FACTORS INFLUENCING RESULTS OF SURGICAL TREATMENT OF METATARSALGIA AND THEIR PROGNOSTIC VALUE.

Objective - to determine the prognostic value of factors that affect the long-term result of surgical treatment of metatarsalgia, to develop a system for predicting the results of surgical treatment of metatarsalgia. A prospective trial of long-term results of surgical treatment of 172 patients with metatarsalgia was conducted from 2000 to 2019. Two study groups were formed: the core study group comprising of 107 patients who underwent Weil-osteotomy, metatarsals proximal osteotomy. The control group consisted of 65 patients who underwent another surgical treatment (metatarsophalangeal resection arthroplasty, surgery of capsular-ligamentous and tendon apparatus of metatarsophalangeal joints, as well as the surgical therapy intended to remove only hammer 2-4 toes deformities). Clinical, instrumental and statistical (correlation-regression analysis) research methods were used. The factors that influenced the end result of treatment were identified. The statistically significant influence of age, sex, BMI < 25, "index minus" and hammer 2-4 toes on the prevalence of positive treatment results were determined. The estimation of the informative nature of the presented factors for the probability of achieving positive results of treatment, the calculation of the prognostic coefficients and their sum were determined. The system for predicting treatment results of metatarsalgia involves the possibility of obtaining a high, medium and low probability of a positive result when applying surgical treatment. The long-term result of surgical treatment of metatarsalgia under the heads of 2 - 4 metatarsals depends on age and factor "hammer 2-4 toes". A high prognostic evaluation of a successful treatment outcome should be expected with a total prognosis of + 6 to +16; a total estimate of prognostic coefficients from + 6 to +16 determines the average probability of positive treatment results; the sum of the prognostic coefficients from - 10 to - 2 determines the low probability of achieving positive treatment results.

Rho overexpression leads to mitosis-associated detachment of cells from epithelial sheets: a link to the mechanism of cancer dissemination.

Dissemination of neoplastic cells from the primary tumor (invasion and metastasis) is a fundamentally dangerous step in multistage carcinogenesis. Recent evidence suggests that Rho GTPase-mediated signaling is linked to dissemination of cells from several different types of human tumors. The Rho family of proteins is typically associated with the regulation of cytoskeletal activity, including actin assembly, microtubule dynamics, and myosin II-dependent contractility of the actin-rich cortex. We examined the effect of overexpression of constitutively active RhoA on islands and monolayers of epithelial cells. Although newly plated cells initially formed small spread islands, there was also a significant population of cells that detached from the substrate, floated in the medium, and then could reattach to the substrate to form new colonies. Detachment of cells from transfected epithelial islands or monolayers occurred in correlation to the plane of cytokinesis after misorientation of the mitotic spindle axis. We suggest that these alterations result from Rho-induced increase of contractility of the cortex of dividing cells, which, during cytokinesis, produces a cell that has budded out of an existing layer of cells. Cell division-mediated detachment of cells from tissue structures may be an important mechanism of tumor dissemination and metastasis.

Rho-dependent formation of epithelial "leader" cells during wound healing.

The motile behavior of epithelial cells located at the edge of a large wound in a monolayer of cultured cells was analyzed. The initial cellular response is alignment of the edge with an accompanying formation of tangential marginal actin bundles within individual cells positioned along the wound edge. Later, coherent out-growths of cell masses occur by the formation of special "leader" cells at the tops of outgrowths and "follower" cells along the sides. Leader cells exhibit profound cytoskeletal reorganization, including disassembly of marginal bundles, the realignment of actin filament bundles, and penetration of microtubules into highly active lamellae. Additionally, cell-cell contacts acquire radial geometry indicative of increased contractile tension. Interestingly, leader cells acquire a cytoskeletal organization and motility typical of fibroblasts. IAR-2 cultures stably transfected with a dominant-negative mutant of RhoA or treated with Rho-kinase inhibitor Y-27632 transformed most edge cells into leader-like cells. Alternatively, transfection of cells with constitutively active RhoA suppressed formation of leaders. Thus, expansion of the epithelial sheet involves functional differentiation into two distinct types of edge cells. The transition between these two patterns is controlled by Rho activity, which in turn controls the dynamic distribution and activity of actin filament bundles, myosin II, and microtubules.

[Cytoskeletal mechanisms of heterocellular contact formation]. / Tsitoskeletnye mekhanizmy formirovaniia geterokletochnykh kontaktov.

We studied the interaction of two main cell types, epitheliocytes and fibroblasts, in a mixed culture. Heterotypic cells had a different cytoskeleton organization and expressed different cell adhesion molecules, cadherins. In spite of this, when the cells contacted in the mixed cultures, a heterophilic contact was formed and the actin cytoskeleton of an epitheliocyte at the site of contact was reorganized: the marginal actin bundle was decomposed and actin structures were formed in its place, that were typical for the fibroblast lamella. No changes were observed in the actin organization of the fibroblast. In architecture, the heterophilic adhesion contacts resembled the contacts between fibroblasts. Both heterophilic and homophilic contacts were transient, rather than constant structures. The formation of heterophilic contacts in mixed cultures can serve as a model of formation of a tissue system consisting of epithelium and mesenchyme.

Mechanisms of polarization of the shape of fibroblasts and epitheliocytes: Separation of the roles of microtubules and Rho-dependent actin-myosin contractility.

Cultured fibroblasts possess a characteristic polarized phenotype manifested by an elongate cell body with an anterior lamella whose cell edge is divided into protrusion-forming and inactive zones. Disruption of the fibroblast microtubule cytoskeleton leads to an increase in Rho-dependent acto-myosin contractile activity and concomitant loss of structural polarity. The functional relationship of myosin-driven contractile activity to loss of fibroblast anterior-posterior polarity is unknown. To dissect the roles of microtubule assembly and of Rho-dependent contractility on structural polarization of cells, polarized fibroblasts and nonpolarized epitheliocytes were treated with the microtubule-depolymerizing drug, nocodazole, and/or the Rho kinase inhibitor, Y-27632. Fibroblasts incubated with Y-27632 increased their degree of polarization by developing a highly elongate cell body with multiple narrow processes extended from the edges of the cell. Treatment of fibroblasts with nocodazole, alone or in combination with Rho kinase inhibitor, produced discoid or polygonal cells having broad, flattened lamellae that did not form long lamellar extensions. Single cultured epitheliocytes of the IAR-2 line do not display anterior-posterior polarization. When treated with Y-27632, the cells acquired a polarized, elongate shape with narrow protrusions and wide lamellas. Nocodazole alone or in combination with Y-27632 did not change the discoid shape of epitheliocytes, however treatment with Y-27632 produced thinning of the lamellar cytoplasm. We conclude that microtubules provide the necessary framework for polarization of fibroblasts and epitheliocytes, whereas Rho-regulated contractility modulates the degree of polarization of fibroblasts and completely inhibits polarization in epitheliocytes.

Contact interactions between epitheliocytes and fibroblasts: formation of heterotypic cadherin-containing adhesion sites is accompanied by local cytoskeletal reorganization.

Contact interactions between different cell types play a number of important roles in development, for example in cell sorting, tissue organization, and ordered migration of cells. The nature of such heterocellular interactions, in contrast to interactions between cells of the same type, remains largely unknown. In this report, we present experimental data examining the dynamics of heterocellular interactions between epitheliocytes and fibroblasts, which express different cadherin cell adhesion molecules and possess different actin cytoskeletal organizations. Our analysis revealed two striking features of heterocellular contact. First, the active free edge of an epitheliocyte reorganizes its actin cytoskeleton after making contact with a fibroblast. Upon contact with the leading edge of a fibroblast, epitheliocytes disassemble their marginal bundle of actin filaments and reassemble actin filaments into a geometric organization more typical of a fibroblast lamella. Second, epitheliocytes and fibroblasts form cell--cell adhesion structures that have an irregular organization and are associated with components of cell adhesion complexes. The structural organization of these adhesions is more closely related to the type of contacts formed between fibroblasts rather than to those between epitheliocytes. Heterotypic epithelio-fibroblastic contacts, like homotypic contacts between fibroblasts, are transient and do not lead to formation of stable contact interactions. We suggest that heterocellular contact interactions in culture may be regarded as models of how tissue systems consisting of epithelia and mesenchyme interact and become organized in vivo.

Phenotypic mixing of vesicular stomatitis virus and D-type oncornavirus.

After mixed infection of cells with vesicular stomatitis virus (VSV, thermolabile mutant tl 17) and oncornavirus type D, phenotypically mixed virions are formed containing the VSV genome and oncornavirus and VSV envelope. The virions are thermostable and have serologic characteristics of both viruses.