RESUMO
BACKGROUND: The effectiveness trial "Stress echo (SE) 2020" evaluates novel applications of SE in and beyond coronary artery disease. The core protocol also includes 4-site simplified scan of B-lines by lung ultrasound, useful to assess pulmonary congestion. PURPOSE: To provide web-based upstream quality control and harmonization of B-lines reading criteria. METHODS: 60 readers (all previously accredited for regional wall motion, 53 B-lines naive) from 52 centers of 16 countries of SE 2020 network read a set of 20 lung ultrasound video-clips selected by the Pisa lab serving as reference standard, after taking an obligatory web-based learning 2-h module ( http://se2020.altervista.org ). Each test clip was scored for B-lines from 0 (black lung, A-lines, no B-lines) to 10 (white lung, coalescing B-lines). The diagnostic gold standard was the concordant assessment of two experienced readers of the Pisa lab. The answer of the reader was considered correct if concordant with reference standard reading ±1 (for instance, reference standard reading of 5 B-lines; correct answer 4, 5, or 6). The a priori determined pass threshold was 18/20 (≥ 90%) with R value (intra-class correlation coefficient) between reference standard and recruiting center) > 0.90. Inter-observer agreement was assessed with intra-class correlation coefficient statistics. RESULTS: All 60 readers were successfully accredited: 26 (43%) on first, 24 (40%) on second, and 10 (17%) on third attempt. The average diagnostic accuracy of the 60 accredited readers was 95%, with R value of 0.95 compared to reference standard reading. The 53 B-lines naive scored similarly to the 7 B-lines expert on first attempt (90 versus 95%, p = NS). Compared to the step-1 of quality control for regional wall motion abnormalities, the mean reading time per attempt was shorter (17 ± 3 vs 29 ± 12 min, p < .01), the first attempt success rate was higher (43 vs 28%, p < 0.01), and the drop-out of readers smaller (0 vs 28%, p < .01). CONCLUSIONS: Web-based learning is highly effective for teaching and harmonizing B-lines reading. Echocardiographers without previous experience with B-lines learn quickly.
Assuntos
Ecocardiografia sob Estresse/normas , Pulmão/diagnóstico por imagem , Edema Pulmonar/diagnóstico , Controle de Qualidade , Feminino , Humanos , Internet , Masculino , Pessoa de Meia-IdadeRESUMO
Crohn's disease results in a hypercoagulable state increasing the risk of venous or arterial thromboembolism. Cardiac involvement has not been routinely identified. Two cases are presented to illustrate that patients with Crohn's disease may represent an exception to the rule that left ventricular apical thrombus should be associated with an underlying wall motion abnormality and reduction in left ventricular ejection fraction.
Assuntos
Trombose Coronária/patologia , Doença de Crohn/patologia , Função Ventricular Esquerda/fisiologia , Adolescente , Adulto , Feminino , Ventrículos do Coração/patologia , Humanos , Imageamento por Ressonância Magnética , MasculinoRESUMO
OBJECTIVE: The purpose of this study was to determine whether resting myocardial deformation and rotation may be altered in diabetic patients with significant epicardial coronary artery disease (CAD) with normal left ventricular ejection fraction. DESIGN: A prospective observational study. SETTING: Diagnosis of epicardial CAD in patients with diabetes. PATIENTS AND METHODS: Eighty-four patients with diabetes suspected of epicardial CAD scheduled for cardiac catheterization had a resting echocardiogram performed prior to their procedure. Echocardiographic measurements were compared between patients with and without significant epicardial CAD as determined by cardiac catheterization. MAIN OUTCOME MEASURES: Measurement of longitudinal strain, strain rate, apical rotation, and rotation rate, using speckle tracking echocardiography. RESULTS: Eighty-four patients were studied, 39 (46.4%) of whom had significant epicardial CAD. Global peak systolic apical rotation was significantly increased (14.9 ± 5.1 vs. 11.0 ± 4.8 degrees, P < 0.001) in patients with epicardial CAD along with faster peak systolic apical rotation rate (90.4 ± 29 vs. 68.1 ± 22.2 degrees/sec, P < 0.001). These findings were further confirmed through multivariate logistic regression analysis (global peak systolic apical rotation OR = 1.17, P = 0.004 and peak systolic apical rotation rate OR = 1.05, P < 0.001). CONCLUSIONS: Patients with diabetes with significant epicardial CAD and normal LVEF exhibit an increase in peak systolic apical counterclockwise rotation and rotation rate detected by echocardiography, suggesting that significant epicardial CAD and its associated myocardial effects in patients with diabetes may be detected noninvasively at rest.
Assuntos
Doença da Artéria Coronariana/diagnóstico por imagem , Doença da Artéria Coronariana/epidemiologia , Complicações do Diabetes/diagnóstico por imagem , Complicações do Diabetes/epidemiologia , Ecocardiografia/estatística & dados numéricos , Ventrículos do Coração/diagnóstico por imagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Comorbidade , Ecocardiografia/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prevalência , Reprodutibilidade dos Testes , Fatores de Risco , Rotação , Sensibilidade e Especificidade , Estados Unidos/epidemiologiaRESUMO
BACKGROUND: In large necropsy studies dissecting intramyocardial hematoma (DIH) with serpiginous tracts across the myocardial fibers has been reported in both the septum and the left ventricle free wall. METHODS: We studied 15 patients admitted to the hospital with acute myocardial infarction (AMI) in which DIH was demonstrated by either transthoracic and/or transesophageal and confirmed intraoperatively or by necropsy. RESULTS: In nine patients the hemorrhagic dissection was predominantly in the septum and in the remaining it was in the free wall of the left ventricle (LV). Myocardial infarction involved the left ventricular inferior wall in two, and the anterior wall in 13 patients. The overall mortality was 47%, and in the group with septal hematoma it reached to 78%. Echocardiography disclosed the various acoustic densities of the evolving intramyocardial hematoma, its extension through the hemorrhagic dissection, its spontaneous reabsorption, as well as its communication with the ventricular cavities. CONCLUSIONS: Echocardiography is the method of choice for the noninvasive diagnosis of patients with suspected myocardial rupture and intramyocardial dissection postmyocardial infarction.
Assuntos
Ecocardiografia/métodos , Aneurisma Cardíaco/diagnóstico por imagem , Ruptura Cardíaca Pós-Infarto/diagnóstico por imagem , Hematoma/diagnóstico por imagem , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
BACKGROUND: The trial "Stress Echo (SE) 2020" evaluates novel applications of SE beyond coronary artery disease. The aim of the study was control quality and harmonize reading criteria. METHODS: One reader from 78 centers of the SE 2020 network asked for credentials to read a set of 20 SE video-clips selected by the core lab. All aspiring centers met the pre-requisite of high-volume and the years of experience in SE ranged from 5 to 31years (mean value 18years). The diagnostic gold standard was a reading by the core lab. The a priori determined pass threshold was 18/20 (≥90%). RESULTS: Of the initial 78 who started, 57 completed the first attempt: individual readers' score on first attempt ranged from 07/20 to 20/20 (accuracy from 35% to 100%, mean 78.7±13%) and 44 readers passed it. There was a very poor correlation between years of experience and the reader's score on first attempt (r=-0.161, p=0.231). Of the 13 readers who failed the first attempt, 12 took it again after the web-based session and their accuracy improved (74% vs. 96%, p<0.001). The kappa inter-observer agreement before and after web-based training was 0.59 on first attempt and rose to 0.91 on the last attempt. CONCLUSIONS: In SE reading, the volume of activity or years of experience is not synonymous with diagnostic quality. Qualitative analysis and operator-dependence can become a limiting weakness in clinical practice, in the absence of strict pathways of learning, credentialing and audit.
Assuntos
Cardiologistas/normas , Competência Clínica/normas , Doença das Coronárias/diagnóstico por imagem , Ecocardiografia sob Estresse/normas , Controle de Qualidade , Doença das Coronárias/epidemiologia , Ecocardiografia sob Estresse/métodos , Humanos , Internacionalidade , Reprodutibilidade dos TestesRESUMO
Agitated saline contrast studies (bubble studies) can be performed with either transthoracic or transesophageal echocardiography for the detection of right-to-left atrial shunts. The echocardiograms of 94 consecutive patients who underwent saline contrast studies with transthoracic and transesophageal approaches were reviewed to compare the ability of these modalities to detect right-to-left atrial shunts.
Assuntos
Meios de Contraste , Ecocardiografia Transesofagiana , Ecocardiografia , Comunicação Interatrial/diagnóstico por imagem , Cloreto de Sódio , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Microbolhas , Pessoa de Meia-Idade , Sensibilidade e EspecificidadeRESUMO
Accessory mitral valve is a rare congenital abnormality and is an unusual cause for subvalvular left ventricular outflow tract (LVOT) obstruction. It is detected first in children and is very rarely noticed in adults. The most common clinical presentation is symptomatic LVOT obstruction. We present a case series of 5 adult patients with varying clinical presentations in which the accessory mitral valve was diagnosed using echocardiography. Three patients presented with varying degrees of symptomatic LVOT obstruction, one presented with recurrent transient ischemic attack and stroke, and one patient was incidentally diagnosed during echocardiography to exclude endocarditis. Accessory mitral valve should be suggested in patients with LVOT obstruction.
Assuntos
Valva Mitral/anormalidades , Valva Mitral/diagnóstico por imagem , Obstrução do Fluxo Ventricular Externo/etiologia , Adulto , Feminino , Sopros Cardíacos , Humanos , Masculino , Pessoa de Meia-Idade , Valva Mitral/cirurgia , Isquemia Miocárdica/etiologia , Recidiva , Acidente Vascular Cerebral/etiologia , Ultrassonografia , Obstrução do Fluxo Ventricular Externo/diagnósticoRESUMO
To determine the prevalence of left ventricular diastolic dysfunction in asymptomatic, normotensive patients with type 2 diabetes mellitus, we studied 61 consecutive normotensive patients with type 2 diabetes using conventional Doppler echocardiography at rest (deceleration time, isovolumic relaxation time, early diastolic velocity [E]/peak atrial systolic velocity [A] ratio), and during the Valsalva maneuver. In addition, mitral annular velocity and velocity of flow propagation were assessed in all patients using tissue Doppler imaging (TDI) and color M-mode echocardiography. A standard resting echocardiogram excluded significant valvular disease and stress echocardiography excluded significant coronary artery disease in those with diastolic dysfunction. Diastolic dysfunction was found in 43 of 57 patients (75%) when all of the above echocardiographic techniques were used. TDI detected diastolic dysfunction more often (63%) than any other echocardiographic approach. Thus, the prevalence of left ventricular diastolic dysfunction in asymptomatic, normotensive patients with type 2 diabetes without significant coronary artery disease is much higher than previously suspected. TDI markedly improved the echocardiographic detection of diastolic dysfunction in asymptomatic patients with type 2 diabetes.
Assuntos
Diabetes Mellitus Tipo 2/diagnóstico por imagem , Diabetes Mellitus Tipo 2/fisiopatologia , Diástole/fisiologia , Manobra de Valsalva/fisiologia , Disfunção Ventricular Esquerda/diagnóstico por imagem , Disfunção Ventricular Esquerda/fisiopatologia , Adulto , Pressão Sanguínea/fisiologia , Ecocardiografia Doppler em Cores , Ecocardiografia sob Estresse , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prevalência , Disfunção Ventricular Esquerda/epidemiologiaRESUMO
Automated border-detection techniques such as acoustic quantification have proven accurate and useful for quantifying left ventricular (LV) function. We acquired LV acoustic quantification waveforms from the parasternal short-axis window in 140 healthy patients in the age range of 16 to 78 years. Signal-averaged waveforms were analyzed for parameters of systolic and diastolic performance. The average fractional area change was 54 +/- 12%, and there were no significant changes in LV systolic function in the age range studied. There were significant changes in diastolic parameters with aging. The percentage of contribution to total LV filling occurring during atrial filling nearly tripled during the 6 decades studied, from 13% in the youngest cohort to 36% in the eighth decade of life. This study provides normal reference values for systolic and diastolic parameters of LV function determined from signal-averaged acoustic quantification waveforms acquired from the parasternal short-axis view in adult and adolescent patients over a wide age range.
Assuntos
Diástole/fisiologia , Sístole/fisiologia , Função Ventricular Esquerda , Adolescente , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valores de Referência , Volume SistólicoRESUMO
The need for more objectively quantifiable evaluation of the left ventricular function, obtainable on line with echocardiography, was fulfilled through modifications of integrated backscatter imaging to permit real-time differentiation of the endocardium and the blood pool area in every image frame. Operator-guided study of individual cardiac chambers permitted instantaneous measurement of chamber areas in either the systole or diastole, with resulting physiologically meaningful recordings that relate to cardiac function. Validation studies by various approaches suggest that the methodology is clinically relevant, and further improvements in design will sharpen its applicability in the future.
RESUMO
Left ventricular (LV) volume and ejection fraction estimation from two-dimensional echocardiograms requires off-line analysis and time-consuming manual tracing. LV volumes may be estimated on-line with a semiautomated edge detection echocardiographic system [also known as acoustic quantification (AQ)], but there are few data that compare volumes obtained from the AQ method with volumes derived from off-line manual tracing of conventional two-dimensional echocardiograms. Echocardiograms were performed in 48 patients at two medical centers. LV volumes were measured from the apical view with the method of discs and area-length formulae and from the parasternal short-axis view with the modified ellipsoid model. Based on the criterion of >/=75% endocardial visualization, 25 (52%) of the short-axis views and 14 (29%) of the apical views were analyzed by a single investigator. End-diastolic and end-systolic LV volumes derived on line with the AQ system showed a very strong linear association with off-line, manually traced volumes (r = 0.96-0.99). Correlations for ejection fraction also were strong (r = 0.90-0.96). End-diastolic and end-systolic LV volumes, measured from the apical views, were underestimated by the AQ method. However, because the error was in the same direction, ejection fractions measured with the AQ system and by manual tracing of conventional echocardiograms were similar. Estimation of ejection fraction using a semiautomated edge detection echocardiographic system is a promising method for noninvasive evaluation of systolic function in carefully selected patients.
RESUMO
A variety of noninvasive tests are available to clinicians for the evaluation of patients in whom ischemic heart disease is suspected because of chest pain, clinical antecedents, or a combination of the two. Although all tests in general help to varying degrees to refine (by inclusion or exclusion) the diagnosis in a given patient, there are undoubtedly important differences between tests regarding their scope and diagnostic accuracy in general, and with respect to certain groups of patients in particular. Because of this, and in view of the obvious economic implications, the topic merits critical review before the information obtained from these tests is used in patient management. This review is not intended to cover all features that argue for or against all currently available noninvasive tests for ischemic heart disease, but to place into perspective the importance of the clinical assessment of the patient in the light of the results of testing, and to obtain a more rational idea of their usefulness. Despite the risk of excluding certain material of interest, excellent techniques such as magnetic resonance imaging will not be covered in the review, only because they have not yet been included in meta-analyses. Emphasis on the Bayesian rationale or paradigm, together with discussion of recent meta-analyses, offers a balanced perspective of the use and possible misuse of these diagnostic tests, and of their clinical and economic implications.
Assuntos
Teste de Esforço , Isquemia Miocárdica/diagnóstico , Teorema de Bayes , Diagnóstico por Imagem , Humanos , Sensibilidade e EspecificidadeRESUMO
An increasing number of patients are implanted with continuous-flow left ventricular assist devices (LVAD) for the treatment of severe congestive heart failure. In parallel with this growing experience has been an increase in knowledge of how these devices alter cardiac physiology and the important implications this has for cardiac function. Echocardiography offers the ability to provide serial noninvasive evaluation before and after LVAD implantation to document these changes, guide management decisions, and identify LVAD dysfunction. The authors detail a comprehensive assessment of LVAD function by transthoracic echocardiography.
Assuntos
Ecocardiografia/métodos , Insuficiência Cardíaca/diagnóstico por imagem , Insuficiência Cardíaca/cirurgia , Coração Auxiliar , Disfunção Ventricular Esquerda/diagnóstico por imagem , Disfunção Ventricular Esquerda/cirurgia , Análise de Falha de Equipamento/métodos , Insuficiência Cardíaca/complicações , Humanos , Prognóstico , Resultado do Tratamento , Disfunção Ventricular Esquerda/etiologiaRESUMO
BACKGROUND: The diabetic heart exhibits increased left ventricular (LV) mass and reduced ventricular function. However, this relationship has not been studied in patients with aortic stenosis (AS), a disease process that causes LV hypertrophy and dysfunction through a distinct mechanism of pressure overload. The aim of this study was to determine how diabetes mellitus (DM) affects LV remodeling and function in patients with severe AS. METHODS AND RESULTS: Echocardiography was performed on 114 patients with severe AS (mean aortic valve area [AVA], 0.6 cm(2)) and included measures of LV remodeling and function. Multivariable linear regression models investigated the independent effect of DM on these aspects of LV structure and function. Compared to patients without diabetes (n=60), those with diabetes (n=54) had increased LV mass and LV end-systolic and end-diastolic dimensions, and decreased LV ejection fraction (EF) and longitudinal systolic strain (all P<0.01). In multivariable analyses adjusting for age, sex, systolic blood pressure, AVA, body surface area, and coronary disease, DM was an independent predictor of increased LV mass (ß=26 g, P=0.01), LV end-systolic dimension (ß=0.5 cm, P=0.008), and LV end-diastolic dimension (ß=0.3 cm, P=0.025). After also adjusting for LV mass, DM was associated with reduced longitudinal systolic strain (ß=1.9%, P=0.023) and a trend toward reduced EF (ß=-5%, P=0.09). Among patients with diabetes, insulin use (as a marker of disease severity) was associated with larger LV end-systolic dimension and worse LV function. LV mass was a strong predictor of reduced EF and systolic strain (both P<0.001). CONCLUSIONS: DM has an additive adverse effect on hypertrophic remodeling (increased LV mass and larger cavity dimensions) and is associated with reduced systolic function in patients with AS beyond known factors of pressure overload.
Assuntos
Estenose da Valva Aórtica/fisiopatologia , Cardiomiopatias Diabéticas/fisiopatologia , Hipertrofia Ventricular Esquerda/fisiopatologia , Remodelação Ventricular , Idoso , Idoso de 80 Anos ou mais , Estenose da Valva Aórtica/diagnóstico por imagem , Feminino , Humanos , Hipertrofia Ventricular Esquerda/diagnóstico por imagem , Masculino , Ultrassonografia , Remodelação Ventricular/fisiologiaRESUMO
UNLABELLED: ACCREDITATION STATEMENT: The American Society of Echocardiography (ASE) is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The ASE designates this educational activity for a maximum of 1 AMA PRA Category 1 Credit.trade mark Physicians should only claim credit commensurate with the extent of their participation in the activity. The American Registry of Diagnostic Medical Sonographers and Cardiovascular Credentialing International recognize the ASE's certificates and have agreed to honor the credit hours toward their registry requirements for sonographers. The ASE is committed to resolving all conflict-of-interest issues, and its mandate is to retain only those speakers with financial interests that can be reconciled with the goals and educational integrity of the educational program. Disclosure of faculty and commercial support sponsor relationships, if any, have been indicated. TARGET AUDIENCE: This activity is designed for all cardiovascular physicians, cardiac sonographers, and nurses with a primary interest and knowledge base in the field of echocardiography; in addition, residents, researchers, clinicians, sonographers, and other medical professionals having a specific interest in contrast echocardiography may be included. OBJECTIVES: Upon completing this activity, participants will be able to: 1. Demonstrate an increased knowledge of the applications for contrast echocardiography and their impact on cardiac diagnosis. 2. Differentiate the available ultrasound contrast agents and ultrasound equipment imaging features to optimize their use. 3. Recognize the indications, benefits, and safety of ultrasound contrast agents, acknowledging the recent labeling changes by the US Food and Drug Administration (FDA) regarding contrast agent use and safety information. 4. Identify specific patient populations that represent potential candidates for the use of contrast agents, to enable cost-effective clinical diagnosis. 5. Incorporate effective teamwork strategies for the implementation of contrast agents in the echocardiography laboratory and establish guidelines for contrast use. 6. Use contrast enhancement for endocardial border delineation and left ventricular opacification in rest and stress echocardiography and unique patient care environments in which echocardiographic image acquisition is frequently challenging, including intensive care units (ICUs) and emergency departments. 7. Effectively use contrast echocardiography for the diagnosis of intracardiac and extracardiac abnormalities, including the identification of complications of acute myocardial infarction. 8. Assess the common pitfalls in contrast imaging and use stepwise, guideline-based contrast equipment setup and contrast agent administration techniques to optimize image acquisition.
Assuntos
Ecocardiografia/métodos , Ecocardiografia/normas , Aumento da Imagem/métodos , Aumento da Imagem/normas , Guias de Prática Clínica como Assunto , Consenso , Meios de Contraste , Estados UnidosRESUMO
AIMS: To illustrate the association between a patent foramen ovale (PFO) and paradoxical embolization. METHODS AND RESULTS: We report a unique case of a paradoxical embolization across a PFO noted during a transesophageal echocardiographic study. Serial images demonstrate the thrombus migrating from the superior vena cava to the left atrium across the PFO. CONCLUSIONS: This case establishes the association between the PFO and paradoxical embolism unequivocally.
Assuntos
Ecocardiografia Transesofagiana , Embolia Paradoxal/diagnóstico por imagem , Comunicação Interatrial/diagnóstico por imagem , Idoso , Feminino , Átrios do Coração , HumanosRESUMO
A patient with severe aortic insufficiency due to fenestration of the non-coronary aortic valve leaflet is described. A preoperative echocardiogram demonstrated early closure of the mitral valve and early diastolic separation of the aortic valve leaflets. These findings disappeared after partial surgical correction and subsequent hemodynamic improvement. Premature opening of the aortic valve is common in severe aortic insufficiency.
RESUMO
Lutjanidae, commonly known as snappers, includes 105 species, grouped in four subfamilies. In spite of the high number of species and of its worldwide distribution, the family has been little investigated and the phylogenetic relationships among some of its genera and species are still cause for debate. Only a small number of the species has been cytogenetically analysed. This study reports the first description of the karyotype of Rhomboplites aurorubens as well as data concerning the distribution of the constitutive heterochromatin and the location of the 18S rRNA and the 5S rRNA genes. Specimens of Ocyurus chrysurus from Venezuela were also investigated for the same cytogenetic features. Both species have a 48 uniarmed karyotype, but R. aurorubens has a single subtelocentric chromosome pair, the smallest of the chromosome complement, among the other acrocentric chromosomes. The C-positive heterochromatin is limited to the pericentromeric regions of all chromosomes. Both species show a single chromosome pair bearing the Nucleolus Organizer Regions, but NORs are differently located, in a terminal position on the short arms of the smallest chromosomes in R. aurorubens and in a paracentromeric position in a chromosome pair of large size in O. chrysurus. In O. chrysurus, the 5S rDNA gene cluster is located on a medium-sized chromosome pair, whereas in R. aurorubens it is syntenic with the 18S rDNA gene cluster on chromosome pair number 24. The obtained cytogenetic data, along with previous cytogenetic, morphological and molecular data for the family, reinforce the proposal to synonymize genus Ocyurus with Lutjanus. A review of Lutjanidae cytogenetics is also included.
Lutjanidae, comumente conhecidos como snappers, inclui 105 espécies, reunidas em quatro subfamílias. A despeito do grande número de espécies e de sua distribuição mundial, a família tem sido pouco estudada e as relações filogenéticas entre alguns de seus gêneros e espécies ainda é motivo de debates. Apenas um pequeno número de espécies foi citogeneticamente analisada. Esse estudo apresenta a primeira descrição do cariótipo de Rhomboplites aurorubens assim como dados relativos à distribuição de heterocromatina constitutiva e localização dos genes 18S rRNA e 5S rRNA. Espécimes de Ocyurus chrysurus da Venezuela foram também analisados quanto às mesmas características citogenéticas. Ambas as espécies têm cariótipos compostos de 48 cromossomos com um único braço, entretanto R. aurorubens tem um único par de cromossomos subtelocêntrico, o menor do complemento cromossômico, entre os outros cromossomos acrocêntricos. A heterocromatina C-positiva é limitada à região pericentromérica de todos os cromossomos. Ambas as species apresentam um único par com Regiões Organizadoras de Nucléolo, mas as RONs são localizadas em posições diferentes, em posição terminal no braço curto dos menores cromossomos de R. aurorubens e em posição paracentromérica no braço longo de um par de cromossomos grandes de O. chrysurus. Em O. chrysurus, os genes 5S rDNA estão localizados em um par de cromossomos de tamanho médio, enquanto em R. aurorubens eles são sintenicamente localizados com os genes 18S rDNA no par de cromossomos número 24. Os dados citogenéticos obtidos, junto com os dados morfológicos e moleculares disponíveis para a família reforçam a proposta de sinonimizar o gênero Ocyurus com Lutjanus. Uma revisão da citogenética dos Lutjanidae é também apresentada
Assuntos
Animais , Perciformes/genética , Citogenética/classificação , Heterocromatina , Genes de RNAr/genéticaAssuntos
Meios de Contraste/administração & dosagem , Doença das Coronárias/diagnóstico por imagem , Ecocardiografia/métodos , Fluorocarbonos , Hipertensão/diagnóstico por imagem , Síndrome Metabólica/complicações , Disfunção Ventricular Esquerda/diagnóstico por imagem , Doença das Coronárias/complicações , Doença das Coronárias/fisiopatologia , Diagnóstico Diferencial , Humanos , Hipertensão/complicações , Hipertensão/fisiopatologia , Injeções Intravenosas , Masculino , Síndrome Metabólica/diagnóstico por imagem , Microbolhas , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Disfunção Ventricular Esquerda/complicações , Disfunção Ventricular Esquerda/fisiopatologiaRESUMO
Given that the introduction of organisms into a new environment usually occurs in low numbers, reducing genetic diversity (the so-called bottleneck effect), and that selection further decreases diversity beyond that caused by the bottleneck, then how do some alien species, if their genetic variation is low under new conditions, succeed in evolving rapidly, becoming invasive and expanding their ranges? In this paper a series of mechanisms that allow the introduced population to acquire new genetic variations are considered. Various possible roles of epigenetic adaptation, hybridization, adaptive mutations, transposons, endosymbiosis, somatic mutations, and mitotic recombination are postulated as sources of new genetic variations. The roles of purging and biotic regulation in the successful invasions of some species is also analyzed.
La introducción de organismos a un nuevo ambiente generalmente ocurre en escaso número de individuos, lo cual determina el llamado "cuello de botella", reduciendo la variación genética, mientras que la selección reduce aún más esta variación. Entonces, ¿Cómo estos exóticos son exitosos, expanden su rango de distribución bajo nuevas condiciones, evolucionan rápidamente y se convierten en invasores, si su variación genética es baja? En el presente trabajo, se consideran una serie de mecanismos que permitirían a las poblaciones introducidas adquirir nueva variación genética. Las adaptaciones epigenéticas, la hibridización, las mutaciones adaptativas, los transposones, la endosimbiosis, las mutaciones somáticas y recombinaciones mitóticas son postuladas como fuentes de nueva variación. Además se analiza el papel de la purificación y la regulación biótica en la invasión exitosa de algunas especies.
A introdução de organismos a um novo ambiente geralmente ocorre em escasso número de indivíduos, o qual determina o chamado "efeito gargalo", reduzindo a variação genética, enquanto que a seleção reduz ainda mais esta variação. Como, então, podem estes exóticos ser bem sucedidos, expandir sua faixa de distribuição sob novas condições, evolucionar rapidamente e se converter em invasores, se sua variação genética é baixa? No presente trabalho, é considerada uma série de mecanismos que permitiriam às populações introduzidas adquirirem nova variação genética. As adaptações epigenéticas, a hibridização, as mutações adaptativas, os transposões, a endossimbiose, as mutações somáticas e recombinações mitóticas são postuladas como fontes de nova variação. Além disso, se analisa o papel da purificação e a regulação biótica na invasão bem sucedida de algumas espécies.