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Biomedical subjects

A Strashun

Publications and source records attributed to A Strashun.

At least 19 recordsLinked to original sources
PubMed1999

Descending auditory system/cerebellum/tinnitus.

The cerebellum and the descending auditory system (DAS) are considered clinically significant for influencing the development of the clinical course of tinnitus of the severe disabling type. It is hypothesized that the SPECT of Brain perfusion asymmetries in cerebellum, demonstrated since 1993, reflect clinically the influence of an aberrant auditory stimulus i.e. tinnitus, on the activity and function of the descending auditory system highlighted by the cerebellum and the acousticomotor systems. SPECT of Brain perfusion asymmetries in the cerebellum have been demonstrated in 60-70% of tinnitus patients of the central type. Electrophysiologic support for this finding includes interference in ocular fixation suppression of the vestibulocular (VOR) with rotation and position testing. Abnormalities in cerebellar function are considered to reflect the psychomotor component of tinnitus. Support for the hypothesis is demonstrated with one patient with a predominantly central type tinnitus of the severe disabling type with cerebellar perfusion asymmetries and associated electrophysiologic evidence of interference in the VOR with rotation testing.

Acoustic Stimulation↗
PubMed1997

Sestamibi scan for preoperative localization in primary hyperparathyroidism.

BACKGROUND: Various invasive and noninvasive localizing tests are available for the evaluation of primary hyperparathyroidism. The surgical success in primary intervention exceeds 90% without localization studies. However, localization tests are absolutely essential for re-exploration and in certain select circumstances, even in primary exploration. The traditional noninvasive localization studies include the sonogram, thallium-technetium scan, computed tomography (CT) scan, and magnetic resonance imaging (MRI). The purpose of this report is to review our recent experience with sestamibi scan. The sestamibi scan appears to be the most sensitive and accurate noninvasive test available today. METHODS: Technetium 99m sestamibi has recently been used for parathyroid localization, in conjunction with iodine123 subtraction. We have evaluated 24 patients with suspected primary hyperparathyroidism to study the role of technetium 99m sestamibi scan. Tc-sestamibi was used either with or without iodine123 for subtraction of thyroid activity. RESULTS: None of these patients had renal failure or secondary hyperparathyroidism. Of 24 patients, the parathyroid adenoma was localized by scintigraphy in 19 patients. Twenty patients underwent surgical exploration. In 17 patients there was a complete correlation between the imaging study and the operative findings (positive predictive value, 89%). There were no false positives in this series. The interpretation of the parathyroid images was relatively easy; however, the depth of the adenoma could not be predicted, based on the scan alone. The largest adenoma weighed 2.7 g, the smallest, 700 mg. CONCLUSION: This newer radiopharmaceutical, technetium 99m sestamibi, appears to be quite useful and accurate in the preoperative localization of patients with primary hyperparathyroidism. Parathyroid enlargement can also be studied by sestamibi imaging alone if delayed imaging is performed.

Adult↗
PubMed1993

Alternating hemiplegia of childhood: studies of regional cerebral blood flow using 99mTc-hexamethylpropylene amine oxime single-photon emission computed tomography.

Alternating hemiplegia of childhood is a rare disorder of unknown cause associated with progressive neurological deterioration. We report the results of regional cerebral blood flow studies using 99mTc-hexamethylpropylene amine oxime single-photon emission computed tomography in 3 patients. These studies were performed during the hemiplegic attacks (n = 6) and during the symptom-free periods (n = 2). Six single-photon emission computed tomographic studies performed during hemiplegic attacks consistently showed relative hyperperfusion of the contralateral cerebral hemisphere. Two single-photon emission computed tomographic studies performed during the asymptomatic phase showed normal and symmetrical cerebral perfusion. This is the first definite demonstration of unilateral increase of cerebral blood flow in alternating hemiplegia. These findings support the possibility of a relationship between the cause of alternating hemiplegia and migraine.

Brain↗
PubMed1992

Reversible increased technetium-99m-HMPAO cerebral cortical activity: a scintigraphic reflection of luxuriant hyperperfusion.

A hemiparetic and aphasic patient, 3 days after acute traumatic transection of the left internal carotid artery requiring life-saving total embolic occlusion, revealed ipsilateral increased peripheral hemispheric 99mTc-HMPAO activity. Ten days postocclusion, HMPAO peripheral cortical flow normalized as hemiparesis and aphasia significantly cleared. The initial lateralized HMPAO hyperactivity pattern may reflect reactive hyperemia, a sign previously identified by contrast angiography and often associated with a better prognosis in evolving CVA. Evanescent peripheral cerebral hyperemia may represent beneficial cortical collateralization of the periinfarct area of a deeper lacunar (white matter) CVA.

Aphasia, Broca↗
PubMed1991

Intermittent torsion: association with horizontal lie of the testicle.

The importance of making an early diagnosis of intermittent testicular torsion cannot be over-emphasized. We report on 3 patients with recurrent episodes of severe testicular pain but who were pain-free at evaluation. All 3 patients were found to have a horizontal lie of the symptomatic testicle and a normal vertical axis in the contralateral asymptomatic testicle. Scrotal exploration revealed a bell-clapper deformity in all 3 patients. A history of recurrent scrotal pain and horizontal testicular lie, even in the absence of pain at the time of physical examination, is a strong indication for exploration and bilateral testicular fixation.

Adolescent↗
PubMed1989

Value of blood-pool subtraction in cardiac indium-111-labeled platelet imaging.

Blood-pool subtraction has been proposed to enhance 111In-labeled platelet imaging of intracardiac thrombi. We tested the accuracy of labeled platelet imaging, with and without blood-pool subtraction, in ten subjects with cardiac thrombi of varying age, eight with endocarditis being treated with antimicrobial therapy and ten normal controls. Imaging was performed early after labeled platelet injection (24 hr or less) and late (48 hr or more). Blood-pool subtraction was carried out. All images were graded subjectively by four experienced, "blinded" readers. Detection accuracy was measured by the sensitivity at three fixed levels of specificity estimated from receiver operator characteristic curve analysis and tested by three-way analysis of variance. Detection accuracy was generally improved on delayed images. Blood-pool subtraction did not improve accuracy. Although blood-pool subtraction increased detection sensitivity, this was offset by decreased specificity. For this population studied, blood-pool subtraction did not improve subjective detection of abnormal platelet deposition by 111In platelet imaging.

Adult↗
PubMed1988

Intensive single-agent mitoxantrone for metastatic breast cancer.

Twenty-seven women with metastatic breast cancer were treated with mitoxantrone as a single agent, with the use of an intensive dose-escalating schedule. Doses were given at 0.5 mg/m2/day as an iv injection for 3 consecutive days and then were escalated each month by 2.5 mg/m2/day until maximal tolerance was reached on the basis of hematologic or cardiac toxicity. No complete responses were demonstrated. Six patients (22%) had partial responses of 5.5 months' median duration. Four of 12 patients who had not received prior doxorubicin responded (33%), whereas two of 15 patients with previous doxorubicin exposure responded (13%). Cardiotoxicity, determined by serial radionuclide ventriculography, occurred in 10 patients (37%) at a mean total mitoxantrone dose of 83.0 mg/m2. Three of these 10 patients had no predisposing risk factors, four had received thoracic radiotherapy that might have involved the heart, and three had received prior doxorubicin without clinical toxicity. The failure of dose intensification to augment the response rate when compared to the response rates reported for less myelotoxic doses of the drug, in addition to the extent of cardiotoxicity noted, calls into question the value of dose intensification of mitoxantrone in the treatment of metastatic breast cancer.

Breast Neoplasms↗
PubMed1987

A phase I-II study of intensive-dose adriamycin for advanced breast cancer.

Twenty-six women with metastatic breast cancer were treated with intensive Adriamycin (Adria Laboratories, Columbus, OH) as a single agent administered for three successive days once a month. Dosing started at 25 or 30 mg/m2/d three times, and was escalated by 5 mg/m2/d monthly to maximal tolerance based on hematologic, mucosal, or cardiac toxicities. Four patients (15%) had complete remissions (CRs) pathologically proven, and six others (23%) sustained complete CRs, but were found to have microscopic residual tumor (three) or refused biopsy (three). Twelve patients (46%) attained partial remission (PR). The overall response (85%) and CR rates (38%) were approximately double those reported with conventional Adriamycin doses. Median unmaintained remission duration for the ten patients in CR was 11 months. Cardiotoxicity, determined by radionuclide physiologic studies, occurred in 16 patients at a mean dose of 459 mg/m2; three patients developed reversible congestive failure. There were no toxic deaths. The median overall survival was 18 months. These data suggest that there is steep dose responsiveness to Adriamycin in metastatic breast cancer, and that more effective techniques for using Adriamycin may exist than those conventionally used.

Adult↗
PubMed1986

Studies of the hepatocellular uptake of the hepatobiliary scintiscanning agent 99mTc-DISIDA.

Bilirubin (BR) and organic anionic dyes such as sulfobromophthalein (BSP), indocyanine green (ICG) and rose bengal (RB) enter the hepatocyte by a specific non-sodium-dependent membrane transport system. Two analogous but distinct Na+-dependent transport systems effect the uptake of conjugated bile acids such as taurocholate (TC) and free fatty acids such as oleate, respectively. The mechanism of uptake of the acetanilidoiminodiacetic acid (HIDA) class of biliary scintiscanning agents is unknown. Accordingly, rat hepatocytes were isolated by collagenase perfusion of the liver and differential centrifugation, and incubated with 99mTc-diisopropyl-HIDA (99mTc-DISIDA) alone, or in the presence of various concentrations of BSP, ICG, RB, oleate or TC, with and without bovine serum albumin (BSA). Initial uptake velocity (Vo) was determined from the initial slope of the cumulative radioactivity/time curve. In albumin free media, uptake of 99mTc-DISIDA was temperature- and pH-dependent, with maximal uptake at 37 degrees C. There was virtually no uptake of inorganic 99mTc. In incubations containing 15-1500 microM 99mTc-DISIDA, Vo was saturable, with estimated Vmax = 65 nmoles/min/10(6) hepatocytes, and Km = 1200 microM. In keeping with its weak albumin binding, 99mTc-DISIDA Vo was only minimally influenced by equimolar concentrations of BSA. 99mTc-DISIDA Vo was inhibited by BR, BSP, ICG and RB, as well as by a rabbit antibody to the rat liver plasma membrane BSP/BR binding protein. Surprisingly, Vo was also inhibited by TC and oleate, but not influenced either by ouabain or by substitution of Li+ for Na+ in the medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Albumins↗
PubMed1982

Planar imaging of positron-emitting radionuclides with a multicrystal camera.

A multicrystal gamma camera has been evaluated for the imaging of 511-keV photons resulting from positron emission. With minor instrument modifications, images of a phantom demonstrating good resolution are obtained. Satisfactory planar images are obtained in animals using fluorine-18 or rubidium-82. These findings establish the feasibility of planar imaging of positron emitters in a clinical setting, and may make possible the more rapid development assessment, and dissemination of positron-emitting radionuclides, thus promoting utilization of tomographic positron imaging techniques.

Animals↗