[Changes in Elemental and Isotopic Composition Accompanying Larval Growth and Metamorphosis of the Moor Frog]

A variety of early ontogenetic events of anuran species (growth, structural and biochemical diversification, metamorphosis) offers a unique opportunity to evaluate the effectiveness and application limits of mass spectrometry method for the analysis of metabolic and transformation events in developing organisms. The dynamics of relative carbon and nitrogen contents and stable isotopes of these elements during larval development in the period of metamorphosis climax and after its conclusion in moor frog specimens developing in their natural habitat and in vitro on a referent diet are traced. A decrease in C/N ratio and enrichment of the tissues with heavy stable isotopes of carbon and nitrogen during embryonal and larval development (prior to the beginning of independent feeding) indicates the increase in the portion and variety of proteins, accompanied by consumption of yolk lipids. The relative nitrogen content increase and C/N ratio decreases with the growth and development of independently feeding tadpoles, which indicates surpassing increase of the portion of proteins in tissues. In growing tadpoles, the rates of tissue renewal in general and rates of protein metabolism in particular affect the kinetics of changes of tissue isotope composition, which approaches isotope composition of the consumed food. A decrease in С/N ratio in the bodies of metamorphs during mass tissue decomposition is indicative of continuing reconstruction of larval organs and growth of anlage of definitive organs. Significant increase of C/N ratio and depletion of liver samples by heavy carbon isotopes are associated with intensive synthesis and reservation of lipids within the organ. Strong enrichment of metamorphs’ tissues with heavy nitrogen isotope indicates the substitution of ammoniotelic type of nitrogen metabolism by urotelic type. Decrease in C/N ratio and enrichment of tissues by heavy carbon isotope may be connected to intensive oxidation of lipids, which supports the growing energy costs of terrestrial underyearlings. Relative contents of heavy nitrogen isotope in the tissues of underyearlings does not change compared to the tissues of metamorphs.

Stem Cells in the Treatment of InsulinDependent Diabetes Mellitus

Diabetes affects over 350 million people worldwide, with the figure projected to rise to nearly 500 million over the next 20 years, according to the World Health Organization. Insulin-dependent diabetes mellitus (type 1 diabetes) is an endocrine disorder caused by an autoimmune reaction that destroys insulin-producing -cells in the pancreas, which leads to insulin deficiency. Administration of exogenous insulin remains at the moment the treatment mainstay. This approach helps to regulate blood glucose levels and significantly increases the life expectancy of patients. However, type 1 diabetes is accompanied by long-term complications associated with the systemic nature of the disease and metabolic abnormalities having a profound impact on health. Of greater impact would be a therapeutic approach which would overcome these limitations by better control of blood glucose levels and prevention of acute and chronic complications. The current efforts in the field of regenerative medicine are aimed at finding such an approach. In this review, we discuss the time-honored technique of donor islets of Langerhans transplantation. We also focus on the use of pluripotent stem and committed cells and cellular reprogramming. The molecular mechanisms of pancreatic differentiation are highlighted. Much attention is devoted to the methods of grafts delivery and to the materials used during its creation.

Stem Cells in the Treatment of Insulin-Dependent Diabetes Mellitus

Diabetes affects over 350 million people worldwide, with the figure projected to rise to nearly 500 million over the next 20 years, according to the World Health Organization. Insulin-dependent diabetes mellitus (type 1 diabetes) is an endocrine disorder caused by an autoimmune reaction that destroys insulin-producing β-cells in the pancreas, which leads to insulin deficiency. Administration of exogenous insulin remains at the moment the treatment mainstay. This approach helps to regulate blood glucose levels and significantly increases the life expectancy of patients. However, type 1 diabetes is accompanied by long-term complications associated with the systemic nature of the disease and metabolic abnormalities having a profound impact on health. Of greater impact would be a therapeutic approach which would overcome these limitations by better control of blood glucose levels and prevention of acute and chronic complications. The current efforts in the field of regenerative medicine are aimed at finding such an approach. In this review, we discuss the time-honored technique of donor islets of Langerhans transplantation. We also focus on the use of pluripotent stem and committed cells and cellular reprogramming. The molecular mechanisms of pancreatic differentiation are highlighted. Much attention is devoted to the methods of grafts delivery and to the materials used during its creation.

The Use of Cellular Technologies in Treatment of Liver Pathologies

Cell techniques find increasing application in modern clinical practice. The II and III phases of clinical trials are already under way for various cellular products used for the restoration of the functions of the cornea, larynx, skin, etc. However, the obtainment of functional cell types specific to different organs and tissues still remains a subject of laboratory research. Liver is one of the most important organs; the problems and prospects of cellular therapy for liver pathologies are currently being actively studied. Cellular therapy of liver pathologies is a complex multistage process requiring a thorough understanding of the molecular mechanisms occurring in liver cells during differentiation and regeneration. An analysis of the current cellular therapy for liver pathologies is presented, the use of various cell types is described, the main molecular mechanisms of hepatocyte differentiation are analyzed, and the challenges and prospects of cell therapy for liver disorders are discussed in this review.

The use of cellular technologies in treatment of liver pathologies

Cell techniques find increasing application in modern clinical practice. The II and III phases of clinical trials are already under way for various cellular products used for the restoration of the functions of the cornea, larynx, skin, etc. However, the obtainment of functional cell types specific to different organs and tissues still remains a subject of laboratory research. Liver is one of the most important organs; the problems and prospects of cellular therapy for liver pathologies are currently being actively studied. Cellular therapy of liver pathologies is a complex multistage process requiring a thorough understanding of the molecular mechanisms occurring in liver cells during differentiation and regeneration. An analysis of the current cellular therapy for liver pathologies is presented, the use of various cell types is described, the main molecular mechanisms of hepatocyte differentiation are analyzed, and the challenges and prospects of cell therapy for liver disorders are discussed in this review.

[Effect of x-ray irradiation on the physiological reactions of dermal melanophores in tadpoles of the common frog]

The effect of X-ray irradiation (700 R) on the physiological reactions of the dermal melanophores in Rana temporaria L. tadpoles of 20-22d stages of development has been studied. It has been shown that the irradiation of the aggregated dermal melanophores does not change the physiological state. As compared these data with previous ones a conclusion of high selective susceptibility to the X-ray irradiation of the tadpoles' epidermal melanophores has been drawn.

[Relations between pigmentation of the cornea and the number of epidermal melanophores in Rana temporaria L. larvae]

The dynamics of the external cornea pigmentation in Rana temporaria L. larvae at the 22d developmental stage have been studied under conditions favourable for various course of certain morphological reactions in the pigment system. The cornea together with the surrounding skin is transferred on the dorsal surface of the larva body, and the piece of the dorsal surface skin is put instead of the cornea removed. When using the reciprocal transplantation method and preserving the organism's integrity (without disturbing melanocyte-stimulating source--namely, the hypophysis, and melatonine sources--namely, the pineal gland and the lateral eyes) the corneal pigmentation is observed on the background of perfect morphological reactions in the pigment system, while the larvae are maintained on the dark and light substrates, that is at various density of the pigment cells (120 larvae have been used). The pigmentation dynamics have been studied from the 6th up to the 20th day in total preparations. The epidermal melanophores density is estimated in 4 areas of each preparation. The melanin amount is estimated by means of the electron paramagnetic resonance-spectrometry according to the contents of free radicals expressed in relative units. A direct proportional dependence between the significantly higher melanin contents (1.5-fold) and a significantly quicker (1.5-fold) process of the corneal pigmentation is revealed, that agrees with an increasing number of the pigment cells per one unit of the body surface in the larvae maintained on the dark substrate. In the larvae maintained on the light substrate, the dependence is of a reverse character. It is probable that the factors forcing the pigmented cells, at cultivation the neural crest cells in vitro to reject from each other, affect the pigmentation of the larval cornea in vivo. If it is the case, the processes specific for the embryonal period, transgress during the cornea pigmentation at the larval stages of development.

[Corneal pigmentation after removal of the eye in Rana temporaria L. larvae]

Pigmentation of the cornea has been studied in the Rana temporaria larvae at the 22d-27th stages of development macroscopically (total corneal preparations with the surrounding skin) and microscopically. Dynamics of the pigment cells transfer that fill the transparent cornea is compared to the histological rearrangement of the latter. The corneal pigmentation is demonstrated to occur with a constant velosity and is well described by means of the linear regression equation. At initial stages of transformation, the corneal pigmentation overtakes the histological processes, then the two processes run in parallel and only towards the metamorphosis period the corneal histological changes slightly overtake the pigmentation process. As a whole, the pigment cells arrangement demonstrates the transformation degree of the external corneal into the skin after the eye has been extirpated. A suggestion is made explaining the necessity of a constant inducing retinal influence on the skin in Anura larvae.