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Results for “Ruthenium Radioisotopes”

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At least 19 recordsLinked to original sources
PubMed1994

A ruthenium-103 red dot blot assay specific for nanogram quantities of sulfated glycosaminoglycans.

Ruthenium-103 red has been used previously to detect nanogram quantities of glycosaminoglycans after they have been separated by electrophoresis on cellulose diacetate. We have applied the critical electrolyte principle to the binding of this dye to polyanions. This eliminates interaction with nucleic acids and hyaluronan. After samples are digested with chondroitinase ABC the method allows the measurement of chondroitin sulfates and heparan sulfates at the 2-ng level in dot blots of tissue extracts.

Animals↗
PubMed1988

Effect of microbial biomass reduction by gamma-irradiation on the sorption of 137Cs, 85Sr, 139Ce, 57Co, 109Cd, 65Zn, 103Ru, 95mTc, I by soils.

Six soils, two Sphagnum peat samples and a clay mineral were irradiated with 40 and 80 kGy (4 and 8 Mrad) from a 60Co source. As a result the microbial biomass, determined separately for each sample, decreased considerably. Depending on the radionuclide, the sorption, as characterised by the distribution coefficient, decreased, increased or remained unchanged. The effect of the irradiation on the sorption of the radionuclides depended, in general, also on the type of the sample, especially whether well humified soils, (e.g. crop soils), poorly humified samples (Sphagnum peat, O-horizon from woodland), or a clay mineral was employed. The data reveal that irradiation produces, besides sterilization, also other effects in soils, which can change their sorption properties.

Adsorption↗
PubMed2004

Modelling the vertical distribution of radionuclides in soil. Part 1: the convection-dispersion equation revisited.

The convective-dispersive transport and linear sorption model is discussed for the vertical migration of radionuclides in soil. An alternative procedure of solving the corresponding system of partial differential equations is presented as well as the special solution for the pulse-like fallout initial condition. Idealizations and simplifications of the model and properties of the solution are discussed. The model is fitted to a set of 528 measured radionuclide soil profiles and the resulting model parameters, apparent convection velocity v and apparent dispersion constant D, are evaluated statistically. Typical orders of magnitude of the velocities and the diffusion constants of Chernobyl-134Cs are 0.3 cm/year and 0.3 cm2/year, respectively. The mobilities of the radionuclides are ranked as 137Cs (global fallout) < 134Cs < 106Ru, 125Sb. Significant regional differences (related to different soils and geological properties below ground) of v and D exist. These analyses also indicate that v and D are not mere fitting parameters, but can be given a real physical interpretation. While in most cases, the convection-dispersion equation (CDE) model produces good descriptions for near-surface soil layers, potentially important limitations are its failure to describe "young" profiles shortly after fallout.

Antimony↗
PubMed2004

Accumulation history of radionuclides in the lichen Stereocaulon vesuvianum from Mt. Vesuvius (south Italy).

The fruticose lichen Stereocaulon vesuvianum, growing on the slopes of Mt. Vesuvius (south Italy), was used as a biomonitor of 134Cs, 137Cs, 103Ru and 106Ru derived from the April 26 1986 Chernobyl nuclear reactor accident. Samples were taken at five different quotes (370, 490, 580, 780 and 960 m a.s.l.) and four successive dates (October 1986, December 1986, October 1987 and May 1999). At the first sampling, the concentrations (as Bq kg(-1) dry weight) ranged between 460 and 1020 for 134Cs, 1330 and 2500 for 137Cs, 90 and 200 for 103Ru and 360 and 710 for 106Ru, values generally lower in respect to those measured in soil and higher plants. Of the total 137Cs measured only 14% was due to 1950s and 1960s nuclear weapons tests fallout. Highest average activities of all nuclides were observed at the quote of 960 m and significant correlation (0.7<r(2)<0.9) with altitude was found for 106Ru and 137Cs values. The time span between the first two samplings (38 days) was enough to highlight only the decay of 103Ru (T1/2=40 days). At sampling performed 1 year later (October 1987) only 134Cs, 137Cs, and 106Ru were observed. Thirteen years after the Chernobyl incident (May 1999), although a decrease was obvious with time, the 137Cs content in lichen thallus was still appreciable (270-570 Bq kg(-1) dw). Experimental results from the first three samplings yield effective residence time of 0.98+/-0.07, 5.9+/-0.3 and 1.6+/-0.1 years for 106Ru, 137Cs and 134Cs, respectively. The last sampling of May 1999 allowed to achieve a more precise determination of lifetime of 137Cs (6.1+/-0.4 years).

Air Pollutants, Radioactive↗
PubMed1990

Prone position reverses gravitational distribution of perfusion in dog lungs with oleic acid-induced injury.

Although oxygenation improves in patients with the adult respiratory distress syndrome and in animals with oleic acid- (OA) induced acute lung injury when they are turned from the supine to the prone position, the mechanism(s) by which this improvement occurs is not known. Several groups have speculated that this improvement results from preferential edema accumulation in the dorsal lung regions and redistribution of perfusion away from these regions when the patients are turned to the prone position. We used radiolabeled microspheres to measure the regional distribution of perfusion (Qr) to the dorsal, mid, and ventral lungs of eight dogs in vivo in the supine and prone positions, before and after inducing acute lung injury with OA, and correlated the Qr observed after injury with the degree of regional extravascular lung water (EVLWr). Before OA, Qr increased along the gravitational gradient when the animals were supine but was more uniformly distributed when they were prone. After OA, Qr again followed a gravitational gradient when the animals were supine but was preferentially distributed to the nondependent regions when they were prone. EVLWr was similar in all regions, regardless of whether OA was injected when the animals were supine or prone. The gravitational Qr gradient is markedly reduced in the prone position, both before and after lung injury. The prone position-induced improvement in oxygenation is not the result of redistribution of Qr away from areas in which edema preferentially develops.

Animals↗
PubMed1988

Evaluation of nonradioactive, colored microspheres for measurement of regional myocardial blood flow in dogs.

Measurement of regional myocardial blood flow (RMBF) is crucial in experimental studies of myocardial ischemia and reperfusion in dogs. The standard measurement technique uses radioactive microspheres; however, not all institutions are able to dispose of radioactive waste and therefore cannot make use of this method. We tested a new, nonradioactive microsphere, labeled with colors instead of nuclides. Simultaneous blood flow measurements with two nuclide-labeled and two colored microspheres were performed after coronary occlusion in dogs. Both techniques show a within-method correlation of r greater than 0.98. Duplicate variability for paired RMBF values in 80 samples was 8.7 +/- 0.1% when computed with radioactive microspheres and 13.2 +/- 1.8% when computed with colored microspheres. There was a good correlation in the measurement of RMBF between the radioactive- and colored-microsphere methods (r = 0.98). The best-fitting linear regression line was expressed by the formula: Colored-microsphere RMBF = 1.11 (radioactive-microsphere RMBF)-0.02. When measured by colored microspheres, RMBF was approximately 8% higher than when computed with radioactive microspheres for blood flow values of 0-2 ml/min/g. When blood flow was increased pharmacologically to levels of 2-7.5 ml/min/g, colored microspheres yielded blood flow values 39% higher than the values computed by radioactive microspheres. We conclude that the nonradioactive, colored-microsphere method correlates with the radioactive technique, but at high flows, it yields values greater than those obtained with radioactive microspheres.

Animals↗
PubMed2004

Influence of the chemical form on the plasma clearance of ruthenium in humans.

The radioisotopes of ruthenium (103Ru and 106Ru) are abundant fission products and represent a radiological risk for the population in case of nuclear accidents. Few biokinetic studies have been performed on humans up to now and consequently the current model recommended by ICRP for ruthenium is derived mainly by extrapolation from animal data. The stable isotope 101Ru and proton activation analysis have been used to study the biokinetics of Ru in blood plasma samples taken during 8 studies in three healthy volunteers. The results obtained demonstrated that complexed Ru (in the form of citrate Ru(IV) complexes) is cleared from blood plasma very rapidly (characteristic half time of 17+/-2 min), while inorganic Ru remains longer in the systemic circulation, and is transferred to other organs and/or excreted with a biological half time of 23+/-2h. Good reproducibility of the clearance curves indicated no evidence of inter- or intra-individual variability when the same Ru solution was injected in repeated experiments to different subjects.

Adult↗
PubMedDate not supplied

106Ru/106Rh plaque radiotherapy for malignant melanomas of the choroid. With follow-up results more than 5 years.

Therapeutic results are presented with follow-up examinations of at least 5 years (min. 5 years, max. 22 years) after 106Ru/106Rh plaque radiotherapy of posterior uveal melanomas. Out of 227 patients 146 (= 64.3%) could be treated successfully, 37 (= 16.3%) had to be enucleated and are alive, 44 (= 19.4%) died from metastases and 40 (17.6%) from other causes. 75.0% of all small melanomas (T1a) showed an excellent regression pattern to flat scars. Five years after treatment the survival rate was 83.7% (deaths from any causes) respectively 88.2% (deaths from metastases only) and 64.8% (deaths from any causes) respectively 79.7% (deaths from metastases only) ten years after irradiation. 106Ru/106Rh plaque radiotherapy can be recommended for small (T1a, b) and medium sized (T2) choroidal melanomas.

Brachytherapy↗
PubMed1991

Histopathology studies in human malignant melanomas of the choroid after unsuccessful treatment with 106Ru/106Rh ophthalmic applicators.

Choroidal malignant melanomas were examined after unsuccessful brachytherapy with 106Ru/106Rh ophthalmic plaques. The histologic findings were compared with those obtained in non-irradiated melanomas similar in size and location. Both groups revealed no significant clinical difference apart from the lower average age of the irradiated patients. Some of the histologic features (scar formation, changes in the distribution of cell types, rate of mitosis) represented reactions to irradiation. No single histologic feature was strongly correlated to the irradiated group. The phenomenon of radioinsensitivity observed in some malignant melanomas cannot be fully elucidated using conventional histologic methods.

Brachytherapy↗
PubMed1994

Radiation effects on the optic nerve observed after brachytherapy of choroidal melanomas with 106Ru/106Rh plaques.

From 1966 to 1990 a total of 93 juxtapapillary choroidal melanomas were treated using 106Ru/106Rh plaques with a notch for the optic nerve. The choroidal melanoma was controlled after brachytherapy in 79 cases (85%). Fourteen eyes (15%) had to be enucleated because of tumor regrowth. Eye and optic nerve phantoms were fabricated, loaded with small-volume thermoluminescent dosimeters, treated with active plaques, and the radiation dose determined at the optic disc and along the optic nerve. The median dose within the anterior optic nerve was 51.2 Gy (range 10.3-60.5 Gy). The probability of developing complete radiation optic neuropathy (RON) was 23% and 53% at 5 and 10 years, respectively. The probability of developing partial RON was 66% at 5 years and 82% at 10 years. The probability of retaining visual acuity better than 0.5 was 38% at 5 years and 26% at 10 years. No dose-response relationship could be established from the ophthalmological, morphological and functional findings. Eyes following plaque irradiation with 50 Gy or more in the center of the optic nerve experienced significant radiation optic neuropathy, other eyes did not.

Adolescent↗
PubMed1992

Quantitative color Doppler imaging in untreated and irradiated choroidal melanoma.

Histological data indicate the importance of tumor vascularization as a determinant of the biological behavior and the response to radiotherapy in choroidal melanoma. Duplex ultrasound and color Doppler imaging, the combination of B-mode ultrasound and pulse-waved Doppler analysis, were used to measure quantitatively neovascular blood flow in 31 patients with choroidal melanoma. Follow-up studies (20 patients) were performed to investigate the change of tumor blood flow in choroidal melanomas after radiotherapy. Blood flow was detected in 30 out of 31 melanomas (size 3.1-17.8 mm) within the tumor and at the tumor base with a mean peak systolic frequency of 1.0 kHz (range 0.3-2.7 kHz), a mean end diastolic frequency of 0.3 kHz (range 0.1-1.0 kHz), and a mean frequency of 0.7 kHz (range 0.2-1.3 kHz). Two and six months after 106Ru/106Rh beta-ray application, 19 patients showed a significant decrease in peak systolic frequency. This occurred with and in advance of the decrease in the tumor size. In one patient, a rising maximum systolic frequency after radiotherapy marked a recurrent tumor growth. Results indicate that the quantitative measurement of tumor blood flow by duplex ultrasound and color Doppler imaging may be a new diagnostic modality for monitoring the effectiveness of radiotherapy in choroidal melanoma.

Adult↗
PubMed1992

Quantitative duplex and color Doppler ultrasound in the follow-up of beta-irradiated (106Ru/106Rh) choroidal melanomas. A prospective study.

The tumor response to radiotherapy depends highly on the local oxygen concentration, which is governed by the tumor's microcirculatory network. The aim of this prospective study was to quantitate the neovascular blood flow in human choroidal melanomas prior to 106Ru/106Rh irradiation and during a 1-year follow-up period. Pulsatile blood flow was elicited by means of duplex and color Doppler ultrasound in 54 of a total of 55 untreated melanomas with a mean peak systolic frequency of 1.0 kHz (range 0.3-2.7 kHz). The neovascular blood flow decreased significantly 4 and 6 months after beta-irradiation. No intrinsic tumor vascularity was detected 8 and 12 months after treatment. In 3 patients, a rising peak systolic frequency occurred following radiotherapy in advance of recurrent tumor growth. Results indicate that the noninvasive quantitation of neovascular blood flow in irradiated choroidal melanomas by pulsed Doppler ultrasound offers a new diagnostic modality for assessing tumor recurrence.

Adult↗