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PubMed1975

Measurement of right ventricular volumes using 131I-MAA.

A method has been presented for determining the right ventricular residual ratio, that is, the ratio of the end-systolic volume to the end-diastolic volume during each cardiac cycle. 131I-MAA was injected as a bolus into the right ventricle, and the ratio of isotope remaining in the chamber during the succeeding cardiac cycles was determined with a collimated scintillation counter placed over the right ventricle. Since the counter detected the radioactivity from the entire right ventricular cavity, potential errors from incomplete mixing were minimized. The washout curve from the ventricle was distorted somewhat by the accumulation of isotope in intervening lung tissue. This distortion was eliminated by subtracting the build-up curve of radioactivity in the lung recorded simultaneously with a second scintillation counter positioned over the lateral chest wall. In 14 dogs anesthetized with chloralose, the right ventricular residual ratio was relatively constant at 40.4 plus or minus 3.1 per cent. Duplicate measurements differed by less than 3 per cent indicating the good reproducibility of the method. Right ventricular stroke volume was determined from cardiac output (dye dilution) and heart rate. With this and the simultaneously determined residual ratio (131I-MAA), end-diastolic volume could be calculated. Stroke volume and stroke work were highly correlated with end-diastolic volume, in keeping with the Frank-Starling mechanism.

Animals↗
PubMed1995

Application of Cerenkov radiation for the assay of 226Ra in natural water.

A Cerenkov based method has been developed for the determination of 226Ra via its beta-emitting daughters, 214Bi and 214Pb. Radium isotopes are separated from interfering elements by coprecipitation on barium sulphate. The precipitate is dissolved in an alkaline solution of EDTA and the Cerenkov signal produced by the build-up of daughter beta activities is counted after 25 days using the tritium channel of a liquid scintillation counter. To correct for any contribution from the daughters of the radium isotopes 224Ra and 228Ra present in the sample, the barium(radium) sulphate is reprecipitated, dissolved in EDTA, and counted 2 days later. Using this procedure, 228Ra can be determined in the same sample. Cerenkov counting efficiency was found to be 77.25%. A lower limit of detection of 17.4 mBq l-1 (based on 3 sigma of the background with 500 min counting time) was achieved. Any liquid scintillation counter can be used. Chemical recoveries in the range 75-95% were determined gravimetrically. Data from both artificial spiked samples and natural samples are presented.

Bismuth↗
PubMed1999

[Measurement of cerebral blood flow the blood sampling method using 99mTc-ECD: simultaneous scintigram scanning of arterial blood samples and the brain with a gamma camera].

To measure regional cerebral blood flow (rCBF) by blood sampling using 99mTc-ECD we devised a method of measuring the radioactive concentration in arterial blood sample with a gamma camera. In this method the head and a blood sample are placed within the same visual field to record the SPECT data of both specimens simultaneously. The results of an evaluation of the counting rate performance, applying the 30 hours decaying method using 99mTc solution showed that this method is not comparable to the well-type scintillation counter and in clinical cases the active concentration in arterial blood sample remained well within the dynamic range. In addition, examination of the influence of scattered radiation from the brain by the dilution method showed that it was negligible at a distance of more than 7.5 cm between the brain and the arterial blood sample. In the present study we placed a head-shaped phantom next to the sample. The results of the examinations suggested that this method is suitable for clinical application, and because it does not require a well-type scintillation counter, it is expected to find wide application.

Blood Specimen Collection↗
PubMed2002

Simultaneous determination of (45)calcium and (65)zinc uptake by caco-2 cells.

A simple method for simultaneously determining cell-associated Ca and Zn in Caco-2 cells is described. Calcium and zinc uptake was measured via radioisotopes (45)Ca and (65)Zn. Preliminary studies revealed that (65)Zn, a positron (beta(+)) and gamma emitter, contributed to (45)Ca counts in a liquid scintillation counter (LSC). However, (45)Ca, being a true beta emitter, did not contribute to the counts in a gamma counter (gammaC). To differentiate the counts of (45)Ca from those of (65)Zn, first a (65)Zn-labeled cell suspension was read in a gammaC and an LSC, thus obtaining the relationship between the radioactive counts obtained from the gammaC and LSC. This information defined the linear relationship between gammaC (65)Zn counts per minute (CPM) and LSC (65)Zn CPM. Because the (45)Ca and (65)Zn counts obtained in the LSC are additive, giving total LSC CPM, the value of LSC (45)Ca CPM was obtained by subtracting LSC (65)Zn CPM from total LSC CPM for the dual-labeled cell sample, obtaining then LSC (45)Ca CPM. To determine the absolute activity or disintegrations per minute (DPM) of each isotope in the dual-labeled sample, the linear relationship between DPM and CPM was determined for each isotope. The method is simple and straightforward for the determination of (45)Ca counts from a sample also containing (65)Zn, using gamma and liquid scintillation counters.

Caco-2 Cells↗
PubMed2005

[Inducing hepatocellular carcinoma-specific cytotoxic T lymphocyte response using formed by fusion of FastDCs and allogeneic human hepatocellular carcinoma cells].

OBJECTIVE: To fuse human hepatocellular carcinoma (HCC) cells with mature monocyte-derived dendritic cells (FastDC) and to observe in vitro the function of the fused cells in stimulating autologous T cells proliferation and inducing HCC-specific cytotoxic T lymphocyte (CTL) response. METHODS: CD14(+) cells were isolated and purified from the peripheral blood of a healthy HLA-A2 blood donor and cultured in fresh dendritic cell complete medium for 24 h, then proinflammatory mediators were supplemented for another 24 h, thus generating mature dendritic cell (FastDCs). The FastDCs were fused with human HCC cells of the line HCCLM3 to generate novel dendritoma. T cells were isolated from selected CD14(-) cells and then divided into 4 groups to be stimulated with dendritoma cells, DCs, HCCLM3 cells, and mixed DCs-HCCLM3 cells respectively for 96 hours. 18 hours before the end of cultivation (3)H-TdR was added into the culture fluid. Scintillation counter was used to measure the cpm values. CD8(+)T cells were isolated from CD14(-) cells, and added with different stimulating cells radiated by (60)Co and IL-2, IL-6, and IL-7. The values of IFN-gamma in the supernatants of the culture fluid of CD8(+)T cells with dendritoma cells, DCs, HCCLM3 cells, and mixed DCs-HCCLM3 cells was measured. HCCLM3, K562, HLE, self monocytes labeled with Na(2)(51)CrO(4) were added with effector cells, gamma-scintillation counter was used to measure the cpm value so as to calculate the killing ability of CTL. RESULTS: The CTLs activated by dendritoma cells specifically killed the HCCLM3 cells in the context of MHC class I and acted less vigorously against the control target cells. The CTLs activated by dendritoma cells were stronger in killing HCCLM3 cells than DCs, HCCLM3 cells, and mixed DCs-HCCLM3 cells (all P < 0.05). The killing activity was decreased on the HCCLM3 cells incubated with anti-HLA-ABC antibody. Three, five, and seven days after co-cultivation the value of IFN-gamma in the supernatants of the culture fluid of CD8(+)T cells with fused cells, DCs, HCCLM3 cells, and mixed DCs-HCCLM3 cells increased gradually, especially in the supernatants of the culture fluid of CD8(+)T cells with dendritoma cells (400 pg/ml +/- 60 pg/ml 3 days after, 1030 pg/ml +/- 160 pg/ml 5 days after, and 1260 pg/L +/- 180 pg/L 7 days after). CONCLUSION: The novel dendritomas formed with HCCLM3 cells and mature FastDCs from healthy human peripheral blood CD14(+) monocytes are potent stimulators for CD8(+)T cells in inducing HCCLM3 cell-specific lysis. With shorter time required for in vitro DC development, the rapid method of generation of dendritoma is more economic and may represent a new strategy for immunotherapy of hepatocellular carcinoma.

CD8 Antigens↗
PubMed2005

Analysis of low level radioactive metabolites in biological fluids using high-performance liquid chromatography with microplate scintillation counting: method validation and application.

TopCount, a microplate scintillation counter (MSC), has been recently employed as an off-line liquid radiochromatographic detector for radioactive metabolite profile analysis. The present study was undertaken to validate TopCount for metabolite profiling with respect to sensitivity, accuracy, precision and radioactivity recovery. Matrix effects of various human samples on TopCount performance and capability of MSC for volatile metabolite analysis were also investigated. TopCount had a limit of detection (LOD) of 5 DPM and a limit of quantification (LOQ) of 15 DPM for [(14)C]-labeled compounds at a 10min counting time. It was two-fold more sensitive than a liquid scintillation counter (LSC), and 50-100-fold more sensitive than a radioactivity flow detector (RFD). TopCount had comparable accuracy and precision to RFD, and comparable precision to LSC for determining relative abundance of metabolites. Human liver microsome incubation (up to 1 mL), plasma (up to 1 mL), urine (up to 2 mL) and feces (up to 50mg) had no significant quenching effects on TopCount performance. Benzoic acid, a volatile metabolite, was detected by TopCount, but not by Microbeta counter after microplates were dried under vacuum. Radioactivity recovery in HPLC-MSC analysis was reliably determined using an LSC-based method. Examples of using HPLC-MSC for analysis of low levels of radioactive metabolites are presented, including determination of plasma metabolite profile, in vitro reactive metabolites trapped by [(3)H]glutathione, and metabolite concentrations in an enzyme kinetic experiment. The data from this study strongly suggest that HPLC in combination with TopCount is a viable alternative analytical tool for detection and quantification of low levels of radioactive metabolites in biological fluids.

Animals↗
PubMed1976

Automatic quantitative radiometric assay of bacterial metabolism.

In a two-compartment scintillation vial, suspensions of bacteria were cultured with 1 muCi of [U-14C] glucose and the released 14C02 was measured continuously, cumulatively, and automatically in a liquid-scintillation counter modified to maintain sample temperature at 37 degrees C. We could follow the metabolism of bacterial populations through their early phase of exponential growth with good precision. The data were obtained conveniently, with use of conventional reagents, glassware, and counting equipment. From analysis of the exponential portion of the curves for cumulative activity vs. time, we could measure cell replication rate precisely in units of time. The resulting values were demonstrably independent of some common experimental variables, including the number of bacteria in the inoculum and counting system sensitivity. Sensitivity of the bacteria to antibiotics was measured to within a few percent by noting the relative prolongation of replication time in the presence of those inhibitors. The digital data from the scintillation counter are susceptible to on- or off-line computer analysis, thus providing the prospect for a totally-automated analytical system. The method shows promise for the mechanized quantitative analysis of bacterial growth, and its inhibition.

Anti-Bacterial Agents↗
PubMed1998

Accuracy and clinical utility of the mini-dose 14C-urea breath test in the evaluation of Helicobacter pylori infection.

The aim of this study was to evaluate the accuracy of the 14C-urea breath test by comparing the results to those obtained by endoscopy with mucosal biopsy. We also examined the value of the breath test result obtained prior to endoscopy in predicting peptic ulcer disease. Forty-two individuals underwent the 14C-urea breath test. Collections of expired C02 were analysed using a liquid scintillation counter. All individuals then underwent endoscopy with biopsy. Biopsy material was evaluated by the rapid urease method and by histology for the presence of H. pylori. Our results demonstrated that the 14C-urea breath test was 100% sensitive and specific when compared to the rapid urease test as the 'gold standard' for the detection of H. pylori. In comparison to pathology, the sensitivity remained 100% and the specificity was 89%. The results of the 14C-urea breath test had a poor predictive value for the determination of peptic ulcer disease. We conclude that the 14C-urea breath test can be easily performed at any medical facility equipped with a liquid scintillation counter and can accurately detect H. pylori. A negative breath test result could not exclude the presence of peptic ulcer disease.

Adult↗
PubMed1972

Technetium-99 m in the diagnosis of thyrotoxicosis.

The thyroid uptake at 20 minutes of intravenously administered Technetium-99(m) ((99m)Tc) was measured in 117 patients with a standard scintillation counter. Patients were divided into three groups on the basis of clinical assessment, four-hour (131)I uptake, triiodothyronine (T-3) resin uptake, and protein-bound iodine measurements.In 31 patients with no evidence of thyroid disease the mean (99m) Tc uptake was 1.8% +/-S.D. 1.1%. In 32 patients with thyroid enlargement who were euthyroid the mean uptake was 2.5% +/-S.D. 2.2%. In 54 thyrotoxic patients the mean uptake was 17.7% with a range of 4.1 to 44%, all cases having an uptake above the upper limit of normal (4.0%). These results agree closely with reported uptake studies using scanning techniques. In seven patients the extrathyroidal neck activity was measured by using a scanner, and the mean was 6.3% of the extrathyroidal total body radioactivity comparing favourably with an assumed 6% used in our calculations.We have shown that the measurement of the thyroid uptake of (99m)Tc with a scintillation counter is of value, and that it is not necessary to use scanning techniques in the diagnosis of thyrotoxicosis. Advantages of (99m) Tc are minimal radiation, reduction in patient and laboratory time, and low cost.

Female↗
PubMed1996

Luminol-and lucigenin-amplified chemiluminescence with rat liver microsomes. Kinetics and influence of ascorbic acid, glutathione, dimethylsulfoxide, N-t-butyl-a-phenyl-nitrone, copper-ions and a copper complex, catalase, superoxide dismutase, hexobarbital and aniline.

For the investigation of luminol (LM)-and lucigenin (LC)-amplified chemiluminescence (CL) in rat liver microsomes using both a liquid-scintillation counter (LKB/Wallac 1219 Rackbeta) and a Berthold luminometer (AutoLumat LB 953) optimal incubation mixtures and conditions and basic kinetics have been established. Whereas calibration curves for both LM- and LC-CL are performed with hydrogenperoxide (LC quantum yield is 6.25 fold higher as that of LM), distinct differences were revealed with microsomes, indicating that different reactive oxygen species (ROS) are determined: Both LM- and LC-CL follow the kinetics of enzymatic reactions in terms of dependence on protein and NADPH or NADH concentration, time course, temperature etc., but with differences. LM-CL does not work without addition of Fe2+, whereas LC-CL does. Both copper ions and copper bound in a complex abolish CL, LC-CL being much more sensitive. Isolated cytochrome P-450 (P450) and NADPH P450 reductase from liver of pheno-barbital treated rats alone proved to be inactive in LM-and LC-CL production, whereas te combination 1:1 without and with addition of lipid was highly active in both LM-and LC-CL. Ascorbic acid and glutathione as scavengers diminish both LM- and LC-CL in concentrations higher then 10(5). Dimethyl-sulfoxide (DMSO) was ineffective in LM-CL up to concentrations of 0.2 M, the very high concentration of 2 M diminished LM-CL only to 1/3. LC-CL was diminished starting at concentrations of 100 mM and at 2 M only 10% of maximum LC-CL was observed. The trap substance N-t-butyl-a-phenylnitrone (BNP) also diminished LC-CL more effectively than LM-CL. Clearcut differences were revealed by the addition of catalase and superoxide dismutase: both enzymes diminished LM-CL only, without any influence on LC-CL. Hexobarbital, a potent uncoupler of P450, enhances LM-CL fivefold, whereas LC-CL is barely influenced. Aniline (without uncoupling capability) decreased both LM-and LC-CL increasingly with increasing concentrations. Therefore the conclusion is drawn that LM-CL measures in liver microsomes predominantly superoxide anion radicals, whereas LC-CL is mainly a measure for microsomal hydroxyl radical formation or of reactive organic radicals. With microsomes of phenobarbital and beta-naphthoflavone treated rats CL was much higher but in principle the same kinetic characteristics could be shown. All results on microsomes were obtained uniformly with the liquid scintillation counter and the Berthold luminometer, the letter being much more effective and more sensitive.

Acridines↗
PubMed2004

Neutron spectra and angular distributions of concrete-moderated neutron calibration fields at JAERI.

The Facility of Radiation Standards of Japan Atomic Energy Research Institute has been equipped with concrete-moderated neutron calibration fields as simulated workplace neutron fields. The fields use an 241Am-Be neutron source placed in the narrow space surrounded by concrete bricks, walls and floor. The neutron spectra and the neutron fluence rates of the fields were measured with the Bonner multi-sphere spectrometer system (BMS), spherical recoil-proton proportional counters, and a liquid scintillation counter (NE-213). The results were compared with each other. The reference values of H*(10) were determined from the results of BMS. The angular distributions of neutron fluence were calculated using MCNP-4B2 to obtain the reference values of Hp(10). The calculated results show that the scattered neutrons have a wide range of incident angles. The reference Hp(10) values considered the angular distribution were found to be 10-18% smaller than those without consideration.

Algorithms↗
PubMed1992

Whole-body cesium 137 activity up to 4 years after the Chernobyl reactor accident in premature newborns, newborns, infants, and children.

Cesium 137 activity was measured after the Chernobyl incident in a whole-body radiation counter (4-pi-scintillation counter) in 85 premature and mature newborns (group 1), 174 infants and young children up to 2 11/12 years (group 2), and 48 children between 3 and 8 years (group 3) from Bonn (Germany) and surroundings. In 1987 the mean level of radioactivity in group 2, at 3.7 Bq/kg body weight corresponding to a mean radiation exposure of 11 muSv/y, was lower than that of group 1 (5.8 Bq/kg, 17 muSv/y) and 3 (9.4 Bq/kg, 28 muSv/y). Up to 1990 the values of all groups revealed a continuous decrease. The latest measurements showed mean values of 0.5 Bq/kg (1.5 muSv/y) in group 1, 0.6 Bq/kg (1.8 muSv/y) in group 2, and 0.8 Bq/kg (2.4 muSv/y) in group 3. A comparison with present cesium 137 values and determinations of the end of the 1950s and beginning of 1960s, both in adults, showed good agreement. The effective dose-equivalent rates amounted to less than 1% of that from natural radiation exposure. These levels should present no teratogenic risks to the population studied and, while there are theoretical mutagenic risks, the dose is so low that no increase in measurable mutagenic effects should be observed.

Accidents↗
PubMed1978

The measurement of calcium absorption and absorption rate with an external arm radioactivity counter.

1. A large-volume scintillation counter was used to measure calcium absorption from the ratio of forearm uptake of 47Ca after oral 47CaCl2 (administered with milk) to forearm uptake after intravenously administered 47CaCl2. 2. In some subjects serial measurements of both forearm uptake of 47Ca and blood 47Ca radioactivity were also recorded, and by using deconvolution both total calcium absorption and calcium absorption rate were determined. 3. The forearm ratio determination of 47Ca absorption correlated well with that obtained by deconvolution of either serial blood 47Ca or forearm 47Ca measurements provided that the forearm radioactivity measurements were made at least 8 h after the administration of 47CaCL2. 4. Although the two deconvolution techniques gave similar estimates of total calcium absorption there were discrepancies between their measurements of calcium absorption rate. These discrepancies were reduced but not eliminated by the use of additional lead shielding around the Armac counter.

Absorption↗
PubMed1993

Effect of static magnetic fields on osteoblasts and fibroblasts in vitro.

In vitro assays were made of the effect of a static magnetic field of a neodymium magnet on cellular behavior. The cell turnover rate was examined by the incorporation of radioactive thymidine, and anabolic processes were measured by the incorporation of radioactive proline. Cell cultures of fibroblast- and osteoblast-like cells of the neonatal rat calvarium were assayed to determine uptakes of radioactive thymidine and proline; these assays were performed in conjunction with examination of an explant of the rat calvarium. The cells were assayed after exposure to a field for 1-, 3-, 5-, 7-, and 10-day periods. Cells were exposed to north and south poles with a pole-face flux density of 0.61 T; control cultures were exposed to an unmagnetised piece of neodymium. After sham exposure or exposure to the magnetic field, 50 microCuries/ml of culture media of isotope were added to the culture medium. The cultures were returned to an incubator for 6 h. Then, following centrifugation, the supernatant was assayed for radioactivity in a scintillation counter after addition of 3 ml of scintillation fluid. A statistically significant magnetic stimulation of turnover rate and synthesis of fibroblasts was found, but stimulation of osteoblasts did not occur. Conversely, the explants, which represent the osteoblasts and fibroblasts in an organised system, showed a statistically significant inhibition in uptake of the radioactive label. The data indicate both variability and diversity of cellular behaviour, and they accentuate the need for caution in the interpretation of effects of static magnetic fields.

Animals↗