[Schwannoma of the parapharyngeal space]. / Shvannoma parafaringeal'nogo prostranstva.

Schwannoma is a benign neoplasm that develops from the Schwann cells of the nerve sheath. The share of neurogenic tumors of the parapharyngeal space accounts for 0.5% of all neoplasms of this localization. The article demonstrates a case from practice, presents the clinical features, diagnostics and methods of treatment for patients with pharyngeal neuromas. The peculiarity of the presented clinical observation is due to the rare occurrence of this pathology and the large size of the schwannoma in the long-term asymptomatic course of the disease.

[Giant destructive polyps of the nasal cavity (clinical case)]. / Klinicheskii sluchai gigantskikh destruktivnykh polipov polosti nosa.

Conservative therapy for chronic polyposis rhinosinusitis are well covered, and modern endoscopic rhinosurgery can effectively cope with this pathology. Clinical cases of large destructive anthrochoanal polyps are not uncommon, the pathology is well studied. However, cases with giant sinonasal polyposis, which lead to bone-destructive changes in the bones of the nose and the walls of the paranasal sinuses are very rare. We found only one case similar to the clinical observation presented in this article.

[Our first experience with endoscopic ear surgery]. / Opyt primeneniia éndoskopicheskoi tekhniki v otokhirurgii u detei.

INTRODUCTION: For the last decades endoscopic ear surgery has become a common practice. Advantages of the endoscopic technique in middle ear surgery are high definition and magnification of the endoscope with a modern camera and the ability to 'look around the corner' with the angled scope. MATERIAL AND METHODS: From March 2017 to November 2019 in NSRC PHOI named after Dmitry Rogachev in the Department of Oncology and Pediatric Surgery 53 patients (81 surgeries) have undergone endoscopic-assisted ear surgery: 3 biopsies for middle ear neoplasm with the transcanal endoscopic approach, 1 endoscopic tympanoplasty for attic retraction pocket with cholesteatoma, 2 endoscopic removal of middle ear tumors (including 1 combined approach) and 32 endoscopic myringoplasties, 22 canal wall down mastoidectomies for extensive middle ear and mastoid cholesteatoma, 21 second-look surgery with ossiculoplasty with overall good outcome. Age of the patients varied from 2 months to 16 years. Follow up period varied from 1 month to 3 years. RESULTS: Two cases of middle ear tumor removal via endoscopic transcanal approach are described. In one case endoscopic transmeatal approach was used as an addition to the middle fossa approach for removal of facial nerve neurinoma located on the upper surface of petrous bone with expansion to the middle ear cavity. In the second case endoscopic transmeatal approach was used alone for removal of benign tumor (salivary gland choristoma) of middle ear cavity with extension to pneumatic system of petrous bone. In both cases endoscopic approach allowed to biopsy the tumor first and then to remove the tumor in a less invasive way, which lead to faster patient recovery. CONCLUSION: In the majority of cases endoscopic technique is a method of assistance in otologic surgery, but sometimes could be a used a single method in middle ear surgery, allowing less traumatic approach and the implementation of high-definition camera for more precise disease control. In our preliminary experience endoscopic technique could be used in pediatric practice independently of the patient's age.

Kinetics and mechanism of the reaction of fluorine atoms with pentafluoropropionic acid.

The kinetics of the reaction between fluorine atoms and pentafluoropropionic acid has been studied experimentally at T = 262-343 K. The overall reaction rate constant decreases with temperature: k1(T) = 6.1 × 10(-13) exp(+1166 K)/T) cm(3) molecule(-1) s(-1). The potential energy surface of the reaction has been studied using quantum chemistry. The results were used in transition state theory calculations of the temperature dependences of the rate constants of the two channels of the reaction. The abstraction channel ultimately producing HF, C2F5, and CO2 is dominant at the experimental temperatures; the addition-elimination channel producing C2F5 and CF(O)OH becomes important above 1000 K.

[Estimation of UV light dose concomitant to ionizing irradiation].

A simple approach to the estimation of UV light dose produced by Cerenkov emission and concomitant irradiation of biological objects with ionizing radiation was suggested. The approach was applied to determine the dependencies of UV light dose (equivalent to 254 nm) accompanied 100 Gy of ionizing radiation on the energy of sparsely ionizing radiation and on the volume of the exposed Escherichia coli cells suspension. It was revealed that the relative excitation contribution to the total lethal effect and the value of the UV dose was greatly increased with an increase in the energy of ionizing radiation and the volume of irradiated suspensions. It is concluded that these observations are in agreement with the supposition that Cerenkov emission is responsible for the production of UV light damage and the phenomenon of photoreacrivation observed after ionizing exposure of bacterial and yeast cells hypersensitive to UV light. A possible synergistic interaction of the damages produced by ionizations and excitations as well as a probable participation of UV component of ionizing radiation in the mechanism of radiation hormesis and adaptive response observed after ionizing radiation exposure is discussed.

[Osmotic homeostasis as one of critical targets of cell damage by some environment factors].

The analysis of ours and literary data confirmed author new conception of cell damage mechanism by some environment factors according which the system of osmotic homeostasis is one of the critical targets of such damage, is presented.

[Phenomenon of Escherichia coli viability reactivation during late periods of culture in salt buffer after ionizing irradiation].

The experimental showing, that reactivation viability phenomenon of E. coli B/r bacteria in phosphate buffer takes place only after irradiation under certain dose range of 60Co gamma-ray, induced the death of certain part of viable cell bacteria population, are presented. It was illustrated that intensity of reactivation viability phenomenon of bacteria do not depend on the concentration of viable microorganisms and the presence in suspension medium nutrient material, leaved of irradiated cells. The received data shown that in the base of the phenomenon there are the processes, distinguished from processes of usual cell reproduction, and may be the consequence of radiostimulate influence on the cell physiology, known from literature, as hormesis.

[About the characters of thermoprotection in influence of osmolites on bacteria].

The influence of the length of staying of Escherichia coli B/r cells in hypertonic NaCl solution before heating at 52 and 60 degrees C on the magnitude of salt thermoprotection was investigated. In addition, the dependence of the isotonic and thermoprotective NaCl concentrations on the exposure temperature was investigated. It was shown that the volume of cell osmotic thermoprotection was independent on the length of preliminary staying of microorganisms in hypertonic NaCl solution. It was also shown that the magnitude of isotonic and thermoprotective osmolite concentrations increased with the increase in the exposure temperature. The analysis of the data obtained and published in literature indicates that the compensating mechanism is involved in salt bacteria thermoprotection rather than the dehydratation one.

[Effect of ionizing irradiation of low intensity on the viability of Escherichia coli bacteria, cultivated in the salt buffer].

The influence of 60Co gamma-ray irradiation of low intensity (0.35 Gy/min) on the viability of Escherichia coli B/r and Escherichia coli BS-1 bacteria cultivated in salt buffer in concentration of 10(8) cell/ml was investigated. It was shown that under the doses induced the cell killing about 60-75%, the irradiated bacteria, like intact cell, were killed during the incubation process, while after the doses induced the cell killing above 99% of cell population, the bacteria viability of the both strains was increased. The increase reaches a certain value on the 2-5 the days of bacterial incubation in this conditions. The nature of observed phenomenology is vague for the present.

[The influence of cyclic heating and cooling on Escherichia coli survival].

Repeated heating and cooling in lethal (2-52 degrees C) and nonlethal (2-37 degrees C) temperature ranges resulted in cell death of Escherichia coli B/r and E. coli B(S-1) suspended in 0.01 M phosphate buffer, pH 7.0 at varying osmotic pressure, but not in cow's milk. The lethal effect increased with the rate of heating and with increasing suspension media tonicity; it may be caused by the temperature destabilization of cellular osmotic homeostasis.

[The influence of ionizing radiation of high intensity on the viability of Escherichia coli bacteria, cultivated in the salt buffer without nutrient additions].

The influence of 60Co gamma-ray radiation of high intensity (85 Gy/min) on the viability of E. coli B/r and E. coli BS-1 bacteria, cultivated in salt buffer with the concentration about 10(8) cells/ml, was studied. It was determined that under the doses, which induce about 80% of death of the cells, the irradiated bacteria, just like the intact cells, die during the incubation processes, while under the doses induced the death of cells above 95%, the cells viability of the both strains increases and reaches the constant value by the byhend 2nd-5th days of incubation in these conditions. In the result of the differences of the reactions of the intact and irradiated with different doses of radiation microorganisms on the incubation during their postradiational period in the phosphate buffer we have the fact of the absence of the dependence of the effect from the dose, or the decreasing of the consequences of the radiation under the increasing of the dose of the radiation. The nature of this phenomenology while stays not understood.

Quantitative evaluation of the parameters of bacterial photoreactivation after exposure to ultraviolet light and ionizing radiation.

The purpose was to compare quantitatively the parameters of photoreactivation of an ultraviolet (UV) light hypersensitive strain of Escherichia coli Bs-1 irradiated with UV light and ionizing radiation. In addition, to evaluate the influence of the different physical and chemical factors on the parameters of the photoreactivation kinetics of the bacterial cells exposed to ionizing radiation. Survival curves and kinetics of the photoreactivation were measured in E. coli Bs-1 cells exposed to UV light (254 nm) and ionizing radiations (gamma-rays of 137Cs, gamma-rays of 60Co and 25 MeV pulsed X-rays). A mathematical model describing the process of photoreactivation in terms of a decreasing effective dose was applied to the experimental data obtained here and that published by others to evaluate quantitatively the probability of photoreactivation and the irreversible component of the radiation damage. Both the rate and extent of photoreactivation decreased in the following order of inactivating agents: WUV light, pulsed X-ray beam, gamma-ray of 60Co and gamma-ray of 137Cs. However, the irreversible component of radiation damage increased with the same order of radiations whereas the probability of photoreactivation per unit time was independent of the kind of radiation. After exposure to 6 MeV photons, the parameters of photoreactivation were changed in the presence of caffeine or after irradiation in the presence of the radioprotective agent dithiothreitol. The independence of the probability of photoreactivation on the quality of radiation indicates the cells have the same ability to photoreactivate damage produced by different kinds of radiations and is an additional argument indicating that during ionizing radiation a UV-like damage can be produced. The decrease in the extent and the rate of photoreactivation with radiation quality is explained by the formation of irreversible damage rather than by the impairment of the photorecovery process itself. Chemical and physical factors influencing the relative contribution of ionization and excitation on the ionizing radiation effect could modify both the extent of the photoreactivation and the probability of the recovery per unit time. It is concluded that the mathematical approach used here may be useful to reveal some new relationships between the parameters of photoreactivation.

[The influence of cooling rates and medium tonicity on Escherichia coli B/r survival after heating with different lethal temperatures].

Cell thermosensitivity of Escherichia coli B/r increases with the cooling rise, especially in hypertonic conditions after heating at 50, 55 and 60 degrees C. A certain relationship is suggested between the observed phenomenon and the osmotic homeostasis system of microorganisms under condition of thermogenic and tonic stress.

[Effect of a dose rate of chronic low-intensity irradiation with 60Co gamma emission and media tonicity on the dynamics of ageing and dying off in Escherichia coli BS-1]. / Vliianie moshchnosti dozy khronicheskogo nizkointensivnogo gamma-izlucheniia 60Co i tonichnosti sredy na dinamiku stareniia i otmiraniia bakterii Escherichia coli BS-1.

The experimental data on radiation reduction of the dynamics of Escherichia coli BS-1 ageing and dying-off with the increase of intensity of chronic exposure to 60Co gamma-Rays in the range of dose rates from 0.1 to 7.6 x 10(2) microGe/h are presented. This phenomenon takes place only under cell irradiation in isotonic and hypotonic suspension medium.

[Some effects of radiation hormesis for bacterial and yeast cells]. / Nekotorye éffekty radiatsionnogo gormezisa bakterial'nykh i drozhzhevykh kletok.

A comparative study of chronic and acute action of ionizing radiation on the processes of aging and dying off of bacterial and yeast cells was carried out. It was ascertained that chronic action of ionizing radiation, 2-10,000 times exceeded the natural background, resulted in slowing down of aging and dying off of both pro- and eukaryotic cells. A single acute irradiation of yeast also resulted in the retardation of dying off of the yeast cells surviving after irradiation. The data is presented demonstrating a great increase in the survival of yeast cells under their repeated irradiation after recovery from potentially lethal radiation.

[Influence of ionizing radiation of low intensity on the processes of reproduction, aging and dying off of Escherichia coli bacteria]. / Vliianie nizkointensivnogo ioniziruiushchego izlucheniia na protsessy razmnozheniia, stareniia i otmiraniia bakterii Escherichia coli.

The influence of 60Co gamma-ray irradiation of low intensity (0.1-0.4, 0.76 x 10(3) microGy/h) on the processes of reproduction, aging and dying off of E. coli B/r and E. coli BS-1 bacteria have been investigated. It was shown that the reproduction of this bacteria strains was not dependent on the dose rate in the range 0.1-0.4 microGy/h. It was shown in comparison with the irradiated E. coli B/r cells dynamics of the aging and dying off of the irradiated E. coli BS-1 is decreased in the process of prolonged (about 190 days) irradiation with a dose rate of 0.76 x 10(3) microGy/h. It is proposed the relationship between the revealed phenomenon of the decrease in the intensity of the irradiated E. coli BS-1 cell aging and dying and the Vavilov-Cerenkov emission.

[Mechanism of thermoresistance in Escherichia coli cells exposed to temperature elevation]. / O prirode povysheniia termoustoichivosti kletok Escherichia coli v protsesse nagreva.

The influence of media with different osmotic pressure (NaCl water solution) and chloramphenicol (10 micrograms/ml) on the survival, permeability, and survival curve shape of Escherichia coli B/r and E. coli Bs-1 cells, heated up to 50, 52, and 60 degrees C was investigated. As shown, the survival curve of cells heated up to 60 degrees C in isotonic conditions was characterized by exponential shape, while the survival curves of cells heated up to 50 and 52 degrees C consisted of two components characterizing thermosensitive and thermoresistant parts of cell population. Hypertonic conditions of heat at 52 degrees C decreased cell lethality and permeability. In this case, survival curves were characterized by exponential shape. Chloramphenicol was shown to protect against damaging action of heat at 50 degrees C and not to affect the viability of cells heated at 52 and 60 degrees C. It is proposed that the increase of cell thermoresistance with heat dose elevation at 50 and 52 degrees C in isotonic conditions, which is accompanied by the appearance of thermotolerant components on survival curves, may be associated with accommodational cell reactions. The essence of these reactions consists in stabilization of the osmotic cell homeostasis.

[The effect of media tonicity on Escherichia coli resistance to heating with different gradient]. / Vliianie tonichnosti sredy na usto'ichivost' bakteri'i Escherichia coli k nagrevu pri razno'i velichine teplovogo perepada.

The influence of NaCl water solutions and glycerine hypertonic concentration on the survival of bacteria Escherichia coli B/r heated with different values of heat drop was investigated. It was shown that the transfer of cell suspensions from isotonic conditions to media with raised osmotic pressure, preliminarily heated up to 60 degrees C, and the following heating at this temperature inhibited differences in cell sensitivity to heating at different heat drop. Unlike, it was found that the transfer of cell suspensions from isotonic conditions to hypertonic media before and after heating at 60 degrees C increased differences in resistance of these microorganisms to heating at different heat drop. It is proposed that different resistance of bacteria to damaging action of hyperthermia at different heat drop, and a modified influence of hypertonic solutions on these differences may be due to heat induced destabilization of cell osmotic homeostasis. The extent of expression of this destabilization may be determined by a quantitative ratio of osmotic pressure values in the cell-suspension medium system in particular temperature and tonic environmental conditions.

[Osmotic modification of thermal damage in Escherichia coli bacteria at various pH values of the media]. / Osmoticheskaia modifikatsiia termopovrezhdenii bakterii Escherichia coli pri raznykh znacheniiakh pH sredy.

A study was made of the influence of media with different osmotic pressure on cell survival and on optic density of supernatants from Escherichia coli B/r and E. coli Bs-1 cell suspensions heated under different pH values of media. Hyperthermia induced cell death accompanied with the loss of optically active (lambda = 260 nm) material. Both cell damage effects were increased in acid and alkaline conditions, compared to neutral condition of heating. Hypertonic media results in a decrease in thermic cell death and loss of cell substances. Under this condition, the protection influence of high osmotic pressure was seen to increase significantly in acid and alkaline conditions of heating, compared to neutral condition. It has been proposed that a higher thermal damage of microorganisms in acid and alkaline beating conditions and protection influence of hypertonic media, especially expressed in acid and alkaline medium, is caused to a great extent by the status of osmotic cell homeostasis.

[Features of consequences of osmotic modification at different steps of cell heating]. / Osobennosti osmoticheskoi modifikatsii posledstvii razlichnoi stepeni nagreva kletok.

The influence of media with different osmotic pressure (NaCl water solutions) on survival and permeability of Escherichia coli B/r and Escherichia coli Bs-1 cells heated up to 50, 52 and 60 degrees C was investigated. Hypotonic media increased, while hypertonic media, within a certain range of sodium chloride concentrations, decreased the damaging action of heating independently of the temperature. The effectiveness of thermoprotection was seen to increase, and the range of osmolyte concentrations, at which the highest effect of protection takes place, to move markedly towards higher concentrations of NaCl with increase in heating temperature. A certain relationship is suggested between the observed phenomenon and the osmotic homeostasis system of microorganisms under condition of thermogenic and tonic stress.