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Photochemical reactions in cell DNA are induced in various organisms by solar UV radiation and may lead to a series of biological responses to DNA damage, including apoptosis, mutagenesis, and carcinogenesis. The chemical nature and the amount of DNA lesions depend on the wavelength of UV radiation. UV type B (UVB, 290-320 nm) causes two main lesions, cyclobutane pyrimidine dimers (CPDs) and, with a lower yield, pyrimidine (6-4) pyrimidone photoproducts (6-4PPs). Their formation is a result of direct UVB photon absorption by DNA bases. UV type A (UVA, 320-400 nm) induces only cyclobutane dimers, which most likely arise via triplet-triplet energy transfer (TTET) from cell chromophores to DNA thymine bases. UVA is much more effective than UVB in inducing sensitized oxidative DNA lesions, such as single-strand breaks and oxidized bases. Of the latter, 8-oxo-dihydroguanine (8-oxodG) is the most frequent, being produced in several oxidation processes. Many recent studies reported novel, more detailed information about the molecular mechanisms of the photochemical reactions that underlie the formation of various DNA lesions. The information is mostly summarized and analyzed in the review. Special attention is paid to the oxidation reactions that are initiated by reactive oxygen species (ROS) and radicals generated by potential endogenous photosensitizers, such as pterins, riboflavin, protoporphyrin IX, NADH, and melanin. The review discusses the role that specific DNA photoproducts play in genotoxic processes induced in living systems by UV radiation of various wavelengths, including human skin carcinogenesis.

It seems that safety of the impact of the UVA on the skin is associated with insidious identifying of early manifestation of damage and distant consequences of impact on the skin and the whole organism. The imagination of safety of UVA exposure has led to wide spread of radiator of UV rays of range A. This scientific research was devoted to identifying of positive and negative impact of UVA on the skin. The aim of the study was to investigate the morphological and functional state of the guinea pigs' skin under the influence of local fractional UVA radiation. Materials and methods. Studies were conducted on albino guinea pigs that weight 300-350 g. The local fractional regime of exposure was obtained by UV radiator OUFK-03, which generates mainly UVA radiation with the aim of creating the model of exposure in the most similar to real conditions. The shaved area (2x2 cm) of animals' skin (n=6) was exposed for 30 minutes for 5 days. Guinea pigs were located in a distance of 10 centimeters from the source of exposure. Experiments with animals were finished on the 6-th day after exposure. All animals were deduced from the experiment with the help of general anesthesia keeping the principles of bioethics with the aim of investigation of peculiarities of morphological changes of skin. Visible changes in the morphological and functional state of the skin were detected on the 6-th day after irradiation: signs of acute inflammation and a tendency to chronicity of the process, multiple, compared with normal, thickening of the epidermis, degenerative changes in epidermocytes, hyper- and parakeratosis, focal destructive changes in connective tissue fibers in the dermis, which are accompanied by reactive inflammatory processes. Signs of starting reparative processes in proliferative form of functional active fibroblasts and increasing of collagenogenesis at sites of damage of collagen and elastin fibers are market simultaneously. It is considered that the negative effects of UVA in studied regime on the skin, the task of developing of depending actions is to reduce negative UVA impact which will be the aim of our next researches.

The ultraviolet (UV) B-induced damage of the eye surface of experimental animals (rabbits) includes loss of corneal epithelium, apoptosis of keratocytes and stromal edema. These changes are accompanied by clinically and histologically manifested corneal inflammation, neutrophil infiltration, and exudation of the anterior chamber of the eye. According to mass spectrometric analysis, UV-induced corneal damage is associated with pronounced changes in the lipid composition of tears, including a decrease in the amount of arachidonic acid and prostaglandin E2 and an increase in the concentrations of prostaglandin D2 and its derivative 15d-PGJ2. In addition, it is accompanied by an alteration in the levels of hydroxyeicosate tetraenic acid derivatives, namely upregulation of 12-HETE and downregulation of 5-HETE. The revealed changes indicate the activation of metabolic pathways involving 5-lipoxygenase, 12-lipoxygenase, cyclooxygenase 1 and 2, and prostaglandin-D-synthase. These findings contribute to understanding mechanisms of UV-induced keratitis and point on feasibility of selective anti-inflammatory therapy for improving corneal regeneration after iatrogenic UV damage.

We investigated the mechanism of UV-radiation influence on trypsin in free and immobilized (on chitosan) states. The catalytic activity of free enzyme under the action of UV-light is subjected to changes to a greater extent than that of the immobilized one. We assume that the photoprotection effect of chitosan is caused for the following reasons: firstly, through interactaction with trypsin molecules chitosan forms a more photoresistant complex as compared to the native protein; secondly, chitosan probably binds the active photopro- ducts of a free radical nature, thus preventing oxidation (destruction) of several amino acids of the enzyme under its UV-radiation.

MicroRNAs belong to small non-coding RNA which regulate gene expression via mRNA degradation or translation inhibition. MicroRNAs are active modulators of gene expression in the skin caused by exogenous factors including ultraviolet irradiation. These effects are realized by targeting transcription factors and signaling systems components. Changes in microRNAs levels started to register in a few hours after exposure to ultraviolet irradiation, wich confirms the presence of an effective fast processes in the scin cells that modulate the functional status of microRNAs. The reported recently ability of microRNAs to be transported by exosomes may be related to systemic effects of ultraviolet irradiation that include the altered immune response and systemic inflammatory reaction. Understanding these processes is important because of the possibility of purposeful influence on the expression and activity of a microRNA that may have implications for diagnosis and therapy of photodermatosis and malignant skin tumors.

Biological effect of a visible light depends on extend of its property to penetrate into the tissues: the greater is a wavelength the more is an effect of a radiation. An impact of a visible light on the skin is evident by wave and quantum effects. Quanta of a visible radiation carry more energy than infrared radiation, although an influence of such radiation on the skin is produced by the light spectrum on the boarder of the ultraviolet and the infrared rays and is manifested by thermal and chemical effects. It is determined that large doses of a visible light (405-436 nm) can cause skin erythema. At this time, the ratio of generation of free radicals in the skin during an exposure to the ultraviolet and the visible light range from 67-33% respectively. Visible rays of 400-500 nm length of wave cause an increase of the concentration of oxygen's active form and mutation of DNA and proteins in the skin. The urticaria in 4-18% of young people induced by photodermatosis is described. As a result of a direct exposure to sunlight photosensitive eczema is more common in elderly. Special place holds a hereditary disease - porphyria, caused by a visible light. In recent years, dermatologists widely use phototherapy. The method uses polychromatic, non-coherent (wavelength of 515-1200 nm) pulsating beam. During phototherapy/light treatment a patient is being exposed to sunlight or bright artificial light. Sources of visible light are lasers, LEDs and fluorescent lamps which have the full range of a visible light. Phototherapy is used in the treatment of acne vulgaris, seasonal affective disorders, depression, psoriasis, eczema and neurodermities. LED of the red and near infrared range also is characterized by the therapeutic effect. They have an ability to influence cromatophores and enhance ATP synthesis in mitochondria. To speed up the healing of wounds and stimulate hair growth light sources of a weak intensity are used. The light of blue-green spectrum is widely used for the treatment of neonatal hyperbilirubinemy. A photodynamic therapy takes a special place. The third generation of the blue (410 nm), yellow (595 nm) and red photosensitors are used. Photodynamic therapy is used in the treatment of cancer as well.

The hypothesis on connection between various germination rates of seeds that are not in dormancy with their epigenetic polymorphism has been checked. It was shown that seedlings which were characterized with different germination rates had different methylation patterns of transcribed and satellite DNA. Different cytogenetic characteristics and their changes were observed under UV-C irradiation as well.

The effect of a mixture of N-acetylcarnosine and D-pantethine (1 : 1, m/m) on UV-A induced cataract in rats was studied. It is shown that instillation of a 5% mixture into the eyes or intraperitoneal injections (25 or 150 mg/kg) inhibit the formation of cataracts, starting from 82nd day of the experiment (p < 0.03), after which the protective effect of the mixture significantly increases (p = 0.0003). UV-A irradiation significantly (p < 0.01) increased the content of water-insoluble proteins in the lens. The use of the mixture of N-Acetylcarnosine and D-pantethine prevented (p < 0.001) an increase in the content of water-insoluble proteins caused by UV-A irradiation. Gel permeation chromatography data showed that, in the control group, water insoluble proteins consist of 3 fractions (40 kDa, 100 - 200 kDa, and1000 kDa). UV-A irradiation reduced the amount of protein in fraction 1 and increases the amount of protein in the fractions 2 and 3. The use of the mixture of N-acetylcarnosine and D-pantethine reduced the effects of UV-A light. The authors attribute the effect of the N-acetylcarnosine and D-pantethine mixture to their chaperone-like properties.

On the basis of original clinical research a rare case of bilateral retinal damage due to tanning lamp radiation exposure is presented. Along with significant decrease of visual acuity and light sensitivity of central visual field as well as color vision impairment, bilateral macular dystrophy was found during an ophthalmoscopy and confirmed by optical coherent tomography and fluorescent angiography. Intensive retinoprotective, vascular, and antioxidant therapy was effective and led to functional improvement and stabilization of the pathologic process associated with photochemical retinal damage. A brief review of literature compares mechanisms of retinal damage by either short or long-wave near visible radiation.

A comparative experimental study of biomicroscopic appearance of lenses in cataracts of different genesis (age-related, ultraviolet and other radiation-induced or combined) has been performed on animals (mice). It is shown that identical lens opacification can be provoked by aging (endogenous factor), as well as ultraviolet and other radiation exposure (exogenous physical factors). The only differential sign is the severity of the damage. These factors can be arranged in the following ascending order by their damaging ability: aging --> ultraviolet --> gamma rays --> gamma rays + ultraviolet. Anti-cataract effect of a chaperone-like combined drug (N-acetylcarnosin and D-pantetin) has been studied in vivo on a "prolonged" model of induced cataract in rats. The use of the combined drug (1:1 mixture of the two peptides) in the form of ocular instillations and intraperitoneal injections helped slowing the progression of the ultraviolet-induced cataract in vivo.

UV and gamma irradiation of barley seedlings induces an increase in the number of various pathologies in the male reproductive system of plants. The majority of cytological abnormalities are rather nonspecific. The main type of the observed pathologies of microsporogenesis is cytomixis, whose activation correlates with a callose hypersecretion in microsporocyte walls. A negative correlation between cytomixis and the sterility of microspores (in the case of gamma irradiation) or the sterility of mature pollen grains (in the case of UV-B irradiation) is revealed. It is supposed that cytomixis represents a kind of a premeiotic cell selection in plants characterized by an intraorganismic genetic heterogeneity (mosaics). The novelty of the idea is that the cytopathology that accompanies cytomixis is considered as a mechanism of the induced death of genetically imbalanced or nonrepairable cells, which is intended to keep the fertility of a male reproductive system. The activation of this mechanism has a threshold character.

Our study has shown that the damaging effect of hydroxylated fullerene C60(OH)25 on mouse peritoneal macrophage plasma membranes increased when we enlarged the concentration of fullerene in the incubation media (from 0.005 to 0.5 mg/ml), the incubation temperature (from 22 degrees C to 37 degrees C) and the time of incubation (from 30 to 90 min). In conditions of the H2O2-induced membrane damage, fullerene was observed to intensify the H2O2-induced damaging effect at a concentration of 0.05 mg/ml and reduce it at a concentration of 0.5 mg/ml. In conditions of the UV-induced membrane damage, it was discovered that the damaging effect of UV increased when C60(OH)25 nanoparticles were added to the incubation media before irradiation and decreased when they were added after irradiation. Eventual participation of ROS in damaging effects of C60(OH)25 was discussed.

Comparative study of lens biomicroscopy in cataract of different etiology (senile, ultraviolet, radioactive and combined ultraviolet- radioactive exposure) is performed in experiment on animals (mice). Lens opacification pattern was showed to be similar in aging as an endogenous factor and ultraviolet (UV) and radioactive exposure as exogenous physical factors. Specificity of these factors is expressed in degree of damage only. Depending on damaging potential the factors may be arranged in a following way (in increasing manner): aging, ultraviolet irradiation, gamma-irradiation, gamma+UV-irradiation.

Microscopic lens changes are studied in mice (F1C57B1XCBA) depending on age and after ultraviolet (UV), gamma-irradiation and their combination. In all animals compared to young 3-months animals nonspecific changes due to aging were revealed: microvacuoles in cytoplasm of fiber cells, flattening of epithelial cells and nuclei fragmentation, swelling and confluence of cortical layer cells in anterior and posterior subcapsular zones. In epithelial cells the following changes were noted: nuclei polymorphism, cavities in a cell layer formation of multilayered structures of fibroblast-like cells and cell desquamation. Degree of nuclei vacuolization was significantly lower in groups with gamma- and gamma+UV-irradiation but higher in a group of UV exposure. The number of cells per unit area was significantly decreased in a group of gamma-irradiation after 7 and 10 months of exposure. Aging and UV exposure caused decrease of nuclei area, whereas affect of gamma-irradiation depended on proliferative capacity of cells: size of central cells increased and of peripheral cells reduced. Specific changes were not revealed for any of the factors.

Using differential electrophoresis protein composition of lens major proteins in hybrid mice F1 (C57B1XCBA) with cataracts of different etiology (senile, ultraviolet, radioactive and combined ultraviolet-radioactive exposure) was studied Changes that may be specific for cataract caused by aging, ultraviolet and/or gamma-irradiation were not revealed in water-soluble and water-insoluble protein fractions.

The review covers the literature proving that ROS formation in aging overbalances the antioxidant defense system potential of the skin structure (horny layer, epidermis and dermis). It has been shown that ROS are involved in the pathogenesis of inflammatory processes and allergic responses in the skin. The role of ROS and antioxidant systems in the cell-mediated responses associated with the MAP kinase activity in the skin is discussed. Special attention is paid to the ultraviolet irradiation exposure, which accounts for its genotoxic, immunosuppressive and carcinogenic effects on the skin.

The paper gives data on the positive and negative effects of human exposure to ultraviolet radiation (UVR). It provides the hygienic characteristics of solaria used to produce an artificial tan. This device has been found to present a high health risk to its users. There are considerable problems in the hygienic assessment of this type of exposure. The ways of solving the arising problems in developing the metrological monitoring of UVR and compiling a document regulating the sanitary-and-epidemiological surveillance of solaria are defined.

Antistress effect of extracellular peptides on UV irradiated yeast of different phylogenetic groups was studied. Yeast from different ecotopes and taxonomic groups exposed to UV radiation of a lethal intensity showed a protective effect and reactivating effect with participation of extracellular peptides. The highest protective activity was found in peptide reactivation factors (RFs) of bakery yeast-Saccharomyces cerevisiae, Kluyveromyces fragilis, and Candida utilis; the highest reactivating activity was exhibited by factors of the above-mentioned cultures and Debariomyces hansenii. Cross-protective and reactivating effects of RFs of yeast belonging to different taxonomic groups were demonstrated. Cross-protection increased two to three times after preexposure of reactivation factors to UV light (activation) in contrast to their reactivating effect.

Four randomized groups of male mice F1 (C57Black/CBA) were investigated: a) UV-irraidated (UV-A, 15 min daily during 9 months, dose 5.6 + 1.2 W/m2), b) gamma-rays irradiated (2 Gy), single, c) influence for combination of UV- and gamma-rays treatment, d) aging. The lens opacities were measured on 7th and 10th month. The expert method based on six grade scale was used for cataract measure. On 7th month the median of lens opacities were Aging group = 0; UV-irradiated group = 2.5; gamma-irradiated group = 4.75; gamma- and UV-irradiated group = 6.0. The difference between all groups was significant (p < 0.004, Kruskall-Wallis ANOVA test). The Conover post hock test has shown the significant difference for all comparison pairs (p < 0.002) with the exception of UV-irradiated group, gamma-irradiated group, gamma- and UV-irradiated group. On 10th month the lens opacities were strongly increased: Aging group = 2.5; UV-irradiated group = 5.0; gamma-irradiated group = 6.5; gamma- and UV-irradiated group = 7.5 (median). The difference between groups was significant (p < 0.0001, Kruskall-Wallis ANOVA test). The Conover post hock test has shown the significant difference for all comparison pairs (p <0.003) with the exception ofthe UV-irradiated group and gamma-irradiated group. The formation of the specific lens opacities for any group was not found. Morphology and protein composition have been investigated on 10th month. The results of morphological changes study show destructive and degenerative impairments of capsule, epithelium cells and lens fibers. However, no specific changes related to some particular actions have been found. In addition, there were no specific changes of protein composition of both water-soluble and water-insoluble fractions estimated with Differential Gel Electrophoresis technique. Obtained data mean that aging, UV-treatment, and gamma-radiation causes the similar changes of lens. It was supposed that UV-treatment or/and gamma-radiation act as an aging factor on the lens.

In this work, we present the evidences of the involvement of Rdh54 in coordination of DNA repair by several pathways. Previously, we isolated rdh54-29 point mutation demonstrating unique properties different from the full deletion of RDH54 gene. Epistatic interaction between rdh54-29 and apn1delta mutations discloses the function of Rdh54p in the process of base excision repair. However, rdh54-29 mutant exhibits sensitivity to many DNA damaging agents including UV light, methylmethanesulphonate and nitrous acid. Such pleiotrophic effect of rdh54-29 mutation may indicate the role of Rdh54p in the regulation of different DNA repair systems. To check this hypothesis, we estimated the effect of rdh54-29 mutation on recombination and mutagenesis. The data confirm the involvement of Rdh54p in coordination of different DNA repair systems including mutagenic and recombinagenic pathways as well as nucleotide excision repair. Rdh54p presumably operates via chromatin remodulation at the site of damage rendering DNA accessible to the DNA repair enzymes.

Ultraviolet radiation with a wavelength of 300-400 nm is characteristic of sunlight at the earth surface and causes DNA damage mediated by energy transfer to O2 with the transformation of the latter in the singlet state. In connection with this, scavengers of reactive oxygen species (ROSs) are potential protectors against the genotoxic effect of this kind of radiation. It was found that the methylene blue dye at doses differing by several orders of magnitude from those that are toxic for humans is able to suppress completely the SOS response induced by UV with a wavelength of 300--400 nm in Escherichia coli.

The results of the investigations of photoaggregation of the main eye lens proteins alpha-, beta- and gamma-crystallins and the model protein carbonic anhydrase in response to pulsed irradiation by a XeCI laser at 308 nm in the wide range of pulse energy densities (w) and pulse repetition rates (F) have been reviewed. A nonlinear dependence of aggregation efficiency on the values of w, F, and the concentration of protein solution was found. A theoretical model that qualitatively describes the experimental results was developed. The aggregation of N-amino-arm truncated beta A3-crystallin was analyzed. It was found that the loss of the N-amino-arm as a result of mutation or eye lens aging increases the probability of UV-induced beta-crystallin aggregation, thereby increasing the predisposition of eye lens to senile cataract. The influence of some short-chain peptides on the aggregation efficiency of beta-crystallin and beta-crystallin in solution with alpha-crystallin was investigated. Based on the results obtained, a combination of peptides (called "a new preparation") was found that most effectively delays the crystallin aggregation. The preparation has been probed on experimental animals. The trials showed that the preparation increases the delay in the development of UV-induced cataract in rats. The possibility of designing a drug for the prophylaxis of the development of cataract in humans based on this preparation is discussed.

Aggregation ofcrystallins, the lens proteins, is one of the basic stages of cataract formation. Among the protein aggregation models used to study the molecular mechanisms of the initial stages of lenticular opacity, UV-induced aggregation of betaL-crystallin is most close to the in vivo conditions. The carnosine derivative N-acetyl carnosine has been shown to be effective in inhibiting the UV-induced aggregation of betaL-crystallin. Examination of the accumulation kinetics of carbonyl groups in betaL-crystallin under UV irradiation has indicated that neither carnosine nor N-acetyl carnosine fails to affect this parameter--an indicator of oxidative protein damage. By taking into account also the fact that N-acetyl carnosine is not an antioxidant, it can be believed that the molecular mechanism of action of this compound on UV-induced aggregation of betaL is unassociated with its antioxidative properties. The authors hypothesize that the molecular chaperon-like properties similar to those of alpha-crystallin underlie the mechanism of action of the acetyl derivative carnosine. The prospects for searching anticataract agents of a new chaperon-like class are discussed.

There is a potential of therapeutic action on certain stages of caractogenesis, in particular on the aggregation of water-soluble proteins of cytoplasmic lens fiber cells, giving rise to insoluble protein complexes. The effect of a combined preparation (N-acetyl carnosine and D-patethine), acting by the chaperon-like mechanism, was studied in vivo on a prolonged rat model of UV-induced cataract. The use of the combined preparation consisting of a mixture of peptides of N-acetyl carnosine and D-patethine in a ratio of 1:1 as ocular instillations and intraperitoneal injections could slow down the development of UV-induced cataract in vivo. Pathomorphological studies suggest that the combined preparation has a protective effect on lens tissue when the rat model of UV-induced cataract is employed.

UV-induced aggregation of betaL-crystallin, one of the major lens proteins, was studied under its pulse radiation with XeCl laser at a wavelength of 308 nm. Unlike the in vitro tested dipeptides L-carnosine, N-acetyl carnosine, D-panthetine, and particularly their combination, the so-called new chaperon was demonstrated to slow down the rate of photoaggregatin of beta-crystallin. The new chaperon, a mixture of D-pathethine and N-acetyl carnosine was ascertained to protect a mixture of betaL- and alpha-crystallins from UV-induced aggregation to a greater extent than D-pathethine or N-acetyl carnosine used alone. An effective drug based on the new chaperon may be designed for the prevention of cataract in sight.

To study the mechanisms of action of new-generation anticataract drugs, it is necessary to have an accessible and adequate model of age-related cataract. A model of UV-induced cataract is pathogenetically closest to that of age-related cataract. A prolonged rat model of UV-induced cataract developing within 10 months is proposed; the clinical features of UV-induced cataract have been established at different stages of its development. A moderate homogeneous cloud-like lenticular opacity was observed at the end of the experiment; a less pronounced homogeneous opacity was seen in the anterior and posterior cortical layers. Cataract development was assessed by the appraisal method using the developed rat lenticular transparency scale, as well as by microdensitometry of biomicroscopic lenticular optical sections. Within the proposed model, the pathomorphological lenticular changes are largely similar to the histological pattern of age-related cataract.

Nucleotide excision repair is one of the most important pathways of DNA repair in eukaryotic cells. Defects of this system lead to serious diseases including certain kinds of cancer. Nucleotide excision repair is able to remove a wide range of the structurally diverse DNA damages such as UV induced pyrimidine dimers, bulky chemical adducts arising under the action of carcinogenic compounds or chemotherapeutical drugs on cellular DNA. A broad substrate specificity of this repair pathway is related to the main intriguing question that is the mechanism of damage recognition by the protein complex in the context of the large excess of undamaged DNA. This review is detailed on the key stage of nucleotide excision repair--the recognition of a lesion in DNA, which is still most debated. We have considered the main models of a primary damage recognition and preincision complex formation that have been suggested by the leading groups in this field. Data presented allow to suggest the model of sequential loading of the proteins of reparative complex on damage DNA as the most reasonable.

The article presents characteristics of ultraviolet rays sources used for prevention, treatment and for tanning. Difficulties in hygienic evaluation of goods are revealed. The authors defined ways to solve this problem--specify metrological support for supervision, create regulation document on sanitary and hygienic evaluation of ultraviolet rays sources.

It was shown that macrophage irradiation in 4.6 J/cm2 (lambda(max) = 306 nm) dose leads to small quantity of damaged cells in cell population, which doesn't change substantially during 60 min of incubation in darkness. So as detergent digitonin treatment (without irradiation) in 3 mkg/ml concentration doesn't lead to substantial cell damage. Also the result of combined influence of UV-irradiation and digitonin added after irradiation, 15 min before the damaged cells counting, has been got. It was shown that macrophage incubation for 15 minutes leads to cell damaging twice as much sum of UV (4.6 J/cm2) and digitonin (3 mkg/ml) damaging. However the level of cell damaging obtained 30 minutes later after finishing of irradiation doesn't exceed the sum of separate effects of this factors. Further increase of postradiation time leads to synergic effect again.

Data on 373 patients treated for cutaneous melanoma were evaluated to test a hypothesis whether there is a correlation between mechanism of protection from ultraviolet radiation and gender. Cutaneous melanoma of the extremities was identified in 63.2% of females and 26.6% of males (p<0.001) versus 26.1% and 54.0%, respectively, with tumors of the trunk (p<0.001). Five-year survival in women was 80.8% versus 76.9% in men in the first group (p>0.2) and 59.5% and 50.0% , respectively, in the second one (p>0.2). Hence, the correlation was concerned with tumor site rather than gender.

The 3H-thymidine incorporation in human lymphocytes of healthy donors induced by UVC radiation under doses 0.0008-60 J/m2 was investigated. It was shown that the incorporation of 3H-thymidine increases under doses in interval 0.1-20 and is constant under doses higher than 20 J/m2. Under doses in interval 0.006-0.03 J/m2 near a half of all samples had the level of incorporation increased in comparison with control samples. We connect the presence, absence or variability of this effect with individual peculiarities of cells and with different activity of cell subpopulations that are different on morphological and physiological characteristics. The hypothesis about the role of this factor in the influence of low doses of pathogenic agents (UVC and X-radiation, chemical compounds) on human lymphocytes is discussed.

The effect of UV radiation in vitro on the level of ascorbate, SH-groups and glutathione reductase activity in the soluble fraction of bovine eye lens was studied. UV-Irradiation increased NADPH-oxidoreductase activity, the level of ascorbate oxidation and decreased the content of SH-groups and activity of glutathione reductase. Significant activation of the NADPH-oxidoreductase activity in the presence of ascorbate and Cu2+ was observed after UV-irradiation. It is suggested that ascorbate may play an important role in the UV-induced lens pathology.

Exposure of a small skin area of volunteers to UV light in 1 minimal erythemal dose is accompanied by rapid appearance in the circulating blood of soluble factors able to restore proliferation of X-ray-damaged autologous lymphocytes, to decrease frequency of chromosome breaks, and to stimulate unscheduled DNA synthesis. The appearance of such an activity in the blood can be also induced without skin irradiation. For this, one volume of a directly UV-irradiated blood is to be mixed in vitro with 10-fold volumes of intact blood, thus modeling the in vivo situation, when a small amount of transcutaneously UV-irradiated blood mixes with intact blood in the circulation. It has been found that the platelet-derived growth factor and epidermal growth factor, added at physiological concentrations to the culture medium, decrease chromosome break frequency in X-damaged cells.

The study of a biological effect of ultraviolet, ultrahigh frequency and gamma-radiation, as well as combinations of these, on the functional status of the sheep body systems has made it possible to evaluate the sensitivity of a body exposed to these factors and its adaptive potentials. The pattern of variations in the body systems when a combined EMR is applied depends on to which extent one or another factor dominates the others. It is however possible that the effect of the leading factor is modified by that of a less severe radiation, energy characteristics of which differ from those of the dominating factor.

Prophylactic peroral use of MIGI-K preparation (products of acid hydrolysis of mussels meat) largely or completely prevented intensification of lipoperoxidation and depression of antioxidative systems (superoxide dismutase, glutathione peroxidase, nonprotein thiols, lipoantioxidants) in skin and liver of UV-irradiated rats.

Radiation measuring on the work places of operators in command and control installations proved that environment parameters depending on electronic display functioning are in line with the regulations' requirements. Nevertheless the operator health estimates show that the problem of personnel security still exists. The authors recommend some measures to improve the situation.

Correlations between effective UVR doses for induction of skin erythema, premature aging and cancer, immunosuppression, vitamin D photobiosynthesis and cataract on the one hand and various ethnic signs, sex, age and metabolic states of organism on the other were considered. Individual UV sensitivity by all criteria mentioned with the exception of immunosuppression and cataract is conditioned by specificity of melanin and DNA metabolism, and risk of skin cancer incidence besides that depends of immune system state. Values of risk factors for UVR effects mentioned incidence in individuals of different sex and age with various ethnic and metabolic conditions are presented.

Information on possible human health-changes associated with stratosphere ozone depletion and amplification factor (% increase of the stick rate by 1% decrease of ozone) values for acute (erythema, keratitis, cataract, immunosuppression) and chronic (skin cancer, cataract) effects of natural UV-radiation was analysed. Amplification factor (AF) values for acute UV-effects increase with degree of ozone depletion. For degrees less than 12.5% they are independent of latitude and equal to 1.9 for erythema, 1.3-1.5 for keratitis, 1.7-2.3 for cataract and 0.9-1.1 for immunosuppression. AF values for incidence of non-melanoma skin cancer are independent of age, higher in males than females, and higher for squamous cell carcinoma, than for basal cell carcinoma. Their optimal estimations for whites equal to 2.7 for basal cell and 4.6 for squamous cell carcinoma. AF values for incidence of cutaneous malignant melanoma range between 1 and 2, for melanoma mortality--between 0.3 and 2. AF values for incidence of cataract range between 0.3 and 1.2 with optimal estimations between 0.6 and 0.8. Prognosis of non-melanoma skin cancer and cataract incidences, melanoma mortality and economic loss for different scenarios of stratosphere ozone depletion are presented.

UVR effects on human health are considered. The critical organs for UVR are skin, eye, and the immune system. In the skin, UVR can induce erythema, tanning, vitamin D photosynthesis, premature aging, and cancer. UVR has a specific immunosuppressive effect on the skin secondary to altered lymphoid cells function. It results in inhibition of the anti-neoplastic activity and suppression of contact hypersensitivity and delayed hypersensitivity to various antigens. UV can induce photokeratoconjunctivitis and play an active role in etiology of cataracts, corneal and retinal degeneration, pterigium and uveal melanoma. Action spectra and biologically effective doses for the effects are presented. Measured UV energy spectra naturally occurring at the Earth's surface and in space were used to calculate the effective time of UV exposure to produce these effects. Data obtained and modulation of the UV effects by other space flight factors are discussed. Quantitative analysis of maximum permissible UV levels in the production area established in Russia, USA, and the Netherlands was performed. As a result, substantive differences in the approaches of these countries to setting limits and permissible ranges were stated. Applicability of the UV limits to regulation of natural UV exposures is considered.

Investigation of the action of mid-frequency ultraviolet radiation (302 nm) on isolated lymphocytes of mice spleen pointed out that intracellular pH of lymphocytes starts decreasing from 0.3 J/cm2. Dose rise above 2.5 J/cm2 increases the number of cells with damaged plasmatic membrane within the lymphocyte population and aggravates the ability of cells to accumulate fluorescein fluorochrome as a product of intracellular fluorescein diacetate hydrolysis.

Quantitative analysis of threshold limit levels of UV-irradiation in the workroom environment established in USA, Netherlands and Russia was made. Comparison of its results with modern information about effective doses and action spectra of UV-radiation biological action allowed to reveal essential differences in the approach to rate setting and in some cases presence of internal contradictions and exceeding of threshold limit levels of UV irradiation above biologically effective values. The possibility of workroom UV standards utilisation for regulation of nature UV-radiation exposures was considered.

Hairless mice of strain HRS were exposed to vertical UV-B-irradiation (280-320 nm) at daily doses of 1 or 2 kJ/m2 (biologically effective doses 200 and 400 J/m2) five days a week for 13 and 6 weeks. As the length of exposure increased, the abundance of automicroflora of the dorsal skin first decreased, then exceeded the control value, was normalized, and remained at the normal level until the end of the experiment. The rates of effect appearance and disappearance, just as its amplitude, increased with the daily doses. No changes were found in resistance to staphylococcal alpha-toxin after its post-irradiation intraperitoneal injection.