Vagal rebound and recovery from psychological stress

OBJECTIVE: To characterize cardiovascular recovery and examine the possible relationship of vagal activity and reflexes to risk for heart disease. METHODS: Subjects performed cold pressor and mental arithmetic tasks. Heart rate, heart period variability, and pre-ejection period were obtained for 1 minute before, during, and after each task (Experiment 1). In the second experiment, subjects performed a Stroop color-word task and a mental arithmetic task. Heart rate, heart period variability, blood pressure, and baroreflex sensitivity were obtained during the 5-minute baseline, task, and recovery periods (Experiment 2). RESULTS: In Experiment 1, heart rate during recovery was lower than baseline despite continued pre-ejection period shortening, whereas recovery heart period variability was higher than baseline. In Experiment 2, blood pressure increased throughout the session. However, recovery heart rate after mental arithmetic was lower than baseline heart rate, and heart period variability was higher during both recovery periods than during baseline. Vagal rebound, a sharp increase in variability in the first minute of recovery, was reduced in men in Experiment 1 and in individuals with a family history of cardiovascular disease in Experiment 2 and was associated with degree of change in baroreflex sensitivity between task and rest. CONCLUSIONS: Cardiovascular recovery from stress is associated with increased vagal modulation despite residual sympathetic activation. Vagal rebound may be involved in mechanisms resetting the baroreflex sensitivity at the onset and offset of stress. Diminished vagal rebound during recovery from stress is associated with standard risk factors for cardiovascular disease. The results support an association between attenuated vagal reflexes and risk for cardiovascular disease.     

Executive and Motivational Control of Performance Task Behavior, and Autonomic Heart-rate Regulation in Children: Physiologic Validation of Two-factor Solution Inhibitory Control

Forty-two (42) children (mean age 10.6 years) from mainstream public ( N = 22) and therapeutic schools ( N = 20) completed performance tasks assessing executive and motivational influences on motor responses. In a separate protocol, children underwent physiologic challenges of paced breathing and supine to standing postural change, while heart rate was continuously monitored.
Executive control was associated with vagal modulation of respiratory driven, high-frequency heart-rate variability ( t = 2.20, p < .03), whereas motivational control was associated with sympathetic modulation of posturally driven, low-frequency heart-rate variability ( t = -2.22, p < .03). These findings supported a two-factor solution of inhibitory control derived in a previous study.     

MR and CT demonstration of levator sling in congenital anorectal anomalies

Demonstration of the levator ani muscle is important in evaluating children with anorectal anomalies. Using magnetic resonance and CT we have imaged the levator sling in three children prior to their definitive surgery for imperforate anus. The levator mechanism was seen as a low signal band extending from the coccyx to the pubis.     

A preliminary study of breast-feeding and maternal symptomatology

The association between breast-feeding status and maternal health is examined. A survey questionnaire was presented via the World Wide Web. Self-reports of 168 breast-feeding and 65 weaned mothers between 4 and 208 weeks postpartum were compared for physician visits, symptomatology, and Perceived Stress Scale scores in the last month. Breast-feeding was associated with fewer physician visits and symptoms and less perceived stress. Moreover, the longer a woman breast-fed before she weaned, the fewer the symptoms and less stress she reported. Breast-feeding is associated with better maternal health both during the breast-feeding period and after weaning. Further research on the effects on maternal health of breast-feeding is indicated. Future prospective longitudinal investigations should address the possible inhibition of lactation by stress and physiological mechanisms that may link breast-feeding and weaning with maternal health.     

Breastfeeding and Maternal Stress Response and Health

This article reviews findings on the maternal stress and health effects of lactation. Several significant associations have emerged. Compared with not breastfeeding, breastfeeding is associated with increased parasympathetic nervous system modulation, greater vascular stress response, lower perceived stress levels, and fewer depressive symptoms. Breastfeeding exclusively is associated with an attenuated initial sympathetic cardiac nervous system response to some laboratory stressors. Bottle-feeding is associated with increased sympathetic and decreased parasympathetic cardiac control. The act of breastfeeding is associated with decreased neuroendocrine response to stressors and decreased negative mood. Finally, breastfeeding is associated with enhanced physical and mental health compared with non-breastfeeding .     

Characteristics of resilient youths living in poverty: the role of self-regulatory processes

As part of a larger investigation of very low income families, this study examined the characteristics that differentiated resilient from nonresilient school-age youths, with a focus on self-regulation (e.g., executive function, emotion regulation) skills. Resilience was operationally defined in a robust and comprehensive manner using well-established instruments that measured children's emotional well-being and mental health. Controlling for other explanatory variables, including differences in the experience of negative life events and chronic strains, resilient youths were notably different from nonresilient youths in terms of having greater self-regulatory skills and self-esteem, as well as in receiving more active parental monitoring. Study findings are discussed with regard to the theoretical framework of self-regulation and their implications for preventive intervention.     

The influence of the supine and prone positions in the esophageal pH monitoring in very low birth weight infants

BACKGROUND: Scarce information is available on the effects of body's positioning in the number and the duration of gastroesophageal reflux episodes in very low birth weight infants. AIM: To evaluate the influence of prone compared to supine positions on the frequency and duration of acid gastroesophageal reflux episodes in very low birth weight infants and study the role of body position in the occurrence of exams with reflux index > or = 5% and > or = 10%. METHODS: Sixty one prolonged esophageal pH monitoring exams were retrospectively analyzed. The difference between the prone and supine position exam duration was not longer than 3 hours. The reflux index was evaluated for the total period of the exam (reflux index total) and for each period in the two positions. The total number of reflux episodes, the number of reflux episodes > 5 minutes and the longest reflux episode were evaluated for each period in the two positions. These parameters were compared in accordance with body positioning, for each one of the three reflux index total categories: reflux index total < 5%, > or = 5% and > or = 10%. The frequencies of exams with reflux index total > or = 5% and reflux index total > or = 10% were compared for both positions. RESULTS: The number of hours in prone (11.2 +/- 1.0) and in supine (11.2 +/- 1.1) position were not different. All the prone positions monitoring parameters were significantly lower than the supine ones, in the three reflux index total categories. In the supine position, 32.7% (20/61) and 27.8% (17/61) of the exams, which were normal in prone, became abnormal, taking into account reflux index > or = 5% and > or = 10%, respectively, obtained for each position. CONCLUSIONS: In prone position, there is a significant decrease in number and duration of acid reflux episodes in very low birth weight infants. Supine position promotes a significant increase in the number of esophageal pH monitoring exams with reflux index > or = 5% and > or = 10%, making easier the diagnose of the gastroesophageal reflux disease.     

Breast feeding, bottle feeding, and maternal autonomic responses to stress

OBJECTIVE: The aim of this study was to examine the effects of breast feeding on autonomic nervous system (ANS) response to stressors. METHODS: Sympathetic and parasympathetic activities were examined before, during, and after standard laboratory stressors in women who were either exclusively breast feeding (n=14) or nonexclusively breast feeding (n=14), and in non-postpartum controls (n=15). RESULTS: Mothers who breast fed exclusively showed greater levels of parasympathetic cardiac modulation and slower heart rate (HR) throughout the session and less HR increase and preejection period (PEP) shortening to mental arithmetic (MA) than did nonexclusive breast feeders and controls. Nonexclusive breast-feeders showed greater electrodermal reactivity to, and greater differences in skin conductance response (SCR) frequency between baseline and recovery from cold pressor (CP) than did either exclusive breast-feeders or controls. Sympathetic activity was negatively related to the number of breast feedings and positively related to bottle feedings. CONCLUSION: Breast feeding shifts maternal ANS balance toward relatively greater parasympathetic and lesser sympathetic activity; the opposite occurs with bottle feeding. The frequency of feeding also is a critical factor in determining breast feeding effects on maternal ANS function.