RESUMEN
We have reported a case of left atrial myxoma in association with an atrial septal defect in a patient followed up over a number of years for recurrent sterile pleural effusions and chronic obstructive lung disease of undetermined cause. During hospitalization for pneumonia, an intracardiac mass and atrial septal defect were found by echocardiography, and verified at operation to be a left atrial myxoma.
Asunto(s)
Neoplasias Cardíacas/complicaciones , Defectos del Tabique Interatrial/complicaciones , Mixoma/complicaciones , Embolia Pulmonar/etiología , Ecocardiografía , Aneurisma Cardíaco/complicaciones , Atrios Cardíacos , Neoplasias Cardíacas/diagnóstico , Humanos , Masculino , Persona de Mediana Edad , Mixoma/diagnósticoRESUMEN
The rare occurrence of mitral stenosis and coexistent left atrial myxoma is reported. The patient had a 25-year history of rheumatic heart disease and was referred for evaluation of progressive mitral stenosis without clinical suspicion of left atrial myxoma. The tumor was discovered by routine echocardiography in the course of evaluation of mitral stenosis. However, prior to surgery the patient experienced an episode of embolization of the tumor without major clinical sequelae. The utility of echocardiography in this case and in patients with mitral stenosis is discussed as well as the patient's spontaneous "cure."
Asunto(s)
Neoplasias Cardíacas/complicaciones , Estenosis de la Válvula Mitral/complicaciones , Mixoma/complicaciones , Cardiopatía Reumática/complicaciones , Ecocardiografía , Femenino , Atrios Cardíacos , Neoplasias Cardíacas/diagnóstico , Humanos , Persona de Mediana Edad , Estenosis de la Válvula Mitral/diagnóstico , Mixoma/diagnóstico , Células Neoplásicas Circulantes/diagnóstico , Cardiopatía Reumática/diagnósticoRESUMEN
1. Tyrosyl residues on ribonuclease A were nitrated with tetranitromethane and then reduced to aminotyrosyl residues. By variation of reaction conditions and degree of exposure of tyrosyl residues it was possible to convert from 1 to all 6 tyrosyl to aminotyrosyl residues. 2. At the lower levels of 1-3 aminated tyrosyl residues/molecule the change in conformation seemed minor and 70% of the enzymatic activity was retained. When the three buried tyrosyl residues or all six residues were aminated only 5% of the enzymatic activity was retained. 3. Titration data, susceptibility to urea denaturation, and fluorescence characteristics indicated that some of the aminotyrosyl residues were buried in the interior and others were exposed on the surface of the protein. On the basis of the activation/emission wavelengths it was possible to distinguish buried (288/320 nm) and exposed (288/365-395 nm) aminotyrosyl residues as well as exposed tyrosyl residues (275-305 nm). 4. The modification of specific tyrosyl residues on a protein to aminotyrosyl residues appears to have some promise for observation of changes in environment of the residues that accompany various conformation changes by monitoring the fluorescence.
Asunto(s)
Ribonucleasas , Aminas , Animales , Sitios de Unión , Bovinos , Páncreas/enzimología , Unión Proteica , Conformación Proteica , Espectrometría de Fluorescencia , Relación Estructura-Actividad , Tirosina/análisis , UreaRESUMEN
1. Five peptides containing tyrosine were converted to the 3-aminotyrosyl peptides by nitration with tetranitromethane and subseuqent reduction of the nitro groups to amino groups. The fluorescence of these aminotyrosyl residues was found to be quite similar to that of 3-aminotyrosine and it is concluded that the fluorescence is not sensitive to incorporation of the amino acid into the peptide chain. 2. Fluorescence of 3-aminotyrosine derivatives was sensitive, however, to the nature of the solvent; as the dielectric constant decreased, fluorescence was enhanced ten fold and the emission maximum shifted from the 350-370 nm value in aqueous solution to 320 nm. It is predicted that similar differences might be expected for exposed and buried aminotyrosyl residues in a protein. 3. Exposed tyrosyl residues on the helical protein tropomyosin and a helical segment of paramyosin were aminated in part (39% and 34% of the total tyrosyl residues, respectively). The fluorescence of the aminated tyrosyl residues on these proteins was similar to that of the aminotyrosyl peptides in an aqueous medium. Although the fluorescence efficiency of an aminotyrosyl residue was much lower than that of a tyrosyl residue, it was easy to distinguish the fluorescence of the aminotyrosyl residues (350-355 nm) on the protein from that arising from unmodified tyrosyl residues (305 nm).