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Biomedical subjects

F A Lee

Publications and source records attributed to F A Lee.

At least 19 recordsLinked to original sources
PubMed1992

Oxidative metabolism and mechanical function in reperfused neonatal pig heart.

Oxidative metabolism in reperfused neonatal myocardium has not been characterized. A blood-perfused isovolumic heart preparation was used to quantify metabolic and mechanical responses of the neonatal left ventricle to global normothermic ischemia and reperfusion. Hearts from piglets aged 2-7 days were subjected to either 2 hrs of total ischemia at 37 degrees C followed by 1 hr of reperfusion or 3 hrs of perfusion alone; glucose and palmitate oxidation were measured in separate experiments by incorporation of the appropriate [14C]-labeled substrate into the perfusate. In the pre-ischemic period, glucose, palmitate, and lactate contributed 10%, 41%, and 36%, respectively, to oxidative metabolism. After 2 hrs of total normothermic ischemia, oxidation of exogenous glucose was 165% and 229% of control values at 30 and 60 minutes of reperfusion, respectively; palmitate oxidation was 110% and 143% of control values at these times. Despite increased glucose oxidation, palmitate oxidation accounted for 69% of myocardial oxygen consumption after 1 hr of reperfusion, with glucose responsible for 25%. Lactate use was minimal during reperfusion. Reperfusion was accompanied by rapid and parallel recovery of oxygen utilization, mechanical function, and high-energy phosphates. The neonatal piglet heart demonstrates significant metabolic and mechanical tolerance to prolonged ischemia. Although glucose utilization increased markedly, palmitate was the primary substrate for energy production in the post-ischemic neonatal heart.

Animals↗
PubMed1992

Hemodynamics of the right ventricle in normal and disease states.

The physiology and hemodynamic functions of the right ventricle in normal and disease states differ considerably from those of the left ventricle. To illuminate these differences, the right ventricle's essential functions in the normal circulation are reviewed, its functional anatomy and blood supply are described, principles and methods of systolic function assessment are discussed, and hemodynamic adaptations to selected diseases causing chronic right-side volume and pressure overload are highlighted.

Heart Diseases↗
PubMed1990

Onset of altered interventricular septal motion during cardiac surgery. Assessment by continuous intraoperative transesophageal echocardiography.

Abnormal motion of the interventricular septum is frequently observed after uncomplicated cardiac surgery. We sought to elucidate the mechanism underlying this phenomenon by using continuous echocardiographic imaging of the heart from a constant transesophageal location in 21 patients undergoing their first cardiac operation. Quantitative global and regional functional analyses were performed in each patient at baseline (stage 1), after median sternotomy (stage 2), after sternal retraction (stage 3), after pericardiotomy (stage 4), after completion of cardiopulmonary bypass (stage 5), and after chest closure (stage 6). During the first four surgical stages, mean left ventricular fractional shortening varied little among regions with a fixed reference system (maximum range, 31.6-39.2%; p = NS) but changed dramatically after the discontinuation of cardiopulmonary bypass (stage 5). The apparent medial hypokinesis that was observed (4.9 +/- 4.7% [SD]) was accompanied by lateral hyperkinesis (65.2 +/- 4.1%, p less than 0.0001). These regional differences were completely eliminated with a floating reference system (33.6 +/- 2.7% for medial, and 34.8 +/- 1.7% for lateral; p = NS), suggesting cardiac translation. Quantitative curvature analysis supported this conclusion, with preservation of baseline regional curvature seen throughout the procedure. The mean length of individual translational vectors (reflecting systolic movement of the endocardial centroid) remained minimal (less than or equal to 1.0 mm) through stage 4 but increased more than fourfold at stage 5, continuing in a medial direction after chest closure (5.2 +/- 3.0 mm and 271 +/- 6 degrees from anterior). Thus, abnormal postoperative septal motion is not caused by removal of restraining forces of the pericardium or anterior mediastinum but rather appears to be directly related to events occurring during cardiopulmonary bypass.

Cardiac Surgical Procedures↗
PubMed1988

Peak filling rate normalized to mitral stroke volume: a new Doppler echocardiographic filling index validated by radionuclide angiographic techniques.

The noninvasive measurement of left ventricular filling has relied predominantly on radionuclide-derived peak filling rate normalized to end-diastolic volume. Doppler echocardiography also has the ability to measure peak filling rate, but wide application of this technique has been limited by technical errors involved in quantitative echocardiographic determination of mitral anulus cross-sectional area and ventricular volumes. For Doppler echocardiography, normalization of peak filling rate to mitral stroke volume rather than end-diastolic volume permits the derivation of a diastolic filling index that is relatively free of errors caused by geometric assumptions, diameter measurements and sample volume positioning. This normalization process can be achieved by simply dividing early peak filling velocity by the time velocity integral of mitral inflow. To validate this new Doppler echocardiographic filling index, Doppler echocardiographic and radionuclide-derived peak filling rate, both normalized to mitral stroke volume, were compared in 30 patients; there was an excellent correlation (r = 0.91, SEE = 0.88). This variable was not influenced by the position of the sample volume in relation to the mitral apparatus in contrast to early filling velocity, which increased 37%, and early/late filling (E/A) ratio, which increased 43% as the sample volume was moved from the anulus to the tips of the mitral leaflets. In a cohort of 22 normal patients, the mean peak filling rate normalized to mitral stroke volume (SV) was 5.25 +/- 1.47 SV/s. The mean peak filling rate for a subgroup of eight normal patients aged 57 to 89 years (mean 71 +/- 9) was 3.9 +/- 1 SV/s.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Treatment of the hemodynamically unstable patient.

The pathogenesis, diagnosis, and management of six clinical syndromes associated with acute myocardial infarction and hemodynamic instability are discussed: (1) autonomic disturbances with hypertension-tachycardia or hypotension-bradycardia; (2) pulmonary edema; (3) cardiogenic shock; (4) right ventricular infarction; (5) rupture of ventricular free wall or septum; and (6) papillary muscle rupture.

Cardiotonic Agents↗
PubMed1986

Para-aortic node biopsy in cervical and endometrial cancers: does it affect survival?

Two hundred ten patients with endometrial and cervical carcinoma had para-aortic node biopsies. Nineteen of the 210 patients (9.0%) had positive para-aortic nodes. These 19 patients received pelvic irradiation, and 18 patients received para-aortic irradiation. The incidence of para-aortic nodal involvement in cervical carcinoma was directly related to the stage of the disease. Eleven of the 12 patients with cervical carcinoma and positive para-aortic nodes received both pelvic and para-aortic irradiation. Three of these patients are alive without disease, resulting in a survival rate of 25%. These patients are surviving for 16, 30, and 41 months. The incidence of positive para-aortic nodes in endometrial adenocarcinoma was related to the uterine length and the histologic grade. The survival rate for patients with endometrial adenocarcinoma and positive para-aortic nodes in this study was 57.1%. Four patients have survived for 1, 30, 60, and 71 months. There were no surgical deaths or radiation therapy complications directly attributable to para-aortic biopsy or irradiation.

Adenocarcinoma↗
PubMed1985

Early costochondral calcification in adolescent hyperthyroidism.

The finding of extensive costochondral calcification in five adolescents, aged 14-16 years, with hyperthyroidism prompted a retrospective study of all young persons with this condition seen in the last 10 years. Thirty-six patients with hyperthyroidism (ages 13-18 years) were evaluated. Of 32 thyrotoxic teenage girls, 21 (66%) showed some degree of calcification, compared with 73 of 600 (12%) in the control group. Only four boys were evaluated, but one had grade 2 (mild) calcification that was not seen in any boy in the control group. Costochondral calcification increases with age and continues throughout life, reflecting the aging process. The much higher incidence of early costochondral calcification in thyrotoxic adolescents than in the general population is a radiographic indication of advanced bone maturation not previously recognized.

Adolescent↗
PubMed1983

Brief clinical communication: neurogenic perineal prolapse in neonates.

Disturbed innervation of the pelvic muscular diaphragm from lumbosacral myelodysplasia and other osseous dysplasias results in flaccid paralysis of the perineum. This permits excessive downward herniation, most noticeable in neonates, of the lower abdominal and pelvic organs. The radiographic changes occurring with organ descensus may be transitory and diverse, and recognition of these various findings is important to avoid misdiagnosis and unnecessary further investigations. Several examples of the radiographic changes are presented.

Bone Diseases, Developmental↗
PubMed1980

Radiation therapy treatment of stage I and II extranodal non-Hodgkin's lymphoma of the head and neck.

We have reviewed the records of 76 patients with Stage I or II extranodal non-Hodgkin's lymphoma who were referred to the Division of Radiation Oncology, Mallinckrodt Institute of Radiology, during the years 1964 through 1974. The histologic slides were reviewed in the 67 cases in which they were available. Forty-three percent of Ann Arbor Stage I and II patients relapsed after primary radiation treatment.Seventy-three percent of these failed in sites distant from the irradiated volume. Failures in the treated volume were infrequent (7%) except in those patients presenting with primary lesions of the brain (4/5). Those patients presenting with lesions of Waldeyer's ring experienced a decrease in survival with increasing tumor size. Because of the high rate of failure in distant sites with tumors in the lingual and palatine tonsils, we are recommending the study of adjuvant chemotherapy in these cases, after primary radiation treatment.

Adolescent↗
PubMed1977

Combined treatment modalities of rhabdomyosarcoma in children.

Thirty-nine previously untreated children with rhabdomyosarcoma were managed by a coordinated program of surgery, radiation therapy, and chemotherapy during the years 1960 to 1973. The primary tumor was located in the head and neck (24), chest wall (1), abdomen (1), pelvis (10), and lower extremity (3). Radiation therapy consisted of tumor doses of 5000 to 6000 rads delivered in five to six weeks. Combination chemotherapy with actinomyctin-D, vincristine and cyclophosphamide was used after 1968. Seventeen of 25 cases (68%) treated after 1968 are alive two to five years following treatment. Only four of 14 cases (29%) who received less radical therapy before 1968 are alive. A relatively high incidence of local failure (23%) was noted in spite of adequate doses of radiotherapy. None of the four cases with metastatic disease at the time of diagnosis survived. Major complications were mainly noted in patients with orbital rhabdomyosarcoma. Correlation of absolute survival with dose of irradiation, primary site, extent of disease and histologic subtypes of the tumor are discussed.

Adolescent↗
PubMed1977

Radiographic features of fucosidosis.

Fucosidosis is an uncommonly recognized lysosomal storage disease which presents with psychomotor deterioration and progressing in some cases to death. The roentgenographic findings in five boys from three families are described. Skeletal abnormalities of a dysostosis multiplex nature are present and though not diagnostic should direct the clinician to perform appropriate biochemical and tissue assay studies to establish the diagnosis.

Adolescent↗