The administration of the opioid buprenorphine decreases motivational error signals

While opioid addiction has reached pandemic proportions, we still lack a good understanding of how the administration of opioids interacts with cognitive functions. Error processing - the ability to detect erroneous actions and correct one's behaviour afterwards - is one such cognitive function that might be susceptible to opioidergic influences. Errors are hypothesised to induce aversive negative arousal, while opioids have been suggested to reduce aversive arousal induced by unpleasant and stressful stimuli. Thus, this study investigated whether the acute administration of an opioid would affect error processing. In a double-blind between-subject study, 42 male volunteers were recruited and received either 0.2 mg buprenorphine (a partial µ-opioid receptor agonist and κ-opioid receptor antagonist) or a placebo pill before they performed a stimulus-response task provoking errors. Electroencephalograms (EEG) were recorded while participants performed the task. We observed no group differences in terms of reaction times, error rates, and affective state ratings during the task between buprenorphine and control participants. Additional measures of adaptive control, however, showed interfering effects of buprenorphine administration. On the neural level, decreased Pe (Error Positivity) amplitudes were found in buprenorphine compared to control participants following error commission. Further, frontal delta oscillations were decreased in the buprenorphine group after all responses. Our neural results jointly demonstrate a general reduction in error processing in those participants who received an opioid before task completion, thereby suggesting that opioids might have indeed the potential to dampen motivational error signals. Importantly, the effects of the opioid were evident in more elaborate error processing stages, thereby impacting on processes of conscious error appraisal and evidence accumulation.

Durable memories and efficient neural coding through mnemonic training using the method of loci

Mnemonic techniques, such as the method of loci, can powerfully boost memory. We compared memory athletes ranked among the world's top 50 in memory sports to mnemonics-naïve controls. In a second study, participants completed a 6-week memory training, working memory training, or no intervention. Behaviorally, memory training enhanced durable, longer-lasting memories. Functional magnetic resonance imaging during encoding and recognition revealed task-based activation decreases in lateral prefrontal, as well as in parahippocampal and retrosplenial cortices in both memory athletes and participants after memory training, partly associated with better performance after 4 months. This was complemented by hippocampal-neocortical coupling during consolidation, which was stronger the more durable memories participants formed. Our findings advance knowledge on how mnemonic training boosts durable memory formation through decreased task-based activation and increased consolidation thereafter. This is in line with conceptual accounts of neural efficiency and highlights a complex interplay of neural processes critical for extraordinary memory.

Exogenous testosterone increases status-seeking motivation in men with unstable low social status

Testosterone is associated with status-seeking behaviors such as competition, which may depend on whether one wins or loses status, but also on the stability of one's status. We examined (1) to what extent testosterone administration affects competition behavior in repeated social contests in men with high or low rank, and (2), whether this relationship is moderated by hierarchy stability, as predicted by the status instability hypothesis. Using a real effort-based design in healthy male participants (N = 173 males), we first found that testosterone (vs. placebo) increased motivation to compete for status, but only in individuals with an unstable low status. A second part of the experiment, tailored to directly compare stable with unstable hierarchies, indicated that exogenous testosterone again increased competitive motivation in individuals with a low unstable status, but decreased competition behavior in men with low stable status. Additionally, exogenous testosterone increased motivation in those with a stable high status. Further analysis suggested that these effects were moderated by individuals' trait dominance, and genetic differences assessed by the androgen receptor (CAG-repeat) and dopamine transporter (DAT1) polymorphisms. Our study provides evidence that testosterone specifically boosts status-related motivation when there is an opportunity to improve one's social status. The findings contribute to our understanding of testosterone's causal role in status-seeking motivation in competition behavior, and indicate that testosterone adaptively increases our drive for high status in a context-dependent manner. We discuss potential neurobiological pathways through which testosterone may attain these effects on behavior.

Challenges in the comparative study of empathy and related phenomena in animals

The aim of this review is to discuss recent arguments and findings in the comparative study of empathy. Based on a multidisciplinary approach including psychology and ethology, we review the non-human animal literature concerning theoretical frameworks, methodology, and research outcomes. One specific objective is to highlight discrepancies between theory and empirical findings, and to discuss ambiguities present in current data and their interpretation. In particular, we focus on emotional contagion and its experimental investigation, and on consolation and targeted helping as measures for sympathy. Additionally, we address the feasibility of comparing across species with behavioural data alone. One main conclusion of our review is that animal research on empathy still faces the challenge of closing the gap between theoretical concepts and empirical evidence. To advance our knowledge, we propose to focus more on the emotional basis of empathy, rather than on possibly ambiguous behavioural indicators, and we provide suggestions to overcome the limitations of previous research .

Acute stress alters neural patterns of value representation for others

Acute stress is often evoked during social interactions, by feelings of threat or negative evaluation by other people. We also constantly interact with others while under stress - in the workplace or in private alike. However, it is not clear how stress affects social interactions. For one, individuals could become more selfish and focused on their own goals. On the other hand, individuals might also become more focused on affiliating with potential social partners, in order to secure their support. There is, indeed, accumulating behavioral evidence that prosocial behaviors increase rather than decrease under stress. Here, we tested the underlying brain processes of such findings, by assessing the effects of stress on the neural representations of (monetary) value for self and other. Participants (N ​= ​30; male, 18-40 years) played a gambling task for themselves and for another participant while undergoing functional magnetic resonance imaging (fMRI). Each participant played the gambling task twice: once immediately following acute stress induction, and once in a control session. We compared neural patterns of value representation in the dorsomedial prefrontal cortex (dmPFC), ventromedial prefrontal cortex (vmPFC) and striatum using representational similarity analysis (RSA). We found that under stress, dmPFC and striatum showed higher dissimilarity between neural patterns underlying high and low value for the other. Dissimilarity of neural patterns underlying high and low value for the self was unaffected by stress. These findings suggest that participants track the magnitude of possible rewards for others more under stress, suggesting increased prosocial orientation.

Increased neural responses to empathy for pain might explain how acute stress increases prosociality

Recent behavioral investigations suggest that acute stress can increase prosocial behavior. Here, we investigated whether increased empathy represents a potential mechanism for this finding. Using functional magnetic resonance imaging, we assessed the effects of acute stress on neural responses related to automatic and regulatory components of empathy for pain as well as subsequent prosocial behavior. Stress increased activation in brain areas associated with the automatic sharing of others' pain, such as the anterior insula, the anterior midcingulate cortex, and the primary somatosensory cortex. In addition, we found increased prosocial behavior under stress. Furthermore, activation in the anterior midcingulate cortex mediated the effects of stress on prosocial behavior. However, stressed participants also displayed stronger and inappropriate other-related responses in situations which required them to take the perspective of another person, and to regulate their automatic affective responses. Thus, while acute stress may increase prosocial behavior by intensifying the sharing of others' emotions, this comes at the cost of reduced cognitive appraisal abilities. Depending on the contextual constraints, stress may therefore affect empathy in ways that are either beneficial or detrimental.

Default mode network deactivation during emotion processing predicts early antidepressant response

Several previous functional magnetic resonance imaging (fMRI) studies have demonstrated the predictive value of brain activity during emotion processing for antidepressant response, with a focus on clinical outcome after 6-8 weeks. However, longitudinal studies emphasize the paramount importance of early symptom improvement for the course of disease in major depressive disorder (MDD). We therefore aimed to assess whether neural activity during the emotion discrimination task (EDT) predicts early antidepressant effects, and how these predictive measures relate to more sustained response. Twenty-three MDD patients were investigated once with ultrahigh-field 7T fMRI and the EDT. Following fMRI, patients received Escitalopram in a flexible dose schema and were assessed with the Hamilton Depression Rating Scale (HAMD) before, and after 2 and 4 weeks of treatment. Deactivation of the precuneus and posterior cingulate cortex (PCC) during the EDT predicted change in HAMD scores after 2 weeks of treatment. Baseline EDT activity was not predictive of HAMD change after 4 weeks of treatment. The precuneus and PCC are integral components of the default mode network (DMN). We show that patients who exhibit stronger DMN suppression during emotion processing are more likely to show antidepressant response after 2 weeks. This is, to our knowledge, the first study to show that DMN activity predicts early antidepressant effects. However, DMN deactivation did not predict response at 4 weeks, suggesting that our finding is representative of early, likely treatment-related, yet unspecific symptom improvement. Regardless, early effects may be harnessed for optimization of treatment regimens and patient care.

From shared to distinct self-other representations in empathy: evidence from neurotypical function and socio-cognitive disorders

Neuroscientific research has identified two fundamental components of empathy: shared emotional representations between self and other, and self-other distinction. The concept of shared representations suggests that during empathy, we co-represent another person's affect by engaging brain and bodily functions underpinning the first-hand experience of the emotion we are empathizing with. This possible grounding of empathy in our own emotional experiences explains the necessity for self-other distinction, which is the capacity to correctly distinguish between our own affective representations and those related to the other. In spite of the importance of these two components in empathy, several aspects still remain controversial. This paper addresses some of them and focuses on (i) the distinction between shared activations versus representations, raising the question what shared representations entail in terms of the underlying neural mechanisms, (ii) the possible mechanisms behind self-other distinction in the cognitive and the affective domains, and whether they have distinct neural underpinnings and (iii) the consequences associated with a selective impairment of one of the two components, thereby addressing their importance in mental disorders such as autism spectrum disorders, psychopathy and alexithymia.

Cardiac Output Determination during Intravenous Cardioangiography Using X-ray Fluorescence Analysis

Cardiac output was determined with an indicator dilution technique during digital venous angiography of the left ventricle in 11 patients. The contrast medium injected into the right atrium was used as indicator. During and after the injection of contrast medium one blood sample per second was obtained through a catheter placed in the descending aorta. The samples were analyzed for iodine content with x-ray fluorescence analysis and cardiac output determined ad modum Stewart-Hamilton. Thermodilution was used as a reference method. The results indicate that the indicator dilution method with the use of contrast medium might be used for calibration of videodensitometric methods for blood flow measurements.

Micro-CT analyses of historical bone samples presenting with osteomyelitis

OBJECTIVE

Osteomyelitis is an inflammation of the bone marrow mainly caused by bacteria such as Staphylococcus aureus. It typically affects long bones, e.g. femora, tibiae and humeri. Recently micro-computed tomography (μCT) techniques offer the opportunity to investigate bone micro-architecture in great detail. Since there is no information on long bone microstructure in osteomyelitis, we studied historic bone samples with osteomyelitis by μCT.

MATERIALS AND METHODS

We investigated 23 femora of 22 individuals suffering from osteomyelitis provided by the Collection of Anatomical Pathology, Museum of Natural History, Vienna (average age 44 ±19 years); 9 femora from body donors made available by the Department of Applied Anatomy, Medical University of Vienna (age range, 56-102 years) were studied as controls. Bone microstructure was assessed by μCT VISCOM X 8060 II with a minimal resolution of 18 μm.

RESULTS

In the osteomyelitic femora, most prominent alterations were seen in the cortical compartment. In 71.4% of the individuals with osteomyelitis, cortical porosity occurred. 57.1% of the individuals showed cortical thinning. In 42.9% trabecularisation of cortical bone was observed.

CONCLUSION

Osteomyelitis is associated with severe alterations of cortical bone structure otherwise typically observed at old age such as cortical porosity and cortical thinning.

Is stress affecting our ability to tune into others? Evidence for gender differences in the effects of stress on self-other distinction

Stress is a ubiquitous challenge in society as we consistently interact with others under the influence of stress. Distinguishing self- from other-related mental representations plays an important role for social interactions, and is a prerequisite for crucial social skills such as action understanding, empathy, and mentalizing. Little is known, however, about the effects of stress on self-other distinction. We assessed how acute stress impacts self-other distinction in the perceptual-motor, the affective, and the cognitive domain, in a male and female sample. In all domains, the results show opposing effects of stress on the two genders: while women showed increases in self-other distinction, men showed decreases. Our findings suggest that women flexibly disambiguate self and other under stress, enabling accurate social responses, while men respond with increased egocentricity and less adaptive regulation. This has crucial implications for explaining gender differences in social skills such as empathy and prosociality.

Congenital lymphangiomatosis and an enteric duplication cyst in a young dog

A two-year-old female poodle with abdominal distention was diagnosed with concurrent enteric duplication cyst and lymphangiomatosis. Both lesions were shown as cystic structures, but some characteristic features of enteric duplication cyst were identified including a thick cyst wall and shared blood supply with the duodenum. Although it was challenging to discriminate between the types of cyst based on diagnostic imaging, this report describes the characteristics of each type of lesion using several different imaging modalities.

T-lymphocyte-rich thymoma and myasthenia gravis in a Siberian tiger (Panthera tigris altaica)

A 10-year-old captive male Siberian tiger (Panthera tigris altaica) presented with acute onset collapse, vomiting and dyspnoea, preceded by a 6-month period of progressive muscle wasting. Following humane destruction, post-mortem examination revealed a large multilobulated mass in the cranial mediastinum, which was diagnosed as a T-lymphocyte-rich thymoma with the aid of immunohistochemistry. Retrospective serology for acetylcholine receptor antibodies (titre 3.90 nmol/l) confirmed a diagnosis of thymoma-associated myasthenia gravis. Thymomas are reported rarely in wild carnivores, but when detected they appear to be similar in morphology to those seen in domestic carnivores and may also be accompanied by paraneoplastic syndromes. The clinical signs of myasthenia gravis in the tiger were consistent with those reported in cats and dogs and the condition is proposed as an important differential diagnosis for generalized weakness in captive Felidae.

The impact of social exclusion vs. inclusion on subjective and hormonal reactions in females and males

BACKGROUND

The experience of social exclusion represents an extremely aversive and threatening situation in daily life. The present study examined the impact of social exclusion compared to inclusion on steroid hormone concentrations as well as on subjective affect ratings.

METHODS

Eighty subjects (40 females) participated in two independent behavioral experiments. They engaged in a computerized ball tossing game in which they ostensibly played with two other players who deliberately excluded or included them, respectively. Hormone samples as well as mood ratings were taken before and after the game.

RESULTS

Social exclusion led to a decrease in positive mood ratings and increased anger ratings. In contrast, social inclusion did not affect positive mood ratings, but decreased sadness ratings. Both conditions did not affect cortisol levels. Testosterone significantly decreased after being excluded in both genders, and increased after inclusion, but only in males. Interestingly, progesterone showed an increase after both conditions only in females.

DISCUSSION

Our results suggest that social exclusion does not trigger a classical stress response but gender-specific changes in sex hormone levels. The testosterone decrease after being excluded in both genders, as well as the increase after inclusion in males can be interpreted within the framework of the biosocial status hypothesis. The progesterone increase might reflect a generalized affiliative response during social interaction in females.

Impact of negative affectively charged stimuli and response style on cognitive-control-related neural activation: an ERP study

The canonical AX-CPT task measures two forms of cognitive control: sustained goal-oriented control ("proactive" control) and transient changes in cognitive control following unexpected events ("reactive" control). We modified this task by adding negative and neutral International Affective Picture System (IAPS) pictures to assess the effects of negative emotion on these two forms of cognitive control. Proactive and reactive control styles were assessed based on measures of behavior and electrophysiology, including the N2 event-related potential component and source space activation (Low Resolution Tomography [LORETA]). We found slower reaction-times and greater DLPFC activation for negative relative to neutral stimuli. Additionally, we found that a proactive style of responding was related to less prefrontal activation (interpreted to reflect increased efficiency of processing) during actively maintained previously cued information and that a reactive style of responding was related to less prefrontal activation (interpreted to reflect increased efficiency of processing) during just-in-time environmentally triggered information. This pattern of results was evident in relatively neutral contexts, but in the face of negative emotion, these associations were not found, suggesting potential response style-by-emotion interaction effects on prefrontal neural activation.

Feelings of helplessness increase ERN amplitudes in healthy individuals

Experiencing feelings of helplessness has repeatedly been reported to contribute to depressive symptoms and negative affect. In turn, depression and negative affective states are associated, among others, with impairments in performance monitoring. Thus, the question arises whether performance monitoring is also affected by feelings of helplessness.

To this end, after the induction of feelings of helplessness via an unsolvable reasoning task, 37 participants (20 females) performed a modified version of a Flanker task. Based on a previously validated questionnaire, 17 participants were classified as helpless and 20 as not-helpless. Behavioral measures revealed no differences between helpless and not-helpless individuals. However, we observed enhanced Error-Related Negativity (ERN) amplitude differences between erroneous and correct responses in the helpless compared to the not-helpless group. Furthermore, correlational analysis revealed that higher scores of helplessness were associated with increased ERN difference scores. No influence of feelings of helplessness on later stages of performance monitoring was observed as indicated by Error-Positivity (Pe) amplitude.

The present study is the first to demonstrate that feelings of helplessness modulate the neuronal correlates of performance monitoring. Thus, even a short-lasting subjective state manipulation can lead to ERN amplitude variation, probably via modulation of mesencephalic dopamine activity.

Sleep and obesity in children: a clinical perspective

Childhood obesity is an international epidemic with many long-term health consequences. The many comorbid conditions associated with obesity underscore the need to explore the different etiologies of obesity which may lead to potential therapeutic interventions. There is growing evidence both that obesity affects sleep, and that sleep patterns and disorders may have an effect on weight. Both respiratory and non-respiratory sleep disorders are associated with obesity; those that have gotten the most attention are the relationships between obesity and obstructive sleep apnea syndrome and short sleep duration. Other forms of sleep-disordered breathing and narcolepsy have also been associated with childhood obesity. Due to the many comorbidities of obesity, this subset of the pediatric population has frequent health care visits across a variety of subspecialties. It is likely that a non-sleep physician will be the first to recognize a sleep-related problem. The aim of this review was to discuss sleep disorders that may be encountered by the general pediatrician and the pediatric subspecialists in their obese pediatric patients and to describe the evidence that links these disorders to obesity.

Co-registration of EEG and MRI data using matching of spline interpolated and MRI-segmented reconstructions of the scalp surface

Accurate co-registration of MRI and EEG data is indispensable for the correct interpretation of EEG maps or source localizations in relation to brain anatomy derived from MRI. In this study, a method for the co-registration of EEG and MRI data is presented. The method consists of an iterative matching of EEG-electrode based reconstructions of the scalp surface to scalp-segmented MRIs. EEG-electrode based surface reconstruction is achieved via spline interpolation of individually digitized 3D-electrode coordinates. In contrast to other approaches, neither fiducial determination nor any additional provisions (such as bite bars, other co-registration devices or head shape digitization) are required, and co-registration errors associated with inaccurate fiducial determination are avoided. The accuracy of the method was estimated by calculating the root-mean-square (RMS) deviation of spline interpolated and MRI-segmented surface reconstructions in 20 subjects. In addition, the distance between co-registered and genuine electrode coordinates was assessed via a simulation study, in which surface reconstruction was based on virtual electrodes determined on the scalp surface of a high-resolution MRI data set. The mean RMS deviation of surface reconstructions was 2.43 mm, and the maximal distance between any two matched surface points was 5.06 mm. The simulated co-registration revealed a mean deviation of genuine and co-registered electrode coordinates of 0.61 mm. It is concluded that surface matching using spline interpolated reconstructions of scalp surfaces is a precise and highly practicable method to co-register EEG and MRI data.

Evidence for premotor cortex activity during dynamic visuospatial imagery from single-trial functional magnetic resonance imaging and event-related slow cortical potentials

A strong correspondence has been repeatedly observed between actually performed and mentally imagined object rotation. This suggests an overlap in the brain regions involved in these processes. Functional neuroimaging studies have consistently revealed parietal and occipital cortex activity during dynamic visuospatial imagery. However, results concerning the involvement of higher-order cortical motor areas have been less consistent. We investigated if and when premotor structures are active during processing of a three-dimensional cube comparison task that requires dynamic visuospatial imagery. In order to achieve a good temporal and spatial resolution, single-trial functional magnetic resonance imaging (fMRI) and scalp-recorded event-related slow cortical potentials (SCPs) were recorded from the same subjects in two separate measurement sessions. In order to reduce inter-subject variability in brain activity due to individual differences, only male subjects (n = 13) with high task-specific ability were investigated. Functional MRI revealed consistent bilateral activity in the occipital (Brodmann area BA18/19) and parietal cortex (BA7), in lateral and medial premotor areas (BA6), the dorsolateral prefrontal cortex (BA9), and the anterior insular cortex. The time-course of SCPs indicated that task-related activity in these areas commenced approximately 550-650 ms after stimulus presentation and persisted until task completion. These results provide strong and consistent evidence that the human premotor cortex is involved in dynamic visuospatial imagery.

Direct current auditory evoked potentials during wakefulness, anesthesia, and emergence from anesthesia

Direct current auditory evoked potentials (DC-AEPs) are a sensitive indicator of depth of anesthesia in animals. However, they have never been investigated in humans. To assess the potential usefulness of DC-AEPs as an indicator of anesthesia in humans, we performed an explorative study in which DC-AEPs were recorded during propofol and methohexital anesthesia in humans. DC-AEPs were recorded via 22 scalp electrodes in 19 volunteers randomly assigned to receive either propofol or methohexital. DC-AEPs were evoked by binaurally presented 2-s, 60-dB, 800-Hz tones; measurements were taken during awake baseline, anesthesia, and emergence. Statistical analysis included analysis of variance and discriminant analysis of data acquired during these three conditions. About 500 ms after stimulus presentation, DC-AEPs could be observed. These potentials were present only during baseline and emergence-not during anesthesia. Statistically significant differences were found between baseline and anesthesia and between anesthesia and emergence. In conclusion, similar effects, as reported in animal studies of anesthetics on the DC-AEPs, could be observed in anesthetized humans. These results demonstrate that DC-AEPs are potentially useful in the assessment of cortical function during anesthesia and might qualify the method for monitoring anesthesia in humans.

Restriction of task processing time affects cortical activity during processing of a cognitive task: an event-related slow cortical potential study

As is known from psychometrics, restriction of task processing time by the instruction to respond as quickly and accurately as possible leads to task-unspecific cognitive processing. Since this task processing mode is used in most functional neuroimaging studies of human cognition, this may evoke cortical activity that is functionally not essential for the particular task under investigation. Using topographic recordings of event-related slow cortical potentials, two experiments have been performed to investigate whether cortical activity during processing of a visuo-spatial imagery task is substantially influenced by the time provided to process the task. Furthermore, it was investigated whether this effect is additionally modulated by a subject's task-specific ability. The instruction to respond as quickly and accurately as possible led to increased negative slow cortical potential amplitudes over parietal and frontal regions and significantly interacted with task-specific ability. While cortical activity recorded over parietal and frontal regions was different between subjects with low and high spatial ability when processing time was unrestricted, no such differences were found between ability groups when subjects were instructed to answer both quickly and accurately. These results suggest that restricting processing time has considerable effects on the amount and the pattern of brain activity during cognitive processing and should be taken into account more explicitly in the experimental design and interpretation of neuroimaging studies of cognition.

Excessive daytime sleepiness in patients suffering from different levels of obstructive sleep apnoea syndrome

Excessive daytime sleepiness (EDS) is a frequent symptom of patients with obstructive sleep apnoea (OSA). EDS is a high-risk factor for accidents at work and on the road. Thirty untreated patients with different levels of severity of OSA were studied concerning night sleep and EDS. The criterion for severity was the respiratory disturbance index (RDI): 15 patients were classified as 'moderately' apnoeic (RDI < 40), 15 as 'severely' apnoeic (RDI > 40). Following night-time polysomnography, objective and subjective aspects of EDS were studied. To assess objective EDS the Maintenance of Wakefulness Test (MWT) and a computer-based vigilance performance test were used. Subjective EDS was determined using the Stanford Sleepiness Scale (SSS), the Epworth Sleepiness Scale (ESS) and the Visual Analogue Scales for Performance (VAS-P) and Tiredness (VAS-T). Well-being was assessed using the Scale of Well-Being by von Zerssen (Bf-S/Bf-S'). Severe apnoea patients spent more time in stage 1 and less in slow-wave sleep. MWT latencies tended to be shorter in the severe apnoea group. Vigilance testing revealed no group differences. Patients with moderate apnoea described themselves as more impaired in all subjective scales, but only SSS scores reached statistical significance. Our results suggest that there is no simple correlation between polysomnographic and respiratory sleep variables at night on the one hand, and the extent of EDS on the other hand. Furthermore, subjective and objective evaluation of EDS does not yield the same results. New approaches which allow a more detailed analysis of night sleep and daytime function are required to identify high-risked patients.

Graft coronary artery disease is strongly related to the aetiology of heart failure and cellular rejections

AIMS

To identify risk factors for the development of coronary artery disease after heart transplantation.

METHODS AND RESULTS

In consecutive heart transplanted patients, who underwent coronary angiography at the first year follow-up, the aetiology of heart failure in 113 was ischaemic heart disease or dilated cardiomyopathy. Development of clinically significant graft coronary artery disease was analysed vs recipient and donor pre- and post-transplantation variables. At 1, 5 and 9 years follow-up, coronary artery disease had developed in 4%, 16%, and 20% of the included patients, respectively. Among patients with ischaemic heart disease as the aetiology of heart failure, 38% developed graft coronary artery disease, while the corresponding figure for patients with dilated cardiomyopathy was 9% (P<0.001) during 9 years of follow-up. In multivariate regression analysis, the aetiology of ischaemic heart disease and the number of cellular rejections were independent predictors of developing graft coronary artery disease, with risk ratios of 5.8, (95% confidence interval of 2.2-14.8 (P=0.0003)) and 3.3, (95% confidence interval of 1.7-6.5 (P=0.0004)), respectively. Classical risk factors for coronary artery disease did not influence the development of graft coronary artery disease.

CONCLUSIONS

Ischaemic heart disease as the aetiology of heart failure and the number of cellular rejections were powerful independent predictors of development of graft coronary artery disease following heart transplantation. The low incidence of graft coronary artery disease among patients with dilated cardiomyopathy implies that coronary angiography after heart transplantation can be made on a more selective basis.

Differences in the ability to process a visuo-spatial task are reflected in event-related slow cortical potentials of human subjects

Recent positron emission tomography (PET) and electroencephalographic (EEG) studies suggest that higher ability in a cognitive task is associated with a more efficient neuronal processing of this task. However, the validity and generalizability of these studies is limited for several reasons. We investigated 20 male and 18 female human subjects with good vs. poor spatial ability performing a visuo-spatial task (cube test). Processing-related slow event-related potentials were recorded via 22 electrodes, evenly distributed over the scalp. Significant differences between good and poor performers were found in both sexes: poor subjects showed higher activity in the parietal region, and their topography was more extended into fronto-central regions. Since the amount and topography of brain activity may vary considerably depending on subjects' ability, we conclude that careful (experimental) control of task-specific ability of subjects is mandatory for cognitive neuroscience studies.

Evaluation of home audiotapes as an abbreviated test for obstructive sleep apnea syndrome (OSAS) in children

Snoring occurs commonly in children and is sometimes associated with obstructive sleep apnea syndrome (OSAS). Based on clinical history alone, it is difficult to distinguish primary snoring, characterized by noisy breathing during sleep without apnea or hypoventilation, from snoring indicative of OSAS. An overnight polysomnogram (PSG) is required to establish a definitive diagnosis of OSAS. Because sleep evaluations are costly and resources are limited, we evaluated whether a home audiotape recording could accurately identify children with OSAS. We studied 36 children referred by pediatricians and otolaryngologists for possible OSAS. Parents completed a questionnaire about their child's sleep and breathing and made a 15-min audiotape of the child's breath sounds during sleep. Overnight PSGs were performed on all patients. There were 29 patients who completed the study: 15 patients in the Primary Snoring group (apnea/hypopnea index < 5) and 14 patients in the OSAS group (apnea/hypopnea index > or = 5). No significant statistical differences existed between the two groups for physical characteristics or questionnaire responses. Seven observers analyzed the audiotapes for the presence of a struggle sound and respiratory pauses. The median sensitivity of the audiotape as a predictor of OSAS was 71% (range 43-86%), and the median specificity was 80% (range 67-80%). The presence of a struggle sound on the audiotape was the parameter most predictive of OSAS. There was a good level of agreement among the seven audiotape observers, as demonstrated by a mean and range kappa statistic of 0.70 (0.50-0.93) for the 21 pairs of observers. Using a clinical score to predict OSAS, the sensitivity was 46%, and the specificity was 83%. We conclude that findings on a home audiotape can be suggestive of OSAS, but are not sufficiently specific to reliably distinguish primary snoring from OSAS.

Sex differences in oral asymmetries during wordrepetition

During speech production the right side of the mouth is opened to a larger degree in most people. This facial asymmetry is thought to be related to a left hemisphere dominance in language processing and/or motor programming. We investigated asymmetrical lip separations during discrete or serial word productions in right handed persons. The results revealed a right sided lip separation bias in both genders during discrete word production in which the words had to be uttered once. As soon as the words had to be produced continuously, however, a clear sex difference appeared with males having the usual right bias but females now showing no clear asymmetry, with a tendency for larger lip separations on the left side. These results suggest the existence of two separate neural systems from which one controls the discrete task and which is left hemisphere dominant in both genders. The other is probably involved in serial word productions and shows a sex difference with regard to its asymmetry pattern.

Coronary aneurysms in patients with autosomal dominant polycystic kidney disease

Patients with autosomal dominant polycystic kidney disease (ADPKD) have an increased risk of intracranial aneurysms. Reports on arterial aneurysms in other locations have not been conclusive. The present study was initiated to investigate the prevalence of coronary aneurysms. Thirty ADPKD patients who had undergone coronary angiography on clinical indication were identified, 15 after renal transplantation. For each ADPKD patient, a control patient was identified with end-stage renal disease, investigated by coronary angiography, and matched for age, sex, and time relation to transplantation. All angiograms were retrieved and reevaluated with respect to aneurysms, defined as an increase in artery diameter by 50% or more, as well as to pathologic ectasias not fulfilling this criterion. Aneurysms were detected in four ADPKD patients and two control subjects. Five more ADPKD patients, but none of the control subjects, had minor ectasias. One ADPKD patient had a dissecting aortic aneurysm, and another died of aortic dissection during bypass surgery. This study adds to the evidence of an increased risk of extracranial aneurysms in ADPKD patients.

Polysomnographic findings in a patient with the mitochondrial encephalomyopathy NARP

A 23-year-old woman with the mitochondrial encephalomyopathy NARP (neurogenic muscle weakness, ataxia, and retinitis pigmentosa) presented with symptoms of obstructive sleep apnea (OSA). An overnight polysomnogram (PSG) showed apnea, EEG slowing, and a paucity of sleep spindles. The patient had a tracheostomy for OSA, and 5 months later she had normal EEG patterns and marked clinical improvement. We propose that patients with mitochondrial encephalomyopathies should have sleep evaluations if the history suggests OSA.

Prediction of left ventricular dysfunction in coronary artery disease from clinical and exercise test findings

We studied the ability to predict depressed left ventricular ejection fraction (LVEF) from clinical and exercise test findings prior to surgery in consecutive patients who underwent coronary artery bypass grafting (CABG) from 1988 to 1991 (n = 663). Multivariate analysis showed a history of myocardial infarction, pathological Q-wave in resting ECG, systolic blood pressure at maximal exercise and the degree of mitral regurgitation as significant independent predictors of impaired LVEF. The relative risk (RR) of depressed LVEF was markedly increased for a previous history of myocardial infarction (RR 3.3, p < 0.0001) and a pathological Q-wave in resting ECG (RR 2.4, p < 0.0001). All associations found between depressed LVEF and exercise test results were poor, and of little value for discriminating patients with depressed LVEF. Thus, clinical data appear to be better markers of low LVEF than the information obtained from the exercise test.

Morbidity and use of medical resources in patients with chest pain and normal or near-normal coronary arteries

To evaluate morbidity and use of medical resources in patients with chest pain and normal or near-normal coronary angiograms: 2,639 consecutive patients who underwent coronary angiograms due to chest pain were registered. Two years thereafter all patients who showed normal or near-normal coronary angiograms were approached with a questionnaire regarding hospitalization during the last 4 years (2 years before and 2 years after angiography). All medical files were also examined. Of the patients who underwent angiography, 163 (6%) had no significant stenoses, and of these, 113 showed complete normal angiograms and 50 showed mild (i.e. <50%) stenoses. During the 2 years before diagnostic angiogram, 66% of the patients were hospitalized compared with only 35% during 2 years after angiography (p <0.001). The reduction in hospitalization was due to curtailed utilization of medical resources for cardiac reasons; mean days in hospital was 6.6 days before angiography versus 2.8 days after (p <0.001). There were no significant differences in hospitalization when comparing patients with mild stenoses and completely normal angiograms. There were, furthermore, no differences between patients with positive or negative exercise tests. Thus, the need for hospitalization is significantly reduced after a diagnostic angiogram reveals normal or near-normal coronary arteries.

Magnetic resonance imaging in the follow-up of patients after aortic root reconstruction

Long-term survival after replacement of the aortic root with a composite graft is improving. Late deaths are in several cases due to complications related to the previous surgery or to pathologies of the remaining aorta. Regular follow-up of these patients is of paramount importance. The purpose of this study is to evaluate the reliability of magnetic resonance imaging (MRI) in such cases. Twenty-seven patients (9 dissections and 18 aneurysms) who had undergone replacement of the aortic root with a composite graft were studied 20 to 167 months after surgery using magnetic resonance imaging with a 1.5 Tesla magnet. The left-ventricular outflow tract, the mechanical valve function, the proximal part of the coronary arteries, the graft, and the remaining aorta could be examined. No aortic insufficiency, ectasy of the proximal part of the coronaries, or pseudoaneurysms were seen. A widening of the remaining ascending aorta was noted in 4 cases. A still open, dissected pipe was visualized in 7 patients. Our conclusions are that MRI provides excellent images of the thoracic and abdominal aorta following surgical repair. The examination is becoming cost-competitive. More import is its very low risk for the patient group considered here: since it is non-invasive and requires no contrast medium or X-ray exposure, examinations can be repeated as required.

Assessment of coronary artery stenosis during PTCA by measurement of the trans-stenotic pressure gradient. Comparison with quantitative coronary angiography

A fibreoptic pressure sensor mounted on an 0.018 inch guidewire (Pressure Guide, RadiMedical Systems, Uppsala, Sweden) was used to measure the trans-stenotic pressure gradient in 20 patients admitted for percutaneous transluminal coronary angioplasty (PTCA) of a single, discrete stenosis. Pressure measurements were made both at rest and during maximal vasodilatation induced by intracoronary injection of papaverine. From the ratio of distal coronary pressure divided by the proximal pressure, the relative coronary flow reserve was calculated. The aim of the study was to compare the different pressure-derived parameters by correlating them to stenosis geometry estimated by quantitative coronary angiography. There was a moderate correlation between baseline pressure gradient and percent area stenosis; r = 0.64, P < 0.001 and minimal cross-sectional area; r = 0.45, P < 0.005. A higher correlation was found between hyperaemic pressure gradient and area stenosis (r = 0.80, P < 0.001) and minimal cross-sectional areas, respectively (r = 0.55, P < 0.005). The best correlation was found between relative coronary flow reserve and area stenosis (r = 0.86, P < 0.001) and minimal cross-sectional area (r = 0.70, P < 0.001). In conclusion, pressure measurement using a pressure guidewire is useful as a complement to angiography in evaluation of coronary stenoses during PTCA. Pressures should be measured during maximal vasodilatation. Relative coronary flow reserve calculated from the pressure measurements provides additional information about the fraction of normal maximal flow possible in the presence of a stenosis.