Radiation Inactivation of Coronavirus Infection Pathogen by the Example of Transmissible Gastroenteritis Virus

Biophysics - In recent years, members of the Coronaviridae family have caused outbreaks of respiratory diseases (MERS, SARS, and COVID-19). At the same time, the potential of radiation-induced...     

The Change in the Linear Energy Transfer of a Clinical Proton Beam in the Presence of Gold Nanoparticles

Biophysics - Gold nanoparticles are promising radiosensitizers for proton radiotherapy. However, the physical mechanisms of gold nanoparticles radiosensitization remain unclear. In the present...     

Vaccine prophylaxis in elderly patients

In 1997-1999 observation was made on elderly people living in old people's homes and in families, as well as groups of young males living in hostel-type homes, altogether 4,518 subjects. Standard inactivated whole-virion influenza vaccine was introduced in a dose of 0.5 ml subcutaneously in a single injection or intranasally in two administrations. In control groups placebo was used. The frequency of seroconversions to vaccine strains of influenza viruses was significantly less in elderly people than in young people following both subcutaneous and intranasal immunization (on the average, by 15-20%). In young people the prophylactic effectiveness of the vaccine introduced intranasally was the same as after subcutaneous immunization with the effectiveness index (EI) being equal to 2.1-2.8. In elderly people the effectiveness of the vaccine after subcutaneous immunization was the same as in young people (EI = 1.7-2.7), but insufficient after intranasal immunization (EI < or = 1.6). The preparation "Amber elixir plus" enhanced the effectiveness of immunization against influenza in elderly people.     

The Prospects of Metal Oxide Nanoradiosensitizers: The Effect of the Elemental Composition of Particles and Characteristics of Radiation Sources on Enhancement of the Adsorbed Dose

Nanoparticles with a high atomic number are of interest as radiosensitizers for radiation therapy of cancer. A variety of nanoparticles and radiation sources makes the challenge of selecting their optimal combinations to achieve maximum irradiation efficacy relevant. In this work, we calculated the values of the dose enhancement factors of elemental compositions of metal oxide nanoparticles (Al₂O₃, TiO₂, MnO₂, Fe₂O₃ and Fe₃O₄, NiO, GeO₂, ZrO₂, CeO₂, Gd₂O₃, Tm₂O₃, HfO₂, Ta₂O₅, and Bi₂O₃), as well as GeO₂ and HfO₂ doped with the rare-earth elements lanthanum or ytterbium in combination with monochromatic photons (1–500 keV) and X-ray radiation corresponding to the radiation of kilovoltage X-ray therapy machines. At a nanoparticle concentration of 10 mg/mL, the maximum values of the dose enhancement factors were from 1.03 to 2.55 for monochromatic radiation and from 1.01 to 2.33 for the studied X-ray spectra. Doping GeO₂ with 20% lanthanum or ytterbium led to an increase in the maximum value of dose enhancement factors by ~10%. Doping HfO₂ did not lead to significant changes in the value of dose-enhancement factors. Thus, all studied elemental compositions of nanoparticles, with the exception of Al₂O₃ (a dose enhancement factor ~1.02), are promising for application in kilovoltage X-ray radiotherapy. At the same time, the complex dependence of dose enhancement factors on the spectral composition of X-ray radiation requires detailed studies of the impact of irradiation conditions on the magnitude of the radiomodifying effect of nanoparticles.

     

The Effect of Gold Nanoparticle Surface Modification with Polyethylene Glycol on the Absorbed Dose Distribution upon Irradiation with 137Cs and 60Co Photons

Biophysics - Abstract—Modification of the surface of gold nanoparticles with polyethylene glycol (PEG) is widely used to investigate radiosensitization in vivo. This modification may lead to...