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Biomedical subjects

S Hirschfeld

Publications and source records attributed to S Hirschfeld.

48 records · Page 3Linked to original sources
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

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

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

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↗
PubMed1975

Measurement of right and left ventricular systolic time intervals by echocardiography.

One of the noninvasive methods of evaluating left ventricular performance is the measurement of left ventricular systolic time intervals (LVSTI). However, noninvasive measurement of right ventricular systole by this technique has been unreliable because of the inability to accurately time the onset of right ventricular ejection. Excellent correlation of LVSTI measured from the carotid pulse and those determined from the echocardiogram was demonstrated in 15 patients. STI of the right ventricle (RVSTI) were measured in a similar fashion from the pulmonary valve echo in 11 normal children. Right ventricular ejection time (RVET) was longer than left ventricular injection time (LVET). Right ventricular pre-ejection period and RPEP was shorter than left ventricular pre-ejection period (LPEP). In 15 children with transposition of the great arteries (TGA) the situation was reversed. RVET was shortened and RPEP was prolonged as the right ventricle contracted against systemic resistance; whereas, the LVET lengthened and LPEP shortened with ejection into a low pressure pulmonary circuit. Our studies in a total of 41 patients indicate the accurate, noninvasive measurement of right, as well as left, ventricular STI can be obtained with the use of echocardiography.

Adolescent↗
PubMed1975

The echocardiographic assessment of pulmonary artery pressure and pulmonary vascular resistance.

Serial assessment of the status of the pulmonary vascular bed requires bed requires cardiac catheterization. We have demonstrated the right ventricular systolic time intervals (RVSTI) may be measured from the pulmonary valve echo. The right ventricular ejection time (RVET) and right pre-ejection period (RPEP) were measured in 45 normal patients. The RVET and RPEP decreased with increasing heart rate but increased with age. The RPEP/RVET, however, was uninfluenced by either age or heart rate. The RPEP/RVET was, therefore, determined from the pulmonary valve echo in 64 patients with congenital heart disease who underwent cardiac catheterization. Increased pulmonary artery diastolic pressure (PADP), pulmonary vascular resistance (PADP), pulmonary vascular resistance (PVR) and mean pulmonary artery pressure (MPAP) resulted inan increased RPEP/RVET. The use of the RPEP/RVET permitted the serial echographic evaluation of the pulmonary vascular bed in selected patients; marked elevation of the ratio indicated the presence of pulmonary hypertension.

Adolescent↗
PubMedDate not supplied

Induction of a novel damage-specific DNA binding protein correlates with enhanced DNA repair in primate cells.

Pretreatment of mammalian cell with DNA-damaging agents, such as UV light or mitomycin C, but not the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA), results in the enhanced repair of subsequently transfected UV-damaged expression vectors. To determine the cellular factors that are responsible for this enhancement, we have used a modified gel retardation assay to detect the proteins that interact with damaged DNA. We have identified a constitutive DNA binding protein in extracts from primate cells that has a high affinity for UV-irradiated double-stranded DNA. Cells pretreated with UV light, mitomycin C, or aphidicolin, but not TPA or serum starvation, have higher levels of this damage-specific DNA binding (DDB) protein. These results suggest that the signal for induction of DDB protein can either be damage to the DNA or interference with cellular DNA replication. The induction of DDB protein varies among primate cells with different phenotypes: (1) virus-transformed repair-proficient cells have partially or fully lost the ability to induce DDB protein above constitutive levels; (2) primary cells from repair-deficient xeroderma pigmentosum (XP) group C, and transformed XP groups A and D, show constitutive DDB protein, but do not show induced levels of this protein 48 h after UV; and (3) primary and transformed repair-deficient cells from one XP E patient are lacking both the constitutive and the induced DDB activity. The correlation between the induction of the DDB protein and the enhanced repair of UV-damaged expression vectors implies the involvement of the DDB protein in this inducible cellular response.

Animals↗
PubMedDate not supplied

Diverse roles of insulin-like growth factors in pediatric solid tumors.

Insulin-like growth factors are abnormally expressed in some pediatric solid tumors. In addition, tumors that do not show significant alterations in pattern of expression are responsive to and may be dependent upon insulin-like growth factors for proliferation. These can be produced by the tumor cells (autocrine), surrounding stromal cells (paracrine), or at a distance (endocrine). Insulin-like growth factor-II plays a role in Wilm's tumor, neuroblastoma, and rhabdomyosarcoma, either as a proliferation factor, a motility factor, or both. Insulin-like growth factor-I may regulate osteosarcoma and the Ewing's family of tumors (primitive neuroectodermal tumors). Understanding the biology of these growth factors and their receptors can lead to new therapeutic approaches.

Adult↗