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Biomedical subjects

D G Pavel

Publications and source records attributed to D G Pavel.

At least 19 recordsLinked to original sources
PubMed1995

Successful methylphenidate treatment of apathy after subcortical infarcts.

A patient with prominent apathy secondary to multiple subcortical infarcts was treated successfully with methylphenidate. SPECT and reaction time testing showed selective improvement of frontal system function, consistent with a recent model of frontal-subcortical circuits and behavior.

Activities of Daily Living↗
PubMed1995

Postoperative cognitive and single photon emission computed tomography assessment of patients with resection of perioperative high-risk arteriovenous malformations.

We studied the outcome of 10 patients who had undergone high-risk surgery for an arteriovenous malformation at our institution between November 1991 and November 1993. All of the lesions were located in the dominant (left) hemisphere. Perioperative risk was assessed by the location of the lesion in functionally eloquent cortex (seven patients) or deep structures (two patients) or the lesion's large volume (two patients). Our patients included six women and four men, and their ages ranged from 22 to 53 years (mean, 35.8). Our follow-up study included the evaluation of neurological sequelae but mainly emphasized the study of cognitive deficits (seven major functional clusters), the incidence of depression and behavioral changes, and the assessment of regional cerebral blood flow with single photon emission computed tomography. Six patients returned to a seemingly "normal" daily life with some minor deficits postoperatively, three developed contralateral hemiparesis, and one had disabling cognitive deficits. Our comprehensive cognitive assessment, in particular, showed that although patients might appear "normal" on a routine neurological examination, most patients showed a mild deficit in at least one cognitive function and three were severely impaired. In addition, the single photon emission computed tomographic studies pointed out hypoperfusion in more extensive regions than the surgical defects shown by magnetic resonance imaging or computed tomographic studies. These single photon emission computed tomography images helped to explain some of the cognitive and behavioral changes better than the anatomic studies. This information will make it possible for the physician to offer continuing supportive care for the patient in postoperative transition to normal life activities.

Adult↗
PubMed1994

Positive captopril renal scintigraphy in a patient with extensive bilateral renal interlobar arterial disease.

The authors determined an unusual cause of renovascular hypertension in a 29-year-old man with the recent onset of hypertension and a history of intravenous substance abuse. Captopril renal scintigraphy (CRS) demonstrated bilateral renogram changes and a decrease in estimated global glomerular filtration rate. The abdominal aortogram failed to show renal artery or branch artery stenosis. Magnified selective views of the kidneys demonstrated extensive, bilateral, small vessel interlobar disease. Two major points are illustrated in this patient. First, in the presence of positive CRS results and a history of renovascular hypertension, bilateral, selective, magnified renal angiography should be performed in accordance with standard abdominal aortic views when large vessel disease is not detected. Second, although surgical intervention is not an option in such patients, finding the cause of hypertension is important for patient management.

Adult↗
PubMed1994

The accuracy of SPECT brain activation images: propagation of registration errors.

Functional single photon emission computed tomography (SPECT) images of brain activation are based on a comparison of base line and activation images. The correctness of the functional images depends, among other factors, on the accurate spatial registration (alignment) of the base line and activation image data. The relationship between the registration errors and the errors of the resulting functional images is studied. It is shown that misregistration errors as small as a shift by 1/8 pixel or rotation by 1 degree result in 5%-10% errors of the pixel values of functional SPECT images of regional blood flow (the ratio and the relative difference images).

Biometry↗
PubMed1994

The accuracy of SPECT brain activation images: propagation of registration errors.

Functional single photon emission computed tomography (SPECT) images of brain activation are based on a comparison of base line and activation images. The correctness of the functional images depends, among other factors, on the accurate spatial registration (alignment) of the base line and activation image data. The relationship between the registration errors and the errors of the resulting functional images is studied. It is shown that misregistration errors as small as a shift by 1/8 pixel or rotation by 1 degree result in 5%-10% errors of the pixel values of functional SPECT images of regional blood flow (the ratio and the relative difference images).

Brain↗
PubMed1992

Use of radionuclide renal imaging for clinical followup after extracorporeal shock wave lithotripsy of renal stones.

Patients treated by extracorporeal shock wave lithotripsy (ESWL) are usually evaluated by excretory urography within 1 month after treatment to determine the clearance of stone debris and rule out asymptomatic obstruction. In an attempt to obtain more precise functional information, we used 99mtechnetium-diethylenetriaminepentaacetic acid and 131iodine-hippurate radionuclide renal imaging studies, and a plain abdominal radiograph as the initial followup study after ESWL of 64 kidneys in 55 patients. Of 53 kidneys studied within 60 days after ESWL 42 had abnormal radionuclide renal imaging studies demonstrating pelviocaliceal stasis, excretory delay or poor function, 8 of which required subsequent interventions for obstructing stone debris. Five patients had excretory delay after ESWL that was unexpected based on a pre-ESWL excretory urogram showing normal function without dilation. A subset of 23 patients with large stone burden or anatomical deformity from a prior operation had baseline radionuclide renal imaging studies before ESWL; function improved in 4 and worsened in 5 by radionuclide renal imaging studies after completion of treatment. A total of 19 patients had radionuclide renal imaging studies earlier (within 17 days) after ESWL because of poor function and/or large stone burden, and as expected they had evidence of obstruction from stone debris, which necessitated further followup. Our experience suggests that followup of ESWL by radionuclide renal imaging studies provides specific functional information that is of particular value in the management of patients with obstructing stone debris and/or diminished renal function. Radionuclide renal imaging studies may also reveal unsuspected obstruction or functional impairment after ESWL of uncomplicated stones, and is recommended as routine followup after ESWL.

Follow-Up Studies↗
PubMed1991

Localization of human sarcoma with radiolabeled monoclonal antibody--a follow-up report.

A group of 16 sarcoma patients with suspected advanced disease were studied with a radiolabeled anti-sarcoma monoclonal antibody (mAb 19-24) in an attempt to localize tumor deposits. All 16 patients received 125I-mAb 19-24 and then had external-probe analysis and imaging performed. Confirmation of tumor deposits was done at surgery or by autopsy. Tissues were studied in surgical patients when possible and analyzed for radioactivity, and tumor-to-blood ratios ranged from 0.6 to 36.8. In conjunction with the patients previously studied, probe results had an overall sensitivity of 83.3% and an overall specificity of 100%; scintigraphic results showed an overall sensitivity of 78.9% and an overall specificity of 100%. Radiolabeled mAb 19-24 may be developed into a useful tool for clinical immunodetection of sarcoma deposits.

Adolescent↗
PubMed1990

Indium 111-labeled granulocyte scan in the diagnosis and management of acute inflammatory bowel disease.

The indium 111 granulocyte scan was used to evaluate 39 individuals known to have or suspected of having inflammatory bowel disease. Twenty-three of these individuals had positive scans and 16 had negative scans. Eighty-seven confirmatory studies, which consisted of barium radiography, endoscopy, operative findings, and histopathology, were performed in 37 of these individuals. The remaining two negative scans corroborated only by clinical course, CBC, and erythrocyte sedimentation rate. In addition, 10 follow-up scans were performed in six of the 39 patients to monitor therapy or investigate a change in symptoms. As an anatomic indicator of acute granulocytic infiltration of the intestinal lamina propria and crypts, the authors found that this scan had a 97 percent rate of sensitivity and 100 percent specificity. Specific indications for the use of the indium 111-labeled granulocyte scan are described. For the authors, in general, this test has become a vital adjunct to endoscopy and radiography in the diagnosis and management of patients with symptoms of inflammatory bowel disease.

Acute Disease↗
PubMed1987

Pitfalls in diagnosing brain death in infancy.

A 3-year-old child with phenotypic trisomy 18 syndrome survived 26 days after a cardiopulmonary arrest, secondary to an acute viral illness. The child was deeply comatose. No barbiturates, other sedatives, or aminoglycoside antibiotics had been recently administered. The child was normothermic with adequate cardiovascular function. Brain stem function was absent, as assessed by testing of brain stem reflexes. Serial cerebral radionuclide angiograms (CRAG) documented intact cerebral blood flow while electrocerebral silence (ECS) was present on two consecutive EEG recordings within 24 hours. Preservation of intracranial circulation was confirmed by rapid rotational computed tomographic (CT) scans. Cranial CT scans also revealed communicating hydrocephalus, and bilateral basal ganglia hemorrhages. This unusual case illustrates discordance between apparent irreversible loss of cortical function as indicated by electrocerebral silence with preserved cerebral blood flow. The implications of these apparent paradoxical events will be discussed in the context of defining brain death in children.

Brain Death↗
PubMed1986

Localization of human sarcoma with radiolabeled monoclonal antibody. A preliminary study.

The early localization of recurrent or metastatic sarcoma remains a challenging clinical problem. 125I-labeled monoclonal antibody (Mab) 19-24, produced in our laboratories against a human malignant fibrous histiocytoma, has been evaluated for detection of locally recurrent or metastatic disease in selected sarcoma patients. In vitro testing indicated various degrees of positive Mab reactivity with most sarcoma types, and low but significant reactivity with some nonsarcoma tumors and several normal tissues, including liver. The iodine-labeled Mab had an immunoreactivity of 90% and a high binding constant (8.1 X 10(9) M-1). Biodistribution studies of radioisotope in sarcoma patients showed rapid clearance of radiolabeled from the blood and uptake in tumor deposits, liver, and spleen. A differential in radioactivity kinetics between liver and tumor was also found. Serial patient scanning determined optimal imaging time to be between 24 and 48 h after i.v. infusion of the radiolabeled Mab. Analysis of tissues obtained during surgery (including a dual antibody-label study using a nonspecific Mab) showed selective localization of the Mab into the sarcoma deposits. Radiolabeled Mab shows potential as a clinically useful tool for localization of sarcoma deposits.

Adult↗
PubMed1986

Normal cerebral radionuclide angiogram in a child with electrocerebral silence.

Pediatric neurologists agree that the determination of brain death in children, and especially retarded children, is difficult and that the criteria used in adult brain death may not be sufficient in pediatric cases. An unusual case of sustained electrocerebral silence on electroencephalogram (EEG) in a three-year-old retarded comatosed child with preserved intracerebral perfusion documented by a series of cerebral radionuclide angiograms (CRAG) is presented. The EEG showing electrocerebral silence represents loss of cerebrum (cortex) function (Barlow 1976). This absence of cortical function is demonstrated even though intracranial circulation is shown to be intact. We believe that the correlative studies presented accurately document a discordance between apparent loss of cortical function in a child as indicated by electrocerebral silence in the face of preserved cerebral blood flow. It is suggested that when evaluating brain death in retarded children with known cerebral atrophy, special emphasis should be placed on the CRAG and that the EEG should be read with caution.

Brain↗
PubMed1985

Localization of radiolabeled monoclonal antibody in a human soft tissue sarcoma xenograft.

125I-labeled monoclonal antibody 19-24 (mouse isotype IgG1) was evaluated for its potential usefulness in the clinical radioimmunodetection of sarcoma. The antibody reacts with a cell surface antigen preferentially expressed in many human soft tissue and bone sarcomas. Chromatographic and electrophoretic analyses indicated that the labeled preparation was relatively pure. Binding studies in vitro demonstrated that specificity for antigen was retained after iodination and indicated that the labeled antibody possessed an immunoreactivity in excess of 90% and a binding constant of 8.1 X 10(9) M-1. When administered to athymic NCr-nu/nu mice bearing 1-cm diameter human fibrosarcoma HT-1080 xenografts, the labeled antibody preferentially localized in tumor deposits. Maximum tumor-to-blood radioactivity ratios (2.2-3.4) were obtained 7 days after antibody injection. Specificity of the localization was confirmed with a control mouse IgG1 antibody and by using a nonreactive xenograft. Distinct tumor images were obtained by gamma camera without the use of subtraction techniques, demonstrating the possible clinical utility of the labeled antibody.

Animals↗
PubMed1984

A model of cyanotic heart disease: functional, pathological, and metabolic sequelae in the immature canine heart.

To assess the etiology of depressed ventricular function in cyanotic congenital heart disease, an experimental model in immature puppies was devised in which the left atrial appendage is directly anastamosed to the distally banded pulmonary artery. The preparation results in significant cyanosis during a 3-month study period (PO2 = 91 +/- 4 vs 43 +/- 3, hematocrit = 33 +/- 3 vs 55 +/- 5). Compared to age- and weight-matched unoperated controls, cyanotic animals developed significant depression of biventricular ejection fraction (P less than 0.05), increased heart weight indexed for body weight (P less than 0.05), increased right ventricular weight (P less than 0.02), and increased right ventricular free wall thickness (P less than 0.05). There was no alteration in ventricular volumes. In addition, mean myocardial stores of high-energy phosphate compounds were unaltered. The model allows a reproducible level of hypoxemia to be produced in young animals, utilizes no prosthetic materials, and allows future experiments to be performed to ascertain the metabolic response of the cyanotic myocardium to exercise or surgically induced ischemia.

Animals↗