Search PubMed⌕ Search

Biomedical subjects

J Doroszewski

Publications and source records attributed to J Doroszewski.

At least 19 recordsLinked to original sources
PubMed1989

Adhesive and motile properties of Lewis lung carcinoma LL2 lines.

The cell substrate adhesion of the Lewis lung carcinoma in vitro maintained sublines (LL2 basic line, WGA-resistant LL2-8, and Aleuria aurantia-resistant LL2-AAA) has been studied by a hydrodynamic method using various shearing forces generated by the medium flow. The force of adhesion of the LL2 cells is about 10(-12) N to 10(-11) N with statistically significant differences between various sublines: it is the highest for LL2-AAA cells, intermediate for LL2 cells and the smallest for LL2-8 cells. In another series of experiments the distribution of the number of single cells and multicellular aggregates in the suspensions of LL2 cells together with the effect of gravitational sedimentation were examined. When the LL2 cells are incubated in 37 degrees C they display active motile behaviour which consists in forming cell-surface extensions of various shapes and duration (from a few seconds to several minutes and more). The displacement of the whole cells (locomotion) has not been observed. The results of the study on adhesion and motility of LL2 cells are discussed from the point of view of their metastatic properties, cell-membrane structure and mechanisms of malignant invasion.

Animals↗
PubMed1988

Model structure of a fragment of biological knowledge (cell motility).

The aim of the study is to contribute to a better understanding of some aspects of the structure of biological knowledge and to make clearer to what extent the methods of reasoning may be useful in this field when only qualitative information is available. A fragment of biological knowledge (theory of cell motility) is analysed from the logicomethodological point of view as a coherent system and the possibility of its formal representation is investigated. The analysis is based on distinguishing the main objects and their features (attributes) of which a given piece of knowledge is composed and on the values which these features may display. The features are interconnected by relations (in which various number of arguments appear) and these relations constitute the main (general, higher level) laws of a given fragment of knowledge (theory). Values of attributes are also mutually connected and these relations correspond to the detailed (lower level) laws. A computer system (in which Prolog language was used) enables to perform inference operations of progressive as well as regressive type. The main categories of reasoning procedures are described and illustrated by examples, namely a) search for conclusions which may be confronted with the actual knowledge in order to verify the system as a whole, b) formation of working hypotheses in the process of their empirical verification and explanation of facts and laws. The problem of development and modification of the system is also discussed.

Cell Movement↗
PubMed1988

Adhesion and locomotion of granulocytes under flow conditions.

The aim of this study was to compare the strength of the surface adhesion of migrating human granulocytes and the main parameters of their locomotion under the influence of various external forces. The strength of adhesion of granulocytes moving in a quiescent medium was studied by detaching them gravitationally from the plane surface situated above them. In these conditions the force of adhesion is of the same order of magnitude as the gravitational force operating upon the cells. The locomotion characteristics of granulocytes migrating on a surface below them are similar to those observed during their movement on a surface above. When the granulocytes migrate with the medium flowing past them, they are not detached from the surface even by relatively great shearing forces (10 and 100 times greater in comparison with the gravitational force) and the locomotion parameters are only slightly modified. The results show that granulocytes are able to migrate in a similar manner when they are subjected to various external forces.

Cell Adhesion↗
PubMed1986

Poiseuille flow method for measuring cell-to-cell adhesion.

A theoretical description of the cell aggregation process in the Poisseuille flow is presented, the capture efficiency being used as the measure of cell adhesiveness. The value of this coefficient is determined both for nonspecific and specific (i.e., mediated by molecules) cell-to-cell interactions. Regarding the cell adhesion described by the DLVO theory, it is possible to determine the conditions under which cell adhesion is maximal. The dependence of capture efficiency on parameters such as shear rate, size of cell, surface potential of cell, the Hamaker constant of substances constituting the cell membrane, and composition of the medium is analyzed. In the case of specific cell adhesion during flow, the change of suspension concentration is related to the number of free and occupied receptor sites, the diffusion constant of the receptors in the cell membrane, the force of a single bond, and the conditions of flow. It is possible to determine the diffusion constant from cell aggregation measurement when the force of a single bond and the number of free and occupied receptor sites are known.

Cell Adhesion↗
PubMed1986

Specific cell-to-cell adhesion under flow conditions.

An experimental method of measuring intercellular adhesion based on cell interactions in Poiseuille flow is presented. Hydrodynamic conditions of suspension flow, concentration of the suspension, and the size of cells allows determination of the capture efficiency, which is a measure of cell adhesiveness. The measurements of cell aggregation were performed with thymus cells and lectin from Ricinus communis. On the ground of theoretical description of the process of cell aggregation, it was possible to estimate the diffusion constant of the receptors in the cell membrane, which is equal to 5.6 X 10(-11) cm2/s. This value is in good agreement with the results of direct measurements of the diffusion constant of the lectin receptor. In the case of formalin-treated cells, the diffusion constant of the lectin receptors is equal to 6.8 X 10(-12) cm2/s. The total number of the receptor sites on the thymus cell surface for lectin R. communis and the affinity constant were also estimated.

Animals↗
PubMed1979

[Characteristics of the erythrocyte movement in the vicinity of the flow chamber wall].

In perfusion experiments it was demonstrated that in close vicinity to the lower wall of a microscopic flow chamber a fraction of red blood cells do not exhibit the typical rotational motion, but flow in a steady position with the flat surface to the wall. The velocity of these cells is significantly smaller than that of the fluid in the same region of the channel. It is suggested that the phenomenon is caused by the action of adhesion-type forces operating between the flowing cells and the channel wall.

Adhesiveness↗
PubMed1979

The passage of lymphatic leukemia L1210 cells injected into glass bead labyrinth: their flow and retention.

Leukemia L1210 cells and normal lymphocytes were injected into the glass bead packing perfused with a medium containing serum proteins in concentration sufficient to greatly reduce the surface adhesion. The passage of radioactively labeled cells introduced as a concentrated suspension, was studied by the analysis of transit-dilution curves. It was demonstrated that a fraction of cells was retained in the labyrinth; other parameters characterizing the cell flow were similar to those of the medium. The mechanism of the arrest of cells is discussed: it is related to geometrical features of the labyrinth and the hydrodynamic forces influencing the cell surface interactions. Intense washing of the glass bead column results in the release of only a minor fraction of cells which were previously arrested. When the L1210 cells which have passed through the labyrinth without being trapped are reinjected into another glass bead layer, their retention is similar to that observed after the first injection; it appears, therefore, that the L1210 cells are uniform as concerns the properties which are important for surface interactions under flow conditions.

Animals↗