Sparing and enhancing dose protraction effects for radiation damage to the aorta of wild-type mice.

Purpose: Our previous work indicated the greater magnitude of damage to the thoracic aorta at 6 months after starting 5 Gy irradiation in descending order of exposure to X-rays in 25 fractions > acute X-rays > acute γ-rays > X-rays in 100 fractions ≫ chronic γ-rays, in which the limitations of the study included a lack of data for fractionated γ-ray exposure. To better understand effects of dose protraction and radiation quality, the present study examined changes after exposure to γ-rays in 25 fractions, and compared its biological effectiveness with five other irradiation regimens.

Materials And Methods: Male C57BL/6J mice received 5 Gy of Cs γ-rays delivered in 25 fractions spread over six weeks.

Temporal Changes in Sparing and Enhancing Dose Protraction Effects of Ionizing Irradiation for Aortic Damage in Wild-Type Mice.

In medical and occupational settings, ionizing irradiation of the circulatory system occurs at various dose rates. We previously found sparing and enhancing dose protraction effects for aortic changes in wild-type mice at 6 months after starting irradiation with 5 Gy of photons. Here, we further analyzed changes at 12 months after stating irradiation.

Vascular Damage in the Aorta of Wild-Type Mice Exposed to Ionizing Radiation: Sparing and Enhancing Effects of Dose Protraction.

During medical (therapeutic or diagnostic) procedures or in other settings, the circulatory system receives ionizing radiation at various dose rates. Here, we analyzed prelesional changes in the circulatory system of wild-type mice at six months after starting acute, intermittent, or continuous irradiation with 5 Gy of photons. Independent of irradiation regimens, irradiation had little impact on left ventricular function, heart weight, and kidney weight.

The Effects of Low-Dose-Rate γ-irradiation on Forced Swim Test-Induced Immobility and Oxidative Stress in Mice.

The forced swim test (FST) induces immobility in mice. Low-dose (high-dose-rate) X-irradiation inhibits FSTinduced immobility in mice due to its antioxidative function. We evaluated the effects of low-dose γ-irradiation at a low-dose-rate on the FST-induced depletion of antioxidants in mouse organs.

X-Irradiation at 0.5 Gy after the forced swim test reduces forced swimming-induced immobility in mice.

The forced swim test (FST) is a screening model for antidepressant activity; it causes immobility and induces oxidative stress. We previously reported that radon inhalation has antidepressant-like effects in mice potentially through the activation of antioxidative functions upon radon inhalation. This study aimed to investigate the effect of prior and post low-dose X-irradiation (0.

Comprehensive and computational analysis of genes in human umbilical vein endothelial cells responsive to X-irradiation.

Radiation exposure such as A-bomb or radiation therapy is considered a major health-risk factor for cardiovascular disease. In order to understand the molecular mechanisms underlying the inflammatory reaction frequently encountered in the vascular system after exposure to ionizing radiation, we carried out a global scale microarray and computational gene expression analyses on human umbilical endothelial cells (HUVECs) exposed to X-ray (2.5 Gy).

Emerging issues in radiogenic cataracts and cardiovascular disease.

In 2011, the International Commission on Radiological Protection issued a statement on tissue reactions (formerly termed non-stochastic or deterministic effects) to recommend lowering the threshold for cataracts and the occupational equivalent dose limit for the crystalline lens of the eye. Furthermore, this statement was the first to list circulatory disease (cardiovascular and cerebrovascular disease) as a health hazard of radiation exposure and to assign its threshold for the heart and brain. These changes have stimulated various discussions and may have impacts on some radiation workers, such as those in the medical sector.

Prolongation of life span in the accelerated aging klotho mouse model, by low-dose-rate continuous γ irradiation.

While lifespan studies provide basic information for estimating the risk of ionizing radiation, findings on the effect of low-dose/low-dose-rate irradiation on the lifespan of mammals are controversial. Here we evaluate the effect of continuous exposure to low-dose-rate γ radiation on the lifespan of mice with accelerated aging caused by mutation of the klotho gene. While control mice died within 80 days after birth, more than 10% of mice exposed continuously to 0.

Ultrasound activates ataxia telangiectasia mutated- and rad3-related (ATR)-checkpoint kinase 1 (Chk1) pathway in human leukemia Jurkat cells.

Low-intensity ultrasound (US) has been shown to induce death of cancer cells; however, the underlying mechanism remains unclarified. Here, we provide novel evidence that the inhibition of checkpoint kinase 1 (Chk1) by a selective inhibitor or small interfering RNA (siRNA) enhances US-induced apoptosis in Jurkat cells. Jurkat cells showed insignificant lysis immediately after US at any applied intensity, whereas approximately 70% of the cells were γH2AX-positive 30min after US at 0.

TGF-β-activated kinase 1 promotes cell cycle arrest and cell survival of X-ray irradiated HeLa cells dependent on p21 induction but independent of NF-κB, p38 MAPK and ERK phosphorylations.

Transforming growth factor-β-activated kinase 1 (TAK1) appears to play a role in inhibiting apoptotic death in response to multiple stresses. To assess the role of TAK1 in X-ray induced apoptosis and cell death, we irradiated parental and siRNA-TAK1-knockdown HeLa cells. Changes in gene expression levels with and without TAK1-knockdown were also examined after irradiation to elucidate the molecular mechanisms involved.

Molecular mechanisms of apoptosis induction by 2-dodecylcyclobutanone, a radiolytic product of palmitic acid, in human lymphoma U937 cells.

The irradiation of fat-containing food forms 2-dodecylcyclobutanone (2-DCB) from palmitic acid (PA). In this study, we investigated whether 2-DCB and PA induce apoptosis in human lymphoma U937 cells. We found that cell viability decreased by 2-DCB and apoptosis was induced by 2-DCB and PA.

Mitochondria-targeted superoxide dismutase (SOD2) regulates radiation resistance and radiation stress response in HeLa cells.

Reactive oxygen species (ROS) act as a mediator of ionizing radiation-induced cellular damage. Previous studies have indicated that MnSOD (SOD2) plays a critical role in protection against ionizing radiation in mammalian cells. In this study, we constructed two types of stable HeLa cell lines overexpressing SOD2, HeLa S3/SOD2 and T-REx HeLa/SOD2, to elucidate the mechanisms underlying the protection against radiation by SOD2.

Inhibition of checkpoint kinase 1 abrogates G2/M checkpoint activation and promotes apoptosis under heat stress.

Hyperthermia induced by heat stress (HS) inhibits the proliferation of cancer cells and induces their apoptosis. However, the mechanism underlying HS-induced apoptosis remains elusive. Here, we demonstrated a novel evidence that checkpoint kinase 1 (Chk1) plays crucial roles in the apoptosis and regulation of cell cycle progression in cells under HS.

Protective effects of radon inhalation on carrageenan-induced inflammatory paw edema in mice.

We assessed whether radon inhalation inhibited carrageenan-induced inflammation in mice. Carrageenan (1% v/v) was injected subcutaneously into paws of mice that had or had not inhaled approximately 2,000 Bq/m(3) of radon for 24 h. Radon inhalation significantly increased superoxide dismutase (SOD) and catalase activities and significantly decreased lipid peroxide levels in mouse paws, indicating that radon inhalation activates antioxidative functions.

Suppressive effects of continuous low-dose-rate γ irradiation on diabetic nephropathy in type II diabetes mellitus model mice.

It has been proposed that the development of diabetic nephropathy is caused in large part by oxidative stress. We previously showed that continuous exposure of mice to low-dose-rate γ radiation enhances antioxidant activity. Here, we studied the ameliorative effect of continuous whole-body irradiation with low-dose-rate γ rays on diabetic nephropathy.

Enhancement of radiation-induced apoptosis of human lymphoma U937 cells by sanazole.

Sanazole has been tested clinically as a hypoxic cell radiosensitizer. In this study, we determined whether sanazole enhances the radiation-induced apoptosis of human lymphoma U937 cells. Our results revealed that, compared with 10 mM sanazole or radiation alone, the combination of both resulted in a significant enhancement of apoptosis after 6 h, which was evaluated on the basis of DNA fragmentation, morphological changes, and phosphatidylserine externalization.

No Different Sensitivity in Terms of Whole-Body Irradiation between Normal and Acatalasemic Mice.

To elucidate the radiosensitivity of an acatalasemic mouse, we examined the time and dose-dependency in the survival rates, the lymphocytes and the intestinal epithelial cells, and the antioxidant function after 3.0 to 12.0 Gy whole body irradiation.

Enhancement of bio-protective functions by low dose/dose-rate radiation.

Effects of low-dose-rate gamma-irradiation on the process of tumorigenesis were investigated in mice treated with a carcinogenic agent or irradiated with high dose X-rays at a high dose rate. A prolonged gamma irradiation at approximately 1 mGy/hr suppressed the appearance of skin tumors induced by methylcholanthrene and delayed the appearance of radiation-induced thymic lymphomas in C57BL/6 mice. We also investigated the effects of low-dose-rate irradiation on disease model mice.

Enhancement of sodium butyrate-induced cell death and apoptosis by X-irradiation in the human colorectal cancer cell line HCT 116.

In this study, we aimed at evaluating the possible enhancing effect exerted by the combined use of sodium butyrate (SB) and X-rays on eradicating the human colorectal cancer cell line HCT 116 containing wild-type p53. We assessed the effect of this combination on the molecular pathways leading to cell death. HCT 116 cells were subjected to SB (1 mM) treatment followed by X-irradiation (5 Gy), and the effects on cell death, cell proliferation and cell cycle were examined.

Genes and genetic networks responsive to mild hyperthermia in human lymphoma U937 cells.

In this study, to better understand the molecular mechanism underlying cellular responses to mild hyperthermia, we investigated gene expression patterns and genetic networks in human myelomonocytic lymphoma U937 cells using high-density oligonucleotide microarrays and computational gene expression analysis tools. The cells were incubated at 41 degrees C for 30 min (mild hyperthermia treatment) and then at 37 degrees C for 0-6 h. Although the mild hyperthermia treatment of the cells did not induce apoptosis, significant increases in the protein expression levels of heat shock proteins (HSPs), namely, Hsp27, Hsp40 and Hsp70, were observed following the activation of heat shock factor-1.

Genetic networks responsive to low-intensity pulsed ultrasound in human lymphoma U937 cells.

To clarify the detailed molecular mechanism underlying cellular responses to nonthermal low-intensity pulsed ultrasound (LIPUS), gene expression patterns and genetic networks in human lymphoma U937 cells were examined using global-scale microarrays and computational gene expression analysis tools. Six hours after LIPUS treatment (0.3W/cm(2) for 1min), apoptosis (14+/-3.

Amelioration of type II diabetes in db/db mice by continuous low-dose-rate gamma irradiation.

Low-dose-rate radiation modulates various biological responses including carcinogenesis, immunological responses and diabetes. We found that continuous irradiation with low-dose-rate gamma rays ameliorated type II diabetes in db/db mice, diabetic mice that lack leptin receptors. Whole-body exposure of db/db mice to low dose-rate gamma radiation improved glucose clearance without affecting the response to insulin.

Effects of post low-dose X-ray irradiation on carbon tetrachloride-induced acatalasemic mice liver damage.

The catalase activities in the blood and organs of the acatalasemic (C3H/AnLCsb-Csb) mouse of the C3H strain are lower than those of the normal (C3H/AnLCSa-Csa) mouse. We examined the effects of post low-dose (0.5 Gy) X-ray irradiation which reduced the oxidative damage under carbon tetrachloride-induced hepatopathy in acatalasemic or normal mice.

Inhibitory effects of prior low-dose X-ray irradiation on carbon tetrachloride-induced hepatopathy in acatalasemic mice.

The catalase activities in blood and organs of the acatalasemic (C3H/AnLCs(b)Cs(b)) mouse of C3H strain are lower than those of the normal (C3H/AnLCs (a)Cs(a)) mouse. We examined the effects of prior low-dose (0.5 Gy) X-ray irradiation, which reduced the oxidative damage under carbon tetrachloride-induced hepatopathy in the acatalasemic or normal mice.

Adjustment function among antioxidant substances in acatalasemic mouse brain and its enhancement by low-dose X-ray irradiation.

The catalase activities in blood and organs of the acatalasemic (C3H/AnLCsbCsb) mouse of the C3H strain are lower than those of the normal (C3H/AnLCsaCsa) mouse. We conducted a study to examine changes in the activities of antioxidant enzymes, such as catalase, superoxide dismutase (SOD) and glutathione peroxidase (GPX), the total gluathione content, and the lipid peroxide level in the brain, which is more sensitive to oxidative stress than other organs, at 3, 6, or 24 hr following X-ray irradiation at doses of 0.25, 0.