scholarly journals Experiments on the inactivation of bacteriophage by radiations, and their bearing on the nature of bacteriophage

1946 ◽  
Vol 133 (873) ◽  
pp. 434-444 ◽  
Keyword(s):  
Exposure Time ◽  
Phage Particle ◽  
Genetic Material ◽  
Plant Viruses ◽  
X Rays ◽  
Survival Curves ◽  
Single Ionization ◽  
Restricted Region ◽  
Genetical Material

Three bacteriophages (S-13, C-36 and Staph-K) were irradiated by γ -rays, X -rays and α -rays. The survival curves were exponential, and the effect of a given dose was independent of the exposure time. For any given phage the inactivation doses of the three radiations increased in the order γ -rays, X -rays, α -rays, while for any given radiation the inactivation doses of the three phages diminished in the order S-13, C-36, Staph-K, which is the order of increasing size. These observations lead to the conclusion that a single ionization suffices to inactivate a phage particle. In the case of the smallest phage investigated (S-13) this ionization is effective wherever in the particle it is produced, and reasons are given for concluding from this fact that S-13 is a macromolecular type of virus analogous to the crystallizable plant viruses. In the case of the larger phages (C-36 and Staph-K ), while a single ionization can in­ activate a phage particle it is not sufficient for it to be produced anywhere in the phage particle; to be effective it must be produced in a more restricted region. It is suggested that this radiosensitive region constitutes the genetical material of the phage, and on the basis of this differentiation into genetic and non-genetic material these phages are regarded as primitive single-celled organisms rather than macromolecules.

scholarly journals Survival Curves and Age Response Functions for Chinese Hamster Cells Exposed to X-Rays or High LET Alpha-Particles

1972 ◽  
Vol 52 (1) ◽  
pp. 88 ◽  
Author(s):  
E. J. Hall ◽  
W. Gross ◽  
R. F. Dvorak ◽  
A. M. Kellerer ◽  
H. H. Rossi
Keyword(s):  
Chinese Hamster ◽  
Alpha Particles ◽  
X Rays ◽  
Response Functions ◽  
Survival Curves ◽  
Chinese Hamster Cells ◽  
High Let

Hydrogen Redistribution in Technically Pure Titanium Alloy under X-Ray Exposure at Room Temperature

2014 ◽  
Vol 880 ◽  
pp. 74-79 ◽  
Author(s):  
Viktor N. Kudiiarov ◽  
Andrey M. Lider ◽  
Natalya S. Pushilina
Keyword(s):  
Titanium Alloy ◽  
Surface Area ◽  
Exposure Time ◽  
Room Temperature ◽  
Hydrogen Diffusion ◽  
Pure Titanium ◽  
Hydrogen Desorption ◽  
X Rays ◽  
X Ray ◽  
State Increase

This paper presents experimental results in study of hydrogen redistribution in technically pure titanium alloy under X-ray exposure at room temperature. It is demonstrated that X-ray exposure to titanium with hydrogen affects hydrogen diffusion and redistribution from the surface area to the depth of the samples irrespective of hydrogen condition in titanium: in hydride form or dissolved state. Increase of the exposure time increases the amount of hydrogen redistributed. Hydrogen desorption during irradiation by X-rays at room temperature does not happen.

scholarly journals Modelling Dose Effects from Space Irradiations: Combination of High-LET and Low-LET Radiations with a Modified Microdosimetric Kinetic Model

Life ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 161 ◽  
Author(s):  
Alejandro Bertolet ◽  
Alejandro Carabe
Keyword(s):  
Kinetic Model ◽  
Poisson Distribution ◽  
Survival Curve ◽  
X Rays ◽  
Linear Quadratic ◽  
Survival Curves ◽  
Survival Fraction ◽  
High Let ◽  
Combined Action ◽  
High Linear Energy Transfer

The Microdosimetric Kinetic Model (MKM) to predict the effects of ionizing radiation on cell colonies is studied and reformulated for the case of high-linear energy transfer (LET) radiations with a low dose. When the number of radiation events happening in a subnuclear domain follows a Poisson distribution, the MKM predicts a linear-quadratic (LQ) survival curve. We show that when few events occur, as for high-LET radiations at doses lower than the mean specific energy imparted to the nucleus, zF,n, a Poisson distribution can no longer be assumed and an initial pure linear relationship between dose and survival fraction should be observed. Predictions of survival curves for combinations of high-LET and low-LET radiations are produced under two assumptions for their comparison: independent and combined action. Survival curves from previously published articles of V79 cell colonies exposed to X-rays, α particles, Ar-ions, Fe-ions, Ne-ions and mixtures of X-rays and each one of the ions are predicted according to the modified MKM. We conclude that mixtures of high-LET and low-LET radiations may enhance the effect of individual actions due to the increase of events in domains provided by the low-LET radiation. This hypothesis is only partially validated by the analyzed experiments.

Plasma sterilization. Methods and mechanisms

2002 ◽  
Vol 74 (3) ◽  
pp. 349-358 ◽  
Author(s):  
Michel Moisan ◽  
Jean Barbeau ◽  
Marie-Charlotte Crevier ◽  
Jacques Pelletier ◽  
Nicolas Philip ◽  
...  
Keyword(s):  
Significant Contribution ◽  
Genetic Material ◽  
Reactive Species ◽  
Gas Pressure ◽  
Survival Curves ◽  
Plasma Sterilization ◽  
Physicochemical Processes ◽  
Inactivation Process ◽  
Uv Photons ◽  
Oxygen Atoms

Utilizing a plasma to achieve sterilization is a possible alternative to conventional sterilization means as far as sterilization of heat-sensitive materials and innocuity of sterilizing agents are concerned. A major issue of plasma sterilization is the respective roles of ultraviolet (UV) photons and reactive species such as atomic and molecular radicals. At reduced gas pressure (£10 torr) and in mixtures containing oxygen, the UV photons dominate the inactivation process, with a significant contribution of oxygen atoms as an erosion agent. Actually, as erosion of the spore progresses, the number of UV photons successfully interacting with the genetic material increases. The different physicochemical processes at play during plasma sterilization are identified and analyzed, based on the specific characteristics of the spore survival curves.

scholarly journals INFLUENCE OF DEATH CRITERIA ON THE X-RAY SURVIVAL CURVES OF THE FUNGUS, NEUROSPORA

1934 ◽  
Vol 17 (4) ◽  
pp. 577-590 ◽  
Author(s):  
Fred M. Uber ◽  
David R. Goddard
Keyword(s):  
Survival Curve ◽  
X Rays ◽  
Survival Curves ◽  
Single Spore ◽  
Accurate Analysis ◽  
Single Well ◽  
Growth Production ◽  
Multiple Hit ◽  
Neurospora Tetrasperma ◽  
Ascospore Production

1. When ascospores of Neurospora tetrasperma were irradiated with 11 kv. X-rays, the single spore cultures obtained displayed a wide variety of mutated forms. 2. Control germinations of ascospores showed uniform behavior, ranging from 92–95 per cent germination. 3. The shape of the survival curves was found to be a function of the criterion of death. The following criteria were used: germination, growth, production of mature ascospores, and the production of normal perithecia. 4. The germination survival curve exhibited a rhythmic variation with dosage. Germination is not a significant criterion of death. 5. Half-survival dosages for growth and ascospore production were approximately 30,000 and 20,000 roentgens, respectively. 6. Multiple hit-to-kill relations were found on the basis of the quantum hit theory; no accurate analysis was possible. 7. The studies indicate that ascospore death does not result from a single well defined reaction, but rather from the integrated effects of several deleterious processes initiated by the radiation.

scholarly journals VLPs Derived from the CCMV Plant Virus Can Directly Transfect and Deliver Heterologous Genes for Translation into Mammalian Cells

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
María V. Villagrana-Escareño ◽  
Elizabeth Reynaga-Hernández ◽  
Othir G. Galicia-Cruz ◽  
Ana L. Durán-Meza ◽  
Viridiana De la Cruz-González ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Mammalian Cells ◽  
Plant Virus ◽  
Fluorescent Protein ◽  
Genetic Material ◽  
Eukaryotic Cell ◽  
Plant Viruses ◽  
Virus Capsids ◽  
First Time ◽  
Drug Nanocarriers

Virus-like particles (VLPs) are being used for therapeutic developments such as vaccines and drug nanocarriers. Among these, plant virus capsids are gaining interest for the formation of VLPs because they can be safely handled and are noncytotoxic. A paradigm in virology, however, is that plant viruses cannot transfect and deliver directly their genetic material or other cargos into mammalian cells. In this work, we prepared VLPs with the CCMV capsid and the mRNA-EGFP as a cargo and reporter gene. We show, for the first time, that these plant virus-based VLPs are capable of directly transfecting different eukaryotic cell lines, without the aid of any transfecting adjuvant, and delivering their nucleic acid for translation as observed by the presence of fluorescent protein. Our results show that the CCMV capsid is a good noncytotoxic container for genome delivery into mammalian cells.

scholarly journals Cross-section ratio of double to single ionization of helium by Compton scattering of 40–100-keV x rays

1999 ◽  
Vol 59 (1) ◽  
pp. 371-379 ◽  
Author(s):  
L. Spielberger ◽  
H. Bräuning ◽  
A. Muthig ◽  
J. Z. Tang ◽  
J. Wang ◽  
...  
Keyword(s):  
Compton Scattering ◽  
Cross Section ◽  
X Rays ◽  
Cross Section Ratio ◽  
Single Ionization ◽  
Section Ratio

scholarly journals Double and Single Ionization of Helium by 58-keV X Rays

1996 ◽  
Vol 76 (25) ◽  
pp. 4685-4688 ◽  
Author(s):  
L. Spielberger ◽  
O. Jagutzki ◽  
B. Krässig ◽  
U. Meyer ◽  
Kh. Khayyat ◽  
...  
Keyword(s):  
X Rays ◽  
Single Ionization

Contribution à l'étude des effets de charge sur l'émission X des matériaux isolants non métallisés

2002 ◽  
Vol 80 (6) ◽  
pp. 661-674
Author(s):  
K Raouadi ◽  
R Renoud ◽  
B Askri ◽  
B Yangui ◽  
Z Fakhfakh
Keyword(s):  
Electron Beam ◽  
Electric Field ◽  
Generating Function ◽  
Exposure Time ◽  
Primary Beam ◽  
X Rays ◽  
Electron Trajectories ◽  
Characteristic Lines

The presence of charges perturbs the X-microanalysis on insulator samples. Attempts to suppress these effects have been fruitless and a better understanding of the charge phenomenon is the only way to a clear interpretation of the results of a X-microanalysis. From a simulation of the charges implanted by an electron beam on an insulator target, we compute, as a fuction of the integrated dose, the characteristics of the emitted X-rays, such as the generating function ϕ (ρ z) or the intensity of the characteristic lines. We underline the role of the electric field on the primary beam and on the electron trajectories in the target. These results allow the analysis of experimentally measured X-rays. Our studies on the effects of the diameter of the probe and on the exposure time led us to establish the best conditions for the successful X-microanalysis of an insulator. [Journal translation]

scholarly journals Association of Caspase 3 Activation and H2AX γ Phosphorylation in the Aging Brain: Studies on Untreated and Irradiated Mice

Biomedicines ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1166
Author(s):  
Nadia Gionchiglia ◽  
Alberto Granato ◽  
Adalberto Merighi ◽  
Laura Lossi
Keyword(s):  
Dna Damage ◽  
Caspase 3 ◽  
Genetic Material ◽  
Aging Brain ◽  
Dna Integrity ◽  
X Rays ◽  
Proliferating Cells ◽  
Dna Repair Mechanisms ◽  
Repair Mechanisms ◽  
Old Mice

Phosphorylation of H2AX is a response to DNA damage, but γH2AX also associates with mitosis and/or apoptosis. We examined the effects of X-rays on DNA integrity to shed more light on the significance of H2AX phosphorylation and its relationship with activation of caspase 3 (CASP3), the main apoptotic effector. After administration of the S phase marker BrdU, brains were collected from untreated and irradiated (10 Gray) 24-month-old mice surviving 15 or 30 min after irradiation. After paraffin embedding, brain sections were single- or double-stained with antibodies against γH2AX, p53-binding protein 1 (53BP1) (which is recruited during the DNA damage response (DDR)), active CASP3 (cCASP3), 5-Bromo-2-deoxyuridine (BrdU), and phosphorylated histone H3 (pHH3) (which labels proliferating cells). After statistical analysis, we demonstrated that irradiation not only induced a robust DDR with the appearance of γH2AX and upregulation of 53BP1 but also that cells with damaged DNA attempted to synthesize new genetic material from the rise in BrdU immunostaining, with increased expression of cCASP3. Association of γH2AX, 53BP1, and cCASP3 was also evident in normal nonirradiated mice, where DNA synthesis appeared to be linked to disturbances in DNA repair mechanisms rather than true mitotic activity.

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