Fractal dynamics of heart beat interval fluctuations in corticotropin-releasing factor receptor subtype 2 deficient mice

Non-linear fractal analysis of cardiac interbeat time series was performed in corticotropin-releasing factor receptor subtype 2 (CRFR2) deficient mice. Heart rate dynamics in mice constitutes a self-similar, scale-invariant, random fractal process with persistent intrinsic long-range correlations and inverse power-law properties. We hypothesized that the sustained tachycardic response elicited by intraperitoneal (ip) injection of human/rat CRF (h/rCRF) is mediated by CRFR2. In wildtype control animals, heart rate was increased to about maximum levels (~ 750 bpm) while in CRFR2-deficient animals baseline values were retained (~ 580 bpm). The tachycardic response elicited by ip-application is mediated by CRFR2 and is interpreted to result from sympathetic stimulation. However, the functional integrity of CRFR2 would not present a prerequisite to maintaining the responsiveness and resiliency of cardiac control to external environmental perturbations experimentally induced by extrinsic ip-application of h/rCRF or under physiological conditions that may be associated with an increased peripheral release of CRF. Under stressful physiological conditions achieved by novelty exposure, CRFR2 is not involved in the cardiodynamic regulation to external short-term stress. While the hypothesis of involvement of CRFR2 in cardiac regulation upon pharmacological stimulation cannot be rejected, the present findings suggest that the mechanism of action is by sympathetic stimulation, but would not unambiguously allow to draw any conclusions as to the physiological role of CRFR2 in the control of cardiac dynamics.     

Heart rate reactivity in HAD and LAD rats during Pavlovian fear conditioning

Recently, we reported that High-Alcohol-Drinking (HAD) rats exhibited selective deficits in active avoidance learning under alcohol-naive conditions, and that administration of moderate doses of alcohol (0.5 and 1.0 g/kg) facilitated learning in these rats (Blankenship et al., 2000; Rorick et al., 2003b). We hypothesized that the deficits resulted from excessive fear in the aversive learning context and that the anxiolytic properties of alcohol may have contributed to the improved learning that was observed after alcohol administration. This hypothesis was supported by a recent study in which prolonged freezing in HAD rats was seen after a classical fear conditioning procedure (Rorick et al., 2003a). To provide additional evidence that HAD rats indeed exhibit behaviors consistent with the expression of increased fear in aversive learning contexts, we employed a Pavlovian fear conditioning task to measure heart rate in HAD and Low-Alcohol-Drinking (LAD) rats. In this study, HAD (HAD-1 and HAD-2) and LAD (LAD-1 and LAD-2) rats were assigned to one of three pre-exposure conditions: Context Only, Context/Tone, or Sequential (Context Only followed by Context/Tone) Pre-Exposure. Following pre-exposure, fear conditioning acquisition and extinction procedures were identical for all groups. Results indicated that although no baseline differences were observed between HAD and LAD rats, HAD rats receiving Context-Only pre-exposure exhibited excessive heart rate reactivity to the tone conditional stimulus during fear conditioning acquisition, compared to LAD rats receiving the same pre-exposure conditions. These findings support the hypothesis that HAD rats exhibit behaviors consistent with increased fear in aversive learning contexts, as measured by autonomic conditioning.     

Negative emotions and coronary heart disease: Causally related or merely coexistent? A review

Negative emotions have been claimed to be a cause of coronary heart disease (CHD) as well as a consequence of cardiovascular disorders. Early case studies of cardiac disorders of soldiers in battle drew attention to the possibility that strong negative emotional states could cause CHD. Subsequent reports of reactions to natural disasters supported the notion that intense negative emotions could precipitate somatic disorders such as CHD. Since then, numerous studies have investigated relations between negative emotions and CHD. Over the years, retrospective studies have found, for example, that negative emotions are often present before the occurrence of CHD. Cross-sectional studies have indicated that symptoms of depression and anxiety are often present in CHD patients. Prospective studies have shown that the likelihood of CHD tends to be higher for people with negative emotions than for those without them. The main symptoms of negative emotional states that seem to be most closely associated with CHD are nervousness, getting easily upset, feeling fatigue, being indecisive, having sleep disturbances, being usually worried about something, and feeling that others would be better off if oneself were dead. Although the findings appear to support the notion of causal connections between negative emotions and CHD, they fail to provide conclusive proof of such relations. An alternative explanation that could also account for the findings is simply that negative emotions and CHD often coexist.     

Neurodevelopmental functioning in children being evaluated for heart transplant prior to 2 years of age

Cardiac defects represent the most common type of birth defect and children with these abnormalities are known to experience a variety of developmental and neuropsychological delays. Children receiving heart transplants may be at the highest risk for delays as they tend to represent the most severely ill patients with heart disease. This study investigates neurocognitive and adaptive functioning in 20 children under 2 years of age who were undergoing evaluation for heart transplant, comparing their performance to that of normative samples. The results indicate delays across various domains of neurocognition, including general cognitive, receptive language, expressive language, fine motor, and gross motor skills. In addition, adaptive and social-emotional functioning fell significantly below that of normative samples. No significant differences were found when comparing the test performance of patients with congenital heart defects (n = 12) to patients with cardiomyopathy (n = 8). Secondary analyses investigating the impact of genetic conditions, premature birth, and non-English language dominance showed minor changes in results across some domains, although this may have been due, at least in part, to decreased power to detect differences. Overall, this study’s results support the need for early evaluation, intensive intervention (e.g., speech, occupational, and physical therapy), and continued monitoring of these patients’ neurodevelopmental/neuropsychological functioning over time. Future research should examine longitudinal changes in development using both pre- and post-transplant data and should investigate the impact of early intervention.     

Congenital heart disease: A primer for the pediatric neuropsychologist

Congenital heart disease (CHD) affects millions of people worldwide, including over one million children in the United States. Approximately 25% of children born with CHD require intensive surgical intervention within the first year of life. Despite improved rates of survival into adulthood – rates that exceed 90% in the modern era – children and adolescents with CHD remain at risk for neurological injury and a range of neurobehavioral and psychosocial challenges that pose a threat to quality of life across the lifespan. Consequently, as experts in both clinical psychology and brain development, neuropsychologists are becoming increasingly involved in cardiac follow-up and monitoring to promote optimal developmental outcomes. The primary objective of this paper is to provide an evidence-based, clinically-oriented primer on CHD for pediatric neuropsychologists working with this growing population of survivors. Following an introduction to current standard-of-care guidelines for managing children and adolescents with CHD, we present an overview of brain development within the context of CHD, review neuropsychological outcomes, examine factors influencing variability in outcomes, and discuss implications and strategies for clinical assessment.     

Attachment patterns moderate the relation between coping flexibility and illness acceptance among kidney transplant recipients

Background and Objectives: Post-transplant kidney recipients may experience psychological concerns which have been associated with negative health behaviors. Illness acceptance might have an important role in this process. In line with the Conservation of Resources Theory (COR), the current study aimed to examine the relationship between coping flexibility, attachment patterns and illness acceptance among post-transplant kidney recipients, and to evaluate whether attachment patterns moderate the link between coping flexibility and illness acceptance.

Design: The study employed a cross-sectional design.

Methods: Ninety-four post-transplant kidney recipients completed questionnaires assessing demographic and medical characteristics, illness acceptance, coping flexibility and attachment patterns.

Results: Our results indicated that coping flexibility was positively associated with illness acceptance. Moreover, attachment moderated this link, as high coping flexibility was associated with increased illness acceptance among individuals with low levels of attachment anxiety, a finding which was not significant when high levels of anxiety were reported.

Conclusions: This study highlights the potential importance of building greater flexibility in order to enhance illness acceptance among kidney transplants recipients. Moreover, the role of insecure attachment patterns in health-related outcomes among kidney transplants recipients is emphasized.     

Walking versus biofeedback: a comparison of acute interventions for stressed students

Background: High rates of stress-related problems in college students and low utilization of treatment options demonstrate the need for effective stress-reducing interventions that can be self-regulated. This study compared the effect of brief paced-breathing with biofeedback and exercise interventions on heart rate variability, state anxiety and affect. Methods: Students (n?=?32) with high levels of perceived stress completed three 10-min interventions on separate days: paced-breathing with biofeedback (Biofeedback), a self-paced walk (Exercise), and an attention control condition of quiet studying (Quiet Study). Anxiety and affect were measured before (Pre), immediately after (Post0) and 15 mins after (Post15) the intervention. Heart rate variability was measured pre- and post-intervention using electrocardiogram. Results: Biofeedback reduced anxiety more than the exercise condition (Pre to Post0: Biofeedback d?=??0.48, Exercise d?=??0.13). Secondly, Exercise temporarily increased energy (Pre to Post0: d?=?0.67), whereas Biofeedback temporarily increased calmness (Pre to Post0: d?=?0.51). All conditions significantly increased total heart rate variability (p?Conclusions: Biofeedback and Exercise interventions improved emotional states in high-stress college students, but the type of change observed (i.e. energizing, calming or anxiety reducing) depended upon the condition.     

仿生学在移植免疫研究中的应用

世界正在进入仿生学时代。在生命科学领域中进行仿真学研究,将极大地促进人类对生命现象的认知,并揭示其普遍规律。运用仿生学原理在天然模型面前扬其利,避其害,将为科学工作者提供一个崭新的科研思维平台。从仿生角度洞悉并破解移植免疫奥秘将是一个具有广阔前景的创新源泉。