Reproducibility and relation to specific and non-specific anti-tumor resistance of the tumor "sneaking through" phenomenon.

The reproducibility and immunological specificity of the tumor "sneaking through" phenomenon and enhancement of tumor growth were studied in syngeneic and random-bred Syrian hamsters by means of a quantitative modification of the transplantation test. After primary challenge the phenomenon was neither observed in normal animals nor in animals effectively immunized against tumor. However, it was regularly observed in some "immune" animals after secondary challenge. In primary challenge of animals "sneaking through" phenomenon was most often observed in animals pretreated with large doses of heat-inactivated tumor cells. This characteristic could not be transferred with serum of pretreated animals. In contrast to specific tumor immunity, the "sneaking through" pbenomenon appeared to be immunologically non-specific. This was observed in cross-transplantation tests with tumor cells bearing different TSTAs. Thus, TSTA is not an inducer and apparently not a target for a response leading to enhancement of tumor growth in pretreated hamsters. Experiments demonstrating enhanced tumor growth in pretreated animals at the same time demonstrate two other possibly more essential findings: (1) normal animals are naturally resistant to transplantation of 1 to about 1 x 10(3) (or more) tumor cells; and (2) this resistance can be totally abrogated by the pretreatment of normal animals with tumor cell preparations. The preliminary data demonstrate that abrogation of natural anti-tumor resistance in adult hamsters subsequently inoculated with SV40 leads to rapid development of primary tumors in such animals. The development of specific anti-tumor immune response in animals treated with inactivated tumor cell preparations was also studied. Significant non-specific inhibition of sponse in Syrian hamsters treated with inactivated syngeneic tumor cells was observed. The data obtained are considered to demonstrate two anti-tumor defense systems in the animal, i.e., non-specific natural resistance and specific anti-tumor immunity. The first seems to be responsible for elimination of low numbers of tumor cells in the normal organism and also to be esseitial for effective induction and functioning of the specific anti-tumor immunity.     

CLearance of Pseudomonas aeruginosa from the lungs in experimental burn trauma

Experiments carried out in rats demonstrated that a burn of degree III of 20% of the body surface disturbs considerably the process of lung clearance from bacterial dissemination (5 million bodies of Pseudomonas pyocyanea). Not only decreased but even negative clearance may be observed indicating multiplication of the bacteria in pulmonary tissues for the first 3 days after burn, and intratracheal infection of the animals. Reduced general antibacterial resistance as a result of burn facilitates rapid penetration of P. pyocyanea into the lymph nodes, blood, kidneys, liver, spleen where it is found 6 hours after infection.     

The role of glycosphingolipids in natural immunity. Gangliosides modulate the cytotoxicity of natural killer cells

Incubation of gangliosides with natural killer (NK) cells from various sources was found to inhibit NK activity in vitro whereas incubation of the same gangliosides with human or mouse lymphoma cells prior to their exposure to NK effectors resulted in a sharp increase in the NK sensitivity of the tumor cells. These effects depended on the oligosaccharide structure of the gangliosides and on the origin of the NK effector cells. The lysis of YAC cells by mouse splenocytes or of MOLT-4 cells by NK cells isolated from the peripheral blood of Syrian hamsters or humans was inhibited most strongly by pre-incubation of the effector cells with gangliosides GM3 and GD3 which are known to be elevated in the serum of tumor-bearing hosts. It is suggested that target cell-associated gangliosides may function as target structures recognized by NK cells while serum gangliosides may contribute to the inhibition of NK cells during tumor development and thus help the tumor to escape NK surveillance.     

The use of mathematical modelling in improving the orthodontic treatment of end defects of the dental arches

Mathematical modelling allowed to use specially designed software package for calculation of the necessary number of variants of dimensions of denture carcass while planning the orthodontic treatment. This could be done for each patient individually, thus ensuring the correct choice of orthodontic technique to replace the end defects of the dentition.     

Diagnosis and treatment of large-cell anaplastic lymphoma in children

Thirty eight children with large-cell anaplastic lymphomas have been recently treated at the Pediatric Department of Malignant Lymphomas, Russian Cancer Research Center, Russian Academy of Medical Sciences. Cytoimmunological studies have revealed that 24 patients had 4 types of cellular elements of large-cell anaplastic lymphoma: Kil(+), Kil(+)B, B-cell, and T-cell lymphomas in 11, 2, 8, and 3 children, respectively. Intensive chemotherapy was performed in relation to the immunophenotype.