Computer-aided diagnosis of carotid atherosclerosis based on ultrasound image statistics, laws' texture and neural networks

Quantitative characterisation of carotid atherosclerosis and classification into symptomatic or asymptomatic is crucial in planning optimal treatment of atheromatous plaque. The computer-aided diagnosis (CAD) system described in this paper can analyse ultrasound (US) images of carotid artery and classify them into symptomatic or asymptomatic based on their echogenicity characteristics. The CAD system consists of three modules: a) the feature extraction module, where first-order statistical (FOS) features and Laws' texture energy can be estimated, b) the dimensionality reduction module, where the number of features can be reduced using analysis of variance (ANOVA), and c) the classifier module consisting of a neural network (NN) trained by a novel hybrid method based on genetic algorithms (GAs) along with the back propagation algorithm. The hybrid method is able to select the most robust features, to adjust automatically the NN architecture and to optimise the classification performance. The performance is measured by the accuracy, sensitivity, specificity and the area under the receiver-operating characteristic (ROC) curve. The CAD design and development is based on images from 54 symptomatic and 54 asymptomatic plaques. This study demonstrates the ability of a CAD system based on US image analysis and a hybrid trained NN to identify atheromatous plaques at high risk of stroke.

Executive functions and their differential contribution to sustained attention in 5- to 8-year-old children

ABSTRACT Everyday routine in general and school settings in particular make high demands on children's abilities to sustain their focus of attention over longer time periods. School tasks thus require the child to accomplish the task on an appropriate level of performance while maintaining the focus of attention even under repetitious or distracting conditions. However, sustained attention (SA) may be a more heterogeneous construct than commonly assumed as it requires the individual not only to sustain attentional capacities but also to store and maintain the task rule (working memory), to inhibit inappropriate responses (inhibition), and to switch according to requirements (switching). It might thus involve processes counted among executive functions (EF). In the present study, performance in EF tasks (covering the core components inhibition, switching, and working memory) and in a SA task was assessed in 118 children, aged between 5;0 and 8;11 years. Similar age-dependent performance trajectories were found in EF components and SA, indicating ongoing performance improvements between 5 until at least 8 years of age in SA and in EF. Interrelations between single EF components and SA showed to be small to moderate. Finally, different patterns of SA performance predictions were found in age-homogeneous subgroups with inhibition being crucial for SA performance in the youngest and switching in the oldest age group. Taken as a whole, even though similarities in assumed developmental trajectories and substantial interrelations point to common underlying processes in EF and SA, age-dependent patterns of explained variance indicate clear discriminability.

Health risk appraisal in older people 6: factors associated with self-reported poor vision and uptake of eye tests in older people

BACKGROUND Although free eye testing is available in the UK from a nation-wide network of optometrists, there is evidence of unrecognised, tractable vision loss amongst older people. A recent review identified this unmet need as a priority for further investigation, highlighting the need to understand public perceptions of eye services and barriers to service access and utilisation. This paper aims to identify risk factors for (1) having poor vision and (2) not having had an eyesight check among community-dwelling older people without an established ophthalmological diagnosis. METHODS Secondary analysis of self-reported data from the ProAge trial. 1792 people without a known ophthalmological diagnosis were recruited from three group practices in London. RESULTS Almost two in ten people in this population of older individuals without known ophthalmological diagnoses had self-reported vision loss, and more than a third of them had not had an eye test in the previous twelve months. In this sample, those with limited education, depressed mood, need for help with instrumental and basic activities of daily living (IADLs and BADLs), and subjective memory complaints were at increased risk of fair or poor self-reported vision. Individuals with basic education only were at increased risk for not having had an eye test in the previous 12 months (OR 1.52, 95% CI 1.17-1.98 p=0.002), as were those with no, or only one chronic condition (OR 1.850, 95% CI 1.382-2.477, p<0.001). CONCLUSIONS Self-reported poor vision in older people without ophthalmological diagnoses is associated with other functional losses, with no or only one chronic condition, and with depression. This pattern of disorders may be the basis for case finding in general practice. Low educational attainment is an independent determinant of not having had eye tests, as well as a factor associated with undiagnosed vision loss. There are other factors, not identified in this study, which determine uptake of eye testing in those with self-reported vision loss. Further exploration is needed to identify these factors and lead towards effective case finding.

Plant architecture

Plant architecture is species specific, indicating that it is under strict genetic control. Although it is also influenced by environmental conditions such as light, temperature, humidity and nutrient status, here we wish to focus only on the endogenous regulatory principles that control plant architecture. We summarise recent progress in the understanding of the basic patterning mechanisms involved in the regulation of leaf arrangement, the genetic regulation of meristem determinacy, i.e. the decision to stop or continue growth, and the control of branching during vegetative and generative development. Finally, we discuss the basis of leaf architecture and the role of cell division and cell growth in morphogenesis.

Notch signaling in the brain: in good and bad times.

Notch signaling is an evolutionarily conserved pathway, which is fundamental for neuronal development and specification. In the last decade, increasing evidence has pointed out an important role of this pathway beyond embryonic development, indicating that Notch also displays a critical function in the mature brain of vertebrates and invertebrates. This pathway appears to be involved in neural progenitor regulation, neuronal connectivity, synaptic plasticity and learning/memory. In addition, Notch appears to be aberrantly regulated in neurodegenerative diseases, including Alzheimer's disease and ischemic injury. The molecular mechanisms by which Notch displays these functions in the mature brain are not fully understood, but are currently the subject of intense research. In this review, we will discuss old and novel Notch targets and molecular mediators that contribute to Notch function in the mature brain and will summarize recent findings that explore the two facets of Notch signaling in brain physiology and pathology.

Kognitive Basisfunktionen und motorisch-koordinative Kompetenzen in Abhängigkeit des Peerstatus bei Kindern zu Beginn der Schulzeit

Zusammenfassung. In der vorliegenden Studie wird der Frage nachgegangen, ob sich zwischen beliebten, durchschnittlichen, unbeachteten und zurückgewiesenen Kindern Unterschiede in spezifischen kognitiven und motorischen Fähigkeiten finden lassen. Zu drei verschiedenen Zeitpunkten wurden mit 177 regulär eingeschulten 7-jährigen Kindern Peernominationen und Peerratings erhoben, um reliable soziometrische Daten zu erhalten und ein Vergleich der beiden Methoden vorzunehmen. Außerdem wurde eine umfassende Testbatterie von insgesamt 20 Aufgaben in den Bereichen Informationsverarbeitungsgeschwindigkeit, Kurzzeit- und Arbeitsgedächtnis, Inhibition, Sprache und Motorik durchgeführt. Mit Ausnahme der Kurzzeitgedächtniskapazität wurden für alle Funktionsbereiche signifikante Unterschiede zwischen den Statusgruppen gefunden. Die kontinuierlichen soziometrischen Werte der Ratingmethode zeigten sich etwas sensitiver als die der Nominationsmethode. Korrelativ wurde mit beiden Methoden ersichtlich, dass bessere Leistungen im kognitiven und motorischen Bereich nicht nur mit mehr Beliebtheit zusammenhingen, sondern auch, dass schlechte Leistungen in Verbindung standen mit sozialer Zurückweisung. Abstract. In the present study, it was investigated whether popular, average, neglected, and rejected children differ with respect to specific cognitive and motor skills. Peer nomination and peer rating methods were used at three different points in time to obtain reliable sociometric data of 177 regularly enrolled 7-year-old children and to compare the two methods. Furthermore, a battery comprising 21 tasks was used to assess speed of information processing, short-term and working memory, inhibition, language, and motor skills. Significant differences were found between children of different status groups with respect to all studied abilities with the exception of short-term memory. The continuous sociometric scores of the rating method resulted to be slightly more sensitive than those obtained with the nomination method. However, correlative analyses with both methods showed that better performance on the cognitive and motor tasks was associated with popularity, whereas worse performance was related to social rejection.

Cognitive and emotional effects of carotid stenosis

PRINCIPLES Patients with carotid artery stenosis (CAS) are at risk of ipsilateral stroke and chronic compromise of cerebral blood flow. It is under debate whether the hypo-perfusion or embolism in CAS is directly related to cognitive impairment. Alternatively, CAS may be a marker for underlying risk factors, which themselves influence cognition. We aimed to determine cognitive performance level and the emotional state of patients with CAS. We hypothesised that patients with high grade stenosis, bilateral stenosis, symptomatic patients and/or those with relevant risk factors would suffer impairment of their cognitive performance and emotional state. METHODS A total of 68 patients with CAS of ≥70% were included in a prospective exploratory study design. All patients underwent structured assessment of executive functions, language, verbal and visual memory, motor speed, anxiety and depression. RESULTS Significantly more patients with CAS showed cognitive impairments (executive functions, word production, verbal and visual memory, motor speed) and anxiety than expected in a normative sample. Bilateral and symptomatic stenosis was associated with slower processing speed. Cognitive performance and anxiety level were not influenced by the side and the degree of stenosis or the presence of collaterals. Factors associated with less cognitive impairment included higher education level, female gender, ambidexterity and treated hypercholesterolemia. CONCLUSIONS Cognitive impairment and increased level of anxiety are frequent in patients with carotid stenosis. The lack of a correlation between cognitive functioning and degree of stenosis or the presence of collaterals, challenges the view that CAS per se leads to cognitive impairment.

Event-relating to potential dementia. Semantic processing in the course of healthy and pathological aging

While most healthy elderly are able to manage their everyday activities, studies showed that there are both stable and declining abilities during healthy aging. For example, there is evidence that semantic memory processes which involve controlled retrieval mechanism decrease, whereas the automatic functioning of the semantic network remains intact. In contrast, patients with Alzheimer’s disease (AD) suffer from episodic and semantic memory impairments aggravating their daily functioning. In AD, severe episodic as well as semantic memory deficits are observable. While the hallmark symptom of episodic memory decline in AD is well investigated, the underlying mechanisms of semantic memory deterioration remain unclear. By disentangling the semantic memory impairments in AD, the present thesis aimed to improve early diagnosis and to find a biomarker for dementia. To this end, a study on healthy aging and a study with dementia patients were conducted investigating automatic and controlled semantic word retrieval. Besides the inclusion of AD patients, a group of participants diagnosed with semantic dementia (SD) – showing isolated semantic memory loss – was assessed. Automatic and controlled semantic word retrieval was measured with standard neuropsychological tests and by means of event-related potentials (ERP) recorded during the performance of a semantic priming (SP) paradigm. Special focus was directed to the N400 or N400-LPC (late positive component) complex, an ERP that is sensitive to the semantic word retrieval. In both studies, data driven topographical analyses were applied. Furthermore, in the patient study, the combination of the individual baseline cerebral blood flow (CBF) with the N400 topography of each participant was employed in order to relate altered functional electrophysiology to the pathophysiology of dementia. Results of the aging study revealed that the automatic semantic word retrieval remains stable during healthy aging, the N400-LPC complex showed a comparable topography in contrast to the young participants. Both patient groups showed automatic SP to some extent, but strikingly the ERP topographies were altered compared to healthy controls. Most importantly, the N400 was identified as a putative marker for dementia. In particular, the degree of the topographical N400 similarity was demonstrated to separate healthy elderly from demented patients. Furthermore, the marker was significantly related to baseline CBF reduction in brain areas relevant for semantic word retrieval. Summing up, the first major finding of the present thesis was that all groups showed semantic priming, but that the N400 topography differed significantly between healthy and demented elderly. The second major contribution was the identification of the N400 similarity as a putative marker for dementia. To conclude, the present thesis added evidence of preserved automatic processing during healthy aging. Moreover, a possible marker which might contribute to an improved diagnosis and lead consequently to a more effective treatment of dementia was presented and has to be further developed.

Bone Volume Fraction and Fabric Anisotropy Are Better Determinants of Trabecular Bone Stiffness than Other Morphological Variables

As our population ages, more individuals suffer from osteoporosis. This disease leads to impaired trabecular architecture and increased fracture risk. It is essential to understand how morphological and mechanical properties of the cancellous bone are related. Morphologyelasticity relationships based on bone volume fraction (BV/TV) and fabric anisotropy explain up to 98% of the variation in elastic properties. Yet, other morphological variables such as individual trabeculae segmentation (ITS) and trabecular bone score (TBS) could improve the stiffness predictions. A total of 743 micro-computed tomography reconstructions of cubic trabecular bone samples extracted from femur, radius, vertebrae and iliac crest were analysed. Their morphology was assessed via 25 variables and their stiffness tensor (inline image) was computed from six independent load cases using micro finite element analyses. Variance inflation factors were calculated to evaluate collinearity between morphological variables and decide upon their inclusion in morphology-elasticity relationships. The statistically admissible morphological variables were included in a multi-linear regression modelling the dependent variable inline image. The contribution of each independent variable was evaluated (ANOVA). Our results show that BV/TV is the best determinant of inline image (inline image=0.889), especially in combination with fabric (inline image=0.968). Including the other independent predictors hardly affected the amount of variance explained by the model (inline image=0.975). Across all anatomical sites, BV/TV explained 87% of the variance of the bone elastic properties. Fabric further described 10% of the bone stiffness, but the improvement in variance explanation by adding other independent factors was marginal (<1%). These findings confirm that BV/TV and fabric are the best determinants of trabecular bone stiffness and show, against common belief, that other morphological variables do not bring any further contribution. These overall conclusions remain to be confirmed for specific bone diseases and post-elastic properties.

Classification of platelet concentrates (Platelet-Rich Plasma-PRP, Platelet-Rich Fibrin-PRF) for topical and infiltrative use in orthopedic and sports medicine: current consensus, clinical implications and perspectives.

Platelet concentrates for topical and infiltrative use - commonly termed Platetet-Rich Plasma (PRP) or Platelet-Rich Fibrin (PRF) - are used or tested as surgical adjuvants or regenerative medicine preparations in most medical fields, particularly in sports medicine and orthopaedic surgery. Even if these products offer interesting therapeutic perspectives, their clinical relevance is largely debated, as the literature on the topic is often confused and contradictory. The long history of these products was always associated with confusions, mostly related to the lack of consensual terminology, characterization and classification of the many products that were tested in the last 40 years. The current consensus is based on a simple classification system dividing the many products in 4 main families, based on their fibrin architecture and cell content: Pure Platelet-Rich Plasma (P-PRP), such as the PRGF-Endoret technique; Leukocyte- and Platelet-Rich Plasma (LPRP), such as Biomet GPS system; Pure Platelet-Rich Fibrin (P-PRF), such as Fibrinet; Leukocyte- and Platelet-Rich Fibrin (L-PRF), such as Intra-Spin L-PRF. The 4 main families of products present different biological signatures and mechanisms, and obvious differences for clinical applications. This classification serves as a basis for further investigations of the effects of these products. Perspectives of evolutions of this classification and terminology are also discussed, particularly concerning the impact of the cell content, preservation and activation on these products in sports medicine and orthopaedics.

Plasma-functionalized electrospun matrix for biograft development and cardiac function stabilization.

Cardiac tissue engineering approaches can deliver large numbers of cells to the damaged myocardium and have thus increasingly been considered as a possible curative treatment to counteract the high prevalence of progressive heart failure after myocardial infarction (MI). Optimal scaffold architecture and mechanical and chemical properties, as well as immune- and bio-compatibility, need to be addressed. We demonstrated that radio-frequency plasma surface functionalized electrospun poly(ɛ-caprolactone) (PCL) fibres provide a suitable matrix for bone-marrow-derived mesenchymal stem cell (MSC) cardiac implantation. Using a rat model of chronic MI, we showed that MSC-seeded plasma-coated PCL grafts stabilized cardiac function and attenuated dilatation. Significant relative decreases of 13% of the ejection fraction (EF) and 15% of the fractional shortening (FS) were observed in sham treated animals; respective decreases of 20% and 25% were measured 4 weeks after acellular patch implantation, whereas a steadied function was observed 4 weeks after MSC-patch implantation (relative decreases of 6% for both EF and FS).

Semi-dwarfism and lodging tolerance in tef (Eragrostis tef) is linked to a mutation in the α-Tubulin 1 gene

Genetic improvement of native crops is a new and promising strategy to combat hunger in the developing world. Tef is the major staple food crop for approximately 50 million people in Ethiopia. As an indigenous cereal, it is well adapted to diverse climatic and soil conditions; however, its productivity is extremely low mainly due to susceptibility to lodging. Tef has a tall and weak stem, liable to lodge (or fall over), which is aggravated by wind, rain, or application of nitrogen fertilizer. To circumvent this problem, the first semi-dwarf lodging-tolerant tef line, called kegne, was developed from an ethyl methanesulphonate (EMS)-mutagenized population. The response of kegne to microtubule-depolymerizing and -stabilizing drugs, as well as subsequent gene sequencing and segregation analysis, suggests that a defect in the α-Tubulin gene is functionally and genetically tightly linked to the kegne phenotype. In diploid species such as rice, homozygous mutations in α-Tubulin genes result in extreme dwarfism and weak stems. In the allotetraploid tef, only one homeologue is mutated, and the presence of the second intact α-Tubulin gene copy confers the agriculturally beneficial semi-dwarf and lodging-tolerant phenotype. Introgression of kegne into locally adapted and popular tef cultivars in Ethiopia will increase the lodging tolerance in the tef germplasm and, as a result, will improve the productivity of this valuable crop.

Neural representation and clinically relevant moderators of individualised self-criticism in healthy subjects

Many people routinely criticise themselves. While self-criticism is largely unproblematic for most individuals, depressed patients exhibit excessive self-critical thinking, which leads to strong negative affects. We used functional magnetic resonance imaging in healthy subjects (N = 20) to investigate neural correlates and possible psychological moderators of self-critical processing. Stimuli consisted of individually selected adjectives of personally negative content and were contrasted with neutral and negative non-self-referential adjectives. We found that confrontation with self-critical material yielded neural activity in regions involved in emotions (anterior insula/hippocampus-amygdala formation) and in anterior and posterior cortical midline structures, which are associated with self-referential and autobiographical memory processing. Furthermore, contrasts revealed an extended network of bilateral frontal brain areas. We suggest that the co-activation of superior and inferior lateral frontal brain regions reflects the recruitment of a frontal top-down pathway, representing cognitive reappraisal strategies for dealing with evoked negative affects. In addition, activation of right superior frontal areas was positively associated with neuroticism and negatively associated with cognitive reappraisal. Although these findings may not be specific to negative stimuli, they support a role for clinically relevant personality traits in successful regulation of emotion during confrontation with self-critical material.