Abstract P153: Heart Rate And Systolic Hypertension At Early Post-kidney Transplant Period

Introduction: Sympathetic nervous system activation may be assessed by increased heart rate, which is associated with worsened cardiovascular and renal outcomes in general population. We aim to examine association between heart rate and blood pressure in kidney transplant recipients. Methods: A single center retrospective cohort study examines association of average successive heart rate (ASHR), which was defined as the average heart rate between successive office heart rate, with systolic blood pressure (SBP) and diastolic blood pressure (DBP) at 12-, 24-, 36-, and 48-weeks post-transplant by using multiple linear regression. Association of the ASHR with systolic hypertension (SHTN) and diastolic hypertension (DHTN) defined as SBP ≥130 and DBP ≥80 mmHg, respectively, were tested by multiple logistic regression. Results: Of all 105 kidney transplant recipients, mean age±SD was 54±12 years old and 61% was female. ASHR were 80±9, 79±10, 78±11, 76±11 beats/minutes at 12, 24, 36, and 48 weeks, respectively (p 0.509); therefore, ASHR was categorized into low and high ASHR groups (<80 and ≥80 beats/minute). The corresponding SBP were 136±17, 135±19, 132±16, 133±16 mmHg (p 0.356) and DBP were 80±11, 80±12, 78±11, 71±11 mmHg, respectively (p 0.644). With adjustment for age, gender, body mass index, type of kidney transplant, and induction immunosuppressive medications, at 24-week post-transplant, every 10 beats/minute increase in ASHR was associated with 4.4 mmHg decrease in SBP (β adjusted -0.440; p 0.016; 95%CI -0.796, -0.084) and high ASHR group was associated with 0.32-time lower odds of developing SHTN (OR adjusted 0.324; p 0.022; 95%CI 0.124, 0.852). There was no statistically significant association between ASHR and SBP at other post-transplant periods as well as between ASHR and DBP. Conclusions: Increased or high heart rate is associated with lower SBP or SHTN, but not DBP or DHTN at early post-transplant period. This association in an opposite direction among kidney transplant recipients may indicate different effects of sympathetic nervous system activation on blood pressure. Changes in immunological and non-immunological factors may contribute to the findings at different post-transplant periods.

Behavioral and Neuronal Effects of Inhaled Bromine Gas: Oxidative Brain Stem Damage

The risk of accidental bromine (Br2) exposure to the public has increased due to its enhanced industrial use. Inhaled Br2 damages the lungs and the heart; however, adverse effects on the brain are unknown. In this study, we examined the neurological effects of inhaled Br2 in Sprague Dawley rats. Rats were exposed to Br2 (600 ppm for 45 min) and transferred to room air and cage behavior, and levels of glial fibrillary acidic protein (GFAP) in plasma were examined at various time intervals. Bromine exposure resulted in abnormal cage behavior such as head hitting, biting and aggression, hypervigilance, and hyperactivity. An increase in plasma GFAP and brain 4-hydroxynonenal (4-HNE) content also was observed in the exposed animals. Acute and delayed sympathetic nervous system activation was also evaluated by assessing the expression of catecholamine biosynthesizing enzymes, tryptophan hydroxylase (TrpH1 and TrpH2), and tyrosine hydroxylase (TyrH), along with an assessment of catecholamines and their metabolites. TyrH was found to be increased in a time-dependent manner. TrpH1 and TrpH2 were significantly decreased upon Br2 exposure in the brainstem. The neurotransmitter content evaluation indicated an increase in 5-HT and dopamine at early timepoints after exposure; however, other metabolites were not significantly altered. Taken together, our results predict brain damage and autonomic dysfunction upon Br2 exposure.

Autonomic Stress Response of Nurse Students in an Objective Structured Clinical Examination (OSCE)

The aim of the present research was to analyze the autonomic stress response of nursing students in a nursing Objective Structured Clinical Evaluation (OSCE). We analyzed, in 41 s-year nursing degree students (20.1 ± 2.3 years), modifications in heart rate variability (HRV) to monitor the autonomic stress response before, during and after the 18 different scenarios of a complete OSCE. Heart rate mean response of nurse students was consistent with an anticipatory anxiety response at the beginning of the OSCE, showing a sympathetic nervous system activation, but HRV parameters show contradictory results. The most stressful OSCE station was the CPR maneuver, the stress response varying according to the station’s demands.

Elevated Activity of the Sympathetic Nervous System Is Related to Diminished Practice Effects in Memory: A Pilot Study

Background: Reductions in memory practice effects have gained interest as risk factor for future cognitive decline. Practice effects vary with age and can be moderated by factors such as individual variability in arousal or stress experience acting as an additional cognitive load. Objective: In the current pilot study, we examined whether sympathetic nervous system activation moderates the relationship between age and practice effects. Methods: Thirty cognitively healthy individuals aged 40–70 years performed a mnemonic discrimination task twice. Salivary alpha amylase (sAA) samples were obtained at different time points as a proxy of sympathetic activity. Spearman correlations examined the relation between practice effects and sAA. Subsequently, age by sAA interactions on practice scores were explored with bootstrapped linear regression models. Additionally, participants were divided in learners (exhibiting practice effects) and non-learners based on the difference in mnemonic discrimination performance. Results: Higher age and baseline SNS activity were independently related to lower practice effects. The non-learners showed significantly higher sAA scores at all time points compared to learners. Among the learners, baseline-adjusted lower levels of sAA after encoding were associated with greater practice effects, particularly in middle-aged individuals. No such interaction was observed for non-learners. Conclusion: These results show that higher baseline sympathetic activation is associated with worse practice effects independently of age. Additionally, in a subgroup of middle-aged learners practice effects were observed when sympathetic activity remained low during learning. These findings suggest that elevated sympathetic nervous system activation may be a promising indicator of imminent cognitive decline.

Is the Brain an Early or Late Component of Essential Hypertension?

The brain’s relationship to essential hypertension is primarily understood to be that of an end-organ, damaged late in life by stroke or dementia. Emerging evidence, however, shows that heightened blood pressure (BP) early in life and prior to traditionally defined hypertension, relates to altered brain structure, cerebrovascular function, and cognitive processing. Deficits in cognitive function, cerebral blood flow responsivity, volumes of brain areas, and white matter integrity all relate to increased but prehypertensive levels of BP. Such relationships may be observed as early as childhood. In this review, we consider the basis of these relationships by examining the emergence of putative causative factors for hypertension that would impact or involve brain function/structure, e.g., sympathetic nervous system activation and related endocrine and inflammatory activation. Currently, however, available evidence is not sufficient to fully explain the specific pattern of brain deficits related to heightened BP. Despite this uncertainty, the evidence reviewed suggests the value that early intervention may have, not only for reducing BP, but also for maintaining brain function.