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Results for “RADIOISOTOPES”

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At least 307 records · Page 17Linked to original sources

PubMed1989

Clinical study of radioisotope clearance from the cerebrospinal fluid space using single photon emission computed tomography.

Radioisotope cisternography with statistical analysis was evaluated in 18 patients with suspected hydrocephalus shown by conventional CT, and 4 control patients. Regions of interest were located at cisterna magna, basal cistern, lateral cistern Sylvii, interhemispheric cistern, and lateral ventricle using three dimensional SPECT images. A value for the constant K was determined for each exponential radioactivity decay curve. On the basis of SPECT-derived K values our patients were grouped into hydrocephalus, nonhydrocephalus, and control patients. Twelve of 14 hydrocephalus patients were treated by shunt operation. Our less-invasive method showed reliable criteria for assessing the cerebrospinal fluid circulation.

Adolescent↗

PubMedDate not supplied

Antibody mediated targeting of radioisotopes, drugs and toxins in diagnosis and treatment.

The recent resurgence of interest in site specific delivery of radioisotopes, chemotherapeutic drugs and toxins for the diagnosis and treatment of cancer, and for the selective manipulation of the immune system, can be directly related to the need for improved diagnosis and the fact that for many cancers, for example lung, colon and gastric, the conventional treatments of surgery, radiotherapy and chemotherapy have reached a plateau in terms of the number of patients cured. To date, because of their specificity, the major emphasis has been on the use of antibodies as carriers and extensive in vitro, in vivo preclinical and clinical evaluation is underway. The aim of this article is to review recent progress, highlight avenues being explored to overcome limitations and to indicate new approaches that are evolving in antibody mediated targeting.

Antibodies, Monoclonal↗

PubMed1994

Fluctuations in Fe, Cu, Zn, Br, As, Se, and Rb concentrations in C57L/J mice bearing BW7756 murine hepatoma using radioisotope-induced X-ray fluorescence.

The effects of selenite or selenate supplementation on the concentration and distribution of Fe, Cu, Zn, As, Br, and Rb are investigated using the radioisotope-induced X-ray fluorescence, RIXRF. These effects are studied in the animals bearing BW7756 murine hepatoma and healthy animals for both of the oxidation states. Selenite and selenate induce different effects on the distribution of selenium, zinc, copper, bromine, and rubidium. The differences may be attributed to the differences in the inter element interaction after absorption into the bloodstream as well as to the mode of their intestinal absorption. Simultaneous supplementation of copper with selenite or selenate at the described levels has a profound influence on the concentration levels of other elements in the normal as well as in the diseased mice. The administration of selenium (0.67 micrograms/g body wt sodium selenite or sodium selenate, daily) and selenium and copper (0.67 and 1.35 micrograms/g body wt, respectively) has no effect on the incidence rate of hepatoma development.

Animals↗

PubMedDate not supplied

Radioisotope induced X-ray emission (RIXE) studies in life sciences.

The inherent advantages of radioisotope induced X-ray emission (RIXE) are briefly presented, with emphasis on their applications to analysis in the life sciences. The following selected applications by RIXE are discussed in general: (1) In vivo analysis: the determination of stable iodine in the thyroid and heavy metals in human bone; (2) the analysis of small tissue samples (about 10 mg) for the simultaneous determination of trace elements between 25 less than or equal to Z less than or equal to 40; data are given from a time study of the disease progress of Lewis lung tumor on a rat's liver over a 24-d period; and (3) a homogeneity study of iron, strontium, and zirconium in IAEA's SL-3 Lake sediment standard reference material is presented.

Animals↗

PubMed1998

Intracoronary radiation using radioisotope solution-filled balloons.

A substantial body of experimental evidence suggests that local application of radiation at sites of angioplasty or stent implantation prevents neointima formation. Recent initial clinical studies report a significant reduction in clinical restenosis rates when gamma emitting radiation sources are used to treat the site of coronary intervention. Because of the energy of therapeutic gamma sources and the shielding requirements, it would be far preferable to deliver ionizing radiation using a local beta emitter. This report discusses a number of the physical, biological, and technical parameters involved in radiation from a balloon angioplasty catheter filled with a beta emitting radioisotope solution.

Angioplasty, Balloon, Coronary↗

PubMed2003

Radioisotopic treatment of bone pain from metastatic prostate cancer.

Hormone-refractory prostate cancer patients with painful bony metastatic lesions are potential candidates for bone-seeking radiopharmaceutical therapies. After careful assessment of symptoms and localization of pain, a bone scan is the single most useful imaging modality for the clinician to assess patients for the presence and distribution of osteoblastic lesions. Increased uptake (compatible with bony metastases) on a conventional bone scan is currently a prerequisite for treating patients with a bone-targeted therapeutic isotope. Determining whether metastatic bony involvement is focal or diffuse is also important in the clinical decision-making process. Patients with multifocal metastatic disease are excellent candidates for systemic therapies, whereas patients with unifocal metastatic disease may be more appropriate candidates for focal therapies such as external-beam radiation. Patients who are poorly tolerant of narcotics should be actively considered for alternative treatments such as systemic radiopharmaceuticals. Contraindications to administration of current bone-seeking radioisotopes include substantial degrees of renal insufficiency or bone marrow suppression.

Bone Neoplasms↗

PubMed1988

Measurement of specific radioactivity of tryptophan labeled with carbon-14 in plasma by high-performance liquid chromatography with a synchronized accumulating radioisotope detector.

Measurement of specific radioactivity by a high-performance liquid chromatograph with a synchronized accumulating radioisotope detector was conducted. Accuracy of measurement for an authentic sample containing 0.2 nCi of tryptophan labeled with carbon-14 exceeded 95%. In the case of a plasma sample obtained 120 min following intravenous administration of 15 muCi of labeled tryptophan to a rat, the coefficient of variation was 7.0%.

Animals↗

PubMed1988

Measurement of specific radioactivity by high-performance liquid chromatograph with a synchronized accumulating radioisotope detector: determination of turnover rate and pool size of tryptophan in rat.

A high-performance liquid chromatograph with a synchronized accumulating radioisotope detector was used to determine the turnover rate and pool size of tryptophan in rat. The specific radioactivity could be followed for three half-lives on the final slope of the specific radioactivity curve following intravenous administration of 15 muCi of carrier free tryptophan labeled with carbon-14. Remarkable individual differences were noted in turnover rate and in pool size among rats.

Animals↗

PubMed1990

A sensitive radioisotopic method for the measurement of NAD(P)H: its application to the assay of metabolites and enzymatic activities.

A radioisotopic method for the assay of NADH or NADPH is presented, which is based on the conversion of 2-[U-14C]ketoglutarate to 14C-labeled glutamate in the reaction catalyzed by glutamate dehydrogenase. The efficiency of the method is close to 75%, its precision (coefficient of variation) close to 5%, and its sensitivity close to 0.1 pmol/sample. This simple and rapid method can be applied to the measurement of several metabolites and enzymatic activities. In the present study, its application to the assay of sorbitol, 3-hydroxybutyrate, glutamate dehydrogenase, 3-hydroxybutyrate dehydrogenase, and glyceraldehyde-3-phosphate dehydrogenase is documented.

3-Hydroxybutyric Acid↗

PubMed1990

Radioisotopic assays of CoASH and carnitine and their acetylated forms in human skeletal muscle.

Radioisotopic assays for the determination of acetyl-CoA, CoASH, and acetylcarnitine have been modified for application to the amount of human muscle tissue that can be obtained by needle biopsy. In the last step common to all three methods, acetyl-CoA is condensed with [14C]oxaloacetate by citrate synthase to give [14C]-citrate. For determination of CoASH, CoASH is reacted with acetylphosphate in a reaction catalyzed by phosphotransacetylase to yield acetyl-CoA. In the assay for acetylcarnitine, acetylcarnitine is reacted with CoASH in a reaction catalyzed by carnitine acetyltransferase to form acetyl-CoA. Inclusion of new simple steps in the acetylcarnitine assay and conditions affecting the reliability of all three methods are also described. Acetylcarnitine and free carnitine levels in human rectus abdominis muscle were 3.0 +/- 1.5 (SD) and 13.5 +/- 4.0 mumol/g dry wt, respectively. Values for acetyl-CoA and CoASH were about 500-fold lower, 6.7 +/- 1.8 and 21 +/- 8.9 nmol/g dry wt, respectively. A strong correlation between acetylcarnitine (y) and short-chain acylcarnitine (x), determined as the difference between total and free carnitine, was found in biopsies from the vastus lateralis muscle obtained during intense muscular effort, y = 1.0x + 0.5; r = 0.976.

Acetyl Coenzyme A↗

PubMed1987

Estimation of whole body bone resorption rate: a comparison of urinary total hydroxyproline excretion with two radioisotopic tracer methods in osteoporosis.

In 37 female patients with primary osteoporosis, urinary hydroxyproline excretion, determined in 18 24-h consecutive complete urine collections was compared with two radioisotopic measurements of bone resorption rate measured simultaneously using 85Sr. A somewhat better fit was obtained when the kinetically determined bone resorption rate was corrected for long-term exchange processes within bone. Regression analysis showed that the intercept of the regression of hydroxyproline excretion on resorption rate, corrected or uncorrected for exchange, was significantly higher than zero at about 100 mumol/day. This is consistent with a substantial fraction of urinary hydroxyproline arising from non-bony sources. Fifteen paired studies were analysed and the results suggested that intra-individual variability in these relationships (when studies were separated by a year or more) were similar to inter-individual variability. We calculated the precision with which an estimate of bone resorption could be determined based on the calculated regressions. As a means of non-invasive quantitation of whole body bone resorption rate, the excretion rate of hydroxyproline, measured over 5 days, for example, appeared competitive with isotopic methods making no correction for exchange and relatively little worse than our exchange corrected method.

Aged↗

PubMed1980

Radioisotopic 51Cr-leukocyte adherence inhibition (LAI) assay. I. Demonstration of anti-tumor immunity in patients with breast carcinoma.

A simplified radioisotopic leukocyte adherence inhibition assay (51Cr-LAI assay) was used to determine tumor-directed immune responses in patients with cancer of the breast. Essential steps in development of this assay are the standardization of conditions for optimal 51Cr uptake by peripheral blood lymphocytes (PBL) and the inclusion of autologous or normal AB serum in the incubation media. A dextrose salt mixture (GNK) was found to enhance intracellular uptake of 51Cr significantly (8-fold) without affecting viability of the cells or without causing selective loss of lymphocyte subpopulations. The presence of 10% autologous or normal AB serum prevented non-specific LAI responses to unrelated tumor antigens. In a study of 46 preoperative patients with suspected breast cancer, clear and accurate prediction of the presence of cancer was achieved with this new assay. All patients with localized breast cancer showed significant adherence inhibition in response to allogeneic breast tumor extracts whereas normal control women and patients with benign diseases did not respond. Neither patients with cancer nor those with benign breast diseases reacted to extracts of benign breast tissue antigens. LAI reactivities appeared to be directed selectively against tumor-associated antigens (TAA) and reflect specific antitumor immunity. This short term (4 h) 51Cr-LAI assay provides reproducible and specific results analogous to those using tube-LAI assay. The test has the advantages of being accurate, sensitive and free from technical bias.

Adult↗

PubMed1989

Development and characterization of monoclonal antibodies with specificity for metallic radioisotope chelators linked to antibodies and other proteins.

Monoclonal antibodies with specificity for the diethylenetriaminepentaacetic acid (DTPA) portion of the GYK-DTPA (glycyl-tyrosyl-lysine-DTPA) linker structure used to chelate metals to immunoglobulins have been prepared. A significant proportion of these antibodies were lambda light chain isotype. Competition assays demonstrated that DTPA, rather than GYK, was the binding site of the antibodies tested. These monoclonal antibodies should be useful reagents for use in assays specific for the presence of the common linker structure used to chelate metallic radioisotopes to monoclonal antibodies. The antibodies tested did not discriminate between chelated and unchelated DTPA.

Amino Acid Sequence↗

PubMed1976

Determination of prostaglandin F2alpha and E2 contents in human cerebrospinal fluid by the radioisotope dilution method.

Prostaglandin F2alpha and E2 contents in human cerebrospinal fluid were determined by the radioisotope dilution method. The mean values of PGF2alpha and PGE2 of men were 9.8+/-0.87 ng/ml and 6.5+/-1.39 ng/ml, respectively. Those of women were 8.3+/-1.4 ng/ml and 6.9+/-1.72 ng/ml, respectively. The correlation between age and PG was significantly with PGE2 of men and with PGF2alpha of women.

Adult↗

PubMed1983

Measurement of urinary histamine: comparison of fluorometric and radioisotopic-enzymatic assay procedures.

Assessment of urinary histamine may prove useful in determining the role of histamine in human health and disease. Urinary histamine may be accurately estimated by a modified fluorometric assay employing diamine oxidase (DAO) digestion and cation-exchange chromatography. Normal urine histamine values obtained by this assay are: arithmetic means (+/- SEM), 8.6 +/- 0.6 ng/ml and 10.5 +/- 0.7 micrograms/24 hr; geometric means (+/- SEM), 6.2 +/- 1.1 ng/ml and 10.0 +/- 1.3 micrograms/24 hr. However, the radioisotopic-enzymatic assay is less expensive, easier to perform, and possibly more sensitive. Therefore the two procedures were compared. The radioenzyme assay was found to be affected by factors in urine (possibly salt concentrations) requiring extraction of histamine from urine by butanol-heptane. Moreover, it was found to be necessary to compare DAO-digested samples with undigested samples to accurately estimate histamine levels and to run the standard curve of histamine in DAO-digested urine. Even with these modifications, the radioenzyme assay was not as accurate as the fluorometric assay for urine samples having histamine values about 60 ng/ml. Therefore we recommend utilization of the modified fluorometric assay for the measurement of urinary histamine levels.

Amine Oxidase (Copper-Containing)↗

PubMed1995

Comparable sensitivities for detection of HIV-1 reverse transcriptase (RT) and other polymerases by RT assays requiring no radioisotopic materials.

An improved non-radioisotopic (Non-RI) reverse transcriptase (RT) assay with a template-primer-immobilized microtiter plate is described, which has greater sensitivity than the former Non-RI RT assay previously described. Non-RI and commercially available non-radioactive (Non-RA) RT assays were compared for their ability to detect various polymerases. Two RTs from Rous-associated virus 2 (RAV-2) and avian myeloblastosis virus (AMV), one polymerase from Escherichia coli (Pol-I) and one recombinant RT of human immunodeficiency virus type 1 (HIV-1) were assessed. Two HIV-1 samples in a culture supernatant and pelleted virion suspended in Triton X-100 solution were measured. The Non-RI RT assay was one hundred times more sensitive by RAV-2 and Pol-I polymerases, and one thousand times more sensitive by the Non-RA assay than by the AMV RT. The Non-RI RT assay was 10, 16 and 64 times more sensitive than the Non-RA assay for measuring recombinant HIV-1 RT, pelleted virus and virus suspended in culture medium, respectively. To explain the discrepancy, it is shown that free biotin, such as in culture medium, disturbs the assay system of the Non-RA RT assay, but not the Non-RI assay. The present assay can be used to clarify the inhibitory mechanism of an anti-HIV-1 substance.

Animals↗

PubMed1986

The adequacy of radioisotope mixing from bolus injections in first-pass radionuclide angiographic assessment of right ventricular function: a study using gold-195m.

The adequacy of radioisotopic mixing in first-pass radionuclide studies of right ventricular function was assessed in 27 patients using multiple injections of gold-195m (half-life 30.5 sec). A theoretical disadvantage of the first-pass technique is inadequate mixing of the injected bolus with blood prior to entry into the right ventricle. Since the calculation of ejection fraction is based on the assumption of complete mixing, this would lead to errors. In order to assess the effects of bolus injection rates and bolus duration on the calculation of right ventricular ejection fraction, multiple, rapid, sequential studies were performed using gold-195m at four bolus injection rates (10, 5, 2 and 1 ml/sec). Slowing the injection rate caused a significant increase in bolus duration, and a significant increase in the number of cardiac cycles available for analysis. Mean ejection fraction, however, was not significantly changed. There was good correlation between right ventricular ejection fraction at all injection rates when compared to 10 ml/sec, and no injection rate led to a consistent over or underestimate of right ventricular ejection fraction. There was no significant relationship between change in bolus duration and variation in ejection fraction. These data indicate that mixing is adequate for first-pass studies of right ventricular function using a rapid bolus.

Cardiac Output↗

PubMed1982

Radioisotope therapy of cystic craniopharyngomas.

Eighteen patients suffering from cystic craniopharyngeoma were treated with intracavitary irradiation. The beta-emitting radioisotope 90y (2.25 MeV) was instilled into the cyst following stereotactic puncture of the space-occupying lesion. The surgical approach was planned using angiograms and reconstructed transmission computer tomography (TCT) coronal and saggital sections. Therapy was devised to deliver 20,000 rad to the cyst's wall. Eleven patients received follow-up TCT examinations after four months. Eight of 11 patients had a significant volume decrease in the craniopharyngeoma cyst. In two patients, the cystic volume remained unchanged; one had progression of disease. It is concluded that the intracavitary treatment of cystic craniopharyngeoma will result in a reduction of the size of the space-occupying lesion.

Adolescent↗