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Biomedical subjects

A de Boisfleury-Chevance

Publications and source records attributed to A de Boisfleury-Chevance.

7 recordsLinked to original sources
PubMed1993

Visualization of intracellular calcium during necrotaxis.

Granulocytes are known to exhibit positive chemotaxis towards erythrocytes destroyed by laser irradiation (necrotaxis). A computerized method for visualizing intracellular calcium concentration in granulocytes during necrotaxis has been developed. Successive bursts of fluorescence were observed: 1 degree) about 10 s after the creation of the necrotactic source; 2 degrees) when the granulocyte touched the target.

Analog-Digital Conversion↗
PubMed1991

Cryopreserved cytoplasts from human polymorphonuclear leukocytes (cytokineplasts) are chemotactic at speeds comparable to those of fresh intact cells.

Cytokineplasts (CKP) are granule-poor cytoplasts from human polymorphonuclear leukocytes (PMN) that retain motile function, even (unlike the parent PMN) after cryopreservation. Employing time-lapse videomicroscopy, we examined the chemotactic properties of CKP after cryopreservation toward erythrocytes lysed by laser microirradiation. Paths of locomotion were plotted for six CKP in the field, and velocities were calculated at 10-sec intervals. Mean velocities of the six fragments, ranging from 9.3 to 20.8 microns/min, are of the order of fresh, intact PMN, the fastest of locomoting cells.

Chemotaxis, Leukocyte↗
PubMed1989

Locomotion of white blood cells: a biophysical analysis.

We determined some biophysical properties of human granulocytes, monocytes, and lymphocytes in respect to their locomotion. Granulocytes were exposed to plasma and were allowed to crawl on uncoated or glycol methacrylate coated glass plates. Monocytes did not migrate on uncoated glass, but did so on glycol methacrylated glass. Lymphocytes did not move on glass or glycol methacrylated glass, but moved on plexiglas coverslips. Granulocytes and monocytes showed a pronounced, directed movement towards a lysed erythrocyte (necrotaxis), lymphocytes showed no necrotactic response. The information collected by the granulocytes and monocytes in the necrotactic gradient was between 1 and 2 bits. This small amount of information indicated that the cellular decision in favor of a new direction of migration is based on a mechanism involving instability. We showed that the necrotactic response of granulocytes and monocytes is the product of the chemokinetic activity and the polar order parameter (= McCutcheon index) indicating that the cellular decision for a new direction of migration is independent of the speed of the cell movement. The movement of monocytes can be characterized in a similar way to that of granulocytes: the angle of deviation from a straight line path is nearly a fixed value (+/- 35 degrees). Lymphocytes stay in a restricted area after straight line movement. Particular attention was focused on cellular properties involved in locomotion. The characteristic time of the internal clock controlling the locomotion was 0.9 minutes for granulocytes and 2 minutes for monocytes. We were not able to determine the characteristic time of lymphocytes. We were able to determine the internal program responsible for the change in direction of movement. The directional memory time for granulocytes was 0.9 minutes. Monocytes had two directional memory times, short (2 minutes) and long (greater than 18 minutes). Lymphocytes had a very short directional memory time of 40 seconds. The distribution of the track velocities of migrating granulocytes and monocytes was described by bell shaped curves indicating homogeneous populations of cells. The distribution for lymphocytes had two maxima.

Biophysical Phenomena↗
PubMed1988

Galvanotaxis of human granulocytes. Dose-response curve.

The galvanotactic response of human granulocytes was investigated theoretically and experimentally. The basic results are: (i) The granulocytes move towards the anode. (ii) The directed movement has been quantified by two different polar order parameters--the McCutcheon index and the average of cos phi. (iii) The polar order parameters are a function of the applied electric field (= dose-response curve). (iv) The inverse of the galvanotactic constant of migrating cells (analogous to the Michaelis-Menten constant) has a value of -0.2 +/- 0.03 V/mm. (v) The galvanotactic response of granulocytes is a non-cooperative process with a cooperativity coefficient of 1 +/- 0.2. (vi) The galvanotactic constant is a function of pH. (vii) The protein essential for the galvanotactic response is very likely a G-protein.

Cell Movement↗
PubMed1984

Facts and speculation about necrotaxis (chemotaxis toward a dying cell).

The name "necrotaxis" has been given to a special type of chemotaxis in which granulocytes and monocytes are attracted to cells in the process of dying. Microirradiation devices (conventional UV and laser) have been used to destroy a target cell. Immediately, leukocytes (neutrophils and monocytes) can be seen to advance towards the damaged cell and to engulf it. Hemoglobin and albumin coagulated in the microbeam are equally necrotactic. The presence of plasma does not seem necessary, as the phenomenon also occurs in a saline environment. The neutrophil nucleus is not necessary for necrotaxis, anucleated cytoplasmic fragments are capable of directionality, rosette formation around the dead cell and phagocytosis. Three specific points are briefly discussed: -- the nature of necrotactic substances -- the recognition mechanism of damaged cells and molecules -- the eventual role of necrotaxis in vivo.

Animals↗
PubMed1983

Heat as a probe of centrosomal function: a phase-contrast and immunofluorescent study of human blood monocytes.

In normal human blood monocytes, the nucleus is indented by the centrosome, which excludes the phase-dense granules that are spread throughout the cytoplasm. Within this paranuclear region, the paired centrioles are marked by immunofluorescent staining with an anti-centrosome antibody directed against the pericentriolar osmiophilic material that appears to serve as microtubule-organizing centers (MTOCs). Congruent paired structures are seen in phase-contrast. Following heat treatment (45 degrees C, 9 min), granules are retracted about a less indented nucleus, and anti-centrosome immunofluorescence is absent or very weak, even though paired centrosomal structures remain at least as phase-dense as in controls. Immunofluorescent staining with antimicrotubule antibody is also essentially lost following heat treatment. These findings are consistent with a heat-induced lesion in the pericentriolar osmiophilic material, which may prove generally useful as a probe of centrosomal function.

Centrioles↗