[Role of ultraviolet radiation and vitamin D metabolism in medical care during space flights]. / Rol ultrafioletovoi radiatsii i obmena vitamina D pri meditsinskom obespechenii kosmicheskikh poletov.

Data on the development of ultraviolet (UV) deficiency in the cosmonauts are analyzed, possible ways to optimize UV radiation and alimentary stearin supply in order to prevent vitamin D deficiency and to correct the changes in phosphorous-calcium metabolism are discussed.

[The duration of the aftereffects of UV-irradiation of man in conditions of UV-insufficiency]. / O dlitel'nosti posledeistviia UF-oblucheniia cheloveka v usloviiakh UF-nedostatochnosti.

The purpose of the present investigation was to study the aftereffect of UV-B-irradiation applied during 10 or 20 sessions. The biological effect and aftereffect duration of UV-B-irradiation of the upper body of 9 healthy volunteers (residents of the city of Moscow and its suburbs) were evaluated in autumn and winter. During UV-irradiation in the range 220-280, 280-320, or 320-400 nm the flux density was 0.035, 1.75, or 0.65 W/m2, respectively. Group 1 subjects (5 men) were exposed to UV-B-irradiation 10 times (once with 0.5, 0.6, 0.75, 0.9, 1.1, 1.35, 1.65 MED and three times with 2.0 MED) and Group 2 subjects (4 men) were exposed to UV-B-irradiation 20 times (twice with 0.5, 0.75, 1.0, 1.25, 1.5, 1.75 MED and eight times with 2 MED). The sessions were arranged every other day. The exposure produced a beneficial effect on the human body: skin sensitivity decreased, resistance of skin capillaries increased, Ca metabolism normalized, blood 25 (OH) D grew. The trend of responses was similar after 10 and 20 sessions; however, 20 sessions caused a longer-term aftereffect. In relation to space programs, it is concluded that UV-irradiation can be applied on the ground before short-term flights (less than 4 months) and in space during longer-term flights (greater than 4 months).

[Effect of simulated weightlessness on calcium metabolism and the condition of bone tissue in experimental animals]. / Vliianie model'noi nevesomosti na obmen kal'tsiia i sostoianie kostnoi tkani éksperimental'nykh zhivotnykh.

Male rats of the Wistar strain were for 40 days exposed to hypokinesia and hypodynamia. After exposure bone biochemical, physical, chemical, morphological and strength parameters were investigated. Both simulation studies led to changes in calcium and phosphorus metabolism but the nature of bone changes was different. It is concluded that the efficacy of drugs used as countermeasures in animal simulation experiments should be assessed by both exposures, viz. small size cages and suspension, because they reproduce different mechanisms of potential bone lesions in microgravity. It is also inferred that various countermeasures should be used in combination to yield the best results.

[Effect of active metabolites of vitamin D 3 on the status of rat bone tissue in various experimental models of hypokinesia]. / Vliianie aktivnykh metabolitov vitamina D 3 na sostoianie kostnoi tkani krys pri razlichnykh éksperimenta'lnykh modelakh gipokinezii.

Rats were for 6 weeks either kept in small cages or suspended. The caged rats showed hypocalcemia and lowered active transport of calcium in the intestine and no changes of PTH in blood. Femoral bone measurements in these rats revealed reduced density and content of calcium and phosphorus in proximal epiphyses, slight increase of these parameters in diaphyses and lack of changes in distal epiphyses. The suspended rats exhibited normocalcemia, noticeable but insignificant increase of PTH and calcium absorption as well as decreased density and content of calcium and phosphorus in distal epiphyses and their slight increase in diaphyses. Administration of active vitamin D3 metabolites led to an increase of bone mineral density and content only in those femur compartments where hypokinesia-induced changes were seen. It is concluded that during hypokinesia bone disorders are predominantly produced by local factors that may increase bone sensitivity to systemic influences.

[Prevention of ultraviolet insufficiency after a long stay by humans in an isolation chamber]. / Profilaktika ul'trafioletovoi nedostatochnosti pri dlitel'nom prebyvanii cheloveka v izolirovannom pomeshchenii.

The purpose of this study was to investigate biological effects of various regimens of ultraviolet irradiation in order to prevent UV insufficiency in men long kept in an enclosure. The subjects were kept for 60 days under artificial illumination in a Moscow laboratory in winter time. Two different regimens of UV irradiation were used and compared: 20 exposures at a dose of 0.75 MED and 20 exposures at incremental doses from 0.5 to 2 or 3 MED. Before and after 10 and 20 exposures (with medium-range radiation being predominant) the skin state, vitamin and mineral metabolism, and cytotoxicity of natural killers were investigated. The experimental observations allowed the conclusion that prophylaxis of UV insufficiency in men long kept in an enclosure can best be provided by UV irradiation at an incremental dose up to 2 MED. During this exposure skin sensitivity to UV radiation decreased, the content of vitamins D, A, E and that of Ca, P, Cu grew, and cytotoxicity of natural killers lightly increased. UV irradiation at a dose of 0.75 MED proved inadequate and that at a dose of 3 MED induced signs of excessive irradiation.

[Study of the activity of various systems of neurohumoral body regulation and ways of its correction in an arid area]. / Izuchenie aktivnosti nekotorykh sistem neirogumoral'noi reguliatsii organizma u putei ee korrektsii v usloviiakh aridnoi zony.

The sympatho-adrenal system, i.e. its hormonal and mediator components, were examined in test subjects who made a 23-day expedition across a desert. The activity of the system was modified using food supplements: whey protein concentrate (50 g) and polyvitamins (Komplivit). It was found that in the arid area the hormonal and mediator components of the sympatho-adrenal system were stimulated. The stimulation degree was reduced by the food supplements which can be used to help the human body get adapted to an arid environment.

[Comparative study of the effect of 1,25 dihydroxyvitamin D3 and 24,25-dihydroxyvitamin D3 on calcium homeostasis and bone tissue state in rats during hypokinesia]. / Sravnitel'noe izuchenie vliianiia 1,25-dioksivitamina D3 i 24,25-dioksivitamina D3 na gomeostaz kal'tsiia i sostoianie kostnoi tkani u krys pri gipokinezii.

Preventive administration of vitamin D3 active metabolites 1.25(OH)2D3 and 24.25(OH)2D3 into growing rats, kept under conditions of long-term hard hypokinesia, normalized Ca metabolism and the state of bone tissue depending on the preparations dose and their combination. 1.25(OH)2D3 at a dose of 0.03 microgram per an animal daily augmented effectively the Ca absorption in small intestine, corrected hypocalcemia, increased slightly the bone tissue density and the Ca and P content in the tissue as well as it elevated the volume of spongiosa, width of the epiphysial growth plate (EGP) and the amount of osteoclasts. After an increase of the metabolite dose up to 0.15 microgram hypercalcemia, hyperphosphatemia, intensive resorption of bone tissue, distinct increase in the osteoclasts content and ectopic calcification were observed. Administration of 1.35(OH)2D3 and 24.25(OH)2D3 combination (0.03 microgram and 0.25 or 1.25 micrograms, respectively) or only 24.25(OH)2D3 at a dose of 1.25 micrograms caused a restoration of Ca absorption in intestine and of its level in blood as well as mineral composition, density of bone tissue, volume of primary and secondary spongiosa were normalized, while the EGP width and amount of osteoclasts remained decreased. Synergic effect of 1.25(OH)2D3 and 24.25(OH)2D3 in rats appears to depend on their various functions in regulation of Ca metabolism, in development and remodelation of bone tissue, thus indicating that these metabolites of vitamin D3 should be used simultaneously under conditions of hypokinesia for prophylactic purposes.

[Calcium absorption in the small intestine in rats during hypokinesia]. / Vsasyvanie kal'tsiia v tonkoi kishke krys pri gipokinezii.

The method of averted and non-averted segments was used to assess calcium absorption in the small intestine of adult and young rats with hypokinesia. A certain decrease in the active (by 13.8%) and more manifest diminution of the total (by 26.3%) calcium transport was established in adult rats after 4 weeks of hypokinesia. In young rats a significant lowering of the active calcium transport was already noted after 1 week of hypokinesia, however, age-dependent shifts in the process were more significant than those induced by hypokinesia. Changes in the calcium-regulating hormones are considered as a possible cause of decreased calcium absorption in the intestine in relation to hypokinesia and age.

[Vitamin allowance of cosmonauts during preflight training and after completing short space flights]. / Obespechennost' vitaminami kosmonavtov v period predpoletnoi podgotovki i posle zaversheniia kratkovremennykh kosmicheskikh poletov.

Supply of the main and doubling crews of cosmonauts with vitamins C, A, D, E, B1, B2, B6, PP, and B12, folic acid and carotinoids was studied during training and after the completion of short-term space flights (from 4 to 13 days). As the result of the investigation conducted during the intensive training, 1 month before the space flight some cases of certain vitamins deficiency were revealed. Administration of additional vitamins during 2 weeks before the flight led to a rise in the cosmonauts' supply with vitamins. The findings obtained after the short-term space flights evidence an intensive metabolization of vitamins and increased vitamin requirements during this period.

[Effect of different doses of ultraviolet radiation on vitamin provision to the human body]. / Vliianie razlichnykh doz ul'trafioletovogo oblucheniia na obespechennost' organizma cheloveka vitaminami.

Exposure of healthy adults to prophylactic doses of UV-radiation in the medium- and long wavelength spectrum improved metabolism of vitamins A, E and D and increased their content in the body. UV-irradiation even in prophylactic doses increased ascorbic acid requirements. Excessive UV-irradiation produced an adverse effect on the vitamin content. However, the vitamin concentration in blood was not significantly decreased. This can be explained by the adaptation of the human body to UV-irradiation upon a continuous increase of its dosage.

[Effects of diets including an active vitamin D 3 metabolite and different contents of calcium and phosphorus on the state of blood free amino acids in hypokinetic rats]. / Vliianie diet s aktivnym metabolitom vitamina D 3 i razlichnym soderzhaniem kal'tsiia i fosfora na sostav svobodynykh aminokislot krovi krys pri gipokinezii.

Some aspects of amino acid metabolism in rats exposed to 30 days of hypokinesia were explored. The animals were placed on the diets with varying Ca/P ratio, containing 24, 25-dihydroxycholecalciferol (24, 25 (OH)2)D3, an active vitamin D3 metabolite. It was demonstrated that high consumption of phosphorus brought about an appreciable reduction in the blood amino acid pool, thus aggravating the body response characteristic for hypokinesia. The use of 24, 25 (OH)2D3 promoted the recovery of the amino acid status of hypokinetic rat blood, while the optimization of the Ca and P content in the diet was absolutely indispensable.