Interactive computer-video modules for health sciences education.

Advances in electronic image recording and computer technology have resulted in a remarkable increase in the power and flexibility of interactive computer-video teaching systems. The University of Washington Health Science Videodisc Development Group first demonstrated a laser videodisc controlled by a remote central computer in 1980. Even this rudimentary unit highlighted basic medical informatics principles including: rapid accessibility; a "generic" or multi-purposed format; ease of computer control; and large collections of valid, rigorously reviewed images.

[Calculation of direct standard costs in the evaluation of new technologies: application to the treatment of acute myeloblastic leukemias].

Financial incidence of new technology can be approached through the utilization of "direct standard cost". This method allows actualization of prices and permits the integration of new procedures. It is applied to acute non lymphoblastic leukemia.

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.

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.

[A new technic for the study of the physiology of erythrocytes: measurement of their deformability as a function of osmolarity. Results obtained by an automatized Ektacytometer in normal blood and in various hemolytic anemias].

A system has been added to the Ektacytometer to allow continuous variation and measurement of the osmolarity of the suspension medium from 50 to 500 mosm kg-1 permitting the analysis of erythrocyte deformability over a range varying from hypo- to hypertonicity. The curves are obtained automatically in 7 min. from a blood sample of 150 microliters.

Quantitation of red cell deformability during progressive deoxygenation and oxygenation in sickling disorders (the use of an automated Ektacytometer).

1. The Ektacytometer, which allows quantitation of cell fluidity under known environmental conditions, has been recently modified so that cells can be exposed to any desired O2 tension during shear stress. 2.

Sickle cell shape and structure: images and concepts (1840-1980).

I. First observations of "crescentic particles" in animals. II.

Discovery of the red blood cell with notes on priorities and credits of discoveries, past, present and future.

A review of the earliest publications and letters of the scientists who have received credit for the first description of red cells illustrates the philosophical and practical difficulties of assigning priorities for discoveries. A knowledge of the scientific and cultural ambience of the day, of reports of scientific contemporaries or predecessors, both partisans and adversaries, and other background information illustrates how the consensus in crediting the discovery originated. However, the broader question remains: what are the proper criteria for assigning priority of discovery, yesterday, today and tomorrow?

New optical technique for measuring erythrocyte deformability with the ektacytometer.

The laser light scattered by erythrocytes subjected to a well-defined shear stess can be analyzed with the ektacytometer to obtain information regarding the changes in cell shape due to fluid shear. We describe an optical technique whereby an observed quantitative output derived from a mesurement of light intensity through a spatial filter is related to the change in cellular dimensions that were previously observed under similar fluid-shear conditions by use of microscopy and a cone-plate viscometer (rheoscope). We also present the predictions of a theoretical model (of the ektacytometer) based on approximations of light-scattering theory developed for nonspherical particles, and give preliminary results for the accuracy and sensitivity of this measurement of erythrocyte deformability.

Automated ektacytometry: a new method of measuring red cell deformability and red cell indices.

The automated ektacytometer enables rapid measurement of red cell deformability by using small aliquots of blood (25 microliter). By subjecting red cells to varying shear stress in suspending media of different osmolalities, one can identify separate contributions of membrane viscoelastic properties, internal viscosity, and surface area-to-volume ratio to overall cellular deformability. The influence of drugs on red cell deformability can also be investigated.

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.

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.

[Detection of fibrillary bodies in human and experimental leukemias by polarizing 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.

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.