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Biomedical subjects

P Som

Publications and source records attributed to P Som.

At least 37 records · Page 2Linked to original sources
PubMed1992

Laryngeal chondrosarcomas: a clinicopathologic study of 11 cases, including two "dedifferentiated" chondrosarcomas.

Laryngeal chondrosarcomas are uncommon, and those that contain a distinct, nonchondroid, high-grade spindle cell sarcoma (the so-called "dedifferentiated" chondrosarcoma or chondrosarcoma with additional malignant mesenchymal component [CAMMC]) are extremely rare. Laryngeal CAMMC merit special attention, as CAMMC in other sites portends a poor prognosis. Eleven patients with laryngeal chondrosarcomas are reported on; 2 of these patients had CAMMC. On follow-up, 3 of the 11 patients had recurrences. The first had recurrence 4 and 11 years after tumor enucleation; that patient died disease free 2 years after salvage total laryngectomy. The second had recurrence 2 years after partial laryngectomy and was lost to follow-up after salvage total laryngectomy. The last patient recurred 13 years after partial laryngectomy and underwent salvage total laryngectomy; that patient was one of the two who developed CAMMC, and he also developed stomal recurrence of the "dedifferentiated" component 3 years after total laryngectomy. The other 8 patients are disease free after partial laryngectomy (6) or total laryngectomy (2) 10 months to 12 years later (mean: 51 months). This includes the 1 other patient with CAMMC, who is disease free 60 months after total laryngectomy. Laryngeal CAMMC has been shown, in at least one of the two patients, to be associated with a poor outcome. Patients with recurrent laryngeal chondrosarcomas do not have a poorer outcome after salvage total laryngectomy. The authors advocate partial laryngectomy if technically feasible.

Adult↗
PubMed1991

A monoclonal antibody reacting with platelets for monitoring thrombolysis.

Thrombus immunoscintigraphy with radiolabeled monoclonal antibodies are presently undergoing intense clinical evaluations. Reports on clinical trials of radiolabeled antifibrins are very encouraging and results of antiplatelet antibody evaluations are forthcoming. Animal studies with antiplatelet antibodies indicate that a diagnosis can be made within the critical "lytic window" of 4-6 h, and thus the imaging procedure may be used as an adjunct to thrombolytic therapy, i.e. screening of patients. We now report on a potentially new application of monoclonal antibodies, immunoimaging for monitoring thrombolysis. In vitro studies were performed with "standardized clots" incubated with 99mTc 50H.19 and re-incubated with streptokinase (SK), urokinase (UK) or recombinant tissue plasminogen activator (rt-PA). The decrease in clot-bound 99mTc 50H.19 activity after SK, UK or rt-PA incubation was proportional to the decrease in clot weight (r = 0.90-0.98). The direct effects of these thrombolytic agents on the labeled antibody and the possible interference of aspirin, warfarin and heparin in thrombus immunoimaging were also investigated. Aspirin, heparin and warfarin did not interfere with clot-binding of 99mTc 50H.19. Thrombolytic agents did not affect the stability of the radiolabel or immunoreactivity of 50H.19. These results indicate that 99mTc 50H.19 is a promising agent that may enable monitoring thrombolysis in addition to thrombus immunoimaging.

Antibodies, Monoclonal↗
PubMed1991

Radiographic evaluation and diagnosis of the failed frontal osteoplastic flap with fat obliteration.

In the absence of evidence of suppurative disease, clinical assessment of the symptomatic patient after frontal osteoplastic flap with fat obliteration is difficult because the cause of the pain is often neuralgic or from chronic vascular headache. Among 59 patients who have undergone this procedure at our institution since 1979, four required revision surgery. These patients were evaluated by computed tomographic and magnetic resonance scans, and the radiographic findings were compared with those present in 20 asymptomatic subjects. On the basis of the results of this study, we believe we can objectively identify those patients with chronic pain in whom the operation has been unsuccessful. A review of our experience with this procedure is presented along with criteria that enable early diagnosis of recurrent disease in the frontal sinus after osteoplastic sinusotomy.

Adipose Tissue↗
PubMed1991

Functional evaluation following microvascular oromandibular reconstruction of the oral cancer patient: a comparative study of reconstructed and nonreconstructed patients.

Over the past decade, the use of free flap transfers in head and neck surgery has led to remarkable advances in the reliability and the ultimate results of oromandibular reconstruction. Stable and retentive dental restorations have been achieved using enosseous implants placed directly into the vascularized bone flaps. However, the functional assessment of patients who underwent primary mandibular reconstruction with these techniques has not been previously reported. A group of 10 reconstructed and 10 nonreconstructed segmental hemimandibulectomy patients were compared using a battery of tests to assess their overall well-being, cosmesis, deglutition, oral competence, speech, length of hospitalization, and dental rehabilitation. In addition, objective measures of the masticatory apparatus (interincisal opening, bite force, chewing performance, and chewing stroke) were used to compare these two groups as well as normal healthy subjects and edentulous patients restored with conventional and implant-borne dentures. The results show a clear advantage for the reconstructed patients in almost all categories. Persistent problems and future directions in oromandibular reconstruction are discussed.

Adult↗
PubMed1991

Imaging of cocaine-induced global and regional myocardial ischemia.

Severe and often fatal cardiac complications have been reported in cocaine users with narrowed coronary arteries caused by atherosclerosis as well as in young adults with normal coronaries. We have found that in normal dogs cocaine induces severe temporary hypoperfusion of the left ventricle as indicated by a significantly lower 201Tl concentration compared to the baseline state. The most significant decrease in uptake occurred 5 min after injection and was more pronounced in the septal and apical segments. Following intravenous administration of cocaine, instead of gradual disappearance of 201Tl from the left ventricle, there was continuous increase in 201Tl concentration in the left ventricle. These imaging experiments indicate that the deleterious effects of cocaine on the heart are probably due to spasm of the coronaries and decreased myocardial perfusion. Since spasm of the large subpericardial vessels does not seem to explain the magnitude of the increased coronary resistance and decreased coronary flow after cocaine as described in the literature, it is suggested that microvascular spasm of smaller vessels plays a major role in the temporary decrease in perfusion. The data may also suggest that severe temporary myocardial ischemia is probably the initiating factor for the cardiac complications induced by cocaine.

Animals↗
PubMed1991

Simulated peribulbar injection of anesthetic.

To evaluate whether intracranial spreading of a local anesthetic might occur after a peribulbar injection, we did simulated peribulbar anesthetic injections with radiopaque dye into two cadaver heads. Using a standard and modified peribulbar injection with a 25-gauge needle, the four orbits were injected with 8 mL of dye. Computed tomography revealed that the dye spread intraconally and intracranially. In one case the dye was seen tracking along the optic nerve sheath. Since intracranial spreading of a local anesthetic may be associated with adverse sequelae (i.e., brainstem anesthesia), we urge caution and vigilance after both peribulbar and retrobulbar anesthetic injections to prevent cardiopulmonary compromise.

Anesthetics↗
PubMed1990

Esthesioneuroblastoma: surgical treatment without radiation.

This study compares the treatment of two groups of patients diagnosed with esthesioneuroblastoma limited to the nasal cavity without evidence of cribriform plate erosion. Five patients were treated with radiation and extracranial excision, and eight patients were treated by craniofacial resection only. The incidences of local recurrence were 60% and 12%, respectively. The paper also presents a new staging classification for these tumors.

Adolescent↗
PubMed1989

Studies of a new fatty acid analog (DMIVN) in hypertensive rats and the effect of verapamil using ARG microimaging.

Studies of myocardial utilization of fatty acids and analogs has focused on coronary heart disease. This study addresses the topic of radioiodinated fatty acid utilization in hypertensive-cardiomyopathy. The new fatty acid analog 19-iodo-3,3-dimethyl-18 nonadecenoic acid (DMIVN) was studied by autoradiographic microimaging (ARG) in salt-sensitive (S) hypertensive (salt-fed) and in salt-sensitive (S) normotensive (low-salt diet), Dahl-strain rats. A salt fed, S-strain group was treated with verapamil and the results were compared to those in a hypertensive, non-treated group. The distribution of DMIVN in the hearts of normotensive rats was uniform. In the myocardium of hypertensive rats nonuniform DMIVN concentration was seen in the subendocardial and mid-layers of the left ventricle (LV). Verapamil given to salt-fed rats prevented hypertension and uniform DMIVN uptake similar to normotensive controls was seen. The data suggest that DMIVN may be suitable for the detection of hypertension induced myocardial changes and for assessing therapy. The distribution and clearance characteristics of DMIVN indicate that DMIVN may be a useful agent for SPECT imaging in man.

Animals↗
PubMed1989

The role of factor analysis in the evaluation of new radiopharmaceuticals.

Factor analysis of dynamic scintigraphic studies has been proposed for a variety of clinical applications. This method also called FADS (Factor Analysis of Dynamic Structures) enables spatial separation of complex images into discrete factors according to their time/activity characteristics. FADS, which does not require a priori formulation of a compartmental model of tracer kinetics, is particularly suitable for the evaluation of new radiolabeled compounds as potential radiopharmaceuticals. In animals as well as in humans it is possible to obtain information on the spatial time-distribution of tracers by analyzing computer acquired scintigraphic studies. On the basis of data obtained and analyzed with this method using [123I]IMP in humans, dogs, rabbits and rats, with two 99mTc labeled monoclonal antibodies in dogs and with 99mTc DTPA in renal transplants, we recommend this method as an adjunct in radiopharmaceutical development and evaluation.

Amphetamines↗
PubMed1989

Mesenteric vascular occlusion: a new diagnostic method using a radiolabeled monoclonal antibody reactive with platelets.

A new method for diagnosing mesenteric vaso-occlusive bowel disease with the use of radioimmunoscintigraphy was developed and tested in experimental models of arterial and venous disease, as well as in a model simulating bowel strangulation. The method involves the use of a monoclonal antibody fragment mixture that binds to platelets. The antibody was labeled with technetium-99m, and imaging was performed with a gamma camera in the planar and single photon emission computed tomography modes. This method allowed visualization of areas of ischemia of 1-6 hours duration in bowel loops in 19 dogs 90-180 minutes after injection of the radiolabeled antibody. No bowel radioactivity accumulation occurred in dogs that underwent the same surgical procedure but were given a nonspecific Tc-99m-labeled antibody or in normal dogs given the specific antibody. It appears that the radiolabeled antibody used, which has higher reactivity with human platelets than with dog platelets, will be a good agent for noninvasive diagnosis of mesenteric vaso-occlusive disease in humans. It may also play a role in the intraoperative determination of the extent and location of ischemic bowel segments.

Animals↗
PubMed1989

Glomus vagale tumors.

Eighteen patients with glomus vagale tumors treated by surgical resection are reviewed. Computed tomography and magnetic resonance imaging are diagnostic. Arteriography is used to determine multicentric tumors. The incidence of multicentric tumors in this series was 40%. Adequate surgical exposure is necessary for removal of the tumor without injury to the carotid artery. Vagal paralysis was present in all cases postoperatively and resulted in dysphagia and aspiration. Cricopharyngeal myotomy and Teflon injection aided in rehabilitation of deglutition. Curability with surgery is high, but radiation therapy is recommended in selected patients.

Adult↗
PubMed1989

Inverted papilloma: an analysis of 87 cases.

A group of 87 patients with inverted papilloma, a locally aggressive benign sinonasal tumor, were treated over the past 15 years. Selection of therapy depends on an accurate radiographic assessment of the extent of tumor. The tumor's local aggressiveness, high rate of recurrence, associated malignancy, and multicentric tendency have led most workers to advocate radical surgical removal of the tumor by lateral rhinotomy and en bloc resection of the ethmoid labyrinth. Radiographic evaluation by computed tomography scanning and magnetic resonance imaging permits identification of a small group of patients who have limited lesions and may be candidates for conservative tumor resection by intranasal or transantral sphenoethmoidectomy. Among our ten patients treated with conservative surgery, there was recurrence in one case (10%). Seventy-five patients underwent rhinotomy and medial maxillectomy, with seven cases recurring (9%). The overall recurrence rate was 9% (8 of 87). Among the 87 cases, 5 patients had carcinoma (6%). The literature is reviewed and the principles of case selection and management are discussed.

Adolescent↗
PubMed1989

Comparative dual-tracer studies of carbon-14 tryptophan and iodine-131 HIPDM in animal models of pancreatic diseases.

Our previous studies have shown that a significant amount of the diamine derivative 131I-N,N,N'-trimethyl-N'-(2-hydroxy-3-methyl-5-iodobenzyl)-1,3- propanediamine (HIPDM) is taken up and retained by the normal pancreas. Therefore, we studied the uptake of [131I]HIPDM in various pathophysiological models in mice (chronic alcoholism, diabetes with beta-cell atrophy and obesity with beta-cell hypertrophy) and compared to 14C-L-Tryptophan (TRY) distribution in order to determine the factors influencing their pancreatic uptake. In normal animals, the pancreas uptake of TRY was generally higher than HIPDM. In diabetes, the relative concentration of both compounds was higher over the controls; however, in obesity, TRY showed lower accumulation than in controls while HIPDM showed no significant difference. Chronic ethanol (20%) ingestion increased TRY uptake in the pancreas compared to controls (36.88 +/- 3.21 vs. 30.03 +/- 4.17% ID/g; p less than 0.01) after 5 wk study period, but it decreased by 10 wk (22.36 +/- 0.95% ID/g; p less than 0.005). There were no significant changes in [131I]HIPDM distribution in alcoholics as compared to the controls. Radioiodinated HIPDM has potential advantages over [11C]TRY for pancreatic imaging since conventional imaging techniques can be employed. Our data, however, suggest that 11C-L-TRY is a more sensitive indicator of various pancreatic disorders.

Animals↗
PubMed1989

Recent developments in neutron capture therapy.

The conditions for the possible initiation of clinical trials with neutron capture therapy at a number of locations in the U.S. is reviewed. There are several new technical developments or plans at the Brookhaven Medical Research Reactor (BMRR), the Power Burst Facility (PBF) at INEL, the Massachusetts Institute of Technology Reactor (MITR) and the Georgia Institute of Technology Research Reactor (GTRR). Emphasis is on the development of epithermal beams for the treatment of deepseated tumors with neutron fluxes in between 10(9) to 10(10) n/cm2s. Therapeutic dose gains, defined as the ratio of tumour dose to maximum normal tissue dose in the treatment volume are expected to be between 2 and 4, depending on the degree of suppression of fast neutron dose. Boron concentrations considered in this case in the tumour are around 35 micrograms 10B/g and tumour/normal tissue concentrations are around 10. The compound development throughout three generations is discussed. The compound proposed nowadays, Na2B12H11SH (or BSH), employed in the treatments in Japan, will likely be replaced in the future by analogous of biomolecules being enriched in the tumour by physiological pathways. Examples are p-boronophenylalanine or boronated porphyrius. The most promising solution envisaged would be the employment of tumour cell specific brononated monoclonal antibodies. Finally the mode of therapy is discussed which will likely be based on a fractioned scheme, to achieve optimized results.

Fast Neutrons↗
PubMed1988

Whole-body autoradiographic localization of [3H]phencyclidine and its metabolites in mice.

When evaluated by whole-body autoradiography (WBAR) and quantitative densitometry, [3H]phencyclidine (PCP) equivalents were found to be removed rapidly from blood, after a single iv dose in mice, and avidly taken up as early as 1 min after dosage by glandular tissues including thyroid, salivary glands, pancreas, pituitary and, most prominently, by stomach mucosa. Stomach:blood [3H]PCP concentration ratios showed that rapid secretion of [3H]PCP from mucosa to the stomach contents occurred within 2 min after dosing. During early intervals, chromatographic analysis of tissue sections demonstrated that PCP was present in brain, liver, and gut primarily in its unaltered chemical form. Mice killed at 60 and 120 min showed persistently high levels of [3H]PCP equivalents within the stomach and intestines, these levels being the highest of all other tissues densitometrically measured. The early time course and magnitude of [3H]PCP uptake by stomach glandular mucosa strongly suggests that cycling of PCP occurs principally through gastroenteric recirculation. Very striking was the high concentration of [3H]PCP radioactivity observed within the adrenal as early as 5 min. The concentration of [3H]PCP equivalents in pituitary, choroid plexus, cortex, hippocampus, and thalamus was highest at 1-20 min following injection. Application of high-resolution quantitative WBAR was found to be a useful tool in the study of the biodistribution of labeled PCP, especially during very early post-treatment time points where alternative tissue counting techniques would not be feasible.

Animals↗