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Biomedical subjects

F Doljanski

Publications and source records attributed to F Doljanski.

34 records · Page 2Linked to original sources
PubMed1974

Cellular immunity against Rous sarcomas of chickens. Preferential reactivity against autochthonous target cells as determined by lymphocyte adherence and cytotoxicity tests in vitro.

Spleen cells from random-bred chickens bearing Rous sarcomas were commonly more reactive against the neoplastic target cells in autochthonous than in allogenic interactions in vitro. This difference was observed both in cytotoxic assays ((51)Cr release from labeled target cells) and in an immunoadherence test measuring attachment of (51)Cr-labeled splenocytes to Rous sarcoma cells. Specific splenocyte reactivity was not observed with normal embryonic chicken fibroblasts, 3T3 cells, or embryonic mouse C3H fibroblasts. The immunoadherence technique required only 2 hr to perform, and revealed a more consistent superiority of autochthonous recognition of Rous sarcoma cells than the cytotoxicity assay. Experiments in which both procedures were used simultaneously with identical cell populations yielded similar results, indicating that splenocyte adherence may be a precursor of and/or concomitant to target cell damage and that individual-specific tumor antigencity may play a part in cellular immunity against Rous sarcomas.

Animals↗
PubMed1972

Electrical sizing of particles in suspensions. 3. Rigid spheroids and red blood cells.

The processes involved during the passage of a suspended particle through a small cylindrical orifice across which exists an electric field are investigated experimentally for an approximate prolate spheroid in the form of two tangent, rigid spheres (ragweed pollen particles) and for fresh, human red blood cells. Oscillograms of current pulses produced by both types of particles are presented and discussed in terms of particle shape and orientation and the effects of the hydrodynamic field. It is concluded that all the particles enter the orifice with their major axes aligned parallel to the orifice axis (electric field), but that during their passage some are rotated by the hydrodynamic field. Cells with their equatorial plane perpendicular to a radius of the orifice change their orientation with respect to the electric field as they are rotated, the others do not; only in the former case is there any deformation. It is shown that the bimodal or skewed size distributions can be explained on this basis, and that size (shape factor x volume) is actually a normally distributed variable (P > 95%). The average size of samples from 10 healthy adults was found to be 102.7 mu(3) with a coefficient of variation of 1.8%. For a volume of 87 mu(3), this corresponds to a shape factor of 1.18, an axial ratio (assuming a perfect oblate spheroid) of 0.26, and an equivalent major axis of 8.6 mu. The effect of high electric fields on red cell size distributions is mentioned.

Adult↗
PubMed1969

Electrical sizing of particles in suspensions. I. Theory.

The processes involved during the passage of a suspended particle through a small cylindrical orifice across which exists an electric field are considered in detail. Expressions are derived for the resulting change in current in terms of the ratios of particle to orifice volume and particle to suspending fluid resistivity, and particle shape. Graphs are presented of the electric field and of the fluid velocity as functions of position within the orifice, and of the shape factor of spheroids as a function of their axial ratio and orientation in the electric field. The effects of the electric and hydrodynamic fields on the orientation of nonspherical particles and on the deformation of nonrigid spheres is treated, and the migration of particles towards the orifice axis is discussed. Oscillograms of current pulses produced by rigid, nonconducting spheres in various orifices are shown and compared with the theoretical predictions.

Biophysical Phenomena↗
PubMed1969

Electrical sizing of particles in suspensions. II. Experiments with rigid spheres.

Experimental verification is provided for the theoretical expressions (see preceding article, I. Theory) describing the electrical processes that take place during the passage of an aqueous suspension of rigid, nonconducting spheres (ragweed pollen) through an orifice across which there exists an electrical field, for a large range of orifice dimensions; the instrumentation developed is considered in some detail. The effective length of an orifice as deduced from conductivity measurements is shown to be essentially the same as that predicted theoretically. Absolute volume distributions are presented of a suspension of polystyrene latex spheres as determined electrically (mean 11.17 mu(3), c. v. 4.2%) and with an electron microscope (mean 11.01 mu(3), c. v. 4.1%). Conflicting experimental results reported in the literature are discussed.

Biophysical Phenomena↗