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PubMed2006

Stoichiometry of ATP and metal cofactor interaction with the sarcoplasmic reticulum Ca(2+)-ATPase: a binding model accounting for radioisotopic and fluorescence results.

Sarcoplasmic reticulum Ca-ATPase belongs to the P-type ATPases family and transports calcium at the expense of ATP hydrolysis. For years, a complex pattern of activity has been observed as a function of ATP and metal cofactor concentrations, leaving the stoichiometry of both metal and ATP in the active site as an open question. In agreement with recent structural studies we present here-using Mn as analogue of Mg-radioisotopic and fluorescence results showing that two metal ions bind to the Ca-ATPase favoring ATP binding. We further show that low ATP concentration favors the binding of these ions, whereas high ATP concentration is inhibitory. We propose a binding model for ATP and metal ions, which permits simulation of our data. Finally, we suggest that (i) the contribution of two metal ions as cofactors of ATP is essential to get maximal activity; (ii) the contribution of two ATP molecules can activate or inhibit the Ca-ATPase depending on metal concentration.

Adenosine Triphosphate↗

PubMed2006

A weighted bootstrap method for the determination of probability density functions of freshwater distribution coefficients (Kds) of Co, Cs, Sr and I radioisotopes.

The objective of the study was to provide global probability density functions (PDFs) representing the uncertainty of distribution coefficients (Kds) in freshwater for radioisotopes of Co, Cs, Sr and I. A comprehensive database containing Kd values referenced in 61 articles was first built and quality scores were affected to each data point according to various criteria (e.g. presentation of data, contact times, pH, solid-to-liquid ratio, expert judgement). A weighted bootstrapping procedure was then set up in order to build PDFs, in such a way that more importance is given to the most relevant data points (i.e. those corresponding to typical natural environments). However, it was also assessed that the relevance and the robustness of the PDFs determined by our procedure depended on the number of Kd values in the database. Owing to the large database, conditional PDFs were also proposed, for site studies where some parametric information is known (e.g. pH, contact time between radionuclides and particles, solid-to-liquid ratio). Such conditional PDFs reduce the uncertainty on the Kd values. These global and conditional PDFs are useful for end-users of dose models because the uncertainty and sensitivity of Kd values are taking into account.

Cesium↗

PubMed2006

Sediment radioisotope dating across a stratigraphic discontinuity in a mining-impacted lake.

Application of radioisotope sediment dating models to lakes subjected to large anthropogenic sediment inputs can be problematic. As a result of copper mining activities, Torch Lake received large volumes of sediment, the characteristics of which were dramatically different from those of the native sediment. Commonly used dating models (CIC-CSR, CRS) were applied to Torch Lake, but assumptions of these methods are violated, rendering sediment geochronologies inaccurate. A modification was made to the CRS model, utilizing a distinct horizon separating mining from post-mining sediment to differentiate between two focusing regimes. (210)Pb inventories in post-mining sediment were adjusted to correspond to those in mining-era sediment, and a sediment geochronology was established and verified using independent markers in (137)Cs accumulation profiles and core X-rays.

Fresh Water↗

PubMed1980

Rapid diagnosis of infections caused by beta-lactamase-producing bacteria by means of an enzyme radioisotopic assay.

We developed a sensitive enzyme radioisotopic assay for the measurement of beta-lactamase, an enzyme produced by a number of pathogenic bacteria. This ERIA was 100-fold more sensitive than the commonly used iodometric or spectrophotometric assays for the measurement of beta-lactamase and, unlike these other assays, the ERIA was not significantly influenced by serum proteins or unlabeled penicillin. Clinical specimens consisting of blood, peritoneal, pleural, and cerebrospinal fluids from patients infected with beta-lactamase-producing organisms yielded positive ERIA tests; fluids from uninfected patients were negative. The ERIA takes approximately 90 minutes to perform, and offers great potential for the rapid diagnosis of serious bacterial infections caused by bacteria which produce beta-lactamase.

Bacterial Infections↗

PubMed2003

Effect of radioisotope sentinel node mapping in patients with cT1 N0 M0 lung cancer.

BACKGROUND: Application of the sentinel node concept to lung cancer is still controversial. Patients with peripheral small lung cancers would gain the most benefit from this concept, if it were valid. We sought to determine whether it is possible to choose between limited lymph node sampling and systematic lymphadenectomy from the distribution of sentinel lymph nodes in patients with node-negative disease on the basis of imaging. METHODS: Sixty-five consecutive patients with cT1 N0 M0 non-small cell lung cancer were enrolled. A radioisotope tracer (4 mCi of technetium-99m tin colloid, 2.0 mL) was injected in the vicinity of the tumor before surgical intervention with computed tomographic guidance. The radioactivity of each resected lymph node was measured separately with a hand-held gamma probe after complete tumor resection. Sentinel nodes were identified, and the accuracy of sentinel node mapping was examined. Whether the location of the sentinel node depended on the site of the primary tumor was also examined. RESULTS: Of the 65 patients, 3 were excluded because of the final pathologic results. Successful radionuclide migration occurred in 39 (62.9%) of the 62 patients. There was 1 (2.6%) false-negative result among 39 patients with a sentinel node, and therefore the sensitivity was 90%, and the specificity was 100%. The most common sentinel lymph nodes were at level 12 (46.7%), followed by level 11 (18.3%), the mediastinum (16.7%), and level 10 (11.7%). CONCLUSION: The sentinel node concept is valid in patients with cT1 N0 M0 lung cancer. The lobar lymph nodes were identified as sentinel nodes more frequently than other lymph nodes. We need to make further efforts to increase the sentinel node identification rate. However, we believe that if sentinel nodes are identified, sentinel node mapping can allow the accurate intraoperative diagnosis of pathologic N0 status in patients with cT1 N0 M0 lung cancer.

Aged↗

PubMedDate not supplied

[Quantification of bone scintigraphy as an objective method in the follow-up of radioisotopic synoviorthesis].

This work tries to provide the clinicians an objective tool that can contribute to the assessment of the results of radioisotopic synoviorthesis (RS). This study aims to assess the value of the quantification of bone scintigraphy in blood pool and late phase of the affected joints treated with 90Y silicate, in order to observe the clinical improvement experienced by most of these patients. A total of 69 bone scintigraphies (BS) in blood pool and late phase have been quantified. They belonged to 23 patients who were treated with RS with 90Y. The first scintigraphy study was performed before the treatment, the second and the third ones were performed 2 and 6 months after treatment. In each BS we quantified the index: counts per pixel of healthy / affected joint. We also have calculated the fraction in the late phase: counts per pixel of healthy bone / counts per pixel of affected and healthy joint. For the comparative statistical analysis of the results we used the Student's t test. We considered statistical significance when p < 0.05. All the patients presented clinical improvement. If we compare the index obtained in BS 2 months after treatment and pre-treatment we find statistical significance (p < 0.05) in the increase of index in the anterior view and late phase. If we compare the index obtained in BS 6 month after treatment and pre-treatment, we find a statistically significant increase in the anterior (p < 0.01) and posterior (p < 0.05) view of the blood pool phase and the anterior view of late phase (p < 0.01). The fraction counts per pixel of healthy bone / counts per pixel of affected and healthy joint did not present a significant increase in any BS control (2 and 6 months). We recommend quantification using the index (counts per pixel healthy / affected joint ) proposed in this work, because it is easy to perform, cheap and reliable in the follow-up of patients treated with RS.

Adolescent↗

PubMed1989

Radio-gas chromatography on wide-bore capillary columns equipped with a synchronized accumulating radioisotope detector.

A gas chromatographic system with wide-bore capillary columns and synchronized accumulating radioisotope detector (SARD) was developed. A direct injection method and constant-flow regulation were applied. The performance of wide-bore capillary columns was good and the correspondence of the resolution obtained with SARD and that with mass detection was excellent. It was proved that the apparatus could detect of the order of 1 pg of 3H-labelled substances (3.7 TBq/mmol) and compete in terms of sensitivity with gas chromatography-mass spectrometry.

Chromatography, Gas↗

PubMed1984

Application of high-performance liquid chromatography with synchronized accumulating radioisotope detector to analysis of glyceryl trinitrate and its metabolites in rat plasma.

A new, sensitive, and specific high-performance liquid chromatographic method for the quantitative analysis of [14C]glyceryl trinitrate and its four metabolites in plasma is described. The drugs are extracted from 0.05 ml of plasma with methanol and analyzed by high-performance liquid chromatography using a synchronized accumulating radioisotope detector. The limit of detection is 0.2 ng per injection. The within-day coefficient of variation is 5.9% at a concentration of 27.0 ng per ml of plasma. The method was applied to single-dose pharmacokinetics of glyceryl trinitrate in rat.

Animals↗

PubMed1999

Enzyme inhibition XI: glutamate decarboxylase activity relationship with the reaction products as determined by the colorimetric and radioisotopic methods.

The relationship of glutamate acid decarboxylase (GAD) activity with the reaction products was developed. It was based on incubating sodium glutamate substrate (S) with GAD enzyme (E) when the enzyme-substrate-complex (ES) product was obtained along with gamma aminobutyric acid (GABA) and unreacted sodium glutamate. The reaction products were separated by paper chromatography. The ES, GABA and S products were sprayed with ninhydrin reagent when ninhydrin-colored-complex (NCC) was formed on the paper chromatogram. The products were extracted with 75% ethanol containing 0.5% cupric sulfate. The NCC absorption readings of ES and S products were measured by a spectrophotometer. A standard curve was prepared by plotting absorption readings against different concentrations of sodium glutamate. This curve was the basis of determining GAD activity of E. coli and C. welchii. It was observed that NCC absorption of ES and S products was directly related with the enzyme activity. The qualities of ES and S products in the reaction mixture increased as the enzyme activity increased with the incubation time. On the other hand, some products in the reaction mixture decreased in the presence of an inhibitor of GAD activity. The relationship of reaction products with GAD activity was also established by the radioisotopic method. The results obtained by the chromatographic separation of products followed by the spectrophotometric method of determining GAD activity is a simple, safe and less expensive compared to the other methods.

Arsenates↗

PubMed2003

Radioisotope for occult lesion localisation (ROLL) of the breast does not require extra radiation protection procedures.

AIM OF STUDY: Dosimetry data from patients and hospital personnel involved in the use of radioisotope for occult lesion localisation (ROLL) of the breast were collected to determine the need for extra radiation protection procedures. METHODS: Sixty-three patients have been enrolled to date into a randomised trial evaluating ROLL. Two megabecquerels of (99m)Tc- MAA in a syringe was mixed with X-ray contrast medium; this was injected directly into the lesion under image guidance. A gamma-detecting probe (Neo-Probe) was used to locate the area of radioactivity. Radiation doses to all staff groups were estimated using time and motion studies and dose rate measurements at a range of distances during each stage of ROLL. RESULTS: The finger dose [FD](+/-95% CI) was considered to be the critical variable for surgeons and radiologists. Surgeon FD=9.3+/-3.3 microSv, Radiologist FD=0.5+/-0.13 microSv. Whole body doses [WBD](+/-95% CI) were estimated for other staff groups. Nurse WBD=0.4+/-0.4 microSv, porter WBD: nil, contamination and waste: nil. CONCLUSIONS: In the case of a surgeon performing 100 procedures per annum, a FD dose of approximately 1 mSv is received, well within the annual dose limit of 150 mSv. Annual WBD to assisting staff may reach 0.04 mSv, compared to an annual limit of 6 mSv. These low doses and the lack of contamination of radioactive waste indicate that no additional radiation protection measures are required.

Breast Neoplasms↗

PubMed1995

Detectability of simulated brain activation using dual radioisotope SPECT based on size and intensity of the focal hyperactivity.

RATIONALE AND OBJECTIVES: Simultaneous single-photon emission computed tomography (SPECT) neuroimaging with both technetium-99m (99mTc) hexamethylpropyleneamine oxime (HMPAO) and iodine-123 (123I) N-isopropyl-iodoamphetamine is a recently introduced method with potential for assessing activation phenomena in the brain. However, there is limited information on the accuracy of the technique for detecting focal cortical sites of neuroactivation. We determined, in vitro, what levels of activation could be detected as a function of the size of the activated region. METHODS: A Lucite brain phantom was filled with both 123I and 99mTc so as to simulate both a nonactivated state (123I) along with focal sites of activation (99mTc). Simulated activations ranged from 0 to 18% in volumes of 7, 14, 20, and 27 cm3. Imaging was performed with a triple-detector gamma camera using a 10% symmetric window at 140 keV and 10% asymmetric window around 159 keV. No correction was made for gamma cross-talk. To determine whether a simulated activation was "detected," the 99mTc: 123I count ratios in the activated regions were compared by t test with ratios in nonactivated regions of similar volume. Detection sensitivities also were calculated as the fraction of the activated 99mTc: 123I ratios that were greater than the mean + 2 standard deviations of the corresponding nonactivated ratios. RESULTS: All sites of simulated activations of 10% or greater were detected. The detection sensitivity was 100% (95% confidence interval, 90-100%) for the two largest chambers with simulated activations of 13-18%. Activations in the 3-6% range, in the same-sized chambers, were detected with a limited sensitivity (67% with a confidence interval of 45-84%). In the 14-cm3 chamber, simulated activations in the 13-18% range were detected with 90% sensitivity (confidence interval, 74-98%). In general, the detection sensitivity was greater for larger chambers and higher levels of simulated activation. CONCLUSION: We conclude that the dual-radioisotope technique using triple-detector SPECT systems and low-energy all-purpose (LEAP) collimators should be highly reliable for identifying focal brain activations above 13% that cover at least 14 cm3 of brain cortex. Smaller, less intense sites of activation will be detected with reduced frequency. These conclusions are based on our assessment of only the physical parameters involved in this methodology and other factors (e.g., the possibility that the relation between cerebral radiotracer concentration and regional cerebral blood flow) may affect the results obtained with patients.

Brain↗

PubMed1968

The determination of glucosamine and galactosamine in some glycoproteins by radioisotope dilution.

1. The principle of radioisotope dilution was applied on a semi-micro scale to the determination of glucosamine and galactosamine in some glycoproteins, such as immunoglobulins, a urinary glycoprotein and blood-group-specific substances. 2. The glycoprotein was hydrolysed in the presence of [1-(14)C]glucosamine or [1-(14)C]galactosamine or both. The amino sugars were made to react with naphthyl isothiocyanate and the products formed were isolated by the method of Scott (1962). The specific radioactivities determined from liquid-scintillation counting and the extinction at 240mmu or 222mmu were used to calculate the content of amino sugars in the protein analysed. 3. Where the values could be compared with those found by other workers, differences were in general not very great. The advantages of the method are that high concentrations of acid can be employed and undesirable side reactions, which may occur with the free sugars, do not affect the results. A potential source of error of the method is discussed.

Carbon Isotopes↗

PubMed2000

Comparison of bioimpedance and radioisotope methods in the estimation of extracellular water volume before and after coronary artery bypass grafting operation.

To estimate extracellular water volume (ECW) changes in connection with coronary artery bypass grafting operation, simultaneous ECW estimations by 51Cr-EDTA dilution and whole-body bioimpedance techniques were performed in 15 patients. The assessments of ECW were compared with patients' weighing results. Whole-body bioimpedance-derived ECW correlated significantly with 51Cr-EDTA dilution-based ECW in the pre-operative period (r=0.74; P<0.005); the bias was 0.2 +/- 1.1 l (+/-SD). In the post-operative period, the agreement between these methods was poor, the bias being 0.5 +/- 2.5 l, and no significant correlation between the methods was found (r=0.38; P>0.05). Whole-body bioimpedance-derived ECW changes correlated significantly with weight changes of the patient induced by the operation (r=0.52; P<0.05). 51Cr-EDTA dilution-based ECW changes correlated neither with weight changes (r=0.33; P>0.05) nor with bioimpedance-derived ECW changes (r=0.03; P>0.05). Alterations in radioisotope tracer distribution and loss of it due to blood leakage in the post-operative period were presumed to explain the discrepancy between dilution technique and weighing results. The results suggest that bioimpedance is a useful non-invasive method for assessment of extracellular volume changes induced by coronary artery bypass grafting operations. 51Cr-EDTA dilution-based ECW determination is not suitable in related conditions.

Aged↗

PubMed2000

A novel balloon angioplasty catheter impregnated with beta-particle emitting radioisotopes for vascular brachytherapy to prevent restenosis; first in vivo results.

BACKGROUND: According to early clinical trials, vascular brachytherapy performed prior to or shortly after angioplasty is very effective in reducing restenosis rates. The purpose of this study was to investigate the effects of a novel radioactive catheter that allows simultaneous balloon angioplasty and beta-particle irradiation in the prevention of restenosis. MATERIAL AND METHODS: The balloon surface of an angioplasty catheter was impregnated with the radioisotope(32)P. Dosimetry calculations using a Monte Carlo method were performed at a radial distance of 0.2 mm from the balloon surface. Rabbit iliac arteries were dilated and simultaneously irradiated with a dose of 20 Gy delivered to the adventitia. Control arteries were only dilated and not irradiated. Neointimal areas, cell numbers and the perimeter of the arteries were measured by histomorphometry after 6 weeks. RESULTS: Neointima formation was reduced after balloon dilatation and simultaneous beta-particle irradiation using the(32)P impregnated angioplasty catheter as compared to balloon dilatation alone with a non-impregnated catheter (0.09+/-0.06 vs 0.27+/-0.09 mm(2)neointimal area and 168+/-45 vs 360+/-133 cells/0.05 mm(2)neointima, P<0.001 vs control, respectively). In addition, balloon dilatation with the(32)P impregnated angioplasty catheter increased the vessel perimeter as compared to balloon dilatation with a non-impregnated catheter (4. 7+/-0.2 vs 3.9+/-0.3 mm, P<0.001 vs control). CONCLUSIONS: Simultaneous balloon dilatation and vascular brachytherapy with a novel(32)P impregnated angioplasty catheter markedly reduces restenosis in vivo by preventing neointimal hyperplasia and constrictive vascular remodelling.

Angioplasty, Balloon↗

PubMed1989

Similar lethal effect in mammalian cells for two radioisotopes of copper with different decay schemes, 64Cu and 67Cu.

The decays of 64Cu incorporated in human malignant (A549) or monkey nonmalignant (CVI) cells lead to cell death. When plotted as a function of the radioactivity introduced in the growth medium (microCi/ml at t = 0), the residual colony-forming capability decreases exponentially. The slope of the corresponding curve is steeper for A549 than for CV1 cells. Different data show that the cellular lethal event is a consequence of 64Cu transmutation and not of the irradiation by the simultaneously emitted beta- and beta+ particles. Liquid holding results show that the lethal event is irreparable. The decays of 67Cu, another radioisotope of copper, lead to cell death with the same exponential survival curve and the same lethal efficiency as for 64Cu, in spite of their different decay schemes. The lethal efficiency of both copper isotopes is close to that of 125I utilized in the form of iododeoxyuridine under the same experimental conditions as 64Cu and 67Cu. The high lethal efficiency of radioactive copper transmutations raises questions about the role in DNA functioning of copper atoms known to be present in trace amounts in this macromolecule. The lethal consequence of radioactive copper transmutations suggests that the copper atoms bound to DNA are essential for cellular functioning.

Animals↗

PubMed2000

"Spin-labelling" with the second hydrogen radioisotope: radicals formed from squalene by muonium addition.

By radio-labelling with muonium (the second hydrogen radioisotope), a free radical species has been clearly identified in squalene (2,6,10,15,19,23-hexamethyl-2,6,10,14,18,22-tetracosahexaene ) with a muon-electron hyperfine coupling of 240.7 MHz, as measured by the muon spin rotation (MuSR) technique. The radical is undetectable in pure squalene due to its high viscosity and the large molecular size which leads to extreme line broadening, but its signals may be resolved on reducing the viscosity of the medium by dilution with diethyl ether. The potential of the MuSR method is thus demonstrated as a means for spin-labelling radical species such as are formed from cellular antioxidants; ESR spectroscopy is unsuitable for studies of radicals formed from this molecule, due to extreme line-broadening and spectral complexity.

Electron Spin Resonance Spectroscopy↗

PubMed1990

A method for computing the derivative of noisy time-activity curves and its application to radioisotope dynamic analysis.

A method for computing the slope or the derivative of time-activity curves containing statistical fluctuations is described. The algorithm presented employs digital differentiation as a digital filter. In designing an effective differentiating filter the Chebyshev-type min-max method and Remez exchange algorithm are used to minimise the weighted Chebyshev error. The validity of this method has been investigated using computer-based Monte Carlo simulation. Renogram curve analysis is presented as an example of an application of this method to radioisotope dynamic analysis. The ratio of the bilateral slopes of the renogram's second segments estimated using this method correlated well with the renal plasma flow ratio (r = 0.97, n = 16). The functional images of the slope of the renogram's second segments have been constructed and ascertained to be clinically useful. This method is considered to provide a powerful tool for extraction of quantitative information both in research and in routine nuclear medicine clinical work, and may be useful in various other fields.

Algorithms↗

PubMed2004

High-throughput screening with quantitation of ATP consumption: a universal non-radioisotope, homogeneous assay for protein kinase.

A number of assays have been developed for high-throughput screening (HTS) of potentially bioactive compounds. To screen millions of chemical compounds efficiently, the best detection technology prior to initiating HTS must be chosen. Ideally, a non-radioisotope (non-RI), homogeneous method, equivalent to the most reliable assay for a particular target, should be selected as an HTS method. Protein kinases are among the most important classes for drug discovery because they participate in various signaling pathways. Several HTS technologies are available for kinase activity: SPA (Amersham, Piscataway, NJ, U.S.A.), HTRF (CIS-US, Inc., Bedford, MA, U.S.A.), IMAP (Molecular Devices, Sunnyvale, CA, U.S.A.), and Z'-LYTE (Invitrogen, Carlsbad, CA, U.S.A.). The amount of phosphorylated product is detected by different methods in these assays. Recently, Kinase-Glo Luminescent Kinase Assay, a non-RI, homogeneous, adenosine triphosphate (ATP) quantitative kit useful for kinase activity detection, has become available from Promega (Madison, WI, U.S.A.). ATP is a universal substrate for kinases. Thus, the Kinase-Glo assay shows promise for becoming the primary method of determining kinase activity in HTS. We have developed a Kinase-Glo system for cyclin-dependent kinase 4 (Cdk4), and compare its results with those of the filtration method, the most reliable assay for in vitro Cdk4 activity. In addition, the reliability and sensitivity of the Kinase-Glo are discussed.

Adenosine Triphosphate↗