Early indicators of bipolar risk in preschool offspring of parents with bipolar disorder

BACKGROUND

Offspring of parents with bipolar disorder (BD-I/II) are at increased risk to develop the disorder. Previous work indicates that bipolar spectrum disorder (BPSD) is often preceded by mood/anxiety symptoms. In school-age offspring of parents with BD, we previously built a risk calculator to predict BPSD onset, which generates person-level risk scores. Here, we test whether preschool symptoms predict school-age BPSD risk.

METHODS

We assessed 113 offspring of parents with BD 1-3 times during preschool years (2-5 years old) and then approximately every 2 years for a mean of 10.6 years. We used penalized (lasso) regression with linear mixed models to assess relationships between preschool mood, anxiety, and behavioral symptoms (parent-reported) and school-age predictors of BPSD onset (i.e., risk score, subthreshold manic symptoms, and mood lability), adjusting for demographics and parental symptomatology. Finally, we conducted survival analyses to assess associations between preschool symptoms and school-age onset of BPSD and mood disorder.

RESULTS

Of 113 preschool offspring, 33 developed new-onset mood disorder, including 19 with new-onset BPSD. Preschool irritability, sleep problems, and parental factors were lasso-selected predictors of school-age risk scores. After accounting for demographic and parental factors, preschool symptoms were no longer significant. Lasso regressions to predict mood lability and subthreshold manic symptoms yielded similar predictors (irritability, sleep problems, and parental affective lability), but preschool symptoms remained predictive even after adjusting for parental factors (ps < .005). Exploratory analyses indicated that preschool irritability univariately predicted new-onset BPSD (p = .02) and mood disorder (p = .02).

CONCLUSIONS

These results provide initial prospective evidence that, as early as preschool, youth who will develop elevated risk scores, mood lability, and subthreshold manic symptoms are already showing symptomatology; these preschool symptoms also predict new-onset BPSD. While replication of findings in larger samples is warranted, results point to the need for earlier assessment of risk and development of early interventions.

0491 Sleep among Adolescents in Juvenile Detention

Introduction

Adolescents involved in the juvenile justice system demonstrate high rates of psychiatric disorders, suicidality, and trauma, all of which is associated with poor sleep. Poor sleep is common among adolescents and is associated with numerous adverse outcomes like inattention, school absenteeism, emotion dysregulation, and substance use, outcomes that are related to juvenile justice system involvement. Yet very little is known about the sleep of adolescents involved in the juvenile justice system. We conducted a medical chart review and survey of detained adolescents to describe the sleep patterns and problems among these youth.

Methods

We reviewed a random sample (26%) of the medical charts of youth detained in a juvenile detention center (n=31) over four days in Summer 2021. We reviewed all medical encounters in the month prior to the date of chart review. Additionally, 13 youth completed the Patient Reported Outcome Measurement Information System Pediatric Sleep Disturbance Short Form (PROMIS-SD). Twelve of them reported their sleep patterns while in detention.

Results

Sleep was mentioned in 23% of all medical encounters, 62% of which indicated poor sleep. Sleep treatment was documented in 24% of notes, all consisting of pharmacotherapy. A sleep diagnosis was documented on 37% of billing sheets of all youth seen by a medical provider in the detention center in July 2021. On average, participants reported lights out around 9pm (SD=35min), sleep onset latency of 74mins (SD=75mins), wake time after sleep onset of ~20 minutes (SD=16mins), and wake-up time of 7:50am (SD=67min). Youth reported average sleep duration of more than 9 hours while detained (SD=103mins). Average PROMIS-SD score was 66.2 (range 51.5-79.1)

Conclusion

Though most youth obtain the recommended amount of sleep while detained, sleep disturbance is highly common among this population and average sleep disturbance is more than one standard deviation above the average. These data may inform the type of sleep interventions that are most relevant to detained youth. Future work should focus on further examining the sleep of adolescents in the juvenile justice system and identifying feasible, acceptable, and useful strategies for implementing evidence-based sleep interventions in this setting.

Support (If Any)

Dr. Levenson’s effort was supported by K23HD087433

281 Feasibility, Acceptability, and Preliminary Impact of a School-Based Sleep Promotion Program for Adolescents

Introduction

Poor sleep is common among adolescents and has been linked with school absenteeism. Though improved sleep has been associated with improved school outcomes, intervention programs for insufficient sleep are not standard in schools, few have used an individualized approach, and none have focused on youth with absenteeism. We conducted an open trial of the feasibility, acceptability, and initial impact of our school-based sleep promotion program among adolescents.

Methods

Participants included 8th and 9th grade students with mild absenteeism, insufficient sleep, and sleep timing shift on the School Sleep Habits Survey (SSHS). The program included a smartphone-based sleep diary and 1-2 tailored sessions with a school staff member. Participants completed baseline and follow-up research assessments. The sleep program focused on education about sleep; cognitive strategies targeting sleep beliefs; stimulus control; and regularization of sleep and wake. We descriptively report program feasibility, acceptability, and change in sleep duration.

Results

Of 33 participants approached by school staff, 12 agreed to participate and 10 completed the study. Seven participants had two program sessions and 5 participants had one program session. Sleep duration increased by 19 minutes across the entire week based on daily sleep diary, and by 31 minutes on weekdays on the SSHS. Most participants (89%) reported that the program was not a burden on their time, that the program length was just right (88%), and that they were likely to participate in research again (75%). While program feasibility was high, most youth (56%) rated program relevance as low or unknown. The most salient implementation barrier was the challenge of embedding the program into each school’s existing procedures.

Conclusion

A school-based sleep promotion program for adolescents with insufficient sleep and mild absenteeism is feasible, acceptable, and associated with improved sleep. An individualized approach, with sessions delivered by school staff, shows great promise for being feasible and clinically significant. Future work should focus on selecting a sample of youth with greater investment in the program to improve school attendance and implementing the program flexibly and with fidelity across schools.

Support (if any)

University of Pittsburgh Center for Interventions for Improve Community Health

186 Sleep among Youth During the COVID-19 Pandemic: Differences between Summer and School-Year

Introduction

Insufficient sleep is highly prevalent among school-age youth and adolescents, which has been exacerbated by the COVID-19 pandemic. However, it is unclear whether sleep during COVID-19 varies based on whether school is in session. We examined the sleep of school-age youth and adolescents during COVID-19 and described changes in rates of insufficient sleep from summer (Time 1) to school year (Time 2). We further examined whether insufficient sleep is associated with mental health service utilization.

Methods

Adults in Southwestern Pennsylvania with children under 18 years old in their household completed a repeated cross-sectional electronic survey. The survey was designed to assess usage of, and unmet need for, health and social service resources, among other health behaviors. As responses were anonymous with no longitudinal linking, we used descriptive statistics and Chi-Square tests to examine our aims at each time point. Insufficient sleep was operationalized as <9 hours (school-age youth) and <8 hours (adolescents) of sleep duration, per National Sleep Foundation standards.

Results

Data were analyzed from n=97 school-age youth and n=83 adolescents at Time 1, and n=77 school-age youth and n=82 adolescents at Time 2. Most school-age youth (76.3%) obtained sufficient sleep at Time 1, which was maintained at Time 2. However, while 75.6% of adolescents obtained sufficient sleep at Time 1, that number fell to 63.3% at Time 2. Youth with insufficient sleep were more likely to utilize mental health services than those obtaining sufficient sleep at a borderline level of statistical significance (p-value = 0.097), after controlling for age group.

Conclusion

The rate of insufficient sleep among adolescents during COVID-19 is meaningfully higher than non-COVID, school-year rates recently reported among adolescents. Youth with insufficient sleep are more likely to utilize mental health services, though the direction of causality in that association is unknown. Future work should focus on strategies for increasing access to sleep promotion programs that support sleep health and mental health during a time of great stress.

Support (if any)

Supported in part by funding to the Pittsburgh Study (Grable Foundation, Shear Family Foundation, University of Pittsburgh Department of Pediatrics, and UPMC Children’s Hospital of Pittsburgh Foundation). Dr. Levenson was supported by K23HD087433.

599 Exploring Ways to Optimize Parental Involvement in Adolescent Sleep Interventions

Introduction

Sleep is critical to the health and functioning of adolescents, but most teens do not obtain the recommended amount of sleep each night. Some sleep interventions have been efficacious in promoting sleep among adolescents, though others have had a more limited impact. One potential strategy for improving the efficacy of adolescent sleep promotion programs is to optimize the role of parents in supporting their child’s sleep. Recent findings on parental involvement in adolescent sleep suggest that monitoring can improve sleep duration but may be challenged by disagreements about sleep between parents and adolescents. Thus, it is crucial to understand how to involve parents in adolescent sleep promotion while supporting adolescent autonomy. Here, we report qualitative data on strategies for involving parents in adolescent sleep promotion in a way that is acceptable and effective. This data was collected specifically to inform the development of a sleep promotion program for adolescents.

Methods

We conducted 9 focus groups (3 each for youth, parents of adolescents, and healthcare providers treating adolescents). Transcripts of focus group proceedings were coded and thematically analyzed using inductive and deductive approaches, focusing on parents’ current role in their child’s sleep and the proposed role of parents in an adolescent sleep program.

Results

Some parents report being involved in their child’s sleep habits by setting bedtimes and supervising a consistent sleep routine. Adolescents prefer parental support that encourages child autonomy for their own sleep routine. To maintain healthy sleep habits, parents report that physicians or other trusted adults may play a key role in facilitating the negotiation of sleep habits that addresses the priorities of both parents and adolescents.

Conclusion

Our findings support adolescent preference for autonomy in their health behaviors consistent with their developing independence during this development period. Future work should focus on improved understanding of how adolescents and parents can negotiate adolescent autonomy and should examine the efficacy of a sleep promotion program based on varying levels of parental involvement.

Support (if any):

Influence of Sialic Acid on Erythrocyte Aggregation in Hypercholesterolemi

The respective role of adhesive forces induced by fibrinogen and repulsive forces induced by erythrocyte sialic acid content on erythrocyte aggregation, was investigated in hypercholesterolemic and control subjects. Aggregation index (AI) and disaggregation shear rate threshold (³t) were determined in the presence of either autologous plasma or dextran. Compared with controls, fibrinogen (p <0.001) and aggregation parameters (AI p <0.01; ³t p <0.01) were higher in hypercholester-olemics while erythrocyte sialic acid content (p <0.001) was lower; in addition total serum sialic acid was increased (p <0.01). The aggregation properties of erythrocytes, independent of plasma environment using dextran as a bridging macromolecule, showed an enhanced disaggregation shear rate threshold and an inverse relationship with erythrocyte sialic acid content. We conclude that decreased erythrocyte sialic acid content may intensify the effect of fibrinogen on aggregation and disaggregation of erythrocytes and participate in the development of atherothrombotic complications.

Sleep apnea risk and clinical correlates in patients with bipolar disorder

OBJECTIVE

Despite the high prevalence of risk factors for obstructive sleep apnea (OSA) among individuals with bipolar disorder, the presence of sleep-disordered breathing has not been systematically assessed in this population. In this study, we sought to determine the level of risk for OSA in a population of remitted individuals with a diagnosis of bipolar I disorder.

METHODS

A total of 72 individuals with a diagnosis of bipolar I disorder, all of whom were overweight by the World Health Organization criteria, completed the Berlin Questionnaire, a self-assessment tool to establish risk for OSA.

RESULTS

Over half of this study population (54.1%) was found to be in the high-risk category for OSA. Participants at high risk for OSA scored significantly higher on measures of both depression and mania, even when sleep items were not counted in the total scores.

CONCLUSIONS

Sleep apnea may be prevalent in patients with bipolar I disorder. Considering the substantial overlap of symptoms between OSA and depression and the potentially harmful effects of sleep disruption in patients with mood disorders, a systematic screening to assess prevalence and associated features of OSA in patients with bipolar disorder is warranted.

Simultaneous evaluation of the harms and benefits of treatments in randomized clinical trials: demonstration of a new approach

BACKGROUND

One aim of personalized medicine is to determine which treatment is to be preferred for an individual patient, given all patient information available. Particularly in mental health, however, there is a lack of a single objective, reliable measure of outcome that is sensitive to crucial individual differences among patients.

METHOD

We examined the feasibility of quantifying the total clinical value provided by a treatment (measured by both harms and benefits) in a single metric. An expert panel was asked to compare 100 pairs of patients, one from each treatment group, who had participated in a randomized clinical trial (RCT) involving interpersonal psychotherapy (IPT) and escitalopram, selecting the patient with the preferred outcome considering both benefits and harms.

RESULTS

From these results, an integrated preference score (IPS) was derived, such that the differences between any two patients' IPSs would predict the clinicians' preferences. This IPS was then computed for all patients in the RCT. A second set of 100 pairs was rated by the panel. Their preferences were highly correlated with the IPS differences (r=0.84). Finally, the IPS was used as the outcome measure comparing IPT and escitalopram. The 95% confidence interval (CI) for the effect size comparing treatments indicated clinical equivalence of the treatments.

CONCLUSIONS

A metric that combines benefits and harms of treatments could increase the value of RCTs by making clearer which treatments are preferable and, ultimately, for whom. Such methods result in more precise estimation of effect sizes, without increasing the required sample size.

Sleep and circadian rhythm abnormalities in the pathophysiology of bipolar disorder

Among other factors, bipolar disorder is characterized by disturbances in sleep and biological rhythms that typically cycle over a 24-h, or circadian period. Indeed, almost all of the functions that constitute symptoms of depression and mania (changes in mood, energy, sleep, interest, appetite, capacity for concentration, etc.) show relatively regular variation over the circadian period. Thus, it would appear logical to search for clues to the pathophysiology of bipolar disorder in the function of the circadian timing system (Wirz-Justice in Int Clin Psychopharmacol 21:S11-S15, 2006). In this chapter, we review the known sleep and biological rhythm abnormalities associated with bipolar disorder. We describe the nature of these circadian rhythm abnormalities and review the evidence supporting their role in bipolar episodes. Last, we discuss a number of pharmacologic and psychosocial treatments for bipolar disorder that target sleep and biological rhythm abnormalities, and we examine their effect on bipolar episodes and symptoms.

Elevated fear conditioning to socially relevant unconditioned stimuli in social anxiety disorder

OBJECTIVE

Though conditioned fear has long been acknowledged as an important etiologic mechanism in social anxiety disorder, past psychophysiological experiments have found no differences in general conditionability among social anxiety patients using generally aversive but socially nonspecific unconditioned stimuli (e.g., unpleasant odors and painful pressure). The authors applied a novel fear conditioning paradigm consisting of socially relevant unconditioned stimuli of critical facial expressions and verbal feedback. This study represents the first effort to assess the conditioning correlates of social anxiety disorder within an ecologically enhanced paradigm.

METHOD

Subjects with social anxiety disorder and age- and gender-matched healthy comparison subjects underwent differential classical conditioning. Conditioned stimuli included images of three neutral facial expressions, each of which was paired with one of three audiovisual unconditioned stimuli: negative insults with critical faces (US(neg)), positive compliments with happy faces (US(pos)), or neutral comments with neutral faces (US(neu)). The conditioned response was measured as the fear-potentiation of the startle-blink reflex elicited during presentation of the conditioned stimuli.

RESULTS

Only social anxiety subjects demonstrated fear conditioning in response to facial expressions, as the startle-blink reflex was potentiated by the CS(neg) versus both CS(neu) and CS(pos) among those with the disorder, while healthy comparison subjects displayed no evidence of conditioned startle-potentiation. Such group differences in conditioning were independent of levels of anxiety to the unconditioned stimulus, implicating associative processes rather than increased unconditioned stimulus reactivity as the active mechanism underlying enhanced conditioned startle-potentiation among social anxiety subjects.

CONCLUSIONS

Results support a conditioning contribution to social anxiety disorder and underscore the importance of disorder-relevant unconditioned stimuli when studying the conditioning correlates of pathologic anxiety.

Reduction of trace but not delay eyeblink conditioning in panic disorder

OBJECTIVE

Individuals with panic disorder perceive panic attacks as unpredictable. Because predictability is fundamental to Pavlovian conditioning, failure to predict panic attacks could be due to a basic deficit in conditioning. The present study examined trace eyeblink conditioning in order to test the hypothesis that individuals with panic disorder are impaired in associative learning tasks that depend on declarative memory.

METHOD

Delay and trace eyeblink conditioning were tested in separate experimental sessions in 19 individuals meeting DSM-IV criteria for panic disorder and 19 sex- and age-matched healthy comparison subjects. In the delay paradigm, a mild puff was delivered to the eye at the end of a 500-msec tone; in the trace paradigm, the puff was delivered after a 700-msec empty "trace" interval that followed the end of the tone.

RESULTS

Patients and comparison subjects showed similar rates of conditioned responses in the delay paradigm, but patients showed reduced rates of conditioned responses in the trace paradigm.

CONCLUSIONS

These results suggest that individuals with panic disorder suffer from a deficit in declarative associative learning. Such a deficit points to impaired hippocampal function that may disrupt cognitive processing of internal and external cues predictive of a panic attack.

A single dose of the selective serotonin reuptake inhibitor citalopram exacerbates anxiety in humans: a fear-potentiated startle study

Serotonin reuptake inhibitors may increase symptoms of anxiety immediately following treatment initiation. The present study examined whether acute citalopram increased fear-potentiated startle to predictable and/or unpredictable shocks in healthy subjects. Eighteen healthy subjects each received two treatments, placebo and 20 mg citalopram in a crossover design. Participants were exposed to three conditions including one in which predictable aversive shocks were signaled by a cue, a second in which unpredictable shocks were anticipated, and a third in which no shocks were administered. Changes in aversive states were investigated using acoustic startle stimuli. Citalopram did not affect baseline startle. However, the phasic startle potentiation to the threat cue in the predictable condition was robustly increased by acute citalopram. The sustained startle potentiation in the unpredictable conditions was also increased by citalopram, but only when the drug was given during the first session. These results indicate that a single dose of citalopram is not anxiogenic in itself, but can exacerbate the expression of fear and anxiety.

Smooth muscle role on pulmonary arterial function during acute pulmonary hypertension in sheep

AIM

We determined the wall mechanical response of the pulmonary artery (PA) to acute pulmonary hypertension induced pharmacologically and by an occlusion maneuver, to study the vascular response of the local segment and its influence in the whole pulmonary circulation.

METHODS

Pulmonary pressure and diameter were measured in six anaesthetized sheep under steady-state conditions. Transient hypertension in the PA was induced by phenylephrine (PHE) and a high pressure (HP) mechanical occlusion aimed at producing the same pulse and mean pressure responses. A viscoelastic arterial wall model was applied and the elastic (E(pd)) and viscous (micro) indexes were obtained. The micro/E(pd) ratio was adopted to quantify the damping performance of the arterial wall segment. The diastolic time constant was used as an indicator of the whole pulmonary buffering function. The systemic pressure was always measured.

RESULTS

The pulmonary mean, systolic and pulse pressure increases (P < 0.05) were similar during PHE and HP, with respect to control. PHE also induced a systemic pressure rise (P < 0.05). The E(pd) elastic index increased during HP (P < 0.05) and tended to increase during PHE with respect to control. The viscous index micro only increased with PHE (P < 0.05) with respect to control and occlusion. The diastolic time constant increased with PHE with respect to control (P < 0.05).

CONCLUSIONS

A pressure rise in the PA, induced by an occlusion maneuver, increased local stiffness. Similar pressure rises with smooth muscle activation (PHE), produced both a stiffness and viscous index increase. In PHE resistance increases more than compliance decreases so that the global net effect is a longer decay time. Smooth-muscle activation enhances the local damping effect (micro/E(pd)), concomitant with the buffering function improvement.

Gender differences in wall shear-mediated brachial artery vasoconstriction and vasodilation

OBJECTIVES

We sought to investigate wall shear rate (WSR) and brachial artery diameter (BAD) changes simultaneously and to determine whether any gender differences exist in arterial reactivity.

BACKGROUND

Wall shear rate/stress and arterial reactivity are rarely assessed at the same time. Furthermore, flow-mediated vasoconstriction has received less attention than flow-mediated vasodilation in humans.

METHODS

A new noninvasive evaluation of WSR in the brachial artery, using multigated, pulsed Doppler velocimeter and a double-transducer probe moved and fixed by a robotic system, was developed.

RESULTS

The validity of the system was tested in vitro with calibrated tubes and showed a high correlation (r = 0.98, p < 0.001). In 10 men and 10 women of similar age, induction of low and high shear rates by forearm occlusion produced significant vasoconstriction and vasodilation, respectively. The time lag for maximal BAD changes was 3 min for vasoconstriction and 1 min for vasodilation. A greater half-time for vasodilation (96 +/- 6 for men and 86 +/- 12 s for women) than for shear rate (31 +/- 5 s for men and 34 +/- 4 s for women) was observed after discontinuation of occlusion. Relative BAD was correlated with WSR changes, showing a significantly higher slope in women than in men (p < 0.01). Moreover, a larger normalized arterial diameter per shear rate was observed for vasoconstriction (p < 0.01) and vasodilation (p < 0.01) in women than in men.

CONCLUSIONS

Shear-mediated arterial vasodilation and vasoconstriction were more pronounced in women than in men, suggesting different gender-related sensitivity in the regulation of large-artery vascular tone.

Do arterial effects of antihypertensive drugs depend on subject's serum cholesterol?

Effects of antihypertensive treatment on large arteries may be influenced by the type of drug and concomitant risk factors such as blood cholesterol. To explore these possibilities we investigated the common carotid artery of 20 subjects with low cholesterol and 19 subjects with high cholesterol, all with essential hypertension, randomly allocated to 3 months of treatment with nitrendipine (20 mg/d) or trandolapril (2 mg/d). Carotid parameters were determined by recording instantaneous pressure (applanation tonometry) and diameter (echotracking device) and by modeling the pressure-diameter loop to obtain the Peterson modulus, stiffness index, measured and isobaric compliances, and wall viscosity. Effects of drugs on carotid parameters did not differ, except on systolic and diastolic diameters (p < 0.01), which increased insignificantly under nitrendipine but decreased (p < 0.01) under trandolapril. Blood cholesterol status did not influence carotid effects of trandolapril, whereas patients with low and high cholesterol treated with nitrendipine exhibited significant differences in drug effects on (a) systolic and pulse pressures (p < 0.05), which decreased in patients with low cholesterol (p < 0.01, p < 0.05) but not in those with high cholesterol; (b) diastolic diameter (p = 0.05), which increased insignificantly in patients with low cholesterol but was unchanged in those with high cholesterol; and (c) wall viscosity (p < 0.01), which decreased in patients with low cholesterol (p < 0.05) but increased insignificantly in those with high cholesterol. Also, wall viscosity change under nitrendipine was positively related to the baseline blood cholesterol ( r = 0.64, p < 0.01). Thus, nitrendipine and trandolapril show noteworthy differences in their effects on the carotid artery, in particular with respect to the status of blood cholesterol, but these differences should be confirmed by larger studies.

Difference in carotid artery wall structure between Swedish and French men at low and high coronary risk

BACKGROUND AND PURPOSE

We attempted to detect a group-specific north-south difference in carotid artery intima-media thickness (IMT), a marker of subsequent cardiovascular complication, by means of a case (high risk)-control (low risk) study in French and Swedish men.

METHODS

The selection of high-risk and low-risk subjects was performed within the lower and upper percentiles of the Framingham risk distribution of 2 samples of 1000 white, male auto workers (45 to 50 years of age) in France (Renault) and Sweden (Volvo). In total, 299 men at low risk (79 French, 76 Swedish) and high risk (61 French, 83 Swedish), free from sustained hypertension, definite hypercholesterolemia, and cardiovascular disease, were included. Both common carotid arteries, by ultrasonography and central off-line computerized analysis, provided measurements of far wall media thickness, lumen diameter, and cross-sectional area IMT (CSA-IMT).

RESULTS

As compared with low-risk status, high-risk status was associated with higher IMT (P<0.001), diameter (P<0.01), and CSA-IMT (P<0.001) in French men and higher CSA-IMT (P<0.05) in Swedish men. IMT, diameter, and CSA-IMT were higher in Swedish than in French men in the low-risk group (P<0.001) and in the high-risk group (P<0.01, P<0.001, P<0.001). The multivariate analysis of the whole population showed that IMT, diameter, and CSA-IMT were associated with risk status (P<0.01, P<0.01, P<0.001) and geographic status (P<0.001).

CONCLUSIONS

These findings show that the geographic status influences carotid artery structure independent of traditional cardiovascular risk factors and that this may affect the mortality and morbidity gradient between Northern and Southern Europe.

Identification of arterial wall dynamics in conscious dogs

Viscoelastic properties determine the dynamic behaviour of the arterial wall under pulsatile pressure and flow, suggesting time- or frequency-dependent responses to changes in wall stress and strain. The objectives of the present study were: (i) to develop a simplified model to derive simultaneously the elastic, viscous and inertial wall moduli; (ii) to assess Young's modulus as a function of frequency, in conscious, chronically instrumented dogs. Parametric discrete time models were used to characterise the dynamics of the arterial system based on thoracic aortic pressure (microtransducer) and diameter (sonomicrometry) measurements in control steady state and during activation of smooth muscle with the alpha-adrenoceptor agonist phenylephrine (5 microg kg(-1) min(-1), I.V.), in eight conscious dogs. The linear autoregressive model and a physically motivated non-linear model were fitted to the input-output (stress-strain) relationship. The aortic buffering function (complex Young's modulus) was obtained in vivo from the identified linear model. Elastic, viscous and inertial moduli were significantly increased from control state ((44.5 +/- 7.7) x 10(4) Pa; (12.3 +/- 4.7) x 10(4) Pa s; (0.048 +/- 0.028) x 10(4) Pa s(2) ) to active state ((85.3 +/- 29.5) x 10(4) Pa, P < 0.001; (22.4 +/- 8.3) x 10(4) Pa s, P < 0.05; (0.148 +/- 0.060) x 10(4) Pa s(2), P < 0.05). These moduli, obtained using the linear model, did not present significant differences compared with those derived using the non-linear model. In control conditions, the magnitude of the normalised complex Young's modulus was found to be similar to that reported in previous animal studies ranging from 1 to 10 Hz. During vascular smooth muscle activation, this modulus was found to be increased with regard to control conditions (P < 0.01) in the frequency range used in this study. The frequency-dependent Young's modulus of the aortic wall was obtained for the first time in conscious, unsedated dogs. The parametric modelling approach allows us to verify that vascular smooth muscle activation increases the elastic, viscous and inertial moduli with the advantage of being able to track their time evolution. Furthermore, under activation, the aortic wall remains stiff in the physiological frequency range, suggesting the impairment of the arterial buffering function. Experimental Physiology (2001) 86.4, 519-528.

Differential effects of nifedipine and co-amilozide on the progression of early carotid wall changes

BACKGROUND

Common carotid artery intima-media thickness (IMT) progression was compared between 4 years of treatment with nifedipine and diuretic.

METHODS AND RESULTS

This study, ancillary to the International Nifedipine GITS Study: Intervention as a Goal in Hypertension Treatment (INSIGHT), involved nifedipine 30 mg or co-amilozide (hydrochlorothiazide 25 mg and amiloride 2.5 mg) with optional subsequent titration. Among 439 randomized hypertensive patients, 324 had >/=1 year of follow-up (intent-to-treat group), and 242 completed follow-up (until-end-of-study group). Ultrasonography was performed at baseline, 4 months later, and then every year. Central computerized reading provided far-wall IMT, diameter, and cross-sectional area IMT (CSA-IMT). The primary outcome was IMT progression rate (slope of IMT-time regression). Secondary outcomes were changes from baseline (Delta) in IMT, diameter, and CSA-IMT. In the until-end-of-study population, between-treatment differences existed in IMT progression rate (P=0.002), Delta IMT (P=0.001), and Delta CSA-IMT (P=0.006), because IMT progressed on co-amilozide but not on nifedipine. In the intent-to-treat population, treatment differences existed in Delta IMT (P=0.004) and Delta CSA-IMT (P=0.04) but not in IMT progression rate (P=0.09). Patients with >/=2, 3, or 4 years of follow-up showed treatment differences in IMT progression rate (P=0.04, 0.004, 0.007, respectively), Delta IMT (P=0.005, 0.001, 0.005), and Delta CSA-IMT (P=0.025, 0.013, 0.015). Diameter decreased more on co-amilozide than on nifedipine in the intent-to-treat population (P<0.05), whereas blood pressure decreased similarly on both treatments.

CONCLUSIONS

A difference in early carotid wall changes is shown between 2 equally effective antihypertensive treatments.

Effect of hypertension on viscoelasticity of large arteries in humans

Two traditional methodologic approaches, the analysis of the arterial pressure waveform in the time domain and the measurement of pulse wave velocity along the arterial tree, have been extensively used to determine the distensibility of large arteries in humans. They have shown that large artery walls are stiffened in the presence of hypertension. However, several methodologic limitations, especially the incapability of these methods to take into account the physiologic pressure-dependence of arterial distensibility, have led to the development of new approaches for characterizing more in depth the elastic and viscous properties of large arteries. The noninvasive recording of instantaneous pressure and diameter waveforms in superficial arteries (carotid or femoral) by means of tonometry and ultrasonography allows, via appropriate model of the arterial wall, determination of the pure elastic properties as well as the wall viscosity of the vessel. Using case (hypertensive)-control (normotensive) studies it has been found that elastic alteration (stiffening) was preferential in the femoral artery rather than in the carotid artery and that viscous alteration (increased wall viscosity) was relatively uniform in both arteries. This topographic dissociation between elastic and viscous responses of the arterial wall to hypertension suggests that the elastic alteration might be a local phenomena dependent on the singularities of the arterial system, whereas abnormal wall viscosity may reflect a more general influence of hypertension on large artery smooth muscle, the likely determinant factor of viscosity. Therefore, the elastic and viscous components of the arterial walls should be considered independently when assessing the development of hypertensive vascular change and its response to antihypertensive treatment.

Long-term regulation of neuronal high-affinity glutamate and glutamine uptake in Aplysia

An increase in transmitter release accompanying long-term sensitization and facilitation occurs at the glutamatergic sensorimotor synapse of Aplysia. We report that a long-term increase in neuronal Glu uptake also accompanies long-term sensitization. Synaptosomes from pleural-pedal ganglia exhibited sodium-dependent, high-affinity Glu transport. Different treatments that induce long-term enhancement of the siphon-withdrawal reflex, or long-term synaptic facilitation increased Glu uptake. Moreover, 5-hydroxytryptamine, a treatment that induces long-term facilitation, also produced a long-term increase in Glu uptake in cultures of sensory neurons. The mechanism for the increase in uptake is an increase in the V(max) of transport. The long-term increase in Glu uptake appeared to be dependent on mRNA and protein synthesis, and transport through the Golgi, because 5,6-dichlorobenzimidazole riboside, emetine, and brefeldin A inhibited the increase in Glu uptake. Also, injection of emetine and 5,6-dichlorobenzimidazole into Aplysia prevented long-term sensitization. Synthesis of Glu itself may be regulated during long-term sensitization because the same treatments that produced an increase in Glu uptake also produced a parallel increase in Gln uptake. These results suggest that coordinated regulation of a number of different processes may be required to establish or maintain long-term synaptic facilitation.

Gender difference in the influence of smoking on arterial wall thickness

BACKGROUND

We hypothesized that arterial wall thickening, an early atherogenic alteration, might be associated with smoking differently according to gender, considering the cardiovascular protection of female sex hormones.

METHODS AND RESULTS

We measured ultrasonographically carotid and femoral intima-media thickness (IMT) in 194 men and 330 women without risk factors other than smoking. In men: (i) current smokers had greater carotid and femoral IMT (P<0.01, P<0.001) and former smokers had greater femoral IMT (P<0.01) than never smokers; (ii) in pooled never, current and former smokers carotid and femoral IMT correlated to current daily smoking (P<0.01) and lifelong smoking (P<0.001); and (iii) carotid and femoral IMT correlated to age in never smokers (P<0.001), current smokers (P<0.01, P<0.001) and former smokers (P<0.01), with greater slopes in current than in former smokers at carotid site (P<0.05) and in current than in never smokers at femoral site (P<0.05). In women: (i) IMT did not differ by smoking status; (ii) in pooled smokers and non smokers femoral IMT correlated to current daily smoking (P=0.01) and to lifelong smoking (P<0.01) with a lower slope than in men (P<0.001), while carotid IMT did not; and (iii) carotid and femoral IMT correlated to age in never smokers (P<0.001), current smokers (P<0.001, P<0.05) and former smokers (P<0.001, P<0.01) with no different slopes.

CONCLUSION

Smoking-related increase in IMT existed in men but not in women, suggesting a possible protection of female gender from early structural arterial alteration of smoking.

[Blood and arterial wall rheology and cardiovascular risk factors]

The vascular endothelium and circulating blood cells are exposed to a hemodynamic environment related to the pulsatile nature of the pressure and blood flow which influence the morphology, the physical properties and the metabolism of the cells. Among these mechanical forces, shear stresses, related to the speed gradients and to the blood viscosity, control vascular vasomotor tone and thrombogenecity, stimulating the production of the endothelial factors of relaxation or contraction, of the coagulation factors or activating erythrocyte and platelet aggregation or disaggregation phenomena. Low shear stress is considered to be a critical factor in the causation of thickening of the arterial wall and in the formation of atheromatous plaques. These plaques develop predominantly in specific parts of the arterial tree where asymmetries in the velocity profiles occur. A close relationship has been found in a large general population between plasma viscosity and thickening of the carotid bifurcation. The blood cells share the same environment as the endothelial cells. Thus, the shear stresses to which the erythrocytes are submitted is a major determinant of the blood viscosity. Shear is also an important physiological parameter regulating platelet aggregation in flowing suspensions. However, in vivo, the response of platelets depends on the balance between activation of the platelets by shear and the same rheological forces acting on the endothelial cells which produce mediators which inhibit this activation in order to maintain blood fluidity.

Localization of glutamate and glutamate transporters in the sensory neurons of Aplysia

The sensorimotor synapse of Aplysia has been used extensively to study the cellular and molecular basis for learning and memory. Recent physiologic studies suggest that glutamate may be the excitatory neurotransmitter used by the sensory neurons (Dale and Kandel [1993] Proc Natl Acad Sci USA. 90:7163-7167; Armitage and Siegelbaum [1998] J Neurosci. 18:8770-8779). We further investigated the hypothesis that glutamate is the excitatory neurotransmitter at this synapse. The somata of sensory neurons in the pleural ganglia showed strong glutamate immunoreactivity. Very intense glutamate immunoreactivity was present in fibers within the neuropil and pleural-pedal connective. Localization of amino acids metabolically related to glutamate was also investigated. Moderate aspartate and glutamine immunoreactivity was present in somata of sensory neurons, but only weak labeling for aspartate and glutamine was present in the neuropil or pleural-pedal connective. In cultured sensory neurons, glutamate immunoreactivity was strong in the somata and processes and was very intense in varicosities; consistent with localization of glutamate in sensory neurons in the intact pleural-pedal ganglion. Cultured sensory neurons showed only weak labeling for aspartate and glutamine. Little or no gamma-aminobutyric acid or glycine immunoreactivity was observed in the pleural-pedal ganglia or in cultured sensory neurons. To further test the hypothesis that the sensory neurons use glutamate as a transmitter, in situ hybridization was performed by using a partial cDNA clone of a putative Aplysia high-affinity glutamate transporter. The sensory neurons, as well as a subset of glia, expressed this mRNA. Known glutamatergic motor neurons B3 and B6 of the buccal ganglion also appeared to express this mRNA. These results, in addition to previous physiological studies (Dale and Kandel [1993] Proc Natl Acad Sci USA. 90:7163-7167; Trudeau and Castellucci [1993] J Neurophysiol. 70:1221-1230; Armitage and Siegelbaum [1998] J Neurosci. 18:8770-8779)) establish glutamate as an excitatory neurotransmitter of the sensorimotor synapse.

Association of plasma viscosity and carotid thickening in a French working cohort

Plasma viscosity and intima-media thickness (IMT) are frequently associated with cardiovascular disease and its risk factors. We evaluated the association of rheologic and vascular factors in asymptomatic subjects. Plasma viscosity (coaxial cylinder viscometry) and both preintrusive and intrusive atherosclerosis in the carotid arteries (ultrasonography) were investigated in 246 men and 337 women aged 17 to 65 years from the AXA study, a prospective cohort of healthy workers. Plasma viscosity was positively related to age-adjusted mean bifurcation carotid artery IMT (P < .01 for men; P < .04 for women) and maximum carotid artery IMT (P < .01 for men; P < .02 for women), but not to mean common carotid artery IMT. Multivariate adjustment affected these relations to a greater extent in men than in women. The odds ratio (range) of having intrusive atherosclerosis in relation to 1 SD greater plasma viscosity was 2.27 (1.52 -3.38) in men and 1.63 (1.17-2.26) in women. Adjustment of age, waist-to-hip ratio, smoking, hypercholesterolemia, hypertension, diabetes, and fibrinogen had very little effect on the magnitude of these odds ratios. Thus, plasma viscosity was associated with carotid thickening, suggesting that rheologic factors are involved in the subclinical phase of atherosclerosis.

Feasibility and reliability of ankle/arm blood pressure index in preventive medicine

Despite its potential usefulness for assessing preclinical atherosclerosis and cardiovascular risk, the ankle/arm blood pressure index (AAI) has not yet been the matter of study evaluating its feasibility and reliability by nonspecialist doctors in a general population. This study was planned for two steps. In step 1, the measurement of AAI, (ratio between Doppler systolic pressure at the ankle for each lower limb and the highest value of Doppler systolic pressure of the two upper limbs), should be performed by 50 general practitioners (GPs), 50 social security center physicians, and 50 occupational health physicians in 3,000 male smokers, 40 to 59 years, without clinical cardiovascular disease. In step 2, AAI measurement, coupled with echography-Doppler of iliofemoral arteries, should be repeated by a specialist in all subjects with decreased AAI (<0.90) and the first two subjects with normal AAI recruited in step 1 by each nonspecialist. The number of physicians and subjects participating in step 1 was lower than planned (80 physicians and 962 subjects) with the greatest defect for GPs (six physicians and 35 subjects) and the prevalence of decreased AAI was low (28 subjects). AAI measurement was repeated in step 2 in only 12 subjects with decreased AAI in step 1 and in 124 subjects with normal AAI in step 1. Five of the six subjects with decreased AAI in step 2 also had decreased AAI in step 1 and 123 of the 130 subjects with normal AAI in step 2 also had normal AAI in step 1. As regards echographic stenosis, decreased AAI had a sensitivity of 44% and a specificity of 98%. AAI seems more feasible for occupational health physicians and social security center physicians and AAI is also reliable for nonspecialists previously trained, but its predictive value as regards echographic stenosis is poor in asymptomatic subjects, which may limit its usefulness for detecting preclinical atherosclerosis.

Distribution of ultrasonographically-assessed dimensions of common carotid arteries in healthy adults of both sexes

Our objective was to provide a description of 'normal' carotid artery dimensions which are increasingly used for detecting early atherosclerosis and predicting clinical complications. Far wall intima-media thickness (IMT), lumen diameter and cross-sectional area intima-media thickness (CSA-IMT) were measured on 1 cm-distal common carotid artery segments on both sides by B-mode ultrasound, using an automated computerized edge-detection program, in 133 men and 216 women aged 17-65 years and free from cardiovascular disease and traditional risk factors. IMT and CSA-IMT increased with age in both sexes and on both sides, while diameter did not, except on the right side in men. Women had lower diameter than men except on the left side at 30 years or below, while IMT did not differ between sexes except on the left side from 31 to 50 years where IMT was higher in men; as a result of their lower diameter, women had lower CSA-IMT than men except on the right side above 50 years. IMT was lower on the right side than on the left side in both sexes, except in 30-year old or younger men and 31- to 40-year old women, while diameter was higher on the right side than on the left side in men and women aged 31-40 years and in women aged 41-50 years; also CSA-IMT was lower on the right side than on the left side in both sexes above 40 years. These data provide reference values of carotid artery dimensions and show that age, sex and side of measurement should be taken into account in the interpretation of 'normal' values of IMT and diameter in clinical practice and trials.

Carotid wall inertial index increase is related to intima-media thickening in hypertensive patients

OBJECTIVE

The aim of this study is to evaluate the relationship between carotid intima-media thickness (IMT) and arterial wall inertial behaviour.

METHODS

The simultaneous and noninvasive assessment of the intima-media complex and arterial diameter waveform was performed using high-resolution ultrasonography. The common carotid artery of eleven normotensive subjects (NTA) and eleven mild-to-moderate essential hypertensive patients (HTA) were measured noninvasively using tonometry and an automatic densitometric analysis of B-mode images to obtain IMT and instantaneous pressure (P) and diameter (D) loops. A linear discrete time model was used to estimate the inertial index (K(M)) using a system modelling-identification approach.

RESULTS

In NTA K(M) was 0.333+/-0.256 (mmHg x s2/mm) and IMT 0.643+/-0.061 (mm), whereas in HTA K(M) was 0.798+/-0.590 (P < 0.05) and IMT 0.760+/-0.034 (P < 0.025). When all data of K(M) versus IMT of NTA and HTA were pooled in a linear regression analysis, a correlation coefficient of r = 0.61 (P < 0.05) was obtained.

CONCLUSION

Wall inertia increase was associated with a higher IMT, suggesting that the intima-media thickening might be partially related to vascular hypertrophy manifested as increase of inertial behaviour.

Experimental and clinical validation of arterial diameter waveform and intimal media thickness obtained from B-mode ultrasound image processing

A new automated computerized system (IôTEC) that assesses concomitantly the instantaneous temporal arterial diameter and intimal media thickness (IMT) obtained from B-mode ultrasound (US) images was validated by sonomicrometry in sheep, by an echo-tracking system in humans, and by a Lucite phantom in vitro. Differences between methods for diameter measurements did not vary in any systematic way, with no significant differences in the lower frequency range. Ultrasonic measurements of the true phantom gap sizes showed high correlation (r2 = 0.98,p < 0.001) with no systematic errors. Carotid and femoral arteries in humans were strongly related between IôTEC and echo-tracking device (r2 = 0.94 carotid; R2 = 0.88 femoral, p < 0.001), with a Gaussian distribution of the errors. This new method showed high intra- and interobserver repeatability of arterial diameter and IMT, allowing consistent characterization of arterial dynamics in humans.

Levels of serotonin in the hemolymph of Aplysia are modulated by light/dark cycles and sensitization training

Serotonin (5-hydroxytryptamine, 5-HT) modulates the behavior and physiology of both vertebrate and invertebrate animals. Effects of injections of 5-HT and the morphology of the serotonergic system of Aplysia indicate that 5-HT may have a humoral, in addition to a neurotransmitter, role. To study possible humoral roles of 5-HT, we measured 5-HT in the hemolymph. The concentration of 5-HT in the hemolymph was approximately 18 nM, a value close to previously reported thresholds for eliciting physiological responses. The concentration of 5-HT in the hemolymph expressed a diurnal rhythm. In addition, electrical stimulation that leads to long-term sensitization significantly increased levels of 5-HT in the hemolymph during training, 1.5 hr after training, and 24 hr after training. Moreover, levels of 5-HT in the hemolymph were significantly correlated with the magnitude of sensitization. The half-life of an increase in 5-HT in the hemolymph was approximately 0.5 hr. Therefore, the persistent increase of 5-HT in the hemolymph 24 hr after sensitization training indicates that training caused a long-lasting increase in the release of 5-HT. This long-lasting increase in 5-HT in the hemolymph was blocked by treatment with an inhibitor of protein synthesis during training. Based on the levels of 5-HT in the hemolymph and its regulation by environmental events, we propose that 5-HT has a humoral role in regulation of the behavioral state of Aplysia. In support of this hypothesis, we found that increasing levels of 5-HT in the hemolymph led to significant alterations in feeding behavior. Increasing levels of 5-HT during the daytime when they were normally low increased the latency to assume feeding posture from daytime to nighttime values.

Aging affects the ocular circadian pacemaker of Aplysia californica

The eye of Aplysia has been used to explore various aspects of circadian rhythms. The authors discovered that age has profound effects on the circadian rhythm of nerve impulses from the eye. With age, there was a significant decrease in the amplitude of the rhythm. The decrease appeared to be continuous over the life span of the animal and was observed both in vitro and in vivo. The free-running period and phase angle of the rhythm steadily increased with age, indicating that the pacemaker itself was affected by age. Rates of transcription and translation were significantly increased with age, suggesting that age-associated alterations of the pacemaker may occur through changes in macromolecular synthesis. Interestingly, eyes from some older (> or = 10 months) animals had "cloudy" lenses (cataracts). Highly damped or arrhythmic rhythms always were seen in eyes with cloudy lenses. Morphology of eyes with cloudy lenses indicated severe retinal degeneration. No such degeneration was observed in eyes with clear lenses that were used in the analysis of the rhythm with age.

Influence of hypercholesterolemia and endothelin-3 pre-treatment on the effects of shear forces on platelet aggregation and cyclic GMP content

Shear forces induce platelet aggregation and stimulate the endothelial production of anti-aggregatory factors. Among them, endothelin-3 (ET-3) has been reported to reduce aggregation and to increase platelet cyclic GMP (cGMP) content. Since hypercholesterolemia modifies both platelet aggregability and endothelial function, we compared in 14 hypercholesterolemic and 15 normocholesterolemic subjects the influences of shear forces (240 and 650 s(-1)) on platelet aggregation and cGMP content, and their modulation by ET-3. Spontaneous maximal aggregation occurred earlier and at a greater extent in hypercholesterolemic than in normocholesterolemic subjects (63+/-2 vs 46+/-6% P < 0.01). Pre-treatment with ET-3 abolished the shear-induced facilitation of maximal aggregation in platelets of normocholesterolemic (from 70+/-2 to 52+2% at 240 s(-1) and from 73+/-1 to 59+/-2S at 650s(-1); P < 0.05) and hypercholesterolemic (from 78+/-3 to 64+/-2 at 240 s(-1) and from 78+/-2 to 66+/-3 at 650 s(-1); P < 0.05) subjects. cGMP content did not significantly differ between normocholesterolemic and hypercholesterolemic subjects (6.1+/-0.5 vs 6.9+/-0.7 pmol/10(9) platelets). It was reduced in platelets submitted to shear forces (P < 0.05). This shear-dependent reduction was suppressed by ET-3 pre-treatment. These results demonstrate that shear forces enhance platelet aggregation and diminish their cGMP content. ET-3 reduces the pro-aggregating effects of shear, suggesting a rise in cGMP content as a dynamic associated mechanism.

Predictive value of waist-to-hip ratio on cardiovascular risk events

BACKGROUND

A central distribution of adipose tissue is frequently associated with cardiovascular disease (CVD) and its risk factors.

METHODS

Clinical usefulness of waist-to-hip ratio (WHR) for predicting the risk of cardiovascular events, estimated with models based on data from the Framingham and Prospective Cardiovascular Münster (PROCAM) studies was evaluated.

SUBJECTS

These were 552 men and 160 women, asymptomatic and at risk for CVD, aged 30-74 y, recruited from an ongoing risk factor screening program conducted at worksites.

RESULTS

Abdominal fatness was a strong predictor of cardiovascular complications in subjects whose WHR was in the top quintile (> 0.98 for men and > 0.91 for women). The estimated percentage rate of coronary heart disease (CHD, P <0.01) and death (P < 0.01), myocardial infarction (P < 0.01), stroke (P < 0.01), total CVD (P < 0.001) and death (P < 0.01) increased with increasing quintile of WHR in men and women. In the highest WHR, the number of subjects exceeding a 15% risk of developing a coronary event over the next 10 y was more than two-fold greater (odds ratio (OR) 2.60 (confidence intervals (CI) 1.09-6.54) than in the lowest WHR quintiles. Similar six-year myocardial infarction (MI) risks at each quintile of WHR were observed in men in both Framingham and PROCAM models. In the overall population, CHD estimates increased with increasing quintiles of WHR with the Framingham model and an adapted model for estimating probabilities of disease in the French population of the Prevention Cardiovasculaire en Médecine du Travail (PCV-METRA) group.

CONCLUSION

Abdominal deposition of fat assessed by WHR may be of strong clinical value for predicting high risk of cardiovascular events.

Decreased regional blood flow in patients with acromegaly

BACKGROUND AND AIMS

One-third of acromegalic patients have hypertension. Acromegaly is also associated with intrinsic cardiac abnormalities known collectively as a hyperkinetic heart syndrome, which is characterized by an increased cardiac index and decreased systemic vascular resistance. As a result, blood flow should be increased in the regional vascular beds of acromegalic patients. The aim of the study was to measure, using direct methods, blood flow and vascular resistance at the level of the brachial artery in acromegalic patients with a confirmed hyperkinetic heart syndrome.

PATIENTS AND CONTROLS

Twelve patients with active acromegaly (five females, seven males; mean (+/- SD) age, 43 +/- 10 years) were studied. Twelve age- and sex-matched normal subjects served as controls.

METHODS

Right heart catheterization was used to measure the cardiac index and stroke volume and to calculate systemic vascular resistance in the acromegalic patients. Brachial haemodynamics were evaluated with a two-dimensional pulsed Doppler system (double transducer probe and range-gated time system of reception). The mean diameter of the brachial artery and mean blood velocity were measured and used to calculate mean blood flow. Vascular resistance was calculated in the brachial artery as the mean arterial pressure/blood flow ratio.

RESULTS

Age, body weight, height, body surface area and heart rate were similar in the acromegalic patients and controls, while mean arterial pressure was higher in patients. The cardiac index and stroke volume were increased in the acromegalic patients, at 4.08 +/- 0.47 (mean +/- SD) l/min/m2 body surface area and 116.7 +/- 19.4 ml, respectively, while systemic vascular resistance was low (12.5 +/- 2.1 U). Brachial artery diameter was similar in the patients and controls. Brachial artery mean blood velocity (P < 0.01) and mean blood flow (P < 0.05) were lower in the patients than in the controls (3.35 +/- 1.26 vs. 5.12 +/- 1.74 cm/s, and 16.4 +/- 9.4 vs. 25.6 +/- 11.6 ml/min/m2, respectively). The higher mean arterial pressure and lower mean blood flow resulted in higher forearm vascular resistance in the patients than in the controls (132 +/- 61 vs. 83.8 +/- 47 mmHg/ml/s/m2, respectively, P < 0.01).

CONCLUSION

While cardiac output is increased and systemic vascular resistance is decreased in active acromegaly, direct measurement of brachial artery haemodynamics showed lower regional blood flow and increased local resistance relative to healthy controls. These results suggest a heterogeneous distribution of cardiac output in acromegaly.

Evidence of carotid artery wall hypertrophy in homozygous homocystinuria

BACKGROUND

We aimed to determine whether intima-media thickness (IMT) was increased in the carotid artery of subjects with homocystinuria to better understand the in vivo contribution of homocysteine to early atherogenesis.

METHODS AND RESULTS

We investigated ultrasonographically the right common carotid artery in 14 subjects with homozygous homocystinuria aged 3 to 34 years (mean, 13 years) and in 15 of their heterozygous parents aged 32 to 47 years (mean, 41 years) by comparison with 2 control groups of 15 healthy subjects of the same age. Far-wall IMT and lumen diameter were measured with a computerized program, and the cross-sectional area of the intima-media complex (CSA-IMC) was calculated from IMT and diameter. Comparison with their respective controls, adjusted for body surface area or height, showed that homozygotes had greater IMT (P<0.001) and CSA-IMC (P<0.05) and smaller diameter (P<0.05), whereas heterozygotes had values similar to their controls. Multivariate analysis of the arterial parameters with age, body surface area (or height), and plasma total homocysteine in the homozygous and heterozygous groups combined showed that IMT was related to age (P<0.05) and homocysteine (P<0.01), diameter was related to body surface area (P<0.001) or height (P<0.05), and CSA-IMC was related to age (P<0.05), body surface area (P<0.05) (but not height), and homocysteine (P<0.05).

CONCLUSIONS

Homozygous homocystinuria was associated with common carotid wall hypertrophy, whereas heterozygous disease was not. Such hypertrophy may reflect a smooth muscle proliferation induced by hyperhomocysteinemia and represent a promising target for testing vascular effects of therapeutic measures to lower homocysteine.

Erythrocyte disaggregation shear stress, sialic acid, and cell aging in humans

Erythrocyte aggregation, which plays an important role in the physiological behavior of blood fluidity, was found to be enhanced in hypertension and hypercholesterolemia. While the role of macromolecule bridging force has been widely described, cellular factors related to membrane sialic acid content, which might contribute to the negative charge of cell surface causing the repulsion of erythrocytes, have been less studied. Cell age-dependent changes in membrane sialic acid content (in micromoles per gram of integral membrane protein) were investigated in 24 normotensive and 24 hypertensive matched subjects, each divided into 2 identical subgroups according to a cutoff of 6.2 mmol/L serum cholesterol. A progressive and significant (P<0.001) decrease in membrane sialic acid content associated with an increase (P<0.001) of disaggregation shear rate threshold (laser reflectometry in the presence of dextran) were observed with increased erythrocyte density (erythrocytes fractionated by density using ultracentrifugation) in both normotensive and hypertensive groups regardless of the cholesterol level. However, disaggregation shear rate threshold was significantly higher and sialic acid content was lower (P<0.001) in both hypertensive and normotensive subjects with hypercholesterolemia compared with either normotensive or hypertensive subjects with low cholesterol, respectively. A high membrane sialic acid content variance, beginning in the younger erythrocytes, was due mainly to triglyceride and LDL cholesterol levels (R2=0.49 for low, R2=0.43 for middle, and R2=0.54 for high densities, ie, young, mean, and senescent erythrocytes, respectively). We conclude that an early decrease in erythrocyte sialic acid content may influence the rheological properties of blood by increasing the adhesive energy of erythrocyte aggregates.

Utility of electrocardiogram for predicting increased left ventricular mass in asymptomatic men at risk for cardiovascular disease

The objective of this study was to test the value of electrocardiogram for predicting left ventricular mass (LVM), assessed echographically in 136 asymptomatic men with at least one major cardiovascular risk factor. We measured the Sokolow-Lyon and Cornell voltages, as well as the ratio of Cornell voltage to QRS voltage in lead II. The prevalence of left ventricular hypertrophy (LVH), defined as LVM of > or = 125 g/m2, was 6%, whereas that of increased LVM, defined as LVM of > or = 99 g/m2, the 90th upper percentile of a control group, was 29%. Receiver operating characteristics curves showed that for predicting LVH at 80% specificity, the Cornell/QRS(II) voltage ratio had a sensitivity of 75%, whereas those of the Cornell and Sokolow-Lyon voltages were 50% and 12.5%, respectively. For predicting increased LVM at 80% specificity, the Cornell/QRS(II) voltage ratio had a sensitivity of 56%, whereas the sensitivities of the Cornell and Sokolow-Lyon voltages were 36% and 22%, respectively. We conclude that, in constrast with the Sokolow-Lyon voltage, the new dimensionless Cornell/QRS(II) voltage shows a sensitivity at a high specificity value at least as acceptable as that of the Cornell voltage for predicting borderline-high LVM in a population with a low prevalence of LVH.

Early atherosclerosis in human hypertension

The detection of preclinical atherosclerosis may contribute to better identifying hypertensive subjects at high risk of complications. Three alterations can be diagnosed noninvasively: calcification, thickening, and stiffening of the arterial wall. Their prevalence is increased in asymptomatic hypertensives and their presence may have important prognostic significance, especially with respect to coronary artery disease. They are also ideal targets to test the efficacy of hypertensive therapy on the arterial wall. Finally, the detection of early atherosclerosis may help to improve the clinical management of hypertensive patients.

Sex and topographic differences in associations between large-artery wall thickness and coronary risk profile in a French working cohort: the AXA Study

Previous reports have investigated associations between carotid intima-media thickness (IMT) and cardiovascular risk factors. Our objective was to investigate this question in greater depth by measuring both femoral and carotid IMT in relation to sex and multifactorial coronary risk. We investigated carotid and femoral artery IMT by using ultrasonography in 326 men and 462 women, 17 to 65 years old. We also evaluated body mass index, blood pressure, blood lipids, glucose, smoking, and Framingham coronary risk. In both vessels, IMT was lower in women than in men. Significant relations between carotid and femoral IMT existed with age and most risk factors in both sexes. After adjustment for age, carotid IMT was related to risk factors in both sexes except for diastolic blood pressure, HDL cholesterol, and smoking in women, whereas femoral IMT was related to triglycerides and smoking in both sexes, systolic blood pressure and blood glucose in men, and total and HDL cholesterol in women. Significant unadjusted and age-adjusted relations of Framingham risk existed with carotid and femoral IMT in both sexes, but slopes of these relations were greater (1) before than after age adjustment, (2) in men than in women at both sites, except the femoral artery after age adjustment, and (3) at the carotid than at the femoral site in both sexes before age adjustment. Carotid IMT in men appears to be a more powerful predictor than it is in women and femoral IMT in both sexes in reflecting multifactorial coronary risk burden, but these differences are partly conditional on age.

Aortic stiffening does not predict coronary and extracoronary atherosclerosis in asymptomatic men at risk for cardiovascular disease

Stiffness of aortic walls has been shown to be a marker of coronary and cerebrovascular diseases in patients with myocardial infarction or stroke. However, its value for predicting preclinical atherosclerosis has not been demonstrated. Therefore, this study tested the association of aortic wall stiffness and coronary and extracoronary atherosclerosis in the absence of clinical cardiovascular disease. In 190 asymptomatic men at cardiovascular risk, carotid-to-femoral pulse wave velocity (PWV) was measured mechanographically and the compliance of the aorta (C), as well as the intrinsic compliance (Ci), was deduced after correction for the effect of blood pressure. Also determined noninvasively were 1) the degree of coronary calcium deposit coded as grade 0, 1, 2, or 3 using ultrafast computed tomography; 2) the extent of extracoronary plaque detected by B-mode echography at three different sites (carotid, abdominal aorta, and femoral) coded as 0, 1, 2, or 3 diseased sites; and 3) the estimated Framingham coronary risk. The grade of coronary calcium was not associated with any aortic elastic parameter. The number of extracoronary diseased sites was not associated with PWV and C but correlated negatively with Ci before but not after age adjustment. The coronary risk correlated positively with PWV and negatively with C before but not after age adjustment and was not associated with Ci. In symptom-free subjects aortic stiffening does not predict the presence of coronary and extracoronary atheroma and therefore cannot be considered as a useful surrogate marker of early atherosclerosis.

Incidence of extrapyramidal syndromes in AIDS patients and a comparison group of medically ill inpatients

The authors retrospectively reviewed the charts of 29 inpatients with AIDS and 24 medically ill inpatients, all of whom were exposed to neuroleptics. Results adjusted for age, gender, type and dosage of neuroleptic, and extrapyramidal prophylaxis indicated that inpatients with AIDS were 7 times more likely to develop extrapyramidal syndromes (EPS) from neuroleptics than the comparison group of medically ill inpatients. Possible neuroanatomic, neuropathologic, and neurochemical reasons for the vulnerability of patients with AIDS to EPS are reviewed.

Preclinical changes of extracoronary arterial structures as indicators of coronary atherosclerosis in men

BACKGROUND

Carotid artery structure change was associated with coronary artery stenosis by angiography of subjects who were for the most part symptomatic.

OBJECTIVE

To determine whether structural changes at multiple extracoronary sites were associated with noninvasively detected coronary calcium for 94 asymptomatic high-risk men.

METHODS AND RESULTS

B-mode ultrasonography allowed us to detect plaque at three sites (carotid, femoral, and abdominal aorta) and to measure intima-medial thickness both in common carotid and in femoral arteries. Ultrafast computed tomography determined the presence and amount of coronary calcification. After adjustment for age, plaques at two or three sites were associated with extensive amounts of coronary calcium [odds ratio 4.94 (95% confidence interval 1.08-23)], but not with the presence of coronary calcium; increase in carotid intima-medial thickness was not associated with presence and extent of coronary calcium; and increase in femoral intima-medial thickness was associated with presence of coronary calcium [odds ratio 1.44 (95% confidence interval 1.03-2)] and extensive coronary calcium [odds ratio 1.50 (95% confidence interval 0.97-2.33)]. Adjustment for cardiovascular risk factors attenuated these associations.

CONCLUSIONS

Femoral intima-medial thickness predicted presence of coronary calcium whereas femoral intima-medial thickness and overall multiple plaques predicted extensive coronary calcium. Because coronary calcium is a marker of atherosclerosis and a predictor of coronary events, B-mode ultrasonography could be of clinical value for stratifying coronary risk.

Carotid wall viscosity increase is related to intima-media thickening in hypertensive patients

Increases in arterial wall viscosity and intima-media thickness (IMT) were found in hypertensive patients. Because smooth muscle cells are responsible for the viscous behavior of the arterial wall and they are involved in the process of thickening of the intima-media complex, this study evaluates the relationship between carotid thickness and wall viscosity. The simultaneous and noninvasive assessment of the intima-media complex and arterial diameter waveform was performed using high-resolution ultrasonography. This technique was contrasted against sonomicrometry in sheep, showing that the waveforms obtained by both methods were similar. The common carotid arteries of 11 normotensive subjects (NTA) and 11 patients with mild to moderate essential hypertension (HTA) were measured noninvasively by using tonometry and an automatic densitometric analysis of B-mode images to obtain IMT and instantaneous pressure and diameter loops. A viscoelastic model was used to derive the wall viscosity index (eta) using the hysteresis loop elimination criteria. In NTA, eta was 2.73+/-1.66 (mm Hg x s/mm) and IMT was 0.58+/-0.08 (mm), whereas in HTA, eta was 5.91+/-2.34 (P<.025) and IMT was 0.70+/-0.12 (P<.025), respectively. When all data of eta versus IMT of NTA and HTA were pooled in a linear regression analysis, a correlation coefficient of r=.71 (P<.05) was obtained. Partial correlation between eta and IMT holding constant pressure was r=.59 (P<.05). In conclusion, wall viscosity increase was associated with a higher IMT even maintaining blood pressure fixed, suggesting that the intima-media thickening might be related to smooth muscle alterations manifested as an increase in viscous behavior.