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PubMed1991

Regional cerebral blood flow during hypoxia-ischemia in the immature rat: comparison of iodoantipyrine and iodoamphetamine as radioactive tracers.

The indicator fractionation method was used to measure regional cerebral blood flow (rCBF) in immature rats, using either iodo-[14C]antipyrine (IAP) or isopropyl-[14C]iodoamphetamine (IPIA) as the radioisotope. Seven-day postnatal rats received a subcutaneous injection of either IAP (5 microCi) of IPIA (10 microCi), two minutes following which the animals were sacrificed and their brains prepared for quantitative autoradiography. Blood flows to cerebral cortex, hippocampus, striatum, thalamus and hypothalamus were comparable using the two methods, whereas blood flows to white matter structures were substantially higher (+ 64-85%) with IAP. Spatial resolution, especially of the gray matter structures, was greater with IPIA than with IAP. During cerebral hypoxia-ischemia (unilateral common carotid artery ligation and hypoxia with 8% oxygen), blood flows to all regions of the ipsilateral cerebral hemisphere were not different from control at 10 and 20 min. At 1-3 h of hypoxia-ischemia, blood flows were decreased in all analyzed structures of the cerebral hemisphere ipsilateral to the carotid artery occlusion, ranging from 7% to 40% of control values. A columnar or patchy distribution of preferential perfusion was seen within the cerebral cortex, striatum and thalamus, with IPIA, which corresponds closely to the pathologic pattern of injury seen within these structures of the immature rat. Such a preferential perfusion was not seen in hippocampus, in which metabolic factors (intrinsic vulnerability) most likely predict the distribution of hypoxic-ischemic brain damage.

Amphetamines↗
PubMed1989

99mTc ethoxy methylpropyl isonitrile: a radioactive tracer for myocardial perfusion imaging.

The initial experience with a new 99mTc labelled myocardial perfusion agent, ethoxy methylpropyl isonitrile (EMI), is described in the primate as model. Rapid biliary clearance of EMI ensures low radionuclide concentration in the liver and lungs after 60 min. Adequate visualization of the myocardium is therefore possible. Heart-to-lung and heart-to-liver ratios of 1.52 and 2.45 respectively were obtained. EMI is an efficient imaging agent to evaluate myocardial ischemia and infarction.

Animals↗
PubMed2005

Determination of soil adhesion to plastic surfaces using a radioactive tracer.

A quantitative radiochemical test procedure was developed for investigating soil adhesion on polyvinyl chloride (PVC) model materials containing different plasticizers (DOP and Hexamoll) and commercial flooring materials. A repeatable test procedure was developed, including soiling and cleaning with a Mini Cleanability Tester. Three soils all containing 51Cr emitting gamma radiation were used. The materials were subjected to successive soiling and cleaning cycles in order to generate soil accumulation. The type and amount of plasticizer appeared to affect soil adhesion on plastic model materials.

Journal Article↗
PubMed2006

Production and separation of no-carrier-added radioactive tracers of yttrium, strontium and rubidium from heavy-ion irradiated germanium target: applicability to the standardization of a separation technique for production of positron-emitting radionuclide 86Y.

Among various positron-emitting radionuclides, certain radioisotopes of Y, Sr and Rb have important applications in diagnostic and therapeutic nuclear medicine. In the present work, an attempt has been made to produce some of those radioisotopes by irradiating a natural Ge-target material with heavy-ion oxygen ((16)O(+6)) projectiles. An effective radiochemical separation scheme was developed to isolate Y, Sr and Rb radiotracers from the irradiated Ge-matrix in no-carrier-added form with a view to applying those radiotracers for standardization of a technique for the radiochemical separation of Y from natural Sr target. The standardized separation technique could be utilized for the production of the positron-emitting (86)Y from an enriched (86)Sr target irradiated at a medical cyclotron.

Electrons↗
PubMed1976

Estimation of blood flow with radioactive tracers.

The techniques of tracer dilution in the circulation, and of tracer uptake by and washout from an orgen, may be described using expressions that are general and are not dependent on specific models such as exponentials. The expressions have been applied to the measurement of cardiac output using impulse and constant rate injection techniques. Further expressions have been given for estimating organ blood flow from inflow/outflow concentration-time curves, and from the distribution of deposited tracer. Some problems with respect to the use of deposition techniques as they are ordinarily applied to the estimation of regional blood flow must be considered, particularly when there are capillary beds in series or where there is countercurrent diffusional shunting of diffusible tracers between inflow and outflow. This review deals with these various aspects of tracer theory as they relate to the measurement of blood flow.

Blood Circulation↗
PubMed1997

15 beta-Hydroxysteroids (Part VII). Steroids of the human perinatal period: the synthesis of steroid markers and their radioactive tracers.

We report the synthesis of 10 novel steroids obtained from 3 beta, 15 beta-diacetoxy-17 alpha-hydroxy-5-pregnen-20-one (1c) as intermediates in the synthesis of 15 beta-acetoxy-20,20-ethylenedioxy-17 alpha-hydroxy-4-pregnen-3-one (6a) and its tritiated tracer 15 beta-acetoxy-20,20-ethylenedioxy-17 alpha-hydroxy-1,2,6,7-3H-pregn-4-en-3-one (6d). The one pot interconversion of intermediate (6a) to 3 beta, 15 beta, 17 alpha-trihydroxy-5-pregnen-20-one (1a) and 3 alpha, 15 beta, 17 alpha-trihydroxy-5 beta-pregnan-20-one (2a) provides a new and efficient approach to the synthesis of diagnostically important metabolites of the human neonate and a possible route in the synthesis of the tritated tracers 3 beta, 15 beta, 17 alpha-trihydroxy-1,2,7-3H-pregn-5-en-20-one (1d) and 3 alpha, 15 beta, 17 alpha-trihydroxy-1,2,6,7-3H-5 beta-pregnan-20-one (2b) for the development of new immunoassays. We also report in this investigation an alternative route in the synthesis of 15 beta, 17 alpha-dihydroxy-4-pregnen-3,20-dione (7a) an intermediate in the synthesis of human 15 beta-hydroxysteroid metabolites.

Biomarkers↗
PubMedDate not supplied

Absorption and transport of radioactive tracers in the midgut of the malaria mosquito, Anopheles stephensi.

Three radiolabeled substances were mixed with fresh heparinized mouse blood and fed to female Anopheles stephensi through a chicken crop membrane. Resorption and transport in the anterior (A) and posterior (P, stomach) parts of the midgut were investigated by means of electron microscopic autoradiography. Digestion products of 125I-labeled bovine serum albumin (BSA) were resorbed only in the P-part, showing a biphasic pattern with maximal values 4 and 18 hr after feeding. Uptake of 3H-labeled amino acids started immediately after feeding in both midgut parts. [14C]glucose was mainly absorbed in the P-part. Labeled carbohydrate storage deposits formed during the initial phase of digestion and were mobilized around 36 hr after feeding. After feeding the mosquitoes on 125I-BSA, oocyte protein yolk spheres and abdominal cuticle became labeled. Ingestion of 3H-labeled amino acids caused the formation of silver grains over follicles and fat body lipids. Feeding on [14C]glucose resulted in labeled fat body carbohydrates and oocyte protein yolk spheres.

Animals↗
PubMed1997

Use of radioactive tracers in the evaluation of penile hemodynamics: history, methodology and measurements.

Radionuclide tracer techniques are intimately associated with some of the early ground-breaking investigations in erectile dysfunction and have evolved along with the field. At the present time, the various investigations can be grouped into four categories: labeled blood-pool; tracer washout; tracer washin and combined blood-pool/tracer and tracer washout examinations. Blood pool studies are most useful in assessing the integrity of arterial inflow, but may also be used to generate indices of venous leak. A non-imaging version of the blood-pool test may represent a simple and cost-effective alternative. Washout of intracavernosal xenon during erection seems the most rigorous method of testing venous integrity. Washout using 99mTc-labeled substances may emerge as a convenient alternative to the more technically difficult xenon examinations. Dual-isotope blood pool and washout examinations, though complicated, represent an ideal method of analyzing penile hemodynamics, with potential to contribute significantly to the understanding of penile physiology. Development of improved pharmacologic stimuli and augmentation of testing protocols by intracavernosal pressure monitoring may further improve the utility of quantitative and physiologic nuclear medicine examinations in erectile dysfunction.

Animals↗
PubMed2004

Sentinel lymph node biopsy in breast cancer--experience with the combined use of dye and radioactive tracer at Aarhus University Hospital.

One hundred and twenty-four patients with palpable tumours underwent sentinel lymph node biopsy (SLNB) and subsequent axillary lymph node dissection. Ultrasound of the axilla was used as part of the diagnostic work-up on all patients and those with lymph node metastasis verified by fine-needle aspiration biopsy (FNAB) were not included. For identifying the SLNs, a combination of Tc-99m-labelled human albumin (Solco-ALBU-RES) and blue dye (Patent Blue V) was used. No lymphoscintigraphy was performed. The SLN was successfully identified in 122 out of 124 (98%) patients and 66 (54%) patients were found to have metastatic involvement of the axillary lymph nodes. In 52 (79%) of these patients, the SLNs were the only nodes involved, 28 (54%) had micrometastasis only. The false-negative rate was 1.5%. This method has proven valid in the staging of the axilla in patients with breast cancer. The advanced techniques of serial sectioning and immunohistochemical staining further improve the diagnostic advantage offered by the SLNB, as it increases the possibility of diagnosing micrometastatic deposits.

Adult↗
PubMed1988

The use of gamma functions in the calculation of organ perfusion functions for non-diffusible radioactive tracers.

This paper introduces a method for quantification of mean organ perfusion by the impulse response function using the experimental time-activity curves for the organ of interest and its supplying artery. These are approximated by gamma functions and a general expression for the impulse response function is then derived. In any particular case, the impulse response function can be calculated simply by insertion of the numerical parameters. The procedure combines speed with freedom from random measurement errors. As an example of a clinical application, the impulse response function of healthy brain tissue is calculated and some clinically important parameters are tabulated.

Blood Circulation↗