Cardiovascular autonomic dysfunction in normotensive awake subjects with obstructive sleep apnoea syndrome

Cardiovascular autonomic function in normotensive awake patients with obstructive sleep apnoea syndrome was studied in 21 normotensive (mean age 48 ± 14 years), drug-free men with obstructive sleep apnoea syndrome. Cardiovascular reflex tests with continuous blood pressure monitoring and biochemical indices were performed the morning after a standard polygraphic sleep recording. A group of 20 agematched (mean age 49 ± 19 years) normal subjects was used as controls. The obstructive sleep apnoea syndrome patients showed higher heart rate and noradrenaline plasma levels (p < 0.05) at rest and a higher blood pressure response to head-up tilt (p < 0.01), suggesting sympathetic overactivity. Respiratory arrhythmia, baroreflex sensitivity index and Valsalva ratio were significantly lower in the obstructive sleep apnoea syndrome group (p < 0.01) whereas the decrease in heart rate induced by the cold face test was significantly higher (p < 0.05) showing a blunting of reflexes dependent on baroreceptor or pulmonary afferents with normal or increased cardiac vagal efferent activity. These abnormalities in autonomic regulation may predispose obstructive sleep apnoea syndrome patients to cardiovascular complications like hypertension and cardiac arrhythmias.     

Gender related differences in the cardiovascular responses to upright tilt in normal subjects

The heart rate and blood pressure responses to head-up tilt of 80 degrees was studied in 20 normal men and 21 normal women aged 20–50 years (mean age 31.1 ± 7.1 years). The heart rate increase in females during tilt was 73% that of males, whereas the increase in diastolic pressure during tilt was 29% of males. Expressed in relation to values obtained supine, heart rate increases on average 30.3% in men as compared to 21.5% in women whereas diastolic pressure increases by 15.2% in men as compared to an increase of only 4.3% in women. The data indicates that the cardiovascular response of normal females to upright tilt differs significantly from that of normal males. This attenuated responsiveness to ortho-stasis in women relative to men may predispose women to postural insufficiency and may account for the predominance of symptomatic women with clinically mild dysautonomia.     

Autonomic cardiovascular reflexes in pregnancy. A longitudinal study

Cardiovascular reflexes were studied in 22 healthy women before they were pregnant, once during each pregnancy trimester and after delivery to evaluate the effect of pregnancy on autonomic control of haemodynamics. The Valsalva manoeuvre, the deep breathing test, the orthostatic test and the isometric handgrip test were used to assess changes in autonomic nervous function. We found that pregnancy altered the heart rate response in the Valsalva manoeuvre, the deep breathing test and the orthostatic tests. The deep breathing difference (p = 0.03) and max/min ratio (p = 0.03) decreased in pregnancy, whereas standing heart rate increased (p < 0.0001). Both the systolic and diastolic blood pressure increased after standing up during pregnancy. The circulatory responses to isometric exercise were not affected by pregnancy. The results show that parasympathetic respon-siveness is decreased in pregnancy and that it returns to normal after delivery.     

Certain cardiovascular indices predict syncope in the postural tachycardia syndrome

Patients with postural tachycardia syndrome (POTS) represent a patient population with orthostatic intolerance; some are prone to syncope, others are not. The underlying neurocardiovascular mechanisms are not completely understood. The current study was undertaken to assess if certain cardiovascular indices are predictive of syncope in POTS. We compared the response to tilt-up and the Valsalva maneuver in four groups: POTS patients who fainted (POTS-f;n=11; 31±11 years); POTS patients who did not faint (POTS-nf;n=9; 29±9 years); normal controls (NLS;n=13; 39±11 years); patients with generalized autonomic failure with orthostatic hypotension and syncope (n=10; 59±14 years). Beat-to-beat heart rate (HR), systolic arterial pressure, diastolic arterial pressure (DAP) and pulse pressure (PP) were monitored using Finapres. Cardiac output, stroke volume (SV) and end-diastolic volume (EDV), and calculated total peripheral resistance (TPR) were recorded using thoracic electrical bioimpedance. An autonomic reflex screen which quantitates the distribution and severity of autonomic failure was also done. With the patient supine, all POTS patients (POTS-nf; POTS-f) had increased HR (p<0.001) and reduced SV/EDV (p<0.001) when compared with NLS. On tilt-up, POTS-f patients were significantly different from both NLS and POTS-nf patients; the most consistent alteration was a fall instead of an increase in TPR; other changes were a greater reduction in PP, a reduction (instead of an increment) in DAP, and a different pattern of changes during the Valsalva maneuver (excessive early phase II, attenuated or absent late phase II). Our results suggest -adrenergic impairment with increased pooling or hypovolemia in POTS-f patients. We conclude that it is possible to identify the mechanism of syncope in POTS patients, and perhaps other patients with orthostatic intolerance and an excessive liability to syncope.     

Abnormal sympathetic hyper-reactivity in patients with myasthenia gravis: A prospective study

Introduction

Patients with myasthenia gravis, especially those in crises, are not infrequently observed to demonstrate wide fluctuation in heart rate and blood pressure.

Objective

This study was conducted to assess autonomic function in patients with myasthenia gravis.

Methods

Patients with myasthenia gravis diagnosed on the basis of typical clinical details, edrophonium or neostigmine test, decremental response on repetitive nerve stimulation testing and anti acetyl choline receptor antibody testing, were compared with age and gender matched controls. Apart from detailed clinical evaluation, all subjects underwent tests of autonomic function, viz. heart rate and blood pressure response on orthostatic tests and isometric handgrip test, Valsalva maneuver, R–R interval variation (RRIV) and the sympathetic skin response (SSR). Results were compared with those in the control group using repeated measures ANOVA and the paired t-test.

Results

Sixty-four patients (27 males, 37 females) with a mean age of 40.5 ± 17 years) with myasthenia gravis of an average 3 ± 4 years duration, and 241 normal controls were enrolled. On the orthostatic tests, patients showed rise in heart rate, systolic and diastolic blood pressure, as did controls, however, the rate and the duration of rise was significantly higher than in the controls (p < 0.01). Similar difference between patients and controls, in rate of rise of these parameters was observed on the isometric hand grip test. No significant difference was observed between the two groups on tests of parasympathetic function (Valsalva ratio, RRIV). These effects could also partially be due to pyridostigmine, which all patients were receiving.

Conclusion

This study suggests sympathetic hyper-reactivity in patients with myasthenia gravis, which could be responsible for serious hemodynamic instability in patients in crisis.     

Impaired orthostatic heart rate recovery is associated with smaller thalamic volume: Results from The Irish Longitudinal Study on Aging (TILDA)

The thalamus is a central hub of the autonomic network and thalamic volume has been associated with high‐risk phenotypes for sudden cardiac death. Heart rate response to physiological stressors (e.g., standing) and the associated recovery patterns provide reliable indicators of both autonomic function and cardiovascular risk. Here we examine if thalamic volume may be a risk marker for impaired heart rate recovery in response to orthostatic challenge. The Irish Longitudinal Study on Aging involves a nationally representative sample of older individuals aged ≥50 years. Multimodal brain magnetic resonance imaging and orthostatic heart rate recovery were available for a cross‐sectional sample of 430 participants. Multivariable regression and linear mixed‐effects models were adjusted for head size, age, sex, education, body mass index, blood pressure, history of cardiovascular diseases and events, cardiovascular medication, diabetes mellitus, smoking, alcohol intake, timed up‐and‐go (a measure of physical frailty), physical exercise and depression. Smaller thalamic volume was associated with slower heart rate recovery (?1.4 bpm per 1 cm³ thalamic volume, 95% CI ?2.01 to ?0.82; p < .001). In multivariable analysis, participants with smaller thalamic volumes had a mean heart rate recovery ?2.7 bpm slower than participants with larger thalamic volumes (95% CI ?3.89 to ?1.61; p < .001). Covariates associated with smaller thalamic volume included age, history of diabetes, and heavy alcohol consumption. Thalamic volume may be an indicator of the structural integrity of the central autonomic network. It may be a clinical biomarker for stratification of individuals at risk of autonomic dysfunction, cardiovascular events, and sudden cardiac death.     

The prevalence of multiple sclerosis in the north–west Italian province of Genoa

The objective of this study was to assess the prevalence of multiple sclerosis (MS), calculated as point prevalence on 31 December 1997, in the province of Genoa, North–western Italy. Methods The province of Genoa is located in North–western Italy, an area of 1835 km². On the point prevalence day the population consisted of 913,218 inhabitants. MS cases were identified by analysing archives of the hospitals with neurological or rehabilitation wards, neurologists serving the community, files of local chapters of the Italian MS society, all requests for oligoclonal bands analysis on CSF in the studied area. Patients included in the study were MS cases diagnosed before 31 December 1997 according to the Poser criteria resident in the province under study. Results A total of 857 subjects were alive and residing in the province of Genoa on the prevalence day. The overall crude prevalence rate was 94 per 100,000 (95% CI 88–100); 291 were males (34%) with a crude prevalence of 67 per 100,000 (95 % CI 60–76) and 566 were females (66%) with a prevalence of 118 per 100,000 (95% CI 108–128). The female/male ratio was 1.9. When age and sex were adjusted to the Italian standard population of 1991 prevalence was 85 per 100,000. Five hundred and thirty two out of the 857 patients agreed to be interviewed. The interviewed sample was representative of the prevalence sample: sex and gender distributions were identical in the two samples. The overall mean age was 48 (± 13) years (48 ± 12 years in males; 48 ± 14 years in females). Mean disease duration was 15 (± 10) years for males and 16 (± 11) years for females. Two hundred and ninety one (55 %) subjects had a relapsing remitting (RR) clinical course, 150 (28%) were secondary progressive (SP) and 91 (17%) were primary progressive (PP). Mean EDSS score was 5 (± 2; median 5). The mean age at time of onset was 33 (±10) years for males and 32 (± 11) years for females. The disease onset was monosymptomatic in 76% (n = 407) patients and polysymptomatic in 24% (n = 125). The mean length of time between clinical onset and diagnosis was 5 (± 6) years. Conclusion We confirmed that the province of Genoa is a very high risk area for MS. We found a high rate of patients with a PP course; also the proportion of patients with high disability scores is greater compared to previous studies.     

Cardiac dysrhythmias during cardiovascular autonomic reflex tests

To assess the possible dysrhythmogenic effect of cardiovascular autonomic function tests, ECG tracings of 925 consecutive subjects, taken during a battery of cardiovascular autonomic reflex tests were analyzed. The battery included the Valsalva manoeuvre, deep breathing test, orthostatic and isometric handgrip. The frequency of ventricular extrasystoles increased during or after the tests, compared with the resting phase, in 11% of healthy subjects, in 11% of diabetic subjects and in 23% of subjects with a previous myocardial infarction (p = 0.001vs healthy subjects). In patients with previous myocardial infarction, the most dysrhythmogenic individual tests were orthostatic and isometric handgrip. In nine subjects, other cardiac rhythm disturbances were detected (including nonsustained ventricular tachycardia, conduction block, and atrial fibrillation). In all cases, the dysrhythmias were asymptomatic and resolved without medical intervention. In conclusion, we consider the cardiovascular reflex test battery safe for the patient. However, due to occasional potentially significant dysrhythmias we recommend continuous monitoring of the electrocardiogram and immediate access to resuscitation facilities during cardiovascular autonomic testing.     

Cardiovascular autonomic function tests to provide normative data from a healthy older population

We aimed to derive normative data for cardiovascular autonomic function tests (AFT) in an older population using new measures. The AFT were performed in 48 healthy control subjects. The average heart rate (HR) response to deep breathing (DB) (HR_DB), Valsalva ratio (VR), magnitude of the HR and blood pressure (BP) response of different phases of the Valsalva maneuver, BP recovery times (PRT 100 and PRT 50) and HR and BP changes on head-up tilting were calculated. The mean age (±standard deviation) of study participants was 58 ± 14.5 years (range 20–82 years), of whom 29 (60%) were men. The systolic blood pressure (SBP) early phase 2 amplitude showed an inverse relationship with age (p = 0.03). There was a trend for progressive attenuation of SBP late phase 2 amplitude with age (p = 0.09). The systolic BP recovery time was not affected by age, gender or body mass index. We concluded that age has a significant effect on most AFT variables. Age and gender did not influence the systolic BP recovery time; hence, systolic BP recovery time could be useful in the evaluation of adrenergic failure.     

Muscle sympathetic nerve activity during postural change in healthy young and older adults

Recent evidence suggests that during orthostatic stress the reflex increase in muscle sympathetic nerve activity may be diminished in older adults. To test this hypothesis, we measured muscle sympathetic nerve activity, plasma noradrenaline concentrations, heart rate, and arterial blood pressure in twelve young (mean, 25 years; range, 19–29 years) adults and 14 older (mean 64 years; range, 60–74 years) healthy adults, while supine and during upright sitting. Supine control levels of muscle sympathetic nerve activity were higher in the older subjects (35 ± 1 vs. 25 ± 1 bursts/min,p < 0.05), but there were no differences in plasma noradrenaline concentrations, heart rate or arterial pressure. Despite higher supine control levels in the older group, the absolute unit increases in muscle sympathetic nerve activity in response to upright sitting (p < 0.05 vs. control) were not different in the two groups (7 ± 1 vs. 7 ± 1 bursts/min), nor were the increases in plasma noradrenaline concentrations. Heart rate did not increase above supine control in response to sitting in either group. Arterial pressure increased slightly (p < 0.05, supine vs. control), but there were no age-related differences. These results indicate that, contrary to recent findings, the reflex increases in muscle sympathetic nerve activity and plasma noradrenaline concentrations and regulation of arterial pressure during this natural orthostatic stress are well preserved in older healthy men and women.     

The profile of executive function in very preterm children at 4 to 12 years

Aim To examine executive functioning in very preterm (gestational age ≤30wks) children at 4 to 12 years of age. Method Two‐hundred very preterm (106 males, 94 females; mean gestational age 28.1wks, SD 1.4; mean age 8y 2mo, SD 2y 6mo) and 230 term children (106 males, 124 females; mean gestational age 39.9wks, SD 1.2; mean age 8y 4mo, SD 2y 3mo) without severe disabilities, born between 1996 and 2004, were assessed on an executive function battery comprising response inhibition, interference control, switching, verbal fluency, verbal and spatial working memory, and planning. Multiple regression analyses examined group differences while adjusting for effects of parental education, age, sex, and speed indices. Results Relative to children born at term, very preterm children had significant (p_s<0.02; where p_s represents p‐values) deficits in verbal fluency (0.5 standardized mean differences [SMD]), response inhibition (0.4 SMD), planning (0.4 SMD), and verbal and spatial working memory (0.3 SMD), independent of slow and highly fluctuating processing speed. A significant group by age interaction indicated that group differences for response inhibition decreased between 4 and 12 years. Interpretation Very preterm birth is associated with a profile of affected and non‐affected executive functions independent of impaired speed. Deficits are of small to moderate magnitude and persist over time, except for response inhibition for which very preterm children catch up with peers.     

Efficacy of compression of different capacitance beds in the amelioration of orthostatic hypotension

Orthostatic hypotension (OH) is the most disabling and serious manifestation of adrenergic failure, occurring in the autonomic neuropathies, pure autonomic failure (PAF) and multiple system atrophy (MSA). No specific treatment is currently available for most etiologies of OH. A reduction in venous capacity, secondary to some physical counter maneuvers (e.g., squatting or leg crossing), or the use of compressive garments, can ameliorate OH. However, there is little information on the differential efficacy, or the mechanisms of improvement, engendered by compression of specific capacitance beds. We therefore evaluated the efficacy of compression of specific compartments (calves, thighs, low abdomen, calves and thighs, and all compartments combined), using a modified antigravity suit, on the end-points of orthostatic blood pressure, and symptoms of orthostatic intolerance. Fourteen patients (PAF,n=9; MSA,n=3; diabetic autonomic neuropathy,n=2; five males and nine females) with clinical OH were studied. The mean age was 62 years (range 31–78). The mean ±SEM orthostatic systolic blood pressure when all compartments were compressed was 115.9±7.4 mmHg, significantly improved (p<0.001) over the head-up tilt value without compression of 89.6±7.0 mmHg. The abdomen was the only single compartment whose compression significantly reduced OH (p<0.005). There was a significant increase of peripheral resistance index (PRI) with compression of abdomen (p<0.001) or all compartments (p<0.001); end-diastolic index and cardiac index did not change. We conclude that denervation increases vascular capacity, and that venous compression improves OH by reducing this capacity and increasing PRI. Compression of all compartments is the most efficacious, followed by abdominal compression, whereas leg compression alone was less effective, presumably reflecting the large capacity of the abdomen relative to the legs.     

Cardiovascular dysautonomia in fatal familial insomnia

Autonomic control of the cardiovascular system was assessed in two patients with Fatal Familial Insomnia. The diagnosis was confirmed at autopsy in patient 1. In the resting state blood pressure and heart rate were higher than controls in patient 1; plasma noradrenaline levels were elevated in both patients. Evaluation of cardiovascular reflexes indicated intact baroreflex pathways but with exaggerated blood pressure and biochemical responses to certain stimuli (postural change, Valsalva manoeuvre, isometric handgrip). There was no pressor response to intravenously infused noradrenaline, an increased response to atropine and diminished depressor and sedative effects to clonidine. Overall these results are indicative of an unbalanced autonomic control with preserved parasympathetic and higher background and stimulated sympathetic activity. These physiological, biochemical and pharmacological data, together with known neuro-pathological findings in this disorder, emphasize the possible role played by the thalamus in regulating autonomic control of cardiovascular function in man.     

The effects of the noradrenaline precursor,l-threo-3,4-dihydroxy-phenylserine,in children with orthostatic intolerance

To evaluate the usefulness ofl-threo-3,4-dihydroxyphenylserine (l-DOPS), a precusor of noradrenaline, in the treatment of orthostatic intolearnce in children, we examined the circulatory responses to orthostatic stress and clinical symptoms before and after medication. Seven children with orthostatic intolerance, two boys and five girls, aged 11–15 years (mean age 13.3 years), were studied.l-DOPS (100–200 mg) was adminstered orally once or twice a day for 4 weeks. Blood pressure (BP) and heart rate (HR) were measured with a non-invasive beat-to-beat method (Finapres). All had a marked reduction in BP (SBP/DBP=–50±9/–27±6 mmHg) with prolonged recovery time in the initial phase during standing. Afterl-DOPS for 4 weeks, BP reduction in the initial phase was significantly attenuated (SBP/DBP=–37±9/–17±7 mmHg,p<0.05) and recovery time was normalized in all, although supine BP and HR were unchanged. Two reported relief of all symptoms, while in five symptoms were markedly improved. There were no adverse effects reported. These preliminary studies have indicated thatl-DOPS may be an effective drug for the treatment of orthostatic intolerance in children.     

Early nocturnal blood pressure changes in diabetic autonomic neuropathy assessed by Fourier series

The 24 h periodic pattern of blood pressure was studied in 44 patients with diabetes mellitus (14 type 1, 30 type 2; mean duration of disease 6.5 ± 1.8 years) in good metabolic control but with abnormal cardiovascular reflex responses; of these 21 were normotensive and 23 hypertensive. All had abnormal responses to at least two out of four tests: deep breathing, lying to standing, Valsalva manoeuvre and postural hypotension. Two sex- and agematched groups, consisting of 20 normotensive and 20 hypertensive diabetic patients without dysautonomia, were studied as controls. Each patient underwent ambulatory blood pressure monitoring for at least 24 h, using an auscultatory automatic device. Data were analysed using the sum of three periodic functions (Fourier partial sum). In the diabetic normotensive groups, the absolute blood pressure fell to its night-time minimum more rapidly, and increased to its morning maximum more slowly, in those with abnormal cardiovascular reflexes than in the controls (nightly blood pressure decrease –5.8/–4.7 vs. –3.8/–4.0 mmHg/h; increase 4.7/3.6 vs. 5.9/6.1 mmHg/h). The same behaviour was found in both hypertensive groups but the amplitude of the differences was more marked (blood pressure nocturnal decrease –7.7/–7.1 vs. –4.3/–3.9 mmHg/h; increase 3.2/2.1 vs. 5.8/4.3 mmHg/h). This analysis of 24 h ambulatory blood pressure data may be of value in diagnosis and evaluation of autonomic deficits.     

Insulin resistance and autonomic function in traumatic lower limb amputees

This study examined plasma insulin response to oral glucose load and autonomic nervous system activity in male lower limb amputees (n = 52) aged 50–65 years, compared to matched controls (n = 53). The groups had similar body mass index, blood pressure and plasma lipid levels. The amputees had higher mean fasting plasma insulin levels (18.4 ± 9.7 (SD) versus 13.7 ± 5.1 m U/l,p = 0.005) and during an oral glucose tolerance test (OGTT) (1 h levels 88.1 ± 45.3 versus 62.1 ± 42.7,p = 0.016) with similar plasma glucose levels, indicating insulin resistance. At baseline with the subjects supine, there were no group differences in low- or high-frequency power of heart rate variability or in plasma levels of norepinephrine (NE) or epinephrine (EPI). In response to orthostasis, the groups had similarly increased plasma NE levels. During the OGTT, amputees had significantly larger increments in low-frequency power than did controls (2.2 ± 1.3 versus 1.6 ± 0.9 (beats/min)² respectively,p < 0.01) and plasma NE levels increased significantly in amputees (1595 ± 849 versus 1941 ± 986 pM,p = 0.0008) but not in controls. At 1 h after glucose administration, plasma EPI levels were decreased significantly from baseline in both groups; at both 1 and 2 h after glucose administration, plasma EPI levels were higher in the amputees than controls. Amputees appear to have a combination of enhanced sympathoneural responsiveness and attenuated suppression of adrenomedullary secretion during glucose challenge. As catecholamines antagonize insulin effects, one possible explanation for insulin resistance in amputees is hyperglycaemia-induced sympathoneural activation and a failure of hyperglycaemia to decrease adrenomedullary secretion.     

Portable infrared pupillometry using Pupilscan: Relation to somatic and autonomic nerve function in diabetes mellitus

The relationship between dynamic pupillary function and peripheral nerve function was studied in 85 randomlyselected diabetic patients and 67 age-matched normals using a portable infrared pupillometer (Pupilscan Version 5). Seven measurements were chosen to represent different components of the pupillary constriction-redilatation curve after a standardized light stimulus. Constriction latency was significantly prolonged in diabetic patients (p = 0.05), as was time to 63% redilatation (p = 0.001). Thermal thresholds at the feet weakly correlated with relative reflex amplitude (warm:r = –0.22,p = 0.05; cool:r = –0.23,p = 0.05), but vibration perception thresholds were more strongly associated with constriction and redilatation velocity (r = –0.42,p = 0.001;r = –0.28,p = 0.03). Among the cardiovascular autonomic function tests, only respiratory R—R variation correlated with constriction velocity (r = 0.47,p < 0.001), and Valsalva ratio with redilatation velocity (r = 0.25,p = 0.04), but postural systolic blood pressure change was also correlated with reflex amplitude and latency time (r = –0.42,p < 0.001;r = 0.41,p = 0.001). There were no significant associations with three measures of sweating function in the feet. Pupil measurements were abnormal in 4–11% of diabetic patients, while other neurological tests were abnormal in 8–35%, consistent with the length-dependence of diabetic neuropathy. Median coefficients of variation were 2.0–7.2% in diabetic patients. Portable pupillometry using this device is currently the simplest method available for measuring a cranial autonomic pathway, though the measurements obtained with it are only weakly associated with the results of other tests of somatic and autonomic function in diabetes, and are unrelated to measurements of distal sudomotor function.     

Reduced cardiac <Superscript>123</Superscript>I-MIBG uptake reflects cardiac sympathetic dysfunction in de novo Parkinson’s disease

It remains unclear whether cardiac iodine-123-labeled metaiodobenzylguanidine (¹²³I-MIBG) uptake is clinically related to autonomic dysfunction on conventional autonomic function testing in de novo Parkinson’s disease (PD). We therefore studied the relation between cardiac ¹²³I-MIBG uptake and cardiovascular autonomic dysfunction in patients with de novo PD. The subjects were 26 patients with de novo PD. The ratio of the average pixel count in the heart to that in the mediastinum was calculated to derive the cardiac ¹²³I-MIBG uptake. Cardiovascular autonomic function was evaluated on the basis of cardiovascular autonomic response on the Valsalva maneuver (VM), and systolic blood pressure response (SBP) on head-up tilt-table testing (HUT). Patients with de novo PD had significantly reduced cardiac ¹²³I-MIBG uptake as compared with controls (1.58 ± 0.43 vs. 2.25 ± 0.34, p = 0.0001) and cardiovascular autonomic response on the VM. No significant difference in the fall in SBP on HUT was found between patients with de novo PD and the controls. Cardiac ¹²³I-MIBG uptake in de novo PD was not significantly related to vasomotor sympathetic function, baroreceptor reflex gain, cardiac parasympathetic function, or the changes in SBP on HUT. Cardiac ¹²³I-MIBG uptake was, however, significantly related to the blood pressure overshoot in phase IV of the VM (r = 0.648, p = 0.0003). Cardiac ¹²³I-MIBG uptake began to decrease in association with the reduction in the overshoot of phase IV on the VM. Cardiac ¹²³I-MIBG uptake clinically reflects cardiac sympathetic dysfunction in de novo PD.     

Sex differences in the association between stressor-evoked interleukin-6 reactivity and C-reactive protein

Individuals differ consistently in the magnitude of their inflammatory responses to acute stressors, with females often showing larger responses than males. While the clinical significance of these individual differences remains unclear, it may be that greater inflammatory responses relate to increased systemic inflammation and thereby risk for chronic inflammatory disease. Here, we examined whether acute stressor-evoked interleukin (IL)-6 responses associate with resting levels of C-reactive protein (CRP), a marker of systemic inflammation, and whether this association differs by sex. Subjects were 57 healthy midlife adults (30–51 years; 33% female; 68% white). Blood was drawn before and 30-min after two mental stress tasks: a multisource interference task and a Stroop color word task. Hierarchical regressions controlling for age, sex, race, and BMI tested whether stressor-evoked IL-6 responses were associated with resting CRP and whether this association differed by sex. Results indicated that sex and stressor-evoked IL-6 responses interacted to predict CRP (ΔR² = 0.08, B = −1.33, β = −0.39, p = 0.02). In males, larger stressor-evoked IL-6 responses associated with higher CRP, whereas in females, stressor-evoked IL-6 responses showed a non-significant negative association with CRP. These findings indicate that inflammatory responses to acute stressors associate with resting levels of CRP; however, this association differs by sex. Previous literature suggests that there are sex differences in stressor-evoked IL-6 responses, but this is the first study to show sex differences in the relationship between acute inflammatory responses and systemic inflammation. The contribution of these sex differences to inflammatory disease risk warrants further investigation.     

Evaluation of non-invasive blood pressure measurement by the Finapres method at rest and during dynamic exercise in subjects with cardiovascular insufficiency

The accuracy and precision of the Finapres in recording rest and exercise blood pressure compared with the intra-arterial (aortic and brachial) and random-zero sphygmomanometer methods was assessed in 84 ischaemic patients in three different studies. Firstly, comparison at rest with the aortic intraarterial pressure in 50 ischaemic patients demonstrated that the Finapres systolic (136.5 ± 21.1 vs. 129.3 ± 19.0 mmHg;p < 0.001) and mean (92.4 ± 13.4 vs. 90.7 ± 11.4 mmHg;p < 0.001) arterial pressures were higher and diastolic pressures lower (70.4 ± 11.5 vs. 71.5 ± 9.8 mmHg;p < 0.001). The reproducibility of the Finapres and invasive method was similar for systolic (4.6% vs. 4.0%), diastolic (2.8% vs. 2.7%) and mean (3.3% vs. 3.0%) blood pressures. Second, in seven subjects studied twice at rest and during 4 min supine bicycle exercise, the exercise increase in blood pressure was greater on the Finapres compared with the brachial intra-arterial pressure (systolic +10.2 ± 6.3 vs. +3.6 ± 9.8 mmHg; diastolic +9.6 ± 11.1 vs. +0.2 ± 2.1 mmHg;p = 0.02 for each); however, at steady-state the peak/trough differences in pressure between the methods were similar. Thirdly, compared under rest conditions, to random zero sphygmomanometer (RZO), the Finapres systolic pressure was higher (6.8 ± 3.5 mmHg) and diastolic pressure lower (–6.0 ± 1.9 mmHg). During upright bicycle exercise, the difference between the Finapres and RZO in systolic blood pressure increased at each level of exercise (+14.3 ± 4.2, +17.9 ± 4.0 and +22.2 ± 4.1 mmHg respectively at each exercise stage:p < 0.01). For RZO, diastolic blood pressure fell as exercise workload increased whereas Finapres diastolic blood pressure increased on exercise (3.1 ± 2.6, 7.0 ± 2.1 and 8.1 ± 2.0 mmHg respectively:p < 0.01). Thus there were systematic differences between the values recorded by the Finapres and proximal blood pressure methods and limited agreement in the rest to exercise increments related to light exercise. Calibration of the Finapres values in terms of the other methods is limited by the variable relationship to these related changes in arterial distensibility.