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Biomedical subjects

R D Ice

Publications and source records attributed to R D Ice.

At least 19 recordsLinked to original sources
PubMed1995

History of medical radionuclide production.

Radionuclide production for medical use originally was incidental to isotope discoveries by physicists and chemists. Once the available radionuclides were identified they were evaluated for potential medical use. Hevesy first used 32P in 1935 to study phosphorous metabolism in rats. Since that time, the development of cyclotrons, linear accelerators, and nuclear reactors have produced hundreds of radionuclides for potential medical use. The history of medical radionuclide production represents an evolutionary, interdisciplinary development of applied nuclear technology. Today the technology is represented by a mature industry and provides medical benefits to millions of patients annually.

Animals↗
PubMed1984

New 75Se-labeled radiopharmaceuticals: 2. Selenium derivatives of aralkylamines.

Two 75Se-labeled aralkylamines, 2-(3,4-methylenedioxyphenylseleno)ethylamine hydrochloride (75Se-6) and 1-methylseleno-1-phenylethylmethylamine hydrochloride (75Se-9), were prepared with high specific activity applying two different chemical means starting from [75Se]selenious acid. Tissue distribution studies in rats show high uptake in the lungs with lung/blood ratios of 27/1 and 2.3/1 at 10 min for compound 75Se-9 and 75Se-6, respectively. High adrenal uptake and adrenal-to-blood ratio (15/1 at 2 h) of compound 75Se-9 were observed. This study indicates that aralkylamines can accommodate a Se group and still show high uptake by the organs that contain appreciable amount of dopaminergic receptors.

Adrenal Medulla↗
PubMed1982

Effects of concurrent drug therapy on technetium Tc-99m gluceptate biodistribution.

Drug interactions with technetium Tc-99m gluceptate resulting in altered biodistribution were studied using chart review and animal tests. Charts of nine patients who had abnormal gallbladder uptake of technetium Tc-99m gluceptate during a two-year period were reviewed to obtain data such as concurrent drug therapy, primary diagnosis, and laboratory values. Adult New Zealand white rabbits were then used for testing the biodistribution of technetium Tc-99m gluceptate when administered concurrently with possibly interacting drugs identified in the chart review--penicillamine, penicillin G potassium, penicillin V potassium, acetaminophen, and trimethoprim-sulfamethoxazole. Chart review revealed no conclusive patterns of altered biodistribution associated with other factors. The data did suggest the possibility that the five drugs listed above might cause increased hepatobiliary clearance of the radiopharmaceutical. Animal tests showed that i.v. penicillamine caused substantial distribution of radioactivity into the gallbladder and small bowel. Minimally increased gallbladder radioactivity occurred when oral acetaminophen and trimethoprim-sulfamethoxazole were administered concurrently. Oral and i.v. penicillins did not increase gallbladder activity. Penicillamine may cause substantial alteration of the biodistribution of technetium Tc-99m gluceptate.

Acetaminophen↗
PubMed1982

Trends in radiopharmaceutical dispensing in a regional nuclear pharmacy.

Dispensing trends for radiopharmaceuticals at a regional nuclear pharmacy over a 51-month period were studied. dispensing records of a regional nuclear pharmacy were analyzed with a forecasting procedure that uses univariate time data to produce time trends and autoregressive models. The overall number of prescriptions increased from 3500 to 5500 per quarter. Radiopharmaceuticals used in nuclear cardiology studies increased from less than 0.1% to 17.5% of total prescriptions dispensed, while radiopharmaceuticals used for brain imaging showed a steady decline from 29% to 11% of total prescriptions dispensed. The demand for other radiopharmaceuticals increased in areas such as renal studies, bone studies, lung studies, liver-function studies, and Ga-67 tumor-uptake studies, and declined slightly for static liver studies. Changes in dispensing trends for radiopharmaceuticals will continue as the practice of nuclear medicine concentrates more on functional studies and as newer imaging techniques become used for other purposes.

Drug Prescriptions↗
PubMed1981

Kit preparation of radioiodinated o-iodohippuran.

The purpose of this study ws to evaluate a kit preparation for radioiodinated o-iodohippuran (I). All ingredients, excluding the radionuclide, were packaged in a ready-to-use kit for easy, quick formulation. Electrophoresis was utilized to evaluate the radiochemical purity of the labeled product and indicated that the radiolabeling technique provided a product with greater than 95% radiochemical purity. Biodistribution studies in rats and rabbits provided an indication of the tissue distribution and localization of the radiopharmaceutical. Computer-generated renogram curves plotted from gamma-camera images of rabbits showed the equivalency of the 131I-labeled I and 123I-labeled I to the commercially available radiopharmaceutical.

Animals↗
PubMed1981

Thymic gallium-67 localization in pediatric patients on chemotherapy: concise communication.

Localization of Ga-67 in the thymus has been reported to occur in children. In our control group of 87 patients, 15% of children under 5 yr and 11% of children over 5 yr demonstrated thymic localization. In contrast, in our study group of seven children with acute lymphocytic leukemia or malignant lymphoma, lymphocytic diffuse, treated on a modified non-Hodgkin's lymphoma protocol, Sloan-Kettering LSA2-L2, thymic localization occurred during treatment in five of the seven. We conclude that increased thymic gallium localization in children under chemotherapy for a known malignancy may reflect increased activity of thymic medullary epithelial cells and regeneration of thymic lymphocytes during recovery form involution induced by certain chemotherapeutic agents.

Adolescent↗
PubMed1979

The in vitro stability of [131I]o-iodohippurate.

The kinetics of [131I]o-iodohippurate (OIH) decomposition were evaluated to develop an accelerated technique for the prediction of radiopharmaceutical stability. Decomposition due to temperature and self-absorbed radiation was characterized simultaneously. Using the proposed technique, the extent of OIH decomposition was calculated a priori to be 7.6% over a 28-day period when extrapolated to a specific concentration of 2 mCi/ml and a storage of 25 degrees C. Extended storage under these same conditions yielded a mean decomposition value of 8.0% over an equivalent time interval. The techniques developed offer a rapid means of accurately assessing the stability of new radiopharmaceuticals as they are developed.

Drug Stability↗
PubMed1977

A new and superior adrenal imaging agent, 131I-6beta-iodomethyl-19-nor-cholesterol (NP-59): evaluation in humans.

We have reported tissue distribution studies in rats and dogs with a new adrenal imaging agent. 131I-6beta-iodomethyl-19-nor-cholesterol (NP-59). This agent concentrated five times higher in the adrenal cortex than 131I-19-iodocholesterol without increased concentration in non-adrenal tissues. We now report in 34 patients, the findings on scintigraphy with NP-59 compared with angiograms and/or adrenal vein hormone levels and histopathology, including 13 patients with hypercortisolism, 12 with primary aldosteronism, 2 with low renin hypertension, 5 with catecholamine excess, 1 with a liver metastasis from an aldosterone producing adrenal cortical carcinoma, and 1 with anaplastic adrenal cortical carcinoma. NP-59 adrenal cortical uptake was more rapid and intense and background activity was less prominent, allowing earlier and more definite interpretation of images than was possible with 131I-19-iodocholesterol.

Adrenal Cortex Neoplasms↗
PubMed1976

Adrenal imaging with 131I-19-iodocholesterol in the diagnostic evaluation of patients with aldosteronism.

The results of adrenal scintiscans, venograms and venous aldosterone levels are compared with the histologic findings in 33 patients submitted to operations for primary aldosteronism. Standard and suppression scintiscans were performed 2-14 days following intravenous administration of 2mCi of 131I-19-iodocholesterol. The adrenal lesions were histologically classified into four categories: 25 patients had adenomas, 6 had macronodular hyperplasia, 1 had microscopic hyperplasia and 1 had an adenocarcinoma. Asymmetrical uptake between the two adrenals seen on standard scintiscans did not differentiate between a tumor or asymmetrical hyperplasia, unless the tumor was greater than 2 cm in diameter. During suppression scintiscans, unilateral uptake visible within five days of tracer injection was consistent with adenoma. Patients with nodular hyperplasia demonstrated early uptake in both adrenal glands during suppression scintiscans, while the patient with microscopic hyperplasia did not. The type of adrenal lesion was correctly identified in 20/26 (77%) of patients by suppression scintiscans; 21/28 (75% of patients by venograms and 12/16 (75%) of patients who had adrenal venous aldosterone measurements attempted. The majority of surgically correctible lesions could be identified on suppression adrenal scintiscans. Adrenal vein catheterization can be reserved for those patients in whom the results of suppression scintiscans are inconsistent with the clinical degree of aldosteronism.

Adenoma↗
PubMed1976

Selenium-75-19-selenocholesterol-a new adrenal scanning agent with high concentration in the adrenal medulla.

A tissue distribution study with 75Se-19-selenocholesterol in rats, rabbits, and dogs showed high adrenal concentrations and good adrenal images. In the dog, higher concentrations were obtained in the adrenal medulla than in the cortex at Days 1 and 7 after dosing. Extraction and thin-layer chromatography of the adrenal lipid in dogs given this compound showed that 75Se in the adrenal is still attached to the steroid moiety. A reduction in production costs is expected from its longer shelf life. Selenium-75-19-selenocholesterol is being evaluated in humans not only for routine use as a adrenal cortex scanning agent, but also for the detection of pheochromocytomas and other sympathetic tissue tumors, especially neuroblastomas.

Adrenal Gland Diseases↗
PubMed1976

Localization of radiolabeled enzyme inhibitors in the adrenal gland.

Tissue distribution studies were performed in rats and dogs at five time intervals between 10 min and 24 hr after the intravenous injection of one of the following radiolabeled adrenocortical enzyme inhibitors: 3H-amino-glutethimide, 125I-3-iodoaminoglutethimide, 3H-SKF-12185, 125I-3-SKF-12185, 3H-metyrapone. 3H-metyrapol. 3H-amphenone B, and 3H-SU-10603. In rats, 3H-SKF-12185 showed the highest uptake in the whole adrenal (3.5% kg dose/gm at 1 hr). In dogs, 3H-metyrapol showed the highest uptake in the adrenal cortex (9% kg dose/gm at 1 hr), and the peak cortex-to-liver concentration ratio was 57 at 2 hr. These peaks uptakes were comparable to those obtained with the conventional iodocholesterols, but they were reached much earlier, with elimination of most of the adrenal radioactivity by 24 hr. These properties would permit the use of 123I as the label and a higher tracer dose, resulting in a higher photon flux. Thus, the radiolabeled enzyme inhibitors show promise as adrenal-scanning agents, with a markedly shortened scanning procedure, a lower absorbed radiation dose, and better resolution.

Adrenal Gland Diseases↗
PubMed1975

Preparation, quality control and clinical acceptance of labeled Macrotec.

Thirty minutes after reconstitution, radiochemical purity determinations of the lung-scanning agent Macrotec (99m-Tc-MAA) indicated 95-100% technetium labeling: 76% of the particles had a mean diameter of 10-50 mu. Rat tissue distribution studies indicated lung uptake of 98% at 15 minutes. The biological half-life in the lung was 8.3 hours. In 12 patients requiring emergency lung scans, 9 scans were rated excellent. No liver, spleen or thyroid uptake or adverse reactions were noted.

Animals↗
PubMed1975

Uptake of radiolabeled estradiol by the canine adrenal.

Tritiated estradiol injected intravenously into 11 mongrel dogs sacrificed at 3, 7, 10, 17, and 60 min showed maximum uptake in the adrenal gland at 3-7 min. The concentrations of radioactivity in the adrenal in percent dose per gram equaled that from 131I-19-iodocholesterol. If a 131I-estradiol could be synthesized that would concentrate similarly in the adrenal, it would offer the advantage of almost instantaneous imaging after the tracer injection and a lower radiation dose.

Adipose Tissue↗
PubMed1975

Generator-produced 99m TcO4-: carrier free.

A solution of 99m-TCO4-minus, as eluted from a 99Mo-99mTc radionuclide generator contains a greater chemical quantity of technetium than that attributable to the metastable isomer alone. The isomeric transition of the radionuclide of interest, 99mTc, gives rise to a determinable and chemically significant quantity of technetium carrier, 99Tc. A method is presented for calculating the total chemical quantity of technetium in a generator eluate.

Molybdenum↗