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Biomedical subjects

J M Rivera

Publications and source records attributed to J M Rivera.

67 records · Page 4Linked to original sources
PubMedDate not supplied

Three-dimensional echocardiography: the influence of number of component images on accuracy of left ventricular volume quantitation.

One approach to three-dimensional echocardiography is to reconstruct the surface of cardiac structures from two-dimensional images positioned in three-dimensional space. This approach has yielded accurate measures; however, the relationship between the number of nonparallel images used in three-dimensional echocardiographic reconstruction to the accuracy of the volume calculated has not been determined. With a canine model in which instantaneous left ventricular volume could be measured in vivo, images were obtained from intersecting long- and short-axis scans and stored with their spatial coordinates. The left ventricle was reconstructed and its volume calculated. The difference between three-dimensional echocardiographic and true volume was determined in 84 different cavitary volumes (4 to 85 ml). In each case, long- and short-axis images were deleted serially from the original data set (maximum of 27) until there were only three images left in the reconstruction. After each set of deletions, left ventricular volume was recalculated with the remaining images. Three-dimensional echocardiography accurately quantified ventricular volume with eight to 12 intersecting images, with a mean error of less than 1 ml and an SD of 5 ml. With a reduction of component images below eight, there were progressive increases in both absolute and mean percentage error. Accurate assessment of stroke volume and ejection fraction in this beating heart model also required eight to 12 images. Left ventricular volume and systolic function can be quantitated by three-dimensional echocardiography with as few as eight to 12 intersecting or nonparallel images.

Analysis of Variance↗
PubMedDate not supplied

Early aspects of human cochlea development and tectorial membrane histogenesis.

Several human embryos and foetuses cochlea from the first half of pregnancy were studied by light, transmission and scanning electron microscopy. Cochlea development in man is the result of three coexisting processes: First, coiling and maturation of the cartilaginous otic capsule. Second, resorption of the periodic mesenchymal reticulum with the appearance of the labyrinthine fluids. Third, differentiation of the sensory epithelium. Tectorial membrane morphogenesis is closely related to the apocrine secretory activity of the greater and lesser epithelial ridges in the 50 mm c.r.l. specimen. In the 70, 110 and 120 mm c.r.l. specimens the secretory activity rests on the interdental cells of the spiral limbus, the undifferentiated cells of Corti's primordium and in the most external cells of the lesser epithelial ridge.

Cochlea↗
PubMedDate not supplied

Clinicopathological factors in early squamous cell carcinoma of the tongue and floor of the mouth, in Biscay (the Basque Country, Spain).

OBJECTIVES: A study is made of the main clinicopathological factors in squamous cell carcinoma (SCC) of the tongue and floor of the mouth in the province of Vizcaya (Biscay) (The Basque Country, Spain), and their relation to patient prognosis. DESIGN: A retrospective study was made of 40 patients with early (clinical stage I/II) SCC of the tongue and floor of the mouth. A previously designed protocol was used to record the clinical and histopathological data, which were subjected to descriptive and comparative bi- and multivariate statistical and survival analyses. RESULTS: There were 34 males and 6 females, with a mean age of 55.7 years (range 33-81). In 23 cases the SCC was located in the tongue, and in 17 cases in the floor of the mouth. The average tumor diameter was 2.6 cm; 65% of the neoplasms were ulcerated. The mean clinical course was 3.4 months, with an average tumor growth rate or velocity of 268 (Evans formula). Thirty-four patients were smokers and 33 consumed alcohol. All SCC of the floor of the mouth, and all regional recurrences, were diagnosed in smokers and drinkers. Survival at 5 years was 65%. Well differentiated SCC were diagnosed in 52.5% of cases. The average histological malignancy grade was 1.96, and was higher in males, tongue malignancies, T2 lesions, tumors with growth velocities above 200, and in recurrent neoplasms. CONCLUSIONS: Early SCC of the tongue and floor of the mouth in Vizcaya affects mainly male smokers and drinkers of alcohol under the age of 60 years. A relationship is observed between the histopathological findings (particularly invasion mode and stage) and patient prognosis.

Adult↗
PubMedDate not supplied

Effects of maternal administration of alcohol on fetal brain development.

The effects of oral administration of alcohol during pregnancy and lactation on fetal and neonatal development were determined. Female Wistar rats were pair-fed nutritionally adequate liquid diets containing either alcohol or isocaloric carbohydrates starting on day 1 of gestation. Blood alcohol levels were determined in the pregnant animals throughout the experiment. On the day of parturition the litters were culled to six. The pups were sacrificed on day 30 and gamma-glutamyl transpeptidase (gamma GTP) activity determined in liver and brain. gamma GTP activity was determined to be elevated in the alcohol treated rats in all areas of brain studied except in the cortex and striatum. Additionally, the alcohol treated animals were smaller than the controls and exhibited higher serum and liver gamma GTP activities. Routine light microscopic plastic sections revealed large vacuolated spaces mainly confined to cortical layer V in the alcoholic rats. Golgi studies also revealed a decreased number of dendritic spines on pyramidal cell dendrites in the alcohol treated animals. These data suggest that exposure to alcohol in utero and in the postnatal period has a dramatic effect on neurons and processes in the cerebral cortex as well as on the membrane bound enzyme, gamma GTP.

Alcohol Drinking↗
PubMedDate not supplied

[Hemodynamic changes caused by prazocin in patients with uncomplicated arterial hypertension].

Hemodynamic changes produced by prazosin were evaluated in 19 patients with mild non complicated essential hypertension using M mode echocardiography. Patients received an initial dose of the drug of 0.5 mg tid, which was augmented gradually. As a whole, arterial pressure was reduced significantly. Heart rate did not show changes. Telediastolic and stroke volumes augmented significantly (p less than 0.05) and consequently cardiac output was increased. Systemic vascular resistance decreased notably (p less than 0.01). Left ventricular function indexes (EF, % shortening, Vcf) were not modified at all. These findings suggest that prazosin is a good antihypertensive drug and its actions upon the different hemodynamic parameters in normal and non complicated hypertensive patients are complex. Generally, it decreases systemic vascular resistance, without modification of contractility. Decreases in afterload were evident and something interesting, in contrast with other papers, is the demonstration of an augmented telediastolic volume, which indicates that the venodilatator effect with the consecutive decrease in blood return to the heart is masked by other effects. Nevertheless, it is necessary to perform a more detailed study with more sensitive methods in order to elucidate the complex hemodynamic interactions produced by prazosin in patients with mild non complicated essential hypertension.

Adult↗
PubMedDate not supplied

[Simplified method of obtaining the correction factor for calculating ventricular volumes].

For the accurate measurement of ventricular volume it is required the obtainment of a correction factor for the magnification caused by the non-parallel X-rays and the "pincushion" distortion, which causes more magnification in the periphery than in the center of the fluoroscopic field. The Kasser and Kennedy method is based in the attainment of the relation between the actual and projected dimensions of a micrometrically calibrated grid filmed at the distance measured between the intensifier tube and the mid-thoracic line during the ventriculography. This technique is very accurate but expensive and troublesome. With the simpler catheter method it is obtained the relation between the projected and actual linear dimensions of the ventriculographic catheter inmediately before ventriculography. This study was aimed to compare the accuracy of the catheter method and two other proposed methods, in which the relation between the projected and actual dimensions were obtained by filming one central coin or five arranged through the fluoroscopic field at the distance measured between the tube and the patients during the ventriculography. These four correction factors were obtained in 15 patients undergoing a diagnostic cardiac catheterization. The catheter method showed a poor correlation with the grid method (r = 0.34), while both coin methods showed a high correlation with the grid method (r = 0.93 and 0.92, respectively). It is concluded that the catheter method is inaccurate and therefore is unwise to use it for the estimation of ventricular volumes. Because the peripheric distortion is clinically unimportant, the central coin methods is proposed as a simplified method for obtaining the magnification correction factor.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗
PubMedDate not supplied

[Ventricular rigidity in mitral stenosis measured by an echocardiographic and hemodynamic method].

Ten patients with mitral stenosis underwent right and left heart catheterization. In order to assess the diastolic properties of these ventricles an hemodynamic-echocardiografic techniques was employed. Left ventricular pressure and an echocardiogram of the body of the left ventricle were simultaneously registered. Ventricular volume was determined using the minor axis (T) of the left ventricle measured form the echogram and assuming the long axis (L) from the L to T relationship observed in the left cineventriculography. Using a microcromputer, a smoothed volume-time curve was obtained, together with its first derivative and a pressure-volume loop. The exponential portion of the diastolic loop was used to obtain a felt ventricular stiffness index at zero volume. End diastolic volume and ejection fraction were normals. Left ventricular filling was impaired but ventricular stiffness was found in the normal range. It is concluded that the proposed method permits the simultaneous obtention of pressure volume data. The processing of complex data can be achieved with a pocket microcomputer. There is no evidence of a left ventricular compliance defect in mitral stenosis.

Adult↗
PubMedDate not supplied

[The hostility complex and myocardial infarct].

Several studies have associated the hostility complex (part of type A personality) to the development of coronary atherosclerosis. The complex is composed by aggressive behavior, frequent rage outbursts, intolerance to waiting lines and sense of urgency. To investigate the occurrence of this behavioral trait, 50 post-myocardial infarction men were compared against 50 normal male subjects of the same age. In all of them sphygmomanometric blood pressure was obtained, total blood cholesterol was measured and hostility was quantified by means of the Cook and Medley's questionnaire and an arbitrary ad hoc scale. Diastolic blood pressure was significatively higher in post-infarction patients (82 +/- 10 vs 77 +/- 9, p < 0.001), as well as the cholesterol level (231 +/- 55 vs 197 +/- 43, p < 0.001). Also, hostility score was higher in the post-infarcted men (16 +/- 4 vs 13 +/- 5, p < 0.001). The hostility score showed correlation with the occurrence of myocardial infarction (p < 0.02). These results establish that post-myocardial infarction patients express more hostility than control subjects. It was not possible to establish the true nature of the relationship among hostility and diastolic blood pressure, total cholesterol and the occurrence of coronary events. Nevertheless, this study confirms that the hostility complex is frequently present in atherosclerotic patients.

Adult↗
PubMedDate not supplied

[Diagnostic and interventional heart catheterization through the radial artery].

Diagnostic and interventional cardiac catheterization using the femoral approach demands hospitalization for more than 24 hours, and occasionally it is complicated by vascular events. This paper informs about out first 95 catheterizations using the radial percutaneous approach. We describe the technique, duration, length of hospitalization and complications. Eighty three male and 12 female patients, aged 54 +/- 12 years were included, 87 of them with coronary heart disease. There were 71 diagnostic procedures, 11 PTCA and 13 elective stenting. The initial success rate was 63% that reached 97% after three months. The mean duration was 46' for diagnostic procedures, 51' for PTCAs and 87' for stenting. Hospitalization length was 5, 31 and 39 hours respectively. Three patients lost the radial pulse, without distal ischemia. Pain was noticed in 16% of the cases. There were not other vascular complications. It is concluded that the percutaneous radial artery approach allows diagnostic and therapeutic procedures, with lesser hospitalization lengths and few vascular complications.

Adult↗