It is demonstrated in this study that a decrease in the rate of irreversible age-related thymus atrophy affects animal longevity. It was observed that the life span of rats may be increased by thymus transplantation from young animals into the immune privileged regions of ageing rats. It has been shown that the season of birth has effects on animal longevity, namely, rats born in the spring–summer period live shorter lives than those born in autumn or winter.

A statistically significant difference in the cumulative survival of Wistar rats born in different seasons has been shown: animals born in late November–early December had an average lifespan 24.8% longer, a minimum lifespan 14.3% longer, and a maximum lifespan 20.7% longer in comparison with animals born in April. Transplantation of thymus tissue into the immune privileged anterior chamber of the eye in animals born both in November and April has shown a geroprotective effect.

Purpose: The aim of this study was evaluating changes in the photosensitizer fluorescence in vivo in the radiation-induced damage area in comparison of intact areas with a simultaneous assessment of changes both in blood parameters and in histological data. Materials and methods: The study was conducted in white outbred SHK mice (n = 21). Their right hindlimbs were irradiated with a dose of 25 Gy after the intraperitoneal injections of photosensitizer 'Photosens'. Fluorescence intensity was traced in vivo by a laser diagnostic system for seven weeks. Simultaneously, histological examination of the damaged areas and blood tests were performed. Results: An increased intensity of the laser-induced fluorescence of the photosensitizer 'Photosens' in the damaged areas, compared to the intact symmetrical ones was observed. Laboratory blood tests and histological examination showed changes that may indicate the occurrence of inflammation. Conclusion: Enhanced intensity of the exogenous fluorescence of the photosensitizer in the radiation-induced inflammation of noncancerous tissues was observed. The obtained results may potentially affect an interpretation of the results of intraoperative tumors navigation that have been previously irradiated and can be used for selection of an individualized dose fractionation algorithm in radiology.

Laser fluorescence spectroscopy (LFS) is widely used in medicine. Today, oncology and oncosurgery are considered as the most promising fields of its application. It is known that cancerous tissues are able to accumulate different porphyrins, both endogenous and exogenous, in enhanced amount due to increased metabolism in cancerous cells. So, LFS can be used in vivo for detection of malignant tumours as well as for real-time intraoperative imaging or diagnostics at a photodynamic therapy. One of the reason of the enhanced accumulation of porphyrins in tissues is a chronic hypoxia. Therefore, it was hypothesized, that LFS could also be used for diagnosis of local inflammation in tissues. Recently, some indirect data confirming the hypothesis was obtained when observed inflammation due to invasion of external substances into tissues. This study proves the hypothesis in a direct experiment with animals and laboratory tests. Enhanced fluorescence intensity of the exogenous photosensitizer was found in inflamed tissues. The direct association between intensity of the fluorescence, histological characteristics and blood test results was shown. It was found that the registered fluorescence signal correlates with neutrophil counts in blood of tested animals. It proves that LFS could be an effective tool for registration of local inflammation.

Background: Development of the new methods of treatment of primary male hypogonadism is an urgent medical problem. Its solution requires a suitable experimental model of the disease. Aim: The creation of new experimental model of primary male hypogonadism. Materials and methods: The study was conducted on the male Wistar rats, hypogonadism was modeled by temporary ligation of the distal part of the spermatic cord. Results: It was shown that three-day ligation of the spermatic cord led to persistent disturbance of the testosterone-producing and reproductive functions. These manifestations were reversible at shorter duration of the exposure. Conclusion: The created model of primary male hypogonadism is characterized by the persistent testosterone-producing and reproductive functions disturbance, technical availability, non-toxicity to the other organs and systems. Availability of the model provides new opportunities for the development of approaches to treating diseases of the reproductive organs in men.

Background: Laser fluorescence spectroscopy (LFS) is widely used in various medical areas, oncology being the most known of them. In general, the LFS is used for in vivo diagnostics of tumors. Recent studies have shown that this method could be used for diagnostics of local inflammation, induced by thermal or mechanical injury. It is of interest if LFS could be used for assessment of soft biological tissue injury caused by radiation exposure. Aim: To study fluorescence of an exogenous photosensitizer and its changes over time in the radiation injury area by LFS method in vivo. Materials and methods: The experiment was done in 12 outbred SHK mice whose right hind limbs were irradiated using a gamma-therapy device ROKUS-AM (source, 60Co, at dose of 15 Gy). Before irradiation, the photosensitizer Photosens was administered to all animals intraperitoneally at dose of 2.5 mg/kg. For 21 days fluorescence was assessed in vivo with a laser diagnostic system LAKK-M in the “fluorescence” operation mode, with an excitation wavelength of 635 nm. At days 7 and 21, tissue samples from the irradiated areas of the model animals were studied histologically and differential blood cell counts were assessed simultaneously. Results: The LFS method showed an increase in the accumulation of the photosensitizer in the affected area, compared to an intact contralateral area, with higher signal intensity from the irradiated limb. The changes in the fluorescence signal from the affected over time had two characteristic peaks at days 3 and 14, probably reflecting the stage of local radiation injury. Conclusion: The use of LFS with an exogenous photosensitizer has a potential for a personalized assessment of radiation reactions in radiology.

In vivo laser-induced fluorescence spectroscopy (LIFS) is primarily used in oncology for the diagnosis of malignant tumors. This paper provides background for and describes experiments modeling nonmalignant local hypoxia and inflammation. LIFS techniques were used to assess the dynamics of induced fluorescence from endogenous porphyrins in the first case and the Photosens exogenous photosensitizer in the second case. In both cases, the fluorescence intensity was observed to be higher in the pathological area than in an intact area. This provides a strong impetus for taking a second look at the use of LIFS in oncology and also provides the foundation for a promising in vivo diagnosis method for ischemic hypoxia and inflammatory processes in areas other than oncology.

The age-dependent, lifespan-extending effect of grafting allogenic thymic tissue into a recipient’s immune-privileged anterior chamber of eye was studied. Grafting thymic tissues from young to old animals was shown to lead to a significant extension of the recipient’s average and maximum lifespans.

A novel method for recording the aggressive behavior in newly formed hierarchic communities has been developed. A temporal and age-related dynamics of the accidental thymus involution in mammals has been studied.