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Appendages
Kinds of Appendages Selected AbstractsIMAGE SECTION: Stunning of Left Atrial Appendage after Spontaneous Conversion of Atrial FibrillationECHOCARDIOGRAPHY, Issue 3 2008Mikko Savontaus M.D. No abstract is available for this article. [source] Role of Echocardiography in Percutaneous Occlusion of the Left Atrial AppendageECHOCARDIOGRAPHY, Issue 4 2007Mráz M.D. Percutaneous occlusion of the left atrial appendage (LAA) is a modern alternative for the treatment of patients with atrial fibrillation (AF) and with a high risk of stroke who are not eligible for long-term anticoagulation therapy. Echocardiography plays a significant role in selecting patients, guiding the procedure, and in the postprocedural follow-up. Objectives and methods: To test the role of transesophagoeal echocardiography (TEE) and intracardiac echocardiography (ICE) in facilitating and shortening the procedure. Results: ICE represents a more convenient approach in patients who are not under generally anesthesia and helps to facilitate transseptal puncture. On the other hand, TEE, having the ability to rotate the image plane, helps to better determine the position of the occluder. Conclusions: Echocardiographic guidance of this procedure is essential. Which approach will be preferred will depend on the development of these two methods. [source] Congenital Aneurysm of Left Atrial Appendage: A Case ReportJOURNAL OF CARDIAC SURGERY, Issue 1 2010Sanjeev Gupta M.S. We report a case of a two-year-old child with congenital aneurysm of the LAA with a large thrombus in it. He presented with an episode of seizures with left-sided hemiparesis. Diagnosis was based on transthoracic echocardiography and magnetic resonance imaging. The patient was successfully treated by surgical resection of the aneurysm and removal of the thrombus.(J Card Surg 2010;25:37-40) [source] Distinguishing Far-Field Appendage from Local Pulmonary Vein Signal in the Left Upper Pulmonary Vein During Atrial TachycardiaJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 4 2010EDWARD DUNCAN Ph.D. First page of article [source] A Tissue-Specific Model of Reentry in the Right Atrial AppendageJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2009JICHAO ZHAO Ph.D. Introduction: Atrial fibrillation is prevalent in the elderly and contributes to mortality in congestive heart failure. Development of computer models of atrial electrical activation that incorporate realistic structures provides a means of investigating the mechanisms that initiate and maintain reentrant atrial arrhythmia. As a step toward this, we have developed a model of the right atrial appendage (RAA) including detailed geometry of the pectinate muscles (PM) and crista terminalis (CT) with high spatial resolution, as well as complete fiber architecture. Methods and Results: Detailed structural images of a pig RAA were acquired using a semiautomated extended-volume imaging system. The generally accepted anisotropic ratio of 10:1 was adopted in the computer model. To deal with the regional action potential duration heterogeneity in the RAA, a Courtemanche cell model and a Luo-Rudy cell model were used for the CT and PM, respectively. Activation through the CT and PM network was adequately reproduced with acceptable accuracy using reduced-order computer models. Using a train of reducing cycle length stimuli applied to a CT/PM junction, we observed functional block both parallel with and perpendicular to the axis of the CT. Conclusion: With stimulation from the CT at the junction of a PM, we conclude: (a) that conduction block within the CT is due to a reduced safety factor; and (b) that unidirectional block and reentry within the CT is due to its high anisotropy. Regional differences in effective refractive period do not explain the observed conduction block. [source] Focal Atrial Tachycardia Originating from the Left Atrial Appendage: Electrocardiographic and Electrophysiologic Characterization and Long-Term Outcomes of Radiofrequency AblationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 5 2007WANG YUN-LONG M.D. Introduction: This study sought to investigate electrophysiologic characteristics and radiofrequency ablation (RFA) in patients with focal atrial tachycardia (AT) arising from the left atrial appendage (LAA). Methods: This study included seven patients undergoing RFA with focal AT. Activation mapping was performed during tachycardia to identify an earlier activation in the left atria and the LAA. The atrial appendage angiography was performed to identify the origin in the LAA before and after RFA. Results: AT occurred spontaneously or was induced by isoproterenol infusion rather than programmed extrastimulation and burst atrial pacing in any patient. The tachycardia demonstrated a characteristic P-wave morphology and endocardial activation pattern. The P wave was highly positive in inferior leads in all patients. Lead V1 showed upright or biphasic (±) component in all patients. Lead V2,V6 showed an isoelectric component in five patients or an upright component with low amplitude (<0.1 mV) in two patients. Earliest endocardial activity occurred at the distal coronary sinus (CS) ahead of P wave in all seven patients. Mean tachycardia cycle length was 381 ± 34 msec and the earliest endocardial activation at the successful RFA site occurred 42.3 ± 9.6 msec before the onset of P wave. RFA was acutely successful in all seven patients. Long-term success was achieved in seven of the seven over a mean follow-up of 24 ± 5 months. Conclusions: The LAA is an uncommon site of origin for focal AT (3%). There were consistent P-wave morphology and endocardial activation associated with this type of AT. The LAA focal ablation is safe and effective. Long-term success was achieved with focal ablation in all patients. [source] Morphologic Characteristics of the Left Atrial Appendage, Roof, and Septum: Implications for the Ablation of Atrial FibrillationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2006WANWARANG WONGCHAROEN M.D. Introduction: The left atrium (LA) ablation in different regions, including LA appendage (LAA), LA roof, and LA septum, has recently been proposed to improve the success rate of treating patients with atrial fibrillation (AF). The purpose of this study was to investigate the anatomy of LAA, LA roof, and LA septum, using computed tomography (CT). Methods and Results: Multidetector CT scan was used to depict the LA in 47 patients with drug-refractory paroxysmal AF (39 males, age = 50 ± 12 years) and 49 control subjects (34 males, age = 54 ± 11 years). The area of LAA orifice, neck, and the length of roof line were greater in AF group than in control subjects. Three types of LAA locations and two types of LAA ridges were observed. Higher incidence of inferior LAA was noted in AF patients. The different morphologies of LA roof were described. Roof pouches were revealed in 15% of AF and 14% of controls. Moreover, we found septal ridge in 32% of AF and 23% of controls. Conclusions: Considerable variations of LAA and LA roof morphologies were demonstrated. Peculiar structures, including roof pouches and septal ridges, were delineated by CT imaging. These findings were important for determining the strategy of AF ablation and avoiding the procedure-related complications. [source] Characterization of spore appendages from Bacillus cereus strainsJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2001T. Stalheim Aims:,Further characterization and comparison of spore appendages from Bacillus cereus strains. Methods and Results:,Appendages were isolated from 10 B. cereus strains from the food industry and food-borne outbreaks. The appendage proteins were dissolved in sample buffer containing 2% SDS and 5% mercaptoethanol at 100°C, and subjected to SDS-PAGE. None of the appendages showed identical protein patterns. Western blots, using antibodies raised against a 3·5 kDa appendage protein, showed that the majority of the appendage proteins reacted with the antibody. Removal of the appendages by sonic treatment of the spores did not alter their heat resistance. The appendages were digested by proteinase K, pepsin, and the enzymes in the detergent Paradigm 10, but not by trypsin or chymotrypsin. Spore adhesion to stainless steel was scarcely affected by removal of the appendages. Digestion of adhered intact spores (with appendages) with Paradigm 10 showed a high degree of variation. Conclusions:,Spore appendages from B. cereus are complex proteinaceous structures that differ among strains. Significance and Impact of the Study:,Information about spore appendages and their involvement in spore adhesion is crucial for improving cleaning methods used for control of bacterial spores in the food industry. [source] Embryonic development of Galloisiana yuasai Asahina, with special reference to external morphology (Insecta: Grylloblattodea)JOURNAL OF MORPHOLOGY, Issue 2 2005Toshiki Uchifune Abstract The embryogenesis of Grylloblattodea, one of the most primitive of the polyneopteran orders, is described using Galloisiana yuasai with special reference to external morphology. The egg membranes are characterized by an endochorion crossed by numerous vertical aeropyles and a fairly thin vitelline membrane, features shared by Mantophasmatodea. The inner layer formation is of the fault type. Serosal elements in the amnioserosal fold differentiate into hydropylar cells, to function in water absorption together with specialized amniotic structures, i.e., an amniotic strand and a thickened amnion. The germ band is of the short germ type. The germ band immerses deep into the yolk after its full elongation along the egg surface, and in this respect blastokinesis closely resembles that of Mantophasmatodea. The embryological features, i.e., those on egg membranes and blastokinesis, may suggest a closer affinity of Grylloblattodea and Mantophasmatodea. Appendages, ectodermal invaginations, and sternal and pleural sclerites are discussed in the light of serial homology, to provide a new basis for elucidating the insect body plan. Appendages are divided into the proximal coxopodite and distal telopodite, the former being divided further into the subcoxa and coxa. Subcoxal and coxal elements are identified in the mandible as well as in the abdominal appendages. The subcoxa is divided into the epimeron and episternum by the pleural suture in thoracic segments. Likewise, in the abdominal segments the subcoxa is divided into two, although the homologs of the epimeron and episternum are not sclerotized, and in the labial segment the subcoxal derivative or the postmentum is divided into the submentum and mentum. Two coxal endites bulge out from the medial side of the gnathal appendages. The mandibular molar and incisor, maxillary lacinia and galea, and labial glossa and paraglossa are serially homologous with each other. In the thoracic segments the original embryonic sternum or "protosternum" is largely replaced by subcoxal elements, and merely remains as a small anterior presternum and a posterior spinasternum. A major part of the venter is represented by the derivatives of the episternum such as an extensive basisternum, katepisternum, and trochantin and the medial element of the epimeron. The pleuron is derived from the episternal elements or the anepisternum and preepisternum, which bears a spiracle in the mesothorax and metathorax, and the lateral element of the epimeron. The homolog of the preepisternum in the prothorax is the cervical sclerite, but with no spiracle developed. A median ventral invagination arises in the thoracic segments as a spina, and the homolog of the spina develops into the eversible sac in the first abdominal segment. J. Morphol. © 2005 Wiley-Liss, Inc. [source] Coronary Artery Fistulas: A Review of the Literature and Presentation of Two Cases of Coronary Fistulas with Drainage into the Left AtriumCONGENITAL HEART DISEASE, Issue 3 2007Scott Ceresnak MD Abstract We report 2 cases of infants presenting with a murmur shortly after birth and diagnosed with coronary artery fistulas with drainage into the left atrium. The first infant had a fistulous communication between the left main coronary artery and the left atrial appendage and presented with signs and symptoms of heart failure. The infant was repaired surgically in the first week of life. The second infant was asymptomatic and had a fistulous communication between the right coronary artery and the left atrium. The infant will have the fistula closed in the cardiac catheterization laboratory when the child is older. The literature on coronary artery fistulas is reviewed, and the diagnosis and management of coronary artery fistulas is discussed. [source] Cor Triatriatum Sinister with and without Left Ventricular Inflow Obstruction: Visualization of the Entire Supravalvular Membrane by Real-time Three-dimensional Echocardiography.CONGENITAL HEART DISEASE, Issue 6 2006Impact on Clinical Management of Individual Patient ABSTRACT We present 4 cases of cor triatriatum in whom the diagnosis was correctly made by 2-dimensional transthoracic echocardiography, which showed the supravalvular left atrial membrane that divides the left atrium into 2 chambers. The pulmonary veins were connected normally to the proximal left atrial chamber and the left atrial appendage was connected to the distal left atrial chamber. In 1 patient there was evidence of severe pulmonary venous obstruction to the mitral valve by Doppler examination, while in the other three, there was no venous obstruction. Patients were then examined by real-time 3-dimensional echocardiography (RT3DE, using ×4 matrix array transducer connected to Sonos 7500 echocardiographic system Phillips, Andover, Mass, USA). This showed the exact morphology of the membrane and led to cancellation of planed surgical intervention in 1 case in which the membrane was only a broad band crossing the left atrial cavity. In addition to delineating the exact morphology of the intracavitary anomaly, this novel echocardiographic imaging modality should be an additive tool to better understand the natural history of these nonobstructive left atrial membranes via longitudinal follow-up of these patients. [source] CULTURALLY-FOCUSED BATTERER COUNSELING FOR AFRICAN-AMERICAN MEN,CRIMINOLOGY AND PUBLIC POLICY, Issue 2 2007EDWARD W. GONDOLF Research Summary: Clinicians and researchers have strongly recommended culturally-focused counseling with African-American men arrested for domestic violence. An experimental clinical trial tested the effectiveness of this approach against conventional cognitive-behavioral counseling in all-African-American groups and in racially-mixed groups (N = 501). No significant difference was found in the reassault rate reported by the men's female partners over a 12-month follow-up period (23% overall). During that period, men in the racially-mixed groups were, moreover, half as likely to be rearrested for domestic violence as the men in the culturally-focused groups. The men's level of racial identification did not significantly affect the outcomes of the counseling options. Policy Implications: Simply adding a culturally-focused counseling group to domestic violence programs does not seem in itself to improve outcomes. In the current study, the culturally-focused counseling was an appendage to an existing agency closely linked to the criminal justice system. Culturally-focused counseling may prove to be more effective within community-based organizations tied to local services and supports. [source] Unusual Left Atrial Appendage Mass: Atypical Presentation of Papillary FibroelastomaECHOCARDIOGRAPHY, Issue 5 2008Miroslawa Jablonski-Cohen M.D. Papillary fibroelastomas are small, histologically benign neoplasms that are typically found on the valvular endocardium. We report a patient with a papillary fibroelastoma in an unusual location: the left atrial appendage. Although the mass was visualized both by computed tomography (CT) and transesophageal echocardiography, the diagnosis was histologically confirmed after surgical excision. [source] Role of Echocardiography in Percutaneous Occlusion of the Left Atrial AppendageECHOCARDIOGRAPHY, Issue 4 2007Mráz M.D. Percutaneous occlusion of the left atrial appendage (LAA) is a modern alternative for the treatment of patients with atrial fibrillation (AF) and with a high risk of stroke who are not eligible for long-term anticoagulation therapy. Echocardiography plays a significant role in selecting patients, guiding the procedure, and in the postprocedural follow-up. Objectives and methods: To test the role of transesophagoeal echocardiography (TEE) and intracardiac echocardiography (ICE) in facilitating and shortening the procedure. Results: ICE represents a more convenient approach in patients who are not under generally anesthesia and helps to facilitate transseptal puncture. On the other hand, TEE, having the ability to rotate the image plane, helps to better determine the position of the occluder. Conclusions: Echocardiographic guidance of this procedure is essential. Which approach will be preferred will depend on the development of these two methods. [source] Relationship between Slow Coronary Flow and Left Atrial Appendage Blood Flow VelocitiesECHOCARDIOGRAPHY, Issue 1 2007Recep Demirbag M.D. Aims: This study was undertaken to assess whether slow coronary flow (SCF)is related to low left atrial appendage (LAA) blood flow velocities. Methods: Study subjects consist of 44 patients with SCF and 11 volunteer subjects with normal coronary angiogram. The diagnosis of SCF was made using the TIMI frame count method. The blood flow velocities were obtained by placing a pulsed-wave Doppler sample volume inside the proximal third of the LAA. Results: The mean LAA emptying velocities (MEV)were significantly lower in patients than control subjects (34.5 ± 9.9 cm/sec vs 84.0 ± 12.1 cm/sec; P < 0.001). In bivariate analysis, significant correlation was found between MEV, and systolic pulmonary venous flow, mean TIMI frame count, deceleration time, and isovolumetric relaxation time (P < 0.05). By multiple linear regression analysis, mean TIMI frame count (ß=,0.865, P < 0.001) was identified as independent predictors of MEV. Conclusion: This study indicates that SCF phenomenon may be related to low LAA blood flows. [source] The Use of Anatomic M-Mode Echocardiography to Determine the Left Atrial Appendage Functions in Patients with Sinus RhythmECHOCARDIOGRAPHY, Issue 2 2005Yekta Gurlertop M.D. Left atrial appendage (LAA) contractile dysfunction is associated with thrombus formation and systemic embolism. LAA function is determined by its flow velocities and fractional area change. This study was performed in order to determine the LAA functions with the anatomic M-mode echocardiography (AMME). Our study comprised 74 patients who had sinus rhythm and underwent transesophageal echocardiography (TEE) for various reasons. LAA fractional change (LAAFAC) was measured by manual planimetry in a transverse basal short-axis approach and LAA emptying and filling velocities also were measured. The AMME values were determined by an M-mode cross section from a cursor placed beneath the orifice of the LAA in transverse basal short-axis imaging. From these values LAA fractional shortening (LAAFS) and ejection fraction (LAAEF) were calculated. LAAEF was calculated by the Teicholz method. The comparisons were conducted, and no correlations between the LAA late filling and the anatomic M-mode values were found (for LAAFS r = 0.18; P > 0.05 and for LAAEF r = 0.19; P > 0.05). There were significant but poor correlations among the LAA late emptying with the anatomic M-mode measurements (for LAAFS r = 0.26; P < 0.05 and for LAAEF r = 0.30; P < 0.01), whereas, there were significant and good correlations between the LAAFAC and the anatomic M-mode values (for LAAFS r = 0.75; P < 0.01 and for LAAEF r = 0.78; P < 0.01). There were significant differences between the valvular heart disease group and the normal group, and between the valvular heart disease group and the ASD group (for LAAFAC P < 0.01, for LAAEF P < 0.01, for LAAFS P < 0.01). There was no difference between the normal group and the ASD group. Our study showed that the LAAEF and LAAFS in patients with sinus rhythm obtained via anatomical M-mode echocardiography is a new method, which can be used instead of left atrial appendage area change. [source] Course of Intraatrial Thrombi Resolution Using Transesophageal EchocardiographyECHOCARDIOGRAPHY, Issue 2 2003Jennifer A. Larsen M.D. Thromboembolic events are associated with atrial fibrillation and with cardioversion to sinus rhythm. Although studies have demonstrated the risk of this complication is reduced by a 3-week period of anticoagulation prior to cardioversion, limited data have suggested a longer period of anticoagulation is necessary for thrombus resolution. We identified and followed 25 patients noted to have intraatrial thrombi on an initial transesophageal echocardiogram (TEE) who subsequently had a follow-up TEE. The majority of patients had a single thrombus, often but not uniformly located in the left atrial appendage with the largest found in those patients with mitral stenosis. Repeat TEE was performed at a mean of 4 ± 6 months and persistent thrombus was noted in 19 of 25 patients (76%). Seven of 19 patients with persistent thrombi were cardioverted and one of these patients had a neurologic event following the procedure (14%). The only findings associated with persistent thrombus were the presence of mitral valve disease and atrial fibrillation.. Our findings suggest that intraatrial thrombi do not generally resolve following several weeks of anticoagulation and that persistent left-sided intraatrial thrombi may be associated with an increased risk for events following cardioversion. Given that a TEE-guided approach to cardioversion is being utilized more frequently, it may be important to determine thrombus characteristics on follow-up that would be predictive of embolic events following cardioversion. (ECHOCARDIOGRAPHY, Volume 20, February 2003) [source] Effect of Inotropic Stimulation on Left Atrial Appendage Function in Atrial Myopathy of Chronic Atrial FibrillationECHOCARDIOGRAPHY, Issue 4 2000MASOOR KAMALESH M.D. Atrial fibrillation (AF) leads to remodeling of the left atrium (LA) and left atrial appendage (LAA), resulting in atrial myopathy. Reduced LA and LAA function in chronic AF leads to thrombus formation and spontaneous echo contrast (SEC). The effect of inotropic stimulation on LAA function in patients with chronic AF is unknown. LAA emptying velocity (LAAEV) and maximal LAA area at baseline and after dobutamine were measured by transesophageal echocardiography in 14 subjects in normal sinus rhythm (NSR) and 6 subjects in AF. SEC in the LA was assessed before and after dobutamine. LAAEV increased significantly in both groups. However, the LAAEV at peak dobutamine in patients with AF remained significantly lower than the baseline LAAEV in patients who were in NSR (P= 0.009). Maximal LAA area decreased significantly with dobutamine in both groups, but LAA area at peak dose of dobutamine inpatients with AF remained greater than baseline area in those in NSR (P= 0.01). Despite the increase in LAAEV, SEC improved in only two of five patients. We conclude that during AF, the LAA responds to inotropic stimulation with only a modest improvement in function. [source] An Efficient Asymmetric Synthesis of 2-Substituted 1,4-Benzodiazepin-3-one as a Potential Molecular ScaffoldEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 8 2005Nuria Cabedo Abstract 2-Substituted 1,4-benzodiazepine-2-one compounds (9,12) were obtained by a highly diastereoselective alkylation of a seven-membered ring benzolactam (8) in the presence of (R)-phenylglycinol as a chiral inductor. The corresponding acid derivative (16) afforded a conformationally constrained structure suitable for preparing peptidomimetic analogues useful as a novel molecular scaffold. After cleavage of the chiral appendage this approach might also lead efficiently to enantiomerically pure 2-substituted benzodiazepines (15). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] The pre-radial history of echinodermsGEOLOGICAL JOURNAL, Issue 3 2005Andrew B. Smith Abstract Gene sequence data now identify a robust phylogeny of deuterostomes and provide a framework within which the evolution of echinoderms can be interpreted. The topology of the molecular tree makes a number of important predictions about the morphological characters of the earliest echinoderm at its split from hemichordates: it possessed gill slits (but not a notochord), had a bilaterally symmetrical body plan in the adult and, less certainly, underwent torsion during development. Carpoids, a highly contentious group of extinct deuterostomes with a plated calcite skeleton that have variously been interpreted as stem- and crown-group chordates, stem-group echinoderms or stem- and crown-group echinoderms, display many of these basal characters and provide critical evidence for how the latest common ancestor of hemichordates and echinoderms was transformed into a pentaradiate crown-group echinoderm. Cinctans have a large atrial opening in addition to mouth and anus, and are interpreted as pharyngeal basket feeders. The paired grooves associated with the mouth indicate the presence of a hydrovascular system, but not necessarily one built along the echinoderm plan (that is, derived from just the left hydrocoel). Stylophorans have a bilateral body plan that is externally masked by torsion and possess gills, either unpaired and external, or paired and internal, opening into an atrial cavity. Their bilateral appendage is a locomotory organ, not an ambulacrum, and there is no evidence that stylophorans ever possessed a well-developed hydrovascular system homologous to the water vascular system of echinoderms and the tentacles of pterobranch hemichordates. Solutes are the most crownward, having a true echinodermal ambulacral system with a single hydropore and no pharyngeal gill openings. Copyright © 2005 John Wiley & Sons, Ltd. [source] , -Peptide Conjugates: Syntheses and CD and NMR Investigations of ,/, -Chimeric Peptides, of a DPA- , -Decapeptide, and of a PEGylated , -HeptapeptideHELVETICA CHIMICA ACTA, Issue 12 2009James Gardiner Abstract ,3 -Peptides consisting of six, seven, and ten homologated proteinogenic amino acid residues have been attached to an , -heptapeptide (all d- amino acid residues; 4), to a hexaethylene glycol chain (PEGylation; 5c), and to dipicolinic acid (DPA derivative 6), respectively. The conjugation of the , -peptides with the second component was carried out through the N-termini in all three cases. According to NMR analysis (CD3OH solutions), the (M)- 314 -helical structure of the , -peptidic segments was unscathed in all three chimeric compounds (Figs.,2, 4, and 5). The , -peptidic section of the ,/, -peptide was unstructured, and so was the oligoethylene glycol chain in the PEGylated compound. Thus, neither does the appendage influence the , -peptidic secondary structure, nor does the latter cause any order in the attached oligomers to be observed by this method of analysis. A similar conclusion may be drawn from CD spectra (Figs.,1, 3, and 5). These results bode well for the development of delivery systems involving , -peptides. [source] Primitive immune systems: Are your ways my ways?IMMUNOLOGICAL REVIEWS, Issue 1 2004Baruch Rinkevich Summary:, Although vertebrate immune systems have been commonly conceived as exquisitely developed to combat pervasiveness by pathogens, they are not infallible. The enigmatic expression of histocompatibility in vertebrates, the manifestation of natural chimerism, autoimmunity, malignancy, and other puzzling outcomes hint that immunity did not arise in evolution to fight infections and that this capacity is a late evolutionary appendage, owing its appearance to the redeployment of a system developed for other reasons. Allorecognition in the colonial tunicate Botryllus schlosseri serves here as a platform for a contending paradigm, advocating that immunity has developed as a surveillance machinery against and for purging of nascent selfish cells (stemmed from a kin organism or from transformed cells within the organism of origin). Defense against pathogens (always representing xenogeneic aliens) appeared later, revealing the multiplicity of newly developed phenomena. Allorecognition events characteristic of the Botryllus primitive immune system, such as fusion versus rejection, the morphological resorption with its expressed hierarchy, and the somatic/germ-cell parasitic outcomes, provide clues to the evolutionary basis of allorecognition. Recent work on Botryllus immunity that highlights the cost of littering individuality by somatic variants/allogeneic cells is discussed. [source] Manoeuvring and vibration reduction of a flexible spacecraft integrating optimal sliding mode controller and distributed piezoelectric sensors/actuatorsINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 6 2007Qinglei Hu Abstract This investigation is to apply optimal sliding mode (OSM) control theory and distributed piezoelectric sensor/actuator technology to vibration control of a flexible spacecraft. An approximate analytical dynamic model of a slewing flexible spacecraft with surface-bonded piezoelectric sensors/actuators is developed using Hamilton's principle with discretization by assumed model method. To satisfy pointing requirements and simultaneously suppress vibration, two separate control loops are adopted. The first uses the piezoceramics as sensors and actuators to actively suppress certain flexible modes by designing a positive position feedback (PPF) compensators that add damping to the flexible structures in certain critical modes in the inner feedback loop; then a second feedback loop is designed using OSM control to slew the spacecraft. The OSM controller minimizes the expected value of a quadratic objective function consisting of only the states with the constraints that the error states always remain on the intersection of sliding surfaces. The advantage in this method is that the vibration reduction and attitude control are achieved separately in the two separate feedback loops, allowing the pointing requirements and simultaneous vibrations suppression to be satisfied independently of one another. An additional attraction of the design method is that the selection of PPF gain is determined by introducing a cost function to be minimized by the feedback gains which are subject to the stability criterion at the same time, such that the feedback gains are selected in a more systematical way to avoid the arbitrary selecting of feedback gains. The proposed control strategy has been implemented on a flexible spacecraft, which is a hub with a cantilever flexible beam appendage and can undergo a single axis rotation. Both analytical and numerical results are presented to show the theoretical and practical merits of this approach. Copyright © 2006 John Wiley & Sons, Ltd. [source] A Symmetry-Based Synthesis of the Heterobicyclic Core of the Zaragozic Acids/SqualestatinsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2009Yuzhou Wang Abstract The pseudo C2 -symmetrical diketone 22 was efficiently constructed from furan-3,4-dimethanol (7) using a two-directional route featuring a double asymmetric dihydroxylation. Acidic hydrolysis of the cyclopentylidene acetals of 22 triggered a selective cyclization of the resulting hexaol diketone to generate the 2,8-dioxabicyclo[3.2.1]octane core of the zaragozic acids/squalestatins. Chemoselective oxidative cleavage of a superfluous two-carbon appendage and further functional group manipulations yielded the enantiomerically pure triester 30, which offers itself as a general heterobicyclic building block for naturally occurring zaragozic acids/squalestatins and unnatural analogues. [source] Highly Enantioselective Biphasic Iminium-Catalyzed Epoxidation of Alkenes.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2009On the Importance of the Counterion, of N(sp2)C(sp3) Rotamers Abstract Diastereomeric biaryliminium cations made of an (Ra)-5,5,,6,6,,7,7,,8,8,-octahydrobinaphthyl core and exocyclic appendages derived from (S)- or (R)-3,3-dimethylbutan-2-amine are effective asymmetric epoxidation catalysts for unfunctionalized alkenes. Herein, we report that the negative counterion of the iminium salts has to be chosen wisely. While the hexafluoroantimonate anion [SbF6,] is optimal for reliable results, one has to be careful about other anions and tetraphenylborate [BPh4,] in particular. We also detail that the so far unexplained "lack" of stereochemical control from the chiral exocyclic appendage in this type of catalysts is due to the existence of atropisomers around the N(sp2)C(sp3) bond that links the azepinium core to the exocyclic stereocenter. Finally, we develop a general model to predict with certainty the high selectivity in the formation of non-racemic epoxides of defined absolute configuration. [source] Cardiac Hemangioma of the Left Atrial Appendag: A Case Report and DiscussionJOURNAL OF CARDIAC SURGERY, Issue 5 2009Bruno Chiappini M.D., Ph.D. In contrast to myxoma, hemangioma rarely involves left atrial tissue in adults and little information about the tumor is available. We encountered a 65-year-old woman with a left atrial hemangioma arising in the appendage and growing like an extracardiac mass. The tumor was removed from the left atrium with all the left appendage under cardiopulmonary bypass. Histopathological examination revealed that it was a cavernous-type hemangioma. Among the five described cases, this case was the only one in which the tumor arose from the appendage and grew into the pericardial cavity with resultant paroxystic atrial fibrillation. [source] Surgical Ablation of Atrial Fibrillation: The Columbia Presbyterian ExperienceJOURNAL OF CARDIAC SURGERY, Issue 5 2006Veli K. Topkara M.D. However, it is not widely applied due to its complexity, increased operative times, and the risk of bleeding. Various energy sources have been introduced to simplify the traditional "cut and sew" approach. Methods: This study involves patients undergoing surgical atrial fibrillation ablation (SAFA) at a single institution from 1999 to 2005. Type of concomitant procedures, preoperative clinical characteristics, and chronicity of AF were evaluated in overall patient population. Parameters including surgical approach, lesion pattern, and energy source used were collected intraoperatively. Clinical outcomes examined were postoperative rhythm success, stroke, early mortality, and long-term survival. Results: Three hundred thirty-nine patients were identified. Three hundred twenty-eight (96.8%) patients had associated cardiac disease and underwent concomitant procedures; 75.8% of patients had persistent AF. Energy sources used were microwave (49.8%), radiofrequency (42.2%), and laser (8.0%). In 41.9% of cases a pulmonary vein encircling lesion was the only lesion created. Combination lesion sets were performed in the remaining cases. Rhythm success rates at 3, 6, 12, and 24 months were 74.1%, 68.2%, 74.5%, and 71.1%, respectively. Patients who underwent surgical removal of left atrial appendage by means of stapling or simple excision had no early postoperative stroke. Early mortality was 4.9%. Postoperative survival rates at 1, 3, and 5 years were 89.6%, 83.1%, and 78.0%. Conclusions: Surgical ablation of atrial fibrillation is a safe and effective procedure in restoring sinus rhythm with excellent postoperative survival rates. Further advancements in the field will eventually result in minimally invasive procedures with higher success rates. [source] Robot-Assisted Isolation of the Pulmonary Veins with Microwave EnergyJOURNAL OF CARDIAC SURGERY, Issue 1 2006F.A.C.S., J. Michael Smith M.D. This study evaluated the feasibility of performing a minimally invasive left atrial isolation on a beating heart using the da Vinci Robotic Surgical System and a flexible microwave probe (Flex 10 by AFx, Inc., Fremont, CA, USA), and the reliability of exit block pacing to confirm transmurality of the lesions created. Methods: On six canines, the Flex 10 probe was passed around the left atrium posterior to the superior vena cava, through the transverse sinus, and back through the oblique sinus via a right-chest-only approach using the da Vinci Robotic Surgical System. Prior to ablation, pacing outside the atrial cuff was confirmed. Ablation was then carried out on the beating heart and repeated (as needed) until electrical isolation was demonstrated by exit block pacing. Probe position was confirmed at the completion of the procedure via sternotomy. Analysis included acute histologic and gross examination of the targeted area. Results: There was no significant difference (p = 0.110) in procedure time, although it decreased 39.6% from the first three cases to the last three cases. Electrical evidence of electrical left atrial isolation was achieved in all subjects. Acute histologic examination confirmed transmurality inconsistently. Additionally, in two animals, the Flex 10 probe was found to be anterior to the left atrial appendage. All animals survived the procedure. Conclusion: A minimally invasive left atrial isolation procedure using monopolar microwave energy with the da Vinci Robotic Surgical System is simple and feasible. However, despite creating an electrical block, transmurality was not demonstrated consistently and further confirmation of catheter positioning is necessary during a right-chest-only approach. [source] Left Superior Vena Cava Draining into the Left Atrium, Associated with Partial Anomalous Pulmonary Venous Connection: Surgical CorrectionJOURNAL OF CARDIAC SURGERY, Issue 4 2005Andrea Quarti M.D. Although intra-atrial rerouting techniques, in patients with no connecting vein, have proved to be reliable and successful, in many cases the extracardiac repair is preferable. We report a case of a 5-month-old patient with a not connected left superior vena cava draining into the left atrium, associated with atrial septal defect and partial anomalous pulmonary venous connection. The correction has been achieved by rerouting the pulmonary venous return into the left atrium and by transposition of the left vena cava on the right appendage. [source] Left Atrial Appendage Tip: An Unusual Site of Successful Ablation After Failed Endocardial and Epicardial Mapping and AblationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 2 2010LUIGI DI BIASE M.D. Left Atrial Appendage Tip. Uncommon sites of ablation for arrhythmias can be the cause of failed ablations. This series includes 4 cases requiring ablation at the tip of the left atrial appendage after both endocardial and epicardial mapping and ablation failed. (J Cardiovasc Electrophysiol, Vol. 21, pp. 203-206, February 2010) [source] | |||||||||||||||||||||||||||||||||||||