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1.
J Appl Microbiol ; 113(6): 1479-90, 2012 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-22900936

RESUMEN

AIMS: To establish protocols for the simultaneous detection and identification of Xanthomonas species causing tomato bacterial spot. METHODS AND RESULTS: We verified the specificity and sensitivity of the previously reported sets of primers designed for strains of the four species of Brazilian tomato bacterial spot xanthomonads, consisting of 30 of Xanthomonas euvesicatoria, 30 of X. vesicatoria, 50 of X. perforans and 50 of X. gardneri. Furthermore, we tested a multiplex PCR protocol for the purpose of concurrent species identification. The possibility of direct detection of the pathogens in diseased leaf samples was also verified. The primers were highly specific, amplifying only target DNA. The sensitivity of the primers in conventional PCR was 50 pg µl(-1) for purified DNA and ranged from 5 × 10(2) to 5 × 10(4) CFU ml(-1) when bacterial suspensions were analysed. The multiplex PCR was suitable for the detection of all four species and showed similar sensitivity to conventional PCR when tested on purified DNA. When using bacterial suspensions, its sensitivity was similar to conventional PCR only when a biological amplification step (Bio-PCR) was included. Both methods were able to detect the pathogens in symptomatic tomato leaves. CONCLUSIONS: Brazilian Xanthomonas strains causing tomato bacterial spot can be differentiated and identified at species level by a PCR-based method and by a multiplex PCR. SIGNIFICANCE AND IMPACT OF THE STUDY: This protocol may be a feasible alternative tool for the identification and detection of these pathogens in plant material and may be used for routine diagnostic purposes in plant pathology laboratories.


Asunto(s)
Reacción en Cadena de la Polimerasa Multiplex , Enfermedades de las Plantas/microbiología , Solanum lycopersicum/microbiología , Xanthomonas/aislamiento & purificación , Brasil , Cartilla de ADN/genética , ADN Bacteriano/aislamiento & purificación , Hojas de la Planta/microbiología , Sensibilidad y Especificidad , Especificidad de la Especie , Xanthomonas/clasificación , Xanthomonas/genética
2.
Braz J Microbiol ; 41(1): 246-52, 2010 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-24031487

RESUMEN

Myrothecium roridum and M. verrucaria are two plant pathogenic species causing foliar spots in a large number of cultivated plants. This paper aims to study the causal agents of foliar spots in vegetable crops (sweet pepper, tomato, cucumber), ornamental plants (Spathiphyllum, Solidago canadensis, Anthurium, Dieffenbachia) and a solanaceous weed plant (Nicandra physalodes). Most of the isolates were identified as M. roridum; only the isolate 'Myr-02' from S. canadensis was identified as M. verrucaria. All the isolates were pathogenic to their original plant hosts and also to some other plants. Some fungicides were tested in vitro against an isolate of M. roridum and the mycelial growth recorded after seven days. Fungicides with quartenary ammonium, Tebuconzole and copper were highly effective in inhibiting the mycelial growth of M. roridum. This paper confirms the first record of M. roridum causing leaf spots in sweet pepper, tomato, Spathiphyllum, Anthurium, Dieffenbachia and N. physalodes. We also report M. roridum as causal agent of cucumber fruit rot and also M. verrucaria in tango plants.

3.
J Am Coll Cardiol ; 15(7): 1587-93, 1990 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-2345239

RESUMEN

M-mode echocardiography reveals an abrupt change between early and late left ventricular posterior wall kinetics during relaxation. No attempt has been previously made to relate this wall kinetic change and transmitral flow rate. In 25 normal subjects, 14 patients with dilated cardiomyopathy (Group 1) and 17 patients with hypertrophic cardiomyopathy (Group 2), M-mode echocardiographic studies were performed on the posterior wall and mitral valve. Transient values of mitral orifice area were calculated and transmitral flow velocities were recorded: area and velocity data yielded transmitral flow rates. Time intervals were determined from mitral opening to peak early area, velocity and flow rate and to posterior wall slope change. An additional group included five patients with a mitral prosthesis. The posterior wall slope change was present when part of the myocardial structures were almost akinetic or when mitral chordae tendineae were absent; slope change appeared as a regional phenomenon in the free wall. In the normal subjects, close values were found for the four time intervals. In the patients with dilated and hypertrophic cardiomyopathy, peak early velocity (95.7 +/- 16.7 and 146.2 +/- 31.4 ms, respectively), peak flow rate (84.7 +/- 18.2 and 137.4 +/- 29.5 ms) and time to slope change (91.4 +/- 18.6 and 133.6 +/- 32.7 ms) were significantly delayed (p less than 0.001) in comparison with peak area (56.6 +/- 9.5 and 84.3 +/- 22.5 ms). Slope change does not indicate the end of the early filling phase but, rather, its transition from acceleration to deceleration. Time to peak velocity or time to peak filling rate must be considered in a relaxation analysis.


Asunto(s)
Corazón/fisiología , Velocidad del Flujo Sanguíneo , Cardiomiopatía Dilatada/fisiopatología , Cardiomiopatía Hipertrófica/fisiopatología , Circulación Coronaria , Diástole , Corazón/fisiopatología , Prótesis Valvulares Cardíacas , Ventrículos Cardíacos , Humanos , Cinética , Válvula Mitral/fisiología , Válvula Mitral/fisiopatología , Factores de Tiempo
4.
J Am Coll Cardiol ; 20(2): 420-32, 1992 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-1634681

RESUMEN

OBJECTIVES: This study was designed to evaluate the relation between the velocity of flow propagation and left ventricular relaxation by using color M-mode Doppler echocardiography to analyze flow propagation in the left ventricle. BACKGROUND: Noninvasive attempts to identify alterations in left ventricular relaxation have been hampered because both the relaxation rate and left atrial filling pressure are the determinants of peak early velocity and filling rate. METHODS: Color M-mode velocity data were transferred to a microcomputer and compared with conventional pulsed Doppler data to assess the ability of color M-mode echocardiography to analyze velocity field properties. The velocity of flow propagation was measured as the slope of the flow wave front during early filling in normal subjects (n = 29) and in patients with disease that alters relaxation (dilated cardiomyopathy [n = 31], ischemic cardiomyopathy [n = 8], hypertrophic cardiomyopathy [n = 5], systemic hypertension [n = 22] and aortic valve disease [n = 25]). In nine patients with end-stage dilated cardiomyopathy, echocardiographic and left heart catheterization data were obtained at baseline and during intracoronary dobutamine infusion. RESULTS: Color M-mode and pulsed Doppler echocardiographic data were highly correlated (n = 217, r = 0.94, p less than 0.0001, velocity range 0.2 to 1.5 m/s). The velocity of flow propagation was lower in patients than in normal subjects (0.46 +/- 0.15 vs. 0.84 +/- 0.11 m/s, p less than 0.0001). The decrease was significant in all disease forms with or without left ventricular dilation. The velocity of flow propagation was related to peak early velocity in normal subjects (p less than 0.001) but not in patients. It varied inversely with the isovolumetric relaxation time constant during dobutamine infusion and the two variables were highly correlated (p less than 0.0001). CONCLUSIONS: The velocity of flow propagation during early filling seems to be highly dependent on the left ventricular relaxation rate and could be an important tool in studying diastolic function.


Asunto(s)
Cardiomiopatías/diagnóstico por imagen , Ecocardiografía Doppler , Ecocardiografía , Enfermedades de las Válvulas Cardíacas/diagnóstico por imagen , Hipertensión/diagnóstico por imagen , Contracción Miocárdica/fisiología , Función Ventricular Izquierda/fisiología , Velocidad del Flujo Sanguíneo/fisiología , Cardiomiopatías/fisiopatología , Dobutamina , Estudios de Evaluación como Asunto , Enfermedades de las Válvulas Cardíacas/fisiopatología , Humanos , Hipertensión/fisiopatología , Reproducibilidad de los Resultados
5.
J Nucl Med ; 40(6): 917-23, 1999 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-10452306

RESUMEN

UNLABELLED: Alterations of cardiac sympathetic innervation are likely to contribute to fatal outcomes in patients with heart failure. These alterations can be evaluated noninvasively by 123I-metaiodoben-zylguanidine (MIBG) imaging. METHODS: The hypothesis that impaired cardiac sympathetic innervation, as assessed using MIBG imaging, is related to adverse outcomes was tested in 112 patients with heart failure resulting from idiopathic cardiomyopathy. Main inclusion criteria were New York Heart Association classes II-IV and radionuclide left ventricular ejection fraction (LVEF) < 40%. Patients were assessed for cardiac MIBG uptake, circulating norepinephrine concentration, LVEF, peak Vo2, x-ray cardiothoracic ratio, M-mode echographic end-diastolic diameter and right-sided heart catheterization parameters. RESULTS: During a mean follow-up of 27 +/- 20 mo, 19 patients had transplants, 25 died of cardiac death (8 sudden deaths), 2 died of noncardiac death and 66 survived without transplantation. The only independent predictors for mortality were low MIBG uptake (P < 0.001) and LVEF (P = 0.02) when using multivariate discriminant analysis. Moreover, MIBG uptake (P < 0.001) and circulating norepinephrine concentration (P = 0.001) were the only independent predictors for life duration when using multivariate life table analysis. CONCLUSION: Impaired cardiac adrenergic innervation as assessed by MIBG imaging is strongly related to mortality. MIBG imaging may help risk stratify patients with heart failure resulting from idiopathic dilated cardiomyopathy.


Asunto(s)
3-Yodobencilguanidina , Cardiomiopatía Dilatada/diagnóstico por imagen , Corazón/diagnóstico por imagen , Corazón/inervación , Radiofármacos , Sistema Nervioso Simpático/diagnóstico por imagen , Adulto , Anciano , Cateterismo Cardíaco , Cardiomiopatía Dilatada/mortalidad , Cardiomiopatía Dilatada/fisiopatología , Interpretación Estadística de Datos , Muerte Súbita Cardíaca/etiología , Ecocardiografía , Estudios de Seguimiento , Trasplante de Corazón , Hemodinámica , Humanos , Radioisótopos de Yodo , Persona de Mediana Edad , Norepinefrina/sangre , Pronóstico , Estudios Prospectivos , Radiografía Torácica , Ventriculografía con Radionúclidos , Volumen Sistólico , Factores de Tiempo , Función Ventricular Izquierda
6.
J Nucl Med ; 33(4): 471-7, 1992 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-1552326

RESUMEN

The prognostic value of 123I-metaiodobenzylguanidine (MIBG) imaging was compared with that of other noninvasive cardiac imaging indices in ninety patients (mean age = 52 +/- 7 yr) suffering from either ischemic (n = 24) or idiopathic (n = 66) cardiomyopathy. Patients had different measurements taken: cardiac MIBG uptake, radionuclide left ventricular ejection fraction, x-ray cardiothoracic ratio and echographic M-Mode data. Cardiac MIBG uptake was assessed as the heart-to-mediastinum activity ratio measured on the chest anterior view image obtained 4 hr after intravenous injection. The patients then had follow-up for 1-27 mo, at which time 10 patients had transplants, 22 had died and 58 were still alive. Data from patients with transplants were not used in the analysis, in which multivariate stepwise regression discriminant analysis showed that cardiac MIBG uptake was more potent to predict survival than other indices: H/M (p less than 0.0001), x-ray cardiothoracic ratio (p = 0.0017), echographic end-diastolic diameter (p = 0.0264) and radionuclide left ventricular ejection fraction (p = 0.0301). Moreover, multivariate life table analysis showed that cardiac MIBG uptake was also the best predictor for life duration: H/M (p = 0.0001), radionuclide left ventricular ejection fraction (p = 0.0098) and x-ray cardiothoracic ratio (p = 0.0139); echographic data were not useful. Thus, cardiac MIBG imaging may be helpful for heart transplantation decision making in patients with heart failure.


Asunto(s)
Insuficiencia Cardíaca/diagnóstico por imagen , Yodobencenos , 3-Yodobencilguanidina , Ecocardiografía , Femenino , Estudios de Seguimiento , Francia/epidemiología , Insuficiencia Cardíaca/epidemiología , Insuficiencia Cardíaca/mortalidad , Humanos , Radioisótopos de Yodo , Masculino , Persona de Mediana Edad , Análisis Multivariante , Pronóstico , Cintigrafía , Volumen Sistólico , Tasa de Supervivencia , Función Ventricular Izquierda/fisiología
7.
Drugs ; 33 Suppl 3: 231-4, 1987.
Artículo en Inglés | MEDLINE | ID: mdl-3315600

RESUMEN

25 patients have been included in a randomised trial aimed to compare prehospital and hospital administration of anisoylated plasminogen streptokinase activator complex (AP-SAC). Patients were first seen, at home, by a noncardiologist doctor working in a mobile-care unit and were then evaluated for entry into the study. If they had evidence of myocardial infarction lasting for less than 3 hours and if there was no contraindication to thrombolytic therapy they were randomly allocated to APSAC 30U or placebo. They were next referred to an intensive coronary unit (ICU). On arrival in the ICU patients were reevaluated and received APSAC if they had previously received placebo. For 24 patients, diagnosis of myocardial infarction was confirmed. One patient died at home after having received placebo. There was 1 hospital death. At-home injection was made within a median of 124 minutes after the beginning of pain, whereas hospital administration was made after a median of 180 minutes. On a clinical basis reperfusion occurred in 16 out of 21 evaluable patients. Four patients had coronary artery bypass graft surgery and 9 had angioplasty. We conclude that prehospital administration of APSAC is feasible, well-tolerated and is a good way to shorten the delay of thrombolytic treatment in myocardial infarction.


Asunto(s)
Fibrinolíticos/administración & dosificación , Infarto del Miocardio/tratamiento farmacológico , Plasminógeno/administración & dosificación , Estreptoquinasa/administración & dosificación , Adulto , Anciano , Anistreplasa , Electrocardiografía , Femenino , Humanos , Masculino , Persona de Mediana Edad , Unidades Móviles de Salud , Distribución Aleatoria , Factores de Tiempo
8.
J Heart Lung Transplant ; 14(5): 846-55, 1995.
Artículo en Inglés | MEDLINE | ID: mdl-8800719

RESUMEN

BACKGROUND: Histologic changes in cardiac allografts resulting from fibrosis or acute rejection can modify ventricular diastolic function and ventricular inflow characteristics. These abnormalities may be detected by color M-mode Doppler echocardiography which has been shown to be sensitive in assessing ventricular diastolic function. METHODS: Twelve cardiac allograft recipients were prospectively studied with serial color M-mode and single-gated Doppler echocardiography, as well as with endomyocardial biopsy, with a follow-up of approximately 10 weeks. The myocardial interstitial collagen content as evaluated by videodensitometry was compared with right and left ventricular late filling termination times measured in the absence of a severe episode of rejection. RESULTS: A positive and significant correlation was found between the collagen content and the corresponding right ventricular late filling termination time (r = 0.89, p < 0.0001), but no correlation was found with the left ventricular late filling termination time. Moreover, variations in collagen content and variations in right ventricular late filling termination time were also highly correlated (r = 0.91, p < 0.0001). In allograft recipients who had episodes of rejection of grade 3A or greater, both right and left ventricular late filling termination times were significantly increased during rejection. CONCLUSIONS: Measurements of right ventricular late filling termination time by color M-mode Doppler echocardiography performed in the absence of acute rejection can be use to monitor the evolution of interstitial collagen content in cardiac allografts. The early detection of abnormally prolonged late filling termination time could be followed by endomyocardial biopsy to confirm the histologic changes.


Asunto(s)
Colágeno/análisis , Ecocardiografía Doppler en Color , Trasplante de Corazón , Miocardio/química , Función Ventricular Derecha , Adulto , Anciano , Biopsia , Femenino , Fibrosis , Rechazo de Injerto/diagnóstico , Humanos , Procesamiento de Imagen Asistido por Computador , Masculino , Persona de Mediana Edad , Miocardio/patología , Estudios Prospectivos , Función Ventricular Izquierda
9.
Ann Thorac Surg ; 55(6): 1513-7, 1993 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-8512404

RESUMEN

The aim of the present study was to determine the long-term status of the native aortic valve after surgical treatment of acute aortic dissection involving the ascending aorta. From 1972 to 1991, 93 patients underwent operation for type I or II aortic dissection. There were 76 men and 17 women. Mean age was 54 +/- 13 years. Eighty patients (86%) had a conservative procedure regarding the aortic root and aortic cusps: 74 had prosthetic replacement of the ascending aorta and 6, complete replacement of the aortic arch. Thirteen patients (14%) had simultaneous replacement of the aortic valve and the ascending aorta. The overall hospital mortality rate was 29% (27/93). The overall actuarial survival rate was 60.2% +/- 5.2%, 49.7% +/- 6.1%, and 35.9% +/- 8.1% at 5, 10, and 15 years, respectively. The survival rates for patients who had an ascending aortic procedure only were 63% +/- 5.5%, 54% +/- 6.5%, and 39% +/- 8.5% at 5, 10, and 15 years, respectively, and for patients who required aortic valve replacement, 45% +/- 14% and 22% +/- 17.5% at 5 and 10 years, respectively. Fifty long-term survivors (94% follow-up) with preservation of the aortic valve and aortic root were studied. Among them, 9 (18%) died within a mean interval of 97 +/- 46 months after operation. Causes of death were ischemic cardiac failure (2), aortic rupture or extension of dissection (4), renal disease (1), stroke (1), and sudden death (1). Forty-one patients had long-term clinical and echocardiographic evaluation.(ABSTRACT TRUNCATED AT 250 WORDS)


Asunto(s)
Aneurisma de la Aorta/cirugía , Disección Aórtica/cirugía , Insuficiencia de la Válvula Aórtica/prevención & control , Válvula Aórtica , Ecocardiografía , Disección Aórtica/diagnóstico por imagen , Disección Aórtica/mortalidad , Aorta , Aneurisma de la Aorta/diagnóstico por imagen , Aneurisma de la Aorta/mortalidad , Prótesis Vascular , Femenino , Estudios de Seguimiento , Prótesis Valvulares Cardíacas , Humanos , Masculino , Persona de Mediana Edad , Reoperación , Análisis de Supervivencia , Factores de Tiempo
10.
J Am Soc Echocardiogr ; 14(8): 798-805, 2001 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-11490328

RESUMEN

We studied the relation between the ischemic threshold at the onset of wall motion abnormality on exercise echocardiography (EE) and the severity of coronary stenosis in patients with 1-vessel coronary artery disease (CAD). We screened 216 consecutive patients who underwent coronary angiography and EE for suspected CAD. Ninety-five (74 men; age, 56 +/- 12 years) satisfied the study criteria, that is, the presence of 1-vessel disease or no evidence of CAD on angiography and a normal baseline echocardiogram. Eighty-seven patients had 1-vessel CAD on angiography, and exercise-induced wall motion abnormality occurred in 73 (77%). Optimal cutoff values of percent diameter stenosis and minimal lumen diameter for predicting a positive EE were 61% (sensitivity and specificity of 76%) and 1.12 mm (sensitivity and specificity of 74%). Among patients with positive EE, heart rate-blood pressure product at ischemic threshold was correlated with quantitative coronary stenosis (r = -0.72, P <.001). The ischemic threshold from continuous monitoring of left ventricular function during semisupine EE is correlated with the severity of coronary stenosis among patients with 1-vessel disease and a normal resting echocardiogram.


Asunto(s)
Enfermedad Coronaria/diagnóstico por imagen , Enfermedad Coronaria/fisiopatología , Vasos Coronarios/diagnóstico por imagen , Vasos Coronarios/fisiopatología , Ecocardiografía , Isquemia Miocárdica/diagnóstico por imagen , Isquemia Miocárdica/fisiopatología , Disfunción Ventricular Izquierda/diagnóstico por imagen , Disfunción Ventricular Izquierda/fisiopatología , Adulto , Anciano , Angiografía Coronaria , Prueba de Esfuerzo , Femenino , Humanos , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados , Posición Supina/fisiología
11.
Eur J Cardiothorac Surg ; 3(3): 196-202, 1989.
Artículo en Inglés | MEDLINE | ID: mdl-2533876

RESUMEN

From September 1985 to August 1988, 32 patients were referred from various intensive care units throughout Paris for urgent cardiac transplantation or for a mechanical bridge to transplantation. At time of admission, under maximal sympathomimetic therapy, the cardiac index (CI) was 1.81 +/- 0.26 l/min per m2, the pulmonary capillary wedge pressure (PCWP 31 +/- 7 mmHg), systemic vascular resistances (SVR) 2053 +/- 469 dynes s cm-5. In 25, diuresis was less than 25 ml/h. Five were anuric. Prior to any final decision, a new inotropic agent, enoximone, was infused in addition to previous treatment as a 10 min bolus iv 1.5-2 mg/kg every 8 h. In 3, the situation further deteriorated, leading to a Jarvik 7-70 implantation within 12 h. In 29 however, within 3 h, the Cl increased to 2.69 +/- 0.56 as SVR dropped to 1410 +/- 453 and PCWP to 18 +/- 7. Diuresis increased to more than 100 ml/h in all. This permitted an indepth evaluation of the transplant candidates leading to contraindications to transplantation in 16. Nine patients could be weaned off iv enoximone. Four of these are still living (NYHA class III) with a follow up of 6-17 months. In 11, transplantation was performed within 2 days. Four died within a month, 2 with multiple organ failure. One patient died after 5 months. Six are back to normal life, NYHA class I (follow up 10 months-2.5 years). This protocol suggests that in patients with extreme heart failure, immediate survival may be increased by iv enoximone therapy, permitting a better selection of the recipients, more efficient pre-transplantation intensive care and consequently a decrease in the indications for a temporary mechanical bridge to a staged transplantation.


Asunto(s)
Cardiotónicos/uso terapéutico , Trasplante de Corazón , Imidazoles/uso terapéutico , Inhibidores de Fosfodiesterasa/uso terapéutico , Adenosina Monofosfato/metabolismo , Adolescente , Adulto , Cardiotónicos/administración & dosificación , Enoximona , Femenino , Corazón Artificial , Corazón Auxiliar , Hemodinámica/efectos de los fármacos , Humanos , Imidazoles/administración & dosificación , Infusiones Intravenosas , Masculino , Persona de Mediana Edad , Evaluación de Procesos y Resultados en Atención de Salud , Inhibidores de Fosfodiesterasa/administración & dosificación
12.
Psychiatr Serv ; 51(3): 327-31, 2000 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-10686237

RESUMEN

The article on the new drugs reprinted below appeared in the February 1956 issue of Mental Hospitals. It is based on a discussion held during the Seventh Mental Hospital Institute in October 1955 in Washington, D.C. Chlorpromazine and reserpine had been available in the United States less than two years when the institute participants met to discuss how their hospitals were coping with the demands of the new treatments. In a commentary and analysis beginning on page 333, Robert Cancro, M.D., considers the broader impact of the introduction of neuroleptics and examines the concerns of the 1956 institute participants in the context of today.


Asunto(s)
Antipsicóticos/historia , Clorpromazina/historia , Trastornos Psicóticos/historia , Reserpina/historia , Antipsicóticos/uso terapéutico , Clorpromazina/uso terapéutico , Historia del Siglo XX , Hospitales Psiquiátricos/historia , Humanos , Servicios de Salud Mental/economía , Servicios de Salud Mental/historia , Trastornos Psicóticos/tratamiento farmacológico , Trastornos Psicóticos/economía , Reserpina/uso terapéutico , Estados Unidos
13.
Biorheology ; 28(3-4): 143-50, 1991.
Artículo en Inglés | MEDLINE | ID: mdl-1932706

RESUMEN

Preliminary assumption of this model is that interactions between actin and myosin presupposes an exact three-dimensional geometrical correspondence between sites, due to the very short time constants present under physiological conditions. Only small and controlled torsions of the actin filaments are accepted. The model uses geometrical information concerning orientations and dimensions of myosin crossbridges and actin monomeres to modelize the distribution of their inter-actions. An orientation map of actin sites in the cross-section perpendicular to the filament axis is proposed, adapted to the specific filament array of vertebrate muscle. Orientation of myosin crossbridges follows Luther's rules. According to the model, any interaction between actin and myosin implies the superimposition of their respective cross-sectional planes. The axial length of actin monomere is 55 A; the distance between two crossbridges along the myosin filament axis is 143 A. The following properties are derived: 1) The shortening step of the sliding actin filament must be a multiple of 11 A (highest common factor). Taking into account the staggered disposition of the two actin strands and the presence of two heads for each cross-bridge, the most probable value for this shortening step is equal to 99 A. A specific scheme is proposed to describe the shortening process. The behavior of the modelized crossbridge does not need any elastic structure--2) Planes situated at 715 A (lowest common multiple) of actin and myosin coinciding planes are also in coincidence. In a hemi-sarcomere the maximal number of these planes, referred to as simultaneously activable planes, is 10 (20 if both myosin heads are considered). The proportion of interactions authorized by the site orientations is 1/12. In the model, the concept of randomly recruited crossbridges is replaced by a discretized recruitment, based on geometrical properties at an ultrastructural level. The proposed distribution is homogeneous: it can be extended radially in the sarcomere and authorizes the actin filament sliding in the whole physiological range under the control of a dual activation function, reproducing Ca++ temporal and spatial distribution.


Asunto(s)
Actomiosina/fisiología , Corazón/fisiología , Modelos Cardiovasculares , Vertebrados/fisiología , Actinas/fisiología , Animales , Filamentos Intermedios/fisiología , Miocardio/ultraestructura , Miosinas/fisiología , Reología
14.
Arch Mal Coeur Vaiss ; 93(3): 291-9, 2000 Mar.
Artículo en Francés | MEDLINE | ID: mdl-11004976

RESUMEN

Hibernating myocardium is a term which covers chronic ischaemic left ventricular dysfunction which is potentially reversible after revascularisation. Hibernating myocardium is classically associated with chronic hypoperfusion responsible for hypocontraction and cellular degeneration. This "classical" conception has been questioned as some workers emphasise that the reduction in coronary reserve responsible for repeated episodes of ischaemia and stunning could be the main causes of myocardial dysfunction. Position emission tomography (PET), and, most of all, myocardial scintigraphy and dobutamine echocardiography are the most commonly used techniques for detecting hibernating myocardium. Their sensitivity is good but the specificity and positive predictive value of dobutamine echocardiography seems to be better than the isotopic techniques. Structural abnormalities of hibernating myocardium and the delay, which is often long, between revascularisation and improvement, may explain some of the discordances between these techniques. Irrespective of the term used, hibernation or chronic ischaemic left ventricular dysfunction with myocardial viability, the reported data is in favour of coronary revascularisation with improved long-term quality of life and reduced mortality in patients with positive viability tests.


Asunto(s)
Isquemia Miocárdica/complicaciones , Aturdimiento Miocárdico/diagnóstico , Disfunción Ventricular Izquierda/diagnóstico , Cardiotónicos , Diagnóstico Diferencial , Dobutamina , Humanos , Isquemia Miocárdica/diagnóstico , Revascularización Miocárdica , Aturdimiento Miocárdico/patología , Sensibilidad y Especificidad , Tomografía Computarizada de Emisión , Disfunción Ventricular Izquierda/patología
15.
Arch Mal Coeur Vaiss ; 93(1 Spec No): 33-41, 2000 Jan.
Artículo en Francés | MEDLINE | ID: mdl-10721446

RESUMEN

As many techniques of medical investigation, echocardiography regularly benefits from technical innovations which, with application, prove to be extremely useful and, for some of them, even widen the field of investigation. The end of this decade has seen the introduction of major improvements. In daily practice, second harmonic imaging has been the most important technical advance with such improved quality of imaging that this mode has rapidly become the routine for transthoracic investigations in adults. All modern echocardiographs are, or can be, equipped at modest cost. Stress echocardiography, the diagnostic reliability of which is closely related to the quality of the imaging, has greatly benefited from this technique, to the point of obtaining equivalent results as nuclear medicine in the detection of myocardial ischaemia and cellular viability. The results are now sufficiently convincing for the technique to have a real prognostic value in myocardial ischaemia. Doppler tissue imaging is also a major advance but the clinical value is still under evaluation: the pulsed Doppler mode is quantifiable during the investigation, contrary to the calculation of transparietal velocity gradients which requires computerisation techniques not provided by all manufacturers. The regain in interest in contrast echocardiography is due to the development of agents which, injected intravenously, cross the pulmonary capillary barrier and opacify the left heart chambers. The reinforcement of the Doppler signal and improved detection of the endocardial echoes have justified the authorization of their commercialisation, but the essential point is their use in the investigation of myocardial perfusion which is under evaluation. Three-dimensional reconstruction has made great strides but its diffusion is still limited by the limited availability of the required powerful computers.


Asunto(s)
Ecocardiografía Doppler/tendencias , Isquemia Miocárdica/diagnóstico por imagen , Medicina Nuclear/tendencias , Adulto , Diagnóstico por Computador , Diagnóstico Diferencial , Ecocardiografía Doppler/economía , Ecocardiografía Doppler/normas , Prueba de Esfuerzo , Costos de la Atención en Salud , Humanos , Pronóstico
16.
Arch Mal Coeur Vaiss ; 88 Spec No 3: 13-7, 1995 Aug.
Artículo en Francés | MEDLINE | ID: mdl-7503612

RESUMEN

After myocardial infarction treated by thrombolysis, secondary improvement of contractility may be observed due to the presence of viable but stunned myocardium in a zone of ischaemia. Echocardiography with lose dose Dobutamine has been proposed as a diagnostic test of myocardial viability. The inotropic effect of the pharmacological agent improves or induces myocardial thickening in zones of ischaemia. A positive response is observed in about one out of two cases. The sensitivity ranges from 79 to 86% and the specificity from 68 to 90% in the reported series. This mode of stress echocardiography for the study of post-infarction myocardial viability is under clinical evaluation: its advantages and limitations should be compared with those of other non-invasive methods, especially thallium myocardial scintigraphy.


Asunto(s)
Dobutamina , Ecocardiografía , Infarto del Miocardio/fisiopatología , Aturdimiento Miocárdico/diagnóstico por imagen , Cardiotónicos , Corazón/fisiopatología , Humanos , Infarto del Miocardio/diagnóstico por imagen
17.
Arch Mal Coeur Vaiss ; 90(7): 911-8, 1997 Jul.
Artículo en Francés | MEDLINE | ID: mdl-9339251

RESUMEN

Echocardiographic factors predictive of the maintenance of sinus rhythm after successful cardioversion were investigated in 94 patients with non-valvular atrial arrhythmias of recent onset. Seventy-five patients with atrial fibrillation and 19 with atrial flutter admitted for reduction of their arrhythmias underwent transthoracic and transoesophageal echocardiography. After excluding a thrombus in the left atrial appendage or checking that it had disappeared (5 patients), and electrical (n = 74) or pharmacological (n = 20) cardioversion was successfully performed. The maintenance of sinus rhythm (n = 44) or recurrence of arrhythmia (n = 50) were controlled every 3 months for one year. The mean value of the peak positive blood flow in the left atrial appendage was 38 +/- 20 cm/s for the whole group. It was not possible to identify an echocardiographic parameter predictive of maintenance of sinus rhythm at one year either in the whole group or in the subgroups with atrial flutter or atrial fibrillation. In the group in atrial flutter, the mean value of the peak positive blood flow in the left atrial appendage was significantly greater than in the group with atrial fibrillation: 49 +/- 22 cm/s vs 35 +/- 18 cm/s, respectively; p < 0.05. The peak of positive flow in the left atrial appendage was statistically related to indirect parameters of left atrial function and of left ventricular function in the group with atrial fibrillation but only with parameters of left ventricular function in the smaller group with atrial flutter.


Asunto(s)
Fibrilación Atrial/terapia , Aleteo Atrial/terapia , Ecocardiografía , Cardioversión Eléctrica , Frecuencia Cardíaca , Anciano , Fibrilación Atrial/fisiopatología , Aleteo Atrial/fisiopatología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Estudios Prospectivos , Recurrencia , Resultado del Tratamiento
18.
Arch Mal Coeur Vaiss ; 77(2): 228-32, 1984 Feb.
Artículo en Francés | MEDLINE | ID: mdl-6424608

RESUMEN

Chronic right ventricular failure was observed in a young female operated at 25 years of age for Fallot's tetralogy despite surgical refixation of the patch closing the ventricular septal defect which had previously worked loose. The signs of right ventricular failure were due to severe tricuspid incompetence, confirmed at catheterisation and selective right ventricular angiography. They were associated with major hypoproteinaemia which was not due to urinary loss nor hepatic dysfunction, but which was attributed to an exudative enteropathy. The correction of the valvular defect by valvuloplasty was followed by rapid correction of the biological abnormality. The authors review the relationship between serum proteins and cardiac disease, discuss those cardiac affections with known associations with exudative enteropathy, and also the possibilities of reversing the biological abnormality after surgical cure of the causal cardiac lesion.


Asunto(s)
Hipoproteinemia/etiología , Complicaciones Posoperatorias/etiología , Tetralogía de Fallot/cirugía , Insuficiencia de la Válvula Tricúspide/etiología , Adulto , Femenino , Prótesis Valvulares Cardíacas , Humanos , Válvula Tricúspide/cirugía , Insuficiencia de la Válvula Tricúspide/cirugía
19.
Arch Mal Coeur Vaiss ; 86(9): 1339-44, 1993 Sep.
Artículo en Francés | MEDLINE | ID: mdl-8129551

RESUMEN

The aim of this study was to determine the role of Doppler echocardiography in establishing the prognosis of Stages to 4 cardiac failure. The echocardiographic indices of left ventricular filling were correlated with catheter data and the 2 year out come of patients. The study population included 54 patients examined prospectively in the context of an evaluation of their cardiac failure. Two years after the initial examination, 19 patients were dead or transplanted. Of the remaining 35 patients, 18 were reevaluated at 6 months. Of the echocardiographic parameters, "hyper normal" mitral flow with a high E/A ration indicated poor prognosis; when E/A > 2, the one year survival was 50% and the 2 year survival 42%. There was overlap between the groups of dead or transplanted and surviving patients only when the E/A ratio was between 2 and 3. The patients with E/A < 2 were all alive without any major events at 2 years. All patients with E/A > 3 had a poor prognosis. The E/A ratio was closely correlated with pulmonary capillary pressure levels (p < 0.001, r = 0.55) and lees closely with cardiac index (p < 0.05, r = 0.4) and radionuclide ejection fraction (p < 0.05, r = 0.28). After 6 months' vasodilator treatment with an angiotensin converting enzyme inhibitor (captopril) the E/A ratio decreased significantly from 1.85 +/- 0.78 to 1.0 0.55 (p < 0.02). A "hyper-normal" mitral flow is related to many factors, including high left ventricular filling pressures, mitral regurgitation and reduced left ventricular compliance. This appearance of mitral flow is a poor prognosis factor in severe cardiac failure.


Asunto(s)
Ecocardiografía Doppler , Insuficiencia Cardíaca/diagnóstico por imagen , Válvula Mitral/diagnóstico por imagen , Análisis Actuarial , Adulto , Anciano , Velocidad del Flujo Sanguíneo , Estudios de Seguimiento , Humanos , Persona de Mediana Edad , Pronóstico , Estudios Prospectivos , Volumen Sistólico
20.
Arch Mal Coeur Vaiss ; 88(9): 1349-52, 1995 Sep.
Artículo en Francés | MEDLINE | ID: mdl-8526717

RESUMEN

The authors report the case of tetralogy of Fallot (TOF) associated with situs inversus, the first description of this rare association in a previously asymptomatic adult. A 32 years old chauffeur was admitted to hospital with pyrexia and convulsions due to a left temporo-parietal cerebral abscess which had a favourable outcome. The chest X-ray and Doppler echocardiographic study showed a TOF with a high infundibular stenosis and dextrocardia. Abdominal ultrasonography confirmed a complete situs inversus. The good tolerance was attributed to the equilibrated character of the TOF. The orientation of the heart and the cono-truncal septation occur at different times during embryogenesis. However, there are genetic arguments in favour of the non-fortuitous nature of this association.


Asunto(s)
Absceso Encefálico/etiología , Situs Inversus/complicaciones , Tetralogía de Fallot/complicaciones , Adulto , Humanos , Masculino , Situs Inversus/embriología , Tetralogía de Fallot/embriología
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