[Molecular nature of regulating cell division and differentiation in an organism].

A short review of the investigations of contactins, tissue-specific compounds providing intercellular contacts, which were discovered by the authors in the 60s, is presented.

[The carcinogen urethane induces high-amplitudes circaseptan variations in target tissues and disrupts the rhythm of cell count in lymphoid organs].

The presence of tumor is accompanied by biological rhythms disturbance both in damaged (target) organ, and in nondamaged systems. As discoordination of biorhythms is sometimes one of the causes of pathologic states, we have investigated, which changes in system of about 7-day duration (circaseptan) biorhythms preceded the tumor appearance. The model of lung carcinogenesis, induced by single dose (0.

[The ultrastructure of the hepatocyte contacts in inbred mice at different ages].

Correlation was revealed between the ultrastructure of hepatocyte contacts and force F, essential for the rupture of the junction between the cell, seized with a microneedle, and the tissue specimen, in mice of the highly cancerous CBA line and of the low cancerous C57BL line at the age of 1.7 and 15 months. The most considerable ultrastructural differences in the cell contacts were found in the above mice at the age of 1 month, when the signs of carcinogenic process cannot yet been seen.

[Stability threshold of a tissue system].

Studies of changes in the cells adhesive force during spontaneous and induced cancerogenesis, as well as under the effect of cancerogenesis promotors permits to reveal the cells adhesion forces critical values which separate tissue states stable and unstable to blastomogenesis. These data are analysed proceeding from the concepts on generalized cooperative transitions in the membranes and their role in the control over biological systems. It is taken into account that the membranes and cytoskeleton elements are the most important systems of the tissue mechanical integration, and phase transitions proceeding in them must be reflected in the tissue mechanical properties.

[Action of carcinogenesis promoters on the adhesive force of cells in the liver, lung and thyroid gland in rats and mice].

The short-term effects of the carcinogenesis promoters on the adhesive force of cells are compared with the data from literature on their ability to exert a promoter action on the carcinogenesis development in the same organs during prolonged introduction after an initiator. The ability of substances to decrease the adhesive force in the tissue below the resistance threshold is established to correlate with its promoter activity. The coincidence of tissue specificity of both effects and active doses of substances is observed.

[Strength of intercellular adhesion in gastric cancer].

Intercellular adhesion strength was measured after Koman in various parts of primary tumor and lymph node metastases of 43 patients with stage III-IV gastric cancer. Also, a fraction of low-adhesion (less than 0.20 mg) cells was assayed.

[Effect of tissue-specific proliferation inhibitors on the level of mitotic activity and cell adhesion in disordered innervation].

In the work there was studied the influence of hepatic chalones on the level of mitotic activity and on the degree of adhesion of hepatocytes after the violation of parasympathetic and sympathetic innervation under the physiological conditions of liver function and in regenerating organ. Some definite regularities were revealed in the change of the power of linkage among the cells of liver parenchyma after the disturbance of its innervation and chalones affected. Significant differences in the effect of the influence of tissue inhibitors of proliferation on the process of regeneration in liver, which has intact or disturbed innervation were discovered.

[Disturbance of the mechanical integration of cells in tissues in the occurrence of spontaneous hepatomas and lung adenomas in mice].

The force (F) and coefficient of stability (Cst) of cell cohesion were measured in the liver parenchyma from CBA mice and in alveolar epithelium of the lung from A mice (genetically susceptible to spontaneous tumours) aged 1 to 13 months. Coefficients of F and Cst magnitude variation increase, while those of mean Cst decrease in animals aged 9 months in the both tissues. In spontaneous tumours F and Cst decrease more considerably.

[A system of mechanical integration of tissue as the basic regulation system at the tissue level of organization].

A new concept for tissue--level regulation system is proposed. This concept is based on three groups of facts: 1) possibility of regulation of tissue behavior by fields of mechanical tension; 2) correlation between changes in mechanical properties of the tissue and its biological behavior at different stages of blastomogenesis; 3) regulative role of tissue--specific (endo- and exo)-genic factors which influence directly the mechanical properties of the tissue. This system is called the system of the mechanical integration of the tissue.

[Effect of contactin from the lung on the cellular proliferative activity of the alveolar wall].

The influence of contactine from rat lung on DNA synthesis in pulmonary alveolar tissue of A mice was studied in vivo. Two-fold decrease in the total index of pulmonary tissue cells labeled with 3H-thymidine was observed 7-24 hours following the contactine injection. The inhibition of DNA syntheses was observed at the same concentrations at which a cell cohesion increases.

[Changes in the intercellular contacts of hepatocytes in the ontogeny of inbred mouse strains with a high (CBA) and low (C57BL) frequency of spontaneous hepatomas].

Some parameters of cellular contacts between hepatocytes were studied in ontogenesis of the inbred mouse lines with the high (CBA) and low (C57BL) frequency of spontaneous hepatomas. In both the lines the force of intercellular linkage of the hepatocytes drops down by the end of the animal's life. But in the C57BL mice this characteristics increases sharply between the 5th and 10th days after birth, whereas in the CBA mice no such increase is observed.

[Mechanical properties of the intercellular contacts of hepatocytes of inbred strains of mice and mice predisposed to spontaneous hepatomas].

The adhesiveness of hepatocytes was evaluated in 7 inbred mice and compared to the reported data on the incidence of spontaneous hepatomas. The adhesiveness was shown to be significantly less in mice predisposed to spontaneous hepatomas as compared to more resistant species. Electron microscopy revealed the presence of little and highly adhesive areas (HAA) in nonspecialized regions of hepatocytic contacts, this presence being shown by elevated (20-30 mm Hg) hydrostatic pressure in the liver blood bed.

[Effect of hepatic adhesion factor, contactin, on the mechanical properties of ultrastructural elements of hepatocyte contact].

Injection of isotonic fluid under heightened pressure 20--30 mm of Hg into the bed of the liver reveals inhomogeneity of the mechanical properties of the simple junction of heptacytes: the zone where the divergence of the contact surfaces is observed is interrupted by highly adhesive regions (HAR) where the normal distance between the membranes is preserved. The adhesive factor acts as an organizer of the inhomogeneity of the simple junction: when it is introduced in vivo, new HAR appear in the simple junction. On account of contact-tropic activity of adhesive factor we termed it--contactin.

[Tissue-specific inhibition of DNA synthesis by contactins, factors that possess tissue-specific adhesive activity].

Highly purified factors extracted from the liver and lungs of adult rats, tissue-specifically increasing the stability of intercellular contacts and of cell plasma membranes to mechanical disruption, were found to decrease, in the same manner, the labeling index (LI) in explants of the embryonic tissue of mice. The comparison of the action of these factors on the LI, and on mechanical properties of the tissue has shown that the latter effect is manifested earlier than the former one.

[Effect of the tissue-specific lung adhesive factor on the urethane induction of pulmonary adenomas in mice].

The effect of adhesive factor (AF), urethane and their combination on the mechanical properties of lung tissue (this effect was assessed by the nuclei isolation during a standard dispersion procedure) and on adenoma induction was studied. As shown, the AF doses eliminating the primary action of urethane on the mechanical properties of the tissue significantly decreased the incidence of adenomas. High AF doses producing a contrary effect on the mechanical properties of the tissue failed to eliminate the primary effect of urethane and did not decrease the number of adenomas induced by urethane.

[Tissue-specific depression of DNA synthesis by calcium salt-free liver and lung extracts that are able to increase the stability of cell linkage in the tissue].

The macromolecular fraction of Ca-free salt extracts (Ca-FSE) removed from lungs and liver of adult rats, mice and fishes inhibits DNA synthesis in the embryonic tissue. The effect of Ca-FSE is tissue-specific rather than species-specific. Ca-FSE was earlier reported to increase with the same specificity the tissue stability to mechanical disruption.