584 research outputs found

    Taking the Edge Off: The Role of Stressful Events and Perceived Stress on Alcohol Use and Problems Among Older Adults

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    Alcohol misuse by older adults is a significant public health concern and is projected to worsen with the aging of the baby boom generation. To help understand the nature of older adult alcoholism, it is crucial to investigate factors such as stress that may influence consumption and problem use among older adults. Findings are mixed on the role of stress and coping in alcohol use, and studies comparing the role of stress and coping in alcohol use on different age groups are rare. Therefore, this study had the following aims: 1) To test a stress and coping model of current alcohol use, at-risk drinking, and alcohol-related problems in a nationally representative sample of older adults; 2) To investigate cohort differences in the Stress and Coping model between young adult: 20-39), early middle age: 40-59), and older adult: 60+) life stages. This investigator conducted secondary analysis of the National Epidemiologic Survey of Alcohol and Related Conditions: NESARC). An overall model of stress and coping was tested using structural equation modeling: SEM) with a subsample of older adult, middle-aged, and young adult current drinkers. Multiple group models tested group differences in the overall model, and interaction tests were conducted to test for a stress buffering effect of social support. Older adults endorsed lower levels of stressful life events, cognitive appraisal of stress and social support than younger age groups; alcohol consumption, at-risk drinking and rate of alcohol problems were also lower. In all age groups, higher levels of stressful events were associated with cognitive appraisal of stress, but in older adults, cognitive appraisal was associated with decreases in alcohol use. Among younger age groups, cognitive appraisal was associated with problem use, but not at-risk drinking or increased consumption. Interaction models were nonsignificant, suggesting that social support does not buffer the effect of stressful events on cognitive appraisal. The overall findings highlight limits of a global stress and coping model of alcohol use. Implications include the need to consider contextual and developmental factors in stress-related drinking including unique stresses in late life, and changing relationships between stress and drinking in older adulthood

    Fatigue and damage as a result of exercise in normal and diseased skeletal muscle

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    This thesis examines the nature of fatigue and damage as it affects healthy and dystrophic skeletal muscle. Initial fatigue studies were carried out using isolated mouse muscles. After 3 min of repeated maximal stimulation, extensor digitorum longus muscle force was reduced to 26% of the fresh value but this could be reversed by the addition of caffeine to the incubation medium, suggesting that acute fatigue is primarily due to failure of the processes of activation. In the human tibialis anterior (TA) muscle it was found that fatigue resulting from stimulated isometric contractions were affected by muscle length. Exercise at short lengths resulted in less force loss at the resting length, whereas exercise at long muscle lengths caused a greater force loss than normal at the resting length. There was a preferential force loss at sub-maximal stimulation frequencies, and this was exacerbated when muscles were exercised in a lengthened positon. Similar changes were observed using isolated mouse soleus muscles. Because of uncertainties about the adequate diffusion of metabolites in isolated muscles the properties of dystrophin-deficient (mdx) mouse muscles were investigated using an in vivo preparation of the TA. The mdx TA was, on average, 30% stronger than that of control mice but had a reduced force/cross-sectional area and a smaller low/high frequency force ratio due to a faster activation time, mdx muscle also displayed a greater fatigue resistance when exercised at a low frequency, but this was not the case with stimulation at maximal frequency. In order to test whether the altered contractile properties of mdx muscle were due to the presence of degenerating and regenerating fibres, the contractile characteristics of normal muscle were investigated during damage and recovery. Damage was induced by stimulated lengthening 1 contractions of the foot dorsiflexor muscles of mice. Maximum force, force-frequency characteristics, and morphology were measured for up to 20 days after exercise. Although the properties of normal/damaged and mdx muscles displayed a number of superficial similarities, it is unlikely that the altered contractile characteristics of mdx muscles are due to the presence of damaged fibres. The possibility that dystrophin-deficient muscles are more susceptible to exercise induced muscle damage was examined by comparing the responses of mdx and norm.al muscles to an episode of eccentric work. The findings were unequivocal, normal and mdx TA muscles displayed similar degrees of force loss 3 days after exercise (55% and 52% respectively) and comparable rates of force recovery after 12 days (76% and 80% of control in normal and mdx muscles respectively). The protective effect afforded by a bout of eccentric exercise against subsequent muscle injury from a similar exercise was characterised. Re-exercising a muscle after 10 days recovery had little effect on the immediate consequences of exercise, but reduced the degree of delayed onset force loss and fibre necrosis. Animals re-exercised after 12 weeks recovery displayed no apparent protection against delayed onset muscle damage when the exercise was repeated. These findings me in general agreement with work carried out in humans, but the time course of recovery post exercise is at least three times faster in the mouse, which has made a study of the long-term effects of eccentric exercise more practical. Six weeks after exercise, increases in muscle mass and force were evident, with a proportion of fibres displaying internal nuclei and signs of fibre splitting. Surprisingly, greater forces and fibre hypertrophy also occurred after 12 weeks recovery from an episode of eccentric work

    Parental Assets and Children\u27s Educational Outcomes

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    Several countries, including Canada, Singapore and the United Kingdom, have enacted asset-based policies for children in recent years. The premise underlying these policies is that increases in assets lead to improvement in various child outcomes over time. But little existing research examines this premise from a dynamic perspective. Using data from the NLSY79 mother and child datasets, two parallel process latent growth curve models are estimated to examine the effects of parental asset accumulation on changes in children’s math and reading achievement over six years during middle childhood. Results indicate that the initial level of assets is positively associated with math scores but not reading scores, while higher rates of asset accumulation are associated with slower rates of decline in reading scores but has no effect on changes in math scores. Overall, the results suggest that the relationship between assets and various child outcomes may not be straightforward. Different dimensions of the asset experience may lead to different outcomes, and the same dimension may also have different effects. Implications for future research and for asset-based policies are discussed

    A Review of Existing Treatments for Substance Abuse Among the Elderly and Recommendations for Future Directions

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    Background: With population aging, there is widespread recognition that the healthcare system must be prepared to serve the unique needs of substance using older adults (OA) in the decades ahead. As such, there is an increasingly urgent need to identify efficient and effective substance abuse treatments (SAT) for OA. Despite this need, there remains a surprising dearth of research on treatment for OA. Aims of review: This review describes and evaluates studies on SAT applied to and specifically designed for OA over the last 30 years with an emphasis on methodologies used and the knowledge gained. Methods: Using three research databases, 25 studies published in the last 30 years which investigated the impact of SAT on OA and met specific selection criteria were reviewed. Results: A majority of the studies were methodologically limited in that they were pre-to-post or post-test only studies. Of the randomized controlled trials, many were limited by sample sizes of 15 individuals or less per group, making main effects difficult to detect. Thus, with caution, the literature suggests that among treatment seeking OA, treatment, whether age-specific or mixed-age, generally works yielding rates of abstinence comparable to general populations and younger cohorts. It also appears that with greater treatment exposure (higher dosage), regardless of level of care, OA do better. Finally, based on only two studies, age-specific treatment appears to potentiate treatment effects for OA. Like younger adults, OA appear to have a heterogeneous response to treatments, and preliminary evidence suggests a possibility of treatment matching for OA. Conclusions: Expansion of research on SAT for OA is urgently needed for maximum effectiveness and efficiency of the healthcare system serving these individuals. Future research needs to include laboratory and community based randomized controlled trials with high internal validity of previously vetted evidenced-based practices, including Motivational Interviewing, cognitive behavioral therapy, and medications such as naltrexone, to determine the best fit for OA

    Changes In Parental Assets And Children\u27s Educational Outcomes

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    Several countries, including Canada, Singapore and the United Kingdom, have enacted asset-based policies for children in recent years. The premise underlying these policies is that increases in assets lead to improvement in various child outcomes over time. But little existing research examines this premise from a dynamic perspective. Using data from the NLSY79 mother and child datasets, two parallel process latent growth curve models are estimated to examine the effects of parental asset accumulation on changes in children\u27s achievements over six years during middle childhood. Results indicate that the initial level of assets is positively associated with math scores, but not reading scores, while faster asset accumulation is associated with changes in reading scores, but not in math scores. Overall, the results suggest that the relationship between assets and various child outcomes may not be straight-forward. Different dimensions of the asset experience may lead to different outcomes, and the same dimension may also have different effects. Implications for future research and for asset-based policies are discussed

    Left Ventricular Trabeculations Decrease the Wall Shear Stress and Increase the Intra-Ventricular Pressure Drop in CFD Simulations

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    The aim of the present study is to characterize the hemodynamics of left ventricular (LV) geometries to examine the impact of trabeculae and papillary muscles (PMs) on blood flow using high performance computing (HPC). Five pairs of detailed and smoothed LV endocardium models were reconstructed from high-resolution magnetic resonance images (MRI) of ex-vivo human hearts. The detailed model of one LV pair is characterized only by the PMs and few big trabeculae, to represent state of art level of endocardial detail. The other four detailed models obtained include instead endocardial structures measuring ≥1 mm2 in cross-sectional area. The geometrical characterizations were done using computational fluid dynamics (CFD) simulations with rigid walls and both constant and transient flow inputs on the detailed and smoothed models for comparison. These simulations do not represent a clinical or physiological scenario, but a characterization of the interaction of endocardial structures with blood flow. Steady flow simulations were employed to quantify the pressure drop between the inlet and the outlet of the LVs and the wall shear stress (WSS). Coherent structures were analyzed using the Q-criterion for both constant and transient flow inputs. Our results show that trabeculae and PMs increase the intra-ventricular pressure drop, reduce the WSS and disrupt the dominant single vortex, usually present in the smoothed-endocardium models, generating secondary small vortices. Given that obtaining high resolution anatomical detail is challenging in-vivo, we propose that the effect of trabeculations can be incorporated into smoothed ventricular geometries by adding a porous layer along the LV endocardial wall. Results show that a porous layer of a thickness of 1.2·10−2 m with a porosity of 20 kg/m2 on the smoothed-endocardium ventricle models approximates the pressure drops, vorticities and WSS observed in the detailed models.This paper has been partially funded by CompBioMed project, under H2020-EU.1.4.1.3 European Union’s Horizon 2020 research and innovation programme, grant agreement n◦ 675451. FS is supported by a grant from Severo Ochoa (n◦ SEV-2015-0493-16-4), Spain. CB is supported by a grant from the Fundació LaMarató de TV3 (n◦ 20154031), Spain. TI and PI are supported by the Institute of Engineering in Medicine, USA, and the Lillehei Heart Institute, USA.Peer ReviewedPostprint (published version

    Attenuation of protective effect against eccentric exercise-induced muscle damage

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    Effects of massage on delayed-onset muscle soreness, swelling, and recovery of muscle function

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    Context: Delayed-onset muscle soreness (DOMS) describes muscle pain and tenderness that typically develop several hours postexercise and consist of predominantly eccentric muscle actions, especially if the exercise is unfamiliar. Although DOMS is likely a symptom of eccentric-exercise–induced muscle damage, it does not necessarily reflect muscle damage. Some prophylactic or therapeutic modalities may be effective only for alleviating DOMS, whereas others may enhance recovery of muscle function without affecting DOMS. Objective: To test the hypothesis that massage applied after eccentric exercise would effectively alleviate DOMS without affecting muscle function. Design: We used an arm-to-arm comparison model with 2 independent variables (control and massage) and 6 dependent variables (maximal isometric and isokinetic voluntary strength, range of motion, upper arm circumference, plasma creatine kinase activity, and muscle soreness). A 2-way repeated-measures analysis of variance and paired t tests were used to examine differences in changes of the dependent variable over time (before, immediately and 30 minutes after exercise, and 1, 2, 3, 4, 7, 10, and 14 days postexercise) between control and massage conditions. Setting: University laboratory. Patients or Other Participants: Ten healthy subjects (5 men and 5 women) with no history of upper arm injury and no experience in resistance training. Intervention(s): Subjects performed 10 sets of 6 maximal isokinetic (90°·s(−1)) eccentric actions of the elbow flexors with each arm on a dynamometer, separated by 2 weeks. One arm received 10 minutes of massage 3 hours after eccentric exercise; the contralateral arm received no treatment. Main Outcome Measure(s): Maximal voluntary isometric and isokinetic elbow flexor strength, range of motion, upper arm circumference, plasma creatine kinase activity, and muscle soreness. Results: Delayed-onset muscle soreness was significantly less for the massage condition for peak soreness in extending the elbow joint and palpating the brachioradialis muscle (P < .05). Soreness while flexing the elbow joint (P = .07) and palpating the brachialis muscle (P = .06) was also less with massage. Massage treatment had significant effects on plasma creatine kinase activity, with a significantly lower peak value at 4 days postexercise (P < .05), and upper arm circumference, with a significantly smaller increase than the control at 3 and 4 days postexercise (P < .05). However, no significant effects of massage on recovery of muscle strength and ROM were evident. Conclusions: Massage was effective in alleviating DOMS by approximately 30% and reducing swelling, but it had no effects on muscle function
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