When 2 become 1: Autistic simultaneity judgements about asynchronous audiovisual speech

It has been proposed that autistic people experience a temporal distortion whereby the temporal binding window of multisensory integration is extended. Research to date has focused on autistic children so whether these differences persist into adulthood remains unknown. In addition, the possibility that the previous observations have arisen from between-group differences in response bias, rather than perceptual differences, has not been addressed. Participants completed simultaneity judgements of audiovisual speech stimuli across a range of stimulus-onset asynchronies. Response times and accuracy data were fitted to a drift-diffusion model so that the drift rate (a measure of processing efficiency) and starting point (response bias) could be estimated. In Experiment 1, we tested a sample of non-autistic adults who completed the Autism Quotient questionnaire. Autism Quotient score was not correlated with either drift rate or response bias, nor were there between-group differences when splitting based on the first and third quantiles of scores. In Experiment 2, we compared the performance of autistic with a group of non-autistic adults. There were no between-group differences in either drift rate or starting point. The results of this study do not support the previous suggestion that autistic people have an extended temporal binding window for audiovisual speech. In addition, exploratory analysis revealed that operationalising the temporal binding window in different ways influenced whether a group difference was observed, which is an important consideration for future work.

Retroperitoneoscopic adrenalectomy - introducing a new surgical technique in South Africa

BACKGROUND

Posterior retroperitoneoscopic adrenalectomy (PRA) is purported to be superior to the laparoscopic transperitoneal approach (LA) in patients with a select spectrum of benign adrenal pathologies. Advantages attributed to the technique include minimal blood loss, shortened operative times, and decreased postoperative pain, explained anatomically by the direct access to the adrenal gland. Reduced workspace is a limitation.

METHODS

A retrospective review of 22 consecutive PRAs performed in a single centre between 1 September 2016 and 30 October 2020 is presented. Two experienced laparoscopic surgeons operated on all patients after acquiring the technique at international centres. Suitable candidates were carefully pre-selected. Non-benign pathology, high vascularity, body mass index (BMI) ≥ 45 kg/m2 and anatomical concerns on prior computed tomography (CT) imaging were exclusion criteria.

RESULTS

Twenty-two PRAs were performed for a spectrum of benign adrenal pathologies. Twenty-one surgeries (95%) were completed. A single case of pheochromocytoma required conversion. The procedure was safe, a minor postoperative complication (pneumaturia) occurred in one case, and the mortality rate was 0%. Median operative time (80 minutes) is comparable to other reported series in the literature, with a modest linear descending tendency noted over the study period. Underlying pathology influenced operative times. Pheochromocytomas proved to be most challenging and required careful preoperative evaluation.

CONCLUSION

The PRA procedures performed at Tygerberg Academic Hospital were safe and reproducible in a select group of cases with benign adrenal pathology. Endocrine surgeons proficient with laparoscopic techniques should be encouraged to use the PRA approach when encountering adrenal neoplasms that fit the criteria.

Intact memory storage but impaired retrieval in visual memory in autism: New insights from an electrophysiological study

In a recent study on visual episodic memory (Desaunay, Clochon, et al., 2020), we have shown event-related potentials (ERPs) differences associated with priming (150-300 msec), familiarity (350-470 msec), and recollection (600-700 msec), in young people with autism spectrum disorders (ASD) compared with typical development (TD). To go further into the study of the processes of storage and retrieval of the memory trace, we re-analyzed Desaunay, Clochon, et al's data using time-frequency analysis, that is, event-related synchronization and desynchronization (ERS/ERD). This allows a decomposition of the spectral power within frequency bands associated with these ERPs. We focused both on the same time windows and the same regions of interest as previously published. We mainly identified, in ASD compared with TD, reduced ERS in low-frequencies (delta, theta) in early time-windows, and non-significant differences in ERD in higher frequencies (alpha, beta1) in all time-windows. Reduced ERS during recognition confirmed previously reported diminution of priming effects and difficulties in manipulation and retrieval of both semantic and episodic information. Conversely, preserved ERD corroborates a preservation of memory storage processes. These observations are consistent with a cognitive model of memory in ASD, that suggests difficulties in cognitive operations or executive demand at retrieval, subsequent to successful long-term storage of information. LAY SUMMARY: We assessed the EEG synchronization and desynchronization, during visual episodic recognition. We observed, in youth with Autism, reduced synchronization in low-frequencies (delta, theta), suggesting reduced access to and manipulation of long-term stored information. By contrast, non-significant differences in desynchronization at higher frequencies (alpha, beta frequency bands), that support long-term stored semantic and episodic information, suggested preserved memory traces.

Duodenojejunal intussusception due to an inflammatory fibroid polyp: a mimic of acute pancreatitis

This report describes an extremely unusual cause of acute pancreatitis. It highlights the value of cross-sectional imaging, in the absence of alcohol and gallstone aetiology, to establish a diagnosis and direct management. Computed tomography (CT) revealed a duodenal jejunal intussusception. A benign inflammatory fibroid tumour, acting as a lead point, was surgically resected and the patient made an unremarkable recovery without further episodes of acute pancreatitis.

Reward Devaluation in Autistic Children and Adolescents with Complex Needs: A Feasibility Study

Rewards act as a motivator for positive behavior and learning. Although compounding evidence indicates that reward processing operates differently in autistic individuals who do not have co-occurring learning disabilities, little is known about individuals who have such difficulties or other complex needs. This study aimed first to assess the feasibility of using an adapted reward devaluation paradigm to examine basic reward processes in this underrepresented population, and second to investigate whether autistic children and adolescents with complex needs would show dynamic behavioral changes in response to changes in the motivational value of a reward. Twenty-seven autistic children and adolescents with complex needs and 20 typically developing 5-year-old children took part in the study. Participants were presented with two visual cues on a touchscreen laptop, which triggered the delivery of a video, music, or physical reward. One of the rewards was then presented in abundance to decrease its motivational value. Participants showed decreased interest in the video and music rewards after devaluation. The experimental setup was found to be suitable to test individuals with complex needs, although recommendations are made for the use of physical rewards. The results suggest that autistic participants with complex needs demonstrate goal-directed behavior and that it is feasible to develop experimental paradigms that can shed important light on learning processes that are fundamental to many education and intervention strategies for this population. Autism Res 2020, 13: 1915-1928. © 2020 The Authors. Autism Research published by International Society for Autism Research and Wiley Periodicals LLC. LAY SUMMARY: We adapted an experimental task to conduct research with autistic children and adolescents with complex needs, who remain grossly underrepresented in autism research. We found that once a reward was presented in great quantity, participants were less motivated to obtain it, showing that they adapted their behavior to changes in the value of that reward. This is an important finding to help promote learning and design better interventions for this population.

The Witness-Aimed First Account (WAFA): A new technique for interviewing autistic witnesses and victims

LAY ABSTRACT

Autistic people may be more likely to be interviewed by police as a victim/witness, yet they experience social communication difficulties alongside specific memory difficulties that can impact their ability to recall information from memory. Police interviewing techniques do not take account of these differences, and so are often ineffective. We developed a new technique for interviewing autistic witnesses, referred to a Witness-Aimed First Account, which was designed to better support differences in the way that autistic witnesses process information in memory. The Witness-Aimed First Account technique encourages witnesses to first segment the witnessed event into discrete, parameter-bound event topics, which are then displayed on post-it notes while the witness goes onto freely recall as much information as they can from within each parameter-bound topic in turn. Since witnessed events are rarely cohesive stories with a logical chain of events, we also explored autistic and non-autistic witnesses' recall when the events were witnessed in a random (nonsensical) order. Thirty-three autistic and 30 typically developing participants were interviewed about their memory for two videos depicting criminal events. Clip segments of one video were 'scrambled', disrupting the event's narrative structure; the other video was watched intact. Although both autistic and non-autistic witnesses recalled fewer details with less accuracy from the scrambled video, Witness-Aimed First Account interviews resulted in more detailed and accurate recall from both autistic and non-autistic witnesses, for both scrambled and unscrambled videos. The Witness-Aimed First Account technique may be a useful tool to improve witnesses' accounts within a legally appropriate, non-leading framework.

Metabolic surgery in South Africa: an initial academic hospital experience

BACKGROUND

In South Africa, 42.0% of adult females and 13.5% of adult males are classified as obese, the highest recorded numbers in Sub-Saharan Africa. Metabolic surgery has been proven to be a safe and effective treatment, yet due to demand on government resources has only been performed to a limited extent in public hospitals. The aim of this study was to describe the safety and efficacy of performing metabolic surgery at a single academic hospital in South Africa.

METHOD

This was a single centre retrospective review of 57 metabolic surgery procedures performed from October 2011 to September 2017 at Tygerberg Hospital, Cape Town, South Africa. The primary outcome was safety including mortality and adverse events. Secondary outcomes included effect of surgery on weight and diabetes resolution.

RESULTS

A total of 57 patients underwent laparoscopic metabolic surgery, of which 44 (83.0%) were female with a mean age (standard deviation) of 42.8 (8.0) years. Fifty-six patients (98%) underwent Roux-and-Y gastric bypass and one (2%) had a sleeve gastrectomy performed. There were no mortalities and overall morbidity was 14.0%, with 3 (5.3%) classified as major and 5 (8.8%) as minor. The follow-up rate at 1 year was 100%. Mean preoperative body mass index (BMI) was 58.8 kg/m2, and comorbidities included hypertension (59.6%), Type 2 Diabetes (42.1%), and dyslipidaemia (36.8%). There were no conversions to open surgery and at one year the mean (95% confidence interval) percentage excess body mass index loss was 50.4% (44.0-56.8%).

CONCLUSION

Metabolic surgery can be performed safely in the public sector in South Africa, with short-term safety and efficacy outcomes comparable to international reports. Larger scale studies are needed to determine long-term outcomes and cost-effectiveness.

The Warburg Dance Movement Library-The WADAMO Library: A Validation Study

The Warburg Dance Movement Library is a validated set of 234 video clips of dance movements for empirical research in the fields of cognitive science and neuroscience of action perception, affect perception and neuroaesthetics. The library contains two categories of video clips of dance movement sequences. Of each pair, one version of the movement sequence is emotionally expressive (Clip a), while the other version of the same sequence (Clip b) is not expressive but as technically correct as the expressive version (Clip a). We sought to complement previous dance video stimuli libraries. Facial information, colour and music have been removed, and each clip has been faded in and out. We equalised stimulus length (6 seconds, 8 counts in dance theory), the dancers' clothing and video background and included both male and female dancers, and we controlled for technical correctness of movement execution. The Warburg Dance Movement Library contains both contemporary and ballet movements. Two online surveys ( N = 160) confirmed the classification into the two categories of expressivity. Four additional online surveys ( N = 80) provided beauty and liking ratings for each clip. A correlation matrix illustrates all variables of this norming study (technical correctness, expressivity, beauty, liking, luminance, motion energy).

Using Time Perception to Explore Implicit Sensitivity to Emotional Stimuli in Autism Spectrum Disorder

Establishing whether implicit responses to emotional cues are intact in autism spectrum disorder (ASD) is fundamental to ascertaining why their emotional understanding is compromised. We used a temporal bisection task to assess for responsiveness to face and wildlife images that varied in emotional salience. There were no significant differences between an adult ASD and comparison group, with both showing implicit overestimation of emotional stimuli. Further, there was no correlation between overestimation of emotional stimuli and autistic traits in undergraduate students. These data do not suggest a fundamental insensitivity to the arousing content of emotional images in ASD, or in individuals with a high degree of autistic traits. The findings have implications for understanding how emotional stimuli are processed in ASD.

Diminished neural resources allocation to time processing in Autism Spectrum Disorders

Background

Interval timing, the ability to judge the duration of short events, has been shown to be compromised in Autism Spectrum Disorders (ASD). Timing abilities are ubiquitous and underlie behaviours as varied as sensory integration, motor coordination or communication. It has been suggested that atypical temporal processing in ASD could contribute to some of the disorder's symptoms, in particular motor clumsiness and difficulties in social interaction and communication. Recent behavioural investigations have suggested that interval timing in ASD is characterised by intact sensitivity but reduced precision in duration judgements.

Methods

In this study we investigated the processing of duration as compared to pitch in a group of high-functioning individuals with ASD using magnetoencephalography (MEG). 18 adolescents and adults with ASD and 18 age- and IQ-matched typically-developing control (TDC) individuals compared two consecutive tones according to their duration or pitch in separate experimental blocks. The analysis was carried out exclusively on physically identical stimuli (500 Hz tones lasting 600 ms), which served, according to instruction, as standard or probe in a Duration or Pitch task respectively.

Results

Our results suggest that compared to TDC individuals, individuals with ASD are less able to predict the duration of the standard tone accurately, affecting the sensitivity of the comparison process. In addition, contrary to TDC individuals who allocate resources at different times depending on the nature of the task (pitch or duration discrimination), individuals with ASD seem to engage less resources for the Duration task than for the Pitch task regardless of the context. Although individuals with ASD showed top-down adaptation to the context of the task, this neuronal strategy reflects a bias in the readiness to perform different types of tasks, and in particular a diminished allocation of resources to duration processing which could have cascading effect on learning and development of other cognitive functions.

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We investigated MEG response associated with duration or pitch comparison in ASD.

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We found lower sensitivity for duration discrimination behaviourally in ASD.

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ASD adults are less able to predict the offset of a standard tone.

•

ASD adults engage less neural resources in duration than pitch discrimination task.

Impact of Semantic Relatedness on Associative Memory: An ERP Study

Encoding and retrieval processes in memory for pairs of pictures are thought to be influenced by inter-item similarity and by features of individual items. Using Event-Related Potentials (ERP), we aimed to identify how these processes impact on both the early mid-frontal FN400 and the Late Positive Component (LPC) potentials during associative retrieval of pictures. Twenty young adults undertook a sham task, using an incidental encoding of semantically related and unrelated pairs of drawings. At test, we conducted a recognition task in which participants were asked to identify target identical pairs of pictures, which could be semantically related or unrelated, among new and rearranged pairs. We observed semantic (related and unrelated pairs) and condition effects (old, rearranged and new pairs) on the early mid-frontal potential. First, a lower amplitude was shown for identical and rearranged semantically related pairs, which might reflect a retrieval process driven by semantic cues. Second, among semantically unrelated pairs, we found a larger negativity for identical pairs, compared to rearranged and new ones, suggesting additional retrieval processing that focuses on associative information. We also observed an LPC old/new effect with a mid-parietal and a right occipito-parietal topography for semantically related and unrelated old pairs, demonstrating a recollection phenomenon irrespective of the degree of association. These findings suggest that associative recognition using visual stimuli begins at early stages of retrieval, and differs according to the degree of semantic relatedness among items. However, either strategy may ultimately lead to recollection processes.

Affective responses to dance

The objective of the present work was the characterization of mechanisms by which affective experiences are elicited in observers when watching dance movements. A total of 203 dance stimuli from a normed stimuli library were used in a series of independent experiments. The following measures were obtained: (i) subjective measures of 97 dance-naïve participants' affective responses (Likert scale ratings, interviews); and (ii) objective measures of the physical parameters of the stimuli (motion energy, luminance), and of the movements represented in the stimuli (roundedness, impressiveness). Results showed that (i) participants' ratings of felt and perceived affect differed, (ii) felt and perceived valence but not arousal ratings correlated with physical parameters of the stimuli (motion energy and luminance), (iii) roundedness in posture shape was related to the experience of more positive emotion than edgy shapes (1 of 3 assessed rounded shapes showed a clear effect on positiveness ratings while a second reached trend level significance), (iv) more impressive movements resulted in more positive affective responses, (v) dance triggered affective experiences through the imagery and autobiographical memories it elicited in some people, and (vi) the physical parameters of the video stimuli correlated only weakly and negatively with the aesthetics ratings of beauty, liking and interest. The novelty of the present approach was twofold; (i) the assessment of multiple affect-inducing mechanisms, and (ii) the use of one single normed stimulus set. The results from this approach lend support to both previous and present findings. Results are discussed with regards to current literature in the field of empirical aesthetics and affective neuroscience.

Humans don't time subsecond intervals like a stopwatch

Many activities require the ability to estimate intervals of time in an accurate and flexible manner. A traditional and popular account suggests that humans possess a kind of internal stopwatch that can be started, paused, and stopped at will. Here we test this idea by measuring variable performance errors in 3 experiments. Participants had to compare the total time accumulated during 1 to 3 short target intervals with a single standard interval. With 2 or more target intervals, participants had to pause, but not reset, their putative internal stopwatches. By establishing baseline performance at 2 different standard durations and extrapolating based on Weber's law, we were able to estimate how much performance should have deteriorated when target segments contained breaks. The decrement in performance we observed far exceeded the stopwatch prediction, and also exceeded the simulated predictions of a modified stopwatch with a slowing pacemaker. The data thus favor either a counter that cannot be paused during subsecond durations or alternative models of subsecond interval duration discrimination that do not posit a count-based metric for time. We discuss several possible strategies that participants might have implemented to apply such clocks in the split-interval task.

Apport de la technique d’Eye-tracking dans la compréhension de l’impact des particularités perceptives sur la cognition dans les Troubles du Spectre Autistique (TSA)

La technique d’Eye-tracking (ET), basée sur la détection du reflet cornéen généré par une lumière infrarouge, permet l’enregistrement en temps réel des mouvements oculaires d’un individu explorant une image ou son environnement. Cette technique révélant le sens du regard en une succession de saccades et de fixations a permis d’apporter un nouvel éclairage sur la manière dont un individu explore le monde environnant et de mettre en lumière les particularités perceptives dans différentes pathologies, dont les troubles du spectre autistique. Les sujets avec trouble du spectre autistique présentent des atypies perceptives se traduisant notamment par un biais de traitement en faveur de la dimension locale (détails). La majorité des travaux en ET se sont intéressés à la cognition sociale. Certains ont notamment révélé que les stratégies d’exploration des visages au sein d’une scène sociale en milieu naturel étaient différentes chez les sujets TSA et pourraient contribuer aux troubles de cognition sociale et de reconnaissance émotionnelle [1]. Toutefois, cette technique trouve également son intérêt dans l’étude d’autres domaines cognitifs tels que les capacités de catégorisation [2] ou la mémoire. Les personnes avec TSA ont un fonctionnement mnésique atypique [3], résultant notamment de difficultés de sélection et d’intégration d’informations perceptives complexes. Ces difficultés ont été identifiées dès les premières millisecondes d’exploration de l’information à mémoriser [4]. Nous proposons d’illustrer l’apport de cette approche pour la caractérisation des atypies perceptives des personnes avec TSA et leurs répercussions sur le fonctionnement cognitif. Nous aborderons également les perspectives nouvelles d’évaluation neuropsychologique et de remédiation qu’offre cette technique d’ET au clinicien.

Recall of a live and personally experienced eyewitness event by adults with autism spectrum disorder

The aim of the present study was to (a) extend previous eyewitness research in autism spectrum disorder (ASD) using a live and personally experienced event; (b) examine whether witnesses with ASD demonstrate a facilitative effect in memory for self- over other-performed actions; (c) explore source monitoring abilities by witnesses with ASD in discriminating who performed which actions within the event. Eighteen high-functioning adults with ASD and 18 age- and IQ-matched typical counterparts participated in a live first aid scenario in which they and the experimenter each performed a number of actions. Participants were subsequently interviewed for their memory of the event using a standard interview procedure with free recall followed by questioning. The ASD group recalled just as many correct details as the comparison group from the event overall, however they made more errors. This was the case across both free recall and questioning phases. Both groups showed a self-enactment effect across both interview phases, recalling more actions that they had performed themselves than actions that the experimenter had performed. However, the ASD group were more likely than their typical comparisons to confuse the source of self-performed actions in free recall, but not in questioning, which may indicate executive functioning difficulties with unsupported test procedures. Findings are discussed in terms of their theoretical and practical implications.

Age does not count: resilience of quantity processing in healthy ageing

Quantity skills have been extensively studied in terms of their development and pathological decline. Recently, numerosity discrimination (i.e., how many items are in a set) has been shown to be resilient to healthy ageing despite relying on inhibitory skills, but whether processing continuous quantities such as time and space is equally well-maintained in ageing participants is not known. Life-long exposure to quantity-related problems may progressively refine proficiency in quantity tasks, or alternatively quantity skills may decline with age. In addition, is not known whether the tight relationship between quantity dimensions typically shown in their interactions is preserved in ageing. To address these questions, two experimental paradigms were used in 38 younger and 32 older healthy adults who showed typical age-related decline in attention, executive function and memory tasks. In both groups we first assessed time and space discrimination independently using a two-choice task (i.e., "Which of two horizontal lines is longer in duration or extension?"), and found that time and space processing were equally accurate in younger and older participants. In a second paradigm, we assessed the relation between different quantity dimensions which were presented as a dynamic pattern of dots independently changing in duration, spatial extension and numerosity. Younger and older participants again showed a similar profile of interaction between number, cumulative area and duration, although older adults showed a greater sensitivity to task-irrelevant information than younger adults in the cumulative area task but lower sensitivity in the duration task. Continuous quantity processing seems therefore resilient to ageing similar to numerosity and to other non-quantity skills like vocabulary or implicit memory; however, ageing might differentially affect different quantity dimensions.

Evidence accumulation in the magnitude system

Perceptual interferences in the estimation of quantities (time, space and numbers) have been interpreted as evidence for a common magnitude system. However, if duration estimation has appears sensitive to spatial and numerical interferences, space and number estimation tend to be resilient to temporal manipulations. These observations question the relative contribution of each quantity in the elaboration of a representation in a common mental metric. Here, we elaborated a task in which perceptual evidence accumulated over time for all tested quantities (space, time and number) in order to match the natural requirement for building a duration percept. For this, we used a bisection task. Experimental trials consisted of dynamic dots of different sizes appearing progressively on the screen. Participants were asked to judge the duration, the cumulative surface or the number of dots in the display while the two non-target dimensions varied independently. In a prospective experiment, participants were informed before the trial which dimension was the target; in a retrospective experiment, participants had to attend to all dimensions and were informed only after a given trial which dimension was the target. Surprisingly, we found that duration was resilient to spatial and numerical interferences whereas space and number estimation were affected by time. Specifically, and counter-intuitively, results revealed that longer durations lead to smaller number and space estimates whether participants knew before (prospectively) or after (retrospectively) a given trial which quantity they had to estimate. Altogether, our results support a magnitude system in which perceptual evidence for time, space and numbers integrate following Bayesian cue-combination rules.

Subjectivity of time perception: a visual emotional orchestration

The aim of the present study was to examine how visual emotional content could orchestrate time perception. The experimental design allowed us to single out the share of emotion in the specific processing of content-bearing pictures, i.e., real-life scenes. Two groups of participants had to reproduce the duration (2, 4, or 6 s) of content-deprived stimuli (gray squares) or differentially valenced content-bearing stimuli, which included neutral, pleasant, and unpleasant pictures (International Affective Pictures Systems). Results showed that the effect of content differed according to duration: at 2 s, the reproduced duration was longer for content-bearing than content-deprived stimuli, but the difference between the two types of stimuli decreased as duration increased and was not significant for the longest duration (6 s). At 4 s, emotional (pleasant and unpleasant) stimuli were judged longer than neutral pictures. Furthermore, whatever the duration, the precision of the reproduction was greater for non-emotional than emotional stimuli (pleasant and unpleasant). These results suggest a dissociation within content effect on timing in the visual modality: relative overestimation of all content-bearing pictures limited to short durations (2 s), and delayed overestimation of emotional relative to neutral pictures at 4 s, as well as a lesser precision in the temporal judgment of emotional pictures whatever the duration. Our results underline the relevance for time perception models to integrate two ways of assessing timing in relationship with emotion: accuracy and precision.

Financial time series prediction using least squares support vector machines within the evidence framework

The Bayesian evidence framework is applied in this paper to least squares support vector machine (LS-SVM) regression in order to infer nonlinear models for predicting a financial time series and the related volatility. On the first level of inference, a statistical framework is related to the LS-SVM formulation which allows one to include the time-varying volatility of the market by an appropriate choice of several hyper-parameters. The hyper-parameters of the model are inferred on the second level of inference. The inferred hyper-parameters, related to the volatility, are used to construct a volatility model within the evidence framework. Model comparison is performed on the third level of inference in order to automatically tune the parameters of the kernel function and to select the relevant inputs. The LS-SVM formulation allows one to derive analytic expressions in the feature space and practical expressions are obtained in the dual space replacing the inner product by the related kernel function using Mercer's theorem. The one step ahead prediction performances obtained on the prediction of the weekly 90-day T-bill rate and the daily DAX30 closing prices show that significant out of sample sign predictions can be made with respect to the Pesaran-Timmerman test statistic.

Caenorhabditis elegans expresses three functional profilins in a tissue-specific manner

Profilins are actin binding proteins, which also interact with polyphosphoinositides and proline-rich ligands. On the basis of the genome sequence, three diverse profilin homologues (PFN) are predicted to exist in Caenorhabditis elegans. We show that all three isoforms PFN-1, PFN-2, and PFN-3 are expressed in vivo and biochemical studies indicate they bind actin and influence actin dynamics in a similar manner. In addition, they bind poly(L-proline) and phosphatidylinositol 4,5-bisphosphate micelles. PFN-1 is essential whereas PFN-2 and PFN-3 are nonessential. Immunostainings revealed different expression patterns for the profilin isoforms. In embryos, PFN-1 localizes in the cytoplasm and to the cell-cell contacts at the early stages, and in the nerve ring during later stages. During late embryogenesis, expression of PFN-3 was specifically detected in body wall muscle cells. In adult worms, PFN-1 is expressed in the neurons, the vulva, and the somatic gonad, PFN-2 in the intestinal wall, the spermatheca, and the pharynx, and PFN-3 localizes in a striking dot-like fashion in body wall muscle. Thus the model organism Caenorhabditis elegans expresses three profilin isoforms and is the first invertebrate animal with tissue-specific profilin expression.

Données sur les transferts du 137Cs et du 60Co dans un écosystème fluvial : le Rhône

L'étude radioécologique du Rhône permet d'évaluer qualitativement et quantitativement les radionucléides présents dans le fleuve. Les études menées in situ posent des questions concernant les modalités de transfert des radionucléides. Dans ce travail des expériences sont mises au point, afin d'analyser les mécanismes de bioconcentration dans les écosystèmes aquatiques. Pour le césium-137 les échanges entre l'eau, le sédiment et divers organismes aquatiques ont permis d'élaborer un modèle mathématique que l'on peut confronter aux valeurs mesurées sur le terrain. En ce qui concerne le Cobalt-60 les auteurs décrivent des expériences permettant l'évaluation de la contribution relative de l'eau et de la nourriture dans l'accumulation du radionucléide par un poisson.

Bayesian framework for least-squares support vector machine classifiers, gaussian processes, and kernel Fisher discriminant analysis

The Bayesian evidence framework has been successfully applied to the design of multilayer perceptrons (MLPs) in the work of MacKay. Nevertheless, the training of MLPs suffers from drawbacks like the nonconvex optimization problem and the choice of the number of hidden units. In support vector machines (SVMs) for classification, as introduced by Vapnik, a nonlinear decision boundary is obtained by mapping the input vector first in a nonlinear way to a high-dimensional kernel-induced feature space in which a linear large margin classifier is constructed. Practical expressions are formulated in the dual space in terms of the related kernel function, and the solution follows from a (convex) quadratic programming (QP) problem. In least-squares SVMs (LS-SVMs), the SVM problem formulation is modified by introducing a least-squares cost function and equality instead of inequality constraints, and the solution follows from a linear system in the dual space. Implicitly, the least-squares formulation corresponds to a regression formulation and is also related to kernel Fisher discriminant analysis. The least-squares regression formulation has advantages for deriving analytic expressions in a Bayesian evidence framework, in contrast to the classification formulations used, for example, in gaussian processes (GPs). The LS-SVM formulation has clear primal-dual interpretations, and without the bias term, one explicitly constructs a model that yields the same expressions as have been obtained with GPs for regression. In this article, the Bayesian evidence framework is combined with the LS-SVM classifier formulation. Starting from the feature space formulation, analytic expressions are obtained in the dual space on the different levels of Bayesian inference, while posterior class probabilities are obtained by marginalizing over the model parameters. Empirical results obtained on 10 public domain data sets show that the LS-SVM classifier designed within the Bayesian evidence framework consistently yields good generalization performances.

cAMP-dependent protein kinase phosphorylation of EVL, a Mena/VASP relative, regulates its interaction with actin and SH3 domains

Proteins of the Ena/VASP family are implicated in processes that require dynamic actin remodeling such as axon guidance and platelet activation. In this work, we explored some of the pathways that likely regulate actin dynamics in part via EVL (Ena/VASP-like protein). Two isoforms, EVL and EVL-I, were highly expressed in hematopoietic cells of thymus and spleen. In CD3-activated T-cells, EVL was found in F-actin-rich patches and at the distal tips of the microspikes that formed on the activated side of the T-cells. Like the other family members, EVL localized to focal adhesions and the leading edge of lamellipodia when expressed in fibroblasts. EVL was a substrate for the cAMP-dependent protein kinase, and this phosphorylation regulated several of the interactions between EVL and its ligands. Unlike VASP, EVL nucleated actin polymerization under physiological conditions, whereas phosphorylation of both EVL and VASP decreased their nucleating activity. EVL bound directly to the Abl, Lyn, and nSrc SH3 domains; the FE65 WW domain; and profilin, likely via its proline-rich core. Binding of Abl and nSrc SH3 domains, but not profilin or other SH3 domains, was abolished by cAMP-dependent protein kinase phosphorylation of EVL. We show strong cooperative binding of two profilin dimers on the polyproline sequence of EVL. Additionally, profilin competed with the SH3 domains for binding to partially overlapping binding sites. These data suggest that the function of EVL could be modulated in a complex manner by its interactions with multiple ligands and through phosphorylation by cyclic nucleotide dependent kinases.

Profilin II is alternatively spliced, resulting in profilin isoforms that are differentially expressed and have distinct biochemical properties

We deduced the structure of the mouse profilin II gene. It contains five exons that can generate four different transcripts by alternative splicing. Two transcripts encode different profilin II isoforms (designated IIa and IIb) that have similar affinities for actin but different affinities for polyphosphoinositides and proline-rich sequences. Profilins IIa and IIb are also present in humans, suggesting that all mammals have three profilin isoforms. Profilin I is the major form in all tissues, except in the brain, where profilin IIa is most abundant. Profilin IIb appears to be a minor form, and its expression is restricted to a limited number of tissues, indicating that the alternative splicing is tightly regulated. Western blotting and whole-mount in situ hybridization show that, in contrast to the expression of profilin I, the expression level of profilin IIa is developmentally regulated. In situ hybridization of adult brain sections reveals overlapping expression patterns of profilins I and IIa.

Dimerization of profilin II upon binding the (GP5)3 peptide from VASP overcomes the inhibition of actin nucleation by profilin II and thymosin beta4

Profilin II dimers bind the (GP5)3 peptide derived from VASP with an affinity of approximately 0.5 microM. The resulting profilin II-peptide complex overcomes the combined capacity of thymosin beta4 and profilin II to inhibit actin nucleation and restores the extent of filament formation. We do not observe such an effect when barbed filament ends are capped. Neither can profilin I, in the presence of the peptide, promote actin polymerization during its early phase consistent with a lower affinity. Since a Pro17 peptide-profilin II complex only partially restores actin polymerization, the glycine residues in the VASP peptide appear important.

Persistent T cell and B cell activities in the duodenal mucosa of AIDS patients

OBJECTIVE

As HIV infection most commonly occurs via a mucosal surface, and as gastrointestinal symptoms are very frequent among HIV-infected patients, we investigated the functional properties of residual lymphocytes in the duodenal mucosa from HIV-infected individuals.

DESIGN

Duodenal biopsies and blood samples were obtained from 19 HIV-infected patients [Centers for Disease Control and Prevention (CDC) stage III] and from 19 controls.

METHODS

Phenotypic analysis of lymphocytes was performed by flow cytometry and/or immunocytochemistry. Interferon gamma (IFN-gamma), interleukin (IL) 4 and immunoglobulin secretions were analysed by enzyme-linked immunospot techniques. The phenotype of cytokine-producing cells was analysed by flow cytometry.

RESULTS

The proportions of duodenal T lymphocytes from HIV-infected patients spontaneously secreting IFN-gamma or IL-4 were not lower than those from healthy controls. In patients with a high intestinal mucosal viral load, they were higher than in controls (P < 0.05). The proportions of immunoglobulin-secreting cells were significantly raised in HIV-infected patients for the three main isotypes.

CONCLUSIONS

T- and B-cell populations of the intestinal mucosa remain functional or are even activated in patients with AIDS, even when the numbers of both mucosal and circulating CD4+ lymphocytes are strongly decreased.

Spontaneous secretion of interferon gamma and interleukin 4 by human intraepithelial and lamina propria gut lymphocytes

BACKGROUND

Cytokines secreted by intestinal T lymphocytes probably play a critical role in regulation of the gut associated immune responses.

AIMS

To quantify interferon gamma (IFN-gamma) and interleukin 4 (IL-4) secreting cells (SC) among human intraepithelial (IEL) and lamina propria (LPL) lymphocytes from the duodenum and right colon in non-pathological situations and in the absence of in vitro stimulation.

PATIENTS

Duodenal and right colonic biopsy specimens were obtained from patients with no inflammation of the intestinal mucosa.

METHODS

Intraepithelial and lamina propria cell suspensions were assayed for numbers of cells spontaneously secreting IFN-gamma and IL-4 by a two site reverse enzyme linked immunospot technique (ELISPOT).

RESULTS

The relatively high proportion of duodenal lymphocytes spontaneously secreting IFN-gamma (IEL 3.6%; LPL 1.9%) and IL-4 (IEL 1.3%; LPL 0.7%) contrasted with the very low numbers of spontaneously IFN-gamma SC and the absence of spontaneously IL-4 SC among peripheral blood mononuclear cells. In the basal state, both IFN-gamma and IL-4 were mainly produced by CD4+ cells. Within the colon, only 0.2% of IEL and LPL secreted IFN-gamma in the basal state, and 0.1% secreted IL-4.

CONCLUSIONS

Compared with peripheral lymphocytes substantial proportions of intestinal epithelial and lamina propria lymphocytes spontaneously secrete IFN-gamma and/or IL-4. These cytokines are probably involved in the normal homoeostasis of the human intestinal mucosa. Disturbances in their secretion could play a role in the pathogenesis of gastrointestinal diseases.

The mammalian profilin isoforms display complementary affinities for PIP2 and proline-rich sequences

We present a study on the binding properties of the bovine profilin isoforms to both phosphatidylinositol 4,5-bisphosphate (PIP2) and proline-rich peptides derived from vasodilator-stimulated phosphoprotein (VASP) and cyclase-associated protein (CAP). Using microfiltration, we show that compared with profilin II, profilin I has a higher affinity for PIP2. On the other hand, fluorescence spectroscopy reveals that proline-rich peptides bind better to profilin II. At micromolar concentrations, profilin II dimerizes upon binding to proline-rich peptides. Circular dichroism measurements of profilin II reveal a significant conformational change in this protein upon binding of the peptide. We show further that PIP2 effectively competes for binding of profilin I to poly-L-proline, since this isoform, but not profilin II, can be eluted from a poly-L-proline column with PIP2. Using affinity chromatography on either profilin isoform, we identified profilin II as the preferred ligand for VASP in bovine brain extracts. The complementary affinities of the profilin isoforms for PIP2 and the proline-rich peptides offer the cell an opportunity to direct actin assembly at different subcellular localizations through the same or different signal transduction pathways.

Differential effect of human immunodeficiency virus infection on the IgA and IgG antibody responses to pneumococcal vaccine

The IgA, IgM, and IgG antibody responses to pneumococcal polysaccharide vaccine were analyzed in 35 asymptomatic or mildly symptomatic human immunodeficiency virus (HIV)-infected patients stratified according to their CD4 cell counts and in 12 healthy controls. Both the antibody titers in serum and saliva and the numbers of circulating antigen-specific antibody-producing cells (Elispot technique) were measured. At the peak of the antibody responses, HIV-infected patients mounted nearly normal IgG responses, while their IgM responses were significantly depressed, regardless of their CD4 cell counts. The IgA antibody response was decreased in patients with < 500 CD4 circulating cells/mm3. Most IgG antibodies belonged to the IgG2 subclass, and most IgA antibodies were dimeric IgA2 in both controls and patients. Anti-capsular pneumococcal polysaccharide IgG titers decreased much more rapidly in HIV-infected patients so that in all groups they were significantly lower than in controls 9 months after vaccination.

Serology of coeliac disease: early diagnosis and therapeutic impact

Sera from 88 patients with untreated coeliac disease (54 children and 34 adults), 127 disease controls and 69 healthy controls were tested for anti-gliadin IgA and IgG and anti-endomysium IgA in order to determine the best serological test or the best combination of tests to pick up all the coeliac patients. Only a combination of anti-gliadin IgG and of anti-endomysium IgA affords a 100% sensitivity for coeliac disease. If anti-gliadin IgA was added to the tests, the specificity of the combination gets higher in case of positive anti-gliadin IgA. It appears therefore that it is possible to detect the atypical cases of coeliac disease by a serological screening. This is of major interest in order to begin early dietary treatment of these patients to avoid the development of malignant disorders. The final diagnosis of coeliac disease must however always rely on the results of a small intestinal biopsy.

Purification and characterization of bovine profilin II. Actin, poly(L-proline) and inositolphospholipid binding

We purified profilin from bovine brain and were able to separate the two isoforms present in this tissue. Since functional characteristics for profilin II are lacking, we assayed the actin, the phosphatidylinositol 4,5-bisphosphate and the poly(L-proline) binding properties of this isoform. Profilin II binds actin with a similar affinity to that of profilin I, although it inhibits actin polymerization more strongly than profilin I under non-equilibrium conditions. Profilin II also binds the anionic phospholipid phosphatidylinositol 4,5-bisphosphate. Profilin II binds to poly(L-proline) more strongly than does profilin I; this is especially evident at more acidic pH values. This difference is explained by an amino acid exchange in the carboxy-terminal part of the protein which has been implicated in poly(L-proline) binding [Björkegren, C., Rozycki, M., Schutt, C., Lindberg, U. & Karlsson, R. (1993) FEBS Lett. 333, 123-126; Metzler, W., Bell, A., Ernst, E., Lavoie, T. & Mueller, L. (1994) J. Biol. Chem. 369, 4620-4625].

Human oesophagus: a convenient antigenic substrate for the determination of anti-endomysium antibodies in the serological diagnosis of coeliac disease

OBJECTIVE

Immunoglobulin (Ig) A-class anti-endomysium antibodies are superior to other current antibody tests for detecting coeliac disease. We aimed to evaluate the suitability of human oesophagus for the determination of anti-endomysium antibodies.

DESIGN

The specificity of monkey and human oesophageal tissue as antigenic substrate were compared using indirect immunofluorescence analysis.

PATIENTS AND METHODS

Overall, 159 individuals were studied: 56 patients with biopsy-proven coeliac disease (39 with active disease) and 103 controls. The patients' IgA-class anti-endomysium antibodies were compared using unfixed cryostat sections of human and monkey oesophagus. Indirect immunofluorescence analysis was performed with an initial serum sample dilution of 1:5, and if positive, the highest dilution yielding a positive reaction was reported.

RESULTS

The anti-endomysium antibody test was positive in 38 out of 39 patients with active coeliac disease using monkey oesophagus (sensitivity 97%) and in all 39 patients with active coeliac disease using human oesophagus (sensitivity 100%). Ten out of 17 coeliac patients on a gluten-free diet had positive anti-endomysium antibodies using monkey oesophagus and 12 using human oesophagus as the antigenic substrate. This test was negative in all 103 controls using both substrates.

CONCLUSIONS

Our study shows that human oesophageal tissue can be used instead of monkey tissue for determining anti-endomysium antibodies. Human tissue is a more sensitive antigenic substrate than monkey oesophagus and can be used to determine low titres of antibodies. Improving the diagnostic sensitivity of the anti-endomysium antibody test would make an important contribution to screening for coeliac disease.

[The clinical relevance of autoantibody studies in connective tissue diseases and vasculitis]

The relevance of detection, quantification and characterisation of antinuclear antibodies and of anti-neutrophil cytoplasm antibodies in diagnosis of connective tissue disorders and of idiopathic vasculitis, is nowadays quite important. Since many years, antibody detection is routinely performed by indirect immunofluorescence tests; their sensitivity is very high so that several diagnoses might be ruled out in the presence of a negative result. These tests are however not specific. During the last years several progress have been realised in the characterisation of the antigens recognized by these antibodies, allowing the development of new techniques for specifically identifying several autoantibodies. It is therefore possible to detect now routinely with specific and sensitive techniques the presence of anti-double stranded DNA, anti-RNP, anti-Sm, anti-Scl-70, anti-SS-A, anti-SS-B, and anti-myeloperoxidase and anti-proteinase 3. The significance of the presence of these antibodies in serum will be discussed in this paper.

[Anti-neutrophil cytoplasmic antibodies (ANCA): major progress in the diagnosis of vasculitis]

ANCA antibodies represent a family of autoantibodies directed against neutrophil enzymes. Immunofluorescence patterns allow to distinguish c-ANCAs from p-ANCAs. The detection of ANCAs is often a key element for the diagnosis of Wegener's granulomatosis, microperiarteritis, Churg-Strauss syndrome and idiopathic rapidly progressive glomerulonephritis. Although the pathogenic role of ANCAs is not firmly established, their detection often allows an early therapeutic decision in necrotizing vasculitides.

[Anti-phospholipid antibodies and recurrent miscarriage]

Antiphospholipid antibodies are associated with arterial and venous thromboembolism, thrombocytopenia and fetal loss. According to several studies the obstetrical problems associated with antiphospholipid antibodies can be successfully treated with immunosuppressive or anticoagulant drugs. The detection of these antibodies is difficult owing to the lack of standardization and of specificity of the laboratory tests.

Moderate mental retardation and nonspecific dysmorphic syndrome associated with ring chromosome 9

A ring chromosome 9 is reported in a 12-year-old, moderately mentally retarded boy. As in other ring chromosome 9 patients, the clinical stigmata are nonspecific and their expressivity is mild. The finding of two normal cells of a total of 121 cells examined favors the hypothesis of a postzygotic, mitotic origin of the ring chromosome formation.