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Biomedical subjects

J Liebman

Publications and source records attributed to J Liebman.

At least 73 records · Page 4Linked to original sources
PubMed1978

Antagonism by mianserin and classical alpha-adrenoceptor blocking drugs of some cardiovascular and behavioral effects of clonidine.

Antagonism of pressor responses to sympathetic outflow stimulation and alpha-adrenoceptor agonists in pithed spontaneously hypertensive rats was used to estimate postsynaptic alpha-adrenoceptor blocking activity of mianserin, phentolamine, phenoxybenzamine, piperoxan and yohimbine. Estimation of presynaptic alpha-adrenoceptor blocking activity of these drugs was obtained by studying their ability to antagonize clonidine-induced suppression of positive chronotropic responses to sympathetic outflow stimulation. In this manner, evidence was obtained that mianserin causes selective presynaptic alpha-adrenoceptor blockade. Mianserin, piperoxan and yohimbine antagonized clonidine-induced avoidance blockade or hypotension in spontaneously hypertensive rats, but methysergide, phenoxybenzamine and phentolamine were ineffective. These results suggest that mianserin may antagonize the central effects of clonidine by blockade of noradrenergic presynaptic or autoreceptors and possibly explain the antidepressant effect of mianserin as due to indirect activation of central noradrenergic neurons.

Adrenergic alpha-Antagonists↗
PubMed1978

Idiopathic familial myocardiopathy in three generations: a clinical and pathologic study.

A peculiar non-hypertrophic myocardiopathy is described which occurred in three and possibly five generations of a single family. Clinical features included systolic murmurs, electrocardiographic abnormalities, and sudden cardiac death with a paucity of symptoms of cardiac dysfunction. Pathological studies in three generations showed a striking similarity of cardiac findings including globular and dilated ventricles, endocardial fibroelastosis, and mitral valve thickening. Myocardium in two showed basophilic degeneration and fibrosis. A retrospective genealogic analysis and a prospective clinical evaluation of living family members suggested an autosomal dominant mode of inheritance with variable penetrance. The cause of this heritable myocardiopathy is presumably a mutant gene; the biochemical defect to which the mutant gene gives rise remains unknown.

Adolescent↗
PubMed1978

Assessment of the pulmonary vascular bed by echocardiographic right ventricular systolic time intervals.

Echocardiography was used to measure right ventricular systolic time intervals (RVSTI) in 85 normal children (group I) and in 229 patients undergoing cardiac catheterization (group II). Corrected right ventricular pre-ejection period (RPEPC) and right ventricular ejection time (RVETc) (based on regression analysis of group I) and RPEP/RVET were each correlated with pulmonary artery (PA) diastolic and mean pressures and pulmonary vascular resistance (PVR). The best correlation (0.83) was between a second degree polynomial of the RPEP/RVET and PA diastolic pressure. The RPEP/RVET allowed prediction of PA diastolic pressure within 10 mm Hg in 85% of the patients. The utility of RPEP/RVET was confirmed in sequential data of 22 patients, in whom alteration in RPEP/RVET accurately reflected the changing PA diastolic pressure. The RPEP/RVET could not be used to assess PA pressure in six patients with congestive cardiomyopathy nor in 18 patients with complete right bundle branch block (CRBBB).

Adolescent↗
PubMed1978

Population based planning as a tool for health plan development.

Population based planning is an appealing methodology for the development of a people-oriented health systems plan. By focusing on the identification and minimization of the social, behavioral, and environmental risks to ill health, population based planning is compatible with the growing understanding of the social origins of health and disease. Models of both population based and resource based planning are presented and used to define the concepts and contrast the two methodologies. To strengthen the population based planning model, Kessner's tracer methodology is incorporated into the technique. Finally, the benefits (focus on the social origins to disease) and the drawbacks (extensive time and data requirements) of population based planning are highlighted.

Health Planning↗
PubMed1978

Comparison of exercise and catheterization results following total surgical correction of tetralogy of Fallot.

Although surgery may correct the hemodynamic abnormalities of tetralogy of Fallot (TOF), the long-term effects on exercise tolerance are uncertain. Twenty-eight patients, aged 7 to 30 years, had cardiac catheterization and maximal graded exercise testing to evaluate the adequacy of the ehmodynamic repair and its relation to exercise performance. Patients were tested 2 to 9 years after operation, and 13 previously had had palliative shunt procedures. At catheterization, 23 of the 28 patients had good surgical results. Despite the satisfactory hemodynamics, maximal working capcity (MWC), maximum heart rate, and exercise blood pressure were diminished when compared to normal values. In 10 patients who had exercise studies at catheterization, right ventricular systolic pressure (RVSP) and residual gradients were magnified by exercise. Abnormalities were independent of age at time of correction, time elapsed since surgery, use of patch in the outflow tract, or any antecedent procedures.

Adolescent↗
PubMed1978

Echographic ventricular systolic time intervals in normal term and preterm neonates.

Right ventricular and left ventricular systolic time intervals (RVSTIs and LVSTIs) were measured in normal term and preterm infants from 1 hour to 90 days of life. LVSTIs in both term and preterm infants were similar in the first five days of life. The ratio of left pre-ejection period (LPEP) to left ventricular ejection time (LVET) was lower in preterm infants older than age 5 days. Estimated gestational age had no influence on LVSTI. The ratio of right pre-ejection period (RPEP) to right ventricular ejection time (RVET) was lower in preterm infants (0.32) than in term newborns (0.37). The preterm RPEP/RVET ratio decreased with age, but at a slower rate than in term babies. This was consistent with the lower pulmonary vascular resistance present in preterm infants.

Echocardiography↗
PubMed1977

Differential effects of morphine and D-amphetamine on self-stimulation from closely adjacent regions in rat midbrain.

The effects of morphine were investigated on self-stimulation from numerous electrode placements in the area of the substantia nigra or in the ventral half of mesencephalic central gray matter. Before pharmacological testing, current intensity was reduced to yield stable, submaximal rates of self-stimulation. Rats were then injected daily with morphine for 10 days, and were tested three hours after injection. Between days 5 and 10 of treatment, many rats self-stimulated at more than 150% of baseline, but some others reduced self-stimulation to as little as 3% of baseline. Histological evaluation revealed that morphine facilitated self-stimulation when the electrode tip was located more than 0.3 mm from substantia nigra or more than 0.2 mm from the midline of central gray. In rats with electrode tips closer to substantia nigra or to the midline of central gray, morphine often reduced or failed to alter self-stimulation rates. The effects of a low dose of D-amphetamine (0.1 mg/kg) were investigated on electrode placements in the substantia nigra area. Placements close to the dorsal border of substantia nigra yielded less facilitation of self-stimulation by D-amphetamine than did placements located more dorsally or medially. Possible catecholaminergic substrates of these differential effects are discussed.

Animals↗
PubMed1977

Resolution of surgically induced right bundle-branch block.

In a retrospective study, the serial electrocardiograms of all patients with surgically induced right bundle-branch block (RBBB) were reviewed. None of these patients had had RBBB prior to operation. Seven patients who had RBBB from 6 to 16 days after operation showed resolution in ECGs done 3 to 8 months later. Two patients are reported, with documentation by vectorcardiogram, in whom RBBB resolved by 3 and 12 years after operation. The origin of transient forms of RBBB may be different from the long-standing form. If RBBB of long duration is due to operative injury to the proximal right bundle, Purkinje fiber network, or distal branch or branches of the right bundle, or to combinations of these tracts, one may speculate about the possibility of regeneration of the right ventricular conduction system. Since no data are available concerning the long-term prognosis of RBBB and since a progressive conduction disturbance can occur, the resolution of RBBB after many years might carry a better prognosis than its persistence.

Adolescent↗
PubMed1977

Persistence of fetal circulation syndrome: an echocardiographic study.

Serial echocardiograms were performed on 17 infants with persistence of fetal circulation syndrome to measure right ventricular systolic time intervals from pulmonic valve echograms and left ventricular systolic time intervals from aortic valve echograms. Right ventricular pre-ejection period/right ventricular ejection time ratio was prolonged in PFCS when compared to that in normal newborn infants, and diminished with clinical improvement. Left ventricular pre-ejection period/left ventricular ejection time ratio was prolonged in infants with PFCS. Echographic RPEP/RVET was consistent with the elevated pulmonary artery pressure and pulmonary vascular resistance of PFCS; elevated LPEP/LVET suggested left ventricular dysfunction.

Blood Circulation↗
PubMed1977

Quantification of the normal Frank and McFee-Parungao orthogonal electrocardiogram at ages two to ten years.

A quantification of the Frank and McFee-Parungao orthogonal electrocardiogram of 175 normal children, ages 2-10 years is presented. There are significant differences in age groups 2-5 and 6-10. The QRS voltages of the younger group demonstrate 1) greater Z anterior, 2) greater initial X right, 3) greater terminal X right, 4) smaller Y inferior, and 5) the T vector is oriented more posteriorly. There are significant differences between the two lead systems. 1) Frank spatial voltages are 70% of those of McFee. 2) Frank X left is 70% of McFee, but terminal X right is 75% and initial X right is 60% of McFee. 3) Frank Y inferior is 78% of McFee, but initial Y superior is 83% and terminal Y superior 61% of McFee. 4) Frank Z anterior is 64% and Frank Z posterior is 70% of McFee. 5) In terms of ratios the Frank is relatively less inferior, about equally posterior and more terminally right. 6) The T vector is more posterior in Frank than McFee.

Age Factors↗
PubMed1977

Intracardiac pressure-sound correlates of echographic aortic valve closure.

Echographic aortic valve closure was compared to the dicrotic notch of the aortic pressure and intracardiac A2 to define the exact temporal relationship of the echographic, pressure, and sound parameters of aortic valve closure. Sixteen children, ages 3--20 years, were evaluated by simultaneous aortic valve echograms, micromanometric aortic root pressure tracings, and intracardiac phonocardiograms recorded at paper speeds of 200 mm/sec. Our observations demonstrated that echographic coaptation of the aortic valve leaflets coincides with the trough of the aortic pressure incisura and the onset of A2. The data suggest that A2 is a result of valve closure.

Adolescent↗
PubMed1977

Neonatal circulatory changes: an echocardiographic study.

Serial echocardiograms were performed in the first three days of life on 38 normal full-term infants. Right ventricular systolic time intervals were measured from the pulmonic valve echogram and left ventricular systolic time intervals were determined from the aortic valve echogram. The heart rate, left ventricular pre-ejection period (LPEP), left ventricular ejection time (LVET), and LPEP/LVET ratio showed insignificant variation with increasing postnatal age. The right ventricular pre-ejection period (RPEP) shortened, the right ventricular ejection time (RVET) lengthened, and the RPEP/RVET ratio decreased with increasing age. The findings suggested that alterations in the RPEP/RVET ratio reflected the decreasing pulmonary artery diastolic pressure and pulmonary vascular resistance of the early neonatal period and may be valuable in the noninvasive evaluation of the newborn's pulmonary vascular bed.

Age Factors↗
PubMed1977

Respiratory distress syndrome: echocardiographic assessment of cardiovascular function and pulmonary vascular resistance.

Echocardiograms were performed for 82 preterm infants comprising 22 normal infants, 29 with mild respiratory distress syndrome (RDS), and 31 with severe RDS. Left ventricular systolic time intervals were measured from aortic valve echograms and right ventricular systolic time intervals from pulmonic valve echograms. Left ventricular performance seemed to be altered early in postnatal adaptation of preterm infants, but played no demonstrable role in the outcome of RDS. The right ventricular preejection period/right ventricular ejection time (RPEP/RVET) ratio was prolonged in 17 out of 31 patients with severe RDS, consistent with increased pulmonary vascular resistance or right ventricular dysfunction. Prolonged RPEP/RVET identified a subgroup with increased mortality and morbidity.

Echocardiography↗
PubMed1976

Right ventricular growth in a case of pulmonic stenosis with intact ventricular septum and hypoplastic right ventricle.

Adequate growth of the hypoplastic right ventricle in a patient with severe pulmonary stenosis with an intact ventricular septum was documented after pulmonary valvotomy in infancy. It is postulated that the growth of the ventricular chamber is largely the result of pulmonary regurgitation resulting from successful pulmonary valvotomy. Based on this and the observations of others on the growth of the hypoplastic right ventricle in pulmonary atresia (with intact septum) cases, an organized approach to eventual total surgical correction is recommended.

Child↗
PubMed1976

The isovolumic contraction time of the left ventricle. An echographic study.

The echographic isovolumic contraction time (ICT) of the left ventricle (LV) was measured in order to assess alterations of LV performance in children with various forms of cardiac disease. The echographic ICT was defined as the interval between coaptation of the anterior and posterior mitral valve leaflets and aortic cusp opening. Four groups of patients were evaluated: normal (48); LV myocardial disease (20); patent ductus arterosus (PDA) (19); and aortic stenosis (AS) (15). In normal children ICT shortened with decreasing age and increasing heart rate. Isovolumic contraction time was more influenced by heart rate (HR) than age, but the relationship was still weak (r = 0.61). In patients with LV myocardial disease ICT was markedly prolonged, while in children with patent ductus arteriosus and aortic stenosis it was shortened as compared with normal children (P less than 0.01).

Adolescent↗