CONSISTENCY OF PERFORMANCE CHANGE AND AUTONOMIC RESPONSE AS A FUNCTION OF EXPRESSED ATTITUDE TOWARD A SPECIFIC STRESS SITUATION

A persistent problem in stress research has been that some individuals may show impairment, while others show improvement or no change in performance under stress. Attempts to relate this variance in performance to general anxiety or other personality variables have generally not been too successful. Based upon responses to a fear of shock item in an attitude questionnaire, Ss were classified as “high fear of shock” or “low fear of shock” types. Half of the Ss in each group were assigned a perceptual-motor task; the others were assigned a cognitive-interference task. After training, all Ss were informed that they would be required to maintain their training performance levels in a situation in which they would be shocked if performance declined. Performance and heart rate measures taken during training were compared with the same measures taken under the threat-of-shock conditions. Results indicate significant differences between groups in both performance and physiological activity with “high fear of shock”Ss exhibiting relatively greater performance impairment and increased heart rate.     

Role of glomerular prostanoid in control of glomerular filtration rate in rats

Summary It is generally accepted that the main action of glomerular prostanoids (GPs) on glomerular filtration rate (GFR) is to modulate the activity of different vasoconstrictors, specially in states of renal hypoperfusion. However it was also suggested that GPs may directly affect GFR. The present study was focused on this last hypothesis, in different experimental models, in rats.In adriamycin induced acute renal failure, the transient decrease of GFR is associated with higher levels of thromboxane B₂. Later on, when GFR returns to normal, vasodilator prostaglandins synthesis was also increased.In captopril induced renal failure in Na depleted rats (where GPs synthesis remained normal), stimulation of PGE₂ and PGI₂ production by K and NaCl was associated with a significant improvement of GFR. Furthermore, the increase in GFR induce by NaCl was prevented by inhibition of prostaglandin synthesis.Infusion of atrial natriuretic peptide in euvolemic rats induce a marked elevation both of GFR and PGE₂ synthesis. It was abolished by previous administration of prostaglandin synthesis inhibitor.In conclusion, glomerular prostanoids may influence GFR, either directly, or as mediator or modulator of other vasoactive hormones.Abbreviations GPs glomerular prostanoids - PG prostaglandin - TX thromboxane - ANP atrial natriuretic peptide - GFR glomerular filtration rate - PE polyethylene Nachtrag zu den Hauptreferaten des 19. Kongresses der Gesellschaft für Nephrologie in Göttingen (Klin Wochenschr 66/18)     

The Origin and Evolution of Human T-Cell Lymphotropic Virus Types I and II

Studies on human T-cell lymphotropic virus types I (HTLV-I) and II (HTLV-II) are briefly reviewed from the viewpoint of molecular evolution, with special reference to the evolutionary rate and evolutionary relationships among these viruses. In particular, it appears that, in contrast to the low level of variability of HTLV-I among different isolates, individual isolates form quasispecies structures. Elucidating the mechanisms connecting these two phenomena will be one of the future problems in the study of the molecular evolution of HTLV-I and HTLV-II.     

Physiological Correlates of Mental Activity: Eye Movements, Alpha, and Heart Rate During Imagining, Suppression, Concentration, Search, and Choice

Rapid eye movements (REMs), EEG alpha, and tonic heart rate (HR) were measured during 6 types of cognitive tasks—imagining a liked person, suppressing thoughts of the person, searching one's mind for alternative solutions, arithmetic involving little concentration, problems involving high concentration, and choosing a preferred activity. The latter 3 required verbalization, the former 3 did not. Only suppression and search did not differ significantly from each other on at least one physiological variable. Imagining, suppression, and search yielded few REMs, high alpha, and low HR. High concentration yielded many REMs, low alpha, and high HR. Choice yielded many REMs, low alpha, and intermediate HR. Low concentration yielded few REMs, low alpha, and high HR. Suppression produced somewhat less alpha than imagining but did not differ significantly in REMs.     

Improvement in Doppler ultrasound human foetal heart rate records by signal correlation

An improved method for the determination of foetal heart rate from Doppler ultrasound signals is described and evaluated. It determines the most probable pulse interval from the recurrence times of multiple echoes generated by each cardiac pulse. The method, when optimised, is shown to offer an improvement over current systems, especially in reduced signal loss.     

Cardiovascular indices of physiological arousal in boys with fragile X syndrome

In this study, the relationship between physiological arousal, as indexed by heart rate variability, was examined in boys with fragile X syndrome (FXS) and typically developing boys matched on chronological age. In addition, the relationship of heart activity to clinical and molecular factors in the group of boys with FXS was examined. Results suggest that boys with FXS have higher levels of heart activity during the passive phases, as reflected in shorter heart periods. This high level of heart activity appears to be due to increased sympathetic activity and reduced parasympathetic activity. Boys with FXS did not display the expected patterns of heart activity in response to phases of increasing challenge, and sympathetic and parasympathetic systems did not appear coordinated in these boys with FXS. Clinical factors may be related to neural regulation of heart activity while molecular factors do not appear to be.     

The rhythm of the heart in the blink of an eye: emotion-modulated startle magnitude covaries with heart rate variability

Emotion-modulated startle is a robust phenomenon that has been demonstrated in a wide range of experimental situations. Similarly, heart rate variability (HRV) has been associated with a diverse range of processes including affective and attentional regulation. The present study sought to examine the relationship between these two important measures of affective behavior. Ninety female participants viewed pleasant, neutral, and unpleasant pictures while exposed to acoustic startle stimuli. The eyeblink startle was recorded both during the affective foregrounds and during intertrial intervals. HRV was assessed during a resting baseline and relationships between HRV and startle magnitudes examined. Results indicated that resting HRV was inversely related to startle magnitude during both intertrial intervals and affective foregrounds. In addition, the participants with the highest HRV showed the most differentiated emotion-modulated startle effects, whereas those with the lowest HRV, compared to those with the highest HRV, showed significantly potentiated startle to neutral foregrounds and marginally potentiated startle to pleasant foregrounds. The findings are consistent with models that posit that prefrontal cortical activity modulates subcortical motivation circuits. These results have important implications for the use of startle probe methodology and for HRV in the study of emotional regulation and dysregulation.     

Hostility and sex differences in the magnitude, duration, and determinants of heart rate response to forehead cold pressor: Parasympathetic aspects of risk

Recent models hypothesize that hostility confers increased risk of CHD through weaker parasympathetic dampening of cardiovascular reactivity (CVR). We tested this possibility using the forehead cold pressor task, a common maneuver which elicits the “dive reflex” characterized by a reflexive decrease in HR presumably through cardiac-parasympathetic stimulation. Participants were initially chosen from the outer quartiles of a sample of 670 undergraduates screened using the hostility subscale of the Aggression Questionnaire ([Buss, A.H., Perry, M., 1992. The Aggression Questionnaire. Journal of Personality and Social Psychology, 63, 452-459.]). The final sample of 80 participants was evenly divided between men and women and high and low hostility. Following a 10-min baseline, participants underwent a 3-min forehead cold pressor task. The task evoked a significant HR deceleration that was mediated by PNS activation, as assessed by respiratory sinus arrhythmia (RSA). Replicating prior research, men displayed greater decrease in HR. More important, low hostiles maintained larger HR deceleration over time compared to high hostiles although the autonomic basis for this effect was unclear. The findings broaden understanding of hostility and sex-related cardiovascular functioning and support the task as a method for evoking PNS-cardiac stimulation.