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Sample records for aging mechanisms expected

  1. Primary Care Clinician Expectations Regarding Aging

    ERIC Educational Resources Information Center

    Davis, Melinda M.; Bond, Lynne A.; Howard, Alan; Sarkisian, Catherine A.

    2011-01-01

    Purpose: Expectations regarding aging (ERA) in community-dwelling older adults are associated with personal health behaviors and health resource usage. Clinicians' age expectations likely influence patients' expectations and care delivery patterns; yet, limited research has explored clinicians' age expectations. The Expectations Regarding Aging…

  2. Brain mechanisms supporting violated expectations of pain.

    PubMed

    Zeidan, Fadel; Lobanov, Oleg V; Kraft, Robert A; Coghill, Robert C

    2015-09-01

    The subjective experience of pain is influenced by interactions between experiences, future predictions, and incoming afferent information. Expectations of high pain can exacerbate pain, whereas expectations of low pain during a consistently noxious stimulus can produce significant reductions in pain. However, the brain mechanisms associated with processing mismatches between expected and experienced pain are poorly understood, but are important for imparting salience to a sensory event to override erroneous top-down expectancy-mediated information. This investigation examined pain-related brain activation when expectations of pain were abruptly violated. After conditioning participants to cues predicting low or high pain, 10 incorrectly cued stimuli were administered across 56 stimulus trials to determine whether expectations would be less influential on pain when there is a high discordance between prestimulus cues and corresponding thermal stimulation. Incorrectly cued stimuli produced pain ratings and pain-related brain activation consistent with placebo analgesia, nocebo hyperalgesia, and violated expectations. Violated expectations of pain were associated with activation in distinct regions of the inferior parietal lobe, including the supramarginal and angular gyrus, and intraparietal sulcus, the superior parietal lobe, cerebellum, and occipital lobe. Thus, violated expectations of pain engage mechanisms supporting salience-driven sensory discrimination, working memory, and associative learning processes. By overriding the influence of expectations on pain, these brain mechanisms are likely engaged in clinical situations in which patients' unrealistic expectations of pain relief diminish the efficacy of pain treatments. Accordingly, these findings underscore the importance of maintaining realistic expectations to augment the effectiveness of pain management.

  3. Brain Mechanisms Supporting Violated Expectations of Pain

    PubMed Central

    Zeidan, Fadel; Lobanov, Oleg V.; Kraft, Robert A.; Coghill, Robert C.

    2015-01-01

    The subjective experience of pain is influenced by interactions between prior experiences, future predictions and incoming afferent information. Expectations of high pain can exacerbate pain while expectations of low pain during a consistently noxious stimulus can produce significant reductions in pain. However, the brain mechanisms associated with processing mismatches between expected and experienced pain are poorly understood, but are important for imparting salience to a sensory event in order to override erroneous top-down expectancy-mediated information. The present investigation examined pain-related brain activation when expectations of pain were abruptly violated. After conditioning participants to cues predicting low or high pain, ten incorrectly cued stimuli were administered across 56 stimulus trials to determine if expectations would be less influential on pain when there is a high discordance between pre-stimulus cues and corresponding thermal stimulation. Incorrectly cued stimuli produced pain ratings and pain-related brain activation consistent with placebo analgesia, nocebo hyperalgesia, and violated expectations. Violated expectations of pain were associated with activation in distinct regions of the inferior parietal lobe, including the supramarginal and angular gyrus, and intraparietal sulcus, the superior parietal lobe, cerebellum and occipital lobe. Thus, violated expectations of pain engage mechanisms supporting salience-driven sensory discrimination, working memory, and associative learning processes. By overriding the influence of expectations on pain, these brain mechanisms are likely engaged in clinical situations where patients’ unrealistic expectations for pain relief diminish the efficacy of pain treatments. Accordingly, these findings underscore the importance of maintaining realistic expectations to augment the effectiveness of pain management. PMID:26083664

  4. An expectation-based memory deficit in aging.

    PubMed

    Bollinger, Jacob; Rubens, Michael T; Masangkay, Edrick; Kalkstein, Jonathan; Gazzaley, Adam

    2011-05-01

    Memory performance can be enhanced by expectations regarding the appearance of ensuing stimuli. Here, we investigated the influence of stimulus-category expectation on memory performance in aging, and used fMRI to explore age-related alterations in associated neural mechanisms. Unlike younger adults, who demonstrated both working memory (WM) and long-term memory (LTM) performance benefits for face stimuli when this stimulus category was expected, older adults did not exhibit these memory benefits. Concordantly, older adults did not exhibit expectation-period activity modulation in visual association cortex (i.e., fusiform face area (FFA)), unlike younger adults. However, within the older population, individuals who demonstrated face-expectation memory benefits also exhibited expectation-period FFA activity modulation equivalent to younger adults. The older cohort also displayed diminished expectation-related functional connectivity between regions of the prefrontal cortex and the FFA, relative to younger adults, suggesting that network alterations underlie the absence of expectation-mediated cortical modulation and memory benefits. This deficit may have broader consequences for the effective utilization of predictive cues to guide attention and engender optimal cognitive performance in older individuals.

  5. The Malleability of Possible Selves and Expectations regarding Aging

    ERIC Educational Resources Information Center

    Bardach, Shoshana H.; Gayer, Christopher C.; Clinkinbeard, Tiffanie; Zanjani, Faika; Watkins, John F.

    2010-01-01

    Many people are apprehensive about old age and their future years. This pilot study sought to improve participants' sense of possibility in, and expectations for, old age. Students and middle-aged volunteers completed a survey including the Expectations Regarding Aging 38-item questionnaire (ERA-38) and a possible-selves questionnaire before and…

  6. Age differences in expected satisfaction with life in retirement.

    PubMed

    Gutierrez, Helen C; Hershey, Douglas A

    2014-01-01

    Research on expected quality of life in retirement has focused on the perceptions of individuals either living in retirement or nearing retirement age. In this article, data are reported that examine expectations of (future) retirement quality of life among younger and middle-aged adults. Toward this end, a new scale--the Satisfaction with Life in Retirement Scale--is introduced. As part of the study, a pair of age-specific, theoretically-driven, hierarchically-structured path models were tested in which individuals' perceptions of future retirement satisfaction were regressed on indicators of financial knowledge, future time perspective, financial risk tolerance, and parental financial values. Models from both age groups were successful in accounting for variability in perceptions of future retirement satisfaction; however, age differences in the model were observed. The results of this investigation have implications for retirement counselors and intervention specialists who seek to cultivate positive perceptions of late life among individuals of different ages.

  7. Effects of Age Expectations on Oncology Social Workers' Clinical Judgment

    ERIC Educational Resources Information Center

    Conlon, Annemarie; Choi, Namkee G.

    2014-01-01

    Objective: This study examined the influence of oncology social workers' expectations regarding aging (ERA) and ERA with cancer (ERAC) on their clinical judgment. Methods: Oncology social workers (N = 322) were randomly assigned to one of four vignettes describing a patient with lung cancer. The vignettes were identical except for the patent's age…

  8. Arts and ageing; life expectancy of historical artists in the Low Countries.

    PubMed

    Mirzada, Fereshta; Schimberg, Anouk S; Engelaer, Frouke M; Bijwaard, Govert E; van Bodegom, David; Westendorp, Rudi G J; van Poppel, Frans W A

    2014-01-01

    Practising arts has been linked to lowering stress, anxiety and blood pressure. These mechanisms are all known to affect the ageing process. Therefore, we examine the relation between long-term involvement in arts and life expectancy at age 50 (LE50), in a cohort of 12,159 male acoustic, literary and visual artists, who were born between 1700 and 1899 in the Low Countries. We compared the life expectancy at age 50 of the various artists with the elite and middle class of that time. In the birth cohorts before 1850, acoustic (LE50:14.5-19.5) and literary artists (LE50:17.8-20.8) had a similar life expectancy at age 50 compared to the elite (LE50:18.0-19.0). Only visual artists (LE50:15.5-17.1) had a lower life expectancy at age 50 compared to the elite at that time. For the most recent birth cohorts from 1850 through 1899, the comparison between artists and the elite reversed and acoustic and literary artist had a lower life expectancy at age 50, while visual artists enjoyed a similar life expectancy at age 50. Although artists belonged to the middle socioeconomic class and lived predominantly in urban areas with poor living conditions, they had a life expectancy similar to the elite population. This is in line with observed favourable effects of practicing arts on health in the short-term. From our historical analysis, we hypothesize several mechanisms through which artistic creativity could influence the ageing process and life expectancy. These hypotheses, however, should be formally tested before any definite conclusions on effects of arts on ageing can be drawn.

  9. Arts and Ageing; Life Expectancy of Historical Artists in the Low Countries

    PubMed Central

    Engelaer, Frouke M.; Bijwaard, Govert E.; van Bodegom, David; Westendorp, Rudi G. J.; van Poppel, Frans W. A.

    2014-01-01

    Practising arts has been linked to lowering stress, anxiety and blood pressure. These mechanisms are all known to affect the ageing process. Therefore, we examine the relation between long-term involvement in arts and life expectancy at age 50 (LE50), in a cohort of 12,159 male acoustic, literary and visual artists, who were born between 1700 and 1899 in the Low Countries. We compared the life expectancy at age 50 of the various artists with the elite and middle class of that time. In the birth cohorts before 1850, acoustic (LE50:14.5–19.5) and literary artists (LE50:17.8–20.8) had a similar life expectancy at age 50 compared to the elite (LE50:18.0–19.0). Only visual artists (LE50:15.5–17.1) had a lower life expectancy at age 50 compared to the elite at that time. For the most recent birth cohorts from 1850 through 1899, the comparison between artists and the elite reversed and acoustic and literary artist had a lower life expectancy at age 50, while visual artists enjoyed a similar life expectancy at age 50. Although artists belonged to the middle socioeconomic class and lived predominantly in urban areas with poor living conditions, they had a life expectancy similar to the elite population. This is in line with observed favourable effects of practicing arts on health in the short-term. From our historical analysis, we hypothesize several mechanisms through which artistic creativity could influence the ageing process and life expectancy. These hypotheses, however, should be formally tested before any definite conclusions on effects of arts on ageing can be drawn. PMID:24416148

  10. [Seed aging and survival mechanisms].

    PubMed

    Grappin, Philippe; Bourdais, Gildas; Collet, Boris; Godin, Béatrice; Job, Dominique; Ogé, Laurent; Jullien, Marc; Rajjou, Loïc

    2008-01-01

    Aging and death are universal to living systems. In temperate climate latitudes the mature seeds of higher plants are exposed to aging and have developed resistance mechanisms allowing survival and plant propagation. In addition to the physicochemical properties of the seed that confer stress resistance, the protein metabolism contributes importantly to longevity mechanisms. Recently, genetic studies have demonstrated the occurrence of the Protein L-isoaspartyl methyltransferase repair enzyme in controlling age-related protein damages and seed survival. These protective mechanisms by protein repair are widespread in all kingdoms, so that the use of seeds as models to study these controlling processes offers the prospect of understanding longevity mechanisms better.

  11. 29 CFR Appendix D to Part 4044 - Tables Used To Determine Expected Retirement Age

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 9 2010-07-01 2010-07-01 false Tables Used To Determine Expected Retirement Age D Appendix... 4044—Tables Used To Determine Expected Retirement Age TABLE I-10—Selection of Retirement Rate Category... II-B. 3 Table II-C. Table II-A—Expected Retirement Ages for Individuals in the Low...

  12. 29 CFR Appendix D to Part 4044 - Tables Used To Determine Expected Retirement Age

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 9 2014-07-01 2014-07-01 false Tables Used To Determine Expected Retirement Age D Appendix... 4044—Tables Used To Determine Expected Retirement Age Table I-14—Selection of Retirement Rate Category... II-B. 3 Table II-C. Table II-A—Expected Retirement Ages for Individuals in the Low...

  13. 29 CFR Appendix D to Part 4044 - Tables Used To Determine Expected Retirement Age

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 9 2013-07-01 2013-07-01 false Tables Used To Determine Expected Retirement Age D Appendix... 4044—Tables Used To Determine Expected Retirement Age Table I-13—Selection of Retirement Rate Category... II-B. 3 Table II-C. Table II-A—Expected Retirement Ages for Individuals in the Low...

  14. 29 CFR Appendix D to Part 4044 - Tables Used To Determine Expected Retirement Age

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 9 2012-07-01 2012-07-01 false Tables Used To Determine Expected Retirement Age D Appendix... 4044—Tables Used To Determine Expected Retirement Age Table I-12— Selection of Retirement Rate Category... II-B. 3 Table II-C. Table II-A—Expected Retirement Ages for Individuals in the Low...

  15. Face-induced expectancies influence neural mechanisms of performance monitoring.

    PubMed

    Osinsky, Roman; Seeger, Jennifer; Mussel, Patrick; Hewig, Johannes

    2016-04-01

    In many daily situations, the consequences of our actions are predicted by cues that are often social in nature. For instance, seeing the face of an evaluator (e.g., a supervisor at work) may activate certain evaluative expectancies, depending on the history of prior encounters with that particular person. We investigated how such face-induced expectancies influence neurocognitive functions of performance monitoring. We recorded an electroencephalogram while participants completed a time-estimation task, during which they received performance feedback from a strict and a lenient evaluator. During each trial, participants first saw the evaluator's face before performing the task and, finally, receiving feedback. Therefore, faces could be used as predictive cues for the upcoming evaluation. We analyzed electrocortical signatures of performance monitoring at the stages of cue processing, task performance, and feedback reception. Our results indicate that, at the cue stage, seeing the strict evaluator's face results in an anticipatory preparation of fronto-medial monitoring mechanisms, as reflected by a sustained negative-going amplitude shift (i.e., the contingent negative variation). At the performance stage, face-induced expectancies of a strict evaluation rule led to increases of early performance monitoring signals (i.e., frontal-midline theta power). At the final stage of feedback reception, violations of outcome expectancies differentially affected the feedback-related negativity and frontal-midline theta power, pointing to a functional dissociation between these signatures. Altogether, our results indicate that evaluative expectancies induced by face-cues lead to adjustments of internal performance monitoring mechanisms at various stages of task processing.

  16. Faster Increases in Human Life Expectancy Could Lead to Slower Population Aging

    PubMed Central

    2015-01-01

    Counterintuitively, faster increases in human life expectancy could lead to slower population aging. The conventional view that faster increases in human life expectancy would lead to faster population aging is based on the assumption that people become old at a fixed chronological age. A preferable alternative is to base measures of aging on people’s time left to death, because this is more closely related to the characteristics that are associated with old age. Using this alternative interpretation, we show that faster increases in life expectancy would lead to slower population aging. Among other things, this finding affects the assessment of the speed at which countries will age. PMID:25876033

  17. Faster increases in human life expectancy could lead to slower population aging.

    PubMed

    Sanderson, Warren C; Scherbov, Sergei

    2015-01-01

    Counterintuitively, faster increases in human life expectancy could lead to slower population aging. The conventional view that faster increases in human life expectancy would lead to faster population aging is based on the assumption that people become old at a fixed chronological age. A preferable alternative is to base measures of aging on people's time left to death, because this is more closely related to the characteristics that are associated with old age. Using this alternative interpretation, we show that faster increases in life expectancy would lead to slower population aging. Among other things, this finding affects the assessment of the speed at which countries will age.

  18. Explaining Optimistic Old Age Disability and Longevity Expectations

    ERIC Educational Resources Information Center

    Costa-Font, Joan; Costa-Font, Montserrat

    2011-01-01

    Biased health care decision making has been regarded as responsible for inefficient behaviours (for example, the limited insurance purchase). This paper empirically examines two sets of biases in the perception of old age disability and longevity. Particularly, we test for the existence of a so called cumulative bias and, secondly, a so called…

  19. Better or Worse than Expected? Aging, Learning, and the ERN

    ERIC Educational Resources Information Center

    Eppinger, Ben; Kray, Jutta; Mock, Barbara; Mecklinger, Axel

    2008-01-01

    This study examined age differences in error processing and reinforcement learning. We were interested in whether the electrophysiological correlates of error processing, the error-related negativity (ERN) and the feedback-related negativity (FRN), reflect learning-related changes in younger and older adults. To do so, we applied a probabilistic…

  20. Marcel Duchamp, the Artist, and the Social Expectations of Aging.

    ERIC Educational Resources Information Center

    Pritikin, Reynold

    1990-01-01

    Reviews life of Marcel Duchamp, considered by many art professionals to be the best artist of this century. Claims Duchamp's career speaks to issues of aging because over his lifetime there was no diminution of quality of innovation, theory, or power. (Author/ABL)

  1. Cellular ageing mechanisms in osteoarthritis.

    PubMed

    Sacitharan, P K; Vincent, T L

    2016-08-01

    Age is the strongest independent risk factor for the development of osteoarthritis (OA) and for many years this was assumed to be due to repetitive microtrauma of the joint surface over time, the so-called 'wear and tear' arthritis. As our understanding of OA pathogenesis has become more refined, it has changed our appreciation of the role of ageing on disease. Cartilage breakdown in disease is not a passive process but one involving induction and activation of specific matrix-degrading enzymes; chondrocytes are exquisitely sensitive to changes in the mechanical, inflammatory and metabolic environment of the joint; cartilage is continuously adapting to these changes by altering its matrix. Ageing influences all of these processes. In this review, we will discuss how ageing affects tissue structure, joint use and the cellular metabolism. We describe what is known about pathways implicated in ageing in other model systems and discuss the potential value of targeting these pathways in OA.

  2. Marcel Duchamp, the artist, and the social expectations of aging.

    PubMed

    Pritikin, R

    1990-10-01

    French artist Marcel Duchamp (1887-1968) is considered by many art professionals to be the greatest artist of this century. During his long career, Duchamp developed a set of radical theories that literally redefined art as a contemporary praxis. Indeed, much of Duchamp's work anticipates what today is called postmodern theory. The Duchamp career speaks to issues of aging because over the span of an entire lifetime of 81 years there was no diminution of quality of innovation, theory, or power.

  3. Age Effects on Hypocotyl Mechanics

    PubMed Central

    Weichold, Susann; Reinecke, Antje; Lisec, Jan; Döring, Anett; Neumetzler, Lutz; Burgert, Ingo; Eder, Michaela

    2016-01-01

    Numerous studies deal with composition and molecular processes involved in primary cell wall formation and alteration in Arabidopsis. However, it still remains difficult to assess the relation between physiological properties and mechanical function at the cell wall level. The thin and fragile structure of primary cell walls and their large biological variability, partly related to structural changes during growth, make mechanical experiments challenging. Since, to the best of our knowledge, there is no reliable data in the literature about how the properties of the fully elongated zone of hypocotyls change with age. We studied in a series of experiments on two different seed batches the tensile properties the region below the growth zone of 4 to 7 day old etiolated Arabidopsis hypocotyls. Additionally, we analysed geometrical parameters, hypocotyl density and cellulose content as individual traits and their relation to tissue mechanics. No significant differences of the mechanical parameters of the non-growing region between 5–7 day old plants could be found whereas in 4 day old plants both tensile stiffness and ultimate tensile stress were significantly lower than in the older plants. Furthermore hypocotyl diameters and densities remain almost the same for 5, 6 and 7 day old seedlings. Naturally, hypocotyl lengths increase with age. The evaluation whether the choice–age or length—influences the mechanical properties showed that both are equally applicable sampling parameters. Additionally, our detailed study allows for the estimation of biological variability, connections between mechanics and hypocotyl age could be established and complement the knowledge on biochemistry and genetics affecting primary plant cell wall growth. The application of two different micromechanical devices for testing living Arabidopsis hypocotyls allows for emphasizing and discussing experimental limitations and for presenting a wide range of possibilities to address current and

  4. Multisensory integration mechanisms during aging

    PubMed Central

    Freiherr, Jessica; Lundström, Johan N.; Habel, Ute; Reetz, Kathrin

    2013-01-01

    The rapid demographical shift occurring in our society implies that understanding of healthy aging and age-related diseases is one of our major future challenges. Sensory impairments have an enormous impact on our lives and are closely linked to cognitive functioning. Due to the inherent complexity of sensory perceptions, we are commonly presented with a complex multisensory stimulation and the brain integrates the information from the individual sensory channels into a unique and holistic percept. The cerebral processes involved are essential for our perception of sensory stimuli and becomes especially important during the perception of emotional content. Despite ongoing deterioration of the individual sensory systems during aging, there is evidence for an increase in, or maintenance of, multisensory integration processing in aging individuals. Within this comprehensive literature review on multisensory integration we aim to highlight basic mechanisms and potential compensatory strategies the human brain utilizes to help maintain multisensory integration capabilities during healthy aging to facilitate a broader understanding of age-related pathological conditions. Further our goal was to identify where further research is needed. PMID:24379773

  5. Multisensory integration mechanisms during aging.

    PubMed

    Freiherr, Jessica; Lundström, Johan N; Habel, Ute; Reetz, Kathrin

    2013-12-13

    The rapid demographical shift occurring in our society implies that understanding of healthy aging and age-related diseases is one of our major future challenges. Sensory impairments have an enormous impact on our lives and are closely linked to cognitive functioning. Due to the inherent complexity of sensory perceptions, we are commonly presented with a complex multisensory stimulation and the brain integrates the information from the individual sensory channels into a unique and holistic percept. The cerebral processes involved are essential for our perception of sensory stimuli and becomes especially important during the perception of emotional content. Despite ongoing deterioration of the individual sensory systems during aging, there is evidence for an increase in, or maintenance of, multisensory integration processing in aging individuals. Within this comprehensive literature review on multisensory integration we aim to highlight basic mechanisms and potential compensatory strategies the human brain utilizes to help maintain multisensory integration capabilities during healthy aging to facilitate a broader understanding of age-related pathological conditions. Further our goal was to identify where further research is needed.

  6. Longitudinal Change in Happiness during Aging: The Predictive Role of Positive Expectancies

    ERIC Educational Resources Information Center

    Holahan, Carole K.; Holahan, Charles J.; Velasquez, Katherine E.; North, Rebecca J.

    2008-01-01

    This study employed hierarchical linear modeling to document the time course of happiness across 20 years from average ages of 66 to 86 among 717 members of the Terman Study of the Gifted. In addition, the study examined the role of positive expectancies about aging, assessed at an average age of 61, in enhancing happiness in aging. The results…

  7. 29 CFR Appendix D to Part 4044 - Tables Used To Determine Expected Retirement Age

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 9 2011-07-01 2011-07-01 false Tables Used To Determine Expected Retirement Age D Appendix... 4044—Tables Used To Determine Expected Retirement Age Table I-11—Selection of Retirement Rate Category If participant reaches URA in year— Participant's retirement rate category is— Low 1 if...

  8. Perceived controllability of expected psychological change across adulthood and old age.

    PubMed

    Heckhausen, J; Baltes, P B

    1991-07-01

    This cross-sectional study focuses on adults' beliefs about the controllability of developmental change in adulthood and old age. Young (n = 33; age range 20-36 years), middle-aged (n = 35; age range 40-55 years), and older (n = 32; age range 60-85 years) adults rated an extensive list of psychological attributes in terms of the degree of expected developmental increase across the adult life span (ages 20-90), the perceived controllability of these changes, their desirability, and their expected age-related timing. The findings indicate a substantial degree of similarity in young, middle-aged, and old adults' overall beliefs about controllability. The three adult age groups agreed in perceiving developmental changes in adulthood as fairly controllable, and with regard to their relative controllability (rank ordering of change-sensitive attributes). Changes expected to occur later in life were consensually perceived to be less desirable, and less desirable changes were perceived as less controllable. However, there were clear age-related differences involving both the age timing of expected changes and the age of respondents. A comparison between the three subject age groups revealed twofold differences: First, the relationship between desirability and perceived controllability was found to increase with subjects' age; second, Q-technique factor analysis showed that large subgroups of the young and the middle-aged adults, but not the old adults, tended to perceive psychological attributes associated with late onset decline as relatively lower in controllability.

  9. What Do Children Know about Their Futures: Do Children's Expectations Predict Outcomes in Middle Age?

    ERIC Educational Resources Information Center

    Hallerod, Bjorn

    2011-01-01

    Are children's statements about their futures related to outcomes in middle age? In 1966 almost 13,500 children ages 12-13 were asked whether they thought their futures would be worse, similar or better as compared to others of their own age. It was shown that children with low, and surprisingly high, expectations did suffer from increased…

  10. Alcohol expectancies: effects of gender, age, and family history of alcoholism.

    PubMed

    Lundahl, L H; Davis, T M; Adesso, V J; Lukas, S E

    1997-01-01

    To explore the effects of gender, age, and positive (FH+) and negative (FH-) family history of alcoholism on alcohol-related expectancies, the Alcohol Expectancy Questionnaire (AEQ) was administered to 627 college students (female n = 430). In an attempt to control for consumption effects, only individuals who described themselves as heavy drinkers were included in the study. A 2 (Family History) x 2 (Gender) x 2 (Age Range) multivariate analysis of variance (MANOVA) was conducted on the six scales of the AEQ. Results indicated that FH+ females under the age of 20 years reported stronger expectancies of social and physical pleasure than did FH- females. Results also suggested that females over the age of 20 reported significantly lower expectancies of global, positive effects compared to all other subjects, regardless of family history of alcoholism. Finally, both male and female subjects under the age of 20 reported greater expectancies of global, positive effects, sexual enhancement, feelings of increased power and aggression, and social assertion compared to individuals over the age of 20. These results indicate that alcohol-related expectancies vary as a function of age, gender, and family history of alcoholism.

  11. Healthy life expectancy in the context of population health and ageing in India.

    PubMed

    Lau, Robin S; Johnson, Shanthi; Kamalanabhan, T J

    2012-01-01

    This study examines life expectancy (LE) and healthy life expectancy (HLE) in India longitudinally over the period 2007 to 2020, providing projections into the future. Specifically, the Indian Healthy Life Expectancy Projection model was developed based on epidemiological data (mortality, disability rates) obtained from the World Health Organization and the Government of India. The current model contributed to 4 key findings: decreases in mortality but not in all age and gender groups; increasing disability in the Indian population over time; increase in LE and HLE into the future in all age and gender groups; and the largest gains in LE and HLE are in the older age bands starting from the 70+ age band in women and 65+ age band in men. This study sheds some light on the population health measures needed to improve the understanding of the determinants of health for the efficient allocation of resources and to inform policy in the planning of health and social services.

  12. Fertility Decline, Gender Composition of Families, and Expectations of Old Age Support

    PubMed Central

    Allendorf, Keera

    2017-01-01

    Recent fertility declines in non-Western countries may have the potential to transform gender systems. One pathway for such transformations is the creation of substantial proportions of families with children of only one gender. Such families, particularly those with only daughters, may facilitate greater symmetry between sons and daughters. This article explores whether such shifts may influence gendered expectations of old age support. In keeping with patriarchal family systems, old age support is customarily provided by sons, but not daughters, in India. Using data from the 2005 Indian Human Development Survey, I find that women with sons overwhelmingly expect old age support from a son. By contrast, women with only daughters largely expect support from a daughter or a source besides a child. These findings suggest that fertility decline may place demographic pressure on gendered patterns of old age support and the gender system more broadly.

  13. Pygmalion and the student: age and classroom differences in children's awareness of teacher expectations.

    PubMed

    Weinstein, R S; Marshall, H H; Sharp, L; Botkin, M

    1987-08-01

    This study explores age and classroom differences in children's awareness of teacher expectations and in the relation between awareness and self-expectations. In a sample of 579 children and their teachers in 30 first- (6-7-year-olds), third- (8-9-year-olds), and fifth-grade (10-11-year-olds) classrooms, assessed in the fall, younger children were found to be less accurate than fifth graders in predicting teacher expectations and in reporting differential patterns in their own interactions with the teacher. Yet first graders identified classroom differences in the degree of differential teacher treatment toward high and low achievers that were associated with differences in the expectations that high and low teacher-expectancy students reported for themselves. Fifth graders appeared more likely than younger children to mirror teacher expectancies in their self-descriptions regardless of the degree of differential treatment reported in the classroom environment.

  14. Longevity in Slovenia: Past and potential gains in life expectancy by age and causes of death

    PubMed Central

    Lotrič Dolinar, Aleša; Došenović Bonča, Petra

    2017-01-01

    Abstract Introduction In Slovenia, longevity is increasing rapidly. From 1997 to 2014, life expectancy at birth increased by 7 and 5 years for men and women, respectively. This paper explores how this gain in life expectancy at birth can be attributed to reduced mortality from five major groups of causes of death by 5-year age groups. It also estimates potential future gains in life expectancy at birth. Methods The importance of the five major causes of death was analysed by cause-elimination life tables. The total elimination of individual causes of death and a partial hypothetical adjustment of mortality to Spanish levels were analysed, along with age and cause decomposition (Pollard). Results During the 1997–2014 period, the increase in life expectancy at birth was due to lower mortality from circulatory diseases (ages above 60, both genders), as well as from lower mortality from neoplasms (ages above 50 years) and external causes (between 20 and 50 years) for men. However, considering the potential future gains in life expectancy at birth, by far the strongest effect can be attributed to lower mortality due to circulatory diseases for both genders. If Spanish mortality rates were reached, life expectancy at birth would increase by more than 2 years, again mainly because of lower mortality from circulatory diseases in very old ages. Discussion and conclusions Life expectancy analyses can improve evidence-based decision-making and allocation of resources among different prevention programmes and measures for more effective disease management that can also reduce the economic burden of chronic diseases. PMID:28289472

  15. Telomere dynamics rather than age predict life expectancy in the wild

    PubMed Central

    Bize, Pierre; Criscuolo, François; Metcalfe, Neil B.; Nasir, Lubna; Monaghan, Pat

    2009-01-01

    Despite accumulating evidence from in vitro studies that cellular senescence is linked to telomere dynamics, how this relates to whole-organism senescence and longevity is poorly understood and controversial. Using data on telomere length in red blood cells and long-term survival from wild Alpine swifts of a range of ages, we report that the telomere length and the rate of telomere loss are predictive of life expectancy, and that slow erosion of relatively long telomeres is associated with the highest survival probabilities. Importantly, because telomere dynamics, rather than chronological age, predict life expectancy, our study provides good evidence for a mechanistic link between telomere erosion and reduced organism longevity under natural conditions, chronological age itself possibly not becoming a significant predictor until very old ages beyond those in our sample. PMID:19324831

  16. Survey of Aging Veterans: A Study of the Means, Resources and Future Expectations of Veterans Aged 55 and Over.

    ERIC Educational Resources Information Center

    Veterans Administration, Washington, DC. Office of Information Management and Statistics.

    A national survey of the needs, resources, and future expectations of veterans aged 55 and over produced findings that the Veterans Administration (VA) will use over the next decade to plan facilities and programs to meet those needs. Findings indicated veterans had a higher educational level and were less likely to be at the lower end of the…

  17. Aging expectations are associated with physical activity and health among older adults of low socioeconomic status.

    PubMed

    Dogra, Shilpa; Al-Sahab, Ban; Manson, James; Tamim, Hala

    2015-04-01

    The purpose of the current study was to determine whether aging expectations (AE) are associated with physical activity participation and health among older adults of low socioeconomic status (SES). A cross-sectional analysis of a sample of 170 older adults (mean age 70.9 years) was conducted. Data on AE, physical activity, and health were collected using the 12 item Expectations Regarding Aging instrument, the Healthy Physical Activity Participation Questionnaire, and the Short Form-36, respectively. Adjusted linear regression models showed significant associations between AE and social functioning, energy/vitality, mental health, and self-rated general health, as well as physical activity. These results suggest that AE may help to better explain the established association between low SES, low physical activity uptake, and poor health outcomes among older adults.

  18. Modelling the molecular mechanisms of aging.

    PubMed

    Mc Auley, Mark T; Guimera, Alvaro Martinez; Hodgson, David; Mcdonald, Neil; Mooney, Kathleen M; Morgan, Amy E; Proctor, Carole J

    2017-02-28

    The aging process is driven at the cellular level by random molecular damage that slowly accumulates with age. Although cells possess mechanisms to repair or remove damage, they are not 100% efficient and their efficiency declines with age. There are many molecular mechanisms involved and exogenous factors such as stress also contribute to the aging process. The complexity of the aging process has stimulated the use of computational modelling in order to increase our understanding of the system, test hypotheses and make testable predictions. As many different mechanisms are involved, a wide range of models have been developed. This paper gives an overview of the types of models that have been developed, the range of tools used, modelling standards and discusses many specific examples of models that have been grouped according to the main mechanisms that they address. We conclude by discussing the opportunities and challenges for future modelling in this field.

  19. Modelling the molecular mechanisms of aging

    PubMed Central

    Mc Auley, Mark T.; Guimera, Alvaro Martinez; Hodgson, David; Mcdonald, Neil; Mooney, Kathleen M.; Morgan, Amy E.

    2017-01-01

    The aging process is driven at the cellular level by random molecular damage that slowly accumulates with age. Although cells possess mechanisms to repair or remove damage, they are not 100% efficient and their efficiency declines with age. There are many molecular mechanisms involved and exogenous factors such as stress also contribute to the aging process. The complexity of the aging process has stimulated the use of computational modelling in order to increase our understanding of the system, test hypotheses and make testable predictions. As many different mechanisms are involved, a wide range of models have been developed. This paper gives an overview of the types of models that have been developed, the range of tools used, modelling standards and discusses many specific examples of models that have been grouped according to the main mechanisms that they address. We conclude by discussing the opportunities and challenges for future modelling in this field. PMID:28096317

  20. Epigenetic mechanisms of dietary restriction induced aging in Drosophila.

    PubMed

    Lian, Ting; Gaur, Uma; Yang, Deying; Li, Diyan; Li, Ying; Yang, Mingyao

    2015-12-01

    Aging is a long-standing problem that people are always interested in. Thus, it is critical to understand the underlying molecular mechanisms in aging and explore the most efficient method to extend life expectancy. To achieve this goal, a wide range of systems including cells, rodent models, budding yeast, worms and flies have been employed for decades. In recent years, the effect of dietary restriction (DR) on lifespan is in the prime focus. Although we have confirmed that reduced insulin and/or insulin-like growth factor (IGF) and the target of rapamycin (TOR) signaling can increase Drosophila lifespan; the precise molecular mechanisms and nutritional response landscape of diet-mediated aging is ambiguous. Epigenetic events have been considered as the major contributors to lifespan extension with response to DR. The role of DNA methylation in aging is well acknowledged in mammals and rodents where it has been shown to impact aging by regulating the transcription, though the mechanism of regulation is not limited to only transcription. In Drosophila, the contribution of methylation during DR in aging is definitely less explored. In this review, we will update the advances in mechanisms of DR, with a particular focus on methylation as an upcoming target for aging studies and discuss Drosophila as a powerful model to understand mechanisms of aging with response to diet.

  1. Month of birth and life expectancy: role of gender and age in a comparative approach

    NASA Astrophysics Data System (ADS)

    Lerchl, Alexander

    2004-09-01

    The effects of month of birth (MOB) on life expectancy of a German subpopulation was investigated. Data from people who died in North Rhine Westphalia in the years 1984 (n=188,515) and 1999 (n=188,850) were analyzed. For comparative purposes, all deaths that occurred at an age of <50 years were excluded (1984: 8.4%; 1999: 6.2%). In general, individuals born in May through July had the lowest age at death (1984: 75.27±0.09 years; 1999: 77.58±0.09 years), while those born between October and December had the highest (1984: 75.98±0.08 years; 1999: 78.35±0.09 years), supporting earlier findings. The observed amplitudes (differences between highest and lowest values) were more pronounced in men than in women. When comparing these data of MOB effects on life expectancy with earlier findings in Australia, Austria, Denmark, Ukraine, and the USA, it is evident that a negative correlation exists between the average age at death and the MOB amplitudes. Separate analyses by gender, possible for the data from Germany, the Ukraine, and the USA, revealed a significant negative correlation for men, but not for women. A new hypothesis is therefore presented describing an influence of life quality, as reflected by average life expectancy, on the extent of MOB effects; for example, seasonally variable sensitivities during pregnancy/early childhood.

  2. Ageing mechanisms and associated lipid changes.

    PubMed

    Kolovou, Genovefa; Katsiki, Niki; Pavlidis, Antonis; Bilianou, Helen; Goumas, George; Mikhailidis, Dimitri P

    2014-01-01

    Ageing is related to slowdown/breakdown of the somatotropic axis (i.e. the somatopause) leading to many physiological changes. The somatopause is accompanied by DNA and other macromolecule damage, and is characterized by a progressive decline in vitality and tissue function. We still do not have a definitive understanding of the mechanism( s) of ageing. Several overlapping theories have been proposed such as: 1) The free radical theory, 2) Mitochondrial Ageing, 3) The Glycation Theory, 4) Protein Damage and Maintenance in Ageing, and, 5) DNA Damage and Repair. Furthermore, several models of ageing were introduced such as genetically programmed senescence, telomere shortening, genomic instability, heterochromatin loss, altered epigenetic patterns and long lived cells. There are certain lipid modifications associated with the somatopause, characterized mainly by an increase in total cholesterol and triglyceride levels in both genders. In this review we consider the mechanisms of ageing and the associated changes in lipid metabolism according to gender.

  3. Age-related characteristics of risky decision-making and progressive expectation formation.

    PubMed

    Kardos, Zsófia; Kóbor, Andrea; Takács, Ádám; Tóth, Brigitta; Boha, Roland; File, Bálint; Molnár, Márk

    2016-10-01

    During daily encounters, it is inevitable that people take risks. Investigating the sequential processing of risk hazards involve expectation formation about outcome contingencies. The present study aimed to explore risk behavior and its neural correlates in sequences of decision making, particularly in old age, which represents a critical period regarding risk-taking propensity. The Balloon Analogue Risk Task was used in an electrophysiological setting with young and elderly age groups. During the task each additional pump on a virtual balloon increased the likelihood of a balloon burst but also increased the chance to collect more reward. Event-related potentials associated with rewarding feedback were analyzed based on the forthcoming decisions (whether to continue or to stop) in order to differentiate between states of expectation towards gain or loss. In the young, the reward positivity ERP component increased as a function of reward contingencies with the largest amplitude for rewarding feedback followed by the decision to stop. In the elderly, however, reward positivity did not reflect the effect of reward structure. Behavioral indices of risk-taking propensity suggest that the performance of the young and the elderly were dissociable only with respect to response times: The elderly was characterized by hesitation and more deliberative decision making throughout the experiment. These findings signify that sequential tracking of outcome contingencies has a key role in cost-efficient action planning and progressive expectation formation.

  4. From stage to age in variable environments: life expectancy and survivorship.

    PubMed

    Tuljapurkar, Shripad; Horvitz, Carol C

    2006-06-01

    Stage-based demographic data are now available on many species of plants and some animals, and they often display temporal and spatial variability. We provide exact formulas to compute age-specific life expectancy and survivorship from stage-based data for three models of temporal variability: cycles, serially independent random variation, and a Markov chain. These models provide a comprehensive description of patterns of temporal variation. Our formulas describe the effects of cohort (birth) environmental condition on mortality at all ages, and of the effects on survivorship of environmental variability experienced over the course of life. This paper complements existing methods for time-invariant stage-based data, and adds to the information on population growth and dynamics available from stochastic demography.

  5. Rapid increase in human life expectancy: will it soon be limited by the aging of elastin?

    PubMed

    Robert, L; Robert, A M; Fülöp, T

    2008-04-01

    The postponement of the most frequent age-related diseases stimulated speculations of the possibility of "dying of old age". The selective decline of individual physiological functions-aging in spare-parts-indicates however the potential limitation of the life-span by the rapid decline of some of the vital parameters. We explored a possibility of such a limitation of maximal life-span by the age-related alteration of elastin, consisting in Ca-accumulation, lipid deposition and elastolytic degradation. The quantitative evaluation of these processes suggests an approximative upper limit for the elastic properties of the cardio-respiratory system of about 100-120 years, at least, as far as elastin is involved. This process, age-related alterations of elastic fibers, is however not the only one limiting the functional value of the cardiovascular system. Crosslinking of collagen fibers by advanced glycation end-products certainly contributes also to the age-dependent rigidification of the cardiovascular system. Therefore the answer to the initial question, can age-dependent alterations of a single matrix macromolecule be limiting such vital functions as the cardio-respiratory system-is a cautious yes, with however the caveat that other, independent mechanisms, such as the Maillard reaction, can also interfere with and limit further the functional value of such vital physiological functions.

  6. Interpretation and expectation in childhood anxiety disorders: age effects and social specificity.

    PubMed

    Creswell, Cathy; Murray, Lynne; Cooper, Peter

    2014-01-01

    Theory and treatment for childhood anxiety disorders typically implicates children's negative cognitions, yet little is known about the characteristics of thinking styles of clinically anxious children. In particular, it is unclear whether differences in thinking styles between children with anxiety disorders and non-anxious children vary as a function of child age, whether particular cognitive distortions are associated with childhood anxiety disorders at different child ages, and whether cognitive content is disorder-specific. The current study addressed these questions among 120 7-12 year old children (53% female) who met diagnostic criteria for social anxiety disorder, other anxiety disorder, or who were not currently anxious. Contrary to expectations, threat interpretation was not inflated amongst anxious compared to non-anxious children at any age, although older (10-12 year old) anxious children did differ from non-anxious children on measures of perceived coping. The notion of cognitive-content specificity was not supported across the age-range. The findings challenge current treatment models of childhood anxiety, and suggest that a focus on changing anxious children's cognitions is not warranted in mid-childhood, and in late childhood cognitive approaches may be better focussed on promoting children's perceptions of control rather than challenging threat interpretations.

  7. Loss of adaptive mechanisms during aging.

    PubMed

    Adelman, R C

    1979-05-01

    Factors contributing to modifications in the capability for enzyme adaptation as an expression of aging are reviewed. Specific examples of altered enzyme adaptations during aging include the responses of hepatic glucokinase activity to glucose and hepatic tyrosine aminotransferase activity to starvation in Sprague-Dawley rats. These impaired enzyme adaptations apparently are not the consequence of alterations in hepatic function during aging. Instead, they reflect disturbances in extrahepatic hormonal regulatory mechanisms. Specific examples include modifications in the control of circulating levels of insulin glucagon, corticosteroids, and thyroid hormones. Age-dependent changes in the regulation of circulating levels of insulin probably originate within the impaired ability of pancreatic islets of Langerhans to secrete the hormone in response to glucose. The rationale for exploiting this experimental approach as a means to understand biological aging is discussed.

  8. Early expectations of AMS: Greater ages and tiny fractions. One failure? — One success

    NASA Astrophysics Data System (ADS)

    Schmidt, Fred H.; Balsley, David R.; Leach, Donald D.

    1987-11-01

    Two of the early expectations of AMS were extension to greater 14C ages than possible with beta counting, and applications using tiny amounts of carbon. We examine each in the light of our experiences. The age limit depends on true or apparent ion counts, which may originate in sample preparation, in the accelerating system itself, or from ions other than 14C which are not adequately suppressed. 14N ions are generated spontaneously in our FN tandem, whether the ion source is open to the tandem or not, but are suppressed in the detector. There is no evidence of spontaneous 14C ion production. Thus the ion-source and tandem system alone is capable of age determinations ⩾ 90000 yr. For presumably "dead" geological graphite, we obtain a maximum of 70000 yr, and about 50000 yr for "dead" material which has undergone chemical and physical preparation. In this respect our full AMS system is at present a mixed success. However, our applications to small fractions have been quite successful. We have applied this advantage to the study of the organic carbon components present in the Amazon River and in deep sea cores.

  9. Mechanical Tests For Monitoring Aging Of Composites

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J.

    1994-01-01

    Experimental study addresses related topics of thermo-oxidative aging of PMR-15 (polyimide matrix/graphite-fiber composite materials) strengths of interfacial bonds, effects of various surface treatments, and relative merits of mechanical tests yielding measures of strengths of materials.

  10. Age of Migration Life Expectancy with Functional Limitations and Morbidity in Mexican Americans.

    PubMed

    Garcia, Marc A; Valderrama-Hinds, Luis M; Chiu, Chi-Tsun; Mutambudzi, Miriam S; Chen, Nai-Wei; Raji, Mukaila

    2017-03-30

    The U.S. Mexican American population enjoys longer life expectancies relative to other racial/ethnic groups but is disproportionately affected by chronic conditions and functional limitations. Studying the impact of heterogeneity in age, time and other characteristics of migration among older Mexican Americans can inform our understanding of health disparities and healthcare needs in later-life. This research used 20 years of data from the Hispanic Established Populations for the Epidemiologic Study of the Elderly to assess the proportion of life spent with functional limitations and one or more morbidity (according to age of migration and sex) in the U.S. Mexican-American population. The results indicate that early-life and late-life migrant women spend more years with Performance-Oriented Mobility Assessment limitations than U.S.-born women. Conversely, midlife migrant women were not statistically different from U.S.-born women in years spent disabled. In men, midlife migrants had longer life expectancies and had more disability-free years than U.S.-born men. For morbidity, late-life migrant women spent a significantly smaller proportion of their elderly years with morbidity than U.S.-born women, but late-life migrant men spent more years with morbidity than U.S.-born men. These findings illustrate that older Mexican Americans in the United States are heterogeneous in nativity and health outcomes. More years spent disabled or unhealthy may result in greater burden on family members and greater dependence on public resources. These findings have implications for the development of social and health policies to appropriately target the medical conditions and disabilities of older Mexican Americans entering late life.

  11. Longevity and aging. Mechanisms and perspectives.

    PubMed

    Labat-Robert, J; Robert, L

    2015-12-01

    Longevity can mostly be determined with relative accuracy from birth and death registers when available. Aging is a multifactorial process, much more difficult to quantitate. Every measurable physiological function declines with specific speeds over a wide range. The mechanisms involved are also different, genetic factors are of importance for longevity determinations. The best-known genes involved are the Sirtuins, active at the genetic and epigenetic level. Aging is multifactorial, not "coded" in the genome. There are, however, a number of well-studied physical and biological parameters involved in aging, which can be determined and quantitated. We shall try to identify parameters affecting longevity as well as aging and suggest some reasonable predictions for the future.

  12. Normal brain ageing: models and mechanisms

    PubMed Central

    Toescu, Emil C

    2005-01-01

    Normal ageing is associated with a degree of decline in a number of cognitive functions. Apart from the issues raised by the current attempts to expand the lifespan, understanding the mechanisms and the detailed metabolic interactions involved in the process of normal neuronal ageing continues to be a challenge. One model, supported by a significant amount of experimental evidence, views the cellular ageing as a metabolic state characterized by an altered function of the metabolic triad: mitochondria–reactive oxygen species (ROS)–intracellular Ca2+. The perturbation in the relationship between the members of this metabolic triad generate a state of decreased homeostatic reserve, in which the aged neurons could maintain adequate function during normal activity, as demonstrated by the fact that normal ageing is not associated with widespread neuronal loss, but become increasingly vulnerable to the effects of excessive metabolic loads, usually associated with trauma, ischaemia or neurodegenerative processes. This review will concentrate on some of the evidence showing altered mitochondrial function with ageing and also discuss some of the functional consequences that would result from such events, such as alterations in mitochondrial Ca2+ homeostasis, ATP production and generation of ROS. PMID:16321805

  13. Mechanisms of age-related bone loss.

    PubMed

    Mosekilde, L

    2001-01-01

    The human skeleton is formed and modelled during childhood and youth through the influence of hormones and daily mechanical usage. Around the age of 20-25 years, the skeleton achieves its maximum mass and strength. Thereafter, and throughout adult life, bone is lost at an almost constant rate due to the dynamic bone turnover process: the remodelling process. During this process, small packets of bone are renewed by teams of bone cells coupled together in time and space. In an adult human skeleton there will be 1-2 million active remodelling sites at any time point. The vast number of turnover units combined with a slightly negative balance at the completion of each process leads to the age-related loss of bone mass mentioned above and, concomitantly, to loss of structural continuity and strength. The magnitude of this loss will be determined by hormonal factors, nutrition and mechanical usage. As a consequence of the remodelling process, the bone tissue of the skeleton will always be younger than the age of the individual. However, as a consequence of the remodelling process, osteopenia and osteoporotic fractures will also occur. In this article, the remodelling-induced changes in the human spine will be used as an example of ageing bone.

  14. Behavioral autonomy age expectations among Mexican-origin mother-daughter dyads: an examination of within-group variability.

    PubMed

    Bámaca-Colbert, Mayra Y; Umaña-Taylor, Adriana J; Espinosa-Hernández, Graciela; Brown, Ashley M

    2012-06-01

    This study examined differences in behavioral autonomy age expectations between Mexican-origin mothers and their adolescent daughters (N = 319 dyads); variability in behavioral autonomy age expectations as a function of nativity and maternal educational attainment also was examined. Findings indicated significant differences between mothers and daughters, such that mothers reported later expectations for the timing of behavioral autonomy than did daughters. Follow-up analyses indicated that findings appeared to be driven by maternal nativity, with dyads comprised of Mexico-born mothers reporting the latest age expectations for behavioral autonomy when compared with dyads comprised of U.S. born mothers. Findings underscore the need to examine normative development among Latino adolescents and their families with a specific focus on how sociocultural characteristics can contribute to within-family differences.

  15. Behavioral Autonomy Age Expectations among Mexican-Origin Mother-Daughter Dyads: An Examination of Within-Group Variability

    PubMed Central

    Bámaca-Colbert, Mayra Y.; Umaña-Taylor, Adriana J.; Espinosa-Hernández, Graciela; Brown, Ashley M.

    2011-01-01

    This study examined differences in behavioral autonomy age expectations between Mexican-origin mothers and their adolescent daughters (N = 319 dyads); variability in behavioral autonomy age expectations as a function of nativity and maternal educational attainment also was examined. Findings indicated significant differences between mothers and daughters such that mothers reported later expectations for the timing of behavioral autonomy than did daughters. Follow-up analyses indicated that findings appeared to be driven by maternal nativity, with dyads comprised of Mexico-born mothers reporting the latest age expectations for behavioral autonomy when compared with dyads comprised of U.S.-born mothers. Findings underscore the need to examine normative development among Latino adolescents and their families with a specific focus on how sociocultural characteristics can contribute to within-family differences. PMID:22093152

  16. Lifestyles and Ageing: Targeting Key Mechanisms to Shift the Balance from Unhealthy to Healthy Ageing.

    PubMed

    Grassi, Claudio; Landi, Francesco; Delogu, Giovanni

    2014-01-01

    The increase in life expectancy has dramatically enhanced the prevalence of age-related chronic diseases resulting in growing costs for both society and individuals. Identification of strategies contributing to healthy ageing is thus one of the major challenges of the coming years. Lifestyle has a primary role among non-genetic factors affecting health and lifespan. In particular, nutrition, mental and physical activity impact the molecular and functional mechanisms whose alterations cause the major age-related diseases. A better understanding of mechanisms underlying the beneficial action of correct lifestyles is useful to develop interventions aimed at preventing and/or delaying the onset of chronic degenerative diseases, to identify high-risk populations who could be targeted in intervention trials as well as to identify novel biomarkers of healthy ageing. A multidisciplinary team of basic scientists and clinicians operating at the Catholic University Medical School in Rome is actively working on this topic to determine the ability of healthy lifestyles to promote active ageing and counteract the major age-related diseases affecting brain health, musculoskeletal function and gut microenvironment. This chapter summarizes our strategic approaches, the major results we obtained so far and the main experimental and translational perspectives.

  17. Characterizing mechanical effects of aging damage

    SciTech Connect

    Sewell, T.D.; Chen, S.P.; Schoonover, J.R.; Trent, B.C.; Howe, P.M.; Hjelm, R.P.; Browning, R.V.

    1998-12-01

    This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The goal was to develop and apply several different experimental and theoretical/computational tools to better understand physical and chemical aging phenomena in plastic-bonded high explosives, and to develop a methodology for predicting the likely effects of aging on the mechanical properties of the composite based on input from these fundamental studies. Initial comparisons were done for spectra of fresh and aged Esane, as well as PBX-9501, and the authors found differences in the carbonyl region of the spectrum, which possibly reflect differences in hydrogen bonding due to aging phenomena. The micromechanical model of composites was extended to study various volume fractions of HMX with binders. The results showed that, as the binder fraction increases, there is a decrease in the maximum stress that can be supported but an increase in the percent strain at final fracture. A more realistic microstructural model was obtained through the use of a phase field model. Using this model, the authors have studied the microstructural evolution as a function of the grain boundary energy vs. misorientation relationship. The initial results indicate that there are some changes in the grain growth rate when the grain-boundary energy dependence on the angle is not constant. They also find that solute tends to segregate at the grain boundary and slows the grain growth kinetics.

  18. Do age-friendly characteristics influence the expectation to age in place? A comparison of low-income and higher income Detroit elders.

    PubMed

    Lehning, Amanda J; Smith, Richard J; Dunkle, Ruth E

    2015-03-01

    Currently there is limited evidence linking age-friendly characteristics to outcomes in elders. Using a representative sample of 1,376 adults aged 60 and older living in Detroit, this study examined the association between age-friendly social and physical environmental characteristics and the expectation to age in place, and the potential differences between low- and higher-income elders. Based on U.S. Environmental Protection Agency's (EPA) age-friendly guide, we identified six factors reflecting age-friendly characteristics. Logistic regression models indicated that regardless of income level only neighborhood problems were significantly associated with expecting to age in place. Low-income elders were more likely to expect to age in place than their higher-income counterparts, and it is unclear whether this resulted from a desire to remain in the home or that there is no place else to go. Future research should address the ways in which financial resources affect the choices, expectations, and outcomes of aging in place.

  19. Teaching Traditional and Non-Traditional Age Individuals: How Should Methods, Expectations, and Standards Differ?

    ERIC Educational Resources Information Center

    Sagaria, Sabato D.

    A study examined achievement and attitudes of traditional and nontraditional age students enrolled in an undergraduate behavioral sciences statistics course. Performance and attitude data were collected from a class of 25 traditional students (average age 22) and from a class of 15 nontraditional students (average age 35). The two groups were…

  20. Stagnating Life Expectancies and Future Prospects in an Age of Uncertainty*

    PubMed Central

    Denney, Justin T.; McNown, Robert; Rogers, Richard G.; Doubilet, Steven

    2014-01-01

    Objective This article provides a timely assessment of U.S. life expectancy given recent stalls in the growth of length of life, the continuing drop in international rankings of life expectancy for the U.S., and during a period of growing social and economic insecurity. Methods Time series analysis is used on over 70 years of data from the Human Mortality Database to forecast future life expectancy to the year 2055. Results The results show limited improvements in U.S. life expectancy at birth, less than 3 years on average, for both men and women. Conclusions Even in uncertain times, it is important to look forward in preparing for the needs of future populations. The results presented here underscore the relevance of policy and health initiatives aimed at improving the nation’s health and reveal important insight into possible limits to mortality improvement over the next five decades. PMID:25506092

  1. Epigenetic Mechanisms of the Aging Human Retina.

    PubMed

    Pennington, Katie L; DeAngelis, Margaret M

    2015-01-01

    Degenerative retinal diseases, such as glaucoma, age-related macular degeneration, and diabetic retinopathy, have complex etiologies with environmental, genetic, and epigenetic contributions to disease pathology. Much effort has gone into elucidating both the genetic and the environmental risk factors for these retinal diseases. However, little is known about how these genetic and environmental risk factors bring about molecular changes that lead to pathology. Epigenetic mechanisms have received extensive attention of late for their promise of bridging the gap between environmental exposures and disease development via their influence on gene expression. Recent studies have identified epigenetic changes that associate with the incidence and/or progression of each of these retinal diseases. Therefore, these epigenetic modifications may be involved in the underlying pathological mechanisms leading to blindness. Further genome-wide epigenetic studies that incorporate well-characterized tissue samples, consider challenges similar to those relevant to gene expression studies, and combine the genome-wide epigenetic data with genome-wide genetic and expression data to identify additional potentially causative agents of disease are needed. Such studies will allow researchers to create much-needed therapeutics to prevent and/or intervene in disease progression. Improved therapeutics will greatly enhance the quality of life and reduce the burden of disease management for millions of patients living with these potentially blinding conditions.

  2. Epigenetic Mechanisms of the Aging Human Retina

    PubMed Central

    Pennington, Katie L.; DeAngelis, Margaret M.

    2015-01-01

    Degenerative retinal diseases, such as glaucoma, age-related macular degeneration, and diabetic retinopathy, have complex etiologies with environmental, genetic, and epigenetic contributions to disease pathology. Much effort has gone into elucidating both the genetic and the environmental risk factors for these retinal diseases. However, little is known about how these genetic and environmental risk factors bring about molecular changes that lead to pathology. Epigenetic mechanisms have received extensive attention of late for their promise of bridging the gap between environmental exposures and disease development via their influence on gene expression. Recent studies have identified epigenetic changes that associate with the incidence and/or progression of each of these retinal diseases. Therefore, these epigenetic modifications may be involved in the underlying pathological mechanisms leading to blindness. Further genome-wide epigenetic studies that incorporate well-characterized tissue samples, consider challenges similar to those relevant to gene expression studies, and combine the genome-wide epigenetic data with genome-wide genetic and expression data to identify additional potentially causative agents of disease are needed. Such studies will allow researchers to create much-needed therapeutics to prevent and/or intervene in disease progression. Improved therapeutics will greatly enhance the quality of life and reduce the burden of disease management for millions of patients living with these potentially blinding conditions. PMID:26966390

  3. The Pygmalion Principle: The Practicum Expectations and Experiences of Mature Aged Student Teachers

    ERIC Educational Resources Information Center

    Etherington, Matthew

    2011-01-01

    This study was part of a larger on-going study that is examining the Pygmalion Principle for the practicum experiences of six mature-age student-teachers. The participants are former graduates with university degrees and aged from 36 to 49. They have extensive career backgrounds unrelated to classroom teaching. For this part of the larger study,…

  4. The Influence of Age and Type of Job on Gender Differences in Pay Expectations.

    ERIC Educational Resources Information Center

    Gasser, Michael B.; Oliver, Jennifer A.; Tan, Rowena N.

    1998-01-01

    Elementary school, secondary school, and college students rated 12 jobs divided between primarily female, primarily male, and gender-neutral occupations according to how much they should make if they were in the occupation. A significant interaction was found between type of job and gender for pay expectations. Suggestions for use in applied…

  5. The Effects of Child Age and Label on Instructor Expectation and Performance.

    ERIC Educational Resources Information Center

    Toner, Ignatius J.; Hagan, Margaret S.

    The present study explored the dynamics of expectancy effects. The process by which labels about children provided to adults (but not to the children themselves) achieve their outcomes was investigated. Forty-eight undergraduate females were provided with information about children whom they were to instruct; each undergraduate was then…

  6. That note sounds wrong! Age-related effects in processing of musical expectation.

    PubMed

    Halpern, Andrea R; Zioga, Ioanna; Shankleman, Martin; Lindsen, Job; Pearce, Marcus T; Bhattacharya, Joydeep

    2017-04-01

    Part of musical understanding and enjoyment stems from the ability to accurately predict what note (or one of a small set of notes) is likely to follow after hearing the first part of a melody. Selective violation of expectations can add to aesthetic response but radical or frequent violations are likely to be disliked or not comprehended. In this study we investigated whether a lifetime of exposure to music among untrained older adults would enhance their reaction to unexpected endings of unfamiliar melodies. Older and younger adults listened to melodies that had expected or unexpected ending notes, according to Western music theory. Ratings of goodness-of-fit were similar in the groups, as was ERP response to the note onset (N1). However, in later time windows (P200 and Late Positive Component), the amplitude of a response to unexpected and expected endings was both larger in older adults, corresponding to greater sensitivity, and more widespread in locus, consistent with a dedifferentiation pattern. Lateralization patterns also differed. We conclude that older adults refine their understanding of this important aspect of music throughout life, with the ability supported by changing patterns of neural activity.

  7. Age- and gender-specific epistasis between ADA and TNF-α influences human life-expectancy.

    PubMed

    Napolioni, Valerio; Carpi, Francesco M; Giannì, Paola; Sacco, Roberto; Di Blasio, Luca; Mignini, Fiorenzo; Lucarini, Nazzareno; Persico, Antonio M

    2011-11-01

    Aging is a complex phenotype with multiple determinants but a strong genetic component significantly impacts on survival to extreme ages. The dysregulation of immune responses occurring with increasing age is believed to contribute to human morbidity and mortality. Conversely, some genetic determinants of successful aging might reside in those polymorphisms for the immune system genes regulating immune responses. Here we examined the main effects of single loci and multi-locus interactions to test the hypothesis that the adenosine deaminase (ADA) and tumor necrosis factor alpha (TNF-α) genes may influence human life-expectancy. ADA (22G>A, rs73598374) and TNF-α (-308G>A, rs1800629; -238G>A, rs361525) functional SNPs have been determined for 1071 unrelated healthy individuals from Central Italy (18-106 years old) divided into three gender-specific age classes defined according to demographic information and accounting for the different survivals between sexes: for men (women), the first class consists of individuals<66 years old (<73 years old), the second class of individuals 66-88 years old (73-91 years old), and the third class of individuals>88 years old (>91 years old). Single-locus analysis showed that only ADA 22G>A is significantly associated with human life-expectancy in males (comparison 1 (age class 2 vs. age class 1), O.R. 1.943, P=0.036; comparison 2 (age class 3 vs. age class 2), O.R. 0.320, P=0.0056). Age- and gender-specific patterns of epistasis between ADA and TNF-α were found using Generalized Multifactor Dimensionality Reduction (GMDR). In comparison 1, a significant two-loci interaction occurs in females between ADA 22G>A and TNF-α -238G>A (Sign Test P=0.011). In comparison 2, both two-loci and three-loci interaction are significant associated with increased life-expectancy over 88 years in males. In conclusion, we report that a combination of functional SNPs within ADA and TNF-α genes can influence life-expectancy in a gender

  8. Genetic analysis of mechanisms of aging.

    PubMed

    Rose, M R; Archer, M A

    1996-06-01

    A wide range of genetic models with postponed aging are now available, from selected mice and Drosophilia to mutant Caenorhabditis elegans and Saccharomyces cerevisiae. These systems allow efficient testing of alternative mechanistic hypotheses for aging. Genetic analysis is forging stronger connections between particular alleles and susceptibility to particular 'diseases of aging'; for example, two different genes for Alzheimer disease have been identified.

  9. Impulsivity and the role of smoking-related outcome expectancies among dependent college-aged cigarette smokers.

    PubMed

    Vanderveen, Joseph W; Cohen, Lee M; Trotter, David R M; Collins, Frank L

    2008-08-01

    The relationship between trait-impulsivity and smoking expectancies on smoking progression in undergraduate college students was examined over a 48-hour period of smoking abstinence. Participants were forty-nine college-aged dependent cigarette smokers who completed measures designed to assess impulsivity, nicotine dependence, and smoking expectancies. Using a series of multilevel models, impulsivity by time analyses indicated significant differences in positive reinforcement expectancies, [F (2, 94)=3.19, p<.05], but not in negative reinforcement expectancies, [F (2, 94)=0.49, p=.61]. Simple slopes analyses indicated that heightened trait-impulsivity predicted greater increases in positive reinforcement outcome expectancies at 48 h of abstinence. Level of impulsivity, however, was not related to changes in negative reinforcement expectancies. Results indicate that during an abstinence period, college students higher in trait-impulsivity may be more prone to relapse due to stronger beliefs about the positive effects from smoking a cigarette. These findings highlight the importance of understanding the interaction of personality and cognitive factors when working with young adult smokers wishing to quit this health-compromising behavior.

  10. Is consensus in anti-aging medical intervention an elusive expectation or a realistic goal?

    PubMed

    Zs-Nagy, Imre

    2009-01-01

    One of the biggest scandals of the recent history of medicine is the conflict of views between the gerontological establishment and the American Academy of Anti-Aging Medicine (A4M). The style used in that discussion was really rough and unusual. On the one hand, according to some representatives of the American Medical Associations (AMA), the use of human growth hormone (hGH) for anti-aging medical interventions is illegal, criminal, and requires persecution. On the other hand, A4M is of the opinion that all this is "...filled with incorrect, misplaced references and studies, and multiple basic scientific errors, in an apparent attempt to damage the anti-aging medical profession...". It is evident that in the frame of a short article is impossible to treat all the relevant aspects of this complicated story. Nevertheless, this Editorial attempts to point out the main results obtained so far, together with the most important issues of theoretical feasibility of the hGH replacement therapy (hGHRT). The comprehensive explanation of the aging process called "membrane hypothesis of aging" (MHA) offers a solid basis for the interpretation of the observed beneficial effects of the hGH through its practically ubiquitous membrane receptors, and the species specificity of this peptide hormone. The specific activation of these receptors stimulates the membrane transport functions, rehydrates the intracellular colloids, allowing to speed up the protein synthesis and turnover, and activates a great number of cellular functions, all observed so far. The facts known about the adult growth hormone deficiency (AGHD) syndrome, and the beneficial effects of hGHRT in all aspects of this pathology suggest that aging may generally be considered as an AGHD syndrome. If this concept is accepted by most of the gerontologists, we can resolve practically all problems involved in the above outlined controversies. All this requires an independent, open-minded approach to the problem, and

  11. Parental Spending on School-Age Children: Structural Stratification and Parental Expectation

    PubMed Central

    Hao, Lingxin; Yeung, Wei-Jun Jean

    2015-01-01

    As consumption expenditures are increasingly recognized as direct measures of children’s material well-being, they provide new insights into the process of intergenerational transfers from parents to children. Little is known, however, about how parents allocate financial resources to individual children. To fill this gap, we develop a conceptual framework based on stratification theory, human capital theory, and the child-development perspective; exploit unique child-level expenditure data from Child Supplements of the PSID; and employ quantile regression to model the distribution of parental spending on children. Overall, we find strong evidence supporting our hypotheses regarding the effects of socioeconomic status (SES), race, and parental expectation. Our nuanced estimates suggest that (1) parental education, occupation, and family income have differential effects on parental spending, with education being the most influential determinant; (2) net of SES, race continues to be a significant predictor of parental spending on children; and (3) parental expectation plays a crucial role in determining whether parents place a premium on child development in spending and how parents prioritize different categories of spending. PMID:25933638

  12. Parental Spending on School-Age Children: Structural Stratification and Parental Expectation.

    PubMed

    Hao, Lingxin; Yeung, Wei-Jun Jean

    2015-06-01

    As consumption expenditures are increasingly recognized as direct measures of children's material well-being, they provide new insights into the process of intergenerational transfers from parents to children. Little is known, however, about how parents allocate financial resources to individual children. To fill this gap, we develop a conceptual framework based on stratification theory, human capital theory, and the child-development perspective; exploit unique child-level expenditure data from Child Supplements of the PSID; and employ quantile regression to model the distribution of parental spending on children. Overall, we find strong evidence supporting our hypotheses regarding the effects of socioeconomic status (SES), race, and parental expectation. Our nuanced estimates suggest that (1) parental education, occupation, and family income have differential effects on parental spending, with education being the most influential determinant; (2) net of SES, race continues to be a significant predictor of parental spending on children; and (3) parental expectation plays a crucial role in determining whether parents place a premium on child development in spending and how parents prioritize different categories of spending.

  13. Molecular mechanisms of proteasome plasticity in aging.

    PubMed

    Rodriguez, Karl A; Gaczynska, Maria; Osmulski, Pawel A

    2010-02-01

    The ubiquitin-proteasome pathway plays a crucial role in regulation of intracellular protein turnover. Proteasome, the central protease of the pathway, encompasses multi-subunit assemblies sharing a common catalytic core supplemented by regulatory modules and localizing to different subcellular compartments. To better comprehend age-related functions of the proteasome we surveyed content, composition and catalytic properties of the enzyme in cytosolic, microsomal and nuclear fractions obtained from mouse livers subjected to organismal aging. We found that during aging subunit composition and subcellular distribution of proteasomes changed without substantial alterations in the total level of core complexes. We observed that the general decline in proteasomes functions was limited to nuclear and cytosolic compartments. Surprisingly, the observed changes in activity and specificity were linked to the amount of the activator module and distinct composition of the catalytic subunits. In contrast, activity, specificity and composition of the microsomal-associated proteasomes remained mostly unaffected by aging; however their relative contribution to the total activity was substantially elevated. Unexpectedly, the nuclear proteasomes were affected most profoundly by aging possibly triggering significant changes in cellular signaling and transcription. Collectively, the data indicate an age-related refocusing of proteasome from the compartment-specific functions towards general protein maintenance.

  14. Patch-based Augmentation of Expectation-Maximization for Brain MRI Tissue Segmentation at Arbitrary Age after Premature Birth

    PubMed Central

    Liu, Mengyuan; Kitsch, Averi; Miller, Steven; Chau, Vann; Poskitt, Kenneth; Rousseau, Francois; Shaw, Dennis; Studholme, Colin

    2015-01-01

    Accurate automated tissue segmentation of premature neonatal magnetic resonance images is a crucial task for quantification of brain injury and its impact on early postnatal growth and later cognitive development. In such studies it is common for scans to be acquired shortly after birth or later during the hospital stay and therefore occur at arbitrary gestational ages during a period of rapid developmental change. It is important to be able to segment any of these scans with comparable accuracy. Previous work on brain tissue segmentation in premature neonates has focused on segmentation at specific ages. Here we look at solving the more general problem using adaptations of age specific atlas based methods and evaluate this using a unique manually traced database of high resolution images spanning 20 gestational weeks of development. We examine the complimentary strengths of age specific atlas-based Expectation-Maximization approaches and patch-based methods for this problem and explore the development of two new hybrid techniques, patch-based augmentation of Expectation-Maximization with weighted fusion and a spatial variability constrained patch search. The former approach seeks to combine the advantages of both atlas- and patch-based methods by learning from the performance of the two techniques across the brain anatomy at different developmental ages, while the latter technique aims to use anatomical variability maps learnt from atlas training data to locally constrain the patch-based search range. The proposed approaches were evaluated using leave-one-out cross-validation. Compared with the conventional age specific atlas-based segmentation and direct patch based segmentation, both new approaches demonstrate improved accuracy in the automated labeling of cortical gray matter, white matter, ventricles and sulcal cortical-spinal fluid regions, while maintaining comparable results in deep gray matter. PMID:26702777

  15. Patch-based augmentation of Expectation-Maximization for brain MRI tissue segmentation at arbitrary age after premature birth.

    PubMed

    Liu, Mengyuan; Kitsch, Averi; Miller, Steven; Chau, Vann; Poskitt, Kenneth; Rousseau, Francois; Shaw, Dennis; Studholme, Colin

    2016-02-15

    Accurate automated tissue segmentation of premature neonatal magnetic resonance images is a crucial task for quantification of brain injury and its impact on early postnatal growth and later cognitive development. In such studies it is common for scans to be acquired shortly after birth or later during the hospital stay and therefore occur at arbitrary gestational ages during a period of rapid developmental change. It is important to be able to segment any of these scans with comparable accuracy. Previous work on brain tissue segmentation in premature neonates has focused on segmentation at specific ages. Here we look at solving the more general problem using adaptations of age specific atlas based methods and evaluate this using a unique manually traced database of high resolution images spanning 20 gestational weeks of development. We examine the complimentary strengths of age specific atlas-based Expectation-Maximization approaches and patch-based methods for this problem and explore the development of two new hybrid techniques, patch-based augmentation of Expectation-Maximization with weighted fusion and a spatial variability constrained patch search. The former approach seeks to combine the advantages of both atlas- and patch-based methods by learning from the performance of the two techniques across the brain anatomy at different developmental ages, while the latter technique aims to use anatomical variability maps learnt from atlas training data to locally constrain the patch-based search range. The proposed approaches were evaluated using leave-one-out cross-validation. Compared with the conventional age specific atlas-based segmentation and direct patch based segmentation, both new approaches demonstrate improved accuracy in the automated labeling of cortical gray matter, white matter, ventricles and sulcal cortical-spinal fluid regions, while maintaining comparable results in deep gray matter.

  16. Treatment of Chronic Hepatitis C in the Aged – Does It Impact Life Expectancy? A Decision Analysis

    PubMed Central

    Maor, Yaakov; Malnick, Stephen D. H.; Melzer, Ehud; Leshno, Moshe

    2016-01-01

    Background and Aims Recent studies have demonstrated that the efficacy of interferon-free direct-acting antiviral agents (DAAs) in patients over 70 is similar to that of younger age groups. Evidence continues to mount that life expectancy (LE) increases with successful treatment of hepatitis C (HCV) patients with advanced fibrosis. The evidence in older people is more limited. Our aim was to estimate the life year (LY) and quality-adjusted life year (QALY) gained by treatment of naïve patients with HCV as a function of patient's age and fibrosis stage. Methods We constructed a Markov model of HCV progression toward advanced liver disease. The primary outcome was LY and QALY saved. The model and the sustained virological response of HCV infected subjects treated with a fixed-dose combination of the NS5B polymerase inhibitor Sofosbuvir and the NS5A replication complex inhibitor Ledipasvir were based on the published literature and expert opinion. Results Generally, both the number of LY gained and QALY gained gradually decreased with advancing age but the rate of decline was slower with more advanced fibrosis stage. For patients with fibrosis stage F1, F2 and F3, LY gained dropped below six months if treated by the age of 55, 65 or 70 years, respectively, while for a patient with fibrosis stage F4, the gain was one LY if treated by the age of 75. The QALY gained for treated over untreated elderly were reasonably high even for those treated at early fibrosis stage. Conclusions There is a significant life expectancy benefit to HCV treatment in patients up to age 75 with advanced-stage fibrosis. PMID:27410963

  17. Age Related Decline in Postural Control Mechanisms.

    ERIC Educational Resources Information Center

    Stelmach, George E.; And Others

    1989-01-01

    Studied voluntary and reflexive mechanisms of postural control of young (N=8) and elderly (N=8) adults through measurement of reflexive reactions to large-fast and small-slow ankle rotation postural disturbances. Found reflexive mechanisms relatively intact for both groups although elderly appeared more disadvantaged when posture was under the…

  18. Differences in Family Size and Marriage Age Expectation and Aspirations of Anglo, Mexican American and Native American Rural Youth in New Mexico.

    ERIC Educational Resources Information Center

    Edington, Everett; Hays, Leonard

    1978-01-01

    In 1975, questionnaires were given to 587 sophomores and seniors in 12 rural high schools. Findings included significant differences between ethnic groups on expected and desired family size and marriage age; but no differences between age groups. (Author/SJL)

  19. Lysosomal cell death mechanisms in aging.

    PubMed

    Gómez-Sintes, Raquel; Ledesma, María Dolores; Boya, Patricia

    2016-12-01

    Lysosomes are degradative organelles essential for cell homeostasis that regulate a variety of processes, from calcium signaling and nutrient responses to autophagic degradation of intracellular components. Lysosomal cell death is mediated by the lethal effects of cathepsins, which are released into the cytoplasm following lysosomal damage. This process of lysosomal membrane permeabilization and cathepsin release is observed in several physiopathological conditions and plays a role in tissue remodeling, the immune response to intracellular pathogens and neurodegenerative diseases. Many evidences indicate that aging strongly influences lysosomal activity by altering the physical and chemical properties of these organelles, rendering them more sensitive to stress. In this review we focus on how aging alters lysosomal function and increases cell sensitivity to lysosomal membrane permeabilization and lysosomal cell death, both in physiological conditions and age-related pathologies.

  20. Cell-Nonautonomous Mechanisms Underlying Cellular and Organismal Aging.

    PubMed

    Medkour, Younes; Svistkova, Veronika; Titorenko, Vladimir I

    2016-01-01

    Cell-autonomous mechanisms underlying cellular and organismal aging in evolutionarily distant eukaryotes have been established; these mechanisms regulate longevity-defining processes within a single eukaryotic cell. Recent findings have provided valuable insight into cell-nonautonomous mechanisms modulating cellular and organismal aging in eukaryotes across phyla; these mechanisms involve a transmission of various longevity factors between different cells, tissues, and organisms. Herein, we review such cell-nonautonomous mechanisms of aging in eukaryotes. We discuss the following: (1) how low molecular weight transmissible longevity factors modulate aging and define longevity of cells in yeast populations cultured in liquid media or on solid surfaces, (2) how communications between proteostasis stress networks operating in neurons and nonneuronal somatic tissues define longevity of the nematode Caenorhabditis elegans by modulating the rates of aging in different tissues, and (3) how different bacterial species colonizing the gut lumen of C. elegans define nematode longevity by modulating the rate of organismal aging.

  1. Factors of skin ageing share common mechanisms.

    PubMed

    Giacomoni, P U; Rein, G

    2001-01-01

    Ageing has been defined as the accumulation of molecular modifications which manifest as macroscopic clinical changes. Human skin, unique among mammalians insofar as it is deprived of fur, is particularly sensitive to environmental stress. Major environmental factors have been recognized to induce modifications of the morphological and biophysical properties of the skin. Metabolites from ingested or inhaled substances do affect skin, which is also sensitive to endogenous hormone levels. Factors as diverse as ultraviolet radiation, atmospheric pollution, wounds, infections, traumatisms, anoxya, cigarette smoke, and hormonal status have a role in increasing the rate of accumulation of molecular modifications and have thus been termed 'factors of ageing'. All these factors share as a common feature, the capability to directly or indirectly induce one of the steps of the micro-inflammatory cycle, which includes the expression of ICAM-1 in endothelial cells. This triggers a process leading to the accumulation of damages in the skin resulting in skin ageing since ICAM-1 expression provokes recruitment and diapedesis of circulating immune cells, which digest the extracellular matrix (ECM) by secreting collagenases, myeloperoxidases and reactive oxygen species. The activation of these lytic processes provokes random damage to resident cells, which in turn secrete prostaglandines and leukotrienes. These signaling molecules induce the degranulation of resident mast cells which release the autacoid histamine and the cytokine TNF-alpha thus activating endothelial cells lining adjacent capillaries which release P-selectin and synthesize ICAM-1. This closes a self-maintained micro-inflammatory cycle, which results in the accumulation of ECM damage, i.e. skin aging. In this paper we review the evidence that two factors able to induce macroscopical and molecular modifications in the skin, protein glycation and stretch, activate the micro-inflammatory cycle. We further present

  2. An Observational Study of Teachers' Expectancy Effects and Their Mediating Mechanisms.

    ERIC Educational Resources Information Center

    Crowe, Patricia B.

    The theory that teachers treat students from whom they expect superior achievement differently than those from whom they expect inferior performance is examined. Five ways of reacting on the part of the teacher are identified for the purpose of this study--teacher warmth, teacher feedback, teacher selection of materials, opportunity offered for…

  3. Smoking Abstinence-related Expectancies among American Indians, African Americans, and Women: Potential Mechanisms of Tobacco-related Disparities

    PubMed Central

    Hendricks, Peter S.; Westmaas, J. Lee; Park, Van M. Ta; Thorne, Christopher B.; Wood, Sabrina B.; Baker, Majel R.; Lawler, R. Marsh; Hooper, Monica Webb; Delucchi, Kevin L.; Hall, Sharon M.

    2014-01-01

    Research has documented tobacco-related health disparities by race and gender. Prior research, however, has not examined expectancies about the smoking cessation process (i.e., abstinence-related expectancies) as potential contributors to tobacco-related disparities in special populations. This cross-sectional study compared abstinence-related expectancies between American Indian (n = 87), African American (n = 151), and White (n = 185) smokers, and between women (n = 231) and men (n = 270) smokers. Abstinence-related expectancies also were examined as mediators of race and gender relationships with motivation to quit and abstinence self-efficacy. Results indicated that American Indians and African Americans were less likely than Whites to expect withdrawal effects, and more likely to expect that quitting would be unproblematic. African Americans also were less likely than Whites to expect smoking cessation interventions to be effective. Compared to men, women were more likely to expect withdrawal effects and weight gain.These expectancy differences mediated race and gender relationships with motivation to quit and abstinence self-efficacy. Findings emphasize potential mechanisms underlying tobacco-related health disparities among American Indians, African Americans, and women, and suggest a number of specific approaches for targeting tobacco dependence interventions to these populations. PMID:23528192

  4. Iron and ageing: an introduction to iron regulatory mechanisms.

    PubMed

    Levenson, Cathy W; Tassabehji, Nadine M

    2004-07-01

    While there have been significant advances made in our understanding of the cellular and molecular mechanisms that regulate iron absorption, transport, storage, and utilization, the effect of ageing on these mechanisms and the role of iron in the ageing process is not fully understood. Thus, this review will provide an overview of the iron regulatory mechanisms that may be a factor in the ageing process. Additional reviews in this volume represent an attempt to explore the very latest information on the regulation of iron with a particular emphasis on age-related pathology including mitochondrial function, Parkinson's disease, Alzheimer's disease, stroke, and cardiovascular disease.

  5. An Update on Inflamm-Aging: Mechanisms, Prevention, and Treatment

    PubMed Central

    Wu, Junzhen

    2016-01-01

    Inflamm-aging is a challenging and promising new branch of aging-related research fields that includes areas such as immunosenescence. Increasing evidence indicates that inflamm-aging is intensively associated with many aging diseases, such as Alzheimer's disease, atherosclerosis, heart disease, type II diabetes, and cancer. Mounting studies have focused on the role of inflamm-aging in disease progression and many advances have been made in the last decade. However, the underlying mechanisms by which inflamm-aging affects pathological changes and disease development are still unclear. Here, we review studies of inflamm-aging that explore the concept, pathological features, mechanisms, intervention, and the therapeutic strategies of inflamm-aging in disease progression. PMID:27493973

  6. Aging: What to Expect

    MedlinePlus

    ... you can do To promote heart health: Include physical activity in your daily routine. Try walking, swimming or other activities you enjoy. Regular moderate physical activity can help you maintain a healthy weight, lower ...

  7. Recursive expectation-maximization clustering: A method for identifying buffering mechanisms composed of phenomic modules

    NASA Astrophysics Data System (ADS)

    Guo, Jingyu; Tian, Dehua; McKinney, Brett A.; Hartman, John L.

    2010-06-01

    Interactions between genetic and/or environmental factors are ubiquitous, affecting the phenotypes of organisms in complex ways. Knowledge about such interactions is becoming rate-limiting for our understanding of human disease and other biological phenomena. Phenomics refers to the integrative analysis of how all genes contribute to phenotype variation, entailing genome and organism level information. A systems biology view of gene interactions is critical for phenomics. Unfortunately the problem is intractable in humans; however, it can be addressed in simpler genetic model systems. Our research group has focused on the concept of genetic buffering of phenotypic variation, in studies employing the single-cell eukaryotic organism, S. cerevisiae. We have developed a methodology, quantitative high throughput cellular phenotyping (Q-HTCP), for high-resolution measurements of gene-gene and gene-environment interactions on a genome-wide scale. Q-HTCP is being applied to the complete set of S. cerevisiae gene deletion strains, a unique resource for systematically mapping gene interactions. Genetic buffering is the idea that comprehensive and quantitative knowledge about how genes interact with respect to phenotypes will lead to an appreciation of how genes and pathways are functionally connected at a systems level to maintain homeostasis. However, extracting biologically useful information from Q-HTCP data is challenging, due to the multidimensional and nonlinear nature of gene interactions, together with a relative lack of prior biological information. Here we describe a new approach for mining quantitative genetic interaction data called recursive expectation-maximization clustering (REMc). We developed REMc to help discover phenomic modules, defined as sets of genes with similar patterns of interaction across a series of genetic or environmental perturbations. Such modules are reflective of buffering mechanisms, i.e., genes that play a related role in the maintenance

  8. Recursive expectation-maximization clustering: a method for identifying buffering mechanisms composed of phenomic modules.

    PubMed

    Guo, Jingyu; Tian, Dehua; McKinney, Brett A; Hartman, John L

    2010-06-01

    Interactions between genetic and/or environmental factors are ubiquitous, affecting the phenotypes of organisms in complex ways. Knowledge about such interactions is becoming rate-limiting for our understanding of human disease and other biological phenomena. Phenomics refers to the integrative analysis of how all genes contribute to phenotype variation, entailing genome and organism level information. A systems biology view of gene interactions is critical for phenomics. Unfortunately the problem is intractable in humans; however, it can be addressed in simpler genetic model systems. Our research group has focused on the concept of genetic buffering of phenotypic variation, in studies employing the single-cell eukaryotic organism, S. cerevisiae. We have developed a methodology, quantitative high throughput cellular phenotyping (Q-HTCP), for high-resolution measurements of gene-gene and gene-environment interactions on a genome-wide scale. Q-HTCP is being applied to the complete set of S. cerevisiae gene deletion strains, a unique resource for systematically mapping gene interactions. Genetic buffering is the idea that comprehensive and quantitative knowledge about how genes interact with respect to phenotypes will lead to an appreciation of how genes and pathways are functionally connected at a systems level to maintain homeostasis. However, extracting biologically useful information from Q-HTCP data is challenging, due to the multidimensional and nonlinear nature of gene interactions, together with a relative lack of prior biological information. Here we describe a new approach for mining quantitative genetic interaction data called recursive expectation-maximization clustering (REMc). We developed REMc to help discover phenomic modules, defined as sets of genes with similar patterns of interaction across a series of genetic or environmental perturbations. Such modules are reflective of buffering mechanisms, i.e., genes that play a related role in the maintenance

  9. Mechanisms Underlying T Cell Immunosenescence: Aging and Cytomegalovirus Infection

    PubMed Central

    Tu, Wenjuan; Rao, Sudha

    2016-01-01

    The ability of the human immune system to protect against infectious disease declines with age and efficacy of vaccination reduces significantly in the elderly. Aging of the immune system, also termed as immunosenescence, involves many changes in human T cell immunity that is characterized by a loss in naïve T cell population and an increase in highly differentiated CD28- memory T cell subset. There is extensive data showing that latent persistent human cytomegalovirus (HCMV) infection is also associated with age-related immune dysfunction in the T cells, which might enhance immunosenescence. Understanding the molecular mechanisms underlying age-related and HCMV-related immunosenescence is critical for the development of effective age-targeted vaccines and immunotherapies. In this review, we will address the role of both aging and HCMV infection that contribute to the T cell senescence and discuss the potential molecular mechanisms in aged T cells. PMID:28082969

  10. National Health Expenditure Projections, 2015-25: Economy, Prices, And Aging Expected To Shape Spending And Enrollment.

    PubMed

    Keehan, Sean P; Poisal, John A; Cuckler, Gigi A; Sisko, Andrea M; Smith, Sheila D; Madison, Andrew J; Stone, Devin A; Wolfe, Christian J; Lizonitz, Joseph M

    2016-08-01

    Health spending growth in the United States for 2015-25 is projected to average 5.8 percent-1.3 percentage points faster than growth in the gross domestic product-and to represent 20.1 percent of the total economy by 2025. As the initial impacts associated with the Affordable Care Act's coverage expansions fade, growth in health spending is expected to be influenced by changes in economic growth, faster growth in medical prices, and population aging. Projected national health spending growth, though faster than observed in the recent history, is slower than in the two decades before the recent Great Recession, in part because of trends such as increasing cost sharing in private health insurance plans and various Medicare payment update provisions. In addition, the share of total health expenditures paid for by federal, state, and local governments is projected to increase to 47 percent by 2025.

  11. Functional Significance of Conflicting Age and Wealth Cross-Categorization: The Dominant Role of Categories That Violate Stereotypical Expectations

    PubMed Central

    Song, Jingjing; Zuo, Bin

    2016-01-01

    The purpose of the current study was to identify the functional significance of conflicting stereotypes and to identify the dominant category in such conflicts. In the present research we examined the conflicting crossed categories of age and wealth with regard to warmth and competence perceptions. It was found (Pilot Study and Study 1) that the old-rich targets presented a conflicting stereotype group in the perception of warmth, whereas young-poor targets presented a conflicting stereotype group in the perception of competence. In addition, the old stereotype dominated the warmth evaluation of old-rich targets, whereas the poor stereotype dominated the competence evaluation of young-poor targets. In Study 2, participants provided warmth and competence evaluations after they learned about the targets' behaviors which demonstrated high or low warmth and high or low competence. The results suggest that for the warmth evaluation of the old-rich target the category that did not match the behavior (i.e., contradicted the stereotype expectation) was more salient and drove judgments. However, the effect of stereotype expectation violation was not found in the competence evaluation of the young-poor target. The results are discussed in terms of their implications for understanding factors that activate and inhibit stereotyped perceptions. PMID:27818640

  12. Distinct Mechanisms of Impairment in Cognitive Ageing and Alzheimer's Disease

    ERIC Educational Resources Information Center

    Mapstone, Mark; Dickerson, Kathryn; Duffy, Charles J.

    2008-01-01

    Similar manifestations of functional decline in ageing and Alzheimer's disease obscure differences in the underlying cognitive mechanisms of impairment. We sought to examine the contributions of top-down attentional and bottom-up perceptual factors to visual self-movement processing in ageing and Alzheimer's disease. We administered a novel…

  13. Molecular Mechanisms of Biological Aging in Intervertebral Discs

    PubMed Central

    Vo, Nam V.; Hartman, Robert A.; Patil, Prashanti R.; Risbud, Makarand V.; Kletsas, Dimitris; Iatridis, James C.; Hoyland, Judith A.; Le Maitre, Christine L.; Sowa, Gwendolyn A.; Kang, James D.

    2016-01-01

    Advanced age is the greatest risk factor for the majority of human ailments, including spine-related chronic disability and back pain, which stem from age-associated intervertebral disc degeneration (IDD). Given the rapid global rise in the aging population, understanding the biology of intervertebral disc aging in order to develop effective therapeutic interventions to combat the adverse effects of aging on disc health is now imperative. Fortunately, recent advances in aging research have begun to shed light on the basic biological process of aging. Here we review some of these insights and organize the complex process of disc aging into three different phases to guide research efforts to understand the biology of disc aging. The objective of this review is to provide an overview of the current knowledge and the recent progress made to elucidate specific molecular mechanisms underlying disc aging. In particular, studies over the last few years have uncovered cellular senescence and genomic instability as important drivers of disc aging. Supporting evidence comes from DNA repair-deficient animal models that show increased disc cellular senescence and accelerated disc aging. Additionally, stress-induced senescent cells have now been well documented to secrete catabolic factors, which can negatively impact the physiology of neighboring cells and ECM. These along with other molecular drivers of aging are reviewed in depth to shed crucial insights into the underlying mechanisms of age-related disc degeneration. We also highlight molecular targets for novel therapies and emerging candidate therapeutics that may mitigate age-associated IDD. PMID:26890203

  14. Epigenetic mechanisms facilitating oligodendrocyte development, maturation, and aging.

    PubMed

    Copray, Sjef; Huynh, Jimmy Long; Sher, Falak; Casaccia-Bonnefil, Patrizia; Boddeke, Erik

    2009-11-15

    The process of oligodendrocyte differentiation is regulated by a dynamic interaction between a genetic and an epigenetic program. Recent studies, addressing nucleosomal histone modifications have considerably increased our knowledge regarding epigenetic regulation of gene expression during oligodendrocyte development and aging. These results have generated new hypotheses regarding the mechanisms underlying the decreased efficiency of endogenous remyelination in response to demyelinating injuries with increasing age. In this review, we present an overview of the epigenetic mechanisms regulating gene expression at specific stages of oligodendrocyte differentiation and maturation as well as the changes that occur with aging.

  15. Mechanisms of the anorexia of aging-a review.

    PubMed

    Wysokiński, Adam; Sobów, Tomasz; Kłoszewska, Iwona; Kostka, Tomasz

    2015-08-01

    Many, even healthy, older people fail to adequately regulate food intake and experience loss of weight. Aging-associated changes in the regulation of appetite and the lack of hunger have been termed as the anorexia of aging. The etiology of the anorexia of aging is multi-factorial and includes a combination of physiological changes associated with aging (decline in smell and taste, reduced central and peripheral drive to eat, delayed gastric emptying), pathological conditions (depression, dementia, somatic diseases, medications and iatrogenic interventions, oral-health status), and social factors (poverty, loneliness). However, exact mechanisms of the anorexia of aging remain to be elucidated. Many neurobiological mechanisms may be secondary to age-related changes in body composition and not associated with anorexia per se. Therefore, further studies on pathophysiological mechanisms of the anorexia of aging should employ accurate measurement of body fat and lean mass. The anorexia of aging is associated with protein-energy malnutrition, sarcopenia, frailty, functional deterioration, morbidity, and mortality. Since this symptom can lead to dramatic consequences, early identification and effective interventions are needed. One of the most important goals in the geriatric care is to optimize nutritional status of the elderly.

  16. Mechanisms of aging-related proteinopathies in Caenorhabditis elegans

    PubMed Central

    Kim, Dong-Kyu; Kim, Tae Ho; Lee, Seung-Jae

    2016-01-01

    Aging is the most important risk factor for human neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Pathologically, these diseases are characterized by the deposition of specific protein aggregates in neurons and glia, representing the impairment of neuronal proteostasis. However, the mechanism by which aging affects the proteostasis system and promotes protein aggregation remains largely unknown. The short lifespan and ample genetic resources of Caenorhabditis elegans (C. elegans) have made this species a favorite model organism for aging research, and the development of proteinopathy models in this organism has helped us to understand how aging processes affect protein aggregation and neurodegeneration. Here, we review the recent literature on proteinopathies in C. elegans models and discuss the insights we have gained into the mechanisms of how aging processes are integrated into the pathogenesis of various neurodegenerative diseases. PMID:27713398

  17. Novel putative mechanisms to link circadian clocks to healthy aging.

    PubMed

    Popa-Wagner, Aurel; Catalin, Bogdan; Buga, Ana-Maria

    2015-08-01

    The circadian clock coordinates the internal physiology to increase the homeostatic capacity thereby providing both a survival advantage to the system and an optimization of energy budgeting. Multiple-oscillator circadian mechanisms are likely to play a role in regulating human health and may contribute to the aging process. Our aim is to give an overview of how the central clock in the hypothalamus and peripheral clocks relate to aging and metabolic disorders, including hyperlipidemia and hyperglycemia. In particular, we unravel novel putative mechanisms to link circadian clocks to healthy aging. This review may lead to the design of large-scale interventions to help people stay healthy as they age by adjusting daily activities, such as feeding behavior, and or adaptation to age-related changes in individual circadian rhythms.

  18. Comparison of mice with accelerated aging caused by distinct mechanisms

    PubMed Central

    Gurkar, Aditi U.; Niedernhofer, Laura J.

    2015-01-01

    Aging is the primary risk factor for numerous chronic, debilitating diseases. These diseases impact quality of life of the elderly and consume a large portion of health care costs. The cost of age-related diseases will only increase as the world's population continues to live longer. Thus it would be advantageous to consider aging itself as a therapeutic target, potentially stemming multiple age-related diseases simultaneously. While logical, this is extremely challenging as the molecular mechanisms that drive aging are still unknown. Furthermore, clinical trials to treat aging are impractical. Even in preclinical models, testing interventions to extend healthspan in old age is lengthy and therefore costly. One approach to expedite aging studies is to take advantage of mouse strains that are engineered to age rapidly. These strains are genetically and phenotypically quite diverse. This review aims to offer a comparison of several of these strains to highlight their relative strengths and weaknesses as models of mammalian and more specifically human aging. Additionally, careful identification of commonalities amongst the strains may lead to the identification of fundamental pathways of aging. PMID:25617508

  19. [Gains in life expectancy at birth in Brazil after the year 2000: the impact of mortality variations by age and cause of death].

    PubMed

    Corrêa, Érika Ribeiro Pereira; Miranda-Ribeiro, Adriana de

    2017-03-01

    Life expectancy at birth is a synthetic mortality indicator that reflects the general living conditions of the population. Changes in mortality by age and causes of death generate no explicit changes in the indicator. The application of a decomposition method can bring light to the analysis of the phenomenon. The aim of this study was to estimate the contribution of age groups and causes of death in the variation in life expectancy at birth, for men and women, from 2000 to 2010, by applying Pollard's decomposition method. Brazilian life tables were obtained from IBGE and death data from SIM. The results indicate that the age group that most contributed to the increase in life expectancy was of less than 1 year old. Among the defined causes, cardiovascular diseases were responsible for the largest increase in life expectancy.

  20. Programmatic features of aging originating in development: aging mechanisms beyond molecular damage?

    PubMed Central

    de Magalhães, João Pedro

    2012-01-01

    The idea that aging follows a predetermined sequence of events, a program, has been discredited by most contemporary authors. Instead, aging is largely thought to occur due to the accumulation of various forms of molecular damage. Recent work employing functional genomics now suggests that, indeed, certain facets of mammalian aging may follow predetermined patterns encoded in the genome as part of developmental processes. It appears that genetic programs coordinating some aspects of growth and development persist into adulthood and may become detrimental. This link between development and aging may occur due to regulated processes, including through the action of microRNAs and epigenetic mechanisms. Taken together with other results, in particular from worms, these findings provide evidence that some aging changes are not primarily a result of a build-up of stochastic damage but are rather a product of regulated processes. These processes are interpreted as forms of antagonistic pleiotropy, the product of a “shortsighted watchmaker,” and thus do not assume aging evolved for a purpose. Overall, it appears that the genome does, indeed, contain specific instructions that drive aging in animals, a radical shift in our perception of the aging process.—de Magalhães, J. P. Programmatic features of aging originating in development: aging mechanisms beyond molecular damage? PMID:22964300

  1. Mechanisms Involved in the Aging-Induced Vascular Dysfunction

    PubMed Central

    El Assar, Mariam; Angulo, Javier; Vallejo, Susana; Peiró, Concepción; Sánchez-Ferrer, Carlos F.; Rodríguez-Mañas, Leocadio

    2012-01-01

    Vascular aging is a key process determining health status of aged population. Aging is an independent cardiovascular risk factor associated to an impairment of endothelial function, which is a very early and important event leading to cardiovascular disease. Vascular aging, formerly being considered an immutable and inexorable risk factor, is now viewed as a target process for intervention in order to achieve a healthier old age. A further knowledge of the mechanisms underlying the age-related vascular dysfunction is required to design an adequate therapeutic strategy to prevent or restore this impairment of vascular functionality. Among the proposed mechanisms that contribute to age-dependent endothelial dysfunction, this review is focused on the following aspects occurring into the vascular wall: (1) the reduction of nitric oxide (NO) bioavailability, caused by diminished NO synthesis and/or by augmented NO scavenging due to oxidative stress, leading to peroxynitrite formation (ONOO−); (2) the possible sources involved in the enhancement of oxidative stress; (3) the increased activity of vasoconstrictor factors; and (4) the development of a low-grade pro-inflammatory environment. Synergisms and interactions between all these pathways are also analyzed. Finally, a brief summary of some cellular mechanisms related to endothelial cell senescence (including telomere and telomerase, stress-induced senescence, as well as sirtuins) are implemented, as they are likely involved in the age-dependent endothelial dysfunction, as well as in the lower vascular repairing capacity observed in the elderly. Prevention or reversion of those mechanisms leading to endothelial dysfunction through life style modifications or pharmacological interventions could markedly improve cardiovascular health in older people. PMID:22783194

  2. Mechanisms involved in the aging-induced vascular dysfunction.

    PubMed

    El Assar, Mariam; Angulo, Javier; Vallejo, Susana; Peiró, Concepción; Sánchez-Ferrer, Carlos F; Rodríguez-Mañas, Leocadio

    2012-01-01

    Vascular aging is a key process determining health status of aged population. Aging is an independent cardiovascular risk factor associated to an impairment of endothelial function, which is a very early and important event leading to cardiovascular disease. Vascular aging, formerly being considered an immutable and inexorable risk factor, is now viewed as a target process for intervention in order to achieve a healthier old age. A further knowledge of the mechanisms underlying the age-related vascular dysfunction is required to design an adequate therapeutic strategy to prevent or restore this impairment of vascular functionality. Among the proposed mechanisms that contribute to age-dependent endothelial dysfunction, this review is focused on the following aspects occurring into the vascular wall: (1) the reduction of nitric oxide (NO) bioavailability, caused by diminished NO synthesis and/or by augmented NO scavenging due to oxidative stress, leading to peroxynitrite formation (ONOO(-)); (2) the possible sources involved in the enhancement of oxidative stress; (3) the increased activity of vasoconstrictor factors; and (4) the development of a low-grade pro-inflammatory environment. Synergisms and interactions between all these pathways are also analyzed. Finally, a brief summary of some cellular mechanisms related to endothelial cell senescence (including telomere and telomerase, stress-induced senescence, as well as sirtuins) are implemented, as they are likely involved in the age-dependent endothelial dysfunction, as well as in the lower vascular repairing capacity observed in the elderly. Prevention or reversion of those mechanisms leading to endothelial dysfunction through life style modifications or pharmacological interventions could markedly improve cardiovascular health in older people.

  3. Protein synthesis as an integral quality control mechanism during ageing.

    PubMed

    Charmpilas, Nikolaos; Daskalaki, Ioanna; Papandreou, Margarita Elena; Tavernarakis, Nektarios

    2015-09-01

    Ageing is manifested as functional and structural deterioration that affects cell and tissue physiology. mRNA translation is a central cellular process, supplying cells with newly synthesized proteins. Accumulating evidence suggests that alterations in protein synthesis are not merely a corollary but rather a critical factor for the progression of ageing. Here, we survey protein synthesis regulatory mechanisms and focus on the pre-translational regulation of the process exerted by non-coding RNA species, RNA binding proteins and alterations of intrinsic RNA properties. In addition, we discuss the tight relationship between mRNA translation and two central pathways that modulate ageing, namely the insulin/IGF-1 and TOR signalling cascades. A thorough understanding of the complex interplay between protein synthesis regulation and ageing will provide critical insights into the pathogenesis of age-related disorders, associated with impaired proteostasis and protein quality control.

  4. Molecular Mechanisms of Aging and Immune System Regulation in Drosophila

    PubMed Central

    Eleftherianos, Ioannis; Castillo, Julio Cesar

    2012-01-01

    Aging is a complex process that involves the accumulation of deleterious changes resulting in overall decline in several vital functions, leading to the progressive deterioration in physiological condition of the organism and eventually causing disease and death. The immune system is the most important host-defense mechanism in humans and is also highly conserved in insects. Extensive research in vertebrates has concluded that aging of the immune function results in increased susceptibility to infectious disease and chronic inflammation. Over the years, interest has grown in studying the molecular interaction between aging and the immune response to pathogenic infections. The fruit fly Drosophila melanogaster is an excellent model system for dissecting the genetic and genomic basis of important biological processes, such as aging and the innate immune system, and deciphering parallel mechanisms in vertebrate animals. Here, we review the recent advances in the identification of key players modulating the relationship between molecular aging networks and immune signal transduction pathways in the fly. Understanding the details of the molecular events involved in aging and immune system regulation will potentially lead to the development of strategies for decreasing the impact of age-related diseases, thus improving human health and life span. PMID:22949833

  5. Localised micro-mechanical stiffening in the ageing aorta

    PubMed Central

    Graham, Helen K.; Akhtar, Riaz; Kridiotis, Constantinos; Derby, Brian; Kundu, Tribikram; Trafford, Andrew W.; Sherratt, Michael J.

    2011-01-01

    Age-related loss of tissue elasticity is a common cause of human morbidity and arteriosclerosis (vascular stiffening) is associated with the development of both fatal strokes and heart failure. However, in the absence of appropriate micro-mechanical testing methodologies, multiple structural remodelling events have been proposed as the cause of arteriosclerosis. Therefore, using a model of ageing in female sheep aorta (young: <18 months, old: >8 years) we: (i) quantified age-related macro-mechanical stiffness, (ii) localised in situ micro-metre scale changes in acoustic wave speed (a measure of tissue stiffness) and (iii) characterised collagen and elastic fibre remodelling. With age, there was an increase in both macro-mechanical stiffness and mean microscopic wave speed (and hence stiffness; young wave speed: 1701 ± 1 m s−1, old wave speed: 1710 ± 1 m s−1, p < 0.001) which was localized to collagen fibril-rich regions located between large elastic lamellae. These micro-mechanical changes were associated with increases in both collagen and elastic fibre content (collagen tissue area, young: 31 ± 2%, old: 40 ± 4%, p < 0.05; elastic fibre tissue area, young: 55 ± 3%, old: 69 ± 4%, p < 0.001). Localised collagen fibrosis may therefore play a key role in mediating age-related arteriosclerosis. Furthermore, high frequency scanning acoustic microscopy is capable of co-localising micro-mechanical and micro-structural changes in ageing tissues. PMID:21777602

  6. Remaining Life Expectancy With and Without Polypharmacy: A Register-Based Study of Swedes Aged 65 Years and Older

    PubMed Central

    Wastesson, Jonas W.; Canudas-Romo, Vladimir; Lindahl-Jacobsen, Rune; Johnell, Kristina

    2016-01-01

    Objectives To investigate the remaining life expectancy with and without polypharmacy for Swedish women and men aged 65 years and older. Design Age-specific prevalence of polypharmacy from the nationwide Swedish Prescribed Drug Register (SPDR) combined with life tables from Statistics Sweden was used to calculate the survival function and remaining life expectancy with and without polypharmacy according to the Sullivan method. Setting Nationwide register-based study. Participants A total of 1,347,564 individuals aged 65 years and older who had been prescribed and dispensed a drug from July 1 to September 30, 2008. Measurements Polypharmacy was defined as the concurrent use of 5 or more drugs. Results At age 65 years, approximately 8 years of the 20 remaining years of life (41%) can be expected to be lived with polypharmacy. More than half of the remaining life expectancy will be spent with polypharmacy after the age of 75 years. Women had a longer life expectancy, but also lived more years with polypharmacy than men. Discussion Older women and men spend a considerable proportion of their lives with polypharmacy. Conclusion Given the negative health outcomes associated with polypharmacy, efforts should be made to reduce the number of years older adults spend with polypharmacy to minimize the risk of unwanted consequences. PMID:26341036

  7. Thermal ageing mechanisms of VVER-1000 reactor pressure vessel steels

    NASA Astrophysics Data System (ADS)

    Shtrombakh, Yaroslav I.; Gurovich, Boris A.; Kuleshova, Evgenia A.; Maltsev, Dmitry A.; Fedotova, Svetlana V.; Chernobaeva, Anna A.

    2014-09-01

    In this paper a complex of microstructural studies (TEM and SEM) and a comparative analysis of the results of these studies with the data of mechanical tests of temperature sets of VVER-1000 RPV surveillance specimens with exposure times up to ∼200,000 h were conducted. Special annealing of control and temperature sets of SS which provides the dissolution of grain boundary segregation was performed to clarify the mechanisms of thermal ageing. It was demonstrated that during long-term exposures up to 200,000 h at the operating temperature of about 310-320 °C thermal ageing effects reveal themselves only for the weld metal (Ni content ⩾ 1.35%) and are the result of grain boundary segregation accumulation (development of reversible temper brittleness). The obtained results improve the accuracy of prediction of the thermal ageing rate of VVER-1000 materials in case of RPV service life extension up to 60 years.

  8. ROS, Cell Senescence, and Novel Molecular Mechanisms in Aging and Age-Related Diseases

    PubMed Central

    Davalli, Pierpaola; Mitic, Tijana; Caporali, Andrea; Lauriola, Angela; D'Arca, Domenico

    2016-01-01

    The aging process worsens the human body functions at multiple levels, thus causing its gradual decrease to resist stress, damage, and disease. Besides changes in gene expression and metabolic control, the aging rate has been associated with the production of high levels of Reactive Oxygen Species (ROS) and/or Reactive Nitrosative Species (RNS). Specific increases of ROS level have been demonstrated as potentially critical for induction and maintenance of cell senescence process. Causal connection between ROS, aging, age-related pathologies, and cell senescence is studied intensely. Senescent cells have been proposed as a target for interventions to delay the aging and its related diseases or to improve the diseases treatment. Therapeutic interventions towards senescent cells might allow restoring the health and curing the diseases that share basal processes, rather than curing each disease in separate and symptomatic way. Here, we review observations on ROS ability of inducing cell senescence through novel mechanisms that underpin aging processes. Particular emphasis is addressed to the novel mechanisms of ROS involvement in epigenetic regulation of cell senescence and aging, with the aim to individuate specific pathways, which might promote healthy lifespan and improve aging. PMID:27247702

  9. Acculturation or Development? Autonomy Expectations among Ethnic German Immigrant Adolescents and Their Native German Age-Mates

    ERIC Educational Resources Information Center

    Titzmann, Peter F.; Silbereisen, Rainer K.

    2012-01-01

    This longitudinal study compared immigrant and native adolescents' expectations concerning the timing of conventional socially acceptable and oppositional less socially acceptable forms of autonomy. Based on normative development and a collectivist background among immigrants, both developmental and acculturative change was expected. The sample…

  10. Aging mechanisms and service life of lead-acid batteries

    NASA Astrophysics Data System (ADS)

    Ruetschi, Paul

    In lead-acid batteries, major aging processes, leading to gradual loss of performance, and eventually to the end of service life, are: Anodic corrosion (of grids, plate-lugs, straps or posts). Positive active mass degradation and loss of adherence to the grid (shedding, sludging). Irreversible formation of lead sulfate in the active mass (crystallization, sulfation). Short-circuits. Loss of water. Aging mechanisms are often inter-dependent. For example, corrosion of the grids will lead to increased resistance to current flow, which will in turn impede proper charge of certain parts of the active mass, resulting in sulfation. Active mass degradation may lead to short-circuits. Sulfation may be the result of a loss of water, and so forth. The rates of the different aging processes strongly depend on the type of use (or misuse) of the battery. Over-charge will lead to accelerated corrosion and also to accelerated loss of water. With increasing depth-of-discharge during cycling, positive active mass degradation is accelerated. Some aging mechanisms are occurring only upon misuse. Short-circuits across the separators, due to the formation of metallic lead dendrites, for example, are usually formed only after (excessively) deep discharge. Stationary batteries, operated under float-charge conditions, will age typically by corrosion of the positive grids. On the other hand, service life of batteries subject to cycling regimes, will typically age by degradation of the structure of the positive active mass. Starter batteries are usually aging by grid corrosion, for instance in normal passenger car use. However, starter batteries of city buses, making frequent stops, may age (prematurely) by positive active mass degradation, because the batteries are subject to numerous shallow discharge cycles. Valve-regulated batteries often fail as a result of negative active mass sulfation, or water loss. For each battery design, and type of use, there is usually a characteristic

  11. Increasing inequality in age of death at shared levels of life expectancy: A comparative study of Scotland and England and Wales.

    PubMed

    Seaman, Rosie; Leyland, Alastair H; Popham, Frank

    2016-12-01

    There is a strong negative correlation between increasing life expectancy and decreasing lifespan variation, a measure of inequality. Previous research suggests that countries achieving a high level of life expectancy later in time generally do so with lower lifespan variation than forerunner countries. This may be because they are able to capitalise on lessons already learnt. However, a few countries achieve a high level of life expectancy later in time with higher inequality. Scotland appears to be such a country and presents an interesting case study because it previously experienced lower inequality when reaching the same level of life expectancy as its closest comparator England and Wales. We calculated life expectancy and lifespan variation for Scotland and England and Wales for the years 1950 to 2012, comparing Scotland to England and Wales when it reached the same level of life expectancy later on in time, and assessed the difference in the level of lifespan variation. The lifespan variation difference between the two countries was then decomposed into age-specific components. Analysis was carried out for males and females separately. Since the 1950s Scotland has achieved the same level of life expectancy at least ten years later in time than England and Wales. Initially it did so with lower lifespan variation. Following the 1980s Scotland has been achieving the same level of life expectancy later in time than England and Wales and with higher inequality, particularly for males. Decomposition revealed that higher inequality is partly explained by lower older age mortality rates but primarily by higher premature adult age mortality rates when life expectancy is the same. Existing studies suggest that premature adult mortality rates are strongly associated with the social determinants of health and may be amenable to social and economic policies. So addressing these policy areas may have benefits for both inequality and population health in Scotland.

  12. Skin aging and oxidative stress: Equol's anti-aging effects via biochemical and molecular mechanisms.

    PubMed

    Lephart, Edwin D

    2016-11-01

    Oxygen in biology is essential for life. It comes at a cost during normal cellular function, where reactive oxygen species (ROS) are generated by oxidative metabolism. Human skin exposed to solar ultra-violet radiation (UVR) dramatically increases ROS production/oxidative stress. It is important to understand the characteristics of human skin and how chronological (intrinsic) aging and photo-aging (extrinsic aging) occur via the impact of ROS production by cascade signaling pathways. The goal is to oppose or neutralize ROS insults to maintain good dermal health. Botanicals, as active ingredients, represent one of the largest categories used in dermatology and cosmeceuticals to combat skin aging. An emerging botanical is equol, a polyphenolic/isoflavonoid molecule found in plants and food products and via gastrointestinal metabolism from precursor compounds. Introductory sections cover oxygen, free radicals (ROS), oxidative stress, antioxidants, human skin aging, cellular/molecular ROS events in skin, steroid enzymes/receptors/hormonal actions and genetic factors in aging skin. The main focus of this review covers the characteristics of equol (phytoestrogenic, antioxidant and enhancement of extracellular matrix properties) to reduce skin aging along with its anti-aging skin influences via reducing oxidative stress cascade events by a variety of biochemical/molecular actions and mechanisms to enhance human dermal health.

  13. Age of sex-determining mechanisms in vertebrates.

    PubMed

    WITSCHI, E

    1959-08-14

    Certain characteristic patterns of physiologic sex determination are not causally linked with types of genic and chromosomal constitution (XX-XY or ZW-ZZ). The observed widespread but not universal parallelism in the distribution of genetic and physiologic patterns among vertebrate groups expresses genealogic relationship. On the basis of this interpretation one may estimate the approximate evolutionary age of the mechanism of genetic sex determination. It is concluded that in all tetrapod vertebrates these mechanisms originated during the Jurassic period. Environmental conditions seem to affect the progress of this evolution.

  14. Aging of the Immune System. Mechanisms and Therapeutic Targets.

    PubMed

    Weyand, Cornelia M; Goronzy, Jörg J

    2016-12-01

    Beginning with the sixth decade of life, the human immune system undergoes dramatic aging-related changes, which continuously progress to a state of immunosenescence. The aging immune system loses the ability to protect against infections and cancer and fails to support appropriate wound healing. Vaccine responses are typically impaired in older individuals. Conversely, inflammatory responses mediated by the innate immune system gain in intensity and duration, rendering older individuals susceptible to tissue-damaging immunity and inflammatory disease. Immune system aging functions as an accelerator for other age-related pathologies. It occurs prematurely in some clinical conditions, most prominently in patients with the autoimmune syndrome rheumatoid arthritis (RA); and such patients serve as an informative model system to study molecular mechanisms of immune aging. T cells from patients with RA are prone to differentiate into proinflammatory effector cells, sustaining chronic-persistent inflammatory lesions in the joints and many other organ systems. RA T cells have several hallmarks of cellular aging; most importantly, they accumulate damaged DNA. Because of deficiency of the DNA repair kinase ataxia telangiectasia mutated, RA T cells carry a higher burden of DNA double-strand breaks, triggering cell-indigenous stress signals that shift the cell's survival potential and differentiation pattern. Immune aging in RA T cells is also associated with metabolic reprogramming; specifically, with reduced glycolytic flux and diminished ATP production. Chronic energy stress affects the longevity and the functional differentiation of older T cells. Altered metabolic patterns provide opportunities to therapeutically target the immune aging process through metabolic interference.

  15. An intrinsic mechanism of secreted protein aging and turnover.

    PubMed

    Yang, Won Ho; Aziz, Peter V; Heithoff, Douglas M; Mahan, Michael J; Smith, Jeffrey W; Marth, Jamey D

    2015-11-03

    The composition and functions of the secreted proteome are controlled by the life spans of different proteins. However, unlike intracellular protein fate, intrinsic factors determining secreted protein aging and turnover have not been identified and characterized. Almost all secreted proteins are posttranslationally modified with the covalent attachment of N-glycans. We have discovered an intrinsic mechanism of secreted protein aging and turnover linked to the stepwise elimination of saccharides attached to the termini of N-glycans. Endogenous glycosidases, including neuraminidase 1 (Neu1), neuraminidase 3 (Neu3), beta-galactosidase 1 (Glb1), and hexosaminidase B (HexB), possess hydrolytic activities that temporally remodel N-glycan structures, progressively exposing different saccharides with increased protein age. Subsequently, endocytic lectins with distinct binding specificities, including the Ashwell-Morell receptor, integrin αM, and macrophage mannose receptor, are engaged in N-glycan ligand recognition and the turnover of secreted proteins. Glycosidase inhibition and lectin deficiencies increased protein life spans and abundance, and the basal rate of N-glycan remodeling varied among distinct proteins, accounting for differences in their life spans. This intrinsic multifactorial mechanism of secreted protein aging and turnover contributes to health and the outcomes of disease.

  16. An intrinsic mechanism of secreted protein aging and turnover

    PubMed Central

    Yang, Won Ho; Aziz, Peter V.; Heithoff, Douglas M.; Mahan, Michael J.; Smith, Jeffrey W.; Marth, Jamey D.

    2015-01-01

    The composition and functions of the secreted proteome are controlled by the life spans of different proteins. However, unlike intracellular protein fate, intrinsic factors determining secreted protein aging and turnover have not been identified and characterized. Almost all secreted proteins are posttranslationally modified with the covalent attachment of N-glycans. We have discovered an intrinsic mechanism of secreted protein aging and turnover linked to the stepwise elimination of saccharides attached to the termini of N-glycans. Endogenous glycosidases, including neuraminidase 1 (Neu1), neuraminidase 3 (Neu3), beta-galactosidase 1 (Glb1), and hexosaminidase B (HexB), possess hydrolytic activities that temporally remodel N-glycan structures, progressively exposing different saccharides with increased protein age. Subsequently, endocytic lectins with distinct binding specificities, including the Ashwell–Morell receptor, integrin αM, and macrophage mannose receptor, are engaged in N-glycan ligand recognition and the turnover of secreted proteins. Glycosidase inhibition and lectin deficiencies increased protein life spans and abundance, and the basal rate of N-glycan remodeling varied among distinct proteins, accounting for differences in their life spans. This intrinsic multifactorial mechanism of secreted protein aging and turnover contributes to health and the outcomes of disease. PMID:26489654

  17. Aging and Immune Function: Molecular Mechanisms to Interventions

    PubMed Central

    Ponnappan, Subramaniam

    2011-01-01

    Abstract The immune system of an organism is an essential component of the defense mechanism aimed at combating pathogenic stress. Age-associated immune dysfunction, also dubbed “immune senescence,” manifests as increased susceptibility to infections, increased onset and progression of autoimmune diseases, and onset of neoplasia. Over the years, extensive research has generated consensus in terms of the phenotypic and functional defects within the immune system in various organisms, including humans. Indeed, age-associated alterations such as thymic involution, T cell repertoire skewing, decreased ability to activate naïve T cells and to generate robust memory responses, have been shown to have a causative role in immune decline. Further, understanding the molecular mechanisms underlying the generation of proteotoxic stress, DNA damage response, modulation of ubiquitin proteasome pathway, and regulation of transcription factor NFκB activation, in immune decline, have paved the way to delineating signaling pathways that cross-talk and impact immune senescence. Given the role of the immune system in combating infections, its effectiveness with age may well be a marker of health and a predictor of longevity. It is therefore believed that a better understanding of the mechanisms underlying immune senescence will lead to an effective interventional strategy aimed at improving the health span of individuals. Antioxid. Redox Signal. 14, 1551–1585. PMID:20812785

  18. Erythropoietin and mTOR: A “One-Two Punch” for Aging-Related Disorders Accompanied by Enhanced Life Expectancy

    PubMed Central

    Maiese, Kenneth

    2016-01-01

    Life expectancy continues to increase throughout the world, but is accompanied by a rise in the incidence of non-communicable diseases. As a result, the benefits of an increased lifespan can be limited by aging-related disorders that necessitate new directives for the development of effective and safe treatment modalities. With this objective, the mechanistic target of rapamycin (mTOR), a 289-kDa serine/threonine protein, and its related pathways of mTOR Complex 1 (mTORC1), mTOR Complex 2 (mTORC2), proline rich Akt substrate 40 kDa (PRAS40), AMP activated protein kinase (AMPK), Wnt signaling, and silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), have generated significant excitement for furthering novel therapies applicable to multiple systems of the body. Yet, the biological and clinical outcome of these pathways can be complex especially with oversight of cell death mechanisms that involve apoptosis and autophagy. Growth factors, and in particular erythropoietin (EPO), are one avenue under consideration to implement control over cell death pathways since EPO can offer potential treatment for multiple disease entities and is intimately dependent upon mTOR signaling. In experimental and clinical studies, EPO appears to have significant efficacy in treating several disorders including those involving the developing brain. However, in mature populations that are affected by aging-related disorders, the direction for the use of EPO to treat clinical disease is less clear that may be dependent upon a number of factors including the understanding of mTOR signaling. Continued focus upon the regulatory elements that control EPO and mTOR signaling could generate critical insights for targeting a broad range of clinical maladies. PMID:27488211

  19. Demographic Ageing of the South African Population: Past (1945-1985) and Expected Trends (1985-2035). Report S-190.

    ERIC Educational Resources Information Center

    Hofmeyr, B. E.; Mostert, W. P.

    This report presents demographic data for four racial populations in South Africa (Blacks, Whites, Coloureds, and Asians) and examines trends in the aging of each of these populations. The age structure of a population is determined most directly by fertility and mortality. The findings of this report support a general theory to the effect that…

  20. Meeting the expectation of industry: an integrated approach for the teaching of mechanics and electronics to design students

    NASA Astrophysics Data System (ADS)

    Bingham, Guy A.; Southee, Darren J.; Page, Tom

    2015-07-01

    This paper examines the traditional engineering-based provision delivered to Product Design and Technology (B.Sc.) undergraduates at the Loughborough Design School and questions its relevancy against the increasing expectations of industry. The paper reviews final-year design projects to understand the level of transference of engineering-based knowledge into design practice and highlights areas of opportunity for improved teaching and learning. The paper discusses the development and implementation of an integrated approach to the teaching of Mechanics and Electronics to formalise and reinforce the key learning process of transference within the design context. The paper concludes with observations from the delivery of this integrated teaching and offers insights from student and academic perspectives for the further improvement of engineering-based teaching and learning.

  1. Mechanism of Inflammation in Age-Related Macular Degeneration

    PubMed Central

    Parmeggiani, Francesco; Romano, Mario R.; Costagliola, Ciro; Semeraro, Francesco; Incorvaia, Carlo; D'Angelo, Sergio; Perri, Paolo; De Palma, Paolo; De Nadai, Katia; Sebastiani, Adolfo

    2012-01-01

    Age-related macular degeneration (AMD) is a multifactorial disease that represents the most common cause of irreversible visual impairment among people over the age of 50 in Europe, the United States, and Australia, accounting for up to 50% of all cases of central blindness. Risk factors of AMD are heterogeneous, mainly including increasing age and different genetic predispositions, together with several environmental/epigenetic factors, that is, cigarette smoking, dietary habits, and phototoxic exposure. In the aging retina, free radicals and oxidized lipoproteins are considered to be major causes of tissue stress resulting in local triggers for parainflammation, a chronic status which contributes to initiation and/or progression of many human neurodegenerative diseases such as AMD. Experimental and clinical evidences strongly indicate the pathogenetic role of immunologic processes in AMD occurrence, consisting of production of inflammatory related molecules, recruitment of macrophages, complement activation, microglial activation and accumulation within those structures that compose an essential area of the retina known as macula lutea. This paper reviews some attractive aspects of the literature about the mechanisms of inflammation in AMD, especially focusing on those findings or arguments more directly translatable to improve the clinical management of patients with AMD and to prevent the severe vision loss caused by this disease. PMID:23209345

  2. Mechanism of inflammation in age-related macular degeneration.

    PubMed

    Parmeggiani, Francesco; Romano, Mario R; Costagliola, Ciro; Semeraro, Francesco; Incorvaia, Carlo; D'Angelo, Sergio; Perri, Paolo; De Palma, Paolo; De Nadai, Katia; Sebastiani, Adolfo

    2012-01-01

    Age-related macular degeneration (AMD) is a multifactorial disease that represents the most common cause of irreversible visual impairment among people over the age of 50 in Europe, the United States, and Australia, accounting for up to 50% of all cases of central blindness. Risk factors of AMD are heterogeneous, mainly including increasing age and different genetic predispositions, together with several environmental/epigenetic factors, that is, cigarette smoking, dietary habits, and phototoxic exposure. In the aging retina, free radicals and oxidized lipoproteins are considered to be major causes of tissue stress resulting in local triggers for parainflammation, a chronic status which contributes to initiation and/or progression of many human neurodegenerative diseases such as AMD. Experimental and clinical evidences strongly indicate the pathogenetic role of immunologic processes in AMD occurrence, consisting of production of inflammatory related molecules, recruitment of macrophages, complement activation, microglial activation and accumulation within those structures that compose an essential area of the retina known as macula lutea. This paper reviews some attractive aspects of the literature about the mechanisms of inflammation in AMD, especially focusing on those findings or arguments more directly translatable to improve the clinical management of patients with AMD and to prevent the severe vision loss caused by this disease.

  3. Nonmonotonic Aging and Memory Retention in Disordered Mechanical Systems

    NASA Astrophysics Data System (ADS)

    Lahini, Yoav; Gottesman, Omer; Amir, Ariel; Rubinstein, Shmuel M.

    2017-02-01

    We observe nonmonotonic aging and memory effects, two hallmarks of glassy dynamics, in two disordered mechanical systems: crumpled thin sheets and elastic foams. Under fixed compression, both systems exhibit monotonic nonexponential relaxation. However, when after a certain waiting time the compression is partially reduced, both systems exhibit a nonmonotonic response: the normal force first increases over many minutes or even hours until reaching a peak value, and only then is relaxation resumed. The peak time scales linearly with the waiting time, indicating that these systems retain long-lasting memory of previous conditions. Our results and the measured scaling relations are in good agreement with a theoretical model recently used to describe observations of monotonic aging in several glassy systems, suggesting that the nonmonotonic behavior may be generic and that athermal systems can show genuine glassy behavior.

  4. Expectant management of severe preeclampsia at 27(0/7) to 33(6/7) weeks' gestation: maternal and perinatal outcomes according to gestational age by weeks at onset of expectant management.

    PubMed

    Bombrys, Annette E; Barton, John R; Habli, Mounira; Sibai, Baha M

    2009-06-01

    We sought to determine perinatal outcome and maternal morbidities based on gestational age (GA) at onset of expectant management in severe preeclampsia (PE) between 27(0/7) and 33 (6/7) weeks. In this retrospective analysis of outcome in patients with severe preeclampsia, we studied 66 patients (71 fetuses) with severe PE at 27 (0)/ (7) to 33(6/ 7). All patients received corticosteroids. Perinatal and maternal complications were analyzed. Five patients had twin gestations. Median for days of prolongation was 5 days (range, 3 to 35). Birth weights of 19 (27%) were < 10% for gestational age, and 6 (8%) were < 5%. All fetuses survived except for one neonatal death at 27 weeks, and three infants had chronic lung disease-two at 27 and one at 28 weeks-but there were no cases of intraventricular hemorrhage (>or= grade ?). Rate of abruption was significantly higher at 27 to 28 weeks as compared with > 28 weeks (25% vs 6%, p = 0.05). There was no eclampsia, and two had transient renal insufficiency at 27 weeks. Four of 11 (36%) patients with expectant management at >or= 32 weeks had pulmonary edema or hemolytic anemia, elevated liver enzymes, and low platelet count. During expectant management, rate of respiratory distress syndrome and other serious neonatal complications decrease with increasing GA, supporting a role for such management in early severe preeclampsia. Because there is significant maternal morbidity at >or= 32 weeks with minimal neonatal benefit, consideration should be given for delivery of these pregnancies following corticosteroid administration.

  5. AGE-DEPENDENT ASCENDING AORTA MECHANICS ASSESSED THROUGH MULTIPHASE CT

    PubMed Central

    Martin, Caitlin; Sun, Wei; Primiano, Charles; McKay, Raymond; Elefteriades, John

    2013-01-01

    Quantification of the age- and gender-specific in vivo mechanical characteristics of the ascending aorta (AA) will allow for identification of abnormalities aside from changes brought on by aging alone. Multiphase clinical CT scans of 45 male patients between the ages of 30 and 79 years were analyzed to assess age-dependent in vivo AA characteristics. The three-dimensional AA geometry for each patient was reconstructed from the CT scans for 9–10 phases throughout the cardiac cycle. The AA circumference was measured during each phase and was used to determine the corresponding diameter, circumferential strain, and wall tension at each phase. The pressure-strain modulus was also determined for each patient. The mean diastolic AA diameter was significantly smaller among young (42.6±5.2 years) at 29.9±2.8 mm than old patients (69.0±5.2 years) at 33.2±3.2 mm. The circumferential AA strain from end-diastole to peak-systole decreased from 0.092±0.03 in young to 0.056±0.03 in old patients. The pressure-strain modulus increased two-fold from 68.4±30.5 kPa in young to 162.0±93.5 kPa in old patients, and the systolic AA wall tension increased from 268.5±31.3 kPa in young to 304.9±49.2 kPa in old patients. The AA dilates and stiffens with aging which increases the vessel wall tension, likely predisposing aneurysm and dissection. PMID:23817767

  6. 'So few fat ones grow old': diet, health, and virtue in the golden age of rising life expectancy.

    PubMed

    Veit, Helen Zoe

    2011-06-01

    Life expectancy and chronic disease rates both rose dramatically in the United States during the first third of the twentieth century. As a result of this concurrence, Americans in this era increasingly thought about things they could do to extend their own lives, especially eating less, exercising more, and limiting stress, all factors thought to reduce chronic disease. New recognition of the correlation between daily physical habits and long lives made longevity look like a sign of virtue. At the same time, amidst discussions about the relationship between individual longevity and national vitality, this correlation also contributed to Americans' moralization of diet, exercise, and emotional self-control.

  7. Tubulin acetylation protects long-lived microtubules against mechanical ageing.

    PubMed

    Portran, Didier; Schaedel, Laura; Xu, Zhenjie; Théry, Manuel; Nachury, Maxence V

    2017-04-01

    Long-lived microtubules endow the eukaryotic cell with long-range transport abilities. While long-lived microtubules are acetylated on Lys40 of α-tubulin (αK40), acetylation takes place after stabilization and does not protect against depolymerization. Instead, αK40 acetylation has been proposed to mechanically stabilize microtubules. Yet how modification of αK40, a residue exposed to the microtubule lumen and inaccessible to microtubule-associated proteins and motors, could affect microtubule mechanics remains an open question. Here we develop FRET-based assays that report on the lateral interactions between protofilaments and find that αK40 acetylation directly weakens inter-protofilament interactions. Congruently, αK40 acetylation affects two processes largely governed by inter-protofilament interactions, reducing the nucleation frequency and accelerating the shrinkage rate. Most relevant to the biological function of acetylation, microfluidics manipulations demonstrate that αK40 acetylation enhances flexibility and confers resilience against repeated mechanical stresses. Thus, unlike deacetylated microtubules that accumulate damage when subjected to repeated stresses, long-lived microtubules are protected from mechanical ageing through their acquisition of αK40 acetylation. In contrast to other tubulin post-translational modifications that act through microtubule-associated proteins, motors and severing enzymes, intraluminal acetylation directly tunes the compliance and resilience of microtubules.

  8. Latina Mothers' and Daughters' Expectations for Autonomy at Age 15 (La Quinceañera)

    ERIC Educational Resources Information Center

    Romo, Laura F.; Mireles-Rios, Rebeca; Lopez-Tello, Gisselle

    2014-01-01

    American children gain more autonomy as they progress through adolescence, however, autonomy-granting for Latina adolescent girls from immigrant families is a relatively unexplored question. In this study, we identified behaviors that Mexican mothers and their daughters deemed to be appropriate when they reach the age of "La…

  9. Investigation of Aging Mechanisms in Lean NOx Traps

    SciTech Connect

    Mark Crocker

    2010-03-31

    Lean NO{sub x} traps (LNTs) represent a promising technology for the abatement of NO{sub x} under lean conditions. Although LNTs are starting to find commercial application, the issue of catalyst durability remains problematic. LNT susceptibility to sulfur poisoning is the single most important factor determining effective catalyst lifetime. The NO{sub x} storage element of the catalyst has a greater affinity for SO{sub 3} than it does for NO{sub 2}, and the resulting sulfate is more stable than the stored nitrate. Although this sulfate can be removed from the catalyst by means of high temperature treatment under rich conditions, the required conditions give rise to deactivation mechanisms such as precious metal sintering, total surface area loss, and solid state reactions between the various oxides present. The principle objective of this project was to improve understanding of the mechanisms of lean NO{sub x} trap aging, and to understand the effect of washcoat composition on catalyst aging characteristics. The approach utilized involved detailed characterization of model catalysts prior to and after aging, in tandem with measurement of catalyst performance in NO{sub x} storage and reduction. In this manner, NO{sub x} storage and reduction characteristics were correlated with the evolution of catalyst physico-chemical properties upon aging. Rather than using poorly characterized proprietary catalysts, or simple model catalysts of the Pt/BaO/Al{sub 2}O{sub 3} type (representing the first generation of LNTs), Pt/Rh/BaO/Al{sub 2}O{sub 3} catalysts were employed which also incorporated CeO{sub 2} or CeO{sub 2}-ZrO{sub 2}, representing a model system which more accurately reflects current LNT formulations. Catalysts were prepared in which the concentration of each of the main components was systematically varied: Pt (50, 75 or 100 g/ft{sup 3}), Rh (10 or 20 g/ft{sup 3}), BaO (15, 30 or 45 g/L), and either CeO{sub 2} (0, 50 or 100 g/L) or CeO{sub 2}-ZrO{sub 2} (0, 50

  10. Passive biaxial mechanical response of aged human iliac arteries.

    PubMed

    Schulze-Bauer, Christian A J; Mörth, Christian; Holzapfel, Gerhard A

    2003-06-01

    Inflation and extension tests of arteries are essential for the understanding of arterial wall mechanics. Data for such tests of human arteries are rare. At autopsy we harvested 10 non-diseased external iliac arteries of aged subjects (52-87 yrs). Structural homogeneity was ensured by means of ultrasound imaging, and anamneses of patients were recorded. We measured the axial in situ stretches, load-free geometries and opening angles. Passive biaxial mechanical responses of preconditioned cylindrical specimens were studied in 37 degrees C calcium-free Tyrode solution under quasistatic loading conditions. Specimens were subjected to pressure cycles varying from 0 to 33.3 kPa (250 mmHg) at nine fixed axial loads, varying from 0 to 9.90N. For the description of the load-deformation behavior we employed five "two-dimensional" orthotropic strain-energy functions frequently used in arterial wall mechanics. The associated constitutive models were compared in regard to their ability of representing the experimental data. Histology showed that the arteries were of the muscular type. In contrast to animal arteries they exhibited intimal layers of considerable thickness. The average ratio of wall thickness to outer diameter was 7.7, which is much less than observed for common animal arteries. We found a clear correlation between age and the axial in situ stretch lambda is (r = -0.72, P = 0.03), and between age and distensibility of specimens, i.e. aged specimens are less distensible. Axial in situ stretches were clearly smaller (1.07 +/- 0.09, mean +/- SD) than in animal arteries. For one specimen lambda is was even smaller than 1.0, i.e. the vessel elongated axially upon excision. The nonlinear and anisotropic load-deformation behavior showed small hystereses. For the majority of specimens we observed axial stretches smaller than 1.3 and circumferential stretches smaller than 1.1 for the investigated loading range. Data from in situ inflation tests showed a significant

  11. Mechanical properties of bulk polydimethylsiloxane for microfluidics over a large range of frequencies and aging times

    NASA Astrophysics Data System (ADS)

    Placet, V.; Delobelle, P.

    2015-03-01

    The dynamic mechanical characterization of polydimethylsiloxane (PDMS) over a large range of frequencies (10-2 < f < 105 Hz) and long aging times at room temperature (4 h < tv < ~60 000 h) has been presented. Three samples with different curing conditions have been studied and three different techniques, dynamic mechanical analysis at different temperatures, nano-indentation and scanning micro-deformation microscopy, have been used. Although the three techniques work at different scales and at different frequencies all the results match the same master curve. As expected, the storage and the loss moduli greatly increase with the frequency. Moreover, these moduli moderately increase with the aging time tv depending on the curing temperature. A simple model which takes the frequency and the aging time into account, and which is based on the Havriliak-Negami model, has been presented and identified. Hence, values of the relaxed and instantaneous moduli at tv = 0 and tv = ∞ are proposed. Only the relaxed moduli depend on the curing conditions and moreover it has been shown that the tangent of the phase lag is independent of the aging time and thus of the curing process.

  12. Bicycle injuries: a matter of mechanism and age.

    PubMed

    Siman-Tov, Maya; Jaffe, Dena H; Peleg, Kobi

    2012-01-01

    Bicycle riding is a popular form of recreation with positive health and environmental effects. These road users are vulnerable to serious injuries, especially when motor vehicles are involved. The goal of this study was to characterize cyclist-related injuries according to motor vehicle involvement for adults versus children. A retrospective study was carried out using data from 11 trauma centers in the Israeli National Trauma Registry (2001-2007). Injuries were classified according to whether a motor vehicle was involved, and differences in injury characteristics were assessed for adults (18+ years) versus children (1-17 years). A total of 5529 patients were hospitalized for bicycle injuries, of whom 1765 were adults and 3764 were children. Thirty percent (n=1662) of all bicycle injuries involved motor vehicles, although the rate of injuries resulting in hospitalization was 37% among adults and 27% among children. Injury characteristics and hospital resource utilization differed substantially by age group. Cyclists struck by a motor vehicle presented with more severe injuries requiring more hospital resources and resulting in poorer outcomes than those not involved with motor vehicles. The interaction effect between motor vehicle involvement and age was significant for torso injuries and need for medical imaging. We found that injury characteristics, hospital resource utilization and health-related outcomes for bicycle injuries are highly dependent on patient's age and mechanism of injury. Effect modification of motor vehicle involvement by age may in part reflect physicians' attitudes toward pediatric imaging. The risks identified in this study should be used for preparedness and management of trauma hospitalizations from bicycle injuries.

  13. Expectations of filial obligation and their impact on preferences for future living arrangements of middle-aged and older Asian Indian immigrants.

    PubMed

    Diwan, Sadhna; Lee, Sang E; Sen, Soma

    2011-03-01

    Filial obligation, described as culturally-defined rights and duties that prescribe how family members are expected to care for and provide support to each other, is an important variable that influences older immigrants' preferences for living and care arrangements. This exploratory study examined variables associated with expectations of filial obligation among middle-aged and older, Asian Indian, first generation immigrants and explored the relationship between variations in expectations of filial obligation and expressed preferences for future living arrangements. Data were collected through telephone surveys of 226 English-speaking immigrants in Atlanta, GA. Although no significant relationships were observed between filial obligation expectations and length of residence in the U.S., respondents indicated a variety of preferred future living arrangements. Contrary to current living arrangement patterns found among older immigrants, very few respondents preferred to move in with their children. The most popular preference was to "move closer to children," followed by "moving to a retirement community" with the majority preferring a retirement community geared to Asian Indians. Other preferences included "not moving" and "returning to India." Variations in expectations of filial obligation, length of residence in the U.S., and self-rated health were significantly associated with these preferences. Implications are discussed for building capacity within ethnic communities to address living arrangement preferences and their repercussions for caregiving in ethnic families and in communities.

  14. Mechanical properties of types 304 and 316 stainless steel after long-term aging and exposure

    SciTech Connect

    Horak, J.A.; Sikka, V.K.; Raske, D.T.

    1983-01-01

    Because designs for Liquid Metal Fast Breeder Reactor (LMFBR) power plants include plant lifetimes to 40 years, an understanding of the mechanical behavior of the structural alloys used is required for times of approx. 2 to 2.5 x 10/sup 5/ h. Most of the alloys used for LMFBR out-of-core structures and components are in a metastable state at the beginning of plant lifetime and evolve to a more stable state and, therefore, microstructure during plant operation. We reviewed mechanical properties and microstructures after prolonged elevated-temperature exposure of types 304 and 316 stainless steel, two alloys used extensively in fast breeder systems. Aging alters properties; in particular, it decreases toughness and tensile ductility, but the properties are still adequate for service. Because stable microstructures have been reached in long-term exposures achieved so far, properties can be expected to remain adequate for service life exposures.

  15. Mechanisms of renal tubular defects in old age.

    PubMed Central

    Dontas, A. S.; Marketos, S. G.; Papanayiotou, P.

    1972-01-01

    The mechanisms of renal tubular dysfunction in old age have been examined in twenty-eight clinically healthy elderly subjects without infection, and in fourteen subjects of similar age with laboratory evidence of intrarenal infection. The data were compared with those from thirteen clinically healthy young subjects. Studied were: proximal tubular (Tm(PAH)) and distal tubular (CH2O) activity, minimal and maximal osmolal U/P ratios, maximal osmolal excretion in hydropenia, and GFR levels under standard hydration and under water-loading. The reduction of GFR in old age is evident particularly in men under conditions of standard hydration: it is accentuated in the presence of renal infection. Proximal tubular activity is also significantly lower in elderly men, especially if they have chronic bacteriuria. The reduction is closely related to GFR levels, with identical Tm(PAH):C(in) ratios in all groups. This supports the intact nephron hypothesis for this part of the nephron. Distal tubular activity is depressed in old age in both sexes proportionately more than proximal tubular activity or the GFR. The lower CH2O: GFR ratios imply a selective distal tubular damage. Maximal osmolal U/P ratios in hydropenia are significantly higher in the young (mean 367) than in either the elderly non-infected (mean 279) or the elderly infected subjects (mean 212). Conversely, minimal U/P ratios in water-loading are lower in the young (mean 0.247) than in either elderly group (means 0.418 and 0.668). Osmolal excretion in hydropenia is not different between the groups, but urine flows in water-loading clearly separate them. The data indicate that simple functions of the distal-collecting tubule (e.g. the CH2O), are less affected in old age than are functions involving several medullary structures (as is the maximal U(osm) or U/P ratio). They suggest that the main impairment of the distal tubular cell involves the failure to achieve a proper osmotic gradient between tubular fluid and

  16. Aging degradation of cast stainless steels: Effects on mechanical properties

    SciTech Connect

    Chopra, O.K.; Chung, H.M.

    1987-06-01

    A program is being conducted to investigate the significance of in-service embrittlement of cast duplex stainless steels under light-water operating conditions. Mechanical property data are presented from Charpy-impact, tensile, and J-R curve tests for several heats of cast stainless steel aged up to 10,000 h at 450, 400, 350, 320, and 290/sup 0/C. The results indicate that thermal aging increases the tensile strength and decreases the impact energy, J/sub IC/, and tearing modulus of the steels. Also, the ductile-to-brittle transition curve shifts to higher temperatures. The fracture toughness results are consistent with the Charpy-impact data, i.e., the relative reduction in J/sub IC/ is similar to the relative decrease in impact energy. The ferrite content and concentration of C in the steel have a strong effect on the overall process of low-temperature embrittlement. The low-carbon CF-3 steels are the most resistant and Mo-containing CF-8M steels are most susceptible to embrittlement. Weakening of the ferrite/austenite phase boundaries by carbide precipitates has a significant effect on the kinetics and extent of embrittlement of the high-carbon CF-8 and CF-8M steels, particularly after aging at temperatures greater than or equal to400/sup 0/C. The influence of N content and distribution of ferrite on loss of toughness are discussed. The data also indicate that existing correlations do not accurately represent the embrittlement behavior over the temperature range 280 to 450/sup 0/C, i.e., extrapolation of high-temperature data to reactor temperatures may not be valid for some compositions of cast stainless steel.

  17. [Ageing rate in workers of mechanic workshops of machinery construction industry in Armenia].

    PubMed

    Sarkisian, G T; Barkhudarov, M S; Kogan, V Iu

    2004-01-01

    Studies of biologic age formation and ageing rate in workers of mechanic workshops revealed that able-bodied population grew old demographically. That is proved by absent age group of 20-29 years and increased share of able-bodied workers older than 50. Young workers aged 30-39 appeared the most vulnerable for occupational hazards--they demonstrated increased ageing rate and maximal excess of biologic age over chronological age and due biologic age.

  18. Aging interferes central control mechanism for eccentric muscle contraction.

    PubMed

    Yao, Wan X; Li, Jinqi; Jiang, Zhiguo; Gao, Jia-Hong; Franklin, Crystal G; Huang, Yufei; Lancaster, Jack L; Yue, Guang H

    2014-01-01

    Previous studies report greater activation in the cortical motor network in controlling eccentric contraction (EC) than concentric contraction (CC) despite lower muscle activation level associated with EC vs. CC in healthy, young individuals. It is unknown, however, whether elderly people exhibiting increased difficulties in performing EC than CC possess this unique cortical control mechanism for EC movements. To address this question, we examined functional magnetic resonance imaging (fMRI) data acquired during EC and CC of the first dorsal interosseous (FDI) muscle in 11 young (20-32 years) and 9 old (67-73 years) individuals. During the fMRI experiment, all subjects performed 20 CC and 20 EC of the right FDI with the same angular distance and velocity. The major findings from the behavioral and fMRI data analysis were that (1) movement stability was poorer in EC than CC in the old but not the young group; (2) similar to previous electrophysiological and fMRI reports, the EC resulted in significantly stronger activation in the motor control network consisting of primary, secondary and association motor cortices than CC in the young and old groups; (3) the biased stronger activation towards EC was significantly greater in the old than the young group especially in the secondary and association cortices such as supplementary and premotor motor areas and anterior cingulate cortex; and (4) in the primary motor and sensory cortices, the biased activation towards EC was significantly greater in the young than the old group. Greater activation in higher-order cortical fields for controlling EC movement by elderly adults may reflect activities in these regions to compensate for aging-related impairments in the ability to control complex EC movements. Our finding is useful for potentially guiding the development of targeted therapies to counteract age-related movement deficits and to prevent injury.

  19. Terrestrial ages of Antarctic meteorites: Implications for concentration mechanisms

    NASA Technical Reports Server (NTRS)

    Schultz, L.

    1986-01-01

    Antarctic meteorites differ from meteorites fallen in other places in their mean terrestrial ages. Boeckl estimated the terrestrial half-life for the disintegration of stone meteorites by weathering under the climatic conditions of the Western United States to be about 3600 years. Antarctic meteorites, however, have terrestrial ages up to 70000 years, indicating larger weathering half-lives. The terrestrial ages of meteorites are determined by their concentration of cosmic-ray-produced radionuclides with suitable half-lives (C-14, Al-26, and Cl-36). These radionuclides have yielded reliable ages for the Antarctic meteorites. The distribution of terrestrial ages of Allan Hills and Yamato meteorites are examined.

  20. Meeting the Expectation of Industry: An Integrated Approach for the Teaching of Mechanics and Electronics to Design Students

    ERIC Educational Resources Information Center

    Bingham, Guy A.; Southee, Darren J.; Page, Tom

    2015-01-01

    This paper examines the traditional engineering-based provision delivered to Product Design and Technology (B.Sc.) undergraduates at the Loughborough Design School and questions its relevancy against the increasing expectations of industry. The paper reviews final-year design projects to understand the level of transference of engineering-based…

  1. Clinicians’ Expectations of Web 2.0 as a Mechanism for Knowledge Transfer of Stroke Best Practices

    PubMed Central

    David, Isabelle; Rochette, Annie

    2012-01-01

    Background Health professionals are increasingly encouraged to adopt an evidence-based practice to ensure greater efficiency of their services. To promote this practice, several strategies exist: distribution of educational materials, local consensus processes, educational outreach visits, local opinion leaders, and reminders. Despite these strategies, gaps continue to be observed between practice and scientific evidence. Therefore, it is important to implement innovative knowledge transfer strategies that will change health professionals’ practices. Through its interactive capacities, Web 2.0 applications are worth exploring. As an example, virtual communities of practice have already begun to influence professional practice. Objective This study was initially developed to help design a Web 2.0 platform for health professionals working with stroke patients. The aim was to gain a better understanding of professionals’ perceptions of Web 2.0 before the development of the platform. Methods A qualitative study following a phenomenological approach was chosen. We conducted individual semi-structured interviews with clinicians and managers. Interview transcripts were subjected to a content analysis. Results Twenty-four female clinicians and managers in Quebec, Canada, aged 28-66 participated. Most participants identified knowledge transfer as the most useful outcome of a Web 2.0 platform. Respondents also expressed their need for a user-friendly platform. Accessibility to a computer and the Internet, features of the Web 2.0 platform, user support, technology skills, and previous technological experience were found to influence perceived ease of use and usefulness. Our results show that the perceived lack of time of health professionals has an influence on perceived behavioral intention to use it despite favorable perception of the usefulness of the Web 2.0 platform. Conclusions In conclusion, female health professionals in Quebec believe that Web 2.0 may be a useful

  2. Aging and Cortical Mechanisms of Speech Perception in Noise

    ERIC Educational Resources Information Center

    Wong, Patrick C. M.; Jin, James Xumin; Gunasekera, Geshri M.; Abel, Rebekah; Lee, Edward R.; Dhar, Sumitrajit

    2009-01-01

    Spoken language processing in noisy environments, a hallmark of the human brain, is subject to age-related decline, even when peripheral hearing might be intact. The present study examines the cortical cerebral hemodynamics (measured by fMRI) associated with such processing in the aging brain. Younger and older subjects identified single words in…

  3. Human fear extinction and return of fear using reconsolidation update mechanisms: the contribution of on-line expectancy ratings.

    PubMed

    Warren, Victor Taylor; Anderson, Kemp M; Kwon, Cliffe; Bosshardt, Lauren; Jovanovic, Tanja; Bradley, Bekh; Norrholm, Seth Davin

    2014-09-01

    Disruption of the reconsolidation of conditioned fear memories has been suggested as a non-pharmacological means of preventing the return of learned fear in human populations. A reconsolidation update paradigm was developed in which a reconsolidation window is opened by a single isolated retrieval trial of a previously reinforced CS+ which is then followed by Extinction Training within that window. However, follow-up studies in humans using multi-methods fear conditioning indices (e.g., fear-potentiated startle, skin conductance, US-expectancy) have failed to replicate the retrieval+extinction effects. In the present study, we further investigated the retrieval+extinction reconsolidation update paradigm by directly comparing the acquisition, extinction, and return of fear-potentiated startle in the absence or presence of US-expectancy measures (using a trial-by-trial response keypad) with and without retrieval of a previously acquired CS-US association. Participants were fear conditioned to two visual cue CS+'s, one of which was presented as a single, isolated retrieval trial before Extinction Training and one that was extinguished as usual. The results show that the inclusion of US-expectancy measures strengthens the CS-US association to provide enhanced fear conditioning and maintenance of fear memories over the experimental sessions. In addition, in the groups that used on-line US-expectancy measures, the retrieval+extinction procedure reduced reinstatement of fear-potentiated startle to both previously reinforced CS+'s, as compared to the extinction as usual group.

  4. Chelation: A Fundamental Mechanism of Action of AGE Inhibitors, AGE Breakers, and Other Inhibitors of Diabetes Complications

    SciTech Connect

    Nagai, Rhoji; Murray, David B.; Metz, Thomas O.; Baynes, John

    2012-03-01

    Advanced glycation or glycoxidation end-products (AGE) increase in tissue proteins with age, and their rate of accumulation is increased in diabetes, nephropathy and inflammatory diseases. AGE inhibitors include a range of compounds that are proposed to act by trapping carbonyl and dicarbonyl intermediates in AGE formation. However, some among the newer generation of AGE inhibitors lack reactive functional groups that would trap reaction intermediates, indicating an alternative mechanism of action. We propose that AGE inhibitors function primarily as chelators, inhibiting metal-catalyzed oxidation reactions. The AGE-inhibitory activity of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers is also consistent with their chelating activity. Finally, compounds described as AGE breakers, or their hydrolysis products, also have strong chelating activity, suggesting that these compounds also act through their chelating activity. We conclude that chelation is the common, and perhaps the primary, mechanism of action of AGE inhibitors and breakers, and that chronic, mild chelation therapy should prove useful in treatment of diabetes and age-related diseases characterized by oxidative stress, inflammation and increased chemical modification of tissue proteins by advanced glycoxidation and lipoxidation end-products.

  5. Aging

    PubMed Central

    Park, Dong Choon

    2013-01-01

    Aging is initiated based on genetic and environmental factors that operate from the time of birth of organisms. Aging induces physiological phenomena such as reduction of cell counts, deterioration of tissue proteins, tissue atrophy, a decrease of the metabolic rate, reduction of body fluids, and calcium metabolism abnormalities, with final progression onto pathological aging. Despite the efforts from many researchers, the progression and the mechanisms of aging are not clearly understood yet. Therefore, the authors would like to introduce several theories which have gained attentions among the published theories up to date; genetic program theory, wear-and-tear theory, telomere theory, endocrine theory, DNA damage hypothesis, error catastrophe theory, the rate of living theory, mitochondrial theory, and free radical theory. Although there have been many studies that have tried to prevent aging and prolong life, here we introduce a couple of theories which have been proven more or less; food, exercise, and diet restriction. PMID:24653904

  6. Great Expectations.

    ERIC Educational Resources Information Center

    Natale, Jo Anna

    1993-01-01

    Inside one Washington, DC, elementary school, Principal John Pannell has high hopes for his students and an expansive school vision. Malcolm X School compensates for disorder outside by clearly inculcating rules and behavior expectations. Children in school uniforms daily repeat a motto promoting Malcolm X as a school of love allowing no hitting,…

  7. Leadership Expectancy.

    ERIC Educational Resources Information Center

    Phillips, Ray C.

    A review of theories of expectation as related to behavior shows a high correlation between educational leaders' perceptions of their faculties and the climate and quality of instructional programs. Thus, effective faculties and high quality educational programs could be linked to a particular type of leadership. Leaders who hold high expectations…

  8. Mechanisms of aging in senescence-accelerated mice

    PubMed Central

    Carter, Todd A; Greenhall, Jennifer A; Yoshida, Shigeo; Fuchs, Sebastian; Helton, Robert; Swaroop, Anand; Lockhart, David J; Barlow, Carrolee

    2005-01-01

    Background Progressive neurological dysfunction is a key aspect of human aging. Because of underlying differences in the aging of mice and humans, useful mouse models have been difficult to obtain and study. We have used gene-expression analysis and polymorphism screening to study molecular senescence of the retina and hippocampus in two rare inbred mouse models of accelerated neurological senescence (SAMP8 and SAMP10) that closely mimic human neurological aging, and in a related normal strain (SAMR1) and an unrelated normal strain (C57BL/6J). Results The majority of age-related gene expression changes were strain-specific, with only a few common pathways found for normal and accelerated neurological aging. Polymorphism screening led to the identification of mutations that could have a direct impact on important disease processes, including a mutation in a fibroblast growth factor gene, Fgf1, and a mutation in and ectopic expression of the gene for the chemokine CCL19, which is involved in the inflammatory response. Conclusion We show that combining the study of inbred mouse strains with interesting traits and gene-expression profiling can lead to the discovery of genes important for complex phenotypes. Furthermore, full-genome polymorphism detection, sequencing and gene-expression profiling of inbred mouse strains with interesting phenotypic differences may provide unique insights into the molecular genetics of late-manifesting complex diseases. PMID:15960800

  9. Discover the network mechanisms underlying the connections between aging and age-related diseases

    PubMed Central

    Yang, Jialiang; Huang, Tao; Song, Won-min; Petralia, Francesca; Mobbs, Charles V.; Zhang, Bin; Zhao, Yong; Schadt, Eric E.; Zhu, Jun; Tu, Zhidong

    2016-01-01

    Although our knowledge of aging has greatly expanded in the past decades, it remains elusive why and how aging contributes to the development of age-related diseases (ARDs). In particular, a global mechanistic understanding of the connections between aging and ARDs is yet to be established. We rely on a network modelling named “GeroNet” to study the connections between aging and more than a hundred diseases. By evaluating topological connections between aging genes and disease genes in over three thousand subnetworks corresponding to various biological processes, we show that aging has stronger connections with ARD genes compared to non-ARD genes in subnetworks corresponding to “response to decreased oxygen levels”, “insulin signalling pathway”, “cell cycle”, etc. Based on subnetwork connectivity, we can correctly “predict” if a disease is age-related and prioritize the biological processes that are involved in connecting to multiple ARDs. Using Alzheimer’s disease (AD) as an example, GeroNet identifies meaningful genes that may play key roles in connecting aging and ARDs. The top modules identified by GeroNet in AD significantly overlap with modules identified from a large scale AD brain gene expression experiment, supporting that GeroNet indeed reveals the underlying biological processes involved in the disease. PMID:27582315

  10. Mechanisms of age-related macular degeneration and therapeutic opportunities.

    PubMed

    van Lookeren Campagne, Menno; LeCouter, Jennifer; Yaspan, Brian L; Ye, Weilan

    2014-01-01

    As the age of the population increases in many nations, age-related degenerative diseases pose significant socioeconomic challenges. One of the key degenerative diseases that compromise quality of life is age-related macular degeneration (AMD). AMD is a multi-faceted condition that affects the central retina, which ultimately leads to blindness in millions of people worldwide. The pathophysiology and risk factors for AMD are complex, and the symptoms manifest in multiple related but distinct forms. The ability to develop effective treatments for AMD will depend on a thorough understanding of the underlying pathophysiology, risk factors, and driver molecular pathways, as well as the ability to develop useful animal models. This review provides an overview of the aforementioned aspects in AMD.

  11. Aging mechanisms in amorphous phase-change materials.

    PubMed

    Raty, Jean Yves; Zhang, Wei; Luckas, Jennifer; Chen, Chao; Mazzarello, Riccardo; Bichara, Christophe; Wuttig, Matthias

    2015-06-24

    Aging is a ubiquitous phenomenon in glasses. In the case of phase-change materials, it leads to a drift in the electrical resistance, which hinders the development of ultrahigh density storage devices. Here we elucidate the aging process in amorphous GeTe, a prototypical phase-change material, by advanced numerical simulations, photothermal deflection spectroscopy and impedance spectroscopy experiments. We show that aging is accompanied by a progressive change of the local chemical order towards the crystalline one. Yet, the glass evolves towards a covalent amorphous network with increasing Peierls distortion, whose structural and electronic properties drift away from those of the resonantly bonded crystal. This behaviour sets phase-change materials apart from conventional glass-forming systems, which display the same local structure and bonding in both phases.

  12. Age differences in the brain mechanisms of good taste.

    PubMed

    Rolls, Edmund T; Kellerhals, Michele B; Nichols, Thomas E

    2015-06-01

    There is strong evidence demonstrating age-related differences in the acceptability of foods and beverages. To examine the neural foundations underlying these age-related differences in the acceptability of different flavors and foods, we performed an fMRI study to investigate brain and hedonic responses to orange juice, orange soda, and vegetable juice in three different age groups: Young (22), Middle (40) and Elderly (60 years). Orange juice and orange soda were found to be liked by all age groups, while vegetable juice was disliked by the Young, but liked by the Elderly. In the insular primary taste cortex, the activations to these stimuli were similar in the 3 age groups, indicating that the differences in liking for these stimuli between the 3 groups were not represented in this first stage of cortical taste processing. In the agranular insula (anterior to the insular primary taste cortex) where flavor is represented, the activations to the stimuli were similar in the Elderly, but in the Young the activations were larger to the vegetable juice than to the orange drinks; and the activations here were correlated with the unpleasantness of the stimuli. In the anterior midcingulate cortex, investigated as a site where the activations were correlated with the unpleasantness of the stimuli, there was again a greater activation to the vegetable than to the orange stimuli in the Young but not in the Elderly. In the amygdala (and orbitofrontal cortex), investigated as sites where the activations were correlated with the pleasantness of the stimuli, there was a smaller activation to the vegetable than to the orange stimuli in the Young but not in the Elderly. The Middle group was intermediate with respect to the separation of their activations to the stimuli in the brain areas that represent the pleasantness or unpleasantness of flavors. Thus age differences in the activations to different flavors can in some brain areas be related to, and probably cause, the

  13. Aging of ErT2 thin films: ERD analysis of mechanical property changes

    SciTech Connect

    Knapp, James A; Bond, Gillian

    2010-01-01

    Rare earth tritide films evolve as tritium decays into 3He, which forms bubbles that influence long-term film stability in applications such as neutron generators. We followed the properties of model ErT2 films as they aged using ERD analysis to monitor T and 3He profiles, nanoindentation testing for mechanical properties and transmission electron microscopy to characterize bubble growth. The profiles of T and 3He are separately measured in ERD using a E - E detector, taking advantage of the differences in energy loss within the E detector. The composition measured by ERD followed the expected build-up of 3He up to near critical release, where 3He begins to escape from the film as bubbles overlap. These measurements complement observations of the changing mechanical properties of these films, where the observed behavior divided into two regimes: a substantial increase in layer hardness but elasticity little changed over 18 months, followed by a decrease in elastic stiffness and a modest decrease in hardness over the final 24 months. The evolution of properties has been explained by a combination of dislocation pinning by the bubbles, elastic softening as the bubbles occupy an increasing fraction of the material, and details of bubble growth modes. The ERD measurements confirm that the changes in properties are due to changes in bubble morphology and not to changes in 3He or T content.

  14. Cellular senescence in aging and age-related disease: from mechanisms to therapy

    PubMed Central

    Childs, Bennett G; Durik, Matej; Baker, Darren J; van Deursen, Jan M

    2016-01-01

    Cellular senescence, a process that imposes permanent proliferative arrest on cells in response to various stressors, has emerged as a potentially important contributor to aging and age-related disease, and it is an attractive target for therapeutic exploitation. A wealth of information about senescence in cultured cells has been acquired over the past half century; however, senescence in living organisms is poorly understood, largely because of technical limitations relating to the identification and characterization of senescent cells in tissues and organs. Furthermore, newly recognized beneficial signaling functions of senescence suggest that indiscriminately targeting senescent cells or modulating their secretome for anti-aging therapy may have negative consequences. Here we discuss current progress and challenges in understanding the stressors that induce senescence in vivo, the cell types that are prone to senesce, and the autocrine and paracrine properties of senescent cells in the contexts of aging and age-related diseases as well as disease therapy. PMID:26646499

  15. Cellular senescence in aging and age-related disease: from mechanisms to therapy.

    PubMed

    Childs, Bennett G; Durik, Matej; Baker, Darren J; van Deursen, Jan M

    2015-12-01

    Cellular senescence, a process that imposes permanent proliferative arrest on cells in response to various stressors, has emerged as a potentially important contributor to aging and age-related disease, and it is an attractive target for therapeutic exploitation. A wealth of information about senescence in cultured cells has been acquired over the past half century; however, senescence in living organisms is poorly understood, largely because of technical limitations relating to the identification and characterization of senescent cells in tissues and organs. Furthermore, newly recognized beneficial signaling functions of senescence suggest that indiscriminately targeting senescent cells or modulating their secretome for anti-aging therapy may have negative consequences. Here we discuss current progress and challenges in understanding the stressors that induce senescence in vivo, the cell types that are prone to senesce, and the autocrine and paracrine properties of senescent cells in the contexts of aging and age-related diseases as well as disease therapy.

  16. Impact of aging mechanism on model simulated carbonaceous aerosols

    PubMed Central

    Huang, Y.; Wu, S.; Dubey, M.K.; French, N. H. F.

    2013-01-01

    Carbonaceous aerosols including organic carbon and black carbon have significant implications for both climate and air quality. In the current global climate or chemical transport models, a fixed hydrophobic-to-hydrophilic conversion lifetime for carbonaceous aerosol (τ) is generally assumed, which is usually around one day. We have implemented a new detailed aging scheme for carbonaceous aerosols in a chemical transport model (GEOS-Chem) to account for both the chemical oxidation and the physical condensation-coagulation effects, where τ is affected by local atmospheric environment including atmospheric concentrations of water vapor, ozone, hydroxyl radical and sulfuric acid. The updated τ exhibits large spatial and temporal variations with the global average (up to 11 km altitude) calculated to be 2.6 days. The chemical aging effects are found to be strongest over the tropical regions driven by the low ozone concentrations and high humidity there. The τ resulted from chemical aging generally decreases with altitude due to increases in ozone concentration and decreases in humidity. The condensation-coagulation effects are found to be most important for the high-latitude areas, in particular the polar regions, where the τ values are calculated to be up to 15 days. When both the chemical aging and condensation-coagulation effects are considered, the total atmospheric burdens and global average lifetimes of BC, black carbon, (OC, organic carbon) are calculated to increase by 9% (3%) compared to the control simulation, with considerable enhancements of BC and OC concentrations in the Southern Hemisphere. Model evaluations against data from multiple datasets show that the updated aging scheme improves model simulations of carbonaceous aerosols for some regions, especially for the remote areas in the Northern Hemisphere. The improvement helps explain the persistent low model bias for carbonaceous aerosols in the Northern Hemisphere reported in literature. Further

  17. Great Expectations for "Great Expectations."

    ERIC Educational Resources Information Center

    Ridley, Cheryl

    Designed to make the study of Dickens'"Great Expectations" an appealing and worthwhile experience, this paper presents a unit of study intended to help students gain (1) an appreciation of Dickens' skill at creating realistic human characters; (2) an insight into the problems of a young man confused by false values and unreal ambitions…

  18. Mechanical Properties of Mass Concrete at Early Ages

    DTIC Science & Technology

    1991-08-01

    material properties during the time that concrete is undergoing the greatest amount of thermal activity and physical change (i.e. early ages, less than 3...Type II, low alkali (LA) portland cement meeting ASTM C 150 and a Class C fly ash meeting ASTM C 618 [11 i]. The fine aggregate was a natural sand...usually require that specially developed or modified models be used. It should also be noted that the use- of high percentages of pozzolans in mass

  19. Chelation: a fundamental mechanism of action of AGE inhibitors, AGE breakers, and other inhibitors of diabetes complications.

    PubMed

    Nagai, Ryoji; Murray, David B; Metz, Thomas O; Baynes, John W

    2012-03-01

    This article outlines evidence that advanced glycation end product (AGE) inhibitors and breakers act primarily as chelators, inhibiting metal-catalyzed oxidation reactions that catalyze AGE formation. We then present evidence that chelation is the most likely mechanism by which ACE inhibitors, angiotensin receptor blockers, and aldose reductase inhibitors inhibit AGE formation in diabetes. Finally, we note several recent studies demonstrating therapeutic benefits of chelators for diabetic cardiovascular and renal disease. We conclude that chronic, low-dose chelation therapy deserves serious consideration as a clinical tool for prevention and treatment of diabetes complications.

  20. What can we expect of normally-developing children implanted at a young age with respect to their auditory, linguistic and cognitive skills?

    PubMed

    van Wieringen, Astrid; Wouters, Jan

    2015-04-01

    As a result of neonatal hearing screening and subsequent early cochlear implantation (CI) profoundly deaf children have access to important information to process auditory signals and master spoken language skills at a young age. Nevertheless, auditory, linguistic and cognitive outcome measures still reveal great variability in individual achievements: some children with CI(s) perform within normal limits, while others lag behind. Understanding the causes of this variation would allow clinicians to offer better prognoses to CI candidates and efficient follow-up and rehabilitation. This paper summarizes what we can expect of normally developing children with CI(s) with regard to spoken language, bilateral and binaural auditory perception, speech perception and cognitive skills. Predictive factors of performance and factors influencing variability are presented, as well as some novel data on cognitive functioning and speech perception in quiet and in noise. Subsequently, we discuss technical and non-technical issues which should be considered in the future in order to optimally guide the child with profound hearing difficulties. This article is part of a Special Issue entitled .

  1. Functional unity of the thymus and pineal gland and study of the mechanisms of aging.

    PubMed

    Polyakova, V O; Linkova, N S; Kvetnoy, I M; Khavinson, V Kh

    2011-09-01

    The data on the morphology and functions of the thymus and pineal gland in individuals of different age are analyzed and common mechanisms of involution of these organs during aging and the consequencies of this process are discussed. Based on the data on the molecular changes in the thymus and pineal gland during aging, the authors hypothesize the functional unity of these organs and their mutual complementarity in the maintenance of normal immune and endocrine status during aging.

  2. Effect of Aging on the Microstructure and Mechanical Properties of Magnesium Alloy AZ31

    NASA Astrophysics Data System (ADS)

    Kerenciler, H.; Gündüz, S.; Erden, M. Akif; Türkmen, M.; Karabulut, H.

    2016-07-01

    The structure and mechanical properties of magnesium alloy AZ31 are studied after conventional and deformation aging under conditions corresponding to the thermal cycle of polymerization in paint coating of cars. The aging is conducted after 3-h solution treatment at 400°C, water quenching, and aging at 180°C for from 10 min to 6 h. Some of the specimens are deformed by 0.5% right after the solution treatment and then aged by the same regime.

  3. Decomposition mechanisms in thermally-aged thin-film explosives

    SciTech Connect

    Erickson, K.L.; Trott, W.M.; Renlund, A.M.

    1994-10-01

    The isothermal decomposition of nitrocellulose (NC) has been examined using two substantially different experimental techniques, involving both confined and unconfined samples. The confined isothermal aging technique involved confined thin-film samples heated to temperatures of 150 to 170{degrees}C, for 1 to 72 hours. Condensed-phase chemistry was monitored real-time using FTIR. Results indicated that the first step in decomposition was scission of the O-NO{sub 2} bond and subsequent formation of carbonyl and hydroxyl products. Scission of the O-NO{sub 2} bond appeared to occur by a first-order reaction. The Arrhenius expression for the first-order reaction rate constant was evaluated from the experimental data. The unconfined rapid isothermal decomposition technique involved both high speed-photography and time-of-flight mass spectrometry (TOFMS). Mass spectra obtained from experiments at 420{degrees}C indicated that NO{sub 2} formation and, therefore, scission of the O-NO{sub 2} bond occurred by a first order reaction, the rate constant for which was evaluated from the experimental data. The rate constant for global pseudo-first order decomposition of NC at 450{degrees}C was also estimated from high speed photography results. Rate constants at 420 and 450{degrees}C were predicted using the Arrhenius expression developed from the confined isothermal aging results and were in good agreement with the rate constants obtained at those temperatures in the unconfined rapid decomposition experiments using TOFMS and high-speed photography. Results from these substantially different measurements gave consistent results over a temperature range of about 300{degrees}C, in which reaction rates vary by nine orders of magnitude, and indicate that the two experimental techniques being developed have good potential for studying condensed-phase decomposition of energetic materials.

  4. Modern evolutionary mechanics theories and resolving the programmed/non-programmed aging controversy.

    PubMed

    Goldsmith, Theodore C

    2014-10-01

    Modern programmed (adaptive) theories of biological aging contend that organisms including mammals have generally evolved mechanisms that purposely limit their lifespans in order to obtain an evolutionary benefit. Modern non-programmed theories contend that mammal aging generally results from natural deteriorative processes, and that lifespan differences between species are explained by differences in the degree to which they resist those processes. Originally proposed in the 19th century, programmed aging in mammals has historically been widely summarily rejected as obviously incompatible with the mechanics of the evolution process. However, relatively recent and continuing developments described here have dramatically changed this situation, and programmed mammal aging now has a better evolutionary basis than non-programmed aging. Resolution of this issue is critically important to medical research because the two theories predict that very different biological mechanisms are ultimately responsible for age-related diseases and conditions.

  5. 77 FR 41457 - Aging Management Associated With Wall Thinning Due to Erosion Mechanisms

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-13

    ... COMMISSION Aging Management Associated With Wall Thinning Due to Erosion Mechanisms AGENCY: Nuclear... Interim Staff Guidance (LR-ISG), LR-ISG-2012-01, ``Wall Thinning Due to Erosion Mechanisms.'' The draft LR... erosion mechanisms for piping and components within the scope of the Requirements for Renewal of...

  6. Humans expect generosity

    NASA Astrophysics Data System (ADS)

    Brañas-Garza, Pablo; Rodríguez-Lara, Ismael; Sánchez, Angel

    2017-02-01

    Mechanisms supporting human ultra-cooperativeness are very much subject to debate. One psychological feature likely to be relevant is the formation of expectations, particularly about receiving cooperative or generous behavior from others. Without such expectations, social life will be seriously impeded and, in turn, expectations leading to satisfactory interactions can become norms and institutionalize cooperation. In this paper, we assess people’s expectations of generosity in a series of controlled experiments using the dictator game. Despite differences in respective roles, involvement in the game, degree of social distance or variation of stakes, the results are conclusive: subjects seldom predict that dictators will behave selfishly (by choosing the Nash equilibrium action, namely giving nothing). The majority of subjects expect that dictators will choose the equal split. This implies that generous behavior is not only observed in the lab, but also expected by subjects. In addition, expectations are accurate, matching closely the donations observed and showing that as a society we have a good grasp of how we interact. Finally, correlation between expectations and actual behavior suggests that expectations can be an important ingredient of generous or cooperative behavior.

  7. Humans expect generosity.

    PubMed

    Brañas-Garza, Pablo; Rodríguez-Lara, Ismael; Sánchez, Angel

    2017-02-14

    Mechanisms supporting human ultra-cooperativeness are very much subject to debate. One psychological feature likely to be relevant is the formation of expectations, particularly about receiving cooperative or generous behavior from others. Without such expectations, social life will be seriously impeded and, in turn, expectations leading to satisfactory interactions can become norms and institutionalize cooperation. In this paper, we assess people's expectations of generosity in a series of controlled experiments using the dictator game. Despite differences in respective roles, involvement in the game, degree of social distance or variation of stakes, the results are conclusive: subjects seldom predict that dictators will behave selfishly (by choosing the Nash equilibrium action, namely giving nothing). The majority of subjects expect that dictators will choose the equal split. This implies that generous behavior is not only observed in the lab, but also expected by subjects. In addition, expectations are accurate, matching closely the donations observed and showing that as a society we have a good grasp of how we interact. Finally, correlation between expectations and actual behavior suggests that expectations can be an important ingredient of generous or cooperative behavior.

  8. Humans expect generosity

    PubMed Central

    Brañas-Garza, Pablo; Rodríguez-Lara, Ismael; Sánchez, Angel

    2017-01-01

    Mechanisms supporting human ultra-cooperativeness are very much subject to debate. One psychological feature likely to be relevant is the formation of expectations, particularly about receiving cooperative or generous behavior from others. Without such expectations, social life will be seriously impeded and, in turn, expectations leading to satisfactory interactions can become norms and institutionalize cooperation. In this paper, we assess people’s expectations of generosity in a series of controlled experiments using the dictator game. Despite differences in respective roles, involvement in the game, degree of social distance or variation of stakes, the results are conclusive: subjects seldom predict that dictators will behave selfishly (by choosing the Nash equilibrium action, namely giving nothing). The majority of subjects expect that dictators will choose the equal split. This implies that generous behavior is not only observed in the lab, but also expected by subjects. In addition, expectations are accurate, matching closely the donations observed and showing that as a society we have a good grasp of how we interact. Finally, correlation between expectations and actual behavior suggests that expectations can be an important ingredient of generous or cooperative behavior. PMID:28195218

  9. Review of mechanical properties and microstructures of Types 304 and 316 stainless steel after long-term aging

    SciTech Connect

    Horak, J.A.; Sikka, V.K.; Raske, D.T.

    1983-01-01

    Because commercial liquid metal fast breeder reactors (LMFBRs) will be designed to last for 35 to 40 years, an understanding of the mechanical behavior of the structural alloys used is required for times of 2.2 to 2.5 x 10/sup 5/ h (assuming a 70% availability factor). Types 304 and 316 stainless steel are used extensively in LMFBR systems. These alloys are in a metastable state when installed and evolve to a more stable state and, therefore, microstructure during plant operation. Correlations of microstructures and mechanical properties during aging under representative LMFBR temperature and loading conditions is desirable from the standpoint of assuring safe, reliable, and economic plant operation. We reviewed the mechanical properties and microstructures of types 304 and 316 stainless steel wrought alloys, welds, and castings after long-term aging in air to 9 x 10/sup 4/ h (about 10-1/2 years). The principal effect of such aging is to reduce fracture toughness (as measured in Charpy impact tests) and tensile ductility. Examples are cited, however, where, because stable microstructures are achieved, these as well as strength-related properties can be expected to remain adequate for service life exposures. 27 figures.

  10. Aging, the Central Nervous System, and Mobility in Older Adults: Neural Mechanisms of Mobility Impairment

    PubMed Central

    Cruz-Almeida, Yenisel; Clark, David J.; Viswanathan, Anand; Scherzer, Clemens R.; De Jager, Philip; Csiszar, Anna; Laurienti, Paul J.; Hausdorff, Jeffery M.; Chen, Wen G.; Ferrucci, Luiggi; Rosano, Caterina; Studenski, Stephanie A.; Black, Sandra E.; Lipsitz, Lewis A.

    2015-01-01

    Background. Mobility is crucial for successful aging and is impaired in many older adults. We know very little about the subtle, subclinical age-related changes in the central nervous system (CNS) that mediate mobility impairment. Methods. A conference series focused on aging, the CNS, and mobility was launched. The second conference addressed major age-associated mechanisms of CNS-mediated mobility impairment. Speakers and conference attendees recommended key areas for future research, identified barriers to progress, and proposed strategies to overcome them. Results. Priorities identified for future research include (a) studying interactions among different mechanisms; (b) examining effects of interventions targeting these mechanisms; (c) evaluating the effect of genetic polymorphisms on risks and course of age-related mobility impairment; and (d) examining the effect of age on CNS repair processes, neuroplasticity, and neuronal compensatory mechanisms. Key strategies to promote research include (a) establish standard measures of mobility across species; (b) evaluate the effect of aging in the absence of disease on CNS and mobility; and (c) use advanced computational methods to better evaluate the interactions between CNS and other systems involved in mobility. Conclusions. CNS is a major player in the process, leading to mobility decline with aging. Future research in this area has the potential to prolong independence in older persons. Better interactions among disciplines and shared research paradigms are needed to make progress. Research priorities include the development of innovative approaches to integrate research on aging, cognition, and movement with attention to neurovascular function, neuroplasticity, and neurophysiological reserve. PMID:26386013

  11. [Single mechanism of remodelling extracellular matrix in thymus and pineal gland at aging].

    PubMed

    Lin'kova, N S; Poliakova, V O; Kvetnoĭ, I M

    2011-01-01

    The expression of matrix metalloproteinase 2 and 9 in thymus and pineal gland has been verified. These data demonstrate single mechanism of remodelling extracellular matrix in thymus and pineal gland at aging.

  12. Advanced glycation end-products: Mechanics of aged collagen from molecule to tissue.

    PubMed

    Gautieri, Alfonso; Passini, Fabian S; Silván, Unai; Guizar-Sicairos, Manuel; Carimati, Giulia; Volpi, Piero; Moretti, Matteo; Schoenhuber, Herbert; Redaelli, Alberto; Berli, Martin; Snedeker, Jess G

    2017-05-01

    Concurrent with a progressive loss of regenerative capacity, connective tissue aging is characterized by a progressive accumulation of Advanced Glycation End-products (AGEs). Besides being part of the typical aging process, type II diabetics are particularly affected by AGE accumulation due to abnormally high levels of systemic glucose that increases the glycation rate of long-lived proteins such as collagen. Although AGEs are associated with a wide range of clinical disorders, the mechanisms by which AGEs contribute to connective tissue disease in aging and diabetes are still poorly understood. The present study harnesses advanced multiscale imaging techniques to characterize a widely employed in vitro model of ribose induced collagen aging and further benchmarks these data against experiments on native human tissues from donors of different age. These efforts yield unprecedented insight into the mechanical changes in collagen tissues across hierarchical scales from molecular, to fiber, to tissue-levels. We observed a linear increase in molecular spacing (from 1.45nm to 1.5nm) and a decrease in the D-period length (from 67.5nm to 67.1nm) in aged tissues, both using the ribose model of in vitro glycation and in native human probes. Multiscale mechanical analysis of in vitro glycated tendons strongly suggests that AGEs reduce tissue viscoelasticity by severely limiting fiber-fiber and fibril-fibril sliding. This study lays an important foundation for interpreting the functional and biological effects of AGEs in collagen connective tissues, by exploiting experimental models of AGEs crosslinking and benchmarking them for the first time against endogenous AGEs in native tissue.

  13. The Role of Exercise in Cardiac Aging: From Physiology to Molecular Mechanisms.

    PubMed

    Roh, Jason; Rhee, James; Chaudhari, Vinita; Rosenzweig, Anthony

    2016-01-22

    Aging induces structural and functional changes in the heart that are associated with increased risk of cardiovascular disease and impaired functional capacity in the elderly. Exercise is a diagnostic and therapeutic tool, with the potential to provide insights into clinical diagnosis and prognosis, as well as the molecular mechanisms by which aging influences cardiac physiology and function. In this review, we first provide an overview of how aging impacts the cardiac response to exercise, and the implications this has for functional capacity in older adults. We then review the underlying molecular mechanisms by which cardiac aging contributes to exercise intolerance, and conversely how exercise training can potentially modulate aging phenotypes in the heart. Finally, we highlight the potential use of these exercise models to complement models of disease in efforts to uncover new therapeutic targets to prevent or treat heart disease in the aging population.

  14. Aging of Stem and Progenitor Cells: Mechanisms, Impact on Therapeutic Potential, and Rejuvenation.

    PubMed

    Nurkovic, Jasmin; Volarevic, Vladislav; Lako, Majlinda; Armstrong, Lyle; Arsenijevic, Nebojsa; Stojkovic, Miodrag

    2016-02-01

    It was once suggested that adult or tissue-specific stem cells may be immortal; however, several recently published data suggest that their efficacy is limited by natural aging in common with most other somatic cell types. Decreased activity of stem cells in old age raises questions as to whether the age of the donor should be considered during stem cell transplantation and at what age the donor stem cells should be harvested to ensure the largest possible number of viable, functional, and non-altered stem cells. Although stem cells remain active into old age, changes in stem cells and their microenvironments inhibit their regenerative potential. The impact of aging on stem cell populations differs between tissues and depends on a number intrinsic and extrinsic factors, including systemic changes associated with immune system alterations. In this review, we describe key mechanisms of stem and progenitor cell aging and techniques that are currently used to identify signs of stem cells aging. Furthermore, we focus on the impact of aging on the capacity for proliferation, differentiation, and clinical use of stem cells. Finally, we detail the aging of embryonic, mesenchymal, and induced pluripotent stem cells, with particular emphasis on aging mechanisms and rejuvenation.

  15. Physicochemical aging mechanisms in soil organic matter assessed by NMR and DSC

    NASA Astrophysics Data System (ADS)

    Schwarz, J.; Jaeger, A.; Bertmer, M.; Schlichting, A.; Leinweber, P.; Schaumann, G. E.

    2009-04-01

    Soil organic matter (SOM) controls a variety of processes occurring at biogeochemical interfaces acting as a highly dynamic matrix. Results from previous studies showed that SOM undergoes physicochemical matrix aging. It was hypothesized that the formation and disruption of water molecule bridges are responsible for this aging process. The objective of this study was to evaluate this hypothesis using three peat samples from different sample sites in Germany: a peat from Rhinluch, 60 km northwest of Berlin, a black peat and a white peat from Fuhrberg near Hannover. The composition determined by pyrolysis field ionisation mass spectrometry was similar for the Rhinluch peat and the Fuhrberg black peat, but showed a distinctly higher carbohydrate content for the Fuhrberg white peat. To elucidate mechanisms of physicochemical matrix aging and to evaluate the hypothesis of water molecule bridges we carried out heating-cooling events in hermetically sealed containers and measured the response by NMR and DSC as a function of time. The heating-cooling event started with heating for 10 minutes at 110 °C followed by rapid cooling and isothermal storage at 19 °C for at least four months. All peats show a non-reversing step transition between 40 °C and 65 °C similar to transitions observed in previous studies. The black peat from Fuhrberg showed an additional step transition between 35 °C and 45 °C. The temperature of the non-reversing step transition immediately decreased by 25 °C in response to the heating-cooling event and slowly re-increased upon isothermal storage within several months. The temperature of the reversing transition showed a similar behaviour but not as strongly as the non-reversing transition. The proton NMR in combination with line separation into Lorentz and Gauss lines was used to differentiate between the different kinds of water. In dependence of the water bridge status the portions of these lines on the total wide line spectrum change; at a

  16. Omega-3 fatty acids and brain resistance to ageing and stress: body of evidence and possible mechanisms.

    PubMed

    Denis, I; Potier, B; Vancassel, S; Heberden, C; Lavialle, M

    2013-03-01

    The increasing life expectancy in the populations of rich countries raises the pressing question of how the elderly can maintain their cognitive function. Cognitive decline is characterised by the loss of short-term memory due to a progressive impairment of the underlying brain cell processes. Age-related brain damage has many causes, some of which may be influenced by diet. An optimal diet may therefore be a practical way of delaying the onset of age-related cognitive decline. Nutritional investigations indicate that the ω-3 poyunsaturated fatty acid (PUFA) content of western diets is too low to provide the brain with an optimal supply of docosahexaenoic acid (DHA), the main ω-3 PUFA in cell membranes. Insufficient brain DHA has been associated with memory impairment, emotional disturbances and altered brain processes in rodents. Human studies suggest that an adequate dietary intake of ω-3 PUFA can slow the age-related cognitive decline and may also protect against the risk of senile dementia. However, despite the many studies in this domain, the beneficial impact of ω-3 PUFA on brain function has only recently been linked to specific mechanisms. This review examines the hypothesis that an optimal brain DHA status, conferred by an adequate ω-3 PUFA intake, limits age-related brain damage by optimizing endogenous brain repair mechanisms. Our analysis of the abundant literature indicates that an adequate amount of DHA in the brain may limit the impact of stress, an important age-aggravating factor, and influences the neuronal and astroglial functions that govern and protect synaptic transmission. This transmission, particularly glutamatergic neurotransmission in the hippocampus, underlies memory formation. The brain DHA status also influences neurogenesis, nested in the hippocampus, which helps maintain cognitive function throughout life. Although there are still gaps in our knowledge of the way ω-3 PUFA act, the mechanistic studies reviewed here indicate that

  17. A comparative study of expectant parents ' childbirth expectations.

    PubMed

    Kao, Bi-Chin; Gau, Meei-Ling; Wu, Shian-Feng; Kuo, Bih-Jaw; Lee, Tsorng-Yeh

    2004-09-01

    The purpose of this study was to understand childbirth expectations and differences in childbirth expectations among expectant parents. For convenience sampling, 200 couples willing to participate in this study were chosen from two hospitals in central Taiwan. Inclusion criteria were at least 36 weeks of gestation, aged 18 and above, no prenatal complications, and willing to consent to participate in this study. Instruments used to collect data included basic demographic data and the Childbirth Expectations Questionnaire. Findings of the study revealed that (1) five factors were identified by expectant parents regarding childbirth expectations including the caregiving environment, expectation of labor pain, spousal support, control and participation, and medical and nursing support; (2) no general differences were identified in the childbirth expectations between expectant fathers and expectant mothers; and (3) expectant fathers with a higher socioeconomic status and who had received prenatal (childbirth) education had higher childbirth expectations, whereas mothers displayed no differences in demographic characteristics. The study results may help clinical healthcare providers better understand differences in expectations during labor and birth and childbirth expectations by expectant parents in order to improve the medical and nursing system and promote positive childbirth experiences and satisfaction for expectant parents.

  18. Characterization of mechanical properties of lamellar structure of the aortic wall: Effect of aging.

    PubMed

    Taghizadeh, Hadi; Tafazzoli-Shadpour, Mohammad

    2017-01-01

    Arterial wall tissues are sensitive to their mechanical surroundings and remodel their structure and mechanical properties when subjected to mechanical stimuli such as increased arterial pressure. Such remodeling is evident in hypertension and aging. Aging is characterized by stiffening of the artery wall which is assigned to disturbed elastin function and increased collagen content. To better understand and provide new insight on microstructural changes induced by aging, the lamellar model of the aortic media was utilized to characterize and compare wall structure and mechanical behavior of the young and old human thoracic aortic samples. Such model regards arterial media as two sets of alternating concentric layers, namely sheets of elastin and interlamellar layers. Histological and biaxial tests were performed and microstructural features and stress-strain curves of media were evaluated in young and old age groups. Then using optimization algorithms and hyperelastic constitutive equations the stress-strain curves of layers were evaluated for both age groups. Results indicated slight elevation in the volume fraction of interlamellar layer among old subjects most probably due to age related collagen deposition. Aging indicated substantial stiffening of interlamellar layers accompanied by noticeable softening of elastic lamellae. The general significant stiffening of old samples were attributed to both increase of volume fraction of interlamellar layers and earlier recruitment of collagen fibers during load bearing due to functional loss of elastin within wall lamellae. Mechanical characterization of lamellar structure of wall media is beneficial in study of arterial remodeling in response to alternated mechanical environment in aging and clinical conditions through coupling of wall microstructure and mechanical behavior.

  19. [The principal mechanisms of age-related involution of wrist bones].

    PubMed

    Pigolkin, Iu I; Fedulova, M V; Iurchenko, M A

    2012-01-01

    The objective of the present study was to elucidate the general mechanisms underlying age-specific changes in the bone tissue of the wrists by the assessment of the signs of their ageing on X-ray images. Roentgenograms of the left wrist of 261 men and 333 women at the age varying from 18 to 90 years were analysed by the planigraphic technique with the use of a scoring system for the estimation of the severity of the signs of ageing (osteoporosis, osteophytes). The study has shown that the signs of ageing in wrist bones become apparent approximately 4-6 years after the completion of ossification. The age-specific changes in the bones are characterized by a strong sexual dimorphism while both the rate of appearance and the intensity of expression of the markers of bone ageing depend on their localization on the radius and phalanges.

  20. Correlation between mechanical and chemical degradation after outdoor and accelerated laboratory aging for multilayer photovoltaic backsheets

    NASA Astrophysics Data System (ADS)

    Lin, Chiao-Chi; Lyu, Yadong; Yu, Li-Chieh; Gu, Xiaohong

    2016-09-01

    Channel cracking fragmentation testing and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy were utilized to study mechanical and chemical degradation of a multilayered backsheet after outdoor and accelerated laboratory aging. A model sample of commercial PPE backsheet, namely polyethylene terephthalate/polyethylene terephthalate/ethylene vinyl acetate (PET/PET/EVA) was investigated. Outdoor aging was performed in Gaithersburg, Maryland, USA for up to 510 days, and complementary accelerated laboratory aging was conducted on the NIST (National Institute of Standards and Technology) SPHERE (Simulated Photodegradation via High Energy Radiant Exposure). Fracture energy, mode I stress intensity factor and film strength were analyzed using an analytical model based on channel cracking fragmentation testing results. The correlation between mechanical and chemical degradation was discussed for both outdoor and accelerated laboratory aging. The results of this work provide preliminary understanding on failure mechanism of backsheets after weathering, laying the groundwork for linking outdoor and indoor accelerated laboratory testing for multilayer photovoltaic backsheets.

  1. Advanced glycoxidation and lipoxidation end products (AGEs and ALEs): an overview of their mechanisms of formation.

    PubMed

    Vistoli, G; De Maddis, D; Cipak, A; Zarkovic, N; Carini, M; Aldini, G

    2013-08-01

    Advanced lipoxidation end products (ALEs) and advanced glycation end products (AGEs) have a pathogenetic role in the development and progression of different oxidative-based diseases including diabetes, atherosclerosis, and neurological disorders. AGEs and ALEs represent a quite complex class of compounds that are formed by different mechanisms, by heterogeneous precursors and that can be formed either exogenously or endogenously. There is a wide interest in AGEs and ALEs involving different aspects of research which are essentially focused on set-up and application of analytical strategies (1) to identify, characterize, and quantify AGEs and ALEs in different pathophysiological conditions; (2) to elucidate the molecular basis of their biological effects; and (3) to discover compounds able to inhibit AGEs/ALEs damaging effects not only as biological tools aimed at validating AGEs/ALEs as drug target, but also as promising drugs. All the above-mentioned research stages require a clear picture of the chemical formation of AGEs/ALEs but this is not simple, due to the complex and heterogeneous pathways, involving different precursors and mechanisms. In view of this intricate scenario, the aim of the present review is to group the main AGEs and ALEs and to describe, for each of them, the precursors and mechanisms of formation.

  2. Effect of delayed aging on mechanical properties of an Al-Cu-Mg alloy

    SciTech Connect

    Ravindranathan, S.P.; Kashyap, K.T.; Kumar, S.R.; Ramachandra, C.; Chatterji, B.

    2000-02-01

    The effect of delayed aging on mechanical properties is characteristically found in Al-Mg-Si alloys. Delayed aging refers to the time elapsed between solutionizing and artificial aging. Delayed aging leads to inferior properties. This effect was investigated in an Al-Cu-Mg alloy (AU2GN) of nominal composition Al-2Cu-1.5Mg-1Fe-1Ni as a function of delay. This alloy also showed a drop in mechanical properties with delay. The results are explained on the basis of Pashley's kinetic model to qualitatively explain the evolution of a coarse precipitate structure with delay. It is found that all the results of delayed aging in the Al-Cu-Mg alloys are similar to those found in Al-Mg-Si alloys.

  3. Molecular Mechanisms of Age-Related Sleep Loss in the Fruit Fly

    PubMed Central

    Robertson, Meagan; Keene, Alex C.

    2013-01-01

    Across phyla, aging is associated with reduced sleep duration and efficiency. Both aging and sleep involve complex genetic architecture and diverse cell types and are heavily influenced by diet and environment. Therefore, understanding the molecular mechanisms of age-dependent changes in sleep will require integrative approaches that go beyond examining these two processes independently. The fruit fly, Drosophila melanogaster, provides a genetically amenable system for dissecting the molecular basis of these processes. In this review, we examine the role of metabolism and circadian rhythms in age-dependent sleep loss. PMID:23594925

  4. Microstructural and Mechanical Property Changes in the Ta-base T-111 Alloy with Aging

    SciTech Connect

    Leonard, Keith J; Busby, Jeremy T; Zinkle, Steven J

    2007-01-01

    The microstructural changes occurring in the Ta-base T-111 (Ta-8W-2Hf) alloy following 1100 h of aging at 1098, 1248 and 1398 K under inert atmosphere and its influence on the mechanical properties are reported. Microstructural evaluations were performed by optical, scanning electron microscopy and, for the first time, transmission electron microscopy. Electrical resistivity, hardness and tensile properties are compared between the as-annealed and aged samples. An increase in the amount of grain boundary precipitation with increasing aging temperature was found to decrease the electrical resistivity and material strength, leading to the eventual embrittlement of the alloy following aging at 1398 K.

  5. Towards aging mechanisms of cross-linked polyethylene (XLPE) cable insulation materials in nuclear power plants

    SciTech Connect

    Liu, Shuaishuai; Fifield, Leonard S.; Bowler, Nicola

    2016-12-19

    Cross-linked polyethylene (XLPE) cable insulation material undergoes simultaneous, accelerated thermal and gamma-radiation aging to simulate the long-term aging environment within nuclear power plants (NPPs). A variety of materials characterization tests, including scanning electron microscopy, thermo-gravimetric analysis, differential scanning calorimetry, oxidation induction time, gel-fraction and dielectric properties measurement, are conducted on pristine and differently aged XLPE samples. A preliminary model of one possible aging mechanism of XLPE cable insulation material under gamma radiation at elevated temperature of 115 °C is suggested.

  6. Why AMD is a disease of ageing and not of development: mechanisms and insights

    PubMed Central

    Sharma, Kaushal; Sharma, Neel Kamal; Anand, Akshay

    2014-01-01

    Ageing disorders can be defined as the progressive and cumulative outcome of several defective cellular mechanisms as well as metabolic pathways, consequently resulting in degeneration. Environment plays an important role in its pathogenesis. In contrast, developmental disorders arise from inherited mutations and usually the role of environmental factors in development of disease is minimal. Age related macular degeneration (AMD) is one such retinal degenerative disorder which starts with the progression of age. Metabolism plays an important role in initiation of such diseases of ageing. Cholesterol metabolism and their oxidized products like 7-ketocholesterol have been shown to adversely impact retinal pigment epithelium (RPE) cells. These molecules can initiate mitochondrial apoptotic processes and also influence the complements factors and expression of angiogenic proteins like VEGF etc. In this review we highlight why and how AMD is an ageing disorder and not a developmental disease substantiated by disrupted cholesterol metabolism common to several age related diseases. PMID:25071560

  7. Impact of temperature on the aging mechanisms of arsenic in soils: fractionation and bioaccessibility.

    PubMed

    Huang, Guanxing; Chen, Zongyu; Wang, Jia; Hou, Qinxuan; Zhang, Ying

    2016-03-01

    The present study focused on the influence of temperature variation on the aging mechanisms of arsenic in soils. The results showed that higher temperature aggravated the decrease of more mobilizable fractions and the increase of less mobilizable or immobilizable fractions in soils over time. During the aging process, the redistribution of both carbonate-bound fraction and specifically sorbed and organic-bound fraction in soils occurred at various temperatures, and the higher temperature accelerated the redistribution of specifically sorbed and organic-bound fraction. The aging processes of arsenic in soils at different temperatures were characterized by several stages, and the aging processes were not complete within 180 days. Arsenic bioaccessibility in soils decreased significantly by the aging, and the decrease was intensified by the higher temperature. In terms of arsenic bioaccessibility, higher temperature accelerated the aging process of arsenic in soils remarkably.

  8. Epigenetic mechanisms underlying lifespan and age-related effects of dietary restriction and the ketogenic diet.

    PubMed

    Moreno, Cesar L; Mobbs, Charles V

    2016-11-22

    Aging constitutes the central risk factor for major diseases including many forms of cancer, neurodegeneration, and cardiovascular diseases. The aging process is characterized by both global and tissue-specific changes in gene expression across taxonomically diverse species. While aging has historically been thought to entail cell-autonomous, even stochastic changes, recent evidence suggests that modulation of this process can be hierarchal, wherein manipulations of nutrient-sensing neurons (e.g., in the hypothalamus) produce peripheral effects that may modulate the aging process itself. The most robust intervention extending lifespan, plausibly impinging on the aging process, involves different modalities of dietary restriction (DR). Lifespan extension by DR is associated with broad protection against diseases (natural and engineered). Here we review potential epigenetic processes that may link lifespan to age-related diseases, particularly in the context of DR and (other) ketogenic diets, focusing on brain and hypothalamic mechanisms.

  9. Age-specific profiles of tissue-level composition and mechanical properties in murine cortical bone

    PubMed Central

    Raghavan, Mekhala; Sahar, Nadder D.; Kohn, David H.; Morris, Michael D.

    2012-01-01

    There is growing evidence that bone composition and tissue-level mechanical properties are significant determinants of skeletal integrity. In the current study, Raman spectroscopy and nanoindentation testing were co-localized to analyze tissue-level compositional and mechanical properties in skeletally mature young (4 or 5 months) and old (19 months) murine femora at similar spatial scales. Standard multivariate linear regression analysis revealed age-dependent patterns in the relationships between mechanical and compositional properties at the tissue scale. However, changes in bone material properties with age are often complex and nonlinear, and can be missed with linear regression and correlation-based methods. A retrospective data mining approach was implemented using non-linear multidimensional visualization and classification to identify spectroscopic and nanoindentation metrics that best discriminated bone specimens of different age-classes. The ability to classify the specimens into the correct age group increased by using combinations of Raman and nanoindentation variables (86–96% accuracy) as compared to using individual measures (59–79% accuracy). Metrics that best classified 4 or 5 month and 19 month specimens (2-age classes) were mineral to matrix ratio, crystallinity, modulus and plasticity index. Metrics that best distinguished between 4, 5 and 19 month specimens (3-age classes) were mineral to matrix ratio, crystallinity, modulus, hardness, cross-linking, carbonate to phosphate ratio, creep displacement and creep viscosity. These findings attest to the complexity of mechanisms underlying bone tissue properties and draw attention to the importance of considering non-linear interactions between tissue-level composition and mechanics that may work together to influence material properties with age. The results demonstrate that a few non-linearly combined compositional and mechanical metrics provide better discriminatory information than a single

  10. Parent Involvement as Parental Monitoring of Student Motivation and Parent Expectations Predicting Later Achievement among African American and European American Middle School Age Students.

    ERIC Educational Resources Information Center

    Seyfried, Sherri F.; Ick-Joong Chung

    2002-01-01

    A study examined the effects of parent involvement and expectations on academic achievement among 567 Black and White middle school students in 18 Seattle (Washington) schools. Parent and teacher surveys indicated that parental involvement was the highest contributor to academic achievement among White students, whereas earlier educational…

  11. Age-related hair changes in men: mechanisms and management of alopecia and graying.

    PubMed

    Mirmirani, Paradi

    2015-01-01

    The appearance of human scalp hair is often tied to perceptions of youth and virility, especially in men. Hair loss, or alopecia and hair graying are commonly associated with advancing age and are frequently a source for emotional distress and anxiety. Our understanding of the complex molecular signals and mechanisms that regulate and influence the hair follicle has expanded in recent years. By harnessing this understanding we are poised to address the esthetic concerns of aging hair. Additionally, changes in the hair follicle may be a reflection of systemic senescent signals, thus because of its accessibility, the hair follicle may serve as an important research tool in gerontology. In this review, the most current knowledge and research regarding mechanisms of androgenetic alopecia, senescent alopecia, and graying are discussed, as are extrinsic factors that may contribute to hair changes with age. Evidence based management strategies for treatment of age-related hair changes are also reviewed.

  12. Mechanical properties of cables exposed to simultaneous thermal and radiation aging

    SciTech Connect

    Jacobus, M.J. ); Fuehrer, G.F. )

    1990-01-01

    Sandia National Laboratories is conducting long-term aging research on representative samples of nuclear power plant Class 1E cables. The objectives of this program are to determine the suitability of these cables for extended life (beyond the 40-year design basis) and to assess various cable condition monitoring (CM) techniques for predicting remaining cable life. This paper provides the results of mechanical measurements that were performed on cable specimens cross-linked polyethylene neoprene jackets: chlorinated polyethylene jackets, fiberglass braid jackets, and chlorosulfonated polyethylene jackets aged at relatively mild, simultaneous thermal and radiation exposure conditions for periods of up to nine months. After aging, some of the aged samples, as well as some unaged samples, were exposed to accident gamma radiation at ambient temperature. The mechanical measurements discussed in this paper include tensile strength, ultimate elongation, and compressive modulus. 10 refs., 22 figs., 2 tabs.

  13. Identification of the mechanisms responsible for static strain ageing in heavily drawn pearlitic steel wires

    NASA Astrophysics Data System (ADS)

    Lamontagne, A.; Kleber, X.; Massardier-Jourdan, V.; Mari, D.

    2014-08-01

    The microstructural changes occurring during drawing and ageing in pearlitic steel wires have been studied using the thermoelectric power (TEP) measurements combined with atom probe tomography (APT) and differential scanning calorimetry (DSC). APT analysis confirmed that cementite dissolution occurs during the cold-drawing process. The high sensitivity of TEP to solute atoms allowed two ageing mechanisms to be identified, both related to a redistribution of carbon atoms. The complementary use of tensile tests and DSC confirmed these results.

  14. Study on the behavior and mechanism of polycarbonate with hot-water aging

    NASA Astrophysics Data System (ADS)

    Kong, L. P.; Zhao, Y. X.; Zhou, C. H.; Huang, Y. H.; Tang, M.; Gao, J. G.

    2016-07-01

    The present work was concerned with hot-water aging behavior and mechanism of Bisphenol A polycarbonate (PC) used as food and packaging materials. It indicated that with the aging time prolonged, PC sample had internal defects and the mechanical properties of PC materials changed not too much, molecular weight decreased, thermal stability declined. Phenolic hydroxyl absorption intensity enhanced in IR spectra and the maximum absorption wavelength red shift of benzene in UV-Vis spectra, the level of BPA increased. The color change of PC sample was not apparent.

  15. Aging behavior and mechanical properties of maraging steels in the presence of submicrocrystalline Laves phase particles

    SciTech Connect

    Mahmoudi, A.; Ghavidel, M.R. Zamanzad; Nedjad, S. Hossein; Heidarzadeh, A.; Ahmadabadi, M. Nili

    2011-10-15

    Cold rolling and annealing of homogenized Fe-Ni-Mn-Mo-Ti-Cr maraging steels resulted in the formation of submicrocrystalline Fe{sub 2}(Mo,Ti) Laves phase particles. Optical and scanning electron microscopy, X-ray diffraction, tensile and hardness tests were used to study the microstructure, aging behavior and mechanical properties of the annealed steels. The annealed microstructures showed age hardenability during subsequent isothermal aging at 753 K. Ultrahigh fracture stress but poor tensile ductility was obtained after substantial age hardening in the specimens with 2% and 4% chromium. Increasing chromium addition up to 6% toughened the aged microstructure at the expense of the fracture stress by increasing the volume fraction of retained austenite. The Laves phase particles acted as crack nucleation sites during tensile deformation. - Highlights: {yields} Laves phases dispersed in a BCC iron matrix by annealing of cold rolled samples. {yields} The samples showed age hardenability during subsequent isothermal aging at 753 K. {yields} Ultrahigh fracture stress but poor ductility was obtained after age hardening. {yields} Increasing chromium addition toughened the aged microstructure. {yields} Laves phase particles acting as crack nucleation sites during tensile deformation.

  16. Age-Related Impairment of Pancreatic Beta-Cell Function: Pathophysiological and Cellular Mechanisms

    PubMed Central

    De Tata, Vincenzo

    2014-01-01

    The incidence of type 2 diabetes significantly increases with age. The relevance of this association is dramatically magnified by the concomitant global aging of the population, but the underlying mechanisms remain to be fully elucidated. Here, some recent advances in this field are reviewed at the level of both the pathophysiology of glucose homeostasis and the cellular senescence of pancreatic islets. Overall, recent results highlight the crucial role of beta-cell dysfunction in the age-related impairment of pancreatic endocrine function and delineate the possibility of new original therapeutic interventions. PMID:25232350

  17. Universal Aging Mechanism for Static and Sliding Friction of Metallic Nanoparticles.

    PubMed

    Feldmann, Michael; Dietzel, Dirk; Tekiel, Antoni; Topple, Jessica; Grütter, Peter; Schirmeisen, André

    2016-07-08

    The term "contact aging" refers to the temporal evolution of the interface between a slider and a substrate usually resulting in increasing friction with time. Current phenomenological models for multiasperity contacts anticipate that such aging is not only the driving force behind the transition from static to sliding friction, but at the same time influences the general dynamics of the sliding friction process. To correlate static and sliding friction on the nanoscale, we show experimental evidence of stick-slip friction for nanoparticles sliding on graphite over a wide dynamic range. We can assign defined periods of aging to the stick phases of the particles, which agree with simulations explicitly including contact aging. Additional slide-hold-slide experiments for the same system allow linking the sliding friction results to static friction measurements, where both friction mechanisms can be universally described by a common aging formalism.

  18. Physical ageing of polyethylene terephthalate under natural sunlight: correlation study between crystallinity and mechanical properties

    NASA Astrophysics Data System (ADS)

    Aljoumaa, Khaled; Abboudi, Maher

    2016-01-01

    Semi-crystalline polyethylene terephthalate (PET) was aged under the effect of natural UV exposure and outdoor temperature during 670 days. The variation in the mechanical and thermal properties beside to the morphology was tracked by applying different analytical techniques, including scanning electron microscopy, infrared spectroscopy, differential scanning calorimetry and wide angle X-ray diffraction, in addition to tensile strength and hardness measurements. It has been confirmed that the ageing process is the results of physical trend only. The aged PET showed a decrease in both tensile strength and strain with an increase in the degree of crystallinity of aged PET samples during the whole period. These changes in crystallinity were examined by various analysis methods: density, calorimetric and infrared spectroscopy. New peaks in FTIR analysis at 1115 and 1090 cm-1 were characterized and proved that this technique is considered to be an easy tool to track the change in the surface crystallinity of aged PET samples directly. The results of this study showed that an augmentation in the degree of crystallinity of outdoor aged PET samples from 18 to 36 %, accompanied with a decrease in tensile strength from 167.9 to 133.7 MPa. Moreover, a good exponential correlation was found between the degree of crystallinity and the mechanical properties of the aged PET.

  19. Mechanisms of vascular calcification in CKD-evidence for premature ageing?

    PubMed

    Shanahan, Catherine M

    2013-11-01

    Ageing is a potent, independent risk factor for cardiovascular disease. Calcification of the vascular smooth muscle cell (VSMC) layer of the vessel media is a hallmark of vascular ageing. Young patients with chronic kidney disease (CKD) exhibit an extremely high cardiovascular mortality, equivalent to that seen in octogenarians in the general population. Even children on dialysis develop accelerated medial vascular calcification and arterial stiffening, leading to the suggestion that patients with CKD exhibit a 'premature ageing' phenotype. It is now well documented that uraemic toxins, particularly those associated with dysregulated mineral metabolism, can drive VSMC damage and phenotypic changes that promote vascular calcification; epidemiological data suggest that some of these same risk factors associate with cardiovascular mortality in the aged general population. Importantly, emerging evidence suggests that uraemic toxins may promote DNA damage, a key factor driving cellular ageing, and moreover, that these ageing mechanisms may reiterate some of those seen in patients with genetically induced progeric syndromes caused by nuclear lamina disruption. This new knowledge should pave the way for the development of novel therapies that target tissue-specific ageing mechanisms to treat vascular decline in CKD.

  20. Oxidative damage and cellular defense mechanisms in sea urchin models of aging.

    PubMed

    Du, Colin; Anderson, Arielle; Lortie, Mae; Parsons, Rachel; Bodnar, Andrea

    2013-10-01

    The free radical, or oxidative stress, theory of aging proposes that the accumulation of oxidative cellular damage is a major contributor to the aging process and a key determinant of species longevity. This study investigates the oxidative stress theory in a novel model for aging research, the sea urchin. Sea urchins present a unique model for the study of aging because of the existence of species with tremendously different natural life spans, including some species with extraordinary longevity and negligible senescence. Cellular oxidative damage, antioxidant capacity, and proteasome enzyme activities were measured in the tissues of three sea urchin species: short-lived Lytechinus variegatus, long-lived Strongylocentrotus franciscanus, and Strongylocentrotus purpuratus, which has an intermediate life span. Levels of protein carbonyls and 4-hydroxynonenal measured in tissues (muscle, nerve, esophagus, gonad, coelomocytes, ampullae) and 8-hydroxy-2'-deoxyguanosine measured in cell-free coelomic fluid showed no general increase with age. The fluorescent age pigment lipofuscin, measured in muscle, nerve, and esophagus, increased with age; however, it appeared to be predominantly extracellular. Antioxidant mechanisms (total antioxidant capacity, superoxide dismutase) and proteasome enzyme activities were maintained with age. In some instances, levels of oxidative damage were lower and antioxidant activity higher in cells or tissues of the long-lived species compared to the short-lived species; however, further studies are required to determine the relationship between oxidative damage and longevity in these animals. Consistent with the predictions of the oxidative stress theory of aging, the results suggest that negligible senescence is accompanied by a lack of accumulation of cellular oxidative damage with age, and maintenance of antioxidant capacity and proteasome enzyme activities may be important mechanisms to mitigate damage.

  1. Oxidative Damage and Cellular Defense Mechanisms in Sea Urchin Models of Aging

    PubMed Central

    Du, Colin; Anderson, Arielle; Lortie, Mae; Parsons, Rachel; Bodnar, Andrea

    2013-01-01

    The free radical or oxidative stress theory of aging proposes that the accumulation of oxidative cellular damage is a major contributor to the aging process and a key determinant of species longevity. This study investigates the oxidative stress theory in a novel model for aging research, the sea urchin. Sea urchins present a unique model for the study of aging due to the existence of species with tremendously different natural life spans including some species with extraordinary longevity and negligible senescence. Cellular oxidative damage, antioxidant capacity and proteasome enzyme activities were measured in the tissues of three sea urchin species: short-lived Lytechinus variegatus, long-lived Strongylocentrotus franciscanus and Strongylocentrotus purpuratus which has an intermediate lifespan. Levels of protein carbonyls and 4-hydroxynonenal (HNE) measured in tissues (muscle, nerve, esophagus, gonad, coelomocytes, ampullae) and 8-hydroxy-2’-deoxyguanosine (8-OHdG) measured in cell-free coelomic fluid showed no general increase with age. The fluorescent age-pigment lipofuscin measured in muscle, nerve and esophagus, increased with age however it appeared to be predominantly extracellular. Antioxidant mechanisms (total antioxidant capacity, superoxide dismutase) and proteasome enzyme activities were maintained with age. In some instances, levels of oxidative damage were lower and antioxidant activity higher in cells or tissues of the long-lived species compared to the short-lived species, however further studies are required to determine the relationship between oxidative damage and longevity in these animals. Consistent with the predictions of the oxidative stress theory of aging, the results suggest that negligible senescence is accompanied by a lack of accumulation of cellular oxidative damage with age and maintenance of antioxidant capacity and proteasome enzyme activities may be important mechanisms to mitigate damage. PMID:23707327

  2. Transient Fluid Flow Along Basement Faults and Rupture Mechanics: Can We Expect Injection-Induced Earthquake Behavior to Correspond Directly With Injection Operations?

    NASA Astrophysics Data System (ADS)

    Norbeck, J. H.; Horne, R. N.

    2015-12-01

    We explored injection-induced earthquake behavior in geologic settings where basement faults are connected hydraulically to overlying saline aquifers targeted for wastewater disposal. Understanding how the interaction between natural geology and injection well operations affects the behavior of injection-induced earthquake sequences has important implications for characterizing seismic hazard risk. Numerical experiments were performed to investigate the extent to which seismicity is influenced by the migration of pressure perturbations along fault zones. Two distinct behaviors were observed: a) earthquake ruptures that were confined to the pressurized region of the fault and b) sustained earthquake ruptures that propagated far beyond the pressure front. These two faulting mechanisms have important implications for assessing the manner in which seismicity can be expected respond to injection well operations.Based upon observations from the numerical experiments, we developed a criterion that can be used to classify the expected faulting behavior near wastewater disposal sites. The faulting criterion depends on the state of stress, the initial fluid pressure, the orientation of the fault, and the dynamic friction coefficient of the fault. If the initial ratio of shear to effective normal stress resolved on the fault (the prestress ratio) is less than the fault's dynamic friction coefficient, then earthquake ruptures will tend to be limited by the distance of the pressure front. In this case, parameters that affect seismic hazard assessment, like the maximum earthquake magnitude or earthquake recurrence interval, could correlate with injection well operational parameters. For example, the maximum earthquake magnitude might be expected to grow over time in a systematic manner as larger patches of the fault are exposed to significant pressure changes. In contrast, if the prestress ratio is greater than dynamic friction, a stress drop can occur outside of the pressurized

  3. Effect of Aging on the Mechanical Properties of Li-Ion Cell Components - A Preliminary Look

    SciTech Connect

    Cao, Lei; Zhang, Chao; Santhanagopalan, Shriram; Pesaran, Ahmad

    2016-05-03

    DOE/VTO/ES initiated the Computer Aided Engineering for Batteries (CAEBAT) in 2010. CAEBAT had a strong focus on building electrochemical-thermal models that simulate the performance of lithium-ion batteries. Since the start of CAEBAT-2 projects in FY14, our emphasis has been on safety aspects -- mechanical deformation in particular. This presentation gives a preliminary look at the effect of aging on the mechanical properties of lithium-ion cell components.

  4. PROGRESSIVE MECHANICAL BEHAVIOR OF HUMAN CORTICAL BONE IN TENSION FOR TWO AGE GROUPS

    PubMed Central

    Nyman, Jeffry S.; Roy, Anuradha; Reyes, Michael J.; Wang, Xiaodu

    2007-01-01

    The capacity of bone for post-yield energy dissipation decreases with age. To gain information on the cause of such changes, we examined the mechanical behavior of human cadaveric bone as a function of progressive deformation. In this study, tensile specimens from tibiae of 9 middle aged and 8 elderly donors were loaded till failure in an incremental and cyclic (load-dwell-unload-dwell-reload) scheme. The elastic modulus, maximum stress, permanent strain, stress relaxation, viscoelastic time constant, plastic strain energy, elastic release strain energy, and hysteresis energy were determined at incremental strains of each loading cycle. Experimental results showed that elderly bone failed at much lower strains compared to middle aged bone, but little age-related differences were observed in the mechanical behavior of bone until the premature failure of elderly bone. Energy dissipation and permanent strain appeared to linearly increase with increasing strain, while non-linear changes occurred in the modulus loss and stress relaxation/time constant with increasing strain. Such changes suggest that two distinct stages may exist in the progressive deformation of bone. In Stage I, rapid damage accumulation and increased involvement of collagen in load bearing appeared to dominate the mechanical behavior of bone with limited energy dissipation (<20% of total energy dissipated), whereas Stage II is dominated by continuous plastic deformation, accompanied by major energy dissipation through all three pathways till failure. This study suggests that damaging mechanisms in bone vary with deformation and age affects the post-yield mechanisms causing a significant decline in the capacity of aged bone to dissipate energy. PMID:18437693

  5. The computer-based Symbol Digit Modalities Test: establishing age-expected performance in healthy controls and evaluation of pediatric MS patients.

    PubMed

    Bigi, Sandra; Marrie, R A; Till, C; Yeh, E A; Akbar, N; Feinstein, A; Banwell, B L

    2017-04-01

    Decreased information processing speed (IPS) is frequently reported in pediatric multiple sclerosis (MS) patients. The computerized version of the Symbol Digit Modalities Test (c-SDMT) measures IPS over eight consecutive trials per session and additionally captures changes in performance within the session. Here, we establish normative c-SDMT performance and test-retest reliability in healthy children (HC) and explore differences in the overall c-SDMT-performance between HC and MS patients. This cross-sectional study included 478 HC (237 female, 49.5%) divided into five age groups (2 years each), and 27 MS patients (22 female, 81.5%) aged 8-18 years. The average time to complete the c-SDMT increased with age (|r| 0.70, 95% CI -0.74, -0.64). Test-retest reliability was high (ICC = 0.91) in HC. The total time to complete the c-SDMT did not differ between children with MS and sex- and age- matched HC (p = 0.23). However, MS patients were less likely to show faster performance across all the successive eight trials compared to HC (p = 0.0001). Healthy children demonstrate faster IPS with increasing age, as well as during successive trials of the c-SDMT. The inability of pediatric MS patients to maintain the increase in processing speed over successive trials suggests a reduced capacity for procedural learning, possibly resulting from cognitive fatigue.

  6. When Age and Culture Interact in an Easy and Yet Cognitively Demanding Task: Older Adults, But Not Younger Adults, Showed the Expected Cultural Differences

    PubMed Central

    Na, Jinkyung; Huang, Chih-Mao; Park, Denise C.

    2017-01-01

    The interaction between age and culture can have various implications for cognition as age represents the effect of biological processes whereas culture represents the effect of sustaining experiences. Nevertheless, their interaction has rarely been examined. Thus, based on the fact that Asians are more intuitive in reasoning than Americans, we examined how this cultural difference might interact with age. Young and old participants from the US and Singapore performed a categorization task (living vs. non-living). To measure their reliance on intuition, we manipulated the typicality of targets (animate vs. inanimate). We showed that (1) RTs for inanimate organisms were slower than RTs for animate organisms (atypicality cost), (2) the cost was particularly large for older adults and (3) an age × culture interaction was observed such that cultural differences in the cost (Singaporeans > Americans) was found only among older participants. Further, we demonstrated that the age effect was associated with cognitive function and the culture effect among older adults was associated with cultural values. Finally, a moderated mediation analysis suggests that cognitive function and cultural values interact with each other in order to jointly influence one’s cognition.

  7. Effects of aging on vasoconstrictor and mechanical properties of rat skeletal muscle arterioles

    NASA Technical Reports Server (NTRS)

    Muller-Delp, Judy; Spier, Scott A.; Ramsey, Michael W.; Lesniewski, Lisa A.; Papadopoulos, Anthony; Humphrey, J. D.; Delp, Michael D.

    2002-01-01

    Exercise capacity and skeletal muscle blood flow during exercise are reduced with advancing age. This reduction in blood flow capacity may be related to increased reactivity of skeletal muscle resistance vessels to vasoconstrictor stimuli. The purpose of this study was to test the hypothesis that aging results in increased vasoconstrictor responses of skeletal muscle resistance arterioles. First-order (1A) arterioles (90-220 microm) from the gastrocnemius and soleus muscles of young (4 mo) and aged (24 mo) Fischer-344 rats were isolated, cannulated, and pressurized via hydrostatic reservoirs. Vasoconstriction in response to increases in norepinephrine (NE; 1 x 10(-9)-1 x 10(-4) M) and KCl (20-100 mM) concentrations and increases in intraluminal pressure (10-130 cmH(2)O) were evaluated in the absence of flow. Responses to NE and KCl were similar in both soleus and gastrocnemius muscle arterioles from young and aged rats. In contrast, active myogenic responses to changes in intraluminal pressure were diminished in soleus and gastrocnemius arterioles from aged rats. To assess whether alterations in the mechanical properties of resistance arterioles underlie altered myogenic responsiveness, passive diameter responses to pressure and mechanical stiffness were evaluated. There was no effect of age on the structural behavior (passive pressure-diameter relationship) or stiffness of arterioles from either the soleus or gastrocnemius muscles. These results suggest that aging does not result in a nonspecific decrease in vasoconstrictor responsiveness of skeletal muscle arterioles. Rather, aging-induced adaptations of vasoreactivity of resistance arterioles appear to be limited to mechanisms that are uniquely involved in the signaling of the myogenic response.

  8. The fragile elderly hip: Mechanisms associated with age-related loss of strength and toughness☆

    PubMed Central

    Reeve, Jonathan; Loveridge, Nigel

    2014-01-01

    Every hip fracture begins with a microscopic crack, which enlarges explosively over microseconds. Most hip fractures in the elderly occur on falling from standing height, usually sideways or backwards. The typically moderate level of trauma very rarely causes fracture in younger people. Here, this paradox is traced to the decline of multiple protective mechanisms at many length scales from nanometres to that of the whole femur. With normal ageing, the femoral neck asymmetrically and progressively loses bone tissue precisely where the cortex is already thinnest and is also compressed in a sideways fall. At the microscopic scale of the basic remodelling unit (BMU) that renews bone tissue, increased numbers of actively remodelling BMUs associated with the reduced mechanical loading in a typically inactive old age augments the numbers of mechanical flaws in the structure potentially capable of initiating cracking. Menopause and over-deep osteoclastic resorption are associated with incomplete BMU refilling leading to excessive porosity, cortical thinning and disconnection of trabeculae. In the femoral cortex, replacement of damaged bone or bone containing dead osteocytes is inefficient, impeding the homeostatic mechanisms that match strength to habitual mechanical usage. In consequence the participation of healthy osteocytes in crack-impeding mechanisms is impaired. Observational studies demonstrate that protective crack deflection in the elderly is reduced. At the most microscopic levels attention now centres on the role of tissue ageing, which may alter the relationship between mineral and matrix that optimises the inhibition of crack progression and on the role of osteocyte ageing and death that impedes tissue maintenance and repair. This review examines recent developments in the understanding of why the elderly hip becomes fragile. This growing understanding is suggesting novel testable approaches for reducing risk of hip fracture that might translate into control

  9. Mechanical properties improvement of silica aerogel through aging: Role of solvent type, time and temperature

    NASA Astrophysics Data System (ADS)

    Omranpour, H.; Dourbash, A.; Motahari, S.

    2014-05-01

    Effective parameters that enhance mechanical properties during aging were investigated in the present study. Silica aerogels were made from tetraethyl orthosilicate (TEOS), water, methanol and NH4F in molar ratio 1:4:8:2×10-3 using a one-step method. Different time, temperature and aging solvents in aging stage were studied. Subsequently, solvent exchange with n-hexane, modification under TMCS solution and ambient pressure drying (APD) were performed for all samples. The aerogels had densities within the range of 0.1 and 0.6 g/cm3. The FTIR, mechanical properties, density and BET results, porosity, pore volume, pore diameter and surface area of the samples, were discussed. The compression properties of the gel increased with the increase in the time and temperature of aging. It was observed that solvents with more polarity improved polymerization, which enhanced the mechanical properties of the related samples. However, the stresses and capillary forces of water during drying were so large that inhibited "spring-back effect" during APD, and consequently a collapsed silica network with higher density was fabricated. In other words, the specific compression strength and modulus declined drastically. For methanol, alcohols inhibit the reactions inconveniently causing more shrinkage. In aging by n-hexane, capillary pressure declined significantly and thereby shrinkage was eliminated and silica aerogels with low bulk densities (0.095 g/cm3), high specific surface areas (600 m2/g), and large pore volumes (2.6 cm3/g) were synthesized.

  10. Increased susceptibility of aging gastric mucosa to injury: the mechanisms and clinical implications.

    PubMed

    Tarnawski, Andrzej S; Ahluwalia, Amrita; Jones, Michael K

    2014-04-28

    This review updates the current views on aging gastric mucosa and the mechanisms of its increased susceptibility to injury. Experimental and clinical studies indicate that gastric mucosa of aging individuals-"aging gastropathy"-has prominent structural and functional abnormalities vs young gastric mucosa. Some of these abnormalities include a partial atrophy of gastric glands, impaired mucosal defense (reduced bicarbonate and prostaglandin generation, decreased sensory innervation), increased susceptibility to injury by a variety of damaging agents such as ethanol, aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs), impaired healing of injury and reduced therapeutic efficacy of ulcer-healing drugs. Detailed analysis of the above changes indicates that the following events occur in aging gastric mucosa: reduced mucosal blood flow and impaired oxygen delivery cause hypoxia, which leads to activation of the early growth response-1 (egr-1) transcription factor. Activation of egr-1, in turn, upregulates the dual specificity phosphatase, phosphatase and tensin homologue deleted on chromosome ten (PTEN) resulting in activation of pro-apoptotic caspase-3 and caspase-9 and reduced expression of the anti-apoptosis protein, survivin. The imbalance between pro- and anti-apoptosis mediators results in increased apoptosis and increased susceptibility to injury. This paradigm has human relevance since increased expression of PTEN and reduced expression of survivin were demonstrated in gastric mucosa of aging individuals. Other potential mechanisms operating in aging gastric mucosa include reduced telomerase activity, increase in replicative cellular senescence, and reduced expression of vascular endothelial growth factor and importin-α-a nuclear transport protein essential for transport of transcription factors to nucleus. Aging gastropathy is an important and clinically relevant issue because of: (1) an aging world population due to prolonged life span; (2) older

  11. Mechanisms of Age-Related Decline in Memory Search across the Adult Life Span

    ERIC Educational Resources Information Center

    Hills, Thomas T.; Mata, Rui; Wilke, Andreas; Samanez-Larkin, Gregory R.

    2013-01-01

    Three alternative mechanisms for age-related decline in memory search have been proposed, which result from either reduced processing speed (global slowing hypothesis), overpersistence on categories (cluster-switching hypothesis), or the inability to maintain focus on local cues related to a decline in working memory (cue-maintenance hypothesis).…

  12. Influence of thermal aging on microstructure and mechanical properties of CLAM steel

    NASA Astrophysics Data System (ADS)

    Huang, Lixin; Hu, Xue; Yang, Chunguang; Yan, Wei; Xiao, Furen; Shan, Yiyin; Yang, Ke

    2013-11-01

    In order to investigate the influence of thermal aging on microstructure and mechanical properties of CLAM (China low activation martensitic) steel, a comparison study was made on the as-tempered and the aged steels. The tempered CLAM steels were subjected to aging treatment at 600 °C for 1100 h and 3000 h, and at 650 °C for 1100 h, respectively. The changes of microstructure were characterized by both transmission electron microscope (TEM) and scanning electron microscope (SEM). The mechanical properties were evaluated by Charpy impact, tensile and Vickers hardness tests. The upper shelf energy (USE) of the thermal aged CLAM steel decreased with the extension of aging time, while the yield strength changed slightly. After long-term thermal aging, the MX type precipitates remained stable. The coarsening of M23C6 and the formation of Laves phase were confirmed by scanning/transmission electron microscopes. The Laves phase was the main factor leading to the increase of DBTT.

  13. Advanced paternal age effects in neurodevelopmental disorders—review of potential underlying mechanisms

    PubMed Central

    Janecka, M; Mill, J; Basson, M A; Goriely, A; Spiers, H; Reichenberg, A; Schalkwyk, L; Fernandes, C

    2017-01-01

    Multiple epidemiological studies suggest a relationship between advanced paternal age (APA) at conception and adverse neurodevelopmental outcomes in offspring, particularly with regard to increased risk for autism and schizophrenia. Conclusive evidence about how age-related changes in paternal gametes, or age-independent behavioral traits affect neural development is still lacking. Recent evidence suggests that the origins of APA effects are likely to be multidimensional, involving both inherited predisposition and de novo events. Here we provide a review of the epidemiological and molecular findings to date. Focusing on the latter, we present the evidence for genetic and epigenetic mechanisms underpinning the association between late fatherhood and disorder in offspring. We also discuss the limitations of the APA literature. We propose that different hypotheses relating to the origins of the APA effects are not mutually exclusive. Instead, multiple mechanisms likely contribute, reflecting the etiological complexity of neurodevelopmental disorders. PMID:28140401

  14. The effect of aging, temperature and brine composition on the mechanical strength of chalk

    NASA Astrophysics Data System (ADS)

    Korsnes, Reidar Inge; Nermoen, Anders; Stødle, Trond; Vika Storm, Eirik; Vadla Madland, Merete

    2014-05-01

    Chalk strength has been of great focus for several research communities since the 1980s when the Ekofisk subsidence problem was discovered. Sea water injection was initiated in 1987 to improve the oil production and to re-pressurize the reservoirs to halt the subsidence. The oil production was improved significantly, but the reservoir compaction in the water saturated regions continued, in contrast to the regions with no water breakthrough. This observation indicates a water weakening effect of the chalk. Extensive studies have been performed during the last decades to enlighten how the brine chemistry alters the rock mechanical properties. These studies have shown that the elastic bulk modulus, yield strength, creep and the deformation rate at constant stress conditions depend on the pore fluid composition. In general, the injected brine is in non-equilibrium with the rock surface inducing alteration of the rock mineralogy. In this study we examined two aspects of the mechanical strength, namely the bulk modulus and the onset of yield during hydrostatic stress loading with 0.7 MPa pore pressure. The test program consisted of aged and un-aged cores, ambient and 130°C test temperature, and four brine compositions: MgCl2, NaCl, Na2SO4, and synthetic sea water (SSW) at ion strengths of 0.657 M. The aging was performed by submerging saturated cores in a closed container with the respective test brine for three weeks at 130°C. Un-aged cores were saturated the same day as they were tested. For each brine composition we present four test setups; (a) aged and tested at 130°C, (b) aged and tested at ambient temperature, (c) un-aged and tested at 130°C, and (d) un-aged and tested at ambient conditions. The main results from our study are: 1. By using NaCl and MgCl2 as saturating brines, neither the test temperature nor the aging procedure affected the yield stress and bulk modulus significantly. 2. Using Na2SO4, the yield point and bulk moduli were reduced if the core

  15. Mechanical properties and microstructure of long term thermal aged WWER 440 RPV steel

    NASA Astrophysics Data System (ADS)

    Kolluri, M.; Kryukov, A.; Magielsen, A. J.; Hähner, P.; Petrosyan, V.; Sevikyan, G.; Szaraz, Z.

    2017-04-01

    The integrity assessment of the Reactor Pressure Vessel (RPV) is essential for the safe and Long Term Operation (LTO) of a Nuclear Power Plant (NPP). Hardening and embrittlement of RPV caused by neutron irradiation and thermal ageing are main reasons for mechanical properties degradation during the operation of an NPP. The thermal ageing-induced degradation of RPV steels becomes more significant with extended operational lives of NPPs. Consequently, the evaluation of thermal ageing effects is important for the structural integrity assessments required for the lifetime extension of NPPs. As a part of NRG's research programme on Structural Materials for safe-LTO of Light Water Reactor (LWR) RPVs, WWER-440 surveillance specimens, which have been thermal aged for 27 years (∼200,000 h) at 290 °C in a surveillance channel of Armenian-NPP, are investigated. Results from the mechanical and microstructural examination of these thermal aged specimens are presented in this article. The results indicate the absence of significant long term thermal ageing effect of 15Cr2MoV-A steel. No age hardening was detected in aged tensile specimens compared with the as-received condition. There is no difference between the impact properties of as-received and thermal aged weld metals. The upper shelf energy of the aged steel remains the same as for the as-received material at a rather high level of about 120 J. The T41 value did not change and was found to be about 10 °C. The microstructure of thermal aged weld, consisting carbides, carbonitrides and manganese-silicon inclusions, did not change significantly compared to as-received state. Grain-boundary segregation of phosphorus in long term aged weld is not significant either which has been confirmed by the absence of intergranular fracture increase in the weld. Negligible hardening and embrittlement observed after such long term thermal ageing is attributed to the optimum chemical composition of 15Cr2MoV-A for high thermal stability.

  16. Mechanisms of Muscle Denervation in Aging: Insights from a Mouse Model of Amyotrophic Lateral Sclerosis

    PubMed Central

    Park, Kevin H.J

    2015-01-01

    Muscle denervation at the neuromuscular junction (NMJ) is thought to be a contributing factor in age-related muscle weakness. Therefore, understanding the mechanisms that modulate NMJ innervation is a key to developing therapies to combat age-related muscle weakness affecting the elderly. Two mouse models, one lacking the Cu/Zn superoxide dismutase (SOD1) gene and another harboring the transgenic mutant human SOD1 gene, display progressive changes at the NMJ, including muscle endplate fragmentation, nerve terminal sprouting, and denervation. These changes at the NMJ share many of the common features observed in the NMJs of aged mice. In this review, research findings demonstrating the effects of PGC-1α, IGF-1, GDNF, MyoD, myogenin, and miR-206 on NMJ innervation patterns in the G93A SOD1 mice will be highlighted in the context of age-related muscle denervation. PMID:26425392

  17. Organic chemical aging mechanisms: An annotated bibliography. Waste Tank Safety Program

    SciTech Connect

    Samuels, W.D.; Camaioni, D.M.; Nelson, D.A.

    1993-09-01

    An annotated bibliography has been compiled of the potential chemical and radiological aging mechanisms of the organic constituents (non-ferrocyanide) that would likely be found in the UST at Hanford. The majority of the work that has been conducted on the aging of organic chemicals used for extraction and processing of nuclear materials has been in conjunction with the acid or PUREX type processes. At Hanford the waste being stored in the UST has been stabilized with caustic. The aging factors that were used in this work were radiolysis, hydrolysis and nitrite/nitrate oxidation. The purpose of this work was two-fold: to determine whether or not research had been or is currently being conducted on the species associated with the Hanford UST waste, either as a mixture or as individual chemicals or chemical functionalities, and to determine what areas of chemical aging need to be addressed by further research.

  18. The role of aging on the mechanical and microstructural response of aluminum 6061 to one-dimensional shock loading

    NASA Astrophysics Data System (ADS)

    Millett, J. C. F.; Bourne, N. K.; Chu, M. Q.; Jones, I. P.; Gray, G. T.; Appleby-Thomas, G.

    2010-10-01

    The shock response of the aluminum alloy 6061, and its variation according to heat treatment have been monitored via the placement of stress gauges in such orientations so as to be sensitive to the lateral component of stress, and hence the shear strength. To complement these measurements, the postshock microstructure and mechanical response have also been determined via full one-dimensional recovery techniques. Results have shown that the solution treated (T0) state, as a largely single phase material displays a fast rising shock pulse with a significant degree of hardening behind the shock front. This indicates that a high degree of dislocation generation is expected. Postshock analysis of recovered samples has confirmed this hypothesis, with dislocation cells being observed and a notable increase in the yield strength in comparison to the as-received material. In contrast, the aged (T6) experiments showed a much longer rise time with a lower degree of hardening behind the shock front. Microstructural analysis postshock shows a more randomized dislocation distribution, with little or no postshock hardening occurring once the shock induced strain has been accounted for. This has been attributed to the presence of fine Mg2Si precipitates inhibiting the motion and generation of dislocations. These measurements are in agreement with work previously carried out on this material. Comparison of the shear strengths of the two heat treatments also shows that although the T6 condition is a little higher than T0, the differences are somewhat lower than expected.

  19. Mechanism of Origin of Conduction Disturbances in Aging Human Atrial Bundles: Experimental and Model Study

    PubMed Central

    Spach, Madison S.; Heidlage, J. Francis; Dolber, Paul C.; Barr, Roger C.

    2007-01-01

    BACKGROUND Aging is associated with a significant increase in atrial tachyarrhythmias, especially atrial fibrillation. A macroscopic repolarization gradient created artificially by a stimulus at one site prior to a premature stimulus from a second site is widely considered to be part of the experimental protocol necessary for the initiation of such arrhythmias in the laboratory. How such gradients occur naturally in aging atrial tissue has remained unknown. OBJECTIVE This study was to determine if the pattern of cellular connectivity in aging human atrial bundles produces a mechanism for variable early premature responses. METHODS Extracellular and intracellular potentials were recorded following control and premature stimuli at a single site in aging human atrial bundles. We also measured cellular geometry, the distribution of connexins, and the distribution of collagenous septa. A model of the atrial bundles was constructed based on the morphological results. Action potential propagation and the sodium current were analyzed following premature stimuli in the model. RESULTS Similar extracellular potential waveform responses occurred following early premature stimuli in the aging bundles and in the model. Variable premature conduction patterns were accounted for by the single model of aging atrial structure. A major feature of the model results was that the conduction events and the magnitude of the sodium current at multiple sites were very sensitive to small changes in the location and the timing of premature stimuli. CONCLUSION In aging human atrial bundles stimulated from only a single site, premature stimuli induce variable arrhythmogenic conduction responses. The generation of these responses is greatly enhanced by remodeling of cellular connectivity during aging. The results provide insight into sodium current-structural interactions as a general mechanism of arrhythmogenic atrial responses to premature stimuli. PMID:17275753

  20. Effect of Cyclic Aging on Mechanical Properties and Microstructure of Maraging Steel 250

    NASA Astrophysics Data System (ADS)

    Tariq, Fawad; Naz, Nausheen; Baloch, Rasheed Ahmed

    2010-10-01

    The effects of thermal cyclic aging on mechanical properties and microstructure of maraging steel 250 were studied using hardness tester, tensile testing machine, impact tester, optical, scanning electron, and stereo microscopy. Samples were solution annealed at 1093 K for 1 h followed by air cooling to form bcc martensite. Cyclic aging treatments were carried out at 753 and 773 K for varying time periods. Increase in hardness and strength with corresponding decrease in ductility and impact strength was observed with increasing aging cycles. Reverted austenite was detected by x-ray diffraction technique formed as a result of cyclic aging. The presence of reverted γ was also confirmed by EDX-SEM analysis and attributed to the formation of Mo- and Ni-rich regions which transformed to γ on cooling. Heterogeneity in composition and amount of reverted γ was found to increase with increase in aging cycles and aging time. Fractography reveals the change in fracture mode from ductile dimple-like to brittle cleavage with increase in hardness and strength due to cyclic aging.

  1. An investigation on microstructure and mechanical property of thermally aged stainless steel weld overlay cladding

    NASA Astrophysics Data System (ADS)

    Cao, X. Y.; Zhu, P.; Ding, X. F.; Lu, Y. H.; Shoji, T.

    2017-04-01

    Microstructural evolution and mechanical property change of E308L stainless steel weld overlay cladding aged at 400 °C for 400, 1000 and 5000 h were investigated by transmission electron microscope (TEM) and small punch test (SPT). The results indicated that thermal aging had no obvious effect on the volume fraction of ferrite, but can cause microstructural evolution by spinodal decomposotion and G-phase precipitation in the ferrite phase. Spinodal decomposition took place after aging up to 1000 h, while G-phase formed along dislocations, and growed up to 2-11 nm after aging for 5000 h. The total energy for inducing deformation and fracture by the small punch tests decreased with the increase of thermal aging time, and this decline was associated with spinodal decomposition and G-phase precipitation. Plastic deformation of the aged ferrite proceeded via formation of curvilinear slip bands. Nucleation of microcracks occurred at the δ/γ interface along the slip bands. The hardening of the ferrite and high stress concentration on δ/γ phase interface resulted in brittle fracture and phase boundary separation after thermal aging.

  2. Aging of running shoes and its effect on mechanical and biomechanical variables: implications for runners.

    PubMed

    Chambon, Nicolas; Sevrez, Violaine; Ly, Quoc Hung; Guéguen, Nils; Berton, Eric; Rao, Guillaume

    2014-01-01

    This study investigates the effect of running shoes' aging on mechanical and biomechanical parameters as a function of midsole materials (viscous, intermediate, elastic) and ground inclination. To this aim, heel area of the shoe (under calcaneal tuberosity) was first mechanically aged at realistic frequency and impact magnitudes based on a 660 km training plan. Stiffness (ST) and viscosity were then measured on both aged and matching new shoes, and repercussions on biomechanical variables (joint kinematics, muscular pre-activation, vertical ground reaction force and tibial acceleration) were assessed during a leg-extended stepping-down task designed to mimic the characteristics of running impacts. Shoes' aging led to increased ST (means: from 127 to 154 N ∙ mm(-1)) and decreased energy dissipation (viscosity) (means: from 2.19 to 1.88 J). The effects induced by mechanical changes on body kinematics were very small. However, they led with the elastic shoe to increased vastus lateralis pre-activation, tibial acceleration peak (means: from 4.5 g to 5.2 g) and rate. Among the three shoes tested, the shoe with intermediate midsole foam provided the best compromise between viscosity and elasticity. The optimum balance remains to be found for the design of shoes regarding at once cushioning, durability and injury prevention.

  3. The Antioxidant Mechanisms Underlying the Aged Garlic Extract- and S-Allylcysteine-Induced Protection

    PubMed Central

    Colín-González, Ana L.; Santana, Ricardo A.; Silva-Islas, Carlos A.; Chánez-Cárdenas, Maria E.; Santamaría, Abel; Maldonado, Perla D.

    2012-01-01

    Aged garlic extract (AGE) is an odorless garlic preparation containing S-allylcysteine (SAC) as its most abundant compound. A large number of studies have demonstrated the antioxidant activity of AGE and SAC in both in vivo—in diverse experimental animal models associated to oxidative stress—and in vitro conditions—using several methods to scavenge reactive oxygen species or to induce oxidative damage. Derived from these experiments, the protective effects of AGE and SAC have been associated with the prevention or amelioration of oxidative stress. In this work, we reviewed different antioxidant mechanisms (scavenging of free radicals and prooxidant species, induction of antioxidant enzymes, activation of Nrf2 factor, inhibition of prooxidant enzymes, and chelating effects) involved in the protective actions of AGE and SAC, thereby emphasizing their potential use as therapeutic agents. In addition, we highlight the ability of SAC to activate Nrf2 factor—a master regulator of the cellular redox state. Here, we include original data showing the ability of SAC to activate Nrf2 factor in cerebral cortex. Therefore, we conclude that the therapeutic properties of these molecules comprise cellular and molecular mechanisms at different levels. PMID:22685624

  4. Mechanisms of premature vascular aging in children with Hutchinson-Gilford progeria syndrome.

    PubMed

    Gerhard-Herman, Marie; Smoot, Leslie B; Wake, Nicole; Kieran, Mark W; Kleinman, Monica E; Miller, David T; Schwartzman, Armin; Giobbie-Hurder, Anita; Neuberg, Donna; Gordon, Leslie B

    2012-01-01

    Hutchinson-Gilford progeria syndrome is a rare, segmental premature aging syndrome of accelerated atherosclerosis and early death from myocardial infarction or stroke. This study sought to establish comprehensive characterization of the fatal vasculopathy in Hutchinson-Gilford progeria syndrome and its relevance to normal aging. We performed cardiovascular assessments at a single clinical site on the largest prospectively studied cohort to date. Carotid-femoral pulse wave velocity was dramatically elevated (mean: 13.00±3.83 m/s). Carotid duplex ultrasound echobrightness, assessed in predefined tissue sites as a measure of arterial wall density, was significantly greater than age- and sex-matched controls in the intima-media (P<0.02), near adventitia (P<0.003), and deep adventitia (P<0.01), as was internal carotid artery mean flow velocity (P<0.0001). Ankle-brachial indices were abnormal in 78% of patients. Effective disease treatments may be heralded by normalizing trends of these noninvasive cardiovascular measures. The data demonstrate that, along with peripheral vascular occlusive disease, accelerated vascular stiffening is an early and pervasive mechanism of vascular disease in Hutchinson-Gilford progeria syndrome. There is considerable overlap with cardiovascular changes of normal aging, which reinforces the view that defining mechanisms of cardiovascular disease in Hutchinson-Gilford progeria syndrome provides a unique opportunity to isolate a subset of factors influencing cardiovascular disease in the general aging population.

  5. Cell-autonomous mechanisms of chronological aging in the yeast Saccharomyces cerevisiae

    PubMed Central

    Arlia-Ciommo, Anthony; Leonov, Anna; Piano, Amanda; Svistkova, Veronika; Titorenko, Vladimir I.

    2014-01-01

    A body of evidence supports the view that the signaling pathways governing cellular aging - as well as mechanisms of their modulation by longevity-extending genetic, dietary and pharmacological interventions - are conserved across species. The scope of this review is to critically analyze recent advances in our understanding of cell-autonomous mechanisms of chronological aging in the budding yeast Saccharomyces cerevisiae. Based on our analysis, we propose a concept of a biomolecular network underlying the chronology of cellular aging in yeast. The concept posits that such network progresses through a series of lifespan checkpoints. At each of these checkpoints, the intracellular concentrations of some key intermediates and products of certain metabolic pathways - as well as the rates of coordinated flow of such metabolites within an intricate network of intercompartmental communications - are monitored by some checkpoint-specific ʺmaster regulatorʺ proteins. The concept envisions that a synergistic action of these master regulator proteins at certain early-life and late-life checkpoints modulates the rates and efficiencies of progression of such processes as cell metabolism, growth, proliferation, stress resistance, macromolecular homeostasis, survival and death. The concept predicts that, by modulating these vital cellular processes throughout lifespan (i.e., prior to an arrest of cell growth and division, and following such arrest), the checkpoint-specific master regulator proteins orchestrate the development and maintenance of a pro- or anti-aging cellular pattern and, thus, define longevity of chronologically aging yeast. PMID:28357241

  6. Microstructure Evolution and Mechanical Properties of 2219 Al Alloy During Aging Treatment

    NASA Astrophysics Data System (ADS)

    Wang, Huimin; Yi, Youping; Huang, Shiquan

    2017-03-01

    Hardness and tensile properties of 2219 Al alloys were tested at various temperature (150, 165, 175 °C) and subjected to T6 temper heat treatment to identify the peak aging time at various temperature. Microstructure evolution and precipitate behavior were analyzed with transmission electron microscope (TEM), differential scanning calorimetry (DSC) and x-ray diffraction (XRD). It is found that the peak aging time is 24 h at 150 °C and does not vary down to 165 °C. When the aging temperature rise to 175 °C, the peak aging time down to 12 h. Considering the strength and elongation, the optimum aging treatment is at 165 °C for 24 h after the solution treatment at 535 °C for 1.5 h. Compared with that of only water-quenched sample, after aged at 165 °C for 24 h, the tensile strength of the 2219 Al alloy increases from 324.5 to 411.8 MPa, yield strength from 168 to 310.8 MPa, respectively. The improvement in the mechanical performance is mainly attributed to the precipitation strengthening of the GP zones, θ″ and θ' phases.

  7. Barriers to the Preclinical Development of Therapeutics that Target Aging Mechanisms.

    PubMed

    Burd, Christin E; Gill, Matthew S; Niedernhofer, Laura J; Robbins, Paul D; Austad, Steven N; Barzilai, Nir; Kirkland, James L

    2016-11-01

    Through the progress of basic science research, fundamental mechanisms that contribute to age-related decline are being described with increasing depth and detail. Although these efforts have identified new drug targets and compounds that extend life span in model organisms, clinical trials of therapeutics that target aging processes remain scarce. Progress in aging research is hindered by barriers associated with the translation of basic science discoveries into the clinic. This report summarizes discussions held at a 2014 Geroscience Network retreat focused on identifying hurdles that currently impede the preclinical development of drugs targeting fundamental aging processes. From these discussions, it was evident that aging researchers have varied perceptions of the ideal preclinical pipeline. To forge a clear and cohesive path forward, several areas of controversy must first be resolved and new tools developed. Here, we focus on five key issues in preclinical drug development (drug discovery, lead compound development, translational preclinical biomarkers, funding, and integration between researchers and clinicians), expanding upon discussions held at the Geroscience Retreat and suggesting areas for further research. By bringing these findings to the attention of the aging research community, we hope to lay the foundation for a concerted preclinical drug development pipeline.

  8. Barriers to the Preclinical Development of Therapeutics that Target Aging Mechanisms

    PubMed Central

    Burd, Christin E.; Gill, Matthew S.; Niedernhofer, Laura J.; Robbins, Paul D.; Austad, Steven N.; Barzilai, Nir

    2016-01-01

    Through the progress of basic science research, fundamental mechanisms that contribute to age-related decline are being described with increasing depth and detail. Although these efforts have identified new drug targets and compounds that extend life span in model organisms, clinical trials of therapeutics that target aging processes remain scarce. Progress in aging research is hindered by barriers associated with the translation of basic science discoveries into the clinic. This report summarizes discussions held at a 2014 Geroscience Network retreat focused on identifying hurdles that currently impede the preclinical development of drugs targeting fundamental aging processes. From these discussions, it was evident that aging researchers have varied perceptions of the ideal preclinical pipeline. To forge a clear and cohesive path forward, several areas of controversy must first be resolved and new tools developed. Here, we focus on five key issues in preclinical drug development (drug discovery, lead compound development, translational preclinical biomarkers, funding, and integration between researchers and clinicians), expanding upon discussions held at the Geroscience Retreat and suggesting areas for further research. By bringing these findings to the attention of the aging research community, we hope to lay the foundation for a concerted preclinical drug development pipeline. PMID:27535964

  9. Statistically tested comparisons of the accuracy of forecasting methods for age-specific and sex-specific mortality and life expectancy.

    PubMed

    Shang, Han Lin

    2015-01-01

    Although there are continuing developments in the methods for forecasting mortality, there are few comparisons of the accuracy of the forecasts. The subject of the statistical validity of these comparisons, which is essential to demographic forecasting, has all but been ignored. We introduce Friedman's test statistics to examine whether the differences in point and interval forecast accuracies are statistically significant between methods. We introduce the Nemenyi test statistic to identify which methods give results that are statistically significantly different from others. Using sex-specific and age-specific data from 20 countries, we apply these two test statistics to examine the forecast accuracy obtained from several principal component methods, which can be categorized into coherent and non-coherent forecasting methods.

  10. Cognitive change in aging: identifying gene-environment correlation and nonshared environment mechanisms.

    PubMed

    Deater-Deckard, Kirby; Mayr, Ulrich

    2005-03-01

    We describe gene-environment processes that may help account for individual differences in successful aging. Our emphasis is on successful aging in the cognitive domain, wherein individuals come to use a variety of strategies to cope with changes in cognitive capacities. We focus on the role of executive control in particular and define gene-environment correlation and nonshared environmental mechanisms. The quantitative genetic methods used to identify these mechanisms are described, with examples from research in childhood, where such studies are now common. Future work will be most effective if it is guided by life-span development frameworks that address these processes, such as the developmental genotype-->environment theory of Scarr and McCartney and the selection/optimization/compensation theory of Baltes and Baltes.

  11. Nanomechanical characterization and mechanical integrity of unaged and aged Li-ion battery cathodes

    NASA Astrophysics Data System (ADS)

    Ramdon, Sanjay; Bhushan, Bharat

    2014-01-01

    Lithium-ion (Li-ion) batteries have been implemented for numerous applications, one of which is in plug-in hybrid electric vehicles (PHEV) and pure electric vehicles (EV). In an effort to prolong battery life it is important to understand the mechanisms that cause reduced battery capacity with aging. In this work, nanomechanical characterization and mechanical integrity studies were carried out on unaged and aged LiFePO4 battery cathodes using atomic force microscopy (AFM) and nanoindentation. Changes in hardness, elastic modulus, creep, nanowear, nanoscratch and nanofriction properties were measured. Measured changes are believed to occur as a result of coarsening and agglomeration of LiFePO4 nanoparticles.

  12. Forming patterns and mechanical properties of austenitic chromium-nickel steel due to strain aging

    NASA Astrophysics Data System (ADS)

    Kamyshanchenko, N. V.; Krasilnikov, V. V.; Nikulin, I. S.; Gal'tsev, A. V.; Belenko, V. A.; Gal'tseva, I. N.

    2016-02-01

    The work presents the results of studies of forming patterns and mechanical properties of martensite transformation, found in the chromium-nickel steels of 08X18H10T grade, subjected to pre-heat treatment followed by deformation aging. Internal energy state is determined by using acoustic emission. The observed patterns improve the mechanical parameters of steels quenched and plastically deformed at low temperature and then subjected to temper under load in the optimum temperature being associated with obtaining a more stable condition of the structure through the processes of relaxation of internal stresses, high dispersion and uniform distribution of carbides and intermetallic particles, increasing the density of dislocations as well as through other processes occurring during deformation aging martensite. Start your abstract here...

  13. Molecular mechanisms of AGE/RAGE-mediated fibrosis in the diabetic heart

    PubMed Central

    Zhao, Jia; Randive, Rushil; Stewart, James A

    2014-01-01

    Chronic hyperglycemia is one of the main characteristics of diabetes. Persistent exposure to elevated glucose levels has been recognized as one of the major causal factors of diabetic complications. In pathologies, like type 2 diabetes mellitus (T2DM), mechanical and biochemical stimuli activate profibrotic signaling cascades resulting in myocardial fibrosis and subsequent impaired cardiac performance due to ventricular stiffness. High levels of glucose nonenzymatically react with long-lived proteins, such as collagen, to form advanced glycation end products (AGEs). AGE-modified collagen increase matrix stiffness making it resistant to hydrolytic turnover, resulting in an accumulation of extracellular matrix (ECM) proteins. AGEs account for many of the diabetic cardiovascular complications through their engagement of the receptor for AGE (RAGE). AGE/RAGE activation stimulates the secretion of numerous profibrotic growth factors, promotes increased collagen deposition leading to tissue fibrosis, as well as increased RAGE expression. To date, the AGE/RAGE cascade is not fully understood. In this review, we will discuss one of the major fibrotic signaling pathways, the AGE/RAGE signaling cascade, as well as propose an alternate pathway via Rap1a that may offer insight into cardiovascular ECM remodeling in T2DM. In a series of studies, we demonstrate a role for Rap1a in the regulation of fibrosis and myofibroblast differentiation in isolated diabetic and non-diabetic fibroblasts. While these studies are still in a preliminary stage, inhibiting Rap1a protein expression appears to down-regulate the molecular switch used to activate the ζ isotype of protein kinase C thereby promote AGE/RAGE-mediated fibrosis. PMID:25512788

  14. Aging-related changes in respiratory system mechanics and morphometry in mice.

    PubMed

    Elliott, Jonathan E; Mantilla, Carlos B; Pabelick, Christina M; Roden, Anja C; Sieck, Gary C

    2016-07-01

    Previous work investigating respiratory system mechanics in mice has reported an aging-related increase in compliance and mean linear intercept (Lm). However, these changes were assessed using only a young (2-mo-old) and old (20- and 26-mo-old) group yet were interpreted to reflect a linear evolution across the life span. Therefore, to investigate respiratory system mechanics and lung morphometry across a more complete spectrum of ages, we utilized 2 (100% survival, n = 6)-, 6 (100% survival, n = 12)-, 18 (90% survival, n = 12)-, 24 (75% survival, n = 12)-, and 30 (25% survival, n = 12)-mo-old C57BL/6 mice. We found a nonlinear aging-related decrease in respiratory system resistance and increase in dynamic compliance and hysteresis between 2- and 24-mo-old mice. However, in 30-mo-old mice, respiratory system resistance increased, and dynamic compliance and hysteresis decreased relative to 24-mo-old mice. Respiratory system impedance spectra were measured between 1-20.5 Hz at positive end-expiratory pressures (PEEP) of 1, 3, 5, and 7 cmH2O. Respiratory system resistance and reactance at each level of PEEP were increased and decreased, respectively, only in 2-mo-old animals. No differences in the respiratory system impedance spectra were observed in 6-, 18-, 24-, and 30-mo-old mice. Additionally, lungs were fixed following tracheal instillation of 4% paraformaldehyde at 25 cmH2O and processed for Lm and airway collagen deposition. There was an aging-related increase in Lm consistent with emphysematous-like changes and no evidence of increased airway collagen deposition. Accordingly, we demonstrate nonlinear aging-related changes in lung mechanics and morphometry in C57BL/6 mice.

  15. Quality Saving Mechanisms of Mitochondria during Aging in a Fully Time-Dependent Computational Biophysical Model

    PubMed Central

    Mellem, Daniel; Fischer, Frank; Jaspers, Sören; Wenck, Horst; Rübhausen, Michael

    2016-01-01

    Mitochondria are essential for the energy production of eukaryotic cells. During aging mitochondria run through various processes which change their quality in terms of activity, health and metabolic supply. In recent years, many of these processes such as fission and fusion of mitochondria, mitophagy, mitochondrial biogenesis and energy consumption have been subject of research. Based on numerous experimental insights, it was possible to qualify mitochondrial behaviour in computational simulations. Here, we present a new biophysical model based on the approach of Figge et al. in 2012. We introduce exponential decay and growth laws for each mitochondrial process to derive its time-dependent probability during the aging of cells. All mitochondrial processes of the original model are mathematically and biophysically redefined and additional processes are implemented: Mitochondrial fission and fusion is separated into a metabolic outer-membrane part and a protein-related inner-membrane part, a quality-dependent threshold for mitophagy and mitochondrial biogenesis is introduced and processes for activity-dependent internal oxidative stress as well as mitochondrial repair mechanisms are newly included. Our findings reveal a decrease of mitochondrial quality and a fragmentation of the mitochondrial network during aging. Additionally, the model discloses a quality increasing mechanism due to the interplay of the mitophagy and biogenesis cycle and the fission and fusion cycle of mitochondria. It is revealed that decreased mitochondrial repair can be a quality saving process in aged cells. Furthermore, the model finds strategies to sustain the quality of the mitochondrial network in cells with high production rates of reactive oxygen species due to large energy demands. Hence, the model adds new insights to biophysical mechanisms of mitochondrial aging and provides novel understandings of the interdependency of mitochondrial processes. PMID:26771181

  16. Aging effects on the mechanical properties of alumina-forming austenitic stainless steels

    SciTech Connect

    Bei, Hongbin; Yamamoto, Yukinori; Brady, Michael P; Santella, Michael L

    2010-01-01

    Isothermal aging and tensile evaluation were conducted for recently developed alumina-forming austenitic stainless steels (AFAs). Microstructural observation reveals that NiAl-type B2 and Fe{sub 2}(Mo,Nb)-type Laves phase precipitates form as dominant second phases in the austenitic matrix during aging at 750 C. At room temperature these precipitates increase the strength but decrease the ductility of the AFA alloys. However, when tested at 750 C, the AFA alloys did not show strong precipitation hardening by these phases, moreover, the elongation to fracture was not affected by aging. Fracture surface and cross-sectional microstructure analysis after tensile testing suggests that the difference of mechanical behaviors between room temperature and 750 C results from the ductile-brittle transition of the B2 precipitates. At room temperature, B2 precipitates are strong but brittle, whereas they become weak but ductile above the ductile-brittle transition temperature (DBTT).

  17. Temperature dependent ageing mechanisms in Lithium-ion batteries - A Post-Mortem study

    NASA Astrophysics Data System (ADS)

    Waldmann, Thomas; Wilka, Marcel; Kasper, Michael; Fleischhammer, Meike; Wohlfahrt-Mehrens, Margret

    2014-09-01

    The effects of temperatures in the range of -20 °C to 70 °C on the ageing behaviour of cycled Lithium-ion batteries are investigated quantitatively by electrochemical methods and Post-Mortem analysis. Commercial 18650-type high-power cells with a LixNi1/3Mn1/3Co1/3O2/LiyMn2O4 blend cathode and graphite/carbon anode were used as test system. The cells were cycled at a rate of 1 C until the discharge capacity falls below 80% of the initial capacity. Interestingly, an Arrhenius plot indicates two different ageing mechanisms for the ranges of -20 °C to 25 °C and 25 °C to 70 °C. Below 25 °C, the ageing rates increase with decreasing temperature, while above 25 °C ageing is accelerated with increasing temperature. The aged 18650 cells are inspected via scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), inductively coupled plasma (ICP), measurements of electrode thickness and X-ray diffraction (XRD) after disassembly to learn more about the chemical reasons of the degradation. The effect of different temperatures on the electrode polarizations are evaluated by assembling electrodes in pouch cells with reference electrode as a model system. We find that the dominating ageing mechanism for T < 25 °C is Lithium plating, while for T > 25 °C the cathodes show degeneration and the anodes will be increasingly covered by SEI layers.

  18. Mechanical Properties of Anisotropic Conductive Adhesive Film Under Hygrothermal Aging and Thermal Cycling

    NASA Astrophysics Data System (ADS)

    Gao, Li-Lan; Chen, Xu; Gao, Hong

    2012-07-01

    Mechanical properties of anisotropic conductive adhesive film (ACF) were investigated experimentally under various environmental conditions. The temperature sweep test was conducted to investigate the effects of temperature on dynamical mechanical properties of the ACF. The ACF exhibited transitions to the glass state, viscoelastic state, and rubber state with increasing temperature, and its glass-transition temperature ( T g) was determined to be 149°C. The creep-recovery behaviors of the ACF were investigated, and it was found that the initial strains, instantaneous strains, and creep or recovery rates increased with increasing temperature. No obvious creep phenomenon was observed at low temperatures (≤0°C). The creep strain and creep rates at any time decreased with increasing hygrothermal aging time. The uniaxial tensile behaviors of the ACF were also investigated under hygrothermal aging and thermal cycling. The results show that the Young's modulus and tensile strength of the ACF decrease with increasing hygrothermal aging time; however, they increase at first and then decrease with increasing thermal cycling time. T g decreases slightly for the ACF after hygrothermal aging; however, it increases after thermal cycling.

  19. Molecular and Cellular Mechanisms of Muscle Aging and Sarcopenia and Effects of Electrical Stimulation in Seniors

    PubMed Central

    Barberi, Laura; Scicchitano, Bianca Maria

    2015-01-01

    The prolongation of skeletal muscle strength in aging and neuromuscular disease has been the objective of numerous studies employing a variety of approaches. It is generally accepted that cumulative failure to repair damage related to an overall decrease in anabolic processes is a primary cause of functional impairment in muscle. The functional performance of skeletal muscle tissues declines during post- natal life and it is compromised in different diseases, due to an alteration in muscle fiber composition and an overall decrease in muscle integrity as fibrotic invasions replace functional contractile tissue. Characteristics of skeletal muscle aging and diseases include a conspicuous reduction in myofiber plasticity (due to the progressive loss of muscle mass and in particular of the most powerful fast fibers), alteration in muscle-specific transcriptional mechanisms, and muscle atrophy. An early decrease in protein synthetic rates is followed by a later increase in protein degradation, to affect biochemical, physiological, and morphological parameters of muscle fibers during the aging process. Alterations in regenerative pathways also compromise the functionality of muscle tissues. In this review we will give an overview of the work on molecular and cellular mechanisms of aging and sarcopenia and the effects of electrical stimulation in seniors.. PMID:26913161

  20. Mechanism of Silicon Electrode Aging upon Cycling in Full Lithium-Ion Batteries.

    PubMed

    Delpuech, Nathalie; Dupre, Nicolas; Moreau, Philippe; Bridel, Jean-Sebastian; Gaubicher, Joel; Lestriez, Bernard; Guyomard, Dominique

    2016-04-21

    Understanding the aging mechanism of silicon-based negative electrodes for lithium-ion batteries upon cycling is essential to solve the problem of low coulombic efficiency and capacity fading and further to implement this new high-capacity material in commercial cells. Nevertheless, such studies have so far focused on half cells in which silicon is cycled versus an infinite reservoir of lithium. In the present work, the aging mechanism of silicon-based electrodes is studied upon cycling in a full Li-ion cell configuration with LiCoO2 as the positive electrode. Postmortem analyses of both electrodes clearly indicate that neither one of them contains lithium and that no discernible degradation results from the cycling. The aging mechanism can be explained by the reduction of solvent molecules. Electrons extracted from the positive electrode are responsible for an internal imbalance in the cell, which results in progressive slippage of the electrodes and reduces the compositional range of cyclable lithium ions for both electrodes.

  1. Age related differences in mechanical demands imposed on the lower back by manual material handling tasks.

    PubMed

    Shojaei, Iman; Vazirian, Milad; Croft, Emily; Nussbaum, Maury A; Bazrgari, Babak

    2016-04-11

    The prevalence of low back pain (LBP) increases with age, yet the underlying mechanism(s) responsible for this remains unclear. To explore the role of biomechanical factors, we investigated age-related differences in lower-back biomechanics during sagittally-symmetric simulated manual material handling tasks. For each task, trunk kinematics and mechanical demand on the lower back were examined, from among 60 participants within five equal-sized and gender-balanced age groups spanning from 20 to 70 years old. The tasks involved lowering a 4.5 kg load from an upright standing posture to both knee height and a fixed height and then lifting the load back to the initial upright posture. During these tasks, segmental body kinematics and ground reaction forces were collected using wireless inertial measurement units and a force platform. Overall, older participants completed the tasks with larger pelvic rotation and smaller lumbar flexion. Such adopted trunk kinematics resulted in larger peak shearing demand at the lower back in older vs. younger participants. These results suggest that older individuals may be at a higher risk for developing lower back pain when completing similar manual material handling tasks, consistent with epidemiological evidence for higher risks of occupational low back pain among this cohort.

  2. Aging and loading rate effects on the mechanical behavior of equine bone

    NASA Astrophysics Data System (ADS)

    Kulin, Robb M.; Jiang, Fengchun; Vecchio, Kenneth S.

    2008-06-01

    Whether due to a sporting accident, high-speed impact, fall, or other catastrophic event, the majority of clinical bone fractures occur under dynamic loading conditions. However, although extensive research has been performed on the quasi-static fracture and mechanical behavior of bone to date, few high-quality studies on the fracture behavior of bone at high strain rates have been performed. Therefore, many questions remain regarding the material behavior, including not only the loading-rate-dependent response of bone, but also how this response varies with age. In this study, tests were performed on equine femoral bone taken post-mortem from donors 6 months to 28 years of age. Quasi-static and dynamic tests were performed to determine the fracture toughness and compressive mechanical behavior as a function of age at varying loading rates. Fracture paths were then analyzed using scanning confocal and scanning-electron microscopy techniques to assess the role of various microstructural features on toughening mechanisms.

  3. Effect of aging temperature on phase decomposition and mechanical properties in cast duplex stainless steels

    DOE PAGES

    Mburu, Sarah; Kolli, R. Prakash; Perea, Daniel E.; ...

    2017-03-06

    The microstructure and mechanical properties in unaged and thermally aged (at 280 °C, 320 °C, 360 °C, and 400 °C to 4300 h) CF–3 and CF–8 cast duplex stainless steels (CDSS) are investigated. The unaged CF–8 steel has Cr-rich M23C6 carbides located at the δ–ferrite/γ–austenite heterophase interfaces that were not observed in the CF–3 steel and this corresponds to a difference in mechanical properties. Both unaged steels exhibit incipient spinodal decomposition into Fe-rich α–domains and Cr-rich α’–domains. During aging, spinodal decomposition progresses and the mean wavelength (MW) and mean amplitude (MA) of the compositional fluctuations increase as a function ofmore » aging temperature. Additionally, G–phase precipitates form between the spinodal decomposition domains in CF–3 at 360 °C and 400 °C and in CF–8 at 400 °C. Finally, the microstructural evolution is correlated to changes in mechanical properties.« less

  4. Lamb Wave Stiffness Characterization of Composites Undergoing Thermal-Mechanical Aging

    NASA Technical Reports Server (NTRS)

    Seale, Michael D.; Madaras, Eric I.

    2004-01-01

    The introduction of new, advanced composite materials into aviation systems requires a thorough understanding of the long term effects of combined thermal and mechanical loading upon those materials. Analytical methods investigating the effects of intense thermal heating combined with mechanical loading have been investigated. The damage mechanisms and fatigue lives were dependent on test parameters as well as stress levels. Castelli, et al. identified matrix dominated failure modes for out-of-phase cycling and fiber dominated damage modes for in-phase cycling. In recent years, ultrasonic methods have been developed that can measure the mechanical stiffness of composites. To help evaluate the effect of aging, a suitably designed Lamb wave measurement system is being used to obtain bending and out-of-plane stiffness coefficients of composite laminates undergoing thermal-mechanical loading. The system works by exciting an antisymmetric Lamb wave and calculating the velocity at each frequency from the known transducer separation and the measured time-of-flight. The same peak in the waveforms received at various distances is used to measure the time difference between the signals. The velocity measurements are accurate and repeatable to within 1% resulting in reconstructed stiffness values repeatable to within 4%. Given the material density and plate thickness, the bending and out-of-plane shear stiffnesses are calculated from a reconstruction of the dispersion curve. A mechanical scanner is used to move the sensors over the surface to map the time-of-flight, velocity, or stiffnesses of the entire specimen. Access to only one side of the material is required and no immersion or couplants are required because the sensors are dry coupled to the surface of the plate. In this study, the elastic stiffnesses D(sub 11), D(sub 22), A(sub 44), and A(sub 55) as well as time-of-flight measurements for composite samples that have undergone combined thermal and mechanical aging for

  5. Glycation-altered proteolysis as a pathobiologic mechanism that links dietary glycemic index, aging, and age-related disease in non diabetics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Epidemiologic studies indicate that the risks for major age-related debilities including coronary heart disease, diabetes, and age-related macular degeneration (AMD) are diminished in people who consume lower glycemic index (GI) diets, but lack of a unifying physiobiochemical mechanism that explains...

  6. Precipitation and mechanical properties of Nb-modified ferritic stainless steel during isothermal aging

    SciTech Connect

    Yan Haitao Bi Hongyun; Li Xin; Xu Zhou

    2009-03-15

    The influence of isothermal aging on precipitation behavior and mechanical properties of Nb-modified ferritic stainless steel was investigated using Thermo-calc software, scanning electron microscopy and transmission electron microscopy. It was observed that TiN, NbC and Fe{sub 2}Nb formed in the investigated steel and the experimental results agreed well with the results calculated by Thermo-calc software. During isothermal aging at 800 deg. C, the coarsening rate of Fe{sub 2}Nb is greater than that of NbC, and the calculated average sizes of NbC and Fe{sub 2}Nb of the aged specimen agreed with the experimental results. In addition, the tensile strength and micro-hardness of the ferritic stainless steel increased with increased aging time from 24 h to 48 h. But aging at 800 deg. C for 96 h caused the coarsening of the precipitation, which led to a decrease of tensile strength and micro-hardness.

  7. Polyphenol Stilbenes: Molecular Mechanisms of Defence against Oxidative Stress and Aging-Related Diseases

    PubMed Central

    Reinisalo, Mika; Kårlund, Anna; Koskela, Ali; Kaarniranta, Kai; Karjalainen, Reijo O.

    2015-01-01

    Numerous studies have highlighted the key roles of oxidative stress and inflammation in aging-related diseases such as obesity, type 2 diabetes, age-related macular degeneration (AMD), and Alzheimer's disease (AD). In aging cells, the natural antioxidant capacity decreases and the overall efficiency of reparative systems against cell damage becomes impaired. There is convincing data that stilbene compounds, a diverse group of natural defence phenolics, abundant in grapes, berries, and conifer bark waste, may confer a protective effect against aging-related diseases. This review highlights recent data helping to clarify the molecular mechanisms involved in the stilbene-mediated protection against oxidative stress. The impact of stilbenes on the nuclear factor-erythroid-2-related factor-2 (Nrf2) mediated cellular defence against oxidative stress as well as the potential roles of SQSTM1/p62 protein in Nrf2/Keap1 signaling and autophagy will be summarized. The therapeutic potential of stilbene compounds against the most common aging-related diseases is discussed. PMID:26180583

  8. Dissecting the molecular mechanisms that impair stress granule formation in aging cells.

    PubMed

    Moujaber, Ossama; Mahboubi, Hicham; Kodiha, Mohamed; Bouttier, Manuella; Bednarz, Klaudia; Bakshi, Ragini; White, John; Larose, Louise; Colmegna, Inés; Stochaj, Ursula

    2017-03-01

    Aging affects numerous aspects of cell biology, but the senescence-associated changes in the stress response are only beginning to emerge. To obtain mechanistic insights into these events, we examined the formation of canonical and non-canonical stress granules (SGs) in the cytoplasm. SG generation is a key event after exposure to physiological or environmental stressors. It requires the SG-nucleating proteins G3BP1 and TIA-1/TIAR and stress-related signaling events. To analyze SG formation, we used two independent models of somatic cell aging. In both model systems, cellular senescence impaired the assembly of two SG classes: (i) it compromised the formation of canonical SGs, and (ii) skewed the production of non-canonical SGs. We dissected the mechanisms underlying these senescence-dependent changes in granule biogenesis and identified several specific targets that were modulated by aging. Thus, we demonstrate a depletion of G3BP1 and TIA-1/TIAR in senescent cells and show that the loss of G3BP1 contributed to impaired SG formation. We further reveal that aging reduced Sp1 levels; this transcription factor regulated G3BP1 and TIA-1/TIAR abundance. The assembly of canonical SGs relies on the phosphorylation of translation initiation factor eIF2α. We show that senescence can cause eIF2α hyperphosphorylation. CReP is a subunit of protein phosphatase 1 and critical to reverse the stress-dependent phosphorylation of eIF2α. We demonstrate that the loss of CReP correlated with the aging-related hyperphosphorylation of eIF2α. Together, we have identified significant changes in the stress response of aging cells and provide mechanistic insights. Based on our work, we propose that the decline in SG formation can provide a new biomarker to evaluate cellular aging.

  9. Strength and Aerobic Exercises Improve Spatial Memory in Aging Rats Through Stimulating Distinct Neuroplasticity Mechanisms.

    PubMed

    Vilela, Thais Ceresér; Muller, Alexandre Pastoris; Damiani, Adriani Paganini; Macan, Tamires Pavei; da Silva, Sabrina; Canteiro, Paula Bortoluzzi; de Sena Casagrande, Alisson; Pedroso, Giulia Dos Santos; Nesi, Renata Tiscoski; de Andrade, Vanessa Moraes; de Pinho, Ricardo Aurino

    2016-11-22

    Aging is associated with impaired cognition and memory and increased susceptibility to neurodegenerative disorders. Physical exercise is neuroprotective; however, the major evidence of this effect involves studies of only aerobic training in young animals. The benefits of other exercise protocols such as strength training in aged animals remains unknown. Here, we investigated the effect of aerobic and strength training on spatial memory and hippocampal plasticity in aging rats. Aging Wistar rats performed aerobic or strength training for 50 min 3 to 4 days/week for 8 weeks. Spatial memory and neurotrophic and glutamatergic signaling in the hippocampus of aged rats were evaluated after aerobic or strength training. Both aerobic and strength training improved cognition during the performance of a spatial memory task. Remarkably, the improvement in spatial memory was accompanied by an increase in synaptic plasticity proteins within the hippocampus after exercise training, with some differences in the intracellular functions of those proteins between the two exercise protocols. Moreover, neurotrophic signaling (CREB, BDNF, and the P75(NTR) receptor) increased after training for both exercise protocols, and aerobic exercise specifically increased glutamatergic proteins (NMDA receptor and PSD-95). We also observed a decrease in DNA damage after aerobic training. In contrast, strength training increased levels of PKCα and the proinflammatory factors TNF-α and IL-1β. Overall, our results show that both aerobic and strength training improved spatial memory in aging rats through inducing distinct molecular mechanisms of neuroplasticity. Our findings extend the idea that exercise protocols can be used to improve cognition during aging.

  10. Aging mechanisms for steel components of high-level waste storage tanks

    SciTech Connect

    Weeks, J.; Bandyopadhyay, K.; Bush, S.; Kassir, M.; Mather, B.; Shewmon, P.; Streicher, M.; Thompson, B.; van Rooyen, D.

    1995-05-01

    High level storage tanks in service at the present time were fabricated from either carbon steel or low-carbon stainless steel, in each case surrounded by a concrete vault. A variety of potential degradation mechanisms may affect these steel tanks, including corrosion, stress-corrosion cracking, fatigue, radiation, erosion, and hydrogen embrittlement. Historically, some of the non-stress-relieved carbon steel tanks have leaked; in the only failure analysis performed to date, stress corrosion cracking in the heat-affected zone (HAZ) of the weld was identified as the cause. Potentially significant aging mechanisms include general corrosion, pitting and/or crevice corrosion stress-corrosion cracking, microbiologically-induced corrosion, concentration cell attack, and corrosion of external tank surfaces by in-leakage of ground water. Aging mechanisms which are deemed non-significant include thermal and radiation embrittlement, creep and stress relaxation, fatigue, erosion and erosion/corrosion wear, and hydrogen embrittlement. Justification for the potential significance or non-significance for each mechanism is provided, based on the current understanding of these processes and the environments to which the tanks are exposed.

  11. Restricting the ageing degradation of the mechanical properties of gamma irradiated UHMWPE using MWCNTs.

    PubMed

    Rama Sreekanth, P S; Kanagaraj, S

    2013-05-01

    Property degradation of the medical grade polymers after gamma irradiation is the primary concern that limits longevity of them. Though the conventional antioxidant material helps to reduce the degradation but it limits the degree of crosslinking of the polymer. The objective of the present work is to study the influence of multi walled carbon nanotubes (MWCNTs) on restricting the degradation of mechanical properties of medical grade ultra high molecular weight polyethylene (UHMWPE) after its irradiation. UHMWPE was reinforced by chemically treated MWCNTs at different concentrations such as 0.5, 1.0, 1.5, and 2.0 wt%. The test samples were then subjected to Co⁶⁰ gamma irradiation with an integral dose of 25, 50, 75 and 100 kGy in air. The mechanical properties of irradiated samples were evaluated within 10 days, 60 and 120 days after irradiation. It was observed that the mechanical properties of virgin UHMWPE and nanocomposites were enhanced immediately after irradiation but they were found to be reduced at later stages. It was also observed that the presence of MWCNTs limited the ageing degradation of the mechanical properties of UHMWPE. Raman spectroscopic and TEM studies confirmed the formation of irradiation induced defects on the MWCNTs. Electron spin resonance studies showed that the relative radical intensity of virgin UHWMPE was reduced significantly with an increase of MWCNTs concentration confirming the radical scavenging ability of them. It is concluded that MWCNTs restricted the ageing degradation of irradiated UHMWPE.

  12. Mechanism of homologous recombination and implications for aging-related deletions in mitochondrial DNA.

    PubMed

    Chen, Xin Jie

    2013-09-01

    Homologous recombination is a universal process, conserved from bacteriophage to human, which is important for the repair of double-strand DNA breaks. Recombination in mitochondrial DNA (mtDNA) was documented more than 4 decades ago, but the underlying molecular mechanism has remained elusive. Recent studies have revealed the presence of a Rad52-type recombination system of bacteriophage origin in mitochondria, which operates by a single-strand annealing mechanism independent of the canonical RecA/Rad51-type recombinases. Increasing evidence supports the notion that, like in bacteriophages, mtDNA inheritance is a coordinated interplay between recombination, repair, and replication. These findings could have profound implications for understanding the mechanism of mtDNA inheritance and the generation of mtDNA deletions in aging cells.

  13. Aging mechanisms for concrete components of High-Level Waste storage tanks

    SciTech Connect

    Kassir, M.; Bandyopadhyay, K.; Bush, S.; Mather, B.; Shewmon, P.; Streicher, M.; Thompson, B.; van Rooyen, D.; Weeks, J.

    1995-05-01

    The age-related degradation mechanisms which affect the concrete and the reinforcing steel in the high-level waste (HLW) storage tanks art evaluated with respect to their potential significance to the continued performance of the concrete, and am classified into non-significant and potentially significant. The identified potentially significant degradation mechanisms include the effects of elevated temperature, freezing and thawing, leaching of calcium hydroxide, aggressive chemical attack, and corrosion of the reinforcing steel. To the extent that available knowledge permits, these mechanisms are generically evaluated and quantified so that site-specific plans may be developed to verify whether significant degradation has occurred in the concrete, and, if so, to formulate mitigating measures to avoid further deterioration and possibly repair the degradation or pursue other management options.

  14. [Aging effect on mechanical properties in fluid resin. (Part 1). Affection of residual monomer (author's transl)].

    PubMed

    Horiuchi, A

    1979-07-01

    Aging effect on the mechanical properties in fluid resins was pointed out, but little was studied on this point. Relationship between amount of residual monomer in the samples prepared by fluid resin and the mechanical properties, brinell hardness, tensile strength, were studied. Test pieces just as polymerized in the size were used. Weights of specimens kept at three different circumstances, in the air at 20 degrees C, in a water bath at 37 degrees C and in a desiccator at 11 mmHg and 40 degrees C, was checked at the prescribed time to clarify the amount of residual monomer and the mechanical properties were measured at the same time. Amount of weight loss, due to evaporation of MMA, must improve the mechanical properties. The improvement by postpolymerization could be neglected. Rate of the weight loss suggests that residual monomer must mainly be at the surface. Molecular weight of PMMA, 86.4 X 10(4) did not have any effect on the mechanical properties and on the evaporation rate of monomers from polymerized specimens. To improve the mechanical properties of fluid resin must be to decrease residual monomer as much as possible in the fluid resin especially at the surface area.

  15. Identification of autophagy as a longevity-assurance mechanism in the aging model Podospora anserina

    PubMed Central

    Knuppertz, Laura; Hamann, Andrea; Pampaloni, Francesco; Stelzer, Ernst; Osiewacz, Heinz D

    2014-01-01

    The filamentous ascomycete Podospora anserina is a well-established aging model in which a variety of different pathways, including those involved in the control of respiration, ROS generation and scavenging, DNA maintenance, proteostasis, mitochondrial dynamics, and programmed cell death have previously been demonstrated to affect aging and life span. Here we address a potential role of autophagy. We provide data demonstrating high basal autophagy levels even in strains cultivated under noninduced conditions. By monitoring an N-terminal fusion of EGFP to the fungal LC3 homolog PaATG8 over the lifetime of the fungus on medium with and without nitrogen supplementation, respectively, we identified a significant increase of GFP puncta in older and in nitrogen-starved cultures suggesting an induction of autophagy during aging. This conclusion is supported by the demonstration of an age-related and autophagy-dependent degradation of a PaSOD1-GFP reporter protein. The deletion of Paatg1, which leads to the lack of the PaATG1 serine/threonine kinase active in early stages of autophagy induction, impairs ascospore germination and development and shortens life span. Under nitrogen-depleted conditions, life span of the wild type is increased almost 4-fold. In contrast, this effect is annihilated in the Paatg1 deletion strain, suggesting that the ability to induce autophagy is beneficial for this fungus. Collectively, our data identify autophagy as a longevity-assurance mechanism in P. anserina and as another surveillance pathway in the complex network of pathways affecting aging and development. These findings provide perspectives for the elucidation of the mechanisms involved in the regulation of individual pathways and their interactions. PMID:24584154

  16. Quantitative analysis of mechanisms that govern red blood cell age structure and dynamics during anaemia.

    PubMed

    Savill, Nicholas J; Chadwick, William; Reece, Sarah E

    2009-06-01

    Mathematical modelling has proven an important tool in elucidating and quantifying mechanisms that govern the age structure and population dynamics of red blood cells (RBCs). Here we synthesise ideas from previous experimental data and the mathematical modelling literature with new data in order to test hypotheses and generate new predictions about these mechanisms. The result is a set of competing hypotheses about three intrinsic mechanisms: the feedback from circulating RBC concentration to production rate of immature RBCs (reticulocytes) in bone marrow, the release of reticulocytes from bone marrow into the circulation, and their subsequent ageing and clearance. In addition we examine two mechanisms specific to our experimental system: the effect of phenylhydrazine (PHZ) and blood sampling on RBC dynamics. We performed a set of experiments to quantify the dynamics of reticulocyte proportion, RBC concentration, and erythropoietin concentration in PHZ-induced anaemic mice. By quantifying experimental error we are able to fit and assess each hypothesis against our data and recover parameter estimates using Markov chain Monte Carlo based Bayesian inference. We find that, under normal conditions, about 3% of reticulocytes are released early from bone marrow and upon maturation all cells are released immediately. In the circulation, RBCs undergo random clearance but have a maximum lifespan of about 50 days. Under anaemic conditions reticulocyte production rate is linearly correlated with the difference between normal and anaemic RBC concentrations, and their release rate is exponentially correlated with the same. PHZ appears to age rather than kill RBCs, and younger RBCs are affected more than older RBCs. Blood sampling caused short aperiodic spikes in the proportion of reticulocytes which appear to have a different developmental pathway than normal reticulocytes. We also provide evidence of large diurnal oscillations in serum erythropoietin levels during anaemia.

  17. Modeling the Mechanical Consequences of Age-Related Trabecular Bone Loss by XFEM Simulation

    PubMed Central

    Fan, Ruoxun; Zhang, Xianbin; Liu, Jun; Jia, Zhengbin; Zhu, Dong

    2016-01-01

    The elderly are more likely to suffer from fracture because of age-related trabecular bone loss. Different bone loss locations and patterns have different effects on bone mechanical properties. Extended finite element method (XFEM) can simulate fracture process and was suited to investigate the effects of bone loss on trabecular bone. Age-related bone loss is indicated by trabecular thinning and loss and may occur at low-strain locations or other random sites. Accordingly, several ideal normal and aged trabecular bone models were created based on different bone loss locations and patterns; then, fracture processes from crack initiation to complete failure of these models were observed by XFEM; finally, the effects of different locations and patterns on trabecular bone were compared. Results indicated that bone loss occurring at low-strain locations was more detrimental to trabecular bone than that occurring at other random sites; meanwhile, the decrease in bone strength caused by trabecular loss was higher than that caused by trabecular thinning, and the effects of vertical trabecular loss on mechanical properties were more severe than horizontal trabecular loss. This study provided a numerical method to simulate trabecular bone fracture and distinguished different effects of the possible occurrence of bone loss locations and patterns on trabecular bone. PMID:27403206

  18. Molecular mechanisms involved in the hormonal prevention of aging in the rat.

    PubMed

    Tresguerres, Jesús A F; Kireev, Roman; Tresguerres, Ana F; Borras, Consuelo; Vara, Elena; Ariznavarreta, Carmen

    2008-02-01

    Previous data from our group have provided support for the role of GH, melatonin and estrogens in the prevention of aging of several physiological parameters from bone, liver metabolism, vascular activity, the central nervous system (CNS), the immune system and the skin. In the present work data on the molecular mechanisms involved are presented. A total of 140 male and female rats have been submitted to different treatments over 10 weeks, between 22 and 24 months of age. Males have been treated with GH and melatonin. Females were divided in two groups: intact and castrated at 12 months of age. The first group was treated with GH and melatonin and the second with the two latter compounds and additionally with estradiol and Phytosoya. Aging was associated with a reduction in the number of neurons of the hylus of the dentate gyrus of the hippocampus and with a reduction of neurogenesis. GH treatment increased the number of neurons but did not increase neurogenesis thus suggesting a reduction of apoptosis. This was supported by the reduction in nucleosomes and the increase in Bcl2 observed in cerebral homogenates together with an increase in sirtuin2 and a reduction of caspases 9 and 3. Melatonin, estrogen and Phytosoya treatments increased neurogenesis but did not enhance the total number of neurons. Aging induced a significant increase in mitochondrial nitric oxide in the hepatocytes, together with a reduction in the mitochondrial fraction content in cytochrome C and an increase of this compound in the cytosolic fraction. Reductions of glutathione peroxidase and glutathione S-transferase were also detected, thus indicating oxidative stress and possibly apoptosis. Treatment for 2.5 months of old rats with GH and melatonin were able to significantly and favourably affect age-induced deteriorations, thus reducing oxidative damage. Keratinocytes obtained from old rats in primary culture showed an increase in lipoperoxides, caspases 8 and 3 as well as a reduction in Bcl2

  19. [Differentiation of radial glia cells into astrocytes is a possible ageing mechanism in mammals].

    PubMed

    Boĭko, A G

    2007-01-01

    Several obscure facts of gerontology are briefly reviewed. A attempt is made to shape new notions of the phenomenon based on the astrocyte hypothesis of ageing in mammals. This hypothesis interprets mammal ageing as a genetic disease with fatal outcome. The disease is caused by single character acquired by the theromorph lineage of the vertebrates in the course of evolution: the transformation of radial glia cells (RGC) into star-shaped astrocytes during the postnatal development, i.e. the disappearance of the fetal radial ways of nerve cell migration from proliferative zones to the sites of their ultimate localization in the brain of adult individuals. This process is the cause for the mammal brain being postmitotic. The disappearance of RGC induces a cascade of system processes termed age-dependent mechanism of self-destruction of mammals (AMSM). The disappearance of RGC inhibits the replacement of the nerve cells that have exhausted their living resources. Nerve cells are rigidly specialized and have restricted lifetime and ability of reparation. After some period, the level of homeostasis in nerve cells starts changing steadily for the worse due to irreversible pathological changes in the cells (especially in the neurosecretory cells). This brings damage to life-sypport systems of the mammal organism thus causing its death. The species-specific maximum life span is thus determined by the rate of metabolism in the organism. AMSM probably displays a general evolutionary principle: outer factors causing death (in non-ageing organisms) are replaced by inner factors.

  20. Calcium dysregulation and neuroinflammation: Discrete and integrated mechanisms for age-related synaptic dysfunction

    PubMed Central

    Sama, Diana M.; Norris, Christopher M.

    2013-01-01

    Some of the best biomarkers of age-related cognitive decline are closely linked to synaptic function and plasticity. This review highlights several age-related synaptic alterations as they relate to Ca2+ dyshomeostasis, through elevation of intracellular Ca2+, and neuroinflammation, through production of pro-inflammatory cytokines including interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α). Though distinct in many ways, Ca2+ and neuroinflammatory signaling mechanisms exhibit extensive cross-talk and bidirectional interactions. For instance, cytokine production in glial cells is strongly dependent on the Ca2+ dependent protein phosphatase calcineurin, which shows elevated activity in animal models of aging and disease. In turn, pro-inflammatory cytokines, such as TNF, can augment the expression/activity of L-type voltage sensitive Ca2+ channels in neurons, leading to Ca2+ dysregulation, hyperactive calcineurin activity, and synaptic depression. Thus, in addition to discussing unique contributions of Ca2+ dyshomeostasis and neuroinflammation, this review emphasizes how these processes interact to hasten age-related synaptic changes. PMID:23751484

  1. Age-Related Neurodegeneration Prevention Through mTOR Inhibition: Potential Mechanisms and Remaining Questions

    PubMed Central

    Jahrling, Jordan B.; Laberge, Remi-Martin

    2016-01-01

    With the global aging population, Alzheimer's disease, Parkinson's disease and mild cognition impairment are increasing in prevalence. The success of rapamycin as an agent to extend lifespan in various organisms, including mice, brings hope that chronic mTOR inhibition could also refrain age-related neurodegeneration. Here we review the evidence suggesting that mTOR inhibition - mainly with rapamycin - is a valid intervention to delay age-related neurodegeneration. We discuss the potential mechanisms by which rapamycin may facilitate neurodegeneration prevention or restoration of cognitive function. We also discuss the known side effects of rapamycin and provide evidence to alleviate exaggerated concerns regarding its wider clinical use. We explore the small molecule alternatives to rapamycin and propose future directions for their development, mainly by exploring the possibility of targeting the downstream effectors of mTOR: S6K1 and especially S6K2. Finally, we discuss the strengths and weaknesses of the models used to determine intervention efficacy for neurodegeneration. We address the difficulties of interpreting data using the common way of investigating the efficacy of interventions to delay/prevent neurodegeneration by observing animal behavior while these animals are under treatment. We propose an experimental design that should isolate the variable of aging in the experimental design and resolve the ambiguity present in recent literature. PMID:26059360

  2. Physical activity and telomere length: Impact of aging and potential mechanisms of action.

    PubMed

    Arsenis, Nicole C; You, Tongjian; Ogawa, Elisa F; Tinsley, Grant M; Zuo, Li

    2017-03-30

    Telomeres protect the integrity of information-carrying DNA by serving as caps on the terminal portions of chromosomes. Telomere length decreases with aging, and this contributes to cell senescence. Recent evidence supports that telomere length of leukocytes and skeletal muscle cells may be positively associated with healthy living and inversely correlated with the risk of several age-related diseases, including cancer, cardiovascular disease, obesity, diabetes, chronic pain, and stress. In observational studies, higher levels of physical activity or exercise are related to longer telomere lengths in various populations, and athletes tend to have longer telomere lengths than non-athletes. This relationship is particularly evident in older individuals, suggesting a role of physical activity in combating the typical age-induced decrements in telomere length. To date, a small number of exercise interventions have been executed to examine the potential influence of chronic exercise on telomere length, but these studies have not fully established such relationship. Several potential mechanisms through which physical activity or exercise could affect telomere length are discussed, including changes in telomerase activity, oxidative stress, inflammation, and decreased skeletal muscle satellite cell content. Future research is needed to mechanistically examine the effects of various modalities of exercise on telomere length in middle-aged and older adults, as well as in specific clinical populations.

  3. Mechanisms of Age-Related Decline in Memory Search Across the Adult Life Span

    PubMed Central

    Hills, Thomas T.; Mata, Rui; Wilke, Andreas; Samanez-Larkin, Gregory R.

    2013-01-01

    Three alternative mechanisms for age-related decline in memory search have been proposed, which result from either reduced processing speed (global slowing hypothesis), overpersistence on categories (cluster-switching hypothesis), or the inability to maintain focus on local cues related to a decline in working memory (cue-maintenance hypothesis). We investigated these 3 hypotheses by formally modeling the semantic recall patterns of 185 adults between 27 to 99 years of age in the animal fluency task (Thurstone, 1938). The results indicate that people switch between global frequency-based retrieval cues and local item-based retrieval cues to navigate their semantic memory. Contrary to the global slowing hypothesis that predicts no qualitative differences in dynamic search processes and the cluster-switching hypothesis that predicts reduced switching between retrieval cues, the results indicate that as people age, they tend to switch more often between local and global cues per item recalled, supporting the cue-maintenance hypothesis. Additional support for the cue-maintenance hypothesis is provided by a negative correlation between switching and digit span scores and between switching and total items recalled, which suggests that cognitive control may be involved in cue maintenance and the effective search of memory. Overall, the results are consistent with age-related decline in memory search being a consequence of reduced cognitive control, consistent with models suggesting that working memory is related to goal perseveration and the ability to inhibit distracting information. PMID:23586941

  4. Changes in Structural-Mechanical Properties and Degradability of Collagen during Aging-associated Modifications*

    PubMed Central

    Panwar, Preety; Lamour, Guillaume; Mackenzie, Neil C. W.; Yang, Heejae; Ko, Frank; Li, Hongbin; Brömme, Dieter

    2015-01-01

    During aging, changes occur in the collagen network that contribute to various pathological phenotypes in the skeletal, vascular, and pulmonary systems. The aim of this study was to investigate the consequences of age-related modifications on the mechanical stability and in vitro proteolytic degradation of type I collagen. Analyzing mouse tail and bovine bone collagen, we found that collagen at both fibril and fiber levels varies in rigidity and Young's modulus due to different physiological changes, which correlate with changes in cathepsin K (CatK)-mediated degradation. A decreased susceptibility to CatK-mediated hydrolysis of fibrillar collagen was observed following mineralization and advanced glycation end product-associated modification. However, aging of bone increased CatK-mediated osteoclastic resorption by ∼27%, and negligible resorption was observed when osteoclasts were cultured on mineral-deficient bone. We observed significant differences in the excavations generated by osteoclasts and C-terminal telopeptide release during bone resorption under distinct conditions. Our data indicate that modification of collagen compromises its biomechanical integrity and affects CatK-mediated degradation both in bone and tissue, thus contributing to our understanding of extracellular matrix aging. PMID:26224630

  5. Circuit mechanisms encoding odors and driving aging-associated behavioral declines in Caenorhabditis elegans

    PubMed Central

    Leinwand, Sarah G; Yang, Claire J; Bazopoulou, Daphne; Chronis, Nikos; Srinivasan, Jagan; Chalasani, Sreekanth H

    2015-01-01

    Chemosensory neurons extract information about chemical cues from the environment. How is the activity in these sensory neurons transformed into behavior? Using Caenorhabditis elegans, we map a novel sensory neuron circuit motif that encodes odor concentration. Primary neurons, AWCON and AWA, directly detect the food odor benzaldehyde (BZ) and release insulin-like peptides and acetylcholine, respectively, which are required for odor-evoked responses in secondary neurons, ASEL and AWB. Consistently, both primary and secondary neurons are required for BZ attraction. Unexpectedly, this combinatorial code is altered in aged animals: odor-evoked activity in secondary, but not primary, olfactory neurons is reduced. Moreover, experimental manipulations increasing neurotransmission from primary neurons rescues aging-associated neuronal deficits. Finally, we correlate the odor responsiveness of aged animals with their lifespan. Together, these results show how odors are encoded by primary and secondary neurons and suggest reduced neurotransmission as a novel mechanism driving aging-associated sensory neural activity and behavioral declines. DOI: http://dx.doi.org/10.7554/eLife.10181.001 PMID:26394000

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

    PubMed

    Epel, Elissa S; Lithgow, Gordon J

    2014-06-01

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

  7. Similar verbal memory impairments in schizophrenia and healthy aging. Implications for understanding of neural mechanisms.

    PubMed

    Silver, Henry; Bilker, Warren B

    2015-03-30

    Memory is impaired in schizophrenia patients but it is not clear whether this is specific to the illness and whether different types of memory (verbal and nonverbal) or memories in different cognitive domains (executive, object recognition) are similarly affected. To study relationships between memory impairments and schizophrenia we compared memory functions in 77 schizophrenia patients, 58 elderly healthy individuals and 41 young healthy individuals. Tests included verbal associative and logical memory and memory in executive and object recognition domains. We compared relationships of memory functions to each other and to other cognitive functions including psychomotor speed and verbal and spatial working memory. Compared to the young healthy group, schizophrenia patients and elderly healthy individuals showed similar severe impairment in logical memory and in the ability to learn new associations (NAL), and similar but less severe impairment in spatial working memory and executive and object memory. Verbal working memory was significantly more impaired in schizophrenia patients than in the healthy elderly. Verbal episodic memory impairment in schizophrenia may share common mechanisms with similar impairment in healthy aging. Impairment in verbal working memory in contrast may reflect mechanisms specific to schizophrenia. Study of verbal explicit memory impairment tapped by the NAL index may advance understanding of abnormal hippocampus dependent mechanisms common to schizophrenia and aging.

  8. Secrets of the lac operon. Glucose hysteresis as a mechanism in dietary restriction, aging and disease.

    PubMed

    Mobbs, Charles V; Mastaitis, Jason W; Zhang, Minhua; Isoda, Fumiko; Cheng, Hui; Yen, Kelvin

    2007-01-01

    Elevated blood glucose associated with diabetes produces progressive and apparently irreversible damage to many cell types. Conversely, reduction of glucose extends life span in yeast, and dietary restriction reduces blood glucose. Therefore it has been hypothesized that cumulative toxic effects of glucose drive at least some aspects of the aging process and, conversely, that protective effects of dietary restriction are mediated by a reduction in exposure to glucose. The mechanisms mediating cumulative toxic effects of glucose are suggested by two general principles of metabolic processes, illustrated by the lac operon but also observed with glucose-induced gene expression. First, metabolites induce the machinery of their own metabolism. Second, induction of gene expression by metabolites can entail a form of molecular memory called hysteresis. When applied to glucose-regulated gene expression, these two principles suggest a mechanism whereby repetitive exposure to postprandial excursions of glucose leads to an age-related increase in glycolytic capacity (and reduction in beta-oxidation of free fatty acids), which in turn leads to an increased generation of oxidative damage and a decreased capacity to respond to oxidative damage, independent of metabolic rate. According to this mechanism, dietary restriction increases life span and reduces pathology by reducing exposure to glucose and therefore delaying the development of glucose-induced glycolytic capacity.

  9. Capacity for sliding between tendon fascicles decreases with ageing in injury prone equine tendons: a possible mechanism for age-related tendinopathy?

    PubMed

    Thorpe, C T; Udeze, C P; Birch, H L; Clegg, P D; Screen, H Rc

    2013-01-08

    Age-related tendinopathy is common in both humans and horses; the initiation and progression of which is similar between species. The majority of tendon injuries occur to high-strain energy storing tendons, such as the human Achilles tendon and equine superficial digital flexor (SDFT). By contrast, the low-strain positional human anterior tibialis tendon and equine common digital extensor (CDET) are rarely injured. It has previously been established that greater extension occurs at the fascicular interface in the SDFT than in the CDET; this may facilitate the large strains experienced during locomotion in the SDFT without damage occurring to the fascicles. This study investigated the alterations in whole tendon, fascicle and interfascicular mechanical properties in the SDFT and CDET with increasing age. It was hypothesised that the amount of sliding at the fascicular interface in the SDFT would decrease with increasing horse age, whereas the properties of the interface in the CDET would remain unchanged with ageing. Data support the hypothesis; there were no alterations in the mechanical properties of the whole SDFT or its constituent fascicles with increasing age. However, there was significantly less sliding at the fascicular interface at physiological loads in samples from aged tendons. There was no relationship between fascicle sliding and age in the CDET. The increase in stiffness of the interfascicular matrix in aged SDFT may result in the fascicles being loaded at an earlier point in the stress strain curve, increasing the risk of damage. This may predispose aged tendons to tendinopathy.

  10. The Formation of Calcified Nanospherites during Micropetrosis Represents a Unique Mineralization Mechanism in Aged Human Bone.

    PubMed

    Milovanovic, Petar; Zimmermann, Elizabeth A; Vom Scheidt, Annika; Hoffmann, Björn; Sarau, George; Yorgan, Timur; Schweizer, Michaela; Amling, Michael; Christiansen, Silke; Busse, Björn

    2017-01-01

    Osteocytes-the central regulators of bone remodeling-are enclosed in a network of microcavities (lacunae) and nanocanals (canaliculi) pervading the mineralized bone. In a hitherto obscure process related to aging and disease, local plugs in the lacuno-canalicular network disrupt cellular communication and impede bone homeostasis. By utilizing a suite of high-resolution imaging and physics-based techniques, it is shown here that the local plugs develop by accumulation and fusion of calcified nanospherites in lacunae and canaliculi (micropetrosis). Two distinctive nanospherites phenotypes are found to originate from different osteocytic elements. A substantial deviation in the spherites' composition in comparison to mineralized bone further suggests a mineralization process unlike regular bone mineralization. Clearly, mineralization of osteocyte lacunae qualifies as a strong marker for degrading bone material quality in skeletal aging. The understanding of micropetrosis may guide future therapeutics toward preserving osteocyte viability to maintain mechanical competence and fracture resistance of bone in elderly individuals.

  11. [Research of anti-aging mechanism of ginsenoside Rg1 on brain].

    PubMed

    Li, Cheng-peng; Zhang, Meng-si; Liu, Jun; Geng, Shan; Li, Jing; Zhu, Jia-hong; Zhang, Yan-yan; Jia, Yan-yan; Wang, Lu; Wang, Shun-he; Wang, Ya-ping

    2014-11-01

    Neurodegenerative disease is common and frequently occurs in elderly patients. Previous studies have shown that ginsenoside Rg1 was able to inhibit senescent of brain, but the mechanism on the brain during the treatment remains elucidated. To study the mechanism of ginsenoside Rg1 in the process of anti-aging of brain, forty male SD rats were randomly divided into normal group, Rg1 normal group, brain aging model group and Rg1 brain aging model group, each group with 10 rats (brain aging model group: subcutaneous injection of D-galactose (120 mg kg(-1)), qd for 42 consecutive days; Rg1 brain aging model group: while copying the same test as that of brain aging model group, begin intraperitoneal injection of ginsenosides Rg1 (20 mg x kg(-1)) qd for 27 d from 16 d. Rg1 normal group: subcutaneous injection of the same amount of saline; begin intraperitoneal injection of ginsenosides Rg1 (20 mg x kg(-1)) qd for 27 d from 16 d. Normal: injected with an equal volume of saline within the same time. Perform the related experiment on the second day after finishing copying the model or the completion of the first two days of drug injections). Learning and memory abilities were measured by Morris water maze. The number of senescent cells was detected by SA-beta-Gal staining while the level of IL-1 and IL-6 proinflammatory cytokines in hippocampus were detected by ELISA. The activities of SOD, contents of GSH in hippo- campus were quantified by chromatometry. The change of telomerase activities and telomerase length were performed by TRAP-PCR and southern blotting assay, respectively. It is pointed that, in brain aging model group, the spatial learning and memory capacities were weaken, SA-beta-Gal positive granules increased in section of brain tissue, the activity of antioxidant enzyme SOD and the contents of GSH decreased in hippocampus, the level of IL-1 and IL-6 increased in hippocampus, while the length of telomere and the activity of telomerase decreased in hippocampus

  12. Effect of Physical Aging on Mechanical Behavior of an Elastomeric Glass under Combined Pressure and Temperature.

    DTIC Science & Technology

    1986-12-01

    NO. 3. RECIPIENT’S CATALOG NUMBER Technical Report No. 7 C.- 4. TITLE (and Subtitle) S . TYPE OF REPORT & PERIOD COVERED Effect of Physical Aging on...Mechanical Behavior of an Elastomeric Glass Under Combined Pressure and Temperature G. PERFORMING ORG. REPORT NUMBER 7. AUTHOR(e) S . CONTRACT OR GRANT...NUMBER( s ) K. Vijayan and K. D. Pae NOOO14-82-K-0608 9. PERFORMING r" GANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT, TASK High PrE 3,ure

  13. Fracture mechanics research at NASA related to the aging commercial transport fleet

    NASA Astrophysics Data System (ADS)

    Newman, James C., Jr.; Harris, Charles E.

    1992-07-01

    NASA is conducting the Airframe Structural Integrity Program in support of the aging commercial transport fleet. This interdisciplinary program is being worked in cooperation with the U.S. airframe manufacturers, airline operators, and the FAA. Advanced analysis methods are under development and an extensive testing program is under way to study fatigue crack growth and fracture in complex built-up shell structures. Innovative nondestructive examination technologies are also being developed to provide large area inspection capability to detect corrosion, disbonds, and cracks. Recent fracture mechanics results applicable to predicting the growth of cracks under monotonic and cyclic loading at rivets in fuselage lap-splice joints are reviewed.

  14. Oral sapropterin augments reflex vasoconstriction in aged human skin through noradrenergic mechanisms.

    PubMed

    Stanhewicz, Anna E; Alexander, Lacy M; Kenney, W Larry

    2013-10-01

    Reflex vasoconstriction is attenuated in aged skin due to a functional loss of adrenergic vasoconstriction. Bioavailability of tetrahydrobiopterin (BH4), an essential cofactor for catecholamine synthesis, is reduced with aging. Locally administered BH4 increases vasoconstriction through adrenergic mechanisms in aged human skin. We hypothesized that oral sapropterin (Kuvan, a pharmaceutical BH4) would augment vasoconstriction elicited by whole-body cooling and tyramine perfusion in aged skin. Ten healthy subjects (age 75 ± 2 yr) ingested sapropterin (10 mg/kg) or placebo in a randomized, double-blind crossover design. Venous blood samples were collected prior to, and 3 h following ingestion. Three intradermal microdialysis fibers were placed in the forearm skin for local delivery of 1) lactated Ringer, 2) 5 mM BH4, and 3) 5 mM yohimbine + 1 mM propranolol (Y+P; to inhibit adrenergic vasoconstriction). Red cell flux was measured at each site by laser-Doppler flowmetry (LDF) as reflex vasoconstriction was induced by lowering and then clamping whole-body skin temperature (Tsk) using a water-perfused suit. Following whole-body cooling, subjects were rewarmed and 1 mM tyramine was perfused at each site to elicit endogenous norepinephrine release from the perivascular nerve terminal. Cutaneous vascular conductance was calculated as CVC = LDF/mean arterial pressure and expressed as change from baseline (ΔCVC). Plasma BH4 was elevated 3 h after ingestion of sapropterin (43.8 ± 3 vs. 19.1 ± 2 pmol/ml; P < 0.001). Sapropterin increased reflex vasoconstriction at the Ringer site at Tsk ≤ 32.5°C (P < 0.05). Local BH4 perfusion augmented reflex vasoconstriction at Tsk ≤ 31.5°C with placebo treatment only (P < 0.05). There was no treatment effect on reflex vasoconstriction at the BH4-perfused or Y+P-perfused sites. Sapropterin increased pharmacologically induced vasoconstriction at the Ringer site (-0.19 ± 0.03 vs. -0.08 ± 0.02 ΔCVC; P = 0.01). There was no

  15. Age-related ransparent root dentin: mineral concentration,crystallite size and mechanical properties

    SciTech Connect

    Kinney, John H.; Nalla, Ravi K.; Pople, John A.; Breunig, Tom M.; Ritchie, Robert O.

    2004-12-29

    Many fractures occur in teeth that have been altered, forexample restored or endodontically repaired. It is therefore essential toevaluate the structure and mechanical properties of these altereddentins. One such altered form of dentin is transparent (sometimes calledsclerotic) dentin, which forms gradually with aging. The present studyfocuses on differences in the structure and mechanical properties ofnormal versus transparent dentin. The mineral concentration, as measuredby X-ray computed microtomography, was signifcantly higher in transparentdentin, the elevated concentration being consistent with the closure ofthe tubule lumens. Crystallite size, as measured by small angle X-rayscattering, was slightly smaller in transparent dentin, although theimportance of this ending requires further study. The elastic propertieswere unchanged by transparency; however, transparent dentin, unlikenormal dentin, exhibited almost no yielding before failure. In addition,the fracture toughness was lowered by roughly 20 percent while thefatigue lifetime was deleteriously affected at high stress levels. Theseresults are discussed in terms of the altered microstructure oftransparent dentin.

  16. [The study of the effectiveness of drug prevention mechanisms of cardiovascular aging by cytoflavin].

    PubMed

    Kartashova, E A; Romantsov, M G; Sarvilina, I V

    2014-01-01

    The aim of the research was the search of the mechanism of Cytoflavin action in patients with isolated systolic arterial hypertension (ISAH) as the aging model. The following research methods were applied: the assessment of complaints, 24-hour arterial pressure monitoring, ultrasound diagnostic, volume sphygmography, lipid profiles and coagulogram, molecular phenotyping by MALDI-TOF-TOF-MS. The combination of Cytoflavin with standard therapy of ISAH led to the most expressed return development of clinical symptoms, the restoration of the haemodynamics, structural and geometrical parameters of cardiovascular system, indicators lipid profiles and coagulogram in the comparison with patients with ISAH, who accepted standard therapy and those of the control groups. Molecular mechanisms of Cytoflavin action, including regulation of the activity of cell signaling pathways through intermolecular interactions were found. We recommend using Cytoflavin together with the standard therapy in treatment of ISAH, which provides the action of geroprotectors for cardiovascular system.

  17. On the age and formation mechanism of the core of the Quadrantid meteoroid stream

    NASA Astrophysics Data System (ADS)

    Abedin, Abedin; Spurný, Pavel; Wiegert, Paul; Pokorný, Petr; Borovička, Jiří; Brown, Peter

    2015-11-01

    The Quadrantid meteor shower is among the strongest annual meteor showers, and has drawn the attention of scientists for several decades. The stream is unusual, among others, for several reasons: its very short duration around maximum activity (≈12-14 h) as detected by visual, photographic and radar observations, its recent onset (around 1835 AD Quetelet, L.A.J. [1839]. Catalogue des principles apparitions d'etoiles filantes) and because it had been the only major stream without an obvious parent body until 2003. Ever since, there have been debates as to the age of the stream and the nature of its proposed parent body, asteroid 2003 EH1. In this work, we present results on the most probable age and formation mechanism of the narrow portion of the Quadrantid meteoroid stream. For the first time we use data on eight high precision photographic Quadrantids, equivalent to gram-kilogram size, to constrain the most likely age of the core of the stream. Out of eight high-precision photographic Quadrantids, five pertain directly to the narrow portion of the stream. In addition, we also use data on five high-precision radar Quadrantids, observed within the peak of the shower. We performed backwards numerical integrations of the equations of motion of a large number of 'clones' of both, the eight high-precision photographic and five radar Quadrantid meteors, along with the proposed parent body, 2003 EH1. According to our results, from the backward integrations, the most likely age of the narrow structure of the Quadrantids is between 200 and 300 years. These presumed ejection epochs, corresponding to 1700-1800 AD, are then used for forward integrations of large numbers of hypothetical meteoroids, ejected from the parent 2003 EH1, until the present epoch. The aim is to constrain whether the core of the Quadrantid meteoroid stream is consistent with a previously proposed relatively young age (≈200 years).

  18. Life expectancy of kibbutz members.

    PubMed

    Leviatan, U; Cohen, J; Jaffe-Katz, A

    1986-01-01

    Data are presented demonstrating that the life expectancy (LE) of kibbutz members--both men and women--is higher than that of the overall Jewish population in Israel. Closer inspection of the death rates at various ages reveals that, from age thirty, those of kibbutz women are lower than those of the Jewish population. Although those of kibbutz men are actually higher until age forty-nine, nevertheless the LE of kibbutz members (based on death rates) surpasses that of Jews in Israel. These data add to and support other research findings illustrating the more positive mental health and well-being found among kibbutz members than among other comparative populations. Similarly, the factors contributing to kibbutz members' life expectancy evolve from this quality of life, especially as this quality of life affects old age.

  19. Optical characters and texture maps of skin and the aging mechanism by use of multiphoton microscopy and optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Wu, Shulian; Li, Hui; Zhang, Xiaoman; Huang, Yudian; Xu, Xiaohui

    2012-03-01

    Cutaneous aging is a complicated biological process affecting different constituents of skin, which can be divided into two types: the chronological aging and the photo-aging. The two cutaneous aging processes often co-exist accompanying with each other. The effects are often overlapped including changes in epithelium and dermis. The degeneration of collagen is a major factor in dermal alteration with aging. In this study, multiphoton microscopy (MPM) with its high resolution imaging and optical coherence tomography (OCT) with its depth resolved imaging were used to study the anti-aging dermatology in vivo. It was attempted to make the optical parameter and texture feature to evaluate the process of aging skin using mathematical image processing. The links among optical parameter, spectrum and texture feature in collagen with aging process were established to uncover mechanism of aging skin.

  20. Reactive molecule species and antioxidative mechanisms in normal skin and skin aging.

    PubMed

    Wölfle, Ute; Seelinger, Günter; Bauer, Georg; Meinke, Martina C; Lademann, Jürgen; Schempp, Christoph M

    2014-01-01

    Reactive oxygen and nitrogen species (ROS/RNS) which may exist as radicals or nonradicals, as well as reactive sulfur species and reactive carbon species, play a major role in aging processes and in carcinogenesis. These reactive molecule species (RMS), often referred to as 'free radicals' or oxidants, are partly by-products of the physiological metabolism. When RMS concentrations exceed a certain threshold, cell compartments and cells are injured and destroyed. Endogenous physiological mechanisms are able to neutralize RMS to some extent, thereby limiting damage. In the skin, however, pollutants and particularly UV irradiation are able to produce additional oxidants which overload the endogenous protection system and cause early aging, debilitation of immune functions, and skin cancer. The application of antioxidants from various sources in skin care products and food supplements is therefore widespread, with increasingly effective formulations being introduced. The harmful effects of RMS (aside from impaired structure and function of DNA, proteins, and lipids) are: interference with specific regulatory mechanisms and signaling pathways in cell metabolism, resulting in chronic inflammation, weakening of immune functions, and degradation of tissue. Important control mechanisms are: MAP-kinases, the aryl-hydrocarbon receptor (AhR), the antagonistic transcription factors nuclear factor-κB and Nrf2 (nuclear factor erythroid 2-related factor 2), and, especially important, the induction of matrix metalloproteinases which degrade dermal connective tissue. Recent research, however, has revealed that RMS and in particular ROS/RNS are apparently also produced by specific enzyme reactions in an evolutionarily adapted manner. They may fulfill important physiologic functions such as the activation of specific signaling chains in the cell metabolism, defense against infectious pathogens, and regulation of the immune system. Normal physiological conditions are characterized by

  1. The aging of Wolff's "law": ontogeny and responses to mechanical loading in cortical bone.

    PubMed

    Pearson, Osbjorn M; Lieberman, Daniel E

    2004-01-01

    The premise that bones grow and remodel throughout life to adapt to their mechanical environment is often called Wolff's law. Wolff's law, however, is not always true, and in fact comprises a variety of different processes that are best considered separately. Here we review the molecular and physiological mechanisms by which bone senses, transduces, and responds to mechanical loads, and the effects of aging processes on the relationship (if any) between cortical bone form and mechanical function. Experimental and comparative evidence suggests that cortical bone is primarily responsive to strain prior to sexual maturity, both in terms of the rate of new bone growth (modeling) as well as rates of turnover (Haversian remodeling). Rates of modeling and Haversian remodeling, however, vary greatly at different skeletal sites. In addition, there is no simple relationship between the orientation of loads in long bone diaphyses and their cross-sectional geometry. In combination, these data caution against assuming without testing adaptationist views about form-function relationships in order to infer adult activity patterns from skeletal features such as cross-sectional geometry, cortical bones density, and musculo-skeletal stress markers. Efforts to infer function from shape in the human skeleton should be based on biomechanical and developmental models that are experimentally tested and validated.

  2. Genome-wide analysis reveals mechanisms modulating autophagy in normal brain aging and in Alzheimer's disease

    PubMed Central

    Lipinski, Marta M.; Zheng, Bin; Lu, Tao; Yan, Zhenyu; Py, Bénédicte F.; Ng, Aylwin; Xavier, Ramnik J.; Li, Cheng; Yankner, Bruce A.; Scherzer, Clemens R.; Yuan, Junying

    2010-01-01

    Dysregulation of autophagy, a cellular catabolic mechanism essential for degradation of misfolded proteins, has been implicated in multiple neurodegenerative diseases. However, the mechanisms that lead to the autophagy dysfunction are still not clear. Based on the results of a genome-wide screen, we show that reactive oxygen species (ROS) serve as common mediators upstream of the activation of the type III PI3 kinase, which is critical for the initiation of autophagy. Furthermore, ROS play an essential function in the induction of the type III PI3 kinase and autophagy in response to amyloid β peptide, the main pathogenic mediator of Alzheimer's disease (AD). However, lysosomal blockage also caused by Aβ is independent of ROS. In addition, we demonstrate that autophagy is transcriptionally down-regulated during normal aging in the human brain. Strikingly, in contrast to normal aging, we observe transcriptional up-regulation of autophagy in the brains of AD patients, suggesting that there might be a compensatory regulation of autophagy. Interestingly, we show that an AD drug and an AD drug candidate have inhibitory effects on autophagy, raising the possibility that decreasing input into the lysosomal system may help to reduce cellular stress in AD. Finally, we provide a list of candidate drug targets that can be used to safely modulate levels of autophagy without causing cell death. PMID:20660724

  3. Cholesterol metabolism: A review of how ageing disrupts the biological mechanisms responsible for its regulation.

    PubMed

    Morgan, A E; Mooney, K M; Wilkinson, S J; Pickles, N A; Mc Auley, M T

    2016-05-01

    Cholesterol plays a vital role in the human body as a precursor of steroid hormones and bile acids, in addition to providing structure to cell membranes. Whole body cholesterol metabolism is maintained by a highly coordinated balancing act between cholesterol ingestion, synthesis, absorption, and excretion. The aim of this review is to discuss how ageing interacts with these processes. Firstly, we will present an overview of cholesterol metabolism. Following this, we discuss how the biological mechanisms which underpin cholesterol metabolism are effected by ageing. Included in this discussion are lipoprotein dynamics, cholesterol absorption/synthesis and the enterohepatic circulation/synthesis of bile acids. Moreover, we discuss the role of oxidative stress in the pathological progression of atherosclerosis and also discuss how cholesterol biosynthesis is effected by both the mammalian target of rapamycin and sirtuin pathways. Next, we examine how diet and alterations to the gut microbiome can be used to mitigate the impact ageing has on cholesterol metabolism. We conclude by discussing how mathematical models of cholesterol metabolism can be used to identify therapeutic interventions.

  4. Age-hardening mechanisms in a commercial dental gold alloy containing platinum and palladium.

    PubMed

    Tani, T; Udoh, K; Yasuda, K; Van Tendeloo, G; Van Landuyt, J

    1991-10-01

    The age-hardening mechanism of a commercial dental gold alloy containing platinum and palladium (in wt.%, 15 Cu, 6 Ag, 5 Pt, 3 Pd, 3 Zn, with the balance as gold) was elucidated by means of electrical resistivity, hardness tests, x-ray and electron diffraction and electron microscopy, as well as high-resolution electron microscopy. The sequence of phase transformations during isothermal aging below the critical temperature, Tc = 825 K, was described as follows: disordered solid solution alpha 0 (FCC)----metastable AuCu I' ordered phase (FCT)----metastable alpha 2 disordered phase (FCC) equilibrium AuCu I ordered phase (FCT) + equilibrium alpha 2 disordered phase (FCC). The hardening was due to the introduction of coherency strain at the interface between the AuCu I' platelet and the matrix. These ordered platelets had mutually perpendicular c-axes to compensate for the strain introduced by their tetragonality. A loss of coherency at the interface brought about softening of the alloy, i.e., over-aging.

  5. Age hardening characteristics and mechanical behavior of Al-Cu-Li-Zr-In alloys

    NASA Technical Reports Server (NTRS)

    Wagner, John A.

    1989-01-01

    An investigation was conducted to determine the age-hardening response and cryogenic mechanical properties of superplastic Al-Cu-Li-Zr-In alloys. Two alloys with compositions Al-2.65Cu-2.17Li-O.13Zr (baseline) and Al-2.60Cu-2.34Li-0.16Zr-0.17In were scaled-up from 30 lb permanent mold ingots to 350 lb DC (direct chill) ingots and thermomechanically processed to 3.2 mm thick sheet. The microstructure of material which contained the indium addition was partially recrystallized compared to the baseline suggesting that indium may influence recrystallization behavior. The indium-modified alloy exhibited superior hardness and strength compared to the baseline alloy when solution-heat-treated at 555 C and aged at 160 C or 190 C. For each alloy, strength increased and toughness was unchanged or decreased when tested at - 185 C compared to ambient temperature. By using optimized heat treatments, the indium-modified alloy exhibited strength levels approaching those of the baseline alloy without deformation prior to aging. The increase in strength of these alloys in the T6 condition make them particularly attractive for superplastic forming applications where post-SPF parts cannot be cold deformed to increase strength.

  6. The age of groundwater in the Lincolnshire Limestone, England and its relevance to the flow mechanism

    USGS Publications Warehouse

    Downing, R.A.; Smith, D.B.; Pearson, F.J.; Monkhouse, R.A.; Otlet, R.L.

    1977-01-01

    Groundwater samples from the Lincolnshire Limestone have been analysed for tritium, radiocarbon, and the stable-isotope ratios 13C 12C, 18O 16O and D/H. The age of the water increases in a downgradient direction below overlying confining deposits and reaches a maximum age greater than 25,000 years within 15 km of the outcrop. The ?? 13C ratio ultimately attains the unusually low negative values of -2??? in a downgradient direction; this is approaching that of the aquifer matrix which is +2.35???. The reason is believed to be exchange of carbon between the groundwater and the matrix by a continuous process of precipitation and further solution of calcium carbonate. The ?? 18O and ?? D ratios imply that recharge of the aquifer during the late Pleistocene took place in the spring and autumn rather than the winter as at present. The data are interpreted by assuming that movement of water through the saturated zone is a combination of flow in fissures and "piston flow" through the micro-fissures and pores of the rock. The mechanism of water movement in the saturated zone is dominated by relatively rapid flow in fissures, but the fissure flow includes a contribution of much older water from "intergranular" storage which enters the fissures from the rock matrix by pressure differentials in the fissure distribution system and by diffusion. The distribution of water of different ages in the aquifer is closely related to recent groundwater abstraction patterns. ?? 1977.

  7. Changes in pattern completion – a key mechanism to explain age-related recognition memory deficits?

    PubMed Central

    Vieweg, Paula; Stangl, Matthias; Howard, Lorelei R.; Wolbers, Thomas

    2016-01-01

    Accurate memory retrieval from partial or degraded input requires the reactivation of memory traces, a hippocampal mechanism termed pattern completion. Age-related changes in hippocampal integrity have been hypothesized to shift the balance of memory processes in favor of the retrieval of already stored information (pattern completion), to the detriment of encoding new events (pattern separation). Using a novel behavioral paradigm, we investigated the impact of cognitive aging (1) on recognition performance across different levels of stimulus completeness, and (2) on potential response biases. Participants were required to identify previously learned scenes among new ones. Additionally, all stimuli were presented in gradually masked versions to alter stimulus completeness. Both young and older adults performed increasingly poorly as the scenes became less complete, and this decline in performance was more pronounced in elderly participants indicative of a pattern completion deficit. Intriguingly, when novel scenes were shown, only the older adults showed an increased tendency to identify these as familiar scenes. In line with theoretical models, we argue that this reflects an age-related bias towards pattern completion. PMID:25597525

  8. Comparable mechanisms of working memory interference by auditory and visual motion in youth and aging.

    PubMed

    Mishra, Jyoti; Zanto, Theodore; Nilakantan, Aneesha; Gazzaley, Adam

    2013-08-01

    Intrasensory interference during visual working memory (WM) maintenance by object stimuli (such as faces and scenes), has been shown to negatively impact WM performance, with greater detrimental impacts of interference observed in aging. Here we assessed age-related impacts by intrasensory WM interference from lower-level stimulus features such as visual and auditory motion stimuli. We consistently found that interference in the form of ignored distractions and secondary task interruptions presented during a WM maintenance period, degraded memory accuracy in both the visual and auditory domain. However, in contrast to prior studies assessing WM for visual object stimuli, feature-based interference effects were not observed to be significantly greater in older adults. Analyses of neural oscillations in the alpha frequency band further revealed preserved mechanisms of interference processing in terms of post-stimulus alpha suppression, which was observed maximally for secondary task interruptions in visual and auditory modalities in both younger and older adults. These results suggest that age-related sensitivity of WM to interference may be limited to complex object stimuli, at least at low WM loads.

  9. Mechanisms of acetylcholine-mediated vasodilatation in young and aged human skin

    PubMed Central

    Holowatz, Lacy A; Thompson, Caitlin S; Minson, Christopher T; Kenney, W Larry

    2005-01-01

    Thermoregulatory cutaneous vasodilatation (VD) is attenuated in aged skin. While acetylcholine (ACh) plays a role in thermally mediated VD, the precise mechanisms through which ACh-mediated VD acts and whether those downstream mechanisms change with ageing are unclear. We tested the hypotheses that both nitric oxide (NO)- and prostanoid-mediated pathways contribute to exogenous ACh-mediated VD, and that both are attenuated with advanced age. Twelve young (Y: 23 ± 1 years) and 10 older (O: 69 ± 1 years) subjects underwent infusions of 137.5 μm ACh at four intradermal microdialysis sites: control (C, Ringer solution), NO synthase inhibited (NOS-I, 10 mml-NAME), cyclooxygenase inhibited (COX-I, 10 mm ketorolac) and NOS-I + COX-I. Red blood cell flux was monitored using laser-Doppler flowmetry, and cutaneous vascular conductance (CVC) was calculated (laser-Doppler flux/mean arterial pressure) and normalized to maximal CVC (%CVCmax) (28 mm sodium nitroprusside + local heating to 43°C). Baseline %CVCmax was increased in the O at COX-I sites (COX-I 16 ± 1, NOS-I + COX-I 16 ± 2 versus C 10 ± 1%CVCmax; P < 0.001) but not in the young, suggesting an age-related shift toward COX vasoconstrictors contributing to basal cutaneous vasomotor tone. There was no difference in peak %CVCmax during ACh infusion between age groups, and the response was unchanged by NOS-I (O: NOS-I 35 ± 5 versus C 38 ± 5%CVCmax; P = 0.84) (Y: NOS-I 41 ± 4 versus C 39 ± 4%CVCmax; P = 0.67). COX-I and NOS-I + COX-I attenuated the peak CVC response to ACh in both groups (COX-I O: 29 ± 3, Y: 22 ± 2%CVCmaxversus C; P < 0.001 both groups; NOS-I + COX-I O: 32 ± 3 versus Y: 29 ± 2%CVCmax; versus C; P < 0.001 both groups). ACh mediates cutaneous VD through prostanoid and non-NO-, non-prostanoid-dependent pathways. Further, older subjects have a diminished prostanoid contribution to ACh-mediated VD. PMID:15661816

  10. Mechanical and Physical Properties of Both Unaged and Aged Coflon and Tefzel. Revised 18 Mar. 1997

    NASA Technical Reports Server (NTRS)

    Samulak, M.; Campion, R. P.

    1996-01-01

    This report deals with all recent mechanical testing performed on variously aged samples of Coflon and TefzeL to complete the work for Phase 1. Earlier results were reported in CAPP/M.7. Fluids A, F, G, and I have all been used for ageing in the last 12 month period, with particular attention concentrated on the effects of Fluid F as a result of discussions at the December 1995 steering committee meeting in Austin. Dramatic mechanical and physical changes occurred to Coflon in our initial studies after 4 weeks at 120 C in this sour gas mixture and so a detailed matrix was drawn up to investigate the effects of time and temperature of exposure. Subsequent tensile tests and compact tension (CT) fatigue tests were performed. Fatigue testing has been limited during this period to Coflon only; however, Tefzel CT samples have been exposed to the same conditions as the Coflon allowing the possibility for fatigue tests to be performed at a later date. Fluid A exposures during the last 6 months have been long-term at 65 C, 100 C and 120 C only. These exposures have been a continuation of earlier work and will complete the investigation of this fluid. Other chemical ageings have involved Fluid G at 120 C to confirm and investigate the hostile nature of this fluid on Coflon. Again, this fluid will not be used in Phase 2. Finally, long-term exposures in Fluid 1, a high aromatic oil mixture, were carried out to investigate the effects on the polymers of aromaticity in a simulated service fluid.

  11. Education: Expectation and the Unexpected

    ERIC Educational Resources Information Center

    Fulford, Amanda

    2016-01-01

    This paper considers concepts of expectation and responsibility, and how these drive dialogic interactions between tutor and student in an age of marketised Higher Education. In thinking about such interactions in terms of different forms of exchange, the paper considers the philosophy of Martin Buber and Emmanuel Levinas on dialogic…

  12. Mechanisms underlying the production of false memories for famous people's names in aging and Alzheimer's disease.

    PubMed

    Plancher, Gaën; Guyard, Anne; Nicolas, Serge; Piolino, Pascale

    2009-10-01

    It is well known that the occurrence of false memories increases with aging, but the results remain inconsistent concerning Alzheimer's disease (AD). Moreover, the mechanisms underlying the production of false memories are still unclear. Using an experimental episodic memory test with material based on the names of famous people in a procedure derived from the DRM paradigm [Roediger, H. L., III, & McDermott, K. B. (1995). Creating false memories: Remembering words not presented in lists. Journal of Experimental Psychology: Learning, Memory & Cognition, 21, 803-814], we examined correct and false recall and recognition in 30 young adults, 40 healthy older adults, and 30 patients with AD. Moreover, we evaluated the relationships between false memory performance, correct episodic memory performance, and a set of neuropsychological assessments evaluating the semantic memory and executive functions. The results clearly indicated that correct recall and recognition performance decreased with the subjects' age, but it decreased even more with AD. In addition, semantically related false recalls and false recognitions increased with age but not with dementia. On the contrary, non-semantically related false recalls and false recognitions increased with AD. Finally, the regression analyses showed that executive functions mediated related false memories and episodic memory mediated related and unrelated false memories in aging. Moreover, executive functions predicted related and unrelated false memories in AD, and episodic and semantic memory predicted semantically related and unrelated false memories in AD. In conclusion, the results obtained are consistent with the current constructive models of memory suggesting that false memory creation depends on different cognitive functions and, consequently, that the impairments of these functions influence the production of false memories.

  13. Mechanical properties of thermally aged cast stainless steels from Shippingport reactor components

    SciTech Connect

    Chopra, O.K.; Shack, W.J.

    1995-04-01

    Thermal embrittlement of static-cast CF-8 stainless steel components from the decommissioned Shippingport reactor has been characterized. Cast stainless steel materials were obtained from four cold-leg check valves, three hot-leg main shutoff valves, and two pump volutes. The actual time-at-temperature for the materials was {approximately}13 y at {approximately}281 C (538 F) for the hot-leg components and {approximately}264 C (507 F) for the cold-leg components. Baseline mechanical properties for as-cast material were determined from tests on either recovery-annealed material, i.e., annealed for 1 h at 550 C and then water quenched, or material from the cooler region of the component. The Shippingport materials show modest decreases in fracture toughness and Charpy-impact properties and a small increase in tensile strength because of relatively low service temperatures and ferrite content of the steel. The procedure and correlations developed at Argonne National Laboratory for estimating mechanical properties of cast stainless steels predict accurate or slightly lower values for Charpy-impact energy, tensile flow stress, fracture toughness J-R curve, and J{sub IC} of the materials. The kinetics of thermal embrittlement and degree of embrittlement at saturation, i.e., the minimum impact energy achieved after long-term aging, were established from materials that were aged further in the laboratory. The results were consistent with the estimates. The correlations successfully predicted the mechanical properties of the Ringhals 2 reactor hot and crossover-leg elbows (CF-8M steel) after service of {approximately} 15 y and the KRB reactor pump cover plate (CF-8) after {approximately} 8 y of service.

  14. Mechanical properties of thermally aged cast stainless steels from shippingport reactor components.

    SciTech Connect

    Chopra, O. K.; Shack, W. J.; Energy Technology

    1995-06-07

    Thermal embrittlement of static-cast CF-8 stainless steel components from the decommissioned Shippingport reactor has been characterized. Cast stainless steel materials were obtained from four cold-leg check valves, three hot-leg main shutoff valves, and two pump volutes. The actual time-at-temperature for the materials was {approx}13 y at {approx}281 C (538 F) for the hot-leg components and {approx}264 C (507 F) for the cold-leg components. Baseline mechanical properties for as-cast material were determined from tests on either recovery-annealed material, i.e., annealed for 1 h at 550 C and then water quenched, or material from the cooler region of the component. The Shippingport materials show modest decreases in fracture toughness and Charpy-impact properties and a small increase in tensile strength because of relatively low service temperatures and ferrite content of the steel. The procedure and correlations developed at Argonne National Laboratory for estimating mechanical properties of cast stainless steels predict accurate or slightly lower values for Charpy-impact energy, tensile flow stress, fracture toughness J-R curve, and JIC of the materials. The kinetics of thermal embrittlement and degree of embrittlement at saturation, i.e., the minimum impact energy achieved after long-term aging, were established from materials that were aged further in the laboratory. The results were consistent with the estimates. The correlations successfully predicted the mechanical properties of the Ringhals 2 reactor hot- and crossover-leg elbows (CF-8M steel) after service of {approx}15 y and the KRB reactor pump cover plate (CF-8) after {approx}8 y of service.

  15. Investigation of the Dynamic Strain Aging and Mechanical Properties in Alloy-625 with Different Microstructures

    NASA Astrophysics Data System (ADS)

    Chatterjee, Arnomitra; Sharma, Garima; Tewari, R.; Chakravartty, J. K.

    2015-03-01

    Tensile tests were carried out on service exposed Alloy 625 ammonia cracker tube used at heavy water production plant to study the effect of microstructure on the serrated yielding and mechanical properties of the material. Owing to temperature gradient during service exposure, the microstructure was different in top, middle, and bottom sections of the tube. Variation of flow stress, ductility, and average work hardening were monitored with temperature. In the present work, emphasis was given on the study of serrated yielding in the service exposed Alloy 625. Detail investigations were made to study the effect of microstructure on the underlying mechanism of dynamic strain aging of the material. The study revealed that both the normal and the inverse Portevin-Le Chatelier effect (PLC) occured in the material at lower and higher temperature regime, respectively. While the normal PLC dynamics was associated with locking of dislocations by interstitial carbon atoms, the inverse one was accomplished by the dislocation pinning by substitutional Mo atoms. Further analyses identified that the basic deformation mechanism was different in middle and bottom samples as that in the top samples which was reflected in the difference in their respective activation energy and stress drop magnitude.

  16. Oral sapropterin acutely augments reflex vasodilation in aged human skin through nitric oxide-dependent mechanisms.

    PubMed

    Stanhewicz, Anna E; Alexander, Lacy M; Kenney, W Larry

    2013-10-01

    Functional constitutive nitric oxide synthase (NOS) and its cofactor tetrahydrobiopterin (BH4) are required for full reflex cutaneous vasodilation and are attenuated in primary aging. Acute, locally administered BH4 increases reflex vasodilation through NO-dependent mechanisms in aged skin. We hypothesized that oral sapropterin (Kuvan, shelf-stable pharmaceutical formulation of BH4) would augment reflex vasodilation in aged human skin during hyperthermia. Nine healthy human subjects (76 ± 1 yr) ingested sapropterin (10 mg/kg) or placebo in a randomized double-blind crossover design. Venous blood samples were collected prior to, and 3 h following, ingestion of sapropterin for measurement of plasma BH4. Three intradermal microdialysis fibers were placed in the forearm skin for local delivery of 1) lactated Ringer's solution, 2) 10 mM BH4, and 3) 20 mM N(G)-nitro-l-arginine methyl ester (l-NAME) to inhibit NOS. Red cell flux was measured at each site by laser-Doppler flowmetry (LDF) as reflex vasodilation was induced using a water-perfused suit. At 1°C rise in oral temperature, mean body temperature was clamped and 20 mM l-NAME was perfused at each site. Cutaneous vascular conductance was calculated (CVC = LDF/MAP) and expressed as a percentage of maximum (%CVCmax 28 mM sodium nitroprusside and local heat 43°C). Plasma concentrations of BH4 were significantly elevated 3 h after ingestion of sapropterin (0 h: 19.1 ± 2 pmol/ml vs. 3 h: 43.8 ± 3 pmol/ml; P < 0.001). Sapropterin increased NO-dependent vasodilation at control site (placebo: 14 ± 1 %CVCmax vs. sapropterin: 25 ± 4 %CVCmax; P = 0.004). Local BH4 administration increased NO-dependent vasodilation compared with control in placebo trials only (control: 14 ± 1 %CVCmax vs. BH4-treated: 24 ± 3 %CVCmax; P = 0.02). These data suggest oral sapropterin increases bioavailable BH4 in aged skin microvasculature sufficiently to increase NO synthesis through NOS and that sapropterin may be a viable intervention to

  17. Walter Benjamin in the Age of Digital Reproduction: Aura in Education--A Rereading of "The Work of Art in the Age of Mechanical Reproduction"

    ERIC Educational Resources Information Center

    Peim, Nick

    2007-01-01

    This paper considers a key text in the field of Cultural Studies for its relevance to questions about the identity of knowledge in education. The concept of "aura" arises as being of special significance in "The Work of Art in the Age of Mechanical Reproduction" as a way of understanding the change that occurs to art when mass reproduction becomes…

  18. Molecular mechanisms of subretinal fibrosis in age-related macular degeneration

    PubMed Central

    Ishikawa, Keijiro; Kannan, Ram; Hinton, David R

    2015-01-01

    Subretinal fibrosis is a result of a wound healing response that follows choroidal neovascularization in neovascular age-related macular degeneration (nAMD). Although anti-vascular endothelial growth factor therapy has become a standard treatment that improves visual acuity in many nAMD patients, unsuccessful treatment outcomes have often been attributed to the progression of subretinal fibrosis. In this review, we summarize the cellular and extracellular components of subretinal fibrous membranes and also discuss the possible molecular mechanisms including the functional involvement of growth factors and the inflammatory response in the process. Moreover, we present an murine animal model of subretinal fibrosis that might facilitate greater understanding of the pathophysiology and the development of novel therapeutic strategies for the inhibition of subretinal fibrosis in nAMD. PMID:25773985

  19. Endoplasmic reticulum stress as a primary pathogenic mechanism leading to age-related macular degeneration.

    PubMed

    Libby, Richard T; Gould, Douglas B

    2010-01-01

    Age-related macular degeneration (AMD) is a multi-factorial disease and a leading cause of blindness. Proteomic and genetic data suggest that activation or de-repression of the alternate complement cascade of innate immunity is involved in end-stage disease. Several lines of evidence suggest that production of reactive oxygen species and chronic oxidative stress lead to protein and lipid modifications that initiate the complement cascade. Understanding the triggers of these pathogenic pathways and the site of the primary insult will be important for development of targeted therapeutics. Endoplasmic reticulum (ER) stress from misfolded mutant proteins and other sources are an important potential tributary mechanism. We propose that misfolded-protein-induced ER stress in the retinal-pigmented epithelium and/or choroid could lead to chronic oxidative stress, complement deregulation and AMD. Small molecules targeted to ER stress and oxidative stress could allow for a shift from disease treatment to disease prevention.

  20. Effect of ageing time on mechanical properties of plasticized poly(hydroxybutyrate) (PHB)

    NASA Astrophysics Data System (ADS)

    Farris, Giuseppe; Cinelli, Patrizia; Anguillesi, Irene; Salvadori, Sara; Coltelli, Maria-Beatrice; Lazzeri, Andrea

    2014-05-01

    Polyhydroxybutyrate (PHB) based materials were prepared by melt extrusion by using different plasticizers, such as poly(ethylene glycol)s (PEG)s having different molecular weight (400, 1500 and 4000). The plasticizers content was varied in the range 10-20% by weight versus the PHB polymeric matrix. The variation of tensile properties of the different samples was monitored as a function of time of ageing to study the stability of the material. The elastic modulus and tensile strength increased as a function of time, whereas the strain at break decreased. The experimental results were explained by considering both the demixing of the plasticizers and the occurring of secondary crystallization. Moreover the variation in mechanical properties was correlated to the structure and concentration of the different plasticizers employed.

  1. Two-subsystem thermodynamics for the mechanics of aging amorphous solids

    NASA Astrophysics Data System (ADS)

    Semkiv, Mykhailo; Anderson, Patrick D.; Hütter, Markus

    2017-03-01

    The effect of physical aging on the mechanics of amorphous solids as well as mechanical rejuvenation is modeled with nonequilibrium thermodynamics, using the concept of two thermal subsystems, namely a kinetic one and a configurational one. Earlier work (Semkiv and Hütter in J Non-Equilib Thermodyn 41(2):79-88, 2016) is extended to account for a fully general coupling of the two thermal subsystems. This coupling gives rise to hypoelastic-type contributions in the expression for the Cauchy stress tensor, that reduces to the more common hyperelastic case for sufficiently long aging. The general model, particularly the reversible and irreversible couplings between the thermal subsystems, is compared in detail with models in the literature (Boyce et al. in Mech Mater 7:15-33, 1988; Buckley et al. in J Mech Phys Solids 52:2355-2377, 2004; Klompen et al. in Macromolecules 38:6997-7008, 2005; Kamrin and Bouchbinder in J Mech Phys Solids 73:269-288 2014; Xiao and Nguyen in J Mech Phys Solids 82:62-81, 2015). It is found that only for the case of Kamrin and Bouchbinder (J Mech Phys Solids 73:269-288, 2014) there is a nontrivial coupling between the thermal subsystems in the reversible dynamics, for which the Jacobi identity is automatically satisfied. Moreover, in their work as well as in Boyce et al. (Mech Mater 7:15-33, 1988), viscoplastic deformation is driven by the deviatoric part of the Cauchy stress tensor, while for Buckley et al. (J Mech Phys Solids 52:2355-2377, 2004) and Xiao and Nguyen (J Mech Phys Solids 82:62-81, 2015) this is not the case.

  2. Influence of Thrombus Age on the Mechanical Thrombectomy Efficacy of the Amplatz Thrombectomy Device In Vitro

    SciTech Connect

    Grimm, Jan Jahnke, Thomas; Muhle, Claus; Heller, Martin; Mueller-Huelsbeck, Stefan

    2003-06-15

    Purpose: To determine the efficacy of thrombectomy for the Amplatz Thrombectomy Device (ATD) according to the age of the thrombus. Methods: Thrombectomy was performed with the 7 Fr or 8 Fr ATD. Five-day-old or 8-day-old thrombi were made from porcine blood by clotting within silicone tubes to be used in a flow model. Emboli sizes, weight, remaining thrombus and activation time were evaluated. Results: The age of the thrombus had no influence on the activation time necessary for complete thrombolysis. A significant difference was found in the overall amount of embolization only with the 7 Fr device although a similar trend was shown with the 8 Fr device. The amount of embolized thrombotic material was higher for both devices if older thrombi (i.e., 8 days old) we reprocessed. The overall impression was that the 8 Fr device showed slightly better results (less remaining thrombus and embolization). Conclusion: A tendency toward higher amounts of embolization was observed if older thrombi were used in the model. Therefore the interventional radiologist should be aware of the potentially higher risk of peripheral embolization when performing mechanical thrombectomy(with the ATD) in older thrombotic occlusions, especially since the higher rate of embolization was mainly due to an increased proportion of larger embolic particles (1 mm), which are clinically more significant.

  3. Vascular Smooth Muscle Cell Stiffness as a Mechanism for Increased Aortic Stiffness with Aging

    PubMed Central

    Qiu, Hongyu; Zhu, Yi; Sun, Zhe; Trzeciakowski, Jerome P.; Gansner, Meredith; Depre, Christophe; Resuello, Ranillo R.G.; Natividad, Filipinas F.; Hunter, William C.; Genin, Guy M.; Elson, Elliot L.; Vatner, Dorothy E.; Meininger, Gerald A.; Vatner, Stephen F.

    2010-01-01

    Rationale Increased aortic stiffness, an important feature of many vascular diseases, e.g., aging, hypertension, atherosclerosis and aortic aneurysms, is assumed due to changes in extracellular matrix (ECM). Objective We tested the hypothesis that the mechanisms also involve intrinsic stiffening of vascular smooth muscle cells (VSMCs). Methods and Results Stiffness was measured in vitro both by atomic force microscopy (AFM) and in a reconstituted tissue model, using VSMCs from aorta of young versus old male monkeys (Macaca fascicularis, n=7/group), where aortic stiffness increases by 200 % in vivo. The apparent elastic modulus was increased (P<0.05) in old VSMCs (41.7±0.5 kPa) versus young (12.8±0.3 kPa), but not after disassembly of the actin cytoskeleton with cytochalasin D. Stiffness of the VSMCs in the reconstituted tissue model was also higher (P<0.05) in old (23.3±3.0 kPa) than in young (13.7±2.4 kPa). Conclusions These data support the novel concept, not appreciated previously, that increased vascular stiffness with aging is due not only to changes in ECM, but also to intrinsic changes in VSMCs. PMID:20634486

  4. Effect of Aging Treatments on the Mechanical and Corrosive Behaviors of Spray-Formed 7075 Alloy

    NASA Astrophysics Data System (ADS)

    Su, Rui-ming; Qu, Ying-dong; Li, Rong-de

    2014-11-01

    Mechanical properties, microstructure, exfoliation corrosion (EXCO), and intergranular corrosion (IGC) behaviors of the spray-formed 7075 aluminum alloy after T6, T73, retrogression (R), and re-aging (RRA) treatment, respectively, were studied by using tensile tester, transmission electron microscope, and scanning electron microscope. The results show that the T6 process can increase the ultimate tensile strength (UTS) up to 760 MPa, while it decreases the elongation, the EXCO, and the IGC resistance of the alloy. The T73 process can improve elongation, the EXCO, and the IGC resistance of the alloy. The corrosion resistance of the alloy can also be improved by R and RRA processes with retrogression times increase. The tiny precipitated phases distributed homogeneously in the matrix can increase the UTS. The close-connected discrete grain boundary phases (GBP) and the narrow precipitate free zones (PFZ) will lower the elongation, the EXCO, and the IGC resistance of the alloy. Contrarily, the discrete GBP and wide PFZ can improve the elongation, the EXCO, and the IGC resistance of the alloy. The EXCO and the IGC behaviors for the spray-formed 7075 alloy after different aging treatments have been established according to the standards of ASTM G34-2001 (2007) and ASTM G110-1992 (2009).

  5. Expecting the Best

    ERIC Educational Resources Information Center

    DiPaula, John

    2010-01-01

    Educational expectations are psychological constructs that change over time and can be altered or influenced by various factors. The concept of educational expectations refers to how much schooling students realistically believe that they will complete. These expectations are eventually raised or lowered as students see others like themselves…

  6. A Mechanism For Solar Forcing of Climate: Did the Maunder Minimum Cause the Little Ice Age?

    NASA Technical Reports Server (NTRS)

    Yung, Yuk L.

    2004-01-01

    The mechanism we wish to demonstrate exploits chemical, radiative, and dynamical sensitivities in the stratosphere to affect the climate of the troposphere. The sun, while its variability in total radiative output over the course of the solar cycle is on the order of 0.1%, exhibits variability in the UV output on the order of 5%. We expect to show that a substantially decreased solar UV output lessened the heating of the Earth's stratosphere during the Maunder Minimum, through decreased radiative absorption by ozone and oxygen. These changes in stratospheric heating would lead to major changes in the stratospheric zonal wind pattern which would in turn affect the propagation characteristics of planetary-scale waves launched in the winter hemisphere. Until recently, there was no quantitative data to relate the changes in the stratosphere to those at the surface. There is now empirical evidence from the NCEP Reanalysis data that a definitive effect of the solar cycle on climate in the troposphere exists. Our recent work is summarized as follows (see complete list of publications in later part of this report).

  7. Temporal expectancy modulates phasic alerting in both detection and discrimination tasks.

    PubMed

    Lu, Shena; Wang, Wei; Cai, Yongchun

    2015-02-01

    The aim of the present study was to investigate whether phasic alerting might be modulated by temporal expectancy and to determine the processing stages at which this modulation might occur. We manipulated participants' expectancy for the target appearance by systematically varying the cue-target stimulus onset asynchrony (SOA) distribution in both detection and discrimination tasks. There were three temporal expectancy conditions: the non-aging condition in which temporal expectancy was eliminated, the aging condition in which temporal expectancy increased as SOA increased, and the accelerated-aging condition in which temporal expectancy increased more dramatically as SOA increased than in the aging condition. We obtained the same pattern of results in both detection and discrimination tasks: the onset time of the alerting effect was postponed successively across the three temporal expectancy conditions. The present findings suggest that the time course of the alerting effect may be modulated by temporal expectancy, highlighting the importance of taking account into the influence of temporal expectancy in studies involving the time course of cognitive processes. Furthermore, since mechanisms underlying the detection and discrimination tasks may differ in early processing stages involving perceptual analysis and response selection, the same result pattern observed in both tasks is consistent with the hypothesis that the modulation of temporal expectancy on phasic alerting occurs at late processing stages involving motor preparation.

  8. Estimation of mechanical properties of cast stainless steels during thermal aging in LWR systems

    SciTech Connect

    Chopra, O.K.

    1991-10-01

    A procedure and correlations are presented for predicting Charpy-impact energy, tensile flow stress, fracture toughness J-R curve, and J{sub IC} of aged cast stainless steels from known material information. The ``saturation`` impact strength and fracture toughness of a specific cast stainless steel, i.e., the minimum value that would be achieved for the material after long-term service, is estimated from the chemical composition of the steel. Mechanical properties as a function of time and temperature of reactor service are estimated from impact energy and flow stress of the unaged material and the kinetics of embrittlement, which are also determined from chemical composition. The J{sub IC} values are determined from the estimated J-R curve and flow stress. Examples of estimating mechanical properties of cast stainless steel components during reactor service are presented. A common predicted lower-bound J-R curve for cast stainless steels of unknown chemical composition is also defined for a given grade of steel, ferrite content, and temperature.

  9. Microstructure and mechanical properties of composite resins subjected to accelerated artificial aging.

    PubMed

    dos Reis, Andréa Cândido; de Castro, Denise Tornavoi; Schiavon, Marco Antônio; da Silva, Leandro Jardel; Agnelli, José Augusto Marcondes

    2013-01-01

    The aim of this study was to investigate the influence of accelerated artificial aging (AAA) on the microstructure and mechanical properties of the Filtek Z250, Filtek Supreme, 4 Seasons, Herculite, P60, Tetric Ceram, Charisma and Filtek Z100. composite resins. The composites were characterized by Fourier-transform Infrared spectroscopy (FTIR) and thermal analyses (Differential Scanning Calorimetry - DSC and Thermogravimetry - TG). The microstructure of the materials was examined by scanning electron microscopy. Surface hardness and compressive strength data of the resins were recorded and the mean values were analyzed statistically by ANOVA and Tukey's test (α=0.05). The results showed significant differences among the commercial brands for surface hardness (F=86.74, p<0.0001) and compressive strength (F=40.31, p<0.0001), but AAA did not affect the properties (surface hardness: F=0.39, p=0.53; compressive strength: F=2.82, p=0.09) of any of the composite resins. FTIR, DSC and TG analyses showed that resin polymerization was complete, and there were no differences between the spectra and thermal curve profiles of the materials obtained before and after AAA. TG confirmed the absence of volatile compounds and evidenced good thermal stability up to 200 °C, and similar amounts of residues were found in all resins evaluated before and after AAA. The AAA treatment did not significantly affect resin surface. Therefore, regardless of the resin brand, AAA did not influence the microstructure or the mechanical properties.

  10. Degradation mechanisms of cable insulation materials during radiation-thermal ageing in radiation environment

    NASA Astrophysics Data System (ADS)

    Seguchi, Tadao; Tamura, Kiyotoshi; Ohshima, Takeshi; Shimada, Akihiko; Kudoh, Hisaaki

    2011-02-01

    Radiation and thermal degradation of ethylene-propylene rubber (EPR) and crosslinked polyethylene (XLPE) as cable insulation materials were investigated by evaluating tensile properties, gel-fraction, and swelling ratio, as well as by the infrared (FTIR) analysis. The activation energy of thermal oxidative degradation changed over the range 100-120 °C for both EPR and XLPE. This may be attributed to the fact that the content of an antioxidant used as the stabilizer for polymers decreases by evaporation during thermal ageing at high temperatures. The analysis of antioxidant content and oxidative products in XLPE as a model sample showed that a small amount of antioxidant significantly reduced the extent of thermal oxidation, but was not effective for radiation induced oxidation. The changes in mechanical properties were well reflected by the degree of oxidation. A new model of polymer degradation mechanisms was proposed where the degradation does not take place by chain reaction via peroxy radical and hydro-peroxide. The role of the antioxidant in the polymer is the reduction of free radical formation in the initiation step in thermal oxidation, and it could not stop radical reactions for either radiation or thermal oxidation.

  11. Thermal aging of cast stainless steels in LWR systems: Estimation of mechanical properties

    SciTech Connect

    Chopra, O.K.

    1991-11-01

    A procedure and correlations are presented for predicting Charpy-impact energy, tensile flow stress, fracture toughness J-R curve, and J{sub IC} of aged cast stainless steels from known material information. The ``saturation`` impact strength and fracture toughness of a specific cast stainless steel, i.e., the minimum value that would be achieved for the material after long-term service, is estimated from the chemical composition of the steel. Mechanical properties as a function of time and temperature of reactor service are estimated from impact energy and flow stress of the unaged material and the kinetics of embrittlement, which are also determined from chemical composition. The J{sub IC} values are determined from the estimated J-R curve and flow stress. Examples of estimating mechanical properties of cast stainless steel components during reactor service are presented. A common ``lower-bound`` J-R curve for cast stainless steels of unknown chemical composition is also defined for a given grade of steel, ferrite content, and temperature.

  12. Thermal aging of cast stainless steels in LWR systems: Estimation of mechanical properties

    SciTech Connect

    Chopra, O.K.

    1991-11-01

    A procedure and correlations are presented for predicting Charpy-impact energy, tensile flow stress, fracture toughness J-R curve, and J{sub IC} of aged cast stainless steels from known material information. The saturation'' impact strength and fracture toughness of a specific cast stainless steel, i.e., the minimum value that would be achieved for the material after long-term service, is estimated from the chemical composition of the steel. Mechanical properties as a function of time and temperature of reactor service are estimated from impact energy and flow stress of the unaged material and the kinetics of embrittlement, which are also determined from chemical composition. The J{sub IC} values are determined from the estimated J-R curve and flow stress. Examples of estimating mechanical properties of cast stainless steel components during reactor service are presented. A common lower-bound'' J-R curve for cast stainless steels of unknown chemical composition is also defined for a given grade of steel, ferrite content, and temperature.

  13. Surface and Mechanical Characterization of Dental Yttria-Stabilized Tetragonal Zirconia Polycrystals (3Y-TZP) After Different Aging Processes.

    PubMed

    Pinto, Palena A; Colas, Guillaume; Filleter, Tobin; De Souza, Grace M

    2016-12-01

    Yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) is a ceramic material used in indirect dental restorations. However, phase transformation at body temperature may compromise the material's mechanical properties, affecting the clinical performance of the restoration. The effect of mastication on 3Y-TZP aging has not been investigated. 3Y-TZP specimens (IPS E-max ZirCAD and Z5) were aged in three different modes (n=13): no aging (control), hydrothermal aging (HA), or chewing simulation (CS). Mechanical properties and surface topography were analyzed. Analysis of variance showed that neither aging protocol (p=0.692) nor material (p=0.283) or the interaction between them (p=0.216) had a significant effect on flexural strength, values ranged from 928.8 MPa (IPSHA) to 1,080.6 MPa (Z5HA). Nanoindentation analysis showed that material, aging protocol, and the interaction between them had a significant effect (p<0.001) on surface hardness and reduced Young's modulus. The compositional analysis revealed similar yttrium content for all the experimental conditions (aging: p=0.997; material: p=0.248; interaction material×aging: p=0.720). Atomic force microscopy showed an effect of aging protocols on phase transformation, with samples submitted to CS exhibiting features compatible with maximized phase transformation, such as increased volume of the material microstructure at the surface leading to an increase in surface roughness.

  14. Effects of Aging Treatments on the Mechanical Behavior of Ti-15V-3Cr-3Sn-3Al Alloy

    NASA Astrophysics Data System (ADS)

    Chou, Y.-K.; Tsay, L. W.; Chen, C.

    2015-09-01

    The effect of aging treatments on the mechanical properties and microstructures of Ti-15V-3Cr-3Sn-3Al (Ti-15-3) alloy was evaluated using tensile, notched tensile, and J-integral tests. The properties for the one-step aged specimens (371 to 648 °C for 8 h) were compared with those for the two-step aged specimens (one-step aged + 426 °C/24 h). An increase in aging temperature of one-step aging resulted in increased notched tensile strength and fracture toughness of the Ti-15-3 alloy. The second-step aging at 426 °C for 24 h caused various degrees of hardening in the group of double aged specimens. Comparing to the one-step aged specimens, increased notch brittleness and decreased fracture toughness were observed in the two-step aged specimens. For the specimens subjected to aging at 648 °C, the formation of thick α layer at β grain boundaries resulted in lower tensile properties and fracture toughness. The fracture modes of the notch-brittle specimens were strongly affected by the distribution, size, and morphology of the α precipitates.

  15. Kazakhstan can achieve ambitious HIV targets despite expected donor withdrawal by combining improved ART procurement mechanisms with allocative and implementation efficiencies

    PubMed Central

    Benedikt, Clemens; Bokazhanova, Aliya; Đurić, Predrag; Petrenko, Irina; Ganina, Lolita; Kelly, Sherrie L.; Stuart, Robyn M.; Kerr, Cliff C.; Vinichenko, Tatiana; Zhang, Shufang; Hamelmann, Christoph; Manova, Manoela; Masaki, Emiko; Wilson, David P.; Gray, Richard T.

    2017-01-01

    Background Despite a non-decreasing HIV epidemic, international donors are soon expected to withdraw funding from Kazakhstan. Here we analyze how allocative, implementation, and technical efficiencies could strengthen the national HIV response under assumptions of future budget levels. Methodology We used the Optima model to project future scenarios of the HIV epidemic in Kazakhstan that varied in future antiretroviral treatment unit costs and management expenditure—two areas identified for potential cost-reductions. We determined optimal allocations across HIV programs to satisfy either national targets or ambitious targets. For each scenario, we considered two cases of future HIV financing: the 2014 national budget maintained into the future and the 2014 budget without current international investment. Findings Kazakhstan can achieve its national HIV targets with the current budget by (1) optimally re-allocating resources across programs and (2) either securing a 35% [30%–39%] reduction in antiretroviral treatment drug costs or reducing management costs by 44% [36%–58%] of 2014 levels. Alternatively, a combination of antiretroviral treatment and management cost-reductions could be sufficient. Furthermore, Kazakhstan can achieve ambitious targets of halving new infections and AIDS-related deaths by 2020 compared to 2014 levels by attaining a 67% reduction in antiretroviral treatment costs, a 19% [14%–27%] reduction in management costs, and allocating resources optimally. Significance With Kazakhstan facing impending donor withdrawal, it is important for the HIV response to achieve more with available resources. This analysis can help to guide HIV response planners in directing available funding to achieve the greatest yield from investments. The key changes recommended were considered realistic by Kazakhstan country representatives. PMID:28207809

  16. A conserved splicing mechanism of the LMNA gene controls premature aging.

    PubMed

    Lopez-Mejia, Isabel C; Vautrot, Valentin; De Toledo, Marion; Behm-Ansmant, Isabelle; Bourgeois, Cyril F; Navarro, Claire L; Osorio, Fernando G; Freije, José M P; Stévenin, James; De Sandre-Giovannoli, Annachiara; Lopez-Otin, Carlos; Lévy, Nicolas; Branlant, Christiane; Tazi, Jamal

    2011-12-01

    Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disorder phenotypically characterized by many features of premature aging. Most cases of HGPS are due to a heterozygous silent mutation (c.1824C>T; p.Gly608Gly) that enhances the use of an internal 5' splice site (5'SS) in exon 11 of the LMNA pre-mRNA and leads to the production of a truncated protein (progerin) with a dominant negative effect. Here we show that HGPS mutation changes the accessibility of the 5'SS of LMNA exon 11 which is sequestered in a conserved RNA structure. Our results also reveal a regulatory role of a subset of serine-arginine (SR)-rich proteins, including serine-arginine rich splicing factor 1 (SRSF1) and SRSF6, on utilization of the 5'SS leading to lamin A or progerin production and a modulation of this regulation in the presence of the c.1824C>T mutation is shown directly on HGPS patient cells. Mutant mice carrying the equivalent mutation in the LMNA gene (c.1827C>T) also accumulate progerin and phenocopy the main cellular alterations and clinical defects of HGPS patients. RNAi-induced depletion of SRSF1 in the HGPS-like mouse embryonic fibroblasts (MEFs) allowed progerin reduction and dysmorphic nuclei phenotype correction, whereas SRSF6 depletion aggravated the HGPS-like MEF's phenotype. We demonstrate that changes in the splicing ratio between lamin A and progerin are key factors for lifespan since heterozygous mice harboring the mutation lived longer than homozygous littermates but less than the wild-type. Genetic and biochemical data together favor the view that physiological progerin production is under tight control of a conserved splicing mechanism to avoid precocious aging.

  17. Mitochondrial protection and anti-aging activity of Astragalus polysaccharides and their potential mechanism.

    PubMed

    Li, Xing-Tai; Zhang, Ya-Kui; Kuang, Hai-Xue; Jin, Feng-Xin; Liu, De-Wen; Gao, Ming-Bo; Liu, Ze; Xin, Xiao-Juan

    2012-01-01

    The current study was performed to investigate mitochondrial protection and anti-aging activity of Astragalus polysaccharides (APS) and the potential underlying mechanism. Lipid peroxidation of liver and brain mitochondria was induced by Fe(2+)-Vit C in vitro. Thiobarbituric acid (TBA) colorimetry was used to measure the content of thiobarbituric acid reactive substances (TBARS). Mouse liver mitochondrial permeability transition (PT) was induced by calcium overload in vitro and spectrophotometry was used to measure it. The scavenging activities of APS on superoxide anion (O(2) (•-)) and hydroxyl radical (•OH), which were produced by reduced nicotinamide adenine dinucleotide (NADH)-N-Methylphenazonium methyl sulfate (PMS) and hydrogen peroxide (H(2)O(2))-Fe(2+) system respectively, were measured by 4-nitrobluetetrazolium chloride (NBT) reduction and Fenton reaction colorimetry respectively. The Na(2)S(2)O(3) titration method was used to measure the scavenging activities of APS on H(2)O(2). APS could inhibit TBARS production, protect mitochondria from PT, and scavenge O(2) (•-), •OH and H(2)O(2) significantly in a concentration-dependent manner respectively. The back of the neck of mice was injected subcutaneously with D-galactose to induce aging at a dose of 100 mg/kg/d for seven weeks. Moreover, the activities of catalase (CAT), surperoxide dismutase (SOD) and glutathione peroxidase (GPx) and anti-hydroxyl radical which were assayed by using commercial monitoring kits were increased significantly in vivo by APS. According to this research, APS protects mitochondria by scavenging reactive oxygen species (ROS), inhibiting mitochondrial PT and increasing the activities of antioxidases. Therefore, APS has the effect of promoting health.

  18. Mechanisms underlying age- and performance-related differences in working memory.

    PubMed

    Daffner, Kirk R; Chong, Hyemi; Sun, Xue; Tarbi, Elise C; Riis, Jenna L; McGinnis, Scott M; Holcomb, Phillip J

    2011-06-01

    This study took advantage of the subsecond temporal resolution of ERPs to investigate mechanisms underlying age- and performance-related differences in working memory. Young and old subjects participated in a verbal n-back task with three levels of difficulty. Each group was divided into high and low performers based on accuracy under the 2-back condition. Both old subjects and low-performing young subjects exhibited impairments in preliminary mismatch/match detection operations (indexed by the anterior N2 component). This may have undermined the quality of information available for the subsequent decision-making process (indexed by the P3 component), necessitating the appropriation of more resources. Additional anterior and right hemisphere activity was recruited by old subjects. Neural efficiency and the capacity to allocate more resources to decision-making differed between high and low performers in both age groups. Under low demand conditions, high performers executed the task utilizing fewer resources than low performers (indexed by the P3 amplitude). As task requirements increased, high-performing young and old subjects were able to appropriate additional resources to decision-making, whereas their low-performing counterparts allocated fewer resources. Higher task demands increased utilization of processing capacity for operations other than decision-making (e.g., sustained attention) that depend upon a shared pool of limited resources. As demands increased, all groups allocated additional resources to the process of sustaining attention (indexed by the posterior slow wave). Demands appeared to have exceeded capacity in low performers, leading to a reduction of resources available to the decision-making process, which likely contributed to a decline in performance.

  19. Low temperature aging mechanism identification and lithium deposition in a large format lithium iron phosphate battery for different charge profiles

    NASA Astrophysics Data System (ADS)

    Ouyang, Minggao; Chu, Zhengyu; Lu, Languang; Li, Jianqiu; Han, Xuebing; Feng, Xuning; Liu, Guangming

    2015-07-01

    Charging procedures at low temperatures severely shorten the cycle life of lithium ion batteries due to lithium deposition on the negative electrode. In this paper, cycle life tests are conducted to reveal the influence of the charging current rate and the cut-off voltage limit on the aging mechanisms of a large format LiFePO4 battery at a low temperature (-10 °C). The capacity degradation rates accelerate rapidly after the charging current reaches 0.25 C or the cut-off voltage reaches 3.55 V. Therefore the scheduled current and voltage during low-temperature charging should be reconsidered to avoid capacity degradation. Lithium deposition contributes to low-temperature aging mechanisms, as something needle-like which might be deposited lithium is observed on the surface of the negative electrode after disassembling the aged battery cell. To confirm our explanation, incremental capacity analysis (ICA) is performed to identify the characteristics of the lithium deposition induced battery aging mechanisms. Furthermore, the aging mechanism is quantified using a mechanistic model, whose parameters are estimated with the particle swarm optimization algorithm (PSO). The loss of reversible lithium originating from secondary SEI formation and dead lithium is confirmed as the cause of the aging.

  20. Microstructures, aging behaviour and mechanical properties in hydrogen and chloride media of backward extruded Mg-Y based biomaterials.

    PubMed

    Peng, Qiuming; Ma, Ning; Fang, Daqing; Li, Hui; Liu, Riping; Tian, Yongjun

    2013-01-01

    Microstructures, aging behaviour from room temperature to 300 °C and mechanical properties in different media of backward extruded (BE) Mg-Y based biomaterial have been investigated. The results reveal that BE-Mg-Y based alloy is mainly composed of polygon-shaped grains and fine precipitates. The results of aging response show that BE-Mg-Y based alloy exhibits remarkable age hardening behaviour when the aging temperature is 200 °C and higher. The high mechanical properties of aged BE-Mg-Y based alloy are mostly associated with fine microstructure, solid solution strengthening and the existence of homogeneous precipitates. The hydrogen embrittlement dependence on the aging time is confirmed in BE-Mg-Y based alloy. Additionally, the strength and elongation of BE-Mg-Y based alloy are significantly influenced by the ion concentration in media. These results offer some implications for understanding the reduced strength of Mg based implants in body environment. It is demonstrated that the temporary high mechanical strength in air of BE-Mg-Y based biomaterials is insufficient to evaluate the in vivo mechanical integrity.

  1. Mechanism of Capacitance Aging under DC Electric Fields in Multilayer Ceramic Capacitors with X7R Characteristics

    NASA Astrophysics Data System (ADS)

    Tsurumi, Takaaki; Shono, Motohiro; Kakemoto, Hirofumi; Wada, Satoshi; Saito, Kenji; Chazono, Hirokazu

    2005-09-01

    Capacitance aging under DC electric fields has been studied on multilayer ceramic capacitors (MLCCs) with X7R characteristics. The capacitance change with time was divided into two consecutive stages. The first stage was due to the nonlinear permittivity of dielectrics and it should not be involved in the aging phenomenon. The second stage depended on the MnO content, grain size and firing conditions of the dielectrics. The aging was markedly depressed above the Curie temperature. From the behavior of the second stage, it was concluded that the capacitance aging is caused by the 90° domain switching in BaTiO3 in the core. An equation that represents the aging behavior in the second stage was presented and the mechanism that explains the capacitance aging was proposed. The first stage was due to the nonlinear permittivity and the second stage was due to the domain switching, but the domain switching was also included in the first stage if the domain walls were moved by the first application of a DC field. The change in the aging behavior with the intensity of the DC field could be explained by separating capacitance change into that due to the nonlinear permittivity and that due to the domain switching according to the mechanism proposed in this study. Finally, a methodology for handling the capacitance aging under DC fields was proposed.

  2. Mechanism of Arachidonic Acid Accumulation during Aging in Mortierella alpina: A Large-Scale Label-Free Comparative Proteomics Study.

    PubMed

    Yu, Yadong; Li, Tao; Wu, Na; Ren, Lujing; Jiang, Ling; Ji, Xiaojun; Huang, He

    2016-11-30

    Arachidonic acid (ARA) is an important polyunsaturated fatty acid having various beneficial physiological effects on the human body. The aging of Mortierella alpina has long been known to significantly improve ARA yield, but the exact mechanism is still elusive. Herein, multiple approaches including large-scale label-free comparative proteomics were employed to systematically investigate the mechanism mentioned above. Upon ultrastructural observation, abnormal mitochondria were found to aggregate around shrunken lipid droplets. Proteomics analysis revealed a total of 171 proteins with significant alterations of expression during aging. Pathway analysis suggested that reactive oxygen species (ROS) were accumulated and stimulated the activation of the malate/pyruvate cycle and isocitrate dehydrogenase, which might provide additional NADPH for ARA synthesis. EC 4.2.1.17-hydratase might be a key player in ARA accumulation during aging. These findings provide a valuable resource for efforts to further improve the ARA content in the oil produced by aging M. alpina.

  3. Changes in mechanical properties of bone within the mandibular condyle with age.

    PubMed

    Huja, Sarandeep S; Rummel, Andrew M; Beck, Frank M

    2008-02-01

    The purpose of the study was to compare indentation modulus (IM) and hardness of condylar bone in young and adult dogs. In addition we desired to examine histologic sections for bone formation activity in the two groups. Mandibular condyles were obtained from adult (1- to 2-year-old) and young (approximately 5-m old) dogs. Two sections/condyle were obtained and one was processed for histomorphometry and the other for mechanical analyses. Indents were made on moist condylar trabecular bone to a depth of 500 nm at a loading rate of 10 nm/s using a custom-made hydration system to obtain IM and hardness. Histomorphometric analyses measured the bone volume/total volume (BV/TV%) and ratio of labeled to unlabeled bone within the condyle. Data were analyzed using a repeated-measures factorial analysis of variance and Tukey-Kramer method. Overall, the IM of the adult condyles (10.0+/-3.4 GPa, Mean+/-SD) were significantly (P<0.0001) higher than in young dogs (5.6+/-2.6 GPa). There was a greater bone mass in the young (60.2%) versus the adult condyles (42%). Also, significantly more labeled bone in the young (66.1%) condylar bone suggested higher bone forming activity than in adult condyles (27.5%). With age there is a change in mass and material properties in the trabecular bone of the mandibular condyle in dogs.

  4. Microscale Mechanism of Age Dependent Wetting Properties of Prickly Pear Cacti (Opuntia).

    PubMed

    Rykaczewski, Konrad; Jordan, Jacob S; Linder, Rubin; Woods, Erik T; Sun, Xiaoda; Kemme, Nicholas; Manning, Kenneth C; Cherry, Brian R; Yarger, Jeffery L; Majure, Lucas C

    2016-09-13

    Cacti thrive in xeric environments through specialized water storage and collection tactics such as a shallow, widespread root system that maximizes rainwater absorption and spines adapted for fog droplet collection. However, in many cacti, the epidermis, not the spines, dominates the exterior surface area. Yet, little attention has been dedicated to studying interactions of the cactus epidermis with water drops. Surprisingly, the epidermis of plants in the genus Opuntia, also known as prickly pear cacti, has water-repelling characteristics. In this work, we report that surface properties of cladodes of 25 taxa of Opuntia grown in an arid Sonoran climate switch from water-repelling to superwetting under water impact over the span of a single season. We show that the old cladode surfaces are not superhydrophilic, but have nearly vanishing receding contact angle. We study water drop interactions with, as well as nano/microscale topology and chemistry of, the new and old cladodes of two Opuntia species and use this information to uncover the microscopic mechanism underlying this phenomenon. We demonstrate that composition of extracted wax and its contact angle do not change significantly with time. Instead, we show that the reported age dependent wetting behavior primarily stems from pinning of the receding contact line along multilayer surface microcracks in the epicuticular wax that expose the underlying highly hydrophilic layers.

  5. Aging of whey protein films and the effect on mechanical and barrier properties.

    PubMed

    Anker, M; Stading, M; Hermansson, A M

    2001-02-01

    This work focuses on the aging of whey protein isolate (WPI) films plasticized with glycerol (G) and sorbitol (S). The films were cast from heated aqueous solutions at pH 7 and dried at 23 degrees C and 50% relative humidity (RH) for 16 h. They were stored in a climate room (23 degrees C, 50% RH) for 120 days, and the film properties were measured at regular intervals. The moisture content (MC) of the WPI/G films decreased from 22% (2 days) to 15% (45 days) and was thereafter constant at 15% (up to 120 days). This affected the mechanical properties and caused an increased stress at break (from 2.7 to 8.3 MPa), a decreased strain at break (from 33 to 4%), and an increased glass transition temperature (T(g)) (from -56 to -45 degrees C). The barrier properties were, however, unaffected, with constant water vapor permeability and a uniform film thickness. The MC of the WPI/S films was constant at approximately 9%, which gave no change in film properties.

  6. Degradation mechanism of LiCoO2/mesocarbon microbeads battery based on accelerated aging tests

    NASA Astrophysics Data System (ADS)

    Guan, Ting; Zuo, Pengjian; Sun, Shun; Du, Chunyu; Zhang, Lingling; Cui, Yingzhi; Yang, Lijie; Gao, Yunzhi; Yin, Geping; Wang, Fuping

    2014-12-01

    A series of LiCoO2/mesocarbon microbeads (MCMB) commercial cells cycled at different rates (0.6C, 1.2C, 1.5C, 1.8C, 2.4C and 3.0C) are disassembled and the capacity fade mechanism is proposed by analyzing the structure, morphology and electrochemical performance evolution at the capacity retention of 95%, 90%, 85%, 80%. The capacity deterioration of the commercial cell is mainly caused by the decay of the reversible capacity of LiCoO2 cathode, the irreversible loss of active lithium and the lithium remaining in anode. The proportions of effects by the above three factors are calculated accurately. The consumption of the active lithium leads to a cell imbalance between the anode and the cathode. The electrochemical test results indicate that the capacity fade of the active materials at the low rate is more obvious than that at the high rate. The influence of the active lithium is gradually increscent with the increasing rate. The rate of 1.5C is the optimal value to accelerate the aging of the full cell by comparing the testing results at different capacity retentions in the specific condition of low charge/discharge rate and shallow depth of discharge.

  7. Effect of Hygrothermal Aging on the Mechanical Properties of Fluorinated and Nonfluorinated Clay-Epoxy Nanocomposites

    PubMed Central

    Hamim, Salah U.; Singh, Raman P.

    2014-01-01

    Hydrophilic nature of epoxy polymers can lead to both reversible and irreversible/permanent changes in epoxy upon moisture absorption. The permanent changes leading to the degradation of mechanical properties due to combined effect of moisture and elevated temperature on EPON 862, Nanomer I.28E, and Somasif MAE clay-epoxy nanocomposites are investigated in this study. The extent of permanent degradation on fracture and flexural properties due to the hygrothermal aging is determined by drying the epoxy and their clay-epoxy nanocomposites after moisture absorption. Significant permanent damage is observed for fracture toughness and flexural modulus, while the extent of permanent damage is less significant for flexural strength. It is also observed that permanent degradation in Somasif MAE clay-epoxy nanocomposites is higher compared to Nanomer I.28E clay-epoxy nanocomposites. Fourier transform infrared (FTIR) spectroscopy revealed that both clays retained their original chemical structure after the absorption-desorption cycle without undergoing significant changes. Scanning electron microscopy (SEM) images of the fracture surfaces provide evidence that Somasif MAE clay particles offered very little resistance to crack propagation in case of redried specimens when compared to Nanomer I.28E counterpart. The reason for the observed higher extent of permanent degradation in Somasif MAE clay-epoxy system has been attributed to the weakening of the filler-matrix interface. PMID:27379285

  8. The Impact of Lymphatic Filariasis Mass Drug Administration Scaling Down on Soil-Transmitted Helminth Control in School-Age Children. Present Situation and Expected Impact from 2016 to 2020

    PubMed Central

    Montresor, Antonio; Mikhailov, Alexei; King, Jonathan

    2016-01-01

    Lymphatic filariasis (LF) and soil-transmitted-helminths (STH) are co-endemic in 58 countries which are mostly in Africa and Asia. Worldwide, 486 million school-age children are considered at risk of both diseases. In 2000, the World Health Organization (WHO) established the global programme to eliminate LF by 2020. Since then, the LF elimination programme has distributed ivermectin or diethylcarbamazine citrate (DEC) in combination with albendazole, thereby also treating STH. Consequently, many school-age children have been treated for STH through the LF programme. As treatment targets towards the 2020 LF elimination goal are achieved, many countries are implementing the transmission assessment survey (TAS) and, if the LF prevalence is estimated to be less than 1%, scaling down mass drug administration (MDA). We analysed the 2014 data on preventive chemotherapy (PC) reported from LF STH co-endemic countries and projected the year and location of TAS expected to be conducted between 2016 and 2020 to assess the impact of this scaling down on STH PC. Eighty percent of all co-endemic countries that have already stopped LF MDA nationally were able to establish STH PC through schools. It is estimated that 14% of the total number of children presently covered by the LF programme is at risk of not continuing to receive PC for STH. In order to achieve and maintain the WHO 2020 goal for STH control, there is an urgent need to establish and reinforce school-based deworming programmes in countries scaling-down national LF elimination programmes. PMID:27992424

  9. The Impact of Lymphatic Filariasis Mass Drug Administration Scaling Down on Soil-Transmitted Helminth Control in School-Age Children. Present Situation and Expected Impact from 2016 to 2020.

    PubMed

    Mupfasoni, Denise; Montresor, Antonio; Mikhailov, Alexei; King, Jonathan

    2016-12-01

    Lymphatic filariasis (LF) and soil-transmitted-helminths (STH) are co-endemic in 58 countries which are mostly in Africa and Asia. Worldwide, 486 million school-age children are considered at risk of both diseases. In 2000, the World Health Organization (WHO) established the global programme to eliminate LF by 2020. Since then, the LF elimination programme has distributed ivermectin or diethylcarbamazine citrate (DEC) in combination with albendazole, thereby also treating STH. Consequently, many school-age children have been treated for STH through the LF programme. As treatment targets towards the 2020 LF elimination goal are achieved, many countries are implementing the transmission assessment survey (TAS) and, if the LF prevalence is estimated to be less than 1%, scaling down mass drug administration (MDA). We analysed the 2014 data on preventive chemotherapy (PC) reported from LF STH co-endemic countries and projected the year and location of TAS expected to be conducted between 2016 and 2020 to assess the impact of this scaling down on STH PC. Eighty percent of all co-endemic countries that have already stopped LF MDA nationally were able to establish STH PC through schools. It is estimated that 14% of the total number of children presently covered by the LF programme is at risk of not continuing to receive PC for STH. In order to achieve and maintain the WHO 2020 goal for STH control, there is an urgent need to establish and reinforce school-based deworming programmes in countries scaling-down national LF elimination programmes.

  10. Alzheimer's Disease as Subcellular `Cancer' --- The Scale-Invariant Principles Underlying the Mechanisms of Aging ---

    NASA Astrophysics Data System (ADS)

    Murase, M.

    1996-01-01

    with self-organization, has been thought to underlie `creative' aspects of biological phenomena such as the origin of life, adaptive evolution of viruses, immune recognition and brain function. It therefore must be surprising to find that the same principles will also underlie `non-creative' aspects, for example, the development of cancer and the aging of complex organisms. Although self-organization has extensively been studied in nonliving things such as chemical reactions and laser physics, it is undoubtedly true that the similar sources of the order are available to living things at different levels and scales. Several paradigm shifts are, however, required to realize how the general principles of natural selection can be extensible to non-DNA molecules which do not possess the intrinsic nature of self-reproduction. One of them is, from the traditional, genetic inheritance view that DNA (or RNA) molecules are the ultimate unit of heritable variations and natural selection at any organization level, to the epigenetic (nongenetic) inheritance view that any non-DNA molecule can be the target of heritable variations and molecular selection to accumulate in certain biochemical environment. Because they are all enriched with a β-sheet content, ready to mostly interact with one another, different denatured proteins like β-amyloid, PHF and prions can individually undergo self-templating or self-aggregating processes out of gene control. Other paradigm shifts requisite for a break-through in the etiology of neurodegenerative disorders will be discussed. As it is based on the scale-invariant principles, the present theory also predicts plausible mechanisms underlying quite different classes of disorders such as amyotrophic lateral sclerosis (ALS), atherosclerosis, senile cataract and many other symptoms of aging. The present theory, thus, provides the consistent and comprehensive account to the origin of aging by means of natural selection and self-organization.

  11. Outside the Expected.

    ERIC Educational Resources Information Center

    Dienstfrey, Harris

    1968-01-01

    In examining the findings of "Pygmalion in the Classroom," an experimental study of the positive effects of favorable teacher expectations on the intellectual development of disadvantaged elementary school students, this review speculates about why the experimental students, whom the teachers expected to improve, and the control…

  12. Reflections on Expectations

    ERIC Educational Resources Information Center

    Santini, Joseph

    2014-01-01

    This article describes a teachers reflections on the matter of student expectations. Santini begins with a common understanding of the "Pygmalion effect" from research projects conducted in earlier years that intimated "people's expectations could influence other people in the world around them." In the world of deaf…

  13. A Superintendent's High Expectations

    ERIC Educational Resources Information Center

    Pascopella, Angela

    2009-01-01

    This article profiles Wanda Bamberg, superintendent of the Aldine (Texas) Independent School District. Bamberg is used to high expectations regardless of the circumstances. She is a firecracker of sorts who talks much and expects much from her staff members, teachers, and students, who are mostly at-risk, Black and Hispanic, and economically…

  14. An Unexpected Expected Value.

    ERIC Educational Resources Information Center

    Schwartzman, Steven

    1993-01-01

    Discusses the surprising result that the expected number of marbles of one color drawn from a set of marbles of two colors after two draws without replacement is the same as the expected number of that color marble after two draws with replacement. Presents mathematical models to help explain this phenomenon. (MDH)

  15. Women's Retirement Expectations: How Stable Are They?

    PubMed Central

    Hardy, Melissa A.

    2009-01-01

    Objective Using the National Longitudinal Survey of Mature Women, we examine between- and within-person differences in expected retirement age as a key element of the retirement planning process. The expectation typologies of 1,626 women born between 1923 and 1937 were classified jointly on the basis of specificity and consistency. Methods Latent class analysis was used to determine retirement expectation patterns over a 7-year span. Multinomial logistic regression analyses were employed to estimate the effects of demographic and status characteristics on the likelihood of reporting 4 distinct longitudinal patterns of retirement expectations. Results Substantial heterogeneity in reports of expected retirement age between and within individuals over the 7-year span was found. Demographic and status characteristics, specifically age, race, marital status, job tenure, and recent job change, sorted respondents into different retirement expectation patterns. Conclusions The frequent within-person fluctuations and substantial between-person heterogeneity in retirement expectations indicate uncertainty and variability in both expectations and process of expectation formation. Variability in respondents' reports suggests that studying retirement expectations at multiple time points better captures the dynamics of preretirement planning. PMID:19176483

  16. When stem cells grow old: phenotypes and mechanisms of stem cell aging

    PubMed Central

    Schultz, Michael B.; Sinclair, David A.

    2016-01-01

    All multicellular organisms undergo a decline in tissue and organ function as they age. An attractive theory is that a loss in stem cell number and/or activity over time causes this decline. In accordance with this theory, aging phenotypes have been described for stem cells of multiple tissues, including those of the hematopoietic system, intestine, muscle, brain, skin and germline. Here, we discuss recent advances in our understanding of why adult stem cells age and how this aging impacts diseases and lifespan. With this increased understanding, it is feasible to design and test interventions that delay stem cell aging and improve both health and lifespan. PMID:26732838

  17. Molecular Mechanism for Age-Related Memory Loss: The Histone-Binding Protein RbAp48

    PubMed Central

    Pavlopoulos, Elias; Jones, Sidonie; Kosmidis, Stylianos; Close, Maggie; Kim, Carla; Kovalerchik, Olga; Small, Scott A.; Kandel, Eric R.

    2016-01-01

    To distinguish age-related memory loss more explicitly from Alzheimer’s disease (AD), we have explored its molecular underpinning in the dentate gyrus (DG), a subregion of the hippocampal formation thought to be targeted by aging. We carried out a gene expression study in human postmortem tissue harvested from both DG and entorhinal cortex (EC), a neighboring subregion unaffected by aging and known to be the site of onset of AD. Using expression in the EC for normalization, we identified 17 genes that manifested reliable age-related changes in the DG. The most significant change was an age-related decline in RbAp48, a histone-binding protein that modifies histone acetylation. To test whether the RbAp48 decline could be responsible for age-related memory loss, we turned to mice and found that, consistent with humans, RbAp48 was less abundant in the DG of old than in young mice. We next generated a transgenic mouse that expressed a dominant-negative inhibitor of RbAp48 in the adult forebrain. Inhibition of RbAp48 in young mice caused hippocampus-dependent memory deficits similar to those associated with aging, as measured by novel object recognition and Morris water maze tests. Functional magnetic resonance imaging studies showed that within the hippocampal formation, dysfunction was selectively observed in the DG, and this corresponded to a regionally selective decrease in histone acetylation. Up-regulation of RbAp48 in the DG of aged wild-type mice ameliorated age-related hippocampus-based memory loss and age-related abnormalities in histone acetylation. Together, these findings show that the DG is a hippocampal subregion targeted by aging, and identify molecular mechanisms of cognitive aging that could serve as valid targets for therapeutic intervention. PMID:23986399

  18. The Possible Mechanism of Advanced Glycation End Products (AGEs) for Alzheimer’s Disease

    PubMed Central

    Ko, Shun-Yao; Ko, Hshin-An; Chu, Kuo-Hsiung; Shieh, Tzong-Ming; Chi, Tzong-Cherng; Chen, Hong-I; Chang, Weng-Cheng; Chang, Shu-Shing

    2015-01-01

    Amyloid precursor protein (APP) has been modified by β and γ-secretase that cause amyloid deposits (plaques) in neuronal cells. Glyceraldhyde-derived AGEs has been identified as a major source of neurotoxicity in Alzheimer’s disease (AD). In a previous study, we demonstrated that glyceraldehyde-derived AGEs increase APP and Aβ via ROS. Furthermore, the combination of AGEs and Aβ has been shown to enhance neurotoxicity. In mice, APP expression is increased by tail vein injection of AGEs. This evidence suggests a correlation between AGEs and the development of AD. However, the role played by AGEs in the pathogenesis of AD remains unclear. In this report, we demonstrate that AGEs up-regulate APP processing protein (BACE and PS1) and Sirt1 expression via ROS, but do not affect the expression of downstream antioxidant genes HO-1 and NQO-1. Moreover, we found that AGEs increase GRP78 expression and enhance the cell death-related pathway p53, bcl-2/bax ratio, caspase 3. These results indicate that AGEs impair the neuroprotective effects of Sirt1 and lead to neuronal cell death via ER stress. Our findings suggest that AGEs increase ROS production, which stimulates downstream pathways related to APP processing, Aβ production, Sirt1, and GRP78, resulting in the up-regulation of cell death related pathway. This in-turn enhances neuronal cell death, which leads to the development of AD. PMID:26587989

  19. Effect of a water-maze procedure on the redox mechanisms in brain parts of aged rats

    PubMed Central

    Krivova, Natalia A.; Zaeva, Olga B.; Grigorieva, Valery A.

    2015-01-01

    The Morris water maze (MWM) is a tool for assessment of age-related modulations spatial learning and memory in laboratory rats. In our work was investigated the age-related decline of MWM performance in 11-month-old rats and the effect exerted by training in the MWM on the redox mechanisms in rat brain parts. Young adult (3-month-old) and aged (11-month-old) male rats were trained in the MWM. Intact animals of the corresponding age were used as the reference groups. The level of pro- and antioxidant capacity in brain tissue homogenates was assessed using the chemiluminescence method. A reduced performance in the MWM test was found in 11-month-old rats: at the first day of training they showed only 30% of successful MWM trials. However, at the last training day the percentage of successful trials was equal for young adult and aged animals. This indicates that the aged 11-month-old rats can successfully learn in MWM. Therewith, the MWM spatial learning procedure itself produces changes in different processes of redox homeostasis in 11-month-old and 3-month-old rats as compared to intact animals. Young adult rats showed a decrease in prooxidant capacity in all brain parts, while 11-month-old rats demonstrated an increase in antioxidant capacity in the olfactory bulb, pons + medulla oblongata and frontal lobe cortex. Hence, the MWM procedure activates the mechanisms that restrict the oxidative stress in brain parts. The obtained results may be an argument for further development of the animal training procedures aimed to activate the mechanisms that can prevent the age-related deterioration of performance in the learning test. This may be useful not only for the development of training procedures applicable to human patients with age-related cognitive impairments, but also for their rehabilitation. PMID:25814952

  20. Clinical outcomes and mechanism of action for rheopheresis treatment of age-related macular degeneration (AMD).

    PubMed

    Pulido, Jose; Sanders, Donald; Winters, Jeffrey L; Klingel, Reinhard

    2005-10-01

    The primary goals are to provide a comprehensive explanation of the potential role of therapeutic apheresis in the treatment of Age-Related Macular Degeneration (AMD). Initial clinical results with this technique and a summary of current literature that addresses the mechanism of action for the Rheopheresis approach are presented. Rheopheresis has been found to be a safe and effective application of double filtration plasmapheresis (DFPP) for extracorporeal hemorheotherapy. In this report, it is proposed that Rheopheresis results in an immediate decrease in the proportion of high molecular weight proteins that could combine with the TIMP-3 fibulin complex allowing for the barely functioning retinal pigment epithelial (RPE) cells to function better and diminish the release of vascular endothelial growth factor (VEGF). Interim results from the randomized, double-masked MIRA-1 clinical trial include (1) improved vision restoration; 28.0% of Treated Primary Eyes increased by > or = 2 lines of best corrected visual acuity (BCVA) compared to 18.2% of Placebo Eyes; (2) a decline in progressive vision loss; 0.0% of treated eyes progressing to worse than 20/200 vision over the 12-month study compared to 18.2% of Placebo Eyes; (3) 57.9% of Treatment Eyes obtained improvement in their BCVA to 20/40 or better (driver's license qualification), compared to only 14.3% of Placebo Eyes 12-month post-treatment. Rheopheresis treatment shows strong promise as a viable clinical option for patients suffering from the dry form of AMD in terms of minimizing vision loss, vision restoration, and overall quality of life factors. Expanded clinical outcomes from the ongoing MIRA-1 clinical study will be valuable in the assessment of this new clinical tool for ophthalmic applications.

  1. The effect of aging on the mechanical behaviour of cuticle in the locust Schistocerca gregaria.

    PubMed

    Parle, Eoin; Taylor, David

    2017-02-08

    Despite some previous work on the morphology and mechanical properties of parts of the insect exoskeleton, there is very little known about how these properties change over time during the life of the insect. We examined the hind tibia of the adult desert locust (Schistocerca gregaria) as a function of time up to 63 days following the final moult, a much longer period that previously studied. We identified an initial growth phase, lasting on average 21 days, in which leg thickness increased rapidly (averaging 1.8μm/day) by endocuticle deposition, and a subsequent mature phase in which the deposition rate slowed to 0.3μm/day. Cantilever bending tests revealed that Young's modulus and failure stress also increased rapidly during the growth phase, but remained almost constant during the mature phase, with average values of 8.3GPa (± 2.3GPa) and 175MPa (±31.5MPa) respectively, which are considerably higher than previously measured for fresh insect cuticle. Biomechanical analysis showed that the failure mode also changed, from local buckling of the tubular leg during the growth phase to failure at the material's ultimate strength in the mature phase. Over time, the ratio of radius/thickness of the leg decreased, passing through the estimated optimal value which would confer the best strength/weight ratio. This is the first ever biomechanical study to track changes in arthropod cuticle over a large part of adult life of the animal, and has revealed some unexpected and complex changes which may shed light on how arthropods regulate their load-bearing skeletal parts during aging.

  2. Extracellular Matrix Disarray as A Mechanism for Greater Abdominal vs. Thoracic Aortic Stiffness with Aging in Primates

    PubMed Central

    Zhang, Jie; Zhao, Xin; Vatner, Dorothy E; McNulty, Tara; Bishop, Sanford; Sun, Zhe; Shen, You-Tang; Chen, Li; Meininger, Gerald A; Vatner, Stephen F

    2016-01-01

    Objective Increased vascular stiffness is central to the pathophysiology of aging, hypertension, diabetes and atherosclerosis. However, relatively few studies have examined vascular stiffness in both the thoracic and abdominal aorta with aging, despite major differences in anatomy, embryological origin and relation to aortic aneurysm. Approach and Results The two other unique features of this study were 1) to study young (9±1 years) and old (26±1 years) male monkeys, and 2) to study direct and continuous measurements of aortic pressure and thoracic and abdominal aortic diameters in conscious monkeys. As expected, aortic stiffness, β, was increased p<0.05, 2–3 fold, in old vs. young thoracic aorta, and augmented further with superimposition of acute hypertension with phenylephrine. Surprisingly, stiffness was not greater in old thoracic aorta than young abdominal aorta. These results can be explained in part by the collagen/elastin ratio, but more importantly, by disarray of collagen and elastin, which correlated best with vascular stiffness. However, vascular smooth muscle cell stiffness, was not different in thoracic vs. abdominal aorta in either young or old monkeys. Conclusions Thus, aortic stiffness increases with aging as expected, but the most severe increases in aortic stiffness observed in the abdominal aorta is novel, where values in young monkeys equaled, or even exceeded, values of thoracic aortic stiffness in old monkeys. These results can be explained by alterations in collagen/elastin ratio, but even more importantly by collagen and elastin disarray. PMID:26891739

  3. Mechanical properties of 8Cr-2WVTa steel aged for 30 000 h

    NASA Astrophysics Data System (ADS)

    Tamura, M.; Shinozuka, K.; Esaka, H.; Sugimoto, S.; Ishizawa, K.; Masamura, K.

    2000-12-01

    A mill production plate of a reduced activation ferritic steel was thermally aged for up to 30 000 h at 400-650°C. Charpy impact tests, creep rupture tests and hardness tests were conducted. Both Vickers hardness number and creep strength decrease with aging at 650°C. The ductile-brittle transition temperature (DBTT) increases with both aging time and aging temperature. However, the DBTT does not exceed +20°C even after aging at 650°C for 30 000 h. Extracted residues and extraction replicas were analyzed metallurgically. The increase in DBTT is related mainly to the precipitation of Laves phase on the prior austenite grain boundaries. The rather low DBTT after aging is caused by the fine prior austenitic grain size.

  4. Dissecting mechanisms of brain aging by studying the intrinsic excitability of neurons

    PubMed Central

    Rizzo, Valerio; Richman, Jeffrey; Puthanveettil, Sathyanarayanan V.

    2015-01-01

    Several studies using vertebrate and invertebrate animal models have shown aging associated changes in brain function. Importantly, changes in soma size, loss or regression of dendrites and dendritic spines and alterations in the expression of neurotransmitter receptors in specific neurons were described. Despite this understanding, how aging impacts intrinsic properties of individual neurons or circuits that govern a defined behavior is yet to be determined. Here we discuss current understanding of specific electrophysiological changes in individual neurons and circuits during aging. PMID:25610394

  5. Reward expectations in honeybees.

    PubMed

    Gil, Mariana

    2010-03-01

    The study of expectations of reward helps to understand rules controlling goal-directed behavior as well as decision making and planning. I shall review a series of recent studies focusing on how the food gathering behavior of honeybees depends upon reward expectations. These studies document that free-flying honeybees develop long-term expectations of reward and use them to regulate their investment of energy/time during foraging. Also, they present a laboratory procedure suitable for analysis of neural substrates of reward expectations in the honeybee brain. I discuss these findings in the context of individual and collective foraging, on the one hand, and neurobiology of learning and memory of reward.

  6. Health expectancy indicators.

    PubMed Central

    Robine, J. M.; Romieu, I.; Cambois, E.

    1999-01-01

    An outline is presented of progress in the development of health expectancy indicators, which are growing in importance as a means of assessing the health status of populations and determining public health priorities. PMID:10083720

  7. Normative shifts of cortical mechanisms of encoding contribute to adult age differences in visual-spatial working memory.

    PubMed

    Störmer, Viola S; Li, Shu-Chen; Heekeren, Hauke R; Lindenberger, Ulman

    2013-06-01

    The capacity of visual-spatial working memory (WM) declines from early to late adulthood. Recent attempts at identifying neural correlates of WM capacity decline have focused on the maintenance phase of WM. Here, we investigate neural mechanisms during the encoding phase as another potential mechanism contributing to adult age differences in WM capacity. We used electroencephalography to track neural activity during encoding and maintenance on a millisecond timescale in 35 younger and 35 older adults performing a visual-spatial WM task. As predicted, we observed pronounced age differences in ERP indicators of WM encoding: Younger adults showed attentional selection during item encoding (N2pc component), but this selection mechanism was greatly attenuated in older adults. Conversely, older adults showed more pronounced signs of early perceptual stimulus processing (N1 component) than younger adults. The amplitude modulation of the N1 component predicted WM capacity in older adults, whereas the attentional amplitude modulation of the N2pc component predicted WM capacity in younger adults. Our findings suggest that adult age differences in mechanisms of WM encoding contribute to adult age differences in limits of visual-spatial WM capacity.

  8. Effects of Aging Treatment on Mechanical Properties of Sn-58Bi Epoxy Solder on ENEPIG-Surface-Finished PCB

    NASA Astrophysics Data System (ADS)

    Kim, Jungsoo; Myung, Woo-Ram; Jung, Seung-Boo

    2016-11-01

    The mechanical properties of Sn-58Bi epoxy solder were evaluated by low-speed shear testing as functions of aging time and temperature. To determine the effects of epoxy, the interfacial reaction and mechanical properties of both Sn-58Bi and Sn-58Bi epoxy solder were investigated after aging treatment. The chemical composition and growth kinetics of the intermetallic compound (IMC) formed at the interface between Sn-58Bi solder and electroless nickel electroless palladium immersion gold (ENEPIG) surface finish were analyzed. Sn-58Bi solder paste was applied by stencil-printing on flame retardant-4 substrate, then reflowed. Reflowed samples were aged at 85°C, 95°C, 105°C, and 115°C for up to 1000 h. (Ni,Pd)3Sn4 IMC formed between Sn-58Bi solder and ENEPIG surface finish after reflow. Ni3Sn4 and Ni3P IMCs formed at the interface between (Ni,Pd)3Sn4 IMC and ENEPIG surface finish after aging at 115°C for 300 h. The overall IMC growth rate of Sn-58Bi solder joint was higher than that of Sn-58Bi epoxy solder joint during aging. The shear strength of Sn-58Bi epoxy solder was about 2.4 times higher than that of Sn-58Bi solder due to the blocking effect of epoxy, and the shear strength decreased with increasing aging time.

  9. Obesity and related consequences to ageing.

    PubMed

    Jura, Magdalena; Kozak, Leslie P

    2016-02-01

    Obesity has become a major public health problem. Given the current increase in life expectancy, the prevalence of obesity also raises steadily among older age groups. The increase in life expectancy is often accompanied with additional years of susceptibility to chronic ill health associated with obesity in the elderly. Both obesity and ageing are conditions leading to serious health problems and increased risk for disease and death. Ageing is associated with an increase in abdominal obesity, a major contributor to insulin resistance and the metabolic syndrome. Obesity in the elderly is thus a serious concern and comprehension of the key mechanisms of ageing and age-related diseases has become a necessary matter. Here, we aimed to identify similarities underlying mechanisms related to both obesity and ageing. We bring together evidence that age-related changes in body fat distribution and metabolism might be key factors of a vicious cycle that can accelerate the ageing process and onset of age-related diseases.

  10. Interaction of age and mechanical stability on bone defect healing: an early transcriptional analysis of fracture hematoma in rat.

    PubMed

    Ode, Andrea; Duda, Georg N; Geissler, Sven; Pauly, Stephan; Ode, Jan-Erik; Perka, Carsten; Strube, Patrick

    2014-01-01

    Among other stressors, age and mechanical constraints significantly influence regeneration cascades in bone healing. Here, our aim was to identify genes and, through their functional annotation, related biological processes that are influenced by an interaction between the effects of mechanical fixation stability and age. Therefore, at day three post-osteotomy, chip-based whole-genome gene expression analyses of fracture hematoma tissue were performed for four groups of Sprague-Dawley rats with a 1.5-mm osteotomy gap in the femora with varying age (12 vs. 52 weeks - biologically challenging) and external fixator stiffness (mechanically challenging). From 31099 analysed genes, 1103 genes were differentially expressed between the six possible combinations of the four groups and from those 144 genes were identified as statistically significantly influenced by the interaction between age and fixation stability. Functional annotation of these differentially expressed genes revealed an association with extracellular space, cell migration or vasculature development. The chip-based whole-genome gene expression data was validated by q-RT-PCR at days three and seven post-osteotomy for MMP-9 and MMP-13, members of the mechanosensitive matrix metalloproteinase family and key players in cell migration and angiogenesis. Furthermore, we observed an interaction of age and mechanical stimuli in vitro on cell migration of mesenchymal stromal cells. These cells are a subpopulation of the fracture hematoma and are known to be key players in bone regeneration. In summary, these data correspond to and might explain our previously described biomechanical healing outcome after six weeks in response to fixation stiffness variation. In conclusion, our data highlight the importance of analysing the influence of risk factors of fracture healing (e.g. advanced age, suboptimal fixator stability) in combination rather than alone.

  11. Induction of oxidative stress causes functional alterations in mouse urothelium via a TRPM8-mediated mechanism: implications for aging.

    PubMed

    Nocchi, Linda; Daly, Donna M; Chapple, Christopher; Grundy, David

    2014-06-01

    The incidence of bladder conditions such as overactive bladder syndrome and its associated urinary incontinence is highly prevalent in the elderly. However, the mechanisms underlying these disorders are unclear. Studies suggest that the urothelium forms a 'sensory network' with the underlying innervation, alterations in which, could compromise bladder function. As the accumulation of reactive oxygen species can cause functional alterations with age, the aim of this study was to investigate whether oxidative stress alters urothelial sensory signalling and whether the mechanism underlying the effect of oxidative stress on the urothelium plays a role in aging. Five-month-old(young) and 24-month-old (aged) mice were used. H2O2 , used to induce oxidative stress, resulted in an increase in bladder afferent nerve activity and urothelial intracellular calcium in preparations from young mice. These functional changes were concurrent with upregulation of TRPM8 in the urothelium. Moreover, application of a TRPM8 antagonist significantly attenuated the H2O2 -induced calcium responses. Interestingly, an upregulation of TRPM8 was also found in the urothelium from aged mice, where high oxidative stress levels were observed, together with a greater calcium response to the TRPM8 agonist WS12. Furthermore, these calcium responses were attenuated by pretreatment with the antioxidant N-acetyl-cysteine. This study shows that oxidative stress affects urothelial function involving a TRPM8-mediated mechanism and these effects may have important implications for aging. These data provide an insight into the possible mechanisms by which oxidative stress causes physiological alterations in the bladder, which may also occur in other organs susceptible to aging.

  12. NPY/neuropeptide Y enhances autophagy in the hypothalamus: a mechanism to delay aging?

    PubMed

    Aveleira, Célia A; Botelho, Mariana; Cavadas, Cláudia

    2015-01-01

    Aging was recently described as a life event programmed by the hypothalamus, a key brain region that is crucial for the neuroendocrine interaction between the central nervous system and the periphery. Autophagy impairment is a hallmark of aging, contributing to the aging phenotype and to the aggravation of age-related diseases. Since hypothalamic autophagy decreases with age, strategies to promote autophagy in the hypothalamus may be relevant for control of the aging process. NPY (neuropeptide Y) is an endogenous neuropeptide mainly produced by the hypothalamus. We recently reported, for the first time, that NPY stimulates autophagy in rodent hypothalamus and mediates caloric restriction-induced autophagy in hypothalamic neurons. Moreover, we observed that NPY acts through NPY1R (neuropeptide Y receptor Y1) or NPY5R activation involving a concerted action of different signaling pathways. Since both hypothalamic autophagy and NPY levels decrease with age, modulation of NPY levels could provide new putative therapeutic tools to ameliorate age-related deteriorations and extend longevity.

  13. Effect of Aging Treatment on the Damping Capacity and Mechanical Properties of Mg-6Al-1Zn Alloy

    PubMed Central

    El-Morsy, Abdel-Wahab; Farahat, Ahmed I. Z.

    2015-01-01

    The damping capacity and mechanical properties of Mg-6Al-1Zn alloy after heat treatment were investigated. The damping characteristics of un-heat-treated, solution treated, and aged Mg-6Al-1Zn specimens were determined by measuring the damping ratio and the logarithmic decrement of free vibrations of a bending beam clamped at one side. The microstructural evaluations confirmed that the β-Mg17Al12 phase was reprecipitated after aging and increased with an increase in aging time. The peak level of damping ratio and logarithmic decrement was obtained after 34 hr of aging time, over which the damping capacity declined according to increasing amount of strong pining points. PMID:25918738

  14. Structures and mechanical properties of ECAP processed 7075 AI alloy upon natural aging and T651 treatment.

    SciTech Connect

    Zhao, Y.; Liao, Xiaozhou; Valiev, R. Z.; Zhu, Y. T.

    2004-01-01

    Equal-channel angular pressing (ECAP) processed ultrafine grained (UFG) and coarse grained (CG) 7075 Al alloys were treated by natural aging and T651 temper (annealed at 120 C for 48 h in Ar atmosphere), respectively. Mechanical tests showed that for the UFG sample, the natural aging resulted in the highest strength (the ultimate tensile strength is 720 MPa). In contrast, for the CG sample, the T651 treatment resulted in the higher strength (the ultimate strength is 590 MPa) than the natural aging (530 MPa). Microstructural analyses indicated that the enhanced strength of the T651 treated CG sample was mainly caused by high densities of G-P zones and metastable {eta}{prime} precipitate. The enhanced strength of the naturally aged UFG sample was mainly caused by the high densities of G-P zones and dislocations. Upon T65 1 treatment, the dislocation density of the UFG sample deceased significantly, overcompensating the precipitation strengthening.

  15. A microscopic and macroscopic study of aging collagen on its molecular structure, mechanical properties, and cellular response.

    PubMed

    Wilson, Samantha L; Guilbert, Marie; Sulé-Suso, Josep; Torbet, Jim; Jeannesson, Pierre; Sockalingum, Ganesh D; Yang, Ying

    2014-01-01

    During aging, collagen structure changes, detrimentally affecting tissues' biophysical and biomechanical properties due to an accumulation of advanced glycation end-products (AGEs). In this investigation, we conducted a parallel study of microscopic and macroscopic properties of different-aged collagens from newborn to 2-yr-old rats, to examine the effect of aging on fibrillogenesis, mechanical and contractile properties of reconstituted hydrogels from these collagens seeded with or without fibroblasts. In addition to fibrillogenesis of collagen under the conventional conditions, some fibrillogenesis was conducted alongside a 12-T magnetic field, and gelation rate and AGE content were measured. A nondestructive indentation technique and optical coherence tomography were used to determine the elastic modulus and dimensional changes, respectively. It was revealed that in comparison to younger specimens, older collagens exhibited higher viscosity, faster gelation rates, and a higher AGE-specific fluorescence. Exceptionally, only young collagens formed highly aligned fibrils under magnetic fields. The youngest collagen demonstrated a higher elastic modulus and contraction in comparison to the older collagen. We conclude that aging changes collagen monomer structure, which considerably affects the fibrillogenesis process, the architecture of the resulting collagen fibers and the global network, and the macroscopic properties of the formed constructs.

  16. A Study on the Synergistic Effect of ECAP and Aging Treatment on the Mechanical Properties of AA6082

    NASA Astrophysics Data System (ADS)

    Baig, Muneer; El-Danaf, Ehab; Mohammed, Jabair Ali

    2016-12-01

    In this study, the synergistic effect of equal-channel angular pressing (ECAP) and aging temperature-time on the mechanical properties of AA6082 has been investigated. The treatments include post-ECAP artificial aging and dynamic aging which was achieved by ECAP processing at 140 °C to 1 pass. It was observed that both routes were effective in enhancing the strength of the alloy. The Vickers microhardness measurements were recorded at three different aging temperatures with varying time intervals. The hardness values of the ECAP-processed alloy to 1 and 2 passes, followed by artificial peak aging was found to be 112.3 and 130 Hv, respectively. Compared to the yield strength of solution-treated alloy, the synergistic effect of ECAP processing to 1 pass and 2 passes followed by artificial aging has resulted in an increase in the yield strength of the alloy by 140 and 183%, respectively. The dynamic aging resulted in an overall increase in the yield strength of the alloy by 177%. The correlation from the modified Johnson-Cook model was close to the observed experimental responses.

  17. Recurrent Sleep Fragmentation Induces Insulin and Neuroprotective Mechanisms in Middle-Aged Flies

    PubMed Central

    Williams, Michael J.; Perland, Emelie; Eriksson, Mikaela M.; Carlsson, Josef; Erlandsson, Daniel; Laan, Loora; Mahebali, Tabusi; Potter, Ella; Frediksson, Robert; Benedict, Christian; Schiöth, Helgi B.

    2016-01-01

    Lack of quality sleep increases central nervous system oxidative stress and impairs removal of neurotoxic soluble metabolites from brain parenchyma. During aging poor sleep quality, caused by sleep fragmentation, increases central nervous system cellular stress. Currently, it is not known how organisms offset age-related cytotoxic metabolite increases in order to safeguard neuronal survival. Furthermore, it is not understood how age and sleep fragmentation interact to affect oxidative stress protection pathways. We demonstrate sleep fragmentation increases systems that protect against oxidative damage and neuroprotective endoplasmic reticulum molecular chaperones, as well as neuronal insulin and dopaminergic expression in middle-aged Drosophila males. Interestingly, even after sleep recovery the expression of these genes was still upregulated in middle-aged flies. Finally, sleep fragmentation generates higher levels of reactive oxygen species (ROS) in middle-aged flies and after sleep recovery these levels remain significantly higher than in young flies. The fact that neuroprotective pathways remain upregulated in middle-aged flies beyond sleep fragmentation suggests it might represent a strong stressor for the brain during later life. PMID:27531979

  18. Peripheral mechanisms of thermoregulatory control of skin blood flow in aged humans

    PubMed Central

    Kenney, W. Larry

    2010-01-01

    Human skin blood flow is controlled via dual innervation from the sympathetic nervous system. Reflex cutaneous vasoconstriction and vasodilation are both impaired with primary aging, rendering the aged more vulnerable to hypothermia and cardiovascular complications from heat-related illness. Age-related alterations in the thermoregulatory control of skin blood flow occur at multiple points along the efferent arm of the reflex, including 1) diminished sympathetic outflow, 2) altered presynaptic neurotransmitter synthesis, 3) reduced vascular responsiveness, and 4) impairments in downstream (endothelial and vascular smooth muscle) second-messenger signaling. This mechanistic review highlights some of the recent findings in the area of aging and the thermoregulatory control of skin blood flow. PMID:20413421

  19. Age-related changes in pumping mechanical behavior of rat ventricle in terms of systolic elastance and resistance.

    PubMed

    Chang, K C; Peng, Y I; Dai, S H; Tseng, Y Z

    2000-09-01

    Both the maximal systolic elastance (Emax) and the theoretical maximal flow (Qmax) can quantify the systolic mechanical behavior of the ventricular pump. Physically, Emax can reflect the intrinsic contractility of the myocardium as an intact heart. The quantity in (Qmax is inversely related to the internal resistance of the left ventricle. How great the effects of age are on these Emax and Qmax has never been examined, however. This study was to determine the ventricular pumping mechanics in terms of the systolic elastance and resistance in male Fischer rats at 6, 12, 18, and 24 months of age. We measured left ventricular (LV) pressure and ascending aortic flow waves using a high-fidelity pressure sensor and an electromagnetic flow probe, respectively. Those two parameters that characterize the systolic pumping mechanics of the left ventricle are obtained by making use of an elastance-resistance model. The basic hemodynamic condition in those animals with different ages is characterized by (i) no significant change in cardiac output and (ii) a decrease in basal heart rate, LV end-systolic pressure, as well as effective arterial volume elastance. Changes that take place in the left ventricle with age include a decline in Emax and an increase in Qmax especially at 24 months. These results demonstrate that the impaired intrinsic contractility of an aging heart may be compensated to some extent by the diminished ventricular internal resistance. Such compensation in aging rats may maintain normal blood flow essential for the metabolic needs of tissues and/or organs before heart dysfunction and failure occur.

  20. Influence of Thermal Aging on the Microstructure and Mechanical Behavior of Dual Phase Precipitation Hardened Powder Metallurgy Stainless Steels

    NASA Astrophysics Data System (ADS)

    Stewart, Jennifer

    2011-12-01

    Increasing demand for high strength powder metallurgy (PM) steels has resulted in the development of dual phase PM steels. In this work, the effects of thermal aging on the microstructure and mechanical behavior of dual phase precipitation hardened powder metallurgy (PM) stainless steels of varying ferrite-martensite content were examined. Quantitative analyses of the inherent porosity and phase fractions were conducted on the steels and no significant differences were noted with respect to aging temperature. Tensile strength, yield strength, and elongation to fracture all increased with increasing aging temperature reaching maxima at 538°C in most cases. Increased strength and decreased ductility were observed in steels of higher martensite content. Nanoindentation of the individual microconstituents was employed to obtain a fundamental understanding of the strengthening contributions. Both the ferrite and martensite hardness values increased with aging temperature and exhibited similar maxima to the bulk tensile properties. Due to the complex non-uniform stresses and strains associated with conventional nanoindentation, micropillar compression has become an attractive method to probe local mechanical behavior while limiting strain gradients and contributions from surrounding features. In this study, micropillars of ferrite and martensite were fabricated by focused ion beam (FIB) milling of dual phase precipitation hardened powder metallurgy (PM) stainless steels. Compression testing was conducted using a nanoindenter equipped with a flat punch indenter. The stress-strain curves of the individual microconstituents were calculated from the load-displacement curves less the extraneous displacements of the system. Using a rule of mixtures approach in conjunction with porosity corrections, the mechanical properties of ferrite and martensite were combined for comparison to tensile tests of the bulk material, and reasonable agreement was found for the ultimate tensile

  1. Study of the formation mechanisms of some volatile compounds during the aging of sweet fortified wines.

    PubMed

    Cutzach, I; Chatonnet, P; Dubourdieu, D

    1999-07-01

    Sweet fortified wines, traditionally aged under strong oxidation conditions, have a characteristic aroma. An experimental laboratory study investigated the aging of red and white sweet fortified wines under various conditions. The formation of various molecules, previously identified as characteristic of the aroma of this type of wine, was monitored by analysis. The development of these compounds during accelerated aging was affected by oxidation and the color of the wine. Among the molecules studied, sotolon [3-hydroxy-4, 5-dimethyl-2(5H)-furanone] was one of the few molecules present in concentrations above the perception threshold, in both red and white wines. Buildup was strongly affected by the presence of oxygen in white wine subjected to accelerated aging. (Ethoxymethyl)furfural, formed from 5-(hydroxymethyl)furfural, and furfural, derived from sugars, are also involved in the aroma of sweet fortified white wines aged in oxygen-free conditions. The substances most characteristic of accelerated aging of sweet fortified red wines were 5-(hydroxymethyl)furfural, acetylformoin, and hydroxymaltol, the formation of which is affected by oxidation, and dihydromaltol, formed in the absence of oxidation.

  2. Improved Corrosion Resistance of As-Extruded GZ51K Biomagnesium Alloy with High Mechanical Properties by Aging Treatment

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaobo; Wang, Qian; Ba, Zhixin; Wang, Zhangzhong; Xue, Yajun

    2016-03-01

    Effects of aging treatment on microstructure, mechanical properties, and corrosion behavior of the as-extruded Mg-5Gd-1Zn-0.6Zr (GZ51K, wt.%) alloy were investigated. Microstructure was observed by optical microscopy and scanning electron microscopy, mechanical properties were tested on a tensile test machine and a microhardness tester, and corrosion behavior was evaluated by mass loss and polarization tests. It is found that most of equiaxed α-Mg grains have long-period stacking ordered (LPSO) structure, and some of them have no LPSO structure. Long-elongated grains are formed in the as-extruded alloy due to partial recrystallization and disappear after being aged at 200 and 220 °C. The as-extruded alloy exhibits both high-yield strength and high ductility. The mechanical properties of the alloy are not apparently enhanced, but the corrosion resistance is significantly improved after aging treatment. Moreover, the alloy with LPSO structure presents uniform corrosion mode in simulated body fluid. The GZ51K alloy with high mechanical properties and uniform corrosion behavior is worthy to be further investigated for biomedical applications.

  3. What can long-lived mutants tell us about mechanisms causing aging and lifespan variation in natural environments?

    PubMed

    Briga, Michael; Verhulst, Simon

    2015-11-01

    Long-lived mutants of model organisms have brought remarkable progress in our understanding of aging mechanisms. However, long-lived mutants are usually maintained in optimal standardized laboratory environments (SLEs), and it is not obvious to what extent insights from long-lived mutants in SLEs can be generalized to more natural environments. To address this question, we reviewed experiments that compared the fitness and lifespan advantage of long-lived mutants relative to wild type controls in SLEs and more challenging environments in various model organisms such as yeast Saccharomyces cerevisiae, the nematode worm Caenorhabditis elegans, the fruitfly Drosophila melanogaster and the mouse Mus musculus. In competition experiments over multiple generations, the long-lived mutants had a lower fitness relative to wild type controls, and this disadvantage was the clearest when the environment included natural challenges such as limited food (N=6 studies). It is well known that most long-lived mutants have impaired reproduction, which provides one reason for the fitness disadvantage. However, based on 12 experiments, we found that the lifespan advantage of long-lived mutants is diminished in more challenging environments, often to the extent that the wild type controls outlive the long-lived mutants. Thus, it appears that information on aging mechanisms obtained from long-lived mutants in SLEs may be specific to such environments, because those same mechanisms do not extend lifespan in more natural environments. This suggests that different mechanisms cause variation in aging and lifespan in SLEs compared to natural populations.

  4. Irreparable telomeric DNA damage and persistent DDR signalling as a shared causative mechanism of cellular senescence and ageing.

    PubMed

    Rossiello, Francesca; Herbig, Utz; Longhese, Maria Pia; Fumagalli, Marzia; d'Adda di Fagagna, Fabrizio

    2014-06-01

    The DNA damage response (DDR) orchestrates DNA repair and halts cell cycle. If damage is not resolved, cells can enter into an irreversible state of proliferative arrest called cellular senescence. Organismal ageing in mammals is associated with accumulation of markers of cellular senescence and DDR persistence at telomeres. Since the vast majority of the cells in mammals are non-proliferating, how do they age? Are telomeres involved? Also oncogene activation causes cellular senescence due to altered DNA replication and DDR activation in particular at the telomeres. Is there a common mechanism shared among apparently distinct types of cellular senescence? And what is the role of telomeric DNA damage?

  5. Evidence for yeast autophagy during simulation of sparkling wine aging: a reappraisal of the mechanism of yeast autolysis in wine.

    PubMed

    Cebollero, Eduardo; Carrascosa, Alfonso V; Gonzalez, Ramon

    2005-01-01

    Yeast autolysis is the source of several molecules responsible for the quality of wines aged in contact with yeast cells. However, the mechanisms of yeast autolysis during wine aging are not completely understood. All descriptions of yeast autolysis in enological conditions emphasize the disturbance of cell organization as the starting event in the internal digestion of the cell, while no reference to autophagy is found in wine-related literature. By using yeast mutants defective in the autophagic or the Cvt pathways we have demonstrated that autophagy does take place in wine production conditions. This finding has implications for the genetic improvement of yeasts for accelerated autolysis.

  6. Future Expectations of Brasilian Street Youth

    ERIC Educational Resources Information Center

    Raffaelli, M.; Koller, S.H.

    2005-01-01

    Future expectations of youth surviving on the streets of Porto Alegre, Brasil, were examined. The sample consisted of 35 boys and 34 girls aged 10-18 (M age 14.4) who participated in a sentence completion task and semi-structured interviews. Responses to two incomplete sentences regarding the future revealed a mismatch between hoped-for and…

  7. Age-Dependent Changes in Geometry, Tissue Composition and Mechanical Properties of Fetal to Adult Cryopreserved Human Heart Valves.

    PubMed

    van Geemen, Daphne; Soares, Ana L F; Oomen, Pim J A; Driessen-Mol, Anita; Janssen-van den Broek, Marloes W J T; van den Bogaerdt, Antoon J; Bogers, Ad J J C; Goumans, Marie-José T H; Baaijens, Frank P T; Bouten, Carlijn V C

    2016-01-01

    There is limited information about age-specific structural and functional properties of human heart valves, while this information is key to the development and evaluation of living valve replacements for pediatric and adolescent patients. Here, we present an extended data set of structure-function properties of cryopreserved human pulmonary and aortic heart valves, providing age-specific information for living valve replacements. Tissue composition, morphology, mechanical properties, and maturation of leaflets from 16 pairs of structurally unaffected aortic and pulmonary valves of human donors (fetal-53 years) were analyzed. Interestingly, no major differences were observed between the aortic and pulmonary valves. Valve annulus and leaflet dimensions increase throughout life. The typical three-layered leaflet structure is present before birth, but becomes more distinct with age. After birth, cell numbers decrease rapidly, while remaining cells obtain a quiescent phenotype and reside in the ventricularis and spongiosa. With age and maturation-but more pronounced in aortic valves-the matrix shows an increasing amount of collagen and collagen cross-links and a reduction in glycosaminoglycans. These matrix changes correlate with increasing leaflet stiffness with age. Our data provide a new and comprehensive overview of the changes of structure-function properties of fetal to adult human semilunar heart valves that can be used to evaluate and optimize future therapies, such as tissue engineering of heart valves. Changing hemodynamic conditions with age can explain initial changes in matrix composition and consequent mechanical properties, but cannot explain the ongoing changes in valve dimensions and matrix composition at older age.

  8. Influence of Thermal Aging on the Mechanical and Corrosion Properties of C-22 Alloy Welds

    SciTech Connect

    Edgecumbe Summers, T.S.; Rebak, R.B.; Seeley, R.R.

    2000-06-15

    The phase stability of C-22 alloy (UNS No. N06022) gas tungsten arc welds was studied by aging samples at 427, 482, 538, 593, 649, 704, and 760 C for times up to 40,000 hours. The tensile properties and the Charpy impact toughness of these samples were measured in the as-welded condition as well as after aging. The corrosion resistance was measured using standard immersion tests in acidic ferric sulfate (ASTM G 28 A) and 2.5% hydrochloric acid solutions at the boiling point. The microstructures of weld samples were examined using scanning electron microscopy (SEM). One weld sample (aged 40,000 hours at 427 C) was examined using transmission electron microscopy (TEM). The structure of the unaged welds was dendritic with tetrahedrally close-packed (TCP) phase particles in the interdendritic regions. Long-range order was seen in the weld aged at 427 C for 40,000 hours and was assumed to also occur in other welds aged below approximately 600 C. At temperatures above about 600 C, TCP phase nucleation and growth of existing particles occurred. This precipitation occurred near the original particles presumably in regions of the highest molybdenum (Mo) segregation. Lower temperatures had little or no effect on the morphology of TCP phases. The C-22 weld samples were approximately 25% stronger but 30-40% less ductile than the base metal. Strengthening of the weld during aging occurred significantly only at 593 C for the aging times investigated. Because strengthening was not seen at higher temperatures, it was assumed to be due to ordering which has been seen in C-22 base metal at this temperature. A small amount of strengthening was seen at 427 C after 40,000 hours where ordering was just beginning. The Charpy impact toughness was reduced dramatically with aging. The time at which this reduction occurred decreased as aging temperature increased suggesting that the reduced ductility is due to the presence and growth of the brittle TCP phases. The corrosion rate of weld

  9. Expectancy and Repetition in Task Preparation

    NASA Technical Reports Server (NTRS)

    Ruthruff, E.; Remington, R. W.; Johnston, James C.; Null, Cynthia H. (Technical Monitor)

    1996-01-01

    We studied the mechanisms of task preparation using a design that pitted task expectancy against task repetition. In one experiment, two simple cognitive tasks were presented in a predictable sequence containing both repetitions and non-repetitions. The typical task sequence was AABBAABB. Occasional violations of this sequence allowed us to measure the effects of valid versus invalid expectancy. With this design, we were able to study the effects of task expectancy, task repetition, and interaction.

  10. Behavior, Expectations and Status

    ERIC Educational Resources Information Center

    Webster, Jr, Murray; Rashotte, Lisa Slattery

    2010-01-01

    We predict effects of behavior patterns and status on performance expectations and group inequality using an integrated theory developed by Fisek, Berger and Norman (1991). We next test those predictions using new experimental techniques we developed to control behavior patterns as independent variables. In a 10-condition experiment, predictions…

  11. Addicted to Expectations? Conference!

    ERIC Educational Resources Information Center

    Gilliland, Mary

    Whether teaching incoming students or training faculty in other disciplines, writing instructors often form unrealistic expectations about goals and skills of students and colleagues, which (like chemical addictions) predictably recur each semester as though they had never occurred before. For effective instruction, it is important that…

  12. Great Expectations. [Lesson Plan].

    ERIC Educational Resources Information Center

    Devine, Kelley

    Based on Charles Dickens' novel "Great Expectations," this lesson plan presents activities designed to help students understand the differences between totalitarianism and democracy; and a that a writer of a story considers theme, plot, characters, setting, and point of view. The main activity of the lesson involves students working in groups to…

  13. Maintaining High Expectations

    ERIC Educational Resources Information Center

    Williams, Roger; Williams, Sherry

    2014-01-01

    Author and husband, Roger Williams, is hearing and signs fluently, and author and wife, Sherry Williams, is deaf and uses both speech and signs, although she is most comfortable signing. As parents of six children--deaf and hearing--they are determined to encourage their children to do their best, and they always set their expectations high. They…

  14. Parenting with High Expectations

    ERIC Educational Resources Information Center

    Timperlake, Benna Hull; Sanders, Genelle Timperlake

    2014-01-01

    In some ways raising deaf or hard of hearing children is no different than raising hearing children; expectations must be established and periodically tweaked. Benna Hull Timperlake, who with husband Roger, raised two hearing children in addition to their deaf daughter, Genelle Timperlake Sanders, and Genelle, now a deaf professional, share their…

  15. Prior expectations facilitate metacognition for perceptual decision.

    PubMed

    Sherman, M T; Seth, A K; Barrett, A B; Kanai, R

    2015-09-01

    The influential framework of 'predictive processing' suggests that prior probabilistic expectations influence, or even constitute, perceptual contents. This notion is evidenced by the facilitation of low-level perceptual processing by expectations. However, whether expectations can facilitate high-level components of perception remains unclear. We addressed this question by considering the influence of expectations on perceptual metacognition. To isolate the effects of expectation from those of attention we used a novel factorial design: expectation was manipulated by changing the probability that a Gabor target would be presented; attention was manipulated by instructing participants to perform or ignore a concurrent visual search task. We found that, independently of attention, metacognition improved when yes/no responses were congruent with expectations of target presence/absence. Results were modeled under a novel Bayesian signal detection theoretic framework which integrates bottom-up signal propagation with top-down influences, to provide a unified description of the mechanisms underlying perceptual decision and metacognition.

  16. The aging behavior of types 308 and 308CRE stainless steels and its effect on mechanical properties

    SciTech Connect

    Vitek, J.M.; David, S.A.

    1987-01-01

    Aging of 308 and 308CRE SS was studied at 475 to 850/sup 0/C for aging times up to 10,000 hours. Above 550/sup 0/C, aging of 308 steel resulted in precipitation of carbides and the transformation of ferrite to sigma phase or the formation of sigma phase in initially ferrite-free material. The elevated-temperature aging of 308CRE steel resulted in the precipitation of titanium-rich carbides, nitrides, and sulfides, and the transformation of ferrite to sigma phase. The distribution of precipitates was affected by the initial condition of the materials. The elevated-temperature creep properties, and in particular the improved properties of 308CRE, were related to the precipitate distribution. Below 550/sup 0/C, aging of welded type 308 steel, precipitation of G-phase within the ferrite was observed, as well as the decomposition of ferrite into alpha and alpha prime. With the help of a novel mechanical properties microprobe, which was capable of determining the hardness of the minor constituent ferrite phase, the hardness behavior as a function of aging could be related to the microstructures. These results are interpreted in terms of the potential susceptibility of these alloys to 475/sup 0/C embrittlement.

  17. Sarcopenia, obesity, and natural killer cell immune senescence in aging: altered cytokine levels as a common mechanism.

    PubMed

    Lutz, Charles T; Quinn, LeBris S

    2012-08-01

    Human aging is characterized by both physical and physiological frailty. A key feature of frailty, sarcopenia is the age-associated decline in skeletal muscle mass, strength, and endurance that characterize even the healthy elderly. Increases in adiposity, particularly in visceral adipose tissue, are almost universal in aging individuals and can contribute to sarcopenia and insulin resistance by increasing levels of inflammatory cytokines known collectively as adipokines. Aging also is associated with declines in adaptive and innate immunity, known as immune senescence, which are risk factors for cancer and all-cause mortality. The cytokine interleukin-15 (IL-15) is highly expressed in skeletal muscle tissue and declines in aging rodent models. IL-15 inhibits fat deposition and insulin resistance, is anabolic for skeletal muscle in certain situations, and is required for the development and survival of natural killer (NK) lymphocytes. We review the effect that adipokines and myokines have on NK cells, with special emphasis on IL-15. We posit that increased adipokine and decreased IL-15 levels during aging constitute a common mechanism for sarcopenia, obesity, and immune senescence.

  18. Mechanisms behind distracted driving behavior: The role of age and executive function in the engagement of distracted driving.

    PubMed

    Pope, Caitlin Northcutt; Bell, Tyler Reed; Stavrinos, Despina

    2017-01-01

    Performing secondary tasks, such as texting while driving, is associated with an increased risk of motor vehicle collisions (MVCs). While cognitive processes, such as executive function, are involved in driving, little is known about the relationship between executive control and willingness to engage in distracted driving. This study investigated the relationship between age, behavioral manifestations of executive function, and self-reported distracted driving behaviors. Executive difficulty (assessed with the BRIEF-A) as well as demographics (age and gender) was considered as possible predictors of engagement in distracted driving behaviors. Fifty-nine young, middle, and older adults self-reported executive difficulty and weekly engagement in distracted driving behaviors. Results revealed that while partially accounted for by age, global executive difficulty was uniquely related to engagement in distracted driving behaviors. Older age was associated with fewer weekly self-reported distracted driving behaviors while higher self-reported executive difficulty was associated with more frequent weekly engagement in distracted behavior. No significant differences were found between young and middle-aged adults on distracted driving behaviors. Findings conclude that distracted driving is a ubiquitous phenomenon evident in drivers of all ages. Possible mechanisms underlying distracted driving behavior could potentially be related to deficits in executive function.

  19. Room-temperature aging of Narmco 5208 carbon-epoxy prepreg. II - Physical, mechanical, and nondestructive characterization

    SciTech Connect

    Cole, K.C.; Noel, D.; Hechler, J.-J.; Cielo, P.; Krapez, J.-C. )

    1991-06-01

    Samples of Narmco Rigidite 5208/WC3000 carbon-epoxy composite prepreg were exposed to ambient temperature and 50 percent relative humidity for different periods up to 66 days. The aging has a significant effect on prepreg physical properties such as tack, volatiles content, and gel time. A set of four-ply laminates made from aged prepreg was subjected to tensile testing, ultrasonic inspection, and optothermal inspection. No relationship could be discerned between laminate properties and prepreg aging time. However, variations in panel homogeneity were observed, and these correlated with thermal diffusivity and tensile modulus measurements, but not with ultimate tensile strength or elongation. A set of six-ply laminates was used to measure compressive properties, interlaminar shear strength, and physical properties. These panels also showed variations in porosity, again unrelated to aging, but in addition, the fiber-resin ratio was observed to decrease with aging time. Both factors were found to affect mechanical properties. The implications concerning the importance of monitoring the aging by physicochemical methods are discussed. 30 refs.

  20. Mechanism of production of troponin T fragments during postmortem aging of porcine muscle.

    PubMed

    Kitamura, Shin-ichi; Muroya, Susumu; Tanabe, Soichi; Okumura, Tomoyuki; Chikuni, Koichi; Nishimura, Toshihide

    2005-05-18

    Troponin T (TnT) is one of the myofibrillar proteins that is easily degraded during postmortem aging of pork. In this study, we determined the N-terminal amino acid sequences of TnT degradation fragments produced during postmortem aging and by m-calpain hydrolysis. The N-terminal amino acid sequences of TnT fragments produced during postmortem aging were EVHEPEEKPRPKLTAP, EKPRPKLTAPKIPEG, and APKIPEGEKVDF. On the other hand, the N-terminal amino acid sequences of TnT fragments produced by the action of m-calpain were APPPPAEV, EVHEPEEK, and APK. These sequences of degradation fragments could be mapped on fast type TnT isoform 2. The peptide bonds of His37-Glu38 and Thr51-Ala52 in fTnT2 were cleaved during postmortem aging as well as by the calpain hydrolysis; therefore, calpain was concluded to have an important role in TnT degradation during postmortem aging. It was also found that the sourness-suppressing peptide APPPPAEVHEVHEEVH (Okumura et al. Biosci. Biotechnol. Biochem. 2004, 68, 1657-1662) derived from TnT degradation could be produced by the action of calpains on Glu21-Ala22 and His37-Glu38 sites.

  1. Degradation of mechanical properties of stainless steel cladding due to neutron irradiation and thermal aging

    SciTech Connect

    Haggag, F.M.

    1994-09-01

    Thermal aging of three-wire series-arc stainless steel weld overlay cladding at 288{degrees}C for 1605 h resulted in an appreciable decrease (16%) in the Charpy V-notch (CVN) upper-shelf energy (USE), but the effect on the 41-J transition temperature shift was very small (3{degrees}C). The combined effect following neutron irradiation at 288{degrees}C to a fluence of 5 X 10{sup 19} neutrons/cm{sup 2} (>1 MeV) was a 22% reduction in the USE and a 29{degrees}C shift in the 41-J transition temperature. The effect of thermal aging on tensile properties was very small. However, the combined effect of irradiation and aging was an increase in the yield strength (6 to 34% at test temperatures from 288 to -125{degrees}C) and no apparent change in ultimate tensile strength or total elongation. Neutron irradiation reduced the initiation fracture toughness (J{sub {kappa}}) much more than did thermal aging alone. However, irradiation slightly decreased the tearing modulus but no reduction was caused by thermal aging alone. The effects of long-term thermal exposure times (20,000 and 50,000 h) will be investigated when the specimens become available. Also, long-term thermal exposure of the three-wire cladding as well as type 308 stainless steel weld materials at 343{degrees}C is in progress.

  2. Mechanical Testing of TR-55 Rubber Thermally Aged Under Tensile Strain

    SciTech Connect

    Small IV, W; Alviso, C T; Wilson, T S; Chinn, S C; Maxwell, R S

    2009-03-10

    TR-55 rubber specimens were previously subjected to an aging process consisting of the application of a tensile strain of approximately 67%, 100%, 133%, or 167% elongation for 4, 8, 12, or 16 h at either 250 C or room temperature. Control specimens at the same temperatures/durations were not subjected to tensile strain. The specimens were allowed to recover at room temperature without external stimuli for over 100 days before tensile testing. A single dog bone was cut from each specimen and a stress-strain curve was obtained. The elastic modulus of each specimen was calculated. Specimens aged under tensile strain exhibited rubber-like behavior dependent on the aging elongation and duration. This behavior was not evident in the unstrained controls. For the unstrained controls, exposure to 250 C resulted in an increase in modulus relative to the unheated material independent of the heating duration. The tensile strain applied during the aging process caused a reduction in modulus relative to the controls; lower moduli were observed for the shorter aging durations. Slippage of the specimens in the grips prevented determination of ultimate strength, as all specimens either slipped completely out of the grip before failure or failed at the original grip edge after slipping.

  3. Molecular mechanism of extrinsic factors affecting anti-aging of stem cells.

    PubMed

    Wong, Tzyy Yue; Solis, Mairim Alexandra; Chen, Ying-Hui; Huang, Lynn Ling-Huei

    2015-03-26

    Scientific evidence suggests that stem cells possess the anti-aging ability to self-renew and maintain differentiation potentials, and quiescent state. The objective of this review is to discuss the micro-environment where stem cells reside in vivo, the secreted factors to which stem cells are exposed, the hypoxic environment, and intracellular factors including genome stability, mitochondria integrity, epigenetic regulators, calorie restrictions, nutrients, and vitamin D. Secreted tumor growth factor-β and fibroblast growth factor-2 are reported to play a role in stem cell quiescence. Extracellular matrices may interact with caveolin-1, the lipid raft on cell membrane to regulate quiescence. N-cadherin, the adhesive protein on niche cells provides support for stem cells. The hypoxic micro-environment turns on hypoxia-inducible factor-1 to prevent mesenchymal stem cells aging through p16 and p21 down-regulation. Mitochondria express glucosephosphate isomerase to undergo glycolysis and prevent cellular aging. Epigenetic regulators such as p300, protein inhibitors of activated Stats and H19 help maintain stem cell quiescence. In addition, calorie restriction may lead to secretion of paracrines cyclic ADP-ribose by intestinal niche cells, which help maintain intestinal stem cells. In conclusion, it is crucial to understand the anti-aging phenomena of stem cells at the molecular level so that the key to solving the aging mystery may be unlocked.

  4. Mechanisms of skeletal muscle aging: insights from Drosophila and mammalian models

    PubMed Central

    Demontis, Fabio; Piccirillo, Rosanna; Goldberg, Alfred L.; Perrimon, Norbert

    2013-01-01

    A characteristic feature of aged humans and other mammals is the debilitating, progressive loss of skeletal muscle function and mass that is known as sarcopenia. Age-related muscle dysfunction occurs to an even greater extent during the relatively short lifespan of the fruit fly Drosophila melanogaster. Studies in model organisms indicate that sarcopenia is driven by a combination of muscle tissue extrinsic and intrinsic factors, and that it fundamentally differs from the rapid atrophy of muscles observed following disuse and fasting. Extrinsic changes in innervation, stem cell function and endocrine regulation of muscle homeostasis contribute to muscle aging. In addition, organelle dysfunction and compromised protein homeostasis are among the primary intrinsic causes. Some of these age-related changes can in turn contribute to the induction of compensatory stress responses that have a protective role during muscle aging. In this Review, we outline how studies in Drosophila and mammalian model organisms can each provide distinct advantages to facilitate the understanding of this complex multifactorial condition and how they can be used to identify suitable therapies. PMID:24092876

  5. Influence of Sea Water Aging on the Mechanical Behaviour of Acrylic Matrix Composites

    NASA Astrophysics Data System (ADS)

    Davies, P.; Le Gac, P.-Y.; Le Gall, M.

    2016-07-01

    A new matrix resin was recently introduced for composite materials, based on acrylic resin chemistry allowing standard room temperature infusion techniques to be used to produce recyclable thermoplastic composites. This is a significant advance, particularly for more environmentally-friendly production of large marine structures such as boats. However, for such applications it is essential to demonstrate that composites produced with these resins resist sea water exposure in service. This paper presents results from a wet aging study of unreinforced acrylic and glass and carbon fibre reinforced acrylic composites. It is shown that the acrylic matrix resin is very stable in seawater, showing lower property losses after seawater aging than those of a commonly-used epoxy matrix resin. Carbon fibre reinforced acrylic also shows good property retention after aging, while reductions in glass fibre reinforced composite strengths suggest that specific glass fibre sizing may be required for optimum durability.

  6. [Molecular mechanisms of combined extremely radiofrequency and infrared therapy in various age patients with chronic parodontitis].

    PubMed

    Ianova, O A; Medvedev, D S; Lin'kova, N S; Trifonov, N I; D'iakonov, M M

    2014-01-01

    The influence of extreme radiofrequency millimeter microwave (EHF) and infrared (IR) electromagnetic emanation on the molecular markers of cell renovation (Ki67, p53) and proinflammatory cytokine TNF-α expression in the buccal cells of various age patients with chronic parodontitis was investigated. The results show that EHF- and IR-electromagnetic emanation increased Ki67 proliferative marker expression and decreased expression of proapoptosis protein p53 and proinflammatory cytokine TNF-α in the buccal epithelium of young, middle-aged and elderly people with chronic parodontitis. The data obtained open the new ability for patogenetic treatment of various age patients with chronic parodontitis using the EHF- and IR-electromagnetic emanation method.

  7. Influence of Sea Water Aging on the Mechanical Behaviour of Acrylic Matrix Composites

    NASA Astrophysics Data System (ADS)

    Davies, P.; Le Gac, P.-Y.; Le Gall, M.

    2017-02-01

    A new matrix resin was recently introduced for composite materials, based on acrylic resin chemistry allowing standard room temperature infusion techniques to be used to produce recyclable thermoplastic composites. This is a significant advance, particularly for more environmentally-friendly production of large marine structures such as boats. However, for such applications it is essential to demonstrate that composites produced with these resins resist sea water exposure in service. This paper presents results from a wet aging study of unreinforced acrylic and glass and carbon fibre reinforced acrylic composites. It is shown that the acrylic matrix resin is very stable in seawater, showing lower property losses after seawater aging than those of a commonly-used epoxy matrix resin. Carbon fibre reinforced acrylic also shows good property retention after aging, while reductions in glass fibre reinforced composite strengths suggest that specific glass fibre sizing may be required for optimum durability.

  8. Mechanical properties of cortical bone and their relationships with age, gender, composition and microindentation properties in the elderly.

    PubMed

    Mirzaali, Mohammad J; Schwiedrzik, J Jakob; Thaiwichai, Suwanwadee; Best, James P; Michler, Johann; Zysset, Philippe K; Wolfram, Uwe

    2016-12-01

    The growing incidence of skeletal fractures poses a significant challenge to ageing societies. Since a major part of physiological loading in the lower limbs is carried by cortical bone, it would be desirable to better understand the structure-mechanical property relationships and scale effects in this tissue. This study aimed at assessing whether microindentation properties combined with chemical and morphological information are usable to predict macroscopic elastic and strength properties in a donor- and site-matched manner. Specimens for quasi-static macroscopic tests in tension, compression, and torsion and microindentation were prepared from a cohort of 19 male and 20 female donors (46 to 99 years). All tests were performed under fully hydrated conditions. The chemical composition of the extra-cellular matrix was investigated with Raman spectroscopy. The results of the micro-mechanical tests were combined with morphological and compositional properties using a power law relationship to predict the macro-mechanical results. Microindentation properties were not gender dependent, remarkably constant over age, and showed an overall small variation with standard deviations of approximately 10 %. Similar results were obtained for chemical tissue composition. Macro-mechanical stiffness and strength were significantly related to porosity for all load cases (p<0.05). In case of macroscopic yield strain and work-to-failure this was only true in torsion and compression, respectively. The correlations of macro-mechanical with micro-mechanical, morphological, and chemical properties showed no significance for cement line density, mineralisation, or variations in the microindentation results and were dominated by porosity with a moderate explanatory power of predominately less than 50 %. The results confirm that age, with minor exceptions gender, and small variations in average mineralisation have negligible effect on the tissue microindentation properties of human

  9. Kinetics and mechanism of thermal aging embrittlement of duplex stainless steels

    SciTech Connect

    Chung, H.M.; Chopra, O.K.

    1987-06-01

    Microstructural characteristics of long-term-aged cast duplex stainless steel specimens from eight laboratory heats and an actual component from a commercial boiling water reactor have been investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), small angle neutron scattering (SANS), and atom probe field ion microscopy (APFIM) techniques. Three precipitate phases, i.e., Cr-rich ..cap alpha..' and the Ni- and Si-rich G phase, and ..gamma../sub 2/ austenite, have been identified in the ferrite matrix of the aged specimens. For CF-8 grade materials, M/sub 23/C/sub 6/ carbides were identified on the austenite-ferrite boundaries as well as in the ferrite matrix for aging at greater than or equal to 450/sup 0/C. It has been shown that Si, C, and Mo contents are important factors that influence the kinetics of the G-phase precipitation. However, TEM and APFIM analyses indicate that the embrittlement for less than or equal to400/sup 0/C aging is primarily associated with Fe and Cr segregation in ferrite by spinodal decomposition. For extended aging, e.g., 6 to 8 years at 350 to 400/sup 0/C, large platelike ..cap alpha..' formed by nucleation and growth from the structure produced by the spinodal decomposition. The Cr content appears to play an important role either to promote the platelike ..cap alpha..' (high Cr content) or to suppress the ..cap alpha..' in favor of ..gamma../sub 2/ precipitation (low Cr). Approximate TTT diagrams for the spinodal, ..cap alpha..', G, ..gamma../sub 2/, and the in-ferrite M/sub 23/C/sub 6/ have been constructed for 250 to 450/sup 0/C aging. Microstructural modifications associated with a 550/sup 0/C reannealing and a subsequent toughness restoration are also discussed. It is shown that the toughness restoration is associated primarily with the dissolution of the Cr-rich region in ferrite.

  10. Peripheral surgical wounding may induce cognitive impairment through interlukin-6-dependent mechanisms in aged mice

    PubMed Central

    Dong, Yuanlin; Xu, Zhipeng; Huang, Lining; Zhang, Yiying; Xie, Zhongcong

    2016-01-01

    Post-operative cognitive dysfunction (POCD) is associated with morbidity, mortality and increased cost of medical care. However, the neuropathogenesis and targeted interventions of POCD remain largely to be determined. We have found that the peripheral surgical wounding induces an age-dependent Aβ accumulation, neuroinflammation and cognitive impairment in aged mice. Pro-inflammatory cytokine interlukin-6 (IL-6) has been reported to be associated with cognitive impairment in rodents and humans. However, the role of IL-6 in the neuropathogenesis of POCD is unknown. We therefore employed pharmacological (IL-6 antibody) and genetic (knockout of IL-6) approach to investigate whether IL-6 contributed to the peripheral surgical wounding-induced cognitive impairment in aged mice. Abdominal surgery under local anesthesia (peripheral surgical wounding) was established in 18-month-old wild-type and IL-6 knockout mice (n = 6 to 10 in each group). Brain level of IL-6 and cognitive function in the mice were determined by western blot, ELISA at the end of procedure, and Fear Conditioning System at 7 days after the procedure. The peripheral surgical wounding increased the level of IL-6 in the hippocampus of aged wild-type, but not IL-6 knockout mice. IL-6 antibody ameliorated the peripheral surgical wounding-induced cognitive impairment in the aged wild-type mice. Finally, the peripheral surgical wounding did not induce cognitive impairment in the aged IL-6 knockout mice. These data suggested that IL-6 would be a required pro-inflammatory cytokine for the peripheral surgical wounding-induced cognitive impairment. Given this, further studies are warranted to investigate the role of IL-6 in the neuropathogenesis and targeted interventions of POCD. PMID:28217289

  11. Aging related erectile dysfunction—potential mechanism to halt or delay its onset

    PubMed Central

    Gonzalez-Cadavid, Nestor F.; Rajfer, Jacob

    2017-01-01

    Erectile dysfunction (ED) will visit every man at some time in his life. The age at when that knock on the door is heard is totally dependent on one’s genetics as well as other extrinsic factors. Unlike guests who come for a visit and then leave, once ED shows up it tends to hang around forever. To add insult to injury, the longer ED hangs around, the worse it will get. It is estimated that by the time a man is in his 40’s, he has about a 40% chance of having some form of ED and this prevalence increases about 10% per decade thereafter. This suggests that the aging related process that leads to ED begins early in life. It turns out that the most common cause of ED, regardless of the patient’s age, is due to a problem with the vascular system of the penis. However, this specific aging related vascular problem is not caused by arterial disease but due to a dysfunction and/or loss of the corporal smooth muscle cells (SMC), the main constituent of the corporal sinusoids. As one gets older, these SMC continue to degrade and disappear. When approximately 15% of these cells have been impacted, it results in an inability of the corporal tissue to retain and/or prevent the blood from “leaking” out of the corporal sinusoids into the systemic veins. However, the corporal SMC themselves begin to combat this aging process by expressing the inducible nitric oxide synthase (iNOS) enzyme to make nitric oxide (NO) in an attempt to quench the high intracellular oxidative stress responsible for the SMC apoptosis. When this iNOS pathway is then pharmacologically upregulated, reversal of these aging related changes in the corpora with correction of the venous leakage is observed. Since we believe that aging related ED is pathologically the same disorder as essential hypertension, the development of a therapeutic regimen that can halt, delay or possibly reverse the cellular processes that lead to aging related ED should also be applicable to those patients diagnosed with

  12. Lamb wave characterization of the effects of long-term thermal-mechanical aging on composite stiffness.

    PubMed

    Seale, M D; Madaras, E I

    1999-09-01

    Lamb waves offer a promising method of evaluating damage in composite materials. The Lamb wave velocity is directly related to the material parameters, so an effective tool exists to monitor damage in composites by measuring the velocity of these waves. The Lamb Wave Imager (LWI) uses a pulse/receive technique that excites an antisymmetric Lamb mode and measures the time-of-flight over a wide frequency range. Given the material density and plate thickness, the bending and out-of-plane shear stiffnesses are calculated from a reconstruction of the dispersion curve. In this study, the time-of-flight as well as the elastic stiffnesses D11, D22, A44, and A55 for composite samples which have undergone combined thermal and mechanical aging are obtained. The samples examined include a baseline specimen with 0 cycles, specimens which have been aged 2350 and 3530 cycles at high strain levels, and one specimen aged 3530 cycles at low strain levels.

  13. Lamb wave characterization of the effects of long-term thermal-mechanical aging on composite stiffness

    NASA Technical Reports Server (NTRS)

    Seale, M. D.; Madaras, E. I.

    1999-01-01

    Lamb waves offer a promising method of evaluating damage in composite materials. The Lamb wave velocity is directly related to the material parameters, so an effective tool exists to monitor damage in composites by measuring the velocity of these waves. The Lamb Wave Imager (LWI) uses a pulse/receive technique that excites an antisymmetric Lamb mode and measures the time-of-flight over a wide frequency range. Given the material density and plate thickness, the bending and out-of-plane shear stiffnesses are calculated from a reconstruction of the dispersion curve. In this study, the time-of-flight as well as the elastic stiffnesses D11, D22, A44, and A55 for composite samples which have undergone combined thermal and mechanical aging are obtained. The samples examined include a baseline specimen with 0 cycles, specimens which have been aged 2350 and 3530 cycles at high strain levels, and one specimen aged 3530 cycles at low strain levels.

  14. Changes in the magnetic and mechanical properties of thermally aged Fe-Cu alloys due to nano-sized precipitates

    NASA Astrophysics Data System (ADS)

    Li, Yi; Li, Yuanfei; Deng, Shanquan; Xu, Ben; Li, Qiulin; Shu, Guogang; Liu, Wei

    2016-01-01

    The changes in the magnetic properties, mechanical properties, and microstructural parameters of Fe-Cu alloys due to thermal aging have been investigated to improve the fundamental understanding of using magnetic technology for the nondestructive evaluation (NDE) of irradiation embrittlement in the reactor pressure vessel (RPV). Nano-sized Cu particles precipitated from a Fe matrix after thermal aging at 500 °C for various times, and the microstructure parameters were determined. The coercivity, Barkhausen noise (BN), Vickers hardness, and yield stress were also measured for these samples. These properties show the same hardening-softening trend with increasing aging time, which can be interpreted in terms of the microstructure parameters evolution based on the model of the pinning of precipitates on domain walls and dislocations. These results suggest the practicability of using magnetic technology for the NDE of the irradiation embrittlement of the RPV.

  15. Parental socioeconomic status and unintentional injury deaths in early childhood: consideration of injury mechanisms, age at death, and gender.

    PubMed

    Hong, Juhee; Lee, Boeun; Ha, Eun Hee; Park, Hyesook

    2010-01-01

    The aim of this study was to determine whether the socioeconomic status (SES) of parents influences early childhood unintentional injury deaths for different injury mechanisms and the gender and age at death of the child. Study design is a population-based retrospective study. Death certificate data from 1995 to 2004 were linked to birth certificate data from 1995 to 1996 for each child who died when aged < or = 8 years. Parental age, birth order, marital status, residence area, educational level, and occupation were used as indices for SES. Cox proportional-hazards analysis was employed. Our results indicate that nonmetropolitan residence, low parental education level, and a father working in a nonadministrative job or as a farmer were associated with a higher risk of death from injury for both boys and girls. A mother aged younger than 20 years and parents working in manual jobs were associated with a higher risk in boys only. The risks of some socioeconomic factors (low parental education and a father working in a manual job or as a farmer) were evident for children aged 1-4 years. The risks of rural residency tended to increase in older children, and the risk of injury from having a mother aged younger than 20 years increased for younger children. The risks of childhood injury deaths from traffic accidents, falls, and fire/burns were associated with the SES of the parents. Younger parents were associated with higher risks of injury deaths from traffic accidents (hazard ratio [HR]: father, 7.9; mother, 1.9) and falls (HR: father, 2.0; mother, 2.5). A father working as a farmer was associated with a higher risk of childhood injury death from fire/burns (HR = 4.0). In conclusion, the parental SES risk profiles of childhood injury deaths varied with the age and gender of the child, and with the injury mechanism. Therefore, reducing excess injury deaths during early childhood requires preventive efforts targeted at high-risk parents, and based on injury mechanism

  16. Dysregulation of SIRT-1 in aging mice increases skeletal muscle fatigue by a PARP-1-dependent mechanism.

    PubMed

    Mohamed, Junaith S; Wilson, Joseph C; Myers, Matthew J; Sisson, Kayla J; Alway, Stephen E

    2014-10-01

    Accumulation of reactive oxygen species (ROS) in skeletal muscles and the resulting decline in muscle performance are hallmarks of sarcopenia. However, the precise mechanism by which ROS results in a decline in muscle performance is unclear. We demonstrate that isometric-exercise concomitantly increases the activities of Silent information regulator 1 (SIRT-1) and Poly [ADP-ribose] polymerase (PARP-1), and that activated SIRT-1 physically binds with and inhibits PARP-1 activity by a deacetylation dependent mechanism in skeletal muscle from young mice. In contrast, skeletal muscle from aged mice displays higher PARP-1 activity and lower SIRT-1 activity due to decreased intracellular NAD+ content, and as a result reduced muscle performance in response to exercise. Interestingly, injection of PJ34, a PARP-1 inhibitor, in aged mice increased SIRT-1 activity by preserving intracellular NAD+ content, which resulted in higher skeletal muscle mitochondrial biogenesis and performance. We found that the higher activity of PARP-1 in H2O2-treated myotubes or in exercised-skeletal muscles from aged mice is due to an elevated level of PARP-1 acetylation by the histone acetyltransferase General control of amino acid synthesis protein 5-like 2 (GCN-5). These results suggest that activation of SIRT-1 and/or inhibition of PARP-1 may ameliorate skeletal muscle performance in pathophysiological conditions such as sarcopenia and disuse-induced atrophy in aging.

  17. Exaggerated neurobiological sensitivity to threat as a mechanism linking anxiety with increased risk for diseases of aging.

    PubMed

    O'Donovan, Aoife; Slavich, George M; Epel, Elissa S; Neylan, Thomas C

    2013-01-01

    Anxiety disorders increase risk for the early development of several diseases of aging. Elevated inflammation, a common risk factor across diseases of aging, may play a key role in the relationship between anxiety and physical disease. However, the neurobiological mechanisms linking anxiety with elevated inflammation remain unclear. In this review, we present a neurobiological model of the mechanisms by which anxiety promotes inflammation. Specifically we propose that exaggerated neurobiological sensitivity to threat in anxious individuals may lead to sustained threat perception, which is accompanied by prolonged activation of threat-related neural circuitry and threat-responsive biological systems including the hypothalamic-pituitary-adrenal (HPA) axis, autonomic nervous system (ANS), and inflammatory response. Over time, this pattern of responding can promote chronic inflammation through structural and functional brain changes, altered sensitivity of immune cell receptors, dysregulation of the HPA axis and ANS, and accelerated cellular aging. Chronic inflammation, in turn, increases risk for diseases of aging. Exaggerated neurobiological sensitivity to threat may thus be a treatment target for reducing disease risk in anxious individuals.

  18. [Parameters of controlled mechanical lung ventilation and external respiratory function during thoracoscopic surgeries in children of different age groups].

    PubMed

    Ovcharenko, N M; Tsypin, L E; Geodakian, O S; Demakhin, A A

    2011-01-01

    The purpose of the study is to estimate the parameters of mechanical ventilation and respiratory function during videotorachoscopic surgeries in children. 73 anesthesias were conducted in children aged 5 to 16 years of age. During the study, a detailed monitoring of respiratory function and parameters of mechanical ventilation was carried out. Indicators reflecting the lung function remained stable in all phases of the study. Parameters of mechanical ventilation during the study varied. Changes in PIP and MAP were similar in all age groups. The maximum changes of compliance were in the third group. One-lung ventilation is safe under certain conditions: increasing FiO2 from 0.5 to 1, the reduction of tidal volume up to 5-5.3 ml/kg, the use of a size or a half size smaller cuffed endotracheal tubes for intubation of the right and left main bronchus compared to those for tracheal intubation. For the intubation of the right main bronchus the endotracheal tube with the Murphy eye should be used, for the means ventilation of the upper lobe of the right lung. If the minute volume of breathing is adequate and there is no preoperative hypercapnia, the elimination of CO2 for one-lung ventilation is not disrupted and the tension of CO2 in arterial blood increases.

  19. Genetic enhancements and expectations.

    PubMed

    Sorensen, K

    2009-07-01

    Some argue that genetic enhancements and environmental enhancements are not importantly different: environmental enhancements such as private schools and chess lessons are simply the old-school way to have a designer baby. I argue that there is an important distinction between the two practices--a distinction that makes state restrictions on genetic enhancements more justifiable than state restrictions on environmental enhancements. The difference is that parents have no settled expectations about genetic enhancements.

  20. Differences in Binding and Monitoring Mechanisms Contribute to Lifespan Age Differences in False Memory

    ERIC Educational Resources Information Center

    Fandakova, Yana; Shing, Yee Lee; Lindenberger, Ulman

    2013-01-01

    Based on a 2-component framework of episodic memory development across the lifespan (Shing & Lindenberger, 2011), we examined the contribution of memory-related binding and monitoring processes to false memory susceptibility in childhood and old age. We administered a repeated continuous recognition task to children (N = 20, 10-12 years),…

  1. Effect of aging on mechanical properties of aluminum-alloy rivets

    NASA Technical Reports Server (NTRS)

    Roop, Frederick C

    1941-01-01

    Curves and tabular data present the results of strength tests made during and after 2 1/2 years of aging on rivets and rivet wire of 3/16-inch nominal diameter. The specimens were of aluminum alloy: 24s, 17s, and a17s of the duralumin type and 53s of the magnesium-silicide type.

  2. [Molecular Mechanisms of Functional Activity Decreasing of the Skin Cells With Its Aging].

    PubMed

    Khavinson, V Kh; Linkova, N S; Kukanova, E O; Orlova, O A

    2016-01-01

    The article discusses the pool of signaling molecules that regulate the functional activity of the skin cells. Molecules of apoptosis and cells skin aging are p53, p21, p15, Cdk 4/6 and Bcl-2. Inflammation in skin fibroblasts are realized through the cytokines TNF-α, TGF-β, IL-1, ICAM-1, matrix metalloproteinase MMP-1,2,3,9, transcription factor NF-κB and activator protein AP-1. An important role in the aging of skin cells play neuroimmunoendocrine signaling molecules--melatonin, serotonin, skin fibroblast proliferation marker chromogranin A and CD98hc. Age-related changes in the activity of immune cells of the skin is associated with impaired expression of cluster of differentiation of T-lymphocytes (CD3, CD4, CD5, CD8, CD11) and dendritic cells (CD83⁺). These signaling molecules produced by the fibroblasts of the skin, regulate the activity of immune cells involved in the cascade of reactions associated with inflammatory responses, proliferation, apoptosis and cell regeneration. Based on these data nowadays new highly selective approaches to the diagnosis of the skin and the creation of cosmetic agents for the prevention of aging are developed.

  3. Effect of aging on mechanical properties of aluminum-alloy rivets

    NASA Technical Reports Server (NTRS)

    Roop, Frederick C

    1941-01-01

    Curves and tabular data present the results of strength tests made during and after 2 1/2 years of aging on rivets and rivet wire of 3/16-inch nominal diameter. The specimens were of aluminum alloy: 24S, 17S, and A17S of the duralumin type and 53S of the magnesium-silicide type.

  4. Pedagogy for Knowledge Recognition and Acquisition: Knowing and Being at the Close of the Mechanical Age

    ERIC Educational Resources Information Center

    Jaros, Milan

    2009-01-01

    It is the outstanding intellectual challenge of our age to find ways of providing citizens with access to and competent acquisition of the new applications and systems of knowledge. The purpose of this article is twofold. First, it is to justify at the conceptual level that we are facing an unprecedented shift in the way knowledge is generated and…

  5. Genome instability of ageing stem cells--Induction and defence mechanisms.

    PubMed

    Burkhalter, Martin D; Rudolph, K Lenhard; Sperka, Tobias

    2015-09-01

    The mammalian organism is comprised of tissue types with varying degrees of self-renewal and regenerative capacity. In most organs self-renewing tissue-specific stem and progenitor cells contribute to organ maintenance, and it is vital to maintain a functional stem cell pool to preserve organ homeostasis. Various conditions like tissue injury, stress responses, and regeneration challenge the stem cell pool to re-establish homeostasis (Fig. 1). However, with increasing age the functionality of adult stem cells declines and genomic mutations accumulate. These defects affect different cellular response pathways and lead to impairments in regeneration, stress tolerance, and organ function as well as to an increased risk for the development of ageing associated diseases and cancer. Maintenance of the genome appears to be of utmost importance to preserve stem cell function and to reduce the risk of ageing associated dysfunctions and pathologies. In this review, we discuss the causal link between stem cell dysfunction and DNA damage accrual, different strategies how stem cells maintain genome integrity, and how these processes are affected during ageing.

  6. Deterioration mechanisms in air-dry pea seeds during early aging.

    PubMed

    Veselova, Tatiana V; Veselovsky, Vladimir A; Obroucheva, Natalie V

    2015-02-01

    The deteriorative reactions underlying seed aging, namely, lipid peroxidation and non-enzymatic carbohydrate hydrolysis, were studied in pea seeds differing in quality. Aging air-dry seeds were subdivided to three fractions using the application to individual seeds of room temperature phosphorescence. These fractions were strong seeds (fraction I) producing normal seedlings, weak seeds (fraction II) producing mainly abnormal seedlings, and dead seeds (fraction III). Enzymatic processes cannot operate in dry seeds due to the absence of free water, and thus an analytical method was needed that does not require the addition of water. The content of lipid peroxidation products was similar in both strong and weak seeds; this excluded the possibility that lipid peroxidation induced the transition of strong to weak seeds during early aging. Lipid peroxidation was activated only in dying seeds. However, glucose content in weak seeds was much higher than in strong seeds, suggestive of non-enzymatic hydrolysis of carbohydrates, probably of oligosaccharides, which utilized bound water in air-dry seeds. This process resulted in lowered water content in weak seeds. Therefore, associated with deterioration of air-dry seeds during early aging is the non-enzymatic hydrolysis of carbohydrates, whereas lipid peroxidation is not the decisive event.

  7. Environmental pollutants and aging: Investigating and modeling mechanisms of susceptibility in later life.

    EPA Science Inventory

    The rapidly expanding population of older adults raises new concerns over their potential vulnerability to environmental pollutants. Decreases in organ-system function and defenses, coupled with reduced metabolic capacity and clearance, are likely mechanisms for enhanced vulnerab...

  8. Melatonin and the theories of aging: a critical appraisal of melatonin's role in antiaging mechanisms.

    PubMed

    Hardeland, Rüdiger

    2013-11-01

    The classic theories of aging such as the free radical theory, including its mitochondria-related versions, have largely focused on a few specific processes of senescence. Meanwhile, numerous interconnections have become apparent between age-dependent changes previously thought to proceed more or less independently. Increased damage by free radicals is not only linked to impairments of mitochondrial function, but also to inflammaging as it occurs during immune remodeling and by release of proinflammatory cytokines from mitotically arrested, DNA-damaged cells that exhibit the senescence-associated secretory phenotype (SASP). Among other effects, SASP can cause mutations in stem cells that reduce the capacity for tissue regeneration or, in worst case, lead to cancer stem cells. Oxidative stress has also been shown to promote telomere attrition. Moreover, damage by free radicals is connected to impaired circadian rhythmicity. Another nexus exists between cellular oscillators and metabolic sensing, in particular to the aging-suppressor SIRT1, which acts as an accessory clock protein. Melatonin, being a highly pleiotropic regulator molecule, interacts directly or indirectly with all the processes mentioned. These influences are critically reviewed, with emphasis on data from aged organisms and senescence-accelerated animals. The sometimes-controversial findings obtained either in a nongerontological context or in comparisons of tumor with nontumor cells are discussed in light of evidence obtained in senescent organisms. Although, in mammals, lifetime extension by melatonin has been rarely documented in a fully conclusive way, a support of healthy aging has been observed in rodents and is highly likely in humans.

  9. The Role of Educational Aspirations and Expectations in the Discontinuity of Intergenerational Low-Income Status

    ERIC Educational Resources Information Center

    Lee, Jungeun Olivia; Hill, Karl G.; Hawkins, J. David

    2012-01-01

    This study investigated one potential mechanism mediating continuity and discontinuity in low-income status across generations: children's educational aspirations and expectations. Data were drawn from a community sample of 808 participants who were followed from age 10 to 30. Four trajectory groups of children's educational aspirations and…

  10. Calorie restriction lowers body temperature in rhesus monkeys, consistent with a postulated anti-aging mechanism in rodents.

    PubMed Central

    Lane, M A; Baer, D J; Rumpler, W V; Weindruch, R; Ingram, D K; Tilmont, E M; Cutler, R G; Roth, G S

    1996-01-01

    Many studies of caloric restriction (CR) in rodents and lower animals indicate that this nutritional manipulation retards aging processes, as evidenced by increased longevity, reduced pathology, and maintenance of physiological function in a more youthful state. The anti-aging effects of CR are believed to relate, at least in part, to changes in energy metabolism. We are attempting to determine whether similar effects occur in response to CR in nonhuman primates. Core (rectal) body temperature decreased progressively with age from 2 to 30 years in rhesus monkeys fed ad lib (controls) and is reduced by approximately 0.5 degrees C in age-matched monkeys subjected to 6 years of a 30% reduction in caloric intake. A short-term (1 month) 30% restriction of 2.5-year-old monkeys lowered subcutaneous body temperature by 1.0 degrees C. Indirect calorimetry showed that 24-hr energy expenditure was reduced by approximately 24% during short-term CR. The temporal association between reduced body temperature and energy expenditure suggests that reductions in body temperature relate to the induction of an energy conservation mechanism during CR. These reductions in body temperature and energy expenditure are consistent with findings in rodent studies in which aging rate was retarded by CR, now strengthening the possibility that CR may exert beneficial effects in primates analogous to those observed in rodents. PMID:8633033

  11. Ti-Mo alloys employed as biomaterials: effects of composition and aging heat treatment on microstructure and mechanical behavior.

    PubMed

    Cardoso, Flavia F; Ferrandini, Peterson L; Lopes, Eder S N; Cremasco, Alessandra; Caram, Rubens

    2014-04-01

    The correlation between the composition, aging heat treatments, microstructural features and mechanical properties of β Ti alloys is of primary significance because it is the foundation for developing and improving new Ti alloys for orthopedic biomaterials. However, in the case of Ti-Mo alloys, this correlation is not fully described in the literature. Therefore, the purpose of this study was to experimentally investigate the effect of composition and aging heat treatments on the microstructure, Vickers hardness and elastic modulus of Ti-Mo alloys. These alloys were solution heat-treated and water-quenched, after which their response to aging heat treatments was investigated. Their microstructure, Vickers hardness and elastic modulus were evaluated, and the results allow us to conclude that stabilization of the β phase is achieved with nearly 10% Mo when a very high cooling rate is applied. Young's modulus was found to be more sensitive to phase variations than hardness. In all of the compositions, the highest hardness values were achieved by aging at 723K, which was attributed to the precipitation of α and ω phases. All of the compositions aged at 573K, 623K and 723K showed overaging within 80h.

  12. Adaptation of Diaphyseal Structure With Aging and Increased Mechanical Usage in the Adult Rat: A Histomorphometrical and Biomechanical Study

    NASA Technical Reports Server (NTRS)

    Jee, Webster S. S.; Li, Xiao Jian; Schaffler, Mitchell B.

    1991-01-01

    The experimental increase in mechanical usage or overloading of the left hindlimb was produced by immobilization of the contralateral hindlimb. The right hindlimb was placed in a flexed position against the body and was immobilized using an elastic bandage. Some control animals were sacrificed initially at time zero and increased mechanical usage and age-matched control animals were sacrificed after 2, 10, 18, and 26 weeks of treatment. All animals received double bone fluorochrome labeling prior to sacrifice. Cortical bone histomorphometry and cross-sectional moments of inertia were determined. Marrow cavity enlargement and total cross-sectional area expansion represented the age-related cortical bone changes. Increased mechanical usage enhanced periosteal bone modeling in the formation mode and dampened endocortical bone remodeling and bone modeling in the resorption mode (resorption drift) to create a slight positive bone balance. These observations are in general agreement with Frost's postulate for mechanical effects on bone modeling and remodeling. The maximum moment of inertia did not change significantly in either control or overloaded tibial shafts. The minimum and polar moment of inertias in overloaded bones increases over those of controls at 18 and 26 weeks of the experiment.

  13. Adaptation of Diaphyseal Structure with Aging and Increased Mechanical Usage in the Adult Rat: A Histomorphometrical and Biomechanical Study

    NASA Technical Reports Server (NTRS)

    Jee, Webster S. S.; Li, Xiao Jian; Schaffler, Mitchell B.

    1991-01-01

    The experimental increase in mechanical usage or overloading of the left hindlimb was produced by immobilization of the contralateral hindlimb. The right hindlimb was placed in a flexed position against the body and was immobilized using an elastic bandage. Some control animals were sacrificed initially at time zero and increased mechanical usage and age-matched control animals were sacrificed after 2, 10, 18, and 26 weeks of treatment. All animals received double bone fluorochrome labeling prior to sacrifice. Cortical bone histomorphometry and cross-sectional moments of inertia were determined. Marrow cavity enlargement and total cross-sectional area expansion represented the age-related cortical bone changes. Increased mechanical usage enhanced periosteal bone modeling in the formation mode and dampened endocortical bone remodeling and bone modeling in the resorption mode (resorption drift) to create a slight positive bone balance. These observations are in general agreement with Frost's postulate for mechanical effects on bone modeling and remodeling. The maximum moment of inertia did not change significantly in either control or overloaded tibial shafts. The minimum and polar moment of inertias in overloaded bones increases over those of controls at 18 and 26 weeks of the experiment.

  14. Mechanisms of Heavy Metal Sequestration in Soils: Plant-Microbe Interactions and Organic Matter Aging

    SciTech Connect

    Teresa W.-M. Fan; Richard M. Higashi; David Crowley; Andrew N. Lane: Teresa A. Cassel; Peter G. Green

    2004-12-31

    For stabilization of heavy metals at contaminated sites, the three way interaction among soil organic matter (OM)-microbes-plants, and their effect on heavy metal binding is critically important for long-term sustainability, a factor that is poorly understood at the molecular level. Using a soil aging system, the humification of plant matter such as wheat straw was probed along with the effect on microbial community on soil from the former McClellan Air Force Base.

  15. Mechanical properties of silorane-based and methacrylate-based composite resins after artificial aging.

    PubMed

    de Castro, Denise Tornavoi; Lepri, César Penazzo; Valente, Mariana Lima da Costa; dos Reis, Andréa Cândido

    2016-01-01

    The aim of this study was to compare the compressive strength of a silorane-based composite resin (Filtek P90) to that of conventional composite resins (Charisma, Filtek Z250, Fill Magic, and NT Premium) before and after accelerated artificial aging (AAA). For each composite resin, 16 cylindrical specimens were prepared and divided into 2 groups. One group underwent analysis of compressive strength in a universal testing machine 24 hours after preparation, and the other was subjected first to 192 hours of AAA and then the compressive strength test. Data were analyzed by analysis of variance, followed by the Tukey HSD post hoc test (α = 0.05). Some statistically significant differences in compressive strength were found among the commercial brands (P < 0.001). The conventional composite resin Fill Magic presented the best performance before (P < 0.05) and after AAA (P < 0.05). Values for compressive strength of the silorane-based composite were among the lowest obtained, both before and after aging. Comparison of each material before and after AAA revealed that the aging process did not influence the compressive strength of the tested resins (P = 0.785).

  16. Aging, Protein Aggregation, Chaperones, and Neurodegenerative Disorders: Mechanisms of Coupling and Therapeutic Opportunities

    PubMed Central

    Cohen, Ehud

    2012-01-01

    Late onset is a key unifying feature of human neurodegenerative maladies such as Alzheimer’s and Parkinson’s diseases and prion disorders. While sporadic cases typically emerge during the patient’s seventh decade of life or later, mutation-linked, familial cases manifest during the fifth or sixth decade. This common temporal emergence pattern raises the prospect that slowing aging may prevent the accumulation of toxic protein aggregates that lead to the development of these disorders, postpone the onset of these maladies, and alleviate their symptoms once emerged. Invertebrate-based studies indicated that reducing the activity of insulin/IGF signaling (IIS), a prominent aging regulatory pathway, protects from neurodegeneration-linked toxic protein aggregation. The validity of this approach has been tested and confirmed in mammals as reducing the activity of the IGF-1 signaling pathway-protected Alzheimer’s model mice from the behavioral and biochemical impairments associated with the disease. Here I review the recent advances in the field, describe the known mechanistic links between toxic protein aggregation and the aging process, and delineate the future therapeutic potential of IIS reduction as a treatment for various neurodegenerative disorders. PMID:23908845

  17. Aging, protein aggregation, chaperones, and neurodegenerative disorders: mechanisms of coupling and therapeutic opportunities.

    PubMed

    Cohen, Ehud

    2012-10-01

    Late onset is a key unifying feature of human neurodegenerative maladies such as Alzheimer's and Parkinson's diseases and prion disorders. While sporadic cases typically emerge during the patient's seventh decade of life or later, mutation-linked, familial cases manifest during the fifth or sixth decade. This common temporal emergence pattern raises the prospect that slowing aging may prevent the accumulation of toxic protein aggregates that lead to the development of these disorders, postpone the onset of these maladies, and alleviate their symptoms once emerged. Invertebrate-based studies indicated that reducing the activity of insulin/IGF signaling (IIS), a prominent aging regulatory pathway, protects from neurodegeneration-linked toxic protein aggregation. The validity of this approach has been tested and confirmed in mammals as reducing the activity of the IGF-1 signaling pathway-protected Alzheimer's model mice from the behavioral and biochemical impairments associated with the disease. Here I review the recent advances in the field, describe the known mechanistic links between toxic protein aggregation and the aging process, and delineate the future therapeutic potential of IIS reduction as a treatment for various neurodegenerative disorders.

  18. Society's expectations of health

    PubMed Central

    Leach, Edmund

    1975-01-01

    Sir Edmund Leach argues that doctors in the modern world, fortified by the traditional concept that the life of the sick person must at all costs be preserved, are to some extent guilty of the false antitheses current today between youth and age. Moreover youth means health, age illness and senility. Until this imbalance is corrected society will be in danger of `a kind of civil war between the generations'. Society must be taught again that mortality cannot be avoided or conquered by medical science, and at the same time that `health' is not enshrined in the young alone. PMID:1177271

  19. The effect of low temperature aging on the mechanical property & phase stability of Y-TZP ceramics

    PubMed Central

    Kim, Hyung-Tae; Yang, Jae-Ho; Lee, Jai-Bong; Kim, Sung-Hun

    2009-01-01

    STATEMENT OF PROBLEM Recently Yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) has been introduced due to superior flexural strength and fracture toughness compared to other dental ceramic systems. Although zirconia has outstanding mechanical properties, the phenomenon of decrease in the life-time of zirconia resulted from degradation in flexural strength after low temperature aging has been reported. PURPOSE The objective of this study was to investigate degradation of flexural strength of Y-TZP ceramics after various low temperature aging treatments and to evaluate the phase stability and micro-structural change after aging by using X-ray diffraction analysis and a scanning electron microscope (SEM). MATERIAL AND METHODS Y-TZP blocks of Vita In-Ceram YZ (Vita Zahnfabrik, Bad Säckingen, Germany) were prepared in 40 mm (length) × 4 mm (width) × 3 mm (height) samples. Specimens were artificially aged in distilled water by heat-treatment at a temperature of 75, 100, 125, 150, 175, 200, and 225℃ for 10 hours, in order to induce the phase transformation at the surface. To measure the mechanical property, the specimens were subjected to a four-point bending test using a universal testing machine (Instron model 3365; Instron, Canton, Mass, USA). In addition, X-ray diffraction analysis (DMAX 2500; Rigaku, Tokyo, Japan) and SEM (Hitachi s4700; Jeol Ltd, Tokyo, Japan) were performed to estimate the phase transformation. The statistical analysis was done using SAS 9.1.3 (SAS institute, USA). The flexural strength data of the experimental groups were analyzed by one-way analysis of variance and to detect statistically significant differences (α= .05). RESULTS The mean flexural strength of sintered Vita In-Ceram YZ without autoclaving was 798 MPa. When applied aging temperature at below 125℃ for 10 hours, the flexural strength of Vita In-Ceram YZ increased up to 1,161 MPa. However, at above 150℃, the flexural strength started to decrease. Although low

  20. Fracture and mechanical stratigraphy for Mississippian-Pennsylvanian age carbonates, Ozark Dome, NW Arkansas

    NASA Astrophysics Data System (ADS)

    Peppers, M.; Burberry, C. M.

    2014-12-01

    Identifying natural fracture patterns in an area gives a detailed look into the local tectonic history. Comparing those fractures to the mechanical properties of the rocks provides key insights into predicting fractures in the subsurface. The Ozark Dome is an ideal study area for fracture research due to multiple fracturing events resulting from the multi-stage deformation Ouachita Orogeny during the late Paleozoic. This study used field observations of lithology and fracture attributes over ~10 outcrops in the Mississppian-Pennsylvanian (360-298 ma) carbonate sequence of the Ozark Plateau. Outcrops were chosen having excellent lithological exposure up the sequence from the Boone to Atoka formations and with 3D representations of the fracture patterns. In all, the area investigated covered nearly 60 square miles. Fracture attributes collected included fracture intensity, length, and abutting relationships; and rock hardness data collected from a Schmidt Hammer. Data was analyzed using programs such as Stereonet and MOVE structural software that generated rose diagrams, structural cross sections, and products. Initial results indicate 4 main fracture orientations that resulted from at least 3 discrete phases of deformation during the Miss-Penn. Initial results also indicate that the present-day mechanical stratigraphy is not the same one that existed during the deformation phases. Work done at the Tiger Blvd. outcrops showed at least 2 distinct mechanical units. Fractures observed at the outcrop did not respect mechanical bed boundaries, and showed no relationship to the differences in mechanical properties observed. This study will aid in the interpretation of fractures in regards to mechanical stratigraphy, which allows for a better understanding of subsurface fracture prediction in carbonate sequences worldwide. Finally, the fracture work here will also help in elucidating the tectonic history of the field area during the Mississippian and Pennsylvanian.

  1. Effects of alcohol intake on time-based event expectations.

    PubMed

    Kunchulia, Marina; Thomaschke, Roland

    2016-04-01

    Previous evidence suggests that alcohol affects various forms of temporal cognition. However, there are presently no studies investigating whether and how alcohol affects on time-based event expectations. Here, we investigated the effects of alcohol on time-based event expectations. Seventeen healthy volunteers, aged between 19 and 36 years, participated. We employed a variable foreperiod paradigm with temporally predictable events, mimicking a computer game. Error rate and reaction time were analyzed in placebo (0 g/kg), low dose (0.2 g/kg) and high dose (0.6 g/kg) conditions. We found that alcohol intake did not eliminate, but substantially reduced, the formation of time-based expectancy. This effect was stronger for high doses, than for low doses, of alcohol. As a result of our studies, we have evidence that alcohol intake impairs time-based event expectations. The mechanism by which the level of alcohol impairs time-based event expectations needs to be clarified by future research.

  2. Mechanical properties of the tracheal mucosal membrane in the rabbit. I. steady-state stiffness as a function of age.

    PubMed

    Wang, L; Tepper, R; Bert, J L; Pinder, K L; Paré, P D; Okazawa, M

    2000-03-01

    Airway responsiveness is exaggerated in infancy and declines with maturation. These age-related differences (R.S. Tepper, T. Du, A. Styhler, M. Ludwig, and J.G. Martin. Am. J. Respir. Crit. Care Med. 151: 836-840, 1995; R.S. Tepper, S.J. Gunst, C.M. Doerschuk, Y. Shen, and W. Bray. J. Appl. Physiol. 78: 505-512, 1995; R.S. Tepper, J. Stevens, and H. Eigen. Am. J. Respir. Crit. Care Med. 149: 678-681, 1994) could be due to changes in the smooth muscle, the lung, and/or the airway wall. Folding of the mucosal membrane can provide an elastic load (R.K. Lambert, J. Appl. Physiol. 71: 666-673, 1991), which impedes smooth muscle shortening. We hypothesized that increased stiffness of the mucosal membrane occurs during aging, causing an increased mechanical load on airway smooth muscle and a decrease in airway responsiveness. Forty female New Zealand White rabbits between 0.75 and 35 mo of age were studied. Rectangular mucosal membrane strips oriented both longitudinally and circumferentially to the long axis of the trachea were dissected, and the stress-strain relationships of each strip were tested. The results showed that the membrane was stiffer in the longitudinal than in the circumferential direction of the airway. However, there was no significant change with age in either orientation. We conclude that the mechanical properties of the airway mucosal membrane did not change during maturation and were not likely to influence age-related changes in airway responsiveness.

  3. Biomimetic remineralization as a progressive dehydration mechanism of collagen matrices – implications in the aging of resin-dentin bonds

    PubMed Central

    Kim, Young Kyung; Mai, Sui; Mazzoni, Annalisa; Liu, Yan; Tezvergil-Mutluay, Arzu; Takahashi, Kei; Zhang, Kai; Pashley, David H.; Tay, Franklin R.

    2010-01-01

    Biomineralization is a dehydration process in which water from the intrafibrillar compartments of collagen fibrils are progressively replaced by apatites. As water is an important element that precipitates the lack of durability of resin-dentin bonds, this study examined the use of a biomimetic remineralization strategy as a progressive dehydration mechanism for preserving joint integrity and maintaining adhesive strength after aging. Human dentin surfaces were bonded with dentin adhesives, restored with resin composites and sectioned into sticks containing the adhesive joint. Experimental specimens were aged in a biomimetic analog-containing remineralizing medium and control specimens in simulated body fluid for up to 12 months. Specimens retrieved from the designated periods were examined by transmission electron microscopy for manifestation of water-rich regions using a silver tracer and for collagen degradation within the adhesive joints. Tensile testing was performed to determine the potential loss of bond integrity after aging. Control specimens exhibited severe collagen degradation within the adhesive joint after aging. Remineralized specimens exhibited progressive dehydration as manifested by silver tracer reduction and partial remineralization of water-filled micro-channels within the adhesive joint, as well as intrafibrillar remineralization of collagen fibrils that were demineralized initially as part of the bonding procedure. Biomimetic remineralization as a progressive dehydration mechanism of water-rich, resin-sparse collagen matrices enables those adhesive joints to resist degradation over the 12-month aging period, as verified by the conservation of their tensile bond strengths. The ability of the proof-of-concept biomimetic remineralization strategy to prevent bond degradation warrants further development of clinically-relevant delivery systems. PMID:20304110

  4. Classical subjective expected utility

    PubMed Central

    Cerreia-Vioglio, Simone; Maccheroni, Fabio; Marinacci, Massimo; Montrucchio, Luigi

    2013-01-01

    We consider decision makers who know that payoff-relevant observations are generated by a process that belongs to a given class M, as postulated in Wald [Wald A (1950) Statistical Decision Functions (Wiley, New York)]. We incorporate this Waldean piece of objective information within an otherwise subjective setting à la Savage [Savage LJ (1954) The Foundations of Statistics (Wiley, New York)] and show that this leads to a two-stage subjective expected utility model that accounts for both state and model uncertainty. PMID:23559375

  5. Skin mechanics measured in vivo using torsion: a new and accurate model more sensitive to age, sex and moisturizing treatment.

    PubMed

    Salter, D C; McArthur, H C; Crosse, J E; Dickens, A D

    1993-10-01

    Summary Measurements of skin mechanics are required to understand better cracking and flaking of the epidermis and loss of 'elasticity'with age in the dermis. Improvements in torsional testing are described here. The resulting data was fitted to algebraic models, the parameters of which can serve both as a concise description of the responses and as a means of relating them to skin structure and physiology. This investigation looks into the suitability of seven such algebraic models. Five of the models examined here appear to be new. Using the commercially available Dia-Stron DTM Torque Meter with our own software, model parameters were studied as indicators of the effects of age and sex in 41 people, and of skin moisturizing treatments in a further 10 people. The two models in the literature were both found to be substantially less accurate and sensitive representations of experimental data than one of the new models proposed here based on the Weibull distribution. This 'WB model'was consistently the one best able to distinguish differences and detect changes which were statistically significant. The WB model appears to be the most powerful and efficient available. Use of this model makes it possible to demonstrate in vivo a statistically significant mechanical difference between male and pre-menopausal female skin using only one parameter (p= 0.0163, with 18 males and 19 females) and to demonstrate a statistically significant mechanical difference between successive decades of age in female skin using only one parameter (p= 0.0124, n= 24). The two parameters of the model most sensitive to skin structure, function and treatment have been combined to form the axes of a 'Skin condition chart'. Any person can be located on this chart at a point indicating their overall skin condition in mechanical terms and any changes in that condition can be clearly demonstrated by movement across the plot.

  6. Gender and Age-Related Differences in Bilateral Lower Extremity Mechanics during Treadmill Running

    PubMed Central

    Phinyomark, Angkoon; Hettinga, Blayne A.; Osis, Sean T.; Ferber, Reed

    2014-01-01

    Female runners have a two-fold risk of sustaining certain running-related injuries as compared to their male counterparts. Thus, a comprehensive understanding of the sex-related differences in running kinematics is necessary. However, previous studies have either used discrete time point variables and inferential statistics and/or relatively small subject numbers. Therefore, the first purpose of this study was to use a principal component analysis (PCA) method along with a support vector machine (SVM) classifier to examine the differences in running gait kinematics between female and male runners across a large sample of the running population as well as between two age-specific sub-groups. Bilateral 3-dimensional lower extremity gait kinematic data were collected during treadmill running. Data were analysed on the complete sample (n = 483: female 263, male 220), a younger subject group (n = 56), and an older subject group (n = 51). The PC scores were first sorted by the percentage of variance explained and we also employed a novel approach wherein PCs were sorted based on between-gender statistical effect sizes. An SVM was used to determine if the sex and age conditions were separable and classifiable based on the PCA. Forty PCs explained 84.74% of the variance in the data and an SVM classification accuracy of 86.34% was found between female and male runners. Classification accuracies between genders for younger subjects were higher than a subgroup of older runners. The observed interactions between age and gender suggest these factors must be considered together when trying to create homogenous sub-groups for research purposes. PMID:25137240

  7. Molecular ageing of alpha- and Beta-synucleins: protein damage and repair mechanisms.

    PubMed

    Vigneswara, Vasanthy; Cass, Simon; Wayne, Declan; Bolt, Edward L; Ray, David E; Carter, Wayne G

    2013-01-01

    Abnormal α-synuclein aggregates are hallmarks of a number of neurodegenerative diseases. Alpha synuclein and β-synucleins are susceptible to post-translational modification as isoaspartate protein damage, which is regulated in vivo by the action of the repair enzyme protein L-isoaspartyl O-methyltransferase (PIMT). We aged in vitro native α-synuclein, the α-synuclein familial mutants A30P and A53T that give rise to Parkinsonian phenotypes, and β-synuclein, at physiological pH and temperature for a time course of up to 20 days. Resolution of native α-synuclein and β-synuclein by two dimensional techniques showed the accumulation of a number of post-translationally modified forms of both proteins. The levels of isoaspartate formed over the 20 day time course were quantified by exogenous methylation with PIMT using S-Adenosyl-L-[(3)H-methyl]methionine as a methyl donor, and liquid scintillation counting of liberated (3)H-methanol. All α-synuclein proteins accumulated isoaspartate at ∼1% of molecules/day, ∼20 times faster than for β-synuclein. This disparity between rates of isoaspartate was confirmed by exogenous methylation of synucleins by PIMT, protein resolution by one-dimensional denaturing gel electrophoresis, and visualisation of (3)H-methyl esters by autoradiography. Protein silver staining and autoradiography also revealed that α-synucleins accumulated stable oligomers that were resistant to denaturing conditions, and which also contained isoaspartate. Co-incubation of approximately equimolar β-synuclein with α-synuclein resulted in a significant reduction of isoaspartate formed in all α-synucleins after 20 days of ageing. Co-incubated α- and β-synucleins, or α, or β synucleins alone, were resolved by non-denaturing size exclusion chromatography and all formed oligomers of ∼57.5 kDa; consistent with tetramerization. Direct association of α-synuclein with β-synuclein in column fractions or from in vitro ageing co-incubations was

  8. Human aneuploidy: mechanisms and new insights into an age-old problem

    PubMed Central

    Nagaoka, So I.; Hassold, Terry J.; Hunt, Patricia A.

    2012-01-01

    Trisomic and monosomic (aneuploid) embryos account for at least 10% of human pregnancies and, for women nearing the end of their reproductive lifespan, the incidence may exceed 50%. The errors that lead to aneuploidy almost always occur in the oocyte but, despite intensive investigation, the underlying molecular basis has remained elusive. Recent studies of humans and model organisms have shed new light on the complexity of meiotic defects, providing evidence that the age-related increase in errors in the human female is not attributable to a single factor but to an interplay between unique features of oogenesis and a host of endogenous and exogenous factors. PMID:22705668

  9. Affect-regulation expectancies among Gamblers.

    PubMed

    Will Shead, N; Hodgins, David C

    2009-09-01

    Factor scores on a gambling expectancy questionnaire (GEQ) were used to subtype 132 university students who gamble regularly (37.9% male; M age = 22.6 years, SD = 6.04) as: Reward Expectancy Gamblers (Reward EGs)-have strong expectations that gambling augments positive mood, Relief Expectancy Gamblers (Relief EGs)-have strong expectations that gambling relieves negative affect, and Non-Expectancy Gamblers (Non-EGs)-have neither strong expectation. Gambling on a high-low card game was compared across subtypes following priming for either "relief" or "reward" affect-regulation expectancies with the Scrambled Sentence Test (SST). The hypothesized Prime type x GEQ subtype interaction was not significant. When a more stringent set of criteria for GEQ subtyping was imposed, the "purified" sub-sample (n = 54) resulted in the hypothesized statistically significant Prime type x GEQ subtype interaction. Relief EGs gambled more after being primed with the construct "relief of negative emotions" compared to after being primed with the construct "augmentation of positive emotion." Planned orthogonal contrasts showed a significant linear increase in number of bets made across GEQ subtypes when prime type corresponded to GEQ subtype. The results suggest a need for components in gambling treatment programs that address clients' expectancies that gambling can provide a specific desirable emotional outcome.

  10. [Study on effect of astragali radix polysaccharides in improving learning and memory functions in aged rats and its mechanism].

    PubMed

    Yao, Hui; Gu, Li-Jia; Guo, Jian-You

    2014-06-01

    To observe the effect of Astragali Radix polysaccharides (APS) on the learning and memory functions of aged rats, in order to explore its mechanism for improving the learning and memory functions. Natural aging female SD rats were selected in the animal model and randomly divided into the control group, the APS low-dose group (50 mg x kg(-1)), the APS high-dose group (150 mg x kg(-1)) and the piracetam-treated group (560 mg x kg(-1)). They were orally administered with the corresponding drugs for consecutively 60 days. Besides, a young control group was set. The learning and memory functions of the rats were tested by the open-field test and the Morris water maze task. The Western-blot method was used to observe the levels of relevant neural plasticity protein N-methyl-D-aspartate receptor (NMDA receptor) in hippocampus, calcium/calmodulin dependent protein kinase II (CaMK II), protein kinase (PKA), the phosphorylation level of CAMP response element binding protein (CREB) and the protein expression of brain derived neurotrophic factor(BDNF). In this study, the authors found that the learning and memory functions and the hippocampus neural plasticity protein expression of the aged rat group were much lower than that of the young control group (P < 0.01). Compared with the aged rat group, the APS group showed the significant improvement in the impaired learning and memory functions of aged rats and the up-regulation in the hippocampus neural plasticity protein expression. The results showed that APS may improve the learning and memory functions of aged rats by increasing the expressions of relevant neural plasticity proteins.

  11. Temperature, age and crust thickness distributions of Loki Patera on Io: implications for resurfacing mechanism

    NASA Technical Reports Server (NTRS)

    Davies, A. G.

    2003-01-01

    A high-spatial-resolution, multi-wavelength observation by the Galileo NIMS instrument has been analysed to determine the temperature and area distribution of a large portion of the ionian volcano Loki Patera. The temperatures of the cooler components from a two-temperature fit to the data can be used to determine ages of the surface. The age of the floor along a profile across the floor of the caldera ranges from 10 to 80 days. This puts the start of the resurfacing in July/early August 2001, yielding a resurfacing rate of approximately 1 km/day, with the new lava spreading from the SW corner of the caldera in a NE direction. This rate is consistent with resurfacing by foundering of the crust on a lava lake. However,the temperature distribution may also result from the emplacement of flows. Implied crust thicknesses (derived using a lava cooling model) range from 2.6 to 0.9 m.

  12. PSYCHIATRIC DISORDERS AND LEUKOCYTE TELOMERE LENGTH: UNDERLYING MECHANISMS LINKING MENTAL ILLNESS WITH CELLULAR AGING

    PubMed Central

    Lindqvist, Daniel; Epel, Elissa S.; Mellon, Synthia H.; Penninx, Brenda W.; Révész, Dóra; Verhoeven, Josine E.; Reus, Victor I.; Lin, Jue; Mahan, Laura; Hough, Christina M.; Rosser, Rebecca; Bersani, F. Saverio; Blackburn, Elizabeth H.; Wolkowitz, Owen M.

    2015-01-01

    Many psychiatric illnesses are associated with early mortality and with an increased risk of developing physical diseases that are more typically seen in the elderly. Moreover, certain psychiatric illnesses may be associated with accelerated cellular aging, evidenced by shortened leukocyte telomere length (LTL), which could underlie this association. Shortened LTL reflects a cell’s mitotic history and cumulative exposure to inflammation and oxidation as well as the availability of telomerase, a telomere-lengthening enzyme. Critically short telomeres can cause cells to undergo senescence, apoptosis or genomic instability, and shorter LTL correlates with poorer health and predicts mortality. Emerging data suggest that LTL may be reduced in certain psychiatric illnesses, perhaps in proportion to exposure to the psychiatric illnesses, although conflicting data exist. Telomerase has been less well characterized in psychiatric illnesses, but a role in depression and in antidepressant and neurotrophic effects has been suggested by preclinical and clinical studies. In this article, studies on LTL and telomerase activity in psychiatric illnesses are critically reviewed, potential mediators are discussed, and future directions are suggested. A deeper understanding of cellular aging in psychiatric illnesses could lead to re-conceptualizing them as systemic illnesses with manifestations inside and outside the brain and could identify new treatment targets. PMID:25999120

  13. Aging and balance control in response to external perturbations: role of anticipatory and compensatory postural mechanisms.

    PubMed

    Kanekar, Neeta; Aruin, Alexander S

    2014-06-01

    The ability to maintain balance deteriorates with increasing age. Anticipatory and compensatory postural adjustments (APAs and CPAs, respectively), both, are known to be affected in the elderly. We examined the effect of aging on the ability of older adults to utilize APAs and its effect on subsequent control of posture (CPAs). Ten elderly individuals were exposed to external predictable and unpredictable perturbations applied to the upper body in the sagittal plane. Body kinematics, electromyographic activity of 13 muscles, and ground reaction forces were analyzed during the anticipatory and compensatory phases of postural control. The elderly were capable of recognizing an upcoming predictable perturbation and activated muscles prior to it. However, the older adults used different muscle strategies and sequence of muscle recruitment than that reported in young adults. Additionally, when the perturbations were unpredictable, no APAs were seen which resulted in large CPAs and greater peak displacements of the center of pressure (COP) and center of mass (COM) following perturbations. As opposed to this, when the perturbations were predictable, APAs were seen in older adults resulting in significantly smaller CPAs. The presence and utilization of APAs in older adults also improved postural stability following the perturbation as seen by significantly smaller COP and COM peak displacements. Using APAs in older adults significantly reduces the need for large CPAs, resulting in greater postural stability following a perturbation. The results provide a foundation for investigating the role of training in improving the interplay between anticipatory and compensatory postural control in older adults.

  14. AMPA receptor trafficking and the mechanisms underlying synaptic plasticity and cognitive aging.

    PubMed

    Henley, Jeremy M; Wilkinson, Kevin A

    2013-03-01

    Even in healthy individuals there is an inexorable agerelated decline in cognitive function. This is due, in large part, to reduced synaptic plasticity caused by changes in the molecular composition of the postsynaptic membrane. AMPA receptors (AMPARs) are glutamate-gated cation channels that mediate the overwhelming majority of fast excitatory transmission in the brain. Changes in AMPAR number and/or function are a core feature of synaptic plasticity and age-related cognitive decline, AMPARs are highly dynamic proteins that are subject to highly controlled trafficking, recycling, and/or degradation and replacement. This active regulation of AMPAR synthesis, targeting, synaptic dwell time, and degradation is fundamentally important for memory formation and storage. Further, aberrant AMPAR trafficking and consequent detrimental changes in synapses are strongly implicated in many brain diseases, which represent a vast social and economic burden. The purpose of this article is to provide an overview of the molecular and cellular AMPA receptor trafficking events that control synaptic responsiveness and plasticity, and highlight what is known currently known about how these processes change with age and disease.

  15. Psychiatric disorders and leukocyte telomere length: Underlying mechanisms linking mental illness with cellular aging.

    PubMed

    Lindqvist, Daniel; Epel, Elissa S; Mellon, Synthia H; Penninx, Brenda W; Révész, Dóra; Verhoeven, Josine E; Reus, Victor I; Lin, Jue; Mahan, Laura; Hough, Christina M; Rosser, Rebecca; Bersani, F Saverio; Blackburn, Elizabeth H; Wolkowitz, Owen M

    2015-08-01

    Many psychiatric illnesses are associated with early mortality and with an increased risk of developing physical diseases that are more typically seen in the elderly. Moreover, certain psychiatric illnesses may be associated with accelerated cellular aging, evidenced by shortened leukocyte telomere length (LTL), which could underlie this association. Shortened LTL reflects a cell's mitotic history and cumulative exposure to inflammation and oxidation as well as the availability of telomerase, a telomere-lengthening enzyme. Critically short telomeres can cause cells to undergo senescence, apoptosis or genomic instability, and shorter LTL correlates with poorer health and predicts mortality. Emerging data suggest that LTL may be reduced in certain psychiatric illnesses, perhaps in proportion to exposure to the psychiatric illnesses, although conflicting data exist. Telomerase has been less well characterized in psychiatric illnesses, but a role in depression and in antidepressant and neurotrophic effects has been suggested by preclinical and clinical studies. In this article, studies on LTL and telomerase activity in psychiatric illnesses are critically reviewed, potential mediators are discussed, and future directions are suggested. A deeper understanding of cellular aging in psychiatric illnesses could lead to re-conceptualizing them as systemic illnesses with manifestations inside and outside the brain and could identify new treatment targets.

  16. Self-oscillating Vocal Fold Model Mechanics: Healthy, Diseased, and Aging

    NASA Astrophysics Data System (ADS)

    Hiubler, Elizabeth P.; Pollok, Lucas F. E.; Apostoli, Adam G.; Hancock, Adrienne B.; Plesniak, Michael W.

    2014-11-01

    Voice disorders have been estimated to have a substantial economic impact of 2.5 billion annually. Approximately 30% of people will suffer from a voice disorder at some point in their lives. Life-sized, self-oscillating, synthetic vocal fold (VF) models are fabricated to exhibit material properties representative of human VFs. These models are created both with and without a polyp-like structure, a pathology that has been shown to produce rich viscous flow structures not normally observed for healthy VFs during normal phonation. Pressure measurements are acquired upstream of the VFs and high-speed images are captured at varying flow rates during VF oscillation to facilitate an understanding of the characteristics of healthy and diseased VFs. The images are analyzed using a videokymography line-scan technique. Clinically-relevant parameters calculated from the volume-velocity output of a circumferentially-vented mask (Rothenberg mask) are compared to human data collected from two groups of males aged 18-30 and 60-80. This study extends the use of synthetic VF models by assessing their ability to replicate behaviors observed in human subject data to advance a means of investigating changes associated with normal, pathological, and the aging voice. Supported by the GWU Institute for Biomedical Engineering (GWIBE) and GWU Center for Biomimetics and Bioinspired Engineering (COBRE).

  17. The Circadian Timing System: A Recent Addition in the Physiological Mechanisms Underlying Pathological and Aging Processes

    PubMed Central

    Arellanes-Licea, Elvira; Caldelas, Ivette; De Ita-Pérez, Dalia; Díaz-Muñoz, Mauricio

    2014-01-01

    Experimental findings and clinical observations have strengthened the association between physio-pathologic aspects of several diseases, as well as aging process, with the occurrence and control of circadian rhythms. The circadian system is composed by a principal pacemaker in the suprachiasmatic nucleus (SNC) which is in coordination with a number of peripheral circadian oscillators. Many pathological entities such as metabolic syndrome, cancer and cardiovascular events are strongly connected with a disruptive condition of the circadian cycle. Inadequate circadian physiology can be elicited by genetic defects (mutations in clock genes or circadian control genes) or physiological deficiencies (desynchronization between SCN and peripheral oscillators). In this review, we focus on the most recent experimental findings regarding molecular defects in the molecular circadian clock and the altered coordination in the circadian system that are related with clinical conditions such as metabolic diseases, cancer predisposition and physiological deficiencies associated to jet-lag and shiftwork schedules. Implications in the aging process will be also reviewed. PMID:25489492

  18. An integrated approach towards identifying age-related mechanisms of slip initiated falls

    PubMed Central

    Lockhart, Thurmon E.

    2008-01-01

    The causes of slip and fall accidents, both in terms of extrinsic and intrinsic factors and their associations are not yet fully understood. Successful intervention solutions for reducing slip and fall accidents require a more complete understanding of the mechanisms involved. Before effective fall prevention strategies can be put into practice, it is central to examine the chain of events in an accident, comprising the exposure to hazards, initiation of events and the final outcome leading to injury and disability. These events can be effectively identified and analyzed by applying epidemiological, psychophysical, biomechanical and tribological research principles and methodologies. In this manuscript, various methods available to examine fall accidents and their underlying mechanisms are presented to provide a comprehensive array of information to help pinpoint the needs and requirements of new interventions aimed at reducing the risk of falls among the growing elderly population. PMID:17768070

  19. Investigation of path dependence in commercial lithium-ion cells for pure electric bus applications: Aging mechanism identification

    NASA Astrophysics Data System (ADS)

    Ma, Zeyu; Jiang, Jiuchun; Shi, Wei; Zhang, Weige; Mi, Chunting Chris

    2015-01-01

    There is a growing need to provide more realistic and accurate State of Health estimations for batteries in electric vehicles. Thus, it is necessary to research various lithium-ion cell aging processes, including cell degradation and related path dependence. This paper focuses on quantitative analyses of cell aging path dependence in a repeatable laboratory setting, considering the influence of duty cycles, depth of discharge (DOD), and the frequency and severity of the thermal cycle, as reflected in pure electric buses operated in Beijing. Incremental capacity analysis (ICA) and differential voltage analysis (DVA) are applied to infer cell degradation mechanisms and quantify the attributions to capacity fade. It was observed that the cells experienced a higher rate of aging at 80% DOD and an accelerated aging at 40 °C in the thermal cycling, as a result of possible loss of active material (LAM) in both electrodes, in addition to the loss of lithium inventory (LLI) and inhibited kinetics. The slight capacity fade from low-temperature extremes likely caused by LLI due to lithium plating, whereas the noticeable fade after the high-temperature excursion was likely caused by LAM and hindrance to kinetics. These results may lead to improved battery management in EV applications.

  20. New insight into hydration and aging mechanisms of paper by the line shape analysis of proton NMR spectra

    NASA Astrophysics Data System (ADS)

    Mallamace, D.; Vasi, S.; Missori, M.; Corsaro, C.

    2016-05-01

    The action of water within biological systems is strictly linked either with their physical chemical properties and with their functions. Cellulose is one of the most studied biopolymers due to its biological importance and its wide use in manufactured products. Among them, paper is mainly constituted by an almost equimolar ratio of cellulose and water. Therefore the study of the behavior of water within pristine and aged paper samples can help to shed light on the degradation mechanisms that irremediably act over time and spoil paper. In this work we present Nuclear Magnetic Resonance (NMR) experiments on modern paper samples made of pure cellulose not aged and artificially aged as well as on ancient paper samples made in 1413 in Perpignan (France). The line shape parameters of the proton NMR spectra were studied as a function of the hydration content. Results indicate that water in aged samples is progressively involved in the hydration of the byproducts of cellulose degradation. This enhances the degradation process itself through the progressive consumption of the cellulose amorphous regions.

  1. Beyond my wildest expectations.

    PubMed

    Nester, Eugene

    2014-01-01

    With support from my parents, I fulfilled their and my expectations of graduating from college and becoming a scientist. My scientific career has focused on two organisms, Bacillus subtilis and Agrobacterium tumefaciens, and two experimental systems, aromatic amino acid synthesis and DNA transfer in bacteria and plants. Studies on B. subtilis emphasized the genetics and biochemistry of aromatic amino acid synthesis and the characterization of competence in DNA transformation. I carried out both as a postdoc at Stanford with Josh Lederberg. At the University of Washington, I continued these studies and then investigated how Agrobacterium transforms plant cells. In collaboration, Milt Gordon, Mary-Dell Chilton, and I found that this bacterium could transfer a piece of its plasmid into plant cells and thereby modify their properties. This discovery opened up a host of intriguing questions that we have tried to answer over the last 35 years.

  2. Dermal Aged and Fetal Fibroblasts Realign in Response to Mechanical Strain

    NASA Technical Reports Server (NTRS)

    Sawyer, Christine; Grymes, Rose; Alvarez, Teresa (Technical Monitor)

    1994-01-01

    Integrins specifically recognize and bind extracellular matrix components, providing physical anchor points and functional setpoints. Focal adhesion complexes, containing integrin and cytoskeletal proteins, are potential mechanoreceptors, poised to distribute applied forces through the cytoskeleton. Pursuing the hypothesis that cells both perceive and respond to external force, we applied a stretch/relaxation regimen to normal human fetal and aged dermal fibroblast monolayers cultured on flexible membranes. The frequency and magnitude of the applied force is precisely controlled by the Flexercell Unit(Trademark). A protocol of stretch (20% elongation of the monolayer) at a frequency of 6 cycles/min caused a progressive change from a randomly distributed pattern of cells to a symmetric, radial distribution with cells aligned parallel to the applied force. We have coined the term 'orienteering' as the process of active alignment of cells in response to applied force. Cytochalasin D was added in graded doses to investigate the role of the actin cytoskeleton in force perception and transmission. A clear dose response was found; at high concentrations orienteering was abolished; and the drug's impact was reversible. The two cell strains used were similar in their alignment behavior and in their responses to cytochalasin D. Orienteering was influenced by cell density, and the cell strains studied differed in this respect. Fetal cells, unlike their aged counterparts, failed to orient at high cell density. In both cell strains, mid-density cultures aligned rapidly and sparse cultures lagged. These results indicate that both cell-cell adhesion and cytoskeleton integrity are critical in mediating the orienteering response. Differences between these two cell strains may relate to their expression of extracellular matrix molecules (fibronectin, collagen type 1) integrins and their relative binding affinities.

  3. Hardening mechanisms in a dynamic strain aging alloy, Hastelloy X, during isothermal and thermomechanical cyclic deformation

    NASA Technical Reports Server (NTRS)

    Miner, R. V.; Castelli, M. G.

    1992-01-01

    The relative contributions of the hardening mechanisms in Hastelloy X during cyclic deformation were investigated by conducting isothermal cyclic deformation tests within a total strain range of +/-0.3 pct and at several temperatures and strain rates, and thermomechanical tests within several different temperature limits. The results of the TEM examinations and special constant structure tests showed that the precipitation on dislocations of Cr23C6 contributed to hardening, but only after sufficient time above 500 C. Solute drag alone produced very considerable cyclic hardening. Heat dislocation densities, peaking around 10 exp 11 per sq cm, were found to develop at temperatures producing the greatest cyclic hardening.

  4. Understanding the relationship between religiousness, spirituality, and underage drinking: the role of positive alcohol expectancies.

    PubMed

    Sauer-Zavala, Shannon; Burris, Jessica L; Carlson, Charles R

    2014-02-01

    Research has consistently found that religiousness and spirituality are negatively associated with underage drinking. However, there is a paucity of research exploring the mechanisms by which these variables influence this important outcome. With 344 underage young adults (ages 18-20; 61 % women), we investigated positive alcohol expectancies as a mediator between religiousness and spirituality (measured separately) and underage alcohol use. Participants completed the Religious Commitment Inventory-10, Daily Spiritual Experiences Scale, Alcohol Expectancies Questionnaire, and Drinking Styles Questionnaire. Results indicate less positive alcohol expectancies partially mediate the relationship between both religiousness and spirituality and underage alcohol use. This suggests religiousness and spirituality's protective influence on underage drinking is partly due to their influence on expectations about alcohol's positive effects. Since underage drinking predicts problem drinking later in life and places one at risk for serious physical and mental health problems, it is important to identify specific points of intervention, including expectations about alcohol that rise from religious and spiritual factors.

  5. Dietary arachidonic acid as a risk factor for age-associated neurodegenerative diseases: Potential mechanisms.

    PubMed

    Thomas, Mélanie H; Pelleieux, Sandra; Vitale, Nicolas; Olivier, Jean Luc

    2016-11-01

    Alzheimer's disease and associated diseases constitute a major public health concern worldwide. Nutrition-based, preventive strategies could possibly be effective in delaying the occurrence of these diseases and lower their prevalence. Arachidonic acid is the second major polyunsaturated fatty acid (PUFA) and several studies support its involvement in Alzheimer's disease. The objective of this review is to examine how dietary arachidonic acid contributes to Alzheimer's disease mechanisms and therefore to its prevention. First, we explore the sources of neuronal arachidonic acid that could potentially originate from either the conversion of linoleic acid, or from dietary sources and transfer across the blood-brain-barrier. In a second part, a brief overview of the role of the two main agents of Alzheimer's disease, tau protein and Aβ peptide is given, followed by the examination of the relationship between arachidonic acid and the disease. Third, the putative mechanisms by which arachidonic acid could influence Alzheimer's disease occurrence and evolution are presented. The conclusion is devoted to what remains to be determined before integrating arachidonic acid in the design of preventive strategies against Alzheimer's disease and other neurodegenerative diseases.

  6. Autonomous anorthosites of the Anabar Shield: Age, geochemistry, and formation mechanism

    NASA Astrophysics Data System (ADS)

    Glukhovskii, M. Z.; Kuz'min, M. I.; Bayanova, T. B.; Bazhenova, G. N.; Lyalina, L. M.; Serov, P. A.

    2015-10-01

    The new high-accuracy data on U-Pb zircon geochronology, Sm-Nd systematics, and geochemistry of anorthosites of the Anabar Shield are discussed. It is established that anorthosite massifs are composed of gabbro-anorthosites (1.96 Ga old) and oligoclasites (1.93 Ga old) in association with monzodiorites (1.84-1.90 Ga old) and porphyroblastic granites. These rocks were generated in the Archean (3.2-2.7 Ga ago) in the lower crust from quartz-diorite melts under the plume tectonics regime in line with the filterpressing mechanism. The rocks were successively exhumed to upper levels of the crust owing to the Paleoproterozoic impact-triggered process to form a tectonically juxtaposed complementary magmatic complex.

  7. Spectacular reproduction: Ron's Angels and mechanical reproduction in the age of ART (assisted reproductive technology).

    PubMed

    Hafstein, Valdimar Tr

    2007-03-01

    Ron Harris captured the popular imagination in October 1999 with a website where he auctioned off the ova of fashion models to the highest bidder. This article treats the controversy surrounding Harris' site within a dual frame of critical theory's approach to reproduction and a folkloristic approach to discourse. The website fuses traditional narrative motifs and structures with the logic of advertising, seventies television, family-values rhetoric, and the fertility industry. I argue that the great attraction of ronsangels.com is that it put into relief the intervention of mechanical reproduction in human fertility together with the state of genetics at the turn of the 21st century. The result is not only a disconcerting aestheticization and commodification of biological reproduction, but also the biological reproduction of a particular aesthetic and moral code--a generation of reality by model.

  8. Sociology of Low Expectations

    PubMed Central

    Samuel, Gabrielle; Williams, Clare

    2015-01-01

    Social scientists have drawn attention to the role of hype and optimistic visions of the future in providing momentum to biomedical innovation projects by encouraging innovation alliances. In this article, we show how less optimistic, uncertain, and modest visions of the future can also provide innovation projects with momentum. Scholars have highlighted the need for clinicians to carefully manage the expectations of their prospective patients. Using the example of a pioneering clinical team providing deep brain stimulation to children and young people with movement disorders, we show how clinicians confront this requirement by drawing on their professional knowledge and clinical expertise to construct visions of the future with their prospective patients; visions which are personalized, modest, and tainted with uncertainty. We refer to this vision-constructing work as recalibration, and we argue that recalibration enables clinicians to manage the tension between the highly optimistic and hyped visions of the future that surround novel biomedical interventions, and the exigencies of delivering those interventions in a clinical setting. Drawing on work from science and technology studies, we suggest that recalibration enrolls patients in an innovation alliance by creating a shared understanding of how the “effectiveness” of an innovation shall be judged. PMID:26527846

  9. Expectations and speech intelligibility.

    PubMed

    Babel, Molly; Russell, Jamie

    2015-05-01

    Socio-indexical cues and paralinguistic information are often beneficial to speech processing as this information assists listeners in parsing the speech stream. Associations that particular populations speak in a certain speech style can, however, make it such that socio-indexical cues have a cost. In this study, native speakers of Canadian English who identify as Chinese Canadian and White Canadian read sentences that were presented to listeners in noise. Half of the sentences were presented with a visual-prime in the form of a photo of the speaker and half were presented in control trials with fixation crosses. Sentences produced by Chinese Canadians showed an intelligibility cost in the face-prime condition, whereas sentences produced by White Canadians did not. In an accentedness rating task, listeners rated White Canadians as less accented in the face-prime trials, but Chinese Canadians showed no such change in perceived accentedness. These results suggest a misalignment between an expected and an observed speech signal for the face-prime trials, which indicates that social information about a speaker can trigger linguistic associations that come with processing benefits and costs.

  10. Glioblastoma: changing expectations?

    PubMed

    Arribas Alpuente, Leoncio; Menéndez López, Antonio; Yayá Tur, Ricardo

    2011-04-01

    Glioblastoma (GB) represents the most aggressive glioma in the adult population. Despite recent research efforts, the prognosis of patients with GB has remained dismal. Lately, the knowledge of genetic information about gliomagenesis has increased; we even have a classification of the genetic expression of the tumour. The main problem is that at the moment we do not have any therapeutical resources to help us better treat these tumours, as we can do, with others tumours like breast, lung and colorectal cancer. We have also improved on diagnostic imaging, especially with the new MRI sequences; we can now better define the characteristics of the tumour area and the surrounding brain structures, allowing us to adjust resections. Thanks to the most advanced surgery techniques, such as neuronavigation, intraoperative control of the nervous function and the tumour volume, the neurosurgeon is able to complete tumour exeresis with less morbidity. These imaging techniques allow the radiation oncologist to better contour the irradiation target volume, the structures and the organs at risk, to diminish the irradiation of apparently healthy tissue. Nowadays, knowledge of brain stem cells provides new expectations for future treatments. Novel targeted agents such as bevacizumab, imatinib, erlotinib, temsirolimus, immunotherapy, cilengitide, talampanel, etc. are helping classical chemotherapeutic agents, like temozolomide, to achieve an increase in overall survival. The main objective is to improve median overall survival, which is currently between 9 and 12 months, with a good quality of life, measured by the ability to carry out daily life activities.

  11. Morphology, mechanical and thermal oxidative aging properties of HDPE composites reinforced by nonmetals recycled from waste printed circuit boards.

    PubMed

    Yang, Shuangqiao; Bai, Shibing; Wang, Qi

    2016-11-01

    In this study nonmetals recycled from waste printed circuit boards (NPCB) is used as reinforce fillers in high-density polyethylene (HDPE) composites. The morphology, mechanical and thermal oxidative aging properties of NPCB reinforced HDPE composites are assessed and it compared with two other commercial functional filler for the first time. Mechanical test results showed that NPCB could be used as reinforcing fillers in the HDPE composites and mechanical properties especially for stiffness is better than other two commercial fillers. The improved mechanical property was confirmed by the higher aspect ratio and strong interfacial adhesion in scanning electron microscopy (SEM) studies. The heat deflection temperature (HDT) test showed the presence of fiberglass in NPCB can improve the heat resistance of composite for their potential applications. Meanwhile, the oxidation induction time (OIT) and the Fourier transform infrared (FTIR) spectroscopy results showed that NPCB has a near resistance to oxidation as two other commercial fillers used in this paper. The above results show the reuse of NPCB in the HDPE composites represents a promising way for resolving both the environmental pollution and the high-value reuse of resources.

  12. How expectation works: psychologic and physiologic pathways.

    PubMed

    Brown, Walter A

    2015-05-01

    Although expectation has been the most widely studied of the mechanisms that drive the placebo effect, we still don't know how it works. We don't know how the thought that one will respond to a substance in a certain way is converted to symptom relief, intoxication, or airway resistance; the pathway between expectation of a response and the response itself remains uncharted. Nonetheless, in the last decade, brain-imaging studies have begun to uncover this pathway. This paper reviews both long-standing psychologic concepts about the underpinnings of expectation and some of the contemporary brain imaging research, which shows that when expectation alleviates depression, produces pain relief or improves parkinsonian symptoms, these effects come with relevant changes in brain activity and chemistry. These findings oblige us to reevaluate some of the traditional common sense notions of how expectation brings about its effects and how placebos work.

  13. Shallow groundwater recharge mechanism and apparent age in the Ndop plain, northwest Cameroon

    NASA Astrophysics Data System (ADS)

    Wirmvem, Mengnjo Jude; Mimba, Mumbfu Ernestine; Kamtchueng, Brice Tchakam; Wotany, Engome Regina; Bafon, Tasin Godlove; Asaah, Asobo Nkengmatia Elvis; Fantong, Wilson Yetoh; Ayonghe, Samuel Ndonwi; Ohba, Takeshi

    2015-02-01

    Knowledge of groundwater recharge and apparent age constitutes a valuable tool for its sustainable management. Accordingly, shallow groundwater (n = 72) in the Ndop plain has been investigated using the stable isotopes of oxygen (18O) and hydrogen (2H or D) and tritium (3H) to determine the recharge process, timing and rate of recharge, and residence time. The shallow groundwater showed low variability in δ18O values (-2.7 to -4.1 ‰) and 3H content (2.4-3.1 TU). The low variability suggests a similar origin, homogenous aquifer, good water mixing and storage capacity of the groundwater reservoir. Like surface water, a cluster of groundwater along the Ndop Meteoric Water Line (NMWL) and Global Meteoric Water Line indicates meteoric origin/recharge. The rainfall recharge occurs under low relative humidity conditions and negligible evaporation effect. About 80 % of the recharge is from direct heterogeneous/diffuse local precipitation at low altitude (<1,260 m) within the Ndop plain. Approximately 20 % is from high altitude precipitation (localised recharge) or is recharged by the numerous inflowing streams and rivers from high elevations. A homogenous cluster of δ-values in groundwater (and surface water) between May and June monsoon rains on the NMWL suggests dominant recharge during these months. The recharge represents at least 16 % (>251 mm) of the annual rainfall (1,540 mm) indicating high annual recharge; high enough for development of the groundwater resource for agriculture. The 3H content (>2.4 TU) in groundwater indicates post-1952 recharged water with an estimated residence time <30 years, suggesting short subsurface circulation, and subsequently a renewable aquifer.

  14. The effect of ageing on the mechanical properties of the silk of the bridge spider Larinioides cornutus (Clerck, 1757)

    NASA Astrophysics Data System (ADS)

    Lepore, Emiliano; Isaia, Marco; Mammola, Stefano; Pugno, Nicola

    2016-05-01

    Spider silk is regarded as one of the best natural polymer fibers especially in terms of low density, high tensile strength and high elongation until breaking. Since only a few bio-engineering studies have been focused on spider silk ageing, we conducted nano-tensile tests on the vertical naturally spun silk fibers of the bridge spider Larinioides cornutus (Clerck, 1757) (Arachnida, Araneae) to evaluate changes in the mechanical properties of the silk (ultimate stress and strain, Young’s modulus, toughness) over time. We studied the natural process of silk ageing at different time intervals from spinning (20 seconds up to one month), comparing silk fibers spun from adult spiders collected in the field. Data were analyzed using Linear Mixed Models. We detected a positive trend versus time for the Young’s modulus, indicating that aged silks are stiffer and possibly less effective in catching prey. Moreover, we observed a negative trend for the ultimate strain versus time, attesting a general decrement of the resistance force. These trends are interpreted as being due to the drying of the silk protein chains and the reorientation among the fibers.

  15. The combined effect of dismantling for steam sterilization and aging on the accuracy of spring-style mechanical torque devices

    PubMed Central

    Mahshid, Minoo; Sadr, Seyed Jalil; Fayyaz, Ali; Kadkhodazadeh, Mahdi

    2013-01-01

    Purpose This study aimed to assess the combined effect of dismantling before sterilization and aging on the accuracy (±10% of the target torque) of spring-style mechanical torque devices (S-S MTDs). Methods Twenty new S-SMTDs from two different manufacturers (Nobel Biocare and Straumann: 10 of each type) were selected and divided into two groups, namely, case (group A) and control (group B). For sterilization, 100 cycles of autoclaving were performed in 100 sequences. In each sequence, 10 repetitions of peak torque values were registered for aging. To measure and assess the output of each device, a Tohnichi torque gauge was used (P<0.05). Results Before steam sterilization, all of the tested devices stayed within 10% of their target values. After 100 cycles of steam sterilization and aging with or without dismantling of the devices, the Nobel Biocare devices stayed within 10% of their target torque. In the Straumann devices, despite the significant difference between the peak torque and target torque values, the absolute error values stayed within 10% of their target torque. Conclusion Within the limitations of this study, there was no significant difference between the mean and absolute value of error between Nobel Biocare and Straumann S-S MTDs. PMID:24236244

  16. Mechanism of inflammation in age-related macular degeneration: an up-to-date on genetic landmarks.

    PubMed

    Parmeggiani, Francesco; Sorrentino, Francesco S; Romano, Mario R; Costagliola, Ciro; Semeraro, Francesco; Incorvaia, Carlo; D'Angelo, Sergio; Perri, Paolo; De Nadai, Katia; Bonomo Roversi, Elia; Franceschelli, Paola; Sebastiani, Adolfo; Rubini, Michele

    2013-01-01

    Age-related macular degeneration (AMD) is the most common cause of irreversible visual impairment among people over 50 years of age, accounting for up to 50% of all cases of legal blindness in Western countries. Although the aging represents the main determinant of AMD, it must be considered a multifaceted disease caused by interactions among environmental risk factors and genetic backgrounds. Mounting evidence and/or arguments document the crucial role of inflammation and immune-mediated processes in the pathogenesis of AMD. Proinflammatory effects secondary to chronic inflammation (e.g., alternative complement activation) and heterogeneous types of oxidative stress (e.g., impaired cholesterol homeostasis) can result in degenerative damages at the level of crucial macular structures, that is photoreceptors, retinal pigment epithelium, and Bruch's membrane. In the most recent years, the association of AMD with genes, directly or indirectly, involved in immunoinflammatory pathways is increasingly becoming an essential core for AMD knowledge. Starting from the key basic-research notions detectable at the root of AMD pathogenesis, the present up-to-date paper reviews the best-known and/or the most attractive genetic findings linked to the mechanisms of inflammation of this complex disease.

  17. The effect of ageing on the mechanical properties of the silk of the bridge spider Larinioides cornutus (Clerck, 1757)

    PubMed Central

    Lepore, Emiliano; Isaia, Marco; Mammola, Stefano; Pugno, Nicola

    2016-01-01

    Spider silk is regarded as one of the best natural polymer fibers especially in terms of low density, high tensile strength and high elongation until breaking. Since only a few bio-engineering studies have been focused on spider silk ageing, we conducted nano-tensile tests on the vertical naturally spun silk fibers of the bridge spider Larinioides cornutus (Clerck, 1757) (Arachnida, Araneae) to evaluate changes in the mechanical properties of the silk (ultimate stress and strain, Young’s modulus, toughness) over time. We studied the natural process of silk ageing at different time intervals from spinning (20 seconds up to one month), comparing silk fibers spun from adult spiders collected in the field. Data were analyzed using Linear Mixed Models. We detected a positive trend versus time for the Young’s modulus, indicating that aged silks are stiffer and possibly less effective in catching prey. Moreover, we observed a negative trend for the ultimate strain versus time, attesting a general decrement of the resistance force. These trends are interpreted as being due to the drying of the silk protein chains and the reorientation among the fibers. PMID:27156712

  18. Possible mechanism underlying the effect of Heshouwuyin, a tonifying kidney herb, on sperm quality in aging rats

    PubMed Central

    2014-01-01

    Background Herb mixtures are used as alternatives to hormone therapy in China for the treatment of partial androgen deficiency in aging men. However, the compositions of these herb mixtures are complex and their mechanisms are often unknown. This study investigates the effect of Heshouwuyin, a Chinese herbal compound for invigorating the kidney, on the control of testosterone secretion and sperm function. Methods Aged Wistar rats were administered with Heshouwuyin. A Shouwu pill group and young group were used as controls. Results Morphology, chemiluminescence, fluorescence immunohistochemistry, and western blot showed that the epididymal sperm of naturally aged rats had intact plasma membranes. They also had abnormal mitochondrial function and DNA integrity, a significant decline in serum testosterone levels, and significant pathological changes in the structure of testicular tissues. Heshouwuyin significantly improved sperm function and serum testosterone levels, and improved testicular morphology. Moreover, the curative efficacy of Heshouwuyin after 60 days was better than that of Heshouwuyin after 30 days and the Shouwu pill group. Conclusion Heshouwuyin exerts an important role in controlling testosterone secretion and sperm function. PMID:25034094

  19. Effects of aging procedures on the molecular, biochemical, morphological, and mechanical properties of vacuum-formed retainers.

    PubMed

    Ahn, Hyo-Won; Ha, Hye-Ryun; Lim, Ho-Nam; Choi, Samjin

    2015-11-01

    The influence of intraoral exposure procedures on the physical characteristics of thermoplastic vacuum-formed retainers (VFRs) is still unclear. The effects of thermoforming and intraoral use on the molecular, chemical, morphological, and mechanical properties of thermoplastic VFRs were investigated. VFRs with a 0.8-mm-thick thermoplastic PETG sheet acquired from 48 patients were investigated with two aging procedures, including vacuum forming and intraoral exposure, for 2-week and 6-month. Eight evaluating sites for thermoplastic VFRs were assessed with seven analytical techniques. LM, SEM, and AFM microscopic findings showed that the surface characteristics increased with increasing in vivo exposure time (a four-fold increase) and varied depending on the sites evaluated (an occlusal surface). Raman and EDX spectroscopic findings showed that aging procedures led to a significant change in the molecular composition of VFRs, leading to a decrease in the composition rate of carbon (C) and the presence of silicon (Si), phosphorus (P), and calcium (Ca). Compressive strength and tensile tests showed that aging procedures led to a significant increase (P<0.01) in ultimate tensile strength, elastic modulus, the stored energy at a 6-mm deflection (u6 mm), and the compressed load at a 3-mm deflection (σ3 mm). Thermoforming led to a smoother surface and no crystallization of PETG sheets. Intraoral exposure accelerated changes in surface morphology, tensile strength, and elastic modulus of VFRs. This change was site-specific and enhanced with an increase in intraoral exposure time. Therefore, thermoforming and in vivo oral exposure procedures led to the molecular, morphological, and mechanical properties of thermoplastic VFRs.

  20. Major League Baseball Players’ Life Expectancies*

    PubMed Central

    Saint Onge, Jarron M.; Rogers, Richard G.; Krueger, Patrick M.

    2009-01-01

    Objective We examine the importance of anthropometric and performance measures, and age, period, and cohort effects in explaining life expectancies among major league baseball (MLB) players over the past century. Methods We use discrete time hazard models to calculate life tables with covariates with data from Total Baseball, a rich source of information on all players who played in the major league. Results Compared to 20-year-old U.S. males, MLB players can expect almost five additional years of life. Height, weight, handedness, and player ratings are unassociated with the risk of death in this population of highly active and successful adults. Career length is inversely associated with the risk of death, likely because those who play longer gain additional incomes, physical fitness, and training. Conclusions Our results indicate improvements in life expectancies with time for all age groups and indicate possible improvements in longevity in the general U.S. population. PMID:19756205

  1. Better options for work and retirement: some suggestions for improving economic security mechanisms for old age.

    PubMed

    Chen, Y P

    1988-01-01

    After identifying the income security system as a tripod structure symbolizing the efforts of the individual, the employer, and the government, the first section of this chapter suggested that economic security is a broader concept than income security, since a person is concerned not only with the acquisition of income and assets but also with the retention and disposal of them. Factors such as health care expenditures, housing and living arrangements, service delivery, and support networks affect income and asset retention. Both acquisition and retention of income and assets, furthermore, are influenced by macroeconomic policies. This section also discussed the possibility that the role of the individual in providing economic security may be underestimated. In the second section, the heterogeneity of older persons was demonstrated in terms of both income sources and the relative importance of these sources to persons in different income classes. Social Security declines in importance as income level rises, whereas assets and employment as sources of income increase with income levels. Occupational pensions are of minimal importance to persons in the lowest-income class. Though more important to persons in the higher-income classes, occupational pensions as a proportion to their total income lie between 10% and 20% for these groups. By definition, public assistance is important only to the lowest-income class. During the last two decades, the relative importance of these income sources has changed, as pointed out in the third section, which also speculated on their future roles. The fourth section proposed possible ways of improving the five income security mechanisms: to provide more child-care credit for women under Social Security, to strengthen portability under private pension plans, to make IRAs more accessible and more meaningful for retirement purposes, to enhance the role of employment for adults, and to raise SSI so as to eliminate poverty. The chapter

  2. Expectations predict chronic pain treatment outcomes.

    PubMed

    Cormier, Stéphanie; Lavigne, Geneviève L; Choinière, Manon; Rainville, Pierre

    2016-02-01

    Accumulating evidence suggests an association between patient pretreatment expectations and numerous health outcomes. However, it remains unclear if and how expectations relate to outcomes after treatments in multidisciplinary pain programs. The present study aims at investigating the predictive association between expectations and clinical outcomes in a large database of chronic pain patients. In this observational cohort study, participants were 2272 patients treated in one of 3 university-affiliated multidisciplinary pain treatment centers. All patients received personalized care, including medical, psychological, and/or physical interventions. Patient expectations regarding pain relief and improvements in quality of life and functioning were measured before the first visit to the pain centers and served as predictor variables. Changes in pain intensity, depressive symptoms, pain interference, and tendency to catastrophize, as well as satisfaction with pain treatment and global impressions of change at 6-month follow-up, were considered as treatment outcomes. Structural equation modeling analyses showed significant positive relationships between expectations and most clinical outcomes, and this association was largely mediated by patients' global impressions of change. Similar patterns of relationships between variables were also observed in various subgroups of patients based on sex, age, pain duration, and pain classification. Such results emphasize the relevance of patient expectations as a determinant of outcomes in multimodal pain treatment programs. Furthermore, the results suggest that superior clinical outcomes are observed in individuals who expect high positive outcomes as a result of treatment.

  3. Expected and Experienced Pain Levels in Electromyography

    PubMed Central

    YALINAY DİKMEN, Pınar; ILGAZ AYDINLAR, Elif; KARLIKAYA, Geysu

    2013-01-01

    Introduction The aim of the present study was to assess pain using a visual analogue scale (VAS) in patients awaiting an EMG procedure (i.e., expected VAS) and after an EMG procedure (i.e., experienced VAS). Methods Expected and experienced pain in response to nerve conduction studies (NCS) and needle EMG were assessed in 108 patients (61 females, 47 males; mean age 43.2±11.6) using a VAS. Results No significant correlations were noted between the expected or the experienced VAS in response to EMG and demographic features of the patients. The expected VAS was significantly higher than the experienced VAS in response to needle EMG (p=0.005). The highest VAS level was noted in the expected VAS in response to needle EMG (4.7±2.2). The lowest VAS level was noted in the experienced VAS in response to NCS (3.6±2.5). Conclusion The present study demonstrated that neither the expected nor the experienced pain associated with EMG exceeded a moderate level. Interestingly, we found that expected pain levels in response to needle EMG were significantly higher than experienced pain levels. Therefore, it may be possible to increase compliance if patients are provided with this information before undergoing electrophysiological procedures.

  4. Effect of heterogeneous precipitation on age-hardening of Al{sub 2}O{sub 3} particle dispersion Al-4mass% Cu composite produced by mechanical alloying

    SciTech Connect

    Arakawa, S.; Hatayama, T.; Matsugi, K.; Yanagisawa, O.

    2000-04-14

    The acceleration of aging kinetics has been frequently observed in aluminum matrix composites produced by ingot or powder metallurgy. Recently, in the mechanically alloyed (MA) Al-4mass%Cu/Al{sub 2}O{sub 3} composites, the authors have found that the age-hardening response significantly decreases, and that considerable stable {theta} phases are formed at a very short aging time. The purposes of this study are to investigate the local precipitation behaviors, and attempt to clarify the dominant microstructural factors of the decrease in the age-harden ability and the acceleration of the age-hardening kinetics in the Al{sub 2}O{sub 3} particle dispersion Al-4mass%Cu composites produced by mechanical alloying. In order to build a basis for comparison, the age-hardening behaviors of the unreinforced matrix alloy (IM alloy), which is produced by ingot metallurgy technique, are also investigated.

  5. Microstructural and compositional contributions towards the mechanical behavior of aging human bone measured by cyclic and impact reference point indentation.

    PubMed

    Abraham, Adam C; Agarwalla, Avinesh; Yadavalli, Aditya; Liu, Jenny Y; Tang, Simon Y

    2016-06-01

    The assessment of fracture risk often relies primarily on measuring bone mineral density, thereby accounting for only a single pathology: the loss of bone mass. However, bone's ability to resist fracture is a result of its biphasic composition and hierarchical structure that imbue it with high strength and toughness. Reference point indentation (RPI) testing is designed to directly probe bone mechanical behavior at the microscale in situ, although it remains unclear which aspects of bone composition and structure influence the results at this scale. Therefore, our goal in this study was to investigate factors that contribute to bone mechanical behavior measured by cyclic reference point indentation, impact reference point indentation, and three-point bending. Twenty-eight female cadavers (ages 57-97) were subjected to cyclic and impact RPI in parallel at the unmodified tibia mid-diaphysis. After RPI, the middiaphyseal tibiae were removed, scanned using micro-CT to obtain cortical porosity (Ct.Po.) and tissue mineral density (TMD), then tested using three-point bending, and lastly assayed for the accumulation of advanced glycation end-products (AGEs). Both the indentation distance increase from cyclic RPI (IDI) and bone material strength index from impact RPI (BMSi) were significantly correlated with TMD (r=-0.390, p=0.006; r=0.430, p=0.002; respectively). Accumulation of AGEs was significantly correlated with IDI (r=0.281, p=0.046), creep indentation distance (CID, r=0.396, p=0.004), and BMSi (r=-0.613, p<0.001). There were no significant relationships between tissue TMD or AGEs accumulation with the quasi-static material properties. Toughness decreased with increasing tissue Ct.Po. (r=-0.621, p<0.001). Other three-point bending measures also correlated with tissue Ct.Po. including the bending modulus (r=-0.50, p<0.001) and ultimate stress (r=-0.56, p<0.001). The effects of Ct.Po. on indentation were less pronounced with IDI (r=0.290, p=0.043) and BMSi (r=-0.299, p

  6. Does benign paroxysmal positional vertigo explain age and gender variation in patients with vertigo by mechanical assistance maneuvers?

    PubMed

    Wang, Jing; Chi, Fang-Lu; Jia, Xian-Hao; Tian, Liang; Richard-Vitton, Th

    2014-11-01

    Benign paroxysmal positional vertigo (BPPV) is one of the most common peripheral vestibular diseases. The aim of this study was to explore the prevalence of BPPV in vertigo patients and the characteristics of BPPV in diagnosis and repositioning using mechanical assistance maneuvers and to analyze and summarize the reasons showing these characteristics. Seven hundred and twenty-six patients with vertigo were enrolled in this study. All patients were inspected by TRV armchair (SYNAPSYS, model TRV, France). BPPV patients were identified by the examination results. The characteristics and results using TRV armchair in diagnosis and treatment of BPPV were compared and analyzed. Of 726 vertigo patients, 209 BPPV patients were diagnosed, including 58 men and 151 women, aged from 16 to 87 (mean 52.90 ± 11.93) years. There were significant differences in the proportion of BPPV in male and female vertigo patients (P = 0.0233), but no differences among all age groups (P = 0.3201). Of 209 BPPV patients, 208 cases were repositioned by TRV armchair and no one appeared to have otolithic debris relocated into another canal in the repositioning procedures. 202 cases (97.12 %) were successful and six cases (2.87 %) were effective. None of them failed. This study suggests that BPPV is one of the most common diseases in the young vertigo patients, just like that in the old ones. Female of the species has predilection for BPPV and the site of predilection is the right posterior semicircular canals (PC-BPPV). The results of repositioning are perfect using mechanical assistance maneuvers.

  7. Mechanical behavior of a Y-TZP ceramic for monolithic restorations: effect of grinding and low-temperature aging.

    PubMed

    Pereira, G K R; Silvestri, T; Camargo, R; Rippe, M P; Amaral, M; Kleverlaan, C J; Valandro, L F

    2016-06-01

    This study aimed to investigate the effects of grinding with diamond burs and low-temperature aging on the mechanical behavior (biaxial flexural strength and structural reliability), surface topography, and phase transformation of a Y-TZP ceramic for monolithic dental restorations. Disc-shaped specimens (Zirlux FC, Ivoclar Vivadent) were manufactured according to ISO 6872 (2008) and divided in accordance with two factors: "grinding - 3 levels" and "LTD - 2 levels". Grinding was performed using a contra-angle handpiece under constant water-cooling with different grit-sizes (extra-fine and coarse diamond burs). LTD was simulated in an autoclave at 134°C, under a pressure of 2 bar, over a period of 20h. Surface topography analysis showed an increase in roughness based on surface treatment grit-size (Coarse>Xfine>Ctrl), LTD did not influence roughness values. Both grinding and LTD promoted an increase in the amount of m-phase, although different susceptibilities to degradation were observed. According to existing literature the increase of m-phase content is a direct indicative of Y-TZP degradation. Weibull analysis showed an increase in characteristic strength after grinding (Coarse=Xfine>Ctrl), while for LTD, distinct effects were observed (Ctrlaging in autoclave for 20h (LTD) and grinding showed not to be detrimental to the mechanical properties of Zirlux FC Y-TZP ceramic.

  8. Neuro-oscillatory mechanisms of intersensory selective attention and task switching in school-aged children, adolescents and young adults.

    PubMed

    Murphy, Jeremy W; Foxe, John J; Molholm, Sophie

    2016-05-01

    The ability to attend to one among multiple sources of information is central to everyday functioning. Just as central is the ability to switch attention among competing inputs as the task at hand changes. Such processes develop surprisingly slowly, such that even into adolescence, we remain slower and more error prone at switching among tasks compared to young adults. The amplitude of oscillations in the alpha band (~8-14 Hz) tracks the top-down deployment of attention, and there is growing evidence that alpha can act as a suppressive mechanism to bias attention away from distracting sensory input. Moreover, the amplitude of alpha has also been shown to be sensitive to the demands of switching tasks. To understand the neural basis of protracted development of these executive functions, we recorded high-density electrophysiology from school-aged children (8-12 years), adolescents (13-17), and young adults (18-34) as they performed a cued inter-sensory selective attention task. The youngest participants showed increased susceptibility to distracting inputs that was especially evident when switching tasks. Concordantly, they showed weaker and delayed onset of alpha modulation compared to the older groups. Thus the flexible and efficient deployment of alpha to bias competition among attentional sets remains underdeveloped in school-aged children.

  9. Measuring Alcohol Expectancies in Youth

    ERIC Educational Resources Information Center

    Randolph, Karen A.; Gerend, Mary A.; Miller, Brenda A.

    2006-01-01

    Beliefs about the consequences of using alcohol, alcohol expectancies, are powerful predictors of underage drinking. The Alcohol Expectancies Questionnaire-Adolescent form (AEQ-A) has been widely used to measure expectancies in youth. Despite its broad use, the factor structure of the AEQ-A has not been firmly established. It is also not known…

  10. Cause-specific life expectancies after 35 years of age for human immunodeficiency syndrome-infected and human immunodeficiency syndrome-negative individuals followed simultaneously in long-term cohort studies, 1984-2008.

    PubMed

    Wada, Nikolas; Jacobson, Lisa P; Cohen, Mardge; French, Audrey; Phair, John; Muñoz, Alvaro

    2013-01-15

    Parametric and semiparametric competing risks methods were used to estimate proportions, timing, and predictors of acquired immune deficiency syndrome (AIDS)-related and non-AIDS-related mortality among individuals both positive and negative for the human immunodeficiency syndrome (HIV) in the Multicenter AIDS Cohort Study (MACS) and Women's Interagency HIV Study (WIHS) from 1984 to 2008 and 1996 to 2008, respectively. Among HIV-positive MACS participants, the proportion of deaths unrelated to AIDS increased from 6% before the introduction of highly active antiretroviral therapy (HAART) (before 1996) to 53% in the HAART era (P < 0.01); the median age of persons who died from non-AIDS-related causes after age 35 years increased from 49.0 to 66.0 years (P < 0.01). In both cohorts during the HAART era, median ages at time of non-AIDS-related death were younger for HIV-positive individuals than for comparable HIV-negative individuals (8.7 years younger in MACS (P < 0.01) and 7.6 years younger in WIHS (P < 0.01)). In a multivariate proportional cause-specific hazards model, unemployment (for non-AIDS death, hazard ratio (HR) = 1.8; for AIDS death, HR = 2.3), depression (for non-AIDS death, HR = 1.4; for AIDS death, HR = 1.4), and hepatitis B or C infection (for non-AIDS death, HR = 1.8, for AIDS death; HR = 1.4) were significantly (P < 0.05) associated with higher hazards of both non-AIDS and AIDS mortality among HIV-positive individuals in the HAART era, independent of study cohort. The results illuminate the changing face of mortality among the growing population infected with HIV.

  11. The Importance of Specifying and Studying Causal Mechanisms in School-Based Randomised Controlled Trials: Lessons from Two Studies of Cross-Age Peer Tutoring

    ERIC Educational Resources Information Center

    Morris, Stephen P.; Edovald, Triin; Lloyd, Cheryl; Kiss, Zsolt

    2016-01-01

    Based on the experience of evaluating 2 cross-age peer-tutoring interventions, we argue that researchers need to pay greater attention to causal mechanisms within the context of school-based randomised controlled trials. Without studying mechanisms, researchers are less able to explain the underlying causal processes that give rise to results from…

  12. Mechanical properties and the structure of chromium-zirconium bronze after dynamic channel-angular pressing and subsequent aging

    NASA Astrophysics Data System (ADS)

    Zel'dovich, V. I.; Dobatkin, S. V.; Frolova, N. Yu.; Khomskaya, I. V.; Kheifets, A. E.; Shorokhov, E. V.; Nasonov, P. A.

    2016-01-01

    Changes in the structure and mechanical properties of the low-alloy chromium-zirconium bronze Cu-0.14% Cr-0.04% Zr have been investigated after a high-strain-rate (104-105 s-1) deformation by the method of dynamic channel-angular pressing (DCAP) and following annealings at 300-700°C. A significant increase in the mechanical properties of the investigated bronze after DCAP and after DCAP and subsequent aging at temperatures of 400-450°C has been established. Thus, compared to the initial quenched state the ultimate tensile strength increases by a factor of 2.6 and 2.8 and the yield stress, by a factor of 3.3 and 5.1, respectively, with the retention of satisfactory plasticity. It has been shown that, upon DCAP and subsequent annealings, in the low-alloyed bronze under investigation there occurs a decomposition of the α solid solution with the precipitation of nanosized particles. This leads to a significant strengthening of the bronze and to an increase in its thermal stability compared with the pure copper subjected to DCAP.

  13. Effect of Natural Aging and Cold Working on Microstructures and Mechanical Properties of Al-4.6Cu-0.5Mg-0.5Ag alloy

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Te; Lee, Sheng-Long; Bor, Hui-Yun; Lin, Jing-Chie

    2013-06-01

    This research investigates the effects of natural aging and cold working prior to artificial aging on microstructures and mechanical properties of Al-4.6Cu-0.5Mg-0.5Ag alloy. Mechanical properties relative to microstructure variations were elucidated by the observations of the optical microscope (OM), differential scanning calorimeter (DSC), electrical conductivity meter (pct IACS), and transmission electron microscopy (TEM). The results showed that natural aging treatment has little noticeable benefit on the quantity of precipitation strengthening phases and mechanical properties, but it increases the precipitation strengthening rate at the initial stage of artificial aging. Cold working brings more lattice defects which suppress Al-Cu (GP zone) and Mg-Ag clustering, and therefore the precipitation of Ω phase decreases. Furthermore, more dislocations are formed, leading to precipitate the more heterogeneous nucleation of θ' phase. The above-mentioned precipitation phenomena and strain hardening effect are more obvious with higher degrees of cold working.

  14. Effects of aging on the structural, mechanical, and thermal properties of the silicone rubber current transformer insulation bushing for a 500 kV substation.

    PubMed

    Wang, Zhigao; Zhang, Xinghai; Wang, Fangqiang; Lan, Xinsheng; Zhou, Yiqian

    2016-01-01

    In order to analyze the cracking and aging reason of the silicone rubber current transformer (CT) insulation bushing used for 8 years from a 500 kV alternating current substation, characteristics including Fourier transform infrared (FTIR) spectroscopy, mechanical properties analysis, hardness, and thermo gravimetric analysis have been carried out. The FTIR results indicated that the external surface of the silicone rubber CT insulation bushing suffered from more serious aging than the internal part, fracture of side chain Si-C bond was much more than the backbone. Mechanical properties and thermal stability results illustrated that the main aging reasons were the breakage of side chain Si-C bond and the excessive cross-linking reaction of the backbone. This study can provide valuable basis for evaluating degradation mechanism and aging state of the silicone rubber insulation bushing in electric power field.

  15. A multistate analysis of active life expectancy.

    PubMed

    Rogers, A; Rogers, R G; Branch, L G

    1989-01-01

    With today's lower mortality rates, longer expectations of life, and new medical technologies, the nation's health policy focus has shifted from emphasis on individual survival to emphasis on personal health and independent living. Using longitudinal data sets and new methodological techniques, researchers have begun to assess active life expectancies, estimating not only how long a subpopulation can expect to live beyond each age, but what fractions of the expected remaining lifetime will be lived as independent, dependent, or institutionalized. New ideas are addressed, applying recently developed multistate life table methods to Waves One and Two of the Massachusetts Health Care Panel Study. Expectations of active life are presented for those 65 and older who initially are in one of two functional states of well-being. Included are expectations of life, for those, for example, who were independent and remained so, or those who were dependent and became independent. Although public health officials are concerned about the number of elderly who cease being independent, preliminary analysis shows that a significant number of the dependent elderly regain their independence, a situation which needs to be addressed in health care planning.

  16. The effects of solution treatment on the mechanical properties of age-hardened A-286 bar stock at elevated and cryogenic temperature

    NASA Technical Reports Server (NTRS)

    Montano, J. W.

    1972-01-01

    The mechanical properties are presented of solution treated and age hardened A-286 corrosion resistant steel bar stock. Material solution treated at 899 C or 982 C, each followed by an age hardening treatment of 718 C, was evaluated. Test specimens manufactured from 1.50 inch (3.81 cm) diameter bar stock were tested at temperatures from +649 C to -253 C. The test data indicated excellent tensile, yield, elongation and reduction-in-area properties at all testing temperatures for both solution treated and aged materials. Cryogenic temperature notched tensile, impact, and shear tests indicated excellent notch strength, ductility, and shear values. There was very little difference in the mechanical properties of the two solution treated and aged materials. The only exception was that the 962 C solution treated and aged material had superior stress rupture properties at 649 C.

  17. The influence of aging on critical transformation stress levels and martensite start temperatures in NiTi. Part 1: Aged microstructure and micro-mechanical modeling

    SciTech Connect

    Gall, K.; Sehitoglu, H.; Chumlyakov, Y.I.; Kireeva, I.V.; Maier, H.J.

    1999-01-01

    Transmission electron microscopy is used to determine the microstructures of a Ti-50.8 at% Ni alloy given different aging treatments. Two different peak-aging treatments are shown to result in disk shaped semi-coherent Ti{sub 3}Ni{sub 4} precipitates with a diameter ranging from 50 nm to 200 nm depending on the aging temperature. In the peak-aged materials, strong strain fields are clearly visible on TEM micrographs. An Eshelby based model is used to predict the local stress fields due to the differences in the lattice parameters of the precipitates and surrounding matrix. The position dependent local stress fields are then resolved onto the 24 different martensite correspondence variant pairs (CVP`s). It is further demonstrated that due to the unique orientation relationship that exists between the precipitate variants and the martensite CVP`s, the local resolved shear stresses are extremely large on some CVP`s and negligible on others. When the Ni rich NiTi is over-aged, it is found that the precipitates coarsen to approximately 1000 nm, they become in-coherent, and the local stress fields disappear. It is also determined that after over-aging in the average composition of the matrix drops from 50.8 at% Ni to approximately 50.4 at% Ni. In a subsequent paper (part 2) the results here are used to explain the dependence of the critical transformation stress levels and martensite start temperatures on the aging treatment.

  18. Reinforcement expectations explain the relationship between depressive history and smoking status in college students.

    PubMed

    McChargue, Dennis E; Spring, Bonnie; Cook, Jessica W; Neumann, Christopher A

    2004-07-01

    Little is understood about biobehavioral mechanisms that mediate the comorbidity between cigarette smoking and depression. We hypothesized that expectancies about nicotine's reinforcing effects are associated with vulnerability to depression, and may partially explain the relationship between history of depression and smoking. Young adult smokers and never smokers (N=175, mean age=19.9 years, S.D.=3.2) were assessed for history of depression and expectations about the negative (e.g., dispels bad moods) and positive (e.g., increases pleasure) reinforcing effects of smoking. Results are inconsistent with the premise that negative reinforcement expectancies mediate the comorbidity between depression and nicotine dependence. Instead, findings suggest that young adults with a prior history of major depression hold exaggerated expectations about nicotine's positive effects, which could enhance their likelihood of initiating smoking.

  19. Ageing Mechanisms and Control. Specialists’ Meeting on Life Management Techniques for Ageing Air Vehicles (Les mecanismes vieillissants et le controle) (Reunions des specialistes des techniques de gestion du cycle de vie pour vehicules aeriens vieillissants)

    DTIC Science & Technology

    2003-02-01

    include vacuum bag, inflated bladder or various forms of mechanical pressure. The use of a vacuum bag is the most common since it is almost always the...of the problems to integration of appropriate solutions in the form of roadmaps. A Depot System Capability Plan has been established to address future...report identifying forty-nine research and development activities in aging aircraft. A System Programme Office for Aging Aircraft has been formed in 2001

  20. The effects of aging process and preactivation on mechanical properties of nickel-titanium closed coil springs

    PubMed Central

    Alavi, Shiva; Haerian, Alireza

    2015-01-01

    Background: The most favorable feature of nickel-titanium (Ni-Ti) alloys in orthodontics is producing constant forces in a wide deformation range. Ni-Ti closed coils produce compressive strength and can be used for several purposes such as space closure. The aim of this study was to evaluate the effects of the aging process (temperature changes and prolonged strain) on Ni-Ti closed coils and to assess the effects of preactivation on forces generated by these coils. Materials and Methods: A total of 60 Ni-Ti closed coils (G&H Wire Co., Indiana, USA) were divided into four groups (n = 15). Two groups were kept in room temperature and two were incubated in 37°C in normal saline for 45 days. All the samples were extended to 30% of their original length. One group of the incubated coils and one group of room temperature coils were preactivated the same amount of 30%. The incubated groups also received 1000 thermocycles on days 22 and 45. The unloading forces were measured by a universal testing machine on days 0, 22 and 45. The data were analyzed using SPSS. Significance was set at 0.05. Results: The unloading forces of the Ni-Ti closed coils was not affected by prolonged heat and moisture either in preactivated groups (P = 0.8) or the nonpreactivated groups (P = 0.6). Furthermore, preactivation had no significant effect on the unloading forces of Ni-Ti closed coils (P = 0.7). Conclusion: Within the limitations of this study, both aging process and preactivation do not affect on mechanical properties of nickel-titanium closed coil springs. Preactivation had no effect on the forces generated by Ni-Ti closed coils. PMID:26005462

  1. Initial precipitation and hardening mechanism during non-isothermal aging in an Al–Mg–Si–Cu 6005A alloy

    SciTech Connect

    Yang, Wenchao; Ji, Shouxun; Huang, Lanping; Sheng, Xiaofei; Li, Zhou; Wang, Mingpu

    2014-08-15

    The characterization of precipitation and hardening mechanism during non-isothermal aging had been investigated using high resolution transmission electron microscopy for an Al–Mg–Si–Cu 6005A alloy. It was proposed that the needle-shaped β″ precipitates with a three-dimension coherency strain-field and an increased number density in the Al matrix provided the maximum strengthening effect for the Al–Mg–Si–Cu 6005A alloy. Simultaneously, it was also found that the formation and evolution of clusters in the early precipitation were associated with the vacancy binding energy, during which Si atoms played an important role in controlling the numbers density of Mg/Si co-clusters, and the excess Si atoms provided the increased number of nucleation sites for the subsequent precipitates to strengthen and improve the precipitation rate. Finally, based on the experimental observation and theoretical analysis, the precipitation sequence during the early precipitation in the Al–Mg–Si–Cu 6005A alloy was proposed as: supersaturated solid solution → Si-vacancy pairs, Mg-vacancy pairs and Mg clusters → Si clusters, and dissolution of Mg clusters → Mg atoms diffusion into the existing Si clusters → Mg/Si co-clusters → GP zone. - Highlights: • β″ precipitates provide the maximum strengthening effect for the 6005A alloy. • Si atoms play an important role in controlling the numbers of Mg/Si co-clusters. • The early aging sequence is deduced based on the solute-vacancy binding energy.

  2. [Interest in registered partnership higher than expected].

    PubMed

    Harmsen, C N; Latten, J J

    1998-10-01

    "Since 1 January 1998 non-married couples of the same or opposite sex [in the Netherlands have been] allowed to have their partnership officially registered. In the first half of 1998 about 1.8 thousand couples of the same sex and 0.8 thousand of opposite sex were registered. These numbers are somewhat higher than the [legislators] expected at the time of introduction of this legal provision. The average age of persons who registered their partnership is considerably higher than that of persons who married. The average age difference between two male partners is almost twice as large as between two marrying persons." (EXCERPT)

  3. Transition in the mechanism of flow-mediated dilation with aging and development of coronary artery disease.

    PubMed

    Beyer, Andreas M; Zinkevich, Natalya; Miller, Bradley; Liu, Yanping; Wittenburg, April L; Mitchell, Michael; Galdieri, Ralph; Sorokin, Andrey; Gutterman, David D

    2017-01-01

    In microvessels of patients with coronary artery disease (CAD), flow-mediated dilation (FMD) is largely dependent upon the endothelium-derived hyperpolarizing factor H2O2. The goal of this study is to examine the influence of age and presence or absence of disease on the mechanism of FMD. Human coronary or adipose arterioles (~150 µm diameter) were prepared for videomicroscopy. The effect of inhibiting COX [indomethacin (Indo) or NOS (L-NAME), eliminating H2O2 (polyethylene glycol-catalase (PEG-CAT)] or targeting a reduction in mitochondrial ROS with scavengers/inhibitors [Vitamin E (mtVitamin E); phenylboronic acid (mtPBA)] was determined in children aged 0-18 years; young adults 19-55 years; older adults >55 years without CAD, and similarly aged adults with CAD. Indo eliminated FMD in children and reduced FMD in younger adults. This response was mediated mainly by PGI2, as the prostacyclin-synthase-inhibitor trans-2-phenyl cyclopropylamine reduced FMD in children and young adults. L-NAME attenuated dilation in children and younger adults and eliminated FMD in older adults without CAD, but had no effect on vessels from those with CAD, where mitochondria-derived H2O2 was the primary mediator. The magnitude of dilation was reduced in older compared to younger adults independent of CAD. Exogenous treatment with a sub-dilator dose of NO blocked FMD in vessels from subjects with CAD, while prolonged inhibition of NOS in young adults resulted in a phenotype similar to that observed in disease. The mediator of coronary arteriolar FMD evolves throughout life from prostacyclin in youth, to NO in adulthood. With the onset of CAD, NO-inhibitable release of H2O2 emerges as the exclusive mediator of FMD. These findings have implications for use of pharmacological agents, such as nonsteroidal anti-inflammatory agents in children and the role of microvascular endothelium in cardiovascular health.

  4. Developing expectations regarding the boundaries of expertise.

    PubMed

    Landrum, Asheley R; Mills, Candice M

    2015-01-01

    Three experiments examined elementary school-aged children's and adults' expectations regarding what specialists (i.e., those with narrow domains of expertise) and generalists (i.e., those with broad domains of expertise) are likely to know. Experiment 1 demonstrated developmental differences in the ability to differentiate between generalists and specialists, with younger children believing generalists have more specific trivia knowledge than older children and adults believed. Experiment 2 demonstrated that children and adults expected generalists to have more underlying principles knowledge than specific trivia knowledge about unfamiliar animals. However, they believed that generalists would have more of both types of knowledge than themselves. Finally, Experiment 3 demonstrated that children and adults recognized that underlying principles knowledge can be generalized between topics closely related to the specialists' domains of expertise. However, they did not recognize when this knowledge was generalizable to topics slightly less related, expecting generalists to know only as much as they would. Importantly, this work contributes to the literature by showing how much of and what kinds of knowledge different types of experts are expected to have. In sum, this work provides insight into some of the ways children's notions of expertise change over development. The current research demonstrates that between the ages of 5 and 10, children are developing the ability to recognize how experts' knowledge is likely to be limited. That said, even older children at times struggle to determine the breadth of an experts' knowledge.

  5. Aging of the inceptive cellular population: the relationship between stem cells and aging.

    PubMed

    Symonds, Catherine E; Galderisi, Umberto; Giordano, Antonio

    2009-04-02

    The average life expectancy worldwide has about doubled and the global population has increased six fold over the past century. With improving health care in the developed world there is a proportional augmentation in the treatment necessary for elderly patients occasioning the call for increased research in the area of aging and age-related diseases. The manifestation of this research has been focalized on the causative cellular processes and molecular mechanisms involved. Here we will discuss the efforts of this research in the area of stem cells, delving into the regulatory mechanisms and how their de-regulation could be attributed to aging and age-related diseases.

  6. [Assessment of life expectancy in older people].

    PubMed

    Vaucher, Yves; Monod, Stéfanie; Büla, Christophe; Rochat, Stéphane

    2012-11-07

    Evaluation of the remaining life expectancy in elderly persons plays an important role in their care, most importantly when treatments are associated with severe side effects or when they reduce the quality of life. Prognostic scores, incorporating the functional status in addition to age and comorbidities, enable evaluation of the mortality risk during different periods of time. Despite some limitations, these scores are useful in establishing individualized treatment plans.

  7. Student Disengagement in Relation to Expected and Unexpected Educational Pathways

    ERIC Educational Resources Information Center

    Blondal, Kristjana S.; Adalbjarnardottir, Sigrun

    2012-01-01

    Students' different educational pathways were examined in relation to their disengagement during adolescence. The participants were Icelandic youth (N = 832) who were followed from age 14 to 22. Based on their academic achievement at age 15 and educational attainment at age 22 they were classified into groups that took expected versus unexpected…

  8. [Nutrition, aging, old age].

    PubMed

    Iván, L

    1998-12-06

    In humans there is evidence that the restriction of total caloric intake appears to be more important than the restriction of any particular macronutrient. Today the mechanism of the effect of caloric restriction is unknown. With advancing age and the occurrence of concomitant illness there is an increased risk of developing nutritional deficiencies. Altered nutritional status is associated with the pathogenesis of a number of common diseases of the elderly, thus it would appear that nutritional modulation and manipulation represents one possible approach to successful aging and a healthy longevity. The conceptual framework of the paper suggests the need of a newer light of the aging processes namely by a holistic human-gero-ecological model and a personality oriented geriatry. There are accentuated the role of the nutrients and vitamins, the food intake and drug-nutrients interactions and the meanings of the differences between the normal and pathological aging.