) leaves exposed to multiple stresses

    PubMed Central

    Mei, Xin; Chen, Yiyong; Zhang, Lingyun; Fu, Xiumin; Wei, Qing; Grierson, Don; Zhou, Ying; Huang, Yahui; Dong, Fang; Yang, Ziyin

    2016-01-01

    γ-Aminobutyric acid (GABA) is one of the major inhibitory neurotransmitters in the central nervous system. It has multiple positive effects on mammalian physiology and is an important bioactive component of tea (Camellia sinensis). GABA generally occurs at a very low level in plants but GABA content increases substantially after exposure to a range of stresses, especially oxygen-deficiency. During processing of tea leaves, a combination of anoxic stress and mechanical damage are essential for the high accumulation of GABA. This is believed to be initiated by a change in glutamate decarboxylase activity, but the underlying mechanisms are unclear. In the present study we characterized factors regulating the expression and activity of three tea glutamate decarboxylase genes (CsGAD1, 2, and 3), and their encoded enzymes. The results suggests that, unlike the model plant Arabidopsis thaliana, there are dual mechanisms regulating the accumulation of GABA in tea leaves exposed to multiple stresses, including activation of CsGAD1 enzymatic activity by calmodulin upon the onset of the stress and accumulation of high levels of CsGAD2 mRNA induced by a combination of anoxic stress and mechanical damage. PMID:27021285

  14. Dual mechanisms regulating glutamate decarboxylases and accumulation of gamma-aminobutyric acid in tea (Camellia sinensis) leaves exposed to multiple stresses.

    PubMed

    Mei, Xin; Chen, Yiyong; Zhang, Lingyun; Fu, Xiumin; Wei, Qing; Grierson, Don; Zhou, Ying; Huang, Yahui; Dong, Fang; Yang, Ziyin

    2016-03-29

    γ-Aminobutyric acid (GABA) is one of the major inhibitory neurotransmitters in the central nervous system. It has multiple positive effects on mammalian physiology and is an important bioactive component of tea (Camellia sinensis). GABA generally occurs at a very low level in plants but GABA content increases substantially after exposure to a range of stresses, especially oxygen-deficiency. During processing of tea leaves, a combination of anoxic stress and mechanical damage are essential for the high accumulation of GABA. This is believed to be initiated by a change in glutamate decarboxylase activity, but the underlying mechanisms are unclear. In the present study we characterized factors regulating the expression and activity of three tea glutamate decarboxylase genes (CsGAD1, 2, and 3), and their encoded enzymes. The results suggests that, unlike the model plant Arabidopsis thaliana, there are dual mechanisms regulating the accumulation of GABA in tea leaves exposed to multiple stresses, including activation of CsGAD1 enzymatic activity by calmodulin upon the onset of the stress and accumulation of high levels of CsGAD2 mRNA induced by a combination of anoxic stress and mechanical damage.

  15. Influence of external mechanical stress on electrical properties of single-crystal n-3C-SiC/p-Si heterojunction diode

    NASA Astrophysics Data System (ADS)

    Qamar, Afzaal; Veit Dao, Dzung; Tanner, Philip; Phan, Hoang-Phuong; Dinh, Toan; Dimitrijev, Sima

    2015-06-01

    This article reports for the first time the electrical properties of fabricated n-3C-SiC/p-Si heterojunction diodes under external mechanical stress in the [110] direction. An anisotype heterojunction diode of n-3C-SiC/p-Si was fabricated by depositing 3C-SiC onto the Si substrate by low-pressure chemical vapor deposition. The mechanical stress significantly affected the scaling current density of the heterojunction. The scaling current density increases with stress and is explained in terms of a band offset reduction at the SiC/Si interface under applied stress. A reduction in the barrier height across the junction owing to applied stress is also explained quantitatively.

  16. Sensorimotor integration: basic concepts, abnormalities related to movement disorders and sensorimotor training-induced cortical reorganization.

    PubMed

    Machado, Sergio; Cunha, Marlo; Velasques, Bruna; Minc, Daniel; Teixeira, Silmar; Domingues, Clayton A; Silva, Julio G; Bastos, Victor H; Budde, Henning; Cagy, Mauricio; Basile, Luis; Piedade, Roberto; Ribeiro, Pedro

    2010-10-01

    Sensorimotor integration is defined as the capability of the central nervous system to integrate different sources of stimuli, and parallelly, to transform such inputs in motor actions. To review the basic principles of sensorimotor integration, such as, its neural bases and its elementary mechanisms involved in specific goal-directed tasks performed by healthy subjects, and the abnormalities reported in the most common movement disorders, such as, Parkinson' disease, dystonia and stroke, like the cortical reorganization-related mechanisms. Whether these disorders are associated with an abnormal peripheral sensory input or defective central processing is still unclear, but most of the data support a central mechanism. We found that the sensorimotor integration process plays a potential role in elementary mechanisms involved in specific goal-directed tasks performed by healthy subjects and in occurrence of abnormalities in most common movement disorders and, moreover, play a potential role on the acquisition of abilities that have as critical factor the coupling of different sensory data which will constitute the basis of elaboration of motor outputs consciously goal-directed.

  17. The microstructure, mechanical stress, texture, and electromigration behavior of Al-Pd alloys

    NASA Astrophysics Data System (ADS)

    Rodbell, K. P.; Knorr, D. B.; Mis, J. D.

    1993-06-01

    As the minimum feature size of interconnect lines decreases below 0.5 urn, the need to control the line microstructure becomes increasingly important. The alloy content, deposition process, fabrication method, and thermal history all determine the microstructure of an interconnect, which, in turn, affects its performance and reliability. The motivation for this work was to characterize the microstructure of various sputtered Al-Pd alloys (Al-0.3wt.%Pd, Al-2Cu-0.3Pd, and Al-0.3Nb-0.3Pd) vs sputtered Al-Cu control samples (Al-0.5Cu and Al-2Cu) and to assess the role of grain size, mechanical stress, and crystallographic texture on the electromigration behavior of submicrometer wide lines. The grain size, mechanical stress, and texture of blanket films were measured as a function of annealing. The as-deposited film stress was tensile and followed a similar stress history on heating for all of the films; on cooling, however, significant differences were observed between the Al-Pd and Al-Cu films in the shape of their stress-temperature-curves. A strong (111) crystallographic texture was typically found for Al-Cu films deposited on SiO2. A stronger (111) texture resulted when Al-Cu was deposited on 25 nm titanium. Al-0.3Pd films, however, exhibited either a weak (111) or (220) texture when deposited on SiO2, which reverted to a strong (111) texture when deposited on 25 nm titanium. The electromigration lifetimes of passivated, ≈0.7 μm wide lines at 250°C and 2.5 × 106 A/cm2 for both single and multi-level samples (separated with W studs) are reported. The electromigration behavior of Al-0.3Pd was found to be less dependent on film microstructure than on the annealing atmosphere used, i.e. forming gas (90% N2-10%H2) annealed Al-0.3Pd films were superior to all of the alloys investigated, while annealing in only N2 resulted in poor lifetimes.

  18. Influence of solder joint length to the mechanical aspect during the thermal stress analysis

    NASA Astrophysics Data System (ADS)

    Tan, J. S.; Khor, C. Y.; Rahim, Wan Mohd Faizal Wan Abd; Ishak, Muhammad Ikman; Rosli, M. U.; Jamalludin, Mohd Riduan; Zakaria, M. S.; Nawi, M. A. M.; Aziz, M. S. Abdul; Ani, F. Che

    2017-09-01

    Solder joint is an important interconnector in surface mount technology (SMT) assembly process. The real time stress, strain and displacement of the solder joint is difficult to observe and assess the experiment. To tackle these problems, simulation analysis was employed to study the von Mises stress, strain and displacement in the thermal stress analysis by using Finite element based software. In this study, a model of leadless electronic package was considered. The thermal stress analysis was performed to investigate the effect of the solder length to those mechanical aspects. The simulation results revealed that solder length gives significant effect to the maximum von Mises stress to the solder joint. Besides, changes in solder length also influence the displacement of the solder joint in the thermal environment. The increment of the solder length significantly reduces the von Mises stress and strain on the solder joint. Thus, the understanding of the physical parameter for solder joint is important for engineer prior to designing the solder joint of the electronic component.

  19. Serum Response Factor (SRF) Ablation Interferes with Acute Stress-Associated Immediate and Long-Term Coping Mechanisms.

    PubMed

    Zimprich, Annemarie; Mroz, Gabi; Meyer Zu Reckendorf, Christopher; Anastasiadou, Sofia; Förstner, Philip; Garrett, Lillian; Hölter, Sabine M; Becker, Lore; Rozman, Jan; Prehn, Cornelia; Rathkolb, Birgit; Moreth, Kristin; Wurst, Wolfgang; Klopstock, Thomas; Klingenspor, Martin; Adamski, Jerzy; Wolf, Eckhard; Bekeredjian, Raffi; Fuchs, Helmut; Gailus-Durner, Valerie; de Angelis, Martin Hrabe; Knöll, Bernd

    2017-12-01

    Stress experience modulates behavior, metabolism, and energy expenditure of organisms. One molecular hallmark of an acute stress response is a rapid induction of immediate early genes (IEGs) such as c-Fos and Egr family members. IEG transcription in neurons is mediated by the neuronal activity-driven gene regulator serum response factor (SRF). We show a first role of SRF in immediate and long-lasting acute restraint stress (AS) responses. For this, we employed a standardized mouse phenotyping protocol at the German Mouse Clinic (GMC) including behavioral, metabolic, and cardiologic tests as well as gene expression profiling to analyze the consequences of forebrain-specific SRF deletion in mice exposed to AS. Adult mice with an SRF deletion in glutamatergic neurons (Srf; CaMKIIa-CreERT2 ) showed hyperactivity, decreased anxiety, and impaired working memory. In response to restraint AS, instant stress reactivity including locomotor behavior and corticosterone induction was impaired in Srf mutant mice. Interestingly, even several weeks after previous AS exposure, SRF-deficient mice showed long-lasting AS-associated changes including altered locomotion, metabolism, energy expenditure, and cardiovascular changes. This suggests a requirement of SRF for mediating long-term stress coping mechanisms in wild-type mice. SRF ablation decreased AS-mediated IEG induction and activity of the actin severing protein cofilin. In summary, our data suggest an SRF function in immediate AS reactions and long-term post-stress-associated coping mechanisms.

  20. Defining the Role of Solid Stress and Matrix Stiffness in Cancer Cell Proliferation and Metastasis

    PubMed Central

    Kalli, Maria; Stylianopoulos, Triantafyllos

    2018-01-01

    Solid tumors are characterized by an abnormal stroma that contributes to the development of biomechanical abnormalities in the tumor microenvironment. In particular, these abnormalities include an increase in matrix stiffness and an accumulation of solid stress in the tumor interior. So far, it is not clearly defined whether matrix stiffness and solid stress are strongly related to each other or they have distinct roles in tumor progression. Moreover, while the effects of stiffness on tumor progression are extensively studied compared to the contribution of solid stress, it is important to ascertain the biological outcomes of both abnormalities in tumorigenesis and metastasis. In this review, we discuss how each of these parameters is evolved during tumor growth and how these parameters are influenced by each other. We further review the effects of matrix stiffness and solid stress on the proliferative and metastatic potential of cancer and stromal cells and summarize the in vitro experimental setups that have been designed to study the individual contribution of these parameters. PMID:29594037

  1. Urine - abnormal color

    MedlinePlus

    ... medlineplus.gov/ency/article/003139.htm Urine - abnormal color To use the sharing features on this page, please enable JavaScript. The usual color of urine is straw-yellow. Abnormally colored urine ...

  2. Abnormal proactive and reactive cognitive control during conflict processing in major depression.

    PubMed

    Vanderhasselt, Marie-Anne; De Raedt, Rudi; De Paepe, Annick; Aarts, Kristien; Otte, Georges; Van Dorpe, Jan; Pourtois, Gilles

    2014-02-01

    According to the Dual Mechanisms of Control framework, cognitive control consists of two complementary components: proactive control refers to anticipatory maintenance of goal-relevant information, whereas reactive control acts as a correction mechanism that is activated when a conflict occurs. Possibly, the well-known diminished inhibitory control in response to negative stimuli in Major Depressive Disorder (MDD) patients stems from a breakdown in proactive control, and/or anomalies in reactive cognitive control. In our study, MDD patients specifically showed increased response latencies when actively inhibiting a dominant response to a sad compared with a happy face. This condition was associated with a longer duration of a dominant ERP topography (800-900 ms poststimulus onset) and a stronger activity in the bilateral dorsal anterior cingulate cortex, reflecting abnormal reactive control when inhibiting attention to a negative stimulus. Moreover, MDD patients showed abnormalities in proactive cognitive control when preparing for the upcoming imperative stimulus (abnormal modulation of the contingent negative variation component), accompanied by more activity in brain regions belonging to the default mode network. All together, deficits to inhibit attention to negative information in MDD might originate from an abnormal use of both proactive resources and reactive control processes. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  3. Peripuberty stress leads to abnormal aggression, altered amygdala and orbitofrontal reactivity and increased prefrontal MAOA gene expression

    PubMed Central

    Márquez, C; Poirier, G L; Cordero, M I; Larsen, M H; Groner, A; Marquis, J; Magistretti, P J; Trono, D; Sandi, C

    2013-01-01

    Although adverse early life experiences have been found to increase lifetime risk to develop violent behaviors, the neurobiological mechanisms underlying these long-term effects remain unclear. We present a novel animal model for pathological aggression induced by peripubertal exposure to stress with face, construct and predictive validity. We show that male rats submitted to fear-induction experiences during the peripubertal period exhibit high and sustained rates of increased aggression at adulthood, even against unthreatening individuals, and increased testosterone/corticosterone ratio. They also exhibit hyperactivity in the amygdala under both basal conditions (evaluated by 2-deoxy-glucose autoradiography) and after a resident–intruder (RI) test (evaluated by c-Fos immunohistochemistry), and hypoactivation of the medial orbitofrontal (MO) cortex after the social challenge. Alterations in the connectivity between the orbitofrontal cortex and the amygdala were linked to the aggressive phenotype. Increased and sustained expression levels of the monoamine oxidase A (MAOA) gene were found in the prefrontal cortex but not in the amygdala of peripubertally stressed animals. They were accompanied by increased activatory acetylation of histone H3, but not H4, at the promoter of the MAOA gene. Treatment with an MAOA inhibitor during adulthood reversed the peripuberty stress-induced antisocial behaviors. Beyond the characterization and validation of the model, we present novel data highlighting changes in the serotonergic system in the prefrontal cortex—and pointing at epigenetic control of the MAOA gene—in the establishment of the link between peripubertal stress and later pathological aggression. Our data emphasize the impact of biological factors triggered by peripubertal adverse experiences on the emergence of violent behaviors. PMID:23321813

  4. Peripuberty stress leads to abnormal aggression, altered amygdala and orbitofrontal reactivity and increased prefrontal MAOA gene expression.

    PubMed

    Márquez, C; Poirier, G L; Cordero, M I; Larsen, M H; Groner, A; Marquis, J; Magistretti, P J; Trono, D; Sandi, C

    2013-01-15

    Although adverse early life experiences have been found to increase lifetime risk to develop violent behaviors, the neurobiological mechanisms underlying these long-term effects remain unclear. We present a novel animal model for pathological aggression induced by peripubertal exposure to stress with face, construct and predictive validity. We show that male rats submitted to fear-induction experiences during the peripubertal period exhibit high and sustained rates of increased aggression at adulthood, even against unthreatening individuals, and increased testosterone/corticosterone ratio. They also exhibit hyperactivity in the amygdala under both basal conditions (evaluated by 2-deoxy-glucose autoradiography) and after a resident-intruder (RI) test (evaluated by c-Fos immunohistochemistry), and hypoactivation of the medial orbitofrontal (MO) cortex after the social challenge. Alterations in the connectivity between the orbitofrontal cortex and the amygdala were linked to the aggressive phenotype. Increased and sustained expression levels of the monoamine oxidase A (MAOA) gene were found in the prefrontal cortex but not in the amygdala of peripubertally stressed animals. They were accompanied by increased activatory acetylation of histone H3, but not H4, at the promoter of the MAOA gene. Treatment with an MAOA inhibitor during adulthood reversed the peripuberty stress-induced antisocial behaviors. Beyond the characterization and validation of the model, we present novel data highlighting changes in the serotonergic system in the prefrontal cortex-and pointing at epigenetic control of the MAOA gene-in the establishment of the link between peripubertal stress and later pathological aggression. Our data emphasize the impact of biological factors triggered by peripubertal adverse experiences on the emergence of violent behaviors.

  5. Biological Mechanisms Underlying the Relationship between Stress and Smoking: State of the Science and Directions for Future Work

    PubMed Central

    Richards, Jessica; Stipelman, Brooke A.; Bornovalova, Marina A.; Daughters, Stacey; Sinha, Rajita; Lejuez, C.W.

    2011-01-01

    Theories of addiction implicate stress as a crucial mechanism underlying initiation, maintenance, and relapse to cigarette smoking. Examinations of the biological stress systems, including functioning of the hypothalamic-pituitary-adrenal (HPA) axis and the autonomic nervous system (ANS), have provided additional insights into the relationship between stress and smoking. To date, convergent data suggests that chronic cigarette smoking is associated with alterations in HPA and ANS functioning; however, less is known about the role of HPA and ANS functioning in smoking initiation and relapse following cessation. In order to organize existing findings and stimulate future research, the current paper summarizes the available literature on the roles of HPA axis and ANS functioning in the relationship between stress and cigarette smoking, highlights limitations within the existing literature, and suggests directions for future research to address unanswered questions in the extant literature on the biological mechanisms underlying the relationship between stress and smoking. PMID:21741435

  6. Fiber post cementation strategies: effect of mechanical cycling on push-out bond strength and cement polymerization stress.

    PubMed

    Bergoli, Cesar Dalmolin; Amaral, Marina; Boaro, Leticia Cristina; Braga, Roberto Ruggiero; Valandro, Luiz Felipe

    2012-08-01

    To evaluate the effect of mechanical cycling and cementation strategies on the push-out bond strength between fiber posts and root dentin and the polymerization stresses produced using three resin cements. Eighty bovine mandibular teeth were sectioned to a length of 16 mm, prepared to 12 mm, and embedded in self-curing acrylic resin. The specimens were then distributed into 8 groups (n = 10): Gr1 - Scotchbond Multi Purpose + RelyX ARC; Gr2 - Scotchbond Multi Purpose + RelyX ARC + mechanical cycling; Gr3 - AdheSE + Multilink Automix; Gr4 - AdheSE + Multilink Automix + mechanical cycling; Gr5 - phosphoric acid + RelyX U100 (self-adhesive cement); Gr6 - phosphoric acid+ RelyX U100 + mechanical cycling; Gr7 - RelyX U100; Gr8 - RelyX U100 + mechanical cycling. The values obtained from the push-out bond strength test were submitted to two-way ANOVA and Tukey's test (p = 0.05), while the values obtained from the polymerization stress test were subjected to one-way ANOVA and Tukey's test (α = 0.05). Mechanical cycling did not affect the bond strength values (p = 0.236), while cementation strategies affected the push-out bond strength (p < 0.001). Luting with RelyX U100 and Scotch Bond Multi Purpose + RelyX ARC yielded higher push-out bond strength values. The polymerization stress results were affected by the factor "cement" (p = 0.0104): the self-adhesive cement RelyX U100 exhibited the lowest values, RelyX ARC resulted in the highest values, while Multilink Automix presented values statistically similar to the other two cements. The self-adhesive cement appears to be a good alternative for luting fiber posts due to the high push-out bond strengths and lower polymerization stress values.

  7. Neuroimaging evidence of brain abnormalities in mastocytosis.

    PubMed

    Boddaert, N; Salvador, A; Chandesris, M O; Lemaître, H; Grévent, D; Gauthier, C; Naggara, O; Georgin-Lavialle, S; Moura, D S; Munsch, F; Jaafari, N; Zilbovicius, M; Lortholary, O; Gaillard, R; Hermine, O

    2017-08-08

    Mastocytosis is a rare disease in which chronic symptoms are related to mast cell accumulation and activation. Patients can display depression-anxiety-like symptoms and cognitive impairment. The pathophysiology of these symptoms may be associated with tissular mast cell infiltration, mast cell mediator release or both. The objective of this study is to perform morphological or functional brain analyses in mastocytosis to identify brain changes associated with this mast cell disorder. We performed a prospective and monocentric comparative study to evaluate the link between subjective psycho-cognitive complaints, psychiatric evaluation and objective medical data using magnetic resonance imaging with morphological and perfusion sequences (arterial spin-labeled perfusion) in 39 patients with mastocytosis compared with 33 healthy controls. In the test cohort of 39 mastocytosis patients with psycho-cognitive complaints, we found that 49% of them had morphological brain abnormalities, mainly abnormal punctuated white matter abnormalities (WMA). WMA were equally frequent in cutaneous mastocytosis patients and indolent forms of systemic mastocytosis patients (42% and 41% of patients with WMA, respectively). Patients with WMA showed increased perfusion in the putamen compared with patients without WMA and with healthy controls. Putamen perfusion was also negatively correlated with depression subscores. This study demonstrates, for we believe the first time, a high prevalence of morphological and functional abnormalities in the brains of mastocytosis patients with neuropsychiatric complaints. Further studies are required to determine the mechanism underpinning this association and to ascertain its specificity.

  8. The mechanisms of cachexia underlying muscle dysfunction in COPD.

    PubMed

    Remels, A H V; Gosker, H R; Langen, R C J; Schols, A M W J

    2013-05-01

    Pulmonary cachexia is a prevalent, debilitating, and well-recognized feature of COPD associated with increased mortality and loss of peripheral and respiratory muscle function. The exact cause and underlying mechanisms of cachexia in COPD are still poorly understood. Increasing evidence, however, shows that pathological changes in intracellular mechanisms of muscle mass maintenance (i.e., protein turnover and myonuclear turnover) are likely involved. Potential factors triggering alterations in these mechanisms in COPD include oxidative stress, myostatin, and inflammation. In addition to muscle wasting, peripheral muscle in COPD is characterized by a fiber-type shift toward a more type II, glycolytic phenotype and an impaired oxidative capacity (collectively referred to as an impaired oxidative phenotype). Atrophied diaphragm muscle in COPD, however, displays an enhanced oxidative phenotype. Interestingly, intrinsic abnormalities in (lower limb) peripheral muscle seem more pronounced in either cachectic patients or weight loss-susceptible emphysema patients, suggesting that muscle wasting and intrinsic changes in peripheral muscle's oxidative phenotype are somehow intertwined. In this manuscript, we will review alterations in mechanisms of muscle mass maintenance in COPD and discuss the involvement of oxidative stress, inflammation, and myostatin as potential triggers of cachexia. Moreover, we postulate that an impaired muscle oxidative phenotype in COPD can accelerate the process of cachexia, as it renders muscle in COPD less energy efficient, thereby contributing to an energy deficit and weight loss when not dietary compensated. Furthermore, loss of peripheral muscle oxidative phenotype may increase the muscle's susceptibility to inflammation- and oxidative stress-induced muscle damage and wasting.

  9. Trichloroethylene exposure aggravates behavioral abnormalities in mice that are deficient in superoxide dismutase.

    PubMed

    Otsuki, Noriyuki; Homma, Takujiro; Fujiwara, Hiroki; Kaneko, Kenya; Hozumi, Yasukazu; Shichiri, Mototada; Takashima, Mizuki; Ito, Junitsu; Konno, Tasuku; Kurahashi, Toshihiro; Yoshida, Yasukazu; Goto, Kaoru; Fujii, Satoshi; Fujii, Junichi

    2016-08-01

    Trichloroethylene (TCE) has been implicated as a causative agent for Parkinson's disease (PD). The administration of TCE to rodents induces neurotoxicity associated with dopaminergic neuron death, and evidence suggests that oxidative stress as a major player in the progression of PD. Here we report on TCE-induced behavioral abnormality in mice that are deficient in superoxide dismutase 1 (SOD1). Wild-type (WT) and SOD1-deficient (Sod1(-/-)) mice were intraperitoneally administered TCE (500 mg/kg) over a period of 4 weeks. Although the TCE-administrated Sod1(-/-) mice showed marked abnormal motor behavior, no significant differences were observed among the experimental groups by biochemical and histopathological analyses. However, treating mouse neuroblastoma-derived NB2a cells with TCE resulted in the down regulation of the SOD1 protein and elevated oxidative stress under conditions where SOD1 production was suppressed. Taken together, these data indicate that SOD1 plays a pivotal role in protecting motor neuron function against TCE toxicity. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. A cross-sectional study of the effects of load carriage on running characteristics and tibial mechanical stress: implications for stress-fracture injuries in women.

    PubMed

    Xu, Chun; Silder, Amy; Zhang, Ju; Reifman, Jaques; Unnikrishnan, Ginu

    2017-03-23

    Load carriage is associated with musculoskeletal injuries, such as stress fractures, during military basic combat training. By investigating the influence of load carriage during exercises on the kinematics and kinetics of the body and on the biomechanical responses of bones, such as the tibia, we can quantify the role of load carriage on bone health. We conducted a cross-sectional study using an integrated musculoskeletal-finite-element model to analyze how the amount of load carriage in women affected the kinematics and kinetics of the body, as well as the tibial mechanical stress during running. We also compared the biomechanics of walking (studied previously) and running under various load-carriage conditions. We observed substantial changes in both hip kinematics and kinetics during running when subjects carried a load. Relative to those observed during running without load, the joint reaction forces at the hip increased by an average of 49.1% body weight when subjects carried a load that was 30% of their body weight (ankle, 4.8%; knee, 20.6%). These results indicate that the hip extensor muscles in women are the main power generators when running with load carriage. When comparing running with walking, finite element analysis revealed that the peak tibial stress during running (tension, 90.6 MPa; compression, 136.2 MPa) was more than three times as great as that during walking (tension, 24.1 MPa; compression, 40.3 MPa), whereas the cumulative stress within one stride did not differ substantially between running (15.2 MPa · s) and walking (13.6 MPa · s). Our findings highlight the critical role of hip extensor muscles and their potential injury in women when running with load carriage. More importantly, our results underscore the need to incorporate the cumulative effect of mechanical stress when evaluating injury risk under various exercise conditions. The results from our study help to elucidate the mechanisms of stress fracture in women.

  11. Abnormal Elasticity of Single-Crystal Magnesiosiderite across the Spin Transition in Earth's Lower Mantle

    NASA Astrophysics Data System (ADS)

    Fu, Suyu; Yang, Jing; Lin, Jung-Fu

    2017-01-01

    Brillouin light scattering and impulsive stimulated light scattering have been used to determine the full elastic constants of magnesiosiderite [(Mg0.35Fe0.65)CO3 ] up to 70 GPa at room temperature in a diamond-anvil cell. Drastic softening in C11 , C33 , C12 , and C13 elastic moduli associated with the compressive stress component and stiffening in C44 and C14 moduli associated with the shear stress component are observed to occur within the spin transition between ˜42.4 and ˜46.5 GPa . Negative values of C12 and C13 are also observed within the spin transition region. The Born criteria constants for the crystal remain positive within the spin transition, indicating that the mixed-spin state remains mechanically stable. Significant auxeticity can be related to the electronic spin transition-induced elastic anomalies based on the analysis of Poisson's ratio. These elastic anomalies are explained using a thermoelastic model for the rhombohedral system. Finally, we conclude that mixed-spin state ferromagnesite, which is potentially a major deep-carbon carrier, is expected to exhibit abnormal elasticity, including a negative Poisson's ratio of -0.6 and drastically reduced VP by 10%, in Earth's midlower mantle.

  12. Thermal–mechanical stress analysis of pressurized water reactor pressure vessel with/without a preexisting crack under grid load following conditions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mohanty, Subhasish; Soppet, William K.; Majumdar, Saurin

    In this paper, we present thermal-mechanical stress analysis of a pressurized water reactor pressure vessel and its hot-leg and cold-leg nozzles. Results are presented from thermal and thermal-mechanical stress analysis under reactor heat-up, cool-down, and grid load-following conditions. Analysis results are given with and without the presence of preexisting crack in the reactor nozzle (axial crack in hot leg nozzle). From the model results it is found that the stress-strain states are significantly higher in case of presence of crack than without crack. In conclusion, the stress-strain state under grid load following condition are more realistic compared to the stress-strainmore » state estimated assuming simplified transients.« less

  13. Thermal–mechanical stress analysis of pressurized water reactor pressure vessel with/without a preexisting crack under grid load following conditions

    DOE PAGES

    Mohanty, Subhasish; Soppet, William K.; Majumdar, Saurin; ...

    2016-10-26

    In this paper, we present thermal-mechanical stress analysis of a pressurized water reactor pressure vessel and its hot-leg and cold-leg nozzles. Results are presented from thermal and thermal-mechanical stress analysis under reactor heat-up, cool-down, and grid load-following conditions. Analysis results are given with and without the presence of preexisting crack in the reactor nozzle (axial crack in hot leg nozzle). From the model results it is found that the stress-strain states are significantly higher in case of presence of crack than without crack. In conclusion, the stress-strain state under grid load following condition are more realistic compared to the stress-strainmore » state estimated assuming simplified transients.« less

  14. Response of Fe-S cluster assembly machinery of Escherichia coli to mechanical stress in a model of amino-acid crystal fermentation.

    PubMed

    Okutani, Satoshi; Iwai, Takayoshi; Iwatani, Shintaro; Matsuno, Kiyoshi; Takahashi, Yasuhiro; Hase, Toshiharu

    2015-09-01

    During amino-acid crystal fermentation, mechanical stress on bacterial cells caused by crystal collision often impacts negatively on bacterial growth and amino-acid production. When Escherichia coli cells were cultivated under mechanical stress of polyvinyl chloride particles as a model of the crystal fermentation, activities of iron-sulfur (Fe-S) cluster-containing enzymes were apparently decreased. Based on an assumption that function of Fe-S cluster assembly machinery would be elevated to recover the enzyme activities in such stressed cells, we analyzed levels of various components of Fe-S cluster assembly machinery by western blotting. It was found that the expression of HscA, a chaperon component of the machinery, was up-regulated and that shorter forms of HscA with the N-terminal region truncated were accumulated, suggesting an important role of HscA against the mechanical stress. An overexpression of HscA gene in E. coli cells gave a positive effect on rescue of the stress-induced decrease of the activity of Fe-S cluster-containing enzyme. These results may provide a new strategy to alleviate the mechanical stress during the amino-acid crystal fermentation. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  15. Mechanisms of disordered neurodegenerative function: concepts and facts about the different roles of the protein kinase RNA-like endoplasmic reticulum kinase (PERK).

    PubMed

    Taalab, Yasmeen M; Ibrahim, Nour; Maher, Ahmed; Hassan, Mubashir; Mohamed, Wael; Moustafa, Ahmed A; Salama, Mohamed; Johar, Dina; Bernstein, Larry

    2018-06-27

    Neurodegenerative diseases, such as Alzheimer's disease, Huntington's disease, Parkinson's disease, prion disease, and amyotrophic lateral sclerosis, are a dissimilar group of disorders that share a hallmark feature of accumulation of abnormal intraneuronal or extraneuronal misfolded/unfolded protein and are classified as protein misfolding disorders. Cellular and endoplasmic reticulum (ER) stress activates multiple signaling cascades of the unfolded protein response (UPR). Consequently, translational and transcriptional alterations in target gene expression occur in response directed toward restoring the ER capacity of proteostasis and reestablishing the cellular homeostasis. Evidences from in vitro and in vivo disease models indicate that disruption of ER homeostasis causes abnormal protein aggregation that leads to synaptic and neuronal dysfunction. However, the exact mechanism by which it contributes to disease progression and pathophysiological changes remains vague. Downstream signaling pathways of UPR are fully integrated, yet with diverse unexpected outcomes in different disease models. Three well-identified ER stress sensors have been implicated in UPR, namely, inositol requiring enzyme 1, protein kinase RNA-activated-like ER kinase (PERK), and activating transcription factor 6. Although it cannot be denied that each of the involved stress sensor initiates a distinct downstream signaling pathway, it becomes increasingly clear that shared pathways are crucial in determining whether or not the UPR will guide the cells toward adaptive prosurvival or proapoptotic responses. We review a body of work on the mechanism of neurodegenerative diseases based on oxidative stress and cell death pathways with emphasis on the role of PERK.

  16. Correlated accumulation of anthocyanins and rosmarinic acid in mechanically stressed red cell suspensions of basil (Ocimum basilicum).

    PubMed

    Strazzer, Pamela; Guzzo, Flavia; Levi, Marisa

    2011-02-15

    A red basil cell line (T2b) rich in rosmarinic acid (RA) was selected for the stable production of anthocyanins (ACs) in the dark. Cell suspension cultures were subjected to mechanical stress through increased agitation (switch from 90 to 150 rpm) to determine the relationship between AC and RA accumulation. Cell extracts were analyzed by HPLC and LC-MS, and the resulting data were processed with multivariate statistical analysis. MS and MS/MS spectra facilitated the putative annotation of several complex cyanidin-based ACs, which were esterified with coumaric acid and, in some cases, also with malonic acid. It was also possible to identify various RA-related molecules, some caffeic and coumaric acid derivatives and some flavanones. Mechanical stress increased the total AC and RA contents, but reduced biomass accumulation. Many metabolites were induced by mechanical stress, including RA and some of its derivatives, most ACs, hydroxycinnamic acids and flavonoids, whereas the abundance of some RA dimers was reduced. Although AC and RA share a common early biosynthetic pathway (from phenylalanine to 4-coumaroyl-CoA) and could have similar or overlapping functions providing antioxidant activity against stress-generated reactive oxygen species, there appeared to be no competition between their individual pathways. Copyright © 2010 Elsevier GmbH. All rights reserved.

  17. Molecular response of canola to salt stress: insights on tolerance mechanisms.

    PubMed

    Shokri-Gharelo, Reza; Noparvar, Pouya Motie

    2018-01-01

    Canola ( Brassica napus L. ) is widely cultivated around the world for the production of edible oils and biodiesel fuel. Despite many canola varieties being described as 'salt-tolerant', plant yield and growth decline drastically with increasing salinity. Although many studies have resulted in better understanding of the many important salt-response mechanisms that control salt signaling in plants, detoxification of ions, and synthesis of protective metabolites, the engineering of salt-tolerant crops has only progressed slowly. Genetic engineering has been considered as an efficient method for improving the salt tolerance of canola but there are many unknown or little-known aspects regarding canola response to salinity stress at the cellular and molecular level. In order to develop highly salt-tolerant canola, it is essential to improve knowledge of the salt-tolerance mechanisms, especially the key components of the plant salt-response network. In this review, we focus on studies of the molecular response of canola to salinity to unravel the different pieces of the salt response puzzle. The paper includes a comprehensive review of the latest studies, particularly of proteomic and transcriptomic analysis, including the most recently identified canola tolerance components under salt stress, and suggests what researchers should focus on in future studies.

  18. Behavior of stress generated in semiconductor chips with high-temperature joints: Influence of mechanical properties of joint materials

    NASA Astrophysics Data System (ADS)

    Ito, H.; Kuwahara, M.; Ohta, R.; Usui, M.

    2018-04-01

    High-temperature joint materials are indispensable to realizing next-generation power modules with high-output performance. However, crack initiation resulting from stress concentration in semiconductor chips joined with high-temperature joint materials remains a critical problem in high-temperature operation. Therefore, clarifying the quantitative influence of joint materials on the stress generated in chips is essential. This study investigates the stress behavior of chips joined by Ni-Sn solid-liquid interdiffusion (SLID), which results in a high-temperature joint material likely to generate cracks after joining or when under thermal cycling. The results are compared with those fabricated using three types of solders, Pb-10%Sn, Sn-0.7%Cu, and Sn-10%Sb (mass %), which are conventional joint materials with different melting points and mechanical properties. Using Ni-Sn SLID results in the generation of high compressive stress (500 MPa) without stress relaxation after the joining process in contrast to the case of solders in which the compressive stresses are low (<300 MPa) and decrease to still lower levels (<250 MPa). In addition, no stress relaxation occurs during thermal cycling when using Ni-Sn SLID, whereas stress relaxation is clearly observed during heating to 200 °C using solders. Different stress behaviors between Ni-Sn SLID and other joint materials are illustrated by their mechanical strength and resistance against plastic and creep deformation. These results suggest that stress relaxation in a chip is key in suppressing crack initiation in highly reliable modules during high-temperature operation.

  19. Central mechanisms for exercise training-induced reduction in sympatho-excitation in chronic heart failure.

    PubMed

    Haack, Karla K V; Zucker, Irving H

    2015-03-01

    The control of sympathetic outflow in the chronic heart failure (CHF) state is markedly abnormal. Patients with heart failure present with increased plasma norepinephrine and increased sympathetic nerve activity. The mechanism for this sympatho-excitation is multiple and varied. Both depression in negative feedback sensory control mechanisms and augmentation of excitatory reflexes contribute to this sympatho-excitation. These include the arterial baroreflex, cardiac reflexes, arterial chemoreflexes and cardiac sympathetic afferent reflexes. In addition, abnormalities in central signaling in autonomic pathways have been implicated in the sympatho-excitatory process in CHF. These mechanisms include increases in central Angiotensin II and the Type 1 receptor, increased in reactive oxygen stress, upregulation in glutamate signaling and NR1 (N-methyl-D-aspartate subtype 1) receptors and others. Exercise training in the CHF state has been shown to reduce sympathetic outflow and result in increased survival and reduced cardiac events. Exercise training has been shown to reduce central Angiotensin II signaling including the Type 1 receptor and reduce oxidative stress by lowering the expression of many of the subunits of NADPH oxidase. In addition, there are profound effects on the central generation of nitric oxide and nitric oxide synthase in sympatho-regulatory areas of the brain. Recent studies have pointed to the balance between Angiotensin Converting Enzyme (ACE) and ACE2, translating into Angiotensin II and Angiotensin 1-7 as important regulators of sympathetic outflow. These enzymes appear to be normalized following exercise training in CHF. Understanding the precise molecular mechanisms by which exercise training is sympatho-inhibitory will uncover new targets for therapy. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Dobutamine Stress Echocardiography and Tissue Synchronization Imaging

    PubMed Central

    Tas, Hakan; Gundogdu, Fuat; Gurlertop, Yekta; Karakelleoglu, Sule

    2008-01-01

    Dobutamine stress echocardiography has emerged as a reliable method for the diagnosis of coronary artery disease and the management of its treatment. Several studies have shown that that this technique works with 80–85% accuracy in comparison with other imaging methods. There are few studies aimed at developing the clinical utility of dobutamine stress echocardiography for the evaluation of normal and abnormal segments that result from dobutamine stress with Tissue Synchronization Imaging. PMID:25610034

  1. Streptozotocin induced oxidative stress, innate immune system responses and behavioral abnormalities in male mice.

    PubMed

    Amiri, Shayan; Haj-Mirzaian, Arya; Momeny, Majid; Amini-Khoei, Hossein; Rahimi-Balaei, Maryam; Poursaman, Simin; Rastegar, Mojgan; Nikoui, Vahid; Mokhtari, Tahmineh; Ghazi-Khansari, Mahmoud; Hosseini, Mir-Jamal

    2017-01-06

    Recent evidence indicates the involvement of inflammatory factors and mitochondrial dysfunction in the etiology of psychiatric disorders such as anxiety and depression. To investigate the possible role of mitochondrial-induced sterile inflammation in the co-occurrence of anxiety and depression, in this study, we treated adult male mice with the intracerebroventricular (i.c.v.) infusion of a single low dose of streptozotocin (STZ, 0.2mg/mouse). Using valid and qualified behavioral tests for the assessment of depressive and anxiety-like behaviors, we showed that STZ-treated mice exhibited behaviors relevant to anxiety and depression 24h following STZ treatment. We observed that the co-occurrence of anxiety and depressive-like behaviors in animals were associated with abnormal mitochondrial function, nitric oxide overproduction and, the increased activity of cytosolic phospholipase A 2 (cPLA 2 ) in the hippocampus. Further, STZ-treated mice had a significant upregulation of genes associated with the innate immune system such as toll-like receptors 2 and 4. Pathological evaluations showed no sign of neurodegeneration in the hippocampus of STZ-treated mice. Results of this study revealed that behavioral abnormalities provoked by STZ, as a cytotoxic agent that targets mitochondria and energy metabolism, are associated with abnormal mitochondrial activity and, consequently the initiation of innate-inflammatory responses in the hippocampus. Our findings highlight the role of mitochondria and innate immunity in the formation of sterile inflammation and behaviors relevant to anxiety and depression. Also, we have shown that STZ injection (i.c.v.) might be an animal model for depression and anxiety disorders based on sterile inflammation. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  2. Cardiac Dysfunction and Oxidative Stress in the Metabolic Syndrome: an Update on Antioxidant Therapies

    PubMed Central

    Ilkun, Olesya; Boudina, Sihem

    2013-01-01

    The metabolic syndrome (MetS) is a cluster of risk factors including obesity, insulin resistance, dyslipidemia, elevated blood pressure and glucose intolerance. The MetS increases the risk for cardiovascular disease (CVD) and type 2 diabetes. Each component of the MetS causes cardiac dysfunction and their combination carries additional risk. The mechanisms underlying cardiac dysfunction in the MetS are complex and might include lipid accumulation, increased fibrosis and stiffness, altered calcium homeostasis, abnormal autophagy, altered substrate utilization, mitochondrial dysfunction and increased oxidative stress. Mitochondrial and extra-mitochondrial sources of reactive oxygen species (ROS) and reduced antioxidant defense mechanisms characterize the myocardium of humans and animals with the MetS. The mechanisms for increased cardiac oxidative stress in the MetS are not fully understood but include increased fatty acid oxidation, mitochondrial dysfunction and enhanced NADPH oxidase activity. Therapies aimed to reduce oxidative stress and enhance antioxidant defense have been employed to reduce cardiac dysfunction in the MetS in animals. In contrast, large scale clinical trials using antioxidants therapies for the treatment of CVD have been disappointing because of the lack of efficacy and undesired side effects. The focus of this review is to summarize the current knowledge about the mechanisms underlying cardiac dysfunction in the MetS with a special interest in the role of oxidative stress. Finally, we will update the reader on the results obtained with natural antioxidant and mitochondria-targeted antioxidant therapies for the treatment of CVD in the MetS. PMID:23323621

  3. Neurologic Correlates of Gait Abnormalities in Cerebral Palsy: Implications for Treatment

    PubMed Central

    Zhou, Joanne; Butler, Erin E.; Rose, Jessica

    2017-01-01

    Cerebral palsy (CP) is the most common movement disorder in children. A diagnosis of CP is often made based on abnormal muscle tone or posture, a delay in reaching motor milestones, or the presence of gait abnormalities in young children. Neuroimaging of high-risk neonates and of children diagnosed with CP have identified patterns of neurologic injury associated with CP, however, the neural underpinnings of common gait abnormalities remain largely uncharacterized. Here, we review the nature of the brain injury in CP, as well as the neuromuscular deficits and subsequent gait abnormalities common among children with CP. We first discuss brain injury in terms of mechanism, pattern, and time of injury during the prenatal, perinatal, or postnatal period in preterm and term-born children. Second, we outline neuromuscular deficits of CP with a focus on spastic CP, characterized by muscle weakness, shortened muscle-tendon unit, spasticity, and impaired selective motor control, on both a microscopic and functional level. Third, we examine the influence of neuromuscular deficits on gait abnormalities in CP, while considering emerging information on neural correlates of gait abnormalities and the implications for strategic treatment. This review of the neural basis of gait abnormalities in CP discusses what is known about links between the location and extent of brain injury and the type and severity of CP, in relation to the associated neuromuscular deficits, and subsequent gait abnormalities. Targeted treatment opportunities are identified that may improve functional outcomes for children with CP. By providing this context on the neural basis of gait abnormalities in CP, we hope to highlight areas of further research that can reduce the long-term, debilitating effects of CP. PMID:28367118

  4. Interactions of Circadian Rhythmicity, Stress and Orexigenic Neuropeptide Systems: Implications for Food Intake Control.

    PubMed

    Blasiak, Anna; Gundlach, Andrew L; Hess, Grzegorz; Lewandowski, Marian H

    2017-01-01

    Many physiological processes fluctuate throughout the day/night and daily fluctuations are observed in brain and peripheral levels of several hormones, neuropeptides and transmitters. In turn, mediators under the "control" of the "master biological clock" reciprocally influence its function. Dysregulation in the rhythmicity of hormone release as well as hormone receptor sensitivity and availability in different tissues, is a common risk-factor for multiple clinical conditions, including psychiatric and metabolic disorders. At the same time circadian rhythms remain in a strong, reciprocal interaction with the hypothalamic-pituitary-adrenal (HPA) axis. Recent findings point to a role of circadian disturbances and excessive stress in the development of obesity and related food consumption and metabolism abnormalities, which constitute a major health problem worldwide. Appetite, food intake and energy balance are under the influence of several brain neuropeptides, including the orexigenic agouti-related peptide, neuropeptide Y, orexin, melanin-concentrating hormone and relaxin-3. Importantly, orexigenic neuropeptide neurons remain under the control of the circadian timing system and are highly sensitive to various stressors, therefore the potential neuronal mechanisms through which disturbances in the daily rhythmicity and stress-related mediator levels contribute to food intake abnormalities rely on reciprocal interactions between these elements.

  5. Interplay between Solo and keratin filaments is crucial for mechanical force–induced stress fiber reinforcement

    PubMed Central

    Fujiwara, Sachiko; Ohashi, Kazumasa; Mashiko, Toshiya; Kondo, Hiroshi; Mizuno, Kensaku

    2016-01-01

    Mechanical force–induced cytoskeletal reorganization is essential for cell and tissue remodeling and homeostasis; however, the underlying cellular mechanisms remain elusive. Solo (ARHGEF40) is a RhoA-targeting guanine nucleotide exchange factor (GEF) involved in cyclical stretch–induced human endothelial cell reorientation and convergent extension cell movement in zebrafish gastrula. In this study, we show that Solo binds to keratin-8/keratin-18 (K8/K18) intermediate filaments through multiple sites. Solo overexpression promotes the formation of thick actin stress fibers and keratin bundles, whereas knockdown of Solo, expression of a GEF-inactive mutant of Solo, or inhibition of ROCK suppresses stress fiber formation and leads to disorganized keratin networks, indicating that the Solo-RhoA-ROCK pathway serves to precisely organize keratin networks, as well as to promote stress fibers. Of importance, knockdown of Solo or K18 or overexpression of GEF-inactive or deletion mutants of Solo suppresses tensile force–induced stress fiber reinforcement. Furthermore, knockdown of Solo or K18 suppresses tensile force-induced RhoA activation. These results strongly suggest that the interplay between Solo and K8/K18 filaments plays a crucial role in tensile force–induced RhoA activation and consequent actin cytoskeletal reinforcement. PMID:26823019

  6. Stress injuries of the pars interarticularis: Radiologic classification and indications for radionuclide imaging

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pennell, R.; Maurer, A.R.; Bonakdarpour, A.

    Lumbar spine radiographs and radionuclide images were compared and correlated with clinical histories of 20 athletes with low back pain. Radiographs were classified as: Normal (Type 0); showing a healing stress fracture (an irregular lucent line) with sclerosis (Type I); as an evolving or healed stress injury with either sclerosis, narrowing, or demineralization (Type II); and as a chronic fracture showing a large lucency with well-defined margins classically referred to as spondylolysis (Type III). Patients were grouped clinically on the basis of their pain: acute onset (Group A, n = 7), acute superimposed on chronic (Group B, n = 9),more » and chronic pain without an acute event (Group C, n = 4). Radiographic abnormalities were present in 95% (19/20) of the patients and radionuclide studies were positive in 60% (12/20). Scintigraphy was positive most often with Type I pars abnormalities (77%, 10/13) and negative most often with Type III abnormalities (91%, 11/12). Of all positive scintigraphy 12/14 (86%) were in pts in Groups A and B (acute symptoms). The authors' findings support theories that radiographic pars abnormalities exist which correspond to stages in the healing of stress induced fractures. With acute symptoms radionuclide imaging need not be obtained if a Type I radiographic abnormality is seen. Radionuclide imaging is indicated with either Type 0, II or III radiographs to confirm or rule out recent stress injury.« less

  7. Instrumental learning and cognitive flexibility processes are impaired in children exposed to early life stress.

    PubMed

    Harms, Madeline B; Shannon Bowen, Katherine E; Hanson, Jamie L; Pollak, Seth D

    2017-10-19

    Children who experience severe early life stress show persistent deficits in many aspects of cognitive and social adaptation. Early stress might be associated with these broad changes in functioning because it impairs general learning mechanisms. To explore this possibility, we examined whether individuals who experienced abusive caregiving in childhood had difficulties with instrumental learning and/or cognitive flexibility as adolescents. Fifty-three 14-17-year-old adolescents (31 exposed to high levels of childhood stress, 22 control) completed an fMRI task that required them to first learn associations in the environment and then update those pairings. Adolescents with histories of early life stress eventually learned to pair stimuli with both positive and negative outcomes, but did so more slowly than their peers. Furthermore, these stress-exposed adolescents showed markedly impaired cognitive flexibility; they were less able than their peers to update those pairings when the contingencies changed. These learning problems were reflected in abnormal activity in learning- and attention-related brain circuitry. Both altered patterns of learning and neural activation were associated with the severity of lifetime stress that the adolescents had experienced. Taken together, the results of this experiment suggest that basic learning processes are impaired in adolescents exposed to early life stress. These general learning mechanisms may help explain the emergence of social problems observed in these individuals. © 2017 The Authors. Developmental Science Published by John Wiley & Sons Ltd.

  8. Endocide-Induced Abnormal Growth Forms of Invasive Giant Salvinia (Salvinia molesta).

    PubMed

    Li, Shiyou; Wang, Ping; Su, Zushang; Lozano, Emily; LaMaster, Olivia; Grogan, Jason B; Weng, Yuhui; Decker, Thomas; Findeisen, John; McGarrity, Monica

    2018-05-22

    Giant salvinia (Salvinia molesta) is one of the most noxious invasive species in the world. The fern is known to have primary, secondary, and tertiary growth forms, which are also commonly hypothesized as growth stages. The identification of these forms is primarily based on the size and folding status of the floating leaves. However, we identified 12 forms in the greenhouse and the field. Our experiments showed that the folding of floating leaves is a reversible trait dependent on water access. The floating leaves quickly fold in response to water shortage, reducing water loss and needs, decreasing growth, and avoiding trichome damage. The leaves re-open to allow trichomes repel water and enhance growth when having adequate water supply. Larger secondary or tertiary forms do not produce small-leaf primary forms without high intensity stress. These results do not support the hypothesis that three growth forms represent sequential growth stages. The abnormal small-leaf forms are the result of endocide-induced autotoxicity and some of them never grow into other forms. The development of abnormal forms and reversible leaf folding strategy in response to high stress along with rapid asexual reproduction are major adaptive traits contributing to the invasiveness of S. molesta.

  9. Deflection Analysis of the Space Shuttle External Tank Door Drive Mechanism

    NASA Technical Reports Server (NTRS)

    Tosto, Michael A.; Trieu, Bo C.; Evernden, Brent A.; Hope, Drew J.; Wong, Kenneth A.; Lindberg, Robert E.

    2008-01-01

    Upon observing an abnormal closure of the Space Shuttle s External Tank Doors (ETD), a dynamic model was created in MSC/ADAMS to conduct deflection analyses of the Door Drive Mechanism (DDM). For a similar analysis, the traditional approach would be to construct a full finite element model of the mechanism. The purpose of this paper is to describe an alternative approach that models the flexibility of the DDM using a lumped parameter approximation to capture the compliance of individual parts within the drive linkage. This approach allows for rapid construction of a dynamic model in a time-critical setting, while still retaining the appropriate equivalent stiffness of each linkage component. As a validation of these equivalent stiffnesses, finite element analysis (FEA) was used to iteratively update the model towards convergence. Following this analysis, deflections recovered from the dynamic model can be used to calculate stress and classify each component s deformation as either elastic or plastic. Based on the modeling assumptions used in this analysis and the maximum input forcing condition, two components in the DDM show a factor of safety less than or equal to 0.5. However, to accurately evaluate the induced stresses, additional mechanism rigging information would be necessary to characterize the input forcing conditions. This information would also allow for the classification of stresses as either elastic or plastic.

  10. Cholesteric liquid crystal gels with a graded mechanical stress

    NASA Astrophysics Data System (ADS)

    Agez, Gonzague; Relaix, Sabrina; Mitov, Michel

    2014-02-01

    In cholesteric liquid-crystalline gels, the mechanical role of the polymer network over the structure of the whole gel has been ignored. We show that it is the stress gradient exerted by the network over the helical structure that drives the broadening of the optical band gap, as evidenced by the absence of a gradient in chiral species. Model calculations and finite-difference time-domain simulations show that the network acts as a spring with a stiffness gradient. The present results indicate a revision to the common understanding of the physical properties of liquid-crystalline gels is necessary when a concentration gradient in a polymer network is present.

  11. Cholesteric liquid crystal gels with a graded mechanical stress.

    PubMed

    Agez, Gonzague; Relaix, Sabrina; Mitov, Michel

    2014-02-01

    In cholesteric liquid-crystalline gels, the mechanical role of the polymer network over the structure of the whole gel has been ignored. We show that it is the stress gradient exerted by the network over the helical structure that drives the broadening of the optical band gap, as evidenced by the absence of a gradient in chiral species. Model calculations and finite-difference time-domain simulations show that the network acts as a spring with a stiffness gradient. The present results indicate a revision to the common understanding of the physical properties of liquid-crystalline gels is necessary when a concentration gradient in a polymer network is present.

  12. Abnormal exhaled ethane concentrations in scleroderma.

    PubMed

    Cope, K A; Solga, S F; Hummers, L K; Wigley, F M; Diehl, A M; Risby, T H

    2006-01-01

    Scleroderma (systemic sclerosis) is a chronic multisystem autoimmune disease in which oxidative stress is suspected to play a role in the pathophysiology. Therefore, it was postulated that patients with scleroderma would have abnormally high breath ethane concentrations, which is a volatile product of free-radical-mediated lipid peroxidation, compared with a group of controls. There was a significant difference (p<0.05) between the mean exhaled ethane concentration of 5.27 pmol ml(-1) CO(2) (SEM=0.76) in the scleroderma patients (n=36) versus the mean exhaled concentration of 2.72 pmol ml(-1) CO(2) (SEM=0.71) in a group of healthy controls (n=21). Within the scleroderma group, those subjects taking a calcium channel blocker had lower ethane concentrations compared with patients who were not taking these drugs (p=0.05). There was a significant inverse association between lung diffusion capacity for carbon monoxide (per cent of predicted) and ethane concentration (b=-2.8, p=0.026, CI=-5.2 to -0.35). These data support the presence of increased oxidative stress among patients with scleroderma that is detected by measuring breath ethane concentrations.

  13. Abnormal pressures as hydrodynamic phenomena

    USGS Publications Warehouse

    Neuzil, C.E.

    1995-01-01

    So-called abnormal pressures, subsurface fluid pressures significantly higher or lower than hydrostatic, have excited speculation about their origin since subsurface exploration first encountered them. Two distinct conceptual models for abnormal pressures have gained currency among earth scientists. The static model sees abnormal pressures generally as relict features preserved by a virtual absence of fluid flow over geologic time. The hydrodynamic model instead envisions abnormal pressures as phenomena in which flow usually plays an important role. This paper develops the theoretical framework for abnormal pressures as hydrodynamic phenomena, shows that it explains the manifold occurrences of abnormal pressures, and examines the implications of this approach. -from Author

  14. Effect of the fungus Piriformospora indica on physiological characteristics and root morphology of wheat under combined drought and mechanical stresses.

    PubMed

    Hosseini, Fatemeh; Mosaddeghi, Mohammad Reza; Dexter, Anthony Roger

    2017-09-01

    This study was done to evaluate the effects of the root-colonizing endophytic fungus Piriformospora indica on wheat growth under combined drought and mechanical stresses. Inoculated (colonized) and non-inoculated (uncolonized) wheat (Triticum aestivum L. cv. Chamran) seedlings were planted in growth chambers filled with moist sand (at a matric suction of 20 hPa). Slight, moderate and severe mechanical stresses (i.e., penetration resistance, Q p , of 1.17, 4.17 and 5.96 MPa, respectively) were produced by a dead-load technique (i.e., placing a weight on the sand surface) in the root medium. Slight, moderate and severe drought stresses were induced using PEG 6000 solutions with osmotic potentials of 0, -0.3 and -0.5 MPa, respectively. After 30 days, plant physiological characteristics and root morphology were measured. An increase in Q p from 1.17 to 5.96 MPa led to greater leaf proline concentration and root diameter, and lower relative water content (RWC), leaf water potential (LWP), chlorophyll contents and root volume. Moreover, severe drought stress decreased root and shoot fresh weights, root volume, leaf area, RWC, LWP and chlorophyll content compared to control. Catalase (CAT) and ascorbate peroxidase (APX) activities under severe drought stress were about 1.5 and 2.9 times greater than control. Interaction of the stresses showed that mechanical stress primarily controls plant water status and physiological responses. However, endophyte presence mitigated the adverse effects of individual and combined stresses on plant growth. Colonized plants were better adapted and had greater root length and volume, RWC, LWP and chlorophyll contents under stressful conditions due to higher absorption sites for water and nutrients. Compared with uncolonized plants, colonized plants showed lower CAT activity implying that wheat inoculated with P. indica was more tolerant and experienced less oxidative damage induced by drought and/or mechanical stress. Copyright

  15. Molecular and Epigenetic Mechanisms for the Complex Effects of Stress on Synaptic Physiology and Cognitive Functions

    PubMed Central

    Yuen, Eunice Y.; Wei, Jing

    2017-01-01

    Abstract Evidence over the past decades has found that stress, particularly through the corticosterone stress hormones, produces complex changes in glutamatergic signaling in prefrontal cortex, which leads to the alteration of cognitive processes medicated by this brain region. Interestingly, the effects of stress on glutamatergic transmission appear to be “U-shaped,” depending upon the duration and severity of the stressor. These biphasic effects of acute vs chronic stress represent the adaptive vs maladaptive responses to stressful stimuli. Animal studies suggest that the stress-induced modulation of excitatory synaptic transmission involves changes in presynaptic glutamate release, postsynaptic glutamate receptor membrane trafficking and degradation, spine structure and cytoskeleton network, and epigenetic control of gene expression. This review will discuss current findings on the key molecules involved in the stress-induced regulation of prefrontal cortex synaptic physiology and prefrontal cortex-mediated functions. Understanding the molecular and epigenetic mechanisms that underlie the complex effects of stress will help to develop novel strategies to cope with stress-related mental disorders. PMID:29016816

  16. Molecular and Epigenetic Mechanisms for the Complex Effects of Stress on Synaptic Physiology and Cognitive Functions.

    PubMed

    Yuen, Eunice Y; Wei, Jing; Yan, Zhen

    2017-11-01

    Evidence over the past decades has found that stress, particularly through the corticosterone stress hormones, produces complex changes in glutamatergic signaling in prefrontal cortex, which leads to the alteration of cognitive processes medicated by this brain region. Interestingly, the effects of stress on glutamatergic transmission appear to be "U-shaped," depending upon the duration and severity of the stressor. These biphasic effects of acute vs chronic stress represent the adaptive vs maladaptive responses to stressful stimuli. Animal studies suggest that the stress-induced modulation of excitatory synaptic transmission involves changes in presynaptic glutamate release, postsynaptic glutamate receptor membrane trafficking and degradation, spine structure and cytoskeleton network, and epigenetic control of gene expression. This review will discuss current findings on the key molecules involved in the stress-induced regulation of prefrontal cortex synaptic physiology and prefrontal cortex-mediated functions. Understanding the molecular and epigenetic mechanisms that underlie the complex effects of stress will help to develop novel strategies to cope with stress-related mental disorders. © The Author 2017. Published by Oxford University Press on behalf of CINP.

  17. Coping as a mechanism linking stressful life events and mental health problems in adolescents.

    PubMed

    Meng, Xiu Hong; Tao, Fang Biao; Wan, Yu Hui; Hu, Yan; Wang, Ren Xi

    2011-12-01

    Although stressful life events represent an etiologic factor of mental health problems in adolescents, few studies have been conducted to address mechanisms linking the stress-psychopathology relation. The present study was designed to examine coping as a mediate factor on the relationship between stressful life events and symptoms of anxiety and depression. The participants were 13 512 students from eight cities of China, who participated in a school-based survey. Data were collected by a questionnaire comprising coping, stressful life events, anxiety, and depressive symptoms. As a model, a series of regression equations were used to examine whether coping mediated the association between stressful life events and symptoms of anxiety and depression. Each dimension of stressful life events showed significant correlation with anxiety, depression and coping (all P<0.001). In the model to analyze mediate effects, all standardized coefficients (β) were significant (all P<0.01), indicating marked mediator effects. Furthermore, negative coping might account for more mediate effects than positive coping on this relationship. Coping partially mediated the relationship between stressful life events and mental health during adolescence. This study highlighted an important public health priority for preventive interventions targeting stress-related psychopathology, and for further promoting adolescents' mental health. Copyright © 2011 The Editorial Board of Biomedical and Environmental Sciences. Published by Elsevier B.V. All rights reserved.

  18. Role of defense/stress-related marker genes, proteins and secondary metabolites in defining rice self-defense mechanisms.

    PubMed

    Jwa, Nam-Soo; Agrawal, Ganesh Kumar; Tamogami, Shigeru; Yonekura, Masami; Han, Oksoo; Iwahashi, Hitoshi; Rakwal, Randeep

    2006-01-01

    Rice, a first cereal crop whose draft genome sequence from two subspecies (japonica-type cv. Nipponbare and indica-type 93-11) was available in 2002, along with its almost complete genome sequence in 2005, has drawn the attention of researchers worldwide because of its immense impact on human existence. One of the most critical research areas in rice is to discern the self-defense mechanism(s), an innate property of all living organisms. The last few decades have seen scattered research into rice responses to diverse environmental stimuli and stress factors. Our understanding on rice self-defense mechanism has increased considerably with accelerated research during recent years mainly due to identification and characterization of several defense/stress-related components, genes, proteins and secondary metabolites. As these identified components have been used to study the defense/stress pathways, their compilation in this review will undoubtedly help rice (and others) researchers to effectively use them as a potential marker for better understanding, and ultimately, in defining rice (and plant) self-defense response pathways.

  19. Açaí (Euterpe oleracea Mart.) Modulates Oxidative Stress Resistance in Caenorhabditis elegans by Direct and Indirect Mechanisms

    PubMed Central

    Bonomo, Larissa de Freitas; Silva, David Nunes; Boasquivis, Patrícia Ferreira; Paiva, Franciny Aparecida; Guerra, Joyce Ferreira da Costa; Martins, Talita Alves Faria; de Jesus Torres, Álvaro Gustavo; de Paula, Igor Thadeu Borges Raposo; Caneschi, Washington Luiz; Jacolot, Philippe; Grossin, Nicolas; Tessier, Frederic J.; Boulanger, Eric; Silva, Marcelo Eustáquio; Pedrosa, Maria Lúcia; de Paula Oliveira, Riva

    2014-01-01

    Açaí (Euterpe oleracea Mart.) has recently emerged as a promising source of natural antioxidants. Despite its claimed pharmacological and nutraceutical value, studies regarding the effects of açaí in vivo are limited. In this study, we use the Caenorhabditis elegans model to evaluate the in vivo antioxidant properties of açaí on an organismal level and to examine its mechanism of action. Supplementation with açaí aqueous extract (AAE) increased both oxidative and osmotic stress resistance independently of any effect on reproduction and development. AAE suppressed bacterial growth, but this antimicrobial property did not influence stress resistance. AAE-increased stress resistance was correlated with reduced ROS production, the prevention of sulfhydryl (SH) level reduction and gcs-1 activation under oxidative stress conditions. Our mechanistic studies indicated that AAE promotes oxidative stress resistance by acting through DAF-16 and the osmotic stress response pathway OSR-1/UNC-43/SEK-1. Finally, AAE increased polyglutamine protein aggregation and decreased proteasome activity. Our findings suggest that natural compounds available in AAE can improve the antioxidant status of a whole organism under certain conditions by direct and indirect mechanisms. PMID:24594796

  20. Açaí (Euterpe oleracea Mart.) modulates oxidative stress resistance in Caenorhabditis elegans by direct and indirect mechanisms.

    PubMed

    Bonomo, Larissa de Freitas; Silva, David Nunes; Boasquivis, Patrícia Ferreira; Paiva, Franciny Aparecida; Guerra, Joyce Ferreira da Costa; Martins, Talita Alves Faria; de Jesus Torres, Álvaro Gustavo; de Paula, Igor Thadeu Borges Raposo; Caneschi, Washington Luiz; Jacolot, Philippe; Grossin, Nicolas; Tessier, Frederic J; Boulanger, Eric; Silva, Marcelo Eustáquio; Pedrosa, Maria Lúcia; Oliveira, Riva de Paula

    2014-01-01

    Açaí (Euterpe oleracea Mart.) has recently emerged as a promising source of natural antioxidants. Despite its claimed pharmacological and nutraceutical value, studies regarding the effects of açaí in vivo are limited. In this study, we use the Caenorhabditis elegans model to evaluate the in vivo antioxidant properties of açaí on an organismal level and to examine its mechanism of action. Supplementation with açaí aqueous extract (AAE) increased both oxidative and osmotic stress resistance independently of any effect on reproduction and development. AAE suppressed bacterial growth, but this antimicrobial property did not influence stress resistance. AAE-increased stress resistance was correlated with reduced ROS production, the prevention of sulfhydryl (SH) level reduction and gcs-1 activation under oxidative stress conditions. Our mechanistic studies indicated that AAE promotes oxidative stress resistance by acting through DAF-16 and the osmotic stress response pathway OSR-1/UNC-43/SEK-1. Finally, AAE increased polyglutamine protein aggregation and decreased proteasome activity. Our findings suggest that natural compounds available in AAE can improve the antioxidant status of a whole organism under certain conditions by direct and indirect mechanisms.