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[Activity of phosphodiesterases in granulation tissue treated with electron irradiation -- experimental study on rats].

The present study evaluated the effect of low doses of electron radiation on the activity of phosphodiesterases in granulation tissue. In order to induce growth of granulation tissue, a PVC sponge disk was introduced under the dorsal skin of 84 Wistar rats. The rats were divided in two groups, control and irradiated. The enzymatic activity was evaluated according to the evolution of the granulation tissue after 5, 7, 10, 14, 17, 20 and 24 days. Irradiation was carried out 3 days after the implantation of the sponge, by means of a linear accelerator, with energy of 6 MeV, and dose of 1.0 Gy. The results of this study showed that 5'-nucleotidase and ATPase had their activity directly affected by irradiation only in the beginning of the tissue repairing process. Alkaline phosphatase did not suffer any direct effect of irradiation. It is possible that the main factor has been the damage of the cellular components responsible for the growth of granulation tissue, which determine the production of enzymes according to the necessity.

Animals↗
PubMed2006

Beta radiation.

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Beta Particles↗
PubMed2003

Mitochondrial DNA heteroplasmy in laboratory mice experimentally enclosed in the radioactive Chernobyl environment.

Mitochondrial DNA heteroplasmy using the protein-coding cytochrome b (Mtcyb) gene was assessed in laboratory mice (C57BL/6 and BALB/c) exposed to the Chernobyl environment. Subacute to subchronic (30-40 days) exposure resulted in a cumulative radiation dose of 1.2-1.6 Gy ( approximately 0.04 Gy/day). Mice were sampled prior to introduction into the enclosures and again after removal from the enclosures. Nucleotide variation (site heteroplasmy) in 306 pre-exposure Mtcyb gene copies (122400 base pairs) was compared to variation in 354 postexposure gene copies (141600 base pairs). Five mutant copies, each characterized by a single nucleotide substitution, were observed (four in the pre-exposure samples, one in a postexposure sample). The frequencies of mutant gene copies and nucleotide substitutions in pre-exposure and postexposure samples were not significantly different. This suggests that this type of exposure (i.e. low dose rate) does not pose a significant mutation risk to the Mtcyb gene in digit tissue. Furthermore, no significant radiation risk to analogous human tissues may exist when occupational exposures involve low dose rates such as these. Finally, linear, cumulative models of genetic risk currently used to estimate radiation-induced effects are likely to be inappropriate for low-dose-rate exposures and need to be re-evaluated critically.

Animals↗
PubMed2000

Coronary aneurysm five months after intracoronary beta-irradiation.

Intracoronary beta-irradiation is believed to be useful in preventing restenosis after coronary angioplasty or as adjunct therapy of an in-stent restenosis. Intracoronary aneurysms after gamma-irradiation were reported by Condado et al. in 1995, especially after doses higher than 25 Gy and without a centering device. In repeated small trials using intracoronary beta-irradiation no aneurysms were reported at 6 months follow-up. We report the development of a coronary aneurysm at 5 months after intracoronary beta-irradiation and stenting. Intracoronary brachytherapy is a new promising technique although one should be cautious about its possible unknown long-term complications.

Aged↗
PubMed2004

Intravascular brachytherapy: indications and management of adverse events.

Intravascular brachytherapy has become the standard of care for the treatment of coronary in-stent restenosis after repeat angioplasty. More than 5000 patients have been treated as part of various clinical trials. Based on the results of the GAMMA I trial, the START ((90)Sr Treatment of Angiographic Restenosis Trial), and the INHIBIT (INtimal Hyperplasia Inhibition with Beta In-stent restenosis Trial), the Checkmate system using (192)Ir, the Betacath system using (90)Sr/Y, and the Galileo system using (32)P, have been approved for the treatment of in-stent restenosis. With a better understanding and application of radiation oncology concepts to vascular brachytherapy, problems such as edge failure are being overcome. The complication of late thrombosis has also become less significant with the elimination of restenting at the brachytherapy procedure, and the prolonged use of antiplatelet therapy. There are other competing modalities in the early phases of clinical trials. The durability of results, lack of any significant long-term complications and the confirmation of the efficacy in other sites will further consolidate the role of radiation in treating in-stent restenosis.

Beta Particles↗
PubMed1987

The effect of beta irradiation on monkey Tenon's capsule fibroblasts in tissue culture.

Fibroblast proliferation with subsequent bleb scarring is a major cause of filtering surgery failure. To investigate possible antiproliferative effects of beta radiation, owl monkey Tenon's capsule fibroblasts in tissue culture were irradiated to doses of 30, 100, 300, 1,000, and 3,000 rads with a linear accelerator and to doses of 95,285, and 950 rads with a Strontium-90 applicator. The irradiated cell proliferation expressed as the percentage of the non-irradiated control growth on the third and seventh days, respectively, after beta irradiation was: 97% and 96% after 30 rads; 72% and 90% after 100 rads; 48% and 44% after 300 rads; 39% and 14% after 1,000 rads; and 39% and 14% after 3,000 rads. Similar effects on cell proliferation were observed with the Strontium-90 applicator. The inhibitory effect of beta irradiation on fibroblast proliferation in tissue culture suggests that beta irradiation after filtering surgery may reduce postoperative bleb scarring.

Animals↗