Effects of Gamma-Rays on Solutions of Sodium Deoxyribonucleate: Possible Chemical Mechanism for their Biological Effects

Nature ◽  
1955 ◽  
Vol 176 (4489) ◽  
pp. 919-921 ◽  
Author(s):  
R. A. COX ◽  
W. G. OVEREND ◽  
A. R. PEACOCKE ◽  
S. WILSON
Keyword(s):  
Gamma Rays ◽  
Biological Effects ◽  
Chemical Mechanism

Biological Effects of Gamma-Rays

1931 ◽  
Vol 37 (3) ◽  
pp. 330-331
Author(s):  
W. G. Whitman ◽  
M. A. Tuve
Keyword(s):  
Gamma Rays ◽  
Biological Effects

scholarly journals Evaluation of radioprotective effect of chickpea (Cicer arietinum) in the survival of Lasioderma serricorne (Fabricius, 1792) (Coleoptera, Anobìidae) irradiated with 60Co

2019 ◽  
Author(s):  
Adilson C. Barros ◽  
Kayo Okazaki ◽  
Valter Arthur
Keyword(s):  
Gamma Rays ◽  
First Generation ◽  
Biological Effects ◽  
Control Diet ◽  
Whole Grains ◽  
Lasioderma Serricorne ◽  
Protective Properties ◽  
Summary Statement ◽  
Set Up ◽  
Radioprotective Properties

ABSTRACTWe investigated the presence of natural radioprotectors in food using a new technical modality that utilizes the insect Lasioderma serricorne as a radiosensitivity bioindicator to check radioprotection properties in minimally processed chickpeas. The insects were obtained from the entomological biotherium of the Laboratory of Radiobiology and Environment of CENA-USP. They were fed with an experimental diet and just when the first generation hatched completely, the experiments were conducted. The randomly chosen control diet, consisted of three parts of wheat germ, one part of brewer’s yeast, and a slice of French bread toasted in an oven previously set up for humidity control. The diet of chickpeas consists only of whole grains crushed in a mechanical grinder to obtain flour. The result was significant for the survival of insects (p<0.0001) reared on a diet of chickpeas compared to those reared on control diet irradiated with gamma rays from 60Co in the range of 5.0 to 1500 Gy. We presented statistical evidence that the chickpea diet has radioprotective properties in the insect for gamma rays.SUMMARY STATEMENTThe study is important because it shows that chickpea has protective properties against ionizing radiation, how to act against its biological effects and minimize them.

scholarly journals The physical basis of the biological effects of high voltage radiations

1934 ◽  
Vol 146 (859) ◽  
pp. 867-879 ◽  
Keyword(s):  
Gamma Rays ◽  
High Voltage ◽  
High Speed ◽  
Biological Effects ◽  
Wave Length ◽  
X Rays ◽  
Absorbed Energy ◽  
Electron Production ◽  
The Mean ◽  
Complex Manner

Although both the physical properties of penetrating X-rays and gamma rays and their biological effects have been carefully studied, the mechanism of the action of the rays is little known. The question of the relative effects of the same absorbed energy per cubic centimetre of tissues when different wave-lengths are used is a particularly important and obscure one. The present paper is attempt to apply recent theories of high-speed electron production to this problem. Radiations, such a high voltage X-rays or gamma rays, on suffering real absorption give rise to high speed negative electrons, either in photoelectric absorption whereby nearly the whole of the quantum is transferred to the electron, or in a Compton recoil process in which only part of the energy is transferred. The mean fraction given to the electrons rises gradually as the radiations become more penetrating. The relative importance of these two types of process varies in a complex manner with the wave-length and absorbing materials, but in this paper it is proposed to confine discussion to the absorption of “hard” radiations in light elements, of which living materials are mostly constructed.

scholarly journals Activation of Heat Shock and Antioxidant Responses by the Natural Product Celastrol: Transcriptional Signatures of a Thiol-targeted Molecule

2008 ◽  
Vol 19 (3) ◽  
pp. 1104-1112 ◽  
Author(s):  
Amy Trott ◽  
James D. West ◽  
Lada Klaić ◽  
Sandy D. Westerheide ◽  
Richard B. Silverman ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Heat Shock ◽  
Natural Product ◽  
Mammalian Cells ◽  
Environmental Changes ◽  
Biological Effects ◽  
Transcriptional Profiling ◽  
Chemical Mechanism ◽  
Quinone Methide ◽  
Chinese Medicinal Herb

Stress response pathways allow cells to sense and respond to environmental changes and adverse pathophysiological states. Pharmacological modulation of cellular stress pathways has implications in the treatment of human diseases, including neurodegenerative disorders, cardiovascular disease, and cancer. The quinone methide triterpene celastrol, derived from a traditional Chinese medicinal herb, has numerous pharmacological properties, and it is a potent activator of the mammalian heat shock transcription factor HSF1. However, its mode of action and spectrum of cellular targets are poorly understood. We show here that celastrol activates Hsf1 in Saccharomyces cerevisiae at a similar effective concentration seen in mammalian cells. Transcriptional profiling revealed that celastrol treatment induces a battery of oxidant defense genes in addition to heat shock genes. Celastrol activated the yeast Yap1 oxidant defense transcription factor via the carboxy-terminal redox center that responds to electrophilic compounds. Antioxidant response genes were likewise induced in mammalian cells, demonstrating that the activation of two major cell stress pathways by celastrol is conserved. We report that celastrol's biological effects, including inhibition of glucocorticoid receptor activity, can be blocked by the addition of excess free thiol, suggesting a chemical mechanism for biological activity based on modification of key reactive thiols by this natural product.

Burns by Ionizing and Non-Ionizing Radiation

2020 ◽  
Author(s):  
Giovanni Alcocer ◽  
Priscilla Alcocer ◽  
Carlos Marquez
Keyword(s):  
Ionizing Radiation ◽  
Visible Light ◽  
Gamma Rays ◽  
Biological Effects ◽  
High Energy ◽  
Low Energy ◽  
X Rays ◽  
Nuclear Accidents ◽  
Diagnostic Equipment ◽  
Nonionizing Radiation

Abstract This article consists of the study and investigative analysis of the effects of burns by radiation in humans. Cases of nuclear accidents, such as Chernobyl (ionizing radiation) and the effects of non-ionizing radiation such as infrared and microwave radiation are detailed. It is examined cases of injuries and burns by ionizing radiation due to irradiation (diagnostic equipment and medical treatment: X-rays, radiotherapy) or contamination (nuclear accidents, wars). Injuries and burns are also caused by nonionizing radiation, such as visible light (laser), ultraviolet, radiofrequency. There are numerous biological issues in the case of tissues, the ionizing radiation (ionizing particles and electromagnetic radiation: X-rays, gamma rays and high energy ultraviolet) can cause damage mainly in the DNA. This can cause mutations in its genetic code and cancer 5. In addition, damage to other tissues and organs can occur, as well as burns, erythema and lesions. The biological effects of nonionizing radiation are currently under investigation. Burns, erythema and lesions can also occur due to the following types of radiation: low energy ultraviolet, visible light, infrared, microwave, radiofrequency, electromagnetic fields. The purpose of this article is to provide an exhaustive analysis of all types of both ionizing and non-ionizing radiation and their effects on living beings. Finally, it is important to follow all safety and radiation protections against both ionizing and non-ionizing radiation.

The action of γ -rays on sodium deoxyribo-nucleate in solution

1958 ◽  
Vol 149 (937) ◽  
pp. 511-533 ◽  
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Bonds ◽  
Biological Effects ◽  
Ultra Violet ◽  
Helical Structure ◽  
Chemical Mechanism ◽  
Negative Slope ◽  
Single Chain ◽  
Double Helical Structure ◽  
Logarithmic Plot

The effect of irradiation by γ -rays from a cobalt-60 source, without exclusion of oxygen, on the molecular structure of herring sperm sodium deoxyribonucleate ( DNA ) has been studied with the following aims: (i) to obtain evidence on the existence of the double-helical DNA structure in aqueous solution by testing the application of recent theoretical treatments for the random fracture of single-chain macromolecules (Charlesby 1954); and (ii) to study the effects of dosages of γ -rays lower than those which have been shown to disrupt the constituent nucleotides. Changes in viscosity, electrometric titration behaviour, ultra-violet absorption, precipitability and other chemical properties have been investigated. The viscosity of solutions of DNA in 0·1 M-sodium chloride was decreased on irradiation by an amount which was independent of the dose rate and was determined by the ratio ( R , in eV/atom of DNA phosphorus) of dosage in eV entering each ml. of solution to concentration of DNA phosphorus. The reduced specific viscosity of irradiated DNA solutions was a linear function of concentration and obeyed the Huggins equation (Huggins 1942). The intrinsic viscosity [ ƞ ] decreased with increasing R and, on a logarithmic plot, the relation was linear with a negative slope of 1.9 at the higher R values. Comparison of this value with that expected from the theory of random degradation leads to the proposal that a decrease in molecular weight, and thus in [ ƞ ], of the DNA can occur only when two independent breaks occur at approximately opposite positions in each of two intertwined polynucleotide chains; this indicates that the double-helical structure adduced for the moist solid state persists in aqueous solution. This is confirmed by the observation that a DNA preparation which had undergone mild acid treatment before irradiation, in order to disrupt the complementary cross-linking hydrogen bonds (Watson & Crick 1953 a ) and there by the double-helical structure, exhibited a less steep decrease of [ ƞ ] with increasing R (i.e. a slope of — 1·2 on the logarithmic plot). The earlier theory for the viscosity of a single-chain macromolecule undergoing random breakdown is extended to the case of degradation of a cross-linked molecule consisting of two intertwined chains. The difference between the forward-and backward-titration curves characteristic of the hydrogen-bonded DNA structure decreased on γ -irradiation, which indicates a progressive disruption of the complementary hydrogen bonds and of the double-helical structure that they hold together; this was confirmed by observed parallel increases in ultra-violet absorption. The asymmetrical character of the displacement suggests, though not quite conclusively, that the hydrogen bonds linking adenine and thymine were ruptured more readily than those joining guanine and cytosine. The combined rupture of all hydrogen bonds had initially a very high G value, of the order of sixty base pairs severed per 100 eV, but this decreased with increasing dosage. This efficient rupture of complementary hydrogen bonds would presumably impair the duplication of the DNA helices in vivo and may underlie some of the biological effects of low dosages of ionizing radiation. The titration studies demonstrated the release at high R of approximately equal quantities of acidic groups with pK' a of about 4·5 to 5·5 and of 5·5 to 8·5; this observation is discussed briefly in connexion with the detailed chemical mechanism of the rupture of phospho-ester linkages. The indirect nature of the action of γ -rays under the present conditions was con-confirmed by the determinative character of the ratio R and by the inhibitory effects of certain com pounds known to combine with the free radicals produced in the water.

A Difference between Biological Effects of Gamma Rays and Heavy Ions

Science ◽  
1960 ◽  
Vol 132 (3436) ◽  
pp. 1311-1312 ◽  
Author(s):  
F. Hutchinson ◽  
S. S. Easter
Keyword(s):  
Gamma Rays ◽  
Heavy Ions ◽  
Biological Effects
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