PubMed Health⌕ Search

Biomedical subjects

M Bessis

Publications and source records attributed to M Bessis.

15 recordsLinked to original sources
PubMed1978

Fibrillar bodies in leukemic cells revealed by polarization microscopy.

An optical polarizing microscope with a good coefficient of extinction permits the visualization of the cytoplasmic fibrillar body in living preparations and smears of leukemic cells (human leukemias and the L 5222 experimental leukemia). These inclusions are not visible by phase contrast microscopy nor in fixed and stained smears. The detection in living cells of fibrillar bodies makes it possible to study directly the conditions for their formation and their reaction to the effect of certain drugs.

Actin Cytoskeleton↗
PubMed1978

Erythropoiesis: comparison of in vivo and in vitro amplification.

1. Amplification is defined as the phase of erythropoiesis that includes all cell divisions of the recognizable erythron. 2. In vivo, amplification always takes place surrounding a central histiocyte (erythroblastic island). It is made up of four to five successive synchronous divisions. 3. In vitro, complete maturation and amplification of erythropoietic cells can be obtained without apparent association with a central histiocyte. 4. The functional significance of the 'erythroblastic island' and disorders of amplification are discussed in relation to clinical disorders of erythropoiesis.

Animals↗
PubMed1978

On the proper use of the Soret band for hemoglobin detection in erythrocytic cells.

Intracellular hemoglobin detection by light microscopy in the Soret band (414nm) is a sensitive means of correlating morphology and biochemical function in studies of erythrpoiesis. Correct application of the technique requires a light source with strong emission in the near ultra-violet, a filter with a pass-band at 414nm, a preparation of living cells or an unfixed smear, and a receiver that is sensitive to the Soret wavelength. The human eye is very insensitive to light at 414nm and quite sensitive to stray green light: it is consequently much inferior to a black and white television or camera film for viewing a Soret image. The appearance of hemoglobin during maturation of erythroid cells in human bone marrow can be detected with greater sensitivity by this method than by a peroxidase-benzidine stain and it is the only method applicable to living cells.

Animals↗
PubMed1977

[Erythrocyte form and deformability for normal blood and some hereditary hemolytic anemias (author's transl)].

1. A brief review of recent results on the structure of erythrocyte membranes and the experimental deformation of red blood cells. 2. A discussion of factors playing a role in the deformability: a) Influence of shape, consisting of the cell surface to volume ration. b) Internal factors, depending mainly on the viscosity of the hemoglobin).c) Degree of flexibility of the membrane. 3. A brief summary of techniques to measure the deformability with emphasis on the method of viscodiffractometry (ektacytometer). 4. Results given by examination in the ektacytometer of hereditary spherocytosis and sickle cell anemia.

Anemia, Hemolytic, Congenital↗
PubMed1976

[Deformation and orientation of sickle erythrocytes submitted to shearing forces].

Blood from patients with homozygous sickle cell anemia gives a "cross shaped" diffraction pattern, when submitted to shear stresses in the Ektacytometer. This pattern, which seems to be specific to these cells, is due to the existence of two populations of elliptical cells: one population (normal, deformable cells) aligned parallel to the direction of the flow, and the other (abnormal, rigid cells) perpendicular to the direction of the flow.

Anemia, Sickle Cell↗
PubMed1975

[Red cell deformability, importance of its measurement in clinical medicine].

A new device for evaluation of red cell deformability is described. A population of red cells dispersed as a monolayer are subjected to a well defined fluid shear stress in a concentric cylinder viscometer. Red cell deformation is a function of rotational speed and red cell elongation is measured in a continuous manner using a diffraction method. Preliminary results in clinical medicine are presented.

Erythrocytes↗
PubMedDate not supplied

Origin of stress macroreticulocytes from macronormoblasts.

Stress erythropoiesis was induced in rats and guinea-pigs by graded amounts of bleeding and phenyl-hydrazine administration. Hemoglobin and DNA content was measured by microspectrophometry of single erythroblasts in the process of nuclear extrusion. DNA content was always 2 C. Hemoglobin content was in all cases superior to the normal value, occasionally reaching a value of almost twice normal.

Animals↗
PubMedDate not supplied

Necrotaxis: a scanning and transmission electron microscopy study.

This paper describes an easy method to determine a "necrotactic rosette forming index (NRI) of leucocytes" after destruction of a red cell by a laser beam. Among the drugs tested, only cytochalasin B (0.5 mug/ml) is found to significantly lower NRI. The lectins PHA and CON-A did not have any effect on the NRI. Patients with infections are found to have increased NRI. Transmission and scanning electron microscopy have permitted the study of fine structurale details of the entire phenomenon.

Animals↗
PubMedDate not supplied

[In vitro studies on amplification of rat erythropoiesis (author's transl)].

From rat bone marrow in which erythropoiesis has been depressed (by suppression of erythropoietin production), liquid culture has yielded a predominantly synchronous amplification of erythroblast development. Groups of 2, 4, 8, 16 and 32 erythrolbasts are observed at 9-15 hour intervals in successive stages of maturation, similar (by their staining characteristics and nuclear size) to that seen in vivo.

Animals↗