Influence Of X-irradiation Research Articles

Ultrastructural investigation of acidocalcisomes and ATPase activity in yeast Candida guilliermondii NP-4 as 'complementary' stress-targets.

As a result of electron microscopic studies of morphogenesis in yeast Candida guilliermondii NP-4, the formation of new structures of volutin acidocalcisomes has been established within the cell cytoplasm. Under influence of X-irradiation, the changes in morphometric and electron-dense properties of yeast cells were identified: in yeast cytoplasm, the electron-dense volutin granules were increased up to 400nm in size. After 24-h post-irradiation incubation of yeasts, the large volutin pellets are fragmented into smaller number particles in size up to 25-150nm. The ATPase activity in yeast mitochondria was changed under X-irradiation. In latent phase of growth, ATPase activity was decreased 1·35-fold in comparison with non-irradiated yeasts. In logarithmic phase of growth, ATPase activity was three times higher than in latent phase, and in stationary phase of growth it has a value similar to the latent phase. Probably, the cells receive the necessary energy from alternative energy sources, such as volutin. Electron microscopy of volutin granule changes might serve as convenient method for evaluation of damages and repair processes in cells under influence of different environmental stress-factors.

The evaluation of protective effect of lycopene against genotoxic influence of X-irradiation in human blood lymphocytes

Many studies suggest that exogenous antioxidants may protect cells against DNA damage caused with ionizing radiation. One of the most powerful antioxidants is lycopene (LYC), a carotenoid derived from tomatoes. The aim of this study was to investigate, using the comet assay, whether LYC can act as protectors/modifiers and prevent DNA damage induced in human blood lymphocytes, as well as to mitigate the effects of radiation exposure. In this project, LYC, dissolved in DMSO at a concentration of 10, 20 or 40 μM/ml of cell suspension, was added to the isolated lymphocytes from human blood at appropriate intervals before or after the X-irradiation at doses of 0.5, 1 and 2 Gy. Cell viability in all groups was maintained at above 70%. The results showed the decrease of DNA damage in cells treated with various concentrations of LYC directly and 1 h before exposure to X-rays compared to the control group exposed to irradiation alone. Contrary results were observed in cells exposed to LYC immediately after exposure to ionizing radiation. The studies confirmed the protective effect of LYC against DNA damage induced by ionizing radiation, but after irradiation the carotenoid did not stimulate of DNA repair and cannot act as modifier. However, supplementation with LYC, especially at lower doses, may be useful in protection from radiation-induced oxidative damage.

Irradiation and Humidity Effects on the Leakage Current in SiOx ( CH 3 ) y-Based Intermetal Dielectric Films

The influence of X-irradiation on leakage currents in -based dielectric films has been studied. In both unirradiated and irradiated samples, the natural logarithm of the leakage current density (J) varies as the (applied electric field)1/2 at high electric fields consistent with the bulk-limited Poole-Frenkel mechanism although the measured slope of the curve is smaller than expected by a factor of 1.5. Radiation induces a shift of the vs. to lower voltages in samples exposed in the presence of zero and 1.5 MV cm−1 bias indicating significant charge trapping. We find clear evidence for uptake of moisture in the films leading to enhanced conductivity. © 2003 The Electrochemical Society. All rights reserved.

Effects of the microindentation, X-irradiation and annealing on the F-centre-like defects production in MgO

Local cathodoluminescence analysis have been applied to defects recognition in indented MgO crystals. Influence of X-irradiation and annealing on the kind and concentration of F-centre-like defects was established.

Latent X-ray Damage in the Rat Sciatic Nerve Results in Delay in Functional Recovery After a Heat Treatment

The influence of X-irradiation on the sensitivity of the rat sciatic nerve to local hyperthermia was investigated. A 10 or 20 mm long segment of the nerve was irradiated intraoperatively using 50 kV X-rays. Hyperthermia (30 min at 45 degrees C), was applied to the irradiated part (over a length of 5 mm) of the nerve using a brass thermode. Functional damage to the nerve was assessed using the toe-spreading test, which mainly assesses the motor function of the sciatic nerve. Radiation alone (doses up to 70 Gy) did not lead to detectable damage for at least 90 weeks. Hyperthermia alone (30 min at 45 degrees C) resulted in complete loss of motor function. This function loss was transient and complete recovery took place in about 4 weeks. Recovery time was scored as the number of days between hyperthermia and the day on which 50% of the motor function had returned. Irradiation (35 Gy) of a nerve segment, which included the heated part, resulted in a delayed recovery from the heat treatment compared to controls (heat only). The time interval and sequence between irradiation and hyperthermia hardly influenced the recovery delay. The size of the irradiated nerve segment did influence the recovery delay. Irradiation of a 20 mm nerve segment led to longer recovery delays than irradiation of a 10 mm segment (a delay of 5-10 days and 1-5 days respectively). A dose-response relation for the irradiation-induced delay in recovery was observed when a large segment (20 mm) of the nerve was irradiated immediately after heat with a dose ranging from 5 to 40 Gy. The delay in heat recovery was dose-dependent below 20 Gy, but after radiation doses above 20 Gy the recovery delay remained almost constant.

The influence of x-irradiation on the electrical properties of SbSI crystals

An investigation of the electrical conductivity of irradiated SbSI single crystals shows its sensitivity to x-radiation. The influence of the x-radiation on the crystal appears to be a function of the temperature of the SbSI specimen. The absence of the shift of T0 and the reduction of emax in the SbSI crystal specimens during and after long x-irradiation suggests that x-radiation does not cause structural changes in the specimen.

Influence of X-irradiation on the different stages of the cell cycle in regenerating rat liver.

Influence of X-irradiation on the different stages of the cell cycle in regenerating rat liver.

Plasmodium cynomolgi: Influence of X-irradiation and sporozoite dilution on relapse patterns in infected rhesus monkeys

It has been possible to demonstrate a direct relationship between number of sporozoites in an inoculum and the number of subsequent relapses in experimental infections with Plasmodium cynomolgi. The reduction in Sporozoite numbers was accomplished through the use of two techniques; (1) X-irradiation and (2) volumetric dilution. The authors conclude that these observations tend to support a concept of latency as an explanation for relapse and delayed patency in malaria. It is difficult to reconcile these results with the generally accepted concept of a continuous cycle of liver schizogony in relapsing malarias.

Influence of X-irradiation on the solicon-silicon dioxide interface of MOS structures

Silicon MOS structures with an SiO2−Si3N4 insulator were exposed to X-rays. Positive oxide charges arise and the continuous density of fast states increases at the Si−SiO2 interface. In addition, a single energy state develops above the middle of the energy gap atE−Ev=600 meV. Annealing measurements in dry air and H2 lead to the conclusion that the single energy level originates from a dissociated hydrogen bond in the silicon dioxide.

Influence of X-irradiation on the different stages of the cell cycle in regenerating rat liver.

Five groups of rats are partially hepatectomized in the afternoon. The first is the non-irradiated control and the others are irradiated (450R) at different post-operative delays of 1 h (hepatocytes in G0), 12 h (middle of G1), 20 h (end of G1 -beginning of S) and 28 h (S phase).

Lymphoid cells in delayed hypersensitivity. 3. The influence of x-irradiation on passive transfer and on in vitro production of soluble mediators.

X-irradiation up to 480 R does not inhibit either adoptive transfer of delayed hypersensitivity or production in vitro of soluble mediators, such as migration-inhibitory factor (MIF). Above that dosage and as high as 3000 R, adoptive transfer is inhibited, but production of MIF is not. An increase in skin response occurred when 24-48 hr were allowed to elapse after intravenous transfer and before skin testing. Treatment of recipients with colchicine at the time of adoptive transfer inhibited the development of a skin reaction to specific antigen.

Influence of X-irradiation and seed-moisture on nucleic-acid and protein metabolism in barley

Seeds with varying moisture content (3–14 per cent) were X-irradiated with doses of 0, 10, 12·5 and 15 kR. Radiation-induced changes in the length of root and shoot, and their fresh and dry weights indicate that the seeds show maximum radioresistance at intermediate moisture levels and that the shoot is more sensitive to X-rays than the root. There was no significant modification of DNA, RNA and acid soluble (AS) content while protein content was adversely affected by radiation irrespective of seed moisture. However, no change in total macromolecular content could be detected in the plant as a whole.

Influence of x-irradiation on enzyme induction: phosphoenolpyruvate carboxykinase in the liver of irradiated mice.

Normal or adrenalectomized mice were wohle-body X-irradiated with 690 —4000 R either after hydrocortisone administration or during a 24 h fasting period, and PEP carboxykinase activity measured after the appropriate time. The results show that the induction of PEP carboxykinase is not affected by the irradiation, neither in hormone treated nor in fasting normal or adrenalectomized mice as compared to the controls. These findings support the assumption that the protein synthesizing system in the living cell is very resistant to ionizing radiation.

The influence of x-irradiation on survival and interferon levels in viral infected mice.

The influence of x-irradiation on survival and interferon levels in viral infected mice.

Inhibition by Radiation of the Development of Drug-Detoxification Enzymes

A study was conducted to ascertain the influence of X-irradiation on the synthesis of detoxification enzymes. In the young male rat some of the detoxification enzymes located in the microsomal fraction of the liver exhibit two distinct phases of development. One phase occurs from the time of birth to about 21 days of age, and the second phase occurs from 21 to about 45 days of age. When weanling male rats were exposed to 100 R, 200 R, or 400 R of X-irradiation, a dose-dependent, reversible inhibition of the second phase of enzyme development occurred. This effect rendered the animals more susceptible to drugs that are detoxified by microsomal enzymes. Partial-body shielding experiments revealed that shielding the liver and testes areas did not prevent the inhibition of enzyme development. The inhibition occurred when only the head was irradiated, indicating that it is due to an abscopal effect. The nature of this indirect effect of radiation was not elucidated, but it seems possible that it involves an ab...

Pharmacological studies on chemical protectors against radiation. II. Influence of x-irradiation on body weight of mouse

When experimental animals are irradiation with radiation rays, various disorders result but the marked change in the initial stage is the loss in body weight. In order to see if this loss in weight could be used as an index for biological assay of chemical radiation protectors, sensitivity of mouse weight to irradiation was examined. The body weight of male ddY mice shows specific loss on X-ray irradiation, and the rate of body weight change two weeks after the irradiation is linear to the dose of irradiation. This rate of body weight change is much more sensitive than changes in survival rate, and effect of irradiation can be observed with a low dose and in a short period.

Gamma globulin and antibody formation in vitro. VII. Effect of x-irradiation on the secondary antibody response in vitro.

The present studies have shown that the influence of X-irradiation on the secondary antibody response in vitro is remarkably similar to its effect on the primary response in vivo. When sensitized tissue was first irradiated and then reexposed to antigen, the duration of the interval between irradiation and antigen addition determined the degree of inhibition of the secondary response obtained. A delay of 12 hr resulted in stronger inhibition than a delay of 6 hr, and an interval of 24 hr before reexposure to antigen caused complete suppression of antibody production to diphtheria toxoid and almost complete suppression when sheep RBC were used as the antigen. Induction of the secondary response in rabbit lymph node tissue in vitro followed by exposure to X-irradiation, revealed that immediate exposure to irradiation after antigen produced stronger inhibition of the subsequent response than irradiation on days 2-3. Irradiation on day 6 had no detectable effect. The effectiveness of the early radiation is probably due to prevention of the proliferation of the antibody-forming cells. BUDR was found to be effective at similar time periods as X-irradiation, whereas colchicine could still stop antibody formation when added late during the secondary response in vitro. It was noted that lymph nodes from some BSA-sensitized rabbits as late as 18 months after sensitization gave a response indistinguishable from a typical secondary response, even when not reexposed to antigen.

Influence of X-Irradiation on Experimental Allergic Encephalomyelitis in Rats

Influence of X-Irradiation on Experimental Allergic Encephalomyelitis in Rats

INFLUENCE OF X-IRRADIATION OF THE DOG KIDNEY ON ERYTHROPOIETIN PRODUCTION.

INFLUENCE OF X-IRRADIATION OF THE DOG KIDNEY ON ERYTHROPOIETIN PRODUCTION.

Formation of 5-hydroxytryptamine in an aqueous solution of 5-hydroxytryptophan treated with x-rays.

IT has been found that 5-HT (5-hydroxytryptamine) is formed by the action of ultra-violet irradiation on 5-HTP (5-hydroxytryptophan) aqueous solution, as a result of a decarboxylation process1. It is of interest to investigate whether the same process takes place under the influence of X-irradiation.