Clinical and Morphological Aspects in Assessing the Safety of OSPL-502 with Repeated Dose Administration.

Background: OSPL-502 is a new potential medicinal drug which stimulates a cognitive function. It is necessary to reveal clinical manifestations of its general toxic effect and determine organs that are most heavily affected by this pharmacological substance.

Aims: To describe and estimate clinical and histopathological changes in the organism of experimental animals in response to the repeated administration of pharmacological substance OSPL-502.

[Epidermal thickness and keratinocyte proliferation after cutaneous application of vitamin D].

Using light microscopy, morphometry and immunohistochemistry, the epidermis of 72 male and female rats was examined 1 day and 1 month after the completion of daily cutaneous applications of vitamin D3-containing composition lasting for two weeks. It was found that vitamin D3 causes a statistically significant reduction in the thickness of interfollicular epidermis and in the number of Ki-67 positive keratinocytes. The identified effects persisted for 1 month after the last application of the preparation.

[The state of keratinocytes of interfollicular epidermis after 13-cis-retinoic acid application (immunocytochemical analysis)].

Immunocytochemical methods were used to study the population of keratinocytes of interfollicular epidermis in rats under the conditions of morphogenesis, experimentally modified by an application of 13-cis-retinoic acid (0.025% and 0.05% solutions for two weeks).

[Morphogenetic aspect of the influence of purified birch tar on skin].

Changes of the histological structure of rat's skin were studied two weeks following the daily applications of native birch tar and of purified birch tar, devoid of the components that could be potentially dangerous for humans. The morphometric investigations were performed with the use of computer technologies on the apparatus-programme complex (DiaMorph, Russia). It has been established that the main morphological manifestations of specific dermatotropic activity of birch tar in the present experiment included: epidermal hypertrophy, hyperkeratosis, stimulation of the activity of all dermal cellular elements, intensification of blood supply, reduction of sebaceous glands.