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Sample records for cardiac stress testing

  1. Heart-Kidney Biomarkers in Patients Undergoing Cardiac Stress Testing

    Directory of Open Access Journals (Sweden)

    Mikko Haapio

    2011-01-01

    Full Text Available We examined association of inducible myocardial perfusion defects with cardiorenal biomarkers, and of diminished left ventricular ejection fraction (LVEF with kidney injury marker plasma neutrophil gelatinase-associated lipocalin (NGAL. Patients undergoing nuclear myocardial perfusion stress imaging were divided into 2 groups. Biomarkers were analyzed pre- and poststress testing. Compared to the patients in the low ischemia group (n=16, the patients in the high ischemia group (n=18 demonstrated a significantly greater rise in cardiac biomarkers plasma BNP, NT-proBNP and cTnI. Subjects were also categorized based on pre- or poststress test detectable plasma NGAL. With stress, the group with no detectable NGAL had a segmental defect score 4.2 compared to 8.2 (P=.06 in the detectable NGAL group, and 0.9 vs. 3.8 (P=.03 at rest. BNP rose with stress to a greater degree in patients with detectable NGAL (10.2 vs. 3.5 pg/mL, P=.03. LVEF at rest and with stress was significantly lower in the detectable NGAL group; 55.8 versus 65.0 (P=.03 and 55.1 vs. 63.8 (P=.04, respectively. Myocardial perfusion defects associate with biomarkers of cardiac stress, and detectable plasma NGAL with significantly lower LVEF, suggesting a specific heart-kidney link.

  2. Physical Stress Echocardiography: Prediction of Mortality and Cardiac Events in Patients with Exercise Test showing Ischemia

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    Ana Carla Pereira de Araujo

    2014-11-01

    Full Text Available Background: Studies have demonstrated the diagnostic accuracy and prognostic value of physical stress echocardiography in coronary artery disease. However, the prediction of mortality and major cardiac events in patients with exercise test positive for myocardial ischemia is limited. Objective: To evaluate the effectiveness of physical stress echocardiography in the prediction of mortality and major cardiac events in patients with exercise test positive for myocardial ischemia. Methods: This is a retrospective cohort in which 866 consecutive patients with exercise test positive for myocardial ischemia, and who underwent physical stress echocardiography were studied. Patients were divided into two groups: with physical stress echocardiography negative (G1 or positive (G2 for myocardial ischemia. The endpoints analyzed were all-cause mortality and major cardiac events, defined as cardiac death and non-fatal acute myocardial infarction. Results: G2 comprised 205 patients (23.7%. During the mean 85.6 ± 15.0-month follow-up, there were 26 deaths, of which six were cardiac deaths, and 25 non-fatal myocardial infarction cases. The independent predictors of mortality were: age, diabetes mellitus, and positive physical stress echocardiography (hazard ratio: 2.69; 95% confidence interval: 1.20 - 6.01; p = 0.016. The independent predictors of major cardiac events were: age, previous coronary artery disease, positive physical stress echocardiography (hazard ratio: 2.75; 95% confidence interval: 1.15 - 6.53; p = 0.022 and absence of a 10% increase in ejection fraction. All-cause mortality and the incidence of major cardiac events were significantly higher in G2 (p < 0. 001 and p = 0.001, respectively. Conclusion: Physical stress echocardiography provides additional prognostic information in patients with exercise test positive for myocardial ischemia.

  3. Update on pharmacological cardiac stress testing: efficacy, risk stratification and patient selection.

    Science.gov (United States)

    Blankstein, Ron; Cannon, Christopher; Udelson, James

    2014-11-01

    Despite greater control of risk factors and improved treatments, coronary heart disease (CHD) remains a significant cause of mortality with 1 in every 4 deaths in the United States due to this disorder.(1) Cardiac stress tests have long been one of the most often utilized testing modalities used to identify patients suspected of having CHD, specifically coronary artery disease (CAD). These tests allow for noninvasive assessment of the coronary circulation and its ability to augment flow in response to physiologic demand. As with any diagnostic testing however, potential health risks as well as the financial burden of cardiovascular stress testing, must be weighed against the benefits and utility of the data procured. Given the rapidly evolving field of cardiac stress testing with respect to new risk stratification guidelines, new agents, and new assessment methods, it is difficult for physicians to remain up to date on the latest research and the benefits and risks of different testing modalities. A recent survey of primary care physicians and cardiologists conducted by the Elsevier Office of Continuing Medical Education found that approximately one-quarter of the cardiologists and primary care physicians surveyed do not feel confident identifying the factors which should be considered before ordering a cardiac stress test as part of pre-operative screening for a patient. Additionally, this survey also reported that primary care physicians reported a high degree of confidence in ordering the appropriate cardiac screening tests for patients yet, cardiologists reported that they frequently/somewhat frequently felt the need to change the test ordered by the internist. This educational intervention focuses on patient selection, exercise vs. pharmacologic stress testing, pharmacologic agents, and the importance of patient and doctor communication in ensuring the right test is recommended for the right patient. This CME Multimedia Activity is also available through the

  4. The early identification of psychosis: can lessons be learnt from cardiac stress testing?

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    Gupta, Swapnil; Ranganathan, Mohini; D'Souza, Deepak Cyril

    2016-01-01

    Psychotic disorders including schizophrenia are amongst the most debilitating psychiatric disorders. There is an urgent need to develop methods to identify individuals at risk with greater precision and as early as possible. At present, a prerequisite for a diagnosis of schizophrenia is the occurrence of a psychotic episode. Therefore, attempting to detect schizophrenia on the basis of psychosis is analogous to diagnosing coronary artery disease (CAD) after the occurrence of a myocardial infarction (MI). The introduction of cardiac stress testing (CST) has revolutionized the detection of CAD and the prevention and management of angina and MI. In this paper, we attempt to apply lessons learnt from CST to the early detection of psychosis by proposing the development of an analogous psychosis stress test. We discuss in detail the various parameters of a proposed psychosis stress test including the choice of a suitable psychological or psychopharmacological "stressor," target population, outcome measures, safety of the approach, and the necessary evolution of test to become clinically informative. The history of evolution of CST may guide the development of a similar approach for the detection and management of psychotic disorders. The initial development of a test to unmask latent risk for schizophrenia will require the selection of a suitable and safe stimulus and the development of outcome measures as a prelude to testing in populations with a range of risk to determine predictive value. The use of CST in CAD offers the intriguing possibility that a similar approach may be applied to the detection and management of schizophrenia.

  5. The utility of cardiac stress testing for detection of cardiovascular disease in breast cancer survivors: a systematic review

    Directory of Open Access Journals (Sweden)

    Kirkham AA

    2015-01-01

    Full Text Available Amy A Kirkham,1 Sean A Virani,2 Kristin L Campbell1,31Rehabilitation Sciences, 2Department of Medicine, 3Department of Physical Therapy, University of British Columbia, Vancouver, BC, CanadaBackground: Heart function tests performed with myocardial stress, or “cardiac stress tests”, may be beneficial for detection of cardiovascular disease. Women who have been diagnosed with breast cancer are more likely to develop cardiovascular diseases than the general population, in part due to the direct toxic effects of cancer treatment on the cardiovascular system. The aim of this review was to determine the utility of cardiac stress tests for the detection of cardiovascular disease after cardiotoxic breast cancer treatment.Design: Systematic review.Methods: Medline and Embase were searched for studies utilizing heart function tests in breast cancer survivors. Studies utilizing a cardiac stress test and a heart function test performed at rest were included to determine whether stress provided added benefit to identifying cardiac abnormalities that were undetected at rest within each study.Results: Fourteen studies were identified. Overall, there was a benefit to utilizing stress tests over tests at rest in identifying evidence of cardiovascular disease in five studies, a possible benefit in five studies, and no benefit in four studies. The most common type of stress test was myocardial perfusion imaging, where reversible perfusion defects were detected under stress in individuals who had no defects at rest, in five of seven studies of long-term follow-up. Two studies demonstrated the benefit of stress echocardiography over resting echocardiography for detecting left ventricular dysfunction in anthracycline-treated breast cancer survivors. There was no benefit of stress cardiac magnetic resonance imaging in one study. Two studies showed a potential benefit of stress electrocardiography, whereas three others did not.Conclusion: The use of cardiac stress

  6. Physical Stress Echocardiography: Prediction of Mortality and Cardiac Events in Patients with Exercise Test showing Ischemia.

    Science.gov (United States)

    Araujo, Ana Carla Pereira de; Santos, Bruno F de Oliveira; Calasans, Flavia Ricci; Pinto, Ibraim M Francisco; Oliveira, Daniel Pio de; Melo, Luiza Dantas; Andrade, Stephanie Macedo; Tavares, Irlaneide da Silva; Sousa, Antonio Carlos Sobral; Oliveira, Joselina Luzia Menezes

    2014-11-01

    Background: Studies have demonstrated the diagnostic accuracy and prognostic value of physical stress echocardiography in coronary artery disease. However, the prediction of mortality and major cardiac events in patients with exercise test positive for myocardial ischemia is limited. Objective: To evaluate the effectiveness of physical stress echocardiography in the prediction of mortality and major cardiac events in patients with exercise test positive for myocardial ischemia. Methods: This is a retrospective cohort in which 866 consecutive patients with exercise test positive for myocardial ischemia, and who underwent physical stress echocardiography were studied. Patients were divided into two groups: with physical stress echocardiography negative (G1) or positive (G2) for myocardial ischemia. The endpoints analyzed were all-cause mortality and major cardiac events, defined as cardiac death and non-fatal acute myocardial infarction. Results: G2 comprised 205 patients (23.7%). During the mean 85.6 ± 15.0-month follow-up, there were 26 deaths, of which six were cardiac deaths, and 25 non-fatal myocardial infarction cases. The independent predictors of mortality were: age, diabetes mellitus, and positive physical stress echocardiography (hazard ratio: 2.69; 95% confidence interval: 1.20 - 6.01; p = 0.016). The independent predictors of major cardiac events were: age, previous coronary artery disease, positive physical stress echocardiography (hazard ratio: 2.75; 95% confidence interval: 1.15 - 6.53; p = 0.022) and absence of a 10% increase in ejection fraction. All-cause mortality and the incidence of major cardiac events were significantly higher in G2 (p ecocardiografia com estresse físico na doença arterial coronária, mas a predição de mortalidade e de eventos cardíacos maiores, em pacientes com teste ergométrico positivo para isquemia miocárdica, é limitada. Objetivo: Avaliar a predição de mortalidade e de eventos cardíacos maiores pela

  7. Stress Echocardiography and Major Cardiac Events in Patients with Normal Exercise Test

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    Calasans, Flávia Ricci; Santos, Bruno Fernandes de Oliveira; Silveira, Débora Consuelo Rocha; de Araújo, Ana Carla Pereira; Melo, Luiza Dantas; Barreto-Filho, José Augusto; Sousa, Antônio Carlos Sobral; Oliveira, Joselina Luzia Menezes

    2013-01-01

    Background Exercise test (ET) is the preferred initial noninvasive test for the diagnosis and risk stratification of coronary artery disease (CAD), however, its lower sensitivity may fail to identify patients at greater risk of adverse events. Objective To assess the value of stress echocardiography (SE) for predicting all-cause mortality and major cardiac events (MACE) in patients with intermediate pretest probability of CAD and a normal ET. Methods 397 patients with intermediate CAD pretest probability, estimated by the Morise score, and normal ET who underwent SE were studied. The patients were divided into two groups according to the absence (G1) or presence (G2) of myocardial ischemia on SE .End points evaluated were all-cause mortality and MACE, defined as cardiac death and nonfatal acute myocardial infarction (AMI). Results G1 group was comprised of 329 (82.8%) patients. The mean age of the patients was 57.37 ± 11 years and 44.1% were male. During a mean follow-up of 75.94 ± 17.24 months, 13 patients died, three of them due to cardiac causes, and 13 patients suffered nonfatal AMI. Myocardial ischemia remained an independent predictor of MACE (HR 2.49; [CI] 95% 1.74-3.58). The independent predictors for all-cause mortality were male gender (HR 9.83; [CI] 95% 2.15-44.97) and age over 60 years (HR 4.57; [CI] 95% 1.39-15.23). Conclusion Positive SE for myocardial ischemia is a predictor of MACE in the studied sample, which helps to identify a subgroup of patients at higher risk of events despite having normal ET. PMID:23765384

  8. Do imaging studies performed in physician offices increase downstream utilization? An empiric analysis of cardiac stress testing with imaging

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    Chen, Jersey; Fazel, Reza; Ross, Joseph S.; McNamara, Robert L.; Einstein, Andrew J.; Al-Mallah, Mouaz; Krumholz, Harlan M.; Nallamothu, Brahmajee K.

    2012-01-01

    Objective To compare patterns of downstream testing and procedures after stress testing with imaging performed at physician offices versus at hospital-outpatient facilities. Background Stress testing with imaging has grown dramatically in recent years, but whether the location of where the test is performed correlates with different patterns for subsequent cardiac testing and procedures is unknown. Methods We identified 82,178 adults with private health insurance from 2005–2007 who underwent ambulatory myocardial perfusion imaging (MPI) or stress echocardiography (SE). Subsequent MPI, SE, cardiac catheterization or revascularization within 6 months were compared between physician office and hospital-outpatient settings. Results Overall, 84.5% of MPI and 84.9% of SE were performed in physician offices. The proportion of patients who underwent subsequent MPI, SE or cardiac catheterization was not statistically different between physician office and hospital-outpatient settings for MPI (14.2% v 14.1%, p=0.80) or SE (7.9% v 8.6%, p=0.21). However, patients with physician-office imaging had slightly higher rates of repeat MPI within 6 months compared with hospital-outpatient imaging for both index MPI (3.5% v 2.0%, p<0.001) and SE (3.4% v 2.1%, p<0.001), and slightly lower rates of cardiac catheterization after index MPI (11.5% v 12.3, p=0.01) and SE (4.5% v 7.0%, p<0.001). Differences in 6-month utilization were observed across the 5 healthcare markets after index MPI but not after index SE. Conclusions Physician office imaging is associated with slightly higher repeat MPI and fewer cardiac catheterizations than hospital outpatient imaging, but no overall difference in the proportion of patients undergoing additional further testing or procedures. While regional variation exists, especially for MPI, the relationship between physician-office location of stress testing with imaging and greater downstream resource utilization appears modest. PMID:21679898

  9. Effects of psychological stress test on the cardiac response of public safety workers: alternative parameters to autonomic balance

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    Huerta-Franco, M. R.; Vargas-Luna, F. M.; Delgadillo-Holtfort, I.

    2015-01-01

    It is well known that public safety workers (PSW) face many stressful situations that yield them as high-risk population for suffering chronic stress diseases. In this multidisciplinary research the cardiac response to induced psychological stress by a short duration Stroop test was evaluated in 20 female and 19 male PSW, in order to compare traditionally used cardiac response parameters with alternative ones. Electrocardiograms have been recorded using the Eindhoven electrodes configuration for 1 min before, 3 min during and 1 min after the test. Signals analysis has been performed for the heart rate and the power spectra of its variability and of the variability of the amplitude of the R-wave, i.e. the highest peak of the electrocardiographic signal periodic sequence. The results demonstrated that the traditional autonomic balance index shows no significant differences between stages. In contrast, the median of the area of the power spectrum of the R-wave amplitude variability in the frequency region dominated by the autonomous nervous system (0.04-to-0.4 Hz) is the more sensitive parameter. Moreover, this parameter allows to identify gender differences consistent with those encountered in other studies.

  10. Nuclear stress test

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    ... Persantine stress test; Thallium stress test; Stress test - nuclear; Adenosine stress test; Regadenoson stress test; CAD - nuclear stress; Coronary artery disease - nuclear stress; Angina - nuclear ...

  11. Cardiac stress MR imaging with dobutamine

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    Strach, K.; Meyer, C.; Schild, H.; Sommer, T. [University of Bonn, Department of Radiology, Bonn (Germany)

    2006-12-15

    Stress testing for detection of ischemia-induced wall-motion abnormalities has become a mainstay for noninvasive diagnosis and risk stratification of patients with suspected coronary artery disease (CAD). Recent technical developments in magnetic resonance imaging (MRI), including the adoption of balanced steady-state free precession (b-SSFP) sequences - preferentially in combination with parallel imaging techniques - have led to a significant reduction of imaging time and improved patient safety. The stress protocol includes application of high-dose dobutamine (up to 40 {mu}g/kg/min) combined with fractionated atropine (up to a maximal dose of 1.0 mg). High-dose dobutamine stress MRI revealed good sensitivity (83-96%) and specificity (80-100%) for detection of significant CAD. Myocardial tagging methods have been shown to further increase sensitivity for CAD detection. Severe complications (sustained tachycardia, ventricular fibrillation, myocardial infarction, cardiogenic shock) are rare but may be expected in 0.1-0.3% of patients. Dobutamine stress MRI has emerged as a reliable and safe clinical alternative for noninvasive assessment of CAD. New pulse sequences, such as real-time imaging, might obviate the need for breath holding and electrocardiogram (ECG) triggering in patients with severe dyspnoea and cardiac arrhythmias, which may further improve the clinical impact and acceptance of stress MRI in the future. (orig.)

  12. Serial measurements of high-sensitivity cardiac troponin T after exercise stress test in stable coronary artery disease

    DEFF Research Database (Denmark)

    Axelsson, Anna; Ruwald, Martin Huth; Dalsgaard, Morten;

    2013-01-01

    The aim was to assess serial measurements of high-sensitivity cardiac troponin T (hs-cTNT) post-exercise in patients with stable coronary artery disease (CAD).......The aim was to assess serial measurements of high-sensitivity cardiac troponin T (hs-cTNT) post-exercise in patients with stable coronary artery disease (CAD)....

  13. Baseline Systolic Blood Pressure Response to Exercise Stress Test Can Predict Exercise Indices following Cardiac Rehabilitation Program

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    Akram Sardari

    2010-11-01

    Full Text Available Background: Systolic blood pressure recovery (rSBP is of prognostic value for predicting the survival and co-morbidity rate in patients with coronary artery disease (CAD. This study investigated the association between rSBP and exercise indices after complete cardiac rehabilitation program (CR in a population-based sample of patients undergoing coronary artery bypass grafting (CABG.Methods: The sample population consisted of 352 patients who underwent pure CABG. The patients underwent standard symptom-limited exercise testing immediately before and also after the completion of the CR sessions. rSBP was defined as the ratio of the systolic blood pressure at 3 minutes in recovery to the systolic blood pressure at peak exercise.Results: An abnormal baseline rSBP after exercise was a strong predictor of exercise parameters in the last session, including metabolic equivalents (β = -0.617, SE = 0.127, p value < 0.001 and peak O2 consumption (β = -1.950, SE = 0.363, p value < 0.001 measured in the last session adjusted for baseline exercise characteristics, demographics, function class, and left ventricular ejection fraction.Conclusion: The current study strongly emphasizes the predictive role of baseline rSBP after exercise in evaluating exercise parameters following CR. This baseline index can predict abnormal METs value, peak O2 consumption, post-exercise heart rate, and heart rate recovery after a 24-session CR program.

  14. Cardiopulmonary stress testing using ambulatory radionuclide monitoring system: The relationship between vascular endothelial function and cardiac response in patients with ischemic heart disease

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    Akima, Takashi; Tabata, Hirotsugu [Self-Defense Forces Central Hospital, Tokyo (Japan); Takase, Bonpei [National Defense Medical Coll., Tokorozawa, Saitama (Japan)] [and others

    2002-02-01

    The relationship in the title was studied with a new type ambulatory radionuclide monitoring system. Subjects were 12 male patients with ischemic heart diseases. After cardiac scintigraphy at rest of {sup 99m}Tc-human serum albumin (740 MBq) with GE Mirenium, patients wore the C-VEST jacket (Capintec medset cardiolight), which consisted from 2 radioactivity detectors and Holter ECG recorder, and underwent the cardiopulmonary stress testing with Treadmill Ramp exercise to evaluate the anaerobic threshold (AT), VO{sub 2}, left ventricular ejection flow (EF) and stroke volume (SV). Vascular endothelial function was recorded by ultrasonography of brachial artery by monitoring the flow-mediated dilation (FD). Mean EF at rest was 56% and there was no relationship between VO{sub 2} at rest or exercise and FD. However, the relationship between FD and change of SV or EF from rest to AT was recognized and thus FD was suggested to participate in cardiac function change at exercise of those patients. (K.H.)

  15. A single exposure to diesel exhaust increases the risk of triggered cardiac arrhythmias in conscious rats during dobutamine cardiac "stress" test.

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    Mild-to-moderate exercise is often used to stress the cardiovascular (CV) system of patients while monitoring them for electrocardiogram (ECG) abnormalities that may indicate underlying CV disease. We previously used dobutamine, which increases heart rate (HR) and contractility, ...

  16. Effect of Thermal Stress on Cardiac Function

    OpenAIRE

    Wilson, Thad E.; Crandall, Craig G.

    2011-01-01

    Whole-body heating decreases pulmonary capillary wedge pressure and cerebral vascular conductance, and causes an inotropic shift in the Frank-Starling curve. Whole-body cooling increases pulmonary capillary wedge pressure and cerebral vascular conductance without changing systolic function. These and other data indicate factors affecting cardiac function may mechanistically contribute to syncope during heat stress and improvements in orthostatic tolerance during cold stress.

  17. Dobutamine cardiac "stress" test reveals increased arrhythmia risk in conscious rats after a single exposure to acrolein

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    Mild-to-moderate exercise is often used to stress the cardiovascular (CV) system of patients while monitoring them for electrocardiogram (ECG) abnormalities that may indicate underlying CV disease. We previously demonstrated that dobutamine, which increases heart rate (HR) and co...

  18. Phospholemman: a novel cardiac stress protein.

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    Cheung, Joseph Y; Zhang, Xue-Qian; Song, Jianliang; Gao, Erhe; Rabinowitz, Joseph E; Chan, Tung O; Wang, Jufang

    2010-08-01

    Phospholemman (PLM), a member of the FXYD family of regulators of ion transport, is a major sarcolemmal substrate for protein kinases A and C in cardiac and skeletal muscle. In the heart, PLM co-localizes and co-immunoprecipitates with Na(+)-K(+)-ATPase, Na(+)/Ca(2+) exchanger, and L-type Ca(2+) channel. Functionally, when phosphorylated at serine(68), PLM stimulates Na(+)-K(+)-ATPase but inhibits Na(+)/Ca(2+) exchanger in cardiac myocytes. In heterologous expression systems, PLM modulates the gating of cardiac L-type Ca(2+) channel. Therefore, PLM occupies a key modulatory role in intracellular Na(+) and Ca(2+) homeostasis and is intimately involved in regulation of excitation-contraction (EC) coupling. Genetic ablation of PLM results in a slight increase in baseline cardiac contractility and prolongation of action potential duration. When hearts are subjected to catecholamine stress, PLM minimizes the risks of arrhythmogenesis by reducing Na(+) overload and simultaneously preserves inotropy by inhibiting Na(+)/Ca(2+) exchanger. In heart failure, both expression and phosphorylation state of PLM are altered and may partly account for abnormalities in EC coupling. The unique role of PLM in regulation of Na(+)-K(+)-ATPase, Na(+)/Ca(2+) exchanger, and potentially L-type Ca(2+) channel in the heart, together with the changes in its expression and phosphorylation in heart failure, make PLM a rational and novel target for development of drugs in our armamentarium against heart failure. Clin Trans Sci 2010; Volume 3: 189-196.

  19. The value of cardiac genetic testing.

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    Ingles, Jodie; Semsarian, Christopher

    2014-08-01

    Genetic testing is an important and necessary aspect of the management of families with cardiac genetic conditions. Commercial genetic tests are available for most cardiac genetic diseases, and increasing uptake amongst patients has contributed to a vastly improved knowledge of the genetic basis of these diseases. The incredible advances in genetic technologies have translated to faster, more comprehensive, and inexpensive commercial genetic tests and has completely changed the landscape of commercial genetic testing in recent years. While there are enormous challenges, mostly relating to interpretation of variants, the value of a genetic diagnosis should not be underestimated. In almost all cases, the single greatest utility is for the predictive genetic testing of family members. This review will describe the value of cardiac genetic testing in the current climate of rapid genetic advancements.

  20. Pregnancy as a cardiac stress model

    OpenAIRE

    2014-01-01

    Cardiac hypertrophy occurs during pregnancy as a consequence of both volume overload and hormonal changes. Both pregnancy- and exercise-induced cardiac hypertrophy are generally thought to be similar and physiological. Despite the fact that there are shared transcriptional responses in both forms of cardiac adaptation, pregnancy results in a distinct signature of gene expression in the heart. In some cases, however, pregnancy can induce adverse cardiac events in previously healthy women witho...

  1. Pregnancy as a cardiac stress model.

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    Chung, Eunhee; Leinwand, Leslie A

    2014-03-15

    Cardiac hypertrophy occurs during pregnancy as a consequence of both volume overload and hormonal changes. Both pregnancy- and exercise-induced cardiac hypertrophy are generally thought to be similar and physiological. Despite the fact that there are shared transcriptional responses in both forms of cardiac adaptation, pregnancy results in a distinct signature of gene expression in the heart. In some cases, however, pregnancy can induce adverse cardiac events in previously healthy women without any known cardiovascular disease. Peripartum cardiomyopathy is the leading cause of non-obstetric mortality during pregnancy. To understand how pregnancy can cause heart disease, it is first important to understand cardiac adaptation during normal pregnancy. This review provides an overview of the cardiac consequences of pregnancy, including haemodynamic, functional, structural, and morphological adaptations, as well as molecular phenotypes. In addition, this review describes the signalling pathways responsible for pregnancy-induced cardiac hypertrophy and angiogenesis. We also compare and contrast cardiac adaptation in response to disease, exercise, and pregnancy. The comparisons of these settings of cardiac hypertrophy provide insight into pregnancy-associated cardiac adaptation.

  2. What Is Stress Testing?

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    ... from exercising long enough (for example, lung disease, anemia , or poor general fitness). Doctors also may use stress testing to assess other problems, ... INDEX ACCESSIBILITY PRIVACY STATEMENT FOIA NO FEAR ACT OIG ...

  3. Apathy and Cognitive Test Performance in Patients Undergoing Cardiac Testing

    Directory of Open Access Journals (Sweden)

    Lynn Reese Kakos

    2013-01-01

    Full Text Available Background. Psychiatric comorbidity is common in patients with cardiovascular disease, with the literature indicating that this population may be at risk for apathy. The current study examined the prevalence of apathy in patients with cardiovascular disease and its relation to aspects of cognitive function. Methods. 123 participants from an outpatient cardiology clinic completed a brief neuropsychological battery, a cardiac stress test, and demographic information, medical history, and depression symptomatology self-report measures. Participants also completed the Apathy Evaluation Scale to quantify apathy. Results. These subjects reported limited levels of apathy and depression. Increased depressive symptomatology, history of heart attack, and metabolic equivalents were significantly correlated with apathy (P<0.05. Partial correlations adjusting for these factors revealed significant correlations between behavioral apathy and a measure of executive function and the other apathy subscale with a measure of attention. Conclusion. Findings revealed that apathy was not prevalent in this sample though associated with medical variables. Apathy was largely unrelated to cognitive function. This pattern may be a result of the mild levels of cardiovascular disease and cognitive dysfunction in the current sample. Future studies in samples with severe cardiovascular disease or neuropsychological impairment may provide insight into these associations.

  4. Modelflow underestimates cardiac output in heat-stressed individuals

    DEFF Research Database (Denmark)

    Shibasaki, Manabu; Wilson, Thad E; Bundgaard-Nielsen, Morten

    2011-01-01

    An estimation of cardiac output can be obtained from arterial pressure waveforms using the Modelflow method. However, whether the assumptions associated with Modelflow calculations are accurate during whole body heating is unknown. This project tested the hypothesis that cardiac output obtained v...

  5. Complexity of cardiac signals for predicting changes in alpha-waves after stress in patients undergoing cardiac catheterization

    Science.gov (United States)

    Chiu, Hung-Chih; Lin, Yen-Hung; Lo, Men-Tzung; Tang, Sung-Chun; Wang, Tzung-Dau; Lu, Hung-Chun; Ho, Yi-Lwun; Ma, Hsi-Pin; Peng, Chung-Kang

    2015-08-01

    The hierarchical interaction between electrical signals of the brain and heart is not fully understood. We hypothesized that the complexity of cardiac electrical activity can be used to predict changes in encephalic electricity after stress. Most methods for analyzing the interaction between the heart rate variability (HRV) and electroencephalography (EEG) require a computation-intensive mathematical model. To overcome these limitations and increase the predictive accuracy of human relaxing states, we developed a method to test our hypothesis. In addition to routine linear analysis, multiscale entropy and detrended fluctuation analysis of the HRV were used to quantify nonstationary and nonlinear dynamic changes in the heart rate time series. Short-time Fourier transform was applied to quantify the power of EEG. The clinical, HRV, and EEG parameters of postcatheterization EEG alpha waves were analyzed using change-score analysis and generalized additive models. In conclusion, the complexity of cardiac electrical signals can be used to predict EEG changes after stress.

  6. Takotsubo cardiomyopathy is an acute cardiac syndrome induced by stress

    DEFF Research Database (Denmark)

    Fuchs, Annette Maria; Bang, Lia E; Holmvang, Lene;

    2016-01-01

    Takotsubo cardiomyopathy (TTC) is an acute cardiac syndrome, characterized by transient left ventricular dysfunction often following a stressful event in post-menopausal women. Symptoms are indistinguishable from myocardial infarction. However, TTC patients do not have a culprit lesion on acute...

  7. Comparison of Depression, Anxiety, and Stress Between Mild and Severe Non-cardiac Chest Pain

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    Bahremand

    2016-05-01

    Full Text Available Background Physical and psychological factors affect one another in patients presenting with non-cardiac chest pain. Studying the psychological components of these patients may improve their treatment process. Objectives To compare depression, anxiety, and stress severity between mild and severe chest pain in patients with non-cardiac chest pain. Patients and Methods A cross-sectional design was used. The statistical population comprised patients with non-cardiac chest pain admitted to the Heart Emergency Center in Kermanshah, Iran. Using a matching method, 94 participants with mild and severe non-cardiac chest pain were selected and studied in two groups of 47. The instruments used in this study include the Comorbidity Index, the brief pain index (BPI, and the depression, anxiety, and stress scale (DASS. The multivariate analysis of variance, chi-squared test, and t-test were used for data analysis. Results After adjusting for the effects of age and comorbid conditions, results showed that there was a significant difference between the two groups in terms of depression, anxiety, and stress; the severity of these variables was exacerbated in patients with severe chest pain (P < 0.001. Conclusions Depression, anxiety, and stress are common psychological components in patients with non-cardiac chest pain especially those with severe chest pain and it is essential that health professionals pay attention to these factors. Therefore, paying attention to psychological factors could help experts to choose solutions that will decrease pain and side effects of the diseases. It may also facilitate treatment procedures among patients in severe pain. Further investigation to determine the association between these variables and non-cardiac chest pain should be considered.

  8. AVE 0991 attenuates cardiac hypertrophy through reducing oxidative stress.

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    Ma, Yuedong; Huang, Huiling; Jiang, Jingzhou; Wu, Lingling; Lin, Chunxi; Tang, Anli; Dai, Gang; He, Jiangui; Chen, Yili

    2016-06-10

    AVE 0991, the nonpeptide angiotensin-(1-7) (Ang-(1-7)) analog, is recognized as having beneficial cardiovascular effects. However, the mechanisms have not been fully elucidated. This study was designed to investigate the effects of AVE 0991 on cardiac hypertrophy and the mechanisms involved. Mice were underwent aortic banding to induce cardiac hypertrophy followed by the administration of AVE 0991 (20 mg kg·day (-1)) for 4 weeks. It was shown that AVE 0991 reduced left ventricular hypertrophy and improved heart function, characterized by decreases in left ventricular weight and left ventricular end-diastolic diameter, and increases in ejection fraction. Moreover, AVE 0991 significantly down-regulated mean myocyte diameter and attenuate the gene expression of the hypertrophic markers. Furthermore, AVE 0991 inhibited the expression of NOX 2 and NOX 4, meaning that AVE 0991 reduced oxidative stress of cardiac hypertrophy mice. Our data showed that AVE 0991 treatment could attenuate cardiac hypertrophy and improve heart function, which may be due to reduce oxidative stress.

  9. Exercise stress testing in clinical practice

    Directory of Open Access Journals (Sweden)

    Francesco Giallauria

    2011-07-01

    Full Text Available Exercise stress testing is an important diagnostic tool for evaluating patient’s cardiovascular performance. The present review describes the accuracy and the value of exercise stress testing in different settings: after an acute coronary event, after percutaneous coronary intervention or coronary artery bypass graft; in patients risk assessment before non-cardiac surgery; in diabetic population; in patients with baseline electrocardiographic abnormalities. Moreover, this review provides insights relating to test accuracy in women and geriatric patients. Finally, this review explores new variables/parameters (dyspnea, chronotropic incompentence, heart rate recovery, functional capacity, integrated scores that in the last few years added an incremental value to conventional analysis of exercise-induced angina or electrocardiographic changes.

  10. Effect of heat stress on cardiac output and systemic vascular conductance during simulated hemorrhage to presyncope in young men

    DEFF Research Database (Denmark)

    Ganio, Matthew S; Overgaard, Morten; Seifert, Thomas;

    2012-01-01

    During moderate actual or simulated hemorrhage, as cardiac output decreases, reductions in systemic vascular conductance (SVC) maintain mean arterial pressure (MAP). Heat stress, however, compromises the control of MAP during simulated hemorrhage, and it remains unknown whether this response is due...... to a persistently high SVC and/or a low cardiac output. This study tested the hypothesis that an inadequate decrease in SVC is the primary contributing mechanism by which heat stress compromises blood pressure control during simulated hemorrhage. Simulated hemorrhage was imposed via lower body negative pressure...... (LBNP) to presyncope in 11 passively heat-stressed subjects (increase core temperature: 1.2 ± 0.2°C; means ± SD). Cardiac output was measured via thermodilution, and SVC was calculated while subjects were normothermic, heat stressed, and throughout subsequent LBNP. MAP was not changed by heat stress...

  11. Effects of Caloric Restriction on Cardiac Oxidative Stress and Mitochondrial Bioenergetics: Potential Role of Cardiac Sirtuins

    Directory of Open Access Journals (Sweden)

    Ken Shinmura

    2013-01-01

    Full Text Available The biology of aging has not been fully clarified, but the free radical theory of aging is one of the strongest aging theories proposed to date. The free radical theory has been expanded to the oxidative stress theory, in which mitochondria play a central role in the development of the aging process because of their critical roles in bioenergetics, oxidant production, and regulation of cell death. A decline in cardiac mitochondrial function associated with the accumulation of oxidative damage might be responsible, at least in part, for the decline in cardiac performance with age. In contrast, lifelong caloric restriction can attenuate functional decline with age, delay the onset of morbidity, and extend lifespan in various species. The effect of caloric restriction appears to be related to a reduction in cellular damage induced by reactive oxygen species. There is increasing evidence that sirtuins play an essential role in the reduction of mitochondrial oxidative stress during caloric restriction. We speculate that cardiac sirtuins attenuate the accumulation of oxidative damage associated with age by modifying specific mitochondrial proteins posttranscriptionally. Therefore, the distinct role of each sirtuin in the heart subjected to caloric restriction should be clarified to translate sirtuin biology into clinical practice.

  12. Credibility and Crisis Stress Testing

    Directory of Open Access Journals (Sweden)

    Li Lian Ong

    2014-02-01

    Full Text Available Credibility is the bedrock of any crisis stress test. The use of stress tests to manage systemic risk was introduced by the U.S. authorities in 2009 in the form of the Supervisory Capital Assessment Program. Since then, supervisory authorities in other jurisdictions have also conducted similar exercises. In some of those cases, the design and implementation of certain elements of the framework have been criticized for their lack of credibility. This paper proposes a set of guidelines for constructing an effective crisis stress test. It combines financial markets impact studies of previous exercises with relevant case study information gleaned from those experiences to identify the key elements and to formulate their appropriate design. Pertinent concepts, issues and nuances particular to crisis stress testing are also discussed. The findings may be useful for country authorities seeking to include stress tests in their crisis management arsenal, as well as for the design of crisis programs.

  13. Exercise stress test

    Science.gov (United States)

    ... Heart disease - treadmill References Balady GJ, Morise AP. Exercise testing. In: Mann DL, Zipes DP, Libby P, Bonow RO, Braunwald E, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine . 10th ed. Philadelphia, PA: Elsevier Saunders; 2015: ...

  14. Testing the stress shadow hypothesis

    Science.gov (United States)

    Felzer, Karen R.; Brodsky, Emily E.

    2005-05-01

    A fundamental question in earthquake physics is whether aftershocks are predominantly triggered by static stress changes (permanent stress changes associated with fault displacement) or dynamic stresses (temporary stress changes associated with earthquake shaking). Both classes of models provide plausible explanations for earthquake triggering of aftershocks, but only the static stress model predicts stress shadows, or regions in which activity is decreased by a nearby earthquake. To test for whether a main shock has produced a stress shadow, we calculate time ratios, defined as the ratio of the time between the main shock and the first earthquake to follow it and the time between the last earthquake to precede the main shock and the first earthquake to follow it. A single value of the time ratio is calculated for each 10 × 10 km bin within 1.5 fault lengths of the main shock epicenter. Large values of the time ratio indicate a long wait for the first earthquake to follow the main shock and thus a potential stress shadow, whereas small values indicate the presence of aftershocks. Simulations indicate that the time ratio test should have sufficient sensitivity to detect stress shadows if they are produced in accordance with the rate and state friction model. We evaluate the 1989 MW 7.0 Loma Prieta, 1992 MW 7.3 Landers, 1994 MW 6.7 Northridge, and 1999 MW 7.1 Hector Mine main shocks. For each main shock, there is a pronounced concentration of small time ratios, indicating the presence of aftershocks, but the number of large time ratios is less than at other times in the catalog. This suggests that stress shadows are not present. By comparing our results to simulations we estimate that we can be at least 98% confident that the Loma Prieta and Landers main shocks did not produce stress shadows and 91% and 84% confident that stress shadows were not generated by the Hector Mine and Northridge main shocks, respectively. We also investigate the long hypothesized existence

  15. The economics of cardiac biomarker testing in suspected myocardial infarction.

    Science.gov (United States)

    Goodacre, Steve; Thokala, Praveen

    2015-03-01

    Suspected myocardial infarction (MI) is a common reason for emergency hospital attendance and admission. Cardiac biomarker measurement is an essential element of diagnostic assessment of suspected MI. Although the cost of a routinely available biomarker may be small, the large patient population and consequences in terms of hospital admission and investigation mean that the economic impact of cardiac biomarker testing is substantial. Economic evaluation involves comparing the estimated costs and effectiveness (outcomes) of two or more interventions or care alternatives. This process creates some difficulties with respect to cardiac biomarkers. Estimating the effectiveness of cardiac biomarkers involves identifying how they help to improve health and how we can measure this improvement. Comparison to an appropriate alternative is also problematic. New biomarkers may be promoted on the basis of reducing hospital admission or length of stay, but hospital admission for low risk patients may incur significant costs while providing very little benefit, making it an inappropriate comparator. Finally, economic evaluation may conclude that a more sensitive biomarker strategy is more effective but, by detecting and treating more cases, is also more expensive. In these circumstances it is unclear whether we should use the more effective or the cheaper option. This article provides an introduction to health economics and addresses the specific issues relevant to cardiac biomarkers. It describes the key concepts relevant to economic evaluation of cardiac biomarkers in suspected MI and highlights key areas of uncertainty and controversy.

  16. Heart rate complexity: A novel approach to assessing cardiac stress reactivity.

    Science.gov (United States)

    Brindle, Ryan C; Ginty, Annie T; Phillips, Anna C; Fisher, James P; McIntyre, David; Carroll, Douglas

    2016-04-01

    Correlation dimension (D2), a measure of heart rate (HR) complexity, has been shown to decrease in response to acute mental stress and relate to adverse cardiovascular health. However, the relationship between stress-induced changes in D2 and HR has yet to be established. The present studies aimed to assess this relationship systematically while controlling for changes in respiration and autonomic activity. In Study 1 (N = 25) D2 decreased during stress and predicted HR reactivity even after adjusting for changes in respiration rate, and cardiac vagal tone. This result was replicated in Study 2 (N = 162) and extended by including a measure of cardiac sympathetic activity; correlation dimension remained an independent predictor of HR reactivity in a hierarchical linear model containing measures of cardiac parasympathetic and sympathetic activity and their interaction. These results suggest that correlation dimension may provide additional information regarding cardiac stress reactivity above that provided by traditional measures of cardiac autonomic function.

  17. Are Cardiac Autonomic Nervous System Activity and Perceived Stress Related to Functional Somatic Symptoms in Adolescents? The TRAILS Study.

    Directory of Open Access Journals (Sweden)

    Karin A M Janssens

    Full Text Available Stressors have been related to medically insufficiently explained or functional somatic symptoms (FSS. However, the underlying mechanism of this association is largely unclear. In the current study, we examined whether FSS are associated with different perceived stress and cardiac autonomic nervous system (ANS levels during a standardized stressful situation, and whether these associations are symptom-specific.We examined 715 adolescents (16.1 years, 51.3% girls from the Dutch cohort study Tracking Adolescents' Individual Lives Sample during the Groningen Social Stress Test (GSST. FSS were assessed by the Youth Self-Report, and clustered into a cluster of overtiredness, dizziness and musculoskeletal pain and a cluster of headache and gastrointestinal symptoms. Perceived stress levels (i.e. unpleasantness and arousal were assessed by the Self-Assessment Manikin, and cardiac ANS activity by assessing heart rate variability (HRV-HF and pre-ejection period (PEP. Perceived stress and cardiac ANS levels before, during, and after the GSST were studied as well as cardiac ANS reactivity. Linear regression analyses were used to examine the associations.Perceived arousal levels during (beta = 0.09, p = 0.04 and after (beta = 0.07, p = 0.047 the GSST, and perceived unpleasantness levels before (beta = 0.07, p = 0.048 and during (beta = 0.12, p = 0.001 the GSST were related to FSS during the past couple of months. The association between perceived stress and FSS was stronger for the FSS cluster of overtiredness, dizziness and musculoskeletal pain than for the cluster of headache and gastrointestinal symptoms. Neither ANS activity levels before, during, and after the GSST, nor maximal HF-HRV and PEP reactivity were related to FSS.This study suggests that perceived stress levels during social stress are related to FSS, whereas cardiac ANS activity and reactivity are not related to FSS.

  18. Hidden Risks in Stress Test

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ The Committee of European Banking Supervisors released better-than-expected stress test results on July 23 for 91European banks,whose combined assets account for 65percent of all European banks.About 84 banks passed the stress test and are able to maintain a core capital adequacy ratio of 6 percent.The positive result has pulled together the global stock and currency markets.But Zhang Monan,a researcher at the State Information Center,said the seemingly rallied financial market is unsustainable and that the European banks will encounter prolonged challenges.

  19. Hidden Risks in Stress Test

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The Committee of European Banking Supervisors released better-than-expected stress test results on July 23 for 91 European banks,whose combined assets account for 65 percent of all European banks.About 84 banks passed the stress test and are able to maintain a core capital adequacy ratio of 6 percent.The positive result has pulled togethe the global stock and currency markets.But Zhang Monan, a researcher at the State Information Center,said the seemingly rallied financial market is unsustainable and that the European banks will encounter prolonged challenges. Zhang expressed her concerns in Securities Times. Edited excerpts follow

  20. Qualitative and quantitative Analysis of the Parenting Styles, Coping Strategies and Perceived Stress in Mothers of Children who have undergone Cardiac Interventions

    OpenAIRE

    Naumoska, Ljubica; Dojcinovski, Ilija; Ristovska, Frosina; Saiti, Sait; T.Paunovska, Suzana; Mitrev, Zan

    2012-01-01

    Exploring the parenting styles, coping strategies and perceived stress in parents of children who have undergone cardiac intervention are challenging issues because they affect the whole family dynamics. Ten mothers of children who have undergone cardiac intervention and ten mothers of healthy children, aged 5 to 14 were administered three questionnaires: Parenting styles Questionnaire, Cope and Perceived stress Questionnaire. The testing was conducted at the final day of their five-day summe...

  1. Stress echocardiography in warmblood horses: comparison of dobutamine/atropine with treadmill exercise as cardiac stressors.

    Science.gov (United States)

    Gehlen, Heidrun; Marnette, Silke; Rohn, Karl; Stadler, Peter

    2006-01-01

    The purpose of this study was to determine whether the combination of dobutamine and atropine causes cardiac stress equivalent to treadmill exercise. Therefore, electrocardiography and echocardiography were performed on 10 warmblood horses before, during, and after different cardiac stress tests. Stressors consisted of a standardized treadmill exercise and combined administration of dobutamine (7.5 microg/kg/min) and atropine (5 microg/kg). Maxima heart rates were achieved during the treadmill exercise (175 +/- 10 bpm). After exercise, a rapid decrease in heart rate was observed. Subsequently, a stress echocardiography for which a heart rate >100 bpm was required could only be performed within 1 minute after exercise. The mean heart rate during echocardiography was 136 +/- 8 bpm after exercise. The combination of dobutamine and atropine also resulted in a significant increase in heart rate, up to 141 +/- 20 bpm. Maxima heart rate was significantly higher during the treadmill exercise, but the decrease in heart rate was significantly slower after dobutamine and atropine administration. Over a period of 7.9 minutes, the mean heart rate was 123 +/- 8 bpm during dobutamine and atropine administration. Consequently, the combination of both drugs offered sufficient time for detailed examinations. Overall, echocardiographic examination identified a decrease in left ventricular (LV) dimensions, an increase in LV wall thickness, and a decrease in stroke volume after the treadmill exercise and during pharmacologic stress testing compared with baseline. Changes in echocardiographic variables generally were more pronounced during dobutamine and atropine administration. Similar to stress echocardiography in humans, in horses the combination of dobutamine and atropine is useful to produce an increase in heart rate comparable with what is achieved with exercise but without the need of increasing dobutamine dosage.

  2. The influence of motor activity on the development of cardiac arrhythmias during experimental emotional stress

    Science.gov (United States)

    Ulyaninskiy, L. S.; Urmancheyeva, T. G.; Stepanyan, Y. P.; Fufacheva, A. A.; Gritsak, A. V.; Kuznetsova, B. A.; Kvitka, A. A.

    1982-01-01

    Experimental emotional stress which can produce various disorders of cardiac rhythm: sinus tachycardia, atrial fibrillation, ventricular, extrasystoles and paroxysmal ventricular tachysystoles was studied. In these conditions the adrenalin content in the blood and myocardium is increased 3 to 4 times. It is found that moderate motor activity leads to a relative decrease of adrenalin in the myocardium and arrest of cardiac arrhythmias.

  3. Preliminary evidence that exercise dependence is associated with blunted cardiac and cortisol reactions to acute psychological stress.

    Science.gov (United States)

    Heaney, Jennifer L J; Ginty, Annie T; Carroll, Douglas; Phillips, Anna C

    2011-02-01

    Low or blunted cardiovascular and cortisol reactions to acute psychological stress have been shown to characterise those with a tobacco or alcohol dependency. The present study tested the hypothesis that exercise dependency would be similarly associated with blunted reactivity. Young female exercisers (N=219) were screened by questionnaire for exercise dependence. Ten women with probable exercise dependence and 10 non dependent controls were selected for laboratory stress testing. Cardiovascular activity and salivary cortisol were measured at rest and in response to a 10-min mental arithmetic stress task. The exercise dependent women showed blunted cardiac reactions to the stress task and blunted cortisol at 10, 20, and 30 minute post stress exposure. These effects could not be accounted for in terms of group differences in stress task performance, nor could the cardiac effects be attributed to group differences in cardio-respiratory fitness. It would seem that low stress reactivity is characteristic of a wide range of dependencies, and is not confined to substance dependence. Our results offer further support for the hypothesis that blunted stress reactivity may be a peripheral marker of a central motivational dysregulation.

  4. Cardiac arrhythmias during exercise testing in healthy men.

    Science.gov (United States)

    Beard, E. F.; Owen, C. A.

    1973-01-01

    Clinically healthy male executives who participate in a long-term physical conditioning program have demonstrated cardiac arrhythmia during and after periodic ergometric testing at submaximal and maximal levels. In 1,385 tests on 248 subjects, it was found that 34% of subjects demonstrated an arrhythmia at some time and 13% of subjects developed arrhythmia on more than one test. Premature systoles of ventricular origin were most common, but premature systoles of atrial origin, premature systoles of junctional origin, paroxysmal atrial tachycardia, atrioventricular block, wandering pacemaker, and pre-excitation were also seen. Careful post-test monitoring and pulse rate regulated training sessions are suggested for such programs.

  5. Downstream Procedures and Outcomes After Stress Testing For Suspected Coronary Artery Disease in the United States

    Science.gov (United States)

    Mudrick, Daniel W; Cowper, Patricia A; Shah, Bimal R; Patel, Manesh R; Jensen, Neil C; Drawz, Matthew J; Peterson, Eric D; Douglas, Pamela S

    2013-01-01

    Background Millions of Americans with suspected coronary artery disease undergo non-invasive cardiac stress testing annually. Downstream procedures and subsequent outcomes among symptomatic patients without known coronary disease referred for stress testing are not well characterized in contemporary community practice. Methods We examined administrative insurance billing data from a national insurance provider from November 2004 through June 2007. After excluding patients with prior cardiac disease or chest pain evaluation, we identified 80,676 people age 40–64 years with outpatient cardiac stress testing within 30 days after an office visit for chest pain. We evaluated rates of invasive coronary angiography, coronary revascularization, and cardiovascular events after stress testing. Results Within 60 days, only 8.8% of stress test patients underwent cardiac catheterization and only 2.7% underwent revascularization; within one year only 0.5% suffered death, myocardial infarction, or stroke. There were marked geographic variations in one-year rates of catheterization (3.8–14.8%) and revascularization (1.2–3.0%) across 20 hospital referral regions. Conclusions In this large national cohort of middle-aged patients without previously coded cardiac diagnosis who were referred for stress testing after outpatient chest pain evaluation, few proceeded to invasive angiography or revascularization, and subsequent cardiovascular events were infrequent. PMID:22424017

  6. Cardiac autonomic testing and diagnosing heart disease. 'A clinical perspective'

    Directory of Open Access Journals (Sweden)

    Nicholas L. DePace

    2014-12-01

    Full Text Available Background Coronary heart disease (CHD is a major health concern, affecting nearly half the middle-age population and responsible for nearly one-third of all deaths. Clinicians have responsibilities beyond diagnosing CHD, including risk stratification of patients for major adverse cardiac events (MACE, modifying the risks and treating the patient. In this first of a two-part review, identifying risk factors is reviewed, including more potential benefit from autonomic testing. Methods Traditional and non-traditional, and modifiable and non-modifiable risk factors for MACE where compared, including newer risk factors, such as inflammation, carotid intimal thickening, ankle-brachial index, CT calcium scoring, and autonomic function testing, specifically independent measurement of parasympathetic and sympathetic (P&S activity. Results The Framingham Heart Study, and others, have identified traditional risk factors for the development of CHD. These factors effectively target high-risk patients, but a large number of individuals who will develop CHD and MACE are not identified. Many patients with CHD who appear to be well-managed by traditional therapies still experience MACE. In order to identify these patients, other possible risk factors have been explored. Advanced autonomic dysfunction, and its more severe form, cardiac autonomic neuropathy, have been strongly associated with an elevated risk of cardiac mortality and are diagnosable through P&S testing. Conclusions Independent measures of P&S activity, provides additional information and has the potential to incrementally add to risk assessment. This additional information enables physicians to (1 specifically target more high-risk patients and (2 titrate therapies, with autonomic testing guidance, in order to minimize risk of cardiac mortality and morbidity.

  7. Myocardial perfusion quantification in patients suspected of cardiac syndrome X with positive and negative exercise testing : A [N-13]ammonia positron emission tomography study

    NARCIS (Netherlands)

    de Vries, Jessica; DeJongste, Mike J. L.; Jessurun, Gillian A. J.; Jager, Pieter L.; Staal, Michiel J.; Slart, Riemer H. J. A.

    2006-01-01

    Background The combination of angina pectoris, angiographically normal coronary arteries, and a positive exercise stress test (EST) is referred to as cardiac syndrome X. However, a large group of patients suspected of syndrome X reveals a normal exercise stress test and weakens the diagnosis of synd

  8. 77 FR 3166 - Annual Stress Test

    Science.gov (United States)

    2012-01-23

    ...-AD91 Annual Stress Test AGENCY: Federal Deposit Insurance Corporation. ACTION: Proposed rule with... stress tests (``proposed rule''). This proposed rule would implement section 165(i)(2) by requiring state... of more than $10 billion to conduct annual stress tests in accordance with the proposed rule,...

  9. 77 FR 16484 - Annual Stress Test

    Science.gov (United States)

    2012-03-21

    ... Office of the Comptroller of the Currency 12 CFR Part 46 RIN 1557-AD58 Annual Stress Test AGENCY: Office... with total consolidated assets of more than $10 billion to conduct an annual stress test and comply... consolidated assets in excess of $10 billion to conduct annual stress tests pursuant to regulations...

  10. Combined heart rate variability and dynamic measures for quantitatively characterizing the cardiac stress status during cycling exercise.

    Science.gov (United States)

    Chen, Szi-Wen; Liaw, Jiunn-Woei; Chang, Ya-Ju; Chuang, Li-Ling; Chien, Chun-Tse

    2015-08-01

    In this study, we aimed to seek for different ways of measuring cardiac stress in terms of heart rate variability (HRV) and heart rate (HR) dynamics, and to develop a novel index that can effectively summarize the information reflected by these measures to continuously and quantitatively characterize the cardiac stress status during physical exercise. Standard deviation, spectral measure of HRV as well as a nonlinear detrended fluctuation analysis (DFA) based fractal-like behavior measure of HR dynamics were all evaluated on the RR time series derived from windowed electrocardiogram (ECG) data for the subjects undergoing cycling exercise. We recruited eleven young healthy subjects in our tests. Each subject was asked to maintain a fixed speed under a constant load during the pedaling test. We obtained the running estimates of the standard deviation of the normal-to-normal interval (SDNN), the high-fidelity power spectral density (PSD) of HRV, and the DFA scaling exponent α, respectively. A trend analysis and a multivariate linear regression analysis of these measures were then performed. Numerical experimental results produced by our analyses showed that a decrease in both SDNN and α was seen during the cycling exercise, while there was no significant correlation between the standard lower frequency to higher frequency (LF-to-HF) spectral power ratio of HRV and the exercise intensity. In addition, while the SDNN and α were both negatively correlated with the Borg rating of perceived exertion (RPE) scale value, it seemed that the LF-to-HF power ratio might not have substantial impact on the Borg value, suggesting that the SDNN and α may be further used as features to detect the cardiac stress status during the physical exercise. We further approached this detection problem by applying a linear discriminant analysis (LDA) to both feature candidates for the task of cardiac stress stratification. As a result, a time-varying parameter, referred to as the cardiac

  11. Stress-induced cardiac autonomic reactivity and preclinical atherosclerosis: does arterial elasticity modify the association?

    Science.gov (United States)

    Chumaeva, Nadja; Hintsanen, Mirka; Pulkki-Råback, Laura; Merjonen, Päivi; Elovainio, Marko; Hintsa, Taina; Juonala, Markus; Kähönen, Mika; Raitakari, Olli T; Keltikangas-Järvinen, Liisa

    2015-01-01

    The effect of acute mental stress on atherosclerosis can be estimated using arterial elasticity measured by carotid artery distensibility (Cdist). We examined the interactive effect of acute stress-induced cardiac reactivity and Cdist to preclinical atherosclerosis assessed by carotid intima-media thickness (IMT) in 58 healthy adults aged 24-39 years participated in the epidemiological Young Finns Study. Cdist and IMT were measured ultrasonographically. Impedance electrocardiography was used to measure acute mental stress-induced cardiac autonomic responses: heart rate (HR), respiratory sinus arrhythmia and pre-ejection period after the mental arithmetic and the public speaking tasks. Interactions between HR reactivity and Cdist in relation to preclinical atherosclerosis were found. The results imply that elevated HR reactivity to acute mental stress is related to less atherosclerosis among healthy participants with higher arterial elasticity. Possibly, increased cardiac reactivity in response to challenging tasks is an adaptive reaction related to better cardiovascular health.

  12. Apocynin attenuates oxidative stress and cardiac fibrosis in angiotensin Ⅱ-induced cardiac diastolic dysfunction in mice

    Institute of Scientific and Technical Information of China (English)

    Yu-qiong LI; Xiao-bo LI; Shu-jie GUO; Shao-li CHU; Ping-jin GAO; Ding-liang ZHU; Wen-quan NIU

    2013-01-01

    Aim:To investigate whether apocynin,a NADPH oxidase inhibitor,produced cardioproteictive effects in Ang Ⅱ-induced hypertensive mice,and to elucidate the underlying mechanisms.Methods:C57BL/6 mice were subcutaneously infused Ang Ⅱ for 4 weeks to mimic cardiac remodeling and fibrosis.Concomitantly the mice were administered apocynin (100 mg· kg-1·d-1) or/and the aldosterone receptor blocker eplerenone (200 mg·kg-1d-1) via gavage for 4 weeks.Systolic blood pressure (SBP) and heart rate were measured,and transthoracic echocardiography was performed.For in vitro study,cardiac fibroblasts were treated with Ang Ⅱ (10 7 mol/L) in the presence of apocynin (105 mol/L) or/and eplerenone (105 mol/L).Immunohistochemistry and Western blotting were used to quantify the expression levels of NADPH oxidase and osteopontin (OPN) proteins in the cells.Results:Both apocynin and eplerenone significantly decreased SBP,and markedly improved diastolic dysfunction in Ang Ⅱ-induced hypertensive mice,accompanied with ameliorated oxidative stress and cardiac fibrosis.In the Ang Ⅱ-treated cardiac fibroblasts,the expression levels of NOX4 and OPN proteins were markedly upregulated.Both Apocynin and eplerenone significantly suppressed the increased expression levels of NOX4 and OPN proteins in the Ang Ⅱ-treated cells.In all the experiments,apocynin and eplerenone produced comparable effects.Co-administration of the two agents did not produce synergic effects.Conclusion:Apocynin produces cardioproteictive effects comparable to those of eplerenone.The beneficial effects of apocynin on myocardial oxidative stress and cardiac fibrosis might be mediated partly through a pathway involving NADPH oxidase and OPN.

  13. 21 CFR 862.1163 - Cardiac allograft gene expression profiling test system.

    Science.gov (United States)

    2010-04-01

    ... HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test Systems § 862.1163 Cardiac allograft gene expression profiling test system....

  14. Chronic stress and coping among cardiac surgeons: a single center study

    Directory of Open Access Journals (Sweden)

    Kyriakos Spiliopoulos

    2014-09-01

    Full Text Available Introduction: Cardiac surgeons stress may impair their quality of life and professional practice. Objective: To assess perceived chronic stress and coping strategies among cardiac surgeons. Methods: Twenty-two cardiac surgeons answered two self-assessment questionnaires, the Trier Inventory for Chronic Stress and the German SGV for coping strategies. Results: Participants mean age was 40±14.1 years and 13 were male; eight were senior physicians and 14 were residents. Mean values for the Trier Inventory for Chronic Stress were within the normal range. Unexperienced physicians had significantly higher levels of dissatisfaction at work, lack of social recognition, and isolation (P<0.05. Coping strategies such as play down, distraction from situation, and substitutional satisfaction were also significantly more frequent among unexperienced surgeons. "Negative" stress-coping strategies occur more often in experienced than in younger colleagues (P=0.029. Female surgeons felt more exposed to overwork (P=0.04 and social stress (P=0.03. Conclusion: Cardiac surgeons show a tendency to high perception of chronic stress phenomena and vulnerability for negative coping strategies.

  15. Cardiac autonomic testing and treating heart disease. 'A clinical perspective'

    Directory of Open Access Journals (Sweden)

    Nicholas L. DePace

    2014-12-01

    Full Text Available Background Coronary heart disease (CHD is a major health concern, affecting nearly half the middle-age population and responsible for nearly one-third of all deaths. Clinicians have several major responsibilities beyond diagnosing CHD, such as risk stratification of patients for major adverse cardiac events (MACE and treating risks, as well as the patient. This second of a two-part review series discusses treating risk factors, including autonomic dysfunction, and expected outcomes. Methods Therapies for treating cardiac mortality risks including cardiovascular autonomic neuropathy (CAN, are discussed. Results While risk factors effectively target high-risk patients, a large number of individuals who will develop complications from heart disease are not identified by current scoring systems. Many patients with heart conditions, who appear to be well-managed by traditional therapies, experience MACE. Parasympathetic and Sympathetic (P&S function testing provides more information and has the potential to further aid doctors in individualizing and titrating therapy to minimize risk. Advanced autonomic dysfunction (AAD and its more severe form cardiovascular autonomic neuropathy have been strongly associated with an elevated risk of cardiac mortality and are diagnosable through autonomic testing. This additional information includes patient-specific physiologic measures, such as sympathovagal balance (SB. Studies have shown that establishing and maintaining proper SB minimizes morbidity and mortality risk. Conclusions P&S testing promotes primary prevention, treating subclinical disease states, as well as secondary prevention, thereby improving patient outcomes through (1 maintaining wellness, (2 preventing symptoms and disorder and (3 treating subclinical manifestations (autonomic dysfunction, as well as (4 disease and symptoms (autonomic neuropathy.

  16. Hearts of dystonia musculorum mice display normal morphological and histological features but show signs of cardiac stress.

    Directory of Open Access Journals (Sweden)

    Justin G Boyer

    Full Text Available Dystonin is a giant cytoskeletal protein belonging to the plakin protein family and is believed to crosslink the major filament systems in contractile cells. Previous work has demonstrated skeletal muscle defects in dystonin-deficient dystonia musculorum (dt mice. In this study, we show that the dystonin muscle isoform is localized at the Z-disc, the H zone, the sarcolemma and intercalated discs in cardiac tissue. Based on this localization pattern, we tested whether dystonin-deficiency leads to structural defects in cardiac muscle. Desmin intermediate filament, microfilament, and microtubule subcellular organization appeared normal in dt hearts. Nevertheless, increased transcript levels of atrial natriuretic factor (ANF, 66% beta-myosin heavy chain (beta-MHC, 95% and decreased levels of sarcoplasmic reticulum calcium pump isoform 2A (SERCA2a, 26%, all signs of cardiac muscle stress, were noted in dt hearts. Hearts from two-week old dt mice were assessed for the presence of morphological and histological alterations. Heart to body weight ratios as well as left ventricular wall thickness and left chamber volume measurements were similar between dt and wild-type control mice. Hearts from dt mice also displayed no signs of fibrosis or calcification. Taken together, our data provide new insights into the intricate structure of the sarcomere by situating dystonin in cardiac muscle fibers and suggest that dystonin does not significantly influence the structural organization of cardiac muscle fibers during early postnatal development.

  17. Secoisolariciresinol diglucoside abrogates oxidative stress-induced damage in cardiac iron overload condition.

    Directory of Open Access Journals (Sweden)

    Stephanie Puukila

    Full Text Available Cardiac iron overload is directly associated with cardiac dysfunction and can ultimately lead to heart failure. This study examined the effect of secoisolariciresinol diglucoside (SDG, a component of flaxseed, on iron overload induced cardiac damage by evaluating oxidative stress, inflammation and apoptosis in H9c2 cardiomyocytes. Cells were incubated with 50 μ5M iron for 24 hours and/or a 24 hour pre-treatment of 500 μ M SDG. Cardiac iron overload resulted in increased oxidative stress and gene expression of the inflammatory mediators tumor necrosis factor-α, interleukin-10 and interferon γ, as well as matrix metalloproteinases-2 and -9. Increased apoptosis was evident by increased active caspase 3/7 activity and increased protein expression of Forkhead box O3a, caspase 3 and Bax. Cardiac iron overload also resulted in increased protein expression of p70S6 Kinase 1 and decreased expression of AMP-activated protein kinase. Pre-treatment with SDG abrogated the iron-induced increases in oxidative stress, inflammation and apoptosis, as well as the increased p70S6 Kinase 1 and decreased AMP-activated protein kinase expression. The decrease in superoxide dismutase activity by iron treatment was prevented by pre-treatment with SDG in the presence of iron. Based on these findings we conclude that SDG was cytoprotective in an in vitro model of iron overload induced redox-inflammatory damage, suggesting a novel potential role for SDG in cardiac iron overload.

  18. Stress Testing of Data-Communication Networks

    Science.gov (United States)

    Leucht, Kurt; Bedette, Guy

    2006-01-01

    NetStress is a computer program that stress-tests a data-communication network and components thereof. NetStress comprises two components running, respectively, in a transmitting system and a receiving system connected to a network under test

  19. Guidelines for genetic testing of inherited cardiac disorders.

    Science.gov (United States)

    Ingles, Jodie; Zodgekar, Poonam R; Yeates, Laura; Macciocca, Ivan; Semsarian, Christopher; Fatkin, Diane

    2011-11-01

    Inherited gene variants have been implicated increasingly in cardiac disorders but the clinical impact of these discoveries has been variable. For some disorders, such as familial hypertrophic cardiomyopathy, long QT syndrome, and familial hypercholesterolaemia, genetic testing has a high yield and has become an integral part of family management. For other disorders, including dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, and atrial fibrillation, relatively less is known about the genes involved and genetic testing has a lower yield. Recent advances in sequencing and array-based technologies promise to change the landscape of our understanding of the genetic basis of human disease and will dramatically increase the rate of detection of genomic variants. Since every individual is expected to harbour thousands of variants, many of which may be novel, interpretation of the functional significance of any single variant is critical, and should be undertaken by experienced personnel. Genotype results can have a wide range of medical and psychosocial implications for affected and unaffected individuals and hence, genetic testing should be performed in a specialised cardiac genetic clinic or clinical genetics service where appropriate family management and genetic counselling can be offered.

  20. Perceived stress as a risk factor for changes in health behaviour and cardiac risk profile

    DEFF Research Database (Denmark)

    Rod, Naja Hulvej; Grønbaek, M; Schnohr, P;

    2009-01-01

    in health behaviour (smoking, physical activity, alcohol consumption, overweight) and cardiac risk profile (cholesterol, HDL cholesterol, blood pressure, diabetes). RESULTS: Individuals with high levels of stress compared to those with low levels of stress were less likely to quit smoking (OR = 0.58; 95% CI......OBJECTIVE: The aim of this study was to evaluate the long-term effects of stress on changes in health behaviour and cardiac risk profile in men and women. DESIGN: A prospective cohort study. SETTING: The Copenhagen City Heart Study, Denmark. SUBJECTS: The analyses were based on 7066 women and men...... to use antihypertensive medication (1.94; 1.63-2.30), and stressed men were more than two times as likely to develop diabetes during follow-up (2.36; 1.22-4.59). CONCLUSION: This longitudinal study supports a causal relation between stress and cardiovascular diseases mediated through unfavourable changes...

  1. Kaempferol Attenuates Cardiac Hypertrophy via Regulation of ASK1/MAPK Signaling Pathway and Oxidative Stress.

    Science.gov (United States)

    Feng, Hong; Cao, Jianlei; Zhang, Guangyu; Wang, Yanggan

    2017-02-20

    Kaempferol has been demonstrated to provide benefits for the treatment of atherosclerosis, coronary heart disease, hyperlipidemia, and diabetes through its antioxidant and anti-inflammatory properties. However, its role in cardiac hypertrophy remains to be elucidated. The aim of our study was to investigate the effects of kaempferol on cardiac hypertrophy and the underlying mechanism. Mice subjected to aorta banding were treated with or without kaempferol (100 mg/kg/d, p. o.) for 6 weeks. Echocardiography was performed to evaluate cardiac function. Mice hearts were collected for pathological observation and molecular mechanism investigation. H9c2 cardiomyocytes were stimulated with or without phenylephrine for in vitro study. Kaempferol significantly attenuated cardiac hypertrophy induced by aorta banding as evidenced by decreased cardiomyocyte areas and interstitial fibrosis, accompanied with improved cardiac functions and decreased apoptosis. The ASK1/MAPK signaling pathways (JNK1/2 and p38) were markedly activated in the aorta banding mouse heart but inhibited by kaempferol treatment. In in vitro experiments, kaempferol also inhibited the activity of ASK1/JNK1/2/p38 signaling pathway and the enlargement of H9c2 cardiomyocytes. Furthermore, our study revealed that kaempferol could protect the mouse heart and H9c2 cells from pathological oxidative stress. Our investigation indicated that treatment with kaempferol protects against cardiac hypertrophy, and its cardioprotection may be partially explained by the inhibition of the ASK1/MAPK signaling pathway and the regulation of oxidative stress.

  2. Cardiac troponin testing in idiopathic inflammatory myopathies and systemic sclerosis-spectrum disorders: biomarkers to distinguish between primary cardiac involvement and low-grade skeletal muscle disease activity.

    Science.gov (United States)

    Hughes, Michael; Lilleker, James B; Herrick, Ariane L; Chinoy, Hector

    2015-05-01

    Primary cardiac involvement, an under-recognised manifestation of the idiopathic inflammatory myopathies (IIM) and systemic sclerosis (SSc)-spectrum disorders, is associated with significant mortality. Within these two conditions, traditional skeletal muscle enzyme testing may not effectively distinguish between skeletal and cardiac muscle involvement, especially in patients with subclinical cardiac disease. Accurate biomarkers are thus required to screen for cardiac disease, to better inform both therapeutic decision-making and treatment response. The widespread uptake of cardiac troponin testing has revolutionised the management of acute coronary syndromes. While cardiac troponin I (cTnI) appears specific to the myocardium, cardiac troponin T (cTnT) is also expressed by skeletal muscle, including regenerating skeletal muscle tissue. There is increasing interest about the role of cardiac troponins as a putative biomarker of primary cardiac involvement in IIM and SSc-spectrum disorders. Herewith we discuss subclinical cardiac disease in IIM and SSc-spectrum disorders, the respective roles of cTnI and cTnT testing, and the re-expression of cTnT within regenerating skeletal muscle tissue. There remains wide variation in access to cardiac troponin testing nationally and internationally. We propose two pragmatic clinical pathways using cardiac troponins, preferably measuring concomitant cTnT followed by confirmatory (cardiac) cTnI to screen patients for subclinical cardiac disease and/or low-grade skeletal muscle disease activity, and also an agenda for future research.

  3. Salubrinal Alleviates Pressure Overload-Induced Cardiac Hypertrophy by Inhibiting Endoplasmic Reticulum Stress Pathway

    Science.gov (United States)

    Rani, Shilpa; Sreenivasaiah, Pradeep Kumar; Cho, Chunghee; Kim, Do Han

    2017-01-01

    Pathological hypertrophy of the heart is closely associated with endoplasmic reticulum stress (ERS), leading to maladaptations such as myocardial fibrosis, induction of apoptosis, and cardiac dysfunctions. Salubrinal is a known selective inhibitor of protein phosphatase 1 (PP1) complex involving dephosphorylation of phospho-eukaryotic translation initiation factor 2 subunit (p-eIF2)-α, the key signaling process in the ERS pathway. In this study, the effects of salubrinal were examined on cardiac hypertrophy using the mouse model of transverse aortic constriction (TAC) and cell model of neonatal rat ventricular myocytes (NRVMs). Treatment of TAC-induced mice with salubrinal (0.5 mg·kg−1·day−1) alleviated cardiac hypertrophy and tissue fibrosis. Salubrinal also alleviated hypertrophic growth in endothelin 1 (ET1)-treated NRVMs. Therefore, the present results suggest that salubrinal may be a potentially efficacious drug for treating pathological cardiac remodeling. PMID:28152298

  4. Aging induces cardiac diastolic dysfunction, oxidative stress, accumulation of advanced glycation endproducts and protein modification.

    Science.gov (United States)

    Li, Shi-Yan; Du, Min; Dolence, E Kurt; Fang, Cindy X; Mayer, Gabriele E; Ceylan-Isik, Asli F; LaCour, Karissa H; Yang, Xiaoping; Wilbert, Christopher J; Sreejayan, Nair; Ren, Jun

    2005-04-01

    Evidence suggests that aging, per se, is a major risk factor for cardiac dysfunction. Oxidative modification of cardiac proteins by non-enzymatic glycation, i.e. advanced glycation endproducts (AGEs), has been implicated as a causal factor in the aging process. This study was designed to examine the role of aging on cardiomyocyte contractile function, cardiac protein oxidation and oxidative modification. Mechanical properties were evaluated in ventricular myocytes from young (2-month) and aged (24-26-month) mice using a MyoCam system. The mechanical indices evaluated were peak shortening (PS), time-to-PS (TPS), time-to-90% relengthening (TR90) and maximal velocity of shortening/relengthening (+/- dL/dt). Oxidative stress and protein damage were evaluated by glutathione and glutathione disulfide (GSH/GSSG) ratio and protein carbonyl content, respectively. Activation of NAD(P)H oxidase was determined by immunoblotting. Aged myocytes displayed a larger cell cross-sectional area, prolonged TR90, and normal PS, +/- dL/dt and TPS compared with young myocytes. Aged myocytes were less tolerant of high stimulus frequency (from 0.1 to 5 Hz) compared with young myocytes. Oxidative stress and protein oxidative damage were both elevated in the aging group associated with significantly enhanced p47phox but not gp91phox expression. In addition, level of cardiac AGEs was approximately 2.5-fold higher in aged hearts than young ones determined by AGEs-ELISA. A group of proteins with a molecular range between 50 and 75 kDa with pI of 4-7 was distinctively modified in aged heart using one- or two-dimension SDS gel electrophoresis analysis. These data demonstrate cardiac diastolic dysfunction and reduced stress tolerance in aged cardiac myocytes, which may be associated with enhanced cardiac oxidative damage, level of AGEs and protein modification by AGEs.

  5. Motivation to pursue genetic testing in individuals with a personal or family history of cardiac events or sudden cardiac death.

    Science.gov (United States)

    Erskine, Kathleen E; Hidayatallah, Nadia Z; Walsh, Christine A; McDonald, Thomas V; Cohen, Lilian; Marion, Robert W; Dolan, Siobhan M

    2014-10-01

    Genetic testing is becoming increasingly available for cardiac channelopathies, such as long QT syndrome and Brugada syndrome, which can lead to sudden cardiac death. Test results can be used to shape an individual's medical management and to identify at-risk family members. In our qualitative study, all participants had a personal or family history of a diagnosed cardiac arrhythmia syndrome or sudden cardiac death. Open-ended interviews were conducted individually and in focus groups. Interviews were audio recorded, transcribed verbatim, and analyzed using a qualitative grounded-theory approach. Of 50 participants, 37 described their motivations for pursuing genetic testing for long QT syndrome or another cardiac channelopathy. Participants' motivations included: to find an explanation for a family member's sudden death, to relieve uncertainty regarding a diagnosis, to guide future medical management, to allay concern about children or other family members, and to comply with recommendations of physicians or family members. Perceived reasons not to pursue genetic testing included denial, fear, and lack of information. The genetic counseling and informed consent process can be enhanced by understanding and addressing an individual's internal and external motivations either for or against pursuing genetic testing.

  6. Stress-dependent cardiac remodeling occurs in the absence of microRNA-21 in mice

    DEFF Research Database (Denmark)

    Patrick, David M; Montgomery, Rusty L; Qi, Xiaoxia

    2010-01-01

    contractility comparable to wild. type littermates. Similarly, inhibition of miR-21 through intravenous delivery of a locked nucleic acid-modified (LNA-modified) antimiR oligonucleotide also failed to block the remodeling response of the heart to stress. We therefore conclude that miR-21 is not essential...... for pathological cardiac remodeling....

  7. The development and testing of the nurses' cardiac triage instrument.

    Science.gov (United States)

    Arslanian-Engoren, Cynthia; Hagerty, Bonnie M

    2013-01-01

    Rapid recognition and treatment of myocardial infarction (MI) reduces morbidity and mortality. Although emergency department (ED) nurses are often the first provider to evaluate individuals and are in a prime position to initiate MI guideline recommendations, no valid and reliable instrument was found to quantify their decision-making processes. The purpose of this study was to develop and test the psychometric properties of a new theoretically driven, empirically based instrument for measuring nurses' cardiac triage decisions. Using a descriptive research design, data were collected using a mailed survey. There were 158 ED nurses who completed a mailed questionnaire. Factor analysis revealed three factors (patient presentation, unbiased nurse reasoning process, and nurse action) with good internal consistency (Cronbach's alpha = .903, .809, .718) and sample adequacy (KMO = .758) of the 30-item instrument. The newly developed instrument has the potential to improve patient outcomes surrounding early MI identification and treatment.

  8. Taxifolin protects against cardiac hypertrophy and fibrosis during biomechanical stress of pressure overload

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Haipeng; Zhang, Xin [Department of Critical Care Medicine, Qilu Hospital of Shandong University, Jinan (China); Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital of Shandong University, Jinan (China); Cui, Yuqian [Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital of Shandong University, Jinan (China); Zhou, Heng [Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan (China); Xu, Dachun [Department of Cardiology, Shanghai Tenth People' s Hospital of Tongji University, Shanghai (China); Shan, Tichao; Zhang, Fan [Department of Critical Care Medicine, Qilu Hospital of Shandong University, Jinan (China); Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital of Shandong University, Jinan (China); Guo, Yuan [Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital of Shandong University, Jinan (China); Chen, Yuguo, E-mail: chen919085@163.com [Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital of Shandong University, Jinan (China); Department of Emergency, Qilu Hospital of Shandong University, Jinan (China); Wu, Dawei, E-mail: wdwu55@163.com [Department of Critical Care Medicine, Qilu Hospital of Shandong University, Jinan (China); Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital of Shandong University, Jinan (China)

    2015-09-01

    Cardiac hypertrophy is a key pathophysiological component to biomechanical stress, which has been considered to be an independent and predictive risk factor for adverse cardiovascular events. Taxifolin (TAX) is a typical plant flavonoid, which has long been used clinically for treatment of cardiovascular and cerebrovascular diseases. However, very little is known about whether TAX can influence the development of cardiac hypertrophy. In vitro studies, we found that TAX concentration-dependently inhibited angiotensin II (Ang II) induced hypertrophy and protein synthesis in cardiac myocytes. Then we established a mouse model by transverse aortic constriction (TAC) to further confirm our findings. It was demonstrated that TAX prevented pressure overload induced cardiac hypertrophy in mice, as assessed by ventricular mass/body weight, echocardiographic parameters, myocyte cross-sectional area, and the expression of ANP, BNP and β-MHC. The excess production of reactive oxygen species (ROS) played critical role in the development of cardiac hypertrophy. TAX arrested oxidative stress and decreased the expression of 4-HNE induced by pressure overload. Moreover, TAX negatively modulated TAC-induced phosphorylation of ERK1/2 and JNK1/2. Further studies showed that TAX significantly attenuated left ventricular fibrosis and collagen synthesis through abrogating the phosphorylation of Smad2 and Smad2/3 nuclear translocation. These results demonstrated that TAX could inhibit cardiac hypertrophy and attenuate ventricular fibrosis after pressure overload. These beneficial effects were at least through the inhibition of the excess production of ROS, ERK1/2, JNK1/2 and Smad signaling pathways. Therefore, TAX might be a potential candidate for the treatment of cardiac hypertrophy and fibrosis. - Highlights: • We focus on the protective effect of taxifolin on cardiac remodeling. • Taxifolin inhibited cardiac hypertrophy and attenuated ventricular fibrosis. • Taxifolin

  9. Stress response and cardiac activity of term and preterm calves in the perinatal period.

    Science.gov (United States)

    Nagel, Christina; Aurich, Jörg; Trenk, Lisa; Ille, Natascha; Drillich, Marc; Pohl, Werner; Aurich, Christine

    2016-10-01

    This study tested the hypothesis of gestational age affecting fetal cardiac activity and the stress response at birth. Heart rate (HR), heart rate variability variables, SD of the beat-to-beat interval and root mean square of successive beat-to-beat differences, and postnatal salivary cortisol concentration were studied in calves born at term (Term, n = 7, gestation length 286.3 ± 2.1 days) or after induction of parturition (Preterm, n = 7, gestation length 279.6 ± 0.2 days). Observation periods covered the last month of gestation (phase A), the last hours before birth including the first stage of labor (phase B), and the neonatal period (phase C). Fetal HR decreased in phase A (P gestation length (r ≥ 0.68, P < 0.01). Because of a certain degree of immaturity, the ability to cope with the stress of birth may be impaired in calves born 1 week before term.

  10. Stress Testing with Student's t Dependence

    NARCIS (Netherlands)

    H.J.W.G. Kole (Erik); C.G. Koedijk (Kees); M.J.C.M. Verbeek (Marno)

    2003-01-01

    textabstractIn this study we propose the use of the Student's t dependence function to model dependence between asset returns when conducting stress tests. To properly include stress testing in a risk management system, it is important to have accurate information about the (joint) probabilities of

  11. 77 FR 62417 - Annual Stress Test

    Science.gov (United States)

    2012-10-15

    ... are multiple covered banks within a single parent organization. D. Scenarios Under the final rule... their stress test results under the same timeframe as their parent holding company. The final rule... stress testing requirements) to submit a single report for both the bank and the bank holding...

  12. Cold face test demonstrates parasympathetic cardiac dysfunction in familial dysautonomia.

    Science.gov (United States)

    Hilz, M J; Stemper, B; Sauer, P; Haertl, U; Singer, W; Axelrod, F B

    1999-06-01

    In familial dysautonomia (FD), i.e., Riley-Day syndrome, parasympathetic dysfunction has not been sufficiently evaluated. The cold face test is a noninvasive method of activating trigeminal brain stem cardiovagal and sympathetic pathways and can be performed in patients with limited cooperation. We performed cold face tests in 11 FD patients and 15 controls. For 60 s, cold compresses (0-1 degrees C) were applied to the cheeks and forehead while we monitored heart rate, respiration, beat-to-beat radial artery blood pressure, and laser-Doppler skin blood flow at the first toe pulp. From these measurements heart rate variability parameters were calculated: root mean square of successive differences (RMSSD), coefficient of variation (CV), low- and high-frequency (LF and HF, respectively) power spectra of the electrocardiogram, and the LF transfer function gain between blood pressure and heart rate. All patients perceived cold stimulation and acknowledged discomfort. In controls, heart rate and skin blood flow decreased significantly during cold face test; in patients, both parameters decreased only briefly and not significantly. In controls, blood pressure, RMSSD, CV, and heart rate HF-power spectra increased but remained unchanged in patients. Respiration, as well as heart rate LF power spectra, did not change in either group. In controls, LF transfer function gain between blood pressure and heart rate indicated that bradycardia was not secondary to blood pressure increase. We conclude that the cold face test demonstrated that patients with FD have a reduced cardiac parasympathetic response, which implies efferent parasympathetic dysfunction.

  13. Protective Effects of Aspirin from Cardiac Hypertrophy and Oxidative Stress in Cardiomyopathic Hamsters

    Directory of Open Access Journals (Sweden)

    Rong Wu

    2012-01-01

    Full Text Available Objective. To evaluate the capacity of chronic ASA therapy to prevent cardiac alterations and increased oxidative stress in cardiomyopathic hamsters. Methods and Results. Male Syrian cardiomyopathic and age-matched inbred control hamsters received ASA orally from the age of 60 days. Animals were sacrificed at the age of 150, 250, and 350 days to evaluate the time course of cardiac hypertrophy and cardiovascular tissue superoxide anion (O2- production. At the age of 150 days, the ventricular weight over body weight ratio, resting heart rate, and cardiovascular O2- production were much higher in cardiomyopathic hamsters than those in control. At the age of 250 days, in addition to the continual deterioration of these parameters with age, the blood pressure started to fall and the signs of heart failure appeared. In these cardiomyopathic hamsters, chronic ASA treatment (a completely prevented elevated O2- production and the NAD(PH oxidase activity, (b significantly slowed down the development of the cardiac hypertrophy and fibrosis. Conclusions. Chronic ASA treatment significantly prevents the deterioration of cardiac function and structure as well as the increased oxidative stress in the cardiomyopathic hamster. Our findings suggest that ASA presents a therapeutic potential to prevent cardiac dysfunction.

  14. Disruption of calpain reduces lipotoxicity-induced cardiac injury by preventing endoplasmic reticulum stress

    Science.gov (United States)

    Li, Shengcun; Zhang, Lulu; Ni, Rui; Cao, Ting; Zheng, Dong; Xiong, Sidong; Greer, Peter A.; Fan, Guo-Chang; Peng, Tianqing

    2016-01-01

    Diabetes and obesity are prevalent in westernized countries. In both conditions, excessive fatty acid uptake by cardiomyocytes induces cardiac lipotoxicity, an important mechanism contributing to diabetic cardiomyopathy. This study investigated the effect of calpain disruption on cardiac lipotoxicity. Cardiac-specific capns1 knockout mice and their wild-type littermates (male, age of 4 weeks) were fed a high fat diet (HFD) or normal diet for 20 weeks. HFD increased body weight, altered blood lipid profiles and impaired glucose tolerance comparably in both capns1 knockout mice and their wild-type littermates. Calpain activity, cardiomyocyte cross-sectional areas, collagen deposition and triglyceride were significantly increased in HFD-fed mouse hearts, and these were accompanied by myocardial dysfunction and up-regulation of hypertrophic and fibrotic collagen genes as well as pro-inflammatory cytokines. These effects of HFD were attenuated by disruption of calpain in capns1 knockout mice. Mechanistically, deletion of capns1 in HFD-fed mouse hearts and disruption of calpain with calpain inhibitor-III, silencing of capn1, or deletion of capns1 in palmitate-stimulated cardiomyocytes prevented endoplasmic reticulum stress, apoptosis, cleavage of caspase-12 and junctophilin-2, and pro-inflammatory cytokine expression. Pharmacological inhibition of endoplasmic reticulum stress diminished palmitate-induced apoptosis and pro-inflammatory cytokine expression in cardiomyocytes. In summary, disruption of calpain prevents lipotoxicity-induced apoptosis in cardiomyocytes and cardiac injury in mice fed a HFD. The role of calpain is mediated, at least partially, through endoplasmic reticulum stress. Thus, calpain/endoplasmic reticulum stress may represent a new mechanism and potential therapeutic targets for cardiac lipotoxicity. PMID:27523632

  15. Protection by 6-aminonicotinamide against oxidative stress in cardiac cells

    DEFF Research Database (Denmark)

    Hofgaard, Johannes P; Sigurdardottir, Kristin Sigridur; Treiman, Marek

    2006-01-01

    Oxidative stress at the time of reperfusion is a major aspect of ischemia-reperfusion injury in heart as well as in other organs. There is a continuing interest in development of pharmacological approaches to alleviate this injury. 6-Aminonicotinamide (6AN) has been shown to diminish myocardial n...

  16. The Mitochondrial Calcium Uniporter Matches Energetic Supply with Cardiac Workload during Stress and Modulates Permeability Transition

    Directory of Open Access Journals (Sweden)

    Timothy S. Luongo

    2015-07-01

    Full Text Available Cardiac contractility is mediated by a variable flux in intracellular calcium (Ca2+, thought to be integrated into mitochondria via the mitochondrial calcium uniporter (MCU channel to match energetic demand. Here, we examine a conditional, cardiomyocyte-specific, mutant mouse lacking Mcu, the pore-forming subunit of the MCU channel, in adulthood. Mcu−/− mice display no overt baseline phenotype and are protected against mCa2+ overload in an in vivo myocardial ischemia-reperfusion injury model by preventing the activation of the mitochondrial permeability transition pore, decreasing infarct size, and preserving cardiac function. In addition, we find that Mcu−/− mice lack contractile responsiveness to acute β-adrenergic receptor stimulation and in parallel are unable to activate mitochondrial dehydrogenases and display reduced bioenergetic reserve capacity. These results support the hypothesis that MCU may be dispensable for homeostatic cardiac function but required to modulate Ca2+-dependent metabolism during acute stress.

  17. The Mitochondrial Calcium Uniporter Matches Energetic Supply with Cardiac Workload during Stress and Modulates Permeability Transition.

    Science.gov (United States)

    Luongo, Timothy S; Lambert, Jonathan P; Yuan, Ancai; Zhang, Xueqian; Gross, Polina; Song, Jianliang; Shanmughapriya, Santhanam; Gao, Erhe; Jain, Mohit; Houser, Steven R; Koch, Walter J; Cheung, Joseph Y; Madesh, Muniswamy; Elrod, John W

    2015-07-01

    Cardiac contractility is mediated by a variable flux in intracellular calcium (Ca(2+)), thought to be integrated into mitochondria via the mitochondrial calcium uniporter (MCU) channel to match energetic demand. Here, we examine a conditional, cardiomyocyte-specific, mutant mouse lacking Mcu, the pore-forming subunit of the MCU channel, in adulthood. Mcu(-/-) mice display no overt baseline phenotype and are protected against mCa(2+) overload in an in vivo myocardial ischemia-reperfusion injury model by preventing the activation of the mitochondrial permeability transition pore, decreasing infarct size, and preserving cardiac function. In addition, we find that Mcu(-/-) mice lack contractile responsiveness to acute β-adrenergic receptor stimulation and in parallel are unable to activate mitochondrial dehydrogenases and display reduced bioenergetic reserve capacity. These results support the hypothesis that MCU may be dispensable for homeostatic cardiac function but required to modulate Ca(2+)-dependent metabolism during acute stress.

  18. Targeted Deletion of MicroRNA-22 Promotes Stress-Induced Cardiac Dilation and Contractile Dysfunction

    Science.gov (United States)

    Gurha, Priyatansh; Abreu-Goodger, Cei; Wang, Tiannan; Ramirez, Maricela O.; Drumond, Ana L.; van Dongen, Stijn; Chen, Yuqing; Bartonicek, Nenad; Enright, Anton J.; Lee, Brendan; Kelm, Robert J.; Reddy, Anilkumar K.; Taffet, George E.; Bradley, Allan; Wehrens, Xander H.; Entman, Mark L.; Rodriguez, Antony

    2012-01-01

    Background Delineating the role of microRNAs (miRNAs) in the posttranscriptional gene regulation offers new insights into how the heart adapts to pathological stress. We developed a knockout of miR-22 in mice and investigated its function in the heart. Methods and Results Here, we show that miR-22–deficient mice are impaired in inotropic and lusitropic response to acute stress by dobutamine. Furthermore, the absence of miR-22 sensitized mice to cardiac decompensation and left ventricular dilation after long-term stimulation by pressure overload. Calcium transient analysis revealed reduced sarcoplasmic reticulum Ca2+ load in association with repressed sarcoplasmic reticulum Ca2+ ATPase activity in mutant myocytes. Genetic ablation of miR-22 also led to a decrease in cardiac expression levels for Serca2a and muscle-restricted genes encoding proteins in the vicinity of the cardiac Z disk/titin cytoskeleton. These phenotypes were attributed in part to inappropriate repression of serum response factor activity in stressed hearts. Global analysis revealed increased expression of the transcriptional/translational repressor purine-rich element binding protein B, a highly conserved miR-22 target implicated in the negative control of muscle expression. Conclusion These data indicate that miR-22 functions as an integrator of Ca2+ homeostasis and myofibrillar protein content during stress in the heart and shed light on the mechanisms that enhance propensity toward heart failure. PMID:22570371

  19. Contraction stress test by intermittent nipple stimulation.

    Science.gov (United States)

    Huddleston, J F; Sutliff, G; Robinson, D

    1984-05-01

    Although the nonstress test has generally supplanted the contraction stress test as the primary test for assessment of fetal well-being, the contraction stress test continues to be useful. Objectionable factors of the contraction stress test have included the time required to complete the test and the frequent necessity for intravenous oxytocin. The authors developed a contraction stress test protocol using contractions produced by intermittent nipple stimulation and used the method for 345 tests on 193 high-risk pregnancies during a 15-month period. The women were instructed to stimulate one breast, through their clothes, for two minutes and then to rest for five minutes. This cycle was repeated as necessary, but was interrupted whenever contractions began. Using this protocol, the authors were successful in achieving an adequate contraction frequency with every attempt, and hyperstimulation was not more frequent than previously reported with the standard contraction stress test. The average time requirement was 45 minutes. No unexplained stillbirths occurred after a negative test.

  20. Stress testing - ettevaatliku investori abimees / Peeter Teder

    Index Scriptorium Estoniae

    Teder, Peeter

    2005-01-01

    Autor selgitab stress testingut kui investeerimisportfelli varade väärtuse hindamist ning tutvustab selle võimalusi ja ohtusid. Diagrammid: Portfelli testimis-stsenaariumiks sobivad hästi börsikrahhid. Vt. samas: Stress testing toimib ka mujal

  1. What is role of sex and age differences in marital conflict and stress of patients under Cardiac Rehabilitation Program?

    Science.gov (United States)

    Komasi, Saeid; Saeidi, Mozhgan

    2016-01-01

    BACKGROUND To investigate the role of sex and age differences in marital conflict and stress of patients who were under cardiac rehabilitation (CR) program. METHODS The data of this cross-sectional study were collected from the database of the CR Department of Imam Ali Hospital, Kermanshah, Iran. The demographics and medical data of 683 persons were collected from January 2003 and January 2010 using medical records, the Beck Anxiety Inventory, the Beck Depression Inventory, the Hudson’s Index of Marital Stress, and the Structured Clinical Interview for axis I disorders. Data were analyzed through Analysis of Covariance and Bonferroni test. RESULTS About 74.8% of the subjects were male. After adjustment for age, educational level, anxiety, and depression-the findings showed that women in CR program had a higher level of marital stress compared to men (54.75 ± 2.52 vs. 49.30 ± 0.89; P = 0.042). Furthermore, it was revealed that women who aged 56-65 years and more experienced higher level of marital stress compared to younger patients (P 0.050). CONCLUSION Marital conflict and stress threaten healthiness of women who aged 56-65 years more prominently than does in males or younger patients. Regarding the effect of marital stress on recurrence of the disease and cardiac-related morbidity and mortality in women, providing effective education and interventions to this group of patients, especially older women and even their spouses could be one of the useful objectives of CR programs. PMID:27752271

  2. 77 FR 61238 - Annual Stress Test

    Science.gov (United States)

    2012-10-09

    ... institutions within a single parent organization. In this regard, the OCC notes that even where such a covered..., such decisions should not be based solely on the results of any single set of stress tests. Rather... activities and exercises rather than relying on any single test or type of test. \\9\\ Supervisory Guidance...

  3. Impact of weightlessness on cardiac shape and left ventricular stress/strain distributions.

    Science.gov (United States)

    Iskovitz, Ilana; Kassemi, Mohammad; Thomas, James D

    2013-12-01

    In this paper, a finite element model of the heart is developed to investigate the impact of different gravitational loadings of Earth, Mars, Moon, and microgravity on the cardiac shape and strain/stress distributions in the left ventricle. The finite element model is based on realistic 3D heart geometry, detailed fiber/sheet micro-architecture, and a validated orthotropic cardiac tissue model and constitutive relationship that capture the passive behavior of the heart at end-diastole. The model predicts the trend and magnitude of cardiac shape change at different gravitational levels with great fidelity in comparison to recent cardiac sphericity measurements performed during simulated reduced-gravity parabolic flight experiments. Moreover, the numerical predictions indicate that although the left ventricular strain distributions remain relatively unaltered across the gravitational fields and the strain extrema values occur at the same relative locations, their values change noticeably with decreasing gravity. As for the stress, however, both the magnitude and location of the extrema change with a decrease in the gravitational field. Consequently, tension regions of the heart on Earth can change into compression regions in space.

  4. Maprotiline treatment differentially influences cardiac β-adrenoreceptors expression under normal and stress conditions

    Directory of Open Access Journals (Sweden)

    Natasa Spasojevic

    2012-12-01

    Full Text Available Alterations in cardiac function were observed in antidepressants treated patients and published in several clinical reports. These detected changes could be either a consequence of the treatment or of depression itself, which has already been proved to be a risk factor in heart diseases. In order to determine a possible influence of chronic treatment with norepinephrinergic reuptake inhibitor, maprotiline, on the heart, we investigated gene expression of cardiac β-adrenoceptors both in controls and in animals with signs of depression. The rats were divided into two groups, unstressed controls and those exposed to chronic unpredictable mild stress (CUMS. The groups were further divided into two subgroups, one receiving daily intraperitoneal injections of vehicle (sterile water and another one maprotiline (10 mg/kg for four weeks. Tissue samples were collected after the last application. Gene expression of cardiac β1- and β2-adrenoceptor was determined using Real-time RT-PCR analysis. Our results show that in control animals expression of both adrenoreceptors was decreased in the right atria after 4 weeks of maprotiline application. Contrary, the same treatment led to a significant increase in expression of cardiac β1-adrenoceptor in the stressed rats, with no change in the characteristics of β2-adrenoceptor. Our findings might reflect the that molecular mechanisms are underlying factors involved in the development of cardiovascular diseases linked with antidepressant treatment.

  5. Popeye domain-containing proteins and stress-mediated modulation of cardiac pacemaking.

    Science.gov (United States)

    Simrick, Subreena; Schindler, Roland F; Poon, Kar-Lai; Brand, Thomas

    2013-10-01

    An intricate network of ion channels and pumps are involved in generating a diastolic pacemaker potential, which is transmitted to the working myocardium with the help of the cardiac conduction system. The principles of cardiac pacemaking are reasonably well understood, however, the mechanism by which the heart increases its beating frequency in response to adrenergic stimulation has not been fully worked out. The Popeye domain-containing (Popdc) genes encode plasma membrane-localized proteins that are able to bind cAMP with high affinity; mice with null mutations in Popdc1 or 2 have a stress-induced pacemaker dysfunction. The phenotype in both mutants develops in an age-dependent manner and thus may model pacemaker dysfunction in man, as well as provide novel mechanistic insights into the process of pacemaker adaptation to stress.

  6. The development of a new cardiac auscultation test: How do screening and diagnostic skills differ?

    DEFF Research Database (Denmark)

    Nielsen, Tommy; Mølgaard, Henning; Ringsted, Charlotte Vibeke;

    2010-01-01

    BACKGROUND: Newly qualified doctors are expected to be able to conduct a cardiac auscultation unassisted, but studies show conflicting results regarding cardiac auscultation skills. METHODS: A two-part test instrument was designed containing innovative recordings of heart sounds from patients wit...

  7. The effects of Vigna unguiculata on cardiac oxidative stress and aorta estrogen receptor-β expression of ovariectomized rats

    Directory of Open Access Journals (Sweden)

    Etik Khusniyati

    2014-12-01

    Conclusions: V. unguiculata is an alternative therapy in decreasing cardiac oxidative stress in ovariectomized rats. Besides, high dose of V. unguiculata also able to increase aorta estrogen receptor-β expression in ovariectomized rats.

  8. Trans-resveratrol reduces cardiac oxidative stress in rats exposed to cigarette smoke

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    Melina Hauck

    2015-07-01

    Full Text Available Differences between reactive oxygen species and antioxidant defense system unbalance the redox status. The exposure to cigarette smoke can increase this imbalance. Trans-resveratrol is a polyphenol with great antioxidant action that reduces the oxidative stress. This study investigated the effect of the trans-resveratrol supplementation on the cardiac oxidative stress in rats exposed to cigarette smoke. Male Wistar rats were randomized into four groups: Control Group (CG, Exposure to Smoke Group (ESG, Antioxidant Group (AG and Exposure to Smoke plus Antioxidant Group (ESAG. Animals were exposed to cigarette smoke and supplemented with trans-resveratrol (6.0 mg kg-1 for two months. The lipid peroxidation (TBARS and the enzymatic activity of catalase (CAT were measured in the cardiac muscle. The ESG presented the highest lipid peroxidation level compared with CG (p < 0.001, AG (p < 0.001 and ESAG (p < 0.006. The CAT activity was higher in the AG (p < 0.001 and ESAG (p < 0.001 compared with CG. The ESG presented lower CAT activity compared with the ESAG (p < 0.001. The supplementation of Trans-resveratrol attenuated the cardiac oxidative stress and increased the activity of catalase. Our findings evidenced the cardioprotective effect of trans-resveratrol in rats exposed to cigarette smoke.

  9. Cognitive emotion regulation fails the stress test.

    Science.gov (United States)

    Raio, Candace M; Orederu, Temidayo A; Palazzolo, Laura; Shurick, Ashley A; Phelps, Elizabeth A

    2013-09-10

    Cognitive emotion regulation has been widely shown in the laboratory to be an effective way to alter the nature of emotional responses. Despite its success in experimental contexts, however, we often fail to use these strategies in everyday life where stress is pervasive. The successful execution of cognitive regulation relies on intact executive functioning and engagement of the prefrontal cortex, both of which are rapidly impaired by the deleterious effects of stress. Because it is specifically under stressful conditions that we may benefit most from such deliberate forms of emotion regulation, we tested the efficacy of cognitive regulation after stress exposure. Participants first underwent fear-conditioning, where they learned that one stimulus (CS+) predicted an aversive outcome but another predicted a neutral outcome (CS-). Cognitive regulation training directly followed where participants were taught to regulate fear responses to the aversive stimulus. The next day, participants underwent an acute stress induction or a control task before repeating the fear-conditioning task using these newly acquired regulation skills. Skin conductance served as an index of fear arousal, and salivary α-amylase and cortisol concentrations were assayed as neuroendocrine markers of stress response. Although groups showed no differences in fear arousal during initial fear learning, nonstressed participants demonstrated robust fear reduction following regulation training, whereas stressed participants showed no such reduction. Our results suggest that stress markedly impairs the cognitive regulation of emotion and highlights critical limitations of this technique to control affective responses under stress.

  10. Liquid salt environment stress-rupture testing

    Science.gov (United States)

    Ren, Weiju; Holcomb, David E.; Muralidharan, Govindarajan; Wilson, Dane F.

    2016-03-22

    Disclosed herein are systems, devices and methods for stress-rupture testing selected materials within a high-temperature liquid salt environment. Exemplary testing systems include a load train for holding a test specimen within a heated inert gas vessel. A thermal break included in the load train can thermally insulate a load cell positioned along the load train within the inert gas vessel. The test specimen can include a cylindrical gage portion having an internal void filled with a molten salt during stress-rupture testing. The gage portion can have an inner surface area to volume ratio of greater than 20 to maximize the corrosive effect of the molten salt on the specimen material during testing. Also disclosed are methods of making a salt ingot for placement within the test specimen.

  11. Effect of atropine-dobutamine stress test on left ventricular echocardiographic parameters in untrained warmblood horses.

    Science.gov (United States)

    Sandersen, Charlotte F; Detilleux, Johanne; de Moffarts, Brieuc; Van Loon, Gunther; Amory, Hélène

    2006-01-01

    The aim of this study was to investigate the effect of combined atropine low-dose dobutamine stress test on left ventricular parameters in adult warmblood horses, to establish a potential protocol for pharmacological stress echocardiography. Seven healthy untrained warmblood horses aged 9 to 22 years were used. Heart rate (HR) and left ventricular B- and M-mode dimensions were recorded at baseline and during stress testing with 35 microg/kg atropine IV followed by incremental dobutamine infusion of 2 to 6 microg/kg/min. HR increased significantly (P stress test induced significant changes in left ventricular echocardiographic parameters in adult warmblood horses. Additional research should evaluate the value of this stress test in horses suffering from cardiac disease.

  12. ST-Elevation Myocardial Infarction after Pharmacologic Persantine Stress Test in a Patient with Wellens’ Syndrome

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    Kunal Patel

    2014-01-01

    Full Text Available Wellens’ syndrome, also known as LAD coronary T-wave inversion syndrome, is a characteristic ECG pattern that highly suggests critical stenosis of the proximal left anterior descending (LAD coronary artery. 75% of patients with this finding go on to develop acute anterior wall myocardial infarction within one week unless prevented by early intervention on the culprit lesion. Most instances of ST-elevation occurring during cardiac stress testing have been observed with exercise, with only seven cases reported in the literature with pharmacologic stress. We present a case of a patient with no known cardiac disease who presented with chest pain and an ECG consistent with Wellens’ syndrome that developed an acute anterior wall ST-elevation myocardial infarction after pharmacologic stress test.

  13. ST-Elevation Myocardial Infarction after Pharmacologic Persantine Stress Test in a Patient with Wellens' Syndrome.

    Science.gov (United States)

    Patel, Kunal; Alattar, Fady; Koneru, Jayanth; Shamoon, Fayez

    2014-01-01

    Wellens' syndrome, also known as LAD coronary T-wave inversion syndrome, is a characteristic ECG pattern that highly suggests critical stenosis of the proximal left anterior descending (LAD) coronary artery. 75% of patients with this finding go on to develop acute anterior wall myocardial infarction within one week unless prevented by early intervention on the culprit lesion. Most instances of ST-elevation occurring during cardiac stress testing have been observed with exercise, with only seven cases reported in the literature with pharmacologic stress. We present a case of a patient with no known cardiac disease who presented with chest pain and an ECG consistent with Wellens' syndrome that developed an acute anterior wall ST-elevation myocardial infarction after pharmacologic stress test.

  14. A multidimensional model of the antecedents of stress and coping appraisals: an approach to studying patients' perceptions of post cardiac surgery pain and their coping strategies.

    Science.gov (United States)

    Shih, F J; Huang, L H

    1996-04-01

    Lazarus' stress and coping theory has been recognized as a valued conceptual framework for nursing scholars who are interested in studying their client's experiences of stress and coping. However, little data provide in-depth critiques in concepts, availability and limitations of employing Lazarus' theory in nursing phenomena in Taiwan, nor did data provide culturally sensitive propositions for Taiwanese nursing scholars to better understand their clients' stress experience such as post cardiac surgery pain. In order to help Taiwanese critical care nurses better understand the process of theoretical development while assessing their clients' perceptions of post cardiac surgery pain, the historical perspective of the concept of stress and the core components of Lazarus' theory are examined. Following is a critical critique of Lazarus' theory as a conceptual framework with which to study how patients perceive post cardiac surgery pain as a stressor. A multidimensional model of the antecedents of stress and coping appraisals for nurses to assess their clients' perceptions of pain and the resulting coping behaviors is further developed based on the aforementioned critiques. Finally, suggestions for testing theoretical propositions related to this phenomenon, as well as implications for nursing practice, research, as theory are delineated and discussed.

  15. Ultrastructural changes, increased oxidative stress, inflammation, and altered cardiac hypertrophic gene expressions in heart tissues of rats exposed to incense smoke.

    Science.gov (United States)

    Al-Attas, Omar S; Hussain, Tajamul; Ahmed, Mukhtar; Al-Daghri, Nasser; Mohammed, Arif A; De Rosas, Edgard; Gambhir, Dikshit; Sumague, Terrance S

    2015-07-01

    Incense smoke exposure has recently been linked to cardiovascular disease risk, heart rate variability, and endothelial dysfunction. To test the possible underlying mechanisms, oxidative stress, and inflammatory markers, gene expressions of cardiac hypertrophic and xenobiotic-metabolizing enzymes and ultrastructural changes were measured, respectively, using standard, ELISA-based, real-time PCR, and transmission electron microscope procedures in heart tissues of Wistar rats after chronically exposing to Arabian incense. Malondialdehyde, tumor necrosis alpha (TNF)-α, and IL-4 levels were significantly increased, while catalase and glutathione levels were significantly declined in incense smoke-exposed rats. Incense smoke exposure also resulted in a significant increase in atrial natriuretic peptide, brain natriuretic peptide, β-myosin heavy chain, CYP1A1 and CYP1A2 messenger RNAs (mRNAs). Rats exposed to incense smoke displayed marked ultrastructural changes in heart muscle with distinct cardiac hypertrophy, which correlated with the augmented hypertrophic gene expression as well as markers of cardiac damage including creatine kinase-myocardial bound (CK-MB) and lactate dehydrogenase (LDH). Increased oxidative stress, inflammation, altered cardiac hypertrophic gene expression, tissue damage, and architectural changes in the heart may collectively contribute to increased cardiovascular disease risk in individuals exposed to incense smoke. Increased gene expressions of CYP1A1 and CYP1A2 may be instrumental in the incense smoke-induced oxidative stress and inflammation. Thus, incense smoke can be considered as a potential environmental pollutant and its long-term exposure may negatively impact human health.

  16. CARDIAC AND BEHAVIORAL-RESPONSES OF LONG-TERM OBESE AND LEAN ZUCKER RATS TO EMOTIONAL-STRESS

    NARCIS (Netherlands)

    NYAKAS, C; BALKAN, B; STEFFENS, AB; BOHUS, B

    1995-01-01

    Obesity is known as a risk factor in stress-related cardiovascular pathology in man. The length of obesity can be an important interacting variable. Therefore, cardiac and behavioral responses to emotional stress were studied in 1-year-old, genetically obese (fa/fa) and lean (Fa/-) male Zucker rats,

  17. Heme oxygenase-1 induction improves cardiac function following myocardial ischemia by reducing oxidative stress.

    Directory of Open Access Journals (Sweden)

    Yossi Issan

    Full Text Available BACKGROUND: Oxidative stress plays a key role in exacerbating diabetes and cardiovascular disease. Heme oxygenase-1 (HO-1, a stress response protein, is cytoprotective, but its role in post myocardial infarction (MI and diabetes is not fully characterized. We aimed to investigate the protection and the mechanisms of HO-1 induction in cardiomyocytes subjected to hypoxia and in diabetic mice subjected to LAD ligation. METHODS: In vitro: cultured cardiomyocytes were treated with cobalt-protoporphyrin (CoPP and tin protoporphyrin (SnPP prior to hypoxic stress. In vivo: CoPP treated streptozotocin-induced diabetic mice were subjected to LAD ligation for 2/24 h. Cardiac function, histology, biochemical damage markers and signaling pathways were measured. RESULTS: HO-1 induction lowered release of lactate dehydrogenase (LDH and creatine phospho kinase (CK, decreased propidium iodide staining, improved cell morphology and preserved mitochondrial membrane potential in cardiomyocytes. In diabetic mice, Fractional Shortening (FS was lower than non-diabetic mice (35±1%vs.41±2, respectively p<0.05. CoPP-treated diabetic animals improved cardiac function (43±2% p<0.01, reduced CK, Troponin T levels and infarct size compared to non-treated diabetic mice (P<0.01, P<0.001, P<0.01 respectively. CoPP-enhanced HO-1 protein levels and reduced oxidative stress in diabetic animals, as indicated by the decrease in superoxide levels in cardiac tissues and plasma TNFα levels (p<0.05. The increased levels of HO-1 by CoPP treatment after LAD ligation led to a shift of the Bcl-2/bax ratio towards the antiapoptotic process (p<0.05. CoPP significantly increased the expression levels of pAKT and pGSK3β (p<0.05 in cardiomyocytes and in diabetic mice with MI. SnPP abolished CoPP's cardioprotective effects. CONCLUSIONS: HO-1 induction plays a role in cardioprotection against hypoxic damage in cardiomyocytes and in reducing post ischemic cardiac damage in the diabetic heart

  18. Cardiac reflections and natural vibrations: Force-frequency relation recording system in the stress echo lab

    Directory of Open Access Journals (Sweden)

    Pianelli Mascia

    2007-11-01

    Full Text Available Abstract Background The inherent ability of ventricular myocardium to increase its force of contraction in response to an increase in contraction frequency is known as the cardiac force-frequency relation (FFR. This relation can be easily obtained in the stress echo lab, where the force is computed as the systolic pressure/end-systolic volume index ratio, and measured for increasing heart rates during stress. Ideally, the noninvasive, imaging independent, objective assessment of FFR would greatly enhance its practical appeal. Objectives 1 – To evaluate the feasibility of the cardiac force measurement by a precordial cutaneous sensor. 2 – To build the curve of force variation as a function of the heart rate. 3 – To compare the standard stress echo results vs. this sensor operator-independent built FFR. Methods The transcutaneous force sensor was positioned in the precordial region in 88 consecutive patients referred for exercise, dipyridamole, or pacing stress. The force was measured as the myocardial vibrations amplitude in the isovolumic contraction period. FFR was computed as the curve of force variation as a function of heart rate. Standard echocardiographic FFR measurements were performed. Results A consistent FFR was obtained in all patients. Both the sensor built and the echo built FFR identifiy pts with normal or abnormal contractile reserve. The best cut-off value of the sensor built FFR was 15.5 g * 10-3 (Sensitivity = 0.85, Specificity = 0.77. Sensor built FFR slope and shape mirror pressure/volume relation during stress. This approach is extendable to daily physiological exercise and could be potentially attractive in home monitoring systems.

  19. Popeye domain containing proteins are essential for stress-mediated modulation of cardiac pacemaking in mice.

    Science.gov (United States)

    Froese, Alexander; Breher, Stephanie S; Waldeyer, Christoph; Schindler, Roland F R; Nikolaev, Viacheslav O; Rinné, Susanne; Wischmeyer, Erhard; Schlueter, Jan; Becher, Jan; Simrick, Subreena; Vauti, Franz; Kuhtz, Juliane; Meister, Patrick; Kreissl, Sonja; Torlopp, Angela; Liebig, Sonja K; Laakmann, Sandra; Müller, Thomas D; Neumann, Joachim; Stieber, Juliane; Ludwig, Andreas; Maier, Sebastian K; Decher, Niels; Arnold, Hans-Henning; Kirchhof, Paulus; Fabritz, Larissa; Brand, Thomas

    2012-03-01

    Cardiac pacemaker cells create rhythmic pulses that control heart rate; pacemaker dysfunction is a prevalent disorder in the elderly, but little is known about the underlying molecular causes. Popeye domain containing (Popdc) genes encode membrane proteins with high expression levels in cardiac myocytes and specifically in the cardiac pacemaking and conduction system. Here, we report the phenotypic analysis of mice deficient in Popdc1 or Popdc2. ECG analysis revealed severe sinus node dysfunction when freely roaming mutant animals were subjected to physical or mental stress. In both mutants, bradyarrhythmia developed in an age-dependent manner. Furthermore, we found that the conserved Popeye domain functioned as a high-affinity cAMP-binding site. Popdc proteins interacted with the potassium channel TREK-1, which led to increased cell surface expression and enhanced current density, both of which were negatively modulated by cAMP. These data indicate that Popdc proteins have an important regulatory function in heart rate dynamics that is mediated, at least in part, through cAMP binding. Mice with mutant Popdc1 and Popdc2 alleles are therefore useful models for the dissection of the mechanisms causing pacemaker dysfunction and could aid in the development of strategies for therapeutic intervention.

  20. PARM-1 is an endoplasmic reticulum molecule involved in endoplasmic reticulum stress-induced apoptosis in rat cardiac myocytes.

    Directory of Open Access Journals (Sweden)

    Koji Isodono

    Full Text Available To identify novel transmembrane and secretory molecules expressed in cardiac myocytes, signal sequence trap screening was performed in rat neonatal cardiac myocytes. One of the molecules identified was a transmembrane protein, prostatic androgen repressed message-1 (PARM-1. While PARM-1 has been identified as a gene induced in prostate in response to castration, its function is largely unknown. Our expression analysis revealed that PARM-1 was specifically expressed in hearts and skeletal muscles, and in the heart, cardiac myocytes, but not non-myocytes expressed PARM-1. Immunofluorescent staining showed that PARM-1 was predominantly localized in endoplasmic reticulum (ER. In Dahl salt-sensitive rats, high-salt diet resulted in hypertension, cardiac hypertrophy and subsequent heart failure, and significantly stimulated PARM-1 expression in the hearts, with a concomitant increase in ER stress markers such as GRP78 and CHOP. In cultured cardiac myocytes, PARM-1 expression was stimulated by proinflammatory cytokines, but not by hypertrophic stimuli. A marked increase in PARM-1 expression was observed in response to ER stress inducers such as thapsigargin and tunicamycin, which also induced apoptotic cell death. Silencing PARM-1 expression by siRNAs enhanced apoptotic response in cardiac myocytes to ER stresses. PARM-1 silencing also repressed expression of PERK and ATF6, and augmented expression of CHOP without affecting IRE-1 expression and JNK and Caspase-12 activation. Thus, PARM-1 expression is induced by ER stress, which plays a protective role in cardiac myocytes through regulating PERK, ATF6 and CHOP expression. These results suggested that PARM-1 is a novel ER transmembrane molecule involved in cardiac remodeling in hypertensive heart disease.

  1. Post-Traumatic Stress Disorder among Cardiac Patients: Prevalence, Risk Factors, and Considerations for Assessment and Treatment

    Directory of Open Access Journals (Sweden)

    Heather Tulloch

    2014-12-01

    Full Text Available There is increasing awareness of the impact of post-traumatic stress disorder (PTSD on physical health, particularly cardiovascular disease. We review the literature on the role of trauma in the development of cardiovascular risk factors and disease, aftermath of a cardiac event, and risk for recurrence in cardiac patients. We explore possible mechanisms to explain these relationships, as well as appropriate assessment and treatment strategies for this population. Our main conclusion is that screening and referral for appropriate treatments are important given the high prevalence rates of PTSD in cardiac populations and the associated impact on morbidity and mortality.

  2. Quantitative Ischemia Detection During Cardiac MR Stress Testing

    Science.gov (United States)

    2007-11-02

    of Health, Bethesda, MD, USA 4 Cardiology Division of the School of Medicine, Johns Hopkins University, Baltimore, MD, USA Abstract- Because ECG...independent detection of the onset of ischemia during acute coronary occlusion. Six mongrel dogs underwent acute coronary artery ischemia of 2 minutes...revised 1985). Six mongrel dogs (20-25 kgs) were preanesthetized with 10 mg/kg ketamine, 2.4 mg/kg xylazine, and 0.02 mg/kg atropine intramuscularly

  3. Interaction of TNF with angiotensin II contributes to mitochondrial oxidative stress and cardiac damage in rats.

    Directory of Open Access Journals (Sweden)

    Nithya Mariappan

    Full Text Available Recent evidence suggests that tumor necrosis factor alpha (TNF and angiotensin II (ANGII induce oxidative stress contribute to cardiovascular disease progression. Here, we examined whether an interaction between TNF and ANGII contributes to altered cardiac mitochondrial biogenesis and ATP production to cause cardiac damage in rats. Rats received intraperitoneal injections of TNF (30 µg/kg, TNF + losartan (LOS, 1 mg/kg, or vehicle for 5 days. Left ventricular (LV function was measured using echocardiography. Rats were sacrificed and LV tissues removed for gene expression, electron paramagnetic resonance and mitochondrial assays. TNF administration significantly increased expression of the NADPH oxidase subunit, gp91phox, and the angiotensin type 1 receptor (AT-1R and decreased eNOS in the LV of rats. Rats that received TNF only had increased production rates of superoxide, peroxynitrite and total reactive oxygen species (ROS in the cytosol and increased production rates of superoxide and hydrogen peroxide in mitochondria. Decreased activities of mitochondrial complexes I, II, and III and mitochondrial genes were observed in rats given TNF. In addition, TNF administration also resulted in a decrease in fractional shortening and an increase in Tei index, suggesting diastolic dysfunction. TNF administration with concomitant LOS treatment attenuated mitochondrial damage, restored cardiac function, and decreased expression of AT1-R and NADPH oxidase subunits. Mitochondrial biogenesis and function is severely impaired by TNF as evidenced by downregulation of mitochondrial genes and increased free radical production, and may contribute to cardiac damage. These defects are independent of the downregulation of mitochondrial gene expression, suggesting novel mechanisms for mitochondrial dysfunction in rats given TNF.

  4. Feasibility of determining myocardial transient ischemic dilation from cardiac CT by automated stress/rest registration

    Science.gov (United States)

    Woo, Jonghye; Slomka, Piotr J.; Nakazato, Ryo; Tamarappoo, Balaji K.; Min, James K.; Germano, Guido; Berman, Daniel S.; Dey, Damini

    2012-02-01

    Transient ischemic dilation (TID) of the left ventricle measured by myocardial perfusion Single Photon Emission Computed Tomography (SPECT) and defined as a the ratio of stress myocardial blood volume to rest myocardial blood volume has been shown to be highly specific for detection of severe coronary artery disease. This work investigates automated quantification of TID from cardiac Computed Tomography (CT) perfusion images. To date, TID has not been computed from CT. Previous studies to compute TID have assumed accurate segmentation of the left ventricle and performed subsequent analysis of volume change mainly on static or less often on gated myocardial perfusion SPECT. This, however, may limit the accuracy of TID due to potential errors from segmentation, perfusion defects or volume measurement from both images. In this study, we propose to use registration methods to determine TID from cardiac CT scans where deformation field within the structure of interest is used to measure the local volume change between stress and rest. Promising results have been demonstrated with 7 datasets, showing the potential of this approach as a comparative method for measuring TID.

  5. Prognostic and diagnostic value of moderate intensity stress test with blood pressure control

    Directory of Open Access Journals (Sweden)

    V. N. Marchenko

    2014-01-01

    Full Text Available In spite of age and blood pressure values at rest,hypertensive response to moderate intensity stress testingis characterized by increasing ofprobable beginning of cardiac infarction, stroke or coronary disease in 1.36 times. The hypertensive response to stress test in people with normal blood pressure values at rest (independent of other risk factors is characterized by increasing risk of future hypertension more than in 2 times. Antihypertensive drugs affect blood pressure values differently during the stress testing. The prognosis of blood pressure values during daily physical activity is necessary for antihypertensive treatment. Low availability of convenient instruments and methodological tools for continuous measurement of blood pressure (similar to Spiroarteriocardiorhythmograph, Finapres duringthe dosed physical loads constrain wide use of stress tests with controlled blood pressure in medical practice.

  6. Role of Oxidative Stress in Thyroid Hormone-Induced Cardiomyocyte Hypertrophy and Associated Cardiac Dysfunction: An Undisclosed Story

    Directory of Open Access Journals (Sweden)

    Mohammad T. Elnakish

    2015-01-01

    Full Text Available Cardiac hypertrophy is the most documented cardiomyopathy following hyperthyroidism in experimental animals. Thyroid hormone-induced cardiac hypertrophy is described as a relative ventricular hypertrophy that encompasses the whole heart and is linked with contractile abnormalities in both right and left ventricles. The increase in oxidative stress that takes place in experimental hyperthyroidism proposes that reactive oxygen species are key players in the cardiomyopathy frequently reported in this endocrine disorder. The goal of this review is to shed light on the effects of thyroid hormones on the development of oxidative stress in the heart along with the subsequent cellular and molecular changes. In particular, we will review the role of thyroid hormone-induced oxidative stress in the development of cardiomyocyte hypertrophy and associated cardiac dysfunction, as well as the potential effectiveness of antioxidant treatments in attenuating these hyperthyroidism-induced abnormalities in experimental animal models.

  7. Genetic counseling and cardiac care in predictively tested hypertrophic cardiomyopathy mutation carriers: The patients' perspective

    NARCIS (Netherlands)

    Christiaans, Imke; Van Langen, Irene M.; Birnie, Erwin; Bonsel, Gouke J.; Wilde, Arthur A. M.; Smets, Ellen M. A.

    2009-01-01

    Hypertrophic cardiomyopathy (HCM) is a common hereditary heart disease associated with sudden cardiac death. Predictive genetic counseling and testing are performed using adapted Huntington guidelines, that is, psychosocial care and time for reflection are not obligatory and the test result can be d

  8. Complementary Detection of Embryotoxic Properties of Substances in the Neural and Cardiac Embryonic Stem Cell Tests

    NARCIS (Netherlands)

    Theunissen, P.T.; Pennings, J.L.A.; Dartel, van D.A.M.; Robinson, J.F.; Kleinjans, J.C.S.; Piersma, A.H.

    2013-01-01

    In developmental toxicity testing, in vitro screening assays are highly needed to increase efficiency and to reduce animal use. A promising in vitro assay is the cardiac embryonic stem cell test (ESTc), in which the effect of developmental toxicants on cardiomyocyte differentiation is assessed. Rece

  9. Carnitine deprivation adversely affects cardiac performance in the lipopolysaccharide- and hypoxia/reoxygenation-stressed piglet heart.

    Science.gov (United States)

    Penn, D; Zhang, L; Bobrowski, P J; Quinn, M; McDonough, K H

    1999-02-01

    Sepsis and hypoxia are important stressors for the neonate. Newborn infants receiving total parenteral nutrition are routinely deprived of carnitine and develop low carnitine plasma and tissue levels. Because of its high metabolic rate and dependence on fatty acids for energy, the newborn heart may be particularly vulnerable to stress in the face of an inadequate carnitine supply. To investigate whether carnitine deprivation affects cardiac performance under stress, 23 neonatal piglets received parenteral nutrition for 2-3 weeks that was either carnitine free (CARN -) or supplemented (CARN +) with L-carnitine (400 mg/L). Bacterial endotoxin (lipopolysaccharide (LPS), 250 microg/kg intravenous bolus) or saline vehicle was administered to anesthetized piglets 3 h prior to study of isolated perfused hearts. Left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure, and left ventricular developed pressure (LVDP) were measured in vitro under aerobic, hypoxic, and reoxygenation conditions in all animals. Plasma and tissue carnitine values were lower in CARN - than in CARN + piglets. In hearts from LPS-treated animals prior to hypoxia, there was no difference in ventricular compliance between CARN - and CARN + groups. LVSP and LVDP were lower in CARN - than CARN + hearts. During hypoxia, LVSP and LVDP fell, but left ventricular end diastolic pressure increased in hearts from both LPS- and saline- treated piglets. Reoxygenation led to poorer recovery in CARN - than CARN + hearts from LPS-treated animals, but not from saline controls. During hypoxia/reoxygenation, lactate efflux initially rose and then fell, while carnitine efflux increased continually. Acetyl- and medium-chain acylcarnitines were detected in the coronary effluent. Our findings suggest that carnitine deprivation diminishes heart carnitine concentrations and impairs cardiac recovery from combined endotoxic and hypoxic stress. Possible mechanisms include reduced acyl buffering and

  10. Prenatal stress and balance of the child's cardiac autonomic nervous system at age 5-6 years.

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    Aimée E van Dijk

    Full Text Available OBJECTIVE: Autonomic nervous system (ANS misbalance is a potential causal factor in the development of cardiovascular disease. The ANS may be programmed during pregnancy due to various maternal factors. Our aim is to study maternal prenatal psychosocial stress as a potential disruptor of cardiac ANS balance in the child. METHODS: Mothers from a prospective birth cohort (ABCD study filled out a questionnaire at gestational week 16 [IQR 12-20], that included validated instruments for state anxiety, depressive symptoms, pregnancy-related anxiety, parenting daily hassles and job strain. A cumulative stress score was also calculated (based on 80(th percentiles. Indicators of cardiac ANS in the offspring at age 5-6 years are: pre-ejection period (PEP, heart rate (HR, respiratory sinus arrhythmia (RSA and cardiac autonomic balance (CAB, measured with electrocardiography and impedance cardiography in resting supine and sitting positions. RESULTS: 2,624 mother-child pairs, only single births, were available for analysis. The stress scales were not significantly associated with HR, PEP, RSA and CAB (p≥0.17. Accumulation of maternal stress was also not associated with HR, PEP, RSA and CAB (p≥0.07. CONCLUSION: Results did not support the hypothesis that prenatal maternal psychosocial stress deregulates cardiac ANS balance in the offspring, at least in rest, and at the age of five-six years.

  11. Vanadium and cadmium in vivo effects in teleost cardiac muscle: metal accumulation and oxidative stress markers.

    Science.gov (United States)

    Soares, S S; Martins, H; Gutiérrez-Merino, C; Aureliano, M

    2008-03-01

    Several biological studies associate vanadium and cadmium with the production of reactive oxygen species (ROS), leading to lipid peroxidation and antioxidant enzymes alterations. The present study aims to analyse and compare the oxidative stress responses induced by an acute intravenous exposure (1 and 7 days) to a sub-lethal concentration (5 mM) of two vanadium solutions, containing different vanadate n-oligomers (n=1-5 or n=10), and a cadmium solution on the cardiac muscle of the marine teleost Halobatrachus didactylus (Lusitanian toadfish). It was observed that vanadium is mainly accumulated in mitochondria (1.33+/-0.26 microM), primarily when this element was administrated as decameric vanadate, than when administrated as metavanadate (432+/-294 nM), while the highest content of cadmium was found in cytosol (365+/-231 nM). Indeed, decavanadate solution promotes stronger increases in mitochondrial antioxidant enzymes activities (catalase: +120%; superoxide dismutase: +140%) than metavanadate solution. On contrary, cadmium increases cytosolic catalase (+111%) and glutathione peroxidases (+50%) activities. It is also observed that vanadate oligomers induce in vitro prooxidant effects in toadfish heart, with stronger effects induced by metavanadate solution. In summary, vanadate and cadmium are differently accumulated in blood and cardiac subcellular fractions and induced different responses in enzymatic antioxidant defence mechanisms. In the present study, it is described for the first time the effects of equal doses of two different metals intravenously injected in the same fish species and upon the same exposure period allowing to understand the mechanisms of vanadate and cadmium toxicity in fish cardiac muscle.

  12. Ameliorated stress related proteins are associated with improved cardiac function by sarcoplasmic reticulum calcium ATPase gene transfer in heart failure

    Institute of Scientific and Technical Information of China (English)

    Zhi-Qing Fu; Xiao-Ying Li; Xiao-Chun Lu; Ya-Fei Mi; Tao Liu; Wei-Hua Ye

    2012-01-01

    Background Previous studies showed that overexpression of sarco-endoplasmic reticulum calcium ATPase (SERCA2a) in a variety of heart failure (HF) models was associated with greatly enhanced cardiac performance. However, it still undefined the effect of SERCA2a overexpression on the systemic inflammatory response and neuro-hormonal factors. Methods A rapid right ventricular pacing model of experimental HF was used in beagles. Then the animals underwent recombinant adeno-associated virus 1 (rAAV1) mediated gene transfection by direct intra-myocardium injection. HF animals were randomized to receive the SERCA2a gene, enhanced green fluorescent protein (control) gene, or equivalent phosphate buffered saline. Thirty days after gene delivery, the cardiac function was evaluated by echocardiographic testing. The protein level of SERCA2a was measured by western blotting. The proteomic analysis of left ventricular (LV) sample was determined using two-dimensional (2-D) gel electrophoresis and MALDI-TOF-MS. The serum levels of the systemic inflammatory and neuro-hormonal factors were assayed using radioimmunoassay kits. Results The cardiac function improved after SERCA- 2a gene transfer due to the significantly increased SERCA2a protein level. Beagles treated with SERCA2a had significantly decreased serum levels of the inflammatory markers (interleukin-6 and tumor necrosis factor-α) and neuro-hormonal factors (brain natriuretic peptide, endothelin-1 and angiotensin Ⅱ) compared with HF animals. The myocardial proteomic analysis showed that haptoglobin heavy chain, heat shock protein (alpha-crystallin-related, B6) were down-regulated, and galectin-1 was up-regulated in SERCA2a group compared with HF group, companied by up-regulated contractile proteins and NADH dehydrogenase. Conclusions These findings demonstrate that regional intramyocardial injections of rAAV1-SERCA2a vectors may improve global LV function, correlating with reverse activation of the systemic inflammatory

  13. Stress Tests and Critical Infrastructure Protection-Resilience

    OpenAIRE

    2014-01-01

    This article describes the methodology to conduct stress tests for critical infrastructures in order to improve their resilience. We leverage the example of nuclear and financial sector in order to investigate how critical infrastructures can benefit from stress tests

  14. Are Cardiac Autonomic Nervous System Activity and Perceived Stress Related to Functional Somatic Symptoms in Adolescents? : The TRAILS Study

    NARCIS (Netherlands)

    Janssens, Karin A M; Riese, Harriëtte; Van Roon, Arie M; Hunfeld, Joke A M; Groot, Paul F C; Oldehinkel, Albertine J; Rosmalen, Judith G M

    2016-01-01

    OBJECTIVE: Stressors have been related to medically insufficiently explained or functional somatic symptoms (FSS). However, the underlying mechanism of this association is largely unclear. In the current study, we examined whether FSS are associated with different perceived stress and cardiac autono

  15. Are Cardiac Autonomic Nervous System Activity and Perceived Stress Related to Functional Somatic Symptoms in Adolescents? The TRAILS Study

    NARCIS (Netherlands)

    Janssens, Karin A. M.; Riese, Harriette; Van Roon, Arie M.; Hunfeld, Joke A. M.; Groot, Paul F. C.; Oldehinkel, Albertine J.; Rosmalen, Judith G. M.

    2016-01-01

    Objective Stressors have been related to medically insufficiently explained or functional somatic symptoms (FSS). However, the underlying mechanism of this association is largely unclear. In the current study, we examined whether FSS are associated with different perceived stress and cardiac autonom

  16. Anxiolytics and stress-induced behavioural and cardiac responses : a study of diazepam and ipsapirone (TVX Q 7821)

    NARCIS (Netherlands)

    Korte, S. Mechiel; Koolhaas, Jaap M.; Schuurman, Teun; Traber, Jörg; Bohus, Bela

    1990-01-01

    The present study has been designed to investigate the effects of the 5-HT1A receptor agonist, ipsapirone (TVX Q 7821), a representative of a novel class of anxiolytics, and the classical benzodiazepine anxiolytic, diazepam, on cardiac and behavioural responses in an emotional stress situation. The

  17. Physical conditioning and mental stress reduction - a randomised trial in patients undergoing cardiac surgery

    Directory of Open Access Journals (Sweden)

    van der Merwe Juliana

    2011-03-01

    Full Text Available Abstract Background Preoperative anxiety and physical unfitness have been shown to have adverse effects on recovery from cardiac surgery. This study involving cardiac surgery patients was primarily aimed at assessing the feasibility of delivering physical conditioning and stress reduction programs within the public hospital setting. Secondary aims were to evaluate the effect of these programs on quality of life (QOL, rates of postoperative atrial fibrillation (AF and length of stay (LOS in hospital. Methods Elective patients scheduled for coronary artery bypass graft and/or valve surgery at a public hospital in Melbourne, Australia were enrolled. Patients were randomized to receive either holistic therapy (HT or usual care (UC. HT consisted of a series of light physical exercise sessions together with a mental stress reduction program administered in an outpatient setting for the first two weeks after placement on the waiting list for surgery. A self-administered SF-36 questionnaire was used to measure QOL and hospital records to collect data on LOS and rate of postoperative AF. Results The study population comprised 117 patients of whom 60 received HT and 57 received UC. Both programs were able to be delivered within the hospital setting but ongoing therapy beyond the two week duration of the program was not carried out due to long waiting periods and insufficient resources. HT, as delivered in this study, compared to UC did not result in significant changes in QOL, LOS or AF incidence. Conclusions Preoperative holistic therapy can be delivered in the hospital setting, although two weeks is insufficient to provide benefits beyond usual care on QOL, LOS or postoperative AF. Further research is now required to determine whether a similar program of longer duration, or targeted to high risk patients can provide measurable benefits. Trial registration This trial was conducted as part of a larger study and according to the principles contained in

  18. Binge Ethanol and MDMA Combination Exacerbates Toxic Cardiac Effects by Inducing Cellular Stress

    Science.gov (United States)

    Navarro-Zaragoza, Javier; Ros-Simó, Clara; Milanés, María-Victoria; Valverde, Olga; Laorden, María-Luisa

    2015-01-01

    Binge drinking is a common pattern of ethanol consumption among young people. Binge drinkers are especially susceptible to brain damage when other substances are co-administered, in particular 3,4 methylendioxymethamphetamine (MDMA). The aim of the present work was to study the mechanisms implicated in the adaptive changes observed after administration of these drugs of abuse. So, we have evaluated the cardiac sympathetic activity and the expression and activation of heat shock protein 27 (HSP27), after voluntary binge ethanol consumption, alone and in combination with MDMA. Both parameters are markers of stressful situations and they could be modified inducing several alterations in different systems. Adolescent mice received MDMA, ethanol or both (ethanol plus MDMA). Drinking in the dark (DID) procedure was used as a model of binge. Noradrenaline (NA) turnover, tyrosine hydroxylase (TH), TH phosphorylated at serine 31 and HSP27 expression and its phosphorylation at serine 82 were evaluated in adolescent mice 48 h, 72 h, and 7 days after treatments in the left ventricle. NA and normetanephrine (NMN) were determined by high-performance liquid chromatography (HPLC); TH and HSP27 expression and phosphorylation were measured by quantitative blot immunollabeling using specific antibodies. Ethanol and MDMA co-administration increased NA turnover and TH expression and phosphorylation versus the consumption of each one of these drugs. In parallel with the described modifications in the cardiac sympathetic activity, our results showed that binge ethanol+MDMA exposure is associated with an increase in HSP27 expression and phosphorylation in the left ventricle, supporting the idea that the combination of both drugs exacerbates the cellular stress induced by ethanol or MDMA alone. PMID:26509576

  19. The Possible Role of Nitric Oxide and Oxidative Stress in the Enhanced Apoptosis of Cardiac Cells in Cirrhotic Rats

    Directory of Open Access Journals (Sweden)

    Hamed Shafaroodi

    2017-02-01

    Full Text Available  Cirrhosis has been related with hyperdynamic circulation, manifesting as increased cardiac output and decreased systemic vascular resistance. In the present study we examined the cirrhosis outcome on apoptosis of rat hearts. We also tried to explore the role of nitric oxide (NO and oxidative stress in the probable changed apoptosis of cirrhotic hearts. Twenty eight days after ligation of bile duct, heart tissues were tested for apoptosis. The extent of malondialdehyde (MDA, and the activities of catalase (CAT, glutathione peroxidase (GSHPx and superoxide dismutase (SOD have been calculated in heart tissues. The cirrhotic hearts exhibited structural defects and greater apoptosis. Chronic treatment of cirrhotic rats with L-NAME, a non-selective inhibitor of NO synthase, inhibited heart structural defects and reduced apoptosis of hearts. We also showed that cirrhotic rat hearts had an enhanced level of MDA and reduced activities of CAT, GSHPx and SOD. When the animals were treated by L-NAME chronically, the MDA level reduced and activities of CAT, GSHPx and SOD augmented in cirrhotic heart. In conclusion, increased apoptosis of cirrhotic hearts probably happen due to NO overproduction and increased oxidative stress in hearts of cirrhotic rats.

  20. 78 FR 65583 - Capital Planning and Stress Testing

    Science.gov (United States)

    2013-11-01

    ... scrutiny, and member concern over the safety of its deposits leading to abnormal withdrawals. These... include actions and timeframes for enhancement of stress test capital. These actions may be to accumulate... covered credit union fails the NCUA stress test and must provide a stress test capital enhancement...

  1. 40 CFR 90.329 - Catalyst thermal stress test.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Catalyst thermal stress test. 90.329... Equipment Provisions § 90.329 Catalyst thermal stress test. (a) Oven characteristics. The oven used for thermally stressing the test catalyst must be capable of maintaining a temperature of 500 ±5 °C and 1000...

  2. 40 CFR 91.329 - Catalyst thermal stress test.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Catalyst thermal stress test. 91.329....329 Catalyst thermal stress test. (a) Oven characteristics. The oven used for termally stressing the test catalyst must be capable of maintaining a temperature of 500 ±5 °C and 1000 ±10 °C. (b)...

  3. Impaired cardiac SIRT1 activity by carbonyl stress contributes to aging-related ischemic intolerance.

    Directory of Open Access Journals (Sweden)

    Chunhu Gu

    Full Text Available Reactive aldehydes can initiate protein oxidative damage which may contribute to heart senescence. Sirtuin 1 (SIRT1 is considered to be a potential interventional target for I/R injury management in the elderly. We hypothesized that aldehyde mediated carbonyl stress increases susceptibility of aged hearts to ischemia/reperfusion (I/R injury, and elucidate the underlying mechanisms with a focus on SIRT1. Male C57BL/6 young (4-6 mo and aged (22-24 mo mice were subjected to myocardial I/R. Cardiac aldehyde dehydrogenase (ALDH2, SIRT1 activity and protein carbonyls were assessed. Our data revealed that aged heart exhibited increased endogenous aldehyde/carbonyl stress due to impaired ALDH2 activity concomitant with blunted SIRT1 activity (P<0.05. Exogenous toxic aldehydes (4-HNE exposure in isolated cardiomyocyte verified that aldehyde-induced carbonyl modification on SIRT1 impaired SIRT1 activity leading to worse hypoxia/reoxygenation (H/R injury, which could all be rescued by Alda-1 (ALDH2 activator (all P<0.05. However, SIRT1 inhibitor blocked the protective effect of Alda-1 on H/R cardiomyocyte. Interestingly, myocardial I/R leads to higher carbonylation but lower activity of SIRT1 in aged hearts than that seen in young hearts (P<0.05. The application of Alda-1 significantly reduced the carbonylation on SIRT1 and markedly improved the tolerance to in vivo I/R injury in aged hearts, but failed to protect Sirt1(+/- knockout mice against myocardial I/R injury. This was verified by Alda-1 treatment improved postischemic contractile function recovery in ex vivo perfused aged but not in Sirt1(+/- hearts. Thus, aldehyde/carbonyl stress is accelerated in aging heart. These results provide a new insight that impaired cardiac SIRT1 activity by carbonyl stress plays a critical role in the increased susceptibility of aged heart to I/R injury. ALDH2 activation can restore this aging-related myocardial ischemic intolerance.

  4. Cardiac Function in Patients with Early Cirrhosis during Maximal Beta-Adrenergic Drive

    DEFF Research Database (Denmark)

    Krag, Aleksander; Bendtsen, Flemming; Dahl, Emilie Kristine

    2014-01-01

    BACKGROUND AND AIM: Cardiac dysfunction in patients with early cirrhosis is debated. We investigated potential cardiac dysfunction by assessing left ventricular systolic performance during a dobutamine stress test in patients with early cirrhosis. PATIENTS AND METHODS: Nineteen patients with Child...

  5. EGCG inhibits cardiomyocyte apoptosis in pressure overload-induced cardiac hypertrophy and protects cardiomyocytes from oxidative stress in rats

    Institute of Scientific and Technical Information of China (English)

    Rui SHENG; Zhen-lun GU; Mei-lin XIE; Wen-xuan ZHOU; Ci-yi GUO

    2007-01-01

    Aim: To investigate the effects of epigallocatechin gallate (EGCG) on pressure overload and hydrogen peroxide (H2O2) induced cardiac myocyte apoptosis. Methods: Cardiac hypertrophy was established in rats by abdominal aortic constriction. EGCG 25, 50 and 100 mg/kg were administered intragastrically (ig). Cultured newborn rat cardiomyocytes were preincubated with EGCG, and oxidative stress injury was induced by H2O2. Results: In cardiac hypertrophy induced by AC in rats, relative to the model group, EGCG 25, 50 and 100 mg/kg ig for 6weeks dose-dependently reduced systolic blood pressure (SBP) and heart weight indices, decreased malondialdehyde (MDA) content, and increased superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) activity, both in serum and in the myocardium. Also, treatment with EGCG 50 and 100 mg/kg markedly improved cardiac structure and inhibited fibrosis in HE and van Gieson (VG) stain, and reduced apoptotic myocytes in the hypertrophic myocardium detected by terminal transferase-mediated dUTP-biotin nick end-labeling (TUNEL) assay. Inthe Western blot analysis, EGCG significantly inhibited pressure overload-inducedp53 increase and bcl-2 decrease. In H2O2-induced cardiomyocyte injury, when preincubated with myocytes for 6-48 h, EGCG 12.5-200 mg/L increased cell viability determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay. EGCG also attenuated H2O2-induced lactate dehydrogenase (LDH) release and MDA formation. Meanwhile, EGCG 50 and 100 mg/L significantly inhibited the cardiomyocyte apoptotic rate in flow cytometry. Conclusion: EGCG inhibits cardiac myocyte apoptosis and oxidative stress in pressure overload in-duced cardiac hypertrophy. Also, EGCG prevented cardiomyocyte apoptosis from oxidative stress in vitro. The mechanism might be related to the inhibitory effects of EGCG on p53 induction and bcl-2 decrease.

  6. Stress Testing Credit Risk: A Survey of Authorities' Aproaches

    OpenAIRE

    Antonella Foglia

    2009-01-01

    This paper reviews the quantitative methods developed at selected authorities for stress testing credit risk, focusing in particular on the methods used to link macroeconomic drivers of stress with bank-specific measures of credit risk (macro stress test). Authorities with a mandate for financial stability are particularly interested in quantifying the macro-to-micro linkages and have developed specific modeling expertise in this field. Stress testing credit risk is also an essential element ...

  7. Low Molecular Weight Fucoidan Alleviates Cardiac Dysfunction in Diabetic Goto-Kakizaki Rats by Reducing Oxidative Stress and Cardiomyocyte Apoptosis

    Directory of Open Access Journals (Sweden)

    Xinfeng Yu

    2014-01-01

    Full Text Available Diabetic cardiomyopathy (DCM is characterized by cardiac dysfunction and cardiomyocyte apoptosis. Oxidative stress is suggested to be the major contributor to the development of DCM. This study was intended to evaluate the protective effect of low molecular weight fucoidan (LMWF against cardiac dysfunction in diabetic rats. Type 2 diabetic goto-kakizaki rats were untreated or treated with LMWF (50 and 100 mg/kg/day for three months. The establishment of DCM model and the effects of LMWF on cardiac function were evaluated by echocardiography and isolated heart perfusion. Ventricle staining with H-E or Sirius Red was performed to investigate the structural changes in myocardium. Functional evaluation demonstrated that LMWF has a beneficial effect on DCM by enhancing myocardial contractility and mitigating cardiac fibrosis. Additionally, LMWF exerted significant inhibitory effects on the reactive oxygen species production and myocyte apoptosis in diabetic hearts. The depressed activity of superoxide dismutase in diabetic heart was also improved by intervention with LMWF. Moreover, LMWF robustly inhibited the enhanced expression of protein kinase C β, an important contributor to oxidative stress, in diabetic heart and high glucose-treated cardiomyocytes. In conclusion, LMWF possesses a protective effect against DCM through ameliorations of PKCβ-mediated oxidative stress and subsequent cardiomyocyte apoptosis in diabetes.

  8. Predictive significance of residual ischemia proved by dobutamine stress: Echocardiography test in patients early after the first uncomplicated myocardial infarction

    Directory of Open Access Journals (Sweden)

    Karanović Nevena

    2004-01-01

    Full Text Available Background. To evaluate the long-term prognostic value of dobutamine stress-echocardiography (ECG test for new coronary events (new episodes of angina pectoris, cardiac-related deaths, and reinfarctions early after the first uncomplicated myocardial infarction. Methods. Dobutamine stress-echocardiography tests were performed in all of 104 patients 10-20 days after the first myocardial infarction. Patients were followed-up for 36 (29 ± 7 months. Kaplan-Meier cumulative survival curves were tested by Breslow test (Log Rank. Results. Two cardiac deaths (1.92%, nine nonfatal myocardial infarctions (8.65%, and three cases of recurrent angina pectoris (2.88% occurred during the prospective follow-up. Cumulative survival curves showed that in patients with negative findings of dobutamine stress-echocardiography test, survival time without significant events was 35.31 months, while in the group with positive findings of dobutamine stress-echocardiography test it was 30.91 months (log Rank 7.22; p<0.01. Prognostic value of dobutamine stress-echocardiography test was analyzed by Cox regression model and was 2.92, meaning that the risk of significant events was 2.92 times higher in the group of patients with positive findings of dobutamine stress-echocardiography test. Conclusion. Patients with negative findings of dobutamine stress-echocardiography test were with significantly higher possibility of surviving without significant events in comparison with the patients in whom the findings of dobutamine stress-echocardiography test were positive. In combination with clinical signs and ECG results, the results of dobutamine stress-echocardiography test improved prognostic value in the patients with the first uncomplicated myocardial infarction, and in that way influenced the strategy of their further treatment.

  9. Cardiorespiratory Mechanical Simulator for In Vitro Testing of Impedance Minute Ventilation Sensors in Cardiac Pacemakers.

    Science.gov (United States)

    Marcelli, Emanuela; Cercenelli, Laura

    2016-01-01

    We developed a cardiorespiratory mechanical simulator (CRMS), a system able to reproduce both the cardiac and respiratory movements, intended to be used for in vitro testing of impedance minute ventilation (iMV) sensors in cardiac pacemakers. The simulator consists of two actuators anchored to a human thorax model and a software interface to control the actuators and to acquire/process impedance signals. The actuators can be driven separately or simultaneously to reproduce the cardiac longitudinal shortening at a programmable heart rate and the diaphragm displacement at a programmable respiratory rate (RR). A standard bipolar pacing lead moving with the actuators and a pacemaker case fixed to the thorax model have been used to measure impedance (Z) variations during the simulated cardiorespiratory movements. The software is able to discriminate the low-frequency component because of respiration (Z(R)) from the high-frequency ripple because of cardiac effect (Z(C)). Impedance minute ventilation is continuously calculated from Z(R) and RR. From preliminary tests, the CRMS proved to be a reliable simulator for in vitro evaluation of iMV sensors. Respiration impedance recordings collected during cardiorespiratory movements reproduced by the CRMS were comparable in morphology and amplitude with in vivo assessments of transthoracic impedance variations.

  10. The relation between BMI with exercise test in individuals with cardiac ischemic pains

    Directory of Open Access Journals (Sweden)

    Ravanbakhsh Esmaeili1

    2009-01-01

    Full Text Available (Received 19 Nov, 2008; Accepted 28 Jan, 2009AbstractBackground and purpose: Prevalence of over weight and obesity is increasing in the world. Those over weight are more susceptible to cardiovascular diseases than other individual's. Studies indicate that body fat distribution has a determining role in the identification of risk factors. Also, the relation between BMI, cardiac ischemic pains and exercise test condition in such patients, is in need further investigation. The aim of this study was to determine the relation between BMI with exercise tolerance test in patients with cardiac ischemic pains, who were referred to the Cardiac Center of Mazandaran Province, in Sari Township.Materials and methods: In this case control study considering the BMI in ischemic patients, 65 were selected as case and 65 persons as control using Tread mill and according to Bruce Protocol, results and tolerance test time was recorded. Independent T test was used for comparison of quantitative indexes mean, while x2 test using SPSS soft ware was used for comparison of the ratio of persons with the qualitative features.Results: Data indicated mean weight of 57.1 kg and height of 1.64m in the case group. Also, 58.5% had history of hyperlipidemia (Cholesterol higher than 200mg/dl and 78.8% with history of blood sugar (higher than 120mg/dl (P<0.001. Even 63.6% had hypertension of 140/9o mm Hg. Our findings showed that BMI in the case and control groups were (26.95±3.94 and (25.95±3.49 respectively. Moreover, a significant relationship between high BMI with cardiac ischemic pains and exercise tolerance test (P<0.001 were demonstrated.Conclusion: Cardiac ischemic pains in individuals with high BMI is common. Exercise tolerance test as one of the non invasive and less expensive procedures, can be an indicator of cardiac ischemic disease.J Mazand Univ Med Sci 2009; 19(68: 64-69 (Persian

  11. Effects of pulmonary veins ligation style for the patients' stress and cardiac on lung cancer

    Directory of Open Access Journals (Sweden)

    Yang SHENTU

    2008-10-01

    Full Text Available Background and objective It is needed to explore the effects of operation on stress statue, myocardial damage and arrhythmia to lung cancer. This study would compare the effects of two ligation styles of pulmonary vein on lung cancer patients' stress and cardiac postoperative. Methods 54 cases were divided into two groups randomly:the pulmonary vein trunk-ligation group (trunk group, 27 cases and the pulmonary vein branch-ligation group (branch group, 27 cases. The blood concentrations of hydrocortisone (HC, blood glucose (BG and cardial troponin-I (cTnI were determined at different time point. The surgical data, the quantum of pain and ECG also recorded. Results ① There were no significance difference of the operation time, blood loss during operation and drainage volume in first day after operation between two groups. ② There're no differences of the quantum of pain between two groups. ③ The HC of the two groups' ascend obviously on the end of operation and descend during postoperative. ④ The BG of the two groups' rise on the 1st day obviously, maintain high level on the 2nd day, descend on the 3rd day but still higher than that of preoperation.⑤ The BG and HC show a direct positive correlation postoperative. ⑥ The cTnIs of the trunk group ascend immediatelyafter operation, but there's no statistically significance between two groups. ⑦ The arrhythmia incidence is higher in the trunk group, but the arrhythmia incidences classified by the date after operation of the two groups' show no distinction. Conclusion ① The effects of two pulmonary vein ligation styles on postoperative stress show no significance differences.② The style of pulmonary vein trunk-ligation has a more obvious tendency to do harm to heart than that of branch-ligation. ③ The style of pulmonary vein branch-ligation may reduce the arrhythmia incidence after operation.

  12. Huntington's disease induced cardiac amyloidosis is reversed by modulating protein folding and oxidative stress pathways in the Drosophila heart.

    Directory of Open Access Journals (Sweden)

    Girish C Melkani

    Full Text Available Amyloid-like inclusions have been associated with Huntington's disease (HD, which is caused by expanded polyglutamine repeats in the Huntingtin protein. HD patients exhibit a high incidence of cardiovascular events, presumably as a result of accumulation of toxic amyloid-like inclusions. We have generated a Drosophila model of cardiac amyloidosis that exhibits accumulation of PolyQ aggregates and oxidative stress in myocardial cells, upon heart-specific expression of Huntingtin protein fragments (Htt-PolyQ with disease-causing poly-glutamine repeats (PolyQ-46, PolyQ-72, and PolyQ-102. Cardiac expression of GFP-tagged Htt-PolyQs resulted in PolyQ length-dependent functional defects that included increased incidence of arrhythmias and extreme cardiac dilation, accompanied by a significant decrease in contractility. Structural and ultrastructural analysis of the myocardial cells revealed reduced myofibrillar content, myofibrillar disorganization, mitochondrial defects and the presence of PolyQ-GFP positive aggregates. Cardiac-specific expression of disease causing Poly-Q also shortens lifespan of flies dramatically. To further confirm the involvement of oxidative stress or protein unfolding and to understand the mechanism of PolyQ induced cardiomyopathy, we co-expressed expanded PolyQ-72 with the antioxidant superoxide dismutase (SOD or the myosin chaperone UNC-45. Co-expression of SOD suppressed PolyQ-72 induced mitochondrial defects and partially suppressed aggregation as well as myofibrillar disorganization. However, co-expression of UNC-45 dramatically suppressed PolyQ-72 induced aggregation and partially suppressed myofibrillar disorganization. Moreover, co-expression of both UNC-45 and SOD more efficiently suppressed GFP-positive aggregates, myofibrillar disorganization and physiological cardiac defects induced by PolyQ-72 than did either treatment alone. Our results demonstrate that mutant-PolyQ induces aggregates, disrupts the sarcomeric

  13. Acute-phase proteins, oxidative stress biomarkers, proinflammatory cytokines, and cardiac troponin in Arabian mares affected with pyometra.

    Science.gov (United States)

    El-Bahr, S M; El-Deeb, W M

    2016-09-01

    New biomarkers are essential for diagnosis of pyometra in mares. In this context, 12 subfertile Arabian mares suffered from pyometra were admitted to the Veterinary Teaching Hospital. The basis for diagnosis of pyometra was positive findings of clinical examination and rectal palpation. Blood samples were collected from diseased animals and from five Arabian healthy mares, which were considered as control group. Acute-phase proteins (APP), oxidative stress biomarkers, proinflammatory cytokines, and cardiac troponin I were estimated in the harvested sera of both groups. Clinical examination revealed purulent yellowish fluid discharged from vagina of affected animals and rectal palpation of the reproductive tract revealed uterine distention. The biochemical analysis of the serum revealed significant increase in cardiac troponin I, creatin kinase, alkaline phosphatase, malondialdehyde, tumor necrosis factor α, interleukins 6, prostaglandin F2α, haptoglobin, and serum amyloid A and significant decrease in reduced glutathione, superoxide dismutase (SOD), total antioxidant capacity, and nitric oxide (NO) of mares affected with pyometra compare to control. Cardiac troponin I was positively correlated with aspartate aminotransferase, creatin kinase, malondialdehyde, alkaline phosphatase, tumor necrosis factor α, interleukins 6, prostaglandin F2α, haptoglobin and serum amyloid A and negatively correlated with glutathione, superoxide dismutase, total antioxidant capacity and nitric oxide in serum of mares affected with pyometra. Moreover, there was high positive correlation between proinflammatory cytokines and APP in serum of mares affected with pyometra. The present study suggests cardiac troponin I together with APP, proinflammatory cytokines, and oxidative stress parameters as biomarkers for pyometra in Arabian mares.

  14. Predischarge maximal exercise test identifies risk for cardiac death in patients with acute myocardial infarction

    DEFF Research Database (Denmark)

    Nielsen, J R; Mickley, H; Damsgaard, E M

    1990-01-01

    A maximal exercise test was performed in 54 patients with acute myocardial infarction (AMI) before discharge and in 49 age-matched control subjects. The long-term prognosis was assessed after an average follow-up of 7.6 years in AMI patients and 5.8 years in control subjects. The maximal work...... capacity and systolic blood pressure increase in AMI patients was 59% that of control subjects (p less than 0.001). Seventeen AMI patients had significant ST-segment shifts, 13 with ST depression and 4 with ST elevation. In AMI patients experiencing a cardiac death during follow-up the maximal work...... were of no significant value. In this study maximal work capacity turned out to be the best single exercise variable for identifying groups of AMI patients with very low and relative high risk of cardiac death. When all 3 exercise variables were combined, the predischarge maximal exercise test...

  15. Effects of adiponectin on oxidative stress and apoptosis in human cardiac myocytes cultured with high glucose

    Institute of Scientific and Technical Information of China (English)

    LI Xing; LI Mei-rong; GUO Zhi-xin

    2012-01-01

    Background Diabetic cardiomyopathy is the major cause of morbidity and mortality in diabetic patients.Oxidative stress plays an important role in diabetic cardiomyopathy.This study aimed to investigate the effects of adiponectin on oxidative stress and apoptosis in human cardiac myocytes (HCM) cultured with high glucose.Methods The cells were assigned to three group: control group,high glucose group and high glucose plus adiponectin group.After culture for 24,48,72 hours,oxidative stress was evaluated by detecting levels of malondialdehyde (MDA)and superoxide dismutase (SOD) in the supernatant of culture media.The expression of p66Shc and Heme oxygenase-1 (HO-1) was detected by real-time polymerase chain reaction (PCR).Flow cytometry was designed to observe and detect cellular apoptosis.Results Our findings showed significant increase in MDA levels and decrease in SOD activity in the high glucose group compared with the control group (P <0.05).However,MDA levels were significantly decreased and SOD activity was significantly increased in the adiponectin group compared with those in the high-glucose group (P <0.05).The mRNA expression of HO-1 in the high glucose group was significantly increased in a time-dependent manner compared with that in the control group (P <0.05).Adiponectin further increased the mRNA expression of HO-1 induced by high glucose in a time-dependent manner (P <0.05).The expression of p66Shc was significantly increased in high glucose group compared with that in the control group (P <0.05).Adiponectin significantly suppressed the upregulation of p66Shc induced by high glucose (P <0.05).The apoptotic rate of cardiomyocytes was significantly increased in the high glucose group compared with that in the control group while the apoptotic rate in the adiponectin group was remarkably declined in comparison with that in the high glucose group.Conclusion Adiponectin reduces high glucose-induced oxidative stress and apoptosis and plays a

  16. Nonsustained wide QRS tachycardia during an exercise ECG stress test.

    Science.gov (United States)

    MacKenzie, Ross

    2007-01-01

    The evaluation of a nonsustained wide QRS tachycardia in a life insurance applicant's exercise test presents a special challenge to the medical director because of the unpredictable and potentially lethal nature of these arrhythmias. Ventricular tachycardia accounts for up to 80% of wide QRS tachycardias in unselected populations and more than 95% of cases with a prior myocardial infarction. Malignant ventricular arrhythmias usually occur in the presence of significant structural heart disease. In this setting, ventricular arrhythmias carry a high risk of sudden cardiac death. Less commonly, ventricular tachycardia occurs in hearts that appear normal. In many such cases, however, the heart is in fact not normal, but rather has less visible abnormalities including derangements of cardiac ion channels or structural proteins. In these individuals, ventricular arrhythmias also carry a high risk of sudden cardiac death. There are, however, some ventricular tachycardia syndromes which occur in normal hearts that have a more benign prognosis.

  17. Cardiac autonomic testing and diagnosing heart disease. “A clinical perspective”

    OpenAIRE

    Nicholas L. DePace; Joy P. Mears; Michael Yayac; Joseph Colombo

    2014-01-01

    Background Coronary heart disease (CHD) is a major health concern, affecting nearly half the middle-age population and responsible for nearly one-third of all deaths. Clinicians have responsibilities beyond diagnosing CHD, including risk stratification of patients for major adverse cardiac events (MACE), modifying the risks and treating the patient. In this first of a two-part review, identifying risk factors is reviewed, including more potential benefit from autonomic testing. Methods...

  18. Low Intensity Physical Exercise Attenuates Cardiac Remodeling and Myocardial Oxidative Stress and Dysfunction in Diabetic Rats

    Directory of Open Access Journals (Sweden)

    C. Gimenes

    2015-01-01

    Full Text Available We evaluated the effects of a low intensity aerobic exercise protocol on cardiac remodeling and myocardial function in diabetic rats. Wistar rats were assigned into four groups: sedentary control (C-Sed, exercised control (C-Ex, sedentary diabetes (DM-Sed, and exercised diabetes (DM-Ex. Diabetes was induced by intraperitoneal injection of streptozotocin. Rats exercised for 9 weeks in treadmill at 11 m/min, 18 min/day. Myocardial function was evaluated in left ventricular (LV papillary muscles and oxidative stress in LV tissue. Statistical analysis was given by ANOVA or Kruskal-Wallis. Echocardiogram showed diabetic groups with higher LV diastolic diameter-to-body weight ratio and lower posterior wall shortening velocity than controls. Left atrium diameter was lower in DM-Ex than DM-Sed (C-Sed: 5.73±0.49; C-Ex: 5.67±0.53; DM-Sed: 6.41±0.54; DM-Ex: 5.81±0.50 mm; P<0.05 DM-Sed vs C-Sed and DM-Ex. Papillary muscle function was depressed in DM-Sed compared to C-Sed. Exercise attenuated this change in DM-Ex. Lipid hydroperoxide concentration was higher in DM-Sed than C-Sed and DM-Ex. Catalase and superoxide dismutase activities were lower in diabetics than controls and higher in DM-Ex than DM-Sed. Glutathione peroxidase activity was lower in DM-Sed than C-Sed and DM-Ex. Conclusion. Low intensity exercise attenuates left atrium dilation and myocardial oxidative stress and dysfunction in type 1 diabetic rats.

  19. Ultrasonic test of highly stressed gear shafts

    Energy Technology Data Exchange (ETDEWEB)

    Schreiner, T. [Siemens AG, Power Generation, KWU, Muelheim (Germany); Heinrich, W. [Siemens AG, Power Generation, KWU, Berlin (Germany); Achtzehn, J. [Siemens AG, Power Generation, ICVW, Erlangen (Germany); Hensley, H. [Siemens Power Generation (Germany)

    1998-12-31

    In the power plant industry, gears are used for increasingly higher turbine capacities. Efficiency enhancements, particularly for the combined gas and steam turbine process, lead to an increase in stresses, even for high-performance gears. Consequently, the requirements for non-destructive material testing are on the increase as well. At Siemens KWU, high-performance gears are used so far only for gas turbines with lower rating (65 MW) to adapt the gas turbine speed (5413 rpm) to the generator speed (3000 rpm/ 50 Hz or 3600 rpm/60 Hz). The gear train consists of a forged and case-hardened wheel shaft and pinion shaft made of material 17 CrNiMo 6, where the wheel shaft can be either a solid or a hollow shaft. Dimensions are typically 2.3 m length and 1 m diameter. As a rule, pinion shafts are solid. The gear design, calling for an additional torsion shaft turning inside the hollow wheel shaft, can absorb more torsional load surges and is more tolerant of deviations during gear train alignment. This design requires two additional forgings (torsion shaft and hub) and an additional bearing 2 refs.

  20. Effect of Exercise and Vitamin E on Cardiac Troponin Alterations in Myocardium and Serum of Rats after Stressful Intense Exercise

    Directory of Open Access Journals (Sweden)

    N.S. AL-Sowyan

    2010-01-01

    Full Text Available Increased concentrations of biomarkers reflecting myocardial stress such as cardiac troponin have been observed following strenuous exercise. The aim of this study was to determine whether the stress of forced exercise would result in injury to the myocardium. The effects of stress induced by short bout strenuous exercise and long term exercise on serum, cardiac and skeletal muscle troponin, also blood glucose and insulin were measured. Moreover, to determine whether vitamin E supplementation could modulate these effects or not. Five groups of rats were investigated, control, strenuous exercised rats, exercised and supplemented rats with vitamin E, long term exercise and long term exercised rats supplemented with vitamin E. Strenuous exercised rats and supplemented rats with vitamin E. produced significant increase in serum, cardiac and skeletal muscle troponin concentration. Long term exercise and long term exercised rats supplemented with vitamin E induced insignificant elevation of serum and muscle troponin concentration with significant increase in cardiac troponin level. In rats subjected to both strenuous and long term exercise and after supplementation of both group with vitamin E, there was a significant decrease in blood glucose and insulin level. These results suggest that stressful exercise induces alteration in myocardial troponin and that training before exercise and vitamin E attenuates the exercise induced heart damage. Accordingly, we can advise individuals who are subjected to strenuous exercise to supplement their diet with vitamin E to protect their heart from myocardial damage and sudden death which may be recorded in some athletes. Furthermore, these results demonstrate another support for the importance of exercise in diabetes mellitus.

  1. Stress Optical Coefficient, Test Methodology, and Glass Standard Evaluation

    Science.gov (United States)

    2016-05-01

    ARL-TN-0756 ● MAY 2016 US Army Research Laboratory Stress Optical Coefficient, Test Methodology, and Glass Standard Evaluation...Stress Optical Coefficient, Test Methodology, and Glass Standard Evaluation by Clayton M Weiss Oak Ridge Institute for Science and Education...Technical Note 3. DATES COVERED (From - To) 19 November 2014–15 August 2015 4. TITLE AND SUBTITLE Stress Optical Coefficient, Test Methodology, and

  2. Cardiac-specific catalase overexpression rescues anthrax lethal toxin-induced cardiac contractile dysfunction: role of oxidative stress and autophagy

    Directory of Open Access Journals (Sweden)

    Kandadi Machender R

    2012-11-01

    Full Text Available Abstract Background Lethal and edema toxins secreted by Bacillus anthracis during anthrax infection were found to incite serious cardiovascular complications. However, the underlying mechanisms in anthrax lethal toxin-induced cardiac anomalies remain unknown. This study was designed to evaluate the impact of antioxidant enzyme catalase in anthrax lethal toxin-induced cardiomyocyte contractile dysfunction. Methods Wild type (WT and cardiac-specific catalase overexpression mice were challenged with lethal toxin (2 μg/g, intraperotineally (i.p.. Cardiomyocyte contractile and intracellular Ca2+ properties were assessed 18 h later using an IonOptix edge-detection system. Proteasome function was assessed using chymotrypsin-like and caspase-like activities. GFP-LC3 puncta and Western blot analysis were used to evaluate autophagy and protein ubiquitination. Results Lethal toxin exposure suppressed cardiomyocyte contractile function (suppressed peak shortening, maximal velocity of shortening/re-lengthening, prolonged duration of shortening/re-lengthening, and impaired intracellular Ca2+ handling, the effects of which were alleviated by catalase. In addition, lethal toxin triggered autophagy, mitochondrial and ubiquitin-proteasome defects, the effects of which were mitigated by catalase. Pretreatment of cardiomyocytes from catalase mice with the autophagy inducer rapamycin significantly attenuated or ablated catalase-offered protection against lethal toxin-induced cardiomyocyte dysfunction. On the other hand, the autophagy inhibitor 3-MA ablated or significantly attenuated lethal toxin-induced cardiomyocyte contractile anomalies. Conclusions Our results suggest that catalase is protective against anthrax lethal toxin-induced cardiomyocyte contractile and intracellular Ca2+ anomalies, possibly through regulation of autophagy and mitochondrial function.

  3. [A study of cardiac dynamics during multistage exercise tests performed on a bycicle ergometer (author's transl)].

    Science.gov (United States)

    Gobbato, F; Fiorito, A; Cornelio, G

    1977-05-01

    The authors analysed the behaviour of the mechanical systole (electromechanical systole; tension time, left ventricular ejection time), as well as of the diastole (both cardiac and hemodynamic diastole) during exercise tests performed on a bycicle ergometer, with 40, 80, 120 watt workloads. The mechanical systole--as well as its components--duration is influenced, during exercise test, by both heart rate and stroke volume--pulse pressure being assumed as an indirect index of the latter. The study of the correlation between the two above mentioned parameters has a great importance in evaluating the cardiac pump efficiency both in health and disease. The study of the behaviour of diastole is likewise very important, as it provides useful information concerning: a) the length of the cardiac muscle post-exercise recovery phase; b) the coronary available perfusion time; c) the Windkessel (arterial bellows) emptying time. Moreover, the blood pressure fall rate in diastole is an useful indirect measure of the peripheral resistance changes during muscular work. A statistical analysis is made and the correlation coefficients and the regression equations between the various parameters are defined.

  4. Critical wall shear stress for the EHEDG test method

    DEFF Research Database (Denmark)

    Jensen, Bo Boye Busk; Friis, Alan

    2004-01-01

    In order to simulate the results of practical cleaning tests on closed processing equipment, based on wall shear stress predicted by computational fluid dynamics, a critical wall shear stress is required for that particular cleaning method. This work presents investigations that provide a critical...... wall shear stress of 3 Pa for the standardised EHEDG cleaning test method. The cleaning tests were performed on a test disc placed in a radial flowcell assay. Turbulent flow conditions were generated and the corresponding wall shear stresses were predicted from CFD simulations. Combining wall shear...... stress predictions from a simulation using the low Re k-epsilon and one using the two-layer model of Norris and Reynolds were found to produce reliable predictions compared to empirical solutions for the ideal flow case. The comparison of wall shear stress curves predicted for the real RFC...

  5. Stress Analysis and Calculation of Flow Interruption Capability Test Loop

    Institute of Scientific and Technical Information of China (English)

    FENG; Bo; QI; Xiao-guang; CHENG; Dao-xi

    2012-01-01

    <正>A stress-analysis and calculation has been done for the flow interruption capability test loop (Fig. 1). In the design condition, the test loop is operated on 350 ℃ and 20MPa. By reasonably simplifying and modeling, a stress-analysis program named Triflex was used to analyze the piping stress and optimize the piping supports, which meet the compliance. The work will provide the necessary basis for the construction of the loop and operation security.

  6. Stress Testing as a Tool of Bank Risk Management

    Directory of Open Access Journals (Sweden)

    Antonyuk Oksana I.

    2013-12-01

    Full Text Available The goal of the article is development of theoretical, methodological and practical recommendations on the use of stress testing by Ukrainian commercial banks. Stress testing is defined as a part of bank risk management on the basis of scientific studies of domestic and foreign scientists. The article marks the essence of the bank stress testing and identifies its role in the structure of banks’ risk management in Ukraine. It considers goals of conducting stress testing in banking institutions. It identifies main aspects and specific features of conducting stress testing of bank risks. It characterises main advantages and shortcomings of use of stress testing in the modern bank risk management. It generalises the world and European approaches to the methods of conducting stress testing in commercial banks in comparison with the Ukrainian methodical recommendations. It shows that results of stress testing have practical value, since they help to preliminary assess influence of potentially negative events upon the state of the loan portfolio of the bank and make relevant managerial decisions.

  7. Oxidative stress in toadfish (Halobactrachus didactylus) cardiac muscle. Acute exposure to vanadate oligomers.

    Science.gov (United States)

    Aureliano, M; Joaquim, N; Sousa, A; Martins, H; Coucelo, J M

    2002-06-07

    Vanadate solutions as "metavanadate" (containing ortho and metavanadate species) and "decavanadate" (containing mainly decameric species) (5 mM; 1 mg/kg) were injected intraperitoneously in Halobatrachus didactylus (toadfish), in order to evaluate the contribution of decameric vanadate species to vanadium (V) intoxication on the cardiac tissue. Following short-term exposure (1 and 7 days), different changes on antioxidant enzyme activities-superoxide dismutase (SOD), catalase (CAT), selenium-glutathione peroxidase (Se-GPx), total glutathione peroxidase (GPx), lipid peroxidation and subcellular vanadium distribution were observed in mitochondrial and cytosolic fractions of heart ventricle toadfish. After 1 day of vanadium intoxication, SOD, CAT and Se-GPx activities were decreased up to 25%, by both vanadate solutions, except mitochondrial CAT activity that increased (+23%) upon decavanadate administration. After 7 days of exposure, decavanadate versus metavanadate solutions promoted different effects mainly on cytosolic CAT activity (-56% versus -5%), mitochondrial CAT activity (-10% versus +10%) and total GPx activity (+1% versus -35%), whereas lipid peroxidation products were significantly increased (+82%) upon 500 microM decavanadate intoxication. Accumulation of vanadium in total (0.137+/-0.011 microg/g) and mitochondrial (0.022+/-0.001 microg/g) fractions was observed upon 7 days of metavanadate exposure, whereas for decavanadate, the concentration of vanadium increased in cytosolic (0.020+/-0.005 microg/g) and mitochondrial (0.021+/-0.009 microg/g) fractions. It is concluded that decameric vanadate species are responsible for a strong increase on lipid peroxidation and a decrease in cytosolic catalase activity thus contributing to oxidative stress responses upon vanadate intoxication, in the toadfish heart.

  8. Angiotensin II type 1 receptor is required for the cardiac fibrosis triggered by mechanical stress independent of Ang II in mice

    Institute of Scientific and Technical Information of China (English)

    YE Yong; YUAN Jie; JIANG Guo-liang; HUANG Jia-yuan; ZHANG Wei-jing; GE Jun-bo; ZOU Yun-zeng; GONG Hui; WU Jian; DING Zhi-wen; SHEN Yi; YIN Pei-pei; WANG Xing-xu; YOU Jie-yun; WANG Shi-jun

    2016-01-01

    AIM:We investigated how AT 1-R stimulated by mechanical stresses induces cardiac fibrosis .METHODS:We produced in vivo cardiac pressure overload model in angiotensinogen knockout ( ATG-/-) mice and in vitro mechanically-stretched cell model in cultured neonatal cardiac cells of ATG-/-mice both lack the participation of Ang II .RESULTS: Pressure overload for 4 weeks in ATG-/-mice induced myocardial hypertrophy accompanied by the significant interstitial fibrosis , however , the TGF-β, a key regulatory factor of fibrosis, was not significantly increased in these ATG-/-mice.Meanwhile, the inhibitor for AT1-R significantly inhibited mechani-cal stress-induced cardiac fibrosis in these ATG-/-models whereas inhibition of TGF-βdid not.CONCLUSION:The results showed that mechanical stress-induced fibrotic responses through AT 1-R required the phosphorylation of Smad 2 but not the involvement of TGF-β.

  9. Serine 105 phosphorylation of transcription factor GATA4 is necessary for stress-induced cardiac hypertrophy in vivo.

    Science.gov (United States)

    van Berlo, Jop H; Elrod, John W; Aronow, Bruce J; Pu, William T; Molkentin, Jeffery D

    2011-07-26

    Cardiac hypertrophy is an adaptive growth process that occurs in response to stress stimulation or injury wherein multiple signal transduction pathways are induced, culminating in transcription factor activation and the reprogramming of gene expression. GATA4 is a critical transcription factor in the heart that is known to induce/regulate the hypertrophic program, in part, by receiving signals from MAPKs. Here we generated knock-in mice in which a known MAPK phosphorylation site at serine 105 (S105) in Gata4 that augments activity was mutated to alanine. Homozygous Gata4-S105A mutant mice were viable as adults, although they showed a compromised stress response of the myocardium. For example, cardiac hypertrophy in response to phenylephrine agonist infusion for 2 wk was largely blunted in Gata4-S105A mice, as was the hypertrophic response to pressure overload at 1 and 2 wk of applied stimulation. Gata4-S105A mice were also more susceptible to heart failure and cardiac dilation after 2 wk of pressure overload. With respect to the upstream pathway, hearts from Gata4-S105A mice did not efficiently hypertrophy following direct ERK1/2 activation using an activated MEK1 transgene in vivo. Mechanistically, GATA4 mutant protein from these hearts failed to show enhanced DNA binding in response to hypertrophic stimulation. Moreover, hearts from Gata4-S105A mice had significant changes in the expression of hypertrophy-inducible, fetal, and remodeling-related genes.

  10. Optimal Design of Multiple Stresses Accelerated Life Test Plan Based on Transforming the Multiple Stresses to Single Stress

    Institute of Scientific and Technical Information of China (English)

    GAO Liang; CHEN Wenhua; QIAN Ping; PAN Jun; HE Qingchuan

    2014-01-01

    For planning optimum multiple stresses accelerated life test plans, a commonly followed guiding principle is that all parameters of the life-stress relationship should be estimated, and the number of the stress level combinations must be no less than the number of parameters of the life-stress relationship. However, the general objective of an accelerated life test(ALT) is to assess thep-th quantile of the product life distribution under normal stress. For this objective,estimating all model parameters is not necessary, and this will increase the cost of test. Based on the theoretical conclusion that the stress level combinations of the optimum multiple stresses ALT plan locate on a straight line through the origin of coordinate, it is proposed that a design idea of planning the optimum multiple stresses ALT plan through transforming the problem of designing an optimum multiple stresses ALT plan to designing an optimum single stress ALT plan. Moreover, a method of planning the optimum multiple stresses ALT plan which can avoid estimating all model parameters is established. An example shows that, the proposed plan which only has two stress level combinations could achieve an accuracy no less than the traditional plan, and save the test time and cost on one stress level combination at least; when the actual product life is less than the design value, even the deviation of the model initial parameters value is up to 20%, the variance of the estimation of thep-th quantile of the proposed plan is still smaller than the traditional plans approximately 25%. A design method is provided for planning the optimum multiple stresses ALT which uses the statistical optimum degenerate test plan as the optimum multiple stresses accelerated life test plan.

  11. Electrophysiologic testing guided risk stratification approach for sudden cardiac death beyond the left ventricular ejection fraction

    Institute of Scientific and Technical Information of China (English)

    Konstantinos A Gatzoulis; Dimitris Tsiachris; Petros Arsenos; Dimitris Tousoulis

    2016-01-01

    Sudden cardiac death threats ischaemic and dilated cardiomyopathy patients. Anti- arrhythmic protection may be provided to these patients with implanted cardiac defibrillators(ICD), after an efficient risk stratification approach. The proposed risk stratifier of an impaired left ventricular ejection fraction has limited sensitivity meaning that a significant number of victims will remain undetectable by this risk stratification approach because they have a preserved left ventricular systolic function. Current risk stratification strategies focus on combinations of non invasive methods like T wave alternans, late potentials, heart rate turbulence, deceleration capacity and others, with invasive methods like the electrophysiologic study. In the presence of an electrically impaired substrate with formed post myocardial infarction fibrotic zones, programmed ventricular stimulation provides important prognostic information for the selection of the patients expected to benefit from an ICD implantation, while due to its high negative predictive value, patients at low risk level may also be detected. Clustering evidence from different research groups and electrophysiologic labs support an electrophysiologic testing guided risk stratification approach for sudden cardiac death.

  12. Electrophysiologic testing guided risk stratification approach for sudden cardiac death beyond the left ventricular ejection fraction.

    Science.gov (United States)

    Gatzoulis, Konstantinos A; Tsiachris, Dimitris; Arsenos, Petros; Tousoulis, Dimitris

    2016-01-26

    Sudden cardiac death threats ischaemic and dilated cardiomyopathy patients. Anti- arrhythmic protection may be provided to these patients with implanted cardiac defibrillators (ICD), after an efficient risk stratification approach. The proposed risk stratifier of an impaired left ventricular ejection fraction has limited sensitivity meaning that a significant number of victims will remain undetectable by this risk stratification approach because they have a preserved left ventricular systolic function. Current risk stratification strategies focus on combinations of non invasive methods like T wave alternans, late potentials, heart rate turbulence, deceleration capacity and others, with invasive methods like the electrophysiologic study. In the presence of an electrically impaired substrate with formed post myocardial infarction fibrotic zones, programmed ventricular stimulation provides important prognostic information for the selection of the patients expected to benefit from an ICD implantation, while due to its high negative predictive value, patients at low risk level may also be detected. Clustering evidence from different research groups and electrophysiologic labs support an electrophysiologic testing guided risk stratification approach for sudden cardiac death.

  13. Keap1 redox-dependent regulation of doxorubicin-induced oxidative stress response in cardiac myoblasts

    Energy Technology Data Exchange (ETDEWEB)

    Nordgren, Kendra K.S., E-mail: knordgre@d.umn.edu; Wallace, Kendall B., E-mail: kwallace@d.umn.edu

    2014-01-01

    Doxorubicin (DOX) is a widely prescribed treatment for a broad scope of cancers, but clinical utility is limited by the cumulative, dose-dependent cardiomyopathy that occurs with repeated administration. DOX-induced cardiotoxicity is associated with the production of reactive oxygen species (ROS) and oxidation of lipids, DNA and proteins. A major cellular defense mechanism against such oxidative stress is activation of the Keap1/Nrf2-antioxidant response element (ARE) signaling pathway, which transcriptionally regulates expression of antioxidant genes such as Nqo1 and Gstp1. In the present study, we address the hypothesis that an initial event associated with DOX-induced oxidative stress is activation of the Keap1/Nrf2-dependent expression of antioxidant genes and that this is regulated through drug-induced changes in redox status of the Keap1 protein. Incubation of H9c2 rat cardiac myoblasts with DOX resulted in a time- and dose-dependent decrease in non-protein sulfhydryl groups. Associated with this was a near 2-fold increase in Nrf2 protein content and enhanced transcription of several of the Nrf2-regulated down-stream genes, including Gstp1, Ugt1a1, and Nqo1; the expression of Nfe2l2 (Nrf2) itself was unaltered. Furthermore, both the redox status and the total amount of Keap1 protein were significantly decreased by DOX, with the loss of Keap1 being due to both inhibited gene expression and increased autophagic, but not proteasomal, degradation. These findings identify the Keap1/Nrf2 pathway as a potentially important initial response to acute DOX-induced oxidative injury, with the primary regulatory events being the oxidation and autophagic degradation of the redox sensor Keap1 protein. - Highlights: • DOX caused a ∼2-fold increase in Nrf2 protein content. • DOX enhanced transcription of several Nrf2-regulated down-stream genes. • Redox status and total amount of Keap1 protein were significantly decreased by DOX. • Loss of Keap1 protein was due to

  14. Protective effect of hyperoside on cardiac ischemia reperfusion injury through inhibition of ER stress and activation of Nrf2 signaling

    Institute of Scientific and Technical Information of China (English)

    Jia-Yin Hou; Ying Liu; Liang Liu; Xin-Ming Li

    2016-01-01

    Objective: To study the protective effect of hyperoside (Hyp) on cardiac ischemia reperfusion injury and its potential mechanism. Methods: Rats were divided into two groups for the evaluation, the Hyp (50 μM Hyp; n=8) and the control group (n=8). Rat hearts were isolated and perfused with Krebs-Henseleit buffer (KHB) for 30 min. After being inhibited with cardioplegic solution, they were stored for 4 h in B21 solution at 4 ℃. Afterwards, rat hearts were perfused with KHB again for 45 min. In this period, Hyp was added into solutions of cardioplegia for storage and KHB. Parameters of cardiac functions, including heart rate, the systolic pressure of the left ventricle, the end-diastolic pressure of the left ventricle, the developed pressure of the left ventricle, the left-ventricular systolic pressure and the peak rise rate of the pressure of the left ventricle were recorded. The levels of adenosine triphosphate (ATP), the content of malondialdehyde and apoptotic cells were determined to evaluate the protective effect of Hyp on hearts suffered from ischemia reperfusion injury. Moreover, cultured cardiac myocytes were subjected to the process simulating ischemia/reperfusion. What were analyzed included the endoplasmic reticulum (ER) stress hallmarks expressions, such as binding immunoglobulin protein and C/EBP homologous protein, using the western blot and real-time PCR. Besides, the NF-E2-related factor 2 (Nrf2) expression was measured to explore the potential mechanism. Results: Compared with the control group, the Hyp group had better cardiac functional parameters and higher ATP levels; pretreatment of Hyp greatly relieved the apoptosis of myocyte, decreased oxidative stress as well as ER stress and activated the signaling pathway of anti-oxidative Nrf2 to a further extent. Conclusions: Hyp plays an important role in preserving cardiac function by improving ATP levels of tissue, easing oxidative injury of myocardium and reducing apoptosis following IRI

  15. Evaluation of cardiac function tests in Sudanese adult patients with sickle cell trait

    Directory of Open Access Journals (Sweden)

    Kamal E.A. Abdelsalam

    2016-10-01

    Full Text Available Background: Cardiac dysfunctions have been recognized as a common complication of sickle cell anaemia (SCA, and together with pulmonary disorder accounts for many deaths in these patients. However, sickle cell traits appear clinically normal, although they have genetic abnormality. The aim of this study was to assess the effect of sickle cell trait on cardiac prognostic markers by measuring high density lipoprotein (HDL-C, low density lipoprotein (LDL-C, cardiac creatine kinase (CK-MB, ultra-sensitive C reactive protein (us-CRP, total homocysteine (Hyc, and N-terminal pro-brain natriuretic peptide (NT-pro BNP tests in adult Sudanese patients with sickle cell trait.Methods: A cross-sectional study was performed in 200 healthy volunteers as a control group and 200 diagnosed patients with sickle cell trait. It was carried out in Khartoum Specialized Hospital, Al-Bayan Hospital, Obayed Clinical Center and Dr. Nadir Specialized Hospital, Sudan between January 2015 and January 2016. All participants were between 20-32 years old. LDL-C, HDL-C, CK-MB, NT-proBNP and hs-CRP concentrations were measured by Hitachi 912 full-automated Chemistry Analyzer (Roche Diagnostics, Germany as manufacturer procedure, while homocysteine level was measured by ELISA technique using special kit.Results: When compared to control group, the levels of LDL-C, hs-CRP and NT-proBNP revealed significant increase in patients’ sera (p<0.001, while Hyc and CK-MB levels were increased insignificantly in patients with SCT (p=0.069, p=0.054 respectively. On the other hand, comparison to control group, HDL-C showed insignificant reduction in patients (p=0.099.Conclusion: The results suggest that sickle cell trait increased the risk of patient-related complication secondary to cardiac dysfunction.

  16. Triple Rule Out versus CT Angiogram Plus Stress Test for Evaluation of Chest Pain in the Emergency Department

    OpenAIRE

    Sawyer, Kelly N.; Payal Shah; Lihua Qu; Kurz, Michael C.; Clark, Carol L.; Swor, Robert A.

    2015-01-01

    Introduction: Undifferentiated chest pain in the emergency department (ED) is a diagnostic challenge. One approach includes a dedicated chest computed tomography (CT) for pulmonary embolism or dissection followed by a cardiac stress test (TRAD). An alternative strategy is a coronary CT angiogram with concurrent chest CT (Triple Rule Out, TRO). The objective of this study was to describe the ED patient course and short-term safety for these evaluation methods. Methods: This was ...

  17. Correlation of Simulation Examination to Written Test Scores for Advanced Cardiac Life Support Testing: Prospective Cohort Study

    Directory of Open Access Journals (Sweden)

    Suzanne L. Strom

    2015-11-01

    Full Text Available Introduction: Traditional Advanced Cardiac Life Support (ACLS courses are evaluated using written multiple-choice tests. High-fidelity simulation is a widely used adjunct to didactic content, and has been used in many specialties as a training resource as well as an evaluative tool. There are no data to our knowledge that compare simulation examination scores with written test scores for ACLS courses. Objective: To compare and correlate a novel high-fidelity simulation-based evaluation with traditional written testing for senior medical students in an ACLS course. Methods: We performed a prospective cohort study to determine the correlation between simulationbased evaluation and traditional written testing in a medical school simulation center. Students were tested on a standard acute coronary syndrome/ventricular fibrillation cardiac arrest scenario. Our primary outcome measure was correlation of exam results for 19 volunteer fourth-year medical students after a 32-hour ACLS-based Resuscitation Boot Camp course. Our secondary outcome was comparison of simulation-based vs. written outcome scores. Results: The composite average score on the written evaluation was substantially higher (93.6% than the simulation performance score (81.3%, absolute difference 12.3%, 95% CI [10.6-14.0%], p<0.00005. We found a statistically significant moderate correlation between simulation scenario test performance and traditional written testing (Pearson r=0.48, p=0.04, validating the new evaluation method. Conclusion: Simulation-based ACLS evaluation methods correlate with traditional written testing and demonstrate resuscitation knowledge and skills. Simulation may be a more discriminating and challenging testing method, as students scored higher on written evaluation methods compared to simulation.

  18. Electrophysiological predictors of sudden cardiac death on physical exercise test in young athletes

    Science.gov (United States)

    Balykova, L. A.; Kotlyarov, A. A.; Ivyanskiy, S. A.; Shirokova, A. A.; Miheeva, K. A.; Makarov, L. M.

    2017-01-01

    The problem of sudden death of young athletes continues to be actual. Among its reasons, primary electric myocardium diseases along with organic heart troubles (cardiomyopathies, cordites, anomalies of coronary arteries) take an important place. The most frequent variant of channelopathesis long QT syndrome (LQTS). Both inherited and acquired LQTS may be the reason of sudden cardiac death during physical activity and have to be revealed prior to sports admission. LQTS diagnostics in young athletes become problematic due to secondary exercise-related QT prolongation. Physical load test may reveal myocardium electric instability and enhance LQTS diagnostics accuracy without genetic testing. The aim was to study electrophysiological parameters of myocardium repolarization and reveal the signs of electrical instability as predictors of the life-threatening arrhythmias in young athletes during physical exercise test. In conclusion, electrophysiological myocardium parameters during physical exercise test noted to be markers of electrical myocardial instability and in combination with the other Schwartz criteria, was evidenced the inherited or acquired LQTS. QTc prolongation in athletes at the peak of exercise as well as in early recovery period were noted to be additional predictor life-threatening arrhythmias and sudden cardiac death in young athletes

  19. Association of neuropeptide Y promoter polymorphism (rs16147) with perceived stress and cardiac vagal outflow in humans

    Science.gov (United States)

    Chang, Hsin-An; Fang, Wen-Hui; Chang, Tieh-Ching; Huang, San-Yuan; Chang, Chuan-Chia

    2016-01-01

    Neuropeptide Y (NPY) is involved in resilience to stress, and higher vagal (parasympathetic) activity has been associated with greater stress resilience. Thus, we examined whether rs16147, a functional promoter polymorphism (C>T) of the NPY gene, could influence vagal tone during chronic high stress levels. NPY genotyping, chronic psychological stress level measurement (using the Perceived Stress Scale [PSS]), cardiac autonomic function assessment (using short-term heart rate variability [HRV]) were performed in 1123 healthy, drug-free Han Chinese participants who were divided into low- and high-PSS groups. In the high-PSS group (n = 522), the root mean square of successive heartbeat interval differences and high frequency power (both HRV indices of parasympathetic activity) were significantly increased in T/T homozygotes compared to C/C homozygotes. However, no significant between-genotype difference was found in any HRV variable in the low-PSS group (n = 601). Our results are the first to demonstrate that functional NPY variation alters chronic stress-related vagal control, suggesting a potential parasympathetic role for NPY gene in stress regulation. PMID:27527739

  20. Mechanism of ghrelin in improving cardiac function by inhibiting endoplasmic reticulum stress in rats with acute myocardial infarctio

    Directory of Open Access Journals (Sweden)

    Min CAI

    2012-11-01

    Full Text Available Objective  To establish the rat model of acute myocardial infarction (AMI, and to explore the mechanism of ghrelin in improving cardiac function through inhibiting endoplasmic reticulum stress (ERS. Methods  AMI model was reproduced in 18 adult male Sprague-Dawley rats (220±20g by ligation of the left anterior descending coronary artery. Four days after the reproduction of the model, 14 survived rats with AMI were randomly divided into two groups (7 each: model group, animals were subcutaneously (sc injected with normal saline only; treatment group, animals were given ghrelin (100μg/kg twice a day (12h interval for two weeks. In addition, a sham-operated group was set up (Sham operation+saline, n=8. Two weeks later, the cardiac function was examined by echocardiography (UCG, the morphological changes in myocardial tissue were observed with hematoxylin-eosin (HE staining, the levels of LDH and CK-MB were determined by ELISA, and the expressions of glucose-regulated protein 78 (GRP-78 and C/EBP homologous protein (CHOP were assessed by Western blotting. Results  AMI model was successfully reproduced in SD rats. Compared with the rats in sham group, those in model group showed poor cardiac function (P < 0.05, HE staining revealed loosening of tissue and edema, ELISA revealed elevation of serum LDH and CK-MB levels (P < 0.05, and up regulation of expressions of GRP-78 and CHOP protein (P < 0.05. While compared with model group, rats in treatment group showed better cardiac function (P < 0.05, tissue loosening and edema were alleviated, the levels of serum LDH and CK-MB lowered (P < 0.05, and inhibition of the expressions of GRP-78 and CHOP protein (P < 0.05. Conclusion  Ghrelin may improve the cardiac function by in hibiting ERS, thus ameliorating the myocardial damage caused by AMI.

  1. Algorithms based on CWT and classifiers to control cardiac alterations and stress using an ECG and a SCR.

    Science.gov (United States)

    Villarejo, María Viqueira; Zapirain, Begoña García; Zorrilla, Amaia Méndez

    2013-05-10

    This paper presents the results of using a commercial pulsimeter as an electrocardiogram (ECG) for wireless detection of cardiac alterations and stress levels for home control. For these purposes, signal processing techniques (Continuous Wavelet Transform (CWT) and J48) have been used, respectively. The designed algorithm analyses the ECG signal and is able to detect the heart rate (99.42%), arrhythmia (93.48%) and extrasystoles (99.29%). The detection of stress level is complemented with Skin Conductance Response (SCR), whose success is 94.02%. The heart rate variability does not show added value to the stress detection in this case. With this pulsimeter, it is possible to prevent and detect anomalies for a non-intrusive way associated to a telemedicine system. It is also possible to use it during physical activity due to the fact the CWT minimizes the motion artifacts.

  2. Thymosin beta 4 prevents oxidative stress by targeting antioxidant and anti-apoptotic genes in cardiac fibroblasts.

    Directory of Open Access Journals (Sweden)

    Sandeep Kumar

    Full Text Available RATIONALE: Thymosin beta-4 (Tβ4 is a ubiquitous protein with diverse functions relating to cell proliferation and differentiation that promotes wound healing and modulates inflammatory responses. The effecter molecules targeted by Tβ4 for cardiac protection remains unknown. The purpose of this study is to determine the molecules targeted by Tβ4 that mediate cardio-protection under oxidative stress. METHODS: Rat neonatal fibroblasts cells were exposed to hydrogen peroxide (H(2O(2 in presence and absence of Tβ4 and expression of antioxidant, apoptotic and pro-fibrotic genes was evaluated by quantitative real-time PCR and western blotting. Reactive oxygen species (ROS levels were estimated by DCF-DA using fluorescent microscopy and fluorimetry. Selected antioxidant and antiapoptotic genes were silenced by siRNA transfections in cardiac fibroblasts and the effect of Tβ4 on H(2O(2-induced profibrotic events was evaluated. RESULTS: Pre-treatment with Tβ4 resulted in reduction of the intracellular ROS levels induced by H(2O(2 in the cardiac fibroblasts. This was associated with an increased expression of antioxidant enzymes Cu/Zn superoxide dismutase (SOD and catalase and reduction of Bax/Bcl(2 ratio. Tβ4 treatment reduced the expression of pro-fibrotic genes [connective tissue growth factor (CTGF, collagen type-1 (Col-I and collagen type-3 (Col-III] in the cardiac fibroblasts. Silencing of Cu/Zn-SOD and catalase gene triggered apoptotic cell death in the cardiac fibroblasts, which was prevented by treatment with Tβ4. CONCLUSION: This is the first report that exhibits the targeted molecules modulated by Tβ4 under oxidative stress utilizing the cardiac fibroblasts. Tβ4 treatment prevented the profibrotic gene expression in the in vitro settings. Our findings indicate that Tβ4 selectively targets and upregulates catalase, Cu/Zn-SOD and Bcl(2, thereby, preventing H(2O(2-induced profibrotic changes in the myocardium. Further studies are

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

    Science.gov (United States)

    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 angina pectoris and abnormal stress test findings. This tool, if validated, could help to guide testing strategies in women with angina pectoris.

  4. The additional value of first pass myocardial perfusion imaging during peak dose of dobutamine stress cardiac MRI for the detection of myocardial ischemia

    NARCIS (Netherlands)

    Lubbers, Daniel D.; Janssen, Caroline H. C.; Kuijpers, Dirkjan; Van Dijkman, Paul R. M.; Overbosch, Jelle; Willems, Tineke P.; Oudkerk, Matthijs

    2008-01-01

    Purpose of this study was to assess the additional value of first pass myocardial perfusion imaging during peak dose of dobutamine stress Cardiac-MR (CMR). Dobutamine Stress CMR was performed in 115 patients with an inconclusive diagnosis of myocardial ischemia on a 1.5 T system (Magnetom Avanto, Si

  5. Resting and dobutamine stress test induced serum concentrations of brain natriuretic peptide in German Shepherd dogs.

    Science.gov (United States)

    Spasojević Kosić, Ljubica; Trailović, Dragiša R; Matunović, Radomir

    2012-12-01

    Studies of clinical uses of brain natriuretic peptide (BNP) represent one of the most important advances in cardiology since the introduction of echocardiography as a clinical diagnostic procedure. Defining the clinical potential of BNP in canine cardiology has not been completed yet. The aim of this study is to measure BNP concentrations in healthy German Shepherd dogs of different ages as a baseline in resting and when conventional protocol of the dobutamine stress test (DST) is applied to dogs. Concentrations of BNP were measured in blood serum by the radioimmunoassay method. The values of BNP concentrations were compared to cardiac parameters obtained by standard cardiac diagnostic procedures (radiology, electrocardiography and echocardiography). No significant differences in serum BNP concentrations existed in dogs of different ages. A statistically significant increase in BNP concentrations was registered after DST. These changes in BNP concentrations were related to ST/T electrocardiographic changes, and correlated to changes in the left ventricular internal diameter in systole (LVESD). These data suggest that BNP is not increased in aged dogs with normal cardiac systolic function and renal function, and that myocardial ischemia leads to a significant increase in BNP concentrations even in dogs with normal left ventricular function.

  6. Effect of rosuvastatin on obesity-induced cardiac oxidative stress in Wistar rats--a preliminary study.

    Science.gov (United States)

    Ansari, Javed A; Bhandari, Uma; Pillai, K K; Haque, S E

    2012-03-01

    The prevalence of obesity has been rising alarmingly and it has now become a global concern causing an enormous economic burden on the health care system. Obesity is generally linked to complications in lipid metabolism and oxidative stress. The aim of the present study was to investigate the effect of rosuvastatin (10 mg/kg, po) on obesity-induced oxidative stress in high fat-fed Wistar rats. Oral administration of rosuvastatin (10 mg/kg) for 21 days along with high fat diet brought about significant elevation in serum high density lipoprotein and cardiac antioxidant enzymes levels (superoxide dismutase, catalase, glutathione, glutathione peroxidase, glutathione peroxidase-, glutathione reductase- and glutathione-S-transferase) while decreasing in serum lactate dehydrogenase, apolipoprotein-B, lipids (triglycerides, total cholesterol, low density lipoprotein-cholesterol, very low density lipoprotein-cholesterol and atherogenic index) and cardiac thiobarbituric acid reactive substances levels. The results were comparable with orlistat, a standard antiobesity drug. These preliminary results for the first time demonstrate that administration of rosuvastatin can be beneficial for the suppression of obesity-induced oxidative stress and dyslipidemia in high fat-fed Wistar rats.

  7. A new paradigm to induce mental stress: The Sing-a-Song Stress Test (SSST

    Directory of Open Access Journals (Sweden)

    Anne-Marie eBrouwer

    2014-07-01

    Full Text Available We here introduce a new experimental paradigm to induce mental stress in a quick and easy way while adhering to ethical standards and controlling for potential confounds resulting from sensory input and body movements. In our Sing-a-Song Stress Test, participants are presented with neutral messages on a screen, interleaved with 1-minute time intervals. The final message is that the participant should sing a song aloud after the interval has elapsed. Participants sit still during the whole procedure. We found that heart rate and skin conductance during the 1-minute intervals following the sing-a-song stress message are substantially higher than during intervals following neutral messages. The order of magnitude of the rise is comparable to that achieved by the Trier Social Stress Test. Skin conductance increase correlates positively with experienced stress level as reported by participants. We also simulated stress detection in real time. When using both skin conductance and heart rate, stress is detected for 18 out of 20 participants, approximately 10s after onset of the sing-a-song message. In conclusion, the Sing-a-Song Stress Test provides a quick, easy, controlled and potent way to induce mental stress and could be helpful in studies ranging from examining physiological effects of mental stress to evaluating interventions to reduce stress.

  8. Thallium stress testing does not predict cardiovascular risk in diabetic patients with end-stage renal disease undergoing cadaveric renal transplantation

    Energy Technology Data Exchange (ETDEWEB)

    Holley, J.L.; Fenton, R.A.; Arthur, R.S. (Univ. of Pittsburgh, PA (USA))

    1991-05-01

    This study assessed the usefulness of thallium stress testing as a predictor of perioperative cardiovascular risk in diabetic patients with end-stage renal disease undergoing cadaveric renal transplantation. Demographic factors influencing the exercise performance in these patients were also examined. The medical records of 189 consecutive patients with diabetic nephropathy who were evaluated for cadaveric renal transplantation were reviewed. Thallium stress testing was the initial examination of cardiovascular status in 141 patients. An adequate examination was one in which at least 70% of maximum heart rate was achieved. A thallium stress test was normal if there were no ST segment depressions on the electrocardiogram and no perfusion abnormalities on the thallium scan. Forty-four patients underwent cardiac catheterization as the initial evaluation (Group C) and four patients underwent transplantation without a formal cardiovascular evaluation (Group D). Sixty-four of the 141 patients undergoing thallium stress testing had an adequate and normal examination (Group A). The incidence of perioperative cardiac events in this group was 2%. Seventy-seven patients (Group B) had an abnormal (n = 41) or an inadequate (n = 36) thallium stress test and most (n = 61) then underwent coronary angiography. The use of beta-blockers was the only predictor of an abnormal or inadequate thallium stress test. Forty-three percent of patients with inadequate or abnormal thallium stress tests had significant coronary artery disease on cardiac catheterization. The perioperative risk of cardiac events was not different in Group A versus Groups B, C, and D combined. Survival of Group A and B patients was not different but was significantly longer than that of Group C patients.

  9. Effect of silymarin on sodium fluoride-induced toxicity and oxidative stress in rat cardiac tissues

    Directory of Open Access Journals (Sweden)

    Seyed M. Nabavi

    2012-12-01

    Full Text Available This study aim to evaluate the protective effect of silymarin on sodium fluoride-induced oxidative stress in rat cardiac tissues. Animals were pretreated with silymarin at 20 and 10 mg/kg prior to sodium fluoride consumption (600 ppm through drinking water. Vitamin C at 10 mg/kg was used as standard antioxidant. There was a significant increase in thiobarbituric acid reactive substances level (59.36 ± 2.19 nmol MDA eq/g tissue along with a decrease in antioxidant enzymes activity (64.27 ± 1.98 U/g tissue for superoxide dismutase activity and 29.17 ± 1.01 µmol/min/mg protein for catalase activity and reduced glutathione level (3.8 ± 0.15 µg/mg protein in the tissues homogenates of the sodium fluoride-intoxicated rats. Silymarin administration to animals before sodium fluoride consumption modified the levels of biochemical parameters.Este estudo objetiva avaliar o efeito protetor da silimarina em fluoreto de sódio induzida por estresse oxidativo em tecido cardíaco de ratos. Os animais foram pré-tratados com silimarina a 20 e 10 mg/kg antes do consumo de fluoreto de sódio (600 ppm através da água de beber. A vitamina C a 10 mg/kg foi utilizada como antioxidante padrão. Houve um aumento significativo no nível de substâncias tiobarbitúrico reativo de ácido (59,36 ± 2.19 nmol MDA eq/g tecido, juntamente com uma diminuição da atividade de enzimas antioxidantes (64,27 ± 1,98 U/g tecido para a atividade de superóxido dismutase e 29,7 ± 1,01 mmol/min/mg de proteína para a atividade da catalase e nível de glutationa reduzida (3,8 ± 0,15 mg/mg de proteína nos homogeneizados de tecidos dos fluoreto de sódio-intoxicados ratos. Administração de silimarina a animais, antes do consumo de fluoreto de sódio modifou os níveis de parâmetros bioquímicos.

  10. Fatigue life estimation procedures for the endurance of a cardiac valve prosthesis: stress/life and damage-tolerant analyses.

    Science.gov (United States)

    Ritchie, R O; Lubock, P

    1986-05-01

    Projected fatigue life analyses are performed to estimate the endurance of a cardiac valve prosthesis under physiological environmental and mechanical conditions. The analyses are conducted using both the classical stress-strain/life and the fracture mechanics-based damage-tolerant approaches, and provide estimates of expected life in terms of initial flaw sizes which may pre-exist in the metal prior to the valve entering service. The damage-tolerant analysis further is supplemented by consideration of the question of "short cracks," which represents a developing area in metal fatigue research, not commonly applied to data in standard engineering design practice.

  11. Immobilization Stress With α2-Adrenergic Stimulation Induces Regional and Transient Reduction of Cardiac Contraction Through Gi Coupling in Rats.

    Science.gov (United States)

    Kuroda, Ryohei; Shintani-Ishida, Kaori; Unuma, Kana; Yoshida, Ken-ichi

    2015-01-01

    Stress cardiomyopathy is characterized by transient apical hypokinesia related to catecholamine overflow. Recently, excessive epinephrine administration was shown to recapitulate stress cardiomyopathy through β2-adrenoceptor (AR)-inhibitory G protein (Gi) coupling in rats. We aimed to study whether α2-AR and Gi affect cardiac contraction in rats in which emotional stress was evoked using immobilization (IMO). Echocardiography results showed that when male rats were exposed to IMO for 30 minutes and then injected with the α2-AR agonist xylazine (Xy), ejection fraction and the movement of the anterior wall (AW) were suppressed, maximally at 5 minutes post-injection, whereas posterior wall (PW) movement was preserved. At the same time points, the phosphorylation of Ser282 in myosin-binding protein-C (MyBP-C-Ser282) was higher in the PW than in the AW. Pretreatment with the Gi inhibitor pertussis toxin (PTX) reversed the low contractility and MyBP-C-Ser282 phosphorylation in the AW, but induced lethal heart failure in 3 out of 11 rats. Moreover, at 5 minutes after Xy injection following 30 minutes of IMO, serum epinephrine levels were increased. Thus, in rats exposed to psychological stress, α2-AR stimulation triggered transient hypo-contractility and MyBP-C-Ser282 hypo-phosphorylation in the AW, in association with an epinephrine surge. PTX treatment reversed the AW hypo-contractility and MyBP-C hypo-phosphorylation, but induced acute heart failure. These findings suggest α2AR/Gi-dependent signaling attenuates MyBP-C phosphorylation and contractility in the AW through an epinephrine surge in rats subjected to IMO and α2-AR stimulation. This model can recapitulate stress cardiomyopathy and thereby deepen our understanding of regional cardiac hypo-contractility and prosurvival mechanisms.

  12. Proposal of quality indicators for cardiac rehabilitation after acute coronary syndrome in Japan: a modified Delphi method and practice test

    Science.gov (United States)

    Ohtera, Shosuke; Kanazawa, Natsuko; Ozasa, Neiko; Ueshima, Kenji; Nakayama, Takeo

    2017-01-01

    Objectives Cardiac rehabilitation is underused and its quality in practice is unclear. A quality indicator is a measurable element of clinical practice performance. This study aimed to propose a set of quality indicators for cardiac rehabilitation following an acute coronary event in the Japanese population and conduct a small-size practice test to confirm feasibility and applicability of the indicators in real-world clinical practice. Design and setting This study used a modified Delphi technique (the RAND/UCLA appropriateness method), a consensus method which involves an evidence review, a face-to-face multidisciplinary panel meeting and repeated anonymous rating. Evidence to be reviewed included clinical practice guidelines available in English or Japanese and existing quality indicators. Performance of each indicator was assessed retrospectively using medical records at a university hospital in Japan. Participants 10 professionals in cardiac rehabilitation for the consensus panel. Results In the literature review, 23 clinical practice guidelines and 16 existing indicators were identified to generate potential indicators. Through the consensus-building process, a total of 30 indicators were assessed and finally 13 indicators were accepted. The practice test (n=39) revealed that 74% of patients underwent cardiac rehabilitation. Median performance of process measures was 93% (IQR 46–100%). ‘Communication with the doctor who referred the patient to cardiac rehabilitation’ and ‘continuous participation in cardiac rehabilitation’ had low performance (32% and 38%, respectively). Conclusions A modified Delphi technique identified a comprehensive set of quality indicators for cardiac rehabilitation. The single-site, small-size practice test confirmed that most of the proposed indicators were measurable in real-world clinical practice. However, some clinical processes which are not covered by national health insurance in Japan had low performance. Further

  13. Angiotensin receptor-mediated oxidative stress is associated with impaired cardiac redox signaling and mitochondrial function in insulin-resistant rats.

    Science.gov (United States)

    Vázquez-Medina, José Pablo; Popovich, Irina; Thorwald, Max A; Viscarra, Jose A; Rodriguez, Ruben; Sonanez-Organis, Jose G; Lam, Lisa; Peti-Peterdi, Janos; Nakano, Daisuke; Nishiyama, Akira; Ortiz, Rudy M

    2013-08-15

    Activation of angiotensin receptor type 1 (AT1) contributes to NADPH oxidase (Nox)-derived oxidative stress during metabolic syndrome. However, the specific role of AT1 in modulating redox signaling, mitochondrial function, and oxidative stress in the heart remains more elusive. To test the hypothesis that AT1 activation increases oxidative stress while impairing redox signaling and mitochondrial function in the heart during diet-induced insulin resistance in obese animals, Otsuka Long Evans Tokushima Fatty (OLETF) rats (n = 8/group) were treated with the AT1 blocker (ARB) olmesartan for 6 wk. Cardiac Nox2 protein expression increased 40% in OLETF compared with age-matched, lean, strain-control Long Evans Tokushima Otsuka (LETO) rats, while mRNA and protein expression of the H₂O₂-producing Nox4 increased 40-100%. ARB treatment prevented the increase in Nox2 without altering Nox4. ARB treatment also normalized the increased levels of protein and lipid oxidation (nitrotyrosine, 4-hydroxynonenal) and increased the redox-sensitive transcription factor Nrf2 by 30% and the activity of antioxidant enzymes (SOD, catalase, GPx) by 50-70%. Citrate synthase (CS) and succinate dehydrogenase (SDH) activities decreased 60-70%, whereas cardiac succinate levels decreased 35% in OLETF compared with LETO, suggesting that mitochondrial function in the heart is impaired during obesity-induced insulin resistance. ARB treatment normalized CS and SDH activities, as well as succinate levels, while increasing AMPK and normalizing Akt, suggesting that AT1 activation also impairs cellular metabolism in the diabetic heart. These data suggest that the cardiovascular complications associated with metabolic syndrome may result from AT1 receptor-mediated Nox2 activation leading to impaired redox signaling, mitochondrial activity, and dysregulation of cellular metabolism in the heart.

  14. Cold Stress and the Cold Pressor Test

    Science.gov (United States)

    Silverthorn, Dee U.; Michael, Joel

    2013-01-01

    Temperature and other environmental stressors are known to affect blood pressure and heart rate. In this activity, students perform the cold pressor test, demonstrating increased blood pressure during a 1- to 2-min immersion of one hand in ice water. The cold pressor test is used clinically to evaluate autonomic and left ventricular function. This…

  15. Exercise Testing and Stress Imaging in Valvular Heart Disease.

    OpenAIRE

    Henri, Christine; Pierard, Luc; Lancellotti, Patrizio; Mongeon, Francois-Pierre; Pibarot, Philippe; Basmadjian, Arsene J.

    2014-01-01

    The role of exercise testing and stress imaging in the management of patients with valvular heart disease (VHD) is reviewed in this article. The American College of Cardiology/American Heart Association and the European Society of Cardiology/European Association of Cardiothoracic Surgery have recently put emphasis on the role of exercise testing to clarify symptom status and the use of stress imaging to assess the dynamic component of valvular abnormalities and unmask subclinical myocardial d...

  16. ST elevation occurring during stress testing

    Directory of Open Access Journals (Sweden)

    Diana Malouf

    2016-04-01

    Full Text Available A case is presented of significant reversible ST elevation occurring during treadmill testing, and the coronary anatomy and subsequent course are described, indicating that ischemia is a potential cause of this electrocardiographic finding.

  17. Does electrophysiological testing have any role in risk stratification for sudden cardiac death?

    Institute of Scientific and Technical Information of China (English)

    Fei Lü; Wei Hua

    2010-01-01

    @@ Introduction Implantation of implantable cardioverter defibrillators (ICD) has widely been accepted for secondary prevention of sudden cardiac death (SCD) in cardiac arrest survivors.1 Currently there are increasing interests in primary prevention of SCD in selected high risk patients who have not experienced cardiac arrest.1

  18. Pummelo Protects Doxorubicin-Induced Cardiac Cell Death by Reducing Oxidative Stress, Modifying Glutathione Transferase Expression, and Preventing Cellular Senescence

    Directory of Open Access Journals (Sweden)

    L. Chularojmontri

    2013-01-01

    Full Text Available Citrus flavonoids have been shown to reduce cardiovascular disease (CVD risks prominently due to their antioxidant effects. Here we investigated the protective effect of pummelo (Citrus maxima, CM fruit juice in rat cardiac H9c2 cells against doxorubicin (DOX- induced cytotoxicity. Four antioxidant compositions (ascorbic acid, hesperidin, naringin, and gallic acid were determined by HPLC. CM significantly increased cardiac cell survival from DOX toxicity as evaluated by MTT assay. Reduction of cellular oxidative stress was monitored by the formation of DCF fluorescent product and total glutathione (GSH levels. The changes in glutathione-S-transferase (GST activity and expression were determined by enzyme activity assay and Western blot analysis, respectively. Influence of CM on senescence-associated β-galactosidase activity (SA-β-gal was also determined. The mechanisms of cytoprotection involved reduction of intracellular oxidative stress, maintaining GSH availability, and enhanced GST enzyme activity and expression. DOX-induced cellular senescence was also attenuated by long-term CM treatment. Thus, CM fruit juice can be promoted as functional fruit to protect cells from oxidative cell death, enhance the phase II GSTP enzyme activity, and decrease senescence phenotype population induced by cardiotoxic agent such as DOX.

  19. Memory Testing Under Different Stress Conditions: An Industrial Evaluation

    CERN Document Server

    Majhi, Ananta K; Gronthoud, Guido; Lousberg, Maurice; Eichenberger, Stefan; Bowen, Fred

    2011-01-01

    This paper presents the effectiveness of various stress conditions (mainly voltage and frequency) on detecting the resistive shorts and open defects in deep sub-micron embedded memories in an industrial environment. Simulation studies on very-low voltage, high voltage and at-speed testing show the need of the stress conditions for high quality products; i.e., low defect-per-million (DPM) level, which is driving the semiconductor market today. The above test conditions have been validated to screen out bad devices on real silicon (a test-chip) built on CMOS 0.18 um technology. IFA (inductive fault analysis) based simulation technique leads to an efficient fault coverage and DPM estimator, which helps the customers upfront to make decisions on test algorithm implementations under different stress conditions in order to reduce the number of test escapes.

  20. Exercise testing and stress imaging in valvular heart disease.

    Science.gov (United States)

    Henri, Christine; Piérard, Luc A; Lancellotti, Patrizio; Mongeon, François-Pierre; Pibarot, Philippe; Basmadjian, Arsène J

    2014-09-01

    The role of exercise testing and stress imaging in the management of patients with valvular heart disease (VHD) is reviewed in this article. The American College of Cardiology/American Heart Association and the European Society of Cardiology/European Association of Cardiothoracic Surgery have recently put emphasis on the role of exercise testing to clarify symptom status and the use of stress imaging to assess the dynamic component of valvular abnormalities and unmask subclinical myocardial dysfunction that could be missed at rest. Recent studies have demonstrated the incremental prognostic value of exercise echocardiography for asymptomatic patients with severe aortic stenosis, moderate-severe mitral stenosis, and severe primary mitral regurgitation. In patients with low-flow, low-gradient aortic stenosis, dobutamine stress echocardiography is recommended to differentiate true severe from pseudosevere aortic stenosis. Data on the prognostic value of stress echocardiography in aortic regurgitation and functional mitral regurgitation are less robust. Data are sparse on the use of stress imaging in right-sided VHD, however recent studies using stress cardiovascular magnetic resonance imaging offer some prognostic information. Although the strongest recommendations for surgical treatment continue to be based on symptom status and resting left ventricular repercussions, stress imaging can be useful to optimize risk stratification and timing of surgery in VHD. Randomized clinical trials are required to confirm that clinical decision-making based on stress imaging can lead to improved outcomes.

  1. Conversion of engineering stresses to Cauchy stresses in tensile and compression tests of thermoplastic polymers

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    Schümann Kerstin

    2016-09-01

    Full Text Available Thermoplastic polymers exhibit non-isochoric behaviour during tensile and compression testing as well as particular deformations like local necking (tension or buckling (compression. A method for the determination of Cauchy stresses from tensile and compression tests is presented, that considers the actual deformations of the test specimens. The exact geometry of the specimens in the respective present configuration is determined in photographs, which are taken continuously throughout the test. The engineering stresses at several time points are converted into Cauchy stresses using newly developed formulas in consideration of the actual specimen geometry. For validation finite element analyses of the tensile and compression tests are performed using the identified stress-strain curves. The numerical results show good agreement with the experiments for the tested polymers. Thus a method for conversion of engineering to Cauchy stresses in tensile and compression tests could be established considering the non-isochoric deformation in plasticity. With this method “true” stress-strain curves as input for finite element material models can be identified for arbitrary materials.

  2. Stressful events and psychological difficulties: testing alternative candidates for sensitivity.

    Science.gov (United States)

    Laceulle, Odilia M; O'Donnell, Kieran; Glover, Vivette; O'Connor, Thomas G; Ormel, Johan; van Aken, Marcel A G; Nederhof, Esther

    2014-02-01

    The current study investigated the longitudinal, reciprocal associations between stressful events and psychological difficulties from early childhood to mid-adolescence. Child age, sex, prenatal maternal anxiety, and difficult temperament were tested as sources of sensitivity, that is, factors that may make children more sensitive to stressful life events. Analyses were based on data from 10,417 children from a prospective, longitudinal study of child development. At ages 4, 7, 9, 11, and 16 years, stressful events and psychological difficulties were measured. Prenatal anxiety was measured at 32 weeks of gestation and difficult temperament was measured at 6 months. Children exposed to stressful events showed significantly increased psychological difficulties at ages 7 and 11 years; there was consistent evidence of a reciprocal pattern: psychological difficulties predicted stressful events at each stage. Analyses also indicated that the associations between stressful events and psychological difficulties were stronger in girls than in boys. We found no evidence for the hypothesis that prenatal anxiety or difficult temperament increased stress sensitivity, that is, moderated the link between life events and psychological difficulties. The findings extend prior work on stress exposure and psychological difficulties and highlight the need for additional research to investigate sources of sensitivity and the mechanisms that might underlie differences in sensitivity to stressful events.

  3. Graded Cycling Test Combined With the Talk Test Is Responsive in Cardiac Rehabilitation

    DEFF Research Database (Denmark)

    Nielsen, Susanne Grøn; Vinther, Anders

    2016-01-01

    with the groups reporting "some" (P equivalent to 2 stages ≈ 1 metabolic equivalent task [MET]) in the present test protocol is suggested as the minimal clinically important difference. CONCLUSIONS: GCT-TT was responsive to changes of power output...

  4. SYNTHETIC STRESS LIFE TESTING OF MECHATRONIC PRODUCTS UNDER VARIABLE STRESS SPECTRUM

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Mechatronic products usually endure the variable stress spectrum when they operate in certain operational condition and environmental condition, which obey the Weibull distribution. In accordance with the features of mechatronic product, this paper analyzes the failure mode, its corresponding sensitive stress and the design principles of life testing profiles. Based on the above analyses, this paper presents a synthetic stress life testing method based on the hybrid Weibull distribution and its statistical method under variable stress spectrum to evaluate the reliability and life indices of mechatronic products. Because the mechatronic products have many characteristics such as high price, long life and small testing samples, the synthetic stress life testing method under variable load spectrum can simulate the real various spectra, decrease the life testing time and reduce the testing samples. So it is effective to carry out the life testing to mechatronic products. The application results of hydraulic pumps indicate that this method can easily handle the experimental data under variable amplitude spectrum, obtain the high precision parameters point estimation and confidence interval estimation and reduce the testing cost greatly.

  5. Market risk stress testing for internationally active financial institutions

    Directory of Open Access Journals (Sweden)

    Marković Petar

    2011-01-01

    Full Text Available The paper develops a comprehensive framework for market risk stress testing in internationally active financial institutions. We begin by defining the scope and type of the stress test and explaining how to select risk factors and the stress time horizon. We then address challenges related to data gathering, followed by in-depth discussion of techniques for developing realistic shock scenarios. Next the process of shock application to a particular portfolio is described, followed by determination of portfolio profit and loss. We conclude by briefly discussing the issue of assigning probability to stress scenarios. We illustrate the framework by considering the development of a ‘worst case’ scenario using global financial market data from Thomson Reuters Datastream.

  6. High-fat, low-carbohydrate diet alters myocardial oxidative stress and impairs recovery of cardiac function after ischemia and reperfusion in obese rats.

    Science.gov (United States)

    Liu, Jian; Lloyd, Steven G

    2013-04-01

    Obesity is associated with elevated risk of heart disease. A solid understanding of the safety and potential adverse effects of high-fat, low-carbohydrate diet (HFLCD) similar to that used by humans for weight loss on the heart is crucial. High fat intake is known to promote increases in reactive oxygen species and mitochondrial damage. We hypothesized that there would be adverse effects of HFLCD on myocardial ischemia/reperfusion injury through enhancing oxidative stress injury and impairing mitochondrial biogenesis in a nongenetic, diet-induced rat model of obesity. To test the hypothesis, 250-g male Sprague-Dawley rats were fed an obesity-promoting diet for 7 weeks to induce obesity, then switched to HFLCD or a low-fat control diet for 2 weeks. Isolated hearts underwent global low flow ischemia for 60 minutes and reperfusion for 60 minutes. High-fat, low-carbohydrate diet resulted in greater weight gain and lower myocardial glycogen, plasma adiponectin, and insulin. Myocardial antioxidant gene transcript and protein expression of superoxide dismutase and catalase were reduced in HFLCD, along with increased oxidative gene NADPH oxidase-4 transcript and xanthine oxidase activity, and a 37% increase in nitrated protein (nitrotyrosine) in HFLCD hearts. The cardiac expression of key mitochondrial regulatory factors such as nuclear respiratory factor-1 and transcription factor A-mitochondrial were inhibited and myocardial mitochondrial DNA copy number decreased. The cardiac expression of adiponectin and its receptors was down-regulated in HFLCD. High-fat, low-carbohydrate diet impaired recovery of left ventricular rate-pressure product after ischemia/reperfusion and led to 3.5-fold increased injury as measured by lactate dehydrogenase release. In conclusion, HFLCD leads to increased ischemic myocardial injury and impaired recovery of function after reperfusion and was associated with attenuation of mitochondrial biogenesis and enhanced oxidative stress in obese rats

  7. Changes in short-chain acyl-coA dehydrogenase during rat cardiac development and stress

    OpenAIRE

    Huang, Jinxian; Xu, Lipeng; Huang, Qiuju; Luo, Jiani; Liu, Peiqing; Chen, Shaorui; Yuan, Xi; Lu, Yao; Wang, Ping; Zhou, Sigui

    2015-01-01

    This study was designed to investigate the expression of short-chain acyl-CoA dehydrogenase (SCAD), a key enzyme of fatty acid β-oxidation, during rat heart development and the difference of SCAD between pathological and physiological cardiac hypertrophy. The expression of SCAD was lowest in the foetal and neonatal heart, which had time-dependent increase during normal heart development. In contrast, a significant decrease in SCAD expression was observed in different ages of spontaneously hyp...

  8. A Reliability Test on PBGA Packaging Through Piezoresistive Stress Sensor

    OpenAIRE

    Liu, C.-H.; Chung, H.; Yang, D.-W.; Tseng, K.-F.; Lwo, B.-J.

    2009-01-01

    ISBN: 978-2-35500-009-6; Plastic packaging is the mainstream on microelectronic packaging technology at present. As the continuous requirements for smaller but higher density products, failure and reliability issues on MEMS/MOEMS packaging because of the hygroscopic swelling mismatch stress become more and more serious. To this end, this paper presented the stress monitoring methodologies as well as the reliability tests on a typical PBGA (Plastic Ball-Grid-Array) packaging due to hygroscopic...

  9. Identifying cardiac syncope based on clinical history: a literature-based model tested in four independent datasets.

    Directory of Open Access Journals (Sweden)

    Janneke Berecki-Gisolf

    Full Text Available BACKGROUND: We aimed to develop and test a literature-based model for symptoms that associate with cardiac causes of syncope. METHODS AND RESULTS: Seven studies (the derivation sample reporting ≥2 predictors of cardiac syncope were identified (4 Italian, 1 Swiss, 1 Canadian, and 1 from the United States. From these, 10 criteria were identified as diagnostic predictors. The conditional probability of each predictor was calculated by summation of the reported frequencies. A model of conditional probabilities and a priori probabilities of cardiac syncope was constructed. The model was tested in four datasets of patients with syncope (the test sample from Calgary (n=670; 21% had cardiac syncope, Amsterdam (n=503; 9%, Milan (n=689; 5% and Rochester (3877; 11%. In the derivation sample ten variables were significantly associated with cardiac syncope: age, gender, structural heart disease, low number of spells, brief or absent prodrome, supine syncope, effort syncope, and absence of nausea, diaphoresis and blurred vision. Fitting the test datasets to the full model gave C-statistics of 0.87 (Calgary, 0.84 (Amsterdam, 0.72 (Milan and 0.71 (Rochester. Model sensitivity and specificity were 92% and 68% for Calgary, 86% and 67% for Amsterdam, 76% and 59% for Milan, and 73% and 52% for Rochester. A model with 5 variables (age, gender, structural heart disease, low number of spells, and lack of prodromal symptoms was as accurate as the total set. CONCLUSION: A simple literature-based Bayesian model of historical criteria can distinguish patients with cardiac syncope from other patients with syncope with moderate accuracy.

  10. Garlic attenuates cardiac oxidative stress via activation of PI3K/AKT/Nrf2-Keap1 pathway in fructose-fed diabetic rat.

    Directory of Open Access Journals (Sweden)

    Raju Padiya

    Full Text Available BACKGROUND: Cardiovascular complication due to diabetes has remained a major cause of death. There is an urgent need to intervene the cardiac complications in diabetes by nutritional or pharmacological agents. Thus the present study was designed to find out the effectiveness of garlic on cardiac complications in insulin-resistant diabetic rats. METHODS AND RESULTS: SD rats were fed high fructose (65% diet alone or along with raw garlic homogenate (250 mg/kg/day or nutrient-matched (65% corn starch control diet for 8 weeks. Fructose-fed diabetic rats showed cardiac hypertrophy, increased NFkB activity and increased oxidative stress. Administration of garlic significantly decreased (p<0.05 cardiac hypertrophy, NFkB activity and oxidative stress. Although we did not observe any changes in myocardial catalase, GSH and GPx in diabetic heart, garlic administration showed significant (p<0.05 increase in all three antioxidant/enzymes levels. Increased endogenous antioxidant enzymes and gene expression in garlic treated diabetic heart are associated with higher protein expression of Nrf2. Increased myocardial H2S levels, activation of PI3K/Akt pathway and decreased Keap levels in fructose-fed heart after garlic administration might be responsible for higher Nrf2 levels. CONCLUSION: Our study demonstrates that raw garlic homogenate is effective in reducing cardiac hypertrophy and fructose-induced myocardial oxidative stress through PI3K/AKT/Nrf2-Keap1 dependent pathway.

  11. The serum protein carbonyl content level in relation to exercise stress test

    Directory of Open Access Journals (Sweden)

    Titiporn Mekrungruangwong

    2012-01-01

    Full Text Available Background: Protein carbonyl (P is oxidatively-modified protein with diagnostic potential for acute myocardial infarction. However, many findings indicated the elevation of serum PC content level related to exercise, which could cause false positive results and limiting the specificity for acute coronary syndrome diagnosis. This study aims to evaluate the level of serum protein carbonyl content in healthy volunteers subjected to exercise stress test (EST. Materials and Methods: Serum from healthy volunteers was collected 5-10 min before performing EST and 1 hour after the EST was achieved. The serum was collected, and the serum PC content level was determined by spectrophotometric DNPH assay. Results: The serum PC content level after exercise stress test was significantly higher than that of before performing EST (0.373 ± 0.05 nM/mg vs. 0.275 ± 0.02 nM/mg, P < 0.0001. The results demonstrated that in both male and female, serum PC content level after EST was significantly higher than that of before performing EST (0.29 ± 0.03 nM/mg vs. 0.36 ± 0.05 nM/mg P < 0.0001 in male, 0.27 ± 0.02 nM/mg vs. 0.38 ± 0.06 nM/mg P < 0.0001 in female, respectively. Conclusions: This study demonstrated that exercise stress test could result in non-specificity and false positive increasing in serum PC content level in healthy subjects, which may cause misinterpretation when using PC as cardiac marker, especially in patients, who underwent exercise stress test or patients who performing heavy physical activities.

  12. Cannabinoids & Stress: impact of HU-210 on behavioral tests of anxiety in acutely stressed mice.

    Science.gov (United States)

    Kinden, Renee; Zhang, Xia

    2015-05-01

    Anxiety disorders are one of the most prevalent classes of mental disorders affecting the general population, but current treatment strategies are restricted by their limited efficacy and side effect profiles. Although the cannabinoid system is speculated to be a key player in the modulation of stress responses and emotionality, the vast majority of current research initiatives had not incorporated stress exposure into their experimental designs. This study was the first to investigate the impact of exogenous cannabinoid administration in an acutely stressed mouse model, where CD1 mice were pre-treated with HU-210, a potent CB1R agonist, prior to acute stress exposure and subsequent behavioral testing. Exogenous cannabinoid administration induced distinct behavioral phenotypes in stressed and unstressed mice. While low doses of HU-210 were anxiolytic in unstressed subjects, this effect was abolished when mice were exposed to an acute stressor. The administration of higher HU-210 doses in combination with acute stress exposure led to severe locomotor deficits that were not previously observed at the same dose in unstressed subjects. These findings suggest that exogenous cannabinoids and acute stress act synergistically in an anxiogenic manner. This study underlies the importance of including stress exposure into future anxiety-cannabinoid research due to the differential impact of cannabinoid administration on stressed and unstressed subjects.

  13. Prospective evaluation of a new protocol for the provisional use of perfusion imaging with exercise stress testing

    Energy Technology Data Exchange (ETDEWEB)

    Duvall, W.L. [Hartford Hospital, Division of Cardiology (Henry Low Heart Center), Hartford, CT (United States); Mount Sinai Medical Center, Division of Cardiology (Mount Sinai Heart), New York, NY (United States); Savino, John A.; Levine, Elliot J.; Croft, Lori B.; Henzlova, Milena J. [Mount Sinai Medical Center, Division of Cardiology (Mount Sinai Heart), New York, NY (United States); Hermann, Luke K. [Mount Sinai Medical Center, Department of Emergency Medicine, New York, NY (United States)

    2014-11-04

    Previous literature suggests that myocardial perfusion imaging (MPI) adds little to the prognosis of patients who exercise >10 metabolic equivalents (METs) during stress testing. With this in mind, we prospectively tested a provisional injection protocol in emergency department (ED) patients presenting for the evaluation of chest pain in which a patient would not receive an injection of radioisotope if adequate exercise was achieved without symptoms and a negative ECG response. All patients who presented to the ED over a 5-year period who were referred for stress testing as part of their ED evaluation were included. Patients considered for a provisional protocol were: exercise stress, age <65 years, no known coronary artery disease, and an interpretable rest ECG. Criteria for not injecting included a maximal predicted heart rate ≥85 %, ≥10 METs of exercise, no anginal symptoms during stress, and no ECG changes. Groups were compared based on stress test results, all-cause and cardiac mortality, follow-up cardiac testing, subsequent revascularization, and cost. A total of 965 patients were eligible with 192 undergoing exercise-only and 773 having perfusion imaging. After 41.6 ± 19.6 months of follow-up, all-cause mortality was similar in the exercise-only versus the exercise plus imaging group (2.6 % vs. 2.1 %, p = 0.59). There were no cardiac deaths in the exercise-only group. At 1 year there was no difference in the number of repeat functional stress tests (1.6 % vs. 2.1 %, p = 0.43), fewer angiograms (0 % vs. 4.0 %, p = 0.002), and a significantly lower cost (65 ± 332 vs 506 ± 1,991, p = 0.002; values are in US dollars) in the exercise-only group. The radiation exposure in the exercise plus imaging group was 8.4 ± 2.1 mSv. A provisional injection protocol has a very low mortality, few follow-up diagnostic tests, and lower cost compared to standard imaging protocols. If adopted it would decrease radiation exposure, save time and decrease health-care costs

  14. APACHE II score, rather than cardiac function, may predict poor prognosis in patients with stress-induced cardiomyopathy.

    Science.gov (United States)

    Joe, Byung-Hyun; Jo, Uk; Kim, Hyun-Soo; Park, Chang-Bum; Hwang, Hui-Jeong; Sohn, Il-Suk; Jin, Eun-Sun; Cho, Jin-Man; Park, Jeong-Hwan; Kim, Chong-Jin

    2012-01-01

    While the disease course of stress-induced cardiomyopathy (SIC) is usually benign, it can be fatal. The prognostic factors to predict poorer outcome are not well established, however. We analyzed the Acute Physiology And Chronic Health Evaluation (APACHE) II score to assess its value for predicting poor prognosis in patients with SIC. Thirty-seven consecutive patients with SIC were followed prospectively during their hospitalization. Clinical factors, including APACHE II score, coronary angiogram, echocardiography and cardiac enzymes at presentation were analyzed. Of the 37 patients, 27 patients (73%) were women. The mean age was 66.1 ± 15.6 yr, and the most common presentation was chest pain (38%). Initial echocardiographic left ventricular ejection fraction (EF) was 42.5% ± 9.3%, and the wall motion score index (WMSI) was 1.9 ± 0.3. Six patients (16%) expired during the follow-up period of hospitalization. Based on the analysis of characteristics and clinical factors, the only predictable variable in prognosis was APACHE II score. The patients with APACHE II score greater than 20 had tendency to expire than the others (P = 0.001). Based on present study, APACHE II score more than 20, rather than cardiac function, is associated with mortality in patients with SIC.

  15. Usefulness of type D personality in predicting five-year cardiac events above and beyond concurrent symptoms of stress in patients with coronary heart disease

    DEFF Research Database (Denmark)

    Denollet, Johan; Pedersen, Susanne S.; Vrints, Christiaan J;

    2006-01-01

    Psychological stress and type D personality have been associated with adverse cardiac prognosis, but little is known about their relative effect on the pathogenesis of coronary heart disease (CHD). "Type D" refers to the tendency to experience negative emotions and to inhibit the expression...... of these emotions in social interactions. We investigated the relative effect of stress and type D personality on prognosis at 5-year follow-up. At baseline, 337 patients with CHD who participated in cardiac rehabilitation filled in the General Health Questionnaire (psychological stress) and the Type D personality...... events at follow-up, including 4 deaths and 8 myocardial infarctions. Type D patients had an increased risk of death/infarction (odds ratio 4.84, 95% confidence interval 1.42 to 16.52, p = 0.01) compared with non-type D patients, independent of disease severity. Stress (p = 0.011) and type D (p = 0...

  16. Double Coronary Artery Anomaly in an Elderly Asymptomatic Patient with Positive Electrocardiogram Stress Test

    Directory of Open Access Journals (Sweden)

    Giuseppe Cannavale

    2013-01-01

    Full Text Available Malignant coronary artery anomalies and myocardial bridging are more common findings in young patients with cardiac symptoms, but these two associated yet different types of anomalies in an elderly patient has been rarely described. The following case describes the diagnostic use of 128-slice coronary-computed tomography images of an 82-year-old male, former professional soccer player, who reached the age of 82 years without any symptoms of coronary heart disease. In this patient, an association of a malignant coronary artery anomaly of origin and course (left descending coronary artery originating from the right sinus of valsalva running between the aorta and the right ventricular outflow tract, together with a long myocardial bridging over the obtuse marginal branch was diagnosed by multi-slice computed tomography thanks to an initial positive electrocardiogram screening stress test.

  17. Negative Exercise Stress Test: Does it Mean Anything? Case study

    Directory of Open Access Journals (Sweden)

    Hassan A. Mohamed

    2007-01-01

    Full Text Available Despite its low sensitivity and specificity (67% and 72%, respectively, exercise testing has remained one of the most widely used noninvasive tests to determine the prognosis in patients with suspected or established coronary disease.As a screening test for coronary artery disease, the exercise stress test is useful in that it is relatively simple and inexpensive. It has been considered particularly helpful in patients with chest pain syndromes who have moderate probability for coronary artery disease, and in whom the resting electrocardiogram (ECG is normal. The following case presentation and discussion will question the predictive value of a negative stress testing in patients with moderate probability for coronary artery disease.

  18. Everyday cognitive functioning in cardiac patients: relationships between self-report, report of a significant other and cognitive test performance.

    Science.gov (United States)

    Elliott, Peter C; Smith, Geoff; Ernest, Christine S; Murphy, Barbara M; Worcester, Marian U C; Higgins, Rosemary O; Le Grande, Michael R; Goble, Alan J; Andrewes, David; Tatoulis, James

    2010-01-01

    Candidates for cardiac bypass surgery often experience cognitive decline. Such decline is likely to affect their everyday cognitive functioning. The aim of the present study was to compare cardiac patients' ratings of their everyday cognitive functioning against significant others' ratings and selected neuropsychological tests. Sixty-nine patients completed a battery of standardised cognitive tests. Patients and significant others also completed the Everyday Function Questionnaire independently of each other. Patient and significant other ratings of patients' everyday cognitive difficulties were found to be similar. Despite the similarities in ratings of difficulties, some everyday cognitive tasks were attributed to different processes. Patients' and significant others' ratings were most closely associated with the neuropsychological test of visual memory. Tests of the patients' verbal memory and fluency were only related to significant others' ratings. Test scores of attention and planning were largely unrelated to ratings by either patients or their significant others.

  19. Global test of seismic static stress triggering model

    Institute of Scientific and Technical Information of China (English)

    万永革; 吴忠良; 周公威; 黄静; 秦立新

    2002-01-01

    Seismic static stress triggering model is tested using Harvard centroid moment tensor (CMT) solution catalogue of 1976~2000 and concept of (earthquake doublet(. Result shows that seismic static stress triggering effect does exist in the view of global earthquakes, but the effect is very weak. Dividing the earthquakes into thrust focal mechanism, normal focal mechanism, strike-slip focal mechanism, we find that non-strike-slip focal mechanism earthquakes have significant triggering effect, whereas, the triggering effect in strike-slip focal mechanism earthquakes is not obvious. Divided the subsequent events delay time of (earthquake doublet( into 5 classes of t(1, t<1, t(10, t<10, 1(t(10 (t is in unit of d), then seismic static stress triggering effect does not change with delay time in short time period after earthquakes. The research on seismic static stress triggering in different regions of the world indicates that triggering effect is significant in subduction belts. Seismic static stress triggering model is tested by using (earthquake doublets( in China and its adjacent region. The result indicates that seismic static stress triggering effect cannot be observed easily in China and its adjacent region due to the seismic focal mechanism type (most of the earthquakes are strike-slip earthquakes).

  20. Myocardial bridging in a survivor of sudden cardiac near-death : Role of intracoronary Doppler flow measurements and angiography during dobutamine stress in the clinical evaluation

    NARCIS (Netherlands)

    Tio, RA; VanGelder, IC; Boonstra, PW; Crijns, HJGM

    1997-01-01

    Extensive myocardial bridging in the left anterior descending coronary artery was found in a 46 year old survivor of sudden cardiac near-death. Positron emission tomography and dobutamine stress echocardiography revealed ischaemia in the myocardium distal to the bridging. Spasm was excluded as cause

  1. A test of stress theory: relief workers in refugee camps.

    Science.gov (United States)

    Soliman, Hussein H; Gillespie, David F

    2011-10-01

    The purpose of this paper is to apply a stress model drawn from the literature to the relief and social service workers who have been active in refugee camps for a prolonged period of time. Working in difficult environments, social service workers deliver essential services to refugee populations around the world. A model of four work-stress determinants--tasks, management, appreciation and collaboration--was tested on 274 social workers in five regions of the Middle East (Jordan, Lebanon and Syria, as well as the occupied Palestinian territories of the Gaza Strip and the West Bank). Statistical fit indices were adequate but two relationships were statistically insignificant. The collaboration variable was dropped to create a modified model with tasks indirectly and management and appreciation directly affecting work-related stress. The five direct relationships and two indirect relationships of this modified model are consistent with stress theory, and all relationships--direct and indirect--are statistically significant.

  2. Sex differences in response to maximal exercise stress test in trained adolescents

    Directory of Open Access Journals (Sweden)

    Fomin Åsa

    2012-08-01

    Full Text Available Abstract Background Sex comparisons between girls and boys in response to exercise in trained adolescents are missing and we investigated similarities and differences as a basis for clinical interpretation and guidance. Methods A total of 24 adolescent females and 27 adolescent males aged 13–19 years underwent a maximal bicycle exercise stress test with measurement of cardiovascular variables, cardiac output, lung volumes, metabolic factors/lactate concentrations and breath-by-breath monitoring of ventilation, and determination of peak VO2. Results Maximum heart rate was similar in females (191 ± 9 bpm and males (194 ± 7 bpm, cardiac index at maximum exercise was lower in females (7.0 ± 1.0 l/min/m2 than in males (8.3 ± 1.4 l/min/m2, P 2 was lower in females (2.37 ± 0.34 l/min than in males (3.38 ± 0.49 l/min, P 2 was normalized to leg muscle mass sex differences disappeared (females: 161 ± 21 ml/min/kg vs. males: 170 ± 23 ml/min/kg. The increase in cardiac index during exercise is the key factor responsible for the greater peak VO2 in adolescent boys compared to girls. Conclusions Differences in peak VO2 in adolescent boys and girls disappear when peak VO2 is normalized to estimated leg muscle mass and therefore provide a tool to conduct individual and intersex comparisons of fitness when evaluating adolescent athletes in aerobic sports.

  3. Nondestructive Testing of Wood Defects Based on Stress Wave Technology

    Directory of Open Access Journals (Sweden)

    Wenshu Lin

    2013-11-01

    Full Text Available The wood samples were tested by the technique of stress wave, and the testing results were analyzed by using the statistic software of SPSS. The results showed that the length, density and knots of wood, the sizes of holes and numbers of holes have significant influence on propagation parameters and dynamic modulus of elasticity. Under the same specifications, the propagation time of the stress wave was longer in the wood with holes than the perfect wood samples, and the time become longer with the increasing the sizes and numbers of holes. The studying results of this paper will provide a sound background for the application of stress-wave technique in detecting the inner defects of wood products and other wooden structures.  

  4. [Psychosomatic aspects of cardiac arrhythmias].

    Science.gov (United States)

    Siepmann, Martin; Kirch, Wilhelm

    2010-07-01

    Emotional stress facilitates the occurrence of cardiac arrhythmias including sudden cardiac death. The prevalence of anxiety and depression is increased in cardiac patients as compared to the normal population. The risk of cardiovascular mortality is enhanced in patients suffering from depression. Comorbid anxiety disorders worsen the course of cardiac arrhythmias. Disturbance of neurocardiac regulation with predominance of the sympathetic tone is hypothesized to be causative for this. The emotional reaction to cardiac arrhythmias is differing to a large extent between individuals. Emotional stress may result from coping with treatment of cardiac arrhythmias. Emotional stress and cardiac arrhythmias may influence each other in the sense of a vicious circle. Somatoform cardiac arrhythmias are predominantly of psychogenic origin. Instrumental measures and frequent contacts between physicians and patients may facilitate disease chronification. The present review is dealing with the multifaceted relationships between cardiac arrhythmias and emotional stress. The underlying mechanisms and corresponding treatment modalities are discussed.

  5. Stress relaxation in tempered glass caused by heat soak testing

    DEFF Research Database (Denmark)

    Schneider, Jens; Hilcken, Jonas; Aronen, Antti;

    2016-01-01

    Heat soak testing of tempered glass is a thermal process required after the tempering process itself to bring glasses of commercial soda-lime-silica-glass to failure that are contaminated with nickel sulphide inclusions, diameter 50 mm to 500 mm typically. Thus, the tests avoid a so-called "spont......Heat soak testing of tempered glass is a thermal process required after the tempering process itself to bring glasses of commercial soda-lime-silica-glass to failure that are contaminated with nickel sulphide inclusions, diameter 50 mm to 500 mm typically. Thus, the tests avoid a so...... of commercial soda-lime-silica glass, it causes stress relaxation in tempered glass and the fracture pattern of the glass changes accordingly, especially thin glasses are affected. Based on the Tool-Narayanaswamy-Model, this paper comprises the theoretical background of the stress...

  6. Oxidative stress, d-ROMs test, and ceruloplasmin.

    Science.gov (United States)

    Colombini, Francesco; Carratelli, Mauro; Alberti, Angelo

    2016-01-01

    Human serum samples were evaluated for oxidative stress with the d-ROMs test. The ceruloplasmin (CP) and copper contents of the samples was independently measured and compared to those calculated on the basis of the d-ROMs test results for pure CP solutions. The d-ROMs readings did not show any significant correlation with either the CP or copper contents of the samples. Critical interference of CP on the d-ROMs test was therefore excluded and the usefulness of the test in the evaluation of global oxidative status of a biological sample could be reassessed.

  7. 77 FR 60948 - Stress Testing of Regulated Entities

    Science.gov (United States)

    2012-10-05

    ... more than $10 billion, and which are regulated by a primary federal financial regulatory agency, to... regulated by a primary Federal financial regulatory agency shall conduct annual stress tests * * * (emphasis.... 5365(i)(2)(C)) requires FHFA, as a primary federal financial regulatory agency, in coordination...

  8. 12 CFR 652.40 - Stress tests for mortgage securities.

    Science.gov (United States)

    2010-01-01

    ... Section 652.40 Banks and Banking FARM CREDIT ADMINISTRATION FARM CREDIT SYSTEM FEDERAL AGRICULTURAL MORTGAGE CORPORATION FUNDING AND FISCAL AFFAIRS Investment Management § 652.40 Stress tests for mortgage... interest rate/yield curve scenarios and be consistent with any asset liability management and interest...

  9. 12 CFR 615.5141 - Stress tests for mortgage securities.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Stress tests for mortgage securities. 615.5141 Section 615.5141 Banks and Banking FARM CREDIT ADMINISTRATION FARM CREDIT SYSTEM FUNDING AND FISCAL AFFAIRS, LOAN POLICIES AND OPERATIONS, AND FUNDING OPERATIONS Investment Management § 615.5141...

  10. 78 FR 59219 - Stress Testing of Regulated Entities

    Science.gov (United States)

    2013-09-26

    ... From the Federal Register Online via the Government Publishing Office ] FEDERAL HOUSING FINANCE... Finance Agency. ACTION: Final rule. SUMMARY: This final rule implements section 165(i)(2) of the Dodd... than $10 billion to conduct annual stress tests to determine whether the companies have the...

  11. 77 FR 62378 - Supervisory and Company-Run Stress Test Requirements for Covered Companies

    Science.gov (United States)

    2012-10-12

    ... Federal Reserve System 12 CFR Part 252 Company-Run Stress Test Requirements; Final Rules #0;#0;Federal... Company-Run Stress Test Requirements for Covered Companies AGENCY: Board of Governors of the Federal... conduct stress tests on an annual basis (collectively, company-run stress tests).\\9\\ The Act requires...

  12. Strain Measurement Using FBG on COPV in Stress Rupture Test

    Science.gov (United States)

    Banks, Curtis; Grant, Joseph

    2007-01-01

    White Sands Test Facility (WSTF) was requested to perform ambient temperature hydrostatic pressurization testing of a Space Transportation System (STS) 40-in. Kevlar Composite Overwrapped Pressure Vessel (COPV). The 40-in. vessel was of the same design and approximate age as the STS Main Propulsion System (MPS) and Orbiter Maneuvering System (OMS) vessels. The NASA Engineering Safety Center (NESC) assembled a team of experts and conducted an assessment that involved a review of national Kevlar COPY data. During the review, the STS COPVs were found to be beyond their original certification of ten years. The team observed that the likelihood of STS COPV Stress rupture, a catastrophic burst before leak failure mode, was greater than previously believed. Consequently, a detailed assessment of remaining stress rupture life became necessary. Prior to STS-114, a certification deviation was written for two flights of OV-103 (Discovery) and OV-104 (Atlantis) per rationale that was based on an extensive review of the Lawrence Livermore National Laboratories, COPV data, and revisions to the STS COPV stress levels. In order to obtain flight rationale to extend the certification deviation through the end of the Program, the Orbiter Project Office has directed an interagency COPV team to conduct further testing and analysis to investigate conservatism in the stress rupture model and evaluate material age degradation. Additional analysis of stress rupture life requires understanding the fiber stresses including stress that occurs due to thru-wall composite compression in COPV components. Data must be obtained at both zero gauge pressure (pre-stress) and at the component operating pressure so that this phenomenon can be properly evaluated. The zero gauge pressure stresses are predominantly a result of the autofrettage process used during vessel manufacture. Determining these pre-stresses and the constitutive behavior of the overwrap at pressure will provide necessary information

  13. Cardiac autonomic imbalance by social stress in rodents: understanding putative biomarkers

    Directory of Open Access Journals (Sweden)

    Susan K Wood, Phd

    2014-08-01

    Full Text Available Exposure to stress or traumatic events can lead to the development of depression and anxiety disorders. In addition to the debilitating consequences on mental health, patients with psychiatric disorders also suffer from autonomic imbalance, making them susceptible to a variety of medical disorders. Emerging evidence utilizing spectral analysis of heart rate variability (HRV, a reliable noninvasive measure of cardiovascular autonomic regulation, indicates that patients with depression and various anxiety disorders (i.e., panic, social, generalized anxiety disorders, and post traumatic stress disorder are characterized by decreased HRV. Social stressors in rodents are ethologically relevant experimental stressors that recapitulate many of the dysfunctional behavioral and physiological changes that occur in psychological disorders. In this review, evidence from clinical studies and preclinical stress models identify putative biomarkers capable of precipitating the comorbidity between disorders of the mind and autonomic dysfunction. Specifically, the role of corticotropin releasing factor, neuropeptide Y and inflammation are investigated. The impetus for this review is to highlight stress-related biomarkers that may prove critical in the development of autonomic imbalance in stress -related psychiatric disorders.

  14. Genetic susceptibility testing from a stress and coping perspective.

    Science.gov (United States)

    Gooding, Holly C; Organista, Kurt; Burack, Jeffrey; Biesecker, Barbara Bowles

    2006-04-01

    Four theories of health behavior and of stress and coping are reviewed for their ability to illuminate interest in uptake and outcomes of genetic testing for adult-onset diseases. These theories are the Health Belief Model, the Theory of Planned Behavior (TPB), the Common Sense Model of Self-regulation (CSM), and the Transactional Model of Stress and Coping (TMSC). Basic concepts of each theory are discussed, followed by evidence from the literature supporting the relevance of these concepts to the understanding of genetic testing for four adult-onset diseases: Huntington's disease, Alzheimer's disease, hereditary breast/ovarian cancer, and hereditary colorectal cancer. Emphasis is placed on the finding that a decision to undergo genetic testing may be considered as a way to cope with both the cognitive and affective concerns that arise from living at increased risk of developing a disease in the future. The potential value of genetic testing for reducing uncertainty about and gaining a sense of control over one's risk of developing a chronic disease is highlighted. We argue that theories which focus on stress and coping provide a useful framework for future studies of genetic testing decisions for adult-onset disease risk.

  15. Acute Anteroseptal Myocardial Infarction after a Negative Exercise Stress Test

    Directory of Open Access Journals (Sweden)

    Abdullah M. Al-Alawi

    2016-05-01

    Full Text Available A myocardial infarction is a rare complication which can occur after an exercise stress test. We report a 48-year-old male who was referred to the Mildura Cardiology Practice, Victoria, Australia, in August 2014 with left-sided chest pain. He underwent an exercise stress test which was negative for myocardial ischaemia. However, the patient presented to the Emergency Department of the Mildura Base Hospital 30 minutes after the test with severe retrosternal chest pain. An acute anteroseptal ST segment elevation myocardial infarction was observed on electrocardiography. After thrombolysis, he was transferred to a tertiary hospital where coronary angiography subsequently revealed significant left anterior descending coronary artery stenosis. Thrombus aspiration and a balloon angioplasty were performed. The patient was discharged three days after the surgical procedure in good health.

  16. Research on Stress Testing of OSPF Protocol Implementation

    Institute of Scientific and Technical Information of China (English)

    Cui Yong (崔勇); Xu Ke; Xu Mingwei; Wu Jianping

    2003-01-01

    The stability and robustness of routing protocol implementations (RPI) in a router are becoming more and more important with the growth of Internet scale. A novel approach named stress testing is proposed to test the properties of RPI. Compared with some traditional test techniques, stress testing is remarkably necessary to inspect and analyze RPI. The test environment is proposed and the test process of OSPF RPI is illustrated by a stochastic Petri Net model with large-scale route simulation and OSPF protocol emulation. Based on this model, the integrated performance tester (IP-TEST) is designed and developed, with which we test a CISCO2600 router. With mathematical methods, we find that the computational complexity of OSPF implementation in this router is O((lnN)4)to the number of its routing table entries. This experiment shows that this technique can inspect the stability, the computational complexity and the scalability of RPI. Furthermore, it can also be widely used with other routing protocols, such as RIP and BGP.

  17. Cardiac and renal nitrosative-oxidative stress after acute poisoning by a nerve agent Tabun.

    Science.gov (United States)

    Dimov, Dimo; Hadjiolova, Radka; Kanev, Kamen; Tomova, Radka; Michova, Anna; Todorov, Todor; Murdjev, Rumen; Boneva, Temenujka; Dimova, Ivanka

    2015-01-01

    We hypothesized that Tabun poisoning, as well as other organophosphorous treatment, cause specific organs' oxidative changes that have not previously been substantiated investigated. In this regard, a marker for nitrosative-oxidative stress in the main haemodynamic organs (heart and kidney) could reveal the existence of such changes. In this study, for the first time we studied the nitrosative/oxidative stress in heart and kidney after acute Tabun (Ethyl N,N- Dimethylphosphoramidocyanidate) poisoning measuring by immunohistochemistry the expression of 3-nitrotyrosine--a marker for nitrosative-oxidative stress. We investigated nitrotyrozine expression in three different groups of animals (with at least 3 animals in each group): the first group was treated with 0.5 LD50 Tabun and organs were collected after 24 h; the second group received vehicle for the same period; in the third group a highly specific re-activator was applied immediately after Tabun application. Heart and kidney were collected after 24 h. The levels of nitrotyrozine production significantly increased (more than 3 times) in cardiomyocytes after Tabun. The application of re-activator slightly reduced these levels not reaching the basal heart levels. Nitrotyrozine expression in kidney increased more than 2 times after Tabun and application of re-activator did not change it significantly. In conclusion, our study evidently demonstrated that Tabun trigger oxidative-nitrosative stress in heart and kidney and these cellular effects should be protected by an additional anti-oxidant therapy, since acetylcholinesterase re-activator is not efficient in this manner.

  18. Beneficial effects of elevating cardiac preload on left-ventricular diastolic function and volume during heat stress

    DEFF Research Database (Denmark)

    Brothers, R M; Pecini, Redi; Dalsgaard, M;

    2014-01-01

    Volume loading normalizes tolerance to a simulated hemorrhagic challenge in heat-stressed individuals, relative to when these individuals are thermoneutral. The mechanism(s) by which this occurs is unknown. This project tested two unique hypotheses; that is, the elevation of central blood volume...... via volume loading while heat stressed would 1) increase indices of left ventricular diastolic function, and 2) preserve left ventricular end-diastolic volume (LVEDV) during a subsequent simulated hemorrhagic challenge induced by lower-body negative pressure (LBNP). Indices of left ventricular...... diastolic function were evaluated in nine subjects during the following conditions: thermoneutral, heat stress, and heat stress after acute volume loading sufficient to return ventricular filling pressures toward thermoneutral levels. LVEDV was also measured in these subjects during the aforementioned...

  19. What Is Cardiac Rehabilitation?

    Science.gov (United States)

    ANSWERS by heart Treatments + Tests What Is Cardiac Rehabilitation? A cardiac rehabilitation (rehab) program takes place in a hospital or ... special help in making lifestyle changes. During your rehabilitation program you’ll… • Have a medical evaluation to ...

  20. Cardiac troponin: a critical review of the case for point-of-care testing in the ED.

    Science.gov (United States)

    Bingisser, Roland; Cairns, Charles; Christ, Michael; Hausfater, Pierre; Lindahl, Bertil; Mair, Johannes; Panteghini, Mauro; Price, Christopher; Venge, Per

    2012-10-01

    The measurement of cardiac troponin concentrations in the blood is a key element in the evaluation of patients with suspected acute coronary syndromes, according to current guidelines, and contributes importantly to the ruling in or ruling out of acute myocardial infarction. The introduction of point-of-care testing for cardiac troponin has the potential to reduce turnaround time for assay results, compared with central laboratory testing, optimizing resource use. Although, in general, many point-of-care cardiac troponin tests are less sensitive than cardiac troponin tests developed for central laboratory-automated analyzers, point-of-care systems have been used successfully within accelerated protocols for the reliable ruling out of acute coronary syndromes, without increasing subsequent readmission rates for this condition. The impact of shortened assay turnaround times with point-of-care technology on length of stay in the emergency department has been limited to date, with most randomized evaluations of this technology having demonstrated little or no reduction in this outcome parameter. Accordingly, the point-of-care approach has not been shown to be cost-effective relative to central laboratory testing. Modeling studies suggest, however, that reengineering overall procedures within the emergency department setting, to take full advantage of reduced therapeutic turnaround time, has the potential to improve the flow of patients through the emergency department, to shorten discharge times, and to reduce cost. To properly evaluate the potential contribution of point-of-care technology in the emergency department, including its cost-effectiveness, future evaluations of point-of-care platforms will need to be embedded completely within a local decision-making structure designed for its use.

  1. Stress Free Temperature Testing and Residual Stress Calculations on Out-of-Autoclave Composites

    Science.gov (United States)

    Cox, Sarah; Tate, LaNetra C.; Danley, Susan; Sampson, Jeff; Taylor, Brian; Miller, Sandi

    2012-01-01

    Future launch vehicles will require the incorporation large composite parts that will make up primary and secondary components of the vehicle. NASA has explored the feasibility of manufacturing these large components using Out-of-Autoclave impregnated carbon fiber composite systems through many composites development projects. Most recently, the Composites for Exploration Project has been looking at the development of a 10 meter diameter fairing structure, similar in size to what will be required for a heavy launch vehicle. The development of new material systems requires the investigation of the material properties and the stress in the parts. Residual stress is an important factor to incorporate when modeling the stresses that a part is undergoing. Testing was performed to verify the stress free temperature with two-ply asymmetric panels. A comparison was done between three newly developed out of autoclave IM7 /Bismalieimide (BMI) systems. This paper presents the testing results and the analysis performed to determine the residual stress of the materials.

  2. Analytical and assay issues for use of cardiac troponin testing for risk stratification in primary care.

    Science.gov (United States)

    Wu, Alan H B; Christenson, Robert H

    2013-08-01

    Cardiac troponin is the standard marker for diagnosis of acute myocardial infarction and risk stratification of patients who present to an emergency department with signs and symptoms of acute cardiac ischemia. Over the past few years, the analytical sensitivity of assays for cardiac troponin has improved significantly to the point where a detectable amount of troponin can be measured in essentially all healthy subjects. Recent studies have shown that use of a highly sensitive troponin assays may provide value to traditional markers of primary disease risk for patients, i.e., for those who have no history of heart disease. There are barriers to the adoption of cardiac troponin for screening high risk cohorts such as the elderly, diabetics and perhaps even the asymptomatic population. Strategies used for the assignment of cutoff concentrations in acute care, i.e., the 99 th percentile, may not be appropriate for primary care as changes over baseline levels may provide more accurate information of risk than cross-sectional results. A review of biological variation has shown that cardiac troponin as a biomarker has low index of individuality, indicating that reference values are of little utility. Whether or not cardiac troponin can be released in reversible injury is a debate that could have significance for detecting minor myocardial injury. A major hurdle for use of troponin in primary care is the lack of assay standardization and nomenclature for the different generations of troponin assays. Standardization requires knowledge of what is released after cardiac injury and what the various cardiac troponin assays are measuring. Currently it is not clear if the cardiac troponin release after ischemic injury is identical to that in circulation of healthy individuals. This may affect the design of future assays and standardization approaches. There is potential that a marker of myocardial injury such as troponin can add to the value of existing indicators and biomarkers

  3. 77 FR 62396 - Annual Company-Run Stress Test Requirements for Banking Organizations With Total Consolidated...

    Science.gov (United States)

    2012-10-12

    ... federal financial regulatory agency to conduct stress tests on an annual basis. The Board is adopting this..., along with other federal financial regulatory agencies and the Federal Reserve system, conducted stress... financial regulatory agency to conduct stress tests on an annual basis (company-run stress tests).\\6\\...

  4. INTERFACE DEVICE FOR NONDESTRUCTIVE TESTING OF RESIDUAL SURFACE STRESSES

    Directory of Open Access Journals (Sweden)

    Gennady A. Perepelkin

    2016-01-01

    Full Text Available The paper considers the organization of connection of a personal computer with a device for nondestructive testing of residual surface stresses. The device works is based on the phenomenon of diffraction of ionizing radiation from the crystal lattice near the surface of the crystallites. Proposed software interface to the organization for each type of user: the device developers, administrators, users. Some aspects of the organization of communication microcontroller to a PC via USB-port

  5. Application of Massively Parallel Sequencing in the Clinical Diagnostic Testing of Inherited Cardiac Conditions

    Directory of Open Access Journals (Sweden)

    Ivone U. S. Leong

    2014-06-01

    Full Text Available Sudden cardiac death in people between the ages of 1–40 years is a devastating event and is frequently caused by several heritable cardiac disorders. These disorders include cardiac ion channelopathies, such as long QT syndrome, catecholaminergic polymorphic ventricular tachycardia and Brugada syndrome and cardiomyopathies, such as hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy. Through careful molecular genetic evaluation of DNA from sudden death victims, the causative gene mutation can be uncovered, and the rest of the family can be screened and preventative measures implemented in at-risk individuals. The current screening approach in most diagnostic laboratories uses Sanger-based sequencing; however, this method is time consuming and labour intensive. The development of massively parallel sequencing has made it possible to produce millions of sequence reads simultaneously and is potentially an ideal approach to screen for mutations in genes that are associated with sudden cardiac death. This approach offers mutation screening at reduced cost and turnaround time. Here, we will review the current commercially available enrichment kits, massively parallel sequencing (MPS platforms, downstream data analysis and its application to sudden cardiac death in a diagnostic environment.

  6. Metabolomic Profiling of Pompe Disease-Induced Pluripotent Stem Cell-Derived Cardiomyocytes Reveals That Oxidative Stress Is Associated With Cardiac and Skeletal Muscle Pathology.

    Science.gov (United States)

    Sato, Yohei; Kobayashi, Hiroshi; Higuchi, Takashi; Shimada, Yohta; Ida, Hiroyuki; Ohashi, Toya

    2016-08-18

    : Pompe disease (PD) is a lysosomal storage disease that is caused by a deficiency of the acid α-glucosidase, which results in glycogen accumulation in the lysosome. The major clinical symptoms of PD include skeletal muscle weakness, respiratory failure, and cardiac hypertrophy. Based on its severity and symptom onset, PD is classified into infantile and late-onset forms. Lysosomal accumulation of glycogen can promote many types of cellular dysfunction, such as autophagic dysfunction, endoplasmic reticulum stress, and abnormal calcium signaling within skeletal muscle. However, the disease mechanism underlying PD cardiomyopathy is not fully understood. Several researchers have shown that PD induced pluripotent stem cell (iPSC)-derived cardiomyocytes successfully replicate the disease phenotype and are useful disease models. We have analyzed the metabolomic profile of late-onset PD iPSC-derived cardiomyocytes and found that oxidative stress and mitochondrial dysfunction are likely associated with cardiac complications. Furthermore, we have validated that these disease-specific changes were also observed in the cardiomyocytes and skeletal muscle of a genetically engineered murine PD model. Oxidative stress may contribute to skeletal muscle and cardiomyocyte dysfunction in PD mice; however, NF-E2-related factor 2 was downregulated in cardiomyocytes and skeletal muscle, despite evidence of oxidative stress. We hypothesized that oxidative stress and an impaired antioxidative stress response mechanism may underlie the molecular pathology of late-onset PD.

  7. Electrocardiography as an early cardiac screening test in children with mitochondrial disease

    Directory of Open Access Journals (Sweden)

    Ran Baik

    2010-05-01

    Full Text Available Purpose : To evaluate myocardial conductivity to understand cardiac involvement in patients with mitochondrial disease. Methods : We performed retrospective study on fifty-seven nonspecific mitochondrial encephalopathy patients with no clinical cardiac manifestations. The patients were diagnosed with mitochondrial respiratory chain complex defects through biochemical enzyme assays of muscle tissue. We performed standard 12-lead electrocardiography (ECG on all patients. Results : ECG abnormalities were observed in 30 patients (52.6%. Prolongation of the QTc interval (&gt;440 ms was seen in 19 patients (33.3%, widening of the corrected QRS interval in 15 (26.3%, and bundle branch block in four (7.0%. Atrioventricular block, premature atrial contraction and premature ventricular contraction were seen in two patients each (3.5% and Wolff-Parkinson-White syndrome in one patient (1.8%. Conclusion : Given this finding, we recommend active screening with ECG in patients with mitochondrial disease even in patients without obvious cardiac manifestation.

  8. Pressure overload-induced mild cardiac hypertrophy reduces leftventricular transmural differences in mitochondrial respiratory chainactivity and increases oxidative stress

    Directory of Open Access Journals (Sweden)

    Michel eKINDO

    2012-08-01

    Full Text Available Objective: Increased mechanical stress and contractility characterizes normal left ventricular subendocardium (Endo but whether Endo mitochondrial respiratory chain complex activities is reduced as compared to subepicardium (Epi and whether pressure overload-induced left ventricular hypertrophy (LVH might modulate transmural gradients through increased reactive oxygen species (ROS production is unknown. Methods: LVH was induced by 6 weeks abdominal aortic banding and cardiac structure and function were determined with echocardiography and catheterization in sham-operated and LVH rats (n=10 for each group. Mitochondrial respiration rates, coupling, content and ROS production were measured in LV Endo and Epi, using saponin-permeabilised fibres, Amplex Red fluorescence and citrate synthase activity.Results: In sham, a transmural respiratory gradient was observed with decreases in endo maximal oxidative capacity (-36.7%, P<0.01 and complex IV activity (-57.4%, P<0.05. Mitochondrial hydrogen peroxide (H2O2 production was similar in both LV layers.Aortic banding induced mild LVH (+31.7% LV mass, associated with normal LV fractional shortening and end diastolic pressure. LVH reduced maximal oxidative capacity (-23.6 and -33.3%, increased mitochondrial H2O2 production (+86.9 and +73.1%, free radical leak (+27.2% and +36.3% and citrate synthase activity (+27.2% and +36.3% in Endo and Epi, respectively.Transmural mitochondrial respiratory chain complex IV activity was reduced in LVH (-57.4 vs –12.2%; P=0.02. Conclusions: Endo mitochondrial respiratory chain complexes activities are reduced compared to LV Epi. Mild LVH impairs mitochondrial oxidative capacity, increases oxidative stress and reduces transmural complex IV activity. Further studies will be helpful to determine whether reduced LV transmural gradient in mitochondrial respiration might be a new marker of a transition from uncomplicated toward complicated LVH.

  9. STRESS TESTS FOR VIDEOSTREAMING SERVICES BASED ON RTSP PROTOCOL

    Directory of Open Access Journals (Sweden)

    Gabriel Elías Chanchí Golondrino

    2015-11-01

    Full Text Available Video-streaming is a technology with major implications these days in such diverse contexts as education, health and the business sector; all of this regarding the ease it provides for remote access to live or recorded media content, allowing communication regardless of geographic location. One standard protocol that enables implementation of this technology is real time streaming protocol, or RTSP. However, since most application servers and Internet services are supported on HTTP requests, very little research has been done on generating tools for carrying out stress tests on streaming servers. This paper presents a stress measuring tool called Hermes, developed in Python, which allows calculation of response times for establishing RTSP connections to streaming servers, as well as obtaining RAM memory consumption and CPU usage rate data from these servers. Hermes was deployed in a video-streaming environment where stress testing was carried out on the LIVE555 server, using calls in the background to VLC and OpenRTSP open source clients. 

  10. Beneficial effects of elevating cardiac preload on left-ventricular diastolic function and volume during heat stress

    DEFF Research Database (Denmark)

    Brothers, R M; Pecini, Redi; Dalsgaard, Morten;

    2014-01-01

    conditions prior to and during a simulated hemorrhagic challenge. Heat stress did not change indices of diastolic function. Subsequent volume infusion elevated indices of diastolic function, specifically early diastolic mitral annular tissue velocity (E') and early diastolic propagation velocity (E) relative......Volume loading normalizes tolerance to a simulated hemorrhagic challenge in heat-stressed individuals, relative to when these individuals are thermoneutral. The mechanism(s) by which this occurs is unknown. This project tested two unique hypotheses; that is, the elevation of central blood volume...... via volume loading while heat stressed would 1) increase indices of left ventricular diastolic function, and 2) preserve left ventricular end-diastolic volume (LVEDV) during a subsequent simulated hemorrhagic challenge induced by lower-body negative pressure (LBNP). Indices of left ventricular...

  11. A meta-analysis comparing the prognostic accuracy of six diagnostic tests for predicting perioperative cardiac risk in patients undergoing major vascular surgery

    NARCIS (Netherlands)

    M.D. Kertai (Miklos); J.J. Bax (Jeroen); M.H. Heijenbrok-Kal (Majanka); M.G.M. Hunink (Myriam); G.J. L' Italien; H. van Urk (Hero); D. Poldermans (Don); J.R.T.C. Roelandt (Jos); H. Boersma (Eric)

    2003-01-01

    textabstractOBJECTIVE: To evaluate the discriminatory value and compare the predictive performance of six non-invasive tests used for perioperative cardiac risk stratification in patients undergoing major vascular surgery. DESIGN: Meta-analysis of published reports. METHODS: Eight

  12. Reference values for the incremental shuttle walk test in patients with cardiovascular disease entering exercise-based cardiac rehabilitation.

    Science.gov (United States)

    Cardoso, Fernando M F; Almodhy, Meshal; Pepera, Garyfalia; Stasinopoulos, Dimitrios M; Sandercock, Gavin R H

    2017-01-01

    The incremental shuttle walk test (ISWT) is used to assess functional capacity of patients entering cardiac rehabilitation. Factors such as age and sex account for a proportion of the variance in test performance in healthy individuals but there are no reference values for patients with cardiovascular disease. The aim of this study was to produce reference values for the ISWT. Participants were n = 548 patients referred to outpatient cardiac rehabilitation who underwent a clinical examination and performed the ISWT. We used regression to identify predictors of performance and produced centile values using the generalised additive model for location, scale and shape model. Men walked significantly further than women (395 ± 165 vs. 269 ± 118 m; t = 9.5, P sex. Age (years) was the strongest predictor of performance in men (β = -5.9; 95% CI: -7.1 to -4.6 m) and women (β = -4.8; 95% CI: -6.3 to 3.3). Centile curves demonstrated a broadly linear decrease in expected ISWT values in males (25-85 years) and a more curvilinear trend in females. Patients entering cardiac rehabilitation present with highly heterogeneous ISWT values. Much of the variance in performance can be explained by patients' age and sex. Comparing absolute values with age-and sex-specific reference values may aid interpretation of ISWT performance during initial patient assessment at entry to cardiac rehabilitation.

  13. Step-Stress Accelerated Degradation Testing for Solar Reflectors: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Jones, W.; Elmore, R.; Lee, J.; Kennedy, C.

    2011-09-01

    To meet the challenge to reduce the cost of electricity generated with concentrating solar power (CSP) new low-cost reflector materials are being developed including metalized polymer reflectors and must be tested and validated against appropriate failure mechanisms. We explore the application of testing methods and statistical inference techniques for quantifying estimates and improving lifetimes of concentrating solar power (CSP) reflectors associated with failure mechanisms initiated by exposure to the ultraviolet (UV) part of the solar spectrum. In general, a suite of durability and reliability tests are available for testing a variety of failure mechanisms where the results of a set are required to understand overall lifetime of a CSP reflector. We will focus on the use of the Ultra-Accelerated Weathering System (UAWS) as a testing device for assessing various degradation patterns attributable to accelerated UV exposure. Depending on number of samples, test conditions, degradation and failure patterns, test results may be used to derive insight into failure mechanisms, associated physical parameters, lifetimes and uncertainties. In the most complicated case warranting advanced planning and statistical inference, step-stress accelerated degradation (SSADT) methods may be applied.

  14. Prognostic significance of silent myocardial ischemia on a thallium stress test

    Energy Technology Data Exchange (ETDEWEB)

    Heller, L.I.; Tresgallo, M.; Sciacca, R.R.; Blood, D.K.; Seldin, D.W.; Johnson, L.L. (Columbia Univ., College of Physicians and Surgeons, New York, NY (USA))

    1990-03-15

    The clinical significance of silent ischemia is not fully known. The purpose of this study was to determine whether the presence or absence of angina during a thallium stress test positive for ischemia was independently predictive of an adverse outcome. Two hundred thirty-four consecutive patients with ischemia on a thallium stress test were identified. Ischemia was defined as the presence of defect(s) on the immediate postexercise scans not in the distribution of prior infarctions that redistributed on 4-hour scans. During the test 129 patients had angina, defined as characteristic neck, jaw, arm, back or chest discomfort, while the remaining 105 patients had no angina. Follow-up ranged from 2 to 8.2 years (mean 5.2 +/- 2.1) and was successfully obtained in 156 patients. Eighty-two of the 156 patients had angina (group A) and 74 had silent ischemia (group S). Group A patients were significantly older (62 +/- 8 vs 59 +/- 8 years, p less than 0.05). There was no significant difference between the 2 groups in terms of sex, history of prior infarction or presence of left main/3-vessel disease. A larger percentage of patients in group A were receiving beta blockers (60 vs 41%, p less than 0.05) and nitrates (52 vs 36%, 0.05 less than p less than 0.10). There was a large number of cardiac events (myocardial infarction, revascularization and death) in both groups (37 of 82 (45%) in group A; 28 of 72 (38%) in group S) but no statistically significant difference between the groups. Similarly, life-table analysis revealed no difference in mortality between the 2 groups.

  15. Is cardiac MRI an effective test for arrhythmogenic right ventricular cardiomyopathy diagnosis?

    Institute of Scientific and Technical Information of China (English)

    Santhi; Chellamuthu; Alyson; M; Smith; Steven; M; Thomas; Catherine; Hill; Peter; W; G; Brown; Abdallah; Al-Mohammad

    2014-01-01

    AIM:To evaluate the referrals with suspected arrhythmogenic right ventricular cardiomyopathy(ARVC)and compare cardiac MR(cMR)findings against clinical diagnosis.METHODS:A retrospective analysis of 114(age range16 to 83,males 55%and females 45%)patients referred for cMR with a suspected diagnosis of ARVC between May 2006 and February 2010 was performed after obtaining institutional approval for service evaluation.Reasons for referral including clinical symptoms and family history of sudden death,electrocardiogram and echo abnormalities,cMR findings,final clinical diagnosis and information about clinical management were obtained.The results of cMR were classified as major,minor,non-specific or negative depending on both functional and tissue characterisation and the cMR results were compared against the final clinical diagnosis.RESULTS:The most common reasons for referral included arrhythmias(30%)and a family history of sudden death(20%).Of the total cohort of 114 patients:4 patients(4%)had major cMR findings for ARVC,13patients(11%)had minor cMR findings,2 patients had non-specific cMR findings relating to the right ventricle and 95 patients had a negative cMR.Of the 4 patients who had major cMR findings,3(75%)had a positive clinical diagnosis.In contrast,of the 13 patients who had minor cMR findings,only 2(15%)had a positive clinical diagnosis.Out of the 95 negative patients,clinical details were available for 81 patients and none of them had ARVC.Excluding the 14 patients with no clinical data and final diagnosis,the sensitivity of the test was 100%,specificity 87%,positive predictive value29%and the negative predictive value 100%.CONCLUSION:CMR is a useful tool for ARVC evaluation because of the high negative predictive value as the outcome has a significant impact on the clinical decision-making.

  16. Application of a PVDF-based stress gauge in determining dynamic stress-strain curves of concrete under impact testing

    Science.gov (United States)

    Meng, Yi; Yi, Weijian

    2011-06-01

    Polyvinylidene fluoride (PVDF) piezoelectric material has been successfully applied in many engineering fields and scientific research. However, it has rarely been used for direct measurement of concrete stresses under impact loading. In this paper, a new PVDF-based stress gauge was developed to measure concrete stresses under impact loading. Calibrated on a split Hopkinson pressure bar (SHPB) with a simple measurement circuit of resistance strain gauges, the PVDF gauge was then used to establish dynamic stress-strain curves of concrete cylinders from a series of axial impact testing on a drop-hammer test facility. Test results show that the stress curves measured by the PVDF-based stress gauges are more stable and cleaner than that of the stress curves calculated with the impact force measured from a load cell.

  17. Testing a Longitudinal Integrated Self-Efficacy and Self-Determination Theory Model for Physical Activity Post-Cardiac Rehabilitation.

    Science.gov (United States)

    Sweet, Shane N; Fortier, Michelle S; Strachan, Shaelyn M; Blanchard, Chris M; Boulay, Pierre

    2014-01-13

    Self-determination theory and self-efficacy theory are prominent theories in the physical activity literature, and studies have begun integrating their concepts. Sweet, Fortier, Strachan and Blanchard (2012) have integrated these two theories in a cross-sectional study. Therefore, this study sought to test a longitudinal integrated model to predict physical activity at the end of a 4-month cardiac rehabilitation program based on theory, research and Sweet et al.'s cross-sectional model. Participants from two cardiac rehabilitation programs (N=109) answered validated self-report questionnaires at baseline, two and four months. Data were analyzed using Amos to assess the path analysis and model fit. Prior to integration, perceived competence and self-efficacy were combined, and labeled as confidence. After controlling for 2-month physical activity and cardiac rehabilitation site, no motivational variables significantly predicted residual change in 4-month physical activity. Although confidence at two months did not predict residual change in 4-month physical activity, it had a strong positive relationship with 2-month physical activity (β=0.30, Pself-efficacy theory were still partially supported. Because the model had good fit, this study demonstrated that theoretical integration is feasible.

  18. Testing a longitudinal integrated self-efficacy and self-determination theory model for physical activity post-cardiac rehabilitation

    Directory of Open Access Journals (Sweden)

    Shane N. Sweet

    2014-01-01

    Full Text Available Self-determination theory and self-efficacy theory are prominent theories in the physical activity literature, and studies have begun integrating their concepts. Sweet, Fortier, Strachan and Blanchard (2012 have integrated these two theories in a cross-sectional study. Therefore, this study sought to test a longitudinal integrated model to predict physical activity at the end of a 4-month cardiac rehabilitation program based on theory, research and Sweet et al.’s cross-sectional model. Participants from two cardiac rehabilitation programs (N=109 answered validated self-report questionnaires at baseline, two and four months. Data were analyzed using Amos to assess the path analysis and model fit. Prior to integration, perceived competence and self-efficacy were combined, and labeled as confidence. After controlling for 2-month physical activity and cardiac rehabilitation site, no motivational variables significantly predicted residual change in 4-month physical activity. Although confidence at two months did not predict residual change in 4-month physical activity, it had a strong positive relationship with 2-month physical activity (β=0.30, P<0.001. The overall model retained good fit indices. In conclusion, results diverged from theoretical predictions of physical activity, but self-determination and self-efficacy theory were still partially supported. Because the model had good fit, this study demonstrated that theoretical integration is feasible.

  19. Effect of Beta-Carotene on Oxidative Stress and Expression of Cardiac Connexin 43

    Energy Technology Data Exchange (ETDEWEB)

    Novo, Rosangela; Azevedo, Paula S.; Minicucci, Marcos F.; Zornoff, Leonardo A. M., E-mail: lzornoff@fmb.unesp.br; Paiva, Sergio A. R. [Faculdade de Medicina de Botucatu - Universidade Estadual Paulista ' Júlio de Mesquita Filho' , Botucatu, SP (Brazil)

    2013-09-15

    Intervention studies have shown an increased mortality in patients who received beta-carotene. However, the mechanisms involved in this phenomenon are still unknown. Evaluate the influence of beta-carotene on oxidative stress and the expression of connexin 43 in rat hearts. Wistar rats, weighing approximately 100 g, were allocated in two groups: Control Group (n = 30), that received the diet routinely used in our laboratory, and Beta-Carotene Group (n = 28), which received beta-carotene (in crystal form, added and mixed to the diet) at a dose of 500 mg of beta carotene/kg of diet. The animals received the treatment until they reached 200-250g, when they were sacrificed. Samples of blood, liver and heart were collected to perform Western blotting and immunohistochemistry for connexin 43; morphometric studies, dosages of beta carotene by high performance liquid chromatography as well as reduced glutathione, oxidized glutathione and lipids hydroperoxides were performed by biochemical analysis. Beta-carotene was detected only in the liver of Beta-Carotene Group animals (288 ± 94.7 μg/kg). Levels of reduced/ oxidized glutathione were higher in the liver and heart of Beta-Carotene Group animals (liver - Control Group: 42.60 ± 1.62; liver - Beta-Carotene Group: 57.40 ± 5.90; p = 0.04; heart: - Control Group: 117.40 ± 1.01; heart - Beta-Carotene Group: 121.81 ± 1.32 nmol/mg protein; p = 0.03). The content of total connexin 43 was larger in Beta-Carotene Group. Beta-carotene demonstrated a positive effect, characterized by the increase of intercellular communication and improvement of anti-oxidizing defense system. In this model, mechanism does not explain the increased mortality rate observed with the beta-carotene supplementation in clinical studies.

  20. ALDH2 attenuates Dox-induced cardiotoxicity by inhibiting cardiac apoptosis and oxidative stress.

    Science.gov (United States)

    Gao, Yawen; Xu, Yan; Hua, Songwen; Zhou, Shenghua; Wang, Kangkai

    2015-01-01

    The anthracycline chemotherapy drug doxorubicin (DOX) is cardiotoxic. This study aimed to explore the effect of acetaldehyde dehydrogenase 2 (ALDH2), a detoxifying protein, on DOX-induced cardiotoxicity and unveil the underlying mechanisms. BALB/c mice were randomly divided in four groups: control group (no treatment), DOX group (DOX administration for myocardial damage induction), DOX + Daidzin group (DOX administration + Daidzin, an ALDH2 antagonist) and DOX + Alda-1 group (DOX administration + Alda-1, an ALDH2 agonist). Then, survival, haemodynamic parameters, expression of pro- and anti-apoptosis markers, reactive oxygen species (ROS) and 4-Hydroxynonenal (4-HNE) levels, expression and localization of NADPH oxidase 2 (NOX2) and its cytoplasmic subunit p47(PHOX), and ALDH2 expression and activity were assessed. Mortality rates of 0, 35, 5, and 70% were obtained in the control, DOX, DOX + Alda-1, and DOX + Daidzin groups, respectively, at the ninth weekend. Compared with control animals, DOX treatment resulted in significantly reduced left ventricular systolic pressure (LVSP) and ± dp/dt, and overtly increased left ventricular end-diastolic pressure (LVEDP); increased Bax expression and caspase-3/7 activity, and reduced Bcl-2 expression in the myocardium; increased ROS (about 2 fold) and 4-HNE adduct (3 fold) levels in the myocardium; increased NOX2 protein expression and membrane translocation of P47(PHOX). These effects were aggravated in the DOX + Daidzin group, DOX + Alda-1 treated animals showed partial or complete alleviation. Finally, Daidzin further reduced the DOX-repressed ALDH2 activity, which was partially rescued by Alda-1. These results indicated that ALDH2 attenuates DOX-induced cardiotoxicity by inhibiting oxidative stress, NOX2 expression and activity, and reducing myocardial apoptosis.

  1. Cardiac echinococcosis

    Directory of Open Access Journals (Sweden)

    Ivanović-Krstić Branislava A.

    2002-01-01

    Full Text Available Cardiac hydatid disease is rare. We report on an uncommon hydatid cyst localized in the right ventricular wall, right atrial wall tricuspid valve left atrium and pericard. A 33-year-old woman was treated for cough, fever and chest pain. Cardiac echocardiograpic examination revealed a round tumor (5.8 x 4 cm in the right ventricular free wall and two smaller cysts behind that tumor. There were cysts in right atrial wall and tricuspidal valve as well. Serologic tests for hydatidosis were positive. Computed tomography finding was consistent with diagnosis of hydatid cyst in lungs and right hylar part. Surgical treatment was rejected due to great risk of cardiac perforation. Medical treatment with albendazole was unsuccessful and the patient died due to systemic hydatid involvement of the lungs, liver and central nervous system.

  2. Taurine exerts hypoglycemic effect in alloxan-induced diabetic rats, improves insulin-mediated glucose transport signaling pathway in heart and ameliorates cardiac oxidative stress and apoptosis

    Energy Technology Data Exchange (ETDEWEB)

    Das, Joydeep; Vasan, Vandana; Sil, Parames C., E-mail: parames@bosemain.boseinst.ac.in

    2012-01-15

    Hyperlipidemia, inflammation and altered antioxidant profiles are the usual complications in diabetes mellitus. In the present study, we investigated the therapeutic potential of taurine in diabetes associated cardiac complications using a rat model. Rats were made diabetic by alloxan (ALX) (single i.p. dose of 120 mg/kg body weight) and left untreated or treated with taurine (1% w/v, orally, in water) for three weeks either from the day of ALX exposure or after the onset of diabetes. Animals were euthanized after three weeks. ALX-induced diabetes decreased body weight, increased glucose level, decreased insulin content, enhanced the levels of cardiac damage markers and altered lipid profile in the plasma. Moreover, it increased oxidative stress (decreased antioxidant enzyme activities and GSH/GSSG ratio, increased xanthine oxidase enzyme activity, lipid peroxidation, protein carbonylation and ROS generation) and enhanced the proinflammatory cytokines levels, activity of myeloperoxidase and nuclear translocation of NFκB in the cardiac tissue of the experimental animals. Taurine treatment could, however, result to a decrease in the elevated blood glucose and proinflammatory cytokine levels, diabetes-evoked oxidative stress, lipid profiles and NFκB translocation. In addition, taurine increased GLUT 4 translocation to the cardiac membrane by enhanced phosphorylation of IR and IRS1 at tyrosine and Akt at serine residue in the heart. Results also suggest that taurine could protect cardiac tissue from ALX induced apoptosis via the regulation of Bcl2 family and caspase 9/3 proteins. Taken together, taurine supplementation in regular diet could play a beneficial role in regulating diabetes and its associated complications in the heart. Highlights: ► Taurine controls blood glucose via protection of pancreatic β cells in diabetic rat. ► Taurine controls blood glucose via increasing the insulin level in diabetic rat. ► Taurine improves cardiac AKT/GLUT4 signaling

  3. Inhibition of NF-κB activity in the hypothalamic paraventricular nucleus attenuates hypertension and cardiac hypertrophy by modulating cytokines and attenuating oxidative stress

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xiao-Jing [Department of Physiology and Pathophysiology, Xi' an Jiaotong University School of Basic Medical Sciences, Xi' an Jiaotong University Cardiovascular Research Center, Xi' an Jiaotong University Health Science Center, Xi' an 710061 (China); Zhang, Dong-Mei [Department of Physiology, Dalian Medical University, Dalian 116044 (China); Jia, Lin-Lin; Qi, Jie; Song, Xin-Ai; Tan, Hong [Department of Physiology and Pathophysiology, Xi' an Jiaotong University School of Basic Medical Sciences, Xi' an Jiaotong University Cardiovascular Research Center, Xi' an Jiaotong University Health Science Center, Xi' an 710061 (China); Cui, Wei [Department of Endocrinology and Metabolism, First Affiliated Hospital of Xi' an Jiaotong University, Xi' an Jiaotong University Health Science Center, Xi' an 710061 (China); Chen, Wensheng [Department of Cardiovascular Surgery, Xijing Hospital, Fourth Military Medical University, Xi' an 710032 (China); Zhu, Guo-Qing [Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing 210029 (China); Qin, Da-Nian, E-mail: dnqin@stu.edu.cn [Department of Physiology, Shantou University Medical College, Shantou 515041 (China); Kang, Yu-Ming, E-mail: ykang@mail.xjtu.edu.cn [Department of Physiology and Pathophysiology, Xi' an Jiaotong University School of Basic Medical Sciences, Xi' an Jiaotong University Cardiovascular Research Center, Xi' an Jiaotong University Health Science Center, Xi' an 710061 (China)

    2015-05-01

    We hypothesized that chronic inhibition of NF-κB activity in the hypothalamic paraventricular nucleus (PVN) delays the progression of hypertension and attenuates cardiac hypertrophy by up-regulating anti-inflammatory cytokines, reducing pro-inflammatory cytokines (PICs), attenuating nuclear factor-κB (NF-κB) p65 and NAD(P)H oxidase in the PVN of young spontaneously hypertensive rats (SHR). Young normotensive Wistar–Kyoto (WKY) and SHR rats received bilateral PVN infusions with NF–κB inhibitor pyrrolidine dithiocarbamate (PDTC) or vehicle for 4 weeks. SHR rats had higher mean arterial pressure and cardiac hypertrophy as indicated by increased whole heart weight/body weight ratio, whole heart weight/tibia length ratio, left ventricular weight/tibia length ratio, cardiomyocyte diameters of the left cardiac ventricle, and mRNA expressions of cardiac atrial natriuretic peptide (ANP) and beta-myosin heavy chain (β-MHC). These SHR rats had higher PVN levels of proinflammatory cytokines (PICs), reactive oxygen species (ROS), the chemokine monocyte chemoattractant protein-1 (MCP-1), NAD(P)H oxidase activity, mRNA expression of NOX-2 and NOX-4, and lower PVN IL-10, and higher plasma levels of PICs and NE, and lower plasma IL-10. PVN infusion of NF-κB inhibitor PDTC attenuated all these changes. These findings suggest that NF-κB activation in the PVN increases sympathoexcitation and hypertensive response, which are associated with the increases of PICs and oxidative stress in the PVN; PVN inhibition of NF-κB activity attenuates PICs and oxidative stress in the PVN, thereby attenuates hypertension and cardiac hypertrophy. - Highlights: • Spontaneously hypertensive rats exhibit neurohormonal excitation in the PVN. • PVN inhibition of NF-κB attenuates hypertension-induced cardiac hypertrophy. • PVN inhibition of NF-κB attenuates hypertension-induced neurohormonal excitation. • PVN inhibition of NF-κB attenuates hypertension-induced imbalance of cytokines

  4. Testing the tenets of minority stress theory in workplace contexts.

    Science.gov (United States)

    Velez, Brandon L; Moradi, Bonnie; Brewster, Melanie E

    2013-10-01

    The links of minority stressors (workplace discrimination, expectations of stigma, internalized heterosexism, and identity management strategies) with psychological distress and job satisfaction were examined in a sample of 326 sexual minority employees. Drawing from minority stress theory and the literature on the vocational experiences of sexual minority people, patterns of mediation and moderation were tested. Minority stressors were associated with greater distress and lower job satisfaction. A mediation model was supported in which the links of discrimination and internalized heterosexism with psychological distress were mediated by a concealment-focused identity management strategy (i.e., avoiding), and the links of discrimination, expectations of stigma, and internalized heterosexism with job satisfaction were mediated by a disclosure-focused identity management strategy (i.e., integrating). Tests of moderation indicated that for sexual minority women (but not men), the positive association of discrimination with distress was stronger at higher levels of internalized heterosexism than at lower levels. In addition, lower levels of internalized heterosexism and concealment strategies (i.e., counterfeiting and avoiding) and higher levels of a disclosure strategy (i.e., integrating) were associated with higher job satisfaction in the context of low discrimination, but this buffering effect disappeared as level of discrimination increased. The implications of these findings for minority stress research are discussed, and clinical recommendations are made.

  5. Cardiac autonomic testing and treating heart disease. “A clinical perspective”

    OpenAIRE

    Nicholas L. DePace; Joy P. Mears; Michael Yayac; Joseph Colombo

    2014-01-01

    Background Coronary heart disease (CHD) is a major health concern, affecting nearly half the middle-age population and responsible for nearly one-third of all deaths. Clinicians have several major responsibilities beyond diagnosing CHD, such as risk stratification of patients for major adverse cardiac events (MACE) and treating risks, as well as the patient. This second of a two-part review series discusses treating risk factors, including autonomic dysfunction, and expected outcomes. ...

  6. A within-subjects comparison of learning and memory performance before and after cardiac catheterization.

    NARCIS (Netherlands)

    Verwey, B.; Derikx, R.L.; Waarde, J.A. van; Essink, G.; Rooij, I.A.L.M. van; Zitman, F.G.

    2007-01-01

    OBJECTIVE: To investigate the influence of stress on the recall of neutral information in a clinical setting, a prospective study was performed on patients who were admitted to the hospital for cardiac catheterization. METHODS: During their hospital stay, 39 cardiac patients were tested for verbal r

  7. Multimodal Imaging after Sudden Cardiac Arrest in an 18-Year-Old Athlete

    Science.gov (United States)

    Rehman, Mobeen Ur; Atalay, Michael K.; Broderick, Ryan J.

    2015-01-01

    We report the case of a previously healthy 18-year-old male athlete who twice presented with sudden cardiac arrest. Our use of electrocardiography, echocardiography, cardiac magnetic resonance, coronary angiography, coronary computed tomographic angiography, and nuclear stress testing enabled the diagnoses of apical hypertrophic cardiomyopathy and anomalous origin of the right coronary artery. We discuss the patient's treatment and note the useful role of multiple cardiovascular imaging methods in cases of sudden cardiac arrest. PMID:26664308

  8. Improved Accelerated Stress Tests Based on Fuel Cell Vehicle Data

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, Timothy [Research Engineer; Motupally, Sathya [Research Engineer

    2012-06-01

    UTC will led a top-tier team of industry and national laboratory participants to update and improve DOE’s Accelerated Stress Tests (AST’s) for hydrogen fuel cells. This in-depth investigation will focused on critical fuel cell components (e.g. membrane electrode assemblies - MEA) whose durability represented barriers for widespread commercialization of hydrogen fuel cell technology. UTC had access to MEA materials that had accrued significant load time under real-world conditions in PureMotion® 120 power plant used in transit buses. These materials are referred to as end-of-life (EOL) components in the rest of this document. Advanced characterization techniques were used to evaluate degradation mode progress using these critical cell components extracted from both bus power plants and corresponding materials tested using the DOE AST’s. These techniques were applied to samples at beginning-of-life (BOL) to serve as a baseline. These comparisons advised the progress of the various failure modes that these critical components were subjected to, such as membrane degradation, catalyst support corrosion, platinum group metal dissolution, and others. Gaps in the existing ASTs predicted the degradation observed in the field in terms of these modes were outlined. Using the gaps, new AST’s were recommended and tested to better reflect the degradation modes seen in field operation. Also, BOL components were degraded in a test vehicle at UTC designed to accelerate the bus field operation.

  9. Building neurophenomics in zebrafish: Effects of prior testing stress and test batteries.

    Science.gov (United States)

    Song, Cai; Yang, Lei; Wang, JiaJia; Chen, Peirong; Li, Shaomin; Liu, Yingcong; Nguyen, Michael; Kaluyeva, Aleksandra; Kyzar, Evan J; Gaikwad, Siddharth; Kalueff, Allan V

    2016-09-15

    The zebrafish (Danio rerio) is a promising model organism for neurophenomics - a new field of neuroscience linking neural phenotypes to various genetic and environmental factors. However, the effects of prior experimental manipulations on zebrafish performance in different behavioral paradigms remain unclear. Here, we examine the influence of selected stressful procedures and test batteries on adult zebrafish anxiety-like behaviors in two commonly used models - the novel tank (NTT) and the light-dark box (LDB) tests. While no overt behavioral differences between outbred short-fin wild-type (WT) and mutant 'pink' glowfish were seen in both tests under baseline (control) conditions, an acute severe stressor (a 30-min car transportation) detected significantly lower mutant fish anxiety-like behavior in these tests. In contrast, WT zebrafish showed no overt NTT or LDB responses following a mild stressor (5-min 40-Wt light) exposure, also showing no differences in batteries of NTT and LDB run immediately one after another, or with a 1-day interval. Collectively, these findings suggest that zebrafish may be relatively less sensitive (e.g., than other popular species, such as rodents) to the test battery effect, and show that stronger stressors may be needed (to complement low-to-moderate stress aquatic screens) to better reveal phenotypical variance in zebrafish assays. Strengthening the value of zebrafish models in neurophenotyping research, this study indicates the potential of using more test batteries and a wider spectrum of pre-test stressors in zebrafish behavioral assays.

  10. A survey of membrane oxygenator heat-exchanger integrity testing at cardiac surgery centres in Great Britain and Ireland.

    Science.gov (United States)

    Carlton, Matthew; Campbell, John

    2013-11-01

    Membrane oxygenator heat exchanger (HE) device failure is reported to be very low for both short- and long-term extracorporeal devices. All oxygenator manufacturers provide instructions for leak testing of their HE devices prior to patient use. In addition to these recommendations, since 2006 at Nottingham University Hospitals (NUH) we have also additionally pressure tested HE devices prior to use. We conducted a national survey of cardiac centers in Great Britain and Ireland to determine the methods undertaken in individual centers for validation of the integrity of HE devices. Furthermore, we also collected information on the routine maintenance techniques utilized within these centers to inhibit microbial growth in the water used in the heater-cooler units (HCUs). In total, 34 responses were collected from the 57 centers performing cardiac surgery, producing a response rate of 60%. Of the responding centers, 71% are adhering to manufacturer's recommended guidelines of circulating the water through the device for 5 minutes. Of these centers, 17% reported detecting a leak between the HE and membrane compartment of the oxygenator. In responding centers, 29% reported using the pressure test technique. In the centers utilizing pressure testing, 60% reported detecting a leak. This survey reports an association of a greater HE leak detection rate using the pressure test technique compared to using water testing in isolation (p = 0.034). We believe the pressure testing method provides the perfusionist with confidence in the integrity of the HE for short- and long-term circulatory support devices prior to use in both elective and emergency situations.

  11. Detraining differentially preserved beneficial effects of exercise on hypertension: effects on blood pressure, cardiac function, brain inflammatory cytokines and oxidative stress.

    Directory of Open Access Journals (Sweden)

    Deepmala Agarwal

    Full Text Available AIMS: This study sought to investigate the effects of physical detraining on blood pressure (BP and cardiac morphology and function in hypertension, and on pro- and anti-inflammatory cytokines (PICs and AIC and oxidative stress within the brain of hypertensive rats. METHODS AND RESULTS: Hypertension was induced in male Sprague-Dawley rats by delivering AngiotensinII for 42 days using implanted osmotic minipumps. Rats were randomized into sedentary, trained, and detrained groups. Trained rats underwent moderate-intensity exercise (ExT for 42 days, whereas, detrained groups underwent 28 days of exercise followed by 14 days of detraining. BP and cardiac function were evaluated by radio-telemetry and echocardiography, respectively. At the end, the paraventricular nucleus (PVN was analyzed by Real-time RT-PCR and Western blot. ExT in AngII-infused rats caused delayed progression of hypertension, reduced cardiac hypertrophy, and improved diastolic function. These results were associated with significantly reduced PICs, increased AIC (interleukin (IL-10, and attenuated oxidative stress in the PVN. Detraining did not abolish the exercise-induced attenuation in MAP in hypertensive rats; however, detraining failed to completely preserve exercise-mediated improvement in cardiac hypertrophy and function. Additionally, detraining did not reverse exercise-induced improvement in PICs in the PVN of hypertensive rats; however, the improvements in IL-10 were abolished. CONCLUSION: These results indicate that although 2 weeks of detraining is not long enough to completely abolish the beneficial effects of regular exercise, continuing cessation of exercise may lead to detrimental effects.

  12. αB-Crystallin R120G variant causes cardiac arrhythmias and alterations in the expression of Ca(2+) -handling proteins and endoplasmic reticulum stress in mice.

    Science.gov (United States)

    Jiao, Qibin; Sanbe, Atsushi; Zhang, Xingwei; Liu, Jun-Ping; Minamisawa, Susumu

    2014-08-01

    Mutations of αB-crystallin (CryαB), a small heat shock protein abundantly expressed in cardiac and skeletal muscles, are known to cause desmin-related myopathies. The CryαB R120G allele has been linked to a familial desminopathy and, in transgenic mice, causes a sudden death at about 28 weeks of age. To investigate the mechanisms of the sudden cardiac arrest of CryαB R120G transgenic mice, we prepared protein samples from left ventricular tissues of two different age groups (10 and 28 weeks) and examined Ca(2+) -handling proteins. Expression of sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA) 2, phospholamban, ryanodine receptor 2 and calsequestrin 2 was significantly decreased in 28- versus 10-week-old CryαB R120G transgenic mice. In addition, low heart rate variability, including heart rate, total power and low frequency, was observed and continuous electrocardiogram monitoring revealed cardiac arrhythmias, such as ventricular tachycardia, atrioventricular block and atrial flutter, in 28-week-old CryαB R120G transgenic mice. In contrast, expression of endoplasmic reticulum (ER) degradation enhancing α-mannosidase-like protein, inositol requirement 1 and X-box binding protein 1 were increased significantly in 28- versus 10-week-old CryαBR120G transgenic mice, suggesting that the CryαBR120G transgenic mice exhibit increased ER stress compared with wild-type mice. Together, the data suggest that the CryαB R120G dominant variant induces ER stress and impairs Ca(2+) regulation, leading to ageing-related cardiac dysfunction, arrhythmias and decreased autonomic tone with shortened lifespan.

  13. Role of multimodality cardiac imaging in preoperative cardiovascular evaluation before noncardiac surgery

    Directory of Open Access Journals (Sweden)

    Fathala Ahmed

    2011-01-01

    Full Text Available The preoperative cardiac assessment of patients undergoing noncardiac surgery is common in the daily practice of medical consultants, anesthesiologists, and surgeons. The number of patients undergoing noncardiac surgery worldwide is increasing. Currently, there are several noninvasive diagnostic tests available for preoperative evaluation. Both nuclear cardiology with myocardial perfusion single photon emission computed tomography (SPECT and stress echocardiography are well-established techniques for preoperative cardiac evaluation. Recently, some studies demonstrated that both coronary angiography by gated multidetector computed tomography and stress cardiac magnetic resonance might potentially play a role in preoperative evaluation as well, but more studies are needed to assess the role of these new modalities in preoperative risk stratification. A common question that arises in preoperative evaluation is if further preoperative testing is needed, which preoperative test should be used. The preferred stress test is the exercise electrocardiogram (ECG. Stress imaging with exercise or pharmacologic stress agents is to be considered in patients with abnormal rest ECG or patients who are unable to exercise. After reviewing this article, the reader should develop an understanding of the following: (1 the magnitude of the cardiac preoperative morbidity and mortality, (2 how to select a patient for further preoperative testing, (3 currently available noninvasive cardiac testing for the detection of coronary artery disease and assessment of left ventricular function, and (4 an approach to select the most appropriate noninvasive cardiac test, if needed.

  14. Pre-Conditioning with CDP-Choline Attenuates Oxidative Stress-Induced Cardiac Myocyte Death in a Hypoxia/Reperfusion Model

    Science.gov (United States)

    González-Pacheco, Héctor; Méndez-Domínguez, Aurelio; Hernández, Salomón; López-Marure, Rebeca; Vazquez-Mellado, Maria J.; Aguilar, Cecilia; Rocha-Zavaleta, Leticia

    2014-01-01

    Background. CDP-choline is a key intermediate in the biosynthesis of phosphatidylcholine, which is an essential component of cellular membranes, and a cell signalling mediator. CDP-choline has been used for the treatment of cerebral ischaemia, showing beneficial effects. However, its potential benefit for the treatment of myocardial ischaemia has not been explored yet. Aim. In the present work, we aimed to evaluate the potential use of CDP-choline as a cardioprotector in an in vitro model of ischaemia/reperfusion injury. Methods. Neonatal rat cardiac myocytes were isolated and subjected to hypoxia/reperfusion using the coverslip hypoxia model. To evaluate the effect of CDP-choline on oxidative stress-induced reperfusion injury, the cells were incubated with H2O2 during reperfusion. The effect of CDP-choline pre- and postconditioning was evaluated using the cell viability MTT assay, and the proportion of apoptotic and necrotic cells was analyzed using the Annexin V determination by flow cytometry. Results. Pre- and postconditioning with 50 mg/mL of CDP-choline induced a significant reduction of cells undergoing apoptosis after hypoxia/reperfusion. Preconditioning with CDP-choline attenuated postreperfusion cell death induced by oxidative stress. Conclusion. CDP-choline administration reduces cell apoptosis induced by oxidative stress after hypoxia/reperfusion of cardiac myocytes. Thus, it has a potential as cardioprotector in ischaemia/reperfusion-injured cardiomyocytes. PMID:24578622

  15. Impact of polyphenols on physiological stress and cardiac burden in marathon runners - results from a substudy of the BeMAGIC study.

    Science.gov (United States)

    Clauss, Sebastian; Scherr, Johannes; Hanley, Alan; Schneider, Jens; Klier, Ina; Lackermair, Korbinian; Hoster, Eva; Vogeser, Michael; Nieman, David C; Halle, Martin; Nickel, Thomas

    2017-01-16

    Introduction Both physiologic stress and chronic heart disease are associated with increased systemic levels of chromogranin A (CGA) and NT-proBNP. Marathon running causes physiological stress and imposes a significant cardiac burden. Polyphenol-rich Mediterranean and Asian diets have been demonstrated to exert beneficial effects on the cardiovascular system. In this study we investigated whether pretreatment with a polyphenol beverage could attenuate the physiological and cardiac stress associated with a marathon. Methods In the BeMaGIC trial 277 athletes were randomized into two groups in a double-blinded fashion receiving 1-1.5 L/day of the same beverages either with (study beverage) or without (placebo) polyphenol enrichment (about 400 mg of gallic acid equivalents per day of a complex mixture of polyphenols).Blood samples were taken three weeks before (V1), one day before (V2), and immediately (V3), 24 hours (V4) and 72 hours (V5) after running a marathon. In our current sub-study CGA and NT-proBNP levels were analyzed by ELISA in the fastest 18 and the slowest 22 runners. Results CGA and NT-proBNP levels increased significantly after the marathon (V3) and returned to baseline 72 hours after the marathon (V5). Neither CGA nor NT-proBNP differed significantly between athletes receiving study beverage versus placebo. Separating our cohort into fast and slow runners did not reveal any significant difference regarding CGA or NT-proBNP levels between groups. Conclusion Our study provides no evidence that polyphenol supplementation attenuates marathon running induced physiological stressor cardiac burden in fast or slow runners.

  16. Expanding stress generation theory: test of a transdiagnostic model.

    Science.gov (United States)

    Conway, Christopher C; Hammen, Constance; Brennan, Patricia A

    2012-08-01

    Originally formulated to understand the recurrence of depressive disorders, the stress generation hypothesis has recently been applied in research on anxiety and externalizing disorders. Results from these investigations, in combination with findings of extensive comorbidity between depression and other mental disorders, suggest the need for an expansion of stress generation models to include the stress generating effects of transdiagnostic pathology as well as those of specific syndromes. Employing latent variable modeling techniques to parse the general and specific elements of commonly co-occurring Axis I syndromes, the current study examined the associations of transdiagnostic internalizing and externalizing dimensions with stressful life events over time. Analyses revealed that, after adjusting for the covariation between the dimensions, internalizing was a significant predictor of interpersonal dependent stress, whereas externalizing was a significant predictor of noninterpersonal dependent stress. Neither latent dimension was associated with the occurrence of independent, or fateful, stressful life events. At the syndrome level, once variance due to the internalizing factor was partialed out, unipolar depression contributed incrementally to the generation of interpersonal dependent stress. In contrast, the presence of panic disorder produced a "stress inhibition" effect, predicting reduced exposure to interpersonal dependent stress. Additionally, dysthymia was associated with an excess of noninterpersonal dependent stress. The latent variable modeling framework used here is discussed in terms of its potential as an integrative model for stress generation research.

  17. Bayesian optimal design of step stress accelerated degradation testing

    Institute of Scientific and Technical Information of China (English)

    Xiaoyang Li; Mohammad Rezvanizaniani; Zhengzheng Ge; Mohamed Abuali; Jay Lee

    2015-01-01

    This study presents a Bayesian methodology for de-signing step stress accelerated degradation testing (SSADT) and its application to batteries. First, the simulation-based Bayesian de-sign framework for SSADT is presented. Then, by considering his-torical data, specific optimal objectives oriented Kul back–Leibler (KL) divergence is established. A numerical example is discussed to il ustrate the design approach. It is assumed that the degrada-tion model (or process) fol ows a drift Brownian motion;the accele-ration model fol ows Arrhenius equation; and the corresponding parameters fol ow normal and Gamma prior distributions. Using the Markov Chain Monte Carlo (MCMC) method and WinBUGS software, the comparison shows that KL divergence is better than quadratic loss for optimal criteria. Further, the effect of simulation outliers on the optimization plan is analyzed and the preferred sur-face fitting algorithm is chosen. At the end of the paper, a NASA lithium-ion battery dataset is used as historical information and the KL divergence oriented Bayesian design is compared with maxi-mum likelihood theory oriented local y optimal design. The results show that the proposed method can provide a much better testing plan for this engineering application.

  18. Triple vessel coronary artery disease presenting as a markedly positive stress electrocardiographic test and a negative SPECT-TL scintigram: a case of balanced Ischemia

    Directory of Open Access Journals (Sweden)

    Eyal Herzog

    2011-09-01

    Full Text Available The presence of false negative nuclear stress test in the settings of positive electrocardiographic changes is a very unusual phenomenon and is usually secondary to balanced ischemia of the myocardial segments evaluated by SPECT-TL. We present a case of an 81- year old post-menopausal female who presented to her primary care physician for evaluation of a 6-week dyspnea on exertion and was referred to our institution for exercise stress test with Thallium SPECT with the objective of ruling out coronary artery disease and identifying possible areas of myocardial ischemia. The resting electrocardiogram was unremarkable and stress test evaluation was made. The patient was admitted to the cardiac care unit and coronary artery bypass grafting was successfully performed. The presence of false negative nuclear stress test in the settings of positive electrocardiographic changes is a very unusual phenomenon and is usually secondary to balanced ischemia of the myocardial segments evaluated by SPECT-TL. Patients undergoing stress tests with these characteristics should undergo careful evaluation and a high level of suspicion should be adopted for further diagnostic assessment of coronary artery disease.

  19. Dobutamine stress echo is superior to exercise stress testing in achieving target heart rate among patients on beta blockers.

    Science.gov (United States)

    Sabbath, Adam; Pack, Michael; Markiewicz, Richard; John, Jooby; Gaballa, Mohamed; Goldman, Steven; Thai, Hoang

    2005-01-01

    Published guidelines recommend continuing beta-adrenergic receptor blockade in patients undergoing stress testing. We evaluated the role of pharmacological versus exercise stress testing in achieving target heart rate (THR) among patients on beta-adrenergic blockade. We compared data from 140 patients who underwent dobutamine stress echo (DSE) and 143 patients who underwent exercise treadmill testing (ETT). In both groups, beta-adrenergic blocker was continued at the time of stress testing. Overall, patients undergoing DSE achieved THR more frequently than ETT. With beta-adrenergic blockade, DSE patients met THR more frequently than ETT patients (p < 0.001). Without beta-adrenergic blockade, there was no difference between either modality in achieving THR. In both DSE and ETT patients, absence of beta-adrenergic blockade increased the odds of achieving THR [odds ratio (OR): 2.46, p = 0.042 and OR: 7.44, p < 0.001, respectively]. Atropine use with DSE increased the odds of achieving THR (OR: 3.76, p = 0.006). In conclusion, pharmacological stress testing appears to be superior to exercise stress testing in achieving THR among patients on beta-adrenergic blockade.

  20. High-Stakes Testing and Its Relationship to Stress Levels of Coastal Secondary Teachers

    Science.gov (United States)

    McDaniel, Sheneatha Lashelle Alexander

    2012-01-01

    The purpose of this research was to examine the relationship between high-stakes tests and stress with secondary teachers. Furthermore, this study investigated whether veteran teachers experience more stress than novice teachers and whether or not self-efficacy, gender, accountability status, and years of experience influence teacher stress as it…

  1. Using Uncertainty Analysis to Guide the Development of Accelerated Stress Tests (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Kempe, M.

    2014-03-01

    Extrapolation of accelerated testing to the long-term results expected in the field has uncertainty associated with the acceleration factors and the range of possible stresses in the field. When multiple stresses (such as temperature and humidity) can be used to increase the acceleration, the uncertainty may be reduced according to which stress factors are used to accelerate the degradation.

  2. Selumetinib, an Oral Anti-Neoplastic Drug, May Attenuate Cardiac Hypertrophy via Targeting the ERK Pathway.

    Directory of Open Access Journals (Sweden)

    Chen Li

    Full Text Available Although extracellular-regulated kinases (ERK are a well-known central mediator in cardiac hypertrophy, no clinically available ERK antagonist has been tested for preventing cardiac hypertrophy. Selumetinib is a novel oral MEK inhibitor that is currently under Phase II and Phase III clinical investigation for advanced solid tumors. In this study, we investigated whether Selumetinib could inhibit the aberrant ERK activation of the heart in response to stress as well as prevent cardiac hypertrophy.In an in vitro model of PE-induced cardiac hypertrophy, Selumetinib significantly inhibited the ERK activation and prevented enlargement of cardiomyocytes or reactivation of certain fetal genes. In the pathologic cardiac hypertrophy model of ascending aortic constriction, Selumetinib provided significant ERK inhibition in the stressed heart but not in the other organs. This selective ERK inhibition prevented left ventricular (LV wall thickening, LV mass increase, fetal gene reactivation and cardiac fibrosis. In another distinct physiologic cardiac hypertrophy model of a swimming rat, Selumetinib provided a similar anti-hypertrophy effect, except that no significant fetal gene reactivation or cardiac fibrosis was observed.Selumetinib, a novel oral anti-cancer drug with good safety records in a number of Phase II clinical trials, can inhibit ERK activity in the heart and prevent cardiac hypertrophy. These promising results indicate that Selumetinib could potentially be used to treat cardiac hypertrophy. However, this hypothesis needs to be validated in human clinical trials.

  3. Selumetinib, an Oral Anti-Neoplastic Drug, May Attenuate Cardiac Hypertrophy via Targeting the ERK Pathway

    Science.gov (United States)

    Yang, Hao; Luo, Fangbo; Chen, Lihong; Cai, Huawei; Li, Yajiao; You, Guiying; Long, Dan; Li, Shengfu; Zhang, Qiuping; Rao, Li

    2016-01-01

    Aims Although extracellular-regulated kinases (ERK) are a well-known central mediator in cardiac hypertrophy, no clinically available ERK antagonist has been tested for preventing cardiac hypertrophy. Selumetinib is a novel oral MEK inhibitor that is currently under Phase II and Phase III clinical investigation for advanced solid tumors. In this study, we investigated whether Selumetinib could inhibit the aberrant ERK activation of the heart in response to stress as well as prevent cardiac hypertrophy. Methods and Results In an in vitro model of PE-induced cardiac hypertrophy, Selumetinib significantly inhibited the ERK activation and prevented enlargement of cardiomyocytes or reactivation of certain fetal genes. In the pathologic cardiac hypertrophy model of ascending aortic constriction, Selumetinib provided significant ERK inhibition in the stressed heart but not in the other organs. This selective ERK inhibition prevented left ventricular (LV) wall thickening, LV mass increase, fetal gene reactivation and cardiac fibrosis. In another distinct physiologic cardiac hypertrophy model of a swimming rat, Selumetinib provided a similar anti-hypertrophy effect, except that no significant fetal gene reactivation or cardiac fibrosis was observed. Conclusions Selumetinib, a novel oral anti-cancer drug with good safety records in a number of Phase II clinical trials, can inhibit ERK activity in the heart and prevent cardiac hypertrophy. These promising results indicate that Selumetinib could potentially be used to treat cardiac hypertrophy. However, this hypothesis needs to be validated in human clinical trials. PMID:27438013

  4. Nondestructive Testing and Characterization of Residual Stress Field Using an Ultrasonic Method

    Institute of Scientific and Technical Information of China (English)

    SONG Wentao; XU Chunguang; PAN Qinxue; SONG Jianfeng

    2016-01-01

    To address the difficulty in testing and calibrating the stress gradient in the depth direction of mechanical components, a new technology of nondestructive testing and characterization of the residual stress gradient field by ultrasonic method is proposed based on acoustoelasticity theory. By carrying out theoretical analysis, the sensitivity coefficients of different types of ultrasonic are obtained by taking the low carbon steel(12%C) as a research object. By fixing the interval distance between sending and receiving transducers, the mathematical expressions of the change of stress and the variation of time are established. To design one sending-one receiving and oblique incidence ultrasonic detection probes, according to Snell law, the critically refracted longitudinal wave (LCR wave) is excited at a certain depth of the fixed distance of the tested components. Then, the relationship between the depth of LCR wave detection and the center frequency of the probe in Q235 steel is obtained through experimental study. To detect the stress gradient in the depth direction, a stress gradient LCR wave detection model is established, through which the stress gradient formula is derived by the relationship between center frequency and detecting depth. A C-shaped stress specimen of Q235 steel is designedto conduct stress loading tests, and the stress is measured with the five group probes at different center frequencies. The accuracy of ultrasonic testing is verified by X-ray stress analyzer. The stress value of each specific depth is calculated using the stress gradient formula. Accordingly, the ultrasonic characterization of residual stress field is realized. Characterization results show that the stress gradient distribution is consistent with the simulation in ANSYS. The new technology can be widely applied in the detection of the residual stress gradient field caused by mechanical processing, such as welding and shot peening.

  5. Nondestructive testing and characterization of residual stress field using an ultrasonic method

    Science.gov (United States)

    Song, Wentao; Xu, Chunguang; Pan, Qinxue; Song, Jianfeng

    2016-03-01

    To address the difficulty in testing and calibrating the stress gradient in the depth direction of mechanical components, a new technology of nondestructive testing and characterization of the residual stress gradient field by ultrasonic method is proposed based on acoustoelasticity theory. By carrying out theoretical analysis, the sensitivity coefficients of different types of ultrasonic are obtained by taking the low carbon steel(12%C) as a research object. By fixing the interval distance between sending and receiving transducers, the mathematical expressions of the change of stress and the variation of time are established. To design one sending-one receiving and oblique incidence ultrasonic detection probes, according to Snell law, the critically refracted longitudinal wave (LCR wave) is excited at a certain depth of the fixed distance of the tested components. Then, the relationship between the depth of LCR wave detection and the center frequency of the probe in Q235 steel is obtained through experimental study. To detect the stress gradient in the depth direction, a stress gradient LCR wave detection model is established, through which the stress gradient formula is derived by the relationship between center frequency and detecting depth. A C-shaped stress specimen of Q235 steel is designed to conduct stress loading tests, and the stress is measured with the five group probes at different center frequencies. The accuracy of ultrasonic testing is verified by X-ray stress analyzer. The stress value of each specific depth is calculated using the stress gradient formula. Accordingly, the ultrasonic characterization of residual stress field is realized. Characterization results show that the stress gradient distribution is consistent with the simulation in ANSYS. The new technology can be widely applied in the detection of the residual stress gradient field caused by mechanical processing, such as welding and shot peening.

  6. Impact of aging on cardiac function in a female rat model of menopause: role of autonomic control, inflammation, and oxidative stress

    Directory of Open Access Journals (Sweden)

    Machi JF

    2016-03-01

    Full Text Available Jacqueline Freire Machi,1,2 Danielle da Silva Dias,3 Sarah Cristina Freitas,3 Oscar Albuquerque de Moraes,1 Maikon Barbosa da Silva,1 Paula Lázara Cruz,1 Cristiano Mostarda,4 Vera M C Salemi,1 Mariana Morris,2 Kátia De Angelis,3 Maria-Cláudia Irigoyen1 1Hypertension Unit, Heart Institute (InCor, School of Medicine, University of Sao Paulo, São Paulo, Brazil; 2Institute of Neuro-Immune Medicine, Nova Southeastern University, Fort Lauderdale, FL, USA; 3Laboratory of Translational Physiology, Universidade Nove de Julho (UNINOVE, São Paulo, 4Health Adult and Child, Federal University of Maranhao (UFMA, São Luiz, Maranhão, Brazil Objective: The aim of this study was to evaluate the effects of aging on metabolic, cardiovascular, autonomic, inflammatory, and oxidative stress parameters after ovarian hormone deprivation (OVX. Methods: Female Wistar rats (3 or 22 months old were divided into: young controls, young ovariectomized, old controls, and old ovariectomized (bilateral ovaries removal. After a 9-week follow-up, physical capacity, metabolic parameters, and morphometric and cardiac functions were assessed. Subsequently, arterial pressure was recorded and cardiac autonomic control was evaluated. Oxidative stress was measured on the cardiac tissue, while inflammatory profile was assessed in the plasma. Results: Aging or OVX caused an increase in body and fat weight and triglyceride concentration and a decrease in both insulin sensitivity and aerobic exercise capacity. Left ventricular diastolic dysfunction and increased cardiac overload (myocardial performance index were reported in old groups when compared with young groups. Aging and OVX led to an increased sympathetic tonus, and vagal tonus was lower only for the old groups. Tumor necrosis factor-α and interleukin-6 were increased in old groups when compared with young groups. Glutathione redox balance (GSH/GSSG was reduced in young ovariectomized, old controls, and old ovariectomized

  7. Intra-amygdala injection of GABAA agonist, muscimol, reduces tachycardia and modifies cardiac sympatho-vagal balance during restraint stress in rats.

    Science.gov (United States)

    Salomé, N; Ngampramuan, S; Nalivaiko, E

    2007-08-24

    At present, little is known about the brain origin of stress-induced cardiac sympathetic drive responsible for stress-induced tachycardia. Our aim was to determine the effect of bilateral microinjections of the GABA(A) receptor agonist, muscimol, into the amygdaloid complex on both the heart rate and cardiac autonomic activity during restraint stress. Experiments were performed in male Sprague-Dawley rats (n=9), with pre-implanted electrocardiographic electrodes. Heart rate increased sharply after the onset of the restraint and reached a peak 1-2 min later (from 344+/-6-440+/-20 BPM). Subsequently, heart rate began to fall, and during the next 10-15 min approached the steady-state level of 384+/-11. After vehicle, mean heart rate during each of three 10-min restraint epochs was significantly higher compared with the pre-restraint level. After muscimol, mean heart rate was significantly elevated only during the first 10 min of restraint. There was no difference in the early peak tachycardia between both conditions. Muscimol substantially accelerated the fall of the HR from the peak to the steady-state level, and thus the area under the curve value for muscimol (503+/-162 BPM x min) was significantly smaller than that for vehicle (1221+/-231 BPM x min); Pheart rate decreased and the low-frequency power increased during the restraint, resulting in a significant rise of the low frequency/high frequency ratio from 1.2+/-0.2-2.8+/-0.6 (n=9, Pheart rate variability indices.

  8. Marketing cardiac CT programs.

    Science.gov (United States)

    Scott, Jason

    2010-01-01

    There are two components of cardiac CT discussed in this article: coronary artery calcium scoring (CACS) and coronary computed tomography angiography (CCTA).The distinctive advantages of each CT examination are outlined. In order to ensure a successful cardiac CT program, it is imperative that imaging facilities market their cardiac CT practices effectively in order to gain a competitive advantage in this valuable market share. If patients receive quality care by competent individuals, they are more likely to recommend the facility's cardiac CT program. Satisfied patients will also be more willing to come back for any further testing.

  9. The Effect of Fabric Type of Common Iranian Working Clothes on the Induced Cardiac and Physiological Strain Under Heat Stress.

    Science.gov (United States)

    Parvari, Roh Allah; Aghaei, Habib Allah; Dehghan, Habibollah; Khademi, Abolfazl; Maracy, Mohammad Reza; Dehghan, Somayeh Farhang

    2015-01-01

    The present study compared the effect of fabric type of working clothes on heat strain responses in different levels of physical workload and under different kinds of weather conditions. Four kinds of working clothing fabric that are greatly popular in Iranian industry were assessed on 18 healthy male at 2 environments: hot and humid (dry temperature [DBt]: 35°C and relative humidity [RH]: 70%) and hot and dry (DBt: 40°C and RH: 40%). The physiological responses such as heart rate and core body temperature were reported. It was found that there were no significant differences between different types of clothing fabric on cardiac and physiological parameters. It can be recommended that 100% cotton clothing ensemble during low-workload activities and 30.2% cotton-69.8% polyester clothing ensemble during moderate-workload activities is used for Iranian workers to maintain the cardiac and physiological strains as low as possible.

  10. Standard practice for preparation and use of Bent-Beam stress-corrosion test specimens

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This practice covers procedures for designing, preparing, and using bent-beam stress-corrosion specimens. 1.2 Different specimen configurations are given for use with different product forms, such as sheet or plate. This practice applicable to specimens of any metal that are stressed to levels less than the elastic limit of the material, and therefore, the applied stress can be accurately calculated or measured (see Note 1). Stress calculations by this practice are not applicable to plastically stressed specimens. Note 1—It is the nature of these practices that only the applied stress can be calculated. Since stress-corrosion cracking is a function of the total stress, for critical applications and proper interpretation of results, the residual stress (before applying external stress) or the total elastic stress (after applying external stress) should be determined by appropriate nondestructive methods, such as X-ray diffraction (1). 1.3 Test procedures are given for stress-corrosion testing by ex...

  11. Testing of the MRL (Medical Research Laboratories) 450 SL-AF Cardiac Monitor

    Science.gov (United States)

    1989-08-01

    inspection, it is subjected to various " referee tests" that check its performance under various anticipated operational conditions. The referee tests...August 1986. Drc INSCop). 6 Accession For NTIS GRA&I DTIC AB Unannounced 0 justi"loation By Di stribut ton/ Availability Codes Avail and/or Dtlst

  12. Oral treatment with herbal formula B307 alleviates cardiac failure in aging R6/2 mice with Huntington’s disease via suppressing oxidative stress, inflammation, and apoptosis

    Directory of Open Access Journals (Sweden)

    Lin CL

    2015-07-01

    reduced under oral B307 treatment (P<0.05. Oral B307 treatment may briefly alleviate cardiac failure in aging HD R6/2 mice via suppressing cardiac oxidative stress, inflammation, and apoptosis. We suggested that the herbal formula B307 may be further developed as a potential health supplement for ameliorating cardiac failure associated with aging. Keywords: Chinese herbal medicines, cardiomyocytes, echocardiography, aging, transgenic mouse model

  13. Stimulating endogenous cardiac regeneration

    Directory of Open Access Journals (Sweden)

    Amanda eFinan

    2015-09-01

    Full Text Available The healthy adult heart has a low turnover of cardiac myocytes. The renewal capacity, however, is augmented after cardiac injury. Participants in cardiac regeneration include cardiac myocytes themselves, cardiac progenitor cells, and peripheral stem cells, particularly from the bone marrow compartment. Cardiac progenitor cells and bone marrow stem cells are augmented after cardiac injury, migrate to the myocardium, and support regeneration. Depletion studies of these populations have demonstrated their necessary role in cardiac repair. However, the potential of these cells to completely regenerate the heart is limited. Efforts are now being focused on ways to augment these natural pathways to improve cardiac healing, primarily after ischemic injury but in other cardiac pathologies as well. Cell and gene therapy or pharmacological interventions are proposed mechanisms. Cell therapy has demonstrated modest results and has passed into clinical trials. However, the beneficial effects of cell therapy have primarily been their ability to produce paracrine effects on the cardiac tissue and recruit endogenous stem cell populations as opposed to direct cardiac regeneration. Gene therapy efforts have focused on prolonging or reactivating natural signaling pathways. Positive results have been demonstrated to activate the endogenous stem cell populations and are currently being tested in clinical trials. A potential new avenue may be to refine pharmacological treatments that are currently in place in the clinic. Evidence is mounting that drugs such as statins or beta blockers may alter endogenous stem cell activity. Understanding the effects of these drugs on stem cell repair while keeping in mind their primary function may strike a balance in myocardial healing. To maximize endogenous cardiac regeneration,a combination of these approaches couldameliorate the overall repair process to incorporate the participation ofmultiple cell players.

  14. Summary report - development of laboratory tests and the stress- strain behaviour of Olkiluoto mica gneiss

    Energy Technology Data Exchange (ETDEWEB)

    Hakala, M.; Heikkilae, E. [Helsinki Univ. of Technology, Espoo (Finland). Lab. of Rock Engineering

    1997-05-01

    This work summarizes the project aimed at developing and qualifying a suitable combination of laboratory tests to establish a statistically reliable stress-strain behaviour of the main rock types at Posiva Oy`s detailed investigation sites for disposal of spent nuclear fuel. The work includes literature study of stress-strain behaviour of brittle rock, development and qualification of laboratory tests, suggested test procedures and interpretation methods and finally testing of Olkiluoto mica gneiss. The Olkiluoto study includes over 130 loading tests. Besides the commonly used laboratory tests, direct tensile tests, damage controlled tests and acoustic emission measurements were also carried out. (orig.) (54 refs.).

  15. 12 CFR 652.100 - Audit of the risk-based capital stress test.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Audit of the risk-based capital stress test... AGRICULTURAL MORTGAGE CORPORATION FUNDING AND FISCAL AFFAIRS Risk-Based Capital Requirements § 652.100 Audit of the risk-based capital stress test. You must have a qualified, independent external auditor...

  16. Life Stress and Reading Comprehension Test Scores in the Middle School Student.

    Science.gov (United States)

    Jones, Maryann Clementi

    A study determined the relationship between life stress and reading comprehension test scores on the IOWA Tests of Basic Skills. Subjects, 41 middle-school students attending Lincoln School in Garwood, New Jersey, were surveyed as to the amount of life stress prevalent in their lives. In addition, the Iowa scores for reading comprehension were…

  17. STATISTICAL INFERENCE OF WEIBULL DISTRIBUTION FOR TAMPERED FAILURE RATE MODEL IN PROGRESSIVE STRESS ACCELERATED LIFE TESTING

    Institute of Scientific and Technical Information of China (English)

    WANG Ronghua; FEI Heliang

    2004-01-01

    In this note, the tampered failure rate model is generalized from the step-stress accelerated life testing setting to the progressive stress accelerated life testing for the first time. For the parametric setting where the scale parameter satisfying the equation of the inverse power law is Weibull, maximum likelihood estimation is investigated.

  18. 78 FR 59165 - Orders: Information Reporting With Respect to Stress Testing of Regulated Entities

    Science.gov (United States)

    2013-09-26

    ... Order and rule. These initial Orders communicate to the regulated entities their reporting requirements...-FHLMC-1 Information Reporting with Respect to Stress Testing of Regulated Entities Whereas, section 165... AGENCY 12 CFR Part 1238 Orders: Information Reporting With Respect to Stress Testing of...

  19. Pentoxifylline Attenuates Cardiac Remodeling Induced by Tobacco Smoke Exposure

    Energy Technology Data Exchange (ETDEWEB)

    Minicucci, Marcos; Oliveira, Fernando; Santos, Priscila; Polegato, Bertha; Roscani, Meliza; Fernandes, Ana Angelica; Lustosa, Beatriz; Paiva, Sergio; Zornoff, Leonardo; Azevedo, Paula, E-mail: paulasa@fmb.unesp.br [Faculdade de Medicina de Botucatu, Universidade Estadual Paulista, São Paulo, SP (Brazil)

    2016-05-15

    Tobacco smoke exposure is an important risk factor for cardiac remodeling. Under this condition, inflammation, oxidative stress, energy metabolism abnormalities, apoptosis, and hypertrophy are present. Pentoxifylline has anti‑inflammatory, anti-apoptotic, anti-thrombotic and anti-proliferative properties. The present study tested the hypothesis that pentoxifylline would attenuate cardiac remodeling induced by smoking. Wistar rats were distributed in four groups: Control (C), Pentoxifylline (PX), Tobacco Smoke (TS), and PX-TS. After two months, echocardiography, invasive blood pressure measurement, biochemical, and histological studies were performed. The groups were compared by two-way ANOVA with a significance level of 5%. TS increased left atrium diameter and area, which was attenuated by PX. In the isolated heart study, TS lowered the positive derivate (+dp/dt), and this was attenuated by PX. The antioxidants enzyme superoxide dismutase and glutathione peroxidase were decreased in the TS group; PX recovered these activities. TS increased lactate dehydrogenase (LDH) and decreased 3-hydroxyacyl Coenzyme A dehydrogenases (OH-DHA) and citrate synthase (CS). PX attenuated LDH, 3-OH-DHA and CS alterations in TS-PX group. TS increased IL-10, ICAM-1, and caspase-3. PX did not influence these variables. TS induced cardiac remodeling, associated with increased inflammation, oxidative stress, apoptosis, and changed energy metabolism. PX attenuated cardiac remodeling by reducing oxidative stress and improving cardiac bioenergetics, but did not act upon cardiac cytokines and apoptosis.

  20. Perspectives on the value of biomarkers in acute cardiac care and implications for strategic management.

    Science.gov (United States)

    Kossaify, Antoine; Garcia, Annie; Succar, Sami; Ibrahim, Antoine; Moussallem, Nicolas; Kossaify, Mikhael; Grollier, Gilles

    2013-01-01

    Biomarkers in acute cardiac care are gaining increasing interest given their clinical benefits. This study is a review of the major conditions in acute cardiac care, with a focus on biomarkers for diagnostic and prognostic assessment. Through a PubMed search, 110 relevant articles were selected. The most commonly used cardiac biomarkers (cardiac troponin, natriuretic peptides, and C-reactive protein) are presented first, followed by a description of variable acute cardiac conditions with their relevant biomarkers. In addition to the conventional use of natriuretic peptides, cardiac troponin, and C-reactive protein, other biomarkers are outlined in variable critical conditions that may be related to acute cardiac illness. These include ST2 and chromogranin A in acute dyspnea and acute heart failure, matrix metalloproteinase in acute chest pain, heart-type fatty acid binding protein in acute coronary syndrome, CD40 ligand and interleukin-6 in acute myocardial infarction, blood ammonia and lactate in cardiac arrest, as well as tumor necrosis factor-alpha in atrial fibrillation. Endothelial dysfunction, oxidative stress and inflammation are involved in the physiopathology of most cardiac diseases, whether acute or chronic. In summary, natriuretic peptides, cardiac troponin, C-reactive protein are currently the most relevant biomarkers in acute cardiac care. Point-of-care testing and multi-markers use are essential for prompt diagnostic approach and tailored strategic management.

  1. Teste ergométrico: valor prognóstico em pacientes idosos com doença aterosclerótica coronariana estável Exercise stress test: prognostic value for elderly patients with stable coronary atherosclerosis

    Directory of Open Access Journals (Sweden)

    Marcelo Eidi Ochiai

    2006-05-01

    Full Text Available OBJETIVO: Estudar o valor prognóstico das variáveis do teste ergométrico em pacientes idosos com doença aterosclerótica coronariana e isquemia induzida pelo esforço. MÉTODOS: Foram estudados 64 pacientes idosos (61 homens, idade de 73 ± 5 anos com doença aterosclerótica coronariana, comprovada por coronariografia, clinicamente estável, fração de ejeção de ventrículo esquerdo maior ou igual a 0,40 e isquemia miocárdica durante o teste ergométrico. A cada seis meses, os pacientes foram avaliados para eventos cardíacos (morte, infarto do miocárdio, angina instável, angioplastia e revascularização do miocárdio. RESULTADOS: Após seguimento médio de 48 meses, 23 (36% pacientes sofreram eventos cardíacos. Não houve diferença clínica e angiográfica entre os pacientes que sofreram o evento e os que não o sofreram. Pela análise multivariada, a presença de dor precordial durante o teste ergométrico (risco relativo de 2,668 e p = 0,031 e a freqüência cardíaca no início da isquemia (risco relativo de 0,966 e p = 0,009 foram associadas a eventos cardíacos. CONCLUSÃO: Nessa população idosa, a presença de dor precordial durante o teste ergométrico e a freqüência cardíaca no início da isquemia foram associadas a eventos cardíacos. Essas variáveis podem ser úteis para avaliação do risco de pacientes com doença aterosclerótica coronariana estável.OBJECTIVE: To study the prognostic value of exercise stress test variables in elderly patients with coronary atherosclerosis and exercise-induced ischemia. METHODS: Sixty-four elderly patients (61 men, 73 ± 5 years old with coronary atherosclerosis, verified by cardiac catheterization, that were clinically stable, had a left ventricle ejection fraction greater than or equal to 0.40 and developed myocardial ischemia during the exercise stress test were studied. The patients were evaluated every six months for cardiac events (death, myocardial infarction, unstable

  2. Stress test: identifying crowding stress-tolerant hybrids in processing sweet corn

    Science.gov (United States)

    Improvement in tolerance to intense competition at high plant populations (i.e. crowding stress) is a major genetic driver of corn yield gain the last half-century. Recent research found differences in crowding stress tolerance among a few modern processing sweet corn hybrids; however, a larger asse...

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

    Science.gov (United States)

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

    2015-02-01

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

  4. A centrifugally actuated point-of-care testing system for the surface acoustic wave immunosensing of cardiac troponin I.

    Science.gov (United States)

    Lee, Woochang; Jung, Jaeyeon; Hahn, Young Ki; Kim, Sang Kyu; Lee, Yeolho; Lee, Joonhyung; Lee, Tae-Han; Park, Jin-Young; Seo, Hyejung; Lee, Jung Nam; Oh, Jin Ho; Choi, Youn-Suk; Lee, Soo Suk

    2013-05-07

    A fully automated point-of-care testing (POCT) system with a surface acoustic wave (SAW) immunosensor was developed for rapid and sensitive detection of cardiac troponin I (cTnI) in body fluid (plasma and whole blood). The assay, based on gold nanoparticle sandwich immunoassay and subsequent gold staining, was performed on the SAW immunosensor packaged inside a disposable microfluidic cartridge. The entire fluidic process, including plasma separation, reagent transport, metering, and mixing, was carried out by controlling the centrifugal force acting on the rotating cartridge and laser-irradiated ferrowax microvalves. On investigation of sensor response to various cTnI concentrations, the system exhibited a high performance with a detection limit of 6.7 pg mL(-1), and the coefficient of variation was less than 10% over the entire test range (10 pg mL(-1) to 25 ng mL(-1)). On comparing this POCT system with a clinically utilized system in a physical laboratory (Centaur® XP; Siemens), a correlation coefficient of 0.998 was found, validating the diagnostic capability of the SAW immunosensor.

  5. High Temperature Stress Analysis on 61-pin Test Assembly for Reactor Core Sub-channel Flow Test

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dongwon; Kim, Hyungmo; Lee, Hyeongyeon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    In this study, a high temperature heat transfer and stress analysis of a 61-pin test fuel assembly scaled down from the full scale 217-pin sub-assembly was conducted. The reactor core subchannel flow characteristic test will be conducted to evaluate uncertainties in computer codes used for reactor core thermal hydraulic design. Stress analysis for a 61-pin fuel assembly scaled down from Prototype Generation IV Sodium-cooled Fast Reactor was conducted and structural integrity in terms of load controlled stress limits was conducted. In this study, The evaluations on load-controlled stress limits for a 61-pin test fuel assembly to be used for reactor core subchannel flow distribution tests were conducted assuming that the test assembly is installed in a Prototype Generation IV Sodium-cooled fast reactor core. The 61-pin test assembly has the geometric similarity on P/D and H/D with PGSFR and material of fuel assembly is austenitic stainless steel 316L. The stress analysis results showed that 4.05MPa under primary load occurred at mid part of the test assembly and it was shown that the value of 4.05Mpa was far smaller than the code allowable of 127MPa. , it was shown that the stress intensity due to due to primary load is very small. The stress analysis results under primary and secondary loads showed that maximum stress intensity of 84.08MPa occurred at upper flange tangent to outer casing and the value was well within the code allowable of 268.8MPa. Integrity evaluations based on strain limits and creep-fatigue damage are underway according to the elevated design codes.

  6. Non-destructive testing of biaxial stress state in ferromagnetic materials

    Science.gov (United States)

    Vengrinovich, V. L.; Vintov, D. A.; Dmitrovich, D. V.

    2014-02-01

    The technique for biaxial stress state quantitative non destructive testing using magnetic, namely Barkhausen Noise, measurements is developed and checked experimentally. The main elaboration concerns the application of uni-axial calibration data for bi-axial stress measurement in the material which treatment pre-history is not definitely known. The article is aimed to get over difficulties, accompanying factual nondestructive stress evaluation, implied from its tensor nature. The developed technique of stress calibration and measurement assumes the bi-axial stress components recovery from uni-axial magnetic and Barkhausen noise measurement results. The complete technology, based on new calibration procedure with grid diagrams is considered in the article.

  7. Rapid, high sensitivity, point-of-care test for cardiac troponin based on optomagnetic biosensor

    NARCIS (Netherlands)

    Dittmer, W.U.; Evers, T.H.; Hardeman, W.M.; Huijnen-Keur, W.M.; Kamps, R.; De Kievit, P.; Neijzen, J.H.M.; Sijbers, M.J.J.; Nieuwenhuis, J.H.; Hefti, M.H.; Dekkers, D.; Martens, M.

    2010-01-01

    BACKGROUND: We present a handheld integrated device based on a novel magnetic-optical technology for the sensitive detection of cardiactroponin I, a biomarker for the positive diagnosis of myocardial infarct, in a finger-prick blood sample. The test can be performed with a turn-around time of 5 min

  8. Sublingual nitroglycerin used in routine tilt testing provokes a cardiac output-mediated vasovagal response

    NARCIS (Netherlands)

    Gisolf, J.; Westerhof, B.E.; Dijk, N. van; Wesseling, K.H.; Wieling, W.; Karemaker, J.M.

    2004-01-01

    Objectives We set out to determine the effect of sublingual nitroglycerin (NTG), as used during routine tilt testing in patients with unexplained syncope, on hemodynamic characteristics and baroreflex control of heart rate (HR) and systemic vascular resistance (SVR). Background Nitroglycerin is used

  9. Depressive symptoms and perceived chronic stress predict test anxiety in nursing students

    Directory of Open Access Journals (Sweden)

    Christoph Augner

    2015-09-01

    Full Text Available Aim: The aim of this study is to identify predictors of test anxiety in nursing students. Design: Cross sectional pilot study. Methods: A questionnaire was administered to 112 students of an Austrian nursing school (mean age = 21.42, SD = 5.21. Test anxiety (measured by the standardized PAF Test Anxiety Questionnaire, perceived chronic stress, depressive symptoms, pathological eating and further psychological and health parameters were measured. Results: We found highly significant correlations between test anxiety and working hours (0.25, depression score (0.52, emotional stability (-0.31, and perceived chronic stress (0.65 (p < 0.01, for all. Regression analysis revealed chronic stress and emotional instability as best predictors for test anxiety. Furthermore, path analysis revealed that past negative academic performance outcomes contribute to test anxiety via depressive symptoms and perceived chronic stress. Conclusion: Depressive symptoms and perceived chronic stress are strongly related to test anxiety. Therefore therapy and training methods that address depressive symptoms and perceived chronic stress, and thereby aim to modify appraisal of potential stressful situations, may be successful in addressing test anxiety.

  10. Butanolic fraction of Moringa oleifera Lam. (Moringaceae) attenuates isoprotrenol induced cardiac necrosis and oxidative stress in rats: an EPR study

    OpenAIRE

    Panda, Sunanda

    2015-01-01

    The preventive effect of Moringa oleifera polyphenolic fraction (MOPF) on cardiac damage was evaluated in isoproterenol (ISO) induced cardiotoxicity model of Wistar rats. Male rats in different groups were treated with MOPF orally at the dose of 50, 100 and 150 mg/kg/day for 28 days and were subsequently administered (s.c.) with ISO (85 mg/kg body weight) for the last two days. At the end of the experiment levels of serum troponin-T, creatine kinase-MB, lactate dehydrogenase, content of malon...

  11. The context counts: congruent learning and testing environments prevent memory retrieval impairment following stress.

    Science.gov (United States)

    Schwabe, Lars; Wolf, Oliver T

    2009-09-01

    Stress before retention testing impairs memory, whereas memory performance is enhanced when the learning context is reinstated at retrieval. In the present study, we examined whether the negative impact of stress before memory retrieval can be attenuated when memory is tested in the same environmental context as that in which learning took place. Subjects learned a 2-D object location task in a room scented with vanilla. Twenty-four hours later, they were exposed to stress or a control condition before memory for the object location task was assessed in a cued-recall test, either in the learning context or in a different context (unfamiliar room without the odor). Stress impaired memory when assessed in the unfamiliar context, but not when assessed in the learning context. These results suggest that the detrimental effects of stress on memory retrieval can be abolished when a distinct learning context is reinstated at test.

  12. Standard test method for determining residual stresses by the hole-drilling strain-gage method

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 Residual Stress Determination: 1.1.1 This test method specifies a hole-drilling procedure for determining residual stress profiles near the surface of an isotropic linearly elastic material. The test method is applicable to residual stress profile determinations where in-plane stress gradients are small. The stresses may remain approximately constant with depth (“uniform” stresses) or they may vary significantly with depth (“non-uniform” stresses). The measured workpiece may be “thin” with thickness much less than the diameter of the drilled hole or “thick” with thickness much greater than the diameter of the drilled hole. Only uniform stress measurements are specified for thin workpieces, while both uniform and non-uniform stress measurements are specified for thick workpieces. 1.2 Stress Measurement Range: 1.2.1 The hole-drilling method can identify in-plane residual stresses near the measured surface of the workpiece material. The method gives localized measurements that indicate the...

  13. Complexity-Measure-Based Sequential Hypothesis Testing for Real-Time Detection of Lethal Cardiac Arrhythmias

    Directory of Open Access Journals (Sweden)

    Chen Szi-Wen

    2007-01-01

    Full Text Available A novel approach that employs a complexity-based sequential hypothesis testing (SHT technique for real-time detection of ventricular fibrillation (VF and ventricular tachycardia (VT is presented. A dataset consisting of a number of VF and VT electrocardiogram (ECG recordings drawn from the MIT-BIH database was adopted for such an analysis. It was split into two smaller datasets for algorithm training and testing, respectively. Each ECG recording was measured in a 10-second interval. For each recording, a number of overlapping windowed ECG data segments were obtained by shifting a 5-second window by a step of 1 second. During the windowing process, the complexity measure (CM value was calculated for each windowed segment and the task of pattern recognition was then sequentially performed by the SHT procedure. A preliminary test conducted using the database produced optimal overall predictive accuracy of . The algorithm was also implemented on a commercial embedded DSP controller, permitting a hardware realization of real-time ventricular arrhythmia detection.

  14. The Application of Normal Stress Reduction Function in Tilt Tests for Different Block Shapes

    Science.gov (United States)

    Kim, Dong Hyun; Gratchev, Ivan; Hein, Maw; Balasubramaniam, Arumugam

    2016-08-01

    This paper focuses on the influence of the shapes of rock cores, which control the sliding or toppling behaviours in tilt tests for the estimation of rock joint roughness coefficients (JRC). When the JRC values are estimated by performing tilt tests, the values are directly proportional to the basic friction of the rock material and the applied normal stress on the sliding planes. Normal stress obviously varies with the shape of the sliding block, and the basic friction angle is also affected by the sample shapes in tilt tests. In this study, the shapes of core blocks are classified into three representative shapes and those are created using plaster. Using the various shaped artificial cores, a set of tilt tests is carried out to identify the shape influences on the normal stress and the basic friction angle in tilt tests. The test results propose a normal stress reduction function to estimate the normal stress for tilt tests according to the sample shapes based on Barton's empirical equation. The proposed normal stress reduction functions are verified by tilt tests using artificial plaster joints and real rock joint sets. The plaster joint sets are well matched and cast in detailed printed moulds using a 3D printing technique. With the application of the functions, the obtained JRC values from the tilt tests using the plaster samples and the natural rock samples are distributed within a reasonable JRC range when compared with the measured values.

  15. The influence of stress wave phenomena during statnamic load testing

    NARCIS (Netherlands)

    Middendorp, P.; Daniels, B.J.

    1996-01-01

    Because of its advantages compared to static and dynamic load testing, especially for bored piles, the application of Statnamic load testing has increased considerably. The Unloading Point Method (UPM) has become a standard tool for the analysis of Stat-namic (STN) load testing signals. The method i

  16. Rethinking innovative designs to further test parasite-stress theory.

    Science.gov (United States)

    Uskul, Ayse K

    2012-04-01

    Fincher & Thornhill's (F&T's) parasite-stress theory of sociality is supported largely by correlational evidence; its persuasiveness would increase significantly via lab and natural experiments and demonstrations of its mediating role. How the theory is linked to other approaches to group differences in psychological differences and to production and dissemination of cultural ideas and practices, need further clarification. So does the theory's view on the possible reduction of negative group interactions.

  17. Effects of lorazepam on cardiac vagal tone during rest and mental stress: assessment by means of spectral analysis

    NARCIS (Netherlands)

    J.H.M. Tulen (Joke); G. Mulder (G.); L. Pepplinkhuizen (Lolke); A.J. Man in't Veld (A.); H.G. van Steenis (H.); P. Moleman (Peter)

    1994-01-01

    textabstractDose-dependent effects of intravenously administered lorazepam on haemodynamic fluctuations were studied by means of spectral analysis, in order to elucidate sympathetic and parasympathetic components in cardiovascular control during situations of rest and mental stress after benzodiazep

  18. EFFECTS OF LORAZEPAM ON CARDIAC VAGAL TONE DURING REST AND MENTAL STRESS - ASSESSMENT BY MEANS OF SPECTRAL-ANALYSIS

    NARCIS (Netherlands)

    TULEN, JHM; MULDER, G; PEPPLINKHUIZEN, L; INTVELD, AJM; VANSTEENIS, HG; MOLEMAN, P

    1994-01-01

    Dose-dependent effects of intravenously administered lorazepam on haemodynamic fluctuations were studied by means of spectral analysis, in order to elucidate sympathetic and parasympathetic components in cardiovascular control during situations of rest and mental stress after benzodiazepine administ

  19. Effects of DL-homocysteine thiolactone on cardiac contractility, coronary flow, and oxidative stress markers in the isolated rat heart: the role of different gasotransmitters.

    Science.gov (United States)

    Zivkovic, Vladimir; Jakovljevic, Vladimir; Pechanova, Olga; Srejovic, Ivan; Joksimovic, Jovana; Selakovic, Dragica; Barudzic, Nevena; Djuric, Dragan M

    2013-01-01

    Considering the adverse effects of DL-homocysteine thiolactone hydrochloride (DL-Hcy TLHC) on vascular function and the possible role of oxidative stress in these mechanisms, the aim of this study was to assess the influence of DL-Hcy TLHC alone and in combination with specific inhibitors of important gasotransmitters, such as L-NAME, DL-PAG, and PPR IX, on cardiac contractility, coronary flow, and oxidative stress markers in an isolated rat heart. The hearts were retrogradely perfused according to the Langendorff technique at a 70 cm H2O and administered 10  μM DL-Hcy TLHC alone or in combination with 30  μM L-NAME, 10  μM DL-PAG, or 10  μM PPR IX. The following parameters were measured: dp/dt max, dp/dt min, SLVP, DLVP, MBP, HR, and CF. Oxidative stress markers were measured spectrophotometrically in coronary effluent through TBARS, NO2, O2(-), and H2O2 concentrations. The administration of DL-Hcy TLHC alone decreased dp/dt max, SLVP, and CF but did not change any oxidative stress parameters. DL-Hcy TLHC with L-NAME decreased CF, O2(-), H2O2, and TBARS. The administration of DL-Hcy TLHC with DL-PAG significantly increased dp/dt max but decreased DLVP, CF, and TBARS. Administration of DL-Hcy TLHC with PPR IX caused a decrease in dp/dt max, SLVP, HR, CF, and TBARS.

  20. Effects of DL-Homocysteine Thiolactone on Cardiac Contractility, Coronary Flow, and Oxidative Stress Markers in the Isolated Rat Heart: The Role of Different Gasotransmitters

    Directory of Open Access Journals (Sweden)

    Vladimir Zivkovic

    2013-01-01

    Full Text Available Considering the adverse effects of DL-homocysteine thiolactone hydrochloride (DL-Hcy TLHC on vascular function and the possible role of oxidative stress in these mechanisms, the aim of this study was to assess the influence of DL-Hcy TLHC alone and in combination with specific inhibitors of important gasotransmitters, such as L-NAME, DL-PAG, and PPR IX, on cardiac contractility, coronary flow, and oxidative stress markers in an isolated rat heart. The hearts were retrogradely perfused according to the Langendorff technique at a 70 cm H2O and administered 10 μM DL-Hcy TLHC alone or in combination with 30 μM L-NAME, 10 μM DL-PAG, or 10 μM PPR IX. The following parameters were measured: dp/dt max, dp/dt min, SLVP, DLVP, MBP, HR, and CF. Oxidative stress markers were measured spectrophotometrically in coronary effluent through TBARS, NO2, O2-, and H2O2 concentrations. The administration of DL-Hcy TLHC alone decreased dp/dt max, SLVP, and CF but did not change any oxidative stress parameters. DL-Hcy TLHC with L-NAME decreased CF, O2-, H2O2, and TBARS. The administration of DL-Hcy TLHC with DL-PAG significantly increased dp/dt max but decreased DLVP, CF, and TBARS. Administration of DL-Hcy TLHC with PPR IX caused a decrease in dp/dt max, SLVP, HR, CF, and TBARS.

  1. Aconitine Challenge Test Reveals a Single Exposure to Air Pollution Causes Increased Cardiac Arrhythmia Risk in Hypertensive Rats - Abstract

    Science.gov (United States)

    Epidemiological studies demonstrate a significant association between arrhythmias and air pollution exposure. Sensitivity to aconitine-induced arrhythmia has been used repeatedly to examine the factors that increase the risk of such cardiac electrical dysfunction. In this study, ...

  2. Cardiac arrest

    Science.gov (United States)

    ... Article.jsp. Accessed June 16, 2014. Myerburg RJ, Castellanos A. Approach to cardiac arrest and life-threatening ... PA: Elsevier Saunders; 2011:chap 63. Myerburg RJ, Castellanos A. Cardiac arrest and audden aardiac death. In: ...

  3. Triple Rule Out versus CT Angiogram Plus Stress Test for Evaluation of Chest Pain in the Emergency Department

    Directory of Open Access Journals (Sweden)

    Kelly N. Sawyer

    2015-10-01

    Full Text Available Introduction: Undifferentiated chest pain in the emergency department (ED is a diagnostic challenge. One approach includes a dedicated chest computed tomography (CT for pulmonary embolism or dissection followed by a cardiac stress test (TRAD. An alternative strategy is a coronary CT angiogram with concurrent chest CT (Triple Rule Out, TRO. The objective of this study was to describe the ED patient course and short-term safety for these evaluation methods. Methods: This was a retrospective observational study of adult patients presenting to a large, community ED for acute chest pain who had non-diagnostic electrocardiograms (ECGs and normal biomarkers. We collected demographics, ED length of stay, hospital costs, and estimated radiation exposures. We evaluated 30-day return visits for major adverse cardiac events. Results: A total of 829 patients underwent TRAD, and 642 patients had TRO. Patients undergoing TRO tended to be younger (mean 52.3 vs 56.5 years and were more likely to be male (42.4% vs. 30.4%. TRO patients tended to have a shorter ED length of stay (mean 14.45 vs. 21.86 hours, to incur less cost (median $449.83 vs. $1147.70, and to be exposed to less radiation (median 7.18 vs. 16.6mSv. No patient in either group had a related 30-day revisit. Conclusion: Use of TRO is feasible for assessment of chest pain in the ED. Both TRAD and TRO safely evaluated patients. Prospective studies investigating this diagnostic strategy are needed to further assess this approach to ED chest pain evaluation.

  4. FlowPing - The New Tool for Throughput and Stress Testing

    Directory of Open Access Journals (Sweden)

    Ondrej Vondrous

    2015-01-01

    Full Text Available This article presents a new tool for network throughput and stress testing. The FlowPing tool is easy to use, and its basic output is very similar to standard Linux ping application. The FlowPing tool is not limited to reach-ability or round trip time testing but is capable of complex UDP based throughput stress testing with rich reporting capabilities on client and server sides. Our new tool implements features, which allow the user to perform tests with variable packet size and traffic rate. All these features can be used in one single test run. This allows the user to use and develop new methodologies for network throughput and stress testing. With the FlowPing tool, it is easy to perform the test with the slowly increasing the amount of network traffic and monitor the behavior of network when the congestion occurs.

  5. Visual Stress Theory and Its Application to Reading and Reading Tests

    Science.gov (United States)

    Wilkins, Arnold; Huang, Jie; Cao, Yue

    2004-01-01

    This paper presents a theory of visual stress. The theory is applied to the assessment of symptoms of visual stress and its treatment with coloured filters. The theory has implications for standard reading assessments that relate both to the visual skills and the age of the children taking the tests. These implications are reviewed, with the…

  6. Effects of stress conditions on rheological properties of granular soil in large triaxial rheology laboratory tests

    Institute of Scientific and Technical Information of China (English)

    陈晓斌; 张家生; 刘宝琛; 唐孟雄

    2008-01-01

    In order to study the rheological properties of red stone granular soil,a series of rheological experiments were executed on large tri-axial rheological apparatus.Under 100,200 and 300 kPa confining stress conditions,the rheological tests were carried out.These experiment results showed that the stress conditions,especially the stress level were the critical influencing factors of the rheological deformation properties.Under the low stress level(S=0.1),the granular soil showed the elastic properties,and there was no obvious rheological deformation.Under the middle stress level(0.2stress level(S>0.8) creep curves showed the non-linear viscous plastic rheological properties.Especially,under the stress level of S=1.0,the accelerated rheological phase of creep curves occurred at early time with a trend of failure.The stress level had obvious effects on the final rheological deformation of the soil sample,and the final rheological deformation increments nonlinearly increased with stress level.The final rheological deformation increment and step was little under low stress level,while it became large under high stress level,which showed the nonlinearly rheological properties of the granular soil.The confining pressure also had direct effects on final rheological deformation,and the final rheological deformation linearly increased with confining pressure increments.

  7. Testing the responses of four wheat crop models to heat stress at anthesis and grain filling.

    Science.gov (United States)

    Liu, Bing; Asseng, Senthold; Liu, Leilei; Tang, Liang; Cao, Weixing; Zhu, Yan

    2016-05-01

    Higher temperatures caused by future climate change will bring more frequent heat stress events and pose an increasing risk to global wheat production. Crop models have been widely used to simulate future crop productivity but are rarely tested with observed heat stress experimental datasets. Four wheat models (DSSAT-CERES-Wheat, DSSAT-Nwheat, APSIM-Wheat, and WheatGrow) were evaluated with 4 years of environment-controlled phytotron experimental datasets with two wheat cultivars under heat stress at anthesis and grain filling stages. Heat stress at anthesis reduced observed grain numbers per unit area and individual grain size, while heat stress during grain filling mainly decreased the size of the individual grains. The observed impact of heat stress on grain filling duration, total aboveground biomass, grain yield, and grain protein concentration (GPC) varied depending on cultivar and accumulated heat stress. For every unit increase of heat degree days (HDD, degree days over 30 °C), grain filling duration was reduced by 0.30-0.60%, total aboveground biomass was reduced by 0.37-0.43%, and grain yield was reduced by 1.0-1.6%, but GPC was increased by 0.50% for cv Yangmai16 and 0.80% for cv Xumai30. The tested crop simulation models could reproduce some of the observed reductions in grain filling duration, final total aboveground biomass, and grain yield, as well as the observed increase in GPC due to heat stress. Most of the crop models tended to reproduce heat stress impacts better during grain filling than at anthesis. Some of the tested models require improvements in the response to heat stress during grain filling, but all models need improvements in simulating heat stress effects on grain set during anthesis. The observed significant genetic variability in the response of wheat to heat stress needs to be considered through cultivar parameters in future simulation studies.

  8. Bayesian Approach for Constant-Stress Accelerated Life Testing for Kumaraswamy Weibull Distribution with Censoring

    Directory of Open Access Journals (Sweden)

    Abeer Abd-Alla EL-Helbawy

    2016-09-01

    Full Text Available The accelerated life tests provide quick information on the life time distributions by testing materials or products at higher than basic conditional levels of stress such as pressure, high temperature, vibration, voltage or load to induce failures. In this paper, the acceleration model assumed is log linear model. Constant stress tests are discussed based on Type I and Type II censoring. The Kumaraswmay Weibull distribution is used. The estimators of the parameters, reliability, hazard rate functions and p-th percentile at normal condition, low stress, and high stress are obtained. In addition, credible intervals for parameters of the models are constructed. Optimum test plan are designed. Some numerical studies are used to solve the complicated integrals such as Laplace and Markov Chain Monte Carlo methods.

  9. In-situ stress from hydraulic fracture measurements in G Tunnel, Nevada Test Site

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C.; Vollendorf, W. C.; Warren, W. E.

    1981-04-01

    Hydraulic fracture work in G Tunnel, Nevada Test Site, performed to obtain the in-situ stress state is discussed. Field equipment and procedures are described; analysis is developed to relate the hydraulic fracture pressures to the in-situ stress state. Pressure data are analyzed to provide estimates of the stress state at a number of locations in the tunnel complex. A unique feature of the work is the mineback - a mining process in which the rock is cut away to reveal the actual plane of the fracture. Advantages, limitations, and problem areas associated with extracting in-situ stress fields from hydraulic fracture pressure records are discussed in detail.

  10. Stress Testing Liquidity Risk: The Case of the Brazilian Banking System.

    OpenAIRE

    Benjamin M. Tabak; Solange M. Guerra; Rodrigo C. Miranda; Sergio Rubens S. de Souza

    2012-01-01

    This paper discusses the effects of the recent financial crisis on the Brazilian banking system. It discusses how liquidity risks have risen during the crisis and preventive measures that were taken in order to cope with these risks. It presents the liquidity stress testing approach that is under use in the Central Bank of Brazil and results from a survey on liquidity stress testing that has been applied to banks that operate in the Brazilian banking system.

  11. Dynamic tensile testing for determining the stress-strain curve at different strain rate

    OpenAIRE

    Mansilla, A; Regidor, A.; García, D.; Negro, A

    2001-01-01

    A detailed discussion of high strain-rate tensile testing is presented. A comparative analysis of different ways to measure stress and strain is made. The experimental stress-strain curves have been suitably interpreted to distinguish between the real behaviour of the material and the influence of the testing methodology itself. A special two sections flat specimen design was performed through FEA computer modelling. The mechanical properties as function of strain rate were experimentally obt...

  12. Stress cycle testing during creep of a particle-strengthened Nb-1Zr-0.1C alloy

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, D.M. [California Univ., Davis (United States). Dept. of Chemical Engineering]|[California Univ., Davis, CA (United States). Div. of Materials Science and Engineering; Mukherjee, A.K. [California Univ., Davis (United States). Dept. of Chemical Engineering]|[California Univ., Davis, CA (United States). Div. of Materials Science and Engineering

    1997-01-01

    Stress cycle testing was performed during high-temperature creep of a particle-strengthened alloy of niobium (Nb-1Zr-0.1C). Two methods were used to analyze the data from the stress cycles to determine the back stress arising from the dislocation substructure as a function of applied stress, temperature, and accumulated strain. Back stresses as high as 96% of the applied stress were measured. In general, the normalized effective stress, calculated from the dislocation back stress, was shown to be independent of the applied stress and temperature. (orig.)

  13. Butanolic fraction of Moringa oleifera Lam. (Moringaceae) attenuates isoprotrenol-induced cardiac necrosis and oxidative stress in rats: an EPR study.

    Science.gov (United States)

    Panda, Sunanda

    2015-01-01

    The preventive effect of Moringa oleifera polyphenolic fraction (MOPF) on cardiac damage was evaluated in isoproterenol (ISO) induced cardiotoxicity model of Wistar rats. Male rats in different groups were treated with MOPF orally at the dose of 50, 100 and 150 mg/kg/day for 28 days and were subsequently administered (s.c.) with ISO (85 mg/kg body weight) for the last two days. At the end of the experiment levels of serum troponin-T, creatine kinase-MB, lactate dehydrogenase, content of malondialdehyde (MDA), activities/levels of different cellular antioxidants were estimated in control and experimental groups. Additionally, scavenging potential to the hydroxyl radical of the fraction was measured by electron paramagnetic resonance (EPR). ISO administered rats showed significant increase in the levels of serum troponin-I, creatine kinase, lactate dehydrogenase, and heart tissue MDA content. Furthermore, marked reduction in the activities of antioxidants such as superoxide dismutase, catalase, glutathione peroxidase and reduced glutathione levels were observed. EPR study showed an increase in signal intensity in ISO-induced rats. Triphenyl tetrazolium chloride (TTC) staining of heart section revealed a marked increase in infarcted area in ISO-induced rats. Histological features of the heart also indicated a disruption in the structure of cardiac myofibrils in these animals. MOPF (100 mg/kg body weight) pretreatment prevented all these adverse effects of ISO. Present results show that the rich polyphenolic content of Moringa oleifera significantly reduced the myocardial damage and decreased the oxidative stress, possibly through hydroxyl radical scavenging activity as evidenced from the EPR spectra.

  14. CORTICOTROPIN-RELEASING HORMONE MICROINFUSION IN THE CENTRAL AMYGDALA DIMINISHES A CARDIAC PARASYMPATHETIC OUTFLOW UNDER STRESS-FREE CONDITIONS

    NARCIS (Netherlands)

    WIERSMA, A; BOHUS, B; KOOLHAAS, JM

    1993-01-01

    The central nucleus of the amygdala (CeA) is known to be involved in the regulation of autonomic, neuroendocrine and behavioural responses in stress situations. The CeA contains large numbers of corticotropin-releasing hormone (CRH) cell bodies. Neuroanatomical studies revealed that the majority of

  15. Are Cardiac Autonomic Nervous System Activity and Perceived Stress Related to Functional Somatic Symptoms in Adolescents? The TRAILS Study

    NARCIS (Netherlands)

    K.A.M. Janssens (Karin); H. Riese (Harriëtte); A.M.M. van Roon (Arie); J.A.M. Hunfeld (Joke); Groot, P.F.C. (Paul F. C.); A.J. Oldehinkel (Albertine); J.G.M. Rosmalen (Judith)

    2016-01-01

    textabstractObjective Stressors have been related to medically insufficiently explained or functional somatic symptoms (FSS). However, the underlying mechanism of this association is largely unclear. In the current study, we examined whether FSS are associated with different perceived stress and car

  16. [Biomechanical test study of rat femurs growing under different stress environment].

    Science.gov (United States)

    Liu, Yingxi; Zhao, Wenzhi; Zhang, Jun; Li, Shouju; Li, Jingnian; Sun, Xiaojiang

    2005-06-01

    By creating two kinds of stress environment in the same animal model, we performed a three-point bending test and a compressing test on the rat femurs growing under different stress conditions to characterize the effect of stress on bone mechanical properties. The right hindlimbs were subjected to sciatic nerve resection to become cripple and were used as unloading group; the left hindlimbs bore excess load and made up the overloading group; the normal rats were used as control group. The animals were encouraged to exercise for half an hour everyday in the morning, noon and evening. The experiment observation finished in four weeks. The biomechanical parameters of femur diaphyses were measured. The experiment results showed that stress environment may change several mechanical parameters of rat femurs. This study indicated that bone tissues can adapt to its stress environment by changing its mechanical properties. The experimental model in this article is practical and reliable.

  17. Protective Effect of Sevoflurane Postconditioning against Cardiac Ischemia/Reperfusion Injury via Ameliorating Mitochondrial Impairment, Oxidative Stress and Rescuing Autophagic Clearance.

    Directory of Open Access Journals (Sweden)

    Peng Yu

    Full Text Available Myocardial infarction leads to heart failure. Autophagy is excessively activated in myocardial ischemia/reperfusion (I/R in rats. The aim of this study is to investigate whether the protection of sevoflurane postconditioning (SPC in myocardial I/R is through restored impaired autophagic flux.Except for the sham control (SHAM group, each rat underwent 30 min occlusion of the left anterior descending coronary (LAD followed by 2 h reperfusion. Cardiac infarction was determined by 2,3,5-triphenyltetrazolium chloride triazole (TTC staining. Cardiac function was examined by hemodynamics and echocardiography. The activation of autophagy was evaluated by autophagosome accumulation, LC3 conversion and p62 degradation. Potential molecular mechanisms were investigated by immunoblotting, real-time PCR and immunofluorescence staining.SPC improved the hemodynamic parameters, cardiac dysfunction, histopathological and ultrastructural damages, and decreased myocardial infarction size after myocardial I/R injury (P < 0.05 vs. I/R group. Compared with the cases in I/R group, myocardial ATP and NAD+ content, mitochondrial function related genes and proteins, and the expressions of SOD2 and HO-1 were increased, while the expressions of ROS and Vimentin were decreased in the SPC group (P < 0.05 vs. I/R group. SPC significantly activated Akt/mTOR signaling, and inhibited the formation of Vps34/Beclin1 complex via increasing expression of Bcl2 protein (P < 0.05 vs. I/R group. SPC suppressed elevated expressions of LC3 II/I ratio, Beclin1, Atg5 and Atg7 in I/R rat, which indicated that SPC inhibited over-activation of autophagy, and promoted autophagosome clearance. Meanwhile, SPC significantly suppressed the decline of Opa1 and increases of Drp1 and Parkin induced by I/R injury (P < 0.05 vs. I/R group. Moreover, SPC maintained the contents of ATP by reducing impaired mitochondria.SPC protects rat hearts against I/R injury via ameliorating mitochondrial impairment

  18. Small Stress Change Triggering a Big Earthquake: a Test of the Critical Point Hypothesis for Earthquakes

    Institute of Scientific and Technical Information of China (English)

    万永革; 吴忠良; 周公威

    2003-01-01

    Whether or not a small stress change can trigger a big earthquake is one of the most important problems related to the critical point hypothesis for earthquakes. We investigate global earthquakes with different focal mechanisms which have different levels of ambient shear stress. This ambient stress level is the stress level required by the earthquakes for their occurrence. Earthquake pairs are studied to see whether the occurrence of the preceding event encourages the occurrence of the succeeding one in terms of the Coulomb stress triggering. It is observed that the stress triggering effect produced by the change of Coulomb failure stress in the same order of magnitudes,about 10-2 MPa, is distinctly different for different focal mechanisms, and thus for different ambient stress levels.For non-strike-slip earthquakes with a relatively low ambient stress level, the triggering effect is more evident,while for strike-slip earthquakes with a relatively high ambient stress level, there is no evident triggering effect.This water level test provides an observational support to the critical point hypothesis for earthquakes.

  19. Spatial and temporal task characteristics as stress: a test of the dynamic adaptability theory of stress, workload, and performance.

    Science.gov (United States)

    Szalma, James L; Teo, Grace W L

    2012-03-01

    The goal for this study was to test assertions of the dynamic adaptability theory of stress, which proposes two fundamental task dimensions, information rate (temporal properties of a task) and information structure (spatial properties of a task). The theory predicts adaptive stability across stress magnitudes, with progressive and precipitous changes in adaptive response manifesting first as increases in perceived workload and stress and then as performance failure. Information structure was manipulated by varying the number of displays to be monitored (1, 2, 4 or 8 displays). Information rate was manipulated by varying stimulus presentation rate (8, 12, 16, or 20 events/min). A signal detection task was used in which critical signals were pairs of digits that differed by 0 or 1. Performance accuracy declined and workload and stress increased as a function of increased task demand, with a precipitous decline in accuracy at the highest demand levels. However, the form of performance change as well as the pattern of relationships between speed and accuracy and between performance and workload/stress indicates that some aspects of the theory need revision. Implications of the results for the theory and for future research are discussed.

  20. Stress and Psychological Health: Testing the Mediating Role of Cognitive Appraisal.

    Science.gov (United States)

    Gomes, A Rui; Faria, Susana; Lopes, Heitor

    2016-06-21

    This study tested the mediating role of primary (e.g., threat and challenge perceptions) and secondary (e.g., coping potential and control perception) cognitive appraisal in the relationship between occupational stress and psychological health. This mediation was tested using a cross-sectional study based on self-reported measures. The total sample consisted of 2,302 nurses, 1,895 females (82.3%) and 407 males (17.7%), who completed an evaluation protocol with measures of occupational stress, cognitive appraisal, and psychological health. To test the mediating role of cognitive appraisal in the relationship between cognitive appraisal and psychological health, we used Structural Equation Modeling (SEM). The results confirmed that primary and secondary cognitive appraisals partially mediated the relationship between occupational stress and psychological health; however, the direct effects of stress on psychological health cannot be ignored. The findings indicated that cognitive appraisal is an important underlying mechanism in explaining adaptation at work.

  1. Organizational and media stress among professional football players: testing an achievement goal theory model.

    Science.gov (United States)

    Kristiansen, E; Halvari, H; Roberts, G C

    2012-08-01

    The purpose of this study was to investigate media and coach-athlete stress experienced by professional football players and their relationship to motivational variables by testing an achievement goal theory (AGT) stress model. In order to do so, we developed scales specifically designed to assess media and coach-athlete stress. Eighty-two elite football players (M(age) =25.17 years, SD=5.19) completed a series of questionnaires. Correlations and bootstrapping were used as primary statistical analyses, supplemented by LISREL, to test the hypotheses. Results revealed that a mastery climate was directly and negatively associated with coach-athlete stress, while a performance climate was directly and positively associated with coach-athlete stress. In addition, an indirect positive path between the performance climate and media stress was revealed through ego orientation. These findings support some of the key postulates of AGT; a mastery climate reduces the perception of stress among athletes, and the converse is true for a performance climate. Coaches of elite footballers are advised to try to reduce the emphasis on performance criteria because of its stress-reducing effects.

  2. Unconscious fearful priming followed by a psychosocial stress test results in higher cortisol levels.

    Science.gov (United States)

    Hänsel, Alexander; von Känel, Roland

    2013-10-01

    Human perception of stress includes an automatic pathway that processes subliminal presented stimuli below the threshold of conscious awareness. Subliminal stimuli can therefore activate the physiologic stress system. Unconscious emotional signals were shown to significantly moderate reactions and responses to subsequent stimuli, an effect called 'priming'. We hypothesized that subliminal presentation of a fearful signal during the Stroop task compared with an emotionally neutral one will prime stress reactivity in a subsequently applied psychosocial stress task, thereby yielding a significant increase in salivary cortisol. Half of 36 participants were repeatedly presented either a fearful face or a neutral one. After this, all underwent a psychosocial stress task. The fearful group showed a significant increase in cortisol levels (p = 0.022). This change was not affected by sex, age and body mass index, and it also did not change when taking resting cortisol levels into account. Post-hoc analyses showed that the increase in cortisol in the fearful group started immediately after the psychosocial stress test. Hence, subliminal exposure to a fearful signal in combination with the Stroop and followed by a psychosocial stress test leads to an increase in stress reactivity.

  3. Effects of chronic and acute stress on rat behaviour in the forced-swim test.

    Science.gov (United States)

    Suvrathan, Aparna; Tomar, Anupratap; Chattarji, Sumantra

    2010-11-01

    Stress and depression may share common neural plasticity mechanisms. Importantly, the development and reversal of stress-induced plasticity requires time. These temporal aspects, however, are not captured fully in the forced-swim test (FST), a behavioural model for testing antidepressant efficacy, used originally in naïve animals. The present study probed whether and how a rodent model of stress affects behaviour in the FST over time. We found that the intensity and duration of stress are critical in the development of depressive symptoms in male Wistar rats (n = 37) as tested in the FST. Chronic immobilization stress (2 h/day for 10 days) elicited a range of responses, from low to high values of immobility in the FST on day 1, and subsequent immobility on day 2 was inversely related to individual day 1 values. As a whole, chronically stressed rats did not exhibit any significant change in immobility either on day 1 or day 2 compared to control rats. However, climbing behaviour was reduced uniformly from day 1 to day 2, despite the differences in immobility. In contrast, a separate group of rats (n = 30) subjected to the same chronic stressor displayed a significant reduction in open-arm exploration in the elevated plus maze, indicative of a robust increase in anxiety-like behaviour. Furthermore, when the 10-day chronic stress paradigm was reduced to a single 2-h episode of immobilization stress, it triggered a uniform day 1 to day 2 increase in immobility, which was not persistent 10 days later. These results highlight a need for closer examination of the ways in which stress-induced modulation of behaviour in the FST may be used and interpreted in future studies aimed at exploring connections between stress and depression.

  4. ROLE OF EXERCISE STRESS TEST IN DETECTING UNDERLYING MYOCARDIAL ISCHEMIA

    Directory of Open Access Journals (Sweden)

    Sachin N.

    2014-07-01

    Full Text Available BACKGROUND: Ischemic heart disease (IHD is the leading cause of death and disability in industrialized countries. In India also there is increasing trends of death and disability due to IHD. The prevalence of IHD in India is 96.7/1000 in urban and 27.1/1000 in rural areas. Main risk factors for IHD are diabetes mellitus, hypertension, obesity, smoking and hyperlipidemia. AIM: The present study aims at early detection of IHD which can prevent death and disability in persons with risk factors. DESIGN: The present study is cross sectional observational study carried out in the govt. medical college of rural Indian set-up. MATERIALS AND METHODS: The present study was carried out on 70 asymptomatic patients of age group 30-70 years with any of the above mentioned risk factors for IHD. The treadmill test was performed in these patients. STATISTICAL ANALYSIS: The analysis was done using MS office excel 2007 software. RESULTS: 24.22% patients showed positive treadmill test. This means 24.22% of patients were having underlying IHD though they were asymptomatic. CONCLUSION: Thus treadmill test is a valuable, non-invasive tool for early detection of myocardial ischemia among the asymptomatic patients with risk factors for coronary artery disease.

  5. High glucose induced oxidative stress and apoptosis in cardiac microvascular endothelial cells are regulated by FoxO3a.

    Directory of Open Access Journals (Sweden)

    Chaoming Peng

    Full Text Available AIM: Cardiac microvascular endothelial cells (CMECs dysfunction contributes to cardiovascular complications in diabetes, whereas, the underlying mechanism is not fully clarified. FoxO transcription factors are involved in apoptosis and reactive oxygen species (ROS production. Therefore, the present study was designed to elucidate the potential role of FoxO3a on the CMECs injury induced by high glucose. MATERIALS AND METHODS: CMECs were isolated from hearts of adult rats and cultured in normal or high glucose medium for 6 h, 12 h and 24 h respectively. To down-regulate FoxO3a expression, CMECs were transfected with FoxO3a siRNA. ROS accumulation and apoptosis in CMECs were assessed by dihydroethidine (DHE staining and TUNEL assay respectively. Moreover, the expressions of Akt, FoxO3a, Bim and BclxL in CMECs were assessed by Western blotting assay. RESULTS: ROS accumulation in CMECs was significantly increased after high glucose incubation for 6 to 24 h. Meanwhile, high glucose also increased apoptosis in CMECs, correlated with decreased the phosphorylation expressions of Akt and FoxO3a. Moreover, high glucose incubation increased the expression of Bim, whereas increased anti-apoptotic protein BclxL. Furthermore, siRNA target FoxO3a silencing enhanced the ROS accumulation, whereas suppressed apoptosis in CMECs. FoxO3a silencing also abolished the disturbance of Bcl-2 proteins induced by high glucose in CMECs. CONCLUSION: Our data provide evidence that high glucose induced FoxO3a activation which suppressed ROS accumulation, and in parallel, resulted in apoptosis of CMECs.

  6. Stress Tests for Chest Pain: When You Need an Imaging Test -- and When You Don't

    Science.gov (United States)

    ... disease. But chest pain can have many possible causes besides heart disease, such as indigestion, anxiety, or muscle injury. If the doctor’s initial evaluation shows that you probably don’t have a heart problem, you may not need a stress test at all. And if you do, a simple ...

  7. Psychological stress and infertility. Part 2: Psychometric test data.

    Science.gov (United States)

    Brand, H J

    1982-12-01

    The hypothesis tested in this study was that a group of female functional infertile patients would show significantly more personality maladjustment than a group with definite organic reproductive pathology and a normal fertile group. No significant differences between the functional and organic groups were found on any of the subscores of four personality questionnaires. The normal group (wives of sterile men) scored higher on extraversion than both the functional and organic groups. On self-control the normal group also scored lower (negative connotation) than the other two groups. In general no evidence for personality maladjustment in functional infertility was found.

  8. [Magnesium deficiency and stress: Issues of their relationship, diagnostic tests, and approaches to therapy].

    Science.gov (United States)

    Tarasov, E A; Blinov, D V; Zimovina, U V; Sandakova, E A

    2015-01-01

    Magnesium plays an important role in the functions of the central nervous system. It takes part in the regulation of the cell membrane, the transmembrane transport of calcium and sodium ions, and metabolic reactions that produce, accumulate, transfer, and utilize energy, free radicals, and their oxidation products. The magnesium-containing substances include many sequestered antigens, such as glial fibrillary acidic protein, S100, and neuron-specific enolase; magnesium may act as a neuroprotector that is able to modulate the regulation of blood-brain barrier permeability. Investigations have demonstrated a relationship between the manifestations of stress reactions (anxiety, autonomic dysfunction, and maladjustment) and magnesium deficiency (MD). Thus, mental and physical stresses cause an increase in magnesium elimination from the body. MD in turn enhances a response to stress, by paradoxically aggravating its sequels. Compensation for MD increases the ability of the nervous system to resist stress. The valid diagnosis of MD present difficulties; namely, a blood magnesium concentration decrease below 0.8 mmol/l is evidence of MD; but the constant blood level of magnesium may be long maintained due to its release from the bone tissue depot. So it is necessary to keep in mind the clinical manifestations of MD. The authors have developed and tested a simple rapid MD assessment test and a stress resistance self-rating test. The proposed tests will help to screen stress resistance and MD in outpatient settings.

  9. A Study on the Storage Reliability of LSINS Based on Step-stress Accelerated Life Test

    Directory of Open Access Journals (Sweden)

    Teng Fei

    2015-01-01

    Full Text Available Based on the step-stress accelerated life test and the laser strap-down inertial navigation system, this paper studies the accelerated life model and the test method, provides the likelihood function, the likelihood equation and the two-order derivative when the stress level is k, evaluates the effectiveness of the method with the simulation test model established by MATLAB, applies the research findings in the storage reliability study of the XX laser strap-down inertial navigation system, and puts forward an effective evaluation method of the storage life of the inertial navigation system.

  10. Stress Testing Recovery EMG for Evaluation of Biofeedback and Progressive Muscle Relaxation Training Effects.

    Science.gov (United States)

    Sime, Wesley E.; DeGood, Douglas E.

    The purpose of this investigation was to assess biofeedback (BF) and progressive muscle relaxation (PMR) and placebo-control training by means of a post-training transfer test. The subjects for the research were 30 women. Initial tests consisted of measuring the electromyographic response of the frontalis muscle of the forehead to stress. After…

  11. Stress and Anxiety Surrounding Forthcoming Standard Assessment Tests in English Schoolchildren

    Science.gov (United States)

    Putwain, Dave W.; Connors, Liz; Woods, Kevin; Nicholson, Laura J.

    2012-01-01

    The Standard Assessment Tests (SATs) taken by pupils in their final year of primary schooling in England have been widely criticised for placing children under too pressure and contributing to an increase in test-related stress and anxiety. In this exploratory study we set out to explore the experiences of forthcoming SATs in a small sample of…

  12. Finger arterial versus intrabrachial pressure and continuous cardiac output during head-up tilt testing in healthy subjects

    NARCIS (Netherlands)

    Jellema, W.T.; Imholz, B.P.M.; Goudoever, J. van; Wesseling, K.H.; Lieshout, J.J. van

    1996-01-01

    1. The aims of this study were to determine the clinical feasibility of continuous, non-invasive Finapres recordings as a replacement for intrabrachial pressure during a 30 min head-up tilt, and the reliability of continuous cardiac output computation by pulse contour analysis from the finger arteri

  13. Partial Shade Stress Test for Thin-Film Photovoltaic Modules: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Silverman, Timothy J.; Deceglie, Michael G.; Deline, Chris; Kurtz, Sarah

    2015-09-02

    Partial shade of monolithic thin-film PV modules can cause reverse-bias conditions leading to permanent damage. In this work, we propose a partial shade stress test for thin-film PV modules that quantifies permanent performance loss. We designed the test with the aid of a computer model that predicts the local voltage, current and temperature stress that result from partial shade. The model predicts the module-scale interactions among the illumination pattern, the electrical properties of the photovoltaic material and the thermal properties of the module package. The test reproduces shading and loading conditions that may occur in the field. It accounts for reversible light-induced performance changes and for additional stress that may be introduced by light-enhanced reverse breakdown. We present simulated and experimental results from the application of the proposed test.

  14. Standard test method for calibration of surface/stress measuring devices

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1997-01-01

    Return to Contents page 1.1 This test method covers calibration or verification of calibration, or both, of surface-stress measuring devices used to measure stress in annealed and heat-strengthened or tempered glass using polariscopic or refractometry based principles. 1.2 This test method is nondestructive. 1.3 This test method uses transmitted light, and therefore, is applicable to light-transmitting glasses. 1.4 This test method is not applicable to chemically tempered glass. 1.5 Using the procedure described, surface stresses can be measured only on the “tin” side of float glass. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  15. Stress mitigation of x-ray beamline monochromators using topography test unit.

    Energy Technology Data Exchange (ETDEWEB)

    Maj, J.; Waldschmidt, G.; Baldo, P.; Macrander, A.; Koshelev, I.; Huang, R.; Maj, L.; Maj, A.; Univ. of Chicago; Northeastern Ohio Univ. Coll. of Medicine; Rosalind Franklin Univ. of Medicine and Science

    2007-01-01

    Silicon and diamond monochromators (crystals), often used in the Advanced Photon Source X-ray beamlines, require a good quality surface finish and stress-free installation to ensure optimal performance. The device used to mount the crystal has been shown to be ajor contributing source of stress. In this case, an adjustable mounting device is an effective method of reducing stresses and improve the rocking curve to levels much closer to ideal. Analysis by a topography test unit has been used to determine the distribution of stresses and to measure the rocking curve, as well as create CCD images of the crystal. This paper describes the process of measuring these stresses and manipulating the mounting device and crystal to create a substantially improved monochromator.

  16. Relationship between female cardiac insufficiency and oxidative stress as well as prolactin cracking%氧化应激和泌乳素裂解与女性心功能不全的关系

    Institute of Scientific and Technical Information of China (English)

    王楠; 李万鹏; 周淑红

    2013-01-01

    氧化应激是心功能不全发生发展的重要机制之一.氧化应激导致组织蛋白酶D激活,组织蛋白酶D将泌乳激素由23 kDa裂解为16 kDa.16 kDa泌乳素抑制血管内皮生成和促进细胞凋亡,与女性心功能不全有关.%Oxidative stress is one of the important mechanisms in the occurrence and development of cardiac dysfunction.Oxidative stress causes cathepsin D activation,which in turn,makes prolactin crack from 23 kDa to 16 kDa.This cracked 16 kDa prolactin inhibits endothelial formation and promotes cell apoptosis,which is related with female cardiac dysfunction.

  17. Assessing corrosion problems in photovoltaic cells via electrochemical stress testing

    Science.gov (United States)

    Shalaby, H.

    1985-01-01

    A series of accelerated electrochemical experiments to study the degradation properties of polyvinylbutyral-encapsulated silicon solar cells has been carried out. The cells' electrical performance with silk screen-silver and nickel-solder contacts was evaluated. The degradation mechanism was shown to be electrochemical corrosion of the cell contacts; metallization elements migrate into the encapsulating material, which acts as an ionic conducting medium. The corrosion products form a conductive path which results in a gradual loss of the insulation characteristics of the encapsulant. The precipitation of corrosion products in the encapsulant also contributes to its discoloration which in turn leads to a reduction in its transparency and the consequent optical loss. Delamination of the encapsulating layers could be attributed to electrochemical gas evolution reactions. The usefulness of the testing technique in qualitatively establishing a reliability difference between metallizations and antireflection coating types is demonstrated.

  18. Cardiac Sarcoidosis.

    Science.gov (United States)

    Birnie, David; Ha, Andrew C T; Gula, Lorne J; Chakrabarti, Santabhanu; Beanlands, Rob S B; Nery, Pablo

    2015-12-01

    Studies suggest clinically manifest cardiac involvement occurs in 5% of patients with pulmonary/systemic sarcoidosis. The principal manifestations of cardiac sarcoidosis (CS) are conduction abnormalities, ventricular arrhythmias, and heart failure. Data indicate that an 20% to 25% of patients with pulmonary/systemic sarcoidosis have asymptomatic (clinically silent) cardiac involvement. An international guideline for the diagnosis and management of CS recommends that patients be screened for cardiac involvement. Most studies suggest a benign prognosis for patients with clinically silent CS. Immunosuppression therapy is advocated for clinically manifest CS. Device therapy, with implantable cardioverter defibrillators, is recommended for some patients.

  19. Short-Term Nose-Only Water-Pipe (Shisha Smoking Exposure Accelerates Coagulation and Causes Cardiac Inflammation and Oxidative Stress in Mice

    Directory of Open Access Journals (Sweden)

    Abderrahim Nemmar

    2015-01-01

    Full Text Available Background/Aim: Water-pipe smoking (WPS has acquired worldwide popularity, and is disseminating particularly rapidly in Europe and North America. However, little is known about the short-term cardiovascular effects of WPS. Methods: Presently, we assessed the short-term cardiovascular effects of nose-only exposure to mainstream WPS in BALB/c mice for 30 min/day for 5 consecutive days. Control mice were exposed to air. At the end of the exposure period, several cardiovascular endpoints were measured. Results: WPS did not affect the number of leukocytes and the plasma concentrations of C-reactive protein, tumor necrosis factor α (TNFα and interleukin-6 (IL-6. Likewise, plasma levels of lipid peroxidation (LPO, reduced glutathione (GSH and catalase were not affected by WPS. By contrast, WPS aggravated in vivo thrombosis by shortening the thrombotic occlusion time in pial arterioles and venules. The number of circulating platelets was reduced by WPS suggesting the occurrence of platelet aggregation in vivo. Elevated concentrations of fibrinogen and plasminogen activator inhibitor-1 were seen after the exposure to WPS. Blood samples taken from mice exposed to WPS and exposed to adenosine diphosphate showed more platelet aggregation. The heart concentrations of IL-6 and TNFα were augmented by WPS. Likewise, heart levels of LPO, reactive oxygen species and the antioxidants catalase and GSH were increased by WPS. However, the systolic blood pressure and heart rate were not affected by WPS. Conclusion: It can be concluded that short-term exposure to WPS exerts procoagulatory effects and induce cardiac inflammation and oxidative stress. At the time point investigated, there was no evidence for blood inflammation or oxidative stress.

  20. Zinc rescues obesity-induced cardiac hypertrophy via stimulating metallothionein to suppress oxidative stress-activated BCL10/CARD9/p38 MAPK pathway.

    Science.gov (United States)

    Wang, Shudong; Gu, Junlian; Xu, Zheng; Zhang, Zhiguo; Bai, Tao; Xu, Jianxiang; Cai, Jun; Barnes, Gregory; Liu, Qiu-Ju; Freedman, Jonathan H; Wang, Yonggang; Liu, Quan; Zheng, Yang; Cai, Lu

    2017-02-03

    Obesity often leads to obesity-related cardiac hypertrophy (ORCH), which is suppressed by zinc-induced inactivation of p38 mitogen-activated protein kinase (p38 MAPK). In this study, we investigated the mechanisms by which zinc inactivates p38 MAPK to prevent ORCH. Mice (4-week old) were fed either high fat diet (HFD, 60% kcal fat) or normal diet (ND, 10% kcal fat) containing variable amounts of zinc (deficiency, normal and supplement) for 3 and 6 months. P38 MAPK siRNA and the p38 MAPK inhibitor SB203580 were used to suppress p38 MAPK activity in vitro and in vivo, respectively. HFD activated p38 MAPK and increased expression of B-cell lymphoma/CLL 10 (BCL10) and caspase recruitment domain family member 9 (CARD9). These responses were enhanced by zinc deficiency and attenuated by zinc supplement. Administration of SB203580 to HFD mice or specific siRNA in palmitate-treated cardiomyocytes eliminated the HFD and zinc deficiency activation of p38 MAPK, but did not significantly impact the expression of BCL10 and CARD9. In cultured cardiomyocytes, inhibition of BCL10 expression by siRNA prevented palmitate-induced increased p38 MAPK activation and atrial natriuretic peptide (ANP) expression. In contrast, inhibition of p38 MAPK prevented ANP expression, but did not affect BCL10 expression. Deletion of metallothionein abolished the protective effect of zinc on palmitate-induced up-regulation of BCL10 and phospho-p38 MAPK. HFD and zinc deficiency synergistically induce ORCH by increasing oxidative stress-mediated activation of BCL10/CARD9/p38 MAPK signalling. Zinc supplement ameliorates ORCH through activation of metallothionein to repress oxidative stress-activated BCL10 expression and p38 MAPK activation.

  1. A Modified Constant-Stress Coupon for Enhanced Natural Crack Start during Fatigue Testing

    Science.gov (United States)

    2016-05-01

    Kaye and Xiaobo Yu Aerospace Division Defence Science and Technology Group DST-Group-TR-3252 ABSTRACT This report details the development of a...as more uniformly distributing the fatigue cracking over the region of constant stress. Stress intensity factors have also been computed for...reduces the number of coupons that need to be tested in order to attain desired statistical confidence levels, leading to significant time savings and

  2. Stress-testing the Standard Model at the LHC

    CERN Document Server

    2016-01-01

    With the high-energy run of the LHC now underway, and clear manifestations of beyond-Standard-Model physics not yet seen in data from the previous run, the search for new physics at the LHC may be a quest for small deviations with big consequences. If clear signals are present, precise predictions and measurements will again be crucial for extracting the maximum information from the data, as in the case of the Higgs boson. Precision will therefore remain a key theme for particle physics research in the coming years. The conference will provide a forum for experimentalists and theorists to identify the challenges and refine the tools for high-precision tests of the Standard Model and searches for signals of new physics at Run II of the LHC. Topics to be discussed include: pinning down Standard Model corrections to key LHC processes; combining fixed-order QCD calculations with all-order resummations and parton showers; new developments in jet physics concerning jet substructure, associated jets and boosted je...

  3. Paradigm Change for Accelerated Stress Testing of Thin-Film Modules

    DEFF Research Database (Denmark)

    Hacke, Peter; Spataru, Sergiu; Johnston, Steve

    2017-01-01

    A fundamental change in the analysis for the accelerated stress testing of thin-film modules is proposed, whereby power changes due to metastability and other effects that may occur due to the thermal history are removed from the power measurement that we obtain as a function of the applied stres...... in standardized tests, the method is demonstrated and discussed for potential-induced degradation testing in view of the physical mechanisms that can lead to confounding power changes in the module....

  4. Patch test function for axisymmetric element of conventional and couple stress theory

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The enhanced patch test proposed by Chen W J(2006) can be used to assess the convergence of the problem with non-homogeneous differential equations.Based on this theory,we establish the patch test function for axisymmetric elements of conventional and couple stress theories,and reach an important conclusion that the patch test function for axisymmetric elements cannot contain non-zero constant shear.

  5. Patch test function for axisymmetric element of conventional and couple stress theory

    Institute of Scientific and Technical Information of China (English)

    CHEN WanJi; ZHAO Jie; WANG JinZhi; JI Bian

    2009-01-01

    The enhanced patch test proposed by Chen W J (2006) can be used to assess the convergence of the problem with non-homogeneous differential equations. Based on this theory, we establish the patch test function for axisyrnrnetric elements of conventional and couple stress theories, and reach an im-portant conclusion that the patch test function for axisymrnetric elements cannot contain non-zero constant shear.

  6. A test case of the deformation rate analysis (DRA) stress measurement method

    Energy Technology Data Exchange (ETDEWEB)

    Dight, P.; Hsieh, A. [Australian Centre for Geomechanics, Univ. of WA, Crawley (Australia); Johansson, E. [Saanio and Riekkola Oy, Helsinki (Finland); Hudson, J.A. [Rock Engineering Consultants (United Kingdom); Kemppainen, K.

    2012-01-15

    As part of Posiva's site and ONKALO investigations, the in situ rock stress has been measured by a variety of techniques, including hydraulic fracturing, overcoring, and convergence measurements. All these techniques involve direct measurements in a drillhole or at the rock surface. An alternative method is to test drillhole core in a way that enables estimation of the magnitudes and orientations of the in situ rock stress. The Kaiser Effect (KE) and Deformation Rate Analysis (DRA) are two ways to do this. In the work reported here, a 'blind' DRA test was conducted on core obtained from the POSE (Posiva's Olkiluoto Spalling Experiment) niche in the ONKALO. The term 'blind' means that the two first authors of this report, who conducted the tests at the Australian Centre for Geomechanics, did not know the depths below surface at which the cores had been obtained. The results of this DRA Test Case are presented, together with an explanation of the DRA procedure. Also, additional information that would help in such DRA testing and associated analysis is explained. One of the problems in comparing the DRA results with the known Olkiluoto stress field is that the latter is highly variable across the site, as experienced by the previous in situ stress measurements and as predicted by numerical analysis. The variability is mainly caused by the presence of the large brittle deformation zones which perturb the local stress state. However, this variability reduces with depth and the stress field becomes more stable at the {approx} 350 m at which the drillhole cores were obtained. Another compounding difficulty is that the stress quantity, being a second order tensor, requires six independent components for its specification. In other words, comparison of the DRA results and the known stress field requires comparison of six different quantities. In terms of the major principal stress orientation, the DRA results predict an orientation completely

  7. Synthetic sea water - An improved stress corrosion test medium for aluminum alloys

    Science.gov (United States)

    Humphries, T. S.; Nelson, E. E.

    1973-01-01

    A major problem in evaluating the stress corrosion cracking resistance of aluminum alloys by alternate immersion in 3.5 percent salt (NaCl) water is excessive pitting corrosion. Several methods were examined to eliminate this problem and to find an improved accelerated test medium. These included the addition of chromate inhibitors, surface treatment of specimens, and immersion in synthetic sea water. The results indicate that alternate immersion in synthetic sea water is a very promising stress corrosion test medium. Neither chromate inhibitors nor surface treatment (anodize and alodine) of the aluminum specimens improved the performance of alternate immersion in 3.5 percent salt water sufficiently to be classified as an effective stress corrosion test method.

  8. Cardiac Malpositions

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Shi Joon; Im, Chung Gie; Yeon, Kyung Mo; Hasn, Man Chung [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    1979-06-15

    Cardiac Malposition refers to any position of the heart other than a left-sided heart in a situs solitus individual. Associated cardiac malformations are so complex that even angiocardiographic and autopsy studies may not afford an accurate information. Although the terms and classifications used to describe the internal cardiac anatomy and their arterial connections in cardiac malpositions differ and tend to be confusing, common agreement exists on the need for a segmental approach to diagnosis. Authors present 18 cases of cardiac malpositions in which cardiac catheterization and angiocardiography were done at the Department of Radiology, Seoul National University Hospital between 1971 and 1979. Authors analyzed the clinical, radiographic, operative and autopsy findings with the emphasis on the angiocardiographic findings. The results are as follows: 1. Among 18 cases with cardiac malpositions, 6 cases had dextrocardia with situs inversus, 9 cases had dextrocardia with situs solitus and 3 cases had levocardia with situs inversus. 2. There was no genuine exception to visceroatrial concordance rule. 3. Associated cardiac malpositions were variable and complex with a tendency of high association of transposition and double outlet varieties with dextrocardia in situs solitus and levocardia in situs inversus. Only one in 6 cases of dextrocardia with situs inversus had pure transposition. 4. In two cases associated pulmonary atresia was found at surgery which was not predicted by angiocardiography. 5. Because many of the associated complex lesions can be corrected surgically provided the diagnosis is accurate, the selective biplane angiocardiography with or without cineradiography is essential.

  9. The Role of Genetic Testing in the Identification of Young Athletes with Inherited Primitive Cardiac Disorders at Risk of Exercise Sudden Death

    Science.gov (United States)

    Tiziano, Francesco Danilo; Palmieri, Vincenzo; Genuardi, Maurizio; Zeppilli, Paolo

    2016-01-01

    Although relatively rare, inherited primitive cardiac disorders (IPCDs) in athletes have a deep social impact since they often present as sudden cardiac death (SCD) of young and otherwise healthy persons. The diagnosis of these conditions is likely underestimated due to the lack of shared clinical criteria and to the existence of several borderline clinical pictures. We will focus on the clinical and molecular diagnosis of the most common IPCDs, namely hypertrophic cardiomyopathies, long QT syndrome, arrhythmogenic right ventricular cardiomyopathy, and left ventricular non-compaction. Collectively, these conditions account for the majority of SCD episodes and/or cardiologic clinical problems in athletes. In addition to the clinical and instrumental tools for the diagnosis of IPCD, the viral technological advances in genetic testing have facilitated the molecular confirmation of these conditions. However, genetic testing presents several issues: the limited sensitivity (globally, around 50%), the low prognostic predictive value, the probability to find pathogenic variants in different genes in the same patient, and the risk of non-interpretable results. In this review, we will analyze the pros and cons of the different clinical approaches for the presymptomatic identification, the diagnosis and management of IPCD athletes, and we will discuss the indications to the genetic testing for patients and their relatives, particularly focusing on the most complex scenarios, such as presymptomatic tests, uncertain results, and unexpected findings. PMID:27617263

  10. Stress and psychological health: testing the mediating role of cognitive appraisal

    OpenAIRE

    Gomes, A. Rui; Faria, Susana; Lopes, Heitor

    2016-01-01

    This study tested the mediating role of primary (e.g., threat and challenge perceptions) and secondary (e.g., coping potential and control perception) cognitive appraisal in the relationship between occupational stress and psychological health. This mediation was tested using a cross-sectional study based on self-reported measures. The total sample consisted of 2,302 nurses, 1,895 females (82.3%) and 407 males (17.7%), who completed an evaluation protocol with measures of occupational stress,...

  11. Developing a Symptom Validity Test for posttraumatic stress disorder: application of the binomial distribution.

    Science.gov (United States)

    Morel, Kenneth R; Shepherd, Bryan E

    2008-12-01

    The past decade has witnessed a significant increase in research on the detection of malingered Posttraumatic Stress Disorder (PTSD) in civil litigation, other disability pension contexts, and in forensic cases. This article reviews the basic principles and statistical procedures that can be used to design and develop a Symptom Validity Test (SVT) for PTSD. We demonstrate how the practical application of the binomial distribution can detect response bias in specific psychiatric disorders such as PTSD and can provide empirically grounded probabilistic evidence of malingering. We cite the Morel Emotional Numbing Test for Posttraumatic Stress Disorder (MENT) as an example.

  12. Diagnosis of coronary artery disease with dobutamine-stress MRI

    NARCIS (Netherlands)

    Kuijpers, D

    2005-01-01

    Dobutamine-stress cardiovascular magnetic resonance (CMR) is a new diagnostic tool for the non-invasive detection of coronary artery disease. Technological advances in CMR have evolved this technique to an adequate alternative to the standard cardiac stress tests. Its high reproducibility and excell

  13. Fatigue Failure Results for Multi-Axial versus Uniaxial Stress Screen Vibration Testing

    Directory of Open Access Journals (Sweden)

    Wayne E. Whiteman

    2002-01-01

    Full Text Available To date, the failure potential and prediction between simultaneous multi-axial versus sequentially applied uniaxial vibration stress screen testing has been the subject of great debate. In most applications, current vibration tests are done by sequentially applying uniaxial excitation to the test specimen along three orthogonal axes. The most common standards for testing military equipment are published in MIL-STD-810F and NAVMAT P-9492. Previous research had shown that uniaxial testing may be unrealistic and inadequate. This current research effort is a continuing effort to systematically investigate the differences between fatigue damage mechanisms and the effects of uniaxial versus tri-axial testing. This includes assessing the ability of the tri-axial method in predicting the formation of damage mechanisms, specifically looking at the effects of stress or fatigue failure. Multi-axial testing achieves the synergistic effect of exciting all modes simultaneously and induces a more realistic vibration stress loading condition. As such, it better approximates real-world operating conditions. This paper provides the latest results on the differences between multi-axial and uniaxial testing of a simple notched cantilever beam.

  14. 3-D distribution of tensile stress in rock specimens for the Brazilian test

    Institute of Scientific and Technical Information of China (English)

    Yong Yu; Chunyan Meng

    2005-01-01

    It is claimed that the formula used for calculating the tensile strength of a disk-shaped rock specimen in the Brazilian test is not accurate, because the formula is based on the 2-dimensional elastic theory and only suitable for very long or very short cylinders. The Matlab software was used to obtain the 2-dimensional distribution of stress in the rock specimen for Brazilian test. Then the 2-dimensional stress distribution in Brazilian disk was analyzed by the Marc FEM software. It can be found that the results obtained by the two software packages can verify each other. Finally, the 3-dimensional elastic stress in the specimen was calculated. The results demonstrate that the distribution of stress on the cross section of the specimen is similar to that in 2-dimension. However, the value of the stress on the cross section varies along the thickness of the specimen and the stress is bigger when getting closer to the end of the specimen. For the specimen with a height-to-diameter ratio of 1 and a Poisson's ratio of 0.25, the tensile strength calculated with the classical 2-D formula is 23.3% smaller than the real strength. Therefore, the classical 2-D formula is too conservative.

  15. Modeling of Stress- Strain Curves of Drained Triaxial Test on Sand

    Directory of Open Access Journals (Sweden)

    Awad A. Karni

    2006-01-01

    Full Text Available This paper presents a hyperbolic mathematical model to predict the complete stress-strain curve of drained triaxial tests on uniform dense sand. The model was formed in one equation with many parameters. The main parameters that are needed to run the model are the confining pressure, angle of friction and the relative density. The other parameters, initial and final slopes of the stress strain curve, the reference stress and the curve-shape parameter are determined as functions of the confining pressure, angle of friction and the relative density using best fitting curve technique from the experimental tests results. Drained triaxial tests were run on clean white uniform sand to utilize and verify this model. These tests were carried out at four levels of confining pressure of 100, 200, 300 and 400 kPa. This model was used to predict the stress-strain curves for drained triaxial tests on quartz sand at different relative density using the data of Kouner[1]. The model predictions were compared with the experimental results and showed good agreements of the predicted results with the experimental results at all levels of applied confining pressures and relative densities.

  16. Effect of Acupressure on Non-stress Test (NST Results: A Randomized-Controlled Trial Study

    Directory of Open Access Journals (Sweden)

    Masoume Pirhadi

    2015-10-01

    Full Text Available BackgroundPregnancy and delivery are among the most stressful events in women’s life . Breech presentation is defined as a fetus in a longitudinal lie with the buttocks or feet closest to the cervix. This occurs in 3-4% of all deliveries.The risk for perinatal mortality was 1 in 300 for planned breech deliveries.Some conventional non-surgical therapies for breech presentation are available. acupoint (BL67 stimulations are commonly used for the correction of breech presentation. The present study aimed to evaluate the effect of acupressure on fetal wellbeing test results.MethodThis study is a clinical trialthat was conducted in one group and the two-steps.Participantswere pregnant women (primigravida who were 35 to 18 years that refer to Shahid Beheshti hospital in Isfahan in 2013 to receive routine prenatal care.The 32 pregnant women (32-36 weeks were randomly selected.They were stimulated immediately after the first Non stress test and before the second test.The researchers’ evaluated and analyzed variables using SPSS software version 20.FindingsMean (SD age of the subjects was 24/7±2/8 and 93/8% of them was housekeeper. The frequency of reactive Non Stress Test (NST was same before and after stimulation. The mean time of the tests’ result was decreased after stimulation significantly ( p-value=0.048. ConclusionsAlthough fetal non-stress test result wasn’t influenced by acupressure but this intervention led to shorter testing time to achieve results. In other words, after the intervention, the time it takes to reach a reactive fetal non-stress test is about 2/7 minutes less than the time without intervention.

  17. Cardiac oxidative stress determination and myocardial morphology after a single ecstasy (MDMA) administration in a rat model.

    Science.gov (United States)

    Cerretani, Daniela; Riezzo, Irene; Fiaschi, Anna Ida; Centini, Fabio; Giorgi, Giorgio; D'Errico, Stefano; Fiore, Carmela; Karch, Steven B; Neri, Margherita; Pomara, Cristoforo; Turillazzi, Emanuela; Fineschi, Vittorio

    2008-11-01

    Experimental and clinical data indicate that 3,4-methylenedioxy-N-methylamphetamine (MDMA) abuse can produce significant cardiovascular toxicity. A mechanism may be a direct toxic effect of redox active metabolites of MDMA. To evaluate the effect of a single MDMA dose on cellular antioxidant defence system and to investigate the morphology in male albino rats, total glutathione (GSH), oxidised glutathione (GSSG), ascorbic acid (AA), glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD) and malondialdehyde (MDAL) were studied. The effects were evaluated at 3, 6, 16 and 24 h after MDMA administration. Antioxidant enzymes activity was significantly reduced: GPx (-24%) and SOD (-50%) after 3 h and GR (-19%) after 6 h from treatment. AA levels decrease (-37%) after 3 h and (-30%) after 6 h; MDAL level increased (+119%) after 3 h; GSH levels decreased after 3 (31.3%) and 6 h (37.9%) from MDMA treatment. GSSG content was not affected by ecstasy administration. Myocardial contraction band necrosis (CBN) was already visible in rats killed at 6 h. After 16 h, macrophagic monocytes around the necrotic myocardial cells were observed, and within 24 h, this infiltrate became more widespread with an early removal of the necrotic material. Calcium deposits were observed within ventricular cardiomyocytes with intact nuclei and sarcomeres. Single administration of MDMA can significantly alter the cellular antioxidant defence system and produce oxidative stress which may result in lipid peroxidation and disruption of Ca(2 +) homeostasis. The depression in Ca(2+) regulatory mechanism by reactive oxygen species ultimately results in intracellular Ca(2 +) overload, CBN and cell death.

  18. Thermal stress analysis of the NASA Dryden hypersonic wing test structure

    Science.gov (United States)

    Morris, Glenn

    1990-01-01

    Present interest in hypersonic vehicles has resulted in a renewed interest in thermal stress analysis of airframe structures. While there are numerous texts and papers on thermal stress analysis, practical examples and experience on light gage aircraft structures are fairly limited. A research program has been undertaken at General Dynamics to demonstrate the present state of the art, verify methods of analysis, gain experience in their use, and develop engineering judgement in thermal stress analysis. The approach for this project has been to conduct a series of analyses of this sample problem and compare analysis results with test data. This comparison will give an idea of how to use our present methods of thermal stress analysis, and how accurate we can expect them to be.

  19. Simulation of Mechanical Stress on Stainless Steel for Pb-Bi Corrosion Test by Using ABAQUS

    Science.gov (United States)

    Irwanto, D.; Mustari, A. P. A.; Budiman, B. A.

    2017-03-01

    Pb-Bi eutectic with its advantageous is proposed to be utilized as a coolant in the GEN IV type of rSeactor. However, high temperature corrosion when contact with stainless steels is one of the issues of Pb-Bi eutectic utilization. It is known that in the environment of high temperature Pb-Bi, mechanical strength of stainless steel may decrease. Thus, simulation of mechanical stress working on stainless steel during in-situ bending test by using ABAQUS was conducted. Several bending degrees were simulated at high temperature to obtain the mechanical stress information. Temperature condition was strongly affect the stress vs. displacement profile. The reported mechanical strength reduction percentage was used to draw predicted mechanical stress under high temperature Pb-Bi environment.

  20. Study and Test of a New Bundle-Structure Riser Stress Monitoring Sensor Based on FBG.

    Science.gov (United States)

    Xu, Jian; Yang, Dexing; Qin, Chuan; Jiang, Yajun; Sheng, Leixiang; Jia, Xiangyun; Bai, Yang; Shen, Xiaohong; Wang, Haiyan; Deng, Xin; Xu, Liangbin; Jiang, Shiquan

    2015-11-24

    To meet the requirements of riser safety monitoring in offshore oil fields, a new Fiber Bragg Grating (FBG)-based bundle-structure riser stress monitoring sensor has been developed. In cooperation with many departments, a 49-day marine test in water depths of 1365 m and 1252 m was completed on the "HYSY-981" ocean oil drilling platform. No welding and pasting were used when the sensor was installed on risers. Therefore, the installation is convenient, reliable and harmless to risers. The continuous, reasonable, time-consistent data obtained indicates that the sensor worked normally under water. In all detailed working conditions, the test results show that the sensor can do well in reflecting stresses and bending moments both in and in magnitude. The measured maximum stress is 132.7 MPa, which is below the allowable stress. In drilling and testing conditions, the average riser stress was 86.6 MPa, which is within the range of the China National Offshore Oil Corporation (CNOOC) mechanical simulation results.

  1. Study and Test of a New Bundle-Structure Riser Stress Monitoring Sensor Based on FBG

    Directory of Open Access Journals (Sweden)

    Jian Xu

    2015-11-01

    Full Text Available To meet the requirements of riser safety monitoring in offshore oil fields, a new Fiber Bragg Grating (FBG-based bundle-structure riser stress monitoring sensor has been developed. In cooperation with many departments, a 49-day marine test in water depths of 1365 m and 1252 m was completed on the “HYSY-981” ocean oil drilling platform. No welding and pasting were used when the sensor was installed on risers. Therefore, the installation is convenient, reliable and harmless to risers. The continuous, reasonable, time-consistent data obtained indicates that the sensor worked normally under water. In all detailed working conditions, the test results show that the sensor can do well in reflecting stresses and bending moments both in and in magnitude. The measured maximum stress is 132.7 MPa, which is below the allowable stress. In drilling and testing conditions, the average riser stress was 86.6 MPa, which is within the range of the China National Offshore Oil Corporation (CNOOC mechanical simulation results.

  2. Mechanical characterization of human aortas from pressurization testing and a paradigm shift for circumferential residual stress.

    Science.gov (United States)

    Labrosse, Michel R; Gerson, Eleanor R; Veinot, John P; Beller, Carsten J

    2013-01-01

    Material properties needed for accurate stress analysis of the human aorta are still incompletely known, especially as many reports have ignored the presence of residual stresses in the aortic wall. To contribute new material regarding these issues, we carried out measurements and pressurization testing on ascending, thoracic and abdominal aortic samples from 24 human subjects aged 38-77 years, and evaluated the opening angle describing the circumferential residual stress level present in the aorta. We determined material constants for the aorta by gender, anatomic location and age group, according to a simple phenomenological constitutive model. The unpressurized aortic radius positively correlated with age, and the circumferential and longitudinal stretch ratios under systemic pressure negatively correlated with age, confirming the known enlargement and stiffening of the aorta with aging. The opening angle was measured to range from a minimum of 89° to above 360° for extreme cases. For given aortic dimensions and material properties, analysis of the in vivo circumferential and longitudinal mural stress distributions indicated a profound influence of the opening angle. For instance, in the thoracic aorta of males aged 38-66, opening angles in the range of 0° to 80° (resp. 60°) may equalize the gradient of in vivo circumferential (resp. longitudinal) stress between the inner and outer layers of the aorta, as commonly expected; however, opening angles above 160° (resp. 120°) may cause the gradient of circumferential (resp. longitudinal) stress to reverse and increase compared to the case without residual stress, putting the maximum stresses toward the adventitia instead of the intima. Even though the analysis of the aortic wall excluded possible longitudinal residual stresses as well as material inhomogeneities, such as constitutive differences between the intimal, medial and adventitial layers, the experimental data reported herein are important to aortic

  3. Daily life stress and the cortisol awakening response: testing the anticipation hypothesis.

    Directory of Open Access Journals (Sweden)

    Daniel J Powell

    Full Text Available The cortisol awakening response (CAR is a distinct facet of the circadian cortisol rhythm associated with various health conditions and risk factors. It has repeatedly been suggested that the CAR could be a result of the anticipated demands of the upcoming day (stress anticipation and could support coping with daily life stress. In a sample of 23 healthy participants CARs were assessed on two consecutive days by measures of salivary cortisol upon awakening (S1 and 30 and 45 minutes later, which were aggregated to the area under the curve increase (AUCI. Stress anticipation was assessed immediately after awakening. On the same days, daily life stress and distress were assessed six times per day based on a quasi-randomized design using handheld computers. Associations were tested by day using regression analysis and standard multilevel/mixed effects models for longitudinal data. The CAR AUCI moderated the effect of daily life stress on distress; higher CAR increases were associated with attenuated distress responses to daily life stress on both days (day 1: p = .039; day 2: p = .004 adjusted for age, gender, sleep quality, time of awakening and oral contraceptive use. Lagged-effects and redundancy models showed that this effect was not due to prior-day CAR increases but specific for same day CARs. On day 2, associations between daily life stress and distress were stronger when individuals showed a higher S1 cortisol level, but this effect was similar for S1 on day 1, and the day 2 effect of S1 became non-significant when S1 on day 1 was controlled. No associations were found between stress anticipation and CARs. Findings indicate that the CAR increase is associated with successful coping with same-day daily life stress.

  4. Objective effect manifestation of pectus excavatum on load-stressed pulmonary function testing: a case report

    Directory of Open Access Journals (Sweden)

    Chan Jason

    2011-12-01

    Full Text Available Abstract Introduction Pectus excavatum is the most common congenital deformity of the anterior chest wall that, under certain conditions, may pose functional problems due to cardiopulmonary compromise and exercise intolerance. Case presentation We present the case of an otherwise physically-adept 21-year-old Chinese sportsman with idiopathic pectus excavatum, whose symptoms manifested only on bearing a loaded body vest and backpack during physical exercise. Corroborative objective evidence was obtained via load-stressed pulmonary function testing, which demonstrated restrictive lung function. Conclusion This report highlights the possible detrimental synergism of thoracic load stress and pectus excavatum on cardiopulmonary function. Thoracic load-stressed pulmonary function testing provides objective evidence in support of such a synergistic relationship.

  5. Test with different stress measurement methods in two orthogonal bore holes in Aespoe HRL

    Energy Technology Data Exchange (ETDEWEB)

    Janson, Thomas; Stigsson, Martin [Golder Associates AB, Stockholm (Sweden)

    2002-12-01

    Within the scope of work, to provide the necessary rock mechanics support for the site investigations, SKB has studied some available pieces of equipment for in situ stress measurements in deep boreholes. A project with the objective to compare three different pieces of equipment for in situ stress measurements under similar conditions has been carried out. The main objective for the project is to compare the three different pieces of equipment for in situ stress measurements and find a strategy for SKB's Site Investigations to determine the state of stress in the rock mass. Two units of equipment use the overcoring method while the third uses the hydraulic fracturing method. The overcoring was performed by AECL, using Deep Door stopper Gauge System (DDGS), and SwedPower, using their triaxial strain measuring instrument (Borre Probe). MeSy Geo Systeme GmbH performed the hydraulic fracturing. The DDGS system is a new method to SKB while the experience of the SwedPower overcoring and the hydraulic fracturing methods are long. The tests were performed in the same orthogonal boreholes at Aespoe Hard Rock Laboratory (HRL), Oskarshamn, Sweden. The measured results have been verified against known conditions at the Aespoe HRL. The results from the three in situ stress measurement methods rose more questions than answers. Which illustrate the complexity to determine the in situ stresses in a rock mass. To understand the difference in results and answer the questions, it was necessary to do deeper investigations such as laboratory tests and theoretical calculations such as geological structure model, analysis of the influence of a nearby fracture, P-wave measurements, uniaxial tests on small cores from the HQ-3 core, theoretical and numerical analyses of the hole bottom (theoretical strains, stress concentrations and microcracking), auditing of DDGS measurements results and assumptions in the DDGS analyse and microscopy investigations on the cores. The following

  6. Epigenetic regulation in cardiac fibrosis

    Institute of Scientific and Technical Information of China (English)

    Li-Ming; Yu; Yong; Xu

    2015-01-01

    Cardiac fibrosis represents an adoptive response in the heart exposed to various stress cues. While resolution of the fibrogenic response heralds normalization of heart function, persistent fibrogenesis is usually associated with progressive loss of heart function and eventually heart failure. Cardiac fibrosis is regulated by a myriad of factors that converge on the transcription of genes encoding extracellular matrix proteins, a process the epigenetic machinery plays a pivotal role. In this minireview, we summarize recent advances regarding the epigenetic regulation of cardiac fibrosis focusing on the role of histone and DNA modifications and non-coding RNAs.

  7. Relationship between Academic Stress and Suicidal Ideation: Testing for Depression as a Mediator Using Multiple Regression

    Science.gov (United States)

    Ang, Rebecca P.; Huan, Vivien S.

    2006-01-01

    Relations among academic stress, depression, and suicidal ideation were examined in 1,108 Asian adolescents 12-18 years old from a secondary school in Singapore. Using Baron and Kenny's [J Pers Soc Psychol 51:1173-1192, 1986] framework, this study tested the prediction that adolescent depression mediated the relationship between academic stress…

  8. Optimal Constant-Stress Accelerated Degradation Test Plans Using Nonlinear Generalized Wiener Process

    Directory of Open Access Journals (Sweden)

    Zhen Chen

    2016-01-01

    Full Text Available Accelerated degradation test (ADT has been widely used to assess highly reliable products’ lifetime. To conduct an ADT, an appropriate degradation model and test plan should be determined in advance. Although many historical studies have proposed quite a few models, there is still room for improvement. Hence we propose a Nonlinear Generalized Wiener Process (NGWP model with consideration of the effects of stress level, product-to-product variability, and measurement errors for a higher estimation accuracy and a wider range of use. Then under the constraints of sample size, test duration, and test cost, the plans of constant-stress ADT (CSADT with multiple stress levels based on the NGWP are designed by minimizing the asymptotic variance of the reliability estimation of the products under normal operation conditions. An optimization algorithm is developed to determine the optimal stress levels, the number of units allocated to each level, inspection frequency, and measurement times simultaneously. In addition, a comparison based on degradation data of LEDs is made to show better goodness-of-fit of the NGWP than that of other models. Finally, optimal two-level and three-level CSADT plans under various constraints and a detailed sensitivity analysis are demonstrated through examples in this paper.

  9. 78 FR 67218 - Agency Information Collection Activities: Company-Run Annual Stress Test Reporting Template and...

    Science.gov (United States)

    2013-11-08

    ..., Attention: 1557-NEW, 400 7th St. SW., Washington, DC 20219. In addition, comments may be sent by fax to (202... stress tests to determine whether additional analytical techniques and exercises could be appropriate to... has modified the FR Y-14A, and, to the extent practical, the OCC will keep its reporting...

  10. Emotional-volitional components of operator reliability. [sensorimotor function testing under stress

    Science.gov (United States)

    Mileryan, Y. A.

    1975-01-01

    Sensorimotor function testing in a tracking task under stressfull working conditions established a psychological characterization for a successful aviation pilot: Motivation significantly increased the reliability and effectiveness of their work. Their acitivities were aimed at suppressing weariness and the feeling of fear caused by the stress factors; they showed patience, endurance, persistence, and a capacity for lengthy volitional efforts.

  11. 78 FR 9633 - Policy Statement on the Scenario Design Framework for Stress Testing

    Science.gov (United States)

    2013-02-11

    ..., Adviser, (202) 452-2339, Office of Financial Stability Policy and Research. ADDRESSES: Interested parties... with the supervisory and company-run stress tests conducted under the Board's regulations issued... Palmer, Senior Supervisory Financial Analyst, (202) 452-2904, Division of Banking Supervision...

  12. Ministries Design Exchange Rate Stress Test for Labor-Intensive Industries

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ China's Ministry of Commerce(MOFCOM)and the Ministry of Industry and Information Technology(MIIT)have designed a stress-test for China's labor-intensive industries,aiming to determine the effect of Yuan appreciation on the textile garment,shoe-making and toy industry.

  13. Simulated Service and Stress Corrosion Cracking Testing for Friction Stir Welded Spun Formed Domes

    Science.gov (United States)

    Stewart, Thomas J.; Torres, Pablo D.; Caratus, Andrei A.; Curreri, Peter A.

    2010-01-01

    Simulated service testing (SST) development was required to help qualify a new 2195 aluminum lithium (Al-Li) alloy spin forming dome fabrication process for the National Aeronautics and Space Administration (NASA) Exploration Development Technology Program. The application for the technology is to produce high strength low weight tank components for NASA s next generation launch vehicles. Since plate material is not currently manufactured large enough to fabricate these domes, two plates are joined by means of friction stir welding. The plates are then pre-contour machined to near final thicknesses allowing for a thicker weld land and anticipating the level of stretch induced by the spin forming process. The welded plates are then placed in a spin forming tool and hot stretched using a trace method producing incremental contours. Finally the dome receives a room temperature contour stretch to final dimensions, heat treatment, quenching, and artificial aging to emulate a T-8 condition of temper. Stress corrosion cracking (SCC) tests were also performed by alternate immersion in a sodium chloride (NaCl) solution using the typical double beam assembly and with 4-point loaded specimens and use of bent-beam stress-corrosion test specimens under alternate immersion conditions. In addition, experiments were conducted to determine the threshold stress intensity factor for SCC (K(sub ISCC)) which to our knowledge has not been determined previously for Al-Li 2195 alloy. The successful simulated service and stress corrosion testing helped to provide confidence to continue to Ares 1 scale dome fabrication

  14. Accelerated Stress Testing of Thin-Film Modules with SnO2:F Transparent Conductors

    Energy Technology Data Exchange (ETDEWEB)

    Osterwald, C. R.; McMahon, T. J.; del Cueto, J. A.; Adelstein, J.; Puett, J.

    2003-05-01

    This paper reviews a testing program conducted at NREL for the past two years that applied voltage, water vapor, and light stresses to thin-film photovoltaic (PV) modules with SnO2:F transparent conducting oxides (TCOs) deposited on soda-lime glass superstrates. Electrochemical corrosion at the glass-TCO interface was observed to result in delamination of the thin-film layers. Experimental testing was directed toward accelerating the corrosion and understanding the nature of the resulting damage.

  15. Transient myocardial ischemia after a first acute myocardial infarction and its relation to clinical characteristics, predischarge exercise testing and cardiac events at one-year follow-up

    DEFF Research Database (Denmark)

    Mickley, H; Pless, P; Nielsen, J R

    1993-01-01

    recording 11 +/- 5 days after AMI 23 patients (19%) had 123 ischemic episodes (group 1), whereas 100 patients demonstrated no ischemia (group 2). Exercise-induced ST-segment depression was more prevalent in group 1 (83%) than in group 2 (47%) (p ... as judged from a shorter exercise duration before significant ST-segment depression (5.5 +/- 2.4 vs 7.7 +/- 4.1 minutes; p depression on exercise testing (4.1 +/- 2.6 vs 2.6 +/- 1.6 mm; p exercise test results revealed an impaired hemodynamic......The relation between early out-of-hospital ambulatory ST-segment monitoring, clinical characteristics, predischarge maximal exercise testing and cardiac events was determined in 123 consecutive men (age 55 +/- 8 years) with a first acute myocardial infarction (AMI). During 36 hours of ambulatory...

  16. Standard Test Method for Testing Polymeric Seal Materials for Geothermal and/or High Temperature Service Under Sealing Stress

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1985-01-01

    1.1 This test method covers the initial evaluation of (screening) polymeric materials for seals under static sealing stress and at elevated temperatures. 1.2 This test method applies to geothermal service only if used in conjunction with Test Method E 1068. 1.3 The test fluid is distilled water. 1.4 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  17. Phosphodiesterase-3 inhibitor (cilostazol) attenuates oxidative stress-induced mitochondrial dysfunction in the heart

    Institute of Scientific and Technical Information of China (English)

    Siriporn C.Chattipakorn; Savitree Thummasorn; Jantira Sanit; Nipon Chattipakorn

    2014-01-01

    Background Cilostazol is a type 3 phosphodiesterase inhibitor which has been previously demonstrated to prevent the occurrence of tachyarrhythmia and improve defibrillation efficacy. However, the mechanism for this beneficial effect is still unclear. Since cardiac mito-chondria have been shown to play a crucial role in fatal cardiac arrhythmias and that oxidative stress is one of the main contributors to arr-hythmia generation, we tested the effects of cilostazol on cardiac mitochondria under severe oxidative stress. Methods Mitochondria were isolated from rat hearts and treated with H2O2 to induce oxidative stress. Cilostazol, at various concentrations, was used to study its protective effects. Pharmacological interventions, including a mitochondrial permeability transition pore (mPTP) blocker, cyclosporine A (CsA), and an inner membrane anion channel (IMAC) blocker, 4’-chlorodiazepam (CDP), were used to investigate the mechanistic role of cilostazol on cardiac mitochondria. Cardiac mitochondrial reactive oxygen species (ROS) production, mitochondrial membrane potential change and mi-tochondrial swelling were determined as indicators of cardiac mitochondrial function. Results Cilostazol preserved cardiac mitochondrial function when exposed to oxidative stress by preventing mitochondrial depolarization, mitochondrial swelling, and decreasing ROS produc-tion. Conclusions Our findings suggest that cardioprotective effects of cilostazol reported previously could be due to its prevention of car-diac mitochondrial dysfunction caused by severe oxidative stress.

  18. Stress-deformed state of cylindrical specimens during indirect tensile strength testing

    Institute of Scientific and Technical Information of China (English)

    Levan Japaridze

    2015-01-01

    In this study, the interaction between cylindrical specimen made of homogeneous, isotropic, and linearly elastic material and loading jaws of any curvature is considered in the Brazilian test. It is assumed that the specimen is diametrically compressed by elliptic normal contact stresses. The frictional contact stresses between the specimen and platens are neglected. The analytical solution starts from the contact problem of the loading jaws of any curvature and cylindrical specimen. The contact width, corresponding loading angle (2q0), and elliptical stresses obtained through solution of the contact problems are used as boundary conditions for a cylindrical specimen. The problem of the theory of elasticity for a cylinder is solved using Muskhelishvili’s method. In this method, the displacements and stresses are represented in terms of two analytical functions of a complex variable. In the main approaches, the nonlinear inter-action between the loading bearing blocks and the specimen as well as the curvature of their surfaces and the elastic parameters of their materials are taken into account. Numerical examples are solved using MATLAB to demonstrate the influence of deformability, curvature of the specimen and platens on the distribution of the normal contact stresses as well as on the tensile and compressive stresses acting across the loaded diameter. Derived equations also allow calculating the modulus of elasticity, total deformation modulus and creep parameters of the specimen material based on the experimental data of radial contraction of the specimen.

  19. Stress-deformed state of cylindrical specimens during indirect tensile strength testing

    Directory of Open Access Journals (Sweden)

    Levan Japaridze

    2015-10-01

    Full Text Available In this study, the interaction between cylindrical specimen made of homogeneous, isotropic, and linearly elastic material and loading jaws of any curvature is considered in the Brazilian test. It is assumed that the specimen is diametrically compressed by elliptic normal contact stresses. The frictional contact stresses between the specimen and platens are neglected. The analytical solution starts from the contact problem of the loading jaws of any curvature and cylindrical specimen. The contact width, corresponding loading angle (2θ0, and elliptical stresses obtained through solution of the contact problems are used as boundary conditions for a cylindrical specimen. The problem of the theory of elasticity for a cylinder is solved using Muskhelishvili's method. In this method, the displacements and stresses are represented in terms of two analytical functions of a complex variable. In the main approaches, the nonlinear interaction between the loading bearing blocks and the specimen as well as the curvature of their surfaces and the elastic parameters of their materials are taken into account. Numerical examples are solved using MATLAB to demonstrate the influence of deformability, curvature of the specimen and platens on the distribution of the normal contact stresses as well as on the tensile and compressive stresses acting across the loaded diameter. Derived equations also allow calculating the modulus of elasticity, total deformation modulus and creep parameters of the specimen material based on the experimental data of radial contraction of the specimen.

  20. Stress Free Temperature Testing and Calculations on Out-of-Autoclave Composites

    Science.gov (United States)

    Cox, Sarah B.; Tate, LeNetra C.; Danley, Susan E.; Sampson, Jeffrey W.; Taylor, Brian J.; Sutter, James K.; Miller, Sandi G.

    2013-01-01

    Future launch vehicles will require the incorporation of large composite parts that will make up primary and secondary components of the vehicle. NASA has explored the feasibility of manufacturing these large components using Out-of-Autoclave impregnated carbon fiber composite systems through many composites development projects. Most recently, the Composites for Exploration Project has been looking at the development of a 10 meter diameter fairing structure, similar in size to what will be required for a heavy launch vehicle. The development of new material systems requires the investigation of the material properties and the stress in the parts. Residual stress is an important factor to incorporate when modeling the stresses that a part is undergoing. Testing was performed to verify the stress free temperature with two-ply asymmetric panels. A comparison was done between three newly developed out of autoclave IM7/Bismaleimide (BMI) systems. This paper presents the testing results and the analysis performed to determine the stress free temperature of the materials

  1. Phenotypic flexibility as a measure of health: the optimal nutritional stress response test.

    Science.gov (United States)

    Stroeve, Johanna H M; van Wietmarschen, Herman; Kremer, Bas H A; van Ommen, Ben; Wopereis, Suzan

    2015-05-01

    Nutrition research is struggling to demonstrate beneficial health effects, since nutritional effects are often subtle and long term. Health has been redefined as the ability of our body to cope with daily-life challenges. Physiology acts as a well-orchestrated machinery to adapt to the continuously changing environment. We term this adaptive capacity "phenotypic flexibility." The phenotypic flexibility concept implies that health can be measured by the ability to adapt to conditions of temporary stress, such as physical exercise, infections or mental stress, in a healthy manner. This may offer a more sensitive way to assess changes in health status of healthy subjects. Here, we performed a systematic review of 61 studies applying different nutritional stress tests to quantify health and nutritional health effects, with the objective to define an optimal nutritional stress test that has the potential to be adopted as the golden standard in nutrition research. To acknowledge the multi-target role of nutrition, a relevant subset of 50 processes that govern optimal health, with high relevance to diet, was used to define phenotypic flexibility. Subsequently, we assessed the response of biomarkers related to this subset of processes to the different challenge tests. Based on the obtained insights, we propose a nutritional stress test composed of a high-fat, high-caloric drink, containing 60 g palm olein, 75 g glucose and 20 g dairy protein in a total volume of 400 ml. The use of such a standardized nutritional challenge test in intervention studies is expected to demonstrate subtle improvements of phenotypic flexibility, thereby enabling substantiation of nutritional health effects.

  2. The usefulness of myocardial SPECT for the preoperative cardiac risk evaluation in noncardiac surgery

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Seok Tae; Lee, Dong Soo; Kang, Won Jon; Chung, June Key; Lee, Myung Chul [College of Medicine, Seoul National Univ., Seoul (Korea, Republic of)

    1999-02-01

    We investigated whether myocardial SPECT had additional usefulness to clinical, functional or surgical indices for the preoperative evaluation of cardiac risks in noncardiac surgery. 118 patients ( M: F=66: 52, 62.7{+-}10.5 years) were studied retrospectively. Eighteen underwent vascular surgeries and 100 nonvascular surgeries. Rest Tl-201/ stress Tc-99m-MIBI SPECT was performed before operation and cardiac events (hard event: cardiac death and myocardial infarction; soft event: ischemic ECG change, congestive heat failure and unstable angina) were surveyed through perioperative periods (14.6{+-}5.6 days). Clinical risk indices, functional capacity, surgery procedures and SPECT findings were tested for their predictive values of perioperative cardiac events. Peri-operative cardiac events occurred in 25 patients (3 hard events and 22 soft events). Clinical risk indices, surgical procedure risks and SPECT findings but functional capacity were predictive of cardiac events. Reversible perfusion decrease was a better predictor than persistent decrease. Multivariate analysis sorted out surgical procedure risk (p=0.0018) and SPECT findings (p=0.0001) as significant risk factors. SPECT could re-stratify perioperative cardiac risks in patients ranked with surgical procedures. We conclude that myocardial SPECT provides additional predictive value to surgical type risks as well as clinical indexes or functional capacity for the prediction of preoperative cardiac events in noncardiac surgery.

  3. Cardiac cameras.

    Science.gov (United States)

    Travin, Mark I

    2011-05-01

    Cardiac imaging with radiotracers plays an important role in patient evaluation, and the development of suitable imaging instruments has been crucial. While initially performed with the rectilinear scanner that slowly transmitted, in a row-by-row fashion, cardiac count distributions onto various printing media, the Anger scintillation camera allowed electronic determination of tracer energies and of the distribution of radioactive counts in 2D space. Increased sophistication of cardiac cameras and development of powerful computers to analyze, display, and quantify data has been essential to making radionuclide cardiac imaging a key component of the cardiac work-up. Newer processing algorithms and solid state cameras, fundamentally different from the Anger camera, show promise to provide higher counting efficiency and resolution, leading to better image quality, more patient comfort and potentially lower radiation exposure. While the focus has been on myocardial perfusion imaging with single-photon emission computed tomography, increased use of positron emission tomography is broadening the field to include molecular imaging of the myocardium and of the coronary vasculature. Further advances may require integrating cardiac nuclear cameras with other imaging devices, ie, hybrid imaging cameras. The goal is to image the heart and its physiological processes as accurately as possible, to prevent and cure disease processes.

  4. Constant-Step Stress Accelerated Life Test of VFD under Logarithmic Normal Distribution Case

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In order to solve the life problem of vacuum fluorescent display (VFD) within shorter time, and reduce the life prediction cost, a constant-step stress accelerated life test was performed with its cathode temperature increased. Statistical analysis was done by applying logarithmic normal distribution for describing the life, and least square method (LSM) for estimating logarithmic normal parameters. Self-designed special software was used to predict the VFD life. It is verified by numerical results that the VFD life follows logarithmic normal distribution,and that the life-stress relationship satisfies linear Arrhenius equation completely. The accurate calculation of the key parameters enables the rapid estimation of VFD life.

  5. Constant-step stress accelerated life test of VFD under Weibull distribution case

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jian-ping; GENG Xin-min

    2005-01-01

    Constant-step stress accelerated life test of Vacuum Fluorescent Display (VFD) was conducted with increased cathode temperature. Statistical analysis was done by applying Weibull distribution for describing the life, and Least Square Method (LSM)for estimating Weibull parameters. Self-designed special software was used to predict the VFD life. Numerical results showed that the average life of VFD is over 30000 h, that the VFD life follows Weibull distribution, and that the life-stress relationship satisfies linear Arrhenius equation completely. Accurate calculation of the key parameter enabled rapid estimation of VFD life.

  6. Stress testing as a tool for simulating the effects of crisis in banks

    Directory of Open Access Journals (Sweden)

    Edward Wiszniowski

    2010-04-01

    Full Text Available Emergence of crisis in financial markets, especially banks, have forced a change in approach to riskmanagement. It has become necessary to develop new or refine existing models of early bankruptcythreat warning, as well as establishing the potential impact of bank failures. One of the tools, indicatingthat resistance to the phenomenon of crisis is “stress testing”. Its aim, at least in the case of banks,is concerned with estimating the level of economic resistance towards the occurring risk. Some ofthese risks are: the non-payment of loans due to deterioration in the economic situation of a country,fluctuations in interest rates, exchange rates and a fall in prices of securities which are traded on stockexchanges. This article discusses the nature of stress testing and shows the current legislation in Polandand presents the results of a stress testing conducted on the largest U.S. banks in May 2009. The rankand results of these studies show the importance of the role of stress testing as a complementary research of a diagnostic and prognostic nature.

  7. Closed testing procedure for multiplicity control. An application on oxidative stress parameters in Hashimoto's Thyroiditis

    Directory of Open Access Journals (Sweden)

    Angela Alibrandi

    2017-03-01

    Full Text Available Closed Testing procedures represent an effective solution to the need to make inferences on multiple aspects at the same time, controlling the Familywise Error Rate (FWER, that is the error rate of the hierarchical family. Closed Testing procedures have a high degree of adaptability to a wide range of experimental situations, both in parametric than in non-parametric ambit. The attention is focused on the  Bonferroni-Holm method, frequently used to counteract the problem of multiple comparisons. The present paper aims to show an original application of the Closed Testing procedures for multiplicity control in medical research, with reference to the oxidative stress; in particular the Min-P Bonferrroni-Holm method was applied to the p-value adjustment, related to three parameters (BAP, D-ROMS, AGEs of oxidative stress in Hashimoto’s thyroidytis.

  8. Planning failure-censored constant-stress par tially accelerated life test

    Institute of Scientific and Technical Information of China (English)

    Ali A Ismail; Abdulhakim A Al-Babtain

    2015-01-01

    This article deals with the case of the failure-censored constant-stress partial y accelerated life test (CSPALT) for highly reliable materials or products assuming the Pareto distribution of the second kind. The maximum likelihood (ML) method is used to estimate the parameters of the CSPALT model. The performance of ML estimators is investigated via their mean square error. Also, the average confidence interval length (IL) and the associated co-verage probability (CP) are obtained. Moreover, optimum CSPALT plans that determine the optimal proportion of the test units al-located to each stress are developed. Such optimum test plans minimize the generalized asymptotic variance (GAV) of the ML estimators of the model parameters. For il ustration, Monte Carlo simulation studies are given and a real life example is provided.

  9. Effects of Different Amounts of Ethyl Alcohol Intake on Cardiac Structure, Function and Oxidative Stress%不同乙醇摄入量对心脏结构、功能及氧化应激的影响

    Institute of Scientific and Technical Information of China (English)

    程燕; 孙尧; 魏剑芬; 马新颖; 梁芳倩; 李歧梅; 李海泽; 于晓龙

    2011-01-01

    Objective:To explore the effects of different amounts of ethyl alcohol intake on cardiac structure and function, and the effects of oxidative stress on cardiac muscle injury caused by ethyl alcohol. Methods: Two hundred and ninety-three subjects were divided into 4 groups according to the different amounts of ethyl alcohol intake including small amounts of alcohol group(5-20 g/d), the median amounts of alcohol group (20-80 g/d), large amounts of alcohol group(≥80 g) and non-alcohol group (<5 g/d). The echocardiogram test was performed in subjects. The levels of blood B urine sodium pep-tide (BNP), superoxide dismutase(SOD)and metal sulfur protein (MT) were also detected. Results: The left ventricular end systolic diameter (LVSD), the left ventricular end diastolic diameter (LVDD) and the level of serum BNP increased, but the left ventricular ejection fraction (LVEF), the left ventricular fractional shortening (FS) and E/A ratio decreased in median and large amounts of alcohol groups than those of non-alcohol group. The values of LVSD and LVDD increased, but LVSD and LVDD decreased in large amounts of alcohol group than those of median amounts of alcohol group. There was a higher serum level of MDA in median and large amounts of alcohol groups compared with that of non-alcohol group and small amounts of alcohol group. There were significantly lower serum levels of SOD and MT in median and large amounts of alcohol groups than those in small amounts of alcohol group and non-alcohol group (P < 0.0S). Conclusion: Median and large amounts of alcohol intake induced cardiac dilatation and heart dysfunction. There was no influence on cardiac structure and function with small amounts of alcohol intake. The large and median amounts of alcohol intake activate oxidation stress, while small amounts of alcohol intake reduce the level of oxidation stress.%探讨不同乙醇摄入量对心脏结构和功能的影响及氧化应激在乙醇所致心

  10. Evaluation of Young's Modulus and Residual Stress of NiFe Film by Microbridge Testing

    Institute of Scientific and Technical Information of China (English)

    Zhimin ZHOU; Yong ZHOU; Mingjun WANG; Chunsheng YANG; Ji'an CHEN; Wen DING; Xiaoyu GAO; Taihua ZHANG

    2006-01-01

    Microbridge testing was used to measure the Young's modulus and residual stress of metallic films. Samples of freestanding NiFe film microbridge were fabricated by microelectromechanical systems. Special ceramic shaft structure was designed to solve the problem of getting the load-deflection curve of NiFe film microbridge by the Nanoindenter XP system with normal Berkovich probe. Theoretical analysis of load-deflection curves of the microbridges was proposed to evaluate the Young's modulus and residual stress of the films simultaneously. The calculated results based on experimental measurements show that the average Young's modulus and residual stress for the electroplated NiFe films are 203.2 GPa and 333.0 MPa, respectively, while the Young's modulus measured by the Nano-hardness method is 209.6±11.8 GPa for the thick NiFe film with silicon substrate.

  11. MICROBRIDGE TESTING OF YOUNG'S MODULUS AND RESIDUAL STRESS OF NICKEL FILM ELECTROPLATED ON SILICON WAFER

    Institute of Scientific and Technical Information of China (English)

    Y. Zhou; C.S Yang; J.A. Chen; G.F. Ding; L. Wang; M.J. Wang; Y.M. Zhang; T.H. Zhang

    2004-01-01

    Microbridge testing is used to measure the Young's modulus and residual stresses of metallic films. Nickel film microbridges with widths of several hundred microns are fabricated by Microelectromechanical Systems. In order to measure the mechanical properties of nickel film microbridges, special shaft structure is designed to solve the problem of getting the load-deflection curves of metal film microbridge by Nanoindenter XP system with normal Berkovich probe. Theoretical analysis of the microbridge load-deflection curve is proposed to evaluate the Young's modulus and residual stress of the films simultaneously. The calculated results based on the experimental measurements show that the average Young's modulus and residual stress are around 190GPa and 175MPa respectively, while the Young's modulus measured by Nanohardness method on nickel film with silicon substrate is 186.8±7.34GPa.

  12. Operational Review of the First Wireline In Situ Stress Test in Scientific Ocean Drilling

    Directory of Open Access Journals (Sweden)

    Casey Moore

    2012-04-01

    Full Text Available Scientific ocean drilling’s first in situ stress measurement was made at Site C0009A during Integrated Ocean Drilling Program (IODP Expedition 319 as part of Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE Stage 2. The Modular Formation Dynamics Tester (MDT, Schlumbergerwireline logging tool was deployed in riser Hole C0009A to measure in situ formation pore pressure, formation permeability (often reported as mobility=permeability/viscosity, and the least principal stress (S3 at several isolated depths (Saffer et al., 2009; Expedition 319 Scientists, 2010. The importance of in situ stress measurements is not only for scientific interests in active tectonic drilling, but also for geomechanical and well bore stability analyses. Certain in situ tools were not previously available for scientific ocean drilling due to the borehole diameter and open hole limits of riserless drilling. The riser-capable drillship, D/V Chikyu,now in service for IODP expeditions, allows all of the techniques available to estimate the magnitudes and orientations of 3-D stresses to be used. These techniques include downhole density logging for vertical stress, breakout and caliper log analyses for maximum horizontal stress, core-based anelastic strain recovery (ASR, used in the NanTroSEIZE expeditions in 2007–2008, and leak-off test (Lin et al., 2008 and minifrac/hydraulic fracturing (NanTroSEIZE Expedition319 in 2009. In this report, the whole operational planning process related to in situ measurements is reviewed, and lessons learned from Expedition 319 are summarized for efficient planning and testing in the future.

  13. Possibilities of applying pharmacological stress testing in assessment of heart functional capacity in dogs

    Directory of Open Access Journals (Sweden)

    Kosić-Spasojević Ljubica

    2010-01-01

    Full Text Available Systolic and diastolic heart functions, evaluated using echocardiography, do not reflect the functional capacity of the patient and they cannot explain the occurrence of symptoms during a certain degree of activity. Evaluation of the functional capacity is an integral part of cardiological examinations in human medicine. Functional examinations of the heart can be carried out using the body burden test or pharmacologically. Investigations carried out so far into canine cardiology have not contributed to the clinical implementation of functional heart examinations in dogs. Pharmacological stress testing is an optimal way to perform a functional heart examination in dogs. Since it reflects the effects of moderate physical activity, dobutamine has been recommended as the medicine of choice for provoking a pharmacological stress test. This work presents a review of the results of the most important investigations, as well as our own investigations, of the application of the dobutamine stress test (DST in dogs, and the problems in investigations so far have been considered and future directions for DST investigations pointed out. .

  14. Accelerated stress testing and diagnostic analysis of degradation in CdTe solar cells

    Science.gov (United States)

    Albin, David S.

    2008-08-01

    Solar cell module reliability is inextricably linked to cell-level reliability. This is particularly so with thin-film technologies. In CdTe, reliability issues historically associate with back contact stability and the use of Cu as an extrinsic dopant. Using a simple approach by which identical cells are heated under open-circuit bias and 1-sun illumination, degradation activation energies of 0.63 and 2.94 eV in laboratory-scale CdS/CdTe devices were identified in the accelerated stress temperature range of 60 to 120 °C. At lower stress temperatures, cell performance changes were linearly correlated with changes in both fill factor (FF) and short-circuit current (Jsc). At higher stress temperatures, changes in efficiency were correlated with changes in FF and open-circuit voltage (Voc). The measured activation energy of 0.63 is associated with Cu-diffusion. During the early stage of stress testing, which may provide additional back contact annealing, improvements in FF were due to Cu-diffusion. Decreased performance observed at longer stress times (decreased FF and Voc), according to a two-diode Pspice model, were due to both increased space-charge recombination (near the junction) and decreased recombination in the bulk. Kirkendall void formation (S-outdiffusion) at the CdS/CdTe interface is given as responsible for the 2.9 eV degradation mechanism.

  15. Cardiac Risk Assessment

    Science.gov (United States)

    ... Risk Assessment Related tests: Lipid Profile , VLDL Cholesterol , hs-CRP , Lp(a) Overview | Common Questions | Related Pages What ... cardiac risk include: High-sensitivity C-reactive protein (hs-CRP) : Studies have shown that measuring CRP with a ...

  16. Nuclear cardiac imaging for the diagnosis and management of heart failure: what can be learned from recent guidelines?

    Science.gov (United States)

    Vervloet, Delphine M; DE Sutter, Johan

    2016-01-20

    The aim of this review is to provide the clinical cardiologist and nuclear medicine specialist a brief overview of the currently accepted clinical use of cardiac nuclear imaging for the diagnosis and management of patients with heart failure based on recent (2012-2015) European Society of Cardiology (ESC) guidelines. We used the most recent ESC guidelines on heart failure, management of stable coronary artery disease, cardiac pacing, myocardial revascularisation, non-cardiac surgery and ventricular arrhythmias and sudden death. Nowadays cardiac nuclear imaging is useful in almost every step in heart failure from diagnostics to treatment. In first diagnosis of heart failure radionuclide imaging can provide information on ventricular function and volumes and nuclear imaging techniques provide accurate and reproducible left ventricular function assessment. In work out of the aetiology of the heart failure CMR, SPECT and PET imaging can demonstrate presence of inducible ischemia and myocardial viability. For prognostic information MIBG might be promising in the future. In treatment planning cardiac nuclear imaging is important to evaluate new angina and to assess accurate left ventricular ejection fraction before cardiac resynchronization therapy. Imaging stress testing is useful in the preoperative evaluation for non-cardiac surgery of heart failure patients. There is until now no recommended place for cardiac nuclear imaging in the follow-up of heart failure patients or prior to the initiation of cardiac rehabilitation.

  17. 78 FR 47217 - Proposed Supervisory Guidance on Implementing Dodd-Frank Act Company-Run Stress Tests for Banking...

    Science.gov (United States)

    2013-08-05

    ... Company-Run Stress Tests for Banking Organizations With Total Consolidated Assets of More Than $10 Billion... encouraged to submit comments by email, if possible. Please use the title ``Proposed Supervisory Guidance on Implementing Dodd-Frank Act Company-Run Stress Tests for Banking Organizations with Total Consolidated...

  18. 78 FR 72534 - Policy Statement on the Principles for Development and Distribution of Annual Stress Test Scenarios

    Science.gov (United States)

    2013-12-03

    ... the potential impact of adverse outcomes on capital adequacy. Accordingly, the FDIC has decided to... capital planning, assessing capital adequacy, and evaluating risk management practices. The Stress Test... capital adequacy. Stress tests are not the only tool the FDIC uses for these purposes; a...

  19. Cardiovascular and cortisol reactivity and habituation to a virtual reality version of the Trier Social Stress Test: a pilot study

    DEFF Research Database (Denmark)

    Jönsson, Peter; Wallergård, Mattias; Osterberg, Kai

    2010-01-01

    The Trier Social Stress Test (TSST) is a widely used protocol to induce stress in laboratory settings. Briefly, in the TSST, the test participant is asked to hold a speech and to do an arithmetic task in front of an audience. In the present pilot study, we examined endocrine and autonomic...

  20. 78 FR 78165 - Orders: Reporting by Regulated Entities of Stress Testing Results as of September 30, 2013...

    Science.gov (United States)

    2013-12-26

    ... AGENCY 12 CFR Part 1238 Orders: Reporting by Regulated Entities of Stress Testing Results as of September... entities their reporting requirements under the framework established by the final rule, and the revised...-FHLMC-2 Reporting by Regulated Entities of Stress Testing Results as of September 30, 2013...

  1. Subcritical crack growth in oxide and non-oxide ceramics using the Constant Stress Rate Test

    Directory of Open Access Journals (Sweden)

    Agnieszka Wojteczko

    2015-12-01

    Full Text Available Fracture toughness is one of the most important parameters for ceramics description. In some cases, material failure occurs at lower stresses than described by KIc parameter. In these terms, determination of fracture toughness only, proves to be insufficient. This may be due to environmental factors, such as humidity, which might cause subcritical crack propagation in a material. Therefore, it is very important to estimate crack growth velocities to predict lifetime of ceramics used under specific conditions. Constant Stress Rate Test is an indirect method of subcritical crack growth parameters estimation. Calculations are made by using strength data, thus avoiding crack measurement. The expansion of flaws causes reduction of material strength. If subcritical crack growth phenomenon occurs, critical value of crack lengths increases with decreasing stress rate due to longer time for flaw to grow before the critical crack propagation at KIc takes place. Subcritical crack growth phenomenon is particularly dangerous for oxide ceramics due to chemical interactions occurring as a result of exposure to humidity. This paper presents results of Constant Stress Rate Test performed for alumina, zirconia, silicon carbide and silicon nitride in order to demonstrate the differences in subcritical crack propagation phenomenon course.

  2. Ultrasonic vocalizations during intermittent swim stress forecasts resilience in a subsequent juvenile social exploration test of anxiety.

    Science.gov (United States)

    Stafford, Nathaniel P; Jones, Adele M; Drugan, Robert C

    2015-01-01

    Current behavioral paradigms of stress resilience traditionally employ forms of prior manipulation or subsequent testing. Recent work has reported adult rat ultrasonic vocalizations (USVs) emitted during intermittent swim stress (ISS) may serve as a predictor of resilience. ISS-induced USVs predicted resilience on several endpoints of behavioral depression and may be considered a forecast of innate resilience. However, a potential problem for these previous findings is the lack of generalizability to other contexts, because both the stress induction and post-stress testing occur in water. The current study tests the generalizability of USVs as a predictor of stress resilience in a non-water-based post-test, the juvenile social exploration test of anxiety. The results provide further support that USVs emitted during ISS predict resilience to depression- and anxiety-like behaviors. Extensions of this work to examine the neurobiology of innate resilience associated with ISS-induced USVs are discussed with comparisons to extant models of learned resilience.

  3. The Stress Analysis and Tests on the Hinge Beam of the Diamond Synthesis Cubic Press

    Directory of Open Access Journals (Sweden)

    Ma Liang

    2016-01-01

    Full Text Available To deal with the problem of the lug fractures of hinge beam caused by the fatigue and overload during the operation of the cubic press, the analysis methods of finite element are applied to the analysis of the internal stress distributions of the hinge beam. The simulation results show that the internal stress of the hinge beam mainly concentrates on the upper surface of the lug roots connecting the outer cylinder with the both lugs. According to the data of simulation and analysis as well as the actual fracture situations, considering the strain-test methods we have designed the schemes of testing the strain on the lugs of hinge beam. And the strain measurements of the lugs are completed by the repeated loading experiments. Comparing the data of simulation and analysis with the measured data has verified their consistency. It also confirms the model established by the simulation and analysis is reasonable and accurate at the same time.

  4. What do central counterparties default funds really cover? A network-based stress test answer

    CERN Document Server

    Poce, Giulia; Gabrielli, Andrea; Zaccaria, Andrea; Baldacci, Giuditta; Polito, Marco; Rizzo, Mariangela; Sabatini, Silvia

    2016-01-01

    In the last years, increasing efforts have been put into the development of effective stress tests to quantify the resilience of financial institutions. Here we propose a stress test methodology for central counterparties based on a network characterization of clearing members, whose links correspond to direct credits and debits. This network constitutes the ground for the propagation of financial distress: equity losses caused by an initial shock with both exogenous and endogenous components reverberate within the network and are amplified through credit and liquidity contagion channels. At the end of the dynamics, we determine the vulnerability of each clearing member, which represents its potential equity loss. We apply the proposed framework to the Fixed Income asset class of CC&G, the central counterparty operating in Italy whose main cleared securities are Italian Government Bonds. We consider two different scenarios: a distributed, plausible initial shock, as well as a shock corresponding to the co...

  5. In vitro blood flow model with physiological wall shear stress for hemocompatibility testing-An example of coronary stent testing.

    Science.gov (United States)

    Engels, Gerwin Erik; Blok, Sjoerd Leendert Johannes; van Oeveren, Willem

    2016-09-18

    Hemocompatibility of blood contacting medical devices has to be evaluated before their intended application. To assess hemocompatibility, blood flow models are often used and can either consist of in vivo animal models or in vitro blood flow models. Given the disadvantages of animal models, in vitro blood flow models are an attractive alternative. The in vitro blood flow models available nowadays mostly focus on generating continuous flow instead of generating a pulsatile flow with certain wall shear stress, which has shown to be more relevant in maintaining hemostasis. To address this issue, the authors introduce a blood flow model that is able to generate a pulsatile flow and wall shear stress resembling the physiological situation, which the authors have coined the "Haemobile." The authors have validated the model by performing Doppler flow measurements to calculate velocity profiles and (wall) shear stress profiles. As an example, the authors evaluated the thrombogenicity of two drug eluting stents, one that was already on the market and one that was still under development. After identifying proper conditions resembling the wall shear stress in coronary arteries, the authors compared the stents with each other and often used reference materials. These experiments resulted in high contrast between hemocompatible and incompatible materials, showing the exceptional testing capabilities of the Haemobile. In conclusion, the authors have developed an in vitro blood flow model which is capable of mimicking physiological conditions of blood flow as close as possible. The model is convenient in use and is able to clearly discriminate between hemocompatible and incompatible materials, making it suitable for evaluating the hemocompatible properties of medical devices.

  6. The Neuromatrix Theory of Pain and Angina during Exercise Stress Testing: Results from the PIMI Study

    Science.gov (United States)

    2011-05-27

    al., 1988; Glusman et al., 1996). In these individuals, the opioid reactivity would produce stronger analgesia of pain from most inputs, including...pain thresholds in silent ischemics might generalize to other areas as well. Pain tests in areas such as the toe, finger or dental pain thresholds...induced opioid Angina and the Neuromatrix 20 analgesia . Indeed, perhaps people who genetically have greater β-endorphin reactivity to stress

  7. Testing a Theoretical Model of the Stress Process in Alzheimer's Caregivers With Race as a Moderator

    OpenAIRE

    Hilgeman, Michelle M.; Durkin, Daniel W.; Sun, Fei; DeCoster, Jamie; Allen, Rebecca S.; Gallagher-Thompson, Dolores; Burgio, Louis D.

    2009-01-01

    Purpose: The primary aim of this study was to test the stress process model (SPM; Pearlin, Mullan, Semple, & Skaff, 1990) in a racially diverse sample of Alzheimer's caregivers (CGs) using structural equation modeling (SEM) and regression techniques. A secondary aim was to examine race or ethnicity as a moderator of the relation between latent constructs (e.g., subjective stressors and role strain) in the SPM. Sample: Participants included White or Caucasian (n = 212), Black or African Americ...

  8. South Africa; Financial Sector Assessment Program-Stress Testing the Financial System-Technical Note

    OpenAIRE

    International Monetary Fund

    2015-01-01

    This Technical Note discusses stress testing (ST) results for the financial system of South Africa. The bank STs suggest that banks have adequate capital to withstand severe shocks, but need larger liquidity capacity to meet regulatory requirements. Even in the severe scenario in which GDP falls for three consecutive years, banks’ capital buffers seem sufficient, although the impact of a large default could be significant. Banks also appear resilient to market risks in both the trading and ...

  9. Prognostic value of non-invasive stress testing for coronary artery disease in obese patients.

    Science.gov (United States)

    Bigvava, Tamar; Zamani, Seyedeh Mahsa; Pieske-Kraigher, Elisabeth; Gebker, Rolf; Pieske, Burkert; Kelle, Sebastian

    2015-12-01

    Detecting coronary artery disease (CAD) in obese patients remains a challenge but can have substantial prognostic implications for this patient group. Until now, sufficient data was not available on which to base the selection of the imaging modality in obese patients. The decision on which imaging modality to use should therefore follow the general guidelines. In this article, the authors discuss the prognostic value of the different non-invasive stress testing methods for CAD in obese patients.

  10. Testing to Investigate Stress-LifetimeCharacteristics of High Voltage Printed Circuit Boards

    Science.gov (United States)

    El Korashy, Oliver; Franke, Andreas; Gollor, Matthias

    2014-08-01

    Printed circuit boards (PCBs) are typically used in all electronic equipment, including those conditioning or controlling high voltage (HV) for space satellite applications. With the use of new subsystems that require higher voltages (generally several hundred volts up to tens of kV), stress-lifetime issues are becoming more complex. In order to allow compact design and cost efficient production of HV modules, there is an increasing demand to improve the design of PCBs with encapsulation or conformal coating at higher voltages.Within a PCB there are a number of electrical field interfaces each of which can have individual stress- lifetime characteristics, and the influence of environmental aging should also be considered, which means a large number of sample types should be tested to gain experimental evidence to define the margin for each interface. This paper demonstrates a method to test multiple samples at a fixed DC voltage stress until the event of a breakdown, and presents test results from 6 single-sided encapsulated PCB samples.

  11. Assessment of Initial Test Conditions for Experiments to Assess Irradiation Assisted Stress Corrosion Cracking Mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Busby, Jeremy T [ORNL; Gussev, Maxim N [ORNL

    2011-04-01

    Irradiation-assisted stress corrosion cracking is a key materials degradation issue in today s nuclear power reactor fleet and affects critical structural components within the reactor core. The effects of increased exposure to irradiation, stress, and/or coolant can substantially increase susceptibility to stress-corrosion cracking of austenitic steels in high-temperature water environments. . Despite 30 years of experience, the underlying mechanisms of IASCC are unknown. Extended service conditions will increase the exposure to irradiation, stress, and corrosive environment for all core internal components. The objective of this effort within the Light Water Reactor Sustainability program is to evaluate the response and mechanisms of IASCC in austenitic stainless steels with single variable experiments. A series of high-value irradiated specimens has been acquired from the past international research programs, providing a valuable opportunity to examine the mechanisms of IASCC. This batch of irradiated specimens has been received and inventoried. In addition, visual examination and sample cleaning has been completed. Microhardness testing has been performed on these specimens. All samples show evidence of hardening, as expected, although the degree of hardening has saturated and no trend with dose is observed. Further, the change in hardening can be converted to changes in mechanical properties. The calculated yield stress is consistent with previous data from light water reactor conditions. In addition, some evidence of changes in deformation mode was identified via examination of the microhardness indents. This analysis may provide further insights into the deformation mode under larger scale tests. Finally, swelling analysis was performed using immersion density methods. Most alloys showed some evidence of swelling, consistent with the expected trends for this class of alloy. The Hf-doped alloy showed densification rather than swelling. This observation may be

  12. Modification of the NEMA XR21-2000 cardiac phantom for testing of imaging systems used in endovascular image guided interventions

    Science.gov (United States)

    Ionita, C. N.; Dohatcu, A.; Jain, A.; Keleshis, C.; Hoffmann, K. R.; Bednarek, D. R.; Rudin, S.

    2009-02-01

    X-ray equipment testing using phantoms that mimic the specific human anatomy, morphology, and structure is a very important step in the research, development, and routine quality assurance for such equipment. Although the NEMA XR21 phantom exists for cardiac applications, there is no such standard phantom for neuro-, peripheral and cardiovascular angiographic applications. We have extended the application of the NEMA XR21-2000 phantom to evaluate neurovascular x-ray imaging systems by structuring it to be head-equivalent; two aluminum plates shaped to fit into the NEMA phantom geometry were added to a 15 cm thick section. Also, to enable digital subtraction angiography (DSA) testing, two replaceable central plates with a hollow slot were made so that various angiographic sections could be inserted into the phantom. We tested the new modified phantom using a flat panel C-arm unit dedicated for endovascular image-guided interventions. All NEMA XR21-2000 standard test sections were used in evaluations with the new "headequivalent" phantom. DSA and DA are able to be tested using two standard removable blocks having simulated arteries of various thickness and iodine concentrations (AAPM Report 15). The new phantom modifications have the benefits of enabling use of the standard NEMA phantom for angiography in both neuro- and cardio-vascular applications, with the convenience of needing only one versatile phantom for multiple applications. Additional benefits compared to using multiple phantoms are increased portability and lower cost.

  13. Proposed Testing to Assess the Accuracy of Glass-To-Metal Seal Stress Analyses.

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, Robert S.; Emery, John M; Tandon, Rajan; Antoun, Bonnie R.; Stavig, Mark E.; Newton, Clay S.; Gibson, Cory S; Bencoe, Denise N.

    2014-09-01

    The material characterization tests conducted on 304L VAR stainless steel and Schott 8061 glass have provided higher fidelity data for calibration of material models used in Glass - T o - Metal (GTM) seal analyses. Specifically, a Thermo - Multi - Linear Elastic Plastic ( thermo - MLEP) material model has be en defined for S S304L and the Simplified Potential Energy Clock nonlinear visc oelastic model has been calibrated for the S8061 glass. To assess the accuracy of finite element stress analyses of GTM seals, a suite of tests are proposed to provide data for comparison to mo del predictions.

  14. Flipping the advanced cardiac life support classroom with team-based learning: comparison of cognitive testing performance for medical students at the University of California, Irvine, United States

    Directory of Open Access Journals (Sweden)

    Megan Boysen-Osborn

    2016-02-01

    Full Text Available Purpose: It aimed to find if written test results improved for advanced cardiac life support (ACLS taught in flipped classroom/team-based Learning (FC/TBL vs. lecture-based (LB control in University of California-Irvine School of Medicine, USA. Methods: Medical students took 2010 ACLS with FC/TBL (2015, compared to 3 classes in LB (2012-14 format. There were 27.5 hours of instruction for FC/TBL model (TBL 10.5, podcasts 9, small-group simulation 8 hours, and 20 (12 lecture, simulation 8 hours in LB. TBL covered 13 cardiac cases; LB had none. Seven simulation cases and didactic content were the same by lecture (2012-14 or podcast (2015 as was testing: 50 multiple-choice questions (MCQ, 20 rhythm matchings, and 7 fill-in clinical cases. Results: 354 students took the course (259 [73.1%] in LB in 2012-14, and 95 [26.9%] in FC/TBL in 2015. Two of 3 tests (MCQ and fill-in improved for FC/TBL. Overall, median scores increased from 93.5% (IQR 90.6, 95.4 to 95.1% (92.8, 96.7, P=0.0001. For the fill-in test: 94.1% for LB (89.6, 97.2 to 96.6% for FC/TBL (92.4, 99.20 P=0.0001. For MC: 88% for LB (84, 92 to 90% for FC/TBL (86, 94, P=0.0002. For the rhythm test: median 100% for both formats. More students failed 1 of 3 tests with LB vs. FC/TBL (24.7% vs. 14.7%, and 2 or 3 components (8.1% vs. 3.2%, P=0.006. Conversely, 82.1% passed all 3 with FC/TBL vs. 67.2% with LB (difference 14.9%, 95% CI 4.8-24.0%. Conclusion: A FC/TBL format for ACLS marginally improved written test results.

  15. Flipping the advanced cardiac life support classroom with team-based learning: comparison of cognitive testing performance for medical students at the University of California, Irvine, United State

    Science.gov (United States)

    2016-01-01

    Purpose: It aimed to find if written test results improved for advanced cardiac life support (ACLS) taught in flipped classroom/team-based Learning (FC/TBL) vs. lecture-based (LB) control in University of California-Irvine School of Medicine, USA. Methods: Medical students took 2010 ACLS with FC/TBL (2015), compared to 3 classes in LB (2012-14) format. There were 27.5 hours of instruction for FC/TBL model (TBL 10.5, podcasts 9, small-group simulation 8 hours), and 20 (12 lecture, simulation 8 hours) in LB. TBL covered 13 cardiac cases; LB had none. Seven simulation cases and didactic content were the same by lecture (2012-14) or podcast (2015) as was testing: 50 multiple-choice questions (MCQ), 20 rhythm matchings, and 7 fill-in clinical cases. Results: 354 students took the course (259 [73.1%] in LB in 2012-14, and 95 [26.9%] in FC/TBL in 2015). Two of 3 tests (MCQ and fill-in) improved for FC/TBL. Overall, median scores increased from 93.5% (IQR 90.6, 95.4) to 95.1% (92.8, 96.7, P=0.0001). For the fill-in test: 94.1% for LB (89.6, 97.2) to 96.6% for FC/TBL (92.4, 99.20 P=0.0001). For MC: 88% for LB (84, 92) to 90% for FC/TBL (86, 94, P=0.0002). For the rhythm test: median 100% for both formats. More students failed 1 of 3 tests with LB vs. FC/TBL (24.7% vs. 14.7%), and 2 or 3 components (8.1% vs. 3.2%, P=0.006). Conversely, 82.1% passed all 3 with FC/TBL vs. 67.2% with LB (difference 14.9%, 95% CI 4.8-24.0%). Conclusion: A FC/TBL format for ACLS marginally improved written test results. PMID:26893399

  16. Critiquing symptom validity tests for posttraumatic stress disorder: a modification of Hartman's criteria.

    Science.gov (United States)

    Morel, Kenneth R; Marshman, Kimberly C

    2008-12-01

    The differential diagnosis of malingering in psychological evaluations for Posttraumatic Stress Disorder (PTSD) is complex and relies upon the integration of clinical knowledge and appropriate psychometric instruments. Over the years, there has been an increase in the use of validity measures, including Symptom Validity Tests (SVTs). In 2005, the National Academy of Neuropsychology published Symptom validity assessment: Practice issues and medical necessity, an official policy statement recognizing the importance of effort on test performance and recommending the utilization of specific SVTs to assess for response bias in neurocognitive and personality evaluations. As new SVTs become available, clinicians need a clear understanding of how to critique these tests and determine the strengths and limitations. This article demonstrates the fundamental principles of critiquing an SVT by applying a modified set of Hartman's [Hartman, D. E. (2002). The unexamined lie is a lie worth fibbing: Neuropsychological malingering and the Word Memory Test. Archives of Clinical Neuropsychology, 17, 709-714] criteria, originally developed for neuropsychological SVTs, to the Morel Emotional Numbing Test for Posttraumatic Stress Disorder (MENT).

  17. Oxidative Stress Level in the Testes of Mice and Rats during Nickel Intoxication

    Directory of Open Access Journals (Sweden)

    Eugenia Murawska-Ciałowicz

    2012-01-01

    Full Text Available The genotioxic and carcinogenic effect of nickel probably results from its capacity to produce reactive oxygen species (ROS and disturb the redox balance. The aim of the study was to find out if rats lacking spermatic protamine 2 are less susceptible to Ni(II than mice. Consequently, the levels of malondialdehyde + 4 hydroxynonenal (MDA+4HDA − markers of lipid peroxidation, as well as the level of reduced glutathione (GSH were measured within the rat and mouse testes. Our results showed that the levels of lipid peroxidation markers were elevated in testicular homogenates of intoxicated mice without any changes in rats. GSH level was lower in the group of intoxicated mice comparing to the control without statistically significant changes in rats’ homogenates. Moreover, the level of GSH in the testes of intoxicated mice was lower than in rats. On the basis of our results, it appears that Ni(II can initiate oxidative stress in the testes of mice but not of rats and can reduce GSH level. Consequently, the antioxidative defense of the testes is reduced. Ni(II that causes oxidative stress in the testes may also contribute to infertility.

  18. Critical assessment of precracked specimen configuration and experimental test variables for stress corrosion testing of 7075-T6 aluminum alloy plate

    Science.gov (United States)

    Domack, M. S.

    1985-01-01

    A research program was conducted to critically assess the effects of precracked specimen configuration, stress intensity solutions, compliance relationships and other experimental test variables for stress corrosion testing of 7075-T6 aluminum alloy plate. Modified compact and double beam wedge-loaded specimens were tested and analyzed to determine the threshold stress intensity factor and stress corrosion crack growth rate. Stress intensity solutions and experimentally determined compliance relationships were developed and compared with other solutions available in the literature. Crack growth data suggests that more effective crack length measurement techniques are necessary to better characterize stress corrosion crack growth. Final load determined by specimen reloading and by compliance did not correlate well, and was considered a major source of interlaboratory variability. Test duration must be determined systematically, accounting for crack length measurement resolution, time for crack arrest, and experimental interferences. This work was conducted as part of a round robin program sponsored by ASTM committees G1.06 and E24.04 to develop a standard test method for stress corrosion testing using precracked specimens.

  19. Antidepressant-like effects of Sanyuansan in the mouse forced swim test, tail suspension test, and chronic mild stress model.

    Science.gov (United States)

    Yan, Shuo; You, Zi-Li; Zhao, Qiu-Ying; Peng, Cheng; He, Gang; Gou, Xiao-Jun; Lin, Bin

    2015-12-01

    Natural products have been widely reported as effective therapeutic alternatives for treatment of depression. Sanyuansan is a compound recipe composed of ginseng total saponins, fish oil, and valeriana. The aims of this study were to validate whether Sanyuansan has antidepressant-like effects through acute behavioral tests including the forced swimming test (FST), tail suspension test (TST), locomotor activity test, and chronic mild stress (CMS) mice model of depression. C57BL/6 mice were given oral administration of 30 mg/kg imipramine, Sanyuansan, and saline, respectively. The acute behavioral tests including the TST, FST, and locomotor activity test were done after the administration of drugs for consecutively three times (24 hours, 1 hour, and 0.5 hour prior to the tests). Furthermore, the sucrose preference and the serum corticosterone level of mice in the CMS model were examined. Sanyuansan only at 900 mg/kg markedly reduced immobility time in the TST compared with the saline-treated group of mice. Sanyuansan at doses of 225 mg/kg, 450 mg/kg, and 900 mg/kg significantly reduced immobility time of mice in the FST. Sanyuansan reversed the CMS-induced anhedonia and hyperactivation of the hypothalamus-pituitary-adrenal axis. In addition, our results showed that neither imipramine nor Sanyuansan at any dosage increased spontaneous motor activity. These results suggested that Sanyuansan induced significant antidepressant-like effects in mice in both acute and chronic animal models, which seemed unlikely to be attributed to an increase in locomotor activities of mice, and had no sedative-like effects.

  20. Design and Experimental Evaluation of a 3rd Generation Addressable CMOS Piezoresistive Stress Sensing Test Chip

    Energy Technology Data Exchange (ETDEWEB)

    Sweet, J.N.; Peterson, D.W.; Hsia, A.H.

    1999-04-13

    Piezoresistive stress sensing chips have been used extensively for measurement of assembly related die surface stresses. Although many experiments can be performed with resistive structures which are directly bonded, for extensive stress mapping it is necessary to have a large number of sensor cells which can be addressed using CMOS logic circuitry. Our previous test chip, the ATC04, has 100 cells, each approximately 0.012 in. on a side, on a chip with a side dimension of 0.45 in. When a cell resistor is addressed, it is connected to a four terminal measurement bus through CMOS transmission gates. In theory, the gate resistances do not affect the measurement. In practice, there may be subtle effects which appear when very high accuracy is required. At high temperatures, gate leakage can increase to a point at which the resistor measurement becomes inaccurate. For ATC04 this occurred at or above 50 C. Here, we report on the first measurements obtained with a new prototype test chip, the ATC06. This prototype was fabricated in a 0.5 micron feature size silicided CMOS process using the MOSIS prototyping facility. The cell size was approximately 0.004 in. on a side. In order to achieve piezoresistive behavior for the implanted resistors it was necessary to employ a non-standard silicide ''blocking'' process. The stress sensitivity of both implanted and polysilicon blocked resistors is discussed. Using a new design strategy for the CMOS logic, it was possible to achieve a design in which only 5 signals had to be routed to a cell for addressing vs. 9 for ATC04. With our new design, the resistor under test is more effectively electrically isolated from other resistors on the chip, thereby improving high temperature performance. We present data showing operation up to 140 C.

  1. Improvement of cognitive test performance in patients undergoing primary CABG and other CPB-assisted cardiac procedures.

    Science.gov (United States)

    van den Goor, Jm; Saxby, Bk; Tijssen, Jg; Wesnes, Ka; de Mol, Ba; Nieuwland, R

    2008-09-01

    Cardiac surgical procedures assisted by cardiopulmonary bypass (CPB) impair cognitive functions. Several studies, however, showed that cognitive functions were unaffected in patients undergoing either primary coronary artery bypass grafting (CABG) or more complex surgery assisted by CPB. Therefore, we conducted a straightforward study to compare patient groups who differed significantly in terms of risk factors such as prolonged CPB times. Consecutive patients (n = 54) were included, undergoing either non-primary CABG, e.g. valve and/or CABG, (n = 30) or primary CABG (n = 24), assisted by CPB. Cognitive function was determined pre-operatively on the day of hospital admission, and post-operatively after one and six months using the Cognitive Drug Research computerized assessment battery. Data from the fourteen individual task variables were summarized in four composite scores: Power of Attention (PoA), Continuity of Attention (CoA), Quality of Episodic Memory (QoEM), and Speed of Memory (SoM). In the non-primary CABG patients, both CoA and QoEM improved after 1 month (p = 0.001 and p = 0.016, respectively), whereas, after 6 months, CoA (p = 0.002), QoEM (p = 0.002) and SoM (p CPB in both non-primary CABG and in primary CABG patients.

  2. Effect of thioperamide on modified forced swimming test-induced oxidative stress in mice.

    Science.gov (United States)

    Akhtar, Mohd; Pillai, K K; Vohora, Divya

    2005-10-01

    This study was designed i) to investigate the role of histamine H3-receptor ligands on mouse modified forced swimming test, a method that distinguishes the catecholaminergic behaviour with that of serotonergic compounds and ii) to evaluate the role of free radicals in mediation of such effects. Swiss strain albino mice were treated with different doses of histamine H3-receptor antagonist thioperamide (3.75, 7.5 and 15 mg/kg intraperitoneally) and agonist (R)-alpha-methylhistamine (5 microg intracerebroventricularly). The climbing, swimming and immobility times were recorded for 6 min. Immediately after modified forced swimming test, the animals were sacrificed and parameters of oxidative stress were assessed in the brain by measuring the thiobarbituric acid reactive substance (TBARS), glutathione (GSH) and catalase levels. Thioperamide (7.5 and 15 mg/kg intraperitoneally) dose-dependently decreased immobility time and increased swimming time but not climbing time. The behaviour of mice treated with (R)-alpha-methylhistamine was similar to that of control mice. A significant reduction in GSH and an increase in catalase levels were observed in brains of mice exposed to modified forced swimming test. Thioperamide pretreatment dose-dependently reversed such an alteration in oxidative stress parameters. (R)-alpha-methylhistamine caused a reversal of altered catalase but not GSH levels. Thioperamide shows antidepressant effects in the modified forced swimming test and causes a reversal of the test-induced oxidative stress indicating its antioxidant potential. The antidepressant effect of thioperamide appears to be mediated via serotonergic and/or antioxidant mechanisms.

  3. Sildenafil vs. Nitroprussiato de Sódio durante Teste de Reatividade Pulmonar pré-transplante cardíaco Sildenafil vs. sodium before nitroprusside for the pulmonary hypertension reversibility test before cardiac transplantation

    Directory of Open Access Journals (Sweden)

    Aguinaldo Figueiredo Freitas Jr

    2012-09-01

    Full Text Available FUNDAMENTO: A hipertensão pulmonar é associada ao pior prognóstico no pós-transplante cardíaco. O teste de reatividade pulmonar com Nitroprussiato de Sódio (NPS está associado a elevados índices de hipotensão arterial sistêmica, disfunção ventricular do enxerto transplantado e elevadas taxas de desqualificação para o transplante. OBJETIVO: Neste estudo, objetivou-se comparar os efeitos do Sildenafil (SIL e NPS sobre variáveis hemodinâmicas, neuro-hormonais e ecocardiográficas durante teste de reatividade pulmonar. MÉTODOS: Os pacientes foram submetidos, simultaneamente, ao cateterismo cardíaco direito, ao ecocardiograma e à dosagem de BNP e gasometria venosa, antes e após administração de NPS (1 - 2 µg/Kg/min ou SIL (100 mg, dose única. RESULTADOS: Ambos reduziram a hipertensão pulmonar, porém o nitrato promoveu hipotensão sistêmica significativa (Pressão Arterial Média - PAM: 85,2 vs. 69,8 mmHg, p BACKGROUND: Pulmonary hypertension is associated with a worse prognosis after cardiac transplantation. The pulmonary hypertension reversibility test with sodium nitroprusside (SNP is associated with a high rate of systemic arterial hypotension, ventricular dysfunction of the transplanted graft and high rates of disqualification from transplantation. OBJECTIVE: This study was aimed at comparing the effects of sildenafil (SIL and SNP on hemodynamic, neurohormonal and echocardiographic variables during the pulmonary reversibility test. METHODS: The patients underwent simultaneously right cardiac catheterization, echocardiography, BNP measurement, and venous blood gas analysis before and after receiving either SNP (1 - 2 µg/kg/min or SIL (100 mg, single dose. RESULTS: Both drugs reduced pulmonary hypertension, but SNP caused a significant systemic hypotension (mean blood pressure - MBP: 85.2 vs. 69.8 mm Hg; p < 0.001. Both drugs reduced cardiac dimensions and improved left cardiac function (SNP: 23.5 vs. 24.8%, p = 0

  4. Stress

    DEFF Research Database (Denmark)

    Keller, Hanne Dauer

    2015-01-01

    Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb.......Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb....

  5. Reproducibility of ratings of perceived exertion soon after myocardial infarction: responses in the stress-testing clinic and the rehabilitation gymnasium.

    Science.gov (United States)

    Buckley, John P; Sim, Julius; Eston, Roger G

    2009-04-01

    The purpose of this study was to compare ratings of perceived exertion (RPE; Borg's 6-20 scale) at the same exercise intensity, between a standard exercise electrocardiogram (ECG) treadmill stress test (exECG) and two subsequent bouts of treadmill exercise in a cardiac rehabilitation gymnasium. Eleven patients (mean +/- s) 60.8 +/- 6.1 years performed an exECG within 12.1 +/- 7.5 d after myocardial infarction (MI) and commenced their first exercise-based rehabilitation session (gym-1), which included the use of a motorised treadmill, within 5.0 +/- 1.3 d after the exECG. A second gym session (gym-2) was performed within 4.2 +/- 1.3 d of gym-1. Gym-1 and gym-2 treadmill exercise was performed at an intensity that equated to the penultimate testing stage of exECG, and RPE and heart rate were compared at this level between the three sessions of testing. The mean work rate at the penultimate testing stage of the exECG was 6.0 +/- 1.0 metabolic equivalents; approximately 67% of peak work rate. The RPE at this work rate during exECG, gym-1 and gym-2 were 15.8 +/- 2.7, 13.3 +/- 3.4 and 13.0 +/- 3.6, respectively. A repeated measures ANOVA revealed these RPE responses to be significantly different (F (2, 20) = 9.8; p = 0.001). Post-hoc Bonferroni-corrected pairwise t-tests showed significant differences (p < or = 0.008) between exECG and gym-1 and exECG and gym-2 but not between gym-1 and gym-2. There was no significant difference in heart rate between the three testing sessions (p = 0.076) but it showed signs of a similar trend to RPE. The intra-participant agreement in RPE between gym-1 and gym-2 was substantial; intraclass correlation coefficient (ICC(2,1)) = 0.85 (p < 0.001) and in all but one participant, RPE differed by < or =2 scale points. The RPE responses during standardised exECG treadmill testing, in patients soon after MI, are inflated compared to responses at the same treadmill work rate during subsequent cardiac rehabilitation exercise sessions. Caution is

  6. Cardiac Rehabilitation

    Science.gov (United States)

    ... your risk of future heart problems, and to improve your health and quality of life. Cardiac rehabilitation programs increase ... exercise routine at home or at a local gym. You may also continue to ... health concerns. Education about nutrition, lifestyle and weight loss ...

  7. Work-related stress is associated with impaired neuropsychological test performance: a clinical cross-sectional study.

    Science.gov (United States)

    Eskildsen, Anita; Andersen, Lars Peter; Pedersen, Anders Degn; Vandborg, Sanne Kjær; Andersen, Johan Hviid

    2015-01-01

    Patients on sick leave due to work-related stress often complain about impaired concentration and memory. However, it is undetermined how widespread these impairments are, and which cognitive domains are most long-term stress sensitive. Previous studies show inconsistent results and are difficult to synthesize. The primary aim of this study was to examine whether patients with work-related stress complaints have cognitive impairments compared to a matched control group without stress. Our secondary aim was to examine whether the level of self-reported perceived stress is associated with neuropsychological test performance. We used a broad neuropsychological test battery to assess 59 outpatients with work-related stress complaints (without major depression) and 59 healthy controls. We matched the patients and controls pairwise by sex, age and educational level. Compared to controls, patients generally showed mildly reduced performance across all the measured domains of the neuropsychological test battery. However, only three comparisons reached statistical significance (p working memory. There were no statistical significant associations between self-reported perceived stress level and neuropsychological test performance. In conclusion, we recommend that cognitive functions should be considered when evaluating patients with work-related stress complaints, especially when given advice regarding return to work. Since this study had a cross-sectional design, it is still uncertain whether the impairments are permanent. Further study is required to establish causal links between work-related stress and cognitive deficits.

  8. Field test on temperature field and thermal stress for prestressed concrete box-girder bridge

    Institute of Scientific and Technical Information of China (English)

    Baoguo CHEN; Rui DING; Junjie ZHENG; Shibiao ZHANG

    2009-01-01

    A field test was conducted to investigate the distribution of temperature field and the variation of thermal stress for a prestressed concrete (PC) box-girder bridge. The change of hydration heat temperature consists of four periods: temperature rising period, constant temperature period, rapid temperature fall period and stow temperature fall period. The peak value of hydration heat temperature increases with the increasing casting temperature of concrete; the relation between them is approximately linear. According to field tests, the thermal stress incurred by hydration heat may induce temperature cracks on the PC box-girder. Furthermore, the nonlinear distribution of temperature gradient and the fluctuation of thermal stress induced by exposure to sunlight were also obtained based on continuous in-situ monitoring. Such results show that the prevailing Chinese Code (2004) is insufficient since it does not take into account the temperature gradient of the bottom slab. Finally, some preventive measures against temperature cracks were proposed based on related studies. The conclusions can provide valuable reference for the design and construction of PC box-girder bridges.

  9. Cardiac abnormalities after subarachnoid hemorrhage

    NARCIS (Netherlands)

    Bilt, I.A.C. van der

    2016-01-01

    Aneurysmal subarachnoid hemorrhage(aSAH) is a devastating neurological disease. During the course of the aSAH several neurological and medical complications may occur. Cardiac abnormalities after aSAH are observed often and resemble stress cardiomyopathy or Tako-tsubo cardiomyopathy(Broken Heart Syn

  10. Reduction of blood oxygen levels enhances postprandial cardiac hypertrophy in Burmese python (Python bivittatus).

    Science.gov (United States)

    Slay, Christopher E; Enok, Sanne; Hicks, James W; Wang, Tobias

    2014-05-15

    Physiological cardiac hypertrophy is characterized by reversible enlargement of cardiomyocytes and changes in chamber architecture, which increase stroke volume and via augmented convective oxygen transport. Cardiac hypertrophy is known to occur in response to repeated elevations of O2 demand and/or reduced O2 supply in several species of vertebrate ectotherms, including postprandial Burmese pythons (Python bivittatus). Recent data suggest postprandial cardiac hypertrophy in P. bivittatus is a facultative rather than obligatory response to digestion, though the triggers of this response are unknown. Here, we hypothesized that an O2 supply-demand mismatch stimulates postprandial cardiac enlargement in Burmese pythons. To test this hypothesis, we rendered animals anemic prior to feeding, essentially halving blood oxygen content during the postprandial period. Fed anemic animals had heart rates 126% higher than those of fasted controls, which, coupled with a 71% increase in mean arterial pressure, suggests fed anemic animals were experiencing significantly elevated cardiac work. We found significant cardiac hypertrophy in fed anemic animals, which exhibited ventricles 39% larger than those of fasted controls and 28% larger than in fed controls. These findings support our hypothesis that those animals with a greater magnitude of O2 supply-demand mismatch exhibit the largest hearts. The 'low O2 signal' stimulating postprandial cardiac hypertrophy is likely mediated by elevated ventricular wall stress associated with postprandial hemodynamics.

  11. Cardiac magnetic resonance imaging after ventricular tachyarrhythmias increases diagnostic precision and reduces the need for family screening for inherited cardiac disease

    DEFF Research Database (Denmark)

    Marstrand, Peter; Axelsson, Anna; Thune, Jens Jakob

    2017-01-01

    -CAG) (81%), exercise stress test (47%), late potentials (54%), electrophysiological study (44%), pharmacological provocation (44%), and/or myocardial biopsy (16%). Family screening was indicated for 53 probands (67%) prior to CMR. After full workup, only 43 cases (54%) warranted evaluation of relatives (19...... magnetic resonance imaging re-defines the cardiac diagnoses in a significant proportion of cases and reduces the number of patients in whom family screening is warranted. Cardiac magnetic resonance imaging is highly relevant for optimal care and resource allocation when an inherited heart disease...

  12. Red wine is less stress reducing than vodka; no differences in neuroendocrine challenge test.

    Science.gov (United States)

    Jarrett, N; Peatfield, R; Glover, V

    1997-01-01

    Red wine, like the drugs reserpine and fenfluramine, causes the release of 5-hydroxytryptamine (5-HT) from storage sites in vitro. This study used a neuroendocrine challenge test design to determine whether the parallel between red wine and these drugs can be extended to central actions in healthy volunteers. Vodka diluted to an equal alcohol content was used as a control. No significant differences were observed between the groups in plasma cortisol, plasma prolactin or in temperature levels. Thus no evidence was obtained for a central 5-HT releasing action by red wine. Self-rating stress and arousal questionnaires were also given. No differences were found in arousal. However whereas vodka had a clear effect in reducing stress, red wine did not. This suggests that red wine does have psychoactive properties independent of its alcohol effects.

  13. The effect of Trier Social Stress Test (TSST) on item and associative recognition of words and pictures in healthy participants

    OpenAIRE

    Jonathan eGuez; Rotem eSaar-Ashkenazy; Eldad eKeha; Chen eTiferet

    2016-01-01

    Psychological stress, induced by the Trier Social Stress Test (TSST), has repeatedly been shown to alter memory performance. Although factors influencing memory performance such as stimulus nature (verbal /pictorial) and emotional valence have been extensively studied, results whether stress impairs or improves memory are still inconsistent. This study aimed at exploring the effect of TSST on item versus associative memory for neutral, verbal, and pictorial stimuli. 48 healthy subjects were r...

  14. The limits of testing particle-mediated oxidative stress in vitro in predicting diverse pathologies; relevance for testing of nanoparticles

    Directory of Open Access Journals (Sweden)

    Gulumian Mary

    2009-04-01

    Full Text Available Abstract In vitro studies with particles are a major staple of particle toxicology, generally used to investigate mechanisms and better understand the molecular events underlying cellular effects. However, there is ethical and financial pressure in nanotoxicology, the new sub-specialty of particle toxicology, to avoid using animals. Therefore an increasing amount of studies are being published using in vitro approaches and such studies require careful interpretation. We point out here that 3 different conventional pathogenic particle types, PM10, asbestos and quartz, which cause diverse pathological effects, have been reported to cause very similar oxidative stress effects in cells in culture. We discuss the likely explanation and implications of this apparent paradox, and its relevance for testing in nanotoxicology.

  15. Standard Test Method for Stress-Corrosion of Titanium Alloys by Aircraft Engine Cleaning Materials

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2006-01-01

    1.1 This test method establishes a test procedure for determining the propensity of aircraft turbine engine cleaning and maintenance materials for causing stress corrosion cracking of titanium alloy parts. 1.2 The evaluation is conducted on representative titanium alloys by determining the effect of contact with cleaning and maintenance materials on tendency of prestressed titanium alloys to crack when subsequently heated to elevated temperatures. 1.3 Test conditions are based upon manufacturer's maximum recommended operating solution concentration. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see and .

  16. Acute heat stress induces differential gene expressions in the testes of a broiler-type strain of Taiwan country chickens.

    Directory of Open Access Journals (Sweden)

    Shih-Han Wang

    Full Text Available The expression of testicular genes following acute heat stress has been reported in layer-type roosters, but few similar studies have been conducted on broilers. This study investigated the effect of acute heat stress on the gene expression in the testes of a broiler-type strain of Taiwan country chickens. Roosters were subjected to acute heat stress (38°C for 4 h, and then exposed to 25°C, with testes collected 0, 2, and 6 h after the cessation of heat stress, using non-heat-stressed roosters as controls (n = 3 roosters per group. The body temperature and respiratory rate increased significantly (p<0.05 during the heat stress. The numbers of apoptotic cells increased 2 h after the acute heat stress (79 ± 7 vs. 322 ± 192, control vs. heat stress; p<0.05, which was earlier than the time of increase in layer-type roosters. Based on a chicken 44 K oligo microarray, 163 genes were found to be expressed significantly different in the testes of the heat-stressed chickens from those of the controls, including genes involved in the response to stimulus, protein metabolism, signal transduction, cell adhesion, transcription, and apoptosis. The mRNA expressions of upregulated genes, including HSP25, HSP90AA1, HSPA2, and LPAR2, and of downregulated genes, including CDH5, CTNNA3, EHF, CIRBP, SLA, and NTF3, were confirmed through quantitative real-time polymerase chain reaction (qRT-PCR. Moreover, numerous transcripts in the testes exhibited distinct expressions between the heat-stressed broiler-type and layer-type chickens. We concluded that the transcriptional responses of testes to acute heat stress may differ between the broiler-type and layer-type roosters. Whether the differential expression patterns associate with the heat-tolerance in the strains require a further exploration.

  17. Stress, Social Support, and Depression: A Test of the Stress-Buffering Hypothesis in a Mexican Sample

    Science.gov (United States)

    Raffaelli, Marcela; Andrade, Flavia C. D.; Wiley, Angela R.; Sanchez-Armass, Omar; Edwards, Laura L.; Aradillas-Garcia, Celia

    2013-01-01

    This study examined social support as a potential moderator between stress and depressive symptoms among Mexican university applicants aged 16--21 years ("N" = 6,715; "M" age = 17.9 years; 55% female). In bivariate analyses, perceived stress was associated with higher levels of depressive symptoms, and social support with lower…

  18. Estresse, ciclo reprodutivo e sensibilidade cardíaca às catecolaminas Stress, reproductive cycle and cardiac sensitivity to cathecolamines

    Directory of Open Access Journals (Sweden)

    Ana Paula Tanno

    2002-09-01

    íacas observadas na espécie humana após exposição à água e à natação.Stress is an organic answer to aversive stimulus or unknown situations to provide the adaptation of host to the new condition. The stressor can be a physical, chemical, emotional and social agent. Different stressors are present in human daily life and can be involved in degenerative diseases and lead to a fast aging process disturbing the body physiology. The main mediators of the stress reaction are the catecholamines (norepinephrine and epinephrine released by the sympathetic nervous system and by the adrenal medulla, and the glucocorticoids released by the adrenal cortex. The catecholamines and glucocorticoids act in the cells and tissues inducing adaptive changes in order to protect the organism and allow its survival. This response to stressors can be modified by the host and stressor characteristics. Among the host ones, age, gender, and in females, the reproductive cycle are relevant. The variations in the levels of sexual steroids estradiol and progesterone, related to the reproductive cycle, modulate the secretion of CRH, ACTH and glucocorticoids during the stress reaction and are involved in the different responses between men and women. Many studies have shown that the exposure to stressors may induce alterations in the sensitivity to catecholamines in the heart, which are related to adaptive processes. These alterations include changes in the activity of the metabolizing system of catecholamines, in the affinity or number of adrenoceptors, in the coupling between the receptor and G protein, and in enzymes mediating intracellular processes after the receptor activation. The study of these alterations may be helpful to the understanding of the cardiac effects of the water activities and swimming in humans.

  19. Estimation of In Situ Stress and Permeability from an Extended Leak-off Test

    Science.gov (United States)

    Nghiep Quach, Quoc; Jo, Yeonguk; Chang, Chandong; Song, Insun

    2016-04-01

    Among many parameters needed to analyze a variety of geomechanical problems related to subsurface CO2 storage projects, two important ones are in situ stress states and permeability of the storage reservoirs and cap rocks. In situ stress is needed for investigating potential risk of fault slip in the reservoir systems and permeability is needed for assessing reservoir flow characteristics and sealing capability of cap rocks. We used an extended leak-off test (XLOT), which is often routinely conducted to assess borehole/casing integrity as well as fracture gradient, to estimate both in situ least principal stress magnitude and in situ permeability in a CO2 storage test site, offshore southeast Korea. The XLOT was conducted at a casing shoe depth (700 m below seafloor) within the cap rock consisting of mudstone, approximately 50 m above the interface between cap rock and storage reservoir. The test depth was cement-grouted and remained for 4 days for curing. Then the hole was further drilled below the casing shoe to create a 4 m open-hole interval at the bottom. Water was injected using hydraulic pump at an approximately constant flowrate into the bottom interval through the casing, during which pressure and flowrate were recorded continuously at the surface. The interval pressure (P) was increased linearly with time (t) as water was injected. At some point, the slope of P-t curve deviated from the linear trend, which indicates leak-off. Pressure reached its peak upon formation breakdown, followed by a gradual pressure decrease. Soon after the formation breakdown, the hole was shut-in by pump shut-off, from which we determined the instantaneous shut-in pressure (ISIP). The ISIP was taken to be the magnitude of the in situ least principal stress (S3), which was determined to be 12.1 MPa. This value is lower than the lithostatic vertical stress, indicating that the S3 is the least horizontal principal stress. The determined S3 magnitude will be used to characterize the

  20. The role of loneliness and social support in adjustment to loss : a test of attachment versus stress theory

    NARCIS (Netherlands)

    Stroebe, W; Stroebe, M; Abakoumkin, G; Schut, H

    1996-01-01

    A longitudinal study of a matched sample of 60 recently widowed and 60 married men and women tested predictions from stress and attachment theory regarding the role of social support in adjustment to bereavement. Stress theory predicts a buffering effect, attributing the impact of bereavement on wel

  1. Stress Testing of the Montenegrin Banking System with Aggregated and Bank-Specific Data

    Directory of Open Access Journals (Sweden)

    Vuković Sanja

    2014-05-01

    Full Text Available There are many different approaches to the process of stress testing and two of them will be investigated in this paper. The first one is a stress test performed on aggregated data i.e. the banking system as a whole. The variable of interest in both exercises is the Loan Loss Provision ratio (hereinafter: the LLP. The main goal of the thesis is to find an answer to the following question: what are the macroeconomic variables that influence LLP the most and how will LLP, as a variable of interest, behave in a situation when all these variables were to experience negative performance at the same time? The resilience of the banking system to such scenario will be tested through the capital adequacy ratio. In order to find out more about the management practices of banks, microlevel data on banks were also used in the analysis. The focus was to see which of the variables are able to explain the LLP ratio for each bank individually and how is this information helpful for possible improvements in the banking sector. The relations between these variables will be able to explain some of the banks’ losses and some of the banks’ practices regarding credit activities. The analysis there will provide for some recommendations for the banks but also for the Central Bank and its way to influence the practices in the banking sector.

  2. EXPERT PANEL OVERSIGHT COMMITTEE ASSESSMENT OF FY2008 CORROSION AND STRESS CORROSION CRACKING SIMULANT TESTING PROGRAM

    Energy Technology Data Exchange (ETDEWEB)

    BOOMER KD

    2009-01-08

    The Expert Panel Oversight Committee (EPOC) has been overseeing the implementation of selected parts of Recommendation III of the final report, Expert Panel workshop for Hanford Site Double-Shell Tank Waste Chemistry Optimization, RPP-RPT-22126. Recommendation III provided four specific requirements necessary for Panel approval of a proposal to revise the chemistry control limits for the Double-Shell Tanks (DSTs). One of the more significant requirements was successful performance of an accelerated stress corrosion cracking (SCC) experimental program. This testing program has evaluated the optimization of the chemistry controls to prevent corrosion in the interstitial liquid and supernatant regions of the DSTs.

  3. Clinical perspectives and evidence of diastolic stress test in heart failure with preserved ejection fraction

    Directory of Open Access Journals (Sweden)

    Evgeny Belyavskiy

    2015-12-01

    Full Text Available The diagnosis of heart failure with preserved ejection fraction (HFPEF remains on the basis of echocardiographic analyses at rest. However, some patients with HFPEF have symptoms such as dyspnea only during exercise. Accordingly, echocardiographic analyses at rest could be insufficiently sensitive to identify these patients. In line, recent studies demonstrated that in some patients with HFPEF left ventricular diastolic abnormalities occur only during exercise. This review discusses and analyzes the clinical relevance and evidence of using diastolic stress test echocardiography in patients with HFPEF.

  4. Cardiac Calcification

    Directory of Open Access Journals (Sweden)

    Morteza Joorabian

    2011-05-01

    Full Text Available There is a spectrum of different types of cardiac"ncalcifications with the importance and significance"nof each type of cardiac calcification, especially"ncoronary artery calcification. Radiologic detection of"ncalcifications within the heart is quite common. The"namount of coronary artery calcification correlates"nwith the severity of coronary artery disease (CAD."nCalcification of the aortic or mitral valve may indicate"nhemodynamically significant valvular stenosis."nMyocardial calcification is a sign of prior infarction,"nwhile pericardial calcification is strongly associated"nwith constrictive pericarditis. A spectrum of different"ntypes of cardiac calcifications (linear, annular,"ncurvilinear,... could be seen in chest radiography and"nother imaging modalities. So a carful inspection for"ndetection and reorganization of these calcifications"nshould be necessary. Numerous modalities exist for"nidentifying coronary calcification, including plain"nradiography, fluoroscopy, intravascular ultrasound,"nMRI, echocardiography, and conventional, helical and"nelectron-beam CT (EBCT. Coronary calcifications"ndetected on EBCT or helical CT can be quantifie,"nand a total calcification score (Cardiac Calcification"nScoring may be calculated. In an asymptomatic"npopulation and/or patients with concomitant risk"nfactors like diabetes mellitus, determination of the"npresence of coronary calcifications identifies the"npatients at risk for future myocardial infarction and"ncoronary artery disease. In patients without coronary"ncalcifications, future cardiovascular events could"nbe excluded. Therefore, detecting and recognizing"ncalcification related to the heart on chest radiography"nand other imaging modalities such as fluoroscopy, CT"nand echocardiography may have important clinical"nimplications.

  5. The stress-corrosion behavior of Al-Li-Cu alloys: A comparison of test methods

    Science.gov (United States)

    Rizzo, P. P.; Galvin, R. P.; Nelson, H. G.

    1982-01-01

    Two powder metallurgy processed (Al-Li-Cu) alloys with and without Mg addition were studied in aqueous 3.5% NaCl solution during the alternate immersion testing of tuning fork specimens, slow crack growth tests using fracture mechanics specimens, and the slow strain rate testing of straining electrode specimens. Scanning electron microscopy and optical metallography were used to demonstrate the character of the interaction between the Al-Li-Cu alloys and the selected environment. Both alloys are susceptible to SC in an aqueous 3.5% NaCl solution under the right electrochemical and microstructural conditions. Each test method yields important information on the character of the SC behavior. Under all conditions investigated, second phase particles strung out in rows along the extrusion direction in the alloys were rapidly attacked, and played principal role in the SC process. With time, larger pits developed from these rows of smaller pits and under certain electrochemical conditions surface cracks initiated from the larger pits and contributed directly to the fracture process. Evidence to support slow crack growth was observed in both the slow strain rate tests and the sustained immersion tests of precracked fracture mechanics specimens. The possible role of H2 in the stress corrosion cracking process is suggested.

  6. Testing the Relationship between Human Occupancy in the Landscape and Tadpole Developmental Stress

    Science.gov (United States)

    Eterovick, Paula C.; Bar, Luís F. F.; Souza, Jorge B.; Castro, José F. M.; Leite, Felipe S. F.; Alford, Ross A.

    2015-01-01

    Amphibian population declines are widespread; the main causal factors are human related and include habitat fragmentation due to agriculture, mining, fires, and urban development. Brazil is the richest country in species of amphibians, and the Brazilian regions with the greatest amphibian diversity are experiencing relatively high rates of habitat destruction, but there are presently relatively few reports of amphibian declines. It is thus important to develop research methods that will detect deterioration in population health before severe declines occur. We tested the use of measurements of fluctuating asymmetry (FA) taken on amphibian larvae to detect anthropogenic stress. We hypothesized that greater human occupancy in the landscape might result in more stressful conditions for amphibians. We conducted this study at the Espinhaço mountain range in southeastern Brazil, using as a model an endemic species (Bokermannohyla saxicola, Hylidae). We chose two tadpole denticle rows and eye-nostril distance as traits for FA measurement. We measured percent cover of human-altered habitats in the landscape around tadpole sampling points and measured FA levels in sampled tadpoles. We found FA levels to differ among localities but found no relationship between human modification of the landscape and tadpole FA levels. Levels of FA in the traits we examined may not be strongly affected by environmental conditions, or may be affected by local variables that were not captured by our landscape-scale measures. Alternatively, populations may be genetically differentiated, affecting how FA levels respond to stress and obscuring the effects of anthropogenic disturbance. PMID:25793699

  7. Testing the relationship between human occupancy in the landscape and tadpole developmental stress.

    Directory of Open Access Journals (Sweden)

    Paula C Eterovick

    Full Text Available Amphibian population declines are widespread; the main causal factors are human related and include habitat fragmentation due to agriculture, mining, fires, and urban development. Brazil is the richest country in species of amphibians, and the Brazilian regions with the greatest amphibian diversity are experiencing relatively high rates of habitat destruction, but there are presently relatively few reports of amphibian declines. It is thus important to develop research methods that will detect deterioration in population health before severe declines occur. We tested the use of measurements of fluctuating asymmetry (FA taken on amphibian larvae to detect anthropogenic stress. We hypothesized that greater human occupancy in the landscape might result in more stressful conditions for amphibians. We conducted this study at the Espinhaço mountain range in southeastern Brazil, using as a model an endemic species (Bokermannohyla saxicola, Hylidae. We chose two tadpole denticle rows and eye-nostril distance as traits for FA measurement. We measured percent cover of human-altered habitats in the landscape around tadpole sampling points and measured FA levels in sampled tadpoles. We found FA levels to differ among localities but found no relationship between human modification of the landscape and tadpole FA levels. Levels of FA in the traits we examined may not be strongly affected by environmental conditions, or may be affected by local variables that were not captured by our landscape-scale measures. Alternatively, populations may be genetically differentiated, affecting how FA levels respond to stress and obscuring the effects of anthropogenic disturbance.

  8. Hypoxia Stress Test Reveals Exaggerated Cardiovascular Effects in Hypertensive Rats after Exposure to the Air Pollutant Acrolein

    Science.gov (United States)

    Exposure to air pollution increases the risk of cardiovascular morbidity and mortality, especially in susceptible populations with cardiovascular disease. Stress tests are useful in assessing cardiovascular risk and manifesting latent effects of exposure. The goal of this study w...

  9. A practical approach for the validation of sterility, endotoxin and potency testing of bone marrow mononucleated cells used in cardiac regeneration in compliance with good manufacturing practice

    Directory of Open Access Journals (Sweden)

    Gola Mauro

    2009-09-01

    Full Text Available Abstract Background Main scope of the EU and FDA regulations is to establish a classification criterion for advanced therapy medicinal products (ATMP. Regulations require that ATMPs must be prepared under good manufacturing practice (GMP. We have validated a commercial system for the determination of bacterial endotoxins in compliance with EU Pharmacopoeia 2.6.14, the sterility testing in compliance with EU Pharmacopoeia 2.6.1 and a potency assay in an ATMP constituted of mononucleated cells used in cardiac regeneration. Methods For the potency assay, cells were placed in the upper part of a modified Boyden chamber containing Endocult Basal Medium with supplements and transmigrated cells were scored. The invasion index was expressed as the ratio between the numbers of invading cells relative to cell migration through a control insert membrane. For endotoxins, we used a commercially available system based on the kinetic chromogenic LAL-test. Validation of sterility was performed by direct inoculation of TSB and FTM media with the cell product following Eu Ph 2.6.1 guideline. Results and discussion The calculated MVD and endotoxin limit were 780× and 39 EU/ml respectively. The 1:10 and 1:100 dilutions were selected for the validation. For sterility, all the FTM cultures were positive after 3 days. For TSB cultures, Mycetes and B. subtilis were positive after 5 and 3 days respectively. The detection limit was 1-10 colonies. A total of four invasion assay were performed: the calculated invasion index was 28.89 ± 16.82% (mean ± SD. Conclusion We have validated a strategy for endotoxin, sterility and potency testing in an ATMP used in cardiac regeneration. Unlike pharmaceutical products, many stem-cell-based products may originate in hospitals where personnel are unfamiliar with the applicable regulations. As new ATMPs are developed, the regulatory framework is likely to evolve. Meanwhile, existing regulations provide an appropriate structure for

  10. Acute heat stress induces differential gene expressions in the testes of a broiler-type strain of Taiwan country chickens.

    Science.gov (United States)

    Wang, Shih-Han; Cheng, Chuen-Yu; Tang, Pin-Chi; Chen, Chih-Feng; Chen, Hsin-Hsin; Lee, Yen-Pai; Huang, San-Yuan

    2015-01-01

    The expression of testicular genes following acute heat stress has been reported in layer-type roosters, but few similar studies have been conducted on broilers. This study investigated the effect of acute heat stress on the gene expression in the testes of a broiler-type strain of Taiwan country chickens. Roosters were subjected to acute heat stress (38°C) for 4 h, and then exposed to 25°C, with testes collected 0, 2, and 6 h after the cessation of heat stress, using non-heat-stressed roosters as controls (n = 3 roosters per group). The body temperature and respiratory rate increased significantly (pstress. The numbers of apoptotic cells increased 2 h after the acute heat stress (79 ± 7 vs. 322 ± 192, control vs. heat stress; pchicken 44 K oligo microarray, 163 genes were found to be expressed significantly different in the testes of the heat-stressed chickens from those of the controls, including genes involved in the response to stimulus, protein metabolism, signal transduction, cell adhesion, transcription, and apoptosis. The mRNA expressions of upregulated genes, including HSP25, HSP90AA1, HSPA2, and LPAR2, and of downregulated genes, including CDH5, CTNNA3, EHF, CIRBP, SLA, and NTF3, were confirmed through quantitative real-time polymerase chain reaction (qRT-PCR). Moreover, numerous transcripts in the testes exhibited distinct expressions between the heat-stressed broiler-type and layer-type chickens. We concluded that the transcriptional responses of testes to acute heat stress may differ between the broiler-type and layer-type roosters. Whether the differential expression patterns associate with the heat-tolerance in the strains require a further exploration.

  11. Molecular Aspects of Exercise-induced Cardiac Remodeling.

    Science.gov (United States)

    Bernardo, Bianca C; McMullen, Julie R

    2016-11-01

    Exercise-induced cardiac remodeling is typically an adaptive response associated with cardiac myocyte hypertrophy and renewal, increased cardiac myocyte contractility, sarcomeric remodeling, cell survival, metabolic and mitochondrial adaptations, electrical remodeling, and angiogenesis. Initiating stimuli/triggers of cardiac remodeling include increased hemodynamic load, increased sympathetic activity, and the release of hormones and growth factors. Prolonged and strenuous exercise may lead to maladaptive exercise-induced cardiac remodeling including cardiac dysfunction and arrhythmia. In addition, this article describes novel therapeutic approaches for the treatment of heart failure that target mechanisms responsible for adaptive exercise-induced cardiac remodeling, which are being developed and tested in preclinical models.

  12. Respiratory gating in cardiac PET

    DEFF Research Database (Denmark)

    Lassen, Martin Lyngby; Rasmussen, Thomas; Christensen, Thomas E

    2016-01-01

    of our study was to compare the resulting imaging quality by the use of a time-based respiratory gating system in two groups administered either adenosine or dipyridamole as the pharmacological stress agent. METHODS AND RESULTS: Forty-eight patients were randomized to adenosine or dipyridamole cardiac...... stress (82)RB-PET. Respiratory rates and depths were measured by a respiratory gating system in addition to registering actual respiratory rates. Patients undergoing adenosine stress showed a decrease in measured respiratory rate from initial to later scan phase measurements [12.4 (±5.7) vs 5.6 (±4......BACKGROUND: Respiratory motion due to breathing during cardiac positron emission tomography (PET) results in spatial blurring and erroneous tracer quantification. Respiratory gating might represent a solution by dividing the PET coincidence dataset into smaller respiratory phase subsets. The aim...

  13. Stress and coping in HIV-positive former plasma/blood donors in China: a test of cognitive appraisal theory.

    Science.gov (United States)

    Meade, Christina S; Wang, Jianping; Lin, Xiuyun; Wu, Hao; Poppen, Paul J

    2010-04-01

    Throughout the 1990s, many villagers in rural China were infected with HIV through commercial plasma/blood donation. These former plasma/blood donors (FPDs) experienced many HIV-related stressors. This study tested a cognitive appraisal model of stress and coping in a sample of HIV-positive adult FPDs. Participants (N = 207) from multiple villages completed a battery of questionnaires assessing HIV-related stress, HIV symptoms, cognitive appraisal, coping behaviors, and psychological distress. Participants reported high levels of HIV-related stress, depression, and anxiety. In a structural equation model, greater HIV-related stress, HIV symptoms, and threat appraisal were directly associated with psychological distress. HIV-related stress was also indirectly associated with psychological distress through threat appraisal. In a second model, coping was found to mediate the relationship between challenge appraisal and psychological distress. Results support the utility of cognitive appraisal theory. Stress management interventions targeting HIV-positive FPDs in China are indicated.

  14. Study on H2S stress corrosion test of welded joint for X65 pipeline steel and numerical analysis

    Institute of Scientific and Technical Information of China (English)

    金晓军; 霍立兴; 张玉凤; 白秉仁; 李晓巍; 曹军

    2004-01-01

    The susceptibility of welded joint for the X65 pipeline steel to H2S stress corrosion cracking (SCC) is investigated. SCC tests on the steel are carried out in the environment based on NACE TM-01-77 solution with saturated gaseous H2S. The threshold stress intensity factor and crack propagation velocity are calculated according to wedge-opening loading (WOL) specimens. The three-dimensional elastic-plastic finite element analysis of WOL specimens is performed by using the FEM programming package ANSYS. Stress field and concentration of hydrogen distribution property ahead of the crack tip are obtained. This paper surveyed the microstructure of welded joint and studied on the mechanical properties of X65 pipeline steel. It provides experimental basis for studying stress corrosion. The results of numerical analysis are consistent with conclusions of stress corrosion test.

  15. Exercise stress testing in healthy subjects during cholinergic stimulation after a single dose of pyridostigmine

    Directory of Open Access Journals (Sweden)

    Salvador M. Serra

    2001-04-01

    Full Text Available OBJETIVE: The evaluation, by exercise stress testing, of the cardiorespiratory effects of pyridostigmine (PYR, a reversible acetylcholinesterase inhibitor. METHODS: A double-blind, randomized, cross-over, placebo-controlled comparison of hemodynamic and ventilation variables of 10 healthy subjects who underwent three exercise stress tests (the first for adaptation and determination of tolerance to exercise, the other two after administration of placebo or 45mg of PYR. RESULTS: Heart rate at rest was: 68±3 vs 68±3bpm before and after placebo, respectively (P=0.38; 70±2 vs 59±2bpm, before and after pyridostigmine, respectively (P<0.01. During exercise, relative to placebo: a significantly lower heart rate after PYR at, respectively, 20% (P=0.02, 40% (P=0.03, 80% (P=0.05 and 100% (P=0.02 of peak effort was observed. No significant differences were observed in arterial blood pressure, oxygen consumption at submaximal and maximal effort, exercise duration, respiratory ratio, CO2 production, ventilation threshold, minute ventilation, and oxygen pulse. CONCLUSION: Pyridostigmine, at a dose of 45mg, decreases heart rate at rest and during exercise, with minimal side effects and without interfering with exercise tolerance and ventilation variables.

  16. Assessment of oxidative stress in serum by d-ROMs test.

    Science.gov (United States)

    Kilk, K; Meitern, R; Härmson, O; Soomets, U; Hõrak, P

    2014-08-01

    Assessment of oxidative stress is an important but technically challenging procedure in medical and biological research. The reactive oxygen metabolites (d-ROMs) test is a simple assay marketed for analyzing the total amount of hydroperoxides in serum via the Fenton's reaction. Earlier reports have raised a suspicion that a part of the signal detected in the assay comes from sources other than metabolites generated by oxidative stress. The aim of this study was to identify which serum components interfere with the d-ROMs signal. By application of sodium azide, ethylenediaminetetraacetic acid, sodium dodecylsulphate, varying temperature, and spiking endogenous substances we demonstrate that in the case of mammalian sera the assay determines ceruloplasmin (CP) activity with potential interferences from hydroperoxides, iron level, thiols, and albumin. In sera of avian species hydroperoxides contribute more to the test outcome, but the CP part is insensitive to inhibition by azide. In conclusion, this assay has deficiencies in terms of detecting realistic concentrations of hydroperoxides, is mostly measuring CP and is also interfered with other serum components, making it very difficult to interpret in most biological systems.

  17. Netherlands' National Fukushima Stress Test for the Borssele Nuclear Power Plant

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-12-15

    This is the National Report of the Kingdom of the Netherlands on the post-Fukushima 'stress test' of the Borssele (one unit) Nuclear Power Plant, the KCB. This report complies with the guidelines published by ENSREG (European Nuclear Safety Regulator Group) in May (objectives and scope) and October 2011 (structure of report) for National Reports. The operator of the KCB has submitted a Licensee Report to the regulatory body, that addresses all topics prescribed in the ENSREG guidelines for the 'stress test' and meets the prescribed format. The National Report presents conclusions about licensee's compliance with its design basis. The conclusions are based on the Licensee Report as well as on several decades of regulatory oversight, including regulatory inspections, evaluations of various applications for modification of the licences, regulatory control of the special Long-Term Operation programme and the various extensive Periodic Safety Reviews. The National Report presents conclusions on the safety margins identified in the Licensee Report. The National report notes the measures proposed and considered in the Licensee Report. In principle, the regulatory body can endorse various of these measures, but further assessment is needed to establish the effectiveness of these. The regulatory body proposes additional topics suitable for (more detailed) assessment.

  18. Semiautomatic validation of RR time series in an ECG stress test database

    Science.gov (United States)

    Armijos, Jairo; García, David; Astudillo, Darwin; Palacio-Baus, Kenneth; Medina, Rubén.; Wong, Sara

    2015-12-01

    This paper reports an automatic method for characterizing the quality of the RR-time series in the stress test database known as DICARDIA. The proposed methodology is simple and consists in subdividing the RR time series in a set of windows for estimating the quantity of artifacts based on a threshold value that depends on the standard deviation of RR-time series for each recorded lead. In a first stage, a manual annotation was performed considering four quality classes for the RR-time series (Reference lead, Good Lead, Low Quality Lead and Useless Lead). Automatic annotation was then performed varying the number of windows and threshold value for the standard deviation of the RR-time series. The metric used for evaluating the quality of the annotation was the Matching Ratio. The best results were obtained using a higher number of windows and considering only three classes (Good Lead, Low Quality Lead and Useless). The proposed methodology allows the utilization of the online available DICARDIA Stress Test database for different types of research.

  19. The Application of Stress-Relaxation Test to Life Assessment of T911/T22 Weld Metal

    Science.gov (United States)

    Cao, Tieshan; Zhao, Jie; Cheng, Congqian; Li, Huifang

    2016-03-01

    A dissimilar weld metal was obtained through submerged arc welding of a T911 steel to a T22 steel, and its creep property was explored by stress-relaxation test assisted by some conventional creep tests. The creep rate information of the stress-relaxation test was compared to the minimum and the average creep rates of the conventional creep test. Log-log graph showed that the creep rate of the stress-relaxation test was in a linear relationship with the minimum creep rate of the conventional creep test. Thus, the creep rate of stress-relaxation test could be used in the Monkman-Grant relation to calculate the rupture life. The creep rate of the stress-relaxation test was similar to the average creep rate, and thereby the rupture life could be evaluated by a method of "time to rupture strain." The results also showed that rupture life which was assessed by the Monkman-Grant relation was more accurate than that obtained through the method of "time to rupture strain."

  20. Will sacubitril-valsartan diminish the clinical utility of B-type natriuretic peptide testing in acute cardiac care?

    DEFF Research Database (Denmark)

    Mair, Johannes; Lindahl, Bertil; Giannitsis, Evangelos;

    2016-01-01

    Since the approval of sacubitril-valsartan for the treatment of chronic heart failure with reduced ejection fraction, a commonly raised suspicion is that a wider clinical use of this new drug may diminish the clinical utility of B-type natriuretic peptide testing as sacubitril may interfere with B...

  1. Effect of degree of lipomobilization on results of glucose test in dairy cows in heat stress

    Directory of Open Access Journals (Sweden)

    Cincović M.R.

    2012-01-01

    Full Text Available Cows exposed to heat stress exhibit a decreased ability to mobilize lipids due to increased sensitivity to insulin, which is expressed in a decreased concentration of NEFA. However, certain cows can preserve the level of lipid mobilization after adapting to heat stress. We assumed that cows that have a preserved ability to mobilize lipids are less sensitive to insulin and that they have a lower tolerance for glucose. The aim of this work was to compare the results of an intravenous glucose tolerance test in cows that exhibited, in prolonged heat stress, a decreased (NEFA0.30 mmol/l ability for lipid mobilization. Glucose concentration and NEFA concentration were measured following intravenous application of glucose. The mean glycaemic index value did not differ statistically significantly between the two groups of cows at 10, 15 and 20 minutes after glucose application (p>0.05, but there was a tendency at 10 and 15 minutes for the glycaemia to be higher in cows with preserved lipomobilization (p<0.1. At 30, 60 and 90 minutes after glucose application, glycaemia was statistically significantly higher (p<0.01; p<0.05 and p<0.05 in the group of cows with preserved lipomobilization. The glycaemic index values (mmol/l shown in the same order (30, 60 and 90 minutes were as follows 9.91±0.21: 9.23±0.41; 5.41±0.5: 4.67±0.33 and 4.31±0.39: 3.47±0.37. The mean value for NEFA concentration in samples originating from the two experimental groups of cows did not differ statistically significantly following glucose application. The NEFA concentration showed a tendency to be higher in cows with preserved lipid mobilization in comparison with cows with decreased lipomobilization at 20 and 30 minutes after glucose application (p<0.1. Following the intravenous glucose tolerance test, NEFA and glucose concentrations were in a significant negative correlation, and that correlation was more expressed in cows with decreased lipomobilization. Cows with preserved

  2. The Implicit Positive and Negative Affect Test: Validity and Relationship with Cardiovascular Stress-Responses.

    Science.gov (United States)

    van der Ploeg, Melanie M; Brosschot, Jos F; Thayer, Julian F; Verkuil, Bart

    2016-01-01

    Self-report, i.e., explicit, measures of affect cannot fully explain the cardiovascular (CV) responses to stressors. Measuring affect beyond self-report, i.e., using implicit measures, could add to our understanding of stress-related CV activity. The Implicit Positive and Negative Affect Test (IPANAT) was administered in two studies to test its ecological validity and relation with CV responses and self-report measures of affect. In Study 1 students (N = 34) viewed four film clips inducing anger, happiness, fear, or no emotion, and completed the IPANAT and the Positive And Negative Affect Scale at baseline and after each clip. Implicit negative affect (INA) was higher and implicit positive affect (IPA) was lower after the anger inducing clip and vice versa after the happiness inducing clip. In Study 2 students performed a stressful math task with (n = 14) or without anger harassment (n = 15) and completed the IPANAT and a Visual Analog Scale as an explicit measure afterwards. Systolic (SBP), diastolic (DBP) blood pressure, heart rate (HR), heart rate variability (HRV), and total peripheral resistance (TPR) were recorded throughout. SBP and DBP were higher and TPR was lower in the harassment condition during the task with a prolonged effect on SBP and DBP during recovery. As expected, explicit negative affect (ENA) was higher and explicit positive affect (EPA) lower after harassment, but ENA and EPA were not related to CV activity. Although neither INA nor IPA differed between the tasks, during both tasks higher INA was related to higher SBP, lower HRV and lower TPR and to slower recovery of DBP after both tasks. Low IPA was related to slower recovery of SBP and DBP after the tasks. Implicit affect was not related to recovery of HR, HRV, and TPR. In conclusion, the IPANAT seems to respond to film clip-induced negative and positive affect and was related to CV activity during and after stressful tasks. These findings support the theory that implicitly measured affect

  3. Effects of Adiponectin on Cell Oxidative Stress and Apoptosis in Human Cardiac Myocytes Cultured with High Glucose%脂联素对高糖环境心肌细胞氧化应激及凋亡的影响

    Institute of Scientific and Technical Information of China (English)

    李美蓉; 李兴

    2012-01-01

    Objective To establish a myocardial cell oxidative stress model by cultivating human cardiac myocytes (HCM) in a high glucose environment, and to observe if there is a protective role of adiponectin (ADPN) on the oxidative stress and apoplosis of myocardial cells, and reveals the protection mechanism of the adiponectin. Methods The in vitro cultured HCM were divided into three groups;the control group, high glucose group, high glucose + adiponectin group, and these cells were cultured 24, 48, 72hours respectively. Then we observed the morphological change of the HCM under the inverted microscope and evaluated the level of superoxide dis-mutase ( SOD) by the xanthineoxidase method. The level of malondialdehyde ( MDA) was detected by benzodiazepines acid method. The expression of adaptin ( P66Shc) and heme oxygenase - 1 ( Ho - 1) in three time points was detected by real - time PCR, and the apoptosis rate of the HCM was tested by the flow cytometry. Results Our findings showed significant increase of MDA levels (P <0.05) and decrease of SOD activity(P<0.05) in the high glucose group compared with the control group. However,in the adiponectin group,MDA levels decreased (P<0.05) and SOD activity increased significantly (P <0.05) compared with those in the high - glucose group and they were time dependent. Compared with the control group,the expression of Ho-1 mRNA and P66Shc mRNA increased in the high -glucose group. The adiponectin group expressed a higher level of Ho - 1 mRNA but a lower level of P66Shc mRNA compared with the glucose group (P < 0.05) and they were time dependent. The apoptosis rate of the HCM in the high - glucose group was higher than the control group; while the apoptotic rate in the adiponectin group declined remarkably compared with the high glucose group. Conclusion The adiponectin has a protective effect on diabetes myocardial cells by upregulating the expression of Ho - 1 mRNA and downregulating the expression of P66Shc mRNA, which can

  4. Lifetime Prediction for Degradation of Solar Mirrors using Step-Stress Accelerated Testing (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J.; Elmore, R.; Kennedy, C.; Gray, M.; Jones, W.

    2011-09-01

    This research is to illustrate the use of statistical inference techniques in order to quantify the uncertainty surrounding reliability estimates in a step-stress accelerated degradation testing (SSADT) scenario. SSADT can be used when a researcher is faced with a resource-constrained environment, e.g., limits on chamber time or on the number of units to test. We apply the SSADT methodology to a degradation experiment involving concentrated solar power (CSP) mirrors and compare the results to a more traditional multiple accelerated testing paradigm. Specifically, our work includes: (1) designing a durability testing plan for solar mirrors (3M's new improved silvered acrylic "Solar Reflector Film (SFM) 1100") through the ultra-accelerated weathering system (UAWS), (2) defining degradation paths of optical performance based on the SSADT model which is accelerated by high UV-radiant exposure, and (3) developing service lifetime prediction models for solar mirrors using advanced statistical inference. We use the method of least squares to estimate the model parameters and this serves as the basis for the statistical inference in SSADT. Several quantities of interest can be estimated from this procedure, e.g., mean-time-to-failure (MTTF) and warranty time. The methods allow for the estimation of quantities that may be of interest to the domain scientists.

  5. Research on friction coefficient of nuclear Reactor Vessel Internals Hold Down Spring: Stress coefficient test analysis method

    Energy Technology Data Exchange (ETDEWEB)

    Linjun, Xie, E-mail: linjunx@zjut.edu.cn [College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou 310014 (China); Guohong, Xue; Ming, Zhang [Shanghai Nuclear Engineering Research & Design Institute, Shanghai 200233 (China)

    2016-08-01

    Graphical abstract: HDS stress coefficient test apparatus. - Highlights: • This paper performs mathematic deduction to the physical model of Hold Down Spring (HDS), establishes a mathematic model of axial load P and stress, stress coefficient and friction coefficient and designs a set of test apparatuses for simulating the pretightening process of the HDS for the first time according to a model similarity criterion. • The mathematical relation between the load and the strain is obtained about the HDS, and the mathematical model of the stress coefficient and the friction coefficient is established. So, a set of test apparatuses for obtaining the stress coefficient is designed according to the model scaling criterion and the friction coefficient of the K1000 HDS is calculated to be 0.336 through the obtained stress coefficient. • The relation curve between the theoretical load and the friction coefficient is obtained through analysis and indicates that the change of the friction coefficient f would influence the pretightening load under the condition of designed stress. The necessary pretightening load in the design process is calculated to be 5469 kN according to the obtained friction coefficient. Therefore, the friction coefficient and the pretightening load under the design conditions can provide accurate pretightening data for the analysis and design of the reactor HDS according to the operations. - Abstract: This paper performs mathematic deduction to the physical model of Hold Down Spring (HDS), establishes a mathematic model of axial load P and stress, stress coefficient and friction coefficient and designs a set of test apparatuses for simulating the pretightening process of the HDS for the first time according to a model similarity criterion. By carrying out tests and researches through a stress testing technique, P–σ curves in loading and unloading processes of the HDS are obtained and the stress coefficient k{sub f} of the HDS is obtained. So, the

  6. How integrated are behavioral and endocrine stress response traits? A repeated measures approach to testing the stress-coping style model.

    Science.gov (United States)

    Boulton, Kay; Couto, Elsa; Grimmer, Andrew J; Earley, Ryan L; Canario, Adelino V M; Wilson, Alastair J; Walling, Craig A

    2015-02-01

    It is widely expected that physiological and behavioral stress responses will be integrated within divergent stress-coping styles (SCS) and that these may represent opposite ends of a continuously varying reactive-proactive axis. If such a model is valid, then stress response traits should be repeatable and physiological and behavioral responses should also change in an integrated manner along a major axis of among-individual variation. While there is some evidence of association between endocrine and behavioral stress response traits, few studies incorporate repeated observations of both. To test this model, we use a multivariate, repeated measures approach in a captive-bred population of Xiphophorus birchmanni. We quantify among-individual variation in behavioral stress response to an open field trial (OFT) with simulated predator attack (SPA) and measure waterborne steroid hormone levels (cortisol, 11-ketotestosterone) before and after exposure. Under the mild stress stimulus (OFT), (multivariate) behavioral variation among individuals was consistent with a strong axis of personality (shy-bold) or coping style (reactive-proactive) variation. However, behavioral responses to a moderate stressor (SPA) were less repeatable, and robust statistical support for repeatable endocrine state over the full sampling period was limited to 11-ketotestosterone. Although post hoc analysis suggested cortisol expression was repeatable over short time periods, qualitative relationships between behavior and glucocorticoid levels were counter to our a priori expectations. Thus, while our results clearly show among-individual differences in behavioral and endocrine traits associated with stress response, the correlation structure between these is not consistent with a simple proactive-reactive axis of integrated stress-coping style. Additionally, the low repeatability of cortisol suggests caution is warranted if single observations (or indeed repeat measures over short sampling

  7. Cardiac nuclear medicine

    Energy Technology Data Exchange (ETDEWEB)

    Gerson, M.C.

    1987-01-01

    The book begins with a review of the radionuclide methods available for evaluating cardiac perfusion and function. The authors discuss planar and tomographic thallium myocardial imaging, first-pass and equilibrium radionuclide angiography, and imaging with infarct-avid tracers. Several common but more specialized procedures are then reviewed: nonogemetric measurement of left ventricular volume, phase (Fourier) analysis, stroke volume ratio, right ventricular function, and diastolic function. A separate chapter is devoted to drug interventions and in particular the use of radionuclide ventriculography to monitor doxorubicin toxicity and therapy of congestive heart failure. The subsequent chapters provide a comprehensive guide to test selection, accuracy, and results in acute myocardial infarction, in postmyocardial infarction, in chronic coronary artery disease, before and after medical or surgical revascularization, in valvular heart disease, in cardiomyopathies, and in cardiac trauma.

  8. Is there a future for neuroprotective agents in cardiac surgery?

    NARCIS (Netherlands)

    van den Bergh, Walter M

    2010-01-01

    This article gives an overview of neuroprotective drugs that were recently tested in clinical trials in cardiac surgery. Also, recommendations are given for successful translational research and considerations for management during cardiac surgery.

  9. Phosphatidylinositol-bisphosphate regulates intercellular coupling in cardiac myocytes

    DEFF Research Database (Denmark)

    Hofgaard, Johannes P; Banach, Kathrin; Mollerup, Sarah

    2008-01-01

    Changes in the lipid composition of cardiac myocytes have been reported during cardiac hypertrophy, cardiomyopathy, and infarction. Because a recent study indicates a relation between low phosphatidylinositol-bisphosphate (PIP(2)) levels and reduced intercellular coupling, we tested the hypothesi...

  10. Characterization of swine stress gene by DNA testing using plucked hair as a source of DNA

    Directory of Open Access Journals (Sweden)

    Bastos Reginaldo Gaspar

    2000-01-01

    Full Text Available The swine stress gene (hal in recessive homozygotes (nn leads to porcine stress syndrome (PSS, and is associated with pale, soft, exudative pork (PSE. In heterozygosis (Nn it is linked to poor carcass quality. A total of 179 pigs (86 Large White, 69 Landrace, 12 Duroc and 12 Pietrain were characterized as normal homozygotes (NN, heterozygotes or recessive homozygotes following amplification of a target region of the hal gene using the polymerase chain reaction (PCR, followed by a restriction endonuclease assay. Plucked hair was used as a source of genomic DNA. The resulting PCR was digested with the restriction enzyme CfoI, followed by agarose gel electrophoresis. Of 179 animals tested, 70% were NN, 28% were Nn, and 2% were nn. The frequency of heterozygotes was higher (P < 0.05 in Landrace (0.43 for Nn than in Large White pigs (0.09 for Nn. Nine of the 12 Pietrain animals were Nn and three were nn, suggesting a high frequency for the n allele in this breed. These results may be related to the incidence of PSS and PSE in these two breeds, both of which are widely used in breeding programs. The utilization of plucked hair as the source of genomic DNA was a non-invasive and quick method to screen farm animals.

  11. Material Properties Test to Determine Ultimate Strain and True Stress-True Strain Curves for High Yield Steels

    Energy Technology Data Exchange (ETDEWEB)

    K.R. Arpin; T.F. Trimble

    2003-04-01

    This testing was undertaken to develop material true stress-true strain curves for elastic-plastic material behavior for use in performing transient analysis. Based on the conclusions of this test, the true stress-true strain curves derived herein are valid for use in elastic-plastic finite element analysis for structures fabricated from these materials. In addition, for the materials tested herein, the ultimate strain values are greater than those values cited as the limits for the elastic-plastic strain acceptance criteria for transient analysis.

  12. Strategy for a Rock Mechanics Site Descriptive Model. Development and testing of an approach to modelling the state of stress

    Energy Technology Data Exchange (ETDEWEB)

    Hakami, Eva; Hakami, Hossein [Itasca Geomekanik AB, Solna (Sweden); Cosgrove, John [Imperial College of Science and Technology, London (United Kingdom)

    2002-05-01

    The overall objective of this project has been to develop, test and establish a method for creating a Rock Mechanics Site Descriptive Model for a site considered in the site investigation programme. The work was divided into three parts, the empirical and theoretical 'property models' and the 'stress model'. The work on the stress model is presented in this report. The work consisted of i) a literature review about geological factors controlling in situ stress and a review about the use of numerical models for this subject, ii) the development of recommendations on the methodology to be applied during a site investigation and iii) the Test Case exercise, where the suggested methods were tested. The main mechanism controlling the in situ stress magnitudes in Sweden is plate tectonics causing the stress field to show similarities in most parts of north-western Europe, having a NW-SE trend of the maximum principal stress. The orientation of the stress field is largely determined by the relative movements by the plates. However, the stress orientation may also be influenced by the presence of large regional weak zones, such as the Tornquist deformation zone that lies between Sweden and Denmark. The strike of the Tornquist deformation zone is parallel to the maximum principal stress as observed in central and southern Sweden. The magnitude of the stress is more difficult to estimate, but the general pattern is an increase in magnitude with depth, at least for the upper kilometres. To determine the stress magnitude at a certain site and depth, with reasonable certainty, stress measurement should be used. A methodology for building a stress model has been proposed. It involves different steps starting with a preliminary stress estimation, followed by steps for interpreting site-specific information. If the stress pattern and structural geology of the site are complex, including major fracture zones intersecting the area, numerical analyses of the

  13. Sign restriction approach to macro stress-testing of the Croatian banking system

    Directory of Open Access Journals (Sweden)

    Nataša Erjavec

    2012-12-01

    Full Text Available The paper employs Uhlig’s sign restriction approach to stress-testing of the Croatian banking system. The analysis is based on a standard monetary VAR comprising real economic activity, inflation and short-term interest rates augmented by the ratio of non-performing loans or return on average equity, both measures representing the aggregate banking sector. In spite of the selected indicator, the results suggest a strong sensitivity of the Croatian banking sector to macroeconomic shocks. The effects are the strongest for contractionary monetary policy shocks, followed by negative demand shocks while the effects of supply shocks turned out to be statistically insignificant. Since Croatia is a small open economy with banking the dominant financial sector, the results obtained could be interesting for policy makers in Croatia and other transition economies with similar characteristics.

  14. The Effects of Maternal Opium Abuse on Fetal Heart Rate using Non-Stress Test

    Science.gov (United States)

    Keikha, Fatemeh; Vahdani, Fahimeh Ghotbizadeh; Latifi, Sahar

    2016-01-01

    Background: Opium is one of the most commonly abused opiates in developing countries including Iran. Considering the importance of maternal health on the newborn, we aimed to assess the effect of opium abuse on fetal heart rate (FHR) characteristics in a sample of pregnant women in Zahedan, Southeast Iran. Methods: This cross-sectional study was done on 100 pregnant women referring to Ali-Ibn-Abi Talib Hospital in Zahedan, during 2011-2013. The participants were divided into two groups comprising of opium abusers and healthy individuals. The participants received 500cc intravenous fluid containing dextrose and then non-stress test results were recorded for 20 minutes. Results: We found no significant difference between the two groups with respect to their demographic characteristics. Fetal movements, variability, acceleration, and reactivity were significantly higher among addicted women (Pabusers compared with the healthy women. Abnormal variability or oscillations of addicted mothers (Pabuser group, mothers addicted to opium need specific prenatal care. PMID:27853327

  15. THE METHOD OF CONSTRUCTING MODELS OF STRESS-TESTING OF THE TRADING PORTFOLIO OF FINANCIAL ORGANIZATIONS

    Directory of Open Access Journals (Sweden)

    Alimbaev Farkhad

    2009-11-01

    Full Text Available The financial crisis gave an impetus to finding “weaknesses” in financial institutions. One such tool is the stress-testing. This method is intended to identify through modeling “hypothetical” or “historical” scenarios, the most losses, in the execution of a script. In the simulation of hypothetical scenarios to find the impact factor, as shock events on the trade portfolio. When using historical scenarios, as the shocks applied developments in the past that have caused catastrophic losses, both in quantitative and qualitative size. For example, such scenarios can be: financial crises of the 90-ies and the current decline in international stock markets, a drop or increase in foreign exchange rates, etc.

  16. Stress testing on silicon carbide electronic devices for prognostics and health management.

    Energy Technology Data Exchange (ETDEWEB)

    Kaplar, Robert James; Brock, Reinhard C.; Marinella, Matthew; King, Michael Patrick; Smith, Mark A.; Atcitty, Stanley

    2011-01-01

    Power conversion systems for energy storage and other distributed energy resource applications are among the drivers of the important role that power electronics plays in providing reliable electricity. Wide band gap semiconductors such as silicon carbide (SiC) and gallium nitride (GaN) will help increase the performance and efficiency of power electronic equipment while condition monitoring (CM) and prognostics and health management (PHM) will increase the operational availability of the equipment and thereby make it more cost effective. Voltage and/or temperature stress testing were performed on a number of SiC devices in order to accelerate failure modes and to identify measureable shifts in electrical characteristics which may provide early indication of those failures. Those shifts can be interpreted and modeled to provide prognostic signatures for use in CM and/or PHM. Such experiments will also lead to a deeper understanding of basic device physics and the degradation mechanisms behind failure.

  17. Stress corrosion cracking of alloy 600 using the constant strain rate test

    Energy Technology Data Exchange (ETDEWEB)

    Bulischeck, T. S.; van Rooyen, D.

    1980-01-01

    The most recent corrosion problems experienced in nuclear steam generators tubed with Inconel alloy 600 is a phenomenon labeled ''denting''. Denting has been found in various degrees of severity in many operating pressurized water reactors. Laboratory investigations have shown that Inconel 600 exhibits intergranular SCC when subjected to high stresses and exposed to deoxygenated water at elevated temperatures. A research project was initiated at Brookhaven National Laboratory in an attempt to improve the qualitative and quantitative understanding of factors influencing SCC in high temperature service-related environments. An effort is also being made to develop an accelerated test method which could be used to predict the service life of tubes which have been deformed or are actively denting. Several heats of commercial Inconel 600 tubing were procured for testing in deaerated pure and primary water at temperatures from 290 to 365/sup 0/C. U-bend type specimens were used to determine crack initiation times which may be expected for tubes where denting has occurred but is arrested and provide baseline data for judging the accelerating effects of the slow strain rate method. Constant extension rate tests were employed to determine the crack velocities experienced in the crack propagation stage and predict failure times of tubes which are actively denting. 8 refs., 17 figs., 5 tabs.

  18. Extremely Low-Stress Triaxiality Tests in Calibration of Fracture Models in Metal-Cutting Simulation

    Science.gov (United States)

    Šebek, František; Kubík, Petr; Petruška, Jindřich; Hůlka, Jiří

    2016-11-01

    The cutting process is now combined with machining, milling, or drilling as one of the widespread manufacturing operations. It is used across various fields of engineering. From an economical point of view, it is desirable to maintain the process in the most effective way in terms of the fracture surface quality or minimizing the burr. It is not possible to manage this experimentally in mass production. Therefore, it is convenient to use numerical computation. To include the crack initiation and propagation in the computations, it is necessary to implement a suitable ductile fracture criterion. Uncoupled ductile fracture models need to be calibrated first from fracture tests when the test selection is crucial. In the present article, there were selected widespread uncoupled ductile fracture models calibrated with, among others, an extremely low-stress triaxiality test realized through the compression of a cylinder with a specific recess. The whole experimental program together with the cutting process experiment were carried out on AISI 1045 carbon steel. After the fracture models were calibrated and the cutting process was simulated with their use, fracture surfaces and force responses from computations were compared with those experimentally obtained and concluding remarks were made.

  19. Comparison of myocardial ischemia during intense mental stress using flight simulation in airline pilots with coronary artery disease to that produced with conventional mental and treadmill exercise stress testing.

    Science.gov (United States)

    Doorey, Andrew; Denenberg, Barry; Sagar, Vidya; Hanna, Tracy; Newman, Jack; Stone, Peter H

    2011-09-01

    Mental stress increases cardiovascular morbidity and mortality. Although laboratory mental stress often causes less myocardial ischemia than exercise stress (ES), it is unclear whether mental stress is intrinsically different or differences are due to less hemodynamic stress with mental stress. We sought to evaluate the hemodynamic and ischemic response to intense realistic mental stress created by modern flight simulators and compare this response to that of exercise treadmill testing and conventional laboratory mental stress (CMS) testing in pilots with coronary disease. Sixteen airline pilots with angiographically documented coronary disease and documented myocardial ischemia during ES were studied using maximal treadmill ES, CMS, and aviation mental stress (AMS) testing. AMS testing was done in a sophisticated simulator using multiple system failures as stressors. Treadmill ES testing resulted in the highest heart rate, but AMS caused a higher blood pressure response than CMS. Maximal rate-pressure product was not significantly different between ES and AMS (25,646 vs 23,347, p = 0.08), although these were higher than CMS (16,336, p mental stress compared to ES do not appear to be due to the creation of less hemodynamic stress. In conclusion, even with equivalent hemodynamic stress, intense realistic mental stress induced by flight simulators results in significantly less myocardial ischemia than ES as measured by ST-segment depression and nuclear ischemia.

  20. Technology-Enabled Remote Monitoring and Self-Management — Vision for Patient Empowerment Following Cardiac and Vascular Surgery: User Testing and Randomized Controlled Trial Protocol

    Science.gov (United States)

    Yost, Jennifer; Turner, Andrew; Bender, Duane; Scott, Ted; Carroll, Sandra; Ritvo, Paul; Peter, Elizabeth; Lamy, Andre; Furze, Gill; Krull, Kirsten; Dunlop, Valerie; Good, Amber; Dvirnik, Nazari; Bedini, Debbie; Naus, Frank; Pettit, Shirley; Henry, Shaunattonie; Probst, Christine; Mills, Joseph; Gossage, Elaine; Travale, Irene; Duquette, Janine; Taberner, Christy; Bhavnani, Sanjeev; Khan, James S; Cowan, David; Romeril, Eric; Lee, John; Colella, Tracey; Choinière, Manon; Busse, Jason; Katz, Joel; Victor, J Charles; Hoch, Jeffrey; Isaranuwatchai, Wanrudee; Kaasalainen, Sharon; Ladak, Salima; O'Keefe-McCarthy, Sheila; Parry, Monica; Sessler, Daniel I; Stacey, Michael; Stevens, Bonnie; Stremler, Robyn; Thabane, Lehana; Watt-Watson, Judy; Whitlock, Richard; MacDermid, Joy C; Leegaard, Marit; McKelvie, Robert; Hillmer, Michael; Cooper, Lynn; Arthur, Gavin; Sider, Krista; Oliver, Susan; Boyajian, Karen; Farrow, Mark; Lawton, Chris; Gamble, Darryl; Walsh, Jake; Field, Mark; LeFort, Sandra; Clyne, Wendy; Ricupero, Maria; Poole, Laurie; Russell-Wood, Karsten; Weber, Michael; McNeil, Jolene; Alpert, Robyn; Sharpe, Sarah; Bhella, Sue; Mohajer, David; Ponnambalam, Sem; Lakhani, Naeem; Khan, Rabia; Liu, Peter

    2016-01-01

    Background Tens of thousands of cardiac and vascular surgeries (CaVS) are performed on seniors in Canada and the United Kingdom each year to improve survival, relieve disease symptoms, and improve health-related quality of life (HRQL). However, chronic postsurgical pain (CPSP), undetected or delayed detection of hemodynamic compromise, complications, and related poor functional status are major problems for substantial numbers of patients during the recovery process. To tackle this problem, we aim to refine and test the effectiveness of an eHealth-enabled service delivery intervention, TecHnology-Enabled remote monitoring and Self-MAnagemenT—VIsion for patient EmpoWerment following Cardiac and VasculaR surgery (THE SMArTVIEW, CoVeRed), which combines remote monitoring, education, and self-management training to optimize recovery outcomes and experience of seniors undergoing CaVS in Canada and the United Kingdom. Objective Our objectives are to (1) refine SMArTVIEW via high-fidelity user testing and (2) examine the effectiveness of SMArTVIEW via a randomized controlled trial (RCT). Methods CaVS patients and clinicians will engage in two cycles of focus groups and usability testing at each site; feedback will be elicited about expectations and experience of SMArTVIEW, in context. The data will be used to refine the SMArTVIEW eHealth delivery program. Upon transfer to the surgical ward (ie, post-intensive care unit [ICU]), 256 CaVS patients will be reassessed postoperatively and randomly allocated via an interactive Web randomization system to the intervention group or usual care. The SMArTVIEW intervention will run from surgical ward day 2 until 8 weeks following surgery. Outcome assessments will occur on postoperative day 30; at week 8; and at 3, 6, 9, and 12 months. The primary outcome is worst postop pain intensity upon movement in the previous 24 hours (Brief Pain Inventory-Short Form), averaged across the previous 14 days. Secondary outcomes include a

  1. Evaluation of the channelized Hotelling observer with an internal-noise model in a train-test paradigm for cardiac SPECT defect detection

    Science.gov (United States)

    Brankov, Jovan G.

    2013-10-01

    The channelized Hotelling observer (CHO) has become a widely used approach for evaluating medical image quality, acting as a surrogate for human observers in early-stage research on assessment and optimization of imaging devices and algorithms. The CHO is typically used to measure lesion detectability. Its popularity stems from experiments showing that the CHO's detection performance can correlate well with that of human observers. In some cases, CHO performance overestimates human performance; to counteract this effect, an internal-noise model is introduced, which allows the CHO to be tuned to match human-observer performance. Typically, this tuning is achieved using example data obtained from human observers. We argue that this internal-noise tuning step is essentially a model training exercise; therefore, just as in supervised learning, it is essential to test the CHO with an internal-noise model on a set of data that is distinct from that used to tune (train) the model. Furthermore, we argue that, if the CHO is to provide useful insights about new imaging algorithms or devices, the test data should reflect such potential differences from the training data; it is not sufficient simply to use new noise realizations of the same imaging method. Motivated by these considerations, the novelty of this paper is the use of new model selection criteria to evaluate ten established internal-noise models, utilizing four different channel models, in a train-test approach. Though not the focus of the paper, a new internal-noise model is also proposed that outperformed the ten established models in the cases tested. The results, using cardiac perfusion SPECT data, show that the proposed train-test approach is necessary, as judged by the newly proposed model selection criteria, to avoid spurious conclusions. The results also demonstrate that, in some models, the optimal internal-noise parameter is very sensitive to the choice of training data; therefore, these models are prone

  2. Evaluation of the channelized Hotelling observer with an internal-noise model in a train-test paradigm for cardiac SPECT defect detection.

    Science.gov (United States)

    Brankov, Jovan G

    2013-10-21

    The channelized Hotelling observer (CHO) has become a widely used approach for evaluating medical image quality, acting as a surrogate for human observers in early-stage research on assessment and optimization of imaging devices and algorithms. The CHO is typically used to measure lesion detectability. Its popularity stems from experiments showing that the CHO's detection performance can correlate well with that of human observers. In some cases, CHO performance overestimates human performance; to counteract this effect, an internal-noise model is introduced, which allows the CHO to be tuned to match human-observer performance. Typically, this tuning is achieved using example data obtained from human observers. We argue that this internal-noise tuning step is essentially a model training exercise; therefore, just as in supervised learning, it is essential to test the CHO with an internal-noise model on a set of data that is distinct from that used to tune (train) the model. Furthermore, we argue that, if the CHO is to provide useful insights about new imaging algorithms or devices, the test data should reflect such potential differences from the training data; it is not sufficient simply to use new noise realizations of the same imaging method. Motivated by these considerations, the novelty of this paper is the use of new model selection criteria to evaluate ten established internal-noise models, utilizing four different channel models, in a train-test approach. Though not the focus of the paper, a new internal-noise model is also proposed that outperformed the ten established models in the cases tested. The results, using cardiac perfusion SPECT data, show that the proposed train-test approach is necessary, as judged by the newly proposed model selection criteria, to avoid spurious conclusions. The results also demonstrate that, in some models, the optimal internal-noise parameter is very sensitive to the choice of training data; therefore, these models are prone

  3. Normal cardiac function in mice with supraphysiological cardiac creatine levels.

    Science.gov (United States)

    Santacruz, Lucia; Hernandez, Alejandro; Nienaber, Jeffrey; Mishra, Rajashree; Pinilla, Miguel; Burchette, James; Mao, Lan; Rockman, Howard A; Jacobs, Danny O

    2014-02-01

    Creatine and phosphocreatine levels are decreased in heart failure, and reductions in myocellular phosphocreatine levels predict the severity of the disease and portend adverse outcomes. Previous studies of transgenic mouse models with increased creatine content higher than two times baseline showed the development of heart failure and shortened lifespan. Given phosphocreatine's role in buffering ATP content, we tested the hypothesis whether elevated cardiac creatine content would alter cardiac function under normal physiological conditions. Here, we report the creation of transgenic mice that overexpress the human creatine transporter (CrT) in cardiac muscle under the control of the α-myosin heavy chain promoter. Cardiac transgene expression was quantified by qRT-PCR, and human CrT protein expression was documented on Western blots and immunohistochemistry using a specific anti-CrT antibody. High-energy phosphate metabolites and cardiac function were measured in transgenic animals and compared with age-matched, wild-type controls. Adult transgenic animals showed increases of 5.7- and 4.7-fold in the content of creatine and free ADP, respectively. Phosphocreatine and ATP levels were two times as high in young transgenic animals but declined to control levels by the time the animals reached 8 wk of age. Transgenic mice appeared to be healthy and had normal life spans. Cardiac morphometry, conscious echocardiography, and pressure-volume loop studies demonstrated mild hypertrophy but normal function. Based on our characterization of the human CrT protein expression, creatine and phosphocreatine content, and cardiac morphometry and function, these transgenic mice provide an in vivo model for examining the therapeutic value of elevated creatine content for cardiac pathologies.

  4. Prenatal Stress and Acute Stress Later in Life Impacts the Responses in Tests for Depressive-Like Behavior in a Sex-Specific Manner

    DEFF Research Database (Denmark)

    Sickmann, Helle Mark; Skoven, Christian; Arentzen, Tina S.

    Prenatal maternal stress increases the predisposition for affective disorders. Furthermore, women appear twice as likely as men to develop stress- and depression-related disorders. Comparable behavioral changes characteristic of clinical depression are found in rat offspring following prenatal...... stress (PS). These include increased helplessness, altered anxiety indicators and sleep modifications. Our purpose was to further investigate behavioral depression indices following PS as well as CNS structural changes including sex specificity of these variables. Pregnant Sprague-Dawley rats were...... in locomotor activity, depressive- and anxiety-like behavior as well as sleep architecture. Some animals were analyzed for CNS microstructural changes based on diffusion MRI. Subsets of PS and control rats were exposed to an acute stressor prior to the behavioral tests. Rearing/climbing activity in a familiar...

  5. Cortisol and ghrelin concentrations following a cold pressor stress test in overweight individuals with and without Night Eating

    OpenAIRE

    Geliebter, Allan; Carnell, Susan; Gluck, Marci E.

    2012-01-01

    Objective To explore appetite-related hormones following stress in overweight individuals, and their interaction with Night Eating (NE) status. Method We measured plasma cortisol and ghrelin concentrations, and recorded ratings of stress and hunger in response to a physiological laboratory stressor (Cold Pressor Test, CPT) in overweight women with (n=11; NE) and without (n=17; non-NE) night eating. Results Following the CPT, cortisol (p < .001) and ghrelin (p < .05) levels increased, as did s...

  6. Determination of the Thermal Expansion Coefficient of Concrete at Early Ages by Using Temperature-stress Testing Machine

    Institute of Scientific and Technical Information of China (English)

    HUO Kaicheng; SHUI Zhonghe; LI Yue

    2006-01-01

    By using the uptodate temperatuer-stress testing machine, the thermal expansion coefficient of concrete at early ages was studied and indicative conclusions were achieved: temperature rising due to hydration heat is not directly correlated with cracking, but the temperature and stress evolution process should be taken into consideration in the same time. Proper chemical admixtures and mineral compositions can improve the mechanical properties of concrete such as thermal expansion coefficient, which is very indicative in practice.

  7. The effect of heat treatment and test parameters on the aqueous stress corrosion cracking of D6AC steel

    Science.gov (United States)

    Gilbreath, W. P.; Adamson, M. J.

    1974-01-01

    The crack growth behavior of D6AC steel as a function of stress intensity, stress and corrosion history and test technique, under sustained load in natural seawater, 3.3 percent NaCl solution, distilled water, and high humidity air was investigated. Reported investigations of D6AC were considered with emphasis on thermal treatment, specimen configuration, fracture toughness, crack-growth rates, initiation period, threshold, and the extension of corrosion fatigue data to sustained load conditions. Stress history effects were found to be most important in that they controlled incubation period, initial crack growth rates, and apparent threshold.

  8. Test study on rupture process and permeability properties of coal-rock in simulating mining stress effect

    Institute of Scientific and Technical Information of China (English)

    GAO gao-bin; LI Hua-min; QIAO Chun-sheng; SU Cheng-dong; WANG Wen

    2009-01-01

    A test system was designed by using a set of self-made experimental devices of coupled coal-gas in simulating mining stress effect,combining the equipment with RMT-150B rock mechanical experimental system,monitoring the rupture process of coal-rock with an acoustic emission (AE) device and collecting gas-flow rate and gas-stress data in real-time automatically with a gas flow-meter and gas pressure sensor.The fracture process and permeability properties test of the coal-rock in mining stress ef-fect was carried out.Test results indicate that AE events and variation of stresses have the same variance tendency and the rupture process of coal-rock can be monitored by AE.The relation curves among stresses,parameters of AE and permeability properties dem-onstrate that the permeability of coal-rock decreases gradually at quasi-elastic stage,in-creases gradually at plastic damage micro-fracture stage,rises suddenly near the peak point and has multi-variation at post-peak slip stage.From the results,such conclusion can be drawn that the variation of permeability can be monitored by AE parameters or stress change.

  9. The biopsychosocial model of stress in adolescence: self-awareness of performance versus stress reactivity.

    Science.gov (United States)

    Rith-Najarian, Leslie R; McLaughlin, Katie A; Sheridan, Margaret A; Nock, Matthew K

    2014-03-01

    Extensive research among adults supports the biopsychosocial (BPS) model of challenge and threat, which describes relationships among stress appraisals, physiological stress reactivity, and performance; however, no previous studies have examined these relationships in adolescents. Perceptions of stressors as well as physiological reactivity to stress increase during adolescence, highlighting the importance of understanding the relationships among stress appraisals, physiological reactivity, and performance during this developmental period. In this study, 79 adolescent participants reported on stress appraisals before and after a Trier Social Stress Test in which they performed a speech task. Physiological stress reactivity was defined by changes in cardiac output and total peripheral resistance from a baseline rest period to the speech task, and performance on the speech was coded using an objective rating system. We observed in adolescents only two relationships found in past adult research on the BPS model variables: (1) pre-task stress appraisal predicted post-task stress appraisal and (2) performance predicted post-task stress appraisal. Physiological reactivity during the speech was unrelated to pre- and post-task stress appraisals and to performance. We conclude that the lack of association between post-task stress appraisal and physiological stress reactivity suggests that adolescents might have low self-awareness of physiological emotional arousal. Our findings further suggest that adolescent stress appraisals are based largely on their performance during stressful situations. Developmental implications of this potential lack of awareness of one's physiological and emotional state during adolescence are discussed.

  10. Stress

    Science.gov (United States)

    ... Honor Become a Member En Español Type 1 Type 2 About Us Online Community Meal Planning Sign In Search: Search More Sites Search ≡ Are You At Risk? Diabetes Basics Living with Diabetes Food & Fitness In My ... Diabetes and Learning About Prediabetes Type 2 Diabetes Risk Test Lower Your Risk Healthy ...

  11. A STUDY OF STRESS AND AUTONOMIC FUNCTION TEST IN MEDICAL STUDENTS

    Directory of Open Access Journals (Sweden)

    Mahima

    2014-02-01

    Full Text Available BA CKGROUND : Medical students are frequently described as stressed in comp arison with general population . 1, 2 Particularly examinations are a major cause of stress . 3 High level of stress may have adverse effect on academic achievement. However there is a deficit of information regarding the interrelationship of stress and academic performance in medical students. The present study adds to the literature of the level of stress during examination and its impact on performance in a cohort of first year medical students. The study also discus ses the areas where medical students are more stressful , effects of stress , student’s adaptation styles , and intervention measures to deal with stress , as it is believed that healthy medical students are likely to become healthy doctors who can the n be model and promote healthy li festyles with their patients .

  12. Cadmium-induced oxidative stress and apoptosis in the testes of frog Rana limnocharis

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Hangjun; Cai Chenchen; Shi Cailei; Cao Hui; Han Ziliu [Department of Environmental Sciences, Hangzhou Normal University, Xuelin Road 16, Xiasha Gaojiao Dongqu, Hangzhou, Zhejiang Province, 310036 (China); Jia Xiuying, E-mail: hznujiaxiuying@126.com [Department of Environmental Sciences, Hangzhou Normal University, Xuelin Road 16, Xiasha Gaojiao Dongqu, Hangzhou, Zhejiang Province, 310036 (China)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Cd can cause vacuoles and deformity of the spermatogenic cells in the frog testes. Black-Right-Pointing-Pointer Cd can result in oxidative stress in the frog testes. Black-Right-Pointing-Pointer Cd can induce significantly increase of ROS contents triggered DNA damages in the frog testes. Black-Right-Pointing-Pointer Cd can cause apoptosis in the testes of male R. limnocharis. Black-Right-Pointing-Pointer Apoptosis by Cd in the frog testes is related to Caspase-3, Bax and Bcl-2 genes. - Abstract: This study explored the genetic damage induced by cadmium exposure in the testes of Rana limnocharis. Healthy adult frogs were exposed to 2.5, 5, 7.5, or 10 mg/L of cadmium solution for 14 days. The results showed that exposure to these concentrations increased the levels of reactive oxygen species and malondialdehyde content in the testes, clearly indicating a dose-effect relationship. Moreover, the same dosages of Cd{sup 2+} solution increased glutathione (reduced) content, with the values being significantly different from those observed in the control group (P < 0.01). The comet assay results demonstrated that the DNA damage rate, tail length, and tail moment of samples obtained from frogs exposed to 2.5-7.5 mg/L of cadmium solution significantly increased compared with those of samples obtained from the control group (P < 0.01). These findings suggest that cadmium can induce free radical generation, followed by lipid peroxidation and DNA damage. Ultrastructural observation revealed vacuoles in the spermatogenic cells, cell dispersion, incomplete cell structures, and deformed nucleoli. Moreover, cadmium exposure induced significant down-regulation of Bcl-2 expression and up-regulation of Bax and caspase-3 expressions. Taken together, these data indicate that cadmium can induce testicular cell apoptosis in R. limnocharis. Exploring the effects of cadmium on the mechanism of reproductive toxicity in amphibians will help provide a

  13. Cardiac tissue engineering

    Directory of Open Access Journals (Sweden)

    MILICA RADISIC

    2005-03-01

    Full Text Available We hypothesized that clinically sized (1-5 mm thick,compact cardiac constructs containing physiologically high density of viable cells (~108 cells/cm3 can be engineered in vitro by using biomimetic culture systems capable of providing oxygen transport and electrical stimulation, designed to mimic those in native heart. This hypothesis was tested by culturing rat heart cells on polymer scaffolds, either with perfusion of culture medium (physiologic interstitial velocity, supplementation of perfluorocarbons, or with electrical stimulation (continuous application of biphasic pulses, 2 ms, 5 V, 1 Hz. Tissue constructs cultured without perfusion or electrical stimulation served as controls. Medium perfusion and addition of perfluorocarbons resulted in compact, thick constructs containing physiologic density of viable, electromechanically coupled cells, in contrast to control constructs which had only a ~100 mm thick peripheral region with functionally connected cells. Electrical stimulation of cultured constructs resulted in markedly improved contractile properties, increased amounts of cardiac proteins, and remarkably well developed ultrastructure (similar to that of native heart as compared to non-stimulated controls. We discuss here the state of the art of cardiac tissue engineering, in light of the biomimetic approach that reproduces in vitro some of the conditions present during normal tissue development.

  14. A Test of a Cognitive Diathesis-Stress Generation Pathway in Early Adolescent Depression

    Science.gov (United States)

    Kercher, Amy; Rapee, Ronald M.

    2009-01-01

    This study evaluates a pathway for depressive risk that integrates cognitive diathesis-stress and stress-generation theories, following Hankin and Abramson's (2001, "Journal of Clinical Child and Adolescent Psychology, 31"(4), 491-504) elaborated cognitive-diathesis transactional stress model. In this model, young adolescents with initial…

  15. Cardiac MRI in Athletes

    NARCIS (Netherlands)

    Luijkx, T.

    2012-01-01

    Cardiac magnetic resonance imaging (CMR) is often used in athletes to image cardiac anatomy and function and is increasingly requested in the context of screening for pathology that can cause sudden cardiac death (SCD). In this thesis, patterns of cardiac adaptation to sports are investigated with C

  16. Reconstruction of stress corrosion cracks using signals of pulsed eddy current testing

    Science.gov (United States)

    Wang, Li; Xie, Shejuan; Chen, Zhenmao; Li, Yong; Wang, Xiaowei; Takagi, Toshiyuki

    2013-06-01

    A scheme to apply signals of pulsed eddy current testing (PECT) to reconstruct a deep stress corrosion crack (SCC) is proposed on the basis of a multi-layer and multi-frequency reconstruction strategy. First, a numerical method is introduced to extract conventional eddy current