Translation. Region: Russian Federal
Source: Novosibirsk State University – Novosibirsk State University –
Researchers from the Laboratory of Nuclear and Innovative Medicine of Novosibirsk State University, together with specialists from the Research Institute of Clinical and Experimental Lymphology (NIIKEL, a branch of the ICG SB RAS), the Novosibirsk branch of the S.N. Fedorov National Medical Research Center for Scientific and Technical Complex “Microsurgery of the Eye” of the Ministry of Health of the Russian Federation, the Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, the N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS (NIOC SB RAS), and the G.I. Budker Institute of Nuclear Physics (INP SB RAS) conducted a series of experiments to study the effects of various protocols for irradiating rabbit eyes with terahertz radiation. The results of the study were published in the article “Assessment of the general clinical condition and functional properties of the eyes of rabbits after THz irradiation” published in the journal Biomedical Optics Express.
The studies were conducted on a unique source of terahertz radiation of the biological user station of the Novosibirsk Free Electron Laser (NFEL) of the Institute of Nuclear Physics SB RAS with a frequency of 2.3 THz and an intensity of 0.012–0.024 mW/cm2. Irradiation durations of 15 and 30 minutes with different intensities were used.
The scientists specified that all observed changes in the cornea of the laboratory animals were subclinical, i.e. asymptomatic, and did not lead to significant pathological changes. These scientific studies are aimed at developing future instructions and recommendations for working with THz radiation and have been approved by the Ethics Committee.
— In the process of preparing and conducting the experiment, it was necessary to generate a lot of know-how and life hacks related to both purely practical issues, for example, with the delivery of rabbits to the INP for irradiation in winter, and with the organization of their ophthalmological examination. Some of the diagnostic studies were carried out on equipment provided to us by the Interra veterinary network and its director Elena Drobot, which greatly simplified our logistics. And in general, this is a very large-scale experiment in terms of the number of participants, which was conceived by NSU and which was completely impossible to implement without the INP, namely without the unique FEL installation and this user station. The task that we set for ourselves — to see how terahertz radiation affects the tissues of a healthy organism of a large model animal — we accomplished. And it is rabbits as an object of research that are good because the data obtained on them are most extrapolated to humans, — said the head of the Laboratory of Nuclear and Innovative Medicine Physics Department of NSU Vladimir Kanygin.
The collaboration of scientists approached the preparation and setting up of the experiment very carefully, performing each stage as thoroughly as possible. This was necessary to cut off any external factors affecting living organisms, such as a change in the usual temperature regime, stress from transportation, etc. Before the experiment, the laboratory animals underwent a 14-day quarantine in the vivarium of the NIOC SB RAS. Before the start of the experiments, the veterinarians participating in the work conducted a full examination of the animals to exclude possible eye diseases, such as cataracts.
Diagnostic examinations of rabbits were conducted on day zero, i.e. on the day of irradiation, the next day, a week later and a month later by specialists of the Scientific and Technical Complex “Microsurgery of the Eye”. Veterinarians monitored the condition of the rabbits at each stage of irradiation and after it.
— Ophthalmologists conducted diagnostic studies of the rabbits’ eyes using optical computed tomography and endothelial microscopy. Our study confirms the fact of the dose-dependent effect of terahertz radiation at high frequencies on the structures of the anterior segment of the eye, in particular, on the endothelial layer of the cornea, which is a unique “pump” for maintaining optimal hydration and homeostasis of the cornea, — explained Kristina Krasner, assistant of the Department of Surgical Diseases of the Institute of Medicine and Medical Technologies of NSU, ophthalmologist of the Novosibirsk branch of the Scientific and Technical Complex “Microsurgery of the Eye”, junior researcher of the laboratory of cell technologies of the Research Institute of Cellular and Electron Microsurgery.
On the day of irradiation, the animals’ blood was tested, which showed that a systemic inflammatory process was occurring in the body. However, scientists came to the conclusion that this was the body’s reaction to stress, since living organisms have no mechanisms of protection against terahertz radiation.
Further studies have shown that terahertz radiation with parameters of 2.3 THz and intensity of 0.012–0.024 mW/cm2 for 30 minutes is conditionally safe for the structures of the rabbit eye. However, the detected changes in the cornea require further study to determine safe exposure limits. It was noted that irradiation of the rabbit cornea led to a decrease in the density of endothelial cells. The detected changes were reversible and did not lead to pathological changes in the cornea.
— Terahertz radiation and terahertz spectroscopy based on it can really enter clinical practice as an effective method for diagnosing oncological diseases or for possible diagnostics of diseases of the organ of vision. Despite the fact that this type of diagnostics is currently experimental and is at the development stage, it is already necessary to start thinking about safety recommendations when working with sources of terahertz radiation. In the course of this study, we studied the effect of various terahertz radiation protocols in time and intensity on the cornea of the eyes of eight laboratory animals – rabbits. We assessed only changes in the anterior segment of the eyeball. Based on the data we obtained, it is premature to draw final conclusions, but the study is a good foundation for drawing up such recommendations in the future, — commented Ekaterina Butikova, Junior Researcher at the Laboratory of Cell Technologies, Research Institute of Cellular and Electron Chemistry, Branch of the Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences.
Scientists involved in the experiments emphasize that the generation of terahertz radiation with the parameters required to conduct the study is only possible at the biological user station of the Novosibirsk Free Electron Laser (NFEL) of the INP SB RAS.
— In terms of average power, NLSE exceeds any existing sources in the world by many orders of magnitude, which allows us to conduct absolutely unique experiments in a very wide range of wavelengths with various biological objects. If we affect living systems with terahertz radiation, we can quite strongly influence the work of their cells, the processes occurring inside them. Such experiments are of interest from the point of view that no living organism has developed any protective mechanisms against intense THz radiation, since it is completely absorbed by the atmosphere, which means that by affecting biological objects, we can study how they adapt, what protective mechanisms they activate. For such biological experiments, a special user station was created at NLSE, which implemented the technology for regulating the average and peak radiation power, as well as the intensity of exposure. For the purity of the experiments, the station was equipped with a shutter and a thermal imager — these devices maintain and control the desired temperature. Thanks to this, we understand that we are receiving the system’s reaction specifically to the effect of radiation, and not to an increase or decrease in temperature, explained Vasily Popik, a senior researcher at the INP SB RAS and a candidate of physical and mathematical sciences.
Experiments on laboratory animals are widely used all over the world to obtain fundamental knowledge, as well as to identify the root causes of various diseases in humans and animals, to study treatment options. All such experiments are conducted in accordance with ethical standards for the treatment of laboratory animals and are approved by the ethics committee before they begin. The Bioethics Committee of the ICG SB RAS approved the experimental work with animals on the topic: “Clinical changes in the rabbit cornea after exposure to THz radiation.”
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