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Biomedical subjects

S Hoory

Publications and source records attributed to S Hoory.

15 recordsLinked to original sources
PubMed1998

A multi-user real time inventorying system for radioactive materials: a networking approach.

A computerized system for radioisotope management and real time inventory coordinated across a large organization is reported. It handles hundreds of individual users and their separate inventory records. Use of highly efficient computer network and database technologies makes it possible to accept, maintain, and furnish all records related to receipt, usage, and disposal of the radioactive materials for the users separately and collectively. The system's central processor is an HP-9000/800 G60 RISC server and users from across the organization use their personal computers to login to this server using the TCP/IP networking protocol, which makes distributed use of the system possible. Radioisotope decay is automatically calculated by the program, so that it can make the up-to-date radioisotope inventory data of an entire institution available immediately. The system is specifically designed to allow use by large numbers of users (about 300) and accommodates high volumes of data input and retrieval without compromising simplicity and accuracy. Overall, it is an example of a true multi-user, on-line, relational database information system that makes the functioning of a radiation safety department efficient.

Computer Communication Networks↗
PubMed1992

RP-30A: new tracer for detection of changes in testicular blood flow in rat torsion model.

RP-30A is a radioactive tracer being evaluated for the detection of regional myocardial blood flow. This study compares RP-30A to technetium 99m pertechnetate as radioactive tracers for the detection of testicular blood flow changes in early testicular torsion. The left testis of adult male Sprague-Dawley rats was subjected to either thirty or sixty minutes of 720 degrees torsion. Injections of RP-30A or 99mTc-pertechnetate followed by sacrifice and scintillation counting of the testes was performed. No significant difference was detected between the torted testes and the right control testes in both groups receiving 99mTc-pertechnetate and the thirty-minute group receiving RP-30A. The torted testes of the sixty-minute group receiving RP-30A revealed a significant difference (decrease) in uptake indicating that RP-30A may be a more sensitive tracer in detecting testicular blood flow changes in early testicular torsion.

Animals↗
PubMed1991

Performance characteristics of a commercial dedicated contamination counter.

The dedicated wipe test counter (DWTC) is a commercial geiger-counter type instrument especially designed for wipe test counting. All samples are counted under the same physical conditions within 0.3 cm from a 2-mg cm-2 mica end-window geiger tube of 1.27 cm in diameter. The counting capabilities of the DWTC were tested for different radioisotopes in common use in the nuclear medicine laboratory. Since most of the imaging agents are 99mTc-based radiopharmaceuticals, an experimental efficiency factor, J = 3 cpm kdpm-1, was determined for this radioisotope by the manufacturer and stored in the counting system for default use. In addition, the formulation for the counting time needed to achieve a measurement with adequate level of significance (two standard deviations) and a background measurement time of 20 min was programmed in the firmware of the DWTC. With these parameters, the counting time for a 99mTc wipe (threshold of 2000 dpm) becomes 1.88 min for a background level of 10 cpm. The counting time increases to 3.25 and 4.80 min for the respective background levels of 20 and 30 cpm while the threshold is kept the same. In practice, we were able to measure activities as low as 0.7 kdpm for 99mTc and 0.09 kdpm for 131I. Linearity was maintained for a wide range of activities for all tested radioisotopes. The DWTC was found to be simple to operate and satisfies all requirements for performing wipe tests in the nuclear medicine laboratory.

Evaluation Studies as Topic↗
PubMed1991

Effect of coronary occlusion and myocardial viability on myocardial activity of technetium-99m-sestamibi.

The timing effect of sestamibi administration with respect to the onset of myocardial ischemia and reperfusion was studied in swine. In different groups of animals sestamibi was administered prior to coronary artery occlusion, during occlusion, or 1/2 hour following reperfusion. Sestamibi administered prior to coronary occlusion resulted in an insignificant decrease in 99mTc activity in the ischemic zone. However, infarct zone activity was reduced to 62 +/- 14% of the nonischemic zone. In contrast, administration during coronary occlusion resulted in similar significant reductions of both ischemic and infarct zone activity. Administration of sestamibi during reperfusion resulted in normal ischemic zone activity and markedly reduced activity in the infarct zone. Significantly reduced activity in the infarct zone was found to be independent of the timing of sestamibi administration with respect to the onset of myocardial ischemia and/or reperfusion. Thus, cell viability appears required for uptake and retention of isotope activity.

Animals↗
PubMed1989

Biodistribution of indium 111-labeled dihematoporphyrin ether in papillomas and body tissues. Relevance to photodynamic therapy.

Hematoporphyrin derivative and its newly purified form, dihematoporphyrin ether, have been shown to localize selectively in malignant tissues and virally induced papillomas. Its use as a probe to distinguish tumors from normal tissues has been largely based on its fluorescence when activated by UV light. These findings are largely subjective, and a direct correlation to its use as a photosensitizing agent to selectively kill transformed cells when activated by an appropriate wavelength of light could not be made. The efficacy of dihematoporphyrin ether photodynamic therapy to selectively kill papillomavirus-transformed cells is based on the increased localization of dihematoporphyrin ether within these tissues as compared with normal tissues. Using cottontail rabbit papillomavirus, cutaneous papillomas were induced on the backs of Dutch belted rabbits. Dihematoporphyrin ether was labeled with indium 111 and intravenously injected into the rabbits. The animals were scanned twice daily for indium 111 activity on a large-field-of-view gamma camera. At 50 hours after injection, the rabbits were killed and papillomas, skin, and major organs collected for biodistribution studies. The results of this study and their relationship to dihematoporphyrin ether photodynamic therapy for the treatment of virally induced papilloma disease is discussed.

Animals↗
PubMed1988

Potential use of indium-111-labeled polymorphonuclear leukocytes for the detection of lung microvascular injury.

The early stages of microvascular injury are often difficult to detect due to the lack of a suitable marker to assess such an injury. We utilized the well known phenomenon of polymorphonuclear leukocyte (PMN) migration to the microvascular bed as a result of acute inflammatory reactions originating from the damaged cells. A radiotracer technique was developed, employing indium-111-labeled PMN for the detection of microvascular injury induced by hyperoxia. New Zealand white rabbits exposed to either 100% oxygen or air for various intervals of time were injected with indium-111-tropolone or oxine-labeled PMNs. Influx of radioactive PMN into the lung was detected in 72 hr/oxygen-exposed animals using gamma scintigraphic technique. Analysis of dry/wet ratios and histological examinations of the lung biopsies indicated noncardiogenic edema formation at this stage. Mortality was 50% beyond 96 hr/oxygen exposure. Our study thus provided a means to detect early microvascular injury during 72 hr/oxygen-exposure, which was not detectable by any other noninvasive techniques. The use of indium-111-labeled PMN thus appears to be a potentially important tool for the clinical assessment of lung microvascular injury.

Animals↗
PubMed1988

Role of polymorphonuclear leukocytes in hyperoxic lung injury. Prevention of neutrophil influx into the lung endothelium during oxygen exposure by ibuprofen.

The present study examines the role of PMN in hyperoxic lung injury using a nonsteroidal anti-inflammatory drug, ibuprofen. New Zealand white rabbits were exposed to 100% oxygen or air for 1 to 4 days. The animals were divided into two groups: the treatment group received ibuprofen with drinking water, and the control group received water alone. After exposure to oxygen or air, the rabbits were injected with indium-III-oxine labeled PMN. Influx or radioactive PMN into the lung was detected using gamma scintigraphic technique only in 72 h and 96 h oxygen-exposed animals which were not treated with ibuprofen. Ibuprofen-treated animals did not exhibit any PMN influx into the lung. Blood gas analysis of all 72 h oxygen-exposed animals did not show any abnormal values, although analysis of dry/wet weight ratios and histopathological examinations indicated noncardiogenic edema formation. After 96 h of oxygen exposure, both ibuprofen-treated and untreated groups suffered from severe acidosis. Gross cytoplasmic edema and partial destruction of lung endothelium were also observed. Mortality was 50% after 96 h of oxygen exposure. Our study, thus, demonstrates that ibuprofen cannot prevent hyperoxic lung injury although it inhibits the influx of PMN into the injured lung, suggesting that PMN are not directly involved in the injury process.

Animals↗
PubMed1987

111Indium-tropolone labeled human PMNs: a rapid method of preparation and evaluation of labeling parameters.

Pure polymorphonuclear leukocytes (PMNs) have been isolated from a small amount of human blood by a single-step density gradient centrifugation method using a commercially available Ficoll-Hypaque mixture of density 1.114. The cells were labelled with [111In]tropolone in both buffer and plasma. Cell viability, ability to generate superoxide anion, and chemotaxis were found to be unaltered both before and after labeling. The optimum tropolone concentration for labeling was found to be 1 X 10(-4) M. Labeling efficiency was higher at 37 degrees C than at room temperature. Compared to [111In]oxine, tropolone preparation both in buffer and plasma resulted in consistently higher yields. Preliminary experiments of in vivo cell viability of the labeled PMNs were carried out in rabbits. The ability of the cells to localize in experimentally produced inflammatory lesions was found to be intact. The method of cell separation and labeling described has been found to be simple and rapid and could easily be incorporated in routine nuclear medicine laboratory practice.

Animals↗
PubMed1987

Use of a gamma camera to estimate bone mineral content based on the dual-photon technique.

Bone mineral content evaluations using a point source of 153Gd of strength 100 mCi or less and a Siemens large field of view gamma camera equipped with a converging collimator is reported. Both 44 and 100 ke V images are digitised in 128 x 128 matrices and processed in a Siemens MicroDelta System attached to a VAX 11-750 computer. Shorter imaging time, low source strength and the usage of existing nuclear medicine equipment are the major highlights of the technique. The effective focal distance (EFD) of the collimator used is experimentally determined with a 57Co source and found to be 75 cm. Focal distances are also calculated from measured values of magnification factors at different points on the collimator face to assess the degree of misalignment of converging holes. Due to the high count rate of the system, corrections for dead time losses and image shrinkages are applied. Two additional low-activity point sources of 153Gd, which serve as live time meters of the system, are used for this purpose. In addition, due to the non-homogeneity of the converging collimator, uniformity corrections for each field of view are found to be essential. In external standards made of various amounts of hydroxyapatite, a correlation coefficient greater than 0.990 with a standard error of the estimate (SEE) 0.0225 is obtained between measured and actual values. In a limited clinical trial, high-resolution images of human spines are acquired and quantitative estimates of bone mineral content are evaluated.

Bone and Bones↗
PubMed1986

Internal dosimetry evaluations: a computerized approach.

A computerized approach to the average absorbed dose calculations in the standard human body is reported. For each selected radionuclide, a matrix S of the order n X n is constructed and stored in the computer. The matrix elements consist of the absorbed dose coefficients per unit cumulated activity (rad microCi-1 hr-1) for n different organs. Each element Sij of the matrix S represents the average dose contribution from a particular radionuclide uniformly distributed in the source organ j to the target organ i. Therefore, the diagonal elements of S represent the average absorbed dose contribution from each organ to itself (target to target). The different organ uptake coefficients and the biological half-lives of several elements and compounds gathered from the literature were organized and stored on the computer disk. During dosimetry evaluations, the system retrieves the physical half-life of the involved radionuclide, searches for the appropriate biophysical factors, computes the cumulated activities Ai of the n organs and then constructs the cumulated activity vector A. The estimates of the average dose absorbed in the various targets are presented by the organ dose vector D. Hence, the dosimetry evaluations of all organs may be obtained by simply multiplying the matrix S by the column vector A.

Computers↗
PubMed1982

A computerized system for control and management of radionuclide inventory: application in nuclear medicine.

An interactive computerized system for radioisotope management and instantaneous inventory is reported. The system is capable of handling operations such as filing, nuclear imaging and disposing of various radionuclides. All radiopharmaceutical transactions are achieved with the aid of a Prime 300 mini-computer of 192K words of high speed semi-conductor memory and over 120 mega bytes of disk storage. The system automatically corrects for the appropriate decay, monitors and updates the storage file after every subsequent study. The performed study is recorded in a special file, together with the time and data retrieved from the computer's real time clock at the time of the entry. The system provides an organized and complete bookkeeping of all records concerning radionuclide transactions. It is found to be simple, efficient, highly versatile, and drastically reduces the time of operation and errors in handling the radioisotope inventory.

Computers↗
PubMedDate not supplied

Role of a nonsteroidal anti-inflammatory agent, ibuprofen, in coronary revascularization after acute myocardial infarction.

The efficacy of using a nonsteroidal anti-inflammatory agent such as ibuprofen for the salvage of ischemic and reperfused myocardium was investigated by examining its ability to improve global and regional functions as well as to preserve high-energy phosphate compounds and inhibit creatine kinase release from an isolated in-situ pig heart subjected to 1 h of normothermic regional ischemia followed by 1 h of global hypothermic arrest and 1 h of normothermic reperfusion. Preperfusion of the heart for 15 min prior to ischemic insult with 50 microM ibuprofen failed to mitigate the myocardial reperfusion injury. Ibuprofen, however, functioned as an anti-inflammatory agent, as judged by its ability to inhibit the influx of indium-111-labeled polymorphonuclear leukocytes and chromium-51 (51Cr)-labeled platelets into the ischemic and reperfused heart. It also blocked the cyclooxygenase pathway, as evidenced by the significant reduction of 6-keto-prostaglandin F1 alpha and thromboxane B2 concentrations in the perfusate. Inhibition of cyclooxygenase resulted in increased accumulation of nonesterified fatty acids, particularly arachidonic acid, in the heart. These results suggest that although ibuprofen can inhibit polymorphonuclear leukocyte and platelet influx into the ischemic and reperfused heart, it causes further damage to the already ischemic heart by reducing prostacyclin concentration and increasing free fatty acids in the heart.

6-Ketoprostaglandin F1 alpha↗