Superior Convexity Research Articles

Brugada syndrome: current concepts and genetic background

Brugada syndrome (BrS) is a hereditary clinical-electrocardiographic arrhythmic entity with low worldwide prevalence. The syndrome is caused by changes in the structure and function of certain cardiac ion channels and reduced expression of Connexin 43 (Cx43) in the Right Ventricle (RV), predominantly in the Right Ventricular Outflow Tract (VSVD), causing electromechanical abnormalities. The diagnosis is based on the presence of spontaneous or medicated ST elevation, characterized by boost of the J point and the ST segment ≥2 mm, of superior convexity "hollow type" (subtype 1A) or descending rectilinear model (subtype 1B). BrS is associated with an increased risk of syncope, palpitations, chest pain, convulsions, difficulty in breathing (nocturnal agonal breathing) and/or Sudden Cardiac Death (SCD) secondary to PVT/VF, unexplained cardiac arrest or documented PVT/VF or Paroxysmal atrial fibrillation (AF) in the absence of apparent macroscopic or structural heart disease, electrolyte disturbance, use of certain medications or coronary heart disease and fever. In less than three decades since the discovery of Brugada syndrome, the concept of Mendelian heredity has come undone. The enormous variants and mutations found mean that we are still far from being able to concretely clarify a genotype-phenotype relationship. There is no doubt that the entity is oligogenetic, associated with environmental factors, and that there are variants of uncertain significance, especially the rare variants of the SCN5A mutation, with European or Japanese ancestors, as well as a spontaneous type 1 or induced pattern, thanks to gnomAD (coalition) researchers who seek to aggregate and harmonize exome and genome sequencing data from a variety of large scale sequencing projects and make summary data available to the scientific community at large). Thus, we believe that this in depth analytical study of the countless mutations attributed to BrS may constitute a real cornerstone that will help to better understand this intriguing syndrome.

Functional Magnetic Resonance Imaging Correlates of Ventral Striatal Deep Brain Stimulation for Poststroke Pain

ObjectiveDeep brain stimulation (DBS) for pain has largely been implemented in an uncontrolled manner to target the somatosensory component of pain, with research leading to mixed results. We have previously shown that patients with poststroke pain syndrome who were treated with DBS targeting the ventral striatum/anterior limb of the internal capsule (VS/ALIC) demonstrated a significant improvement in measures related to the affective sphere of pain. In this study, we sought to determine how DBS targeting the VS/ALIC modifies brain activation in response to pain. Materials and MethodsFive patients with poststroke pain syndrome who were blinded to DBS status (ON/OFF) and six age- and sex-matched healthy controls underwent functional magnetic resonance imaging (fMRI) measuring blood oxygen level-dependent activation in a block design. In this design, each participant received heat stimuli to the affected or unaffected wrist area. Statistical comparisons were performed using fMRI z-maps. ResultsIn response to pain, patients in the DBS OFF state showed significant activation (p < 0.001) in the same regions as healthy controls (thalamus, insula, and operculum) and in additional regions (orbitofrontal and superior convexity cortical areas). DBS significantly reduced activation of these additional regions and introduced foci of significant inhibitory activation (p < 0.001) in the hippocampi when painful stimulation was applied to the affected side. ConclusionsThese findings suggest that DBS of the VS/ALIC modulates affective neural networks.

Computerized tomography based 3D modeling of the clavicle.

Previous studies have suggested clavicular morphology is highly variable, particularly in the lateral retrocurved section. Current clavicle fracture plating systems require three dimensional intra-operative contouring to achieve adequate fit and necessitate variable soft tissue dissection placing fracture perfusion and muscular attachments at risk. The aim of this study was to search for a surgically relevant superficial shape pattern. This is a retrospective CT-based analysis of 174 non-pathological clavicles in 95 adults (45 females, 50 males). Using the principle of cylindrical parameterisation generated 3-D computer models, we identified an implant preferred pathway (IPP), defined as a continuous linear region where the least possible soft tissue disruption would be necessary for plate fixation. The IPP mean form was within 3.04 mm (SD ± 1.34) on all clavicles. Clavicle length, and not shape, was found to be the biggest variable (correlation between size and form co-ordinates r = 0.99, p < 0.05), accounting for 79% of overall variability. This length variation was mainly located in the medial antecurved section. Superior convexity and recurvatum were the main shape variables, however they only contributed 8% and 5% to the overall variation, respectively. Three IPP lengths were shown to match all clavicles when aligned at the acromial end first. In contrast to previous studies, we have shown that the IPP is fairly consistent with respect to the general shape with the exception of length variation which mainly affected the medial antecurved section. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1216-1223, 2016. Future pre-contoured fracture fixation systems should provide variable length plates with a constant lateral section retrocurve and a variable medial antecurve.

Functional Brain Mapping of the Macaque Related to Spatial Working Memory as Revealed by PET

To define the cortical areas that subserve spatial working memory in a nonhuman primate, we measured regional cerebral blood flow (rCBF) with [(15)O]H(2)O and positron emission tomography while monkeys performed a visually guided saccade (VGS) task and an oculomotor delayed-response (ODR) task. Both Statistical Parametric Mapping and regions of interest-based analyses revealed an increase of rCBF in the area surrounding the principal sulcus (PS), the superior convexity, the anterior bank of the arcuate sulcus (AS), the lateral orbitofrontal cortex (lOFC), the frontal pole (FP), the anterior cingulate cortex (ACC), the lateral bank of the intraparietal sulcus (lIPS) and the prestriate cortex. In the prefrontal cortex (PS, superior convexity, AS, lOFC and FP), rCBF values correlated positively with ODR task performance scores. From the hippocampus, rCBF values correlated negatively with ODR task performance. From the AS, superior convexity, lOFC, FP, ACC and lIPS, rCBF values of the PS correlated positively with rCBF values and negatively with hippocampus rCBF values. These results suggest that neural circuitry in the prefrontal cortex directly contributes the spatial working memory processes and that, in spatial working memory processes, the posterior parietal cortex and hippocampus have a different role to the prefrontal cortex.

Prefrontal representation of stimulus attributes during delay tasks. II. The role of behavioral significance

Rhesus monkeys were trained to perform two visual discrimination tasks with delayed response. In both tasks, the response depended on the color of the cue, a lighted circle in the center of a panel. Red and green guided one task, yellow and blue the other. In the course of performance, a fifth color (violet), non-relevant and inconsequential, was presented at random in the same location as the cues. All 5 stimuli were of equal brithtness. Many cells in the dorsolateral prefrontal cortex (sulcus principalis and superior convexity) treated the relevant cues differently than the irrelevant stimulus. In general, cellular reactions to that stimulus were of lesser magnitude than the reactions to the cues. Cell reaction differences as a function of stimulus significance outnumbered and overshadowed differences as a function of cue-color or any other task variable. The results indicate that, during visual delay tasks, units in the dorsolateral prefrontal cortex differentiate stimuli by their behavioral significance, as well as by other stimulus attributes, including color. Because the motivational evaluation of sensory stimuli is an integral part of the cognitive processes in delay tasks (together with short-term memory and motor set), these results support the notion that the prefrontal cortex integrates motivational inputs into the structure of behavioral action.

Fundamental functions in equilibrium thermodynamics

In the standard presentations of the principles of Gibbsian equilibrium thermodynamics one can find several gaps in the logic. For a subject that is as widely used as equilibrium thermodynamics, it is of interest to clear up such questions of mathematical rigor. In this paper it is shown that using convex analysis one can give a mathematically rigorous treatment of several basic aspects of equilibrium thermodynamics. On the basis of a fundamental convexity property implied by the second law, the following topics are discussed: thermodynamic stability, transformed fundamental functions (such as the Gibbs free energy), and the existence and uniqueness of possible final equilibrium states of closed composite thermodynamic systems. It is shown that a standard mathematical characterization of thermodynamic stability (involving a positive definiteness property) is sufficient but in fact not necessary for the physically superior convexity characterization of thermodynamic stability. Furthermore, it is found that functions such as the Gibbs free energy can be rigorously and globally defined using convex conjugation instead of Legendre transformation. Another result desribed in this paper is that equilibrium thermodynamics cannot always uniquely predict possible final equilibrium states of closed composite thermodynamic systems.

Suppression-burst activity from isolated cerebral cortex in man

1. 1. Direct electrical recording from the cortex of man has been carried out on 34 patients before, throughout and following prefrontal lobotomy. Operations were done under local as well as Pentothal anesthesia, and included the classical or standard “open” prefrontal lobotomy and surgical isolation by undercutting of both superior convexity (partial Brodmann areas 9 and 10) and orbital surfaces. The pial circulation was preserved in all cases. 2. 2. All cases showed a marked decrease in electrical activity from cortex rostral to the section, and all but one showed the development of bursts of fast activity alternating with quiet sections of record. Such bursts were usually superimposed on or followed by high voltage very slow delta activity. 3. 3. This suppression-burst activity was confined to isolated cortex and was not seen from leads lateral and posterior to such cortex. It was characteristically asynchronous from right and left sides. 4. 4. Suppression-burst activity, as judged from its continued presence at the time of repeat operation,persisted for over a year in the electrogram of undercut cortex, but was not detected in the scalp EEG. 5. 5. Suppression-burst activity, while resembling the patterns of barbiturate bursts, does not depend on barbiturate or other anesthesia for it developed in characteristic form in cases operated under local anesthesia. 6. 6. This pattern is probably analogous to that seen in cats following lesions to the basal diencephalon. It is possibly related to the release of cortex from the influence of the reticular activating system. 7. 7. Some of the literature dealing with the relative role of cortex and thalamus is reviewed. It is concluded that there is autochthonous electrocortical activity and that reverberating thalamo-cortical circuits are not necessary for the maintenance of such activity.

The Significance of the Roentgen Visibility of the Horizontal Fissure

THE appearance in the roentgenogram of the chest of linear shadows corresponding to the interlobar fissures of the lung is not unusual, and by comparison of such shadows with anatomic specimens a better understanding of the anatomy of the lungs has been attained (10, 5, 24). This has permitted the more accurate localization of pathologic processes seen in the chest roentgenogram in terms of the lobes and fissures which may be involved. Particularly important has been the identification of certain previously puzzling shadows sometimes included among the “unresolved pneumonias,” and which have, in some instances, been shown to be due to effusions limited to the pulmonary fissures. The unusual and, at times, bizarre outlines of these shadows are thus easily understood. By means of its normal position in the horizontal plane, the fissure between the right upper and middle lobes has attracted primary attention in this extension of x-ray critique. Thus, it is obvious that the plane of a fissure which becomes partially radiopaque would more easily be demonstrable when its greatest diameter lay in the axis of the roentgen ray, whereas, if the ray should penetrate it perpendicularly, the result might be only a faint haziness in the area of its projection, difficult of evaluation, if even detectable. In the customary postero-anterior chest roentgenogram, the horizontal fissure is, therefore, in a position, despite its slight superior convexity, to cast its densest shadow, whereas the long or oblique fissures in front of the lower lobes, being intercepted perpendicularly by the x-ray in the greater part of their extent, are not usually noticed on the film unless they contain a considerable amount of fluid, or their walls are grossly thickened by pathologic induration. Such pathology might give rise to the unusual shadows referred to previously, correctly identified through an adequate understanding of pulmonary lobar anatomy, and by the study of the interlobar spaces, in the case in question, by unusual or special technic. At times the lateral extremity of the oblique fissure attains a plane passing anterolaterally from the hilus which permits it to be demonstrated in the usual chest radiogram as an almost vertical line or one passing slightly laterally and cephalad from the diaphragm, approximately one-fourth the distance from the lateral costal margin to the mid-line (Fig. 1). This shadow may be either unilateral or bilateral, and visualization is made possible by the occasional concurrence of the plane of the fissure and the more divergent rays from an x-ray target comparatively close to the film. A lateral projection, however, permits better demonstration of the oblique fissure of the hemithorax nearest the film, and, on the right, its relationship with the horizontal fissure (11). These demonstrations have been presented by several authors (2, 4, 10).