Radio-induced Changes Research Articles

Upfront and Repeated Gamma-Knife Radiosurgery for Small (≤5 mL) Unruptured Brain Arteriovenous Malformation: A Cohort of 249 Consecutive Patients

According to A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA), conservative treatment seems to be superior to any intervention for unruptured brain arteriovenous malformations (AVMs). This study aims to evaluate safety and efficacy of upfront and repeated Gamma-Knife Radiosurgery (GKRS) in patients harboring small AVMs fulfilling the inclusion criteria of ARUBA. A retrospective study was conducted to evaluate outcomes of unruptured naive brain AVM with a volume ⩽ 5 mL eligible to ARUBA treated by GKRS with at least 3 years of follow-up. From 1992 to 2014, 249 patients fulfilled the inclusion criteria of this study. The median age was 36 years (range: 18-78 years). The median treated volume of the nidus was 1.3 mL (range: 0.4-5 mL) and 63% of the AVM were in eloquent areas. Radiosurgery-based AVM score was 1-1.8 (76%), the Spetzler-Martin grade was II-III (73%), and the Virginia Radiosurgery AVM scale was ≤1 point (75%). The overall AVM obliteration rate was 77.1% after up to 3 GKRS sessions. The median dose at the margin was 24 Gy (15-25 Gy) and the median follow-up was 45 months (range: 36-205 months). Eight patients (3.2%) experienced hemorrhage after GKRS, corresponding to a post-GKRS hemorrhage annual rate of 1.03%. Permanent symptomatic radio-induced changes rate was 2% (4 increased seizures, 1 neurologic deficit). The very low toxicity rate and the high occlusion rate suggest in favor of upfront and repeated GKRS for unruptured small AVMs (⩽5 mL).

Evaluation of gamma irradition process for induction of color change in gel composite

The gamma irradiation process of industrial and medical materials is based on radio-induced changes for specific purposes, such as sterilization or induction of color formation. In gem irradiation, for example, color changes according to the deposited dose. In this work we present results obtained by the irradiation of clinical gel/copper sulfate composite to observe the color change for further evaluation of its use as an indicator of volume dose distribution. The irradiations were performed with a Co-60 source at doses between 10-100 kGy in XXXXX of XXXXX. Samples were prepared in three different compositions in relation to the amount of copper sulfate added (100, 400 and 500 mg of CuSO4 in 100 ml of clinical gel). Samples were photographed before and after exposure and color change evaluated with the ImageJ© program. Was observed color change in the samples as the radiation dose increase. Greater color variations were observed for the sample of clinical gel/CuSO4 (100 mg). The samples were re-evaluated one month after irradiation and it was noticed that the color undergoes alteration over time, but without returning to the original color. These results are useful in characterizing future use of the composite as a volumetric indicator of dose distribution in gamma irradiation processes.

Analytical methods for assessing changes induced by gamma exposure in an animal model.

Ionizing radiation can cause radio-induced changes in the cellular metabolome due to the breakdown of DNA bonds. Our goal was to find the early tissue response to radiation exposure supported by distinct analytical methods. Histological analyses were performed on the organs extracted from rats to search for microscopic changes. The histological slides stained with hematoxyline-eosin (HE) were analyzed in magnification (40x). Subsequently, the tissues were subjected to mass spectrometry that allowed molecular analysis and DESI-MSI that generated the molecular image of lipids, assessing changes in intensities, especially in the brain. The histological analysis found nonspecific inflammatory changes; no areas of fibrosis, necrosis, or apoptosis were identified, suggesting non-morphological tissue alterations. However, the DESI-MSI images of brain lipids allowed the observation of many radio-induced changes in the lipid's intensities. No early radio induced histological or mass weight changes in the radiation exposed rats could be observed at 5 Gy. However, early changes in the molecular level were observed in the DESI-MSI images of the brain lipids. The DESI-MSI method proved to be efficient and relevant, allowing a regional molecular analysis of the tissues, expanding a new field of study that is still in its infancy: radiometabolomics.

In silico model of the early effects of radiation therapy on the microcirculation and the surrounding tissues

BackgroundRadiation-induced organ dysfunction are frequently described by Normal Tissue Complication Probability models. The approximations of this radiobiological approach do not allow to consider the important role played by the microvasculature not only in the dose–response of the blood vessels but also of the organs where it is located. To this purpose, we presented a computational model that describes the fluid dynamics of microcirculation when the parameters of the network and the surrounding tissues are affected by radio-induced changes. Materials and methodsThe effects of the ionizing radiation on the capillary bed are mediated by the inflammatory response. We derived from a literature search the possible morphological and functional variations of the network due to the process of the acute inflammation. Specifically, we considered vasodilation, increased membrane permeability with consequent fluid extravasation and increased wall elasticity. These perturbations to the system were included in a computational model, already able to describe the physics of the microcirculation and its exchanges with the surrounding tissues. ResultsTwo computational descriptions were considered. In the first one, we changed a set of 4 parameters associated with the increased fluid exchange from the health scenario at the baseline to a seriously compromised scenario with the edema formation. The second study investigated the effect of a perturbation to the vessel wall elasticity. ConclusionsThese simulations represent a first step towards the challenging objective of understanding and describing in a mechanistic way the effects of radiation on the vascular microenvironment.

Dynamic modulations of the MDA-MB-231 secretions at low dose radiation

The goal was to investigate the time dynamic nature of the secreted protein profiles at 15–240 kDa, expressed by MDA-MB-231 breast cancer cells, exposed to 240 ± 12 mGy dose. After 2 h, a variety of proteins in the supernatant reduced their concentration up to 10–12 h, as an early event. After 24 h, up- and down-regulations of the secretions of several factors were postulated, indicating significant radio-induced changes. At a late event, in 48–96 h, the findings pointed out to distinct radio-induced modulations characterizing early and late profiles. Such findings suggest dynamic secretome behavior, possibly related to distinct MDA-MB-231 phenotypes.

Physiological and radio-induced modulations of low-weight globulins in distinct vascular compartments

The main goal was to investigate the profiles of molecular weight globulins lower than albumin in the electrophoresis system in function of the exposition time to gamma radiation. At 72 h post-irradiation, the globulin electrophoretic profiles bellow albumin showed significant radio-induced changes. In addition, the vascular system, specifically the inferior vena cava, kidney, spleen, jugular, hepatic, and pulmonary veins presented a physiological compartmental distribution of globulins. The findings pointed out the radio-induced alterations of the serum globulin concentrations as a late event, possibly related to a radio modulation of the genes’ expression.

Bond strength of dental adhesive systems irradiated with ionizing radiation.

The aim of the present paper was to determine the effect of different types of ionizing radiation on the bond strength of three different dentin adhesive systems. One hundred twenty specimens of 60 human teeth (protocol number: 032/2007) sectioned mesiodistally were divided into 3 groups according to the adhesives systems used: SB (Adper Single Bond Plus), CB (Clearfil SE Bond) and AP (Adper Prompt Self-Etch). The adhesives were applied on dentin and photo-activated using LED (Lec 1000, MMoptics, 1000 mW/cm2). Customized elastomer molds (0.5 mm thickness) with three orifices of 1.2 mm diameter were placed onto the bonding areas and filled with composite resin (Filtek Z-250), which was photo-activated for 20 s. Each group was subdivided into 4 subgroups for application of the different types of ionizing radiation: ultraviolet radiation (UV), diagnostic x-ray radiation (DX), therapeutic x-ray radiation (TX) and without irradiation (control group, CG). Microshear tests were carried out (Instron, model 4411), and afterwards the modes of failure were evaluated by optical and scanning electron microscope and classified using 5 scores: adhesive failure, mixed failures with 3 significance levels, and cohesive failure. The results of the shear bond strength test were submitted to ANOVA with Tukey's test and Dunnett's test, and the data from the failure pattern evaluation were analyzed with the Mann Whitney test (p = 0.05). No change in bond strength of CB and AP was observed after application of the different radiation types, only SB showed increase in bond strength after UV (p = 0.0267) irradiation. The UV also changed the failure patterns of SB (p = 0.0001). The radio-induced changes did not cause degradation of the restorations, which means that they can be exposed to these types of ionizing radiation without weakening the bond strength.

Nasopharyngeal Carcinomas

Current treatment of nasopharyngeal carcinomas includes radiation therapy (RT) alone or combined with chemotherapy and neck dissection. Consequently all patients with nasopharyngeal carcinomas are treated with RT. To evaluate the CT and MRI appearance of nasopharyngeal carcinomas treated with RT and the ability of CT and MRI to differentiate persistent or residual tumour from radio-induced changes of head and neck tissues. Post-treatment CT and MRI examinations of 28 patients with primary nasopharyngeal cancers treated with RT (6000–7500 cGy) were retrospectively evaluated. We divided the patients in three groups on the basis of the differences in the CT and MRI appearance of the primary tumours treated with RT 1. Responders (9 patients): complete resolution of tumour or reduction in tumour size = or > 75%; 2. Non-Responders (8 patients): persistent tumour or residual mass with reduction in tumour size = or < 50%; 3. Partial Responders: (11 patients) persistent residual mass with reduction in tumour size from 50% to 75% or persistent asymmetry of the mucosal surface. There are some points to analyse in the interpretation of CT and MRI imaging of post-treated nasopharynx: Transient changes of irradiated soft tissues are more prominent during the first three months after RT (increased en-hancement of the pharyngeal mucosa and thickening of the pharyngeal walls). Persis-tent changes are subgrouped in 1. Soft tissue changes: a. Glandular (major salivary glands scialoadenitis and fatty degeneration); b. Deep (reticulation and fibrous degeneration of pre- and post-styloid parapharyngeal fat; c. Visceral (retraction of the pharyngeal wall and distorsion of lateral recess); d. Nervous (radio-induced damage of the CNS such myelopathy and radionecrosis. 2. Bone tissue changes: a. Fatty degeneration of bone marrow of the skull base; b. Sclerosis of the cortical bone of the basisphenoid. 3. Sinonasal changes: Reactive chronic sinusitis. Perineural-perivascular spread and skull base erosion is indicative of a poor outcome. The patients of the third group may also be followed with seriated CT because they have a significant percentage of recurrence.

Laryngeal Carcinomas: CT Appearance after Radiation Therapy

Current treatment of head and and neck carcinomas includes also Radiation Therapy (RT). Control with RT allows the patient to retain a functioning organ in cases in which surgical cure may require an extensive demolition. Consequently a growing number of selected patients are treated with RT. To evaluate the CT appearance of laryngeal carcinomas treated with RT and the ability of Computed Tomography (CT) to differentiate persistent or residual tumor from radio-induced changes of soft tissues.Pre- and post-treatment CT examinations (n = 325) of 132 patients with primary laryngeal cancers treated with RT (4500–7500 cGy) were retrospectively evaluated.We subdivide the patients in three groups on the basis of the differences in the CT appearance of the primary tumors treated with RT 1) Responders (42): complete resolution of tumor or reduction in tumor size = or > 75%; 2) Non-Responders (55): persistent tumor or residual mass with reduction in tumor size — or < 50%. 3) Partial Responders (35): persistent residual mass with reduction in tumor size from 50% to 75% or persistent asimmetry of the mucosal surface.There are some points to analyse in the interpretation of CT imaging of post-treated head and neck region: 1) Transient changes of irradiated soft tissues are more prominent during the first three month after RT. 2) Persistent changes are subgrouped in: a) Superficial (skin and platysmal thickening, reticulation of subcutaneous fat); b) Glandular (major salivary glands adenitis and fatty degeneration); c) Deep (reticulation and fibrous degeneration of anterior and posterior cervical and perivascular fat); d) Visceral (increased en-hancement of the pharyngeal mucosa and thickening of posterior pharyngeal wall, epiglottis, aryepiglottic folds, false vocal cords, anterior and posterior commissures, subglottic larynx, increased attenuation of paralaryngeal fat). 3) Progressive arytenoid cartilage sclerosis is indicative of a poor outcome. 4) The patients of the third group may be followed also with seriated CT, because they have a significant percentage of recurrence.

Radiation Effects in Graphite

A review of radiation effects on graphite is presented. Included are discussions of the general relations of these effects with original structural properties, and details of radioinduced changes. Other discussions are devoted to stored energy, annealing, and future problems in the use of nuclear graphite. Data and illustrations concerning structure and radioinduced changes are included. (J.R.D.)

On the Role of DNA in the Radiation Damage of the Cell

Results are reported from a series of investigations of the role of desoxyribonucleic acid (DNA) in radiation injury in cells. It was concluded that radioinduced changes in DNA metabolism and state involve complex disturbances in metabolism in both the nucleus and cytoplasm of the irradiated cell.

Recovery effect of highly polymerized homologous liver deoxyribonucleic acid injected into lethally irradiated rats: histological examination of the spleen and bone marrow.

Histological examination was made on the radioinduced changes in the spleen and bone marrow of rats exposed to a LD/sub 100/30/ of x rays, treated with homologous native liver DNA, and killed on the 4th or 9th day after irradiation. It is concluded that the spleen and bone marrow of the lethally irradiated rats treated with DNA are less damaged than the untreated controls. The reticular cells are not so much altered and there are more lymphopoietic elements in the spleen and myelopoietic and erythropoietic elements in the bone marrow. (D.L.C.)

An Effect of Ionizing Radiations on the Hydrogen Bonds in Wool

Irradiation with 15-Mev electrons changes certain physical properties of wool fibers profoundly, even after doses of as little as 5 x 10/sup 6/ rads. Lithium bromide solutions disorientate the crystalline areas of wool which consist of polypeptide chains held together by hydrogen bonds. Irradiation increases the disorientation prcduced by lithium bromide and renders it irreversible. In sodium bisuifite solutions, wool contracts by breaking the disulfide bonds in the matrix in which the micelles are held. This effect is increased by irradiation, but the influence of radiation is less far-reaching than in the lithium bromide test. These radioinduced changes can be stimulated, in part at least, by chemical treatments that break disulfide or peptide bonds. But the number of bonds that have to be broken is many times as great as the number that are destroyed by a dose of radiation that gives a comparable effect. It is concluded that the relevant changes produced by radiation reside in the hydrogen bonding of the micelles and that radiochemical chanas involving covalent bonds are not principally responsible. The changes studied were essentially independent of moisture content of the wool fibers and of the presence of oxygen. (auth)

Effects of cell-free spleen extract treatment on the hematopoietic tissues of irradiated guineapigs. II. Histochemical observations with alkaline phosphatase staining.

Guinea pigs were given whole-body Co60 irradiation (650 r) and injected daily thereafter with cell-free extracts of homologous and heterologous spleen. Spleen of irradiated control guinea pigs showed a progressive reduction of alkaline phosphatase staining commencing after the 3rd postirradiation day and reaching a maximum on or about the 9th day. Treatment of the animals with spleen extracts modified the radioinduced changes in alkaline phosphatase staining, so that an almost normal appearance was noted over the entire 14-day observation period. Most of the alkaiine phosphatase-staining spleen elements were mature neutrophils. It was concluded that spleen extract treatment affects apparently various celluiar elements of spleen in a different way. The results support the hypothesis that protection of phosphorylization processes against effects of irradiation represent one of the mechanisms by which the radiation protective effect of spleen extracts is effected.

Effects of cell-free spleen extract treatment on hematopoietic tissues of irradiated guineapigs. I. Histological observations.

Radioinduced histological changes were studied in the spleen and bone marrow of guinea pigs that were exposed to the LD/sub 75/20/ (650 r) of Co/sup 60/ gamma radiation and had received homologous or heterologous cell-free spleen extracts after irradiation. In both organs, postirradiation treatment with the spleen extracts accelerated the recovery from irradiation. Furthermore, it appears that the chain of events was the same with homologous (guinea pig spieen) or heterologous (mouse spleen) extract. It was concluded that the previousiy established reduction of radiation mortality by homologous as well as heterologous spleen extracts is due to a common mechanism. The cell-free spleen extracts also enhanced the natural recovery process in the bloodforming organs. The accelerated recovery process was due to a stimulatory effect of the spleen extract on the stem cells. Spleen extract treatment affected the radioinduced changes in spleen profoundly during the first week after irradiation, while the bone marrow changes were most significantly influenced at the beginning of the second postirradiation week. It is suggested that bone marrow recovery, at least to a certain extent, is subordinate to that of the spleen. With cell-free spieen extracts, the initial phase of radioinduced bone marrow effects remained entirely unchanged. Amore » complete restitution was observed within 14 days in the spleen cell- treated animals, while in the untreated irradiated animals complete recovery was not attained before 21 days. The regeneration of both erythroand myelopoietic tissue was acceierated. (P.C.H.)« less

Radiobiological Mechanisms of Genetic Effects. A Review of Some Current Lines of Research

Radioinduced changes in nuclear material and particularly those leading to genetic consequences are reviewed. The induction by radiation of gene mutations and other changes in the gene material, chiefly chromosome breaks, are discussed in detail. Topics discussed include the chemical nature of the genetic material, the dependence of radiation-induced mutations on dose, the relation of target and gene size, the influence of ion density, the substructure of the gene, the spocificity of mutagenic agents, back mutation, the sensitive stage for the induction of mutation, the radiomimetic effects of oxygen, and modifying factors which are capable of exerting influences on widely different radiobiological effects such as gene mutation, chromosome rearrangement, growth inhibition, and death of cell or organism. 153 references. (C.H.)